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xfs_log_recover.c

/*
 * Copyright (c) 2000-2006 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_error.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_inode_item.h"
#include "xfs_alloc.h"
#include "xfs_ialloc.h"
#include "xfs_log_priv.h"
#include "xfs_buf_item.h"
#include "xfs_log_recover.h"
#include "xfs_extfree_item.h"
#include "xfs_trans_priv.h"
#include "xfs_quota.h"
#include "xfs_rw.h"
#include "xfs_utils.h"

STATIC int  xlog_find_zeroed(xlog_t *, xfs_daddr_t *);
STATIC int  xlog_clear_stale_blocks(xlog_t *, xfs_lsn_t);
STATIC void xlog_recover_insert_item_backq(xlog_recover_item_t **q,
                                     xlog_recover_item_t *item);
#if defined(DEBUG)
STATIC void xlog_recover_check_summary(xlog_t *);
#else
#define     xlog_recover_check_summary(log)
#endif


/*
 * Sector aligned buffer routines for buffer create/read/write/access
 */

#define XLOG_SECTOR_ROUNDUP_BBCOUNT(log, bbs)   \
      ( ((log)->l_sectbb_mask && (bbs & (log)->l_sectbb_mask)) ? \
      ((bbs + (log)->l_sectbb_mask + 1) & ~(log)->l_sectbb_mask) : (bbs) )
#define XLOG_SECTOR_ROUNDDOWN_BLKNO(log, bno)   ((bno) & ~(log)->l_sectbb_mask)

xfs_buf_t *
xlog_get_bp(
      xlog_t            *log,
      int         nbblks)
{
      if (nbblks <= 0 || nbblks > log->l_logBBsize) {
            xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
            XFS_ERROR_REPORT("xlog_get_bp(1)",
                         XFS_ERRLEVEL_HIGH, log->l_mp);
            return NULL;
      }

      if (log->l_sectbb_log) {
            if (nbblks > 1)
                  nbblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
            nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
      }
      return xfs_buf_get_noaddr(BBTOB(nbblks), log->l_mp->m_logdev_targp);
}

void
xlog_put_bp(
      xfs_buf_t   *bp)
{
      xfs_buf_free(bp);
}

STATIC xfs_caddr_t
xlog_align(
      xlog_t            *log,
      xfs_daddr_t blk_no,
      int         nbblks,
      xfs_buf_t   *bp)
{
      xfs_caddr_t ptr;

      if (!log->l_sectbb_log)
            return XFS_BUF_PTR(bp);

      ptr = XFS_BUF_PTR(bp) + BBTOB((int)blk_no & log->l_sectbb_mask);
      ASSERT(XFS_BUF_SIZE(bp) >=
            BBTOB(nbblks + (blk_no & log->l_sectbb_mask)));
      return ptr;
}


/*
 * nbblks should be uint, but oh well.  Just want to catch that 32-bit length.
 */
STATIC int
xlog_bread_noalign(
      xlog_t            *log,
      xfs_daddr_t blk_no,
      int         nbblks,
      xfs_buf_t   *bp)
{
      int         error;

      if (nbblks <= 0 || nbblks > log->l_logBBsize) {
            xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
            XFS_ERROR_REPORT("xlog_bread(1)",
                         XFS_ERRLEVEL_HIGH, log->l_mp);
            return EFSCORRUPTED;
      }

      if (log->l_sectbb_log) {
            blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
            nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
      }

      ASSERT(nbblks > 0);
      ASSERT(BBTOB(nbblks) <= XFS_BUF_SIZE(bp));
      ASSERT(bp);

      XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
      XFS_BUF_READ(bp);
      XFS_BUF_BUSY(bp);
      XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
      XFS_BUF_SET_TARGET(bp, log->l_mp->m_logdev_targp);

      xfsbdstrat(log->l_mp, bp);
      error = xfs_iowait(bp);
      if (error)
            xfs_ioerror_alert("xlog_bread", log->l_mp,
                          bp, XFS_BUF_ADDR(bp));
      return error;
}

STATIC int
xlog_bread(
      xlog_t            *log,
      xfs_daddr_t blk_no,
      int         nbblks,
      xfs_buf_t   *bp,
      xfs_caddr_t *offset)
{
      int         error;

      error = xlog_bread_noalign(log, blk_no, nbblks, bp);
      if (error)
            return error;

      *offset = xlog_align(log, blk_no, nbblks, bp);
      return 0;
}

/*
 * Write out the buffer at the given block for the given number of blocks.
 * The buffer is kept locked across the write and is returned locked.
 * This can only be used for synchronous log writes.
 */
STATIC int
xlog_bwrite(
      xlog_t            *log,
      xfs_daddr_t blk_no,
      int         nbblks,
      xfs_buf_t   *bp)
{
      int         error;

      if (nbblks <= 0 || nbblks > log->l_logBBsize) {
            xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
            XFS_ERROR_REPORT("xlog_bwrite(1)",
                         XFS_ERRLEVEL_HIGH, log->l_mp);
            return EFSCORRUPTED;
      }

      if (log->l_sectbb_log) {
            blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
            nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
      }

      ASSERT(nbblks > 0);
      ASSERT(BBTOB(nbblks) <= XFS_BUF_SIZE(bp));

      XFS_BUF_SET_ADDR(bp, log->l_logBBstart + blk_no);
      XFS_BUF_ZEROFLAGS(bp);
      XFS_BUF_BUSY(bp);
      XFS_BUF_HOLD(bp);
      XFS_BUF_PSEMA(bp, PRIBIO);
      XFS_BUF_SET_COUNT(bp, BBTOB(nbblks));
      XFS_BUF_SET_TARGET(bp, log->l_mp->m_logdev_targp);

      if ((error = xfs_bwrite(log->l_mp, bp)))
            xfs_ioerror_alert("xlog_bwrite", log->l_mp,
                          bp, XFS_BUF_ADDR(bp));
      return error;
}

#ifdef DEBUG
/*
 * dump debug superblock and log record information
 */
STATIC void
xlog_header_check_dump(
      xfs_mount_t       *mp,
      xlog_rec_header_t *head)
{
      int               b;

      cmn_err(CE_DEBUG, "%s:  SB : uuid = ", __func__);
      for (b = 0; b < 16; b++)
            cmn_err(CE_DEBUG, "%02x", ((__uint8_t *)&mp->m_sb.sb_uuid)[b]);
      cmn_err(CE_DEBUG, ", fmt = %d\n", XLOG_FMT);
      cmn_err(CE_DEBUG, "    log : uuid = ");
      for (b = 0; b < 16; b++)
            cmn_err(CE_DEBUG, "%02x", ((__uint8_t *)&head->h_fs_uuid)[b]);
      cmn_err(CE_DEBUG, ", fmt = %d\n", be32_to_cpu(head->h_fmt));
}
#else
#define xlog_header_check_dump(mp, head)
#endif

