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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
  * All Rights Reserved.
  */
 #include "xfs.h"
 #include "xfs_fs.h"
 #include "xfs_shared.h"
 #include "xfs_format.h"
 #include "xfs_log_format.h"
 #include "xfs_trans_resv.h"
 #include "xfs_bit.h"
 #include "xfs_mount.h"
 #include "xfs_inode.h"
 #include "xfs_btree.h"
 #include "xfs_ialloc.h"
 #include "xfs_ialloc_btree.h"
 #include "xfs_alloc.h"
 #include "xfs_errortag.h"
 #include "xfs_error.h"
 #include "xfs_bmap.h"
 #include "xfs_trans.h"
 #include "xfs_buf_item.h"
 #include "xfs_icreate_item.h"
 #include "xfs_icache.h"
 #include "xfs_trace.h"
 #include "xfs_log.h"
 #include "xfs_rmap.h"
 #include "xfs_ag.h"
 
 /*
  * Lookup a record by ino in the btree given by cur.
  */
 int                 /* error */
 xfs_inobt_lookup(
     struct xfs_btree_cur    *cur,   /* btree cursor */
     xfs_agino_t     ino,    /* starting inode of chunk */
     xfs_lookup_t        dir,    /* <=, >=, == */
     int         *stat)  /* success/failure */
 {
     cur->bc_rec.i.ir_startino = ino;
     cur->bc_rec.i.ir_holemask = 0;
     cur->bc_rec.i.ir_count = 0;
     cur->bc_rec.i.ir_freecount = 0;
     cur->bc_rec.i.ir_free = 0;
     return xfs_btree_lookup(cur, dir, stat);
 }
 
 /*
  * Update the record referred to by cur to the value given.
  * This either works (return 0) or gets an EFSCORRUPTED error.
  */
 STATIC int              /* error */
 xfs_inobt_update(
     struct xfs_btree_cur    *cur,   /* btree cursor */
     xfs_inobt_rec_incore_t  *irec)  /* btree record */
 {
     union xfs_btree_rec rec;
 
     rec.inobt.ir_startino = cpu_to_be32(irec->ir_startino);
     if (xfs_has_sparseinodes(cur->bc_mp)) {
         rec.inobt.ir_u.sp.ir_holemask = cpu_to_be16(irec->ir_holemask);
         rec.inobt.ir_u.sp.ir_count = irec->ir_count;
         rec.inobt.ir_u.sp.ir_freecount = irec->ir_freecount;
     } else {
         /* ir_holemask/ir_count not supported on-disk */
         rec.inobt.ir_u.f.ir_freecount = cpu_to_be32(irec->ir_freecount);
     }
     rec.inobt.ir_free = cpu_to_be64(irec->ir_free);
     return xfs_btree_update(cur, &rec);
 }
 
 /* Convert on-disk btree record to incore inobt record. */
 void
 xfs_inobt_btrec_to_irec(
     struct xfs_mount        *mp,
     const union xfs_btree_rec   *rec,
     struct xfs_inobt_rec_incore *irec)
 {
     irec->ir_startino = be32_to_cpu(rec->inobt.ir_startino);
     if (xfs_has_sparseinodes(mp)) {
         irec->ir_holemask = be16_to_cpu(rec->inobt.ir_u.sp.ir_holemask);
         irec->ir_count = rec->inobt.ir_u.sp.ir_count;
         irec->ir_freecount = rec->inobt.ir_u.sp.ir_freecount;
     } else {
         /*
          * ir_holemask/ir_count not supported on-disk. Fill in hardcoded
          * values for full inode chunks.
          */
         irec->ir_holemask = XFS_INOBT_HOLEMASK_FULL;
         irec->ir_count = XFS_INODES_PER_CHUNK;
         irec->ir_freecount =
                 be32_to_cpu(rec->inobt.ir_u.f.ir_freecount);
     }
     irec->ir_free = be64_to_cpu(rec->inobt.ir_free);
 }
 
 /*
  * Get the data from the pointed-to record.
  */
 int
 xfs_inobt_get_rec(
     struct xfs_btree_cur        *cur,
     struct xfs_inobt_rec_incore *irec,
     int             *stat)
 {
     struct xfs_mount        *mp = cur->bc_mp;
     union xfs_btree_rec     *rec;
     int             error;
     uint64_t            realfree;
 
     error = xfs_btree_get_rec(cur, &rec, stat);
     if (error || *stat == 0)
         return error;
 
     xfs_inobt_btrec_to_irec(mp, rec, irec);
 
     if (!xfs_verify_agino(cur->bc_ag.pag, irec->ir_startino))
         goto out_bad_rec;
     if (irec->ir_count < XFS_INODES_PER_HOLEMASK_BIT ||
         irec->ir_count > XFS_INODES_PER_CHUNK)
         goto out_bad_rec;
     if (irec->ir_freecount > XFS_INODES_PER_CHUNK)
         goto out_bad_rec;
 
     /* if there are no holes, return the first available offset */
     if (!xfs_inobt_issparse(irec->ir_holemask))
         realfree = irec->ir_free;
     else
         realfree = irec->ir_free & xfs_inobt_irec_to_allocmask(irec);
     if (hweight64(realfree) != irec->ir_freecount)
         goto out_bad_rec;
 
     return 0;
 
 out_bad_rec:
     xfs_warn(mp,
         "%s Inode BTree record corruption in AG %d detected!",
         cur->bc_btnum == XFS_BTNUM_INO ? "Used" : "Free",
         cur->bc_ag.pag->pag_agno);
     xfs_warn(mp,
 "start inode 0x%x, count 0x%x, free 0x%x freemask 0x%llx, holemask 0x%x",
         irec->ir_startino, irec->ir_count, irec->ir_freecount,
         irec->ir_free, irec->ir_holemask);
     return -EFSCORRUPTED;
 }
 
 /*
  * Insert a single inobt record. Cursor must already point to desired location.
  */
 int
 xfs_inobt_insert_rec(
     struct xfs_btree_cur    *cur,
     uint16_t        holemask,
     uint8_t         count,
     int32_t         freecount,
     xfs_inofree_t       free,
     int         *stat)
 {
     cur->bc_rec.i.ir_holemask = holemask;
     cur->bc_rec.i.ir_count = count;
     cur->bc_rec.i.ir_freecount = freecount;
     cur->bc_rec.i.ir_free = free;
     return xfs_btree_insert(cur, stat);
 }
 
 /*
  * Insert records describing a newly allocated inode chunk into the inobt.
  */
 STATIC int
 xfs_inobt_insert(
     struct xfs_mount    *mp,
     struct xfs_trans    *tp,
     struct xfs_buf      *agbp,
     struct xfs_perag    *pag,
     xfs_agino_t     newino,
     xfs_agino_t     newlen,
     xfs_btnum_t     btnum)
 {
     struct xfs_btree_cur    *cur;
     xfs_agino_t     thisino;
     int         i;
     int         error;
 
     cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, btnum);
 
     for (thisino = newino;
          thisino < newino + newlen;
          thisino += XFS_INODES_PER_CHUNK) {
         error = xfs_inobt_lookup(cur, thisino, XFS_LOOKUP_EQ, &i);
         if (error) {
             xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
             return error;
         }
         ASSERT(i == 0);
 
         error = xfs_inobt_insert_rec(cur, XFS_INOBT_HOLEMASK_FULL,
                          XFS_INODES_PER_CHUNK,
                          XFS_INODES_PER_CHUNK,
                          XFS_INOBT_ALL_FREE, &i);
         if (error) {
             xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
             return error;
         }
         ASSERT(i == 1);
     }
 
     xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
 
     return 0;
 }
 
 /*
  * Verify that the number of free inodes in the AGI is correct.
  */
 #ifdef DEBUG
 static int
 xfs_check_agi_freecount(
     struct xfs_btree_cur    *cur)
 {
     if (cur->bc_nlevels == 1) {
         xfs_inobt_rec_incore_t rec;
         int     freecount = 0;
         int     error;
         int     i;
 
         error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &i);
         if (error)
             return error;
 
         do {
             error = xfs_inobt_get_rec(cur, &rec, &i);
             if (error)
                 return error;
 
             if (i) {
                 freecount += rec.ir_freecount;
                 error = xfs_btree_increment(cur, 0, &i);
                 if (error)
                     return error;
             }
         } while (i == 1);
 
         if (!xfs_is_shutdown(cur->bc_mp))
             ASSERT(freecount == cur->bc_ag.pag->pagi_freecount);
     }
     return 0;
 }
 #else
 #define xfs_check_agi_freecount(cur)    0
 #endif
 
 /*
  * Initialise a new set of inodes. When called without a transaction context
  * (e.g. from recovery) we initiate a delayed write of the inode buffers rather
  * than logging them (which in a transaction context puts them into the AIL
  * for writeback rather than the xfsbufd queue).
  */
 int
 xfs_ialloc_inode_init(
     struct xfs_mount    *mp,
     struct xfs_trans    *tp,
     struct list_head    *buffer_list,
     int         icount,
     xfs_agnumber_t      agno,
     xfs_agblock_t       agbno,
     xfs_agblock_t       length,
     unsigned int        gen)
 {
     struct xfs_buf      *fbuf;
     struct xfs_dinode   *free;
     int         nbufs;
     int         version;
     int         i, j;
     xfs_daddr_t     d;
     xfs_ino_t       ino = 0;
     int         error;
 
     /*
      * 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.
      */
     nbufs = length / M_IGEO(mp)->blocks_per_cluster;
 
     /*
      * 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.
      *
      * For v3 inodes, we also need to write the inode number into the inode,
      * so calculate the first inode number of the chunk here as
      * XFS_AGB_TO_AGINO() only works within a filesystem block, not
      * across multiple filesystem blocks (such as a cluster) and so cannot
      * be used in the cluster buffer loop below.
      *
      * Further, because we are writing the inode directly into the buffer
      * and calculating a CRC on the entire inode, we have ot log the entire
      * inode so that the entire range the CRC covers is present in the log.
      * That means for v3 inode we log the entire buffer rather than just the
      * inode cores.
      */
     if (xfs_has_v3inodes(mp)) {
         version = 3;
         ino = XFS_AGINO_TO_INO(mp, agno, XFS_AGB_TO_AGINO(mp, agbno));
 
         /*
          * log the initialisation that is about to take place as an
          * logical operation. This means the transaction does not
          * need to log the physical changes to the inode buffers as log
          * recovery will know what initialisation is actually needed.
          * Hence we only need to log the buffers as "ordered" buffers so
          * they track in the AIL as if they were physically logged.
          */
         if (tp)
             xfs_icreate_log(tp, agno, agbno, icount,
                     mp->m_sb.sb_inodesize, length, gen);
     } else
         version = 2;
 
     for (j = 0; j < nbufs; j++) {
         /*
          * Get the block.
          */
         d = XFS_AGB_TO_DADDR(mp, agno, agbno +
                 (j * M_IGEO(mp)->blocks_per_cluster));
         error = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
                 mp->m_bsize * M_IGEO(mp)->blocks_per_cluster,
                 XBF_UNMAPPED, &fbuf);
         if (error)
             return error;
 
         /* Initialize the inode buffers and log them appropriately. */
         fbuf->b_ops = &xfs_inode_buf_ops;
         xfs_buf_zero(fbuf, 0, BBTOB(fbuf->b_length));
         for (i = 0; i < M_IGEO(mp)->inodes_per_cluster; i++) {
             int ioffset = i << mp->m_sb.sb_inodelog;
 
             free = xfs_make_iptr(mp, fbuf, i);
             free->di_magic = cpu_to_be16(XFS_DINODE_MAGIC);
             free->di_version = version;
             free->di_gen = cpu_to_be32(gen);
             free->di_next_unlinked = cpu_to_be32(NULLAGINO);
 
             if (version == 3) {
                 free->di_ino = cpu_to_be64(ino);
                 ino++;
                 uuid_copy(&free->di_uuid,
                       &mp->m_sb.sb_meta_uuid);
                 xfs_dinode_calc_crc(mp, free);
             } else if (tp) {
                 /* just log the inode core */
                 xfs_trans_log_buf(tp, fbuf, ioffset,
                       ioffset + XFS_DINODE_SIZE(mp) - 1);
             }
         }
 
         if (tp) {
             /*
              * Mark the buffer as an inode allocation buffer so it
              * sticks in AIL at the point of this allocation
              * transaction. This ensures the they are on disk before
              * the tail of the log can be moved past this
              * transaction (i.e. by preventing relogging from moving
              * it forward in the log).
              */
             xfs_trans_inode_alloc_buf(tp, fbuf);
             if (version == 3) {
                 /*
                  * Mark the buffer as ordered so that they are
                  * not physically logged in the transaction but
                  * still tracked in the AIL as part of the
                  * transaction and pin the log appropriately.
                  */
                 xfs_trans_ordered_buf(tp, fbuf);
             }
         } else {
             fbuf->b_flags |= XBF_DONE;
             xfs_buf_delwri_queue(fbuf, buffer_list);
             xfs_buf_relse(fbuf);
         }
     }
     return 0;
 }
 
