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ffs_softdep.c

/*-
 * Copyright 1998, 2000 Marshall Kirk McKusick. All Rights Reserved.
 *
 * The soft updates code is derived from the appendix of a University
 * of Michigan technical report (Gregory R. Ganger and Yale N. Patt,
 * "Soft Updates: A Solution to the Metadata Update Problem in File
 * Systems", CSE-TR-254-95, August 1995).
 *
 * Further information about soft updates can be obtained from:
 *
 *    Marshall Kirk McKusick        http://www.mckusick.com/softdep/
 *    1614 Oxford Street            mckusick@mckusick.com
 *    Berkeley, CA 94709-1608       +1-510-843-9542
 *    USA
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY MARSHALL KIRK MCKUSICK ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL MARSHALL KIRK MCKUSICK BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *    from: @(#)ffs_softdep.c 9.59 (McKusick) 6/21/00
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/ufs/ffs/ffs_softdep.c,v 1.211 2007/06/22 13:22:36 kib Exp $");

/*
 * For now we want the safety net that the DIAGNOSTIC and DEBUG flags provide.
 */
#ifndef DIAGNOSTIC
#define DIAGNOSTIC
#endif
#ifndef DEBUG
#define DEBUG
#endif

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/kdb.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/stat.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/vnode.h>
#include <sys/conf.h>
#include <ufs/ufs/dir.h>
#include <ufs/ufs/extattr.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufsmount.h>
#include <ufs/ffs/fs.h>
#include <ufs/ffs/softdep.h>
#include <ufs/ffs/ffs_extern.h>
#include <ufs/ufs/ufs_extern.h>

#include <vm/vm.h>

#include "opt_ffs.h"
#include "opt_quota.h"

#ifndef SOFTUPDATES

int
softdep_flushfiles(oldmnt, flags, td)
      struct mount *oldmnt;
      int flags;
      struct thread *td;
{

      panic("softdep_flushfiles called");
}

int
softdep_mount(devvp, mp, fs, cred)
      struct vnode *devvp;
      struct mount *mp;
      struct fs *fs;
      struct ucred *cred;
{

      return (0);
}

void 
softdep_initialize()
{

      return;
}

void
softdep_uninitialize()
{

      return;
}

void
softdep_setup_inomapdep(bp, ip, newinum)
      struct buf *bp;
      struct inode *ip;
      ino_t newinum;
{

      panic("softdep_setup_inomapdep called");
}

void
softdep_setup_blkmapdep(bp, mp, newblkno)
      struct buf *bp;
      struct mount *mp;
      ufs2_daddr_t newblkno;
{

      panic("softdep_setup_blkmapdep called");
}

void 
softdep_setup_allocdirect(ip, lbn, newblkno, oldblkno, newsize, oldsize, bp)
      struct inode *ip;
      ufs_lbn_t lbn;
      ufs2_daddr_t newblkno;
      ufs2_daddr_t oldblkno;
      long newsize;
      long oldsize;
      struct buf *bp;
{
      
      panic("softdep_setup_allocdirect called");
}

void 
softdep_setup_allocext(ip, lbn, newblkno, oldblkno, newsize, oldsize, bp)
      struct inode *ip;
      ufs_lbn_t lbn;
      ufs2_daddr_t newblkno;
      ufs2_daddr_t oldblkno;
      long newsize;
      long oldsize;
      struct buf *bp;
{
      
      panic("softdep_setup_allocext called");
}

void
softdep_setup_allocindir_page(ip, lbn, bp, ptrno, newblkno, oldblkno, nbp)
      struct inode *ip;
      ufs_lbn_t lbn;
      struct buf *bp;
      int ptrno;
      ufs2_daddr_t newblkno;
      ufs2_daddr_t oldblkno;
      struct buf *nbp;
{

      panic("softdep_setup_allocindir_page called");
}

void
softdep_setup_allocindir_meta(nbp, ip, bp, ptrno, newblkno)
      struct buf *nbp;
      struct inode *ip;
      struct buf *bp;
      int ptrno;
      ufs2_daddr_t newblkno;
{

      panic("softdep_setup_allocindir_meta called");
}

void
softdep_setup_freeblocks(ip, length, flags)
      struct inode *ip;
      off_t length;
      int flags;
{
      
      panic("softdep_setup_freeblocks called");
}

void
softdep_freefile(pvp, ino, mode)
            struct vnode *pvp;
            ino_t ino;
            int mode;
{

      panic("softdep_freefile called");
}

int 
softdep_setup_directory_add(bp, dp, diroffset, newinum, newdirbp, isnewblk)
      struct buf *bp;
      struct inode *dp;
      off_t diroffset;
      ino_t newinum;
      struct buf *newdirbp;
      int isnewblk;
{

      panic("softdep_setup_directory_add called");
}

void 
softdep_change_directoryentry_offset(dp, base, oldloc, newloc, entrysize)
      struct inode *dp;
      caddr_t base;
      caddr_t oldloc;
      caddr_t newloc;
      int entrysize;
{

      panic("softdep_change_directoryentry_offset called");
}

void 
softdep_setup_remove(bp, dp, ip, isrmdir)
      struct buf *bp;
      struct inode *dp;
      struct inode *ip;
      int isrmdir;
{
      
      panic("softdep_setup_remove called");
}

void 
softdep_setup_directory_change(bp, dp, ip, newinum, isrmdir)
      struct buf *bp;
      struct inode *dp;
      struct inode *ip;
      ino_t newinum;
      int isrmdir;
{

      panic("softdep_setup_directory_change called");
}

void
softdep_change_linkcnt(ip)
      struct inode *ip;
{

      panic("softdep_change_linkcnt called");
}

void 
softdep_load_inodeblock(ip)
      struct inode *ip;
{

      panic("softdep_load_inodeblock called");
}

void 
softdep_update_inodeblock(ip, bp, waitfor)
      struct inode *ip;
      struct buf *bp;
      int waitfor;
{

      panic("softdep_update_inodeblock called");
}

int
softdep_fsync(vp)
      struct vnode *vp; /* the "in_core" copy of the inode */
{

      return (0);
}

void
softdep_fsync_mountdev(vp)
      struct vnode *vp;
{

      return;
}

int
softdep_flushworklist(oldmnt, countp, td)
      struct mount *oldmnt;
      int *countp;
      struct thread *td;
{

      *countp = 0;
      return (0);
}

int
softdep_sync_metadata(struct vnode *vp)
{

      return (0);
}

int
softdep_slowdown(vp)
      struct vnode *vp;
{

      panic("softdep_slowdown called");
}

void
softdep_releasefile(ip)
      struct inode *ip; /* inode with the zero effective link count */
{

      panic("softdep_releasefile called");
}

int
softdep_request_cleanup(fs, vp)
      struct fs *fs;
      struct vnode *vp;
{

      return (0);
}

int
softdep_check_suspend(struct mount *mp,
                  struct vnode *devvp,
                  int softdep_deps,
                  int softdep_accdeps,
                  int secondary_writes,
                  int secondary_accwrites)
{
      struct bufobj *bo;
      int error;
      
      (void) softdep_deps,
      (void) softdep_accdeps;

      ASSERT_VI_LOCKED(devvp, "softdep_check_suspend");
      bo = &devvp->v_bufobj;

      for (;;) {
            if (!MNT_ITRYLOCK(mp)) {
                  VI_UNLOCK(devvp);
                  MNT_ILOCK(mp);
                  MNT_IUNLOCK(mp);
                  VI_LOCK(devvp);
                  continue;
            }
            if (mp->mnt_secondary_writes != 0) {
                  VI_UNLOCK(devvp);
                  msleep(&mp->mnt_secondary_writes,
                         MNT_MTX(mp),
                         (PUSER - 1) | PDROP, "secwr", 0);
                  VI_LOCK(devvp);
                  continue;
            }
            break;
      }

      /*
       * Reasons for needing more work before suspend:
       * - Dirty buffers on devvp.
       * - Secondary writes occurred after start of vnode sync loop
       */
      error = 0;
      if (bo->bo_numoutput > 0 ||
          bo->bo_dirty.bv_cnt > 0 ||
          secondary_writes != 0 ||
          mp->mnt_secondary_writes != 0 ||
          secondary_accwrites != mp->mnt_secondary_accwrites)
            error = EAGAIN;
      VI_UNLOCK(devvp);
      return (error);
}

void
softdep_get_depcounts(struct mount *mp,
                  int *softdepactivep,
                  int *softdepactiveaccp)
{
      (void) mp;
      *softdepactivep = 0;
      *softdepactiveaccp = 0;
}

#else
/*
 * These definitions need to be adapted to the system to which
 * this file is being ported.
 */
/*
 * malloc types defined for the softdep system.
 */
static MALLOC_DEFINE(M_PAGEDEP, "pagedep","File page dependencies");
static MALLOC_DEFINE(M_INODEDEP, "inodedep","Inode dependencies");
static MALLOC_DEFINE(M_NEWBLK, "newblk","New block allocation");
static MALLOC_DEFINE(M_BMSAFEMAP, "bmsafemap","Block or frag allocated from cyl group map");
static MALLOC_DEFINE(M_ALLOCDIRECT, "allocdirect","Block or frag dependency for an inode");
static MALLOC_DEFINE(M_INDIRDEP, "indirdep","Indirect block dependencies");
static MALLOC_DEFINE(M_ALLOCINDIR, "allocindir","Block dependency for an indirect block");
static MALLOC_DEFINE(M_FREEFRAG, "freefrag","Previously used frag for an inode");
static MALLOC_DEFINE(M_FREEBLKS, "freeblks","Blocks freed from an inode");
static MALLOC_DEFINE(M_FREEFILE, "freefile","Inode deallocated");
static MALLOC_DEFINE(M_DIRADD, "diradd","New directory entry");
static MALLOC_DEFINE(M_MKDIR, "mkdir","New directory");
static MALLOC_DEFINE(M_DIRREM, "dirrem","Directory entry deleted");
static MALLOC_DEFINE(M_NEWDIRBLK, "newdirblk","Unclaimed new directory block");
static MALLOC_DEFINE(M_SAVEDINO, "savedino","Saved inodes");

#define M_SOFTDEP_FLAGS (M_WAITOK | M_USE_RESERVE)

#define     D_PAGEDEP   0
#define     D_INODEDEP  1
#define     D_NEWBLK    2
#define     D_BMSAFEMAP 3
#define     D_ALLOCDIRECT     4
#define     D_INDIRDEP  5
#define     D_ALLOCINDIR      6
#define     D_FREEFRAG  7
#define     D_FREEBLKS  8
#define     D_FREEFILE  9
#define     D_DIRADD    10
#define     D_MKDIR           11
#define     D_DIRREM    12
#define     D_NEWDIRBLK 13
#define     D_LAST            D_NEWDIRBLK

/* 
 * translate from workitem type to memory type
 * MUST match the defines above, such that memtype[D_XXX] == M_XXX
 */
static struct malloc_type *memtype[] = {
      M_PAGEDEP,
      M_INODEDEP,
      M_NEWBLK,
      M_BMSAFEMAP,
      M_ALLOCDIRECT,
      M_INDIRDEP,
      M_ALLOCINDIR,
      M_FREEFRAG,
      M_FREEBLKS,
      M_FREEFILE,
      M_DIRADD,
      M_MKDIR,
      M_DIRREM,
      M_NEWDIRBLK
};

#define DtoM(type) (memtype[type])

/*
 * Names of malloc types.
 */
#define TYPENAME(type)  \
      ((unsigned)(type) < D_LAST ? memtype[type]->ks_shortdesc : "???")
/*
 * End system adaptation definitions.
 */

/*
 * Forward declarations.
 */
struct inodedep_hashhead;
struct newblk_hashhead;
struct pagedep_hashhead;

/*
 * Internal function prototypes.
 */
static      void softdep_error(char *, int);
static      void drain_output(struct vnode *);
static      struct buf *getdirtybuf(struct buf *, struct mtx *, int);
static      void clear_remove(struct thread *);
static      void clear_inodedeps(struct thread *);
static      int flush_pagedep_deps(struct vnode *, struct mount *,
          struct diraddhd *);
static      int flush_inodedep_deps(struct mount *, ino_t);
static      int flush_deplist(struct allocdirectlst *, int, int *);
static      int handle_written_filepage(struct pagedep *, struct buf *);
static  void diradd_inode_written(struct diradd *, struct inodedep *);
static      int handle_written_inodeblock(struct inodedep *, struct buf *);
static      void handle_allocdirect_partdone(struct allocdirect *);
static      void handle_allocindir_partdone(struct allocindir *);
static      void initiate_write_filepage(struct pagedep *, struct buf *);
static      void handle_written_mkdir(struct mkdir *, int);
static      void initiate_write_inodeblock_ufs1(struct inodedep *, struct buf *);
static      void initiate_write_inodeblock_ufs2(struct inodedep *, struct buf *);
static      void handle_workitem_freefile(struct freefile *);
static      void handle_workitem_remove(struct dirrem *, struct vnode *);
static      struct dirrem *newdirrem(struct buf *, struct inode *,
          struct inode *, int, struct dirrem **);
static      void free_diradd(struct diradd *);
static      void free_allocindir(struct allocindir *, struct inodedep *);
static      void free_newdirblk(struct newdirblk *);
static      int indir_trunc(struct freeblks *, ufs2_daddr_t, int, ufs_lbn_t,
          ufs2_daddr_t *);
static      void deallocate_dependencies(struct buf *, struct inodedep *);
static      void free_allocdirect(struct allocdirectlst *,
          struct allocdirect *, int);
static      int check_inode_unwritten(struct inodedep *);
static      int free_inodedep(struct inodedep *);
static      void handle_workitem_freeblocks(struct freeblks *, int);
static      void merge_inode_lists(struct allocdirectlst *,struct allocdirectlst *);
static      void setup_allocindir_phase2(struct buf *, struct inode *,
          struct allocindir *);
static      struct allocindir *newallocindir(struct inode *, int, ufs2_daddr_t,
          ufs2_daddr_t);
static      void handle_workitem_freefrag(struct freefrag *);
static      struct freefrag *newfreefrag(struct inode *, ufs2_daddr_t, long);
static      void allocdirect_merge(struct allocdirectlst *,
          struct allocdirect *, struct allocdirect *);
static      struct bmsafemap *bmsafemap_lookup(struct mount *, struct buf *);
static      int newblk_find(struct newblk_hashhead *, struct fs *, ufs2_daddr_t,
          struct newblk **);
static      int newblk_lookup(struct fs *, ufs2_daddr_t, int, struct newblk **);
static      int inodedep_find(struct inodedep_hashhead *, struct fs *, ino_t,
          struct inodedep **);
static      int inodedep_lookup(struct mount *, ino_t, int, struct inodedep **);
static      int pagedep_lookup(struct inode *, ufs_lbn_t, int, struct pagedep **);
static      int pagedep_find(struct pagedep_hashhead *, ino_t, ufs_lbn_t,
          struct mount *mp, int, struct pagedep **);
static      void pause_timer(void *);
static      int request_cleanup(struct mount *, int);
static      int process_worklist_item(struct mount *, int);
static      void add_to_worklist(struct worklist *);
static      void softdep_flush(void);
static      int softdep_speedup(void);

/*
 * Exported softdep operations.
 */
static      void softdep_disk_io_initiation(struct buf *);
static      void softdep_disk_write_complete(struct buf *);
static      void softdep_deallocate_dependencies(struct buf *);
static      int softdep_count_dependencies(struct buf *bp, int);

static struct mtx lk;
MTX_SYSINIT(softdep_lock, &lk, "Softdep Lock", MTX_DEF);

#define TRY_ACQUIRE_LOCK(lk)        mtx_trylock(lk)
#define ACQUIRE_LOCK(lk)            mtx_lock(lk)
#define FREE_LOCK(lk)               mtx_unlock(lk)

/*
 * Worklist queue management.
 * These routines require that the lock be held.
 */
#ifndef /* NOT */ DEBUG
#define WORKLIST_INSERT(head, item) do {  \
      (item)->wk_state |= ONWORKLIST;           \
      LIST_INSERT_HEAD(head, item, wk_list);    \
} while (0)
#define WORKLIST_REMOVE(item) do {        \
      (item)->wk_state &= ~ONWORKLIST;    \
      LIST_REMOVE(item, wk_list);         \
} while (0)
#else /* DEBUG */
static      void worklist_insert(struct workhead *, struct worklist *);
static      void worklist_remove(struct worklist *);

#define WORKLIST_INSERT(head, item) worklist_insert(head, item)
#define WORKLIST_REMOVE(item) worklist_remove(item)

static void
worklist_insert(head, item)
      struct workhead *head;
      struct worklist *item;
{

      mtx_assert(&lk, MA_OWNED);
      if (item->wk_state & ONWORKLIST)
            panic("worklist_insert: already on list");
      item->wk_state |= ONWORKLIST;
      LIST_INSERT_HEAD(head, item, wk_list);
}

static void
worklist_remove(item)
      struct worklist *item;
{

      mtx_assert(&lk, MA_OWNED);
      if ((item->wk_state & ONWORKLIST) == 0)
            panic("worklist_remove: not on list");
      item->wk_state &= ~ONWORKLIST;
      LIST_REMOVE(item, wk_list);
}
#endif /* DEBUG */

/*
 * Routines for tracking and managing workitems.
 */
static      void workitem_free(struct worklist *, int);
static      void workitem_alloc(struct worklist *, int, struct mount *);

#define     WORKITEM_FREE(item, type) workitem_free((struct worklist *)(item), (type))

static void
workitem_free(item, type)
      struct worklist *item;
      int type;
{
      struct ufsmount *ump;
      mtx_assert(&lk, MA_OWNED);

#ifdef DEBUG
      if (item->wk_state & ONWORKLIST)
            panic("workitem_free: still on list");
      if (item->wk_type != type)
            panic("workitem_free: type mismatch");
#endif
      ump = VFSTOUFS(item->wk_mp);
      if (--ump->softdep_deps == 0 && ump->softdep_req)
            wakeup(&ump->softdep_deps);
      FREE(item, DtoM(type));
}

static void
workitem_alloc(item, type, mp)
      struct worklist *item;
      int type;
      struct mount *mp;
{
      item->wk_type = type;
      item->wk_mp = mp;
      item->wk_state = 0;
      ACQUIRE_LOCK(&lk);
      VFSTOUFS(mp)->softdep_deps++;
      VFSTOUFS(mp)->softdep_accdeps++;
      FREE_LOCK(&lk);
}

/*
 * Workitem queue management
 */
static int max_softdeps;      /* maximum number of structs before slowdown */
static int maxindirdeps = 50; /* max number of indirdeps before slowdown */
static int tickdelay = 2;     /* number of ticks to pause during slowdown */
static int proc_waiting;      /* tracks whether we have a timeout posted */
static int *stat_countp;      /* statistic to count in proc_waiting timeout */
static struct callout_handle handle; /* handle on posted proc_waiting timeout */
static int req_pending;
static int req_clear_inodedeps;     /* syncer process flush some inodedeps */
#define FLUSH_INODES          1
static int req_clear_remove;  /* syncer process flush some freeblks */
#define FLUSH_REMOVE          2
#define FLUSH_REMOVE_WAIT     3
/*
 * runtime statistics
 */
static int stat_worklist_push;      /* number of worklist cleanups */
static int stat_blk_limit_push;     /* number of times block limit neared */
static int stat_ino_limit_push;     /* number of times inode limit neared */
static int stat_blk_limit_hit;      /* number of times block slowdown imposed */
static int stat_ino_limit_hit;      /* number of times inode slowdown imposed */
static int stat_sync_limit_hit;     /* number of synchronous slowdowns imposed */
static int stat_indir_blk_ptrs;     /* bufs redirtied as indir ptrs not written */
static int stat_inode_bitmap; /* bufs redirtied as inode bitmap not written */
static int stat_direct_blk_ptrs;/* bufs redirtied as direct ptrs not written */
static int stat_dir_entry;    /* bufs redirtied as dir entry cannot write */

SYSCTL_INT(_debug, OID_AUTO, max_softdeps, CTLFLAG_RW, &max_softdeps, 0, "");
SYSCTL_INT(_debug, OID_AUTO, tickdelay, CTLFLAG_RW, &tickdelay, 0, "");
SYSCTL_INT(_debug, OID_AUTO, maxindirdeps, CTLFLAG_RW, &maxindirdeps, 0, "");
SYSCTL_INT(_debug, OID_AUTO, worklist_push, CTLFLAG_RW, &stat_worklist_push, 0,"");
SYSCTL_INT(_debug, OID_AUTO, blk_limit_push, CTLFLAG_RW, &stat_blk_limit_push, 0,"");
SYSCTL_INT(_debug, OID_AUTO, ino_limit_push, CTLFLAG_RW, &stat_ino_limit_push, 0,"");
SYSCTL_INT(_debug, OID_AUTO, blk_limit_hit, CTLFLAG_RW, &stat_blk_limit_hit, 0, "");
SYSCTL_INT(_debug, OID_AUTO, ino_limit_hit, CTLFLAG_RW, &stat_ino_limit_hit, 0, "");
SYSCTL_INT(_debug, OID_AUTO, sync_limit_hit, CTLFLAG_RW, &stat_sync_limit_hit, 0, "");
SYSCTL_INT(_debug, OID_AUTO, indir_blk_ptrs, CTLFLAG_RW, &stat_indir_blk_ptrs, 0, "");
SYSCTL_INT(_debug, OID_AUTO, inode_bitmap, CTLFLAG_RW, &stat_inode_bitmap, 0, "");
SYSCTL_INT(_debug, OID_AUTO, direct_blk_ptrs, CTLFLAG_RW, &stat_direct_blk_ptrs, 0, "");
SYSCTL_INT(_debug, OID_AUTO, dir_entry, CTLFLAG_RW, &stat_dir_entry, 0, "");
/* SYSCTL_INT(_debug, OID_AUTO, worklist_num, CTLFLAG_RD, &softdep_on_worklist, 0, ""); */

SYSCTL_DECL(_vfs_ffs);

static int compute_summary_at_mount = 0;  /* Whether to recompute the summary at mount time */
SYSCTL_INT(_vfs_ffs, OID_AUTO, compute_summary_at_mount, CTLFLAG_RW,
         &compute_summary_at_mount, 0, "Recompute summary at mount");

static struct proc *softdepproc;
static struct kproc_desc softdep_kp = {
      "softdepflush",
      softdep_flush,
      &softdepproc
};
SYSINIT(sdproc, SI_SUB_KTHREAD_UPDATE, SI_ORDER_ANY, kproc_start, &softdep_kp)

static void
softdep_flush(void)
{
      struct mount *nmp;
      struct mount *mp;
      struct ufsmount *ump;
      struct thread *td;
      int remaining;
      int vfslocked;

      td = curthread;
      td->td_pflags |= TDP_NORUNNINGBUF;

      for (;;) {  
            kthread_suspend_check(softdepproc);
            vfslocked = VFS_LOCK_GIANT((struct mount *)NULL);
            ACQUIRE_LOCK(&lk);
            /*
             * If requested, try removing inode or removal dependencies.
             */
            if (req_clear_inodedeps) {
                  clear_inodedeps(td);
                  req_clear_inodedeps -= 1;
                  wakeup_one(&proc_waiting);
            }
            if (req_clear_remove) {
                  clear_remove(td);
                  req_clear_remove -= 1;
                  wakeup_one(&proc_waiting);
            }
            FREE_LOCK(&lk);
            VFS_UNLOCK_GIANT(vfslocked);
            remaining = 0;
            mtx_lock(&mountlist_mtx);
            for (mp = TAILQ_FIRST(&mountlist); mp != NULL; mp = nmp)  {
                  nmp = TAILQ_NEXT(mp, mnt_list);
                  if ((mp->mnt_flag & MNT_SOFTDEP) == 0)
                        continue;
                  if (vfs_busy(mp, LK_NOWAIT, &mountlist_mtx, td))
                        continue;
                  vfslocked = VFS_LOCK_GIANT(mp);
                  softdep_process_worklist(mp, 0);
                  ump = VFSTOUFS(mp);
                  remaining += ump->softdep_on_worklist -
                        ump->softdep_on_worklist_inprogress;
                  VFS_UNLOCK_GIANT(vfslocked);
                  mtx_lock(&mountlist_mtx);
                  nmp = TAILQ_NEXT(mp, mnt_list);
                  vfs_unbusy(mp, td);
            }
            mtx_unlock(&mountlist_mtx);
            if (remaining)
                  continue;
            ACQUIRE_LOCK(&lk);
            if (!req_pending)
                  msleep(&req_pending, &lk, PVM, "sdflush", hz);
            req_pending = 0;
            FREE_LOCK(&lk);
      }
}

static int
softdep_speedup(void)
{

      mtx_assert(&lk, MA_OWNED);
      if (req_pending == 0) {
            req_pending = 1;
            wakeup(&req_pending);
      }

      return speedup_syncer();
}

/*
 * Add an item to the end of the work queue.
 * This routine requires that the lock be held.
 * This is the only routine that adds items to the list.
 * The following routine is the only one that removes items
 * and does so in order from first to last.
 */
static void
add_to_worklist(wk)
      struct worklist *wk;
{
      struct ufsmount *ump;

      mtx_assert(&lk, MA_OWNED);
      ump = VFSTOUFS(wk->wk_mp);
      if (wk->wk_state & ONWORKLIST)
            panic("add_to_worklist: already on list");
      wk->wk_state |= ONWORKLIST;
      if (LIST_EMPTY(&ump->softdep_workitem_pending))
            LIST_INSERT_HEAD(&ump->softdep_workitem_pending, wk, wk_list);
      else
            LIST_INSERT_AFTER(ump->softdep_worklist_tail, wk, wk_list);
      ump->softdep_worklist_tail = wk;
      ump->softdep_on_worklist += 1;
}

/*
 * Process that runs once per second to handle items in the background queue.
 *
 * Note that we ensure that everything is done in the order in which they
 * appear in the queue. The code below depends on this property to ensure
 * that blocks of a file are freed before the inode itself is freed. This
 * ordering ensures that no new <vfsid, inum, lbn> triples will be generated
 * until all the old ones have been purged from the dependency lists.
 */
int 
softdep_process_worklist(mp, full)
      struct mount *mp;
      int full;
{
      struct thread *td = curthread;
      int cnt, matchcnt, loopcount;
      struct ufsmount *ump;
      long starttime;

      KASSERT(mp != NULL, ("softdep_process_worklist: NULL mp"));
      /*
       * Record the process identifier of our caller so that we can give
       * this process preferential treatment in request_cleanup below.
       */
      matchcnt = 0;
      ump = VFSTOUFS(mp);
      ACQUIRE_LOCK(&lk);
      loopcount = 1;
      starttime = time_second;
      while (ump->softdep_on_worklist > 0) {
            if ((cnt = process_worklist_item(mp, 0)) == -1)
                  break;
            else
                  matchcnt += cnt;
            /*
             * If requested, try removing inode or removal dependencies.
             */
            if (req_clear_inodedeps) {
                  clear_inodedeps(td);
                  req_clear_inodedeps -= 1;
                  wakeup_one(&proc_waiting);
            }
            if (req_clear_remove) {
                  clear_remove(td);
                  req_clear_remove -= 1;
                  wakeup_one(&proc_waiting);
            }
            /*
             * We do not generally want to stop for buffer space, but if
             * we are really being a buffer hog, we will stop and wait.
             */
            if (loopcount++ % 128 == 0) {
                  FREE_LOCK(&lk);
                  bwillwrite();
                  ACQUIRE_LOCK(&lk);
            }
            /*
             * Never allow processing to run for more than one
             * second. Otherwise the other mountpoints may get
             * excessively backlogged.
             */
            if (!full && starttime != time_second) {
                  matchcnt = -1;
                  break;
            }
      }
      FREE_LOCK(&lk);
      return (matchcnt);
}

