ClabureDB: Classified Bug-Reports Database

   /*
    * Copyright (c) 2000-2005 Silicon Graphics, Inc.
    * All Rights Reserved.
    *
    * This program is free software; you can redistribute it and/or
    * modify it under the terms of the GNU General Public License as
    * published by the Free Software Foundation.
    *
    * This program is distributed in the hope that it would be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write the Free Software Foundation,
   * Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
   */
  #include "xfs.h"
  #include "xfs_fs.h"
  #include "xfs_types.h"
  #include "xfs_bit.h"
  #include "xfs_log.h"
  #include "xfs_inum.h"
  #include "xfs_trans.h"
  #include "xfs_sb.h"
  #include "xfs_ag.h"
  #include "xfs_dir2.h"
  #include "xfs_dmapi.h"
  #include "xfs_mount.h"
  #include "xfs_bmap_btree.h"
  #include "xfs_alloc_btree.h"
  #include "xfs_ialloc_btree.h"
  #include "xfs_dir2_sf.h"
  #include "xfs_attr_sf.h"
  #include "xfs_dinode.h"
  #include "xfs_inode.h"
  #include "xfs_btree.h"
  #include "xfs_ialloc.h"
  #include "xfs_alloc.h"
  #include "xfs_bmap.h"
  #include "xfs_rtalloc.h"
  #include "xfs_fsops.h"
  #include "xfs_error.h"
  #include "xfs_rw.h"
  #include "xfs_inode_item.h"
  #include "xfs_trans_space.h"
  #include "xfs_utils.h"
  
  
  /*
   * Prototypes for internal functions.
   */
  
  
  STATIC int xfs_rtallocate_range(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
                  xfs_extlen_t, xfs_buf_t **, xfs_fsblock_t *);
  STATIC int xfs_rtany_summary(xfs_mount_t *, xfs_trans_t *, int, int,
                  xfs_rtblock_t, xfs_buf_t **, xfs_fsblock_t *, int *);
  STATIC int xfs_rtcheck_range(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
                  xfs_extlen_t, int, xfs_rtblock_t *, int *);
  STATIC int xfs_rtfind_back(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
                  xfs_rtblock_t, xfs_rtblock_t *);
  STATIC int xfs_rtfind_forw(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
                  xfs_rtblock_t, xfs_rtblock_t *);
  STATIC int xfs_rtget_summary( xfs_mount_t *, xfs_trans_t *, int,
                  xfs_rtblock_t, xfs_buf_t **, xfs_fsblock_t *, xfs_suminfo_t *);
  STATIC int xfs_rtmodify_range(xfs_mount_t *, xfs_trans_t *, xfs_rtblock_t,
                  xfs_extlen_t, int);
  STATIC int xfs_rtmodify_summary(xfs_mount_t *, xfs_trans_t *, int,
                  xfs_rtblock_t, int, xfs_buf_t **, xfs_fsblock_t *);
  
  /*
   * Internal functions.
   */
  
  /*
   * Allocate space to the bitmap or summary file, and zero it, for growfs.
   */
  STATIC int                                /* error */
  xfs_growfs_rt_alloc(
          xfs_mount_t        *mp,                /* file system mount point */
          xfs_extlen_t        oblocks,        /* old count of blocks */
          xfs_extlen_t        nblocks,        /* new count of blocks */
          xfs_ino_t        ino)                /* inode number (bitmap/summary) */
  {
          xfs_fileoff_t        bno;                /* block number in file */
          xfs_buf_t        *bp;                /* temporary buffer for zeroing */
          int                cancelflags;        /* flags for xfs_trans_cancel */
          int                committed;        /* transaction committed flag */
          xfs_daddr_t        d;                /* disk block address */
          int                error;                /* error return value */
          xfs_fsblock_t        firstblock;        /* first block allocated in xaction */
          xfs_bmap_free_t        flist;                /* list of freed blocks */
          xfs_fsblock_t        fsbno;                /* filesystem block for bno */
          xfs_inode_t        *ip;                /* pointer to incore inode */
          xfs_bmbt_irec_t        map;                /* block map output */
          int                nmap;                /* number of block maps */
          int                resblks;        /* space reservation */
          xfs_trans_t        *tp;                /* transaction pointer */
 
         /*
          * Allocate space to the file, as necessary.
          */
         while (oblocks < nblocks) {
                 tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFSRT_ALLOC);
                 resblks = XFS_GROWFSRT_SPACE_RES(mp, nblocks - oblocks);
                 cancelflags = 0;
                 /*
                  * Reserve space & log for one extent added to the file.
                  */
                 if ((error = xfs_trans_reserve(tp, resblks,
                                 XFS_GROWRTALLOC_LOG_RES(mp), 0,
                                 XFS_TRANS_PERM_LOG_RES,
                                 XFS_DEFAULT_PERM_LOG_COUNT)))
                         goto error_cancel;
                 cancelflags = XFS_TRANS_RELEASE_LOG_RES;
                 /*
                  * Lock the inode.
                  */
                 if ((error = xfs_trans_iget(mp, tp, ino, 0,
                                                 XFS_ILOCK_EXCL, &ip)))
                         goto error_cancel;
                 XFS_BMAP_INIT(&flist, &firstblock);
                 /*
                  * Allocate blocks to the bitmap file.
                  */
                 nmap = 1;
                 cancelflags |= XFS_TRANS_ABORT;
                 error = xfs_bmapi(tp, ip, oblocks, nblocks - oblocks,
                         XFS_BMAPI_WRITE | XFS_BMAPI_METADATA, &firstblock,
                         resblks, &map, &nmap, &flist, NULL);
                 if (!error && nmap < 1)
                         error = XFS_ERROR(ENOSPC);
                 if (error)
                         goto error_cancel;
                 /*
                  * Free any blocks freed up in the transaction, then commit.
                  */
                 error = xfs_bmap_finish(&tp, &flist, &committed);
                 if (error)
                         goto error_cancel;
                 error = xfs_trans_commit(tp, XFS_TRANS_RELEASE_LOG_RES);
                 if (error)
                         goto error;
                 /*
                  * Now we need to clear the allocated blocks.
                  * Do this one block per transaction, to keep it simple.
                  */
                 cancelflags = 0;
                 for (bno = map.br_startoff, fsbno = map.br_startblock;
                      bno < map.br_startoff + map.br_blockcount;
                      bno++, fsbno++) {
                         tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFSRT_ZERO);
                         /*
                          * Reserve log for one block zeroing.
                          */
                         if ((error = xfs_trans_reserve(tp, 0,
                                         XFS_GROWRTZERO_LOG_RES(mp), 0, 0, 0)))
                                 goto error_cancel;
                         /*
                          * Lock the bitmap inode.
                          */
                         if ((error = xfs_trans_iget(mp, tp, ino, 0,
                                                         XFS_ILOCK_EXCL, &ip)))
                                 goto error_cancel;
                         /*
                          * Get a buffer for the block.
                          */
                         d = XFS_FSB_TO_DADDR(mp, fsbno);
                         bp = xfs_trans_get_buf(tp, mp->m_ddev_targp, d,
                                 mp->m_bsize, 0);
                         if (bp == NULL) {
                                 error = XFS_ERROR(EIO);
                                 goto error_cancel;
                         }
                         memset(XFS_BUF_PTR(bp), 0, mp->m_sb.sb_blocksize);
                         xfs_trans_log_buf(tp, bp, 0, mp->m_sb.sb_blocksize - 1);
                         /*
                          * Commit the transaction.
                          */
                         error = xfs_trans_commit(tp, 0);
                         if (error)
                                 goto error;
                 }
                 /*
                  * Go on to the next extent, if any.
                  */
                 oblocks = map.br_startoff + map.br_blockcount;
         }
         return 0;
 error_cancel:
         xfs_trans_cancel(tp, cancelflags);
 error:
         return error;
 }
 
 /*
  * Attempt to allocate an extent minlen<=len<=maxlen starting from
  * bitmap block bbno.  If we don't get maxlen then use prod to trim
  * the length, if given.  Returns error; returns starting block in *rtblock.
  * The lengths are all in rtextents.
  */
 STATIC int                                /* error */
 xfs_rtallocate_extent_block(
         xfs_mount_t        *mp,                /* file system mount point */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_rtblock_t        bbno,                /* bitmap block number */
         xfs_extlen_t        minlen,                /* minimum length to allocate */
         xfs_extlen_t        maxlen,                /* maximum length to allocate */
         xfs_extlen_t        *len,                /* out: actual length allocated */
         xfs_rtblock_t        *nextp,                /* out: next block to try */
         xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
         xfs_fsblock_t        *rsb,                /* in/out: summary block number */
         xfs_extlen_t        prod,                /* extent product factor */
         xfs_rtblock_t        *rtblock)        /* out: start block allocated */
 {
         xfs_rtblock_t        besti;                /* best rtblock found so far */
         xfs_rtblock_t        bestlen;        /* best length found so far */
         xfs_rtblock_t        end;                /* last rtblock in chunk */
         int                error;                /* error value */
         xfs_rtblock_t        i;                /* current rtblock trying */
         xfs_rtblock_t        next;                /* next rtblock to try */
         int                stat;                /* status from internal calls */
 