 /*
  * Align startino and allocmask for a recently allocated sparse chunk such that
  * they are fit for insertion (or merge) into the on-disk inode btrees.
  *
  * Background:
  *
  * When enabled, sparse inode support increases the inode alignment from cluster
  * size to inode chunk size. This means that the minimum range between two
  * non-adjacent inode records in the inobt is large enough for a full inode
  * record. This allows for cluster sized, cluster aligned block allocation
  * without need to worry about whether the resulting inode record overlaps with
  * another record in the tree. Without this basic rule, we would have to deal
  * with the consequences of overlap by potentially undoing recent allocations in
  * the inode allocation codepath.
  *
  * Because of this alignment rule (which is enforced on mount), there are two
  * inobt possibilities for newly allocated sparse chunks. One is that the
  * aligned inode record for the chunk covers a range of inodes not already
  * covered in the inobt (i.e., it is safe to insert a new sparse record). The
  * other is that a record already exists at the aligned startino that considers
  * the newly allocated range as sparse. In the latter case, record content is
  * merged in hope that sparse inode chunks fill to full chunks over time.
  */
 STATIC void
 xfs_align_sparse_ino(
     struct xfs_mount        *mp,
     xfs_agino_t         *startino,
     uint16_t            *allocmask)
 {
     xfs_agblock_t           agbno;
     xfs_agblock_t           mod;
     int             offset;
 
     agbno = XFS_AGINO_TO_AGBNO(mp, *startino);
     mod = agbno % mp->m_sb.sb_inoalignmt;
     if (!mod)
         return;
 
     /* calculate the inode offset and align startino */
     offset = XFS_AGB_TO_AGINO(mp, mod);
     *startino -= offset;
 
     /*
      * Since startino has been aligned down, left shift allocmask such that
      * it continues to represent the same physical inodes relative to the
      * new startino.
      */
     *allocmask <<= offset / XFS_INODES_PER_HOLEMASK_BIT;
 }
 
 /*
  * Determine whether the source inode record can merge into the target. Both
  * records must be sparse, the inode ranges must match and there must be no
  * allocation overlap between the records.
  */
 STATIC bool
 __xfs_inobt_can_merge(
     struct xfs_inobt_rec_incore *trec,  /* tgt record */
     struct xfs_inobt_rec_incore *srec)  /* src record */
 {
     uint64_t            talloc;
     uint64_t            salloc;
 
     /* records must cover the same inode range */
     if (trec->ir_startino != srec->ir_startino)
         return false;
 
     /* both records must be sparse */
     if (!xfs_inobt_issparse(trec->ir_holemask) ||
         !xfs_inobt_issparse(srec->ir_holemask))
         return false;
 
     /* both records must track some inodes */
     if (!trec->ir_count || !srec->ir_count)
         return false;
 
     /* can't exceed capacity of a full record */
     if (trec->ir_count + srec->ir_count > XFS_INODES_PER_CHUNK)
         return false;
 
     /* verify there is no allocation overlap */
     talloc = xfs_inobt_irec_to_allocmask(trec);
     salloc = xfs_inobt_irec_to_allocmask(srec);
     if (talloc & salloc)
         return false;
 
     return true;
 }
 
 /*
  * Merge the source inode record into the target. The caller must call
  * __xfs_inobt_can_merge() to ensure the merge is valid.
  */
 STATIC void
 __xfs_inobt_rec_merge(
     struct xfs_inobt_rec_incore *trec,  /* target */
     struct xfs_inobt_rec_incore *srec)  /* src */
 {
     ASSERT(trec->ir_startino == srec->ir_startino);
 
     /* combine the counts */
     trec->ir_count += srec->ir_count;
     trec->ir_freecount += srec->ir_freecount;
 
     /*
      * Merge the holemask and free mask. For both fields, 0 bits refer to
      * allocated inodes. We combine the allocated ranges with bitwise AND.
      */
     trec->ir_holemask &= srec->ir_holemask;
     trec->ir_free &= srec->ir_free;
 }
 
 /*
  * Insert a new sparse inode chunk into the associated inode btree. The inode
  * record for the sparse chunk is pre-aligned to a startino that should match
  * any pre-existing sparse inode record in the tree. This allows sparse chunks
  * to fill over time.
  *
  * This function supports two modes of handling preexisting records depending on
  * the merge flag. If merge is true, the provided record is merged with the
  * existing record and updated in place. The merged record is returned in nrec.
  * If merge is false, an existing record is replaced with the provided record.
  * If no preexisting record exists, the provided record is always inserted.
  *
  * It is considered corruption if a merge is requested and not possible. Given
  * the sparse inode alignment constraints, this should never happen.
  */
 STATIC int
 xfs_inobt_insert_sprec(
     struct xfs_mount        *mp,
     struct xfs_trans        *tp,
     struct xfs_buf          *agbp,
     struct xfs_perag        *pag,
     int             btnum,
     struct xfs_inobt_rec_incore *nrec,  /* in/out: new/merged rec. */
     bool                merge)  /* merge or replace */
 {
     struct xfs_btree_cur        *cur;
     int             error;
     int             i;
     struct xfs_inobt_rec_incore rec;
 
     cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, btnum);
 
     /* the new record is pre-aligned so we know where to look */
     error = xfs_inobt_lookup(cur, nrec->ir_startino, XFS_LOOKUP_EQ, &i);
     if (error)
         goto error;
     /* if nothing there, insert a new record and return */
     if (i == 0) {
         error = xfs_inobt_insert_rec(cur, nrec->ir_holemask,
                          nrec->ir_count, nrec->ir_freecount,
                          nrec->ir_free, &i);
         if (error)
             goto error;
         if (XFS_IS_CORRUPT(mp, i != 1)) {
             error = -EFSCORRUPTED;
             goto error;
         }
 
         goto out;
     }
 
     /*
      * A record exists at this startino. Merge or replace the record
      * depending on what we've been asked to do.
      */
     if (merge) {
         error = xfs_inobt_get_rec(cur, &rec, &i);
         if (error)
             goto error;
         if (XFS_IS_CORRUPT(mp, i != 1)) {
             error = -EFSCORRUPTED;
             goto error;
         }
         if (XFS_IS_CORRUPT(mp, rec.ir_startino != nrec->ir_startino)) {
             error = -EFSCORRUPTED;
             goto error;
         }
 
         /*
          * This should never fail. If we have coexisting records that
          * cannot merge, something is seriously wrong.
          */
         if (XFS_IS_CORRUPT(mp, !__xfs_inobt_can_merge(nrec, &rec))) {
             error = -EFSCORRUPTED;
             goto error;
         }
 
         trace_xfs_irec_merge_pre(mp, pag->pag_agno, rec.ir_startino,
                      rec.ir_holemask, nrec->ir_startino,
                      nrec->ir_holemask);
 
         /* merge to nrec to output the updated record */
         __xfs_inobt_rec_merge(nrec, &rec);
 
         trace_xfs_irec_merge_post(mp, pag->pag_agno, nrec->ir_startino,
                       nrec->ir_holemask);
 
         error = xfs_inobt_rec_check_count(mp, nrec);
         if (error)
             goto error;
     }
 
     error = xfs_inobt_update(cur, nrec);
     if (error)
         goto error;
 
 out:
     xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
     return 0;
 error:
     xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
     return error;
 }
 
 /*
  * Allocate new inodes in the allocation group specified by agbp.  Returns 0 if
  * inodes were allocated in this AG; -EAGAIN if there was no space in this AG so
  * the caller knows it can try another AG, a hard -ENOSPC when over the maximum
  * inode count threshold, or the usual negative error code for other errors.
  */
 STATIC int
 xfs_ialloc_ag_alloc(
     struct xfs_trans    *tp,
     struct xfs_buf      *agbp,
     struct xfs_perag    *pag)
 {
     struct xfs_agi      *agi;
     struct xfs_alloc_arg    args;
     int         error;
     xfs_agino_t     newino;     /* new first inode's number */
     xfs_agino_t     newlen;     /* new number of inodes */
     int         isaligned = 0;  /* inode allocation at stripe */
                         /* unit boundary */
     /* init. to full chunk */
     struct xfs_inobt_rec_incore rec;
     struct xfs_ino_geometry *igeo = M_IGEO(tp->t_mountp);
     uint16_t        allocmask = (uint16_t) -1;
     int         do_sparse = 0;
 
     memset(&args, 0, sizeof(args));
     args.tp = tp;
     args.mp = tp->t_mountp;
     args.fsbno = NULLFSBLOCK;
     args.oinfo = XFS_RMAP_OINFO_INODES;
 
 #ifdef DEBUG
     /* randomly do sparse inode allocations */
     if (xfs_has_sparseinodes(tp->t_mountp) &&
         igeo->ialloc_min_blks < igeo->ialloc_blks)
         do_sparse = prandom_u32() & 1;
 #endif
 
     /*
      * Locking will ensure that we don't have two callers in here
      * at one time.
      */
     newlen = igeo->ialloc_inos;
     if (igeo->maxicount &&
         percpu_counter_read_positive(&args.mp->m_icount) + newlen >
                             igeo->maxicount)
         return -ENOSPC;
     args.minlen = args.maxlen = igeo->ialloc_blks;
     /*
      * 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 = agbp->b_addr;
     newino = be32_to_cpu(agi->agi_newino);
     args.agbno = XFS_AGINO_TO_AGBNO(args.mp, newino) +
              igeo->ialloc_blks;
     if (do_sparse)
         goto sparse_alloc;
     if (likely(newino != NULLAGINO &&
           (args.agbno < be32_to_cpu(agi->agi_length)))) {
         args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
         args.type = XFS_ALLOCTYPE_THIS_BNO;
         args.prod = 1;
 
         /*
          * We need to take into account alignment here to ensure that
          * we don't modify the free list if we fail to have an exact
          * block. If we don't have an exact match, and every oher
          * attempt allocation attempt fails, we'll end up cancelling
          * a dirty transaction and shutting down.
          *
          * For an exact allocation, alignment must be 1,
          * however we need to take cluster alignment into account when
          * fixing up the freelist. Use the minalignslop field to
          * indicate that extra blocks might be required for alignment,
          * but not to use them in the actual exact allocation.
          */
         args.alignment = 1;
         args.minalignslop = igeo->cluster_align - 1;
 
         /* Allow space for the inode btree to split. */
         args.minleft = igeo->inobt_maxlevels;
         if ((error = xfs_alloc_vextent(&args)))
             return error;
 
         /*
          * This request might have dirtied the transaction if the AG can
          * satisfy the request, but the exact block was not available.
          * If the allocation did fail, subsequent requests will relax
          * the exact agbno requirement and increase the alignment
          * instead. It is critical that the total size of the request
          * (len + alignment + slop) does not increase from this point
          * on, so reset minalignslop to ensure it is not included in
          * subsequent requests.
          */
         args.minalignslop = 0;
     }
 
