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ffs_alloc.c

/*-
 * Copyright (c) 2002 Networks Associates Technology, Inc.
 * All rights reserved.
 *
 * This software was developed for the FreeBSD Project by Marshall
 * Kirk McKusick and Network Associates Laboratories, the Security
 * Research Division of Network Associates, Inc. under DARPA/SPAWAR
 * contract N66001-01-C-8035 ("CBOSS"), as part of the DARPA CHATS
 * research program
 *
 * 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 THE AUTHOR AND CONTRIBUTORS ``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 THE AUTHOR OR CONTRIBUTORS 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.
 *
 * Copyright (c) 1982, 1986, 1989, 1993
 *    The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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.
 *
 *    @(#)ffs_alloc.c   8.18 (Berkeley) 5/26/95
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/sys/ufs/ffs/ffs_alloc.c,v 1.147 2007/09/10 14:12:29 bz Exp $");

#include "opt_quota.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
#include <sys/conf.h>
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/kernel.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>

#include <ufs/ufs/extattr.h>
#include <ufs/ufs/quota.h>
#include <ufs/ufs/inode.h>
#include <ufs/ufs/ufs_extern.h>
#include <ufs/ufs/ufsmount.h>

#include <ufs/ffs/fs.h>
#include <ufs/ffs/ffs_extern.h>

typedef ufs2_daddr_t allocfcn_t(struct inode *ip, int cg, ufs2_daddr_t bpref,
                          int size);

static ufs2_daddr_t ffs_alloccg(struct inode *, int, ufs2_daddr_t, int);
static ufs2_daddr_t
            ffs_alloccgblk(struct inode *, struct buf *, ufs2_daddr_t);
#ifdef DIAGNOSTIC
static int  ffs_checkblk(struct inode *, ufs2_daddr_t, long);
#endif
static ufs2_daddr_t ffs_clusteralloc(struct inode *, int, ufs2_daddr_t, int);
static void ffs_clusteracct(struct ufsmount *, struct fs *, struct cg *,
                ufs1_daddr_t, int);
static ino_t      ffs_dirpref(struct inode *);
static ufs2_daddr_t ffs_fragextend(struct inode *, int, ufs2_daddr_t, int, int);
static void ffs_fserr(struct fs *, ino_t, char *);
static ufs2_daddr_t     ffs_hashalloc
            (struct inode *, int, ufs2_daddr_t, int, allocfcn_t *);
static ufs2_daddr_t ffs_nodealloccg(struct inode *, int, ufs2_daddr_t, int);
static ufs1_daddr_t ffs_mapsearch(struct fs *, struct cg *, ufs2_daddr_t, int);
static int  ffs_reallocblks_ufs1(struct vop_reallocblks_args *);
static int  ffs_reallocblks_ufs2(struct vop_reallocblks_args *);

/*
 * Allocate a block in the filesystem.
 *
 * The size of the requested block is given, which must be some
 * multiple of fs_fsize and <= fs_bsize.
 * A preference may be optionally specified. If a preference is given
 * the following hierarchy is used to allocate a block:
 *   1) allocate the requested block.
 *   2) allocate a rotationally optimal block in the same cylinder.
 *   3) allocate a block in the same cylinder group.
 *   4) quadradically rehash into other cylinder groups, until an
 *      available block is located.
 * If no block preference is given the following hierarchy is used
 * to allocate a block:
 *   1) allocate a block in the cylinder group that contains the
 *      inode for the file.
 *   2) quadradically rehash into other cylinder groups, until an
 *      available block is located.
 */
int
ffs_alloc(ip, lbn, bpref, size, cred, bnp)
      struct inode *ip;
      ufs2_daddr_t lbn, bpref;
      int size;
      struct ucred *cred;
      ufs2_daddr_t *bnp;
{
      struct fs *fs;
      struct ufsmount *ump;
      ufs2_daddr_t bno;
      int cg, reclaimed;
      static struct timeval lastfail;
      static int curfail;
      int64_t delta;
#ifdef QUOTA
      int error;
#endif

      *bnp = 0;
      fs = ip->i_fs;
      ump = ip->i_ump;
      mtx_assert(UFS_MTX(ump), MA_OWNED);
#ifdef DIAGNOSTIC
      if ((u_int)size > fs->fs_bsize || fragoff(fs, size) != 0) {
            printf("dev = %s, bsize = %ld, size = %d, fs = %s\n",
                devtoname(ip->i_dev), (long)fs->fs_bsize, size,
                fs->fs_fsmnt);
            panic("ffs_alloc: bad size");
      }
      if (cred == NOCRED)
            panic("ffs_alloc: missing credential");
#endif /* DIAGNOSTIC */
      reclaimed = 0;
retry:
#ifdef QUOTA
      UFS_UNLOCK(ump);
      error = chkdq(ip, btodb(size), cred, 0);
      if (error)
            return (error);
      UFS_LOCK(ump);
#endif
      if (size == fs->fs_bsize && fs->fs_cstotal.cs_nbfree == 0)
            goto nospace;
      if (priv_check_cred(cred, PRIV_VFS_BLOCKRESERVE, 0) &&
          freespace(fs, fs->fs_minfree) - numfrags(fs, size) < 0)
            goto nospace;
      if (bpref >= fs->fs_size)
            bpref = 0;
      if (bpref == 0)
            cg = ino_to_cg(fs, ip->i_number);
      else
            cg = dtog(fs, bpref);
      bno = ffs_hashalloc(ip, cg, bpref, size, ffs_alloccg);
      if (bno > 0) {
            delta = btodb(size);
            if (ip->i_flag & IN_SPACECOUNTED) {
                  UFS_LOCK(ump);
                  fs->fs_pendingblocks += delta;
                  UFS_UNLOCK(ump);
            }
            DIP_SET(ip, i_blocks, DIP(ip, i_blocks) + delta);
            ip->i_flag |= IN_CHANGE | IN_UPDATE;
            *bnp = bno;
            return (0);
      }
nospace:
#ifdef QUOTA
      UFS_UNLOCK(ump);
      /*
       * Restore user's disk quota because allocation failed.
       */
      (void) chkdq(ip, -btodb(size), cred, FORCE);
      UFS_LOCK(ump);
#endif
      if (fs->fs_pendingblocks > 0 && reclaimed == 0) {
            reclaimed = 1;
            softdep_request_cleanup(fs, ITOV(ip));
            goto retry;
      }
      UFS_UNLOCK(ump);
      if (ppsratecheck(&lastfail, &curfail, 1)) {
            ffs_fserr(fs, ip->i_number, "filesystem full");
            uprintf("\n%s: write failed, filesystem is full\n",
                fs->fs_fsmnt);
      }
      return (ENOSPC);
}

/*
 * Reallocate a fragment to a bigger size
 *
 * The number and size of the old block is given, and a preference
 * and new size is also specified. The allocator attempts to extend
 * the original block. Failing that, the regular block allocator is
 * invoked to get an appropriate block.
 */
int
ffs_realloccg(ip, lbprev, bprev, bpref, osize, nsize, cred, bpp)
      struct inode *ip;
      ufs2_daddr_t lbprev;
      ufs2_daddr_t bprev;
      ufs2_daddr_t bpref;
      int osize, nsize;
      struct ucred *cred;
      struct buf **bpp;
{
      struct vnode *vp;
      struct fs *fs;
      struct buf *bp;
      struct ufsmount *ump;
      int cg, request, error, reclaimed;
      ufs2_daddr_t bno;
      static struct timeval lastfail;
      static int curfail;
      int64_t delta;

      *bpp = 0;
      vp = ITOV(ip);
      fs = ip->i_fs;
      bp = NULL;
      ump = ip->i_ump;
      mtx_assert(UFS_MTX(ump), MA_OWNED);
#ifdef DIAGNOSTIC
      if (vp->v_mount->mnt_kern_flag & MNTK_SUSPENDED)
            panic("ffs_realloccg: allocation on suspended filesystem");
      if ((u_int)osize > fs->fs_bsize || fragoff(fs, osize) != 0 ||
          (u_int)nsize > fs->fs_bsize || fragoff(fs, nsize) != 0) {
            printf(
            "dev = %s, bsize = %ld, osize = %d, nsize = %d, fs = %s\n",
                devtoname(ip->i_dev), (long)fs->fs_bsize, osize,
                nsize, fs->fs_fsmnt);
            panic("ffs_realloccg: bad size");
      }
      if (cred == NOCRED)
            panic("ffs_realloccg: missing credential");
#endif /* DIAGNOSTIC */
      reclaimed = 0;
retry:
      if (priv_check_cred(cred, PRIV_VFS_BLOCKRESERVE, 0) &&
          freespace(fs, fs->fs_minfree) -  numfrags(fs, nsize - osize) < 0) {
            goto nospace;
      }
      if (bprev == 0) {
            printf("dev = %s, bsize = %ld, bprev = %jd, fs = %s\n",
                devtoname(ip->i_dev), (long)fs->fs_bsize, (intmax_t)bprev,
                fs->fs_fsmnt);
            panic("ffs_realloccg: bad bprev");
      }
      UFS_UNLOCK(ump);
      /*
       * Allocate the extra space in the buffer.
       */
      error = bread(vp, lbprev, osize, NOCRED, &bp);
      if (error) {
            brelse(bp);
            return (error);
      }

      if (bp->b_blkno == bp->b_lblkno) {
            if (lbprev >= NDADDR)
                  panic("ffs_realloccg: lbprev out of range");
            bp->b_blkno = fsbtodb(fs, bprev);
      }