         /*
          * Loop over all the extents starting in this bitmap block,
          * looking for one that's long enough.
          */
         for (i = XFS_BLOCKTOBIT(mp, bbno), besti = -1, bestlen = 0,
                 end = XFS_BLOCKTOBIT(mp, bbno + 1) - 1;
              i <= end;
              i++) {
                 /*
                  * See if there's a free extent of maxlen starting at i.
                  * If it's not so then next will contain the first non-free.
                  */
                 error = xfs_rtcheck_range(mp, tp, i, maxlen, 1, &next, &stat);
                 if (error) {
                         return error;
                 }
                 if (stat) {
                         /*
                          * i for maxlen is all free, allocate and return that.
                          */
                         error = xfs_rtallocate_range(mp, tp, i, maxlen, rbpp,
                                 rsb);
                         if (error) {
                                 return error;
                         }
                         *len = maxlen;
                         *rtblock = i;
                         return 0;
                 }
                 /*
                  * In the case where we have a variable-sized allocation
                  * request, figure out how big this free piece is,
                  * and if it's big enough for the minimum, and the best
                  * so far, remember it.
                  */
                 if (minlen < maxlen) {
                         xfs_rtblock_t        thislen;        /* this extent size */
 
                         thislen = next - i;
                         if (thislen >= minlen && thislen > bestlen) {
                                 besti = i;
                                 bestlen = thislen;
                         }
                 }
                 /*
                  * If not done yet, find the start of the next free space.
                  */
                 if (next < end) {
                         error = xfs_rtfind_forw(mp, tp, next, end, &i);
                         if (error) {
                                 return error;
                         }
                 } else
                         break;
         }
         /*
          * Searched the whole thing & didn't find a maxlen free extent.
          */
         if (minlen < maxlen && besti != -1) {
                 xfs_extlen_t        p;        /* amount to trim length by */
 
                 /*
                  * If size should be a multiple of prod, make that so.
                  */
                 if (prod > 1 && (p = do_mod(bestlen, prod)))
                         bestlen -= p;
                 /*
                  * Allocate besti for bestlen & return that.
                  */
                 error = xfs_rtallocate_range(mp, tp, besti, bestlen, rbpp, rsb);
                 if (error) {
                         return error;
                 }
                 *len = bestlen;
                 *rtblock = besti;
                 return 0;
         }
         /*
          * Allocation failed.  Set *nextp to the next block to try.
          */
         *nextp = next;
         *rtblock = NULLRTBLOCK;
         return 0;
 }
 
 /*
  * Allocate an extent of length minlen<=len<=maxlen, starting at block
  * bno.  If we don't get maxlen then use prod to trim the length, if given.
  * Returns error; returns starting block in *rtblock.
  * The lengths are all in rtextents.
  */
 STATIC int                                /* error */
 xfs_rtallocate_extent_exact(
         xfs_mount_t        *mp,                /* file system mount point */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_rtblock_t        bno,                /* starting block number to allocate */
         xfs_extlen_t        minlen,                /* minimum length to allocate */
         xfs_extlen_t        maxlen,                /* maximum length to allocate */
         xfs_extlen_t        *len,                /* out: actual length allocated */
         xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
         xfs_fsblock_t        *rsb,                /* in/out: summary block number */
         xfs_extlen_t        prod,                /* extent product factor */
         xfs_rtblock_t        *rtblock)        /* out: start block allocated */
 {
         int                error;                /* error value */
         xfs_extlen_t        i;                /* extent length trimmed due to prod */
         int                isfree;                /* extent is free */
         xfs_rtblock_t        next;                /* next block to try (dummy) */
 
         ASSERT(minlen % prod == 0 && maxlen % prod == 0);
         /*
          * Check if the range in question (for maxlen) is free.
          */
         error = xfs_rtcheck_range(mp, tp, bno, maxlen, 1, &next, &isfree);
         if (error) {
                 return error;
         }
         if (isfree) {
                 /*
                  * If it is, allocate it and return success.
                  */
                 error = xfs_rtallocate_range(mp, tp, bno, maxlen, rbpp, rsb);
                 if (error) {
                         return error;
                 }
                 *len = maxlen;
                 *rtblock = bno;
                 return 0;
         }
         /*
          * If not, allocate what there is, if it's at least minlen.
          */
         maxlen = next - bno;
         if (maxlen < minlen) {
                 /*
                  * Failed, return failure status.
                  */
                 *rtblock = NULLRTBLOCK;
                 return 0;
         }
         /*
          * Trim off tail of extent, if prod is specified.
          */
         if (prod > 1 && (i = maxlen % prod)) {
                 maxlen -= i;
                 if (maxlen < minlen) {
                         /*
                          * Now we can't do it, return failure status.
                          */
                         *rtblock = NULLRTBLOCK;
                         return 0;
                 }
         }
         /*
          * Allocate what we can and return it.
          */
         error = xfs_rtallocate_range(mp, tp, bno, maxlen, rbpp, rsb);
         if (error) {
                 return error;
         }
         *len = maxlen;
         *rtblock = bno;
         return 0;
 }
 
 /*
  * Allocate an extent of length minlen<=len<=maxlen, starting as near
  * to bno as possible.  If we don't get maxlen then use prod to trim
  * the length, if given.  The lengths are all in rtextents.
  */
 STATIC int                                /* error */
 xfs_rtallocate_extent_near(
         xfs_mount_t        *mp,                /* file system mount point */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_rtblock_t        bno,                /* starting block number to allocate */
         xfs_extlen_t        minlen,                /* minimum length to allocate */
         xfs_extlen_t        maxlen,                /* maximum length to allocate */
         xfs_extlen_t        *len,                /* out: actual length allocated */
         xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
         xfs_fsblock_t        *rsb,                /* in/out: summary block number */
         xfs_extlen_t        prod,                /* extent product factor */
         xfs_rtblock_t        *rtblock)        /* out: start block allocated */
 {
         int                any;                /* any useful extents from summary */
         xfs_rtblock_t        bbno;                /* bitmap block number */
         int                error;                /* error value */
         int                i;                /* bitmap block offset (loop control) */
         int                j;                /* secondary loop control */
         int                log2len;        /* log2 of minlen */
         xfs_rtblock_t        n;                /* next block to try */
         xfs_rtblock_t        r;                /* result block */
 
         ASSERT(minlen % prod == 0 && maxlen % prod == 0);
         /*
          * If the block number given is off the end, silently set it to
          * the last block.
          */
         if (bno >= mp->m_sb.sb_rextents)
                 bno = mp->m_sb.sb_rextents - 1;
         /*
          * Try the exact allocation first.
          */
         error = xfs_rtallocate_extent_exact(mp, tp, bno, minlen, maxlen, len,
                 rbpp, rsb, prod, &r);
         if (error) {
                 return error;
         }
         /*
          * If the exact allocation worked, return that.
          */
         if (r != NULLRTBLOCK) {
                 *rtblock = r;
                 return 0;
         }
         bbno = XFS_BITTOBLOCK(mp, bno);
         i = 0;
         ASSERT(minlen != 0);
         log2len = xfs_highbit32(minlen);
         /*
          * Loop over all bitmap blocks (bbno + i is current block).
          */
         for (;;) {
                 /*
                  * Get summary information of extents of all useful levels
                  * starting in this bitmap block.
                  */
                 error = xfs_rtany_summary(mp, tp, log2len, mp->m_rsumlevels - 1,
                         bbno + i, rbpp, rsb, &any);
                 if (error) {
                         return error;
                 }
                 /*
                  * If there are any useful extents starting here, try
                  * allocating one.
                  */
                 if (any) {
                         /*
                          * On the positive side of the starting location.
                          */
                         if (i >= 0) {
                                 /*
                                  * Try to allocate an extent starting in
                                  * this block.
                                  */
                                 error = xfs_rtallocate_extent_block(mp, tp,
                                         bbno + i, minlen, maxlen, len, &n, rbpp,
                                         rsb, prod, &r);
                                 if (error) {
                                         return error;
                                 }
                                 /*
                                  * If it worked, return it.
                                  */
                                 if (r != NULLRTBLOCK) {
                                         *rtblock = r;
                                         return 0;
                                 }
                         }
                         /*
                          * On the negative side of the starting location.
                          */
                         else {                /* i < 0 */
                                 /*
                                  * Loop backwards through the bitmap blocks from
                                  * the starting point-1 up to where we are now.
                                  * There should be an extent which ends in this
                                  * bitmap block and is long enough.
                                  */
                                 for (j = -1; j > i; j--) {
                                         /*
                                          * Grab the summary information for
                                          * this bitmap block.
                                          */
                                         error = xfs_rtany_summary(mp, tp,
                                                 log2len, mp->m_rsumlevels - 1,
                                                 bbno + j, rbpp, rsb, &any);
                                         if (error) {
                                                 return error;
                                         }
                                         /*
                                          * If there's no extent given in the
                                          * summary that means the extent we
                                          * found must carry over from an
                                          * earlier block.  If there is an
                                          * extent given, we've already tried
                                          * that allocation, don't do it again.
                                          */
                                         if (any)
                                                 continue;
                                         error = xfs_rtallocate_extent_block(mp,
                                                 tp, bbno + j, minlen, maxlen,
                                                 len, &n, rbpp, rsb, prod, &r);
                                         if (error) {
                                                 return error;
                                         }
                                         /*
                                          * If it works, return the extent.
                                          */
                                         if (r != NULLRTBLOCK) {
                                                 *rtblock = r;
                                                 return 0;
                                         }
                                 }
                                 /*
                                  * There weren't intervening bitmap blocks
                                  * with a long enough extent, or the
                                  * allocation didn't work for some reason
                                  * (i.e. it's a little * too short).
                                  * Try to allocate from the summary block
                                  * that we found.
                                  */
                                 error = xfs_rtallocate_extent_block(mp, tp,
                                         bbno + i, minlen, maxlen, len, &n, rbpp,
                                         rsb, prod, &r);
                                 if (error) {
                                         return error;
                                 }
                                 /*
                                  * If it works, return the extent.
                                  */
                                 if (r != NULLRTBLOCK) {
                                         *rtblock = r;
                                         return 0;
                                 }
                         }
                 }
                 /*
                  * Loop control.  If we were on the positive side, and there's
                  * still more blocks on the negative side, go there.
                  */
                 if (i > 0 && (int)bbno - i >= 0)
                         i = -i;
                 /*
                  * If positive, and no more negative, but there are more
                  * positive, go there.
                  */
                 else if (i > 0 && (int)bbno + i < mp->m_sb.sb_rbmblocks - 1)
                         i++;
                 /*
                  * If negative or 0 (just started), and there are positive
                  * blocks to go, go there.  The 0 case moves to block 1.
                  */
                 else if (i <= 0 && (int)bbno - i < mp->m_sb.sb_rbmblocks - 1)
                         i = 1 - i;
                 /*
                  * If negative or 0 and there are more negative blocks,
                  * go there.
                  */
                 else if (i <= 0 && (int)bbno + i > 0)
                         i--;
                 /*
                  * Must be done.  Return failure.
                  */
                 else
                         break;
         }
         *rtblock = NULLRTBLOCK;
         return 0;
 }
 