     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 (igeo->ialloc_align) {
             ASSERT(!xfs_has_noalign(args.mp));
             args.alignment = args.mp->m_dalign;
             isaligned = 1;
         } else
             args.alignment = igeo->cluster_align;
         /*
          * 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, pag->pag_agno, args.agbno);
         /*
          * Allocate a fixed-size extent of inodes.
          */
         args.type = XFS_ALLOCTYPE_NEAR_BNO;
         args.prod = 1;
         /*
          * Allow space for the inode btree to split.
          */
         args.minleft = igeo->inobt_maxlevels;
         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, pag->pag_agno, args.agbno);
         args.alignment = igeo->cluster_align;
         if ((error = xfs_alloc_vextent(&args)))
             return error;
     }
 
     /*
      * Finally, try a sparse allocation if the filesystem supports it and
      * the sparse allocation length is smaller than a full chunk.
      */
     if (xfs_has_sparseinodes(args.mp) &&
         igeo->ialloc_min_blks < igeo->ialloc_blks &&
         args.fsbno == NULLFSBLOCK) {
 sparse_alloc:
         args.type = XFS_ALLOCTYPE_NEAR_BNO;
         args.agbno = be32_to_cpu(agi->agi_root);
         args.fsbno = XFS_AGB_TO_FSB(args.mp, pag->pag_agno, args.agbno);
         args.alignment = args.mp->m_sb.sb_spino_align;
         args.prod = 1;
 
         args.minlen = igeo->ialloc_min_blks;
         args.maxlen = args.minlen;
 
         /*
          * The inode record will be aligned to full chunk size. We must
          * prevent sparse allocation from AG boundaries that result in
          * invalid inode records, such as records that start at agbno 0
          * or extend beyond the AG.
          *
          * Set min agbno to the first aligned, non-zero agbno and max to
          * the last aligned agbno that is at least one full chunk from
          * the end of the AG.
          */
         args.min_agbno = args.mp->m_sb.sb_inoalignmt;
         args.max_agbno = round_down(args.mp->m_sb.sb_agblocks,
                         args.mp->m_sb.sb_inoalignmt) -
                  igeo->ialloc_blks;
 
         error = xfs_alloc_vextent(&args);
         if (error)
             return error;
 
         newlen = XFS_AGB_TO_AGINO(args.mp, args.len);
         ASSERT(newlen <= XFS_INODES_PER_CHUNK);
         allocmask = (1 << (newlen / XFS_INODES_PER_HOLEMASK_BIT)) - 1;
     }
 
     if (args.fsbno == NULLFSBLOCK)
         return -EAGAIN;
 
     ASSERT(args.len == args.minlen);
 
     /*
      * Stamp and write the inode buffers.
      *
      * Seed the new inode cluster with a random generation number. This
      * prevents short-term reuse of generation numbers if a chunk is
      * freed and then immediately reallocated. We use random numbers
      * rather than a linear progression to prevent the next generation
      * number from being easily guessable.
      */
     error = xfs_ialloc_inode_init(args.mp, tp, NULL, newlen, pag->pag_agno,
             args.agbno, args.len, prandom_u32());
 
     if (error)
         return error;
     /*
      * Convert the results.
      */
     newino = XFS_AGB_TO_AGINO(args.mp, args.agbno);
 
     if (xfs_inobt_issparse(~allocmask)) {
         /*
          * We've allocated a sparse chunk. Align the startino and mask.
          */
         xfs_align_sparse_ino(args.mp, &newino, &allocmask);
 
         rec.ir_startino = newino;
         rec.ir_holemask = ~allocmask;
         rec.ir_count = newlen;
         rec.ir_freecount = newlen;
         rec.ir_free = XFS_INOBT_ALL_FREE;
 
         /*
          * Insert the sparse record into the inobt and allow for a merge
          * if necessary. If a merge does occur, rec is updated to the
          * merged record.
          */
         error = xfs_inobt_insert_sprec(args.mp, tp, agbp, pag,
                 XFS_BTNUM_INO, &rec, true);
         if (error == -EFSCORRUPTED) {
             xfs_alert(args.mp,
     "invalid sparse inode record: ino 0x%llx holemask 0x%x count %u",
                   XFS_AGINO_TO_INO(args.mp, pag->pag_agno,
                            rec.ir_startino),
                   rec.ir_holemask, rec.ir_count);
             xfs_force_shutdown(args.mp, SHUTDOWN_CORRUPT_INCORE);
         }
         if (error)
             return error;
 
         /*
          * We can't merge the part we've just allocated as for the inobt
          * due to finobt semantics. The original record may or may not
          * exist independent of whether physical inodes exist in this
          * sparse chunk.
          *
          * We must update the finobt record based on the inobt record.
          * rec contains the fully merged and up to date inobt record
          * from the previous call. Set merge false to replace any
          * existing record with this one.
          */
         if (xfs_has_finobt(args.mp)) {
             error = xfs_inobt_insert_sprec(args.mp, tp, agbp, pag,
                        XFS_BTNUM_FINO, &rec, false);
             if (error)
                 return error;
         }
     } else {
         /* full chunk - insert new records to both btrees */
         error = xfs_inobt_insert(args.mp, tp, agbp, pag, newino, newlen,
                      XFS_BTNUM_INO);
         if (error)
             return error;
 
         if (xfs_has_finobt(args.mp)) {
             error = xfs_inobt_insert(args.mp, tp, agbp, pag, newino,
                          newlen, XFS_BTNUM_FINO);
             if (error)
                 return error;
         }
     }
 
     /*
      * Update AGI counts and newino.
      */
     be32_add_cpu(&agi->agi_count, newlen);
     be32_add_cpu(&agi->agi_freecount, newlen);
     pag->pagi_freecount += newlen;
     pag->pagi_count += newlen;
     agi->agi_newino = cpu_to_be32(newino);
 
     /*
      * 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);
     return 0;
 }
 
 /*
  * Try to retrieve the next record to the left/right from the current one.
  */
 STATIC int
 xfs_ialloc_next_rec(
     struct xfs_btree_cur    *cur,
     xfs_inobt_rec_incore_t  *rec,
     int         *done,
     int         left)
 {
     int                     error;
     int         i;
 
     if (left)
         error = xfs_btree_decrement(cur, 0, &i);
     else
         error = xfs_btree_increment(cur, 0, &i);
 
     if (error)
         return error;
     *done = !i;
     if (i) {
         error = xfs_inobt_get_rec(cur, rec, &i);
         if (error)
             return error;
         if (XFS_IS_CORRUPT(cur->bc_mp, i != 1))
             return -EFSCORRUPTED;
     }
 
     return 0;
 }
 
 STATIC int
 xfs_ialloc_get_rec(
     struct xfs_btree_cur    *cur,
     xfs_agino_t     agino,
     xfs_inobt_rec_incore_t  *rec,
     int         *done)
 {
     int                     error;
     int         i;
 
     error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_EQ, &i);
     if (error)
         return error;
     *done = !i;
     if (i) {
         error = xfs_inobt_get_rec(cur, rec, &i);
         if (error)
             return error;
         if (XFS_IS_CORRUPT(cur->bc_mp, i != 1))
             return -EFSCORRUPTED;
     }
 
     return 0;
 }
 
 /*
  * Return the offset of the first free inode in the record. If the inode chunk
  * is sparsely allocated, we convert the record holemask to inode granularity
  * and mask off the unallocated regions from the inode free mask.
  */
 STATIC int
 xfs_inobt_first_free_inode(
     struct xfs_inobt_rec_incore *rec)
 {
     xfs_inofree_t           realfree;
 
     /* if there are no holes, return the first available offset */
     if (!xfs_inobt_issparse(rec->ir_holemask))
         return xfs_lowbit64(rec->ir_free);
 
     realfree = xfs_inobt_irec_to_allocmask(rec);
     realfree &= rec->ir_free;
 
     return xfs_lowbit64(realfree);
 }
 
 /*
  * Allocate an inode using the inobt-only algorithm.
  */
 STATIC int
 xfs_dialloc_ag_inobt(
     struct xfs_trans    *tp,
     struct xfs_buf      *agbp,
     struct xfs_perag    *pag,
     xfs_ino_t       parent,
     xfs_ino_t       *inop)
 {
     struct xfs_mount    *mp = tp->t_mountp;
     struct xfs_agi      *agi = agbp->b_addr;
     xfs_agnumber_t      pagno = XFS_INO_TO_AGNO(mp, parent);
     xfs_agino_t     pagino = XFS_INO_TO_AGINO(mp, parent);
     struct xfs_btree_cur    *cur, *tcur;
     struct xfs_inobt_rec_incore rec, trec;
     xfs_ino_t       ino;
     int         error;
     int         offset;
     int         i, j;
     int         searchdistance = 10;
 
     ASSERT(pag->pagi_init);
     ASSERT(pag->pagi_inodeok);
     ASSERT(pag->pagi_freecount > 0);
 
  restart_pagno:
     cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
     /*
      * 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);
 
     error = xfs_check_agi_freecount(cur);
     if (error)
         goto error0;
 
     /*
      * If in the same AG as the parent, try to get near the parent.
      */
     if (pagno == pag->pag_agno) {
         int     doneleft;   /* done, to the left */
         int     doneright;  /* done, to the right */
 
         error = xfs_inobt_lookup(cur, pagino, XFS_LOOKUP_LE, &i);
         if (error)
             goto error0;
         if (XFS_IS_CORRUPT(mp, i != 1)) {
             error = -EFSCORRUPTED;
             goto error0;
         }
 
         error = xfs_inobt_get_rec(cur, &rec, &j);
         if (error)
             goto error0;
         if (XFS_IS_CORRUPT(mp, j != 1)) {
             error = -EFSCORRUPTED;
             goto error0;
         }
 
         if (rec.ir_freecount > 0) {
             /*
              * Found a free inode in the same chunk
              * as the parent, done.
              */
             goto alloc_inode;
         }
 
 
         /*
          * In the same AG as parent, but parent's chunk is full.
          */
 
         /* duplicate the cursor, search left & right simultaneously */
         error = xfs_btree_dup_cursor(cur, &tcur);
         if (error)
             goto error0;
 
         /*
          * Skip to last blocks looked up if same parent inode.
          */
         if (pagino != NULLAGINO &&
             pag->pagl_pagino == pagino &&
             pag->pagl_leftrec != NULLAGINO &&
             pag->pagl_rightrec != NULLAGINO) {
             error = xfs_ialloc_get_rec(tcur, pag->pagl_leftrec,
                            &trec, &doneleft);
             if (error)
                 goto error1;
 
             error = xfs_ialloc_get_rec(cur, pag->pagl_rightrec,
                            &rec, &doneright);
             if (error)
                 goto error1;
         } else {
             /* search left with tcur, back up 1 record */
             error = xfs_ialloc_next_rec(tcur, &trec, &doneleft, 1);
             if (error)
                 goto error1;
 
             /* search right with cur, go forward 1 record. */
             error = xfs_ialloc_next_rec(cur, &rec, &doneright, 0);
             if (error)
                 goto error1;
         }
 
         /*
          * Loop until we find an inode chunk with a free inode.
          */
         while (--searchdistance > 0 && (!doneleft || !doneright)) {
             int useleft;  /* using left inode chunk this time */
 
             /* figure out the closer block if both are valid. */
             if (!doneleft && !doneright) {
                 useleft = pagino -
                  (trec.ir_startino + XFS_INODES_PER_CHUNK - 1) <
                   rec.ir_startino - pagino;
             } else {
                 useleft = !doneleft;
             }
 
             /* free inodes to the left? */
             if (useleft && trec.ir_freecount) {
                 xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
                 cur = tcur;
 
                 pag->pagl_leftrec = trec.ir_startino;
                 pag->pagl_rightrec = rec.ir_startino;
                 pag->pagl_pagino = pagino;
                 rec = trec;
                 goto alloc_inode;
             }
 
             /* free inodes to the right? */
             if (!useleft && rec.ir_freecount) {
                 xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
 
                 pag->pagl_leftrec = trec.ir_startino;
                 pag->pagl_rightrec = rec.ir_startino;
                 pag->pagl_pagino = pagino;
                 goto alloc_inode;
             }
 