/*
 * Process one item on the worklist.
 */
static int
process_worklist_item(mp, flags)
      struct mount *mp;
      int flags;
{
      struct worklist *wk, *wkend;
      struct ufsmount *ump;
      struct vnode *vp;
      int matchcnt = 0;

      mtx_assert(&lk, MA_OWNED);
      KASSERT(mp != NULL, ("process_worklist_item: NULL mp"));
      /*
       * If we are being called because of a process doing a
       * copy-on-write, then it is not safe to write as we may
       * recurse into the copy-on-write routine.
       */
      if (curthread->td_pflags & TDP_COWINPROGRESS)
            return (-1);
      /*
       * Normally we just process each item on the worklist in order.
       * However, if we are in a situation where we cannot lock any
       * inodes, we have to skip over any dirrem requests whose
       * vnodes are resident and locked.
       */
      ump = VFSTOUFS(mp);
      vp = NULL;
      LIST_FOREACH(wk, &ump->softdep_workitem_pending, wk_list) {
            if (wk->wk_state & INPROGRESS)
                  continue;
            if ((flags & LK_NOWAIT) == 0 || wk->wk_type != D_DIRREM)
                  break;
            wk->wk_state |= INPROGRESS;
            ump->softdep_on_worklist_inprogress++;
            FREE_LOCK(&lk);
            ffs_vget(mp, WK_DIRREM(wk)->dm_oldinum,
                LK_NOWAIT | LK_EXCLUSIVE, &vp);
            ACQUIRE_LOCK(&lk);
            wk->wk_state &= ~INPROGRESS;
            ump->softdep_on_worklist_inprogress--;
            if (vp != NULL)
                  break;
      }
      if (wk == 0)
            return (-1);
      /*
       * Remove the item to be processed. If we are removing the last
       * item on the list, we need to recalculate the tail pointer.
       * As this happens rarely and usually when the list is short,
       * we just run down the list to find it rather than tracking it
       * in the above loop.
       */
      WORKLIST_REMOVE(wk);
      if (wk == ump->softdep_worklist_tail) {
            LIST_FOREACH(wkend, &ump->softdep_workitem_pending, wk_list)
                  if (LIST_NEXT(wkend, wk_list) == NULL)
                        break;
            ump->softdep_worklist_tail = wkend;
      }
      ump->softdep_on_worklist -= 1;
      FREE_LOCK(&lk);
      if (vn_start_secondary_write(NULL, &mp, V_NOWAIT))
            panic("process_worklist_item: suspended filesystem");
      matchcnt++;
      switch (wk->wk_type) {

      case D_DIRREM:
            /* removal of a directory entry */
            handle_workitem_remove(WK_DIRREM(wk), vp);
            break;

      case D_FREEBLKS:
            /* releasing blocks and/or fragments from a file */
            handle_workitem_freeblocks(WK_FREEBLKS(wk), flags & LK_NOWAIT);
            break;

      case D_FREEFRAG:
            /* releasing a fragment when replaced as a file grows */
            handle_workitem_freefrag(WK_FREEFRAG(wk));
            break;

      case D_FREEFILE:
            /* releasing an inode when its link count drops to 0 */
            handle_workitem_freefile(WK_FREEFILE(wk));
            break;

      default:
            panic("%s_process_worklist: Unknown type %s",
                "softdep", TYPENAME(wk->wk_type));
            /* NOTREACHED */
      }
      vn_finished_secondary_write(mp);
      ACQUIRE_LOCK(&lk);
      return (matchcnt);
}

/*
 * Move dependencies from one buffer to another.
 */
void
softdep_move_dependencies(oldbp, newbp)
      struct buf *oldbp;
      struct buf *newbp;
{
      struct worklist *wk, *wktail;

      if (!LIST_EMPTY(&newbp->b_dep))
            panic("softdep_move_dependencies: need merge code");
      wktail = 0;
      ACQUIRE_LOCK(&lk);
      while ((wk = LIST_FIRST(&oldbp->b_dep)) != NULL) {
            LIST_REMOVE(wk, wk_list);
            if (wktail == 0)
                  LIST_INSERT_HEAD(&newbp->b_dep, wk, wk_list);
            else
                  LIST_INSERT_AFTER(wktail, wk, wk_list);
            wktail = wk;
      }
      FREE_LOCK(&lk);
}

/*
 * Purge the work list of all items associated with a particular mount point.
 */
int
softdep_flushworklist(oldmnt, countp, td)
      struct mount *oldmnt;
      int *countp;
      struct thread *td;
{
      struct vnode *devvp;
      int count, error = 0;
      struct ufsmount *ump;

      /*
       * Alternately flush the block device associated with the mount
       * point and process any dependencies that the flushing
       * creates. We continue until no more worklist dependencies
       * are found.
       */
      *countp = 0;
      ump = VFSTOUFS(oldmnt);
      devvp = ump->um_devvp;
      while ((count = softdep_process_worklist(oldmnt, 1)) > 0) {
            *countp += count;
            vn_lock(devvp, LK_EXCLUSIVE | LK_RETRY, td);
            error = VOP_FSYNC(devvp, MNT_WAIT, td);
            VOP_UNLOCK(devvp, 0, td);
            if (error)
                  break;
      }
      return (error);
}

int
softdep_waitidle(struct mount *mp)
{
      struct ufsmount *ump;
      int error;
      int i;

      ump = VFSTOUFS(mp);
      ACQUIRE_LOCK(&lk);
      for (i = 0; i < 10 && ump->softdep_deps; i++) {
            ump->softdep_req = 1;
            if (ump->softdep_on_worklist)
                  panic("softdep_waitidle: work added after flush.");
            msleep(&ump->softdep_deps, &lk, PVM, "softdeps", 1);
      }
      ump->softdep_req = 0;
      FREE_LOCK(&lk);
      error = 0;
      if (i == 10) {
            error = EBUSY;
            printf("softdep_waitidle: Failed to flush worklist for %p\n",
                mp);
      }

      return (error);
}

/*
 * Flush all vnodes and worklist items associated with a specified mount point.
 */
int
softdep_flushfiles(oldmnt, flags, td)
      struct mount *oldmnt;
      int flags;
      struct thread *td;
{
      int error, count, loopcnt;

      error = 0;

      /*
       * Alternately flush the vnodes associated with the mount
       * point and process any dependencies that the flushing
       * creates. In theory, this loop can happen at most twice,
       * but we give it a few extra just to be sure.
       */
      for (loopcnt = 10; loopcnt > 0; loopcnt--) {
            /*
             * Do another flush in case any vnodes were brought in
             * as part of the cleanup operations.
             */
            if ((error = ffs_flushfiles(oldmnt, flags, td)) != 0)
                  break;
            if ((error = softdep_flushworklist(oldmnt, &count, td)) != 0 ||
                count == 0)
                  break;
      }
      /*
       * If we are unmounting then it is an error to fail. If we
       * are simply trying to downgrade to read-only, then filesystem
       * activity can keep us busy forever, so we just fail with EBUSY.
       */
      if (loopcnt == 0) {
            if (oldmnt->mnt_kern_flag & MNTK_UNMOUNT)
                  panic("softdep_flushfiles: looping");
            error = EBUSY;
      }
      if (!error)
            error = softdep_waitidle(oldmnt);
      return (error);
}

/*
 * Structure hashing.
 * 
 * There are three types of structures that can be looked up:
 *    1) pagedep structures identified by mount point, inode number,
 *       and logical block.
 *    2) inodedep structures identified by mount point and inode number.
 *    3) newblk structures identified by mount point and
 *       physical block number.
 *
 * The "pagedep" and "inodedep" dependency structures are hashed
 * separately from the file blocks and inodes to which they correspond.
 * This separation helps when the in-memory copy of an inode or
 * file block must be replaced. It also obviates the need to access
 * an inode or file page when simply updating (or de-allocating)
 * dependency structures. Lookup of newblk structures is needed to
 * find newly allocated blocks when trying to associate them with
 * their allocdirect or allocindir structure.
 *
 * The lookup routines optionally create and hash a new instance when
 * an existing entry is not found.
 */
#define DEPALLOC  0x0001      /* allocate structure if lookup fails */
#define NODELAY         0x0002      /* cannot do background work */

/*
 * Structures and routines associated with pagedep caching.
 */
LIST_HEAD(pagedep_hashhead, pagedep) *pagedep_hashtbl;
u_long      pagedep_hash;           /* size of hash table - 1 */
#define     PAGEDEP_HASH(mp, inum, lbn) \
      (&pagedep_hashtbl[((((register_t)(mp)) >> 13) + (inum) + (lbn)) & \
          pagedep_hash])

static int
pagedep_find(pagedephd, ino, lbn, mp, flags, pagedeppp)
      struct pagedep_hashhead *pagedephd;
      ino_t ino;
      ufs_lbn_t lbn;
      struct mount *mp;
      int flags;
      struct pagedep **pagedeppp;
{
      struct pagedep *pagedep;

      LIST_FOREACH(pagedep, pagedephd, pd_hash)
            if (ino == pagedep->pd_ino &&
                lbn == pagedep->pd_lbn &&
                mp == pagedep->pd_list.wk_mp)
                  break;
      if (pagedep) {
            *pagedeppp = pagedep;
            if ((flags & DEPALLOC) != 0 &&
                (pagedep->pd_state & ONWORKLIST) == 0)
                  return (0);
            return (1);
      }
      *pagedeppp = NULL;
      return (0);
}
/*
 * Look up a pagedep. Return 1 if found, 0 if not found or found
 * when asked to allocate but not associated with any buffer.
 * If not found, allocate if DEPALLOC flag is passed.
 * Found or allocated entry is returned in pagedeppp.
 * This routine must be called with splbio interrupts blocked.
 */
static int
pagedep_lookup(ip, lbn, flags, pagedeppp)
      struct inode *ip;
      ufs_lbn_t lbn;
      int flags;
      struct pagedep **pagedeppp;
{
      struct pagedep *pagedep;
      struct pagedep_hashhead *pagedephd;
      struct mount *mp;
      int ret;
      int i;

      mtx_assert(&lk, MA_OWNED);
      mp = ITOV(ip)->v_mount;
      pagedephd = PAGEDEP_HASH(mp, ip->i_number, lbn);

      ret = pagedep_find(pagedephd, ip->i_number, lbn, mp, flags, pagedeppp);
      if (*pagedeppp || (flags & DEPALLOC) == 0)
            return (ret);
      FREE_LOCK(&lk);
      MALLOC(pagedep, struct pagedep *, sizeof(struct pagedep),
          M_PAGEDEP, M_SOFTDEP_FLAGS|M_ZERO);
      workitem_alloc(&pagedep->pd_list, D_PAGEDEP, mp);
      ACQUIRE_LOCK(&lk);
      ret = pagedep_find(pagedephd, ip->i_number, lbn, mp, flags, pagedeppp);
      if (*pagedeppp) {
            WORKITEM_FREE(pagedep, D_PAGEDEP);
            return (ret);
      }
      pagedep->pd_ino = ip->i_number;
      pagedep->pd_lbn = lbn;
      LIST_INIT(&pagedep->pd_dirremhd);
      LIST_INIT(&pagedep->pd_pendinghd);
      for (i = 0; i < DAHASHSZ; i++)
            LIST_INIT(&pagedep->pd_diraddhd[i]);
      LIST_INSERT_HEAD(pagedephd, pagedep, pd_hash);
      *pagedeppp = pagedep;
      return (0);
}

/*
 * Structures and routines associated with inodedep caching.
 */
LIST_HEAD(inodedep_hashhead, inodedep) *inodedep_hashtbl;
static u_long     inodedep_hash;    /* size of hash table - 1 */
static long num_inodedep;     /* number of inodedep allocated */
#define     INODEDEP_HASH(fs, inum) \
      (&inodedep_hashtbl[((((register_t)(fs)) >> 13) + (inum)) & inodedep_hash])

static int
inodedep_find(inodedephd, fs, inum, inodedeppp)
      struct inodedep_hashhead *inodedephd;
      struct fs *fs;
      ino_t inum;
      struct inodedep **inodedeppp;
{
      struct inodedep *inodedep;

      LIST_FOREACH(inodedep, inodedephd, id_hash)
            if (inum == inodedep->id_ino && fs == inodedep->id_fs)
                  break;
      if (inodedep) {
            *inodedeppp = inodedep;
            return (1);
      }
      *inodedeppp = NULL;

      return (0);
}
/*
 * Look up an inodedep. Return 1 if found, 0 if not found.
 * If not found, allocate if DEPALLOC flag is passed.
 * Found or allocated entry is returned in inodedeppp.
 * This routine must be called with splbio interrupts blocked.
 */
static int
inodedep_lookup(mp, inum, flags, inodedeppp)
      struct mount *mp;
      ino_t inum;
      int flags;
      struct inodedep **inodedeppp;
{
      struct inodedep *inodedep;
      struct inodedep_hashhead *inodedephd;
      struct fs *fs;

      mtx_assert(&lk, MA_OWNED);
      fs = VFSTOUFS(mp)->um_fs;
      inodedephd = INODEDEP_HASH(fs, inum);

      if (inodedep_find(inodedephd, fs, inum, inodedeppp))
            return (1);
      if ((flags & DEPALLOC) == 0)
            return (0);
      /*
       * If we are over our limit, try to improve the situation.
       */
      if (num_inodedep > max_softdeps && (flags & NODELAY) == 0)
            request_cleanup(mp, FLUSH_INODES);
      FREE_LOCK(&lk);
      MALLOC(inodedep, struct inodedep *, sizeof(struct inodedep),
            M_INODEDEP, M_SOFTDEP_FLAGS);
      workitem_alloc(&inodedep->id_list, D_INODEDEP, mp);
      ACQUIRE_LOCK(&lk);
      if (inodedep_find(inodedephd, fs, inum, inodedeppp)) {
            WORKITEM_FREE(inodedep, D_INODEDEP);
            return (1);
      }
      num_inodedep += 1;
      inodedep->id_fs = fs;
      inodedep->id_ino = inum;
      inodedep->id_state = ALLCOMPLETE;
      inodedep->id_nlinkdelta = 0;
      inodedep->id_savedino1 = NULL;
      inodedep->id_savedsize = -1;
      inodedep->id_savedextsize = -1;
      inodedep->id_buf = NULL;
      LIST_INIT(&inodedep->id_pendinghd);
      LIST_INIT(&inodedep->id_inowait);
      LIST_INIT(&inodedep->id_bufwait);
      TAILQ_INIT(&inodedep->id_inoupdt);
      TAILQ_INIT(&inodedep->id_newinoupdt);
      TAILQ_INIT(&inodedep->id_extupdt);
      TAILQ_INIT(&inodedep->id_newextupdt);
      LIST_INSERT_HEAD(inodedephd, inodedep, id_hash);
      *inodedeppp = inodedep;
      return (0);
}

/*
 * Structures and routines associated with newblk caching.
 */
LIST_HEAD(newblk_hashhead, newblk) *newblk_hashtbl;
u_long      newblk_hash;            /* size of hash table - 1 */
#define     NEWBLK_HASH(fs, inum) \
      (&newblk_hashtbl[((((register_t)(fs)) >> 13) + (inum)) & newblk_hash])

static int
newblk_find(newblkhd, fs, newblkno, newblkpp)
      struct newblk_hashhead *newblkhd;
      struct fs *fs;
      ufs2_daddr_t newblkno;
      struct newblk **newblkpp;
{
      struct newblk *newblk;

      LIST_FOREACH(newblk, newblkhd, nb_hash)
            if (newblkno == newblk->nb_newblkno && fs == newblk->nb_fs)
                  break;
      if (newblk) {
            *newblkpp = newblk;
            return (1);
      }
      *newblkpp = NULL;
      return (0);
}

/*
 * Look up a newblk. Return 1 if found, 0 if not found.
 * If not found, allocate if DEPALLOC flag is passed.
 * Found or allocated entry is returned in newblkpp.
 */
static int
newblk_lookup(fs, newblkno, flags, newblkpp)
      struct fs *fs;
      ufs2_daddr_t newblkno;
      int flags;
      struct newblk **newblkpp;
{
      struct newblk *newblk;
      struct newblk_hashhead *newblkhd;

      newblkhd = NEWBLK_HASH(fs, newblkno);
      if (newblk_find(newblkhd, fs, newblkno, newblkpp))
            return (1);
      if ((flags & DEPALLOC) == 0)
            return (0);
      FREE_LOCK(&lk);
      MALLOC(newblk, struct newblk *, sizeof(struct newblk),
            M_NEWBLK, M_SOFTDEP_FLAGS);
      ACQUIRE_LOCK(&lk);
      if (newblk_find(newblkhd, fs, newblkno, newblkpp)) {
            FREE(newblk, M_NEWBLK);
            return (1);
      }
      newblk->nb_state = 0;
      newblk->nb_fs = fs;
      newblk->nb_newblkno = newblkno;
      LIST_INSERT_HEAD(newblkhd, newblk, nb_hash);
      *newblkpp = newblk;
      return (0);
}

/*
 * Executed during filesystem system initialization before
 * mounting any filesystems.
 */
void 
softdep_initialize()
{

      LIST_INIT(&mkdirlisthd);
      max_softdeps = desiredvnodes * 4;
      pagedep_hashtbl = hashinit(desiredvnodes / 5, M_PAGEDEP,
          &pagedep_hash);
      inodedep_hashtbl = hashinit(desiredvnodes, M_INODEDEP, &inodedep_hash);
      newblk_hashtbl = hashinit(64, M_NEWBLK, &newblk_hash);

      /* initialise bioops hack */
      bioops.io_start = softdep_disk_io_initiation;
      bioops.io_complete = softdep_disk_write_complete;
      bioops.io_deallocate = softdep_deallocate_dependencies;
      bioops.io_countdeps = softdep_count_dependencies;
}

/*
 * Executed after all filesystems have been unmounted during
 * filesystem module unload.
 */
void
softdep_uninitialize()
{

      hashdestroy(pagedep_hashtbl, M_PAGEDEP, pagedep_hash);
      hashdestroy(inodedep_hashtbl, M_INODEDEP, inodedep_hash);
      hashdestroy(newblk_hashtbl, M_NEWBLK, newblk_hash);
}

/*
 * Called at mount time to notify the dependency code that a
 * filesystem wishes to use it.
 */
int
softdep_mount(devvp, mp, fs, cred)
      struct vnode *devvp;
      struct mount *mp;
      struct fs *fs;
      struct ucred *cred;
{
      struct csum_total cstotal;
      struct ufsmount *ump;
      struct cg *cgp;
      struct buf *bp;
      int error, cyl;

      MNT_ILOCK(mp);
      mp->mnt_flag = (mp->mnt_flag & ~MNT_ASYNC) | MNT_SOFTDEP;
      if ((mp->mnt_kern_flag & MNTK_SOFTDEP) == 0) {
            mp->mnt_kern_flag = (mp->mnt_kern_flag & ~MNTK_ASYNC) | 
                  MNTK_SOFTDEP;
            mp->mnt_noasync++;
      }
      MNT_IUNLOCK(mp);
      ump = VFSTOUFS(mp);
      LIST_INIT(&ump->softdep_workitem_pending);
      ump->softdep_worklist_tail = NULL;
      ump->softdep_on_worklist = 0;
      ump->softdep_deps = 0;
      /*
       * When doing soft updates, the counters in the
       * superblock may have gotten out of sync. Recomputation
       * can take a long time and can be deferred for background
       * fsck.  However, the old behavior of scanning the cylinder
       * groups and recalculating them at mount time is available
       * by setting vfs.ffs.compute_summary_at_mount to one.
       */
      if (compute_summary_at_mount == 0 || fs->fs_clean != 0)
            return (0);
      bzero(&cstotal, sizeof cstotal);
      for (cyl = 0; cyl < fs->fs_ncg; cyl++) {
            if ((error = bread(devvp, fsbtodb(fs, cgtod(fs, cyl)),
                fs->fs_cgsize, cred, &bp)) != 0) {
                  brelse(bp);
                  return (error);
            }
            cgp = (struct cg *)bp->b_data;
            cstotal.cs_nffree += cgp->cg_cs.cs_nffree;
            cstotal.cs_nbfree += cgp->cg_cs.cs_nbfree;
            cstotal.cs_nifree += cgp->cg_cs.cs_nifree;
            cstotal.cs_ndir += cgp->cg_cs.cs_ndir;
            fs->fs_cs(fs, cyl) = cgp->cg_cs;
            brelse(bp);
      }
#ifdef DEBUG
      if (bcmp(&cstotal, &fs->fs_cstotal, sizeof cstotal))
            printf("%s: superblock summary recomputed\n", fs->fs_fsmnt);
#endif
      bcopy(&cstotal, &fs->fs_cstotal, sizeof cstotal);
      return (0);
}

/*
 * Protecting the freemaps (or bitmaps).
 * 
 * To eliminate the need to execute fsck before mounting a filesystem
 * after a power failure, one must (conservatively) guarantee that the
 * on-disk copy of the bitmaps never indicate that a live inode or block is
 * free.  So, when a block or inode is allocated, the bitmap should be
 * updated (on disk) before any new pointers.  When a block or inode is
 * freed, the bitmap should not be updated until all pointers have been
 * reset.  The latter dependency is handled by the delayed de-allocation
 * approach described below for block and inode de-allocation.  The former
 * dependency is handled by calling the following procedure when a block or
 * inode is allocated. When an inode is allocated an "inodedep" is created
 * with its DEPCOMPLETE flag cleared until its bitmap is written to disk.
 * Each "inodedep" is also inserted into the hash indexing structure so
 * that any additional link additions can be made dependent on the inode
 * allocation.
 * 
 * The ufs filesystem maintains a number of free block counts (e.g., per
 * cylinder group, per cylinder and per <cylinder, rotational position> pair)
 * in addition to the bitmaps.  These counts are used to improve efficiency
 * during allocation and therefore must be consistent with the bitmaps.
 * There is no convenient way to guarantee post-crash consistency of these
 * counts with simple update ordering, for two main reasons: (1) The counts
 * and bitmaps for a single cylinder group block are not in the same disk
 * sector.  If a disk write is interrupted (e.g., by power failure), one may
 * be written and the other not.  (2) Some of the counts are located in the
 * superblock rather than the cylinder group block. So, we focus our soft
 * updates implementation on protecting the bitmaps. When mounting a
 * filesystem, we recompute the auxiliary counts from the bitmaps.
 */

/*
 * Called just after updating the cylinder group block to allocate an inode.
 */
void
softdep_setup_inomapdep(bp, ip, newinum)
      struct buf *bp;         /* buffer for cylgroup block with inode map */
      struct inode *ip; /* inode related to allocation */
      ino_t newinum;          /* new inode number being allocated */
{
      struct inodedep *inodedep;
      struct bmsafemap *bmsafemap;

      /*
       * Create a dependency for the newly allocated inode.
       * Panic if it already exists as something is seriously wrong.
       * Otherwise add it to the dependency list for the buffer holding
       * the cylinder group map from which it was allocated.
       */
      ACQUIRE_LOCK(&lk);
      if ((inodedep_lookup(UFSTOVFS(ip->i_ump), newinum, DEPALLOC|NODELAY,
          &inodedep)))
            panic("softdep_setup_inomapdep: dependency for new inode "
                "already exists");
      inodedep->id_buf = bp;
      inodedep->id_state &= ~DEPCOMPLETE;
      bmsafemap = bmsafemap_lookup(inodedep->id_list.wk_mp, bp);
      LIST_INSERT_HEAD(&bmsafemap->sm_inodedephd, inodedep, id_deps);
      FREE_LOCK(&lk);
}

/*
 * Called just after updating the cylinder group block to
 * allocate block or fragment.
 */
void
softdep_setup_blkmapdep(bp, mp, newblkno)
      struct buf *bp;         /* buffer for cylgroup block with block map */
      struct mount *mp; /* filesystem doing allocation */
      ufs2_daddr_t newblkno;  /* number of newly allocated block */
{
      struct newblk *newblk;
      struct bmsafemap *bmsafemap;
      struct fs *fs;

      fs = VFSTOUFS(mp)->um_fs;
      /*
       * Create a dependency for the newly allocated block.
       * Add it to the dependency list for the buffer holding
       * the cylinder group map from which it was allocated.
       */
      ACQUIRE_LOCK(&lk);
      if (newblk_lookup(fs, newblkno, DEPALLOC, &newblk) != 0)
            panic("softdep_setup_blkmapdep: found block");
      newblk->nb_bmsafemap = bmsafemap = bmsafemap_lookup(mp, bp);
      LIST_INSERT_HEAD(&bmsafemap->sm_newblkhd, newblk, nb_deps);
      FREE_LOCK(&lk);
}

/*
 * Find the bmsafemap associated with a cylinder group buffer.
 * If none exists, create one. The buffer must be locked when
 * this routine is called and this routine must be called with
 * splbio interrupts blocked.
 */
static struct bmsafemap *
bmsafemap_lookup(mp, bp)
      struct mount *mp;
      struct buf *bp;
{
      struct bmsafemap *bmsafemap;
      struct worklist *wk;

      mtx_assert(&lk, MA_OWNED);
      LIST_FOREACH(wk, &bp->b_dep, wk_list)
            if (wk->wk_type == D_BMSAFEMAP)
                  return (WK_BMSAFEMAP(wk));
      FREE_LOCK(&lk);
      MALLOC(bmsafemap, struct bmsafemap *, sizeof(struct bmsafemap),
            M_BMSAFEMAP, M_SOFTDEP_FLAGS);
      workitem_alloc(&bmsafemap->sm_list, D_BMSAFEMAP, mp);
      bmsafemap->sm_buf = bp;
      LIST_INIT(&bmsafemap->sm_allocdirecthd);
      LIST_INIT(&bmsafemap->sm_allocindirhd);
      LIST_INIT(&bmsafemap->sm_inodedephd);
      LIST_INIT(&bmsafemap->sm_newblkhd);
      ACQUIRE_LOCK(&lk);
      WORKLIST_INSERT(&bp->b_dep, &bmsafemap->sm_list);
      return (bmsafemap);
}

/*
 * Direct block allocation dependencies.
 * 
 * When a new block is allocated, the corresponding disk locations must be
 * initialized (with zeros or new data) before the on-disk inode points to
 * them.  Also, the freemap from which the block was allocated must be
 * updated (on disk) before the inode's pointer. These two dependencies are
 * independent of each other and are needed for all file blocks and indirect
 * blocks that are pointed to directly by the inode.  Just before the
 * "in-core" version of the inode is updated with a newly allocated block
 * number, a procedure (below) is called to setup allocation dependency
 * structures.  These structures are removed when the corresponding
 * dependencies are satisfied or when the block allocation becomes obsolete
 * (i.e., the file is deleted, the block is de-allocated, or the block is a
 * fragment that gets upgraded).  All of these cases are handled in
 * procedures described later.
 * 
 * When a file extension causes a fragment to be upgraded, either to a larger
 * fragment or to a full block, the on-disk location may change (if the
 * previous fragment could not simply be extended). In this case, the old
 * fragment must be de-allocated, but not until after the inode's pointer has
 * been updated. In most cases, this is handled by later procedures, which
 * will construct a "freefrag" structure to be added to the workitem queue
 * when the inode update is complete (or obsolete).  The main exception to
 * this is when an allocation occurs while a pending allocation dependency
 * (for the same block pointer) remains.  This case is handled in the main
 * allocation dependency setup procedure by immediately freeing the
 * unreferenced fragments.
 */ 
void 
softdep_setup_allocdirect(ip, lbn, newblkno, oldblkno, newsize, oldsize, bp)
      struct inode *ip; /* inode to which block is being added */
      ufs_lbn_t lbn;          /* block pointer within inode */
      ufs2_daddr_t newblkno;  /* disk block number being added */
      ufs2_daddr_t oldblkno;  /* previous block number, 0 unless frag */
      long newsize;           /* size of new block */
      long oldsize;           /* size of new block */
      struct buf *bp;         /* bp for allocated block */
{
      struct allocdirect *adp, *oldadp;
      struct allocdirectlst *adphead;
      struct bmsafemap *bmsafemap;
      struct inodedep *inodedep;
      struct pagedep *pagedep;
      struct newblk *newblk;
      struct mount *mp;

      mp = UFSTOVFS(ip->i_ump);
      MALLOC(adp, struct allocdirect *, sizeof(struct allocdirect),
            M_ALLOCDIRECT, M_SOFTDEP_FLAGS|M_ZERO);
      workitem_alloc(&adp->ad_list, D_ALLOCDIRECT, mp);
      adp->ad_lbn = lbn;
      adp->ad_newblkno = newblkno;
      adp->ad_oldblkno = oldblkno;
      adp->ad_newsize = newsize;
      adp->ad_oldsize = oldsize;
      adp->ad_state = ATTACHED;
      LIST_INIT(&adp->ad_newdirblk);
      if (newblkno == oldblkno)
            adp->ad_freefrag = NULL;
      else
            adp->ad_freefrag = newfreefrag(ip, oldblkno, oldsize);