 /*
  * Allocate an extent of length minlen<=len<=maxlen, with no position
  * specified.  If we don't get maxlen then use prod to trim
  * the length, if given.  The lengths are all in rtextents.
  */
 STATIC int                                /* error */
 xfs_rtallocate_extent_size(
         xfs_mount_t        *mp,                /* file system mount point */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_extlen_t        minlen,                /* minimum length to allocate */
         xfs_extlen_t        maxlen,                /* maximum length to allocate */
         xfs_extlen_t        *len,                /* out: actual length allocated */
         xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
         xfs_fsblock_t        *rsb,                /* in/out: summary block number */
         xfs_extlen_t        prod,                /* extent product factor */
         xfs_rtblock_t        *rtblock)        /* out: start block allocated */
 {
         int                error;                /* error value */
         int                i;                /* bitmap block number */
         int                l;                /* level number (loop control) */
         xfs_rtblock_t        n;                /* next block to be tried */
         xfs_rtblock_t        r;                /* result block number */
         xfs_suminfo_t        sum;                /* summary information for extents */
 
         ASSERT(minlen % prod == 0 && maxlen % prod == 0);
         ASSERT(maxlen != 0);
 
         /*
          * Loop over all the levels starting with maxlen.
          * At each level, look at all the bitmap blocks, to see if there
          * are extents starting there that are long enough (>= maxlen).
          * Note, only on the initial level can the allocation fail if
          * the summary says there's an extent.
          */
         for (l = xfs_highbit32(maxlen); l < mp->m_rsumlevels; l++) {
                 /*
                  * Loop over all the bitmap blocks.
                  */
                 for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
                         /*
                          * Get the summary for this level/block.
                          */
                         error = xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
                                 &sum);
                         if (error) {
                                 return error;
                         }
                         /*
                          * Nothing there, on to the next block.
                          */
                         if (!sum)
                                 continue;
                         /*
                          * Try allocating the extent.
                          */
                         error = xfs_rtallocate_extent_block(mp, tp, i, maxlen,
                                 maxlen, len, &n, rbpp, rsb, prod, &r);
                         if (error) {
                                 return error;
                         }
                         /*
                          * If it worked, return that.
                          */
                         if (r != NULLRTBLOCK) {
                                 *rtblock = r;
                                 return 0;
                         }
                         /*
                          * If the "next block to try" returned from the
                          * allocator is beyond the next bitmap block,
                          * skip to that bitmap block.
                          */
                         if (XFS_BITTOBLOCK(mp, n) > i + 1)
                                 i = XFS_BITTOBLOCK(mp, n) - 1;
                 }
         }
         /*
          * Didn't find any maxlen blocks.  Try smaller ones, unless
          * we're asking for a fixed size extent.
          */
         if (minlen > --maxlen) {
                 *rtblock = NULLRTBLOCK;
                 return 0;
         }
         ASSERT(minlen != 0);
         ASSERT(maxlen != 0);
 
         /*
          * Loop over sizes, from maxlen down to minlen.
          * This time, when we do the allocations, allow smaller ones
          * to succeed.
          */
         for (l = xfs_highbit32(maxlen); l >= xfs_highbit32(minlen); l--) {
                 /*
                  * Loop over all the bitmap blocks, try an allocation
                  * starting in that block.
                  */
                 for (i = 0; i < mp->m_sb.sb_rbmblocks; i++) {
                         /*
                          * Get the summary information for this level/block.
                          */
                         error =        xfs_rtget_summary(mp, tp, l, i, rbpp, rsb,
                                                   &sum);
                         if (error) {
                                 return error;
                         }
                         /*
                          * If nothing there, go on to next.
                          */
                         if (!sum)
                                 continue;
                         /*
                          * Try the allocation.  Make sure the specified
                          * minlen/maxlen are in the possible range for
                          * this summary level.
                          */
                         error = xfs_rtallocate_extent_block(mp, tp, i,
                                         XFS_RTMAX(minlen, 1 << l),
                                         XFS_RTMIN(maxlen, (1 << (l + 1)) - 1),
                                         len, &n, rbpp, rsb, prod, &r);
                         if (error) {
                                 return error;
                         }
                         /*
                          * If it worked, return that extent.
                          */
                         if (r != NULLRTBLOCK) {
                                 *rtblock = r;
                                 return 0;
                         }
                         /*
                          * If the "next block to try" returned from the
                          * allocator is beyond the next bitmap block,
                          * skip to that bitmap block.
                          */
                         if (XFS_BITTOBLOCK(mp, n) > i + 1)
                                 i = XFS_BITTOBLOCK(mp, n) - 1;
                 }
         }
         /*
          * Got nothing, return failure.
          */
         *rtblock = NULLRTBLOCK;
         return 0;
 }
 
 /*
  * Mark an extent specified by start and len allocated.
  * Updates all the summary information as well as the bitmap.
  */
 STATIC int                                /* error */
 xfs_rtallocate_range(
         xfs_mount_t        *mp,                /* file system mount point */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_rtblock_t        start,                /* start block to allocate */
         xfs_extlen_t        len,                /* length to allocate */
         xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
         xfs_fsblock_t        *rsb)                /* in/out: summary block number */
 {
         xfs_rtblock_t        end;                /* end of the allocated extent */
         int                error;                /* error value */
         xfs_rtblock_t        postblock;        /* first block allocated > end */
         xfs_rtblock_t        preblock;        /* first block allocated < start */
 
         end = start + len - 1;
         /*
          * Assume we're allocating out of the middle of a free extent.
          * We need to find the beginning and end of the extent so we can
          * properly update the summary.
          */
         error = xfs_rtfind_back(mp, tp, start, 0, &preblock);
         if (error) {
                 return error;
         }
         /*
          * Find the next allocated block (end of free extent).
          */
         error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
                 &postblock);
         if (error) {
                 return error;
         }
         /*
          * Decrement the summary information corresponding to the entire
          * (old) free extent.
          */
         error = xfs_rtmodify_summary(mp, tp,
                 XFS_RTBLOCKLOG(postblock + 1 - preblock),
                 XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
         if (error) {
                 return error;
         }
         /*
          * If there are blocks not being allocated at the front of the
          * old extent, add summary data for them to be free.
          */
         if (preblock < start) {
                 error = xfs_rtmodify_summary(mp, tp,
                         XFS_RTBLOCKLOG(start - preblock),
                         XFS_BITTOBLOCK(mp, preblock), 1, rbpp, rsb);
                 if (error) {
                         return error;
                 }
         }
         /*
          * If there are blocks not being allocated at the end of the
          * old extent, add summary data for them to be free.
          */
         if (postblock > end) {
                 error = xfs_rtmodify_summary(mp, tp,
                         XFS_RTBLOCKLOG(postblock - end),
                         XFS_BITTOBLOCK(mp, end + 1), 1, rbpp, rsb);
                 if (error) {
                         return error;
                 }
         }
         /*
          * Modify the bitmap to mark this extent allocated.
          */
         error = xfs_rtmodify_range(mp, tp, start, len, 0);
         return error;
 }
 
 /*
  * Return whether there are any free extents in the size range given
  * by low and high, for the bitmap block bbno.
  */
 STATIC int                                /* error */
 xfs_rtany_summary(
         xfs_mount_t        *mp,                /* file system mount structure */
         xfs_trans_t        *tp,                /* transaction pointer */
         int                low,                /* low log2 extent size */
         int                high,                /* high log2 extent size */
         xfs_rtblock_t        bbno,                /* bitmap block number */
         xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
         xfs_fsblock_t        *rsb,                /* in/out: summary block number */
         int                *stat)                /* out: any good extents here? */
 {
         int                error;                /* error value */
         int                log;                /* loop counter, log2 of ext. size */
         xfs_suminfo_t        sum;                /* summary data */
 
         /*
          * Loop over logs of extent sizes.  Order is irrelevant.
          */
         for (log = low; log <= high; log++) {
                 /*
                  * Get one summary datum.
                  */
                 error = xfs_rtget_summary(mp, tp, log, bbno, rbpp, rsb, &sum);
                 if (error) {
                         return error;
                 }
                 /*
                  * If there are any, return success.
                  */
                 if (sum) {
                         *stat = 1;
                         return 0;
                 }
         }
         /*
          * Found nothing, return failure.
          */
         *stat = 0;
         return 0;
 }
 