#ifdef QUOTA
      error = chkdq(ip, btodb(nsize - osize), cred, 0);
      if (error) {
            brelse(bp);
            return (error);
      }
#endif
      /*
       * Check for extension in the existing location.
       */
      cg = dtog(fs, bprev);
      UFS_LOCK(ump);
      bno = ffs_fragextend(ip, cg, bprev, osize, nsize);
      if (bno) {
            if (bp->b_blkno != fsbtodb(fs, bno))
                  panic("ffs_realloccg: bad blockno");
            delta = btodb(nsize - osize);
            if (ip->i_flag & IN_SPACECOUNTED) {
                  UFS_LOCK(ump);
                  fs->fs_pendingblocks += delta;
                  UFS_UNLOCK(ump);
            }
            DIP_SET(ip, i_blocks, DIP(ip, i_blocks) + delta);
            ip->i_flag |= IN_CHANGE | IN_UPDATE;
            allocbuf(bp, nsize);
            bp->b_flags |= B_DONE;
            if ((bp->b_flags & (B_MALLOC | B_VMIO)) != B_VMIO)
                  bzero((char *)bp->b_data + osize, nsize - osize);
            else
                  vfs_bio_clrbuf(bp);
            *bpp = bp;
            return (0);
      }
      /*
       * Allocate a new disk location.
       */
      if (bpref >= fs->fs_size)
            bpref = 0;
      switch ((int)fs->fs_optim) {
      case FS_OPTSPACE:
            /*
             * Allocate an exact sized fragment. Although this makes
             * best use of space, we will waste time relocating it if
             * the file continues to grow. If the fragmentation is
             * less than half of the minimum free reserve, we choose
             * to begin optimizing for time.
             */
            request = nsize;
            if (fs->fs_minfree <= 5 ||
                fs->fs_cstotal.cs_nffree >
                (off_t)fs->fs_dsize * fs->fs_minfree / (2 * 100))
                  break;
            log(LOG_NOTICE, "%s: optimization changed from SPACE to TIME\n",
                  fs->fs_fsmnt);
            fs->fs_optim = FS_OPTTIME;
            break;
      case FS_OPTTIME:
            /*
             * At this point we have discovered a file that is trying to
             * grow a small fragment to a larger fragment. To save time,
             * we allocate a full sized block, then free the unused portion.
             * If the file continues to grow, the `ffs_fragextend' call
             * above will be able to grow it in place without further
             * copying. If aberrant programs cause disk fragmentation to
             * grow within 2% of the free reserve, we choose to begin
             * optimizing for space.
             */
            request = fs->fs_bsize;
            if (fs->fs_cstotal.cs_nffree <
                (off_t)fs->fs_dsize * (fs->fs_minfree - 2) / 100)
                  break;
            log(LOG_NOTICE, "%s: optimization changed from TIME to SPACE\n",
                  fs->fs_fsmnt);
            fs->fs_optim = FS_OPTSPACE;
            break;
      default:
            printf("dev = %s, optim = %ld, fs = %s\n",
                devtoname(ip->i_dev), (long)fs->fs_optim, fs->fs_fsmnt);
            panic("ffs_realloccg: bad optim");
            /* NOTREACHED */
      }
      bno = ffs_hashalloc(ip, cg, bpref, request, ffs_alloccg);
      if (bno > 0) {
            bp->b_blkno = fsbtodb(fs, bno);
            if (!DOINGSOFTDEP(vp))
                  ffs_blkfree(ump, fs, ip->i_devvp, bprev, (long)osize,
                      ip->i_number);
            if (nsize < request)
                  ffs_blkfree(ump, fs, ip->i_devvp,
                      bno + numfrags(fs, nsize),
                      (long)(request - nsize), ip->i_number);
            delta = btodb(nsize - osize);
            if (ip->i_flag & IN_SPACECOUNTED) {
                  UFS_LOCK(ump);
                  fs->fs_pendingblocks += delta;
                  UFS_UNLOCK(ump);
            }
            DIP_SET(ip, i_blocks, DIP(ip, i_blocks) + delta);
            ip->i_flag |= IN_CHANGE | IN_UPDATE;
            allocbuf(bp, nsize);
            bp->b_flags |= B_DONE;
            if ((bp->b_flags & (B_MALLOC | B_VMIO)) != B_VMIO)
                  bzero((char *)bp->b_data + osize, nsize - osize);
            else
                  vfs_bio_clrbuf(bp);
            *bpp = bp;
            return (0);
      }
#ifdef QUOTA
      UFS_UNLOCK(ump);
      /*
       * Restore user's disk quota because allocation failed.
       */
      (void) chkdq(ip, -btodb(nsize - osize), cred, FORCE);
      UFS_LOCK(ump);
#endif
nospace:
      /*
       * no space available
       */
      if (fs->fs_pendingblocks > 0 && reclaimed == 0) {
            reclaimed = 1;
            softdep_request_cleanup(fs, vp);
            UFS_UNLOCK(ump);
            if (bp)
                  brelse(bp);
            UFS_LOCK(ump);
            goto retry;
      }
      UFS_UNLOCK(ump);
      if (bp)
            brelse(bp);
      if (ppsratecheck(&lastfail, &curfail, 1)) {
            ffs_fserr(fs, ip->i_number, "filesystem full");
            uprintf("\n%s: write failed, filesystem is full\n",
                fs->fs_fsmnt);
      }
      return (ENOSPC);
}

/*
 * Reallocate a sequence of blocks into a contiguous sequence of blocks.
 *
 * The vnode and an array of buffer pointers for a range of sequential
 * logical blocks to be made contiguous is given. The allocator attempts
 * to find a range of sequential blocks starting as close as possible
 * from the end of the allocation for the logical block immediately
 * preceding the current range. If successful, the physical block numbers
 * in the buffer pointers and in the inode are changed to reflect the new
 * allocation. If unsuccessful, the allocation is left unchanged. The
 * success in doing the reallocation is returned. Note that the error
 * return is not reflected back to the user. Rather the previous block
 * allocation will be used.
 */

SYSCTL_NODE(_vfs, OID_AUTO, ffs, CTLFLAG_RW, 0, "FFS filesystem");

static int doasyncfree = 1;
SYSCTL_INT(_vfs_ffs, OID_AUTO, doasyncfree, CTLFLAG_RW, &doasyncfree, 0, "");

static int doreallocblks = 1;
SYSCTL_INT(_vfs_ffs, OID_AUTO, doreallocblks, CTLFLAG_RW, &doreallocblks, 0, "");

#ifdef DEBUG
static volatile int prtrealloc = 0;
#endif

int
ffs_reallocblks(ap)
      struct vop_reallocblks_args /* {
            struct vnode *a_vp;
            struct cluster_save *a_buflist;
      } */ *ap;
{

      if (doreallocblks == 0)
            return (ENOSPC);
      if (VTOI(ap->a_vp)->i_ump->um_fstype == UFS1)
            return (ffs_reallocblks_ufs1(ap));
      return (ffs_reallocblks_ufs2(ap));
}
      
static int
ffs_reallocblks_ufs1(ap)
      struct vop_reallocblks_args /* {
            struct vnode *a_vp;
            struct cluster_save *a_buflist;
      } */ *ap;
{
      struct fs *fs;
      struct inode *ip;
      struct vnode *vp;
      struct buf *sbp, *ebp;
      ufs1_daddr_t *bap, *sbap, *ebap = 0;
      struct cluster_save *buflist;
      struct ufsmount *ump;
      ufs_lbn_t start_lbn, end_lbn;
      ufs1_daddr_t soff, newblk, blkno;
      ufs2_daddr_t pref;
      struct indir start_ap[NIADDR + 1], end_ap[NIADDR + 1], *idp;
      int i, len, start_lvl, end_lvl, ssize;

      vp = ap->a_vp;
      ip = VTOI(vp);
      fs = ip->i_fs;
      ump = ip->i_ump;
      if (fs->fs_contigsumsize <= 0)
            return (ENOSPC);
      buflist = ap->a_buflist;
      len = buflist->bs_nchildren;
      start_lbn = buflist->bs_children[0]->b_lblkno;
      end_lbn = start_lbn + len - 1;
#ifdef DIAGNOSTIC
      for (i = 0; i < len; i++)
            if (!ffs_checkblk(ip,
               dbtofsb(fs, buflist->bs_children[i]->b_blkno), fs->fs_bsize))
                  panic("ffs_reallocblks: unallocated block 1");
      for (i = 1; i < len; i++)
            if (buflist->bs_children[i]->b_lblkno != start_lbn + i)
                  panic("ffs_reallocblks: non-logical cluster");
      blkno = buflist->bs_children[0]->b_blkno;
      ssize = fsbtodb(fs, fs->fs_frag);
      for (i = 1; i < len - 1; i++)
            if (buflist->bs_children[i]->b_blkno != blkno + (i * ssize))
                  panic("ffs_reallocblks: non-physical cluster %d", i);
#endif
      /*
       * If the latest allocation is in a new cylinder group, assume that
       * the filesystem has decided to move and do not force it back to
       * the previous cylinder group.
       */
      if (dtog(fs, dbtofsb(fs, buflist->bs_children[0]->b_blkno)) !=
          dtog(fs, dbtofsb(fs, buflist->bs_children[len - 1]->b_blkno)))
            return (ENOSPC);
      if (ufs_getlbns(vp, start_lbn, start_ap, &start_lvl) ||
          ufs_getlbns(vp, end_lbn, end_ap, &end_lvl))
            return (ENOSPC);
      /*
       * Get the starting offset and block map for the first block.
       */
      if (start_lvl == 0) {
            sbap = &ip->i_din1->di_db[0];
            soff = start_lbn;
      } else {
            idp = &start_ap[start_lvl - 1];
            if (bread(vp, idp->in_lbn, (int)fs->fs_bsize, NOCRED, &sbp)) {
                  brelse(sbp);
                  return (ENOSPC);
            }
            sbap = (ufs1_daddr_t *)sbp->b_data;
            soff = idp->in_off;
      }
      /*
       * If the block range spans two block maps, get the second map.
       */
      if (end_lvl == 0 || (idp = &end_ap[end_lvl - 1])->in_off + 1 >= len) {
            ssize = len;
      } else {
#ifdef DIAGNOSTIC
            if (start_ap[start_lvl-1].in_lbn == idp->in_lbn)
                  panic("ffs_reallocblk: start == end");
#endif
            ssize = len - (idp->in_off + 1);
            if (bread(vp, idp->in_lbn, (int)fs->fs_bsize, NOCRED, &ebp))
                  goto fail;
            ebap = (ufs1_daddr_t *)ebp->b_data;
      }
      /*
       * Find the preferred location for the cluster.
       */
      UFS_LOCK(ump);
      pref = ffs_blkpref_ufs1(ip, start_lbn, soff, sbap);
      /*
       * Search the block map looking for an allocation of the desired size.
       */
      if ((newblk = ffs_hashalloc(ip, dtog(fs, pref), pref,
          len, ffs_clusteralloc)) == 0) {
            UFS_UNLOCK(ump);
            goto fail;
      }
      /*
       * We have found a new contiguous block.
       *
       * First we have to replace the old block pointers with the new
       * block pointers in the inode and indirect blocks associated
       * with the file.
       */
#ifdef DEBUG
      if (prtrealloc)
            printf("realloc: ino %d, lbns %jd-%jd\n\told:", ip->i_number,
                (intmax_t)start_lbn, (intmax_t)end_lbn);
#endif
      blkno = newblk;
      for (bap = &sbap[soff], i = 0; i < len; i++, blkno += fs->fs_frag) {
            if (i == ssize) {
                  bap = ebap;
                  soff = -i;
            }
#ifdef DIAGNOSTIC
            if (!ffs_checkblk(ip,
               dbtofsb(fs, buflist->bs_children[i]->b_blkno), fs->fs_bsize))
                  panic("ffs_reallocblks: unallocated block 2");
            if (dbtofsb(fs, buflist->bs_children[i]->b_blkno) != *bap)
                  panic("ffs_reallocblks: alloc mismatch");
#endif
#ifdef DEBUG
            if (prtrealloc)
                  printf(" %d,", *bap);
#endif
            if (DOINGSOFTDEP(vp)) {
                  if (sbap == &ip->i_din1->di_db[0] && i < ssize)
                        softdep_setup_allocdirect(ip, start_lbn + i,
                            blkno, *bap, fs->fs_bsize, fs->fs_bsize,
                            buflist->bs_children[i]);
                  else
                        softdep_setup_allocindir_page(ip, start_lbn + i,
                            i < ssize ? sbp : ebp, soff + i, blkno,
                            *bap, buflist->bs_children[i]);
            }
            *bap++ = blkno;
      }
      /*
       * Next we must write out the modified inode and indirect blocks.
       * For strict correctness, the writes should be synchronous since
       * the old block values may have been written to disk. In practise
       * they are almost never written, but if we are concerned about
       * strict correctness, the `doasyncfree' flag should be set to zero.
       *
       * The test on `doasyncfree' should be changed to test a flag
       * that shows whether the associated buffers and inodes have
       * been written. The flag should be set when the cluster is
       * started and cleared whenever the buffer or inode is flushed.
       * We can then check below to see if it is set, and do the
       * synchronous write only when it has been cleared.
       */
      if (sbap != &ip->i_din1->di_db[0]) {
            if (doasyncfree)
                  bdwrite(sbp);
            else
                  bwrite(sbp);
      } else {
            ip->i_flag |= IN_CHANGE | IN_UPDATE;
            if (!doasyncfree)
                  ffs_update(vp, 1);
      }
      if (ssize < len) {
            if (doasyncfree)
                  bdwrite(ebp);
            else
                  bwrite(ebp);
      }
      /*
       * Last, free the old blocks and assign the new blocks to the buffers.
       */
#ifdef DEBUG
      if (prtrealloc)
            printf("\n\tnew:");
#endif
      for (blkno = newblk, i = 0; i < len; i++, blkno += fs->fs_frag) {
            if (!DOINGSOFTDEP(vp))
                  ffs_blkfree(ump, fs, ip->i_devvp,
                      dbtofsb(fs, buflist->bs_children[i]->b_blkno),
                      fs->fs_bsize, ip->i_number);
            buflist->bs_children[i]->b_blkno = fsbtodb(fs, blkno);
#ifdef DIAGNOSTIC
            if (!ffs_checkblk(ip,
               dbtofsb(fs, buflist->bs_children[i]->b_blkno), fs->fs_bsize))
                  panic("ffs_reallocblks: unallocated block 3");
#endif
#ifdef DEBUG
            if (prtrealloc)
                  printf(" %d,", blkno);
#endif
      }
#ifdef DEBUG
      if (prtrealloc) {
            prtrealloc--;
            printf("\n");
      }
#endif
      return (0);