/*
 * check log record header for recovery
 */
STATIC int
xlog_header_check_recover(
      xfs_mount_t       *mp,
      xlog_rec_header_t *head)
{
      ASSERT(be32_to_cpu(head->h_magicno) == XLOG_HEADER_MAGIC_NUM);

      /*
       * IRIX doesn't write the h_fmt field and leaves it zeroed
       * (XLOG_FMT_UNKNOWN). This stops us from trying to recover
       * a dirty log created in IRIX.
       */
      if (unlikely(be32_to_cpu(head->h_fmt) != XLOG_FMT)) {
            xlog_warn(
      "XFS: dirty log written in incompatible format - can't recover");
            xlog_header_check_dump(mp, head);
            XFS_ERROR_REPORT("xlog_header_check_recover(1)",
                         XFS_ERRLEVEL_HIGH, mp);
            return XFS_ERROR(EFSCORRUPTED);
      } else if (unlikely(!uuid_equal(&mp->m_sb.sb_uuid, &head->h_fs_uuid))) {
            xlog_warn(
      "XFS: dirty log entry has mismatched uuid - can't recover");
            xlog_header_check_dump(mp, head);
            XFS_ERROR_REPORT("xlog_header_check_recover(2)",
                         XFS_ERRLEVEL_HIGH, mp);
            return XFS_ERROR(EFSCORRUPTED);
      }
      return 0;
}

/*
 * read the head block of the log and check the header
 */
STATIC int
xlog_header_check_mount(
      xfs_mount_t       *mp,
      xlog_rec_header_t *head)
{
      ASSERT(be32_to_cpu(head->h_magicno) == XLOG_HEADER_MAGIC_NUM);

      if (uuid_is_nil(&head->h_fs_uuid)) {
            /*
             * IRIX doesn't write the h_fs_uuid or h_fmt fields. If
             * h_fs_uuid is nil, we assume this log was last mounted
             * by IRIX and continue.
             */
            xlog_warn("XFS: nil uuid in log - IRIX style log");
      } else if (unlikely(!uuid_equal(&mp->m_sb.sb_uuid, &head->h_fs_uuid))) {
            xlog_warn("XFS: log has mismatched uuid - can't recover");
            xlog_header_check_dump(mp, head);
            XFS_ERROR_REPORT("xlog_header_check_mount",
                         XFS_ERRLEVEL_HIGH, mp);
            return XFS_ERROR(EFSCORRUPTED);
      }
      return 0;
}

STATIC void
xlog_recover_iodone(
      struct xfs_buf    *bp)
{
      if (XFS_BUF_GETERROR(bp)) {
            /*
             * We're not going to bother about retrying
             * this during recovery. One strike!
             */
            xfs_ioerror_alert("xlog_recover_iodone",
                          bp->b_mount, bp, XFS_BUF_ADDR(bp));
            xfs_force_shutdown(bp->b_mount, SHUTDOWN_META_IO_ERROR);
      }
      bp->b_mount = NULL;
      XFS_BUF_CLR_IODONE_FUNC(bp);
      xfs_biodone(bp);
}

/*
 * This routine finds (to an approximation) the first block in the physical
 * log which contains the given cycle.  It uses a binary search algorithm.
 * Note that the algorithm can not be perfect because the disk will not
 * necessarily be perfect.
 */
STATIC int
xlog_find_cycle_start(
      xlog_t            *log,
      xfs_buf_t   *bp,
      xfs_daddr_t first_blk,
      xfs_daddr_t *last_blk,
      uint        cycle)
{
      xfs_caddr_t offset;
      xfs_daddr_t mid_blk;
      uint        mid_cycle;
      int         error;

      mid_blk = BLK_AVG(first_blk, *last_blk);
      while (mid_blk != first_blk && mid_blk != *last_blk) {
            error = xlog_bread(log, mid_blk, 1, bp, &offset);
            if (error)
                  return error;
            mid_cycle = xlog_get_cycle(offset);
            if (mid_cycle == cycle) {
                  *last_blk = mid_blk;
                  /* last_half_cycle == mid_cycle */
            } else {
                  first_blk = mid_blk;
                  /* first_half_cycle == mid_cycle */
            }
            mid_blk = BLK_AVG(first_blk, *last_blk);
      }
      ASSERT((mid_blk == first_blk && mid_blk+1 == *last_blk) ||
             (mid_blk == *last_blk && mid_blk-1 == first_blk));

      return 0;
}

/*
 * Check that the range of blocks does not contain the cycle number
 * given.  The scan needs to occur from front to back and the ptr into the
 * region must be updated since a later routine will need to perform another
 * test.  If the region is completely good, we end up returning the same
 * last block number.
 *
 * Set blkno to -1 if we encounter no errors.  This is an invalid block number
 * since we don't ever expect logs to get this large.
 */
STATIC int
xlog_find_verify_cycle(
      xlog_t            *log,
      xfs_daddr_t start_blk,
      int         nbblks,
      uint        stop_on_cycle_no,
      xfs_daddr_t *new_blk)
{
      xfs_daddr_t i, j;
      uint        cycle;
      xfs_buf_t   *bp;
      xfs_daddr_t bufblks;
      xfs_caddr_t buf = NULL;
      int         error = 0;

      bufblks = 1 << ffs(nbblks);

      while (!(bp = xlog_get_bp(log, bufblks))) {
            /* can't get enough memory to do everything in one big buffer */
            bufblks >>= 1;
            if (bufblks <= log->l_sectbb_log)
                  return ENOMEM;
      }

      for (i = start_blk; i < start_blk + nbblks; i += bufblks) {
            int   bcount;

            bcount = min(bufblks, (start_blk + nbblks - i));

            error = xlog_bread(log, i, bcount, bp, &buf);
            if (error)
                  goto out;

            for (j = 0; j < bcount; j++) {
                  cycle = xlog_get_cycle(buf);
                  if (cycle == stop_on_cycle_no) {
                        *new_blk = i+j;
                        goto out;
                  }

                  buf += BBSIZE;
            }
      }

      *new_blk = -1;

out:
      xlog_put_bp(bp);
      return error;
}

/*
 * Potentially backup over partial log record write.
 *
 * In the typical case, last_blk is the number of the block directly after
 * a good log record.  Therefore, we subtract one to get the block number
 * of the last block in the given buffer.  extra_bblks contains the number
 * of blocks we would have read on a previous read.  This happens when the
 * last log record is split over the end of the physical log.
 *
 * extra_bblks is the number of blocks potentially verified on a previous
 * call to this routine.
 */
STATIC int
xlog_find_verify_log_record(
      xlog_t                  *log,
      xfs_daddr_t       start_blk,
      xfs_daddr_t       *last_blk,
      int               extra_bblks)
{
      xfs_daddr_t       i;
      xfs_buf_t         *bp;
      xfs_caddr_t       offset = NULL;
      xlog_rec_header_t *head = NULL;
      int               error = 0;
      int               smallmem = 0;
      int               num_blks = *last_blk - start_blk;
      int               xhdrs;