             /* get next record to check */
             if (useleft) {
                 error = xfs_ialloc_next_rec(tcur, &trec,
                                  &doneleft, 1);
             } else {
                 error = xfs_ialloc_next_rec(cur, &rec,
                                  &doneright, 0);
             }
             if (error)
                 goto error1;
         }
 
         if (searchdistance <= 0) {
             /*
              * Not in range - save last search
              * location and allocate a new inode
              */
             xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
             pag->pagl_leftrec = trec.ir_startino;
             pag->pagl_rightrec = rec.ir_startino;
             pag->pagl_pagino = pagino;
 
         } else {
             /*
              * We've reached the end of the btree. because
              * we are only searching a small chunk of the
              * btree each search, there is obviously free
              * inodes closer to the parent inode than we
              * are now. restart the search again.
              */
             pag->pagl_pagino = NULLAGINO;
             pag->pagl_leftrec = NULLAGINO;
             pag->pagl_rightrec = NULLAGINO;
             xfs_btree_del_cursor(tcur, XFS_BTREE_NOERROR);
             xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
             goto restart_pagno;
         }
     }
 
     /*
      * In a different AG from the parent.
      * See if the most recently allocated block has any free.
      */
     if (agi->agi_newino != cpu_to_be32(NULLAGINO)) {
         error = xfs_inobt_lookup(cur, be32_to_cpu(agi->agi_newino),
                      XFS_LOOKUP_EQ, &i);
         if (error)
             goto error0;
 
         if (i == 1) {
             error = xfs_inobt_get_rec(cur, &rec, &j);
             if (error)
                 goto error0;
 
             if (j == 1 && rec.ir_freecount > 0) {
                 /*
                  * The last chunk allocated in the group
                  * still has a free inode.
                  */
                 goto alloc_inode;
             }
         }
     }
 
     /*
      * None left in the last group, search the whole AG
      */
     error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &i);
     if (error)
         goto error0;
     if (XFS_IS_CORRUPT(mp, i != 1)) {
         error = -EFSCORRUPTED;
         goto error0;
     }
 
     for (;;) {
         error = xfs_inobt_get_rec(cur, &rec, &i);
         if (error)
             goto error0;
         if (XFS_IS_CORRUPT(mp, i != 1)) {
             error = -EFSCORRUPTED;
             goto error0;
         }
         if (rec.ir_freecount > 0)
             break;
         error = xfs_btree_increment(cur, 0, &i);
         if (error)
             goto error0;
         if (XFS_IS_CORRUPT(mp, i != 1)) {
             error = -EFSCORRUPTED;
             goto error0;
         }
     }
 
 alloc_inode:
     offset = xfs_inobt_first_free_inode(&rec);
     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, pag->pag_agno, rec.ir_startino + offset);
     rec.ir_free &= ~XFS_INOBT_MASK(offset);
     rec.ir_freecount--;
     error = xfs_inobt_update(cur, &rec);
     if (error)
         goto error0;
     be32_add_cpu(&agi->agi_freecount, -1);
     xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
     pag->pagi_freecount--;
 
     error = xfs_check_agi_freecount(cur);
     if (error)
         goto error0;
 
     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;
 }
 
 /*
  * Use the free inode btree to allocate an inode based on distance from the
  * parent. Note that the provided cursor may be deleted and replaced.
  */
 STATIC int
 xfs_dialloc_ag_finobt_near(
     xfs_agino_t         pagino,
     struct xfs_btree_cur        **ocur,
     struct xfs_inobt_rec_incore *rec)
 {
     struct xfs_btree_cur        *lcur = *ocur;  /* left search cursor */
     struct xfs_btree_cur        *rcur;  /* right search cursor */
     struct xfs_inobt_rec_incore rrec;
     int             error;
     int             i, j;
 
     error = xfs_inobt_lookup(lcur, pagino, XFS_LOOKUP_LE, &i);
     if (error)
         return error;
 
     if (i == 1) {
         error = xfs_inobt_get_rec(lcur, rec, &i);
         if (error)
             return error;
         if (XFS_IS_CORRUPT(lcur->bc_mp, i != 1))
             return -EFSCORRUPTED;
 
         /*
          * See if we've landed in the parent inode record. The finobt
          * only tracks chunks with at least one free inode, so record
          * existence is enough.
          */
         if (pagino >= rec->ir_startino &&
             pagino < (rec->ir_startino + XFS_INODES_PER_CHUNK))
             return 0;
     }
 
     error = xfs_btree_dup_cursor(lcur, &rcur);
     if (error)
         return error;
 
     error = xfs_inobt_lookup(rcur, pagino, XFS_LOOKUP_GE, &j);
     if (error)
         goto error_rcur;
     if (j == 1) {
         error = xfs_inobt_get_rec(rcur, &rrec, &j);
         if (error)
             goto error_rcur;
         if (XFS_IS_CORRUPT(lcur->bc_mp, j != 1)) {
             error = -EFSCORRUPTED;
             goto error_rcur;
         }
     }
 
     if (XFS_IS_CORRUPT(lcur->bc_mp, i != 1 && j != 1)) {
         error = -EFSCORRUPTED;
         goto error_rcur;
     }
     if (i == 1 && j == 1) {
         /*
          * Both the left and right records are valid. Choose the closer
          * inode chunk to the target.
          */
         if ((pagino - rec->ir_startino + XFS_INODES_PER_CHUNK - 1) >
             (rrec.ir_startino - pagino)) {
             *rec = rrec;
             xfs_btree_del_cursor(lcur, XFS_BTREE_NOERROR);
             *ocur = rcur;
         } else {
             xfs_btree_del_cursor(rcur, XFS_BTREE_NOERROR);
         }
     } else if (j == 1) {
         /* only the right record is valid */
         *rec = rrec;
         xfs_btree_del_cursor(lcur, XFS_BTREE_NOERROR);
         *ocur = rcur;
     } else if (i == 1) {
         /* only the left record is valid */
         xfs_btree_del_cursor(rcur, XFS_BTREE_NOERROR);
     }
 
     return 0;
 
 error_rcur:
     xfs_btree_del_cursor(rcur, XFS_BTREE_ERROR);
     return error;
 }
 
 /*
  * Use the free inode btree to find a free inode based on a newino hint. If
  * the hint is NULL, find the first free inode in the AG.
  */
 STATIC int
 xfs_dialloc_ag_finobt_newino(
     struct xfs_agi          *agi,
     struct xfs_btree_cur        *cur,
     struct xfs_inobt_rec_incore *rec)
 {
     int error;
     int i;
 
     if (agi->agi_newino != cpu_to_be32(NULLAGINO)) {
         error = xfs_inobt_lookup(cur, be32_to_cpu(agi->agi_newino),
                      XFS_LOOKUP_EQ, &i);
         if (error)
             return error;
         if (i == 1) {
             error = xfs_inobt_get_rec(cur, rec, &i);
             if (error)
                 return error;
             if (XFS_IS_CORRUPT(cur->bc_mp, i != 1))
                 return -EFSCORRUPTED;
             return 0;
         }
     }
 
     /*
      * Find the first inode available in the AG.
      */
     error = xfs_inobt_lookup(cur, 0, XFS_LOOKUP_GE, &i);
     if (error)
         return error;
     if (XFS_IS_CORRUPT(cur->bc_mp, i != 1))
         return -EFSCORRUPTED;
 
     error = xfs_inobt_get_rec(cur, rec, &i);
     if (error)
         return error;
     if (XFS_IS_CORRUPT(cur->bc_mp, i != 1))
         return -EFSCORRUPTED;
 
     return 0;
 }
 
 /*
  * Update the inobt based on a modification made to the finobt. Also ensure that
  * the records from both trees are equivalent post-modification.
  */
 STATIC int
 xfs_dialloc_ag_update_inobt(
     struct xfs_btree_cur        *cur,   /* inobt cursor */
     struct xfs_inobt_rec_incore *frec,  /* finobt record */
     int             offset) /* inode offset */
 {
     struct xfs_inobt_rec_incore rec;
     int             error;
     int             i;
 
     error = xfs_inobt_lookup(cur, frec->ir_startino, XFS_LOOKUP_EQ, &i);
     if (error)
         return error;
     if (XFS_IS_CORRUPT(cur->bc_mp, i != 1))
         return -EFSCORRUPTED;
 
     error = xfs_inobt_get_rec(cur, &rec, &i);
     if (error)
         return error;
     if (XFS_IS_CORRUPT(cur->bc_mp, i != 1))
         return -EFSCORRUPTED;
     ASSERT((XFS_AGINO_TO_OFFSET(cur->bc_mp, rec.ir_startino) %
                    XFS_INODES_PER_CHUNK) == 0);
 
     rec.ir_free &= ~XFS_INOBT_MASK(offset);
     rec.ir_freecount--;
 
     if (XFS_IS_CORRUPT(cur->bc_mp,
                rec.ir_free != frec->ir_free ||
                rec.ir_freecount != frec->ir_freecount))
         return -EFSCORRUPTED;
 
     return xfs_inobt_update(cur, &rec);
 }
 
 /*
  * Allocate an inode using the free inode btree, if available. Otherwise, fall
  * back to the inobt search algorithm.
  *
  * The caller selected an AG for us, and made sure that free inodes are
  * available.
  */
 static int
 xfs_dialloc_ag(
     struct xfs_trans    *tp,
     struct xfs_buf      *agbp,
     struct xfs_perag    *pag,
     xfs_ino_t       parent,
     xfs_ino_t       *inop)
 {
     struct xfs_mount        *mp = tp->t_mountp;
     struct xfs_agi          *agi = agbp->b_addr;
     xfs_agnumber_t          pagno = XFS_INO_TO_AGNO(mp, parent);
     xfs_agino_t         pagino = XFS_INO_TO_AGINO(mp, parent);
     struct xfs_btree_cur        *cur;   /* finobt cursor */
     struct xfs_btree_cur        *icur;  /* inobt cursor */
     struct xfs_inobt_rec_incore rec;
     xfs_ino_t           ino;
     int             error;
     int             offset;
     int             i;
 
     if (!xfs_has_finobt(mp))
         return xfs_dialloc_ag_inobt(tp, agbp, pag, parent, inop);
 
     /*
      * 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);
 
     cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_FINO);
 
     error = xfs_check_agi_freecount(cur);
     if (error)
         goto error_cur;
 
     /*
      * The search algorithm depends on whether we're in the same AG as the
      * parent. If so, find the closest available inode to the parent. If
      * not, consider the agi hint or find the first free inode in the AG.
      */
     if (pag->pag_agno == pagno)
         error = xfs_dialloc_ag_finobt_near(pagino, &cur, &rec);
     else
         error = xfs_dialloc_ag_finobt_newino(agi, cur, &rec);
     if (error)
         goto error_cur;
 
     offset = xfs_inobt_first_free_inode(&rec);
     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, pag->pag_agno, rec.ir_startino + offset);
 
     /*
      * Modify or remove the finobt record.
      */
     rec.ir_free &= ~XFS_INOBT_MASK(offset);
     rec.ir_freecount--;
     if (rec.ir_freecount)
         error = xfs_inobt_update(cur, &rec);
     else
         error = xfs_btree_delete(cur, &i);
     if (error)
         goto error_cur;
 
     /*
      * The finobt has now been updated appropriately. We haven't updated the
      * agi and superblock yet, so we can create an inobt cursor and validate
      * the original freecount. If all is well, make the equivalent update to
      * the inobt using the finobt record and offset information.
      */
     icur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
 
     error = xfs_check_agi_freecount(icur);
     if (error)
         goto error_icur;
 
     error = xfs_dialloc_ag_update_inobt(icur, &rec, offset);
     if (error)
         goto error_icur;
 
     /*
      * Both trees have now been updated. We must update the perag and
      * superblock before we can check the freecount for each btree.
      */
     be32_add_cpu(&agi->agi_freecount, -1);
     xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
     pag->pagi_freecount--;
 
     xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -1);
 
     error = xfs_check_agi_freecount(icur);
     if (error)
         goto error_icur;
     error = xfs_check_agi_freecount(cur);
     if (error)
         goto error_icur;
 
     xfs_btree_del_cursor(icur, XFS_BTREE_NOERROR);
     xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
     *inop = ino;
     return 0;
 
 error_icur:
     xfs_btree_del_cursor(icur, XFS_BTREE_ERROR);
 error_cur:
     xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
     return error;
 }
 
 static int
 xfs_dialloc_roll(
     struct xfs_trans    **tpp,
     struct xfs_buf      *agibp)
 {
     struct xfs_trans    *tp = *tpp;
     struct xfs_dquot_acct   *dqinfo;
     int         error;
 
