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xfs_ialloc.c

/*
 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
 * All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write the Free Software Foundation,
 * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_types.h"
#include "xfs_bit.h"
#include "xfs_log.h"
#include "xfs_inum.h"
#include "xfs_trans.h"
#include "xfs_sb.h"
#include "xfs_ag.h"
#include "xfs_dir2.h"
#include "xfs_dmapi.h"
#include "xfs_mount.h"
#include "xfs_bmap_btree.h"
#include "xfs_alloc_btree.h"
#include "xfs_ialloc_btree.h"
#include "xfs_dir2_sf.h"
#include "xfs_attr_sf.h"
#include "xfs_dinode.h"
#include "xfs_inode.h"
#include "xfs_btree.h"
#include "xfs_ialloc.h"
#include "xfs_alloc.h"
#include "xfs_rtalloc.h"
#include "xfs_error.h"
#include "xfs_bmap.h"

/*
 * Log specified fields for the inode given by bp and off.
 */
STATIC void
xfs_ialloc_log_di(
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_buf_t   *bp,        /* inode buffer */
      int         off,        /* index of inode in buffer */
      int         fields)           /* bitmask of fields to log */
{
      int               first;            /* first byte number */
      int               ioffset;    /* off in bytes */
      int               last;       /* last byte number */
      xfs_mount_t       *mp;        /* mount point structure */
      static const short      offsets[] = {     /* field offsets */
                                    /* keep in sync with bits */
            offsetof(xfs_dinode_core_t, di_magic),
            offsetof(xfs_dinode_core_t, di_mode),
            offsetof(xfs_dinode_core_t, di_version),
            offsetof(xfs_dinode_core_t, di_format),
            offsetof(xfs_dinode_core_t, di_onlink),
            offsetof(xfs_dinode_core_t, di_uid),
            offsetof(xfs_dinode_core_t, di_gid),
            offsetof(xfs_dinode_core_t, di_nlink),
            offsetof(xfs_dinode_core_t, di_projid),
            offsetof(xfs_dinode_core_t, di_pad),
            offsetof(xfs_dinode_core_t, di_atime),
            offsetof(xfs_dinode_core_t, di_mtime),
            offsetof(xfs_dinode_core_t, di_ctime),
            offsetof(xfs_dinode_core_t, di_size),
            offsetof(xfs_dinode_core_t, di_nblocks),
            offsetof(xfs_dinode_core_t, di_extsize),
            offsetof(xfs_dinode_core_t, di_nextents),
            offsetof(xfs_dinode_core_t, di_anextents),
            offsetof(xfs_dinode_core_t, di_forkoff),
            offsetof(xfs_dinode_core_t, di_aformat),
            offsetof(xfs_dinode_core_t, di_dmevmask),
            offsetof(xfs_dinode_core_t, di_dmstate),
            offsetof(xfs_dinode_core_t, di_flags),
            offsetof(xfs_dinode_core_t, di_gen),
            offsetof(xfs_dinode_t, di_next_unlinked),
            offsetof(xfs_dinode_t, di_u),
            offsetof(xfs_dinode_t, di_a),
            sizeof(xfs_dinode_t)
      };


      ASSERT(offsetof(xfs_dinode_t, di_core) == 0);
      ASSERT((fields & (XFS_DI_U|XFS_DI_A)) == 0);
      mp = tp->t_mountp;
      /*
       * Get the inode-relative first and last bytes for these fields
       */
      xfs_btree_offsets(fields, offsets, XFS_DI_NUM_BITS, &first, &last);
      /*
       * Convert to buffer offsets and log it.
       */
      ioffset = off << mp->m_sb.sb_inodelog;
      first += ioffset;
      last += ioffset;
      xfs_trans_log_buf(tp, bp, first, last);
}

/*
 * Allocation group level functions.
 */

/*
 * Allocate new inodes in the allocation group specified by agbp.
 * Return 0 for success, else error code.
 */
STATIC int                    /* error code or 0 */
xfs_ialloc_ag_alloc(
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_buf_t   *agbp,            /* alloc group buffer */
      int         *alloc)
{
      xfs_agi_t   *agi;       /* allocation group header */
      xfs_alloc_arg_t   args;       /* allocation argument structure */
      int         blks_per_cluster;  /* fs blocks per inode cluster */
      xfs_btree_cur_t   *cur;       /* inode btree cursor */
      xfs_daddr_t d;          /* disk addr of buffer */
      xfs_agnumber_t    agno;
      int         error;
      xfs_buf_t   *fbuf;            /* new free inodes' buffer */
      xfs_dinode_t      *free;            /* new free inode structure */
      int         i;          /* inode counter */
      int         j;          /* block counter */
      int         nbufs;            /* num bufs of new inodes */
      xfs_agino_t newino;           /* new first inode's number */
      xfs_agino_t newlen;           /* new number of inodes */
      int         ninodes;    /* num inodes per buf */
      xfs_agino_t thisino;    /* current inode number, for loop */
      int         version;    /* inode version number to use */
      int         isaligned = 0;    /* inode allocation at stripe unit */
                              /* boundary */

      args.tp = tp;
      args.mp = tp->t_mountp;

      /*
       * Locking will ensure that we don't have two callers in here
       * at one time.
       */
      newlen = XFS_IALLOC_INODES(args.mp);
      if (args.mp->m_maxicount &&
          args.mp->m_sb.sb_icount + newlen > args.mp->m_maxicount)
            return XFS_ERROR(ENOSPC);
      args.minlen = args.maxlen = XFS_IALLOC_BLOCKS(args.mp);
      /*
       * First try to allocate inodes contiguous with the last-allocated
       * chunk of inodes.  If the filesystem is striped, this will fill
       * an entire stripe unit with inodes.
       */
      agi = XFS_BUF_TO_AGI(agbp);
      newino = be32_to_cpu(agi->agi_newino);
      args.agbno = XFS_AGINO_TO_AGBNO(args.mp, newino) +
                  XFS_IALLOC_BLOCKS(args.mp);
      if (likely(newino != NULLAGINO &&
              (args.agbno < be32_to_cpu(agi->agi_length)))) {
            args.fsbno = XFS_AGB_TO_FSB(args.mp,
                        be32_to_cpu(agi->agi_seqno), args.agbno);
            args.type = XFS_ALLOCTYPE_THIS_BNO;
            args.mod = args.total = args.wasdel = args.isfl =
                  args.userdata = args.minalignslop = 0;
            args.prod = 1;
            args.alignment = 1;
            /*
             * Allow space for the inode btree to split.
             */
            args.minleft = XFS_IN_MAXLEVELS(args.mp) - 1;
            if ((error = xfs_alloc_vextent(&args)))
                  return error;
      } else
            args.fsbno = NULLFSBLOCK;