      ASSERT(start_blk != 0 || *last_blk != start_blk);

      if (!(bp = xlog_get_bp(log, num_blks))) {
            if (!(bp = xlog_get_bp(log, 1)))
                  return ENOMEM;
            smallmem = 1;
      } else {
            error = xlog_bread(log, start_blk, num_blks, bp, &offset);
            if (error)
                  goto out;
            offset += ((num_blks - 1) << BBSHIFT);
      }

      for (i = (*last_blk) - 1; i >= 0; i--) {
            if (i < start_blk) {
                  /* valid log record not found */
                  xlog_warn(
            "XFS: Log inconsistent (didn't find previous header)");
                  ASSERT(0);
                  error = XFS_ERROR(EIO);
                  goto out;
            }

            if (smallmem) {
                  error = xlog_bread(log, i, 1, bp, &offset);
                  if (error)
                        goto out;
            }

            head = (xlog_rec_header_t *)offset;

            if (XLOG_HEADER_MAGIC_NUM == be32_to_cpu(head->h_magicno))
                  break;

            if (!smallmem)
                  offset -= BBSIZE;
      }

      /*
       * We hit the beginning of the physical log & still no header.  Return
       * to caller.  If caller can handle a return of -1, then this routine
       * will be called again for the end of the physical log.
       */
      if (i == -1) {
            error = -1;
            goto out;
      }

      /*
       * We have the final block of the good log (the first block
       * of the log record _before_ the head. So we check the uuid.
       */
      if ((error = xlog_header_check_mount(log->l_mp, head)))
            goto out;

      /*
       * We may have found a log record header before we expected one.
       * last_blk will be the 1st block # with a given cycle #.  We may end
       * up reading an entire log record.  In this case, we don't want to
       * reset last_blk.  Only when last_blk points in the middle of a log
       * record do we update last_blk.
       */
      if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
            uint  h_size = be32_to_cpu(head->h_size);

            xhdrs = h_size / XLOG_HEADER_CYCLE_SIZE;
            if (h_size % XLOG_HEADER_CYCLE_SIZE)
                  xhdrs++;
      } else {
            xhdrs = 1;
      }

      if (*last_blk - i + extra_bblks !=
          BTOBB(be32_to_cpu(head->h_len)) + xhdrs)
            *last_blk = i;

out:
      xlog_put_bp(bp);
      return error;
}

/*
 * Head is defined to be the point of the log where the next log write
 * write could go.  This means that incomplete LR writes at the end are
 * eliminated when calculating the head.  We aren't guaranteed that previous
 * LR have complete transactions.  We only know that a cycle number of
 * current cycle number -1 won't be present in the log if we start writing
 * from our current block number.
 *
 * last_blk contains the block number of the first block with a given
 * cycle number.
 *
 * Return: zero if normal, non-zero if error.
 */
STATIC int
xlog_find_head(
      xlog_t            *log,
      xfs_daddr_t *return_head_blk)
{
      xfs_buf_t   *bp;
      xfs_caddr_t offset;
      xfs_daddr_t new_blk, first_blk, start_blk, last_blk, head_blk;
      int         num_scan_bblks;
      uint        first_half_cycle, last_half_cycle;
      uint        stop_on_cycle;
      int         error, log_bbnum = log->l_logBBsize;

      /* Is the end of the log device zeroed? */
      if ((error = xlog_find_zeroed(log, &first_blk)) == -1) {
            *return_head_blk = first_blk;

            /* Is the whole lot zeroed? */
            if (!first_blk) {
                  /* Linux XFS shouldn't generate totally zeroed logs -
                   * mkfs etc write a dummy unmount record to a fresh
                   * log so we can store the uuid in there
                   */
                  xlog_warn("XFS: totally zeroed log");
            }

            return 0;
      } else if (error) {
            xlog_warn("XFS: empty log check failed");
            return error;
      }

      first_blk = 0;                /* get cycle # of 1st block */
      bp = xlog_get_bp(log, 1);
      if (!bp)
            return ENOMEM;

      error = xlog_bread(log, 0, 1, bp, &offset);
      if (error)
            goto bp_err;

      first_half_cycle = xlog_get_cycle(offset);

      last_blk = head_blk = log_bbnum - 1;      /* get cycle # of last block */
      error = xlog_bread(log, last_blk, 1, bp, &offset);
      if (error)
            goto bp_err;

      last_half_cycle = xlog_get_cycle(offset);
      ASSERT(last_half_cycle != 0);

      /*
       * If the 1st half cycle number is equal to the last half cycle number,
       * then the entire log is stamped with the same cycle number.  In this
       * case, head_blk can't be set to zero (which makes sense).  The below
       * math doesn't work out properly with head_blk equal to zero.  Instead,
       * we set it to log_bbnum which is an invalid block number, but this
       * value makes the math correct.  If head_blk doesn't changed through
       * all the tests below, *head_blk is set to zero at the very end rather
       * than log_bbnum.  In a sense, log_bbnum and zero are the same block
       * in a circular file.
       */
      if (first_half_cycle == last_half_cycle) {
            /*
             * In this case we believe that the entire log should have
             * cycle number last_half_cycle.  We need to scan backwards
             * from the end verifying that there are no holes still
             * containing last_half_cycle - 1.  If we find such a hole,
             * then the start of that hole will be the new head.  The
             * simple case looks like
             *        x | x ... | x - 1 | x
             * Another case that fits this picture would be
             *        x | x + 1 | x ... | x
             * In this case the head really is somewhere at the end of the
             * log, as one of the latest writes at the beginning was
             * incomplete.
             * One more case is
             *        x | x + 1 | x ... | x - 1 | x
             * This is really the combination of the above two cases, and
             * the head has to end up at the start of the x-1 hole at the
             * end of the log.
             *
             * In the 256k log case, we will read from the beginning to the
             * end of the log and search for cycle numbers equal to x-1.
             * We don't worry about the x+1 blocks that we encounter,
             * because we know that they cannot be the head since the log
             * started with x.
             */
            head_blk = log_bbnum;
            stop_on_cycle = last_half_cycle - 1;
      } else {
            /*
             * In this case we want to find the first block with cycle
             * number matching last_half_cycle.  We expect the log to be
             * some variation on
             *        x + 1 ... | x ...
             * The first block with cycle number x (last_half_cycle) will
             * be where the new head belongs.  First we do a binary search
             * for the first occurrence of last_half_cycle.  The binary
             * search may not be totally accurate, so then we scan back
             * from there looking for occurrences of last_half_cycle before
             * us.  If that backwards scan wraps around the beginning of
             * the log, then we look for occurrences of last_half_cycle - 1
             * at the end of the log.  The cases we're looking for look
             * like
             *        x + 1 ... | x | x + 1 | x ...
             *                               ^ binary search stopped here
             * or
             *        x + 1 ... | x ... | x - 1 | x
             *        <---------> less than scan distance
             */
            stop_on_cycle = last_half_cycle;
            if ((error = xlog_find_cycle_start(log, bp, first_blk,
                                    &head_blk, last_half_cycle)))
                  goto bp_err;
      }