     /*
      * Hold to on to the agibp across the commit so no other allocation can
      * come in and take the free inodes we just allocated for our caller.
      */
     xfs_trans_bhold(tp, agibp);
 
     /*
      * We want the quota changes to be associated with the next transaction,
      * NOT this one. So, detach the dqinfo from this and attach it to the
      * next transaction.
      */
     dqinfo = tp->t_dqinfo;
     tp->t_dqinfo = NULL;
 
     error = xfs_trans_roll(&tp);
 
     /* Re-attach the quota info that we detached from prev trx. */
     tp->t_dqinfo = dqinfo;
 
     /*
      * Join the buffer even on commit error so that the buffer is released
      * when the caller cancels the transaction and doesn't have to handle
      * this error case specially.
      */
     xfs_trans_bjoin(tp, agibp);
     *tpp = tp;
     return error;
 }
 
 static 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;
 }
 
 static bool
 xfs_dialloc_good_ag(
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     umode_t         mode,
     int         flags,
     bool            ok_alloc)
 {
     struct xfs_mount    *mp = tp->t_mountp;
     xfs_extlen_t        ineed;
     xfs_extlen_t        longest = 0;
     int         needspace;
     int         error;
 
     if (!pag->pagi_inodeok)
         return false;
 
     if (!pag->pagi_init) {
         error = xfs_ialloc_read_agi(pag, tp, NULL);
         if (error)
             return false;
     }
 
     if (pag->pagi_freecount)
         return true;
     if (!ok_alloc)
         return false;
 
     if (!pag->pagf_init) {
         error = xfs_alloc_read_agf(pag, tp, flags, NULL);
         if (error)
             return false;
     }
 
     /*
      * Check that there is enough free space for the file plus a chunk of
      * inodes if we need to allocate some. If this is the first pass across
      * the AGs, take into account the potential space needed for alignment
      * of inode chunks when checking the longest contiguous free space in
      * the AG - this prevents us from getting ENOSPC because we have free
      * space larger than ialloc_blks but alignment constraints prevent us
      * from using it.
      *
      * If we can't find an AG with space for full alignment slack to be
      * taken into account, we must be near ENOSPC in all AGs.  Hence we
      * don't include alignment for the second pass and so if we fail
      * allocation due to alignment issues then it is most likely a real
      * ENOSPC condition.
      *
      * XXX(dgc): this calculation is now bogus thanks to the per-ag
      * reservations that xfs_alloc_fix_freelist() now does via
      * xfs_alloc_space_available(). When the AG fills up, pagf_freeblks will
      * be more than large enough for the check below to succeed, but
      * xfs_alloc_space_available() will fail because of the non-zero
      * metadata reservation and hence we won't actually be able to allocate
      * more inodes in this AG. We do soooo much unnecessary work near ENOSPC
      * because of this.
      */
     ineed = M_IGEO(mp)->ialloc_min_blks;
     if (flags && ineed > 1)
         ineed += M_IGEO(mp)->cluster_align;
     longest = pag->pagf_longest;
     if (!longest)
         longest = pag->pagf_flcount > 0;
     needspace = S_ISDIR(mode) || S_ISREG(mode) || S_ISLNK(mode);
 
     if (pag->pagf_freeblks < needspace + ineed || longest < ineed)
         return false;
     return true;
 }
 
 static int
 xfs_dialloc_try_ag(
     struct xfs_trans    **tpp,
     struct xfs_perag    *pag,
     xfs_ino_t       parent,
     xfs_ino_t       *new_ino,
     bool            ok_alloc)
 {
     struct xfs_buf      *agbp;
     xfs_ino_t       ino;
     int         error;
 
     /*
      * Then read in the AGI buffer and recheck with the AGI buffer
      * lock held.
      */
     error = xfs_ialloc_read_agi(pag, *tpp, &agbp);
     if (error)
         return error;
 
     if (!pag->pagi_freecount) {
         if (!ok_alloc) {
             error = -EAGAIN;
             goto out_release;
         }
 
         error = xfs_ialloc_ag_alloc(*tpp, agbp, pag);
         if (error < 0)
             goto out_release;
 
         /*
          * We successfully allocated space for an inode cluster in this
          * AG.  Roll the transaction so that we can allocate one of the
          * new inodes.
          */
         ASSERT(pag->pagi_freecount > 0);
         error = xfs_dialloc_roll(tpp, agbp);
         if (error)
             goto out_release;
     }
 
     /* Allocate an inode in the found AG */
     error = xfs_dialloc_ag(*tpp, agbp, pag, parent, &ino);
     if (!error)
         *new_ino = ino;
     return error;
 
 out_release:
     xfs_trans_brelse(*tpp, agbp);
     return error;
 }
 
 /*
  * Allocate an on-disk inode.
  *
  * Mode is used to tell whether the new inode is a directory and hence where to
  * locate it. The on-disk inode that is allocated will be returned in @new_ino
  * on success, otherwise an error will be set to indicate the failure (e.g.
  * -ENOSPC).
  */
 int
 xfs_dialloc(
     struct xfs_trans    **tpp,
     xfs_ino_t       parent,
     umode_t         mode,
     xfs_ino_t       *new_ino)
 {
     struct xfs_mount    *mp = (*tpp)->t_mountp;
     xfs_agnumber_t      agno;
     int         error = 0;
     xfs_agnumber_t      start_agno;
     struct xfs_perag    *pag;
     struct xfs_ino_geometry *igeo = M_IGEO(mp);
     bool            ok_alloc = true;
     int         flags;
     xfs_ino_t       ino;
 
     /*
      * Directories, symlinks, and regular files frequently allocate at least
      * one block, so factor that potential expansion when we examine whether
      * an AG has enough space for file creation.
      */
     if (S_ISDIR(mode))
         start_agno = xfs_ialloc_next_ag(mp);
     else {
         start_agno = XFS_INO_TO_AGNO(mp, parent);
         if (start_agno >= mp->m_maxagi)
             start_agno = 0;
     }
 
     /*
      * If we have already hit the ceiling of inode blocks then clear
      * ok_alloc so we scan all available agi structures for a free
      * inode.
      *
      * Read rough value of mp->m_icount by percpu_counter_read_positive,
      * which will sacrifice the preciseness but improve the performance.
      */
     if (igeo->maxicount &&
         percpu_counter_read_positive(&mp->m_icount) + igeo->ialloc_inos
                             > igeo->maxicount) {
         ok_alloc = false;
     }
 
     /*
      * 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.
      */
     agno = start_agno;
     flags = XFS_ALLOC_FLAG_TRYLOCK;
     for (;;) {
         pag = xfs_perag_get(mp, agno);
         if (xfs_dialloc_good_ag(*tpp, pag, mode, flags, ok_alloc)) {
             error = xfs_dialloc_try_ag(tpp, pag, parent,
                     &ino, ok_alloc);
             if (error != -EAGAIN)
                 break;
         }
 
         if (xfs_is_shutdown(mp)) {
             error = -EFSCORRUPTED;
             break;
         }
         if (++agno == mp->m_maxagi)
             agno = 0;
         if (agno == start_agno) {
             if (!flags) {
                 error = -ENOSPC;
                 break;
             }
             flags = 0;
         }
         xfs_perag_put(pag);
     }
 
     if (!error)
         *new_ino = ino;
     xfs_perag_put(pag);
     return error;
 }
 
 /*
  * Free the blocks of an inode chunk. We must consider that the inode chunk
  * might be sparse and only free the regions that are allocated as part of the
  * chunk.
  */
 STATIC void
 xfs_difree_inode_chunk(
     struct xfs_trans        *tp,
     xfs_agnumber_t          agno,
     struct xfs_inobt_rec_incore *rec)
 {
     struct xfs_mount        *mp = tp->t_mountp;
     xfs_agblock_t           sagbno = XFS_AGINO_TO_AGBNO(mp,
                             rec->ir_startino);
     int             startidx, endidx;
     int             nextbit;
     xfs_agblock_t           agbno;
     int             contigblk;
     DECLARE_BITMAP(holemask, XFS_INOBT_HOLEMASK_BITS);
 
     if (!xfs_inobt_issparse(rec->ir_holemask)) {
         /* not sparse, calculate extent info directly */
         xfs_free_extent_later(tp, XFS_AGB_TO_FSB(mp, agno, sagbno),
                   M_IGEO(mp)->ialloc_blks,
                   &XFS_RMAP_OINFO_INODES);
         return;
     }
 
     /* holemask is only 16-bits (fits in an unsigned long) */
     ASSERT(sizeof(rec->ir_holemask) <= sizeof(holemask[0]));
     holemask[0] = rec->ir_holemask;
 
     /*
      * Find contiguous ranges of zeroes (i.e., allocated regions) in the
      * holemask and convert the start/end index of each range to an extent.
      * We start with the start and end index both pointing at the first 0 in
      * the mask.
      */
     startidx = endidx = find_first_zero_bit(holemask,
                         XFS_INOBT_HOLEMASK_BITS);
     nextbit = startidx + 1;
     while (startidx < XFS_INOBT_HOLEMASK_BITS) {
         nextbit = find_next_zero_bit(holemask, XFS_INOBT_HOLEMASK_BITS,
                          nextbit);
         /*
          * If the next zero bit is contiguous, update the end index of
          * the current range and continue.
          */
         if (nextbit != XFS_INOBT_HOLEMASK_BITS &&
             nextbit == endidx + 1) {
             endidx = nextbit;
             goto next;
         }
 
         /*
          * nextbit is not contiguous with the current end index. Convert
          * the current start/end to an extent and add it to the free
          * list.
          */
         agbno = sagbno + (startidx * XFS_INODES_PER_HOLEMASK_BIT) /
                   mp->m_sb.sb_inopblock;
         contigblk = ((endidx - startidx + 1) *
                  XFS_INODES_PER_HOLEMASK_BIT) /
                 mp->m_sb.sb_inopblock;
 
         ASSERT(agbno % mp->m_sb.sb_spino_align == 0);
         ASSERT(contigblk % mp->m_sb.sb_spino_align == 0);
         xfs_free_extent_later(tp, XFS_AGB_TO_FSB(mp, agno, agbno),
                   contigblk, &XFS_RMAP_OINFO_INODES);
 
         /* reset range to current bit and carry on... */
         startidx = endidx = nextbit;
 
 next:
         nextbit++;
     }
 }
 
 STATIC int
 xfs_difree_inobt(
     struct xfs_mount        *mp,
     struct xfs_trans        *tp,
     struct xfs_buf          *agbp,
     struct xfs_perag        *pag,
     xfs_agino_t         agino,
     struct xfs_icluster     *xic,
     struct xfs_inobt_rec_incore *orec)
 {
     struct xfs_agi          *agi = agbp->b_addr;
     struct xfs_btree_cur        *cur;
     struct xfs_inobt_rec_incore rec;
     int             ilen;
     int             error;
     int             i;
     int             off;
 
     ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));
     ASSERT(XFS_AGINO_TO_AGBNO(mp, agino) < be32_to_cpu(agi->agi_length));
 
     /*
      * Initialize the cursor.
      */
     cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
 
     error = xfs_check_agi_freecount(cur);
     if (error)
         goto error0;
 
     /*
      * Look for the entry describing this inode.
      */
     if ((error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &i))) {
         xfs_warn(mp, "%s: xfs_inobt_lookup() returned error %d.",
             __func__, error);
         goto error0;
     }
     if (XFS_IS_CORRUPT(mp, i != 1)) {
         error = -EFSCORRUPTED;
         goto error0;
     }
     error = xfs_inobt_get_rec(cur, &rec, &i);
     if (error) {
         xfs_warn(mp, "%s: xfs_inobt_get_rec() returned error %d.",
             __func__, error);
         goto error0;
     }
     if (XFS_IS_CORRUPT(mp, i != 1)) {
         error = -EFSCORRUPTED;
         goto error0;
     }
     /*
      * Get the offset in the inode chunk.
      */
     off = agino - rec.ir_startino;
     ASSERT(off >= 0 && off < XFS_INODES_PER_CHUNK);
     ASSERT(!(rec.ir_free & XFS_INOBT_MASK(off)));
     /*
      * Mark the inode free & increment the count.
      */
     rec.ir_free |= XFS_INOBT_MASK(off);
     rec.ir_freecount++;
 