      if (unlikely(args.fsbno == NULLFSBLOCK)) {
            /*
             * Set the alignment for the allocation.
             * If stripe alignment is turned on then align at stripe unit
             * boundary.
             * If the cluster size is smaller than a filesystem block
             * then we're doing I/O for inodes in filesystem block size
             * pieces, so don't need alignment anyway.
             */
            isaligned = 0;
            if (args.mp->m_sinoalign) {
                  ASSERT(!(args.mp->m_flags & XFS_MOUNT_NOALIGN));
                  args.alignment = args.mp->m_dalign;
                  isaligned = 1;
            } else if (XFS_SB_VERSION_HASALIGN(&args.mp->m_sb) &&
                     args.mp->m_sb.sb_inoalignmt >=
                     XFS_B_TO_FSBT(args.mp,
                        XFS_INODE_CLUSTER_SIZE(args.mp)))
                        args.alignment = args.mp->m_sb.sb_inoalignmt;
            else
                  args.alignment = 1;
            /*
             * Need to figure out where to allocate the inode blocks.
             * Ideally they should be spaced out through the a.g.
             * For now, just allocate blocks up front.
             */
            args.agbno = be32_to_cpu(agi->agi_root);
            args.fsbno = XFS_AGB_TO_FSB(args.mp,
                        be32_to_cpu(agi->agi_seqno), args.agbno);
            /*
             * Allocate a fixed-size extent of inodes.
             */
            args.type = XFS_ALLOCTYPE_NEAR_BNO;
            args.mod = args.total = args.wasdel = args.isfl =
                  args.userdata = args.minalignslop = 0;
            args.prod = 1;
            /*
             * Allow space for the inode btree to split.
             */
            args.minleft = XFS_IN_MAXLEVELS(args.mp) - 1;
            if ((error = xfs_alloc_vextent(&args)))
                  return error;
      }

      /*
       * If stripe alignment is turned on, then try again with cluster
       * alignment.
       */
      if (isaligned && args.fsbno == NULLFSBLOCK) {
            args.type = XFS_ALLOCTYPE_NEAR_BNO;
            args.agbno = be32_to_cpu(agi->agi_root);
            args.fsbno = XFS_AGB_TO_FSB(args.mp,
                        be32_to_cpu(agi->agi_seqno), args.agbno);
            if (XFS_SB_VERSION_HASALIGN(&args.mp->m_sb) &&
                  args.mp->m_sb.sb_inoalignmt >=
                  XFS_B_TO_FSBT(args.mp, XFS_INODE_CLUSTER_SIZE(args.mp)))
                        args.alignment = args.mp->m_sb.sb_inoalignmt;
            else
                  args.alignment = 1;
            if ((error = xfs_alloc_vextent(&args)))
                  return error;
      }

      if (args.fsbno == NULLFSBLOCK) {
            *alloc = 0;
            return 0;
      }
      ASSERT(args.len == args.minlen);
      /*
       * Convert the results.
       */
      newino = XFS_OFFBNO_TO_AGINO(args.mp, args.agbno, 0);
      /*
       * Loop over the new block(s), filling in the inodes.
       * For small block sizes, manipulate the inodes in buffers
       * which are multiples of the blocks size.
       */
      if (args.mp->m_sb.sb_blocksize >= XFS_INODE_CLUSTER_SIZE(args.mp)) {
            blks_per_cluster = 1;
            nbufs = (int)args.len;
            ninodes = args.mp->m_sb.sb_inopblock;
      } else {
            blks_per_cluster = XFS_INODE_CLUSTER_SIZE(args.mp) /
                           args.mp->m_sb.sb_blocksize;
            nbufs = (int)args.len / blks_per_cluster;
            ninodes = blks_per_cluster * args.mp->m_sb.sb_inopblock;
      }
      /*
       * Figure out what version number to use in the inodes we create.
       * If the superblock version has caught up to the one that supports
       * the new inode format, then use the new inode version.  Otherwise
       * use the old version so that old kernels will continue to be
       * able to use the file system.
       */
      if (XFS_SB_VERSION_HASNLINK(&args.mp->m_sb))
            version = XFS_DINODE_VERSION_2;
      else
            version = XFS_DINODE_VERSION_1;

      for (j = 0; j < nbufs; j++) {
            /*
             * Get the block.
             */
            d = XFS_AGB_TO_DADDR(args.mp, be32_to_cpu(agi->agi_seqno),
                             args.agbno + (j * blks_per_cluster));
            fbuf = xfs_trans_get_buf(tp, args.mp->m_ddev_targp, d,
                               args.mp->m_bsize * blks_per_cluster,
                               XFS_BUF_LOCK);
            ASSERT(fbuf);
            ASSERT(!XFS_BUF_GETERROR(fbuf));
            /*
             * Set initial values for the inodes in this buffer.
             */
            xfs_biozero(fbuf, 0, ninodes << args.mp->m_sb.sb_inodelog);
            for (i = 0; i < ninodes; i++) {
                  free = XFS_MAKE_IPTR(args.mp, fbuf, i);
                  free->di_core.di_magic = cpu_to_be16(XFS_DINODE_MAGIC);
                  free->di_core.di_version = version;
                  free->di_next_unlinked = cpu_to_be32(NULLAGINO);
                  xfs_ialloc_log_di(tp, fbuf, i,
                        XFS_DI_CORE_BITS | XFS_DI_NEXT_UNLINKED);
            }
            xfs_trans_inode_alloc_buf(tp, fbuf);
      }
      be32_add(&agi->agi_count, newlen);
      be32_add(&agi->agi_freecount, newlen);
      agno = be32_to_cpu(agi->agi_seqno);
      down_read(&args.mp->m_peraglock);
      args.mp->m_perag[agno].pagi_freecount += newlen;
      up_read(&args.mp->m_peraglock);
      agi->agi_newino = cpu_to_be32(newino);
      /*
       * Insert records describing the new inode chunk into the btree.
       */
      cur = xfs_btree_init_cursor(args.mp, tp, agbp, agno,
                  XFS_BTNUM_INO, (xfs_inode_t *)0, 0);
      for (thisino = newino;
           thisino < newino + newlen;
           thisino += XFS_INODES_PER_CHUNK) {
            if ((error = xfs_inobt_lookup_eq(cur, thisino,
                        XFS_INODES_PER_CHUNK, XFS_INOBT_ALL_FREE, &i))) {
                  xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
                  return error;
            }
            ASSERT(i == 0);
            if ((error = xfs_inobt_insert(cur, &i))) {
                  xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
                  return error;
            }
            ASSERT(i == 1);
      }
      xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
      /*
       * Log allocation group header fields
       */
      xfs_ialloc_log_agi(tp, agbp,
            XFS_AGI_COUNT | XFS_AGI_FREECOUNT | XFS_AGI_NEWINO);
      /*
       * Modify/log superblock values for inode count and inode free count.
       */
      xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, (long)newlen);
      xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, (long)newlen);
      *alloc = 1;
      return 0;
}