      /*
       * Now validate the answer.  Scan back some number of maximum possible
       * blocks and make sure each one has the expected cycle number.  The
       * maximum is determined by the total possible amount of buffering
       * in the in-core log.  The following number can be made tighter if
       * we actually look at the block size of the filesystem.
       */
      num_scan_bblks = XLOG_TOTAL_REC_SHIFT(log);
      if (head_blk >= num_scan_bblks) {
            /*
             * We are guaranteed that the entire check can be performed
             * in one buffer.
             */
            start_blk = head_blk - num_scan_bblks;
            if ((error = xlog_find_verify_cycle(log,
                                    start_blk, num_scan_bblks,
                                    stop_on_cycle, &new_blk)))
                  goto bp_err;
            if (new_blk != -1)
                  head_blk = new_blk;
      } else {          /* need to read 2 parts of log */
            /*
             * We are going to scan backwards in the log in two parts.
             * First we scan the physical end of the log.  In this part
             * of the log, we are looking for blocks with cycle number
             * last_half_cycle - 1.
             * If we find one, then we know that the log starts there, as
             * we've found a hole that didn't get written in going around
             * the end of the physical log.  The simple case for this is
             *        x + 1 ... | x ... | x - 1 | x
             *        <---------> less than scan distance
             * If all of the blocks at the end of the log have cycle number
             * last_half_cycle, then we check the blocks at the start of
             * the log looking for occurrences of last_half_cycle.  If we
             * find one, then our current estimate for the location of the
             * first occurrence of last_half_cycle is wrong and we move
             * back to the hole we've found.  This case looks like
             *        x + 1 ... | x | x + 1 | x ...
             *                               ^ binary search stopped here
             * Another case we need to handle that only occurs in 256k
             * logs is
             *        x + 1 ... | x ... | x+1 | x ...
             *                   ^ binary search stops here
             * In a 256k log, the scan at the end of the log will see the
             * x + 1 blocks.  We need to skip past those since that is
             * certainly not the head of the log.  By searching for
             * last_half_cycle-1 we accomplish that.
             */
            start_blk = log_bbnum - num_scan_bblks + head_blk;
            ASSERT(head_blk <= INT_MAX &&
                  (xfs_daddr_t) num_scan_bblks - head_blk >= 0);
            if ((error = xlog_find_verify_cycle(log, start_blk,
                              num_scan_bblks - (int)head_blk,
                              (stop_on_cycle - 1), &new_blk)))
                  goto bp_err;
            if (new_blk != -1) {
                  head_blk = new_blk;
                  goto bad_blk;
            }

            /*
             * Scan beginning of log now.  The last part of the physical
             * log is good.  This scan needs to verify that it doesn't find
             * the last_half_cycle.
             */
            start_blk = 0;
            ASSERT(head_blk <= INT_MAX);
            if ((error = xlog_find_verify_cycle(log,
                              start_blk, (int)head_blk,
                              stop_on_cycle, &new_blk)))
                  goto bp_err;
            if (new_blk != -1)
                  head_blk = new_blk;
      }

 bad_blk:
      /*
       * Now we need to make sure head_blk is not pointing to a block in
       * the middle of a log record.
       */
      num_scan_bblks = XLOG_REC_SHIFT(log);
      if (head_blk >= num_scan_bblks) {
            start_blk = head_blk - num_scan_bblks; /* don't read head_blk */

            /* start ptr at last block ptr before head_blk */
            if ((error = xlog_find_verify_log_record(log, start_blk,
                                          &head_blk, 0)) == -1) {
                  error = XFS_ERROR(EIO);
                  goto bp_err;
            } else if (error)
                  goto bp_err;
      } else {
            start_blk = 0;
            ASSERT(head_blk <= INT_MAX);
            if ((error = xlog_find_verify_log_record(log, start_blk,
                                          &head_blk, 0)) == -1) {
                  /* We hit the beginning of the log during our search */
                  start_blk = log_bbnum - num_scan_bblks + head_blk;
                  new_blk = log_bbnum;
                  ASSERT(start_blk <= INT_MAX &&
                        (xfs_daddr_t) log_bbnum-start_blk >= 0);
                  ASSERT(head_blk <= INT_MAX);
                  if ((error = xlog_find_verify_log_record(log,
                                          start_blk, &new_blk,
                                          (int)head_blk)) == -1) {
                        error = XFS_ERROR(EIO);
                        goto bp_err;
                  } else if (error)
                        goto bp_err;
                  if (new_blk != log_bbnum)
                        head_blk = new_blk;
            } else if (error)
                  goto bp_err;
      }

      xlog_put_bp(bp);
      if (head_blk == log_bbnum)
            *return_head_blk = 0;
      else
            *return_head_blk = head_blk;
      /*
       * When returning here, we have a good block number.  Bad block
       * means that during a previous crash, we didn't have a clean break
       * from cycle number N to cycle number N-1.  In this case, we need
       * to find the first block with cycle number N-1.
       */
      return 0;

 bp_err:
      xlog_put_bp(bp);

      if (error)
          xlog_warn("XFS: failed to find log head");
      return error;
}

/*
 * Find the sync block number or the tail of the log.
 *
 * This will be the block number of the last record to have its
 * associated buffers synced to disk.  Every log record header has
 * a sync lsn embedded in it.  LSNs hold block numbers, so it is easy
 * to get a sync block number.  The only concern is to figure out which
 * log record header to believe.
 *
 * The following algorithm uses the log record header with the largest
 * lsn.  The entire log record does not need to be valid.  We only care
 * that the header is valid.
 *
 * We could speed up search by using current head_blk buffer, but it is not
 * available.
 */
int
xlog_find_tail(
      xlog_t                  *log,
      xfs_daddr_t       *head_blk,
      xfs_daddr_t       *tail_blk)
{
      xlog_rec_header_t *rhead;
      xlog_op_header_t  *op_head;
      xfs_caddr_t       offset = NULL;
      xfs_buf_t         *bp;
      int               error, i, found;
      xfs_daddr_t       umount_data_blk;
      xfs_daddr_t       after_umount_blk;
      xfs_lsn_t         tail_lsn;
      int               hblks;

      found = 0;