     /*
      * When an inode chunk is free, it becomes eligible for removal. Don't
      * remove the chunk if the block size is large enough for multiple inode
      * chunks (that might not be free).
      */
     if (!xfs_has_ikeep(mp) && rec.ir_free == XFS_INOBT_ALL_FREE &&
         mp->m_sb.sb_inopblock <= XFS_INODES_PER_CHUNK) {
         struct xfs_perag    *pag = agbp->b_pag;
 
         xic->deleted = true;
         xic->first_ino = XFS_AGINO_TO_INO(mp, pag->pag_agno,
                 rec.ir_startino);
         xic->alloc = xfs_inobt_irec_to_allocmask(&rec);
 
         /*
          * 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 = rec.ir_freecount;
         be32_add_cpu(&agi->agi_count, -ilen);
         be32_add_cpu(&agi->agi_freecount, -(ilen - 1));
         xfs_ialloc_log_agi(tp, agbp, XFS_AGI_COUNT | XFS_AGI_FREECOUNT);
         pag->pagi_freecount -= ilen - 1;
         pag->pagi_count -= ilen;
         xfs_trans_mod_sb(tp, XFS_TRANS_SB_ICOUNT, -ilen);
         xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, -(ilen - 1));
 
         if ((error = xfs_btree_delete(cur, &i))) {
             xfs_warn(mp, "%s: xfs_btree_delete returned error %d.",
                 __func__, error);
             goto error0;
         }
 
         xfs_difree_inode_chunk(tp, pag->pag_agno, &rec);
     } else {
         xic->deleted = false;
 
         error = xfs_inobt_update(cur, &rec);
         if (error) {
             xfs_warn(mp, "%s: xfs_inobt_update returned error %d.",
                 __func__, error);
             goto error0;
         }
 
         /*
          * Change the inode free counts and log the ag/sb changes.
          */
         be32_add_cpu(&agi->agi_freecount, 1);
         xfs_ialloc_log_agi(tp, agbp, XFS_AGI_FREECOUNT);
         pag->pagi_freecount++;
         xfs_trans_mod_sb(tp, XFS_TRANS_SB_IFREE, 1);
     }
 
     error = xfs_check_agi_freecount(cur);
     if (error)
         goto error0;
 
     *orec = rec;
     xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
     return 0;
 
 error0:
     xfs_btree_del_cursor(cur, XFS_BTREE_ERROR);
     return error;
 }
 
 /*
  * Free an inode in the free inode btree.
  */
 STATIC int
 xfs_difree_finobt(
     struct xfs_mount        *mp,
     struct xfs_trans        *tp,
     struct xfs_buf          *agbp,
     struct xfs_perag        *pag,
     xfs_agino_t         agino,
     struct xfs_inobt_rec_incore *ibtrec) /* inobt record */
 {
     struct xfs_btree_cur        *cur;
     struct xfs_inobt_rec_incore rec;
     int             offset = agino - ibtrec->ir_startino;
     int             error;
     int             i;
 
     cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_FINO);
 
     error = xfs_inobt_lookup(cur, ibtrec->ir_startino, XFS_LOOKUP_EQ, &i);
     if (error)
         goto error;
     if (i == 0) {
         /*
          * If the record does not exist in the finobt, we must have just
          * freed an inode in a previously fully allocated chunk. If not,
          * something is out of sync.
          */
         if (XFS_IS_CORRUPT(mp, ibtrec->ir_freecount != 1)) {
             error = -EFSCORRUPTED;
             goto error;
         }
 
         error = xfs_inobt_insert_rec(cur, ibtrec->ir_holemask,
                          ibtrec->ir_count,
                          ibtrec->ir_freecount,
                          ibtrec->ir_free, &i);
         if (error)
             goto error;
         ASSERT(i == 1);
 
         goto out;
     }
 
     /*
      * Read and update the existing record. We could just copy the ibtrec
      * across here, but that would defeat the purpose of having redundant
      * metadata. By making the modifications independently, we can catch
      * corruptions that we wouldn't see if we just copied from one record
      * to another.
      */
     error = xfs_inobt_get_rec(cur, &rec, &i);
     if (error)
         goto error;
     if (XFS_IS_CORRUPT(mp, i != 1)) {
         error = -EFSCORRUPTED;
         goto error;
     }
 
     rec.ir_free |= XFS_INOBT_MASK(offset);
     rec.ir_freecount++;
 
     if (XFS_IS_CORRUPT(mp,
                rec.ir_free != ibtrec->ir_free ||
                rec.ir_freecount != ibtrec->ir_freecount)) {
         error = -EFSCORRUPTED;
         goto error;
     }
 
     /*
      * The content of inobt records should always match between the inobt
      * and finobt. The lifecycle of records in the finobt is different from
      * the inobt in that the finobt only tracks records with at least one
      * free inode. Hence, if all of the inodes are free and we aren't
      * keeping inode chunks permanently on disk, remove the record.
      * Otherwise, update the record with the new information.
      *
      * Note that we currently can't free chunks when the block size is large
      * enough for multiple chunks. Leave the finobt record to remain in sync
      * with the inobt.
      */
     if (!xfs_has_ikeep(mp) && rec.ir_free == XFS_INOBT_ALL_FREE &&
         mp->m_sb.sb_inopblock <= XFS_INODES_PER_CHUNK) {
         error = xfs_btree_delete(cur, &i);
         if (error)
             goto error;
         ASSERT(i == 1);
     } else {
         error = xfs_inobt_update(cur, &rec);
         if (error)
             goto error;
     }
 
 out:
     error = xfs_check_agi_freecount(cur);
     if (error)
         goto error;
 
     xfs_btree_del_cursor(cur, XFS_BTREE_NOERROR);
     return 0;
 
 error:
     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(
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     xfs_ino_t       inode,
     struct xfs_icluster *xic)
 {
     /* REFERENCED */
     xfs_agblock_t       agbno;  /* block number containing inode */
     struct xfs_buf      *agbp;  /* buffer for allocation group header */
     xfs_agino_t     agino;  /* allocation group inode number */
     int         error;  /* error return value */
     struct xfs_mount    *mp = tp->t_mountp;
     struct xfs_inobt_rec_incore rec;/* btree record */
 
     /*
      * Break up inode number into its components.
      */
     if (pag->pag_agno != XFS_INO_TO_AGNO(mp, inode)) {
         xfs_warn(mp, "%s: agno != pag->pag_agno (%d != %d).",
             __func__, XFS_INO_TO_AGNO(mp, inode), pag->pag_agno);
         ASSERT(0);
         return -EINVAL;
     }
     agino = XFS_INO_TO_AGINO(mp, inode);
     if (inode != XFS_AGINO_TO_INO(mp, pag->pag_agno, agino))  {
         xfs_warn(mp, "%s: inode != XFS_AGINO_TO_INO() (%llu != %llu).",
             __func__, (unsigned long long)inode,
             (unsigned long long)XFS_AGINO_TO_INO(mp, pag->pag_agno, agino));
         ASSERT(0);
         return -EINVAL;
     }
     agbno = XFS_AGINO_TO_AGBNO(mp, agino);
     if (agbno >= mp->m_sb.sb_agblocks)  {
         xfs_warn(mp, "%s: agbno >= mp->m_sb.sb_agblocks (%d >= %d).",
             __func__, agbno, mp->m_sb.sb_agblocks);
         ASSERT(0);
         return -EINVAL;
     }
     /*
      * Get the allocation group header.
      */
     error = xfs_ialloc_read_agi(pag, tp, &agbp);
     if (error) {
         xfs_warn(mp, "%s: xfs_ialloc_read_agi() returned error %d.",
             __func__, error);
         return error;
     }
 
     /*
      * Fix up the inode allocation btree.
      */
     error = xfs_difree_inobt(mp, tp, agbp, pag, agino, xic, &rec);
     if (error)
         goto error0;
 
     /*
      * Fix up the free inode btree.
      */
     if (xfs_has_finobt(mp)) {
         error = xfs_difree_finobt(mp, tp, agbp, pag, agino, &rec);
         if (error)
             goto error0;
     }
 
     return 0;
 
 error0:
     return error;
 }
 
 STATIC int
 xfs_imap_lookup(
     struct xfs_mount    *mp,
     struct xfs_trans    *tp,
     struct xfs_perag    *pag,
     xfs_agino_t     agino,
     xfs_agblock_t       agbno,
     xfs_agblock_t       *chunk_agbno,
     xfs_agblock_t       *offset_agbno,
     int         flags)
 {
     struct xfs_inobt_rec_incore rec;
     struct xfs_btree_cur    *cur;
     struct xfs_buf      *agbp;
     int         error;
     int         i;
 
     error = xfs_ialloc_read_agi(pag, tp, &agbp);
     if (error) {
         xfs_alert(mp,
             "%s: xfs_ialloc_read_agi() returned error %d, agno %d",
             __func__, error, pag->pag_agno);
         return error;
     }
 
     /*
      * Lookup the inode record for the given agino. If the record cannot be
      * found, then it's an invalid inode number and we should abort. Once
      * we have a record, we need to ensure it contains the inode number
      * we are looking up.
      */
     cur = xfs_inobt_init_cursor(mp, tp, agbp, pag, XFS_BTNUM_INO);
     error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &i);
     if (!error) {
         if (i)
             error = xfs_inobt_get_rec(cur, &rec, &i);
         if (!error && i == 0)
             error = -EINVAL;
     }
 
     xfs_trans_brelse(tp, agbp);
     xfs_btree_del_cursor(cur, error);
     if (error)
         return error;
 
     /* check that the returned record contains the required inode */
     if (rec.ir_startino > agino ||
         rec.ir_startino + M_IGEO(mp)->ialloc_inos <= agino)
         return -EINVAL;
 
     /* for untrusted inodes check it is allocated first */
     if ((flags & XFS_IGET_UNTRUSTED) &&
         (rec.ir_free & XFS_INOBT_MASK(agino - rec.ir_startino)))
         return -EINVAL;
 
     *chunk_agbno = XFS_AGINO_TO_AGBNO(mp, rec.ir_startino);
     *offset_agbno = agbno - *chunk_agbno;
     return 0;
 }
 
 /*
  * Return the location of the inode in imap, for mapping it into a buffer.
  */
 int
 xfs_imap(
     struct xfs_mount     *mp,   /* file system mount structure */
     struct xfs_trans     *tp,   /* transaction pointer */
     xfs_ino_t       ino,    /* inode to locate */
     struct xfs_imap     *imap,  /* location map structure */
     uint            flags)  /* flags for inode btree lookup */
 {
     xfs_agblock_t       agbno;  /* block number of inode in the alloc group */
     xfs_agino_t     agino;  /* inode number within alloc group */
     xfs_agblock_t       chunk_agbno;    /* first block in inode chunk */
     xfs_agblock_t       cluster_agbno;  /* first block in inode cluster */
     int         error;  /* error code */
     int         offset; /* index of inode in its buffer */
     xfs_agblock_t       offset_agbno;   /* blks from chunk start to inode */
     struct xfs_perag    *pag;
 
     ASSERT(ino != NULLFSINO);
 