fail:
      if (ssize < len)
            brelse(ebp);
      if (sbap != &ip->i_din1->di_db[0])
            brelse(sbp);
      return (ENOSPC);
}

static int
ffs_reallocblks_ufs2(ap)
      struct vop_reallocblks_args /* {
            struct vnode *a_vp;
            struct cluster_save *a_buflist;
      } */ *ap;
{
      struct fs *fs;
      struct inode *ip;
      struct vnode *vp;
      struct buf *sbp, *ebp;
      ufs2_daddr_t *bap, *sbap, *ebap = 0;
      struct cluster_save *buflist;
      struct ufsmount *ump;
      ufs_lbn_t start_lbn, end_lbn;
      ufs2_daddr_t soff, newblk, blkno, pref;
      struct indir start_ap[NIADDR + 1], end_ap[NIADDR + 1], *idp;
      int i, len, start_lvl, end_lvl, ssize;

      vp = ap->a_vp;
      ip = VTOI(vp);
      fs = ip->i_fs;
      ump = ip->i_ump;
      if (fs->fs_contigsumsize <= 0)
            return (ENOSPC);
      buflist = ap->a_buflist;
      len = buflist->bs_nchildren;
      start_lbn = buflist->bs_children[0]->b_lblkno;
      end_lbn = start_lbn + len - 1;
#ifdef DIAGNOSTIC
      for (i = 0; i < len; i++)
            if (!ffs_checkblk(ip,
               dbtofsb(fs, buflist->bs_children[i]->b_blkno), fs->fs_bsize))
                  panic("ffs_reallocblks: unallocated block 1");
      for (i = 1; i < len; i++)
            if (buflist->bs_children[i]->b_lblkno != start_lbn + i)
                  panic("ffs_reallocblks: non-logical cluster");
      blkno = buflist->bs_children[0]->b_blkno;
      ssize = fsbtodb(fs, fs->fs_frag);
      for (i = 1; i < len - 1; i++)
            if (buflist->bs_children[i]->b_blkno != blkno + (i * ssize))
                  panic("ffs_reallocblks: non-physical cluster %d", i);
#endif
      /*
       * If the latest allocation is in a new cylinder group, assume that
       * the filesystem has decided to move and do not force it back to
       * the previous cylinder group.
       */
      if (dtog(fs, dbtofsb(fs, buflist->bs_children[0]->b_blkno)) !=
          dtog(fs, dbtofsb(fs, buflist->bs_children[len - 1]->b_blkno)))
            return (ENOSPC);
      if (ufs_getlbns(vp, start_lbn, start_ap, &start_lvl) ||
          ufs_getlbns(vp, end_lbn, end_ap, &end_lvl))
            return (ENOSPC);
      /*
       * Get the starting offset and block map for the first block.
       */
      if (start_lvl == 0) {
            sbap = &ip->i_din2->di_db[0];
            soff = start_lbn;
      } else {
            idp = &start_ap[start_lvl - 1];
            if (bread(vp, idp->in_lbn, (int)fs->fs_bsize, NOCRED, &sbp)) {
                  brelse(sbp);
                  return (ENOSPC);
            }
            sbap = (ufs2_daddr_t *)sbp->b_data;
            soff = idp->in_off;
      }
      /*
       * If the block range spans two block maps, get the second map.
       */
      if (end_lvl == 0 || (idp = &end_ap[end_lvl - 1])->in_off + 1 >= len) {
            ssize = len;
      } else {
#ifdef DIAGNOSTIC
            if (start_ap[start_lvl-1].in_lbn == idp->in_lbn)
                  panic("ffs_reallocblk: start == end");
#endif
            ssize = len - (idp->in_off + 1);
            if (bread(vp, idp->in_lbn, (int)fs->fs_bsize, NOCRED, &ebp))
                  goto fail;
            ebap = (ufs2_daddr_t *)ebp->b_data;
      }
      /*
       * Find the preferred location for the cluster.
       */
      UFS_LOCK(ump);
      pref = ffs_blkpref_ufs2(ip, start_lbn, soff, sbap);
      /*
       * Search the block map looking for an allocation of the desired size.
       */
      if ((newblk = ffs_hashalloc(ip, dtog(fs, pref), pref,
          len, ffs_clusteralloc)) == 0) {
            UFS_UNLOCK(ump);
            goto fail;
      }
      /*
       * We have found a new contiguous block.
       *
       * First we have to replace the old block pointers with the new
       * block pointers in the inode and indirect blocks associated
       * with the file.
       */
#ifdef DEBUG
      if (prtrealloc)
            printf("realloc: ino %d, lbns %jd-%jd\n\told:", ip->i_number,
                (intmax_t)start_lbn, (intmax_t)end_lbn);
#endif
      blkno = newblk;
      for (bap = &sbap[soff], i = 0; i < len; i++, blkno += fs->fs_frag) {
            if (i == ssize) {
                  bap = ebap;
                  soff = -i;
            }
#ifdef DIAGNOSTIC
            if (!ffs_checkblk(ip,
               dbtofsb(fs, buflist->bs_children[i]->b_blkno), fs->fs_bsize))
                  panic("ffs_reallocblks: unallocated block 2");
            if (dbtofsb(fs, buflist->bs_children[i]->b_blkno) != *bap)
                  panic("ffs_reallocblks: alloc mismatch");
#endif
#ifdef DEBUG
            if (prtrealloc)
                  printf(" %jd,", (intmax_t)*bap);
#endif
            if (DOINGSOFTDEP(vp)) {
                  if (sbap == &ip->i_din2->di_db[0] && i < ssize)
                        softdep_setup_allocdirect(ip, start_lbn + i,
                            blkno, *bap, fs->fs_bsize, fs->fs_bsize,
                            buflist->bs_children[i]);
                  else
                        softdep_setup_allocindir_page(ip, start_lbn + i,
                            i < ssize ? sbp : ebp, soff + i, blkno,
                            *bap, buflist->bs_children[i]);
            }
            *bap++ = blkno;
      }
      /*
       * Next we must write out the modified inode and indirect blocks.
       * For strict correctness, the writes should be synchronous since
       * the old block values may have been written to disk. In practise
       * they are almost never written, but if we are concerned about
       * strict correctness, the `doasyncfree' flag should be set to zero.
       *
       * The test on `doasyncfree' should be changed to test a flag
       * that shows whether the associated buffers and inodes have
       * been written. The flag should be set when the cluster is
       * started and cleared whenever the buffer or inode is flushed.
       * We can then check below to see if it is set, and do the
       * synchronous write only when it has been cleared.
       */
      if (sbap != &ip->i_din2->di_db[0]) {
            if (doasyncfree)
                  bdwrite(sbp);
            else
                  bwrite(sbp);
      } else {
            ip->i_flag |= IN_CHANGE | IN_UPDATE;
            if (!doasyncfree)
                  ffs_update(vp, 1);
      }
      if (ssize < len) {
            if (doasyncfree)
                  bdwrite(ebp);
            else
                  bwrite(ebp);
      }
      /*
       * Last, free the old blocks and assign the new blocks to the buffers.
       */
#ifdef DEBUG
      if (prtrealloc)
            printf("\n\tnew:");
#endif
      for (blkno = newblk, i = 0; i < len; i++, blkno += fs->fs_frag) {
            if (!DOINGSOFTDEP(vp))
                  ffs_blkfree(ump, fs, ip->i_devvp,
                      dbtofsb(fs, buflist->bs_children[i]->b_blkno),
                      fs->fs_bsize, ip->i_number);
            buflist->bs_children[i]->b_blkno = fsbtodb(fs, blkno);
#ifdef DIAGNOSTIC
            if (!ffs_checkblk(ip,
               dbtofsb(fs, buflist->bs_children[i]->b_blkno), fs->fs_bsize))
                  panic("ffs_reallocblks: unallocated block 3");
#endif
#ifdef DEBUG
            if (prtrealloc)
                  printf(" %jd,", (intmax_t)blkno);
#endif
      }
#ifdef DEBUG
      if (prtrealloc) {
            prtrealloc--;
            printf("\n");
      }
#endif
      return (0);

fail:
      if (ssize < len)
            brelse(ebp);
      if (sbap != &ip->i_din2->di_db[0])
            brelse(sbp);
      return (ENOSPC);
}

/*
 * Allocate an inode in the filesystem.
 *
 * If allocating a directory, use ffs_dirpref to select the inode.
 * If allocating in a directory, the following hierarchy is followed:
 *   1) allocate the preferred inode.
 *   2) allocate an inode in the same cylinder group.
 *   3) quadradically rehash into other cylinder groups, until an
 *      available inode is located.
 * If no inode preference is given the following hierarchy is used
 * to allocate an inode:
 *   1) allocate an inode in cylinder group 0.
 *   2) quadradically rehash into other cylinder groups, until an
 *      available inode is located.
 */
int
ffs_valloc(pvp, mode, cred, vpp)
      struct vnode *pvp;
      int mode;
      struct ucred *cred;
      struct vnode **vpp;
{
      struct inode *pip;
      struct fs *fs;
      struct inode *ip;
      struct timespec ts;
      struct ufsmount *ump;
      ino_t ino, ipref;
      int cg, error;
      static struct timeval lastfail;
      static int curfail;

      *vpp = NULL;
      pip = VTOI(pvp);
      fs = pip->i_fs;
      ump = pip->i_ump;