 /*
  * Get a buffer for the bitmap or summary file block specified.
  * The buffer is returned read and locked.
  */
 STATIC int                                /* error */
 xfs_rtbuf_get(
         xfs_mount_t        *mp,                /* file system mount structure */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_rtblock_t        block,                /* block number in bitmap or summary */
         int                issum,                /* is summary not bitmap */
         xfs_buf_t        **bpp)                /* output: buffer for the block */
 {
         xfs_buf_t        *bp;                /* block buffer, result */
         xfs_daddr_t        d;                /* disk addr of block */
         int                error;                /* error value */
         xfs_fsblock_t        fsb;                /* fs block number for block */
         xfs_inode_t        *ip;                /* bitmap or summary inode */
 
         ip = issum ? mp->m_rsumip : mp->m_rbmip;
         /*
          * Map from the file offset (block) and inode number to the
          * file system block.
          */
         error = xfs_bmapi_single(tp, ip, XFS_DATA_FORK, &fsb, block);
         if (error) {
                 return error;
         }
         ASSERT(fsb != NULLFSBLOCK);
         /*
          * Convert to disk address for buffer cache.
          */
         d = XFS_FSB_TO_DADDR(mp, fsb);
         /*
          * Read the buffer.
          */
         error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp, d,
                                    mp->m_bsize, 0, &bp);
         if (error) {
                 return error;
         }
         ASSERT(bp && !XFS_BUF_GETERROR(bp));
         *bpp = bp;
         return 0;
 }
 
 #ifdef DEBUG
 /*
  * Check that the given extent (block range) is allocated already.
  */
 STATIC int                                /* error */
 xfs_rtcheck_alloc_range(
         xfs_mount_t        *mp,                /* file system mount point */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_rtblock_t        bno,                /* starting block number of extent */
         xfs_extlen_t        len,                /* length of extent */
         int                *stat)                /* out: 1 for allocated, 0 for not */
 {
         xfs_rtblock_t        new;                /* dummy for xfs_rtcheck_range */
 
         return xfs_rtcheck_range(mp, tp, bno, len, 0, &new, stat);
 }
 #endif
 
 /*
  * Check that the given range is either all allocated (val = 0) or
  * all free (val = 1).
  */
 STATIC int                                /* error */
 xfs_rtcheck_range(
         xfs_mount_t        *mp,                /* file system mount point */
         xfs_trans_t        *tp,                /* transaction pointer */
         xfs_rtblock_t        start,                /* starting block number of extent */
         xfs_extlen_t        len,                /* length of extent */
         int                val,                /* 1 for free, 0 for allocated */
         xfs_rtblock_t        *new,                /* out: first block not matching */
         int                *stat)                /* out: 1 for matches, 0 for not */
 {
         xfs_rtword_t        *b;                /* current word in buffer */
         int                bit;                /* bit number in the word */
         xfs_rtblock_t        block;                /* bitmap block number */
         xfs_buf_t        *bp;                /* buf for the block */
         xfs_rtword_t        *bufp;                /* starting word in buffer */
         int                error;                /* error value */
         xfs_rtblock_t        i;                /* current bit number rel. to start */
         xfs_rtblock_t        lastbit;        /* last useful bit in word */
         xfs_rtword_t        mask;                /* mask of relevant bits for value */
         xfs_rtword_t        wdiff;                /* difference from wanted value */
         int                word;                /* word number in the buffer */
 
         /*
          * Compute starting bitmap block number
          */
         block = XFS_BITTOBLOCK(mp, start);
         /*
          * Read the bitmap block.
          */
         error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
         if (error) {
                 return error;
         }
         bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
         /*
          * Compute the starting word's address, and starting bit.
          */
         word = XFS_BITTOWORD(mp, start);
         b = &bufp[word];
         bit = (int)(start & (XFS_NBWORD - 1));
         /*
          * 0 (allocated) => all zero's; 1 (free) => all one's.
          */
         val = -val;
         /*
          * If not starting on a word boundary, deal with the first
          * (partial) word.
          */
         if (bit) {
                 /*
                  * Compute first bit not examined.
                  */
                 lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
                 /*
                  * Mask of relevant bits.
                  */
                 mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
                 /*
                  * Compute difference between actual and desired value.
                  */
                 if ((wdiff = (*b ^ val) & mask)) {
                         /*
                          * Different, compute first wrong bit and return.
                          */
                         xfs_trans_brelse(tp, bp);
                         i = XFS_RTLOBIT(wdiff) - bit;
                         *new = start + i;
                         *stat = 0;
                         return 0;
                 }
                 i = lastbit - bit;
                 /*
                  * Go on to next block if that's where the next word is
                  * and we need the next word.
                  */
                 if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
                         /*
                          * If done with this block, get the next one.
                          */
                         xfs_trans_brelse(tp, bp);
                        error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        b = bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = 0;
                } else {
                        /*
                         * Go on to the next word in the buffer.
                         */
                        b++;
                }
        } else {
                /*
                 * Starting on a word boundary, no partial word.
                 */
                i = 0;
        }
        /*
         * Loop over whole words in buffers.  When we use up one buffer
         * we move on to the next one.
         */
        while (len - i >= XFS_NBWORD) {
                /*
                 * Compute difference between actual and desired value.
                 */
                if ((wdiff = *b ^ val)) {
                        /*
                         * Different, compute first wrong bit and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i += XFS_RTLOBIT(wdiff);
                        *new = start + i;
                        *stat = 0;
                        return 0;
                }
                i += XFS_NBWORD;
                /*
                 * Go on to next block if that's where the next word is
                 * and we need the next word.
                 */
                if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
                        /*
                         * If done with this block, get the next one.
                         */
                        xfs_trans_brelse(tp, bp);
                        error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        b = bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = 0;
                } else {
                        /*
                         * Go on to the next word in the buffer.
                         */
                        b++;
                }
        }
        /*
         * If not ending on a word boundary, deal with the last
         * (partial) word.
         */
        if ((lastbit = len - i)) {
                /*
                 * Mask of relevant bits.
                 */
                mask = ((xfs_rtword_t)1 << lastbit) - 1;
                /*
                 * Compute difference between actual and desired value.
                 */
                if ((wdiff = (*b ^ val) & mask)) {
                        /*
                         * Different, compute first wrong bit and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i += XFS_RTLOBIT(wdiff);
                        *new = start + i;
                        *stat = 0;
                        return 0;
                } else
                        i = len;
        }
        /*
         * Successful, return.
         */
        xfs_trans_brelse(tp, bp);
        *new = start + i;
        *stat = 1;
        return 0;
}

/*
 * Copy and transform the summary file, given the old and new
 * parameters in the mount structures.
 */
STATIC int                                /* error */
xfs_rtcopy_summary(
        xfs_mount_t        *omp,                /* old file system mount point */
        xfs_mount_t        *nmp,                /* new file system mount point */
        xfs_trans_t        *tp)                /* transaction pointer */
{
        xfs_rtblock_t        bbno;                /* bitmap block number */
        xfs_buf_t        *bp;                /* summary buffer */
        int                error;                /* error return value */
        int                log;                /* summary level number (log length) */
        xfs_suminfo_t        sum;                /* summary data */
        xfs_fsblock_t        sumbno;                /* summary block number */

        bp = NULL;
        for (log = omp->m_rsumlevels - 1; log >= 0; log--) {
                for (bbno = omp->m_sb.sb_rbmblocks - 1;
                     (xfs_srtblock_t)bbno >= 0;
                     bbno--) {
                        error = xfs_rtget_summary(omp, tp, log, bbno, &bp,
                                &sumbno, &sum);
                        if (error)
                                return error;
                        if (sum == 0)
                                continue;
                        error = xfs_rtmodify_summary(omp, tp, log, bbno, -sum,
                                &bp, &sumbno);
                        if (error)
                                return error;
                        error = xfs_rtmodify_summary(nmp, tp, log, bbno, sum,
                                &bp, &sumbno);
                        if (error)
                                return error;
                        ASSERT(sum > 0);
                }
        }
        return 0;
}

/*
 * Searching backward from start to limit, find the first block whose
 * allocated/free state is different from start's.
 */
STATIC int                                /* error */
xfs_rtfind_back(
        xfs_mount_t        *mp,                /* file system mount point */
        xfs_trans_t        *tp,                /* transaction pointer */
        xfs_rtblock_t        start,                /* starting block to look at */
        xfs_rtblock_t        limit,                /* last block to look at */
        xfs_rtblock_t        *rtblock)        /* out: start block found */
{
        xfs_rtword_t        *b;                /* current word in buffer */
        int                bit;                /* bit number in the word */
        xfs_rtblock_t        block;                /* bitmap block number */
        xfs_buf_t        *bp;                /* buf for the block */
        xfs_rtword_t        *bufp;                /* starting word in buffer */
        int                error;                /* error value */
        xfs_rtblock_t        firstbit;        /* first useful bit in the word */
        xfs_rtblock_t        i;                /* current bit number rel. to start */
        xfs_rtblock_t        len;                /* length of inspected area */
        xfs_rtword_t        mask;                /* mask of relevant bits for value */
        xfs_rtword_t        want;                /* mask for "good" values */
        xfs_rtword_t        wdiff;                /* difference from wanted value */
        int                word;                /* word number in the buffer */