      /*
       * Find previous log record
       */
      if ((error = xlog_find_head(log, head_blk)))
            return error;

      bp = xlog_get_bp(log, 1);
      if (!bp)
            return ENOMEM;
      if (*head_blk == 0) {                     /* special case */
            error = xlog_bread(log, 0, 1, bp, &offset);
            if (error)
                  goto bread_err;

            if (xlog_get_cycle(offset) == 0) {
                  *tail_blk = 0;
                  /* leave all other log inited values alone */
                  goto exit;
            }
      }

      /*
       * Search backwards looking for log record header block
       */
      ASSERT(*head_blk < INT_MAX);
      for (i = (int)(*head_blk) - 1; i >= 0; i--) {
            error = xlog_bread(log, i, 1, bp, &offset);
            if (error)
                  goto bread_err;

            if (XLOG_HEADER_MAGIC_NUM == be32_to_cpu(*(__be32 *)offset)) {
                  found = 1;
                  break;
            }
      }
      /*
       * If we haven't found the log record header block, start looking
       * again from the end of the physical log.  XXXmiken: There should be
       * a check here to make sure we didn't search more than N blocks in
       * the previous code.
       */
      if (!found) {
            for (i = log->l_logBBsize - 1; i >= (int)(*head_blk); i--) {
                  error = xlog_bread(log, i, 1, bp, &offset);
                  if (error)
                        goto bread_err;

                  if (XLOG_HEADER_MAGIC_NUM ==
                      be32_to_cpu(*(__be32 *)offset)) {
                        found = 2;
                        break;
                  }
            }
      }
      if (!found) {
            xlog_warn("XFS: xlog_find_tail: couldn't find sync record");
            ASSERT(0);
            return XFS_ERROR(EIO);
      }

      /* find blk_no of tail of log */
      rhead = (xlog_rec_header_t *)offset;
      *tail_blk = BLOCK_LSN(be64_to_cpu(rhead->h_tail_lsn));

      /*
       * Reset log values according to the state of the log when we
       * crashed.  In the case where head_blk == 0, we bump curr_cycle
       * one because the next write starts a new cycle rather than
       * continuing the cycle of the last good log record.  At this
       * point we have guaranteed that all partial log records have been
       * accounted for.  Therefore, we know that the last good log record
       * written was complete and ended exactly on the end boundary
       * of the physical log.
       */
      log->l_prev_block = i;
      log->l_curr_block = (int)*head_blk;
      log->l_curr_cycle = be32_to_cpu(rhead->h_cycle);
      if (found == 2)
            log->l_curr_cycle++;
      log->l_tail_lsn = be64_to_cpu(rhead->h_tail_lsn);
      log->l_last_sync_lsn = be64_to_cpu(rhead->h_lsn);
      log->l_grant_reserve_cycle = log->l_curr_cycle;
      log->l_grant_reserve_bytes = BBTOB(log->l_curr_block);
      log->l_grant_write_cycle = log->l_curr_cycle;
      log->l_grant_write_bytes = BBTOB(log->l_curr_block);

      /*
       * Look for unmount record.  If we find it, then we know there
       * was a clean unmount.  Since 'i' could be the last block in
       * the physical log, we convert to a log block before comparing
       * to the head_blk.
       *
       * Save the current tail lsn to use to pass to
       * xlog_clear_stale_blocks() below.  We won't want to clear the
       * unmount record if there is one, so we pass the lsn of the
       * unmount record rather than the block after it.
       */
      if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
            int   h_size = be32_to_cpu(rhead->h_size);
            int   h_version = be32_to_cpu(rhead->h_version);

            if ((h_version & XLOG_VERSION_2) &&
                (h_size > XLOG_HEADER_CYCLE_SIZE)) {
                  hblks = h_size / XLOG_HEADER_CYCLE_SIZE;
                  if (h_size % XLOG_HEADER_CYCLE_SIZE)
                        hblks++;
            } else {
                  hblks = 1;
            }
      } else {
            hblks = 1;
      }
      after_umount_blk = (i + hblks + (int)
            BTOBB(be32_to_cpu(rhead->h_len))) % log->l_logBBsize;
      tail_lsn = log->l_tail_lsn;
      if (*head_blk == after_umount_blk &&
          be32_to_cpu(rhead->h_num_logops) == 1) {
            umount_data_blk = (i + hblks) % log->l_logBBsize;
            error = xlog_bread(log, umount_data_blk, 1, bp, &offset);
            if (error)
                  goto bread_err;

            op_head = (xlog_op_header_t *)offset;
            if (op_head->oh_flags & XLOG_UNMOUNT_TRANS) {
                  /*
                   * Set tail and last sync so that newly written
                   * log records will point recovery to after the
                   * current unmount record.
                   */
                  log->l_tail_lsn =
                        xlog_assign_lsn(log->l_curr_cycle,
                                    after_umount_blk);
                  log->l_last_sync_lsn =
                        xlog_assign_lsn(log->l_curr_cycle,
                                    after_umount_blk);
                  *tail_blk = after_umount_blk;

                  /*
                   * Note that the unmount was clean. If the unmount
                   * was not clean, we need to know this to rebuild the
                   * superblock counters from the perag headers if we
                   * have a filesystem using non-persistent counters.
                   */
                  log->l_mp->m_flags |= XFS_MOUNT_WAS_CLEAN;
            }
      }

      /*
       * Make sure that there are no blocks in front of the head
       * with the same cycle number as the head.  This can happen
       * because we allow multiple outstanding log writes concurrently,
       * and the later writes might make it out before earlier ones.
       *
       * We use the lsn from before modifying it so that we'll never
       * overwrite the unmount record after a clean unmount.
       *
       * Do this only if we are going to recover the filesystem
       *
       * NOTE: This used to say "if (!readonly)"
       * However on Linux, we can & do recover a read-only filesystem.
       * We only skip recovery if NORECOVERY is specified on mount,
       * in which case we would not be here.
       *
       * But... if the -device- itself is readonly, just skip this.
       * We can't recover this device anyway, so it won't matter.
       */
      if (!xfs_readonly_buftarg(log->l_mp->m_logdev_targp)) {
            error = xlog_clear_stale_blocks(log, tail_lsn);
      }

bread_err:
exit:
      xlog_put_bp(bp);

      if (error)
            xlog_warn("XFS: failed to locate log tail");
      return error;
}