     /*
      * Split up the inode number into its parts.
      */
     pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ino));
     agino = XFS_INO_TO_AGINO(mp, ino);
     agbno = XFS_AGINO_TO_AGBNO(mp, agino);
     if (!pag || agbno >= mp->m_sb.sb_agblocks ||
         ino != XFS_AGINO_TO_INO(mp, pag->pag_agno, agino)) {
         error = -EINVAL;
 #ifdef DEBUG
         /*
          * Don't output diagnostic information for untrusted inodes
          * as they can be invalid without implying corruption.
          */
         if (flags & XFS_IGET_UNTRUSTED)
             goto out_drop;
         if (!pag) {
             xfs_alert(mp,
                 "%s: agno (%d) >= mp->m_sb.sb_agcount (%d)",
                 __func__, XFS_INO_TO_AGNO(mp, ino),
                 mp->m_sb.sb_agcount);
         }
         if (agbno >= mp->m_sb.sb_agblocks) {
             xfs_alert(mp,
         "%s: agbno (0x%llx) >= mp->m_sb.sb_agblocks (0x%lx)",
                 __func__, (unsigned long long)agbno,
                 (unsigned long)mp->m_sb.sb_agblocks);
         }
         if (pag && ino != XFS_AGINO_TO_INO(mp, pag->pag_agno, agino)) {
             xfs_alert(mp,
         "%s: ino (0x%llx) != XFS_AGINO_TO_INO() (0x%llx)",
                 __func__, ino,
                 XFS_AGINO_TO_INO(mp, pag->pag_agno, agino));
         }
         xfs_stack_trace();
 #endif /* DEBUG */
         goto out_drop;
     }
 
     /*
      * For bulkstat and handle lookups, we have an untrusted inode number
      * that we have to verify is valid. We cannot do this just by reading
      * the inode buffer as it may have been unlinked and removed leaving
      * inodes in stale state on disk. Hence we have to do a btree lookup
      * in all cases where an untrusted inode number is passed.
      */
     if (flags & XFS_IGET_UNTRUSTED) {
         error = xfs_imap_lookup(mp, tp, pag, agino, agbno,
                     &chunk_agbno, &offset_agbno, flags);
         if (error)
             goto out_drop;
         goto out_map;
     }
 
     /*
      * If the inode cluster size is the same as the blocksize or
      * smaller we get to the buffer by simple arithmetics.
      */
     if (M_IGEO(mp)->blocks_per_cluster == 1) {
         offset = XFS_INO_TO_OFFSET(mp, ino);
         ASSERT(offset < mp->m_sb.sb_inopblock);
 
         imap->im_blkno = XFS_AGB_TO_DADDR(mp, pag->pag_agno, agbno);
         imap->im_len = XFS_FSB_TO_BB(mp, 1);
         imap->im_boffset = (unsigned short)(offset <<
                             mp->m_sb.sb_inodelog);
         error = 0;
         goto out_drop;
     }
 
     /*
      * If the inode chunks are aligned then use simple maths to
      * find the location. Otherwise we have to do a btree
      * lookup to find the location.
      */
     if (M_IGEO(mp)->inoalign_mask) {
         offset_agbno = agbno & M_IGEO(mp)->inoalign_mask;
         chunk_agbno = agbno - offset_agbno;
     } else {
         error = xfs_imap_lookup(mp, tp, pag, agino, agbno,
                     &chunk_agbno, &offset_agbno, flags);
         if (error)
             goto out_drop;
     }
 
 out_map:
     ASSERT(agbno >= chunk_agbno);
     cluster_agbno = chunk_agbno +
         ((offset_agbno / M_IGEO(mp)->blocks_per_cluster) *
          M_IGEO(mp)->blocks_per_cluster);
     offset = ((agbno - cluster_agbno) * mp->m_sb.sb_inopblock) +
         XFS_INO_TO_OFFSET(mp, ino);
 
     imap->im_blkno = XFS_AGB_TO_DADDR(mp, pag->pag_agno, cluster_agbno);
     imap->im_len = XFS_FSB_TO_BB(mp, M_IGEO(mp)->blocks_per_cluster);
     imap->im_boffset = (unsigned short)(offset << mp->m_sb.sb_inodelog);
 
     /*
      * If the inode number maps to a block outside the bounds
      * of the file system then return NULL rather than calling
      * read_buf and panicing when we get an error from the
      * driver.
      */
     if ((imap->im_blkno + imap->im_len) >
         XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks)) {
         xfs_alert(mp,
     "%s: (im_blkno (0x%llx) + im_len (0x%llx)) > sb_dblocks (0x%llx)",
             __func__, (unsigned long long) imap->im_blkno,
             (unsigned long long) imap->im_len,
             XFS_FSB_TO_BB(mp, mp->m_sb.sb_dblocks));
         error = -EINVAL;
         goto out_drop;
     }
     error = 0;
 out_drop:
     if (pag)
         xfs_perag_put(pag);
     return error;
 }
 
 /*
  * Log specified fields for the ag hdr (inode section). The growth of the agi
  * structure over time requires that we interpret the buffer as two logical
  * regions delineated by the end of the unlinked list. This is due to the size
  * of the hash table and its location in the middle of the agi.
  *
  * For example, a request to log a field before agi_unlinked and a field after
  * agi_unlinked could cause us to log the entire hash table and use an excessive
  * amount of log space. To avoid this behavior, log the region up through
  * agi_unlinked in one call and the region after agi_unlinked through the end of
  * the structure in another.
  */
 void
 xfs_ialloc_log_agi(
     struct xfs_trans    *tp,
     struct xfs_buf      *bp,
     uint32_t        fields)
 {
     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),
         offsetof(xfs_agi_t, agi_free_root),
         offsetof(xfs_agi_t, agi_free_level),
         offsetof(xfs_agi_t, agi_iblocks),
         sizeof(xfs_agi_t)
     };
 #ifdef DEBUG
     struct xfs_agi      *agi = bp->b_addr;
 
     ASSERT(agi->agi_magicnum == cpu_to_be32(XFS_AGI_MAGIC));
 #endif
 
     /*
      * Compute byte offsets for the first and last fields in the first
      * region and log the agi buffer. This only logs up through
      * agi_unlinked.
      */
     if (fields & XFS_AGI_ALL_BITS_R1) {
         xfs_btree_offsets(fields, offsets, XFS_AGI_NUM_BITS_R1,
                   &first, &last);
         xfs_trans_log_buf(tp, bp, first, last);
     }
 
     /*
      * Mask off the bits in the first region and calculate the first and
      * last field offsets for any bits in the second region.
      */
     fields &= ~XFS_AGI_ALL_BITS_R1;
     if (fields) {
         xfs_btree_offsets(fields, offsets, XFS_AGI_NUM_BITS_R2,
                   &first, &last);
         xfs_trans_log_buf(tp, bp, first, last);
     }
 }
 
 static xfs_failaddr_t
 xfs_agi_verify(
     struct xfs_buf  *bp)
 {
     struct xfs_mount *mp = bp->b_mount;
     struct xfs_agi  *agi = bp->b_addr;
     int     i;
 
     if (xfs_has_crc(mp)) {
         if (!uuid_equal(&agi->agi_uuid, &mp->m_sb.sb_meta_uuid))
             return __this_address;
         if (!xfs_log_check_lsn(mp, be64_to_cpu(agi->agi_lsn)))
             return __this_address;
     }
 
     /*
      * Validate the magic number of the agi block.
      */
     if (!xfs_verify_magic(bp, agi->agi_magicnum))
         return __this_address;
     if (!XFS_AGI_GOOD_VERSION(be32_to_cpu(agi->agi_versionnum)))
         return __this_address;
 
     if (be32_to_cpu(agi->agi_level) < 1 ||
         be32_to_cpu(agi->agi_level) > M_IGEO(mp)->inobt_maxlevels)
         return __this_address;
 
     if (xfs_has_finobt(mp) &&
         (be32_to_cpu(agi->agi_free_level) < 1 ||
          be32_to_cpu(agi->agi_free_level) > M_IGEO(mp)->inobt_maxlevels))
         return __this_address;
 
     /*
      * during growfs operations, the perag is not fully initialised,
      * so we can't use it for any useful checking. growfs ensures we can't
      * use it by using uncached buffers that don't have the perag attached
      * so we can detect and avoid this problem.
      */
     if (bp->b_pag && be32_to_cpu(agi->agi_seqno) != bp->b_pag->pag_agno)
         return __this_address;
 
     for (i = 0; i < XFS_AGI_UNLINKED_BUCKETS; i++) {
         if (agi->agi_unlinked[i] == cpu_to_be32(NULLAGINO))
             continue;
         if (!xfs_verify_ino(mp, be32_to_cpu(agi->agi_unlinked[i])))
             return __this_address;
     }
 
     return NULL;
 }
 
 static void
 xfs_agi_read_verify(
     struct xfs_buf  *bp)
 {
     struct xfs_mount *mp = bp->b_mount;
     xfs_failaddr_t  fa;
 
     if (xfs_has_crc(mp) &&
         !xfs_buf_verify_cksum(bp, XFS_AGI_CRC_OFF))
         xfs_verifier_error(bp, -EFSBADCRC, __this_address);
     else {
         fa = xfs_agi_verify(bp);
         if (XFS_TEST_ERROR(fa, mp, XFS_ERRTAG_IALLOC_READ_AGI))
             xfs_verifier_error(bp, -EFSCORRUPTED, fa);
     }
 }
 
 static void
 xfs_agi_write_verify(
     struct xfs_buf  *bp)
 {
     struct xfs_mount    *mp = bp->b_mount;
     struct xfs_buf_log_item *bip = bp->b_log_item;
     struct xfs_agi      *agi = bp->b_addr;
     xfs_failaddr_t      fa;
 
     fa = xfs_agi_verify(bp);
     if (fa) {
         xfs_verifier_error(bp, -EFSCORRUPTED, fa);
         return;
     }
 
     if (!xfs_has_crc(mp))
         return;
 
     if (bip)
         agi->agi_lsn = cpu_to_be64(bip->bli_item.li_lsn);
     xfs_buf_update_cksum(bp, XFS_AGI_CRC_OFF);
 }
 
 const struct xfs_buf_ops xfs_agi_buf_ops = {
     .name = "xfs_agi",
     .magic = { cpu_to_be32(XFS_AGI_MAGIC), cpu_to_be32(XFS_AGI_MAGIC) },
     .verify_read = xfs_agi_read_verify,
     .verify_write = xfs_agi_write_verify,
     .verify_struct = xfs_agi_verify,
 };
 
 /*
  * Read in the allocation group header (inode allocation section)
  */
 int
 xfs_read_agi(
     struct xfs_perag    *pag,
     struct xfs_trans    *tp,
     struct xfs_buf      **agibpp)
 {
     struct xfs_mount    *mp = pag->pag_mount;
     int         error;
 
     trace_xfs_read_agi(pag->pag_mount, pag->pag_agno);
 
     error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
             XFS_AG_DADDR(mp, pag->pag_agno, XFS_AGI_DADDR(mp)),
             XFS_FSS_TO_BB(mp, 1), 0, agibpp, &xfs_agi_buf_ops);
     if (error)
         return error;
     if (tp)
         xfs_trans_buf_set_type(tp, *agibpp, XFS_BLFT_AGI_BUF);
 
     xfs_buf_set_ref(*agibpp, XFS_AGI_REF);
     return 0;
 }
 
 /*
  * Read in the agi and initialise the per-ag data. If the caller supplies a
  * @agibpp, return the locked AGI buffer to them, otherwise release it.
  */
 int
 xfs_ialloc_read_agi(
     struct xfs_perag    *pag,
     struct xfs_trans    *tp,
     struct xfs_buf      **agibpp)
 {
     struct xfs_buf      *agibp;
     struct xfs_agi      *agi;
     int         error;
 
     trace_xfs_ialloc_read_agi(pag->pag_mount, pag->pag_agno);
 
     error = xfs_read_agi(pag, tp, &agibp);
     if (error)
         return error;
 
     agi = agibp->b_addr;
     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;
     }
 
     /*
      * 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_is_shutdown(pag->pag_mount));
     if (agibpp)
         *agibpp = agibp;
     else
         xfs_trans_brelse(tp, agibp);
     return 0;
 }
 
 /* Is there an inode record covering a given range of inode numbers? */
 int
 xfs_ialloc_has_inode_record(
     struct xfs_btree_cur    *cur,
     xfs_agino_t     low,
     xfs_agino_t     high,
     bool            *exists)
 {
     struct xfs_inobt_rec_incore irec;
     xfs_agino_t     agino;
     uint16_t        holemask;
     int         has_record;
     int         i;
     int         error;
 