      ACQUIRE_LOCK(&lk);
      if (lbn >= NDADDR) {
            /* allocating an indirect block */
            if (oldblkno != 0)
                  panic("softdep_setup_allocdirect: non-zero indir");
      } else {
            /*
             * Allocating a direct block.
             *
             * If we are allocating a directory block, then we must
             * allocate an associated pagedep to track additions and
             * deletions.
             */
            if ((ip->i_mode & IFMT) == IFDIR &&
                pagedep_lookup(ip, lbn, DEPALLOC, &pagedep) == 0)
                  WORKLIST_INSERT(&bp->b_dep, &pagedep->pd_list);
      }
      if (newblk_lookup(ip->i_fs, newblkno, 0, &newblk) == 0)
            panic("softdep_setup_allocdirect: lost block");
      if (newblk->nb_state == DEPCOMPLETE) {
            adp->ad_state |= DEPCOMPLETE;
            adp->ad_buf = NULL;
      } else {
            bmsafemap = newblk->nb_bmsafemap;
            adp->ad_buf = bmsafemap->sm_buf;
            LIST_REMOVE(newblk, nb_deps);
            LIST_INSERT_HEAD(&bmsafemap->sm_allocdirecthd, adp, ad_deps);
      }
      LIST_REMOVE(newblk, nb_hash);
      FREE(newblk, M_NEWBLK);

      inodedep_lookup(mp, ip->i_number, DEPALLOC | NODELAY, &inodedep);
      adp->ad_inodedep = inodedep;
      WORKLIST_INSERT(&bp->b_dep, &adp->ad_list);
      /*
       * The list of allocdirects must be kept in sorted and ascending
       * order so that the rollback routines can quickly determine the
       * first uncommitted block (the size of the file stored on disk
       * ends at the end of the lowest committed fragment, or if there
       * are no fragments, at the end of the highest committed block).
       * Since files generally grow, the typical case is that the new
       * block is to be added at the end of the list. We speed this
       * special case by checking against the last allocdirect in the
       * list before laboriously traversing the list looking for the
       * insertion point.
       */
      adphead = &inodedep->id_newinoupdt;
      oldadp = TAILQ_LAST(adphead, allocdirectlst);
      if (oldadp == NULL || oldadp->ad_lbn <= lbn) {
            /* insert at end of list */
            TAILQ_INSERT_TAIL(adphead, adp, ad_next);
            if (oldadp != NULL && oldadp->ad_lbn == lbn)
                  allocdirect_merge(adphead, adp, oldadp);
            FREE_LOCK(&lk);
            return;
      }
      TAILQ_FOREACH(oldadp, adphead, ad_next) {
            if (oldadp->ad_lbn >= lbn)
                  break;
      }
      if (oldadp == NULL)
            panic("softdep_setup_allocdirect: lost entry");
      /* insert in middle of list */
      TAILQ_INSERT_BEFORE(oldadp, adp, ad_next);
      if (oldadp->ad_lbn == lbn)
            allocdirect_merge(adphead, adp, oldadp);
      FREE_LOCK(&lk);
}

/*
 * Replace an old allocdirect dependency with a newer one.
 * This routine must be called with splbio interrupts blocked.
 */
static void
allocdirect_merge(adphead, newadp, oldadp)
      struct allocdirectlst *adphead;     /* head of list holding allocdirects */
      struct allocdirect *newadp;   /* allocdirect being added */
      struct allocdirect *oldadp;   /* existing allocdirect being checked */
{
      struct worklist *wk;
      struct freefrag *freefrag;
      struct newdirblk *newdirblk;

      mtx_assert(&lk, MA_OWNED);
      if (newadp->ad_oldblkno != oldadp->ad_newblkno ||
          newadp->ad_oldsize != oldadp->ad_newsize ||
          newadp->ad_lbn >= NDADDR)
            panic("%s %jd != new %jd || old size %ld != new %ld",
                "allocdirect_merge: old blkno",
                (intmax_t)newadp->ad_oldblkno,
                (intmax_t)oldadp->ad_newblkno,
                newadp->ad_oldsize, oldadp->ad_newsize);
      newadp->ad_oldblkno = oldadp->ad_oldblkno;
      newadp->ad_oldsize = oldadp->ad_oldsize;
      /*
       * If the old dependency had a fragment to free or had never
       * previously had a block allocated, then the new dependency
       * can immediately post its freefrag and adopt the old freefrag.
       * This action is done by swapping the freefrag dependencies.
       * The new dependency gains the old one's freefrag, and the
       * old one gets the new one and then immediately puts it on
       * the worklist when it is freed by free_allocdirect. It is
       * not possible to do this swap when the old dependency had a
       * non-zero size but no previous fragment to free. This condition
       * arises when the new block is an extension of the old block.
       * Here, the first part of the fragment allocated to the new
       * dependency is part of the block currently claimed on disk by
       * the old dependency, so cannot legitimately be freed until the
       * conditions for the new dependency are fulfilled.
       */
      if (oldadp->ad_freefrag != NULL || oldadp->ad_oldblkno == 0) {
            freefrag = newadp->ad_freefrag;
            newadp->ad_freefrag = oldadp->ad_freefrag;
            oldadp->ad_freefrag = freefrag;
      }
      /*
       * If we are tracking a new directory-block allocation,
       * move it from the old allocdirect to the new allocdirect.
       */
      if ((wk = LIST_FIRST(&oldadp->ad_newdirblk)) != NULL) {
            newdirblk = WK_NEWDIRBLK(wk);
            WORKLIST_REMOVE(&newdirblk->db_list);
            if (!LIST_EMPTY(&oldadp->ad_newdirblk))
                  panic("allocdirect_merge: extra newdirblk");
            WORKLIST_INSERT(&newadp->ad_newdirblk, &newdirblk->db_list);
      }
      free_allocdirect(adphead, oldadp, 0);
}
            
/*
 * Allocate a new freefrag structure if needed.
 */
static struct freefrag *
newfreefrag(ip, blkno, size)
      struct inode *ip;
      ufs2_daddr_t blkno;
      long size;
{
      struct freefrag *freefrag;
      struct fs *fs;

      if (blkno == 0)
            return (NULL);
      fs = ip->i_fs;
      if (fragnum(fs, blkno) + numfrags(fs, size) > fs->fs_frag)
            panic("newfreefrag: frag size");
      MALLOC(freefrag, struct freefrag *, sizeof(struct freefrag),
            M_FREEFRAG, M_SOFTDEP_FLAGS);
      workitem_alloc(&freefrag->ff_list, D_FREEFRAG, UFSTOVFS(ip->i_ump));
      freefrag->ff_inum = ip->i_number;
      freefrag->ff_blkno = blkno;
      freefrag->ff_fragsize = size;
      return (freefrag);
}

/*
 * This workitem de-allocates fragments that were replaced during
 * file block allocation.
 */
static void 
handle_workitem_freefrag(freefrag)
      struct freefrag *freefrag;
{
      struct ufsmount *ump = VFSTOUFS(freefrag->ff_list.wk_mp);

      ffs_blkfree(ump, ump->um_fs, ump->um_devvp, freefrag->ff_blkno,
          freefrag->ff_fragsize, freefrag->ff_inum);
      ACQUIRE_LOCK(&lk);
      WORKITEM_FREE(freefrag, D_FREEFRAG);
      FREE_LOCK(&lk);
}

/*
 * Set up a dependency structure for an external attributes data block.
 * This routine follows much of the structure of softdep_setup_allocdirect.
 * See the description of softdep_setup_allocdirect above for details.
 */
void 
softdep_setup_allocext(ip, lbn, newblkno, oldblkno, newsize, oldsize, bp)
      struct inode *ip;
      ufs_lbn_t lbn;
      ufs2_daddr_t newblkno;
      ufs2_daddr_t oldblkno;
      long newsize;
      long oldsize;
      struct buf *bp;
{
      struct allocdirect *adp, *oldadp;
      struct allocdirectlst *adphead;
      struct bmsafemap *bmsafemap;
      struct inodedep *inodedep;
      struct newblk *newblk;
      struct mount *mp;

      mp = UFSTOVFS(ip->i_ump);
      MALLOC(adp, struct allocdirect *, sizeof(struct allocdirect),
            M_ALLOCDIRECT, M_SOFTDEP_FLAGS|M_ZERO);
      workitem_alloc(&adp->ad_list, D_ALLOCDIRECT, mp);
      adp->ad_lbn = lbn;
      adp->ad_newblkno = newblkno;
      adp->ad_oldblkno = oldblkno;
      adp->ad_newsize = newsize;
      adp->ad_oldsize = oldsize;
      adp->ad_state = ATTACHED | EXTDATA;
      LIST_INIT(&adp->ad_newdirblk);
      if (newblkno == oldblkno)
            adp->ad_freefrag = NULL;
      else
            adp->ad_freefrag = newfreefrag(ip, oldblkno, oldsize);

      ACQUIRE_LOCK(&lk);
      if (newblk_lookup(ip->i_fs, newblkno, 0, &newblk) == 0)
            panic("softdep_setup_allocext: lost block");

      inodedep_lookup(mp, ip->i_number, DEPALLOC | NODELAY, &inodedep);
      adp->ad_inodedep = inodedep;

      if (newblk->nb_state == DEPCOMPLETE) {
            adp->ad_state |= DEPCOMPLETE;
            adp->ad_buf = NULL;
      } else {
            bmsafemap = newblk->nb_bmsafemap;
            adp->ad_buf = bmsafemap->sm_buf;
            LIST_REMOVE(newblk, nb_deps);
            LIST_INSERT_HEAD(&bmsafemap->sm_allocdirecthd, adp, ad_deps);
      }
      LIST_REMOVE(newblk, nb_hash);
      FREE(newblk, M_NEWBLK);

      WORKLIST_INSERT(&bp->b_dep, &adp->ad_list);
      if (lbn >= NXADDR)
            panic("softdep_setup_allocext: lbn %lld > NXADDR",
                (long long)lbn);
      /*
       * The list of allocdirects must be kept in sorted and ascending
       * order so that the rollback routines can quickly determine the
       * first uncommitted block (the size of the file stored on disk
       * ends at the end of the lowest committed fragment, or if there
       * are no fragments, at the end of the highest committed block).
       * Since files generally grow, the typical case is that the new
       * block is to be added at the end of the list. We speed this
       * special case by checking against the last allocdirect in the
       * list before laboriously traversing the list looking for the
       * insertion point.
       */
      adphead = &inodedep->id_newextupdt;
      oldadp = TAILQ_LAST(adphead, allocdirectlst);
      if (oldadp == NULL || oldadp->ad_lbn <= lbn) {
            /* insert at end of list */
            TAILQ_INSERT_TAIL(adphead, adp, ad_next);
            if (oldadp != NULL && oldadp->ad_lbn == lbn)
                  allocdirect_merge(adphead, adp, oldadp);
            FREE_LOCK(&lk);
            return;
      }
      TAILQ_FOREACH(oldadp, adphead, ad_next) {
            if (oldadp->ad_lbn >= lbn)
                  break;
      }
      if (oldadp == NULL)
            panic("softdep_setup_allocext: lost entry");
      /* insert in middle of list */
      TAILQ_INSERT_BEFORE(oldadp, adp, ad_next);
      if (oldadp->ad_lbn == lbn)
            allocdirect_merge(adphead, adp, oldadp);
      FREE_LOCK(&lk);
}

/*
 * Indirect block allocation dependencies.
 * 
 * The same dependencies that exist for a direct block also exist when
 * a new block is allocated and pointed to by an entry in a block of
 * indirect pointers. The undo/redo states described above are also
 * used here. Because an indirect block contains many pointers that
 * may have dependencies, a second copy of the entire in-memory indirect
 * block is kept. The buffer cache copy is always completely up-to-date.
 * The second copy, which is used only as a source for disk writes,
 * contains only the safe pointers (i.e., those that have no remaining
 * update dependencies). The second copy is freed when all pointers
 * are safe. The cache is not allowed to replace indirect blocks with
 * pending update dependencies. If a buffer containing an indirect
 * block with dependencies is written, these routines will mark it
 * dirty again. It can only be successfully written once all the
 * dependencies are removed. The ffs_fsync routine in conjunction with
 * softdep_sync_metadata work together to get all the dependencies
 * removed so that a file can be successfully written to disk. Three
 * procedures are used when setting up indirect block pointer
 * dependencies. The division is necessary because of the organization
 * of the "balloc" routine and because of the distinction between file
 * pages and file metadata blocks.
 */

/*
 * Allocate a new allocindir structure.
 */
static struct allocindir *
newallocindir(ip, ptrno, newblkno, oldblkno)
      struct inode *ip; /* inode for file being extended */
      int ptrno;        /* offset of pointer in indirect block */
      ufs2_daddr_t newblkno;  /* disk block number being added */
      ufs2_daddr_t oldblkno;  /* previous block number, 0 if none */
{
      struct allocindir *aip;

      MALLOC(aip, struct allocindir *, sizeof(struct allocindir),
            M_ALLOCINDIR, M_SOFTDEP_FLAGS|M_ZERO);
      workitem_alloc(&aip->ai_list, D_ALLOCINDIR, UFSTOVFS(ip->i_ump));
      aip->ai_state = ATTACHED;
      aip->ai_offset = ptrno;
      aip->ai_newblkno = newblkno;
      aip->ai_oldblkno = oldblkno;
      aip->ai_freefrag = newfreefrag(ip, oldblkno, ip->i_fs->fs_bsize);
      return (aip);
}

/*
 * Called just before setting an indirect block pointer
 * to a newly allocated file page.
 */
void
softdep_setup_allocindir_page(ip, lbn, bp, ptrno, newblkno, oldblkno, nbp)
      struct inode *ip; /* inode for file being extended */
      ufs_lbn_t lbn;          /* allocated block number within file */
      struct buf *bp;         /* buffer with indirect blk referencing page */
      int ptrno;        /* offset of pointer in indirect block */
      ufs2_daddr_t newblkno;  /* disk block number being added */
      ufs2_daddr_t oldblkno;  /* previous block number, 0 if none */
      struct buf *nbp;  /* buffer holding allocated page */
{
      struct allocindir *aip;
      struct pagedep *pagedep;

      ASSERT_VOP_LOCKED(ITOV(ip), "softdep_setup_allocindir_page");
      aip = newallocindir(ip, ptrno, newblkno, oldblkno);
      ACQUIRE_LOCK(&lk);
      /*
       * If we are allocating a directory page, then we must
       * allocate an associated pagedep to track additions and
       * deletions.
       */
      if ((ip->i_mode & IFMT) == IFDIR &&
          pagedep_lookup(ip, lbn, DEPALLOC, &pagedep) == 0)
            WORKLIST_INSERT(&nbp->b_dep, &pagedep->pd_list);
      WORKLIST_INSERT(&nbp->b_dep, &aip->ai_list);
      setup_allocindir_phase2(bp, ip, aip);
      FREE_LOCK(&lk);
}

/*
 * Called just before setting an indirect block pointer to a
 * newly allocated indirect block.
 */
void
softdep_setup_allocindir_meta(nbp, ip, bp, ptrno, newblkno)
      struct buf *nbp;  /* newly allocated indirect block */
      struct inode *ip; /* inode for file being extended */
      struct buf *bp;         /* indirect block referencing allocated block */
      int ptrno;        /* offset of pointer in indirect block */
      ufs2_daddr_t newblkno;  /* disk block number being added */
{
      struct allocindir *aip;

      ASSERT_VOP_LOCKED(ITOV(ip), "softdep_setup_allocindir_meta");
      aip = newallocindir(ip, ptrno, newblkno, 0);
      ACQUIRE_LOCK(&lk);
      WORKLIST_INSERT(&nbp->b_dep, &aip->ai_list);
      setup_allocindir_phase2(bp, ip, aip);
      FREE_LOCK(&lk);
}

/*
 * Called to finish the allocation of the "aip" allocated
 * by one of the two routines above.
 */
static void 
setup_allocindir_phase2(bp, ip, aip)
      struct buf *bp;         /* in-memory copy of the indirect block */
      struct inode *ip; /* inode for file being extended */
      struct allocindir *aip; /* allocindir allocated by the above routines */
{
      struct worklist *wk;
      struct indirdep *indirdep, *newindirdep;
      struct bmsafemap *bmsafemap;
      struct allocindir *oldaip;
      struct freefrag *freefrag;
      struct newblk *newblk;
      ufs2_daddr_t blkno;

      mtx_assert(&lk, MA_OWNED);
      if (bp->b_lblkno >= 0)
            panic("setup_allocindir_phase2: not indir blk");
      for (indirdep = NULL, newindirdep = NULL; ; ) {
            LIST_FOREACH(wk, &bp->b_dep, wk_list) {
                  if (wk->wk_type != D_INDIRDEP)
                        continue;
                  indirdep = WK_INDIRDEP(wk);
                  break;
            }
            if (indirdep == NULL && newindirdep) {
                  indirdep = newindirdep;
                  WORKLIST_INSERT(&bp->b_dep, &indirdep->ir_list);
                  newindirdep = NULL;
            }
            if (indirdep) {
                  if (newblk_lookup(ip->i_fs, aip->ai_newblkno, 0,
                      &newblk) == 0)
                        panic("setup_allocindir: lost block");
                  if (newblk->nb_state == DEPCOMPLETE) {
                        aip->ai_state |= DEPCOMPLETE;
                        aip->ai_buf = NULL;
                  } else {
                        bmsafemap = newblk->nb_bmsafemap;
                        aip->ai_buf = bmsafemap->sm_buf;
                        LIST_REMOVE(newblk, nb_deps);
                        LIST_INSERT_HEAD(&bmsafemap->sm_allocindirhd,
                            aip, ai_deps);
                  }
                  LIST_REMOVE(newblk, nb_hash);
                  FREE(newblk, M_NEWBLK);
                  aip->ai_indirdep = indirdep;
                  /*
                   * Check to see if there is an existing dependency
                   * for this block. If there is, merge the old
                   * dependency into the new one.
                   */
                  if (aip->ai_oldblkno == 0)
                        oldaip = NULL;
                  else

                        LIST_FOREACH(oldaip, &indirdep->ir_deplisthd, ai_next)
                              if (oldaip->ai_offset == aip->ai_offset)
                                    break;
                  freefrag = NULL;
                  if (oldaip != NULL) {
                        if (oldaip->ai_newblkno != aip->ai_oldblkno)
                              panic("setup_allocindir_phase2: blkno");
                        aip->ai_oldblkno = oldaip->ai_oldblkno;
                        freefrag = aip->ai_freefrag;
                        aip->ai_freefrag = oldaip->ai_freefrag;
                        oldaip->ai_freefrag = NULL;
                        free_allocindir(oldaip, NULL);
                  }
                  LIST_INSERT_HEAD(&indirdep->ir_deplisthd, aip, ai_next);
                  if (ip->i_ump->um_fstype == UFS1)
                        ((ufs1_daddr_t *)indirdep->ir_savebp->b_data)
                            [aip->ai_offset] = aip->ai_oldblkno;
                  else
                        ((ufs2_daddr_t *)indirdep->ir_savebp->b_data)
                            [aip->ai_offset] = aip->ai_oldblkno;
                  FREE_LOCK(&lk);
                  if (freefrag != NULL)
                        handle_workitem_freefrag(freefrag);
            } else
                  FREE_LOCK(&lk);
            if (newindirdep) {
                  newindirdep->ir_savebp->b_flags |= B_INVAL | B_NOCACHE;
                  brelse(newindirdep->ir_savebp);
                  ACQUIRE_LOCK(&lk);
                  WORKITEM_FREE((caddr_t)newindirdep, D_INDIRDEP);
                  if (indirdep)
                        break;
                  FREE_LOCK(&lk);
            }
            if (indirdep) {
                  ACQUIRE_LOCK(&lk);
                  break;
            }
            MALLOC(newindirdep, struct indirdep *, sizeof(struct indirdep),
                  M_INDIRDEP, M_SOFTDEP_FLAGS);
            workitem_alloc(&newindirdep->ir_list, D_INDIRDEP,
                UFSTOVFS(ip->i_ump));
            newindirdep->ir_state = ATTACHED;
            if (ip->i_ump->um_fstype == UFS1)
                  newindirdep->ir_state |= UFS1FMT;
            LIST_INIT(&newindirdep->ir_deplisthd);
            LIST_INIT(&newindirdep->ir_donehd);
            if (bp->b_blkno == bp->b_lblkno) {
                  ufs_bmaparray(bp->b_vp, bp->b_lblkno, &blkno, bp,
                      NULL, NULL);
                  bp->b_blkno = blkno;
            }
            newindirdep->ir_savebp =
                getblk(ip->i_devvp, bp->b_blkno, bp->b_bcount, 0, 0, 0);
            BUF_KERNPROC(newindirdep->ir_savebp);
            bcopy(bp->b_data, newindirdep->ir_savebp->b_data, bp->b_bcount);
            ACQUIRE_LOCK(&lk);
      }
}

/*
 * Block de-allocation dependencies.
 * 
 * When blocks are de-allocated, the on-disk pointers must be nullified before
 * the blocks are made available for use by other files.  (The true
 * requirement is that old pointers must be nullified before new on-disk
 * pointers are set.  We chose this slightly more stringent requirement to
 * reduce complexity.) Our implementation handles this dependency by updating
 * the inode (or indirect block) appropriately but delaying the actual block
 * de-allocation (i.e., freemap and free space count manipulation) until
 * after the updated versions reach stable storage.  After the disk is
 * updated, the blocks can be safely de-allocated whenever it is convenient.
 * This implementation handles only the common case of reducing a file's
 * length to zero. Other cases are handled by the conventional synchronous
 * write approach.
 *
 * The ffs implementation with which we worked double-checks
 * the state of the block pointers and file size as it reduces
 * a file's length.  Some of this code is replicated here in our
 * soft updates implementation.  The freeblks->fb_chkcnt field is
 * used to transfer a part of this information to the procedure
 * that eventually de-allocates the blocks.
 *
 * This routine should be called from the routine that shortens
 * a file's length, before the inode's size or block pointers
 * are modified. It will save the block pointer information for
 * later release and zero the inode so that the calling routine
 * can release it.
 */
void
softdep_setup_freeblocks(ip, length, flags)
      struct inode *ip; /* The inode whose length is to be reduced */
      off_t length;           /* The new length for the file */
      int flags;        /* IO_EXT and/or IO_NORMAL */
{
      struct freeblks *freeblks;
      struct inodedep *inodedep;
      struct allocdirect *adp;
      struct vnode *vp;
      struct buf *bp;
      struct fs *fs;
      ufs2_daddr_t extblocks, datablocks;
      struct mount *mp;
      int i, delay, error;

      fs = ip->i_fs;
      mp = UFSTOVFS(ip->i_ump);
      if (length != 0)
            panic("softdep_setup_freeblocks: non-zero length");
      MALLOC(freeblks, struct freeblks *, sizeof(struct freeblks),
            M_FREEBLKS, M_SOFTDEP_FLAGS|M_ZERO);
      workitem_alloc(&freeblks->fb_list, D_FREEBLKS, mp);
      freeblks->fb_state = ATTACHED;
      freeblks->fb_uid = ip->i_uid;
      freeblks->fb_previousinum = ip->i_number;
      freeblks->fb_devvp = ip->i_devvp;
      extblocks = 0;
      if (fs->fs_magic == FS_UFS2_MAGIC)
            extblocks = btodb(fragroundup(fs, ip->i_din2->di_extsize));
      datablocks = DIP(ip, i_blocks) - extblocks;
      if ((flags & IO_NORMAL) == 0) {
            freeblks->fb_oldsize = 0;
            freeblks->fb_chkcnt = 0;
      } else {
            freeblks->fb_oldsize = ip->i_size;
            ip->i_size = 0;
            DIP_SET(ip, i_size, 0);
            freeblks->fb_chkcnt = datablocks;
            for (i = 0; i < NDADDR; i++) {
                  freeblks->fb_dblks[i] = DIP(ip, i_db[i]);
                  DIP_SET(ip, i_db[i], 0);
            }
            for (i = 0; i < NIADDR; i++) {
                  freeblks->fb_iblks[i] = DIP(ip, i_ib[i]);
                  DIP_SET(ip, i_ib[i], 0);
            }
            /*
             * If the file was removed, then the space being freed was
             * accounted for then (see softdep_releasefile()). If the
             * file is merely being truncated, then we account for it now.
             */
            if ((ip->i_flag & IN_SPACECOUNTED) == 0) {
                  UFS_LOCK(ip->i_ump);
                  fs->fs_pendingblocks += datablocks;
                  UFS_UNLOCK(ip->i_ump);
            }
      }
      if ((flags & IO_EXT) == 0) {
            freeblks->fb_oldextsize = 0;
      } else {
            freeblks->fb_oldextsize = ip->i_din2->di_extsize;
            ip->i_din2->di_extsize = 0;
            freeblks->fb_chkcnt += extblocks;
            for (i = 0; i < NXADDR; i++) {
                  freeblks->fb_eblks[i] = ip->i_din2->di_extb[i];
                  ip->i_din2->di_extb[i] = 0;
            }
      }
      DIP_SET(ip, i_blocks, DIP(ip, i_blocks) - freeblks->fb_chkcnt);
      /*
       * Push the zero'ed inode to to its disk buffer so that we are free
       * to delete its dependencies below. Once the dependencies are gone
       * the buffer can be safely released.
       */
      if ((error = bread(ip->i_devvp,
          fsbtodb(fs, ino_to_fsba(fs, ip->i_number)),
          (int)fs->fs_bsize, NOCRED, &bp)) != 0) {
            brelse(bp);
            softdep_error("softdep_setup_freeblocks", error);
      }
      if (ip->i_ump->um_fstype == UFS1)
            *((struct ufs1_dinode *)bp->b_data +
                ino_to_fsbo(fs, ip->i_number)) = *ip->i_din1;
      else
            *((struct ufs2_dinode *)bp->b_data +
                ino_to_fsbo(fs, ip->i_number)) = *ip->i_din2;
      /*
       * Find and eliminate any inode dependencies.
       */
      ACQUIRE_LOCK(&lk);
      (void) inodedep_lookup(mp, ip->i_number, DEPALLOC, &inodedep);
      if ((inodedep->id_state & IOSTARTED) != 0)
            panic("softdep_setup_freeblocks: inode busy");
      /*
       * Add the freeblks structure to the list of operations that
       * must await the zero'ed inode being written to disk. If we
       * still have a bitmap dependency (delay == 0), then the inode
       * has never been written to disk, so we can process the
       * freeblks below once we have deleted the dependencies.
       */
      delay = (inodedep->id_state & DEPCOMPLETE);
      if (delay)
            WORKLIST_INSERT(&inodedep->id_bufwait, &freeblks->fb_list);
      /*
       * Because the file length has been truncated to zero, any
       * pending block allocation dependency structures associated
       * with this inode are obsolete and can simply be de-allocated.
       * We must first merge the two dependency lists to get rid of
       * any duplicate freefrag structures, then purge the merged list.
       * If we still have a bitmap dependency, then the inode has never
       * been written to disk, so we can free any fragments without delay.
       */
      if (flags & IO_NORMAL) {
            merge_inode_lists(&inodedep->id_newinoupdt,
                &inodedep->id_inoupdt);
            while ((adp = TAILQ_FIRST(&inodedep->id_inoupdt)) != 0)
                  free_allocdirect(&inodedep->id_inoupdt, adp, delay);
      }
      if (flags & IO_EXT) {
            merge_inode_lists(&inodedep->id_newextupdt,
                &inodedep->id_extupdt);
            while ((adp = TAILQ_FIRST(&inodedep->id_extupdt)) != 0)
                  free_allocdirect(&inodedep->id_extupdt, adp, delay);
      }
      FREE_LOCK(&lk);
      bdwrite(bp);
      /*
       * We must wait for any I/O in progress to finish so that
       * all potential buffers on the dirty list will be visible.
       * Once they are all there, walk the list and get rid of
       * any dependencies.
       */
      vp = ITOV(ip);
      VI_LOCK(vp);
      drain_output(vp);
restart:
      TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs) {
            if (((flags & IO_EXT) == 0 && (bp->b_xflags & BX_ALTDATA)) ||
                ((flags & IO_NORMAL) == 0 &&
                  (bp->b_xflags & BX_ALTDATA) == 0))
                  continue;
            if ((bp = getdirtybuf(bp, VI_MTX(vp), MNT_WAIT)) == NULL)
                  goto restart;
            VI_UNLOCK(vp);
            ACQUIRE_LOCK(&lk);
            (void) inodedep_lookup(mp, ip->i_number, 0, &inodedep);
            deallocate_dependencies(bp, inodedep);
            FREE_LOCK(&lk);
            bp->b_flags |= B_INVAL | B_NOCACHE;
            brelse(bp);
            VI_LOCK(vp);
            goto restart;
      }
      VI_UNLOCK(vp);
      ACQUIRE_LOCK(&lk);
      if (inodedep_lookup(mp, ip->i_number, 0, &inodedep) != 0)
            (void) free_inodedep(inodedep);

      if(delay) {
            freeblks->fb_state |= DEPCOMPLETE;
            /*
             * If the inode with zeroed block pointers is now on disk
             * we can start freeing blocks. Add freeblks to the worklist
             * instead of calling  handle_workitem_freeblocks directly as
             * it is more likely that additional IO is needed to complete
             * the request here than in the !delay case.
             */  
            if ((freeblks->fb_state & ALLCOMPLETE) == ALLCOMPLETE)
                  add_to_worklist(&freeblks->fb_list);
      }

      FREE_LOCK(&lk);
      /*
       * If the inode has never been written to disk (delay == 0),
       * then we can process the freeblks now that we have deleted
       * the dependencies.
       */
      if (!delay)
            handle_workitem_freeblocks(freeblks, 0);
}