/*
 * Is the log zeroed at all?
 *
 * The last binary search should be changed to perform an X block read
 * once X becomes small enough.  You can then search linearly through
 * the X blocks.  This will cut down on the number of reads we need to do.
 *
 * If the log is partially zeroed, this routine will pass back the blkno
 * of the first block with cycle number 0.  It won't have a complete LR
 * preceding it.
 *
 * Return:
 *    0  => the log is completely written to
 *    -1 => use *blk_no as the first block of the log
 *    >0 => error has occurred
 */
STATIC int
xlog_find_zeroed(
      xlog_t            *log,
      xfs_daddr_t *blk_no)
{
      xfs_buf_t   *bp;
      xfs_caddr_t offset;
      uint          first_cycle, last_cycle;
      xfs_daddr_t new_blk, last_blk, start_blk;
      xfs_daddr_t     num_scan_bblks;
      int           error, log_bbnum = log->l_logBBsize;

      *blk_no = 0;

      /* check totally zeroed log */
      bp = xlog_get_bp(log, 1);
      if (!bp)
            return ENOMEM;
      error = xlog_bread(log, 0, 1, bp, &offset);
      if (error)
            goto bp_err;

      first_cycle = xlog_get_cycle(offset);
      if (first_cycle == 0) {       /* completely zeroed log */
            *blk_no = 0;
            xlog_put_bp(bp);
            return -1;
      }

      /* check partially zeroed log */
      error = xlog_bread(log, log_bbnum-1, 1, bp, &offset);
      if (error)
            goto bp_err;

      last_cycle = xlog_get_cycle(offset);
      if (last_cycle != 0) {        /* log completely written to */
            xlog_put_bp(bp);
            return 0;
      } else if (first_cycle != 1) {
            /*
             * If the cycle of the last block is zero, the cycle of
             * the first block must be 1. If it's not, maybe we're
             * not looking at a log... Bail out.
             */
            xlog_warn("XFS: Log inconsistent or not a log (last==0, first!=1)");
            return XFS_ERROR(EINVAL);
      }

      /* we have a partially zeroed log */
      last_blk = log_bbnum-1;
      if ((error = xlog_find_cycle_start(log, bp, 0, &last_blk, 0)))
            goto bp_err;

      /*
       * Validate the answer.  Because there is no way to guarantee that
       * the entire log is made up of log records which are the same size,
       * we scan over the defined maximum blocks.  At this point, the maximum
       * is not chosen to mean anything special.   XXXmiken
       */
      num_scan_bblks = XLOG_TOTAL_REC_SHIFT(log);
      ASSERT(num_scan_bblks <= INT_MAX);

      if (last_blk < num_scan_bblks)
            num_scan_bblks = last_blk;
      start_blk = last_blk - num_scan_bblks;

      /*
       * We search for any instances of cycle number 0 that occur before
       * our current estimate of the head.  What we're trying to detect is
       *        1 ... | 0 | 1 | 0...
       *                       ^ binary search ends here
       */
      if ((error = xlog_find_verify_cycle(log, start_blk,
                               (int)num_scan_bblks, 0, &new_blk)))
            goto bp_err;
      if (new_blk != -1)
            last_blk = new_blk;

      /*
       * Potentially backup over partial log record write.  We don't need
       * to search the end of the log because we know it is zero.
       */
      if ((error = xlog_find_verify_log_record(log, start_blk,
                        &last_blk, 0)) == -1) {
          error = XFS_ERROR(EIO);
          goto bp_err;
      } else if (error)
          goto bp_err;

      *blk_no = last_blk;
bp_err:
      xlog_put_bp(bp);
      if (error)
            return error;
      return -1;
}

/*
 * These are simple subroutines used by xlog_clear_stale_blocks() below
 * to initialize a buffer full of empty log record headers and write
 * them into the log.
 */
STATIC void
xlog_add_record(
      xlog_t                  *log,
      xfs_caddr_t       buf,
      int               cycle,
      int               block,
      int               tail_cycle,
      int               tail_block)
{
      xlog_rec_header_t *recp = (xlog_rec_header_t *)buf;

      memset(buf, 0, BBSIZE);
      recp->h_magicno = cpu_to_be32(XLOG_HEADER_MAGIC_NUM);
      recp->h_cycle = cpu_to_be32(cycle);
      recp->h_version = cpu_to_be32(
                  xfs_sb_version_haslogv2(&log->l_mp->m_sb) ? 2 : 1);
      recp->h_lsn = cpu_to_be64(xlog_assign_lsn(cycle, block));
      recp->h_tail_lsn = cpu_to_be64(xlog_assign_lsn(tail_cycle, tail_block));
      recp->h_fmt = cpu_to_be32(XLOG_FMT);
      memcpy(&recp->h_fs_uuid, &log->l_mp->m_sb.sb_uuid, sizeof(uuid_t));
}

STATIC int
xlog_write_log_records(
      xlog_t            *log,
      int         cycle,
      int         start_block,
      int         blocks,
      int         tail_cycle,
      int         tail_block)
{
      xfs_caddr_t offset;
      xfs_buf_t   *bp;
      int         balign, ealign;
      int         sectbb = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
      int         end_block = start_block + blocks;
      int         bufblks;
      int         error = 0;
      int         i, j = 0;

      bufblks = 1 << ffs(blocks);
      while (!(bp = xlog_get_bp(log, bufblks))) {
            bufblks >>= 1;
            if (bufblks <= log->l_sectbb_log)
                  return ENOMEM;
      }

      /* We may need to do a read at the start to fill in part of
       * the buffer in the starting sector not covered by the first
       * write below.
       */
      balign = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, start_block);
      if (balign != start_block) {
            error = xlog_bread_noalign(log, start_block, 1, bp);
            if (error)
                  goto out_put_bp;

            j = start_block - balign;
      }

      for (i = start_block; i < end_block; i += bufblks) {
            int         bcount, endcount;

            bcount = min(bufblks, end_block - start_block);
            endcount = bcount - j;

            /* We may need to do a read at the end to fill in part of
             * the buffer in the final sector not covered by the write.
             * If this is the same sector as the above read, skip it.
             */
            ealign = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, end_block);
            if (j == 0 && (start_block + endcount > ealign)) {
                  offset = XFS_BUF_PTR(bp);
                  balign = BBTOB(ealign - start_block);
                  error = XFS_BUF_SET_PTR(bp, offset + balign,
                                    BBTOB(sectbb));
                  if (error)
                        break;

                  error = xlog_bread_noalign(log, ealign, sectbb, bp);
                  if (error)
                        break;

                  error = XFS_BUF_SET_PTR(bp, offset, bufblks);
                  if (error)
                        break;
            }

            offset = xlog_align(log, start_block, endcount, bp);
            for (; j < endcount; j++) {
                  xlog_add_record(log, offset, cycle, i+j,
                              tail_cycle, tail_block);
                  offset += BBSIZE;
            }
            error = xlog_bwrite(log, start_block, endcount, bp);
            if (error)
                  break;
            start_block += endcount;
            j = 0;
      }