      UFS_LOCK(ump);
      if (fs->fs_cstotal.cs_nifree == 0)
            goto noinodes;

      if ((mode & IFMT) == IFDIR)
            ipref = ffs_dirpref(pip);
      else
            ipref = pip->i_number;
      if (ipref >= fs->fs_ncg * fs->fs_ipg)
            ipref = 0;
      cg = ino_to_cg(fs, ipref);
      /*
       * Track number of dirs created one after another
       * in a same cg without intervening by files.
       */
      if ((mode & IFMT) == IFDIR) {
            if (fs->fs_contigdirs[cg] < 255)
                  fs->fs_contigdirs[cg]++;
      } else {
            if (fs->fs_contigdirs[cg] > 0)
                  fs->fs_contigdirs[cg]--;
      }
      ino = (ino_t)ffs_hashalloc(pip, cg, ipref, mode,
                              (allocfcn_t *)ffs_nodealloccg);
      if (ino == 0)
            goto noinodes;
      error = ffs_vget(pvp->v_mount, ino, LK_EXCLUSIVE, vpp);
      if (error) {
            ffs_vfree(pvp, ino, mode);
            return (error);
      }
      ip = VTOI(*vpp);
      if (ip->i_mode) {
            printf("mode = 0%o, inum = %lu, fs = %s\n",
                ip->i_mode, (u_long)ip->i_number, fs->fs_fsmnt);
            panic("ffs_valloc: dup alloc");
      }
      if (DIP(ip, i_blocks) && (fs->fs_flags & FS_UNCLEAN) == 0) {  /* XXX */
            printf("free inode %s/%lu had %ld blocks\n",
                fs->fs_fsmnt, (u_long)ino, (long)DIP(ip, i_blocks));
            DIP_SET(ip, i_blocks, 0);
      }
      ip->i_flags = 0;
      DIP_SET(ip, i_flags, 0);
      /*
       * Set up a new generation number for this inode.
       */
      if (ip->i_gen == 0 || ++ip->i_gen == 0)
            ip->i_gen = arc4random() / 2 + 1;
      DIP_SET(ip, i_gen, ip->i_gen);
      if (fs->fs_magic == FS_UFS2_MAGIC) {
            vfs_timestamp(&ts);
            ip->i_din2->di_birthtime = ts.tv_sec;
            ip->i_din2->di_birthnsec = ts.tv_nsec;
      }
      ip->i_flag = 0;
      vnode_destroy_vobject(*vpp);
      (*vpp)->v_type = VNON;
      if (fs->fs_magic == FS_UFS2_MAGIC)
            (*vpp)->v_op = &ffs_vnodeops2;
      else
            (*vpp)->v_op = &ffs_vnodeops1;
      return (0);
noinodes:
      UFS_UNLOCK(ump);
      if (ppsratecheck(&lastfail, &curfail, 1)) {
            ffs_fserr(fs, pip->i_number, "out of inodes");
            uprintf("\n%s: create/symlink failed, no inodes free\n",
                fs->fs_fsmnt);
      }
      return (ENOSPC);
}

/*
 * Find a cylinder group to place a directory.
 *
 * The policy implemented by this algorithm is to allocate a
 * directory inode in the same cylinder group as its parent
 * directory, but also to reserve space for its files inodes
 * and data. Restrict the number of directories which may be
 * allocated one after another in the same cylinder group
 * without intervening allocation of files.
 *
 * If we allocate a first level directory then force allocation
 * in another cylinder group.
 */
static ino_t
ffs_dirpref(pip)
      struct inode *pip;
{
      struct fs *fs;
      int cg, prefcg, dirsize, cgsize;
      int avgifree, avgbfree, avgndir, curdirsize;
      int minifree, minbfree, maxndir;
      int mincg, minndir;
      int maxcontigdirs;

      mtx_assert(UFS_MTX(pip->i_ump), MA_OWNED);
      fs = pip->i_fs;

      avgifree = fs->fs_cstotal.cs_nifree / fs->fs_ncg;
      avgbfree = fs->fs_cstotal.cs_nbfree / fs->fs_ncg;
      avgndir = fs->fs_cstotal.cs_ndir / fs->fs_ncg;

      /*
       * Force allocation in another cg if creating a first level dir.
       */
      ASSERT_VOP_LOCKED(ITOV(pip), "ffs_dirpref");
      if (ITOV(pip)->v_vflag & VV_ROOT) {
            prefcg = arc4random() % fs->fs_ncg;
            mincg = prefcg;
            minndir = fs->fs_ipg;
            for (cg = prefcg; cg < fs->fs_ncg; cg++)
                  if (fs->fs_cs(fs, cg).cs_ndir < minndir &&
                      fs->fs_cs(fs, cg).cs_nifree >= avgifree &&
                      fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                        mincg = cg;
                        minndir = fs->fs_cs(fs, cg).cs_ndir;
                  }
            for (cg = 0; cg < prefcg; cg++)
                  if (fs->fs_cs(fs, cg).cs_ndir < minndir &&
                      fs->fs_cs(fs, cg).cs_nifree >= avgifree &&
                      fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                        mincg = cg;
                        minndir = fs->fs_cs(fs, cg).cs_ndir;
                  }
            return ((ino_t)(fs->fs_ipg * mincg));
      }

      /*
       * Count various limits which used for
       * optimal allocation of a directory inode.
       */
      maxndir = min(avgndir + fs->fs_ipg / 16, fs->fs_ipg);
      minifree = avgifree - avgifree / 4;
      if (minifree < 1)
            minifree = 1;
      minbfree = avgbfree - avgbfree / 4;
      if (minbfree < 1)
            minbfree = 1;
      cgsize = fs->fs_fsize * fs->fs_fpg;
      dirsize = fs->fs_avgfilesize * fs->fs_avgfpdir;
      curdirsize = avgndir ? (cgsize - avgbfree * fs->fs_bsize) / avgndir : 0;
      if (dirsize < curdirsize)
            dirsize = curdirsize;
      if (dirsize <= 0)
            maxcontigdirs = 0;            /* dirsize overflowed */
      else
            maxcontigdirs = min((avgbfree * fs->fs_bsize) / dirsize, 255);
      if (fs->fs_avgfpdir > 0)
            maxcontigdirs = min(maxcontigdirs,
                            fs->fs_ipg / fs->fs_avgfpdir);
      if (maxcontigdirs == 0)
            maxcontigdirs = 1;

      /*
       * Limit number of dirs in one cg and reserve space for 
       * regular files, but only if we have no deficit in
       * inodes or space.
       */
      prefcg = ino_to_cg(fs, pip->i_number);
      for (cg = prefcg; cg < fs->fs_ncg; cg++)
            if (fs->fs_cs(fs, cg).cs_ndir < maxndir &&
                fs->fs_cs(fs, cg).cs_nifree >= minifree &&
                fs->fs_cs(fs, cg).cs_nbfree >= minbfree) {
                  if (fs->fs_contigdirs[cg] < maxcontigdirs)
                        return ((ino_t)(fs->fs_ipg * cg));
            }
      for (cg = 0; cg < prefcg; cg++)
            if (fs->fs_cs(fs, cg).cs_ndir < maxndir &&
                fs->fs_cs(fs, cg).cs_nifree >= minifree &&
                fs->fs_cs(fs, cg).cs_nbfree >= minbfree) {
                  if (fs->fs_contigdirs[cg] < maxcontigdirs)
                        return ((ino_t)(fs->fs_ipg * cg));
            }
      /*
       * This is a backstop when we have deficit in space.
       */
      for (cg = prefcg; cg < fs->fs_ncg; cg++)
            if (fs->fs_cs(fs, cg).cs_nifree >= avgifree)
                  return ((ino_t)(fs->fs_ipg * cg));
      for (cg = 0; cg < prefcg; cg++)
            if (fs->fs_cs(fs, cg).cs_nifree >= avgifree)
                  break;
      return ((ino_t)(fs->fs_ipg * cg));
}

/*
 * Select the desired position for the next block in a file.  The file is
 * logically divided into sections. The first section is composed of the
 * direct blocks. Each additional section contains fs_maxbpg blocks.
 *
 * If no blocks have been allocated in the first section, the policy is to
 * request a block in the same cylinder group as the inode that describes
 * the file. If no blocks have been allocated in any other section, the
 * policy is to place the section in a cylinder group with a greater than
 * average number of free blocks.  An appropriate cylinder group is found
 * by using a rotor that sweeps the cylinder groups. When a new group of
 * blocks is needed, the sweep begins in the cylinder group following the
 * cylinder group from which the previous allocation was made. The sweep
 * continues until a cylinder group with greater than the average number
 * of free blocks is found. If the allocation is for the first block in an
 * indirect block, the information on the previous allocation is unavailable;
 * here a best guess is made based upon the logical block number being
 * allocated.
 *
 * If a section is already partially allocated, the policy is to
 * contiguously allocate fs_maxcontig blocks. The end of one of these
 * contiguous blocks and the beginning of the next is laid out
 * contiguously if possible.
 */
ufs2_daddr_t
ffs_blkpref_ufs1(ip, lbn, indx, bap)
      struct inode *ip;
      ufs_lbn_t lbn;
      int indx;
      ufs1_daddr_t *bap;
{
      struct fs *fs;
      int cg;
      int avgbfree, startcg;

      mtx_assert(UFS_MTX(ip->i_ump), MA_OWNED);
      fs = ip->i_fs;
      if (indx % fs->fs_maxbpg == 0 || bap[indx - 1] == 0) {
            if (lbn < NDADDR + NINDIR(fs)) {
                  cg = ino_to_cg(fs, ip->i_number);
                  return (cgbase(fs, cg) + fs->fs_frag);
            }
            /*
             * Find a cylinder with greater than average number of
             * unused data blocks.
             */
            if (indx == 0 || bap[indx - 1] == 0)
                  startcg =
                      ino_to_cg(fs, ip->i_number) + lbn / fs->fs_maxbpg;
            else
                  startcg = dtog(fs, bap[indx - 1]) + 1;
            startcg %= fs->fs_ncg;
            avgbfree = fs->fs_cstotal.cs_nbfree / fs->fs_ncg;
            for (cg = startcg; cg < fs->fs_ncg; cg++)
                  if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                        fs->fs_cgrotor = cg;
                        return (cgbase(fs, cg) + fs->fs_frag);
                  }
            for (cg = 0; cg <= startcg; cg++)
                  if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                        fs->fs_cgrotor = cg;
                        return (cgbase(fs, cg) + fs->fs_frag);
                  }
            return (0);
      }
      /*
       * We just always try to lay things out contiguously.
       */
      return (bap[indx - 1] + fs->fs_frag);
}

/*
 * Same as above, but for UFS2
 */
ufs2_daddr_t
ffs_blkpref_ufs2(ip, lbn, indx, bap)
      struct inode *ip;
      ufs_lbn_t lbn;
      int indx;
      ufs2_daddr_t *bap;
{
      struct fs *fs;
      int cg;
      int avgbfree, startcg;

      mtx_assert(UFS_MTX(ip->i_ump), MA_OWNED);
      fs = ip->i_fs;
      if (indx % fs->fs_maxbpg == 0 || bap[indx - 1] == 0) {
            if (lbn < NDADDR + NINDIR(fs)) {
                  cg = ino_to_cg(fs, ip->i_number);
                  return (cgbase(fs, cg) + fs->fs_frag);
            }
            /*
             * Find a cylinder with greater than average number of
             * unused data blocks.
             */
            if (indx == 0 || bap[indx - 1] == 0)
                  startcg =
                      ino_to_cg(fs, ip->i_number) + lbn / fs->fs_maxbpg;
            else
                  startcg = dtog(fs, bap[indx - 1]) + 1;
            startcg %= fs->fs_ncg;
            avgbfree = fs->fs_cstotal.cs_nbfree / fs->fs_ncg;
            for (cg = startcg; cg < fs->fs_ncg; cg++)
                  if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                        fs->fs_cgrotor = cg;
                        return (cgbase(fs, cg) + fs->fs_frag);
                  }
            for (cg = 0; cg <= startcg; cg++)
                  if (fs->fs_cs(fs, cg).cs_nbfree >= avgbfree) {
                        fs->fs_cgrotor = cg;
                        return (cgbase(fs, cg) + fs->fs_frag);
                  }
            return (0);
      }
      /*
       * We just always try to lay things out contiguously.
       */
      return (bap[indx - 1] + fs->fs_frag);
}