/*
 * Reclaim any dependency structures from a buffer that is about to
 * be reallocated to a new vnode. The buffer must be locked, thus,
 * no I/O completion operations can occur while we are manipulating
 * its associated dependencies. The mutex is held so that other I/O's
 * associated with related dependencies do not occur.
 */
static void
deallocate_dependencies(bp, inodedep)
      struct buf *bp;
      struct inodedep *inodedep;
{
      struct worklist *wk;
      struct indirdep *indirdep;
      struct allocindir *aip;
      struct pagedep *pagedep;
      struct dirrem *dirrem;
      struct diradd *dap;
      int i;

      mtx_assert(&lk, MA_OWNED);
      while ((wk = LIST_FIRST(&bp->b_dep)) != NULL) {
            switch (wk->wk_type) {

            case D_INDIRDEP:
                  indirdep = WK_INDIRDEP(wk);
                  /*
                   * None of the indirect pointers will ever be visible,
                   * so they can simply be tossed. GOINGAWAY ensures
                   * that allocated pointers will be saved in the buffer
                   * cache until they are freed. Note that they will
                   * only be able to be found by their physical address
                   * since the inode mapping the logical address will
                   * be gone. The save buffer used for the safe copy
                   * was allocated in setup_allocindir_phase2 using
                   * the physical address so it could be used for this
                   * purpose. Hence we swap the safe copy with the real
                   * copy, allowing the safe copy to be freed and holding
                   * on to the real copy for later use in indir_trunc.
                   */
                  if (indirdep->ir_state & GOINGAWAY)
                        panic("deallocate_dependencies: already gone");
                  indirdep->ir_state |= GOINGAWAY;
                  VFSTOUFS(bp->b_vp->v_mount)->um_numindirdeps += 1;
                  while ((aip = LIST_FIRST(&indirdep->ir_deplisthd)) != 0)
                        free_allocindir(aip, inodedep);
                  if (bp->b_lblkno >= 0 ||
                      bp->b_blkno != indirdep->ir_savebp->b_lblkno)
                        panic("deallocate_dependencies: not indir");
                  bcopy(bp->b_data, indirdep->ir_savebp->b_data,
                      bp->b_bcount);
                  WORKLIST_REMOVE(wk);
                  WORKLIST_INSERT(&indirdep->ir_savebp->b_dep, wk);
                  continue;

            case D_PAGEDEP:
                  pagedep = WK_PAGEDEP(wk);
                  /*
                   * None of the directory additions will ever be
                   * visible, so they can simply be tossed.
                   */
                  for (i = 0; i < DAHASHSZ; i++)
                        while ((dap =
                            LIST_FIRST(&pagedep->pd_diraddhd[i])))
                              free_diradd(dap);
                  while ((dap = LIST_FIRST(&pagedep->pd_pendinghd)) != 0)
                        free_diradd(dap);
                  /*
                   * Copy any directory remove dependencies to the list
                   * to be processed after the zero'ed inode is written.
                   * If the inode has already been written, then they 
                   * can be dumped directly onto the work list.
                   */
                  LIST_FOREACH(dirrem, &pagedep->pd_dirremhd, dm_next) {
                        LIST_REMOVE(dirrem, dm_next);
                        dirrem->dm_dirinum = pagedep->pd_ino;
                        if (inodedep == NULL ||
                            (inodedep->id_state & ALLCOMPLETE) ==
                             ALLCOMPLETE)
                              add_to_worklist(&dirrem->dm_list);
                        else
                              WORKLIST_INSERT(&inodedep->id_bufwait,
                                  &dirrem->dm_list);
                  }
                  if ((pagedep->pd_state & NEWBLOCK) != 0) {
                        LIST_FOREACH(wk, &inodedep->id_bufwait, wk_list)
                              if (wk->wk_type == D_NEWDIRBLK &&
                                  WK_NEWDIRBLK(wk)->db_pagedep ==
                                    pagedep)
                                    break;
                        if (wk != NULL) {
                              WORKLIST_REMOVE(wk);
                              free_newdirblk(WK_NEWDIRBLK(wk));
                        } else
                              panic("deallocate_dependencies: "
                                    "lost pagedep");
                  }
                  WORKLIST_REMOVE(&pagedep->pd_list);
                  LIST_REMOVE(pagedep, pd_hash);
                  WORKITEM_FREE(pagedep, D_PAGEDEP);
                  continue;

            case D_ALLOCINDIR:
                  free_allocindir(WK_ALLOCINDIR(wk), inodedep);
                  continue;

            case D_ALLOCDIRECT:
            case D_INODEDEP:
                  panic("deallocate_dependencies: Unexpected type %s",
                      TYPENAME(wk->wk_type));
                  /* NOTREACHED */

            default:
                  panic("deallocate_dependencies: Unknown type %s",
                      TYPENAME(wk->wk_type));
                  /* NOTREACHED */
            }
      }
}

/*
 * Free an allocdirect. Generate a new freefrag work request if appropriate.
 * This routine must be called with splbio interrupts blocked.
 */
static void
free_allocdirect(adphead, adp, delay)
      struct allocdirectlst *adphead;
      struct allocdirect *adp;
      int delay;
{
      struct newdirblk *newdirblk;
      struct worklist *wk;

      mtx_assert(&lk, MA_OWNED);
      if ((adp->ad_state & DEPCOMPLETE) == 0)
            LIST_REMOVE(adp, ad_deps);
      TAILQ_REMOVE(adphead, adp, ad_next);
      if ((adp->ad_state & COMPLETE) == 0)
            WORKLIST_REMOVE(&adp->ad_list);
      if (adp->ad_freefrag != NULL) {
            if (delay)
                  WORKLIST_INSERT(&adp->ad_inodedep->id_bufwait,
                      &adp->ad_freefrag->ff_list);
            else
                  add_to_worklist(&adp->ad_freefrag->ff_list);
      }
      if ((wk = LIST_FIRST(&adp->ad_newdirblk)) != NULL) {
            newdirblk = WK_NEWDIRBLK(wk);
            WORKLIST_REMOVE(&newdirblk->db_list);
            if (!LIST_EMPTY(&adp->ad_newdirblk))
                  panic("free_allocdirect: extra newdirblk");
            if (delay)
                  WORKLIST_INSERT(&adp->ad_inodedep->id_bufwait,
                      &newdirblk->db_list);
            else
                  free_newdirblk(newdirblk);
      }
      WORKITEM_FREE(adp, D_ALLOCDIRECT);
}

/*
 * Free a newdirblk. Clear the NEWBLOCK flag on its associated pagedep.
 * This routine must be called with splbio interrupts blocked.
 */
static void
free_newdirblk(newdirblk)
      struct newdirblk *newdirblk;
{
      struct pagedep *pagedep;
      struct diradd *dap;
      int i;

      mtx_assert(&lk, MA_OWNED);
      /*
       * If the pagedep is still linked onto the directory buffer
       * dependency chain, then some of the entries on the
       * pd_pendinghd list may not be committed to disk yet. In
       * this case, we will simply clear the NEWBLOCK flag and
       * let the pd_pendinghd list be processed when the pagedep
       * is next written. If the pagedep is no longer on the buffer
       * dependency chain, then all the entries on the pd_pending
       * list are committed to disk and we can free them here.
       */
      pagedep = newdirblk->db_pagedep;
      pagedep->pd_state &= ~NEWBLOCK;
      if ((pagedep->pd_state & ONWORKLIST) == 0)
            while ((dap = LIST_FIRST(&pagedep->pd_pendinghd)) != NULL)
                  free_diradd(dap);
      /*
       * If no dependencies remain, the pagedep will be freed.
       */
      for (i = 0; i < DAHASHSZ; i++)
            if (!LIST_EMPTY(&pagedep->pd_diraddhd[i]))
                  break;
      if (i == DAHASHSZ && (pagedep->pd_state & ONWORKLIST) == 0) {
            LIST_REMOVE(pagedep, pd_hash);
            WORKITEM_FREE(pagedep, D_PAGEDEP);
      }
      WORKITEM_FREE(newdirblk, D_NEWDIRBLK);
}

/*
 * Prepare an inode to be freed. The actual free operation is not
 * done until the zero'ed inode has been written to disk.
 */
void
softdep_freefile(pvp, ino, mode)
      struct vnode *pvp;
      ino_t ino;
      int mode;
{
      struct inode *ip = VTOI(pvp);
      struct inodedep *inodedep;
      struct freefile *freefile;

      /*
       * This sets up the inode de-allocation dependency.
       */
      MALLOC(freefile, struct freefile *, sizeof(struct freefile),
            M_FREEFILE, M_SOFTDEP_FLAGS);
      workitem_alloc(&freefile->fx_list, D_FREEFILE, pvp->v_mount);
      freefile->fx_mode = mode;
      freefile->fx_oldinum = ino;
      freefile->fx_devvp = ip->i_devvp;
      if ((ip->i_flag & IN_SPACECOUNTED) == 0) {
            UFS_LOCK(ip->i_ump);
            ip->i_fs->fs_pendinginodes += 1;
            UFS_UNLOCK(ip->i_ump);
      }

      /*
       * If the inodedep does not exist, then the zero'ed inode has
       * been written to disk. If the allocated inode has never been
       * written to disk, then the on-disk inode is zero'ed. In either
       * case we can free the file immediately.
       */
      ACQUIRE_LOCK(&lk);
      if (inodedep_lookup(pvp->v_mount, ino, 0, &inodedep) == 0 ||
          check_inode_unwritten(inodedep)) {
            FREE_LOCK(&lk);
            handle_workitem_freefile(freefile);
            return;
      }
      WORKLIST_INSERT(&inodedep->id_inowait, &freefile->fx_list);
      FREE_LOCK(&lk);
      ip->i_flag |= IN_MODIFIED;
}

/*
 * Check to see if an inode has never been written to disk. If
 * so free the inodedep and return success, otherwise return failure.
 * This routine must be called with splbio interrupts blocked.
 *
 * If we still have a bitmap dependency, then the inode has never
 * been written to disk. Drop the dependency as it is no longer
 * necessary since the inode is being deallocated. We set the
 * ALLCOMPLETE flags since the bitmap now properly shows that the
 * inode is not allocated. Even if the inode is actively being
 * written, it has been rolled back to its zero'ed state, so we
 * are ensured that a zero inode is what is on the disk. For short
 * lived files, this change will usually result in removing all the
 * dependencies from the inode so that it can be freed immediately.
 */
static int
check_inode_unwritten(inodedep)
      struct inodedep *inodedep;
{

      mtx_assert(&lk, MA_OWNED);
      if ((inodedep->id_state & DEPCOMPLETE) != 0 ||
          !LIST_EMPTY(&inodedep->id_pendinghd) ||
          !LIST_EMPTY(&inodedep->id_bufwait) ||
          !LIST_EMPTY(&inodedep->id_inowait) ||
          !TAILQ_EMPTY(&inodedep->id_inoupdt) ||
          !TAILQ_EMPTY(&inodedep->id_newinoupdt) ||
          !TAILQ_EMPTY(&inodedep->id_extupdt) ||
          !TAILQ_EMPTY(&inodedep->id_newextupdt) ||
          inodedep->id_nlinkdelta != 0)
            return (0);

      /*
       * Another process might be in initiate_write_inodeblock_ufs[12]
       * trying to allocate memory without holding "Softdep Lock".
       */
      if ((inodedep->id_state & IOSTARTED) != 0 &&
          inodedep->id_savedino1 == NULL)
            return (0);

      inodedep->id_state |= ALLCOMPLETE;
      LIST_REMOVE(inodedep, id_deps);
      inodedep->id_buf = NULL;
      if (inodedep->id_state & ONWORKLIST)
            WORKLIST_REMOVE(&inodedep->id_list);
      if (inodedep->id_savedino1 != NULL) {
            FREE(inodedep->id_savedino1, M_SAVEDINO);
            inodedep->id_savedino1 = NULL;
      }
      if (free_inodedep(inodedep) == 0)
            panic("check_inode_unwritten: busy inode");
      return (1);
}

/*
 * Try to free an inodedep structure. Return 1 if it could be freed.
 */
static int
free_inodedep(inodedep)
      struct inodedep *inodedep;
{

      mtx_assert(&lk, MA_OWNED);
      if ((inodedep->id_state & ONWORKLIST) != 0 ||
          (inodedep->id_state & ALLCOMPLETE) != ALLCOMPLETE ||
          !LIST_EMPTY(&inodedep->id_pendinghd) ||
          !LIST_EMPTY(&inodedep->id_bufwait) ||
          !LIST_EMPTY(&inodedep->id_inowait) ||
          !TAILQ_EMPTY(&inodedep->id_inoupdt) ||
          !TAILQ_EMPTY(&inodedep->id_newinoupdt) ||
          !TAILQ_EMPTY(&inodedep->id_extupdt) ||
          !TAILQ_EMPTY(&inodedep->id_newextupdt) ||
          inodedep->id_nlinkdelta != 0 || inodedep->id_savedino1 != NULL)
            return (0);
      LIST_REMOVE(inodedep, id_hash);
      WORKITEM_FREE(inodedep, D_INODEDEP);
      num_inodedep -= 1;
      return (1);
}

/*
 * This workitem routine performs the block de-allocation.
 * The workitem is added to the pending list after the updated
 * inode block has been written to disk.  As mentioned above,
 * checks regarding the number of blocks de-allocated (compared
 * to the number of blocks allocated for the file) are also
 * performed in this function.
 */
static void
handle_workitem_freeblocks(freeblks, flags)
      struct freeblks *freeblks;
      int flags;
{
      struct inode *ip;
      struct vnode *vp;
      struct fs *fs;
      struct ufsmount *ump;
      int i, nblocks, level, bsize;
      ufs2_daddr_t bn, blocksreleased = 0;
      int error, allerror = 0;
      ufs_lbn_t baselbns[NIADDR], tmpval;
      int fs_pendingblocks;

      ump = VFSTOUFS(freeblks->fb_list.wk_mp);
      fs = ump->um_fs;
      fs_pendingblocks = 0;
      tmpval = 1;
      baselbns[0] = NDADDR;
      for (i = 1; i < NIADDR; i++) {
            tmpval *= NINDIR(fs);
            baselbns[i] = baselbns[i - 1] + tmpval;
      }
      nblocks = btodb(fs->fs_bsize);
      blocksreleased = 0;
      /*
       * Release all extended attribute blocks or frags.
       */
      if (freeblks->fb_oldextsize > 0) {
            for (i = (NXADDR - 1); i >= 0; i--) {
                  if ((bn = freeblks->fb_eblks[i]) == 0)
                        continue;
                  bsize = sblksize(fs, freeblks->fb_oldextsize, i);
                  ffs_blkfree(ump, fs, freeblks->fb_devvp, bn, bsize,
                      freeblks->fb_previousinum);
                  blocksreleased += btodb(bsize);
            }
      }
      /*
       * Release all data blocks or frags.
       */
      if (freeblks->fb_oldsize > 0) {
            /*
             * Indirect blocks first.
             */
            for (level = (NIADDR - 1); level >= 0; level--) {
                  if ((bn = freeblks->fb_iblks[level]) == 0)
                        continue;
                  if ((error = indir_trunc(freeblks, fsbtodb(fs, bn),
                      level, baselbns[level], &blocksreleased)) != 0)
                        allerror = error;
                  ffs_blkfree(ump, fs, freeblks->fb_devvp, bn,
                      fs->fs_bsize, freeblks->fb_previousinum);
                  fs_pendingblocks += nblocks;
                  blocksreleased += nblocks;
            }
            /*
             * All direct blocks or frags.
             */
            for (i = (NDADDR - 1); i >= 0; i--) {
                  if ((bn = freeblks->fb_dblks[i]) == 0)
                        continue;
                  bsize = sblksize(fs, freeblks->fb_oldsize, i);
                  ffs_blkfree(ump, fs, freeblks->fb_devvp, bn, bsize,
                      freeblks->fb_previousinum);
                  fs_pendingblocks += btodb(bsize);
                  blocksreleased += btodb(bsize);
            }
      }
      UFS_LOCK(ump);
      fs->fs_pendingblocks -= fs_pendingblocks;
      UFS_UNLOCK(ump);
      /*
       * If we still have not finished background cleanup, then check
       * to see if the block count needs to be adjusted.
       */
      if (freeblks->fb_chkcnt != blocksreleased &&
          (fs->fs_flags & FS_UNCLEAN) != 0 &&
          ffs_vget(freeblks->fb_list.wk_mp, freeblks->fb_previousinum,
          (flags & LK_NOWAIT) | LK_EXCLUSIVE, &vp) == 0) {
            ip = VTOI(vp);
            DIP_SET(ip, i_blocks, DIP(ip, i_blocks) + \
                freeblks->fb_chkcnt - blocksreleased);
            ip->i_flag |= IN_CHANGE;
            vput(vp);
      }

#ifdef DIAGNOSTIC
      if (freeblks->fb_chkcnt != blocksreleased &&
          ((fs->fs_flags & FS_UNCLEAN) == 0 || (flags & LK_NOWAIT) != 0))
            printf("handle_workitem_freeblocks: block count\n");
      if (allerror)
            softdep_error("handle_workitem_freeblks", allerror);
#endif /* DIAGNOSTIC */

      ACQUIRE_LOCK(&lk);
      WORKITEM_FREE(freeblks, D_FREEBLKS);
      FREE_LOCK(&lk);
}

/*
 * Release blocks associated with the inode ip and stored in the indirect
 * block dbn. If level is greater than SINGLE, the block is an indirect block
 * and recursive calls to indirtrunc must be used to cleanse other indirect
 * blocks.
 */
static int
indir_trunc(freeblks, dbn, level, lbn, countp)
      struct freeblks *freeblks;
      ufs2_daddr_t dbn;
      int level;
      ufs_lbn_t lbn;
      ufs2_daddr_t *countp;
{
      struct buf *bp;
      struct fs *fs;
      struct worklist *wk;
      struct indirdep *indirdep;
      struct ufsmount *ump;
      ufs1_daddr_t *bap1 = 0;
      ufs2_daddr_t nb, *bap2 = 0;
      ufs_lbn_t lbnadd;
      int i, nblocks, ufs1fmt;
      int error, allerror = 0;
      int fs_pendingblocks;

      ump = VFSTOUFS(freeblks->fb_list.wk_mp);
      fs = ump->um_fs;
      fs_pendingblocks = 0;
      lbnadd = 1;
      for (i = level; i > 0; i--)
            lbnadd *= NINDIR(fs);
      /*
       * Get buffer of block pointers to be freed. This routine is not
       * called until the zero'ed inode has been written, so it is safe
       * to free blocks as they are encountered. Because the inode has
       * been zero'ed, calls to bmap on these blocks will fail. So, we
       * have to use the on-disk address and the block device for the
       * filesystem to look them up. If the file was deleted before its
       * indirect blocks were all written to disk, the routine that set
       * us up (deallocate_dependencies) will have arranged to leave
       * a complete copy of the indirect block in memory for our use.
       * Otherwise we have to read the blocks in from the disk.
       */
#ifdef notyet
      bp = getblk(freeblks->fb_devvp, dbn, (int)fs->fs_bsize, 0, 0,
          GB_NOCREAT);
#else
      bp = incore(&freeblks->fb_devvp->v_bufobj, dbn);
#endif
      ACQUIRE_LOCK(&lk);
      if (bp != NULL && (wk = LIST_FIRST(&bp->b_dep)) != NULL) {
            if (wk->wk_type != D_INDIRDEP ||
                (indirdep = WK_INDIRDEP(wk))->ir_savebp != bp ||
                (indirdep->ir_state & GOINGAWAY) == 0)
                  panic("indir_trunc: lost indirdep");
            WORKLIST_REMOVE(wk);
            WORKITEM_FREE(indirdep, D_INDIRDEP);
            if (!LIST_EMPTY(&bp->b_dep))
                  panic("indir_trunc: dangling dep");
            ump->um_numindirdeps -= 1;
            FREE_LOCK(&lk);
      } else {
#ifdef notyet
            if (bp)
                  brelse(bp);
#endif
            FREE_LOCK(&lk);
            error = bread(freeblks->fb_devvp, dbn, (int)fs->fs_bsize,
                NOCRED, &bp);
            if (error) {
                  brelse(bp);
                  return (error);
            }
      }
      /*
       * Recursively free indirect blocks.
       */
      if (ump->um_fstype == UFS1) {
            ufs1fmt = 1;
            bap1 = (ufs1_daddr_t *)bp->b_data;
      } else {
            ufs1fmt = 0;
            bap2 = (ufs2_daddr_t *)bp->b_data;
      }
      nblocks = btodb(fs->fs_bsize);
      for (i = NINDIR(fs) - 1; i >= 0; i--) {
            if (ufs1fmt)
                  nb = bap1[i];
            else
                  nb = bap2[i];
            if (nb == 0)
                  continue;
            if (level != 0) {
                  if ((error = indir_trunc(freeblks, fsbtodb(fs, nb),
                       level - 1, lbn + (i * lbnadd), countp)) != 0)
                        allerror = error;
            }
            ffs_blkfree(ump, fs, freeblks->fb_devvp, nb, fs->fs_bsize,
                freeblks->fb_previousinum);
            fs_pendingblocks += nblocks;
            *countp += nblocks;
      }
      UFS_LOCK(ump);
      fs->fs_pendingblocks -= fs_pendingblocks;
      UFS_UNLOCK(ump);
      bp->b_flags |= B_INVAL | B_NOCACHE;
      brelse(bp);
      return (allerror);
}

/*
 * Free an allocindir.
 * This routine must be called with splbio interrupts blocked.
 */
static void
free_allocindir(aip, inodedep)
      struct allocindir *aip;
      struct inodedep *inodedep;
{
      struct freefrag *freefrag;

      mtx_assert(&lk, MA_OWNED);
      if ((aip->ai_state & DEPCOMPLETE) == 0)
            LIST_REMOVE(aip, ai_deps);
      if (aip->ai_state & ONWORKLIST)
            WORKLIST_REMOVE(&aip->ai_list);
      LIST_REMOVE(aip, ai_next);
      if ((freefrag = aip->ai_freefrag) != NULL) {
            if (inodedep == NULL)
                  add_to_worklist(&freefrag->ff_list);
            else
                  WORKLIST_INSERT(&inodedep->id_bufwait,
                      &freefrag->ff_list);
      }
      WORKITEM_FREE(aip, D_ALLOCINDIR);
}

/*
 * Directory entry addition dependencies.
 * 
 * When adding a new directory entry, the inode (with its incremented link
 * count) must be written to disk before the directory entry's pointer to it.
 * Also, if the inode is newly allocated, the corresponding freemap must be
 * updated (on disk) before the directory entry's pointer. These requirements
 * are met via undo/redo on the directory entry's pointer, which consists
 * simply of the inode number.
 * 
 * As directory entries are added and deleted, the free space within a
 * directory block can become fragmented.  The ufs filesystem will compact
 * a fragmented directory block to make space for a new entry. When this
 * occurs, the offsets of previously added entries change. Any "diradd"
 * dependency structures corresponding to these entries must be updated with
 * the new offsets.
 */

/*
 * This routine is called after the in-memory inode's link
 * count has been incremented, but before the directory entry's
 * pointer to the inode has been set.
 */
int
softdep_setup_directory_add(bp, dp, diroffset, newinum, newdirbp, isnewblk)
      struct buf *bp;         /* buffer containing directory block */
      struct inode *dp; /* inode for directory */
      off_t diroffset;  /* offset of new entry in directory */
      ino_t newinum;          /* inode referenced by new directory entry */
      struct buf *newdirbp;   /* non-NULL => contents of new mkdir */
      int isnewblk;           /* entry is in a newly allocated block */
{
      int offset;       /* offset of new entry within directory block */
      ufs_lbn_t lbn;          /* block in directory containing new entry */
      struct fs *fs;
      struct diradd *dap;
      struct allocdirect *adp;
      struct pagedep *pagedep;
      struct inodedep *inodedep;
      struct newdirblk *newdirblk = 0;
      struct mkdir *mkdir1, *mkdir2;
      struct mount *mp;

      /*
       * Whiteouts have no dependencies.
       */
      if (newinum == WINO) {
            if (newdirbp != NULL)
                  bdwrite(newdirbp);
            return (0);
      }
      mp = UFSTOVFS(dp->i_ump);
      fs = dp->i_fs;
      lbn = lblkno(fs, diroffset);
      offset = blkoff(fs, diroffset);
      MALLOC(dap, struct diradd *, sizeof(struct diradd), M_DIRADD,
            M_SOFTDEP_FLAGS|M_ZERO);
      workitem_alloc(&dap->da_list, D_DIRADD, mp);
      dap->da_offset = offset;
      dap->da_newinum = newinum;
      dap->da_state = ATTACHED;
      if (isnewblk && lbn < NDADDR && fragoff(fs, diroffset) == 0) {
            MALLOC(newdirblk, struct newdirblk *, sizeof(struct newdirblk),
                M_NEWDIRBLK, M_SOFTDEP_FLAGS);
            workitem_alloc(&newdirblk->db_list, D_NEWDIRBLK, mp);
      }
      if (newdirbp == NULL) {
            dap->da_state |= DEPCOMPLETE;
            ACQUIRE_LOCK(&lk);
      } else {
            dap->da_state |= MKDIR_BODY | MKDIR_PARENT;
            MALLOC(mkdir1, struct mkdir *, sizeof(struct mkdir), M_MKDIR,
                M_SOFTDEP_FLAGS);
            workitem_alloc(&mkdir1->md_list, D_MKDIR, mp);
            mkdir1->md_state = MKDIR_BODY;
            mkdir1->md_diradd = dap;
            MALLOC(mkdir2, struct mkdir *, sizeof(struct mkdir), M_MKDIR,
                M_SOFTDEP_FLAGS);
            workitem_alloc(&mkdir2->md_list, D_MKDIR, mp);
            mkdir2->md_state = MKDIR_PARENT;
            mkdir2->md_diradd = dap;
            /*
             * Dependency on "." and ".." being written to disk.
             */
            mkdir1->md_buf = newdirbp;
            ACQUIRE_LOCK(&lk);
            LIST_INSERT_HEAD(&mkdirlisthd, mkdir1, md_mkdirs);
            WORKLIST_INSERT(&newdirbp->b_dep, &mkdir1->md_list);
            FREE_LOCK(&lk);
            bdwrite(newdirbp);
            /*
             * Dependency on link count increase for parent directory
             */
            ACQUIRE_LOCK(&lk);
            if (inodedep_lookup(mp, dp->i_number, 0, &inodedep) == 0
                || (inodedep->id_state & ALLCOMPLETE) == ALLCOMPLETE) {
                  dap->da_state &= ~MKDIR_PARENT;
                  WORKITEM_FREE(mkdir2, D_MKDIR);
            } else {
                  LIST_INSERT_HEAD(&mkdirlisthd, mkdir2, md_mkdirs);
                  WORKLIST_INSERT(&inodedep->id_bufwait,&mkdir2->md_list);
            }
      }
      /*
       * Link into parent directory pagedep to await its being written.
       */
      if (pagedep_lookup(dp, lbn, DEPALLOC, &pagedep) == 0)
            WORKLIST_INSERT(&bp->b_dep, &pagedep->pd_list);
      dap->da_pagedep = pagedep;
      LIST_INSERT_HEAD(&pagedep->pd_diraddhd[DIRADDHASH(offset)], dap,
          da_pdlist);
      /*
       * Link into its inodedep. Put it on the id_bufwait list if the inode
       * is not yet written. If it is written, do the post-inode write
       * processing to put it on the id_pendinghd list.
       */
      (void) inodedep_lookup(mp, newinum, DEPALLOC, &inodedep);
      if ((inodedep->id_state & ALLCOMPLETE) == ALLCOMPLETE)
            diradd_inode_written(dap, inodedep);
      else
            WORKLIST_INSERT(&inodedep->id_bufwait, &dap->da_list);
      if (isnewblk) {
            /*
             * Directories growing into indirect blocks are rare
             * enough and the frequency of new block allocation
             * in those cases even more rare, that we choose not
             * to bother tracking them. Rather we simply force the
             * new directory entry to disk.
             */
            if (lbn >= NDADDR) {
                  FREE_LOCK(&lk);
                  /*
                   * We only have a new allocation when at the
                   * beginning of a new block, not when we are
                   * expanding into an existing block.
                   */
                  if (blkoff(fs, diroffset) == 0)
                        return (1);
                  return (0);
            }
            /*
             * We only have a new allocation when at the beginning
             * of a new fragment, not when we are expanding into an
             * existing fragment. Also, there is nothing to do if we
             * are already tracking this block.
             */
            if (fragoff(fs, diroffset) != 0) {
                  FREE_LOCK(&lk);
                  return (0);
            }
            if ((pagedep->pd_state & NEWBLOCK) != 0) {
                  WORKITEM_FREE(newdirblk, D_NEWDIRBLK);
                  FREE_LOCK(&lk);
                  return (0);
            }
            /*
             * Find our associated allocdirect and have it track us.
             */
            if (inodedep_lookup(mp, dp->i_number, 0, &inodedep) == 0)
                  panic("softdep_setup_directory_add: lost inodedep");
            adp = TAILQ_LAST(&inodedep->id_newinoupdt, allocdirectlst);
            if (adp == NULL || adp->ad_lbn != lbn)
                  panic("softdep_setup_directory_add: lost entry");
            pagedep->pd_state |= NEWBLOCK;
            newdirblk->db_pagedep = pagedep;
            WORKLIST_INSERT(&adp->ad_newdirblk, &newdirblk->db_list);
      }
      FREE_LOCK(&lk);
      return (0);
}