STATIC_INLINE xfs_agnumber_t
xfs_ialloc_next_ag(
      xfs_mount_t *mp)
{
      xfs_agnumber_t    agno;

      spin_lock(&mp->m_agirotor_lock);
      agno = mp->m_agirotor;
      if (++mp->m_agirotor == mp->m_maxagi)
            mp->m_agirotor = 0;
      spin_unlock(&mp->m_agirotor_lock);

      return agno;
}

/*
 * Select an allocation group to look for a free inode in, based on the parent
 * inode and then mode.  Return the allocation group buffer.
 */
STATIC xfs_buf_t *                  /* allocation group buffer */
xfs_ialloc_ag_select(
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_ino_t   parent,           /* parent directory inode number */
      mode_t            mode,       /* bits set to indicate file type */
      int         okalloc)    /* ok to allocate more space */
{
      xfs_buf_t   *agbp;            /* allocation group header buffer */
      xfs_agnumber_t    agcount;    /* number of ag's in the filesystem */
      xfs_agnumber_t    agno;       /* current ag number */
      int         flags;            /* alloc buffer locking flags */
      xfs_extlen_t      ineed;            /* blocks needed for inode allocation */
      xfs_extlen_t      longest = 0;      /* longest extent available */
      xfs_mount_t *mp;        /* mount point structure */
      int         needspace;  /* file mode implies space allocated */
      xfs_perag_t *pag;       /* per allocation group data */
      xfs_agnumber_t    pagno;            /* parent (starting) ag number */

      /*
       * Files of these types need at least one block if length > 0
       * (and they won't fit in the inode, but that's hard to figure out).
       */
      needspace = S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode);
      mp = tp->t_mountp;
      agcount = mp->m_maxagi;
      if (S_ISDIR(mode))
            pagno = xfs_ialloc_next_ag(mp);
      else {
            pagno = XFS_INO_TO_AGNO(mp, parent);
            if (pagno >= agcount)
                  pagno = 0;
      }
      ASSERT(pagno < agcount);
      /*
       * Loop through allocation groups, looking for one with a little
       * free space in it.  Note we don't look for free inodes, exactly.
       * Instead, we include whether there is a need to allocate inodes
       * to mean that blocks must be allocated for them,
       * if none are currently free.
       */
      agno = pagno;
      flags = XFS_ALLOC_FLAG_TRYLOCK;
      down_read(&mp->m_peraglock);
      for (;;) {
            pag = &mp->m_perag[agno];
            if (!pag->pagi_init) {
                  if (xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
                        agbp = NULL;
                        goto nextag;
                  }
            } else
                  agbp = NULL;

            if (!pag->pagi_inodeok) {
                  xfs_ialloc_next_ag(mp);
                  goto unlock_nextag;
            }

            /*
             * Is there enough free space for the file plus a block
             * of inodes (if we need to allocate some)?
             */
            ineed = pag->pagi_freecount ? 0 : XFS_IALLOC_BLOCKS(mp);
            if (ineed && !pag->pagf_init) {
                  if (agbp == NULL &&
                      xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
                        agbp = NULL;
                        goto nextag;
                  }
                  (void)xfs_alloc_pagf_init(mp, tp, agno, flags);
            }
            if (!ineed || pag->pagf_init) {
                  if (ineed && !(longest = pag->pagf_longest))
                        longest = pag->pagf_flcount > 0;
                  if (!ineed ||
                      (pag->pagf_freeblks >= needspace + ineed &&
                       longest >= ineed &&
                       okalloc)) {
                        if (agbp == NULL &&
                            xfs_ialloc_read_agi(mp, tp, agno, &agbp)) {
                              agbp = NULL;
                              goto nextag;
                        }
                        up_read(&mp->m_peraglock);
                        return agbp;
                  }
            }
unlock_nextag:
            if (agbp)
                  xfs_trans_brelse(tp, agbp);
nextag:
            /*
             * No point in iterating over the rest, if we're shutting
             * down.
             */
            if (XFS_FORCED_SHUTDOWN(mp)) {
                  up_read(&mp->m_peraglock);
                  return NULL;
            }
            agno++;
            if (agno >= agcount)
                  agno = 0;
            if (agno == pagno) {
                  if (flags == 0) {
                        up_read(&mp->m_peraglock);
                        return NULL;
                  }
                  flags = 0;
            }
      }
}

/*
 * Visible inode allocation functions.
 */

/*
 * Allocate an inode on disk.
 * Mode is used to tell whether the new inode will need space, and whether
 * it is a directory.
 *
 * The arguments IO_agbp and alloc_done are defined to work within
 * the constraint of one allocation per transaction.
 * xfs_dialloc() is designed to be called twice if it has to do an
 * allocation to make more free inodes.  On the first call,
 * IO_agbp should be set to NULL. If an inode is available,
 * i.e., xfs_dialloc() did not need to do an allocation, an inode
 * number is returned.  In this case, IO_agbp would be set to the
 * current ag_buf and alloc_done set to false.
 * If an allocation needed to be done, xfs_dialloc would return
 * the current ag_buf in IO_agbp and set alloc_done to true.
 * The caller should then commit the current transaction, allocate a new
 * transaction, and call xfs_dialloc() again, passing in the previous
 * value of IO_agbp.  IO_agbp should be held across the transactions.
 * Since the agbp is locked across the two calls, the second call is
 * guaranteed to have a free inode available.
 *
 * Once we successfully pick an inode its number is returned and the
 * on-disk data structures are updated.  The inode itself is not read
 * in, since doing so would break ordering constraints with xfs_reclaim.
 */
int
xfs_dialloc(
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_ino_t   parent,           /* parent inode (directory) */
      mode_t            mode,       /* mode bits for new inode */
      int         okalloc,    /* ok to allocate more space */
      xfs_buf_t   **IO_agbp,  /* in/out ag header's buffer */
      boolean_t   *alloc_done,      /* true if we needed to replenish
                                 inode freelist */
      xfs_ino_t   *inop)            /* inode number allocated */
{
      xfs_agnumber_t    agcount;    /* number of allocation groups */
      xfs_buf_t   *agbp;            /* allocation group header's buffer */
      xfs_agnumber_t    agno;       /* allocation group number */
      xfs_agi_t   *agi;       /* allocation group header structure */
      xfs_btree_cur_t   *cur;       /* inode allocation btree cursor */
      int         error;            /* error return value */
      int         i;          /* result code */
      int         ialloced;   /* inode allocation status */
      int         noroom = 0; /* no space for inode blk allocation */
      xfs_ino_t   ino;        /* fs-relative inode to be returned */
      /* REFERENCED */
      int         j;          /* result code */
      xfs_mount_t *mp;        /* file system mount structure */
      int         offset;           /* index of inode in chunk */
      xfs_agino_t pagino;           /* parent's a.g. relative inode # */
      xfs_agnumber_t    pagno;            /* parent's allocation group number */
      xfs_inobt_rec_incore_t rec;   /* inode allocation record */
      xfs_agnumber_t    tagno;            /* testing allocation group number */
      xfs_btree_cur_t   *tcur;            /* temp cursor */
      xfs_inobt_rec_incore_t trec;  /* temp inode allocation record */