/*
 * Implement the cylinder overflow algorithm.
 *
 * The policy implemented by this algorithm is:
 *   1) allocate the block in its requested cylinder group.
 *   2) quadradically rehash on the cylinder group number.
 *   3) brute force search for a free block.
 *
 * Must be called with the UFS lock held.  Will release the lock on success
 * and return with it held on failure.
 */
/*VARARGS5*/
static ufs2_daddr_t
ffs_hashalloc(ip, cg, pref, size, allocator)
      struct inode *ip;
      int cg;
      ufs2_daddr_t pref;
      int size;   /* size for data blocks, mode for inodes */
      allocfcn_t *allocator;
{
      struct fs *fs;
      ufs2_daddr_t result;
      int i, icg = cg;

      mtx_assert(UFS_MTX(ip->i_ump), MA_OWNED);
#ifdef DIAGNOSTIC
      if (ITOV(ip)->v_mount->mnt_kern_flag & MNTK_SUSPENDED)
            panic("ffs_hashalloc: allocation on suspended filesystem");
#endif
      fs = ip->i_fs;
      /*
       * 1: preferred cylinder group
       */
      result = (*allocator)(ip, cg, pref, size);
      if (result)
            return (result);
      /*
       * 2: quadratic rehash
       */
      for (i = 1; i < fs->fs_ncg; i *= 2) {
            cg += i;
            if (cg >= fs->fs_ncg)
                  cg -= fs->fs_ncg;
            result = (*allocator)(ip, cg, 0, size);
            if (result)
                  return (result);
      }
      /*
       * 3: brute force search
       * Note that we start at i == 2, since 0 was checked initially,
       * and 1 is always checked in the quadratic rehash.
       */
      cg = (icg + 2) % fs->fs_ncg;
      for (i = 2; i < fs->fs_ncg; i++) {
            result = (*allocator)(ip, cg, 0, size);
            if (result)
                  return (result);
            cg++;
            if (cg == fs->fs_ncg)
                  cg = 0;
      }
      return (0);
}

/*
 * Determine whether a fragment can be extended.
 *
 * Check to see if the necessary fragments are available, and
 * if they are, allocate them.
 */
static ufs2_daddr_t
ffs_fragextend(ip, cg, bprev, osize, nsize)
      struct inode *ip;
      int cg;
      ufs2_daddr_t bprev;
      int osize, nsize;
{
      struct fs *fs;
      struct cg *cgp;
      struct buf *bp;
      struct ufsmount *ump;
      int nffree;
      long bno;
      int frags, bbase;
      int i, error;
      u_int8_t *blksfree;

      ump = ip->i_ump;
      fs = ip->i_fs;
      if (fs->fs_cs(fs, cg).cs_nffree < numfrags(fs, nsize - osize))
            return (0);
      frags = numfrags(fs, nsize);
      bbase = fragnum(fs, bprev);
      if (bbase > fragnum(fs, (bprev + frags - 1))) {
            /* cannot extend across a block boundary */
            return (0);
      }
      UFS_UNLOCK(ump);
      error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)),
            (int)fs->fs_cgsize, NOCRED, &bp);
      if (error)
            goto fail;
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp))
            goto fail;
      bp->b_xflags |= BX_BKGRDWRITE;
      cgp->cg_old_time = cgp->cg_time = time_second;
      bno = dtogd(fs, bprev);
      blksfree = cg_blksfree(cgp);
      for (i = numfrags(fs, osize); i < frags; i++)
            if (isclr(blksfree, bno + i))
                  goto fail;
      /*
       * the current fragment can be extended
       * deduct the count on fragment being extended into
       * increase the count on the remaining fragment (if any)
       * allocate the extended piece
       */
      for (i = frags; i < fs->fs_frag - bbase; i++)
            if (isclr(blksfree, bno + i))
                  break;
      cgp->cg_frsum[i - numfrags(fs, osize)]--;
      if (i != frags)
            cgp->cg_frsum[i - frags]++;
      for (i = numfrags(fs, osize), nffree = 0; i < frags; i++) {
            clrbit(blksfree, bno + i);
            cgp->cg_cs.cs_nffree--;
            nffree++;
      }
      UFS_LOCK(ump);
      fs->fs_cstotal.cs_nffree -= nffree;
      fs->fs_cs(fs, cg).cs_nffree -= nffree;
      fs->fs_fmod = 1;
      ACTIVECLEAR(fs, cg);
      UFS_UNLOCK(ump);
      if (DOINGSOFTDEP(ITOV(ip)))
            softdep_setup_blkmapdep(bp, UFSTOVFS(ump), bprev);
      bdwrite(bp);
      return (bprev);

fail:
      brelse(bp);
      UFS_LOCK(ump);
      return (0);

}

/*
 * Determine whether a block can be allocated.
 *
 * Check to see if a block of the appropriate size is available,
 * and if it is, allocate it.
 */
static ufs2_daddr_t
ffs_alloccg(ip, cg, bpref, size)
      struct inode *ip;
      int cg;
      ufs2_daddr_t bpref;
      int size;
{
      struct fs *fs;
      struct cg *cgp;
      struct buf *bp;
      struct ufsmount *ump;
      ufs1_daddr_t bno;
      ufs2_daddr_t blkno;
      int i, allocsiz, error, frags;
      u_int8_t *blksfree;

      ump = ip->i_ump;
      fs = ip->i_fs;
      if (fs->fs_cs(fs, cg).cs_nbfree == 0 && size == fs->fs_bsize)
            return (0);
      UFS_UNLOCK(ump);
      error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)),
            (int)fs->fs_cgsize, NOCRED, &bp);
      if (error)
            goto fail;
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp) ||
          (cgp->cg_cs.cs_nbfree == 0 && size == fs->fs_bsize))
            goto fail;
      bp->b_xflags |= BX_BKGRDWRITE;
      cgp->cg_old_time = cgp->cg_time = time_second;
      if (size == fs->fs_bsize) {
            UFS_LOCK(ump);
            blkno = ffs_alloccgblk(ip, bp, bpref);
            ACTIVECLEAR(fs, cg);
            UFS_UNLOCK(ump);
            bdwrite(bp);
            return (blkno);
      }
      /*
       * check to see if any fragments are already available
       * allocsiz is the size which will be allocated, hacking
       * it down to a smaller size if necessary
       */
      blksfree = cg_blksfree(cgp);
      frags = numfrags(fs, size);
      for (allocsiz = frags; allocsiz < fs->fs_frag; allocsiz++)
            if (cgp->cg_frsum[allocsiz] != 0)
                  break;
      if (allocsiz == fs->fs_frag) {
            /*
             * no fragments were available, so a block will be
             * allocated, and hacked up
             */
            if (cgp->cg_cs.cs_nbfree == 0)
                  goto fail;
            UFS_LOCK(ump);
            blkno = ffs_alloccgblk(ip, bp, bpref);
            bno = dtogd(fs, blkno);
            for (i = frags; i < fs->fs_frag; i++)
                  setbit(blksfree, bno + i);
            i = fs->fs_frag - frags;
            cgp->cg_cs.cs_nffree += i;
            fs->fs_cstotal.cs_nffree += i;
            fs->fs_cs(fs, cg).cs_nffree += i;
            fs->fs_fmod = 1;
            cgp->cg_frsum[i]++;
            ACTIVECLEAR(fs, cg);
            UFS_UNLOCK(ump);
            bdwrite(bp);
            return (blkno);
      }
      bno = ffs_mapsearch(fs, cgp, bpref, allocsiz);
      if (bno < 0)
            goto fail;
      for (i = 0; i < frags; i++)
            clrbit(blksfree, bno + i);
      cgp->cg_cs.cs_nffree -= frags;
      cgp->cg_frsum[allocsiz]--;
      if (frags != allocsiz)
            cgp->cg_frsum[allocsiz - frags]++;
      UFS_LOCK(ump);
      fs->fs_cstotal.cs_nffree -= frags;
      fs->fs_cs(fs, cg).cs_nffree -= frags;
      fs->fs_fmod = 1;
      blkno = cgbase(fs, cg) + bno;
      ACTIVECLEAR(fs, cg);
      UFS_UNLOCK(ump);
      if (DOINGSOFTDEP(ITOV(ip)))
            softdep_setup_blkmapdep(bp, UFSTOVFS(ump), blkno);
      bdwrite(bp);
      return (blkno);

fail:
      brelse(bp);
      UFS_LOCK(ump);
      return (0);
}

/*
 * Allocate a block in a cylinder group.
 *
 * This algorithm implements the following policy:
 *   1) allocate the requested block.
 *   2) allocate a rotationally optimal block in the same cylinder.
 *   3) allocate the next available block on the block rotor for the
 *      specified cylinder group.
 * Note that this routine only allocates fs_bsize blocks; these
 * blocks may be fragmented by the routine that allocates them.
 */
static ufs2_daddr_t
ffs_alloccgblk(ip, bp, bpref)
      struct inode *ip;
      struct buf *bp;
      ufs2_daddr_t bpref;
{
      struct fs *fs;
      struct cg *cgp;
      struct ufsmount *ump;
      ufs1_daddr_t bno;
      ufs2_daddr_t blkno;
      u_int8_t *blksfree;

      fs = ip->i_fs;
      ump = ip->i_ump;
      mtx_assert(UFS_MTX(ump), MA_OWNED);
      cgp = (struct cg *)bp->b_data;
      blksfree = cg_blksfree(cgp);
      if (bpref == 0 || dtog(fs, bpref) != cgp->cg_cgx) {
            bpref = cgp->cg_rotor;
      } else {
            bpref = blknum(fs, bpref);
            bno = dtogd(fs, bpref);
            /*
             * if the requested block is available, use it
             */
            if (ffs_isblock(fs, blksfree, fragstoblks(fs, bno)))
                  goto gotit;
      }
      /*
       * Take the next available block in this cylinder group.
       */
      bno = ffs_mapsearch(fs, cgp, bpref, (int)fs->fs_frag);
      if (bno < 0)
            return (0);
      cgp->cg_rotor = bno;
gotit:
      blkno = fragstoblks(fs, bno);
      ffs_clrblock(fs, blksfree, (long)blkno);
      ffs_clusteracct(ump, fs, cgp, blkno, -1);
      cgp->cg_cs.cs_nbfree--;
      fs->fs_cstotal.cs_nbfree--;
      fs->fs_cs(fs, cgp->cg_cgx).cs_nbfree--;
      fs->fs_fmod = 1;
      blkno = cgbase(fs, cgp->cg_cgx) + bno;
      /* XXX Fixme. */
      UFS_UNLOCK(ump);
      if (DOINGSOFTDEP(ITOV(ip)))
            softdep_setup_blkmapdep(bp, UFSTOVFS(ump), blkno);
      UFS_LOCK(ump);
      return (blkno);
}