        /*
         * Compute and read in starting bitmap block for starting block.
         */
        block = XFS_BITTOBLOCK(mp, start);
        error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
        if (error) {
                return error;
        }
        bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
        /*
         * Get the first word's index & point to it.
         */
        word = XFS_BITTOWORD(mp, start);
        b = &bufp[word];
        bit = (int)(start & (XFS_NBWORD - 1));
        len = start - limit + 1;
        /*
         * Compute match value, based on the bit at start: if 1 (free)
         * then all-ones, else all-zeroes.
         */
        want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
        /*
         * If the starting position is not word-aligned, deal with the
         * partial word.
         */
        if (bit < XFS_NBWORD - 1) {
                /*
                 * Calculate first (leftmost) bit number to look at,
                 * and mask for all the relevant bits in this word.
                 */
                firstbit = XFS_RTMAX((xfs_srtblock_t)(bit - len + 1), 0);
                mask = (((xfs_rtword_t)1 << (bit - firstbit + 1)) - 1) <<
                        firstbit;
                /*
                 * Calculate the difference between the value there
                 * and what we're looking for.
                 */
                if ((wdiff = (*b ^ want) & mask)) {
                        /*
                         * Different.  Mark where we are and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i = bit - XFS_RTHIBIT(wdiff);
                        *rtblock = start - i + 1;
                        return 0;
                }
                i = bit - firstbit + 1;
                /*
                 * Go on to previous block if that's where the previous word is
                 * and we need the previous word.
                 */
                if (--word == -1 && i < len) {
                        /*
                         * If done with this block, get the previous one.
                         */
                        xfs_trans_brelse(tp, bp);
                        error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = XFS_BLOCKWMASK(mp);
                        b = &bufp[word];
                } else {
                        /*
                         * Go on to the previous word in the buffer.
                         */
                        b--;
                }
        } else {
                /*
                 * Starting on a word boundary, no partial word.
                 */
                i = 0;
        }
        /*
         * Loop over whole words in buffers.  When we use up one buffer
         * we move on to the previous one.
         */
        while (len - i >= XFS_NBWORD) {
                /*
                 * Compute difference between actual and desired value.
                 */
                if ((wdiff = *b ^ want)) {
                        /*
                         * Different, mark where we are and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
                        *rtblock = start - i + 1;
                        return 0;
                }
                i += XFS_NBWORD;
                /*
                 * Go on to previous block if that's where the previous word is
                 * and we need the previous word.
                 */
                if (--word == -1 && i < len) {
                        /*
                         * If done with this block, get the previous one.
                         */
                        xfs_trans_brelse(tp, bp);
                        error = xfs_rtbuf_get(mp, tp, --block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = XFS_BLOCKWMASK(mp);
                        b = &bufp[word];
                } else {
                        /*
                         * Go on to the previous word in the buffer.
                         */
                        b--;
                }
        }
        /*
         * If not ending on a word boundary, deal with the last
         * (partial) word.
         */
        if (len - i) {
                /*
                 * Calculate first (leftmost) bit number to look at,
                 * and mask for all the relevant bits in this word.
                 */
                firstbit = XFS_NBWORD - (len - i);
                mask = (((xfs_rtword_t)1 << (len - i)) - 1) << firstbit;
                /*
                 * Compute difference between actual and desired value.
                 */
                if ((wdiff = (*b ^ want) & mask)) {
                        /*
                         * Different, mark where we are and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i += XFS_NBWORD - 1 - XFS_RTHIBIT(wdiff);
                        *rtblock = start - i + 1;
                        return 0;
                } else
                        i = len;
        }
        /*
         * No match, return that we scanned the whole area.
         */
        xfs_trans_brelse(tp, bp);
        *rtblock = start - i + 1;
        return 0;
}

/*
 * Searching forward from start to limit, find the first block whose
 * allocated/free state is different from start's.
 */
STATIC int                                /* error */
xfs_rtfind_forw(
        xfs_mount_t        *mp,                /* file system mount point */
        xfs_trans_t        *tp,                /* transaction pointer */
        xfs_rtblock_t        start,                /* starting block to look at */
        xfs_rtblock_t        limit,                /* last block to look at */
        xfs_rtblock_t        *rtblock)        /* out: start block found */
{
        xfs_rtword_t        *b;                /* current word in buffer */
        int                bit;                /* bit number in the word */
        xfs_rtblock_t        block;                /* bitmap block number */
        xfs_buf_t        *bp;                /* buf for the block */
        xfs_rtword_t        *bufp;                /* starting word in buffer */
        int                error;                /* error value */
        xfs_rtblock_t        i;                /* current bit number rel. to start */
        xfs_rtblock_t        lastbit;        /* last useful bit in the word */
        xfs_rtblock_t        len;                /* length of inspected area */
        xfs_rtword_t        mask;                /* mask of relevant bits for value */
        xfs_rtword_t        want;                /* mask for "good" values */
        xfs_rtword_t        wdiff;                /* difference from wanted value */
        int                word;                /* word number in the buffer */

        /*
         * Compute and read in starting bitmap block for starting block.
         */
        block = XFS_BITTOBLOCK(mp, start);
        error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
        if (error) {
                return error;
        }
        bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
        /*
         * Get the first word's index & point to it.
         */
        word = XFS_BITTOWORD(mp, start);
        b = &bufp[word];
        bit = (int)(start & (XFS_NBWORD - 1));
        len = limit - start + 1;
        /*
         * Compute match value, based on the bit at start: if 1 (free)
         * then all-ones, else all-zeroes.
         */
        want = (*b & ((xfs_rtword_t)1 << bit)) ? -1 : 0;
        /*
         * If the starting position is not word-aligned, deal with the
         * partial word.
         */
        if (bit) {
                /*
                 * Calculate last (rightmost) bit number to look at,
                 * and mask for all the relevant bits in this word.
                 */
                lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
                mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
                /*
                 * Calculate the difference between the value there
                 * and what we're looking for.
                 */
                if ((wdiff = (*b ^ want) & mask)) {
                        /*
                         * Different.  Mark where we are and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i = XFS_RTLOBIT(wdiff) - bit;
                        *rtblock = start + i - 1;
                        return 0;
                }
                i = lastbit - bit;
                /*
                 * Go on to next block if that's where the next word is
                 * and we need the next word.
                 */
                if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
                        /*
                         * If done with this block, get the previous one.
                         */
                        xfs_trans_brelse(tp, bp);
                        error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        b = bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = 0;
                } else {
                        /*
                         * Go on to the previous word in the buffer.
                         */
                        b++;
                }
        } else {
                /*
                 * Starting on a word boundary, no partial word.
                 */
                i = 0;
        }
        /*
         * Loop over whole words in buffers.  When we use up one buffer
         * we move on to the next one.
         */
        while (len - i >= XFS_NBWORD) {
                /*
                 * Compute difference between actual and desired value.
                 */
                if ((wdiff = *b ^ want)) {
                        /*
                         * Different, mark where we are and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i += XFS_RTLOBIT(wdiff);
                        *rtblock = start + i - 1;
                        return 0;
                }
                i += XFS_NBWORD;
                /*
                 * Go on to next block if that's where the next word is
                 * and we need the next word.
                 */
                if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
                        /*
                         * If done with this block, get the next one.
                         */
                        xfs_trans_brelse(tp, bp);
                        error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        b = bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = 0;
                } else {
                        /*
                         * Go on to the next word in the buffer.
                         */
                        b++;
                }
        }
        /*
         * If not ending on a word boundary, deal with the last
         * (partial) word.
         */
        if ((lastbit = len - i)) {
                /*
                 * Calculate mask for all the relevant bits in this word.
                 */
                mask = ((xfs_rtword_t)1 << lastbit) - 1;
                /*
                 * Compute difference between actual and desired value.
                 */
                if ((wdiff = (*b ^ want) & mask)) {
                        /*
                         * Different, mark where we are and return.
                         */
                        xfs_trans_brelse(tp, bp);
                        i += XFS_RTLOBIT(wdiff);
                        *rtblock = start + i - 1;
                        return 0;
                } else
                        i = len;
        }
        /*
         * No match, return that we scanned the whole area.
         */
        xfs_trans_brelse(tp, bp);
        *rtblock = start + i - 1;
        return 0;
}

/*
 * Mark an extent specified by start and len freed.
 * Updates all the summary information as well as the bitmap.
 */
STATIC int                                /* error */
xfs_rtfree_range(
        xfs_mount_t        *mp,                /* file system mount point */
        xfs_trans_t        *tp,                /* transaction pointer */
        xfs_rtblock_t        start,                /* starting block to free */
        xfs_extlen_t        len,                /* length to free */
        xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
        xfs_fsblock_t        *rsb)                /* in/out: summary block number */
{
        xfs_rtblock_t        end;                /* end of the freed extent */
        int                error;                /* error value */
        xfs_rtblock_t        postblock;        /* first block freed > end */
        xfs_rtblock_t        preblock;        /* first block freed < start */

        end = start + len - 1;
        /*
         * Modify the bitmap to mark this extent freed.
         */
        error = xfs_rtmodify_range(mp, tp, start, len, 1);
        if (error) {
                return error;
        }
        /*
         * Assume we're freeing out of the middle of an allocated extent.
         * We need to find the beginning and end of the extent so we can
         * properly update the summary.
         */
        error = xfs_rtfind_back(mp, tp, start, 0, &preblock);
        if (error) {
                return error;
        }
        /*
         * Find the next allocated block (end of allocated extent).
         */
        error = xfs_rtfind_forw(mp, tp, end, mp->m_sb.sb_rextents - 1,
                &postblock);
        /*
         * If there are blocks not being freed at the front of the
         * old extent, add summary data for them to be allocated.
         */
        if (preblock < start) {
                error = xfs_rtmodify_summary(mp, tp,
                        XFS_RTBLOCKLOG(start - preblock),
                        XFS_BITTOBLOCK(mp, preblock), -1, rbpp, rsb);
                if (error) {
                        return error;
                }
        }
        /*
         * If there are blocks not being freed at the end of the
         * old extent, add summary data for them to be allocated.
         */
        if (postblock > end) {
                error = xfs_rtmodify_summary(mp, tp,
                        XFS_RTBLOCKLOG(postblock - end),
                        XFS_BITTOBLOCK(mp, end + 1), -1, rbpp, rsb);
                if (error) {
                        return error;
                }
        }
        /*
         * Increment the summary information corresponding to the entire
         * (new) free extent.
         */
        error = xfs_rtmodify_summary(mp, tp,
                XFS_RTBLOCKLOG(postblock + 1 - preblock),
                XFS_BITTOBLOCK(mp, preblock), 1, rbpp, rsb);
        return error;
}