/*
 * This procedure is called to change the offset of a directory
 * entry when compacting a directory block which must be owned
 * exclusively by the caller. Note that the actual entry movement
 * must be done in this procedure to ensure that no I/O completions
 * occur while the move is in progress.
 */
void 
softdep_change_directoryentry_offset(dp, base, oldloc, newloc, entrysize)
      struct inode *dp; /* inode for directory */
      caddr_t base;           /* address of dp->i_offset */
      caddr_t oldloc;         /* address of old directory location */
      caddr_t newloc;         /* address of new directory location */
      int entrysize;          /* size of directory entry */
{
      int offset, oldoffset, newoffset;
      struct pagedep *pagedep;
      struct diradd *dap;
      ufs_lbn_t lbn;

      ACQUIRE_LOCK(&lk);
      lbn = lblkno(dp->i_fs, dp->i_offset);
      offset = blkoff(dp->i_fs, dp->i_offset);
      if (pagedep_lookup(dp, lbn, 0, &pagedep) == 0)
            goto done;
      oldoffset = offset + (oldloc - base);
      newoffset = offset + (newloc - base);

      LIST_FOREACH(dap, &pagedep->pd_diraddhd[DIRADDHASH(oldoffset)], da_pdlist) {
            if (dap->da_offset != oldoffset)
                  continue;
            dap->da_offset = newoffset;
            if (DIRADDHASH(newoffset) == DIRADDHASH(oldoffset))
                  break;
            LIST_REMOVE(dap, da_pdlist);
            LIST_INSERT_HEAD(&pagedep->pd_diraddhd[DIRADDHASH(newoffset)],
                dap, da_pdlist);
            break;
      }
      if (dap == NULL) {

            LIST_FOREACH(dap, &pagedep->pd_pendinghd, da_pdlist) {
                  if (dap->da_offset == oldoffset) {
                        dap->da_offset = newoffset;
                        break;
                  }
            }
      }
done:
      bcopy(oldloc, newloc, entrysize);
      FREE_LOCK(&lk);
}

/*
 * Free a diradd dependency structure. This routine must be called
 * with splbio interrupts blocked.
 */
static void
free_diradd(dap)
      struct diradd *dap;
{
      struct dirrem *dirrem;
      struct pagedep *pagedep;
      struct inodedep *inodedep;
      struct mkdir *mkdir, *nextmd;

      mtx_assert(&lk, MA_OWNED);
      WORKLIST_REMOVE(&dap->da_list);
      LIST_REMOVE(dap, da_pdlist);
      if ((dap->da_state & DIRCHG) == 0) {
            pagedep = dap->da_pagedep;
      } else {
            dirrem = dap->da_previous;
            pagedep = dirrem->dm_pagedep;
            dirrem->dm_dirinum = pagedep->pd_ino;
            add_to_worklist(&dirrem->dm_list);
      }
      if (inodedep_lookup(pagedep->pd_list.wk_mp, dap->da_newinum,
          0, &inodedep) != 0)
            (void) free_inodedep(inodedep);
      if ((dap->da_state & (MKDIR_PARENT | MKDIR_BODY)) != 0) {
            for (mkdir = LIST_FIRST(&mkdirlisthd); mkdir; mkdir = nextmd) {
                  nextmd = LIST_NEXT(mkdir, md_mkdirs);
                  if (mkdir->md_diradd != dap)
                        continue;
                  dap->da_state &= ~mkdir->md_state;
                  WORKLIST_REMOVE(&mkdir->md_list);
                  LIST_REMOVE(mkdir, md_mkdirs);
                  WORKITEM_FREE(mkdir, D_MKDIR);
            }
            if ((dap->da_state & (MKDIR_PARENT | MKDIR_BODY)) != 0)
                  panic("free_diradd: unfound ref");
      }
      WORKITEM_FREE(dap, D_DIRADD);
}

/*
 * Directory entry removal dependencies.
 * 
 * When removing a directory entry, the entry's inode pointer must be
 * zero'ed on disk before the corresponding inode's link count is decremented
 * (possibly freeing the inode for re-use). This dependency is handled by
 * updating the directory entry but delaying the inode count reduction until
 * after the directory block has been written to disk. After this point, the
 * inode count can be decremented whenever it is convenient.
 */

/*
 * This routine should be called immediately after removing
 * a directory entry.  The inode's link count should not be
 * decremented by the calling procedure -- the soft updates
 * code will do this task when it is safe.
 */
void 
softdep_setup_remove(bp, dp, ip, isrmdir)
      struct buf *bp;         /* buffer containing directory block */
      struct inode *dp; /* inode for the directory being modified */
      struct inode *ip; /* inode for directory entry being removed */
      int isrmdir;            /* indicates if doing RMDIR */
{
      struct dirrem *dirrem, *prevdirrem;

      /*
       * Allocate a new dirrem if appropriate and ACQUIRE_LOCK.
       */
      dirrem = newdirrem(bp, dp, ip, isrmdir, &prevdirrem);

      /*
       * If the COMPLETE flag is clear, then there were no active
       * entries and we want to roll back to a zeroed entry until
       * the new inode is committed to disk. If the COMPLETE flag is
       * set then we have deleted an entry that never made it to
       * disk. If the entry we deleted resulted from a name change,
       * then the old name still resides on disk. We cannot delete
       * its inode (returned to us in prevdirrem) until the zeroed
       * directory entry gets to disk. The new inode has never been
       * referenced on the disk, so can be deleted immediately.
       */
      if ((dirrem->dm_state & COMPLETE) == 0) {
            LIST_INSERT_HEAD(&dirrem->dm_pagedep->pd_dirremhd, dirrem,
                dm_next);
            FREE_LOCK(&lk);
      } else {
            if (prevdirrem != NULL)
                  LIST_INSERT_HEAD(&dirrem->dm_pagedep->pd_dirremhd,
                      prevdirrem, dm_next);
            dirrem->dm_dirinum = dirrem->dm_pagedep->pd_ino;
            FREE_LOCK(&lk);
            handle_workitem_remove(dirrem, NULL);
      }
}

/*
 * Allocate a new dirrem if appropriate and return it along with
 * its associated pagedep. Called without a lock, returns with lock.
 */
static long num_dirrem;       /* number of dirrem allocated */
static struct dirrem *
newdirrem(bp, dp, ip, isrmdir, prevdirremp)
      struct buf *bp;         /* buffer containing directory block */
      struct inode *dp; /* inode for the directory being modified */
      struct inode *ip; /* inode for directory entry being removed */
      int isrmdir;            /* indicates if doing RMDIR */
      struct dirrem **prevdirremp; /* previously referenced inode, if any */
{
      int offset;
      ufs_lbn_t lbn;
      struct diradd *dap;
      struct dirrem *dirrem;
      struct pagedep *pagedep;

      /*
       * Whiteouts have no deletion dependencies.
       */
      if (ip == NULL)
            panic("newdirrem: whiteout");
      /*
       * If we are over our limit, try to improve the situation.
       * Limiting the number of dirrem structures will also limit
       * the number of freefile and freeblks structures.
       */
      ACQUIRE_LOCK(&lk);
      if (num_dirrem > max_softdeps / 2)
            (void) request_cleanup(ITOV(dp)->v_mount, FLUSH_REMOVE);
      num_dirrem += 1;
      FREE_LOCK(&lk);
      MALLOC(dirrem, struct dirrem *, sizeof(struct dirrem),
            M_DIRREM, M_SOFTDEP_FLAGS|M_ZERO);
      workitem_alloc(&dirrem->dm_list, D_DIRREM, ITOV(dp)->v_mount);
      dirrem->dm_state = isrmdir ? RMDIR : 0;
      dirrem->dm_oldinum = ip->i_number;
      *prevdirremp = NULL;

      ACQUIRE_LOCK(&lk);
      lbn = lblkno(dp->i_fs, dp->i_offset);
      offset = blkoff(dp->i_fs, dp->i_offset);
      if (pagedep_lookup(dp, lbn, DEPALLOC, &pagedep) == 0)
            WORKLIST_INSERT(&bp->b_dep, &pagedep->pd_list);
      dirrem->dm_pagedep = pagedep;
      /*
       * Check for a diradd dependency for the same directory entry.
       * If present, then both dependencies become obsolete and can
       * be de-allocated. Check for an entry on both the pd_dirraddhd
       * list and the pd_pendinghd list.
       */

      LIST_FOREACH(dap, &pagedep->pd_diraddhd[DIRADDHASH(offset)], da_pdlist)
            if (dap->da_offset == offset)
                  break;
      if (dap == NULL) {

            LIST_FOREACH(dap, &pagedep->pd_pendinghd, da_pdlist)
                  if (dap->da_offset == offset)
                        break;
            if (dap == NULL)
                  return (dirrem);
      }
      /*
       * Must be ATTACHED at this point.
       */
      if ((dap->da_state & ATTACHED) == 0)
            panic("newdirrem: not ATTACHED");
      if (dap->da_newinum != ip->i_number)
            panic("newdirrem: inum %d should be %d",
                ip->i_number, dap->da_newinum);
      /*
       * If we are deleting a changed name that never made it to disk,
       * then return the dirrem describing the previous inode (which
       * represents the inode currently referenced from this entry on disk).
       */
      if ((dap->da_state & DIRCHG) != 0) {
            *prevdirremp = dap->da_previous;
            dap->da_state &= ~DIRCHG;
            dap->da_pagedep = pagedep;
      }
      /*
       * We are deleting an entry that never made it to disk.
       * Mark it COMPLETE so we can delete its inode immediately.
       */
      dirrem->dm_state |= COMPLETE;
      free_diradd(dap);
      return (dirrem);
}

/*
 * Directory entry change dependencies.
 * 
 * Changing an existing directory entry requires that an add operation
 * be completed first followed by a deletion. The semantics for the addition
 * are identical to the description of adding a new entry above except
 * that the rollback is to the old inode number rather than zero. Once
 * the addition dependency is completed, the removal is done as described
 * in the removal routine above.
 */

/*
 * This routine should be called immediately after changing
 * a directory entry.  The inode's link count should not be
 * decremented by the calling procedure -- the soft updates
 * code will perform this task when it is safe.
 */
void 
softdep_setup_directory_change(bp, dp, ip, newinum, isrmdir)
      struct buf *bp;         /* buffer containing directory block */
      struct inode *dp; /* inode for the directory being modified */
      struct inode *ip; /* inode for directory entry being removed */
      ino_t newinum;          /* new inode number for changed entry */
      int isrmdir;            /* indicates if doing RMDIR */
{
      int offset;
      struct diradd *dap = NULL;
      struct dirrem *dirrem, *prevdirrem;
      struct pagedep *pagedep;
      struct inodedep *inodedep;
      struct mount *mp;

      offset = blkoff(dp->i_fs, dp->i_offset);
      mp = UFSTOVFS(dp->i_ump);

      /*
       * Whiteouts do not need diradd dependencies.
       */
      if (newinum != WINO) {
            MALLOC(dap, struct diradd *, sizeof(struct diradd),
                M_DIRADD, M_SOFTDEP_FLAGS|M_ZERO);
            workitem_alloc(&dap->da_list, D_DIRADD, mp);
            dap->da_state = DIRCHG | ATTACHED | DEPCOMPLETE;
            dap->da_offset = offset;
            dap->da_newinum = newinum;
      }

      /*
       * Allocate a new dirrem and ACQUIRE_LOCK.
       */
      dirrem = newdirrem(bp, dp, ip, isrmdir, &prevdirrem);
      pagedep = dirrem->dm_pagedep;
      /*
       * The possible values for isrmdir:
       *    0 - non-directory file rename
       *    1 - directory rename within same directory
       *   inum - directory rename to new directory of given inode number
       * When renaming to a new directory, we are both deleting and
       * creating a new directory entry, so the link count on the new
       * directory should not change. Thus we do not need the followup
       * dirrem which is usually done in handle_workitem_remove. We set
       * the DIRCHG flag to tell handle_workitem_remove to skip the 
       * followup dirrem.
       */
      if (isrmdir > 1)
            dirrem->dm_state |= DIRCHG;

      /*
       * Whiteouts have no additional dependencies,
       * so just put the dirrem on the correct list.
       */
      if (newinum == WINO) {
            if ((dirrem->dm_state & COMPLETE) == 0) {
                  LIST_INSERT_HEAD(&pagedep->pd_dirremhd, dirrem,
                      dm_next);
            } else {
                  dirrem->dm_dirinum = pagedep->pd_ino;
                  add_to_worklist(&dirrem->dm_list);
            }
            FREE_LOCK(&lk);
            return;
      }

      /*
       * If the COMPLETE flag is clear, then there were no active
       * entries and we want to roll back to the previous inode until
       * the new inode is committed to disk. If the COMPLETE flag is
       * set, then we have deleted an entry that never made it to disk.
       * If the entry we deleted resulted from a name change, then the old
       * inode reference still resides on disk. Any rollback that we do
       * needs to be to that old inode (returned to us in prevdirrem). If
       * the entry we deleted resulted from a create, then there is
       * no entry on the disk, so we want to roll back to zero rather
       * than the uncommitted inode. In either of the COMPLETE cases we
       * want to immediately free the unwritten and unreferenced inode.
       */
      if ((dirrem->dm_state & COMPLETE) == 0) {
            dap->da_previous = dirrem;
      } else {
            if (prevdirrem != NULL) {
                  dap->da_previous = prevdirrem;
            } else {
                  dap->da_state &= ~DIRCHG;
                  dap->da_pagedep = pagedep;
            }
            dirrem->dm_dirinum = pagedep->pd_ino;
            add_to_worklist(&dirrem->dm_list);
      }
      /*
       * Link into its inodedep. Put it on the id_bufwait list if the inode
       * is not yet written. If it is written, do the post-inode write
       * processing to put it on the id_pendinghd list.
       */
      if (inodedep_lookup(mp, newinum, DEPALLOC, &inodedep) == 0 ||
          (inodedep->id_state & ALLCOMPLETE) == ALLCOMPLETE) {
            dap->da_state |= COMPLETE;
            LIST_INSERT_HEAD(&pagedep->pd_pendinghd, dap, da_pdlist);
            WORKLIST_INSERT(&inodedep->id_pendinghd, &dap->da_list);
      } else {
            LIST_INSERT_HEAD(&pagedep->pd_diraddhd[DIRADDHASH(offset)],
                dap, da_pdlist);
            WORKLIST_INSERT(&inodedep->id_bufwait, &dap->da_list);
      }
      FREE_LOCK(&lk);
}

/*
 * Called whenever the link count on an inode is changed.
 * It creates an inode dependency so that the new reference(s)
 * to the inode cannot be committed to disk until the updated
 * inode has been written.
 */
void
softdep_change_linkcnt(ip)
      struct inode *ip; /* the inode with the increased link count */
{
      struct inodedep *inodedep;

      ACQUIRE_LOCK(&lk);
      (void) inodedep_lookup(UFSTOVFS(ip->i_ump), ip->i_number,
          DEPALLOC, &inodedep);
      if (ip->i_nlink < ip->i_effnlink)
            panic("softdep_change_linkcnt: bad delta");
      inodedep->id_nlinkdelta = ip->i_nlink - ip->i_effnlink;
      FREE_LOCK(&lk);
}

/*
 * Called when the effective link count and the reference count
 * on an inode drops to zero. At this point there are no names
 * referencing the file in the filesystem and no active file
 * references. The space associated with the file will be freed
 * as soon as the necessary soft dependencies are cleared.
 */
void
softdep_releasefile(ip)
      struct inode *ip; /* inode with the zero effective link count */
{
      struct inodedep *inodedep;
      struct fs *fs;
      int extblocks;

      if (ip->i_effnlink > 0)
            panic("softdep_releasefile: file still referenced");
      /*
       * We may be called several times as the on-disk link count
       * drops to zero. We only want to account for the space once.
       */
      if (ip->i_flag & IN_SPACECOUNTED)
            return;
      /*
       * We have to deactivate a snapshot otherwise copyonwrites may
       * add blocks and the cleanup may remove blocks after we have
       * tried to account for them.
       */
      if ((ip->i_flags & SF_SNAPSHOT) != 0)
            ffs_snapremove(ITOV(ip));
      /*
       * If we are tracking an nlinkdelta, we have to also remember
       * whether we accounted for the freed space yet.
       */
      ACQUIRE_LOCK(&lk);
      if ((inodedep_lookup(UFSTOVFS(ip->i_ump), ip->i_number, 0, &inodedep)))
            inodedep->id_state |= SPACECOUNTED;
      FREE_LOCK(&lk);
      fs = ip->i_fs;
      extblocks = 0;
      if (fs->fs_magic == FS_UFS2_MAGIC)
            extblocks = btodb(fragroundup(fs, ip->i_din2->di_extsize));
      UFS_LOCK(ip->i_ump);
      ip->i_fs->fs_pendingblocks += DIP(ip, i_blocks) - extblocks;
      ip->i_fs->fs_pendinginodes += 1;
      UFS_UNLOCK(ip->i_ump);
      ip->i_flag |= IN_SPACECOUNTED;
}

/*
 * This workitem decrements the inode's link count.
 * If the link count reaches zero, the file is removed.
 */
static void 
handle_workitem_remove(dirrem, xp)
      struct dirrem *dirrem;
      struct vnode *xp;
{
      struct thread *td = curthread;
      struct inodedep *inodedep;
      struct vnode *vp;
      struct inode *ip;
      ino_t oldinum;
      int error;

      if ((vp = xp) == NULL &&
          (error = ffs_vget(dirrem->dm_list.wk_mp,
          dirrem->dm_oldinum, LK_EXCLUSIVE, &vp)) != 0) {
            softdep_error("handle_workitem_remove: vget", error);
            return;
      }
      ip = VTOI(vp);
      ACQUIRE_LOCK(&lk);
      if ((inodedep_lookup(dirrem->dm_list.wk_mp,
          dirrem->dm_oldinum, 0, &inodedep)) == 0)
            panic("handle_workitem_remove: lost inodedep");
      /*
       * Normal file deletion.
       */
      if ((dirrem->dm_state & RMDIR) == 0) {
            ip->i_nlink--;
            DIP_SET(ip, i_nlink, ip->i_nlink);
            ip->i_flag |= IN_CHANGE;
            if (ip->i_nlink < ip->i_effnlink)
                  panic("handle_workitem_remove: bad file delta");
            inodedep->id_nlinkdelta = ip->i_nlink - ip->i_effnlink;
            num_dirrem -= 1;
            WORKITEM_FREE(dirrem, D_DIRREM);
            FREE_LOCK(&lk);
            vput(vp);
            return;
      }
      /*
       * Directory deletion. Decrement reference count for both the
       * just deleted parent directory entry and the reference for ".".
       * Next truncate the directory to length zero. When the
       * truncation completes, arrange to have the reference count on
       * the parent decremented to account for the loss of "..".
       */
      ip->i_nlink -= 2;
      DIP_SET(ip, i_nlink, ip->i_nlink);
      ip->i_flag |= IN_CHANGE;
      if (ip->i_nlink < ip->i_effnlink)
            panic("handle_workitem_remove: bad dir delta");
      inodedep->id_nlinkdelta = ip->i_nlink - ip->i_effnlink;
      FREE_LOCK(&lk);
      if ((error = ffs_truncate(vp, (off_t)0, 0, td->td_ucred, td)) != 0)
            softdep_error("handle_workitem_remove: truncate", error);
      ACQUIRE_LOCK(&lk);
      /*
       * Rename a directory to a new parent. Since, we are both deleting
       * and creating a new directory entry, the link count on the new
       * directory should not change. Thus we skip the followup dirrem.
       */
      if (dirrem->dm_state & DIRCHG) {
            num_dirrem -= 1;
            WORKITEM_FREE(dirrem, D_DIRREM);
            FREE_LOCK(&lk);
            vput(vp);
            return;
      }
      /*
       * If the inodedep does not exist, then the zero'ed inode has
       * been written to disk. If the allocated inode has never been
       * written to disk, then the on-disk inode is zero'ed. In either
       * case we can remove the file immediately.
       */
      dirrem->dm_state = 0;
      oldinum = dirrem->dm_oldinum;
      dirrem->dm_oldinum = dirrem->dm_dirinum;
      if (inodedep_lookup(dirrem->dm_list.wk_mp, oldinum,
          0, &inodedep) == 0 || check_inode_unwritten(inodedep)) {
            if (xp != NULL)
                  add_to_worklist(&dirrem->dm_list);
            FREE_LOCK(&lk);
            vput(vp);
            if (xp == NULL)
                  handle_workitem_remove(dirrem, NULL);
            return;
      }
      WORKLIST_INSERT(&inodedep->id_inowait, &dirrem->dm_list);
      FREE_LOCK(&lk);
      ip->i_flag |= IN_CHANGE;
      ffs_update(vp, 0);
      vput(vp);
}

/*
 * Inode de-allocation dependencies.
 * 
 * When an inode's link count is reduced to zero, it can be de-allocated. We
 * found it convenient to postpone de-allocation until after the inode is
 * written to disk with its new link count (zero).  At this point, all of the
 * on-disk inode's block pointers are nullified and, with careful dependency
 * list ordering, all dependencies related to the inode will be satisfied and
 * the corresponding dependency structures de-allocated.  So, if/when the
 * inode is reused, there will be no mixing of old dependencies with new
 * ones.  This artificial dependency is set up by the block de-allocation
 * procedure above (softdep_setup_freeblocks) and completed by the
 * following procedure.
 */
static void 
handle_workitem_freefile(freefile)
      struct freefile *freefile;
{
      struct fs *fs;
      struct inodedep *idp;
      struct ufsmount *ump;
      int error;

      ump = VFSTOUFS(freefile->fx_list.wk_mp);
      fs = ump->um_fs;
#ifdef DEBUG
      ACQUIRE_LOCK(&lk);
      error = inodedep_lookup(UFSTOVFS(ump), freefile->fx_oldinum, 0, &idp);
      FREE_LOCK(&lk);
      if (error)
            panic("handle_workitem_freefile: inodedep survived");
#endif
      UFS_LOCK(ump);
      fs->fs_pendinginodes -= 1;
      UFS_UNLOCK(ump);
      if ((error = ffs_freefile(ump, fs, freefile->fx_devvp,
          freefile->fx_oldinum, freefile->fx_mode)) != 0)
            softdep_error("handle_workitem_freefile", error);
      ACQUIRE_LOCK(&lk);
      WORKITEM_FREE(freefile, D_FREEFILE);
      FREE_LOCK(&lk);
}


/*
 * Helper function which unlinks marker element from work list and returns
 * the next element on the list.
 */
static __inline struct worklist *
markernext(struct worklist *marker)
{
      struct worklist *next;
      
      next = LIST_NEXT(marker, wk_list);
      LIST_REMOVE(marker, wk_list);
      return next;
}

/*
 * Disk writes.
 * 
 * The dependency structures constructed above are most actively used when file
 * system blocks are written to disk.  No constraints are placed on when a
 * block can be written, but unsatisfied update dependencies are made safe by
 * modifying (or replacing) the source memory for the duration of the disk
 * write.  When the disk write completes, the memory block is again brought
 * up-to-date.
 *
 * In-core inode structure reclamation.
 * 
 * Because there are a finite number of "in-core" inode structures, they are
 * reused regularly.  By transferring all inode-related dependencies to the
 * in-memory inode block and indexing them separately (via "inodedep"s), we
 * can allow "in-core" inode structures to be reused at any time and avoid
 * any increase in contention.
 *
 * Called just before entering the device driver to initiate a new disk I/O.
 * The buffer must be locked, thus, no I/O completion operations can occur
 * while we are manipulating its associated dependencies.
 */
static void 
softdep_disk_io_initiation(bp)
      struct buf *bp;         /* structure describing disk write to occur */
{
      struct worklist *wk;
      struct worklist marker;
      struct indirdep *indirdep;
      struct inodedep *inodedep;

      /*
       * We only care about write operations. There should never
       * be dependencies for reads.
       */
      if (bp->b_iocmd != BIO_WRITE)
            panic("softdep_disk_io_initiation: not write");

      marker.wk_type = D_LAST + 1;  /* Not a normal workitem */
      PHOLD(curproc);               /* Don't swap out kernel stack */

      ACQUIRE_LOCK(&lk);
      /*
       * Do any necessary pre-I/O processing.
       */
      for (wk = LIST_FIRST(&bp->b_dep); wk != NULL;
           wk = markernext(&marker)) {
            LIST_INSERT_AFTER(wk, &marker, wk_list);
            switch (wk->wk_type) {

            case D_PAGEDEP:
                  initiate_write_filepage(WK_PAGEDEP(wk), bp);
                  continue;

            case D_INODEDEP:
                  inodedep = WK_INODEDEP(wk);
                  if (inodedep->id_fs->fs_magic == FS_UFS1_MAGIC)
                        initiate_write_inodeblock_ufs1(inodedep, bp);
                  else
                        initiate_write_inodeblock_ufs2(inodedep, bp);
                  continue;

            case D_INDIRDEP:
                  indirdep = WK_INDIRDEP(wk);
                  if (indirdep->ir_state & GOINGAWAY)
                        panic("disk_io_initiation: indirdep gone");
                  /*
                   * If there are no remaining dependencies, this
                   * will be writing the real pointers, so the
                   * dependency can be freed.
                   */
                  if (LIST_EMPTY(&indirdep->ir_deplisthd)) {
                        struct buf *bp;

                        bp = indirdep->ir_savebp;
                        bp->b_flags |= B_INVAL | B_NOCACHE;
                        /* inline expand WORKLIST_REMOVE(wk); */
                        wk->wk_state &= ~ONWORKLIST;
                        LIST_REMOVE(wk, wk_list);
                        WORKITEM_FREE(indirdep, D_INDIRDEP);
                        FREE_LOCK(&lk);
                        brelse(bp);
                        ACQUIRE_LOCK(&lk);
                        continue;
                  }
                  /*
                   * Replace up-to-date version with safe version.
                   */
                  FREE_LOCK(&lk);
                  MALLOC(indirdep->ir_saveddata, caddr_t, bp->b_bcount,
                      M_INDIRDEP, M_SOFTDEP_FLAGS);
                  ACQUIRE_LOCK(&lk);
                  indirdep->ir_state &= ~ATTACHED;
                  indirdep->ir_state |= UNDONE;
                  bcopy(bp->b_data, indirdep->ir_saveddata, bp->b_bcount);
                  bcopy(indirdep->ir_savebp->b_data, bp->b_data,
                      bp->b_bcount);
                  continue;

            case D_MKDIR:
            case D_BMSAFEMAP:
            case D_ALLOCDIRECT:
            case D_ALLOCINDIR:
                  continue;

            default:
                  panic("handle_disk_io_initiation: Unexpected type %s",
                      TYPENAME(wk->wk_type));
                  /* NOTREACHED */
            }
      }
      FREE_LOCK(&lk);
      PRELE(curproc);               /* Allow swapout of kernel stack */
}

/*
 * Called from within the procedure above to deal with unsatisfied
 * allocation dependencies in a directory. The buffer must be locked,
 * thus, no I/O completion operations can occur while we are
 * manipulating its associated dependencies.
 */
static void
initiate_write_filepage(pagedep, bp)
      struct pagedep *pagedep;
      struct buf *bp;
{
      struct diradd *dap;
      struct direct *ep;
      int i;

      if (pagedep->pd_state & IOSTARTED) {
            /*
             * This can only happen if there is a driver that does not
             * understand chaining. Here biodone will reissue the call
             * to strategy for the incomplete buffers.
             */
            printf("initiate_write_filepage: already started\n");
            return;
      }
      pagedep->pd_state |= IOSTARTED;
      for (i = 0; i < DAHASHSZ; i++) {
            LIST_FOREACH(dap, &pagedep->pd_diraddhd[i], da_pdlist) {
                  ep = (struct direct *)
                      ((char *)bp->b_data + dap->da_offset);
                  if (ep->d_ino != dap->da_newinum)
                        panic("%s: dir inum %d != new %d",
                            "initiate_write_filepage",
                            ep->d_ino, dap->da_newinum);
                  if (dap->da_state & DIRCHG)
                        ep->d_ino = dap->da_previous->dm_oldinum;
                  else
                        ep->d_ino = 0;
                  dap->da_state &= ~ATTACHED;
                  dap->da_state |= UNDONE;
            }
      }
}