/*
 * Determine whether a cluster can be allocated.
 *
 * We do not currently check for optimal rotational layout if there
 * are multiple choices in the same cylinder group. Instead we just
 * take the first one that we find following bpref.
 */
static ufs2_daddr_t
ffs_clusteralloc(ip, cg, bpref, len)
      struct inode *ip;
      int cg;
      ufs2_daddr_t bpref;
      int len;
{
      struct fs *fs;
      struct cg *cgp;
      struct buf *bp;
      struct ufsmount *ump;
      int i, run, bit, map, got;
      ufs2_daddr_t bno;
      u_char *mapp;
      int32_t *lp;
      u_int8_t *blksfree;

      fs = ip->i_fs;
      ump = ip->i_ump;
      if (fs->fs_maxcluster[cg] < len)
            return (0);
      UFS_UNLOCK(ump);
      if (bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)), (int)fs->fs_cgsize,
          NOCRED, &bp))
            goto fail_lock;
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp))
            goto fail_lock;
      bp->b_xflags |= BX_BKGRDWRITE;
      /*
       * Check to see if a cluster of the needed size (or bigger) is
       * available in this cylinder group.
       */
      lp = &cg_clustersum(cgp)[len];
      for (i = len; i <= fs->fs_contigsumsize; i++)
            if (*lp++ > 0)
                  break;
      if (i > fs->fs_contigsumsize) {
            /*
             * This is the first time looking for a cluster in this
             * cylinder group. Update the cluster summary information
             * to reflect the true maximum sized cluster so that
             * future cluster allocation requests can avoid reading
             * the cylinder group map only to find no clusters.
             */
            lp = &cg_clustersum(cgp)[len - 1];
            for (i = len - 1; i > 0; i--)
                  if (*lp-- > 0)
                        break;
            UFS_LOCK(ump);
            fs->fs_maxcluster[cg] = i;
            goto fail;
      }
      /*
       * Search the cluster map to find a big enough cluster.
       * We take the first one that we find, even if it is larger
       * than we need as we prefer to get one close to the previous
       * block allocation. We do not search before the current
       * preference point as we do not want to allocate a block
       * that is allocated before the previous one (as we will
       * then have to wait for another pass of the elevator
       * algorithm before it will be read). We prefer to fail and
       * be recalled to try an allocation in the next cylinder group.
       */
      if (dtog(fs, bpref) != cg)
            bpref = 0;
      else
            bpref = fragstoblks(fs, dtogd(fs, blknum(fs, bpref)));
      mapp = &cg_clustersfree(cgp)[bpref / NBBY];
      map = *mapp++;
      bit = 1 << (bpref % NBBY);
      for (run = 0, got = bpref; got < cgp->cg_nclusterblks; got++) {
            if ((map & bit) == 0) {
                  run = 0;
            } else {
                  run++;
                  if (run == len)
                        break;
            }
            if ((got & (NBBY - 1)) != (NBBY - 1)) {
                  bit <<= 1;
            } else {
                  map = *mapp++;
                  bit = 1;
            }
      }
      if (got >= cgp->cg_nclusterblks)
            goto fail_lock;
      /*
       * Allocate the cluster that we have found.
       */
      blksfree = cg_blksfree(cgp);
      for (i = 1; i <= len; i++)
            if (!ffs_isblock(fs, blksfree, got - run + i))
                  panic("ffs_clusteralloc: map mismatch");
      bno = cgbase(fs, cg) + blkstofrags(fs, got - run + 1);
      if (dtog(fs, bno) != cg)
            panic("ffs_clusteralloc: allocated out of group");
      len = blkstofrags(fs, len);
      UFS_LOCK(ump);
      for (i = 0; i < len; i += fs->fs_frag)
            if (ffs_alloccgblk(ip, bp, bno + i) != bno + i)
                  panic("ffs_clusteralloc: lost block");
      ACTIVECLEAR(fs, cg);
      UFS_UNLOCK(ump);
      bdwrite(bp);
      return (bno);

fail_lock:
      UFS_LOCK(ump);
fail:
      brelse(bp);
      return (0);
}

/*
 * Determine whether an inode can be allocated.
 *
 * Check to see if an inode is available, and if it is,
 * allocate it using the following policy:
 *   1) allocate the requested inode.
 *   2) allocate the next available inode after the requested
 *      inode in the specified cylinder group.
 */
static ufs2_daddr_t
ffs_nodealloccg(ip, cg, ipref, mode)
      struct inode *ip;
      int cg;
      ufs2_daddr_t ipref;
      int mode;
{
      struct fs *fs;
      struct cg *cgp;
      struct buf *bp, *ibp;
      struct ufsmount *ump;
      u_int8_t *inosused;
      struct ufs2_dinode *dp2;
      int error, start, len, loc, map, i;

      fs = ip->i_fs;
      ump = ip->i_ump;
      if (fs->fs_cs(fs, cg).cs_nifree == 0)
            return (0);
      UFS_UNLOCK(ump);
      error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, cg)),
            (int)fs->fs_cgsize, NOCRED, &bp);
      if (error) {
            brelse(bp);
            UFS_LOCK(ump);
            return (0);
      }
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp) || cgp->cg_cs.cs_nifree == 0) {
            brelse(bp);
            UFS_LOCK(ump);
            return (0);
      }
      bp->b_xflags |= BX_BKGRDWRITE;
      cgp->cg_old_time = cgp->cg_time = time_second;
      inosused = cg_inosused(cgp);
      if (ipref) {
            ipref %= fs->fs_ipg;
            if (isclr(inosused, ipref))
                  goto gotit;
      }
      start = cgp->cg_irotor / NBBY;
      len = howmany(fs->fs_ipg - cgp->cg_irotor, NBBY);
      loc = skpc(0xff, len, &inosused[start]);
      if (loc == 0) {
            len = start + 1;
            start = 0;
            loc = skpc(0xff, len, &inosused[0]);
            if (loc == 0) {
                  printf("cg = %d, irotor = %ld, fs = %s\n",
                      cg, (long)cgp->cg_irotor, fs->fs_fsmnt);
                  panic("ffs_nodealloccg: map corrupted");
                  /* NOTREACHED */
            }
      }
      i = start + len - loc;
      map = inosused[i];
      ipref = i * NBBY;
      for (i = 1; i < (1 << NBBY); i <<= 1, ipref++) {
            if ((map & i) == 0) {
                  cgp->cg_irotor = ipref;
                  goto gotit;
            }
      }
      printf("fs = %s\n", fs->fs_fsmnt);
      panic("ffs_nodealloccg: block not in map");
      /* NOTREACHED */
gotit:
      /*
       * Check to see if we need to initialize more inodes.
       */
      ibp = NULL;
      if (fs->fs_magic == FS_UFS2_MAGIC &&
          ipref + INOPB(fs) > cgp->cg_initediblk &&
          cgp->cg_initediblk < cgp->cg_niblk) {
            ibp = getblk(ip->i_devvp, fsbtodb(fs,
                ino_to_fsba(fs, cg * fs->fs_ipg + cgp->cg_initediblk)),
                (int)fs->fs_bsize, 0, 0, 0);
            bzero(ibp->b_data, (int)fs->fs_bsize);
            dp2 = (struct ufs2_dinode *)(ibp->b_data);
            for (i = 0; i < INOPB(fs); i++) {
                  dp2->di_gen = arc4random() / 2 + 1;
                  dp2++;
            }
            cgp->cg_initediblk += INOPB(fs);
      }
      UFS_LOCK(ump);
      ACTIVECLEAR(fs, cg);
      setbit(inosused, ipref);
      cgp->cg_cs.cs_nifree--;
      fs->fs_cstotal.cs_nifree--;
      fs->fs_cs(fs, cg).cs_nifree--;
      fs->fs_fmod = 1;
      if ((mode & IFMT) == IFDIR) {
            cgp->cg_cs.cs_ndir++;
            fs->fs_cstotal.cs_ndir++;
            fs->fs_cs(fs, cg).cs_ndir++;
      }
      UFS_UNLOCK(ump);
      if (DOINGSOFTDEP(ITOV(ip)))
            softdep_setup_inomapdep(bp, ip, cg * fs->fs_ipg + ipref);
      bdwrite(bp);
      if (ibp != NULL)
            bawrite(ibp);
      return (cg * fs->fs_ipg + ipref);
}

/*
 * check if a block is free
 */
static int
ffs_isfreeblock(struct fs *fs, u_char *cp, ufs1_daddr_t h)
{

      switch ((int)fs->fs_frag) {
      case 8:
            return (cp[h] == 0);
      case 4:
            return ((cp[h >> 1] & (0x0f << ((h & 0x1) << 2))) == 0);
      case 2:
            return ((cp[h >> 2] & (0x03 << ((h & 0x3) << 1))) == 0);
      case 1:
            return ((cp[h >> 3] & (0x01 << (h & 0x7))) == 0);
      default:
            panic("ffs_isfreeblock");
      }
      return (0);
}

/*
 * Free a block or fragment.
 *
 * The specified block or fragment is placed back in the
 * free map. If a fragment is deallocated, a possible
 * block reassembly is checked.
 */
void
ffs_blkfree(ump, fs, devvp, bno, size, inum)
      struct ufsmount *ump;
      struct fs *fs;
      struct vnode *devvp;
      ufs2_daddr_t bno;
      long size;
      ino_t inum;
{
      struct cg *cgp;
      struct buf *bp;
      ufs1_daddr_t fragno, cgbno;
      ufs2_daddr_t cgblkno;
      int i, cg, blk, frags, bbase;
      u_int8_t *blksfree;
      struct cdev *dev;

      cg = dtog(fs, bno);
      if (devvp->v_type != VCHR) {
            /* devvp is a snapshot */
            dev = VTOI(devvp)->i_devvp->v_rdev;
            cgblkno = fragstoblks(fs, cgtod(fs, cg));
      } else {
            /* devvp is a normal disk device */
            dev = devvp->v_rdev;
            cgblkno = fsbtodb(fs, cgtod(fs, cg));
            ASSERT_VOP_LOCKED(devvp, "ffs_blkfree");
            if ((devvp->v_vflag & VV_COPYONWRITE) &&
                ffs_snapblkfree(fs, devvp, bno, size, inum))
                  return;
      }
#ifdef DIAGNOSTIC
      if ((u_int)size > fs->fs_bsize || fragoff(fs, size) != 0 ||
          fragnum(fs, bno) + numfrags(fs, size) > fs->fs_frag) {
            printf("dev=%s, bno = %jd, bsize = %ld, size = %ld, fs = %s\n",
                devtoname(dev), (intmax_t)bno, (long)fs->fs_bsize,
                size, fs->fs_fsmnt);
            panic("ffs_blkfree: bad size");
      }
#endif
      if ((u_int)bno >= fs->fs_size) {
            printf("bad block %jd, ino %lu\n", (intmax_t)bno,
                (u_long)inum);
            ffs_fserr(fs, inum, "bad block");
            return;
      }
      if (bread(devvp, cgblkno, (int)fs->fs_cgsize, NOCRED, &bp)) {
            brelse(bp);
            return;
      }
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp)) {
            brelse(bp);
            return;
      }
      bp->b_xflags |= BX_BKGRDWRITE;
      cgp->cg_old_time = cgp->cg_time = time_second;
      cgbno = dtogd(fs, bno);
      blksfree = cg_blksfree(cgp);
      UFS_LOCK(ump);
      if (size == fs->fs_bsize) {
            fragno = fragstoblks(fs, cgbno);
            if (!ffs_isfreeblock(fs, blksfree, fragno)) {
                  if (devvp->v_type != VCHR) {
                        UFS_UNLOCK(ump);
                        /* devvp is a snapshot */
                        brelse(bp);
                        return;
                  }
                  printf("dev = %s, block = %jd, fs = %s\n",
                      devtoname(dev), (intmax_t)bno, fs->fs_fsmnt);
                  panic("ffs_blkfree: freeing free block");
            }
            ffs_setblock(fs, blksfree, fragno);
            ffs_clusteracct(ump, fs, cgp, fragno, 1);
            cgp->cg_cs.cs_nbfree++;
            fs->fs_cstotal.cs_nbfree++;
            fs->fs_cs(fs, cg).cs_nbfree++;
      } else {
            bbase = cgbno - fragnum(fs, cgbno);
            /*
             * decrement the counts associated with the old frags
             */
            blk = blkmap(fs, blksfree, bbase);
            ffs_fragacct(fs, blk, cgp->cg_frsum, -1);
            /*
             * deallocate the fragment
             */
            frags = numfrags(fs, size);
            for (i = 0; i < frags; i++) {
                  if (isset(blksfree, cgbno + i)) {
                        printf("dev = %s, block = %jd, fs = %s\n",
                            devtoname(dev), (intmax_t)(bno + i),
                            fs->fs_fsmnt);
                        panic("ffs_blkfree: freeing free frag");
                  }
                  setbit(blksfree, cgbno + i);
            }
            cgp->cg_cs.cs_nffree += i;
            fs->fs_cstotal.cs_nffree += i;
            fs->fs_cs(fs, cg).cs_nffree += i;
            /*
             * add back in counts associated with the new frags
             */
            blk = blkmap(fs, blksfree, bbase);
            ffs_fragacct(fs, blk, cgp->cg_frsum, 1);
            /*
             * if a complete block has been reassembled, account for it
             */
            fragno = fragstoblks(fs, bbase);
            if (ffs_isblock(fs, blksfree, fragno)) {
                  cgp->cg_cs.cs_nffree -= fs->fs_frag;
                  fs->fs_cstotal.cs_nffree -= fs->fs_frag;
                  fs->fs_cs(fs, cg).cs_nffree -= fs->fs_frag;
                  ffs_clusteracct(ump, fs, cgp, fragno, 1);
                  cgp->cg_cs.cs_nbfree++;
                  fs->fs_cstotal.cs_nbfree++;
                  fs->fs_cs(fs, cg).cs_nbfree++;
            }
      }
      fs->fs_fmod = 1;
      ACTIVECLEAR(fs, cg);
      UFS_UNLOCK(ump);
      bdwrite(bp);
}