/*
 * Read and return the summary information for a given extent size,
 * bitmap block combination.
 * Keeps track of a current summary block, so we don't keep reading
 * it from the buffer cache.
 */
STATIC int                                /* error */
xfs_rtget_summary(
        xfs_mount_t        *mp,                /* file system mount structure */
        xfs_trans_t        *tp,                /* transaction pointer */
        int                log,                /* log2 of extent size */
        xfs_rtblock_t        bbno,                /* bitmap block number */
        xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
        xfs_fsblock_t        *rsb,                /* in/out: summary block number */
        xfs_suminfo_t        *sum)                /* out: summary info for this block */
{
        xfs_buf_t        *bp;                /* buffer for summary block */
        int                error;                /* error value */
        xfs_fsblock_t        sb;                /* summary fsblock */
        int                so;                /* index into the summary file */
        xfs_suminfo_t        *sp;                /* pointer to returned data */

        /*
         * Compute entry number in the summary file.
         */
        so = XFS_SUMOFFS(mp, log, bbno);
        /*
         * Compute the block number in the summary file.
         */
        sb = XFS_SUMOFFSTOBLOCK(mp, so);
        /*
         * If we have an old buffer, and the block number matches, use that.
         */
        if (rbpp && *rbpp && *rsb == sb)
                bp = *rbpp;
        /*
         * Otherwise we have to get the buffer.
         */
        else {
                /*
                 * If there was an old one, get rid of it first.
                 */
                if (rbpp && *rbpp)
                        xfs_trans_brelse(tp, *rbpp);
                error = xfs_rtbuf_get(mp, tp, sb, 1, &bp);
                if (error) {
                        return error;
                }
                /*
                 * Remember this buffer and block for the next call.
                 */
                if (rbpp) {
                        *rbpp = bp;
                        *rsb = sb;
                }
        }
        /*
         * Point to the summary information & copy it out.
         */
        sp = XFS_SUMPTR(mp, bp, so);
        *sum = *sp;
        /*
         * Drop the buffer if we're not asked to remember it.
         */
        if (!rbpp)
                xfs_trans_brelse(tp, bp);
        return 0;
}

/*
 * Set the given range of bitmap bits to the given value.
 * Do whatever I/O and logging is required.
 */
STATIC int                                /* error */
xfs_rtmodify_range(
        xfs_mount_t        *mp,                /* file system mount point */
        xfs_trans_t        *tp,                /* transaction pointer */
        xfs_rtblock_t        start,                /* starting block to modify */
        xfs_extlen_t        len,                /* length of extent to modify */
        int                val)                /* 1 for free, 0 for allocated */
{
        xfs_rtword_t        *b;                /* current word in buffer */
        int                bit;                /* bit number in the word */
        xfs_rtblock_t        block;                /* bitmap block number */
        xfs_buf_t        *bp;                /* buf for the block */
        xfs_rtword_t        *bufp;                /* starting word in buffer */
        int                error;                /* error value */
        xfs_rtword_t        *first;                /* first used word in the buffer */
        int                i;                /* current bit number rel. to start */
        int                lastbit;        /* last useful bit in word */
        xfs_rtword_t        mask;                /* mask o frelevant bits for value */
        int                word;                /* word number in the buffer */

        /*
         * Compute starting bitmap block number.
         */
        block = XFS_BITTOBLOCK(mp, start);
        /*
         * Read the bitmap block, and point to its data.
         */
        error = xfs_rtbuf_get(mp, tp, block, 0, &bp);
        if (error) {
                return error;
        }
        bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
        /*
         * Compute the starting word's address, and starting bit.
         */
        word = XFS_BITTOWORD(mp, start);
        first = b = &bufp[word];
        bit = (int)(start & (XFS_NBWORD - 1));
        /*
         * 0 (allocated) => all zeroes; 1 (free) => all ones.
         */
        val = -val;
        /*
         * If not starting on a word boundary, deal with the first
         * (partial) word.
         */
        if (bit) {
                /*
                 * Compute first bit not changed and mask of relevant bits.
                 */
                lastbit = XFS_RTMIN(bit + len, XFS_NBWORD);
                mask = (((xfs_rtword_t)1 << (lastbit - bit)) - 1) << bit;
                /*
                 * Set/clear the active bits.
                 */
                if (val)
                        *b |= mask;
                else
                        *b &= ~mask;
                i = lastbit - bit;
                /*
                 * Go on to the next block if that's where the next word is
                 * and we need the next word.
                 */
                if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
                        /*
                         * Log the changed part of this block.
                         * Get the next one.
                         */
                        xfs_trans_log_buf(tp, bp,
                                (uint)((char *)first - (char *)bufp),
                                (uint)((char *)b - (char *)bufp));
                        error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        first = b = bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = 0;
                } else {
                        /*
                         * Go on to the next word in the buffer
                         */
                        b++;
                }
        } else {
                /*
                 * Starting on a word boundary, no partial word.
                 */
                i = 0;
        }
        /*
         * Loop over whole words in buffers.  When we use up one buffer
         * we move on to the next one.
         */
        while (len - i >= XFS_NBWORD) {
                /*
                 * Set the word value correctly.
                 */
                *b = val;
                i += XFS_NBWORD;
                /*
                 * Go on to the next block if that's where the next word is
                 * and we need the next word.
                 */
                if (++word == XFS_BLOCKWSIZE(mp) && i < len) {
                        /*
                         * Log the changed part of this block.
                         * Get the next one.
                         */
                        xfs_trans_log_buf(tp, bp,
                                (uint)((char *)first - (char *)bufp),
                                (uint)((char *)b - (char *)bufp));
                        error = xfs_rtbuf_get(mp, tp, ++block, 0, &bp);
                        if (error) {
                                return error;
                        }
                        first = b = bufp = (xfs_rtword_t *)XFS_BUF_PTR(bp);
                        word = 0;
                } else {
                        /*
                         * Go on to the next word in the buffer
                         */
                        b++;
                }
        }
        /*
         * If not ending on a word boundary, deal with the last
         * (partial) word.
         */
        if ((lastbit = len - i)) {
                /*
                 * Compute a mask of relevant bits.
                 */
                bit = 0;
                mask = ((xfs_rtword_t)1 << lastbit) - 1;
                /*
                 * Set/clear the active bits.
                 */
                if (val)
                        *b |= mask;
                else
                        *b &= ~mask;
                b++;
        }
        /*
         * Log any remaining changed bytes.
         */
        if (b > first)
                xfs_trans_log_buf(tp, bp, (uint)((char *)first - (char *)bufp),
                        (uint)((char *)b - (char *)bufp - 1));
        return 0;
}

/*
 * Read and modify the summary information for a given extent size,
 * bitmap block combination.
 * Keeps track of a current summary block, so we don't keep reading
 * it from the buffer cache.
 */
STATIC int                                /* error */
xfs_rtmodify_summary(
        xfs_mount_t        *mp,                /* file system mount point */
        xfs_trans_t        *tp,                /* transaction pointer */
        int                log,                /* log2 of extent size */
        xfs_rtblock_t        bbno,                /* bitmap block number */
        int                delta,                /* change to make to summary info */
        xfs_buf_t        **rbpp,                /* in/out: summary block buffer */
        xfs_fsblock_t        *rsb)                /* in/out: summary block number */
{
        xfs_buf_t        *bp;                /* buffer for the summary block */
        int                error;                /* error value */
        xfs_fsblock_t        sb;                /* summary fsblock */
        int                so;                /* index into the summary file */
        xfs_suminfo_t        *sp;                /* pointer to returned data */

        /*
         * Compute entry number in the summary file.
         */
        so = XFS_SUMOFFS(mp, log, bbno);
        /*
         * Compute the block number in the summary file.
         */
        sb = XFS_SUMOFFSTOBLOCK(mp, so);
        /*
         * If we have an old buffer, and the block number matches, use that.
         */
        if (rbpp && *rbpp && *rsb == sb)
                bp = *rbpp;
        /*
         * Otherwise we have to get the buffer.
         */
        else {
                /*
                 * If there was an old one, get rid of it first.
                 */
                if (rbpp && *rbpp)
                        xfs_trans_brelse(tp, *rbpp);
                error = xfs_rtbuf_get(mp, tp, sb, 1, &bp);
                if (error) {
                        return error;
                }
                /*
                 * Remember this buffer and block for the next call.
                 */
                if (rbpp) {
                        *rbpp = bp;
                        *rsb = sb;
                }
        }
        /*
         * Point to the summary information, modify and log it.
         */
        sp = XFS_SUMPTR(mp, bp, so);
        *sp += delta;
        xfs_trans_log_buf(tp, bp, (uint)((char *)sp - (char *)XFS_BUF_PTR(bp)),
                (uint)((char *)sp - (char *)XFS_BUF_PTR(bp) + sizeof(*sp) - 1));
        return 0;
}