/*
 * Version of initiate_write_inodeblock that handles UFS1 dinodes.
 * Note that any bug fixes made to this routine must be done in the
 * version found below.
 *
 * Called from within the procedure above to deal with unsatisfied
 * allocation dependencies in an inodeblock. The buffer must be
 * locked, thus, no I/O completion operations can occur while we
 * are manipulating its associated dependencies.
 */
static void 
initiate_write_inodeblock_ufs1(inodedep, bp)
      struct inodedep *inodedep;
      struct buf *bp;               /* The inode block */
{
      struct allocdirect *adp, *lastadp;
      struct ufs1_dinode *dp;
      struct ufs1_dinode *sip;
      struct fs *fs;
      ufs_lbn_t i, prevlbn = 0;
      int deplist;

      if (inodedep->id_state & IOSTARTED)
            panic("initiate_write_inodeblock_ufs1: already started");
      inodedep->id_state |= IOSTARTED;
      fs = inodedep->id_fs;
      dp = (struct ufs1_dinode *)bp->b_data +
          ino_to_fsbo(fs, inodedep->id_ino);
      /*
       * If the bitmap is not yet written, then the allocated
       * inode cannot be written to disk.
       */
      if ((inodedep->id_state & DEPCOMPLETE) == 0) {
            if (inodedep->id_savedino1 != NULL)
                  panic("initiate_write_inodeblock_ufs1: I/O underway");
            FREE_LOCK(&lk);
            MALLOC(sip, struct ufs1_dinode *,
                sizeof(struct ufs1_dinode), M_SAVEDINO, M_SOFTDEP_FLAGS);
            ACQUIRE_LOCK(&lk);
            inodedep->id_savedino1 = sip;
            *inodedep->id_savedino1 = *dp;
            bzero((caddr_t)dp, sizeof(struct ufs1_dinode));
            dp->di_gen = inodedep->id_savedino1->di_gen;
            return;
      }
      /*
       * If no dependencies, then there is nothing to roll back.
       */
      inodedep->id_savedsize = dp->di_size;
      inodedep->id_savedextsize = 0;
      if (TAILQ_EMPTY(&inodedep->id_inoupdt))
            return;
      /*
       * Set the dependencies to busy.
       */
      for (deplist = 0, adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp;
           adp = TAILQ_NEXT(adp, ad_next)) {
#ifdef DIAGNOSTIC
            if (deplist != 0 && prevlbn >= adp->ad_lbn)
                  panic("softdep_write_inodeblock: lbn order");
            prevlbn = adp->ad_lbn;
            if (adp->ad_lbn < NDADDR &&
                dp->di_db[adp->ad_lbn] != adp->ad_newblkno)
                  panic("%s: direct pointer #%jd mismatch %d != %jd",
                      "softdep_write_inodeblock",
                      (intmax_t)adp->ad_lbn,
                      dp->di_db[adp->ad_lbn],
                      (intmax_t)adp->ad_newblkno);
            if (adp->ad_lbn >= NDADDR &&
                dp->di_ib[adp->ad_lbn - NDADDR] != adp->ad_newblkno)
                  panic("%s: indirect pointer #%jd mismatch %d != %jd",
                      "softdep_write_inodeblock",
                      (intmax_t)adp->ad_lbn - NDADDR,
                      dp->di_ib[adp->ad_lbn - NDADDR],
                      (intmax_t)adp->ad_newblkno);
            deplist |= 1 << adp->ad_lbn;
            if ((adp->ad_state & ATTACHED) == 0)
                  panic("softdep_write_inodeblock: Unknown state 0x%x",
                      adp->ad_state);
#endif /* DIAGNOSTIC */
            adp->ad_state &= ~ATTACHED;
            adp->ad_state |= UNDONE;
      }
      /*
       * The on-disk inode cannot claim to be any larger than the last
       * fragment that has been written. Otherwise, the on-disk inode
       * might have fragments that were not the last block in the file
       * which would corrupt the filesystem.
       */
      for (lastadp = NULL, adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp;
           lastadp = adp, adp = TAILQ_NEXT(adp, ad_next)) {
            if (adp->ad_lbn >= NDADDR)
                  break;
            dp->di_db[adp->ad_lbn] = adp->ad_oldblkno;
            /* keep going until hitting a rollback to a frag */
            if (adp->ad_oldsize == 0 || adp->ad_oldsize == fs->fs_bsize)
                  continue;
            dp->di_size = fs->fs_bsize * adp->ad_lbn + adp->ad_oldsize;
            for (i = adp->ad_lbn + 1; i < NDADDR; i++) {
#ifdef DIAGNOSTIC
                  if (dp->di_db[i] != 0 && (deplist & (1 << i)) == 0)
                        panic("softdep_write_inodeblock: lost dep1");
#endif /* DIAGNOSTIC */
                  dp->di_db[i] = 0;
            }
            for (i = 0; i < NIADDR; i++) {
#ifdef DIAGNOSTIC
                  if (dp->di_ib[i] != 0 &&
                      (deplist & ((1 << NDADDR) << i)) == 0)
                        panic("softdep_write_inodeblock: lost dep2");
#endif /* DIAGNOSTIC */
                  dp->di_ib[i] = 0;
            }
            return;
      }
      /*
       * If we have zero'ed out the last allocated block of the file,
       * roll back the size to the last currently allocated block.
       * We know that this last allocated block is a full-sized as
       * we already checked for fragments in the loop above.
       */
      if (lastadp != NULL &&
          dp->di_size <= (lastadp->ad_lbn + 1) * fs->fs_bsize) {
            for (i = lastadp->ad_lbn; i >= 0; i--)
                  if (dp->di_db[i] != 0)
                        break;
            dp->di_size = (i + 1) * fs->fs_bsize;
      }
      /*
       * The only dependencies are for indirect blocks.
       *
       * The file size for indirect block additions is not guaranteed.
       * Such a guarantee would be non-trivial to achieve. The conventional
       * synchronous write implementation also does not make this guarantee.
       * Fsck should catch and fix discrepancies. Arguably, the file size
       * can be over-estimated without destroying integrity when the file
       * moves into the indirect blocks (i.e., is large). If we want to
       * postpone fsck, we are stuck with this argument.
       */
      for (; adp; adp = TAILQ_NEXT(adp, ad_next))
            dp->di_ib[adp->ad_lbn - NDADDR] = 0;
}
            
/*
 * Version of initiate_write_inodeblock that handles UFS2 dinodes.
 * Note that any bug fixes made to this routine must be done in the
 * version found above.
 *
 * Called from within the procedure above to deal with unsatisfied
 * allocation dependencies in an inodeblock. The buffer must be
 * locked, thus, no I/O completion operations can occur while we
 * are manipulating its associated dependencies.
 */
static void 
initiate_write_inodeblock_ufs2(inodedep, bp)
      struct inodedep *inodedep;
      struct buf *bp;               /* The inode block */
{
      struct allocdirect *adp, *lastadp;
      struct ufs2_dinode *dp;
      struct ufs2_dinode *sip;
      struct fs *fs;
      ufs_lbn_t i, prevlbn = 0;
      int deplist;

      if (inodedep->id_state & IOSTARTED)
            panic("initiate_write_inodeblock_ufs2: already started");
      inodedep->id_state |= IOSTARTED;
      fs = inodedep->id_fs;
      dp = (struct ufs2_dinode *)bp->b_data +
          ino_to_fsbo(fs, inodedep->id_ino);
      /*
       * If the bitmap is not yet written, then the allocated
       * inode cannot be written to disk.
       */
      if ((inodedep->id_state & DEPCOMPLETE) == 0) {
            if (inodedep->id_savedino2 != NULL)
                  panic("initiate_write_inodeblock_ufs2: I/O underway");
            FREE_LOCK(&lk);
            MALLOC(sip, struct ufs2_dinode *,
                sizeof(struct ufs2_dinode), M_SAVEDINO, M_SOFTDEP_FLAGS);
            ACQUIRE_LOCK(&lk);
            inodedep->id_savedino2 = sip;
            *inodedep->id_savedino2 = *dp;
            bzero((caddr_t)dp, sizeof(struct ufs2_dinode));
            dp->di_gen = inodedep->id_savedino2->di_gen;
            return;
      }
      /*
       * If no dependencies, then there is nothing to roll back.
       */
      inodedep->id_savedsize = dp->di_size;
      inodedep->id_savedextsize = dp->di_extsize;
      if (TAILQ_EMPTY(&inodedep->id_inoupdt) &&
          TAILQ_EMPTY(&inodedep->id_extupdt))
            return;
      /*
       * Set the ext data dependencies to busy.
       */
      for (deplist = 0, adp = TAILQ_FIRST(&inodedep->id_extupdt); adp;
           adp = TAILQ_NEXT(adp, ad_next)) {
#ifdef DIAGNOSTIC
            if (deplist != 0 && prevlbn >= adp->ad_lbn)
                  panic("softdep_write_inodeblock: lbn order");
            prevlbn = adp->ad_lbn;
            if (dp->di_extb[adp->ad_lbn] != adp->ad_newblkno)
                  panic("%s: direct pointer #%jd mismatch %jd != %jd",
                      "softdep_write_inodeblock",
                      (intmax_t)adp->ad_lbn,
                      (intmax_t)dp->di_extb[adp->ad_lbn],
                      (intmax_t)adp->ad_newblkno);
            deplist |= 1 << adp->ad_lbn;
            if ((adp->ad_state & ATTACHED) == 0)
                  panic("softdep_write_inodeblock: Unknown state 0x%x",
                      adp->ad_state);
#endif /* DIAGNOSTIC */
            adp->ad_state &= ~ATTACHED;
            adp->ad_state |= UNDONE;
      }
      /*
       * The on-disk inode cannot claim to be any larger than the last
       * fragment that has been written. Otherwise, the on-disk inode
       * might have fragments that were not the last block in the ext
       * data which would corrupt the filesystem.
       */
      for (lastadp = NULL, adp = TAILQ_FIRST(&inodedep->id_extupdt); adp;
           lastadp = adp, adp = TAILQ_NEXT(adp, ad_next)) {
            dp->di_extb[adp->ad_lbn] = adp->ad_oldblkno;
            /* keep going until hitting a rollback to a frag */
            if (adp->ad_oldsize == 0 || adp->ad_oldsize == fs->fs_bsize)
                  continue;
            dp->di_extsize = fs->fs_bsize * adp->ad_lbn + adp->ad_oldsize;
            for (i = adp->ad_lbn + 1; i < NXADDR; i++) {
#ifdef DIAGNOSTIC
                  if (dp->di_extb[i] != 0 && (deplist & (1 << i)) == 0)
                        panic("softdep_write_inodeblock: lost dep1");
#endif /* DIAGNOSTIC */
                  dp->di_extb[i] = 0;
            }
            lastadp = NULL;
            break;
      }
      /*
       * If we have zero'ed out the last allocated block of the ext
       * data, roll back the size to the last currently allocated block.
       * We know that this last allocated block is a full-sized as
       * we already checked for fragments in the loop above.
       */
      if (lastadp != NULL &&
          dp->di_extsize <= (lastadp->ad_lbn + 1) * fs->fs_bsize) {
            for (i = lastadp->ad_lbn; i >= 0; i--)
                  if (dp->di_extb[i] != 0)
                        break;
            dp->di_extsize = (i + 1) * fs->fs_bsize;
      }
      /*
       * Set the file data dependencies to busy.
       */
      for (deplist = 0, adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp;
           adp = TAILQ_NEXT(adp, ad_next)) {
#ifdef DIAGNOSTIC
            if (deplist != 0 && prevlbn >= adp->ad_lbn)
                  panic("softdep_write_inodeblock: lbn order");
            prevlbn = adp->ad_lbn;
            if (adp->ad_lbn < NDADDR &&
                dp->di_db[adp->ad_lbn] != adp->ad_newblkno)
                  panic("%s: direct pointer #%jd mismatch %jd != %jd",
                      "softdep_write_inodeblock",
                      (intmax_t)adp->ad_lbn,
                      (intmax_t)dp->di_db[adp->ad_lbn],
                      (intmax_t)adp->ad_newblkno);
            if (adp->ad_lbn >= NDADDR &&
                dp->di_ib[adp->ad_lbn - NDADDR] != adp->ad_newblkno)
                  panic("%s indirect pointer #%jd mismatch %jd != %jd",
                      "softdep_write_inodeblock:",
                      (intmax_t)adp->ad_lbn - NDADDR,
                      (intmax_t)dp->di_ib[adp->ad_lbn - NDADDR],
                      (intmax_t)adp->ad_newblkno);
            deplist |= 1 << adp->ad_lbn;
            if ((adp->ad_state & ATTACHED) == 0)
                  panic("softdep_write_inodeblock: Unknown state 0x%x",
                      adp->ad_state);
#endif /* DIAGNOSTIC */
            adp->ad_state &= ~ATTACHED;
            adp->ad_state |= UNDONE;
      }
      /*
       * The on-disk inode cannot claim to be any larger than the last
       * fragment that has been written. Otherwise, the on-disk inode
       * might have fragments that were not the last block in the file
       * which would corrupt the filesystem.
       */
      for (lastadp = NULL, adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp;
           lastadp = adp, adp = TAILQ_NEXT(adp, ad_next)) {
            if (adp->ad_lbn >= NDADDR)
                  break;
            dp->di_db[adp->ad_lbn] = adp->ad_oldblkno;
            /* keep going until hitting a rollback to a frag */
            if (adp->ad_oldsize == 0 || adp->ad_oldsize == fs->fs_bsize)
                  continue;
            dp->di_size = fs->fs_bsize * adp->ad_lbn + adp->ad_oldsize;
            for (i = adp->ad_lbn + 1; i < NDADDR; i++) {
#ifdef DIAGNOSTIC
                  if (dp->di_db[i] != 0 && (deplist & (1 << i)) == 0)
                        panic("softdep_write_inodeblock: lost dep2");
#endif /* DIAGNOSTIC */
                  dp->di_db[i] = 0;
            }
            for (i = 0; i < NIADDR; i++) {
#ifdef DIAGNOSTIC
                  if (dp->di_ib[i] != 0 &&
                      (deplist & ((1 << NDADDR) << i)) == 0)
                        panic("softdep_write_inodeblock: lost dep3");
#endif /* DIAGNOSTIC */
                  dp->di_ib[i] = 0;
            }
            return;
      }
      /*
       * If we have zero'ed out the last allocated block of the file,
       * roll back the size to the last currently allocated block.
       * We know that this last allocated block is a full-sized as
       * we already checked for fragments in the loop above.
       */
      if (lastadp != NULL &&
          dp->di_size <= (lastadp->ad_lbn + 1) * fs->fs_bsize) {
            for (i = lastadp->ad_lbn; i >= 0; i--)
                  if (dp->di_db[i] != 0)
                        break;
            dp->di_size = (i + 1) * fs->fs_bsize;
      }
      /*
       * The only dependencies are for indirect blocks.
       *
       * The file size for indirect block additions is not guaranteed.
       * Such a guarantee would be non-trivial to achieve. The conventional
       * synchronous write implementation also does not make this guarantee.
       * Fsck should catch and fix discrepancies. Arguably, the file size
       * can be over-estimated without destroying integrity when the file
       * moves into the indirect blocks (i.e., is large). If we want to
       * postpone fsck, we are stuck with this argument.
       */
      for (; adp; adp = TAILQ_NEXT(adp, ad_next))
            dp->di_ib[adp->ad_lbn - NDADDR] = 0;
}

/*
 * This routine is called during the completion interrupt
 * service routine for a disk write (from the procedure called
 * by the device driver to inform the filesystem caches of
 * a request completion).  It should be called early in this
 * procedure, before the block is made available to other
 * processes or other routines are called.
 */
static void 
softdep_disk_write_complete(bp)
      struct buf *bp;         /* describes the completed disk write */
{
      struct worklist *wk;
      struct worklist *owk;
      struct workhead reattach;
      struct newblk *newblk;
      struct allocindir *aip;
      struct allocdirect *adp;
      struct indirdep *indirdep;
      struct inodedep *inodedep;
      struct bmsafemap *bmsafemap;

      /*
       * If an error occurred while doing the write, then the data
       * has not hit the disk and the dependencies cannot be unrolled.
       */
      if ((bp->b_ioflags & BIO_ERROR) != 0 && (bp->b_flags & B_INVAL) == 0)
            return;
      LIST_INIT(&reattach);
      /*
       * This lock must not be released anywhere in this code segment.
       */
      ACQUIRE_LOCK(&lk);
      owk = NULL;
      while ((wk = LIST_FIRST(&bp->b_dep)) != NULL) {
            WORKLIST_REMOVE(wk);
            if (wk == owk)
                  panic("duplicate worklist: %p\n", wk);
            owk = wk;
            switch (wk->wk_type) {

            case D_PAGEDEP:
                  if (handle_written_filepage(WK_PAGEDEP(wk), bp))
                        WORKLIST_INSERT(&reattach, wk);
                  continue;

            case D_INODEDEP:
                  if (handle_written_inodeblock(WK_INODEDEP(wk), bp))
                        WORKLIST_INSERT(&reattach, wk);
                  continue;

            case D_BMSAFEMAP:
                  bmsafemap = WK_BMSAFEMAP(wk);
                  while ((newblk = LIST_FIRST(&bmsafemap->sm_newblkhd))) {
                        newblk->nb_state |= DEPCOMPLETE;
                        newblk->nb_bmsafemap = NULL;
                        LIST_REMOVE(newblk, nb_deps);
                  }
                  while ((adp =
                     LIST_FIRST(&bmsafemap->sm_allocdirecthd))) {
                        adp->ad_state |= DEPCOMPLETE;
                        adp->ad_buf = NULL;
                        LIST_REMOVE(adp, ad_deps);
                        handle_allocdirect_partdone(adp);
                  }
                  while ((aip =
                      LIST_FIRST(&bmsafemap->sm_allocindirhd))) {
                        aip->ai_state |= DEPCOMPLETE;
                        aip->ai_buf = NULL;
                        LIST_REMOVE(aip, ai_deps);
                        handle_allocindir_partdone(aip);
                  }
                  while ((inodedep =
                       LIST_FIRST(&bmsafemap->sm_inodedephd)) != NULL) {
                        inodedep->id_state |= DEPCOMPLETE;
                        LIST_REMOVE(inodedep, id_deps);
                        inodedep->id_buf = NULL;
                  }
                  WORKITEM_FREE(bmsafemap, D_BMSAFEMAP);
                  continue;

            case D_MKDIR:
                  handle_written_mkdir(WK_MKDIR(wk), MKDIR_BODY);
                  continue;

            case D_ALLOCDIRECT:
                  adp = WK_ALLOCDIRECT(wk);
                  adp->ad_state |= COMPLETE;
                  handle_allocdirect_partdone(adp);
                  continue;

            case D_ALLOCINDIR:
                  aip = WK_ALLOCINDIR(wk);
                  aip->ai_state |= COMPLETE;
                  handle_allocindir_partdone(aip);
                  continue;

            case D_INDIRDEP:
                  indirdep = WK_INDIRDEP(wk);
                  if (indirdep->ir_state & GOINGAWAY)
                        panic("disk_write_complete: indirdep gone");
                  bcopy(indirdep->ir_saveddata, bp->b_data, bp->b_bcount);
                  FREE(indirdep->ir_saveddata, M_INDIRDEP);
                  indirdep->ir_saveddata = 0;
                  indirdep->ir_state &= ~UNDONE;
                  indirdep->ir_state |= ATTACHED;
                  while ((aip = LIST_FIRST(&indirdep->ir_donehd)) != 0) {
                        handle_allocindir_partdone(aip);
                        if (aip == LIST_FIRST(&indirdep->ir_donehd))
                              panic("disk_write_complete: not gone");
                  }
                  WORKLIST_INSERT(&reattach, wk);
                  if ((bp->b_flags & B_DELWRI) == 0)
                        stat_indir_blk_ptrs++;
                  bdirty(bp);
                  continue;

            default:
                  panic("handle_disk_write_complete: Unknown type %s",
                      TYPENAME(wk->wk_type));
                  /* NOTREACHED */
            }
      }
      /*
       * Reattach any requests that must be redone.
       */
      while ((wk = LIST_FIRST(&reattach)) != NULL) {
            WORKLIST_REMOVE(wk);
            WORKLIST_INSERT(&bp->b_dep, wk);
      }
      FREE_LOCK(&lk);
}

/*
 * Called from within softdep_disk_write_complete above. Note that
 * this routine is always called from interrupt level with further
 * splbio interrupts blocked.
 */
static void 
handle_allocdirect_partdone(adp)
      struct allocdirect *adp;      /* the completed allocdirect */
{
      struct allocdirectlst *listhead;
      struct allocdirect *listadp;
      struct inodedep *inodedep;
      long bsize, delay;

      if ((adp->ad_state & ALLCOMPLETE) != ALLCOMPLETE)
            return;
      if (adp->ad_buf != NULL)
            panic("handle_allocdirect_partdone: dangling dep");
      /*
       * The on-disk inode cannot claim to be any larger than the last
       * fragment that has been written. Otherwise, the on-disk inode
       * might have fragments that were not the last block in the file
       * which would corrupt the filesystem. Thus, we cannot free any
       * allocdirects after one whose ad_oldblkno claims a fragment as
       * these blocks must be rolled back to zero before writing the inode.
       * We check the currently active set of allocdirects in id_inoupdt
       * or id_extupdt as appropriate.
       */
      inodedep = adp->ad_inodedep;
      bsize = inodedep->id_fs->fs_bsize;
      if (adp->ad_state & EXTDATA)
            listhead = &inodedep->id_extupdt;
      else
            listhead = &inodedep->id_inoupdt;
      TAILQ_FOREACH(listadp, listhead, ad_next) {
            /* found our block */
            if (listadp == adp)
                  break;
            /* continue if ad_oldlbn is not a fragment */
            if (listadp->ad_oldsize == 0 ||
                listadp->ad_oldsize == bsize)
                  continue;
            /* hit a fragment */
            return;
      }
      /*
       * If we have reached the end of the current list without
       * finding the just finished dependency, then it must be
       * on the future dependency list. Future dependencies cannot
       * be freed until they are moved to the current list.
       */
      if (listadp == NULL) {
#ifdef DEBUG
            if (adp->ad_state & EXTDATA)
                  listhead = &inodedep->id_newextupdt;
            else
                  listhead = &inodedep->id_newinoupdt;
            TAILQ_FOREACH(listadp, listhead, ad_next)
                  /* found our block */
                  if (listadp == adp)
                        break;
            if (listadp == NULL)
                  panic("handle_allocdirect_partdone: lost dep");
#endif /* DEBUG */
            return;
      }
      /*
       * If we have found the just finished dependency, then free
       * it along with anything that follows it that is complete.
       * If the inode still has a bitmap dependency, then it has
       * never been written to disk, hence the on-disk inode cannot
       * reference the old fragment so we can free it without delay.
       */
      delay = (inodedep->id_state & DEPCOMPLETE);
      for (; adp; adp = listadp) {
            listadp = TAILQ_NEXT(adp, ad_next);
            if ((adp->ad_state & ALLCOMPLETE) != ALLCOMPLETE)
                  return;
            free_allocdirect(listhead, adp, delay);
      }
}

/*
 * Called from within softdep_disk_write_complete above. Note that
 * this routine is always called from interrupt level with further
 * splbio interrupts blocked.
 */
static void
handle_allocindir_partdone(aip)
      struct allocindir *aip;       /* the completed allocindir */
{
      struct indirdep *indirdep;

      if ((aip->ai_state & ALLCOMPLETE) != ALLCOMPLETE)
            return;
      if (aip->ai_buf != NULL)
            panic("handle_allocindir_partdone: dangling dependency");
      indirdep = aip->ai_indirdep;
      if (indirdep->ir_state & UNDONE) {
            LIST_REMOVE(aip, ai_next);
            LIST_INSERT_HEAD(&indirdep->ir_donehd, aip, ai_next);
            return;
      }
      if (indirdep->ir_state & UFS1FMT)
            ((ufs1_daddr_t *)indirdep->ir_savebp->b_data)[aip->ai_offset] =
                aip->ai_newblkno;
      else
            ((ufs2_daddr_t *)indirdep->ir_savebp->b_data)[aip->ai_offset] =
                aip->ai_newblkno;
      LIST_REMOVE(aip, ai_next);
      if (aip->ai_freefrag != NULL)
            add_to_worklist(&aip->ai_freefrag->ff_list);
      WORKITEM_FREE(aip, D_ALLOCINDIR);
}

/*
 * Called from within softdep_disk_write_complete above to restore
 * in-memory inode block contents to their most up-to-date state. Note
 * that this routine is always called from interrupt level with further
 * splbio interrupts blocked.
 */
static int 
handle_written_inodeblock(inodedep, bp)
      struct inodedep *inodedep;
      struct buf *bp;         /* buffer containing the inode block */
{
      struct worklist *wk, *filefree;
      struct allocdirect *adp, *nextadp;
      struct ufs1_dinode *dp1 = NULL;
      struct ufs2_dinode *dp2 = NULL;
      int hadchanges, fstype;

      if ((inodedep->id_state & IOSTARTED) == 0)
            panic("handle_written_inodeblock: not started");
      inodedep->id_state &= ~IOSTARTED;
      if (inodedep->id_fs->fs_magic == FS_UFS1_MAGIC) {
            fstype = UFS1;
            dp1 = (struct ufs1_dinode *)bp->b_data +
                ino_to_fsbo(inodedep->id_fs, inodedep->id_ino);
      } else {
            fstype = UFS2;
            dp2 = (struct ufs2_dinode *)bp->b_data +
                ino_to_fsbo(inodedep->id_fs, inodedep->id_ino);
      }
      /*
       * If we had to rollback the inode allocation because of
       * bitmaps being incomplete, then simply restore it.
       * Keep the block dirty so that it will not be reclaimed until
       * all associated dependencies have been cleared and the
       * corresponding updates written to disk.
       */
      if (inodedep->id_savedino1 != NULL) {
            if (fstype == UFS1)
                  *dp1 = *inodedep->id_savedino1;
            else
                  *dp2 = *inodedep->id_savedino2;
            FREE(inodedep->id_savedino1, M_SAVEDINO);
            inodedep->id_savedino1 = NULL;
            if ((bp->b_flags & B_DELWRI) == 0)
                  stat_inode_bitmap++;
            bdirty(bp);
            return (1);
      }
      inodedep->id_state |= COMPLETE;
      /*
       * Roll forward anything that had to be rolled back before 
       * the inode could be updated.
       */
      hadchanges = 0;
      for (adp = TAILQ_FIRST(&inodedep->id_inoupdt); adp; adp = nextadp) {
            nextadp = TAILQ_NEXT(adp, ad_next);
            if (adp->ad_state & ATTACHED)
                  panic("handle_written_inodeblock: new entry");
            if (fstype == UFS1) {
                  if (adp->ad_lbn < NDADDR) {
                        if (dp1->di_db[adp->ad_lbn]!=adp->ad_oldblkno)
                              panic("%s %s #%jd mismatch %d != %jd",
                                  "handle_written_inodeblock:",
                                  "direct pointer",
                                  (intmax_t)adp->ad_lbn,
                                  dp1->di_db[adp->ad_lbn],
                                  (intmax_t)adp->ad_oldblkno);
                        dp1->di_db[adp->ad_lbn] = adp->ad_newblkno;
                  } else {
                        if (dp1->di_ib[adp->ad_lbn - NDADDR] != 0)
                              panic("%s: %s #%jd allocated as %d",
                                  "handle_written_inodeblock",
                                  "indirect pointer",
                                  (intmax_t)adp->ad_lbn - NDADDR,
                                  dp1->di_ib[adp->ad_lbn - NDADDR]);
                        dp1->di_ib[adp->ad_lbn - NDADDR] =
                            adp->ad_newblkno;
                  }
            } else {
                  if (adp->ad_lbn < NDADDR) {
                        if (dp2->di_db[adp->ad_lbn]!=adp->ad_oldblkno)
                              panic("%s: %s #%jd %s %jd != %jd",
                                  "handle_written_inodeblock",
                                  "direct pointer",
                                  (intmax_t)adp->ad_lbn, "mismatch",
                                  (intmax_t)dp2->di_db[adp->ad_lbn],
                                  (intmax_t)adp->ad_oldblkno);
                        dp2->di_db[adp->ad_lbn] = adp->ad_newblkno;
                  } else {
                        if (dp2->di_ib[adp->ad_lbn - NDADDR] != 0)
                              panic("%s: %s #%jd allocated as %jd",
                                  "handle_written_inodeblock",
                                  "indirect pointer",
                                  (intmax_t)adp->ad_lbn - NDADDR,
                                  (intmax_t)
                                  dp2->di_ib[adp->ad_lbn - NDADDR]);
                        dp2->di_ib[adp->ad_lbn - NDADDR] =
                            adp->ad_newblkno;
                  }
            }
            adp->ad_state &= ~UNDONE;
            adp->ad_state |= ATTACHED;
            hadchanges = 1;
      }
      for (adp = TAILQ_FIRST(&inodedep->id_extupdt); adp; adp = nextadp) {
            nextadp = TAILQ_NEXT(adp, ad_next);
            if (adp->ad_state & ATTACHED)
                  panic("handle_written_inodeblock: new entry");
            if (dp2->di_extb[adp->ad_lbn] != adp->ad_oldblkno)
                  panic("%s: direct pointers #%jd %s %jd != %jd",
                      "handle_written_inodeblock",
                      (intmax_t)adp->ad_lbn, "mismatch",
                      (intmax_t)dp2->di_extb[adp->ad_lbn],
                      (intmax_t)adp->ad_oldblkno);
            dp2->di_extb[adp->ad_lbn] = adp->ad_newblkno;
            adp->ad_state &= ~UNDONE;
            adp->ad_state |= ATTACHED;
            hadchanges = 1;
      }
      if (hadchanges && (bp->b_flags & B_DELWRI) == 0)
            stat_direct_blk_ptrs++;
      /*
       * Reset the file size to its most up-to-date value.
       */
      if (inodedep->id_savedsize == -1 || inodedep->id_savedextsize == -1)
            panic("handle_written_inodeblock: bad size");
      if (fstype == UFS1) {
            if (dp1->di_size != inodedep->id_savedsize) {
                  dp1->di_size = inodedep->id_savedsize;
                  hadchanges = 1;
            }
      } else {
            if (dp2->di_size != inodedep->id_savedsize) {
                  dp2->di_size = inodedep->id_savedsize;
                  hadchanges = 1;
            }
            if (dp2->di_extsize != inodedep->id_savedextsize) {
                  dp2->di_extsize = inodedep->id_savedextsize;
                  hadchanges = 1;
            }
      }
      inodedep->id_savedsize = -1;
      inodedep->id_savedextsize = -1;
      /*
       * If there were any rollbacks in the inode block, then it must be
       * marked dirty so that its will eventually get written back in
       * its correct form.
       */
      if (hadchanges)
            bdirty(bp);
      /*
       * Process any allocdirects that completed during the update.
       */
      if ((adp = TAILQ_FIRST(&inodedep->id_inoupdt)) != NULL)
            handle_allocdirect_partdone(adp);
      if ((adp = TAILQ_FIRST(&inodedep->id_extupdt)) != NULL)
            handle_allocdirect_partdone(adp);
      /*
       * Process deallocations that were held pending until the
       * inode had been written to disk. Freeing of the inode
       * is delayed until after all blocks have been freed to
       * avoid creation of new <vfsid, inum, lbn> triples
       * before the old ones have been deleted.
       */
      filefree = NULL;
      while ((wk = LIST_FIRST(&inodedep->id_bufwait)) != NULL) {
            WORKLIST_REMOVE(wk);
            switch (wk->wk_type) {

            case D_FREEFILE:
                  /*
                   * We defer adding filefree to the worklist until
                   * all other additions have been made to ensure
                   * that it will be done after all the old blocks
                   * have been freed.
                   */
                  if (filefree != NULL)
                        panic("handle_written_inodeblock: filefree");
                  filefree = wk;
                  continue;

            case D_MKDIR:
                  handle_written_mkdir(WK_MKDIR(wk), MKDIR_PARENT);
                  continue;

            case D_DIRADD:
                  diradd_inode_written(WK_DIRADD(wk), inodedep);
                  continue;

            case D_FREEBLKS:
                  wk->wk_state |= COMPLETE;
                  if ((wk->wk_state  & ALLCOMPLETE) != ALLCOMPLETE)
                        continue;
                   /* -- fall through -- */
            case D_FREEFRAG:
            case D_DIRREM:
                  add_to_worklist(wk);
                  continue;

            case D_NEWDIRBLK:
                  free_newdirblk(WK_NEWDIRBLK(wk));
                  continue;

            default:
                  panic("handle_written_inodeblock: Unknown type %s",
                      TYPENAME(wk->wk_type));
                  /* NOTREACHED */
            }
      }
      if (filefree != NULL) {
            if (free_inodedep(inodedep) == 0)
                  panic("handle_written_inodeblock: live inodedep");
            add_to_worklist(filefree);
            return (0);
      }