#ifdef DIAGNOSTIC
/*
 * Verify allocation of a block or fragment. Returns true if block or
 * fragment is allocated, false if it is free.
 */
static int
ffs_checkblk(ip, bno, size)
      struct inode *ip;
      ufs2_daddr_t bno;
      long size;
{
      struct fs *fs;
      struct cg *cgp;
      struct buf *bp;
      ufs1_daddr_t cgbno;
      int i, error, frags, free;
      u_int8_t *blksfree;

      fs = ip->i_fs;
      if ((u_int)size > fs->fs_bsize || fragoff(fs, size) != 0) {
            printf("bsize = %ld, size = %ld, fs = %s\n",
                (long)fs->fs_bsize, size, fs->fs_fsmnt);
            panic("ffs_checkblk: bad size");
      }
      if ((u_int)bno >= fs->fs_size)
            panic("ffs_checkblk: bad block %jd", (intmax_t)bno);
      error = bread(ip->i_devvp, fsbtodb(fs, cgtod(fs, dtog(fs, bno))),
            (int)fs->fs_cgsize, NOCRED, &bp);
      if (error)
            panic("ffs_checkblk: cg bread failed");
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp))
            panic("ffs_checkblk: cg magic mismatch");
      bp->b_xflags |= BX_BKGRDWRITE;
      blksfree = cg_blksfree(cgp);
      cgbno = dtogd(fs, bno);
      if (size == fs->fs_bsize) {
            free = ffs_isblock(fs, blksfree, fragstoblks(fs, cgbno));
      } else {
            frags = numfrags(fs, size);
            for (free = 0, i = 0; i < frags; i++)
                  if (isset(blksfree, cgbno + i))
                        free++;
            if (free != 0 && free != frags)
                  panic("ffs_checkblk: partially free fragment");
      }
      brelse(bp);
      return (!free);
}
#endif /* DIAGNOSTIC */

/*
 * Free an inode.
 */
int
ffs_vfree(pvp, ino, mode)
      struct vnode *pvp;
      ino_t ino;
      int mode;
{
      struct inode *ip;

      if (DOINGSOFTDEP(pvp)) {
            softdep_freefile(pvp, ino, mode);
            return (0);
      }
      ip = VTOI(pvp);
      return (ffs_freefile(ip->i_ump, ip->i_fs, ip->i_devvp, ino, mode));
}

/*
 * Do the actual free operation.
 * The specified inode is placed back in the free map.
 */
int
ffs_freefile(ump, fs, devvp, ino, mode)
      struct ufsmount *ump;
      struct fs *fs;
      struct vnode *devvp;
      ino_t ino;
      int mode;
{
      struct cg *cgp;
      struct buf *bp;
      ufs2_daddr_t cgbno;
      int error, cg;
      u_int8_t *inosused;
      struct cdev *dev;

      cg = ino_to_cg(fs, ino);
      if (devvp->v_type != VCHR) {
            /* devvp is a snapshot */
            dev = VTOI(devvp)->i_devvp->v_rdev;
            cgbno = fragstoblks(fs, cgtod(fs, cg));
      } else {
            /* devvp is a normal disk device */
            dev = devvp->v_rdev;
            cgbno = fsbtodb(fs, cgtod(fs, cg));
      }
      if ((u_int)ino >= fs->fs_ipg * fs->fs_ncg)
            panic("ffs_freefile: range: dev = %s, ino = %lu, fs = %s",
                devtoname(dev), (u_long)ino, fs->fs_fsmnt);
      if ((error = bread(devvp, cgbno, (int)fs->fs_cgsize, NOCRED, &bp))) {
            brelse(bp);
            return (error);
      }
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp)) {
            brelse(bp);
            return (0);
      }
      bp->b_xflags |= BX_BKGRDWRITE;
      cgp->cg_old_time = cgp->cg_time = time_second;
      inosused = cg_inosused(cgp);
      ino %= fs->fs_ipg;
      if (isclr(inosused, ino)) {
            printf("dev = %s, ino = %lu, fs = %s\n", devtoname(dev),
                (u_long)ino + cg * fs->fs_ipg, fs->fs_fsmnt);
            if (fs->fs_ronly == 0)
                  panic("ffs_freefile: freeing free inode");
      }
      clrbit(inosused, ino);
      if (ino < cgp->cg_irotor)
            cgp->cg_irotor = ino;
      cgp->cg_cs.cs_nifree++;
      UFS_LOCK(ump);
      fs->fs_cstotal.cs_nifree++;
      fs->fs_cs(fs, cg).cs_nifree++;
      if ((mode & IFMT) == IFDIR) {
            cgp->cg_cs.cs_ndir--;
            fs->fs_cstotal.cs_ndir--;
            fs->fs_cs(fs, cg).cs_ndir--;
      }
      fs->fs_fmod = 1;
      ACTIVECLEAR(fs, cg);
      UFS_UNLOCK(ump);
      bdwrite(bp);
      return (0);
}

/*
 * Check to see if a file is free.
 */
int
ffs_checkfreefile(fs, devvp, ino)
      struct fs *fs;
      struct vnode *devvp;
      ino_t ino;
{
      struct cg *cgp;
      struct buf *bp;
      ufs2_daddr_t cgbno;
      int ret, cg;
      u_int8_t *inosused;

      cg = ino_to_cg(fs, ino);
      if (devvp->v_type != VCHR) {
            /* devvp is a snapshot */
            cgbno = fragstoblks(fs, cgtod(fs, cg));
      } else {
            /* devvp is a normal disk device */
            cgbno = fsbtodb(fs, cgtod(fs, cg));
      }
      if ((u_int)ino >= fs->fs_ipg * fs->fs_ncg)
            return (1);
      if (bread(devvp, cgbno, (int)fs->fs_cgsize, NOCRED, &bp)) {
            brelse(bp);
            return (1);
      }
      cgp = (struct cg *)bp->b_data;
      if (!cg_chkmagic(cgp)) {
            brelse(bp);
            return (1);
      }
      inosused = cg_inosused(cgp);
      ino %= fs->fs_ipg;
      ret = isclr(inosused, ino);
      brelse(bp);
      return (ret);
}

/*
 * Find a block of the specified size in the specified cylinder group.
 *
 * It is a panic if a request is made to find a block if none are
 * available.
 */
static ufs1_daddr_t
ffs_mapsearch(fs, cgp, bpref, allocsiz)
      struct fs *fs;
      struct cg *cgp;
      ufs2_daddr_t bpref;
      int allocsiz;
{
      ufs1_daddr_t bno;
      int start, len, loc, i;
      int blk, field, subfield, pos;
      u_int8_t *blksfree;

      /*
       * find the fragment by searching through the free block
       * map for an appropriate bit pattern
       */
      if (bpref)
            start = dtogd(fs, bpref) / NBBY;
      else
            start = cgp->cg_frotor / NBBY;
      blksfree = cg_blksfree(cgp);
      len = howmany(fs->fs_fpg, NBBY) - start;
      loc = scanc((u_int)len, (u_char *)&blksfree[start],
            fragtbl[fs->fs_frag],
            (u_char)(1 << (allocsiz - 1 + (fs->fs_frag % NBBY))));
      if (loc == 0) {
            len = start + 1;
            start = 0;
            loc = scanc((u_int)len, (u_char *)&blksfree[0],
                  fragtbl[fs->fs_frag],
                  (u_char)(1 << (allocsiz - 1 + (fs->fs_frag % NBBY))));
            if (loc == 0) {
                  printf("start = %d, len = %d, fs = %s\n",
                      start, len, fs->fs_fsmnt);
                  panic("ffs_alloccg: map corrupted");
                  /* NOTREACHED */
            }
      }
      bno = (start + len - loc) * NBBY;
      cgp->cg_frotor = bno;
      /*
       * found the byte in the map
       * sift through the bits to find the selected frag
       */
      for (i = bno + NBBY; bno < i; bno += fs->fs_frag) {
            blk = blkmap(fs, blksfree, bno);
            blk <<= 1;
            field = around[allocsiz];
            subfield = inside[allocsiz];
            for (pos = 0; pos <= fs->fs_frag - allocsiz; pos++) {
                  if ((blk & field) == subfield)
                        return (bno + pos);
                  field <<= 1;
                  subfield <<= 1;
            }
      }
      printf("bno = %lu, fs = %s\n", (u_long)bno, fs->fs_fsmnt);
      panic("ffs_alloccg: block not in map");
      return (-1);
}

/*
 * Update the cluster map because of an allocation or free.
 *
 * Cnt == 1 means free; cnt == -1 means allocating.
 */
void
ffs_clusteracct(ump, fs, cgp, blkno, cnt)
      struct ufsmount *ump;
      struct fs *fs;
      struct cg *cgp;
      ufs1_daddr_t blkno;
      int cnt;
{
      int32_t *sump;
      int32_t *lp;
      u_char *freemapp, *mapp;
      int i, start, end, forw, back, map, bit;

      mtx_assert(UFS_MTX(ump), MA_OWNED);

      if (fs->fs_contigsumsize <= 0)
            return;
      freemapp = cg_clustersfree(cgp);
      sump = cg_clustersum(cgp);
      /*
       * Allocate or clear the actual block.
       */
      if (cnt > 0)
            setbit(freemapp, blkno);
      else
            clrbit(freemapp, blkno);
      /*
       * Find the size of the cluster going forward.
       */
      start = blkno + 1;
      end = start + fs->fs_contigsumsize;
      if (end >= cgp->cg_nclusterblks)
            end = cgp->cg_nclusterblks;
      mapp = &freemapp[start / NBBY];
      map = *mapp++;
      bit = 1 << (start % NBBY);
      for (i = start; i < end; i++) {
            if ((map & bit) == 0)
                  break;
            if ((i & (NBBY - 1)) != (NBBY - 1)) {
                  bit <<= 1;
            } else {
                  map = *mapp++;
                  bit = 1;
            }
      }
      forw = i - start;
      /*
       * Find the size of the cluster going backward.
       */
      start = blkno - 1;
      end = start - fs->fs_contigsumsize;
      if (end < 0)
            end = -1;
      mapp = &freemapp[start / NBBY];
      map = *mapp--;
      bit = 1 << (start % NBBY);
      for (i = start; i > end; i--) {
            if ((map & bit) == 0)
                  break;
            if ((i & (NBBY - 1)) != 0) {
                  bit >>= 1;
            } else {
                  map = *mapp--;
                  bit = 1 << (NBBY - 1);
            }
      }
      back = start - i;
      /*
       * Account for old cluster and the possibly new forward and
       * back clusters.
       */
      i = back + forw + 1;
      if (i > fs->fs_contigsumsize)
            i = fs->fs_contigsumsize;
      sump[i] += cnt;
      if (back > 0)
            sump[back] -= cnt;
      if (forw > 0)
            sump[forw] -= cnt;
      /*
       * Update cluster summary information.
       */
      lp = &sump[fs->fs_contigsumsize];
      for (i = fs->fs_contigsumsize; i > 0; i--)
            if (*lp-- > 0)
                  break;
      fs->fs_maxcluster[cgp->cg_cgx] = i;
}