/*
 * Visible (exported) functions.
 */

/*
 * Grow the realtime area of the filesystem.
 */
int
xfs_growfs_rt(
        xfs_mount_t        *mp,                /* mount point for filesystem */
        xfs_growfs_rt_t        *in)                /* growfs rt input struct */
{
        xfs_rtblock_t        bmbno;                /* bitmap block number */
        xfs_buf_t        *bp;                /* temporary buffer */
        int                cancelflags;        /* flags for xfs_trans_cancel */
        int                error;                /* error return value */
        xfs_inode_t        *ip;                /* bitmap inode, used as lock */
        xfs_mount_t        *nmp;                /* new (fake) mount structure */
        xfs_drfsbno_t        nrblocks;        /* new number of realtime blocks */
        xfs_extlen_t        nrbmblocks;        /* new number of rt bitmap blocks */
        xfs_drtbno_t        nrextents;        /* new number of realtime extents */
        uint8_t                nrextslog;        /* new log2 of sb_rextents */
        xfs_extlen_t        nrsumblocks;        /* new number of summary blocks */
        uint                nrsumlevels;        /* new rt summary levels */
        uint                nrsumsize;        /* new size of rt summary, bytes */
        xfs_sb_t        *nsbp;                /* new superblock */
        xfs_extlen_t        rbmblocks;        /* current number of rt bitmap blocks */
        xfs_extlen_t        rsumblocks;        /* current number of rt summary blks */
        xfs_sb_t        *sbp;                /* old superblock */
        xfs_fsblock_t        sumbno;                /* summary block number */
        xfs_trans_t        *tp;                /* transaction pointer */

        sbp = &mp->m_sb;
        cancelflags = 0;
        /*
         * Initial error checking.
         */
        if (mp->m_rtdev_targp == NULL || mp->m_rbmip == NULL ||
            (nrblocks = in->newblocks) <= sbp->sb_rblocks ||
            (sbp->sb_rblocks && (in->extsize != sbp->sb_rextsize)))
                return XFS_ERROR(EINVAL);
        if ((error = xfs_sb_validate_fsb_count(sbp, nrblocks)))
                return error;
        /*
         * Read in the last block of the device, make sure it exists.
         */
        error = xfs_read_buf(mp, mp->m_rtdev_targp,
                        XFS_FSB_TO_BB(mp, nrblocks - 1),
                        XFS_FSB_TO_BB(mp, 1), 0, &bp);
        if (error)
                return error;
        ASSERT(bp);
        xfs_buf_relse(bp);
        /*
         * Calculate new parameters.  These are the final values to be reached.
         */
        nrextents = nrblocks;
        do_div(nrextents, in->extsize);
        nrbmblocks = howmany_64(nrextents, NBBY * sbp->sb_blocksize);
        nrextslog = xfs_highbit32(nrextents);
        nrsumlevels = nrextslog + 1;
        nrsumsize = (uint)sizeof(xfs_suminfo_t) * nrsumlevels * nrbmblocks;
        nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
        nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
        /*
         * New summary size can't be more than half the size of
         * the log.  This prevents us from getting a log overflow,
         * since we'll log basically the whole summary file at once.
         */
        if (nrsumblocks > (mp->m_sb.sb_logblocks >> 1))
                return XFS_ERROR(EINVAL);
        /*
         * Get the old block counts for bitmap and summary inodes.
         * These can't change since other growfs callers are locked out.
         */
        rbmblocks = XFS_B_TO_FSB(mp, mp->m_rbmip->i_d.di_size);
        rsumblocks = XFS_B_TO_FSB(mp, mp->m_rsumip->i_d.di_size);
        /*
         * Allocate space to the bitmap and summary files, as necessary.
         */
        if ((error = xfs_growfs_rt_alloc(mp, rbmblocks, nrbmblocks,
                        mp->m_sb.sb_rbmino)))
                return error;
        if ((error = xfs_growfs_rt_alloc(mp, rsumblocks, nrsumblocks,
                        mp->m_sb.sb_rsumino)))
                return error;
        /*
         * Allocate a new (fake) mount/sb.
         */
        nmp = kmem_alloc(sizeof(*nmp), KM_SLEEP);
        /*
         * Loop over the bitmap blocks.
         * We will do everything one bitmap block at a time.
         * Skip the current block if it is exactly full.
         * This also deals with the case where there were no rtextents before.
         */
        for (bmbno = sbp->sb_rbmblocks -
                     ((sbp->sb_rextents & ((1 << mp->m_blkbit_log) - 1)) != 0);
             bmbno < nrbmblocks;
             bmbno++) {
                *nmp = *mp;
                nsbp = &nmp->m_sb;
                /*
                 * Calculate new sb and mount fields for this round.
                 */
                nsbp->sb_rextsize = in->extsize;
                nsbp->sb_rbmblocks = bmbno + 1;
                nsbp->sb_rblocks =
                        XFS_RTMIN(nrblocks,
                                  nsbp->sb_rbmblocks * NBBY *
                                  nsbp->sb_blocksize * nsbp->sb_rextsize);
                nsbp->sb_rextents = nsbp->sb_rblocks;
                do_div(nsbp->sb_rextents, nsbp->sb_rextsize);
                ASSERT(nsbp->sb_rextents != 0);
                nsbp->sb_rextslog = xfs_highbit32(nsbp->sb_rextents);
                nrsumlevels = nmp->m_rsumlevels = nsbp->sb_rextslog + 1;
                nrsumsize =
                        (uint)sizeof(xfs_suminfo_t) * nrsumlevels *
                        nsbp->sb_rbmblocks;
                nrsumblocks = XFS_B_TO_FSB(mp, nrsumsize);
                nmp->m_rsumsize = nrsumsize = XFS_FSB_TO_B(mp, nrsumblocks);
                /*
                 * Start a transaction, get the log reservation.
                 */
                tp = xfs_trans_alloc(mp, XFS_TRANS_GROWFSRT_FREE);
                cancelflags = 0;
                if ((error = xfs_trans_reserve(tp, 0,
                                XFS_GROWRTFREE_LOG_RES(nmp), 0, 0, 0)))
                        break;
                /*
                 * Lock out other callers by grabbing the bitmap inode lock.
                 */
                if ((error = xfs_trans_iget(mp, tp, mp->m_sb.sb_rbmino, 0,
                                                XFS_ILOCK_EXCL, &ip)))
                        break;
                ASSERT(ip == mp->m_rbmip);
                /*
                 * Update the bitmap inode's size.
                 */
                mp->m_rbmip->i_d.di_size =
                        nsbp->sb_rbmblocks * nsbp->sb_blocksize;
                xfs_trans_log_inode(tp, mp->m_rbmip, XFS_ILOG_CORE);
                cancelflags |= XFS_TRANS_ABORT;
                /*
                 * Get the summary inode into the transaction.
                 */
                if ((error = xfs_trans_iget(mp, tp, mp->m_sb.sb_rsumino, 0,
                                                XFS_ILOCK_EXCL, &ip)))
                        break;
                ASSERT(ip == mp->m_rsumip);
                /*
                 * Update the summary inode's size.
                 */
                mp->m_rsumip->i_d.di_size = nmp->m_rsumsize;
                xfs_trans_log_inode(tp, mp->m_rsumip, XFS_ILOG_CORE);
                /*
                 * Copy summary data from old to new sizes.
                 * Do this when the real size (not block-aligned) changes.
                 */
                if (sbp->sb_rbmblocks != nsbp->sb_rbmblocks ||
                    mp->m_rsumlevels != nmp->m_rsumlevels) {
                        error = xfs_rtcopy_summary(mp, nmp, tp);
                        if (error)
                                break;
                }
                /*
                 * Update superblock fields.
                 */
                if (nsbp->sb_rextsize != sbp->sb_rextsize)
                        xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSIZE,
                                nsbp->sb_rextsize - sbp->sb_rextsize);
                if (nsbp->sb_rbmblocks != sbp->sb_rbmblocks)
                        xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBMBLOCKS,
                                nsbp->sb_rbmblocks - sbp->sb_rbmblocks);
                if (nsbp->sb_rblocks != sbp->sb_rblocks)
                        xfs_trans_mod_sb(tp, XFS_TRANS_SB_RBLOCKS,
                                nsbp->sb_rblocks - sbp->sb_rblocks);
                if (nsbp->sb_rextents != sbp->sb_rextents)
                        xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTENTS,
                                nsbp->sb_rextents - sbp->sb_rextents);
                if (nsbp->sb_rextslog != sbp->sb_rextslog)
                        xfs_trans_mod_sb(tp, XFS_TRANS_SB_REXTSLOG,
                                nsbp->sb_rextslog - sbp->sb_rextslog);
                /*
                 * Free new extent.
                 */
                bp = NULL;
                error = xfs_rtfree_range(nmp, tp, sbp->sb_rextents,
                        nsbp->sb_rextents - sbp->sb_rextents, &bp, &sumbno);
                if (error)
                        break;
                /*
                 * Mark more blocks free in the superblock.
                 */
                xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS,
                        nsbp->sb_rextents - sbp->sb_rextents);
                /*
                 * Update mp values into the real mp structure.
                 */
                mp->m_rsumlevels = nrsumlevels;
                mp->m_rsumsize = nrsumsize;

                error = xfs_trans_commit(tp, 0);
                if (error) {
                        tp = NULL;
                        break;
                }
        }

        if (error && tp)
                xfs_trans_cancel(tp, cancelflags);

        /*
         * Free the fake mp structure.
         */
        kmem_free(nmp);

        return error;
}

/*
 * Allocate an extent in the realtime subvolume, with the usual allocation
 * parameters.  The length units are all in realtime extents, as is the
 * result block number.
 */
int                                        /* error */
xfs_rtallocate_extent(
        xfs_trans_t        *tp,                /* transaction pointer */
        xfs_rtblock_t        bno,                /* starting block number to allocate */
        xfs_extlen_t        minlen,                /* minimum length to allocate */
        xfs_extlen_t        maxlen,                /* maximum length to allocate */
        xfs_extlen_t        *len,                /* out: actual length allocated */
        xfs_alloctype_t        type,                /* allocation type XFS_ALLOCTYPE... */
        int                wasdel,                /* was a delayed allocation extent */
        xfs_extlen_t        prod,                /* extent product factor */
        xfs_rtblock_t        *rtblock)        /* out: start block allocated */
{
        int                error;                /* error value */
        xfs_inode_t        *ip;                /* inode for bitmap file */
        xfs_mount_t        *mp;                /* file system mount structure */
        xfs_rtblock_t        r;                /* result allocated block */
        xfs_fsblock_t        sb;                /* summary file block number */
        xfs_buf_t        *sumbp;                /* summary file block buffer */