     *exists = false;
     error = xfs_inobt_lookup(cur, low, XFS_LOOKUP_LE, &has_record);
     while (error == 0 && has_record) {
         error = xfs_inobt_get_rec(cur, &irec, &has_record);
         if (error || irec.ir_startino > high)
             break;
 
         agino = irec.ir_startino;
         holemask = irec.ir_holemask;
         for (i = 0; i < XFS_INOBT_HOLEMASK_BITS; holemask >>= 1,
                 i++, agino += XFS_INODES_PER_HOLEMASK_BIT) {
             if (holemask & 1)
                 continue;
             if (agino + XFS_INODES_PER_HOLEMASK_BIT > low &&
                     agino <= high) {
                 *exists = true;
                 return 0;
             }
         }
 
         error = xfs_btree_increment(cur, 0, &has_record);
     }
     return error;
 }
 
 /* Is there an inode record covering a given extent? */
 int
 xfs_ialloc_has_inodes_at_extent(
     struct xfs_btree_cur    *cur,
     xfs_agblock_t       bno,
     xfs_extlen_t        len,
     bool            *exists)
 {
     xfs_agino_t     low;
     xfs_agino_t     high;
 
     low = XFS_AGB_TO_AGINO(cur->bc_mp, bno);
     high = XFS_AGB_TO_AGINO(cur->bc_mp, bno + len) - 1;
 
     return xfs_ialloc_has_inode_record(cur, low, high, exists);
 }
 
 struct xfs_ialloc_count_inodes {
     xfs_agino_t         count;
     xfs_agino_t         freecount;
 };
 
 /* Record inode counts across all inobt records. */
 STATIC int
 xfs_ialloc_count_inodes_rec(
     struct xfs_btree_cur        *cur,
     const union xfs_btree_rec   *rec,
     void                *priv)
 {
     struct xfs_inobt_rec_incore irec;
     struct xfs_ialloc_count_inodes  *ci = priv;
 
     xfs_inobt_btrec_to_irec(cur->bc_mp, rec, &irec);
     ci->count += irec.ir_count;
     ci->freecount += irec.ir_freecount;
 
     return 0;
 }
 
 /* Count allocated and free inodes under an inobt. */
 int
 xfs_ialloc_count_inodes(
     struct xfs_btree_cur        *cur,
     xfs_agino_t         *count,
     xfs_agino_t         *freecount)
 {
     struct xfs_ialloc_count_inodes  ci = {0};
     int             error;
 
     ASSERT(cur->bc_btnum == XFS_BTNUM_INO);
     error = xfs_btree_query_all(cur, xfs_ialloc_count_inodes_rec, &ci);
     if (error)
         return error;
 
     *count = ci.count;
     *freecount = ci.freecount;
     return 0;
 }
 
 /*
  * Initialize inode-related geometry information.
  *
  * Compute the inode btree min and max levels and set maxicount.
  *
  * Set the inode cluster size.  This may still be overridden by the file
  * system block size if it is larger than the chosen cluster size.
  *
  * For v5 filesystems, scale the cluster size with the inode size to keep a
  * constant ratio of inode per cluster buffer, but only if mkfs has set the
  * inode alignment value appropriately for larger cluster sizes.
  *
  * Then compute the inode cluster alignment information.
  */
 void
 xfs_ialloc_setup_geometry(
     struct xfs_mount    *mp)
 {
     struct xfs_sb       *sbp = &mp->m_sb;
     struct xfs_ino_geometry *igeo = M_IGEO(mp);
     uint64_t        icount;
     uint            inodes;
 
     igeo->new_diflags2 = 0;
     if (xfs_has_bigtime(mp))
         igeo->new_diflags2 |= XFS_DIFLAG2_BIGTIME;
     if (xfs_has_large_extent_counts(mp))
         igeo->new_diflags2 |= XFS_DIFLAG2_NREXT64;
 
     /* Compute inode btree geometry. */
     igeo->agino_log = sbp->sb_inopblog + sbp->sb_agblklog;
     igeo->inobt_mxr[0] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 1);
     igeo->inobt_mxr[1] = xfs_inobt_maxrecs(mp, sbp->sb_blocksize, 0);
     igeo->inobt_mnr[0] = igeo->inobt_mxr[0] / 2;
     igeo->inobt_mnr[1] = igeo->inobt_mxr[1] / 2;
 
     igeo->ialloc_inos = max_t(uint16_t, XFS_INODES_PER_CHUNK,
             sbp->sb_inopblock);
     igeo->ialloc_blks = igeo->ialloc_inos >> sbp->sb_inopblog;
 
     if (sbp->sb_spino_align)
         igeo->ialloc_min_blks = sbp->sb_spino_align;
     else
         igeo->ialloc_min_blks = igeo->ialloc_blks;
 
     /* Compute and fill in value of m_ino_geo.inobt_maxlevels. */
     inodes = (1LL << XFS_INO_AGINO_BITS(mp)) >> XFS_INODES_PER_CHUNK_LOG;
     igeo->inobt_maxlevels = xfs_btree_compute_maxlevels(igeo->inobt_mnr,
             inodes);
     ASSERT(igeo->inobt_maxlevels <= xfs_iallocbt_maxlevels_ondisk());
 
     /*
      * Set the maximum inode count for this filesystem, being careful not
      * to use obviously garbage sb_inopblog/sb_inopblock values.  Regular
      * users should never get here due to failing sb verification, but
      * certain users (xfs_db) need to be usable even with corrupt metadata.
      */
     if (sbp->sb_imax_pct && igeo->ialloc_blks) {
         /*
          * Make sure the maximum inode count is a multiple
          * of the units we allocate inodes in.
          */
         icount = sbp->sb_dblocks * sbp->sb_imax_pct;
         do_div(icount, 100);
         do_div(icount, igeo->ialloc_blks);
         igeo->maxicount = XFS_FSB_TO_INO(mp,
                 icount * igeo->ialloc_blks);
     } else {
         igeo->maxicount = 0;
     }
 
     /*
      * Compute the desired size of an inode cluster buffer size, which
      * starts at 8K and (on v5 filesystems) scales up with larger inode
      * sizes.
      *
      * Preserve the desired inode cluster size because the sparse inodes
      * feature uses that desired size (not the actual size) to compute the
      * sparse inode alignment.  The mount code validates this value, so we
      * cannot change the behavior.
      */
     igeo->inode_cluster_size_raw = XFS_INODE_BIG_CLUSTER_SIZE;
     if (xfs_has_v3inodes(mp)) {
         int new_size = igeo->inode_cluster_size_raw;
 
         new_size *= mp->m_sb.sb_inodesize / XFS_DINODE_MIN_SIZE;
         if (mp->m_sb.sb_inoalignmt >= XFS_B_TO_FSBT(mp, new_size))
             igeo->inode_cluster_size_raw = new_size;
     }
 
     /* Calculate inode cluster ratios. */
     if (igeo->inode_cluster_size_raw > mp->m_sb.sb_blocksize)
         igeo->blocks_per_cluster = XFS_B_TO_FSBT(mp,
                 igeo->inode_cluster_size_raw);
     else
         igeo->blocks_per_cluster = 1;
     igeo->inode_cluster_size = XFS_FSB_TO_B(mp, igeo->blocks_per_cluster);
     igeo->inodes_per_cluster = XFS_FSB_TO_INO(mp, igeo->blocks_per_cluster);
 
     /* Calculate inode cluster alignment. */
     if (xfs_has_align(mp) &&
         mp->m_sb.sb_inoalignmt >= igeo->blocks_per_cluster)
         igeo->cluster_align = mp->m_sb.sb_inoalignmt;
     else
         igeo->cluster_align = 1;
     igeo->inoalign_mask = igeo->cluster_align - 1;
     igeo->cluster_align_inodes = XFS_FSB_TO_INO(mp, igeo->cluster_align);
 
     /*
      * If we are using stripe alignment, check whether
      * the stripe unit is a multiple of the inode alignment
      */
     if (mp->m_dalign && igeo->inoalign_mask &&
         !(mp->m_dalign & igeo->inoalign_mask))
         igeo->ialloc_align = mp->m_dalign;
     else
         igeo->ialloc_align = 0;
 }
 
 /* Compute the location of the root directory inode that is laid out by mkfs. */
 xfs_ino_t
 xfs_ialloc_calc_rootino(
     struct xfs_mount    *mp,
     int         sunit)
 {
     struct xfs_ino_geometry *igeo = M_IGEO(mp);
     xfs_agblock_t       first_bno;
 
     /*
      * Pre-calculate the geometry of AG 0.  We know what it looks like
      * because libxfs knows how to create allocation groups now.
      *
      * first_bno is the first block in which mkfs could possibly have
      * allocated the root directory inode, once we factor in the metadata
      * that mkfs formats before it.  Namely, the four AG headers...
      */
     first_bno = howmany(4 * mp->m_sb.sb_sectsize, mp->m_sb.sb_blocksize);
 
     /* ...the two free space btree roots... */
     first_bno += 2;
 
     /* ...the inode btree root... */
     first_bno += 1;
 
     /* ...the initial AGFL... */
     first_bno += xfs_alloc_min_freelist(mp, NULL);
 
     /* ...the free inode btree root... */
     if (xfs_has_finobt(mp))
         first_bno++;
 
     /* ...the reverse mapping btree root... */
     if (xfs_has_rmapbt(mp))
         first_bno++;
 
     /* ...the reference count btree... */
     if (xfs_has_reflink(mp))
         first_bno++;
 
     /*
      * ...and the log, if it is allocated in the first allocation group.
      *
      * This can happen with filesystems that only have a single
      * allocation group, or very odd geometries created by old mkfs
      * versions on very small filesystems.
      */
     if (xfs_ag_contains_log(mp, 0))
          first_bno += mp->m_sb.sb_logblocks;
 
     /*
      * Now round first_bno up to whatever allocation alignment is given
      * by the filesystem or was passed in.
      */
     if (xfs_has_dalign(mp) && igeo->ialloc_align > 0)
         first_bno = roundup(first_bno, sunit);
     else if (xfs_has_align(mp) &&
             mp->m_sb.sb_inoalignmt > 1)
         first_bno = roundup(first_bno, mp->m_sb.sb_inoalignmt);
 
     return XFS_AGINO_TO_INO(mp, 0, XFS_AGB_TO_AGINO(mp, first_bno));
 }
 
 /*
  * Ensure there are not sparse inode clusters that cross the new EOAG.
  *
  * This is a no-op for non-spinode filesystems since clusters are always fully
  * allocated and checking the bnobt suffices.  However, a spinode filesystem
  * could have a record where the upper inodes are free blocks.  If those blocks
  * were removed from the filesystem, the inode record would extend beyond EOAG,
  * which will be flagged as corruption.
  */
 int
 xfs_ialloc_check_shrink(
     struct xfs_trans    *tp,
     xfs_agnumber_t      agno,
     struct xfs_buf      *agibp,
     xfs_agblock_t       new_length)
 {
     struct xfs_inobt_rec_incore rec;
     struct xfs_btree_cur    *cur;
     struct xfs_mount    *mp = tp->t_mountp;
     struct xfs_perag    *pag;
     xfs_agino_t     agino = XFS_AGB_TO_AGINO(mp, new_length);
     int         has;
     int         error;
 
     if (!xfs_has_sparseinodes(mp))
         return 0;
 
     pag = xfs_perag_get(mp, agno);
     cur = xfs_inobt_init_cursor(mp, tp, agibp, pag, XFS_BTNUM_INO);
 
     /* Look up the inobt record that would correspond to the new EOFS. */
     error = xfs_inobt_lookup(cur, agino, XFS_LOOKUP_LE, &has);
     if (error || !has)
         goto out;
 
     error = xfs_inobt_get_rec(cur, &rec, &has);
     if (error)
         goto out;
 
     if (!has) {
         error = -EFSCORRUPTED;
         goto out;
     }
 
     /* If the record covers inodes that would be beyond EOFS, bail out. */
     if (rec.ir_startino + XFS_INODES_PER_CHUNK > agino) {
         error = -ENOSPC;
         goto out;
     }
 out:
     xfs_btree_del_cursor(cur, error);
     xfs_perag_put(pag);
     return error;
 }