      if (*IO_agbp == NULL) {
            /*
             * We do not have an agbp, so select an initial allocation
             * group for inode allocation.
             */
            agbp = xfs_ialloc_ag_select(tp, parent, mode, okalloc);
            /*
             * Couldn't find an allocation group satisfying the
             * criteria, give up.
             */
            if (!agbp) {
                  *inop = NULLFSINO;
                  return 0;
            }
            agi = XFS_BUF_TO_AGI(agbp);
            ASSERT(be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC);
      } else {
            /*
             * Continue where we left off before.  In this case, we
             * know that the allocation group has free inodes.
             */
            agbp = *IO_agbp;
            agi = XFS_BUF_TO_AGI(agbp);
            ASSERT(be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC);
            ASSERT(be32_to_cpu(agi->agi_freecount) > 0);
      }
      mp = tp->t_mountp;
      agcount = mp->m_sb.sb_agcount;
      agno = be32_to_cpu(agi->agi_seqno);
      tagno = agno;
      pagno = XFS_INO_TO_AGNO(mp, parent);
      pagino = XFS_INO_TO_AGINO(mp, parent);

      /*
       * If we have already hit the ceiling of inode blocks then clear
       * okalloc so we scan all available agi structures for a free
       * inode.
       */

      if (mp->m_maxicount &&
          mp->m_sb.sb_icount + XFS_IALLOC_INODES(mp) > mp->m_maxicount) {
            noroom = 1;
            okalloc = 0;
      }

      /*
       * Loop until we find an allocation group that either has free inodes
       * or in which we can allocate some inodes.  Iterate through the
       * allocation groups upward, wrapping at the end.
       */
      *alloc_done = B_FALSE;
      while (!agi->agi_freecount) {
            /*
             * Don't do anything if we're not supposed to allocate
             * any blocks, just go on to the next ag.
             */
            if (okalloc) {
                  /*
                   * Try to allocate some new inodes in the allocation
                   * group.
                   */
                  if ((error = xfs_ialloc_ag_alloc(tp, agbp, &ialloced))) {
                        xfs_trans_brelse(tp, agbp);
                        if (error == ENOSPC) {
                              *inop = NULLFSINO;
                              return 0;
                        } else
                              return error;
                  }
                  if (ialloced) {
                        /*
                         * We successfully allocated some inodes, return
                         * the current context to the caller so that it
                         * can commit the current transaction and call
                         * us again where we left off.
                         */
                        ASSERT(be32_to_cpu(agi->agi_freecount) > 0);
                        *alloc_done = B_TRUE;
                        *IO_agbp = agbp;
                        *inop = NULLFSINO;
                        return 0;
                  }
            }
            /*
             * If it failed, give up on this ag.
             */
            xfs_trans_brelse(tp, agbp);
            /*
             * Go on to the next ag: get its ag header.
             */
nextag:
            if (++tagno == agcount)
                  tagno = 0;
            if (tagno == agno) {
                  *inop = NULLFSINO;
                  return noroom ? ENOSPC : 0;
            }
            down_read(&mp->m_peraglock);
            if (mp->m_perag[tagno].pagi_inodeok == 0) {
                  up_read(&mp->m_peraglock);
                  goto nextag;
            }
            error = xfs_ialloc_read_agi(mp, tp, tagno, &agbp);
            up_read(&mp->m_peraglock);
            if (error)
                  goto nextag;
            agi = XFS_BUF_TO_AGI(agbp);
            ASSERT(be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC);
      }
      /*
       * Here with an allocation group that has a free inode.
       * Reset agno since we may have chosen a new ag in the
       * loop above.
       */
      agno = tagno;
      *IO_agbp = NULL;
      cur = xfs_btree_init_cursor(mp, tp, agbp, be32_to_cpu(agi->agi_seqno),
                            XFS_BTNUM_INO, (xfs_inode_t *)0, 0);
      /*
       * If pagino is 0 (this is the root inode allocation) use newino.
       * This must work because we've just allocated some.
       */
      if (!pagino)
            pagino = be32_to_cpu(agi->agi_newino);
#ifdef DEBUG
      if (cur->bc_nlevels == 1) {
            int   freecount = 0;

            if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
                  goto error0;
            XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
            do {
                  if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino,
                              &rec.ir_freecount, &rec.ir_free, &i)))
                        goto error0;
                  XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
                  freecount += rec.ir_freecount;
                  if ((error = xfs_inobt_increment(cur, 0, &i)))
                        goto error0;
            } while (i == 1);

            ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||
                   XFS_FORCED_SHUTDOWN(mp));
      }
#endif
      /*
       * If in the same a.g. as the parent, try to get near the parent.
       */
      if (pagno == agno) {
            if ((error = xfs_inobt_lookup_le(cur, pagino, 0, 0, &i)))
                  goto error0;
            if (i != 0 &&
                (error = xfs_inobt_get_rec(cur, &rec.ir_startino,
                      &rec.ir_freecount, &rec.ir_free, &j)) == 0 &&
                j == 1 &&
                rec.ir_freecount > 0) {
                  /*
                   * Found a free inode in the same chunk
                   * as parent, done.
                   */
            }
            /*
             * In the same a.g. as parent, but parent's chunk is full.
             */
            else {
                  int   doneleft;   /* done, to the left */
                  int   doneright;  /* done, to the right */

                  if (error)
                        goto error0;
                  ASSERT(i == 1);
                  ASSERT(j == 1);
                  /*
                   * Duplicate the cursor, search left & right
                   * simultaneously.
                   */
                  if ((error = xfs_btree_dup_cursor(cur, &tcur)))
                        goto error0;
                  /*
                   * Search left with tcur, back up 1 record.
                   */
                  if ((error = xfs_inobt_decrement(tcur, 0, &i)))
                        goto error1;
                  doneleft = !i;
                  if (!doneleft) {
                        if ((error = xfs_inobt_get_rec(tcur,
                                    &trec.ir_startino,
                                    &trec.ir_freecount,
                                    &trec.ir_free, &i)))
                              goto error1;
                        XFS_WANT_CORRUPTED_GOTO(i == 1, error1);
                  }
                  /*
                   * Search right with cur, go forward 1 record.
                   */
                  if ((error = xfs_inobt_increment(cur, 0, &i)))
                        goto error1;
                  doneright = !i;
                  if (!doneright) {
                        if ((error = xfs_inobt_get_rec(cur,
                                    &rec.ir_startino,
                                    &rec.ir_freecount,
                                    &rec.ir_free, &i)))
                              goto error1;
                        XFS_WANT_CORRUPTED_GOTO(i == 1, error1);
                  }
                  /*
                   * Loop until we find the closest inode chunk
                   * with a free one.
                   */
                  while (!doneleft || !doneright) {
                        int   useleft;  /* using left inode
                                         chunk this time */

                        /*
                         * Figure out which block is closer,
                         * if both are valid.
                         */
                        if (!doneleft && !doneright)
                              useleft =
                                    pagino -
                                    (trec.ir_startino +
                                     XFS_INODES_PER_CHUNK - 1) <
                                     rec.ir_startino - pagino;
                        else
                              useleft = !doneleft;
                        /*
                         * If checking the left, does it have
                         * free inodes?
                         */
                        if (useleft && trec.ir_freecount) {
                              /*
                               * Yes, set it up as the chunk to use.
                               */
                              rec = trec;
                              xfs_btree_del_cursor(cur,
                                    XFS_BTREE_NOERROR);
                              cur = tcur;
                              break;
                        }
                        /*
                         * If checking the right, does it have
                         * free inodes?
                         */
                        if (!useleft && rec.ir_freecount) {
                              /*
                               * Yes, it's already set up.
                               */
                              xfs_btree_del_cursor(tcur,
                                    XFS_BTREE_NOERROR);
                              break;
                        }
                        /*
                         * If used the left, get another one
                         * further left.
                         */
                        if (useleft) {
                              if ((error = xfs_inobt_decrement(tcur, 0,
                                          &i)))
                                    goto error1;
                              doneleft = !i;
                              if (!doneleft) {
                                    if ((error = xfs_inobt_get_rec(
                                              tcur,
                                              &trec.ir_startino,
                                              &trec.ir_freecount,
                                              &trec.ir_free, &i)))
                                          goto error1;
                                    XFS_WANT_CORRUPTED_GOTO(i == 1,
                                          error1);
                              }
                        }
                        /*
                         * If used the right, get another one
                         * further right.
                         */
                        else {
                              if ((error = xfs_inobt_increment(cur, 0,
                                          &i)))
                                    goto error1;
                              doneright = !i;
                              if (!doneright) {
                                    if ((error = xfs_inobt_get_rec(
                                              cur,
                                              &rec.ir_startino,
                                              &rec.ir_freecount,
                                              &rec.ir_free, &i)))
                                          goto error1;
                                    XFS_WANT_CORRUPTED_GOTO(i == 1,
                                          error1);
                              }
                        }
                  }
                  ASSERT(!doneleft || !doneright);
            }
      }
      /*
       * In a different a.g. from the parent.
       * See if the most recently allocated block has any free.
       */
      else if (be32_to_cpu(agi->agi_newino) != NULLAGINO) {
            if ((error = xfs_inobt_lookup_eq(cur,
                        be32_to_cpu(agi->agi_newino), 0, 0, &i)))
                  goto error0;
            if (i == 1 &&
                (error = xfs_inobt_get_rec(cur, &rec.ir_startino,
                      &rec.ir_freecount, &rec.ir_free, &j)) == 0 &&
                j == 1 &&
                rec.ir_freecount > 0) {
                  /*
                   * The last chunk allocated in the group still has
                   * a free inode.
                   */
            }
            /*
             * None left in the last group, search the whole a.g.
             */
            else {
                  if (error)
                        goto error0;
                  if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
                        goto error0;
                  ASSERT(i == 1);
                  for (;;) {
                        if ((error = xfs_inobt_get_rec(cur,
                                    &rec.ir_startino,
                                    &rec.ir_freecount, &rec.ir_free,
                                    &i)))
                              goto error0;
                        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
                        if (rec.ir_freecount > 0)
                              break;
                        if ((error = xfs_inobt_increment(cur, 0, &i)))
                              goto error0;
                        XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
                  }
            }
      }
      offset = XFS_IALLOC_FIND_FREE(&rec.ir_free);
      ASSERT(offset >= 0);
      ASSERT(offset < XFS_INODES_PER_CHUNK);
      ASSERT((XFS_AGINO_TO_OFFSET(mp, rec.ir_startino) %
                           XFS_INODES_PER_CHUNK) == 0);
      ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino + offset);
      XFS_INOBT_CLR_FREE(&rec, offset);
      rec.ir_freecount--;
      if ((error = xfs_inobt_update(cur, rec.ir_startino, rec.ir_freecount,
                  rec.ir_free)))
            goto error0;
      be32_add(&agi->agi_freecount, -1);
      xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
      down_read(&mp->m_peraglock);
      mp->m_perag[tagno].pagi_freecount--;
      up_read(&mp->m_peraglock);
#ifdef DEBUG
      if (cur->bc_nlevels == 1) {
            int   freecount = 0;

            if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
                  goto error0;
            do {
                  if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino,
                              &rec.ir_freecount, &rec.ir_free, &i)))
                        goto error0;
                  XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
                  freecount += rec.ir_freecount;
                  if ((error = xfs_inobt_increment(cur, 0, &i)))
                        goto error0;
            } while (i == 1);
            ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||
                   XFS_FORCED_SHUTDOWN(mp));
      }
#endif
      xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
      xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -1);
      *inop = ino;
      return 0;
error1:
      xfs_btree_del_cursor(tcur, XFS_BTREE_ERROR);
error0:
      xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
      return error;
}