        ASSERT(minlen > 0 && minlen <= maxlen);
        mp = tp->t_mountp;
        /*
         * If prod is set then figure out what to do to minlen and maxlen.
         */
        if (prod > 1) {
                xfs_extlen_t        i;

                if ((i = maxlen % prod))
                        maxlen -= i;
                if ((i = minlen % prod))
                        minlen += prod - i;
                if (maxlen < minlen) {
                        *rtblock = NULLRTBLOCK;
                        return 0;
                }
        }
        /*
         * Lock out other callers by grabbing the bitmap inode lock.
         */
        if ((error = xfs_trans_iget(mp, tp, mp->m_sb.sb_rbmino, 0,
                                        XFS_ILOCK_EXCL, &ip)))
                return error;
        sumbp = NULL;
        /*
         * Allocate by size, or near another block, or exactly at some block.
         */
        switch (type) {
        case XFS_ALLOCTYPE_ANY_AG:
                error = xfs_rtallocate_extent_size(mp, tp, minlen, maxlen, len,
                                &sumbp,        &sb, prod, &r);
                break;
        case XFS_ALLOCTYPE_NEAR_BNO:
                error = xfs_rtallocate_extent_near(mp, tp, bno, minlen, maxlen,
                                len, &sumbp, &sb, prod, &r);
                break;
        case XFS_ALLOCTYPE_THIS_BNO:
                error = xfs_rtallocate_extent_exact(mp, tp, bno, minlen, maxlen,
                                len, &sumbp, &sb, prod, &r);
                break;
        default:
                ASSERT(0);
        }
        if (error) {
                return error;
        }
        /*
         * If it worked, update the superblock.
         */
        if (r != NULLRTBLOCK) {
                long        slen = (long)*len;

                ASSERT(*len >= minlen && *len <= maxlen);
                if (wasdel)
                        xfs_trans_mod_sb(tp, XFS_TRANS_SB_RES_FREXTENTS, -slen);
                else
                        xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, -slen);
        }
        *rtblock = r;
        return 0;
}

/*
 * Free an extent in the realtime subvolume.  Length is expressed in
 * realtime extents, as is the block number.
 */
int                                        /* error */
xfs_rtfree_extent(
        xfs_trans_t        *tp,                /* transaction pointer */
        xfs_rtblock_t        bno,                /* starting block number to free */
        xfs_extlen_t        len)                /* length of extent freed */
{
        int                error;                /* error value */
        xfs_inode_t        *ip;                /* bitmap file inode */
        xfs_mount_t        *mp;                /* file system mount structure */
        xfs_fsblock_t        sb;                /* summary file block number */
        xfs_buf_t        *sumbp;                /* summary file block buffer */

        mp = tp->t_mountp;
        /*
         * Synchronize by locking the bitmap inode.
         */
        if ((error = xfs_trans_iget(mp, tp, mp->m_sb.sb_rbmino, 0,
                                        XFS_ILOCK_EXCL, &ip)))
                return error;
#if defined(__KERNEL__) && defined(DEBUG)
        /*
         * Check to see that this whole range is currently allocated.
         */
        {
                int        stat;                /* result from checking range */

                error = xfs_rtcheck_alloc_range(mp, tp, bno, len, &stat);
                if (error) {
                        return error;
                }
                ASSERT(stat);
        }
#endif
        sumbp = NULL;
        /*
         * Free the range of realtime blocks.
         */
        error = xfs_rtfree_range(mp, tp, bno, len, &sumbp, &sb);
        if (error) {
                return error;
        }
        /*
         * Mark more blocks free in the superblock.
         */
        xfs_trans_mod_sb(tp, XFS_TRANS_SB_FREXTENTS, (long)len);
        /*
         * If we've now freed all the blocks, reset the file sequence
         * number to 0.
         */
        if (tp->t_frextents_delta + mp->m_sb.sb_frextents ==
            mp->m_sb.sb_rextents) {
                if (!(ip->i_d.di_flags & XFS_DIFLAG_NEWRTBM))
                        ip->i_d.di_flags |= XFS_DIFLAG_NEWRTBM;
                *(__uint64_t *)&ip->i_d.di_atime = 0;
                xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        }
        return 0;
}

/*
 * Initialize realtime fields in the mount structure.
 */
int                                /* error */
xfs_rtmount_init(
        xfs_mount_t        *mp)        /* file system mount structure */
{
        xfs_buf_t        *bp;        /* buffer for last block of subvolume */
        xfs_daddr_t        d;        /* address of last block of subvolume */
        int                error;        /* error return value */
        xfs_sb_t        *sbp;        /* filesystem superblock copy in mount */

        sbp = &mp->m_sb;
        if (sbp->sb_rblocks == 0)
                return 0;
        if (mp->m_rtdev_targp == NULL) {
                cmn_err(CE_WARN,
        "XFS: This filesystem has a realtime volume, use rtdev=device option");
                return XFS_ERROR(ENODEV);
        }
        mp->m_rsumlevels = sbp->sb_rextslog + 1;
        mp->m_rsumsize =
                (uint)sizeof(xfs_suminfo_t) * mp->m_rsumlevels *
                sbp->sb_rbmblocks;
        mp->m_rsumsize = roundup(mp->m_rsumsize, sbp->sb_blocksize);
        mp->m_rbmip = mp->m_rsumip = NULL;
        /*
         * Check that the realtime section is an ok size.
         */
        d = (xfs_daddr_t)XFS_FSB_TO_BB(mp, mp->m_sb.sb_rblocks);
        if (XFS_BB_TO_FSB(mp, d) != mp->m_sb.sb_rblocks) {
                cmn_err(CE_WARN, "XFS: realtime mount -- %llu != %llu",
                        (unsigned long long) XFS_BB_TO_FSB(mp, d),
                        (unsigned long long) mp->m_sb.sb_rblocks);
                return XFS_ERROR(E2BIG);
        }
        error = xfs_read_buf(mp, mp->m_rtdev_targp,
                                d - XFS_FSB_TO_BB(mp, 1),
                                XFS_FSB_TO_BB(mp, 1), 0, &bp);
        if (error) {
                cmn_err(CE_WARN,
        "XFS: realtime mount -- xfs_read_buf failed, returned %d", error);
                if (error == ENOSPC)
                        return XFS_ERROR(E2BIG);
                return error;
        }
        xfs_buf_relse(bp);
        return 0;
}

/*
 * Get the bitmap and summary inodes into the mount structure
 * at mount time.
 */
int                                        /* error */
xfs_rtmount_inodes(
        xfs_mount_t        *mp)                /* file system mount structure */
{
        int                error;                /* error return value */
        xfs_sb_t        *sbp;

        sbp = &mp->m_sb;
        if (sbp->sb_rbmino == NULLFSINO)
                return 0;
        error = xfs_iget(mp, NULL, sbp->sb_rbmino, 0, 0, &mp->m_rbmip, 0);
        if (error)
                return error;
        ASSERT(mp->m_rbmip != NULL);
        ASSERT(sbp->sb_rsumino != NULLFSINO);
        error = xfs_iget(mp, NULL, sbp->sb_rsumino, 0, 0, &mp->m_rsumip, 0);
        if (error) {
                IRELE(mp->m_rbmip);
                return error;
        }
        ASSERT(mp->m_rsumip != NULL);
        return 0;
}

/*
 * Pick an extent for allocation at the start of a new realtime file.
 * Use the sequence number stored in the atime field of the bitmap inode.
 * Translate this to a fraction of the rtextents, and return the product
 * of rtextents and the fraction.
 * The fraction sequence is 0, 1/2, 1/4, 3/4, 1/8, ..., 7/8, 1/16, ...
 */
int                                        /* error */
xfs_rtpick_extent(
        xfs_mount_t        *mp,                /* file system mount point */
        xfs_trans_t        *tp,                /* transaction pointer */
        xfs_extlen_t        len,                /* allocation length (rtextents) */
        xfs_rtblock_t        *pick)                /* result rt extent */
{
        xfs_rtblock_t        b;                /* result block */
        int                error;                /* error return value */
        xfs_inode_t        *ip;                /* bitmap incore inode */
        int                log2;                /* log of sequence number */
        __uint64_t        resid;                /* residual after log removed */
        __uint64_t        seq;                /* sequence number of file creation */
        __uint64_t        *seqp;                /* pointer to seqno in inode */

        if ((error = xfs_trans_iget(mp, tp, mp->m_sb.sb_rbmino, 0,
                                        XFS_ILOCK_EXCL, &ip)))
                return error;
        ASSERT(ip == mp->m_rbmip);
        seqp = (__uint64_t *)&ip->i_d.di_atime;
        if (!(ip->i_d.di_flags & XFS_DIFLAG_NEWRTBM)) {
                ip->i_d.di_flags |= XFS_DIFLAG_NEWRTBM;
                *seqp = 0;
        }
        seq = *seqp;
        if ((log2 = xfs_highbit64(seq)) == -1)
                b = 0;
        else {
                resid = seq - (1ULL << log2);
                b = (mp->m_sb.sb_rextents * ((resid << 1) + 1ULL)) >>
                    (log2 + 1);
                if (b >= mp->m_sb.sb_rextents)
                        b = do_mod(b, mp->m_sb.sb_rextents);
                if (b + len > mp->m_sb.sb_rextents)
                        b = mp->m_sb.sb_rextents - len;
        }
        *seqp = seq + 1;
        xfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
        *pick = b;
        return 0;
}