/*
 * Fserr prints the name of a filesystem with an error diagnostic.
 *
 * The form of the error message is:
 *    fs: error message
 */
static void
ffs_fserr(fs, inum, cp)
      struct fs *fs;
      ino_t inum;
      char *cp;
{
      struct thread *td = curthread;      /* XXX */
      struct proc *p = td->td_proc;

      log(LOG_ERR, "pid %d (%s), uid %d inumber %d on %s: %s\n",
          p->p_pid, p->p_comm, td->td_ucred->cr_uid, inum, fs->fs_fsmnt, cp);
}

/*
 * This function provides the capability for the fsck program to
 * update an active filesystem. Eleven operations are provided:
 *
 * adjrefcnt(inode, amt) - adjusts the reference count on the
 *    specified inode by the specified amount. Under normal
 *    operation the count should always go down. Decrementing
 *    the count to zero will cause the inode to be freed.
 * adjblkcnt(inode, amt) - adjust the number of blocks used to
 *    by the specifed amount.
 * adjndir, adjbfree, adjifree, adjffree, adjnumclusters(amt) -
 *    adjust the superblock summary.
 * freedirs(inode, count) - directory inodes [inode..inode + count - 1]
 *    are marked as free. Inodes should never have to be marked
 *    as in use.
 * freefiles(inode, count) - file inodes [inode..inode + count - 1]
 *    are marked as free. Inodes should never have to be marked
 *    as in use.
 * freeblks(blockno, size) - blocks [blockno..blockno + size - 1]
 *    are marked as free. Blocks should never have to be marked
 *    as in use.
 * setflags(flags, set/clear) - the fs_flags field has the specified
 *    flags set (second parameter +1) or cleared (second parameter -1).
 */

static int sysctl_ffs_fsck(SYSCTL_HANDLER_ARGS);

SYSCTL_PROC(_vfs_ffs, FFS_ADJ_REFCNT, adjrefcnt, CTLFLAG_WR|CTLTYPE_STRUCT,
      0, 0, sysctl_ffs_fsck, "S,fsck", "Adjust Inode Reference Count");

static SYSCTL_NODE(_vfs_ffs, FFS_ADJ_BLKCNT, adjblkcnt, CTLFLAG_WR,
      sysctl_ffs_fsck, "Adjust Inode Used Blocks Count");

static SYSCTL_NODE(_vfs_ffs, FFS_ADJ_NDIR, adjndir, CTLFLAG_WR,
      sysctl_ffs_fsck, "Adjust number of directories");

static SYSCTL_NODE(_vfs_ffs, FFS_ADJ_NBFREE, adjnbfree, CTLFLAG_WR,
      sysctl_ffs_fsck, "Adjust number of free blocks");

static SYSCTL_NODE(_vfs_ffs, FFS_ADJ_NIFREE, adjnifree, CTLFLAG_WR,
      sysctl_ffs_fsck, "Adjust number of free inodes");

static SYSCTL_NODE(_vfs_ffs, FFS_ADJ_NFFREE, adjnffree, CTLFLAG_WR,
      sysctl_ffs_fsck, "Adjust number of free frags");

static SYSCTL_NODE(_vfs_ffs, FFS_ADJ_NUMCLUSTERS, adjnumclusters, CTLFLAG_WR,
      sysctl_ffs_fsck, "Adjust number of free clusters");

static SYSCTL_NODE(_vfs_ffs, FFS_DIR_FREE, freedirs, CTLFLAG_WR,
      sysctl_ffs_fsck, "Free Range of Directory Inodes");

static SYSCTL_NODE(_vfs_ffs, FFS_FILE_FREE, freefiles, CTLFLAG_WR,
      sysctl_ffs_fsck, "Free Range of File Inodes");

static SYSCTL_NODE(_vfs_ffs, FFS_BLK_FREE, freeblks, CTLFLAG_WR,
      sysctl_ffs_fsck, "Free Range of Blocks");

static SYSCTL_NODE(_vfs_ffs, FFS_SET_FLAGS, setflags, CTLFLAG_WR,
      sysctl_ffs_fsck, "Change Filesystem Flags");

#ifdef DEBUG
static int fsckcmds = 0;
SYSCTL_INT(_debug, OID_AUTO, fsckcmds, CTLFLAG_RW, &fsckcmds, 0, "");
#endif /* DEBUG */

static int
sysctl_ffs_fsck(SYSCTL_HANDLER_ARGS)
{
      struct fsck_cmd cmd;
      struct ufsmount *ump;
      struct vnode *vp;
      struct inode *ip;
      struct mount *mp;
      struct fs *fs;
      ufs2_daddr_t blkno;
      long blkcnt, blksize;
      struct file *fp;
      int filetype, error;

      if (req->newlen > sizeof cmd)
            return (EBADRPC);
      if ((error = SYSCTL_IN(req, &cmd, sizeof cmd)) != 0)
            return (error);
      if (cmd.version != FFS_CMD_VERSION)
            return (ERPCMISMATCH);
      if ((error = getvnode(curproc->p_fd, cmd.handle, &fp)) != 0)
            return (error);
      vn_start_write(fp->f_data, &mp, V_WAIT);
      if (mp == 0 || strncmp(mp->mnt_stat.f_fstypename, "ufs", MFSNAMELEN)) {
            vn_finished_write(mp);
            fdrop(fp, curthread);
            return (EINVAL);
      }
      if (mp->mnt_flag & MNT_RDONLY) {
            vn_finished_write(mp);
            fdrop(fp, curthread);
            return (EROFS);
      }
      ump = VFSTOUFS(mp);
      fs = ump->um_fs;
      filetype = IFREG;

      switch (oidp->oid_number) {

      case FFS_SET_FLAGS:
#ifdef DEBUG
            if (fsckcmds)
                  printf("%s: %s flags\n", mp->mnt_stat.f_mntonname,
                      cmd.size > 0 ? "set" : "clear");
#endif /* DEBUG */
            if (cmd.size > 0)
                  fs->fs_flags |= (long)cmd.value;
            else
                  fs->fs_flags &= ~(long)cmd.value;
            break;

      case FFS_ADJ_REFCNT:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("%s: adjust inode %jd count by %jd\n",
                      mp->mnt_stat.f_mntonname, (intmax_t)cmd.value,
                      (intmax_t)cmd.size);
            }
#endif /* DEBUG */
            if ((error = ffs_vget(mp, (ino_t)cmd.value, LK_EXCLUSIVE, &vp)))
                  break;
            ip = VTOI(vp);
            ip->i_nlink += cmd.size;
            DIP_SET(ip, i_nlink, ip->i_nlink);
            ip->i_effnlink += cmd.size;
            ip->i_flag |= IN_CHANGE;
            if (DOINGSOFTDEP(vp))
                  softdep_change_linkcnt(ip);
            vput(vp);
            break;

      case FFS_ADJ_BLKCNT:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("%s: adjust inode %jd block count by %jd\n",
                      mp->mnt_stat.f_mntonname, (intmax_t)cmd.value,
                      (intmax_t)cmd.size);
            }
#endif /* DEBUG */
            if ((error = ffs_vget(mp, (ino_t)cmd.value, LK_EXCLUSIVE, &vp)))
                  break;
            ip = VTOI(vp);
            if (ip->i_flag & IN_SPACECOUNTED) {
                  UFS_LOCK(ump);
                  fs->fs_pendingblocks += cmd.size;
                  UFS_UNLOCK(ump);
            }
            DIP_SET(ip, i_blocks, DIP(ip, i_blocks) + cmd.size);
            ip->i_flag |= IN_CHANGE;
            vput(vp);
            break;

      case FFS_DIR_FREE:
            filetype = IFDIR;
            /* fall through */

      case FFS_FILE_FREE:
#ifdef DEBUG
            if (fsckcmds) {
                  if (cmd.size == 1)
                        printf("%s: free %s inode %d\n",
                            mp->mnt_stat.f_mntonname,
                            filetype == IFDIR ? "directory" : "file",
                            (ino_t)cmd.value);
                  else
                        printf("%s: free %s inodes %d-%d\n",
                            mp->mnt_stat.f_mntonname,
                            filetype == IFDIR ? "directory" : "file",
                            (ino_t)cmd.value,
                            (ino_t)(cmd.value + cmd.size - 1));
            }
#endif /* DEBUG */
            while (cmd.size > 0) {
                  if ((error = ffs_freefile(ump, fs, ump->um_devvp,
                      cmd.value, filetype)))
                        break;
                  cmd.size -= 1;
                  cmd.value += 1;
            }
            break;

      case FFS_BLK_FREE:
#ifdef DEBUG
            if (fsckcmds) {
                  if (cmd.size == 1)
                        printf("%s: free block %jd\n",
                            mp->mnt_stat.f_mntonname,
                            (intmax_t)cmd.value);
                  else
                        printf("%s: free blocks %jd-%jd\n",
                            mp->mnt_stat.f_mntonname, 
                            (intmax_t)cmd.value,
                            (intmax_t)cmd.value + cmd.size - 1);
            }
#endif /* DEBUG */
            blkno = cmd.value;
            blkcnt = cmd.size;
            blksize = fs->fs_frag - (blkno % fs->fs_frag);
            while (blkcnt > 0) {
                  if (blksize > blkcnt)
                        blksize = blkcnt;
                  ffs_blkfree(ump, fs, ump->um_devvp, blkno,
                      blksize * fs->fs_fsize, ROOTINO);
                  blkno += blksize;
                  blkcnt -= blksize;
                  blksize = fs->fs_frag;
            }
            break;

      /*
       * Adjust superblock summaries.  fsck(8) is expected to
       * submit deltas when necessary.
       */
      case FFS_ADJ_NDIR:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("%s: adjust number of directories by %jd\n",
                      mp->mnt_stat.f_mntonname, (intmax_t)cmd.value);
            }
#endif /* DEBUG */
            fs->fs_cstotal.cs_ndir += cmd.value;
            break;
      case FFS_ADJ_NBFREE:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("%s: adjust number of free blocks by %+jd\n",
                      mp->mnt_stat.f_mntonname, (intmax_t)cmd.value);
            }
#endif /* DEBUG */
            fs->fs_cstotal.cs_nbfree += cmd.value;
            break;
      case FFS_ADJ_NIFREE:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("%s: adjust number of free inodes by %+jd\n",
                      mp->mnt_stat.f_mntonname, (intmax_t)cmd.value);
            }
#endif /* DEBUG */
            fs->fs_cstotal.cs_nifree += cmd.value;
            break;
      case FFS_ADJ_NFFREE:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("%s: adjust number of free frags by %+jd\n",
                      mp->mnt_stat.f_mntonname, (intmax_t)cmd.value);
            }
#endif /* DEBUG */
            fs->fs_cstotal.cs_nffree += cmd.value;
            break;
      case FFS_ADJ_NUMCLUSTERS:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("%s: adjust number of free clusters by %+jd\n",
                      mp->mnt_stat.f_mntonname, (intmax_t)cmd.value);
            }
#endif /* DEBUG */
            fs->fs_cstotal.cs_numclusters += cmd.value;
            break;

      default:
#ifdef DEBUG
            if (fsckcmds) {
                  printf("Invalid request %d from fsck\n",
                      oidp->oid_number);
            }
#endif /* DEBUG */
            error = EINVAL;
            break;

      }
      fdrop(fp, curthread);
      vn_finished_write(mp);
      return (error);
}

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