/*
 * Free disk inode.  Carefully avoids touching the incore inode, all
 * manipulations incore are the caller's responsibility.
 * The on-disk inode is not changed by this operation, only the
 * btree (free inode mask) is changed.
 */
int
xfs_difree(
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_ino_t   inode,            /* inode to be freed */
      xfs_bmap_free_t   *flist,           /* extents to free */
      int         *delete,    /* set if inode cluster was deleted */
      xfs_ino_t   *first_ino) /* first inode in deleted cluster */
{
      /* REFERENCED */
      xfs_agblock_t     agbno;      /* block number containing inode */
      xfs_buf_t   *agbp;      /* buffer containing allocation group header */
      xfs_agino_t agino;      /* inode number relative to allocation group */
      xfs_agnumber_t    agno; /* allocation group number */
      xfs_agi_t   *agi; /* allocation group header */
      xfs_btree_cur_t   *cur; /* inode btree cursor */
      int         error;      /* error return value */
      int         i;    /* result code */
      int         ilen; /* inodes in an inode cluster */
      xfs_mount_t *mp;  /* mount structure for filesystem */
      int         off;  /* offset of inode in inode chunk */
      xfs_inobt_rec_incore_t rec;   /* btree record */

      mp = tp->t_mountp;

      /*
       * Break up inode number into its components.
       */
      agno = XFS_INO_TO_AGNO(mp, inode);
      if (agno >= mp->m_sb.sb_agcount)  {
            cmn_err(CE_WARN,
                  "xfs_difree: agno >= mp->m_sb.sb_agcount (%d >= %d) on %s.  Returning EINVAL.",
                  agno, mp->m_sb.sb_agcount, mp->m_fsname);
            ASSERT(0);
            return XFS_ERROR(EINVAL);
      }
      agino = XFS_INO_TO_AGINO(mp, inode);
      if (inode != XFS_AGINO_TO_INO(mp, agno, agino))  {
            cmn_err(CE_WARN,
                  "xfs_difree: inode != XFS_AGINO_TO_INO() "
                  "(%llu != %llu) on %s.  Returning EINVAL.",
                  (unsigned long long)inode,
                  (unsigned long long)XFS_AGINO_TO_INO(mp, agno, agino),
                  mp->m_fsname);
            ASSERT(0);
            return XFS_ERROR(EINVAL);
      }
      agbno = XFS_AGINO_TO_AGBNO(mp, agino);
      if (agbno >= mp->m_sb.sb_agblocks)  {
            cmn_err(CE_WARN,
                  "xfs_difree: agbno >= mp->m_sb.sb_agblocks (%d >= %d) on %s.  Returning EINVAL.",
                  agbno, mp->m_sb.sb_agblocks, mp->m_fsname);
            ASSERT(0);
            return XFS_ERROR(EINVAL);
      }
      /*
       * Get the allocation group header.
       */
      down_read(&mp->m_peraglock);
      error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
      up_read(&mp->m_peraglock);
      if (error) {
            cmn_err(CE_WARN,
                  "xfs_difree: xfs_ialloc_read_agi() returned an error %d on %s.  Returning error.",
                  error, mp->m_fsname);
            return error;
      }
      agi = XFS_BUF_TO_AGI(agbp);
      ASSERT(be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC);
      ASSERT(agbno < be32_to_cpu(agi->agi_length));
      /*
       * Initialize the cursor.
       */
      cur = xfs_btree_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO,
            (xfs_inode_t *)0, 0);
#ifdef DEBUG
      if (cur->bc_nlevels == 1) {
            int freecount = 0;

            if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
                  goto error0;
            do {
                  if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino,
                              &rec.ir_freecount, &rec.ir_free, &i)))
                        goto error0;
                  if (i) {
                        freecount += rec.ir_freecount;
                        if ((error = xfs_inobt_increment(cur, 0, &i)))
                              goto error0;
                  }
            } while (i == 1);
            ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||
                   XFS_FORCED_SHUTDOWN(mp));
      }
#endif
      /*
       * Look for the entry describing this inode.
       */
      if ((error = xfs_inobt_lookup_le(cur, agino, 0, 0, &i))) {
            cmn_err(CE_WARN,
                  "xfs_difree: xfs_inobt_lookup_le returned()  an error %d on %s.  Returning error.",
                  error, mp->m_fsname);
            goto error0;
      }
      XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
      if ((error = xfs_inobt_get_rec(cur, &rec.ir_startino, &rec.ir_freecount,
                  &rec.ir_free, &i))) {
            cmn_err(CE_WARN,
                  "xfs_difree: xfs_inobt_get_rec()  returned an error %d on %s.  Returning error.",
                  error, mp->m_fsname);
            goto error0;
      }
      XFS_WANT_CORRUPTED_GOTO(i == 1, error0);
      /*
       * Get the offset in the inode chunk.
       */
      off = agino - rec.ir_startino;
      ASSERT(off >= 0 && off < XFS_INODES_PER_CHUNK);
      ASSERT(!XFS_INOBT_IS_FREE(&rec, off));
      /*
       * Mark the inode free & increment the count.
       */
      XFS_INOBT_SET_FREE(&rec, off);
      rec.ir_freecount++;

      /*
       * When an inode cluster is free, it becomes eligible for removal
       */
      if ((mp->m_flags & XFS_MOUNT_IDELETE) &&
          (rec.ir_freecount == XFS_IALLOC_INODES(mp))) {

            *delete = 1;
            *first_ino = XFS_AGINO_TO_INO(mp, agno, rec.ir_startino);

            /*
             * Remove the inode cluster from the AGI B+Tree, adjust the
             * AGI and Superblock inode counts, and mark the disk space
             * to be freed when the transaction is committed.
             */
            ilen = XFS_IALLOC_INODES(mp);
            be32_add(&agi->agi_count, -ilen);
            be32_add(&agi->agi_freecount, -(ilen - 1));
            xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);
            down_read(&mp->m_peraglock);
            mp->m_perag[agno].pagi_freecount -= ilen - 1;
            up_read(&mp->m_peraglock);
            xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, -ilen);
            xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -(ilen - 1));

            if ((error = xfs_inobt_delete(cur, &i))) {
                  cmn_err(CE_WARN, "xfs_difree: xfs_inobt_delete returned an error %d on %s.\n",
                        error, mp->m_fsname);
                  goto error0;
            }

            xfs_bmap_add_free(XFS_AGB_TO_FSB(mp,
                        agno, XFS_INO_TO_AGBNO(mp,rec.ir_startino)),
                        XFS_IALLOC_BLOCKS(mp), flist, mp);
      } else {
            *delete = 0;

            if ((error = xfs_inobt_update(cur, rec.ir_startino, rec.ir_freecount, rec.ir_free))) {
                  cmn_err(CE_WARN,
                        "xfs_difree: xfs_inobt_update()  returned an error %d on %s.  Returning error.",
                        error, mp->m_fsname);
                  goto error0;
            }
            /* 
             * Change the inode free counts and log the ag/sb changes.
             */
            be32_add(&agi->agi_freecount, 1);
            xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
            down_read(&mp->m_peraglock);
            mp->m_perag[agno].pagi_freecount++;
            up_read(&mp->m_peraglock);
            xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, 1);
      }