      /*
       * If no outstanding dependencies, free it.
       */
      if (free_inodedep(inodedep) ||
          (TAILQ_FIRST(&inodedep->id_inoupdt) == 0 &&
           TAILQ_FIRST(&inodedep->id_extupdt) == 0))
            return (0);
      return (hadchanges);
}

/*
 * Process a diradd entry after its dependent inode has been written.
 * This routine must be called with splbio interrupts blocked.
 */
static void
diradd_inode_written(dap, inodedep)
      struct diradd *dap;
      struct inodedep *inodedep;
{
      struct pagedep *pagedep;

      dap->da_state |= COMPLETE;
      if ((dap->da_state & ALLCOMPLETE) == ALLCOMPLETE) {
            if (dap->da_state & DIRCHG)
                  pagedep = dap->da_previous->dm_pagedep;
            else
                  pagedep = dap->da_pagedep;
            LIST_REMOVE(dap, da_pdlist);
            LIST_INSERT_HEAD(&pagedep->pd_pendinghd, dap, da_pdlist);
      }
      WORKLIST_INSERT(&inodedep->id_pendinghd, &dap->da_list);
}

/*
 * Handle the completion of a mkdir dependency.
 */
static void
handle_written_mkdir(mkdir, type)
      struct mkdir *mkdir;
      int type;
{
      struct diradd *dap;
      struct pagedep *pagedep;

      if (mkdir->md_state != type)
            panic("handle_written_mkdir: bad type");
      dap = mkdir->md_diradd;
      dap->da_state &= ~type;
      if ((dap->da_state & (MKDIR_PARENT | MKDIR_BODY)) == 0)
            dap->da_state |= DEPCOMPLETE;
      if ((dap->da_state & ALLCOMPLETE) == ALLCOMPLETE) {
            if (dap->da_state & DIRCHG)
                  pagedep = dap->da_previous->dm_pagedep;
            else
                  pagedep = dap->da_pagedep;
            LIST_REMOVE(dap, da_pdlist);
            LIST_INSERT_HEAD(&pagedep->pd_pendinghd, dap, da_pdlist);
      }
      LIST_REMOVE(mkdir, md_mkdirs);
      WORKITEM_FREE(mkdir, D_MKDIR);
}

/*
 * Called from within softdep_disk_write_complete above.
 * A write operation was just completed. Removed inodes can
 * now be freed and associated block pointers may be committed.
 * Note that this routine is always called from interrupt level
 * with further splbio interrupts blocked.
 */
static int 
handle_written_filepage(pagedep, bp)
      struct pagedep *pagedep;
      struct buf *bp;         /* buffer containing the written page */
{
      struct dirrem *dirrem;
      struct diradd *dap, *nextdap;
      struct direct *ep;
      int i, chgs;

      if ((pagedep->pd_state & IOSTARTED) == 0)
            panic("handle_written_filepage: not started");
      pagedep->pd_state &= ~IOSTARTED;
      /*
       * Process any directory removals that have been committed.
       */
      while ((dirrem = LIST_FIRST(&pagedep->pd_dirremhd)) != NULL) {
            LIST_REMOVE(dirrem, dm_next);
            dirrem->dm_dirinum = pagedep->pd_ino;
            add_to_worklist(&dirrem->dm_list);
      }
      /*
       * Free any directory additions that have been committed.
       * If it is a newly allocated block, we have to wait until
       * the on-disk directory inode claims the new block.
       */
      if ((pagedep->pd_state & NEWBLOCK) == 0)
            while ((dap = LIST_FIRST(&pagedep->pd_pendinghd)) != NULL)
                  free_diradd(dap);
      /*
       * Uncommitted directory entries must be restored.
       */
      for (chgs = 0, i = 0; i < DAHASHSZ; i++) {
            for (dap = LIST_FIRST(&pagedep->pd_diraddhd[i]); dap;
                 dap = nextdap) {
                  nextdap = LIST_NEXT(dap, da_pdlist);
                  if (dap->da_state & ATTACHED)
                        panic("handle_written_filepage: attached");
                  ep = (struct direct *)
                      ((char *)bp->b_data + dap->da_offset);
                  ep->d_ino = dap->da_newinum;
                  dap->da_state &= ~UNDONE;
                  dap->da_state |= ATTACHED;
                  chgs = 1;
                  /*
                   * If the inode referenced by the directory has
                   * been written out, then the dependency can be
                   * moved to the pending list.
                   */
                  if ((dap->da_state & ALLCOMPLETE) == ALLCOMPLETE) {
                        LIST_REMOVE(dap, da_pdlist);
                        LIST_INSERT_HEAD(&pagedep->pd_pendinghd, dap,
                            da_pdlist);
                  }
            }
      }
      /*
       * If there were any rollbacks in the directory, then it must be
       * marked dirty so that its will eventually get written back in
       * its correct form.
       */
      if (chgs) {
            if ((bp->b_flags & B_DELWRI) == 0)
                  stat_dir_entry++;
            bdirty(bp);
            return (1);
      }
      /*
       * If we are not waiting for a new directory block to be
       * claimed by its inode, then the pagedep will be freed.
       * Otherwise it will remain to track any new entries on
       * the page in case they are fsync'ed.
       */
      if ((pagedep->pd_state & NEWBLOCK) == 0) {
            LIST_REMOVE(pagedep, pd_hash);
            WORKITEM_FREE(pagedep, D_PAGEDEP);
      }
      return (0);
}

/*
 * Writing back in-core inode structures.
 * 
 * The filesystem only accesses an inode's contents when it occupies an
 * "in-core" inode structure.  These "in-core" structures are separate from
 * the page frames used to cache inode blocks.  Only the latter are
 * transferred to/from the disk.  So, when the updated contents of the
 * "in-core" inode structure are copied to the corresponding in-memory inode
 * block, the dependencies are also transferred.  The following procedure is
 * called when copying a dirty "in-core" inode to a cached inode block.
 */

/*
 * Called when an inode is loaded from disk. If the effective link count
 * differed from the actual link count when it was last flushed, then we
 * need to ensure that the correct effective link count is put back.
 */
void 
softdep_load_inodeblock(ip)
      struct inode *ip; /* the "in_core" copy of the inode */
{
      struct inodedep *inodedep;

      /*
       * Check for alternate nlink count.
       */
      ip->i_effnlink = ip->i_nlink;
      ACQUIRE_LOCK(&lk);
      if (inodedep_lookup(UFSTOVFS(ip->i_ump),
          ip->i_number, 0, &inodedep) == 0) {
            FREE_LOCK(&lk);
            return;
      }
      ip->i_effnlink -= inodedep->id_nlinkdelta;
      if (inodedep->id_state & SPACECOUNTED)
            ip->i_flag |= IN_SPACECOUNTED;
      FREE_LOCK(&lk);
}

/*
 * This routine is called just before the "in-core" inode
 * information is to be copied to the in-memory inode block.
 * Recall that an inode block contains several inodes. If
 * the force flag is set, then the dependencies will be
 * cleared so that the update can always be made. Note that
 * the buffer is locked when this routine is called, so we
 * will never be in the middle of writing the inode block 
 * to disk.
 */
void 
softdep_update_inodeblock(ip, bp, waitfor)
      struct inode *ip; /* the "in_core" copy of the inode */
      struct buf *bp;         /* the buffer containing the inode block */
      int waitfor;            /* nonzero => update must be allowed */
{
      struct inodedep *inodedep;
      struct worklist *wk;
      struct mount *mp;
      struct buf *ibp;
      int error;

      /*
       * If the effective link count is not equal to the actual link
       * count, then we must track the difference in an inodedep while
       * the inode is (potentially) tossed out of the cache. Otherwise,
       * if there is no existing inodedep, then there are no dependencies
       * to track.
       */
      mp = UFSTOVFS(ip->i_ump);
      ACQUIRE_LOCK(&lk);
      if (inodedep_lookup(mp, ip->i_number, 0, &inodedep) == 0) {
            FREE_LOCK(&lk);
            if (ip->i_effnlink != ip->i_nlink)
                  panic("softdep_update_inodeblock: bad link count");
            return;
      }
      if (inodedep->id_nlinkdelta != ip->i_nlink - ip->i_effnlink)
            panic("softdep_update_inodeblock: bad delta");
      /*
       * Changes have been initiated. Anything depending on these
       * changes cannot occur until this inode has been written.
       */
      inodedep->id_state &= ~COMPLETE;
      if ((inodedep->id_state & ONWORKLIST) == 0)
            WORKLIST_INSERT(&bp->b_dep, &inodedep->id_list);
      /*
       * Any new dependencies associated with the incore inode must 
       * now be moved to the list associated with the buffer holding
       * the in-memory copy of the inode. Once merged process any
       * allocdirects that are completed by the merger.
       */
      merge_inode_lists(&inodedep->id_newinoupdt, &inodedep->id_inoupdt);
      if (!TAILQ_EMPTY(&inodedep->id_inoupdt))
            handle_allocdirect_partdone(TAILQ_FIRST(&inodedep->id_inoupdt));
      merge_inode_lists(&inodedep->id_newextupdt, &inodedep->id_extupdt);
      if (!TAILQ_EMPTY(&inodedep->id_extupdt))
            handle_allocdirect_partdone(TAILQ_FIRST(&inodedep->id_extupdt));
      /*
       * Now that the inode has been pushed into the buffer, the
       * operations dependent on the inode being written to disk
       * can be moved to the id_bufwait so that they will be
       * processed when the buffer I/O completes.
       */
      while ((wk = LIST_FIRST(&inodedep->id_inowait)) != NULL) {
            WORKLIST_REMOVE(wk);
            WORKLIST_INSERT(&inodedep->id_bufwait, wk);
      }
      /*
       * Newly allocated inodes cannot be written until the bitmap
       * that allocates them have been written (indicated by
       * DEPCOMPLETE being set in id_state). If we are doing a
       * forced sync (e.g., an fsync on a file), we force the bitmap
       * to be written so that the update can be done.
       */
      if (waitfor == 0) {
            FREE_LOCK(&lk);
            return;
      }
retry:
      if ((inodedep->id_state & DEPCOMPLETE) != 0) {
            FREE_LOCK(&lk);
            return;
      }
      ibp = inodedep->id_buf;
      ibp = getdirtybuf(ibp, &lk, MNT_WAIT);
      if (ibp == NULL) {
            /*
             * If ibp came back as NULL, the dependency could have been
             * freed while we slept.  Look it up again, and check to see
             * that it has completed.
             */
            if (inodedep_lookup(mp, ip->i_number, 0, &inodedep) != 0)
                  goto retry;
            FREE_LOCK(&lk);
            return;
      }
      FREE_LOCK(&lk);
      if ((error = bwrite(ibp)) != 0)
            softdep_error("softdep_update_inodeblock: bwrite", error);
}

/*
 * Merge the a new inode dependency list (such as id_newinoupdt) into an
 * old inode dependency list (such as id_inoupdt). This routine must be
 * called with splbio interrupts blocked.
 */
static void
merge_inode_lists(newlisthead, oldlisthead)
      struct allocdirectlst *newlisthead;
      struct allocdirectlst *oldlisthead;
{
      struct allocdirect *listadp, *newadp;

      newadp = TAILQ_FIRST(newlisthead);
      for (listadp = TAILQ_FIRST(oldlisthead); listadp && newadp;) {
            if (listadp->ad_lbn < newadp->ad_lbn) {
                  listadp = TAILQ_NEXT(listadp, ad_next);
                  continue;
            }
            TAILQ_REMOVE(newlisthead, newadp, ad_next);
            TAILQ_INSERT_BEFORE(listadp, newadp, ad_next);
            if (listadp->ad_lbn == newadp->ad_lbn) {
                  allocdirect_merge(oldlisthead, newadp,
                      listadp);
                  listadp = newadp;
            }
            newadp = TAILQ_FIRST(newlisthead);
      }
      while ((newadp = TAILQ_FIRST(newlisthead)) != NULL) {
            TAILQ_REMOVE(newlisthead, newadp, ad_next);
            TAILQ_INSERT_TAIL(oldlisthead, newadp, ad_next);
      }
}

/*
 * If we are doing an fsync, then we must ensure that any directory
 * entries for the inode have been written after the inode gets to disk.
 */
int
softdep_fsync(vp)
      struct vnode *vp; /* the "in_core" copy of the inode */
{
      struct inodedep *inodedep;
      struct pagedep *pagedep;
      struct worklist *wk;
      struct diradd *dap;
      struct mount *mp;
      struct vnode *pvp;
      struct inode *ip;
      struct buf *bp;
      struct fs *fs;
      struct thread *td = curthread;
      int error, flushparent, pagedep_new_block;
      ino_t parentino;
      ufs_lbn_t lbn;

      ip = VTOI(vp);
      fs = ip->i_fs;
      mp = vp->v_mount;
      ACQUIRE_LOCK(&lk);
      if (inodedep_lookup(mp, ip->i_number, 0, &inodedep) == 0) {
            FREE_LOCK(&lk);
            return (0);
      }
      if (!LIST_EMPTY(&inodedep->id_inowait) ||
          !LIST_EMPTY(&inodedep->id_bufwait) ||
          !TAILQ_EMPTY(&inodedep->id_extupdt) ||
          !TAILQ_EMPTY(&inodedep->id_newextupdt) ||
          !TAILQ_EMPTY(&inodedep->id_inoupdt) ||
          !TAILQ_EMPTY(&inodedep->id_newinoupdt))
            panic("softdep_fsync: pending ops");
      for (error = 0, flushparent = 0; ; ) {
            if ((wk = LIST_FIRST(&inodedep->id_pendinghd)) == NULL)
                  break;
            if (wk->wk_type != D_DIRADD)
                  panic("softdep_fsync: Unexpected type %s",
                      TYPENAME(wk->wk_type));
            dap = WK_DIRADD(wk);
            /*
             * Flush our parent if this directory entry has a MKDIR_PARENT
             * dependency or is contained in a newly allocated block.
             */
            if (dap->da_state & DIRCHG)
                  pagedep = dap->da_previous->dm_pagedep;
            else
                  pagedep = dap->da_pagedep;
            parentino = pagedep->pd_ino;
            lbn = pagedep->pd_lbn;
            if ((dap->da_state & (MKDIR_BODY | COMPLETE)) != COMPLETE)
                  panic("softdep_fsync: dirty");
            if ((dap->da_state & MKDIR_PARENT) ||
                (pagedep->pd_state & NEWBLOCK))
                  flushparent = 1;
            else
                  flushparent = 0;
            /*
             * If we are being fsync'ed as part of vgone'ing this vnode,
             * then we will not be able to release and recover the
             * vnode below, so we just have to give up on writing its
             * directory entry out. It will eventually be written, just
             * not now, but then the user was not asking to have it
             * written, so we are not breaking any promises.
             */
            if (vp->v_iflag & VI_DOOMED)
                  break;
            /*
             * We prevent deadlock by always fetching inodes from the
             * root, moving down the directory tree. Thus, when fetching
             * our parent directory, we first try to get the lock. If
             * that fails, we must unlock ourselves before requesting
             * the lock on our parent. See the comment in ufs_lookup
             * for details on possible races.
             */
            FREE_LOCK(&lk);
            if (ffs_vget(mp, parentino, LK_NOWAIT | LK_EXCLUSIVE, &pvp)) {
                  VOP_UNLOCK(vp, 0, td);
                  error = ffs_vget(mp, parentino, LK_EXCLUSIVE, &pvp);
                  vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, td);
                  if (error != 0)
                        return (error);
            }
            /*
             * All MKDIR_PARENT dependencies and all the NEWBLOCK pagedeps
             * that are contained in direct blocks will be resolved by 
             * doing a ffs_update. Pagedeps contained in indirect blocks
             * may require a complete sync'ing of the directory. So, we
             * try the cheap and fast ffs_update first, and if that fails,
             * then we do the slower ffs_syncvnode of the directory.
             */
            if (flushparent) {
                  int locked;

                  if ((error = ffs_update(pvp, 1)) != 0) {
                        vput(pvp);
                        return (error);
                  }
                  ACQUIRE_LOCK(&lk);
                  locked = 1;
                  if (inodedep_lookup(mp, ip->i_number, 0, &inodedep) != 0) {
                        if ((wk = LIST_FIRST(&inodedep->id_pendinghd)) != NULL) {
                              if (wk->wk_type != D_DIRADD)
                                    panic("softdep_fsync: Unexpected type %s",
                                          TYPENAME(wk->wk_type));
                              dap = WK_DIRADD(wk);
                              if (dap->da_state & DIRCHG)
                                    pagedep = dap->da_previous->dm_pagedep;
                              else
                                    pagedep = dap->da_pagedep;
                              pagedep_new_block = pagedep->pd_state & NEWBLOCK;
                              FREE_LOCK(&lk);
                              locked = 0;
                              if (pagedep_new_block &&
                                  (error = ffs_syncvnode(pvp, MNT_WAIT))) {
                                    vput(pvp);
                                    return (error);
                              }
                        }
                  }
                  if (locked)
                        FREE_LOCK(&lk);
            }
            /*
             * Flush directory page containing the inode's name.
             */
            error = bread(pvp, lbn, blksize(fs, VTOI(pvp), lbn), td->td_ucred,
                &bp);
            if (error == 0)
                  error = bwrite(bp);
            else
                  brelse(bp);
            vput(pvp);
            if (error != 0)
                  return (error);
            ACQUIRE_LOCK(&lk);
            if (inodedep_lookup(mp, ip->i_number, 0, &inodedep) == 0)
                  break;
      }
      FREE_LOCK(&lk);
      return (0);
}

/*
 * Flush all the dirty bitmaps associated with the block device
 * before flushing the rest of the dirty blocks so as to reduce
 * the number of dependencies that will have to be rolled back.
 */
void
softdep_fsync_mountdev(vp)
      struct vnode *vp;
{
      struct buf *bp, *nbp;
      struct worklist *wk;

      if (!vn_isdisk(vp, NULL))
            panic("softdep_fsync_mountdev: vnode not a disk");
restart:
      ACQUIRE_LOCK(&lk);
      VI_LOCK(vp);
      TAILQ_FOREACH_SAFE(bp, &vp->v_bufobj.bo_dirty.bv_hd, b_bobufs, nbp) {
            /* 
             * If it is already scheduled, skip to the next buffer.
             */
            if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL))
                  continue;

            if ((bp->b_flags & B_DELWRI) == 0)
                  panic("softdep_fsync_mountdev: not dirty");
            /*
             * We are only interested in bitmaps with outstanding
             * dependencies.
             */
            if ((wk = LIST_FIRST(&bp->b_dep)) == NULL ||
                wk->wk_type != D_BMSAFEMAP ||
                (bp->b_vflags & BV_BKGRDINPROG)) {
                  BUF_UNLOCK(bp);
                  continue;
            }
            VI_UNLOCK(vp);
            FREE_LOCK(&lk);
            bremfree(bp);
            (void) bawrite(bp);
            goto restart;
      }
      FREE_LOCK(&lk);
      drain_output(vp);
      VI_UNLOCK(vp);
}

/*
 * This routine is called when we are trying to synchronously flush a
 * file. This routine must eliminate any filesystem metadata dependencies
 * so that the syncing routine can succeed by pushing the dirty blocks
 * associated with the file. If any I/O errors occur, they are returned.
 */
int
softdep_sync_metadata(struct vnode *vp)
{
      struct pagedep *pagedep;
      struct allocdirect *adp;
      struct allocindir *aip;
      struct buf *bp, *nbp;
      struct worklist *wk;
      int i, error, waitfor;

      if (!DOINGSOFTDEP(vp))
            return (0);
      /*
       * Ensure that any direct block dependencies have been cleared.
       */
      ACQUIRE_LOCK(&lk);
      if ((error = flush_inodedep_deps(vp->v_mount, VTOI(vp)->i_number))) {
            FREE_LOCK(&lk);
            return (error);
      }
      FREE_LOCK(&lk);
      /*
       * For most files, the only metadata dependencies are the
       * cylinder group maps that allocate their inode or blocks.
       * The block allocation dependencies can be found by traversing
       * the dependency lists for any buffers that remain on their
       * dirty buffer list. The inode allocation dependency will
       * be resolved when the inode is updated with MNT_WAIT.
       * This work is done in two passes. The first pass grabs most
       * of the buffers and begins asynchronously writing them. The
       * only way to wait for these asynchronous writes is to sleep
       * on the filesystem vnode which may stay busy for a long time
       * if the filesystem is active. So, instead, we make a second
       * pass over the dependencies blocking on each write. In the
       * usual case we will be blocking against a write that we
       * initiated, so when it is done the dependency will have been
       * resolved. Thus the second pass is expected to end quickly.
       */
      waitfor = MNT_NOWAIT;

top:
      /*
       * We must wait for any I/O in progress to finish so that
       * all potential buffers on the dirty list will be visible.
       */
      VI_LOCK(vp);
      drain_output(vp);
      while ((bp = TAILQ_FIRST(&vp->v_bufobj.bo_dirty.bv_hd)) != NULL) {
            bp = getdirtybuf(bp, VI_MTX(vp), MNT_WAIT);
            if (bp)
                  break;
      }
      VI_UNLOCK(vp);
      if (bp == NULL)
            return (0);
loop:
      /* While syncing snapshots, we must allow recursive lookups */
      bp->b_lock.lk_flags |= LK_CANRECURSE;
      ACQUIRE_LOCK(&lk);
      /*
       * As we hold the buffer locked, none of its dependencies
       * will disappear.
       */
      LIST_FOREACH(wk, &bp->b_dep, wk_list) {
            switch (wk->wk_type) {

            case D_ALLOCDIRECT:
                  adp = WK_ALLOCDIRECT(wk);
                  if (adp->ad_state & DEPCOMPLETE)
                        continue;
                  nbp = adp->ad_buf;
                  nbp = getdirtybuf(nbp, &lk, waitfor);
                  if (nbp == NULL)
                        continue;
                  FREE_LOCK(&lk);
                  if (waitfor == MNT_NOWAIT) {
                        bawrite(nbp);
                  } else if ((error = bwrite(nbp)) != 0) {
                        break;
                  }
                  ACQUIRE_LOCK(&lk);
                  continue;

            case D_ALLOCINDIR:
                  aip = WK_ALLOCINDIR(wk);
                  if (aip->ai_state & DEPCOMPLETE)
                        continue;
                  nbp = aip->ai_buf;
                  nbp = getdirtybuf(nbp, &lk, waitfor);
                  if (nbp == NULL)
                        continue;
                  FREE_LOCK(&lk);
                  if (waitfor == MNT_NOWAIT) {
                        bawrite(nbp);
                  } else if ((error = bwrite(nbp)) != 0) {
                        break;
                  }
                  ACQUIRE_LOCK(&lk);
                  continue;

            case D_INDIRDEP:
            restart:

                  LIST_FOREACH(aip, &WK_INDIRDEP(wk)->ir_deplisthd, ai_next) {
                        if (aip->ai_state & DEPCOMPLETE)
                              continue;
                        nbp = aip->ai_buf;
                        nbp = getdirtybuf(nbp, &lk, MNT_WAIT);
                        if (nbp == NULL)
                              goto restart;
                        FREE_LOCK(&lk);
                        if ((error = bwrite(nbp)) != 0) {
                              goto loop_end;
                        }
                        ACQUIRE_LOCK(&lk);
                        goto restart;
                  }
                  continue;

            case D_INODEDEP:
                  if ((error = flush_inodedep_deps(wk->wk_mp,
                      WK_INODEDEP(wk)->id_ino)) != 0) {
                        FREE_LOCK(&lk);
                        break;
                  }
                  continue;

            case D_PAGEDEP:
                  /*
                   * We are trying to sync a directory that may
                   * have dependencies on both its own metadata
                   * and/or dependencies on the inodes of any
                   * recently allocated files. We walk its diradd
                   * lists pushing out the associated inode.
                   */
                  pagedep = WK_PAGEDEP(wk);
                  for (i = 0; i < DAHASHSZ; i++) {
                        if (LIST_FIRST(&pagedep->pd_diraddhd[i]) == 0)
                              continue;
                        if ((error =
                            flush_pagedep_deps(vp, wk->wk_mp,
                                    &pagedep->pd_diraddhd[i]))) {
                              FREE_LOCK(&lk);
                              goto loop_end;
                        }
                  }
                  continue;

            case D_MKDIR:
                  /*
                   * This case should never happen if the vnode has
                   * been properly sync'ed. However, if this function
                   * is used at a place where the vnode has not yet
                   * been sync'ed, this dependency can show up. So,
                   * rather than panic, just flush it.
                   */
                  nbp = WK_MKDIR(wk)->md_buf;
                  nbp = getdirtybuf(nbp, &lk, waitfor);
                  if (nbp == NULL)
                        continue;
                  FREE_LOCK(&lk);
                  if (waitfor == MNT_NOWAIT) {
                        bawrite(nbp);
                  } else if ((error = bwrite(nbp)) != 0) {
                        break;
                  }
                  ACQUIRE_LOCK(&lk);
                  continue;

            case D_BMSAFEMAP:
                  /*
                   * This case should never happen if the vnode has
                   * been properly sync'ed. However, if this function
                   * is used at a place where the vnode has not yet
                   * been sync'ed, this dependency can show up. So,
                   * rather than panic, just flush it.
                   */
                  nbp = WK_BMSAFEMAP(wk)->sm_buf;
                  nbp = getdirtybuf(nbp, &lk, waitfor);
                  if (nbp == NULL)
                        continue;
                  FREE_LOCK(&lk);
                  if (waitfor == MNT_NOWAIT) {
                        bawrite(nbp);
                  } else if ((error = bwrite(nbp)) != 0) {
                        break;
                  }
                  ACQUIRE_LOCK(&lk);
                  continue;

            default:
                  panic("softdep_sync_metadata: Unknown type %s",
                      TYPENAME(wk->wk_type));
                  /* NOTREACHED */
            }
      loop_end:
            /* We reach here only in error and unlocked */
            if (error == 0)
                  panic("softdep_sync_metadata: zero error");
            bp->b_lock.lk_flags &= ~LK_CANRECURSE;
            bawrite(bp);
            return (error);
      }
      FREE_LOCK(&lk);
      VI_LOCK(vp);
      while ((nbp = TAILQ_NEXT(bp, b_bobufs)) != NULL) {
            nbp = getdirtybuf(nbp, VI_MTX(vp), MNT_WAIT);
            if (nbp)
                  break;
      }
      VI_UNLOCK(vp);
      bp->b_lock.lk_flags &= ~LK_CANRECURSE;
      bawrite(bp);
      if (nbp != NULL) {
            bp = nbp;
            goto loop;
      }
      /*
       * The brief unlock is to allow any pent up dependency
       * processing to be done. Then proceed with the second pass.
       */
      if (waitfor == MNT_NOWAIT) {
            waitfor = MNT_WAIT;
            goto top;
      }