 out_put_bp:
      xlog_put_bp(bp);
      return error;
}

/*
 * This routine is called to blow away any incomplete log writes out
 * in front of the log head.  We do this so that we won't become confused
 * if we come up, write only a little bit more, and then crash again.
 * If we leave the partial log records out there, this situation could
 * cause us to think those partial writes are valid blocks since they
 * have the current cycle number.  We get rid of them by overwriting them
 * with empty log records with the old cycle number rather than the
 * current one.
 *
 * The tail lsn is passed in rather than taken from
 * the log so that we will not write over the unmount record after a
 * clean unmount in a 512 block log.  Doing so would leave the log without
 * any valid log records in it until a new one was written.  If we crashed
 * during that time we would not be able to recover.
 */
STATIC int
xlog_clear_stale_blocks(
      xlog_t            *log,
      xfs_lsn_t   tail_lsn)
{
      int         tail_cycle, head_cycle;
      int         tail_block, head_block;
      int         tail_distance, max_distance;
      int         distance;
      int         error;

      tail_cycle = CYCLE_LSN(tail_lsn);
      tail_block = BLOCK_LSN(tail_lsn);
      head_cycle = log->l_curr_cycle;
      head_block = log->l_curr_block;

      /*
       * Figure out the distance between the new head of the log
       * and the tail.  We want to write over any blocks beyond the
       * head that we may have written just before the crash, but
       * we don't want to overwrite the tail of the log.
       */
      if (head_cycle == tail_cycle) {
            /*
             * The tail is behind the head in the physical log,
             * so the distance from the head to the tail is the
             * distance from the head to the end of the log plus
             * the distance from the beginning of the log to the
             * tail.
             */
            if (unlikely(head_block < tail_block || head_block >= log->l_logBBsize)) {
                  XFS_ERROR_REPORT("xlog_clear_stale_blocks(1)",
                               XFS_ERRLEVEL_LOW, log->l_mp);
                  return XFS_ERROR(EFSCORRUPTED);
            }
            tail_distance = tail_block + (log->l_logBBsize - head_block);
      } else {
            /*
             * The head is behind the tail in the physical log,
             * so the distance from the head to the tail is just
             * the tail block minus the head block.
             */
            if (unlikely(head_block >= tail_block || head_cycle != (tail_cycle + 1))){
                  XFS_ERROR_REPORT("xlog_clear_stale_blocks(2)",
                               XFS_ERRLEVEL_LOW, log->l_mp);
                  return XFS_ERROR(EFSCORRUPTED);
            }
            tail_distance = tail_block - head_block;
      }

      /*
       * If the head is right up against the tail, we can't clear
       * anything.
       */
      if (tail_distance <= 0) {
            ASSERT(tail_distance == 0);
            return 0;
      }

      max_distance = XLOG_TOTAL_REC_SHIFT(log);
      /*
       * Take the smaller of the maximum amount of outstanding I/O
       * we could have and the distance to the tail to clear out.
       * We take the smaller so that we don't overwrite the tail and
       * we don't waste all day writing from the head to the tail
       * for no reason.
       */
      max_distance = MIN(max_distance, tail_distance);

      if ((head_block + max_distance) <= log->l_logBBsize) {
            /*
             * We can stomp all the blocks we need to without
             * wrapping around the end of the log.  Just do it
             * in a single write.  Use the cycle number of the
             * current cycle minus one so that the log will look like:
             *     n ... | n - 1 ...
             */
            error = xlog_write_log_records(log, (head_cycle - 1),
                        head_block, max_distance, tail_cycle,
                        tail_block);
            if (error)
                  return error;
      } else {
            /*
             * We need to wrap around the end of the physical log in
             * order to clear all the blocks.  Do it in two separate
             * I/Os.  The first write should be from the head to the
             * end of the physical log, and it should use the current
             * cycle number minus one just like above.
             */
            distance = log->l_logBBsize - head_block;
            error = xlog_write_log_records(log, (head_cycle - 1),
                        head_block, distance, tail_cycle,
                        tail_block);

            if (error)
                  return error;

            /*
             * Now write the blocks at the start of the physical log.
             * This writes the remainder of the blocks we want to clear.
             * It uses the current cycle number since we're now on the
             * same cycle as the head so that we get:
             *    n ... n ... | n - 1 ...
             *    ^^^^^ blocks we're writing
             */
            distance = max_distance - (log->l_logBBsize - head_block);
            error = xlog_write_log_records(log, head_cycle, 0, distance,
                        tail_cycle, tail_block);
            if (error)
                  return error;
      }

      return 0;
}

/******************************************************************************
 *
 *          Log recover routines
 *
 ******************************************************************************
 */

STATIC xlog_recover_t *
xlog_recover_find_tid(
      xlog_recover_t          *q,
      xlog_tid_t        tid)
{
      xlog_recover_t          *p = q;

      while (p != NULL) {
            if (p->r_log_tid == tid)
                break;
            p = p->r_next;
      }
      return p;
}

STATIC void
xlog_recover_put_hashq(
      xlog_recover_t          **q,
      xlog_recover_t          *trans)
{
      trans->r_next = *q;
      *q = trans;
}

STATIC void
xlog_recover_add_item(
      xlog_recover_item_t     **itemq)
{
      xlog_recover_item_t     *item;

      item = kmem_zalloc(sizeof(xlog_recover_item_t), KM_SLEEP);
      xlog_recover_insert_item_backq(itemq, item);
}

STATIC int
xlog_recover_add_to_cont_trans(
      xlog_recover_t          *trans,
      xfs_caddr_t       dp,
      int               len)
{
      xlog_recover_item_t     *item;
      xfs_caddr_t       ptr, old_ptr;
      int               old_len;

      item = trans->r_itemq;
      if (item == NULL) {
            /* finish copying rest of trans header */
            xlog_recover_add_item(&trans->r_itemq);
            ptr = (xfs_caddr_t) &trans->r_theader +
                        sizeof(xfs_trans_header_t) - len;
            memcpy(ptr, dp, len); /* d, s, l */
            return 0;
      }
      item = item->ri_prev;

      old_ptr = item->ri_buf[item->ri_cnt-1].i_addr;
      old_len = item->ri_buf[item->ri_cnt-1].i_len;

      ptr = kmem_realloc(old_ptr, len+old_len, old_len, 0u);
      memcpy(&ptr[old_len], dp, len); /* d, s, l */
      item->ri_buf[item->ri_cnt-1].i_len += len;
      item->ri_buf[item->ri_cnt-1].i_addr = ptr;
      return 0;
}