#ifdef DEBUG
      if (cur->bc_nlevels == 1) {
            int freecount = 0;

            if ((error = xfs_inobt_lookup_ge(cur, 0, 0, 0, &i)))
                  goto error0;
            do {
                  if ((error = xfs_inobt_get_rec(cur,
                              &rec.ir_startino,
                              &rec.ir_freecount,
                              &rec.ir_free, &i)))
                        goto error0;
                  if (i) {
                        freecount += rec.ir_freecount;
                        if ((error = xfs_inobt_increment(cur, 0, &i)))
                              goto error0;
                  }
            } while (i == 1);
            ASSERT(freecount == be32_to_cpu(agi->agi_freecount) ||
                   XFS_FORCED_SHUTDOWN(mp));
      }
#endif
      xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
      return 0;

error0:
      xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
      return error;
}

/*
 * Return the location of the inode in bno/off, for mapping it into a buffer.
 */
/*ARGSUSED*/
int
xfs_dilocate(
      xfs_mount_t *mp,  /* file system mount structure */
      xfs_trans_t *tp,  /* transaction pointer */
      xfs_ino_t   ino,  /* inode to locate */
      xfs_fsblock_t     *bno, /* output: block containing inode */
      int         *len, /* output: num blocks in inode cluster */
      int         *off, /* output: index in block of inode */
      uint        flags)      /* flags concerning inode lookup */
{
      xfs_agblock_t     agbno;      /* block number of inode in the alloc group */
      xfs_buf_t   *agbp;      /* agi buffer */
      xfs_agino_t agino;      /* inode number within alloc group */
      xfs_agnumber_t    agno; /* allocation group number */
      int         blks_per_cluster; /* num blocks per inode cluster */
      xfs_agblock_t     chunk_agbno;      /* first block in inode chunk */
      xfs_agino_t chunk_agino;      /* first agino in inode chunk */
      __int32_t   chunk_cnt;  /* count of free inodes in chunk */
      xfs_inofree_t     chunk_free; /* mask of free inodes in chunk */
      xfs_agblock_t     cluster_agbno;    /* first block in inode cluster */
      xfs_btree_cur_t   *cur; /* inode btree cursor */
      int         error;      /* error code */
      int         i;    /* temp state */
      int         offset;     /* index of inode in its buffer */
      int         offset_agbno;     /* blks from chunk start to inode */

      ASSERT(ino != NULLFSINO);
      /*
       * Split up the inode number into its parts.
       */
      agno = XFS_INO_TO_AGNO(mp, ino);
      agino = XFS_INO_TO_AGINO(mp, ino);
      agbno = XFS_AGINO_TO_AGBNO(mp, agino);
      if (agno >= mp->m_sb.sb_agcount || agbno >= mp->m_sb.sb_agblocks ||
          ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
#ifdef DEBUG
            /* no diagnostics for bulkstat, ino comes from userspace */
            if (flags & XFS_IMAP_BULKSTAT)
                  return XFS_ERROR(EINVAL);
            if (agno >= mp->m_sb.sb_agcount) {
                  xfs_fs_cmn_err(CE_ALERT, mp,
                              "xfs_dilocate: agno (%d) >= "
                              "mp->m_sb.sb_agcount (%d)",
                              agno,  mp->m_sb.sb_agcount);
            }
            if (agbno >= mp->m_sb.sb_agblocks) {
                  xfs_fs_cmn_err(CE_ALERT, mp,
                              "xfs_dilocate: agbno (0x%llx) >= "
                              "mp->m_sb.sb_agblocks (0x%lx)",
                              (unsigned long long) agbno,
                              (unsigned long) mp->m_sb.sb_agblocks);
            }
            if (ino != XFS_AGINO_TO_INO(mp, agno, agino)) {
                  xfs_fs_cmn_err(CE_ALERT, mp,
                              "xfs_dilocate: ino (0x%llx) != "
                              "XFS_AGINO_TO_INO(mp, agno, agino) "
                              "(0x%llx)",
                              ino, XFS_AGINO_TO_INO(mp, agno, agino));
            }
            xfs_stack_trace();
#endif /* DEBUG */
            return XFS_ERROR(EINVAL);
      }
      if ((mp->m_sb.sb_blocksize >= XFS_INODE_CLUSTER_SIZE(mp)) ||
          !(flags & XFS_IMAP_LOOKUP)) {
            offset = XFS_INO_TO_OFFSET(mp, ino);
            ASSERT(offset < mp->m_sb.sb_inopblock);
            *bno = XFS_AGB_TO_FSB(mp, agno, agbno);
            *off = offset;
            *len = 1;
            return 0;
      }
      blks_per_cluster = XFS_INODE_CLUSTER_SIZE(mp) >> mp->m_sb.sb_blocklog;
      if (*bno != NULLFSBLOCK) {
            offset = XFS_INO_TO_OFFSET(mp, ino);
            ASSERT(offset < mp->m_sb.sb_inopblock);
            cluster_agbno = XFS_FSB_TO_AGBNO(mp, *bno);
            *off = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
                  offset;
            *len = blks_per_cluster;
            return 0;
      }
      if (mp->m_inoalign_mask) {
            offset_agbno = agbno & mp->m_inoalign_mask;
            chunk_agbno = agbno - offset_agbno;
      } else {
            down_read(&mp->m_peraglock);
            error = xfs_ialloc_read_agi(mp, tp, agno, &agbp);
            up_read(&mp->m_peraglock);
            if (error) {
#ifdef DEBUG
                  xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
                              "xfs_ialloc_read_agi() returned "
                              "error %d, agno %d",
                              error, agno);
#endif /* DEBUG */
                  return error;
            }
            cur = xfs_btree_init_cursor(mp, tp, agbp, agno, XFS_BTNUM_INO,
                  (xfs_inode_t *)0, 0);
            if ((error = xfs_inobt_lookup_le(cur, agino, 0, 0, &i))) {
#ifdef DEBUG
                  xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
                              "xfs_inobt_lookup_le() failed");
#endif /* DEBUG */
                  goto error0;
            }
            if ((error = xfs_inobt_get_rec(cur, &chunk_agino, &chunk_cnt,
                        &chunk_free, &i))) {
#ifdef DEBUG
                  xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
                              "xfs_inobt_get_rec() failed");
#endif /* DEBUG */
                  goto error0;
            }
            if (i == 0) {
#ifdef DEBUG
                  xfs_fs_cmn_err(CE_ALERT, mp, "xfs_dilocate: "
                              "xfs_inobt_get_rec() failed");
#endif /* DEBUG */
                  error = XFS_ERROR(EINVAL);
            }
            xfs_trans_brelse(tp, agbp);
            xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
            if (error)
                  return error;
            chunk_agbno = XFS_AGINO_TO_AGBNO(mp, chunk_agino);
            offset_agbno = agbno - chunk_agbno;
      }
      ASSERT(agbno >= chunk_agbno);
      cluster_agbno = chunk_agbno +
            ((offset_agbno / blks_per_cluster) * blks_per_cluster);
      offset = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
            XFS_INO_TO_OFFSET(mp, ino);
      *bno = XFS_AGB_TO_FSB(mp, agno, cluster_agbno);
      *off = offset;
      *len = blks_per_cluster;
      return 0;
error0:
      xfs_trans_brelse(tp, agbp);
      xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
      return error;
}