      /*
       * If we have managed to get rid of all the dirty buffers,
       * then we are done. For certain directories and block
       * devices, we may need to do further work.
       *
       * We must wait for any I/O in progress to finish so that
       * all potential buffers on the dirty list will be visible.
       */
      VI_LOCK(vp);
      drain_output(vp);
      VI_UNLOCK(vp);
      return (0);
}

/*
 * Flush the dependencies associated with an inodedep.
 * Called with splbio blocked.
 */
static int
flush_inodedep_deps(mp, ino)
      struct mount *mp;
      ino_t ino;
{
      struct inodedep *inodedep;
      int error, waitfor;

      /*
       * This work is done in two passes. The first pass grabs most
       * of the buffers and begins asynchronously writing them. The
       * only way to wait for these asynchronous writes is to sleep
       * on the filesystem vnode which may stay busy for a long time
       * if the filesystem is active. So, instead, we make a second
       * pass over the dependencies blocking on each write. In the
       * usual case we will be blocking against a write that we
       * initiated, so when it is done the dependency will have been
       * resolved. Thus the second pass is expected to end quickly.
       * We give a brief window at the top of the loop to allow
       * any pending I/O to complete.
       */
      for (error = 0, waitfor = MNT_NOWAIT; ; ) {
            if (error)
                  return (error);
            FREE_LOCK(&lk);
            ACQUIRE_LOCK(&lk);
            if (inodedep_lookup(mp, ino, 0, &inodedep) == 0)
                  return (0);
            if (flush_deplist(&inodedep->id_inoupdt, waitfor, &error) ||
                flush_deplist(&inodedep->id_newinoupdt, waitfor, &error) ||
                flush_deplist(&inodedep->id_extupdt, waitfor, &error) ||
                flush_deplist(&inodedep->id_newextupdt, waitfor, &error))
                  continue;
            /*
             * If pass2, we are done, otherwise do pass 2.
             */
            if (waitfor == MNT_WAIT)
                  break;
            waitfor = MNT_WAIT;
      }
      /*
       * Try freeing inodedep in case all dependencies have been removed.
       */
      if (inodedep_lookup(mp, ino, 0, &inodedep) != 0)
            (void) free_inodedep(inodedep);
      return (0);
}

/*
 * Flush an inode dependency list.
 * Called with splbio blocked.
 */
static int
flush_deplist(listhead, waitfor, errorp)
      struct allocdirectlst *listhead;
      int waitfor;
      int *errorp;
{
      struct allocdirect *adp;
      struct buf *bp;

      mtx_assert(&lk, MA_OWNED);
      TAILQ_FOREACH(adp, listhead, ad_next) {
            if (adp->ad_state & DEPCOMPLETE)
                  continue;
            bp = adp->ad_buf;
            bp = getdirtybuf(bp, &lk, waitfor);
            if (bp == NULL) {
                  if (waitfor == MNT_NOWAIT)
                        continue;
                  return (1);
            }
            FREE_LOCK(&lk);
            if (waitfor == MNT_NOWAIT) {
                  bawrite(bp);
            } else if ((*errorp = bwrite(bp)) != 0) {
                  ACQUIRE_LOCK(&lk);
                  return (1);
            }
            ACQUIRE_LOCK(&lk);
            return (1);
      }
      return (0);
}

/*
 * Eliminate a pagedep dependency by flushing out all its diradd dependencies.
 * Called with splbio blocked.
 */
static int
flush_pagedep_deps(pvp, mp, diraddhdp)
      struct vnode *pvp;
      struct mount *mp;
      struct diraddhd *diraddhdp;
{
      struct inodedep *inodedep;
      struct ufsmount *ump;
      struct diradd *dap;
      struct vnode *vp;
      int error = 0;
      struct buf *bp;
      ino_t inum;
      struct worklist *wk;

      ump = VFSTOUFS(mp);
      while ((dap = LIST_FIRST(diraddhdp)) != NULL) {
            /*
             * Flush ourselves if this directory entry
             * has a MKDIR_PARENT dependency.
             */
            if (dap->da_state & MKDIR_PARENT) {
                  FREE_LOCK(&lk);
                  if ((error = ffs_update(pvp, 1)) != 0)
                        break;
                  ACQUIRE_LOCK(&lk);
                  /*
                   * If that cleared dependencies, go on to next.
                   */
                  if (dap != LIST_FIRST(diraddhdp))
                        continue;
                  if (dap->da_state & MKDIR_PARENT)
                        panic("flush_pagedep_deps: MKDIR_PARENT");
            }
            /*
             * A newly allocated directory must have its "." and
             * ".." entries written out before its name can be
             * committed in its parent. We do not want or need
             * the full semantics of a synchronous ffs_syncvnode as
             * that may end up here again, once for each directory
             * level in the filesystem. Instead, we push the blocks
             * and wait for them to clear. We have to fsync twice
             * because the first call may choose to defer blocks
             * that still have dependencies, but deferral will
             * happen at most once.
             */
            inum = dap->da_newinum;
            if (dap->da_state & MKDIR_BODY) {
                  FREE_LOCK(&lk);
                  if ((error = ffs_vget(mp, inum, LK_EXCLUSIVE, &vp)))
                        break;
                  if ((error=ffs_syncvnode(vp, MNT_NOWAIT)) ||
                      (error=ffs_syncvnode(vp, MNT_NOWAIT))) {
                        vput(vp);
                        break;
                  }
                  VI_LOCK(vp);
                  drain_output(vp);
                  /*
                   * If first block is still dirty with a D_MKDIR
                   * dependency then it needs to be written now.
                   */
                  for (;;) {
                        error = 0;
                        bp = gbincore(&vp->v_bufobj, 0);
                        if (bp == NULL)
                              break;      /* First block not present */
                        error = BUF_LOCK(bp,
                                     LK_EXCLUSIVE |
                                     LK_SLEEPFAIL |
                                     LK_INTERLOCK,
                                     VI_MTX(vp));
                        VI_LOCK(vp);
                        if (error == ENOLCK)
                              continue;   /* Slept, retry */
                        if (error != 0)
                              break;            /* Failed */
                        if ((bp->b_flags & B_DELWRI) == 0) {
                              BUF_UNLOCK(bp);
                              break;      /* Buffer not dirty */
                        }
                        for (wk = LIST_FIRST(&bp->b_dep);
                             wk != NULL;
                             wk = LIST_NEXT(wk, wk_list))
                              if (wk->wk_type == D_MKDIR)
                                    break;
                        if (wk == NULL)
                              BUF_UNLOCK(bp);   /* Dependency gone */
                        else {
                              /*
                               * D_MKDIR dependency remains,
                               * must write buffer to stable
                               * storage.
                               */
                              VI_UNLOCK(vp);
                              bremfree(bp);
                              error = bwrite(bp);
                              VI_LOCK(vp);
                        }
                        break;
                  }
                  VI_UNLOCK(vp);
                  vput(vp);
                  if (error != 0)
                        break;      /* Flushing of first block failed */
                  ACQUIRE_LOCK(&lk);
                  /*
                   * If that cleared dependencies, go on to next.
                   */
                  if (dap != LIST_FIRST(diraddhdp))
                        continue;
                  if (dap->da_state & MKDIR_BODY)
                        panic("flush_pagedep_deps: MKDIR_BODY");
            }
            /*
             * Flush the inode on which the directory entry depends.
             * Having accounted for MKDIR_PARENT and MKDIR_BODY above,
             * the only remaining dependency is that the updated inode
             * count must get pushed to disk. The inode has already
             * been pushed into its inode buffer (via VOP_UPDATE) at
             * the time of the reference count change. So we need only
             * locate that buffer, ensure that there will be no rollback
             * caused by a bitmap dependency, then write the inode buffer.
             */
retry:
            if (inodedep_lookup(UFSTOVFS(ump), inum, 0, &inodedep) == 0)
                  panic("flush_pagedep_deps: lost inode");
            /*
             * If the inode still has bitmap dependencies,
             * push them to disk.
             */
            if ((inodedep->id_state & DEPCOMPLETE) == 0) {
                  bp = inodedep->id_buf;
                  bp = getdirtybuf(bp, &lk, MNT_WAIT);
                  if (bp == NULL)
                        goto retry;
                  FREE_LOCK(&lk);
                  if ((error = bwrite(bp)) != 0)
                        break;
                  ACQUIRE_LOCK(&lk);
                  if (dap != LIST_FIRST(diraddhdp))
                        continue;
            }
            /*
             * If the inode is still sitting in a buffer waiting
             * to be written, push it to disk.
             */
            FREE_LOCK(&lk);
            if ((error = bread(ump->um_devvp,
                fsbtodb(ump->um_fs, ino_to_fsba(ump->um_fs, inum)),
                (int)ump->um_fs->fs_bsize, NOCRED, &bp)) != 0) {
                  brelse(bp);
                  break;
            }
            if ((error = bwrite(bp)) != 0)
                  break;
            ACQUIRE_LOCK(&lk);
            /*
             * If we have failed to get rid of all the dependencies
             * then something is seriously wrong.
             */
            if (dap == LIST_FIRST(diraddhdp))
                  panic("flush_pagedep_deps: flush failed");
      }
      if (error)
            ACQUIRE_LOCK(&lk);
      return (error);
}

/*
 * A large burst of file addition or deletion activity can drive the
 * memory load excessively high. First attempt to slow things down
 * using the techniques below. If that fails, this routine requests
 * the offending operations to fall back to running synchronously
 * until the memory load returns to a reasonable level.
 */
int
softdep_slowdown(vp)
      struct vnode *vp;
{
      int max_softdeps_hard;

      ACQUIRE_LOCK(&lk);
      max_softdeps_hard = max_softdeps * 11 / 10;
      if (num_dirrem < max_softdeps_hard / 2 &&
          num_inodedep < max_softdeps_hard &&
          VFSTOUFS(vp->v_mount)->um_numindirdeps < maxindirdeps) {
            FREE_LOCK(&lk);
            return (0);
      }
      if (VFSTOUFS(vp->v_mount)->um_numindirdeps >= maxindirdeps)
            softdep_speedup();
      stat_sync_limit_hit += 1;
      FREE_LOCK(&lk);
      return (1);
}

/*
 * Called by the allocation routines when they are about to fail
 * in the hope that we can free up some disk space.
 * 
 * First check to see if the work list has anything on it. If it has,
 * clean up entries until we successfully free some space. Because this
 * process holds inodes locked, we cannot handle any remove requests
 * that might block on a locked inode as that could lead to deadlock.
 * If the worklist yields no free space, encourage the syncer daemon
 * to help us. In no event will we try for longer than tickdelay seconds.
 */
int
softdep_request_cleanup(fs, vp)
      struct fs *fs;
      struct vnode *vp;
{
      struct ufsmount *ump;
      long starttime;
      ufs2_daddr_t needed;
      int error;

      ump = VTOI(vp)->i_ump;
      mtx_assert(UFS_MTX(ump), MA_OWNED);
      needed = fs->fs_cstotal.cs_nbfree + fs->fs_contigsumsize;
      starttime = time_second + tickdelay;
      /*
       * If we are being called because of a process doing a
       * copy-on-write, then it is not safe to update the vnode
       * as we may recurse into the copy-on-write routine.
       */
      if (!(curthread->td_pflags & TDP_COWINPROGRESS)) {
            UFS_UNLOCK(ump);
            error = ffs_update(vp, 1);
            UFS_LOCK(ump);
            if (error != 0)
                  return (0);
      }
      while (fs->fs_pendingblocks > 0 && fs->fs_cstotal.cs_nbfree <= needed) {
            if (time_second > starttime)
                  return (0);
            UFS_UNLOCK(ump);
            ACQUIRE_LOCK(&lk);
            if (ump->softdep_on_worklist > 0 &&
                process_worklist_item(UFSTOVFS(ump), LK_NOWAIT) != -1) {
                  stat_worklist_push += 1;
                  FREE_LOCK(&lk);
                  UFS_LOCK(ump);
                  continue;
            }
            request_cleanup(UFSTOVFS(ump), FLUSH_REMOVE_WAIT);
            FREE_LOCK(&lk);
            UFS_LOCK(ump);
      }
      return (1);
}

/*
 * If memory utilization has gotten too high, deliberately slow things
 * down and speed up the I/O processing.
 */
extern struct thread *syncertd;
static int
request_cleanup(mp, resource)
      struct mount *mp;
      int resource;
{
      struct thread *td = curthread;
      struct ufsmount *ump;

      mtx_assert(&lk, MA_OWNED);
      /*
       * We never hold up the filesystem syncer or buf daemon.
       */
      if (td->td_pflags & (TDP_SOFTDEP|TDP_NORUNNINGBUF))
            return (0);
      ump = VFSTOUFS(mp);
      /*
       * First check to see if the work list has gotten backlogged.
       * If it has, co-opt this process to help clean up two entries.
       * Because this process may hold inodes locked, we cannot
       * handle any remove requests that might block on a locked
       * inode as that could lead to deadlock.  We set TDP_SOFTDEP
       * to avoid recursively processing the worklist.
       */
      if (ump->softdep_on_worklist > max_softdeps / 10) {
            td->td_pflags |= TDP_SOFTDEP;
            process_worklist_item(mp, LK_NOWAIT);
            process_worklist_item(mp, LK_NOWAIT);
            td->td_pflags &= ~TDP_SOFTDEP;
            stat_worklist_push += 2;
            return(1);
      }
      /*
       * Next, we attempt to speed up the syncer process. If that
       * is successful, then we allow the process to continue.
       */
      if (softdep_speedup() && resource != FLUSH_REMOVE_WAIT)
            return(0);
      /*
       * If we are resource constrained on inode dependencies, try
       * flushing some dirty inodes. Otherwise, we are constrained
       * by file deletions, so try accelerating flushes of directories
       * with removal dependencies. We would like to do the cleanup
       * here, but we probably hold an inode locked at this point and 
       * that might deadlock against one that we try to clean. So,
       * the best that we can do is request the syncer daemon to do
       * the cleanup for us.
       */
      switch (resource) {

      case FLUSH_INODES:
            stat_ino_limit_push += 1;
            req_clear_inodedeps += 1;
            stat_countp = &stat_ino_limit_hit;
            break;

      case FLUSH_REMOVE:
      case FLUSH_REMOVE_WAIT:
            stat_blk_limit_push += 1;
            req_clear_remove += 1;
            stat_countp = &stat_blk_limit_hit;
            break;

      default:
            panic("request_cleanup: unknown type");
      }
      /*
       * Hopefully the syncer daemon will catch up and awaken us.
       * We wait at most tickdelay before proceeding in any case.
       */
      proc_waiting += 1;
      if (handle.callout == NULL)
            handle = timeout(pause_timer, 0, tickdelay > 2 ? tickdelay : 2);
      msleep((caddr_t)&proc_waiting, &lk, PPAUSE, "softupdate", 0);
      proc_waiting -= 1;
      return (1);
}

/*
 * Awaken processes pausing in request_cleanup and clear proc_waiting
 * to indicate that there is no longer a timer running.
 */
static void
pause_timer(arg)
      void *arg;
{

      ACQUIRE_LOCK(&lk);
      *stat_countp += 1;
      wakeup_one(&proc_waiting);
      if (proc_waiting > 0)
            handle = timeout(pause_timer, 0, tickdelay > 2 ? tickdelay : 2);
      else
            handle.callout = NULL;
      FREE_LOCK(&lk);
}

/*
 * Flush out a directory with at least one removal dependency in an effort to
 * reduce the number of dirrem, freefile, and freeblks dependency structures.
 */
static void
clear_remove(td)
      struct thread *td;
{
      struct pagedep_hashhead *pagedephd;
      struct pagedep *pagedep;
      static int next = 0;
      struct mount *mp;
      struct vnode *vp;
      int error, cnt;
      ino_t ino;

      mtx_assert(&lk, MA_OWNED);

      for (cnt = 0; cnt < pagedep_hash; cnt++) {
            pagedephd = &pagedep_hashtbl[next++];
            if (next >= pagedep_hash)
                  next = 0;
            LIST_FOREACH(pagedep, pagedephd, pd_hash) {
                  if (LIST_EMPTY(&pagedep->pd_dirremhd))
                        continue;
                  mp = pagedep->pd_list.wk_mp;
                  ino = pagedep->pd_ino;
                  if (vn_start_write(NULL, &mp, V_NOWAIT) != 0)
                        continue;
                  FREE_LOCK(&lk);
                  if ((error = ffs_vget(mp, ino, LK_EXCLUSIVE, &vp))) {
                        softdep_error("clear_remove: vget", error);
                        vn_finished_write(mp);
                        ACQUIRE_LOCK(&lk);
                        return;
                  }
                  if ((error = ffs_syncvnode(vp, MNT_NOWAIT)))
                        softdep_error("clear_remove: fsync", error);
                  VI_LOCK(vp);
                  drain_output(vp);
                  VI_UNLOCK(vp);
                  vput(vp);
                  vn_finished_write(mp);
                  ACQUIRE_LOCK(&lk);
                  return;
            }
      }
}

/*
 * Clear out a block of dirty inodes in an effort to reduce
 * the number of inodedep dependency structures.
 */
static void
clear_inodedeps(td)
      struct thread *td;
{
      struct inodedep_hashhead *inodedephd;
      struct inodedep *inodedep;
      static int next = 0;
      struct mount *mp;
      struct vnode *vp;
      struct fs *fs;
      int error, cnt;
      ino_t firstino, lastino, ino;

      mtx_assert(&lk, MA_OWNED);
      /*
       * Pick a random inode dependency to be cleared.
       * We will then gather up all the inodes in its block 
       * that have dependencies and flush them out.
       */
      for (cnt = 0; cnt < inodedep_hash; cnt++) {
            inodedephd = &inodedep_hashtbl[next++];
            if (next >= inodedep_hash)
                  next = 0;
            if ((inodedep = LIST_FIRST(inodedephd)) != NULL)
                  break;
      }
      if (inodedep == NULL)
            return;
      fs = inodedep->id_fs;
      mp = inodedep->id_list.wk_mp;
      /*
       * Find the last inode in the block with dependencies.
       */
      firstino = inodedep->id_ino & ~(INOPB(fs) - 1);
      for (lastino = firstino + INOPB(fs) - 1; lastino > firstino; lastino--)
            if (inodedep_lookup(mp, lastino, 0, &inodedep) != 0)
                  break;
      /*
       * Asynchronously push all but the last inode with dependencies.
       * Synchronously push the last inode with dependencies to ensure
       * that the inode block gets written to free up the inodedeps.
       */
      for (ino = firstino; ino <= lastino; ino++) {
            if (inodedep_lookup(mp, ino, 0, &inodedep) == 0)
                  continue;
            if (vn_start_write(NULL, &mp, V_NOWAIT) != 0)
                  continue;
            FREE_LOCK(&lk);
            if ((error = ffs_vget(mp, ino, LK_EXCLUSIVE, &vp)) != 0) {
                  softdep_error("clear_inodedeps: vget", error);
                  vn_finished_write(mp);
                  ACQUIRE_LOCK(&lk);
                  return;
            }
            if (ino == lastino) {
                  if ((error = ffs_syncvnode(vp, MNT_WAIT)))
                        softdep_error("clear_inodedeps: fsync1", error);
            } else {
                  if ((error = ffs_syncvnode(vp, MNT_NOWAIT)))
                        softdep_error("clear_inodedeps: fsync2", error);
                  VI_LOCK(vp);
                  drain_output(vp);
                  VI_UNLOCK(vp);
            }
            vput(vp);
            vn_finished_write(mp);
            ACQUIRE_LOCK(&lk);
      }
}

/*
 * Function to determine if the buffer has outstanding dependencies
 * that will cause a roll-back if the buffer is written. If wantcount
 * is set, return number of dependencies, otherwise just yes or no.
 */
static int
softdep_count_dependencies(bp, wantcount)
      struct buf *bp;
      int wantcount;
{
      struct worklist *wk;
      struct inodedep *inodedep;
      struct indirdep *indirdep;
      struct allocindir *aip;
      struct pagedep *pagedep;
      struct diradd *dap;
      int i, retval;

      retval = 0;
      ACQUIRE_LOCK(&lk);
      LIST_FOREACH(wk, &bp->b_dep, wk_list) {
            switch (wk->wk_type) {

            case D_INODEDEP:
                  inodedep = WK_INODEDEP(wk);
                  if ((inodedep->id_state & DEPCOMPLETE) == 0) {
                        /* bitmap allocation dependency */
                        retval += 1;
                        if (!wantcount)
                              goto out;
                  }
                  if (TAILQ_FIRST(&inodedep->id_inoupdt)) {
                        /* direct block pointer dependency */
                        retval += 1;
                        if (!wantcount)
                              goto out;
                  }
                  if (TAILQ_FIRST(&inodedep->id_extupdt)) {
                        /* direct block pointer dependency */
                        retval += 1;
                        if (!wantcount)
                              goto out;
                  }
                  continue;

            case D_INDIRDEP:
                  indirdep = WK_INDIRDEP(wk);

                  LIST_FOREACH(aip, &indirdep->ir_deplisthd, ai_next) {
                        /* indirect block pointer dependency */
                        retval += 1;
                        if (!wantcount)
                              goto out;
                  }
                  continue;

            case D_PAGEDEP:
                  pagedep = WK_PAGEDEP(wk);
                  for (i = 0; i < DAHASHSZ; i++) {

                        LIST_FOREACH(dap, &pagedep->pd_diraddhd[i], da_pdlist) {
                              /* directory entry dependency */
                              retval += 1;
                              if (!wantcount)
                                    goto out;
                        }
                  }
                  continue;

            case D_BMSAFEMAP:
            case D_ALLOCDIRECT:
            case D_ALLOCINDIR:
            case D_MKDIR:
                  /* never a dependency on these blocks */
                  continue;

            default:
                  panic("softdep_check_for_rollback: Unexpected type %s",
                      TYPENAME(wk->wk_type));
                  /* NOTREACHED */
            }
      }
out:
      FREE_LOCK(&lk);
      return retval;
}

/*
 * Acquire exclusive access to a buffer.
 * Must be called with a locked mtx parameter.
 * Return acquired buffer or NULL on failure.
 */
static struct buf *
getdirtybuf(bp, mtx, waitfor)
      struct buf *bp;
      struct mtx *mtx;
      int waitfor;
{
      int error;

      mtx_assert(mtx, MA_OWNED);
      if (BUF_LOCK(bp, LK_EXCLUSIVE | LK_NOWAIT, NULL) != 0) {
            if (waitfor != MNT_WAIT)
                  return (NULL);
            error = BUF_LOCK(bp,
                LK_EXCLUSIVE | LK_SLEEPFAIL | LK_INTERLOCK, mtx);
            /*
             * Even if we sucessfully acquire bp here, we have dropped
             * mtx, which may violates our guarantee.
             */
            if (error == 0)
                  BUF_UNLOCK(bp);
            else if (error != ENOLCK)
                  panic("getdirtybuf: inconsistent lock: %d", error);
            mtx_lock(mtx);
            return (NULL);
      }
      if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
            if (mtx == &lk && waitfor == MNT_WAIT) {
                  mtx_unlock(mtx);
                  BO_LOCK(bp->b_bufobj);
                  BUF_UNLOCK(bp);
                  if ((bp->b_vflags & BV_BKGRDINPROG) != 0) {
                        bp->b_vflags |= BV_BKGRDWAIT;
                        msleep(&bp->b_xflags, BO_MTX(bp->b_bufobj),
                               PRIBIO | PDROP, "getbuf", 0);
                  } else
                        BO_UNLOCK(bp->b_bufobj);
                  mtx_lock(mtx);
                  return (NULL);
            }
            BUF_UNLOCK(bp);
            if (waitfor != MNT_WAIT)
                  return (NULL);
            /*
             * The mtx argument must be bp->b_vp's mutex in
             * this case.
             */
#ifdef      DEBUG_VFS_LOCKS
            if (bp->b_vp->v_type != VCHR)
                  ASSERT_VI_LOCKED(bp->b_vp, "getdirtybuf");
#endif
            bp->b_vflags |= BV_BKGRDWAIT;
            msleep(&bp->b_xflags, mtx, PRIBIO, "getbuf", 0);
            return (NULL);
      }
      if ((bp->b_flags & B_DELWRI) == 0) {
            BUF_UNLOCK(bp);
            return (NULL);
      }
      bremfree(bp);
      return (bp);
}


/*
 * Check if it is safe to suspend the file system now.  On entry,
 * the vnode interlock for devvp should be held.  Return 0 with
 * the mount interlock held if the file system can be suspended now,
 * otherwise return EAGAIN with the mount interlock held.
 */
int
softdep_check_suspend(struct mount *mp,
                  struct vnode *devvp,
                  int softdep_deps,
                  int softdep_accdeps,
                  int secondary_writes,
                  int secondary_accwrites)
{
      struct bufobj *bo;
      struct ufsmount *ump;
      int error;

      ASSERT_VI_LOCKED(devvp, "softdep_check_suspend");
      ump = VFSTOUFS(mp);
      bo = &devvp->v_bufobj;

      for (;;) {
            if (!TRY_ACQUIRE_LOCK(&lk)) {
                  VI_UNLOCK(devvp);
                  ACQUIRE_LOCK(&lk);
                  FREE_LOCK(&lk);
                  VI_LOCK(devvp);
                  continue;
            }
            if (!MNT_ITRYLOCK(mp)) {
                  FREE_LOCK(&lk);
                  VI_UNLOCK(devvp);
                  MNT_ILOCK(mp);
                  MNT_IUNLOCK(mp);
                  VI_LOCK(devvp);
                  continue;
            }
            if (mp->mnt_secondary_writes != 0) {
                  FREE_LOCK(&lk);
                  VI_UNLOCK(devvp);
                  msleep(&mp->mnt_secondary_writes,
                         MNT_MTX(mp),
                         (PUSER - 1) | PDROP, "secwr", 0);
                  VI_LOCK(devvp);
                  continue;
            }
            break;
      }

      /*
       * Reasons for needing more work before suspend:
       * - Dirty buffers on devvp.
       * - Softdep activity occurred after start of vnode sync loop
       * - Secondary writes occurred after start of vnode sync loop
       */
      error = 0;
      if (bo->bo_numoutput > 0 ||
          bo->bo_dirty.bv_cnt > 0 ||
          softdep_deps != 0 ||
          ump->softdep_deps != 0 ||
          softdep_accdeps != ump->softdep_accdeps ||
          secondary_writes != 0 ||
          mp->mnt_secondary_writes != 0 ||
          secondary_accwrites != mp->mnt_secondary_accwrites)
            error = EAGAIN;
      FREE_LOCK(&lk);
      VI_UNLOCK(devvp);
      return (error);
}


/*
 * Get the number of dependency structures for the file system, both
 * the current number and the total number allocated.  These will
 * later be used to detect that softdep processing has occurred.
 */
void
softdep_get_depcounts(struct mount *mp,
                  int *softdep_depsp,
                  int *softdep_accdepsp)
{
      struct ufsmount *ump;

      ump = VFSTOUFS(mp);
      ACQUIRE_LOCK(&lk);
      *softdep_depsp = ump->softdep_deps;
      *softdep_accdepsp = ump->softdep_accdeps;
      FREE_LOCK(&lk);
}

/*
 * Wait for pending output on a vnode to complete.
 * Must be called with vnode lock and interlock locked.
 *
 * XXX: Should just be a call to bufobj_wwait().
 */
static void
drain_output(vp)
      struct vnode *vp;
{
      ASSERT_VOP_LOCKED(vp, "drain_output");
      ASSERT_VI_LOCKED(vp, "drain_output");

      while (vp->v_bufobj.bo_numoutput) {
            vp->v_bufobj.bo_flag |= BO_WWAIT;
            msleep((caddr_t)&vp->v_bufobj.bo_numoutput,
                VI_MTX(vp), PRIBIO + 1, "drainvp", 0);
      }
}

/*
 * Called whenever a buffer that is being invalidated or reallocated
 * contains dependencies. This should only happen if an I/O error has
 * occurred. The routine is called with the buffer locked.
 */ 
static void
softdep_deallocate_dependencies(bp)
      struct buf *bp;
{

      if ((bp->b_ioflags & BIO_ERROR) == 0)
            panic("softdep_deallocate_dependencies: dangling deps");
      softdep_error(bp->b_vp->v_mount->mnt_stat.f_mntonname, bp->b_error);
      panic("softdep_deallocate_dependencies: unrecovered I/O error");
}

/*
 * Function to handle asynchronous write errors in the filesystem.
 */
static void
softdep_error(func, error)
      char *func;
      int error;
{

      /* XXX should do something better! */
      printf("%s: got error %d while accessing filesystem\n", func, error);
}

#endif /* SOFTUPDATES */

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