/*
 * Compute and fill in value of m_in_maxlevels.
 */
void
xfs_ialloc_compute_maxlevels(
      xfs_mount_t *mp)        /* file system mount structure */
{
      int         level;
      uint        maxblocks;
      uint        maxleafents;
      int         minleafrecs;
      int         minnoderecs;

      maxleafents = (1LL << XFS_INO_AGINO_BITS(mp)) >>
            XFS_INODES_PER_CHUNK_LOG;
      minleafrecs = mp->m_alloc_mnr[0];
      minnoderecs = mp->m_alloc_mnr[1];
      maxblocks = (maxleafents + minleafrecs - 1) / minleafrecs;
      for (level = 1; maxblocks > 1; level++)
            maxblocks = (maxblocks + minnoderecs - 1) / minnoderecs;
      mp->m_in_maxlevels = level;
}

/*
 * Log specified fields for the ag hdr (inode section)
 */
void
xfs_ialloc_log_agi(
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_buf_t   *bp,        /* allocation group header buffer */
      int         fields)           /* bitmask of fields to log */
{
      int               first;            /* first byte number */
      int               last;       /* last byte number */
      static const short      offsets[] = {     /* field starting offsets */
                              /* keep in sync with bit definitions */
            offsetof(xfs_agi_t, agi_magicnum),
            offsetof(xfs_agi_t, agi_versionnum),
            offsetof(xfs_agi_t, agi_seqno),
            offsetof(xfs_agi_t, agi_length),
            offsetof(xfs_agi_t, agi_count),
            offsetof(xfs_agi_t, agi_root),
            offsetof(xfs_agi_t, agi_level),
            offsetof(xfs_agi_t, agi_freecount),
            offsetof(xfs_agi_t, agi_newino),
            offsetof(xfs_agi_t, agi_dirino),
            offsetof(xfs_agi_t, agi_unlinked),
            sizeof(xfs_agi_t)
      };
#ifdef DEBUG
      xfs_agi_t         *agi; /* allocation group header */

      agi = XFS_BUF_TO_AGI(bp);
      ASSERT(be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC);
#endif
      /*
       * Compute byte offsets for the first and last fields.
       */
      xfs_btree_offsets(fields, offsets, XFS_AGI_NUM_BITS, &first, &last);
      /*
       * Log the allocation group inode header buffer.
       */
      xfs_trans_log_buf(tp, bp, first, last);
}

/*
 * Read in the allocation group header (inode allocation section)
 */
int
xfs_ialloc_read_agi(
      xfs_mount_t *mp,        /* file system mount structure */
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_agnumber_t    agno,       /* allocation group number */
      xfs_buf_t   **bpp)            /* allocation group hdr buf */
{
      xfs_agi_t   *agi;       /* allocation group header */
      int         agi_ok;           /* agi is consistent */
      xfs_buf_t   *bp;        /* allocation group hdr buf */
      xfs_perag_t *pag;       /* per allocation group data */
      int         error;

      ASSERT(agno != NULLAGNUMBER);
      error = xfs_trans_read_buf(
                  mp, tp, mp->m_ddev_targp,
                  XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
                  XFS_FSS_TO_BB(mp, 1), 0, &bp);
      if (error)
            return error;
      ASSERT(bp && !XFS_BUF_GETERROR(bp));

      /*
       * Validate the magic number of the agi block.
       */
      agi = XFS_BUF_TO_AGI(bp);
      agi_ok =
            be32_to_cpu(agi->agi_magicnum) == XFS_AGI_MAGIC &&
            XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum));
      if (unlikely(XFS_TEST_ERROR(!agi_ok, mp, XFS_ERRTAG_IALLOC_READ_AGI,
                  XFS_RANDOM_IALLOC_READ_AGI))) {
            XFS_CORRUPTION_ERROR("xfs_ialloc_read_agi", XFS_ERRLEVEL_LOW,
                             mp, agi);
            xfs_trans_brelse(tp, bp);
            return XFS_ERROR(EFSCORRUPTED);
      }
      pag = &mp->m_perag[agno];
      if (!pag->pagi_init) {
            pag->pagi_freecount = be32_to_cpu(agi->agi_freecount);
            pag->pagi_count = be32_to_cpu(agi->agi_count);
            pag->pagi_init = 1;
      } else {
            /*
             * It's possible for these to be out of sync if
             * we are in the middle of a forced shutdown.
             */
            ASSERT(pag->pagi_freecount == be32_to_cpu(agi->agi_freecount) ||
                  XFS_FORCED_SHUTDOWN(mp));
      }

#ifdef DEBUG
      {
            int   i;

            for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++)
                  ASSERT(agi->agi_unlinked[i]);
      }
#endif

      XFS_BUF_SET_VTYPE_REF(bp, B_FS_AGI, XFS_AGI_REF);
      *bpp = bp;
      return 0;
}

/*
 * Read in the agi to initialise the per-ag data in the mount structure
 */
int
xfs_ialloc_pagi_init(
      xfs_mount_t *mp,        /* file system mount structure */
      xfs_trans_t *tp,        /* transaction pointer */
      xfs_agnumber_t    agno)       /* allocation group number */
{
      xfs_buf_t   *bp = NULL;
      int         error;

      error = xfs_ialloc_read_agi(mp, tp, agno, &bp);
      if (error)
            return error;
      if (bp)
            xfs_trans_brelse(tp, bp);
      return 0;
}

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