/*
 * The next region to add is the start of a new region.  It could be
 * a whole region or it could be the first part of a new region.  Because
 * of this, the assumption here is that the type and size fields of all
 * format structures fit into the first 32 bits of the structure.
 *
 * This works because all regions must be 32 bit aligned.  Therefore, we
 * either have both fields or we have neither field.  In the case we have
 * neither field, the data part of the region is zero length.  We only have
 * a log_op_header and can throw away the header since a new one will appear
 * later.  If we have at least 4 bytes, then we can determine how many regions
 * will appear in the current log item.
 */
STATIC int
xlog_recover_add_to_trans(
      xlog_recover_t          *trans,
      xfs_caddr_t       dp,
      int               len)
{
      xfs_inode_log_format_t  *in_f;                  /* any will do */
      xlog_recover_item_t     *item;
      xfs_caddr_t       ptr;

      if (!len)
            return 0;
      item = trans->r_itemq;
      if (item == NULL) {
            /* we need to catch log corruptions here */
            if (*(uint *)dp != XFS_TRANS_HEADER_MAGIC) {
                  xlog_warn("XFS: xlog_recover_add_to_trans: "
                          "bad header magic number");
                  ASSERT(0);
                  return XFS_ERROR(EIO);
            }
            if (len == sizeof(xfs_trans_header_t))
                  xlog_recover_add_item(&trans->r_itemq);
            memcpy(&trans->r_theader, dp, len); /* d, s, l */
            return 0;
      }

      ptr = kmem_alloc(len, KM_SLEEP);
      memcpy(ptr, dp, len);
      in_f = (xfs_inode_log_format_t *)ptr;

      if (item->ri_prev->ri_total != 0 &&
           item->ri_prev->ri_total == item->ri_prev->ri_cnt) {
            xlog_recover_add_item(&trans->r_itemq);
      }
      item = trans->r_itemq;
      item = item->ri_prev;

      if (item->ri_total == 0) {          /* first region to be added */
            if (in_f->ilf_size == 0 ||
                in_f->ilf_size > XLOG_MAX_REGIONS_IN_ITEM) {
                  xlog_warn(
      "XFS: bad number of regions (%d) in inode log format",
                          in_f->ilf_size);
                  ASSERT(0);
                  return XFS_ERROR(EIO);
            }

            item->ri_total = in_f->ilf_size;
            item->ri_buf =
                  kmem_zalloc(item->ri_total * sizeof(xfs_log_iovec_t),
                            KM_SLEEP);
      }
      ASSERT(item->ri_total > item->ri_cnt);
      /* Description region is ri_buf[0] */
      item->ri_buf[item->ri_cnt].i_addr = ptr;
      item->ri_buf[item->ri_cnt].i_len  = len;
      item->ri_cnt++;
      return 0;
}

STATIC void
xlog_recover_new_tid(
      xlog_recover_t          **q,
      xlog_tid_t        tid,
      xfs_lsn_t         lsn)
{
      xlog_recover_t          *trans;

      trans = kmem_zalloc(sizeof(xlog_recover_t), KM_SLEEP);
      trans->r_log_tid   = tid;
      trans->r_lsn         = lsn;
      xlog_recover_put_hashq(q, trans);
}

STATIC int
xlog_recover_unlink_tid(
      xlog_recover_t          **q,
      xlog_recover_t          *trans)
{
      xlog_recover_t          *tp;
      int               found = 0;

      ASSERT(trans != NULL);
      if (trans == *q) {
            *q = (*q)->r_next;
      } else {
            tp = *q;
            while (tp) {
                  if (tp->r_next == trans) {
                        found = 1;
                        break;
                  }
                  tp = tp->r_next;
            }
            if (!found) {
                  xlog_warn(
                       "XFS: xlog_recover_unlink_tid: trans not found");
                  ASSERT(0);
                  return XFS_ERROR(EIO);
            }
            tp->r_next = tp->r_next->r_next;
      }
      return 0;
}

STATIC void
xlog_recover_insert_item_backq(
      xlog_recover_item_t     **q,
      xlog_recover_item_t     *item)
{
      if (*q == NULL) {
            item->ri_prev = item->ri_next = item;
            *q = item;
      } else {
            item->ri_next           = *q;
            item->ri_prev           = (*q)->ri_prev;
            (*q)->ri_prev           = item;
            item->ri_prev->ri_next  = item;
      }
}

STATIC void
xlog_recover_insert_item_frontq(
      xlog_recover_item_t     **q,
      xlog_recover_item_t     *item)
{
      xlog_recover_insert_item_backq(q, item);
      *q = item;
}

STATIC int
xlog_recover_reorder_trans(
      xlog_recover_t          *trans)
{
      xlog_recover_item_t     *first_item, *itemq, *itemq_next;
      xfs_buf_log_format_t    *buf_f;
      ushort                  flags = 0;

      first_item = itemq = trans->r_itemq;
      trans->r_itemq = NULL;
      do {
            itemq_next = itemq->ri_next;
            buf_f = (xfs_buf_log_format_t *)itemq->ri_buf[0].i_addr;

            switch (ITEM_TYPE(itemq)) {
            case XFS_LI_BUF:
                  flags = buf_f->blf_flags;
                  if (!(flags & XFS_BLI_CANCEL)) {
                        xlog_recover_insert_item_frontq(&trans->r_itemq,
                                                itemq);
                        break;
                  }
            case XFS_LI_INODE:
            case XFS_LI_DQUOT:
            case XFS_LI_QUOTAOFF:
            case XFS_LI_EFD:
            case XFS_LI_EFI:
                  xlog_recover_insert_item_backq(&trans->r_itemq, itemq);
                  break;
            default:
                  xlog_warn(
      "XFS: xlog_recover_reorder_trans: unrecognized type of log operation");
                  ASSERT(0);
                  return XFS_ERROR(EIO);
            }
            itemq = itemq_next;
      } while (first_item != itemq);
      return 0;
}

/*
 * Build up the table of buf cancel records so that we don't replay
 * cancelled data in the second pass.  For buffer records that are
 * not cancel records, there is nothing to do here so we just return.
 *
 * If we get a cancel record which is already in the table, this indicates
 * that the buffer was cancelled multiple times.  In order to ensure
 * that during pass 2 we keep the record in the table until we reach its
 * last occurrence in the log, we keep a reference count in the cancel
 * record in the table to tell us how many times we expect to see this
 * record during the second pass.
 */
STATIC void
xlog_recover_do_buffer_pass1(
      xlog_t                  *log,
      xfs_buf_log_format_t    *buf_f)
{
      xfs_buf_cancel_t  *bcp;
      xfs_buf_cancel_t  *nextp;
      xfs_buf_cancel_t  *prevp;
      xfs_buf_cancel_t  **bucket;
      xfs_daddr_t       blkno = 0;
      uint              len = 0;
      ushort                  flags = 0;

      switch (buf_f->blf_type) {
      case XFS_LI_BUF:
            blkno = buf_f->blf_blkno;
            len = buf_f->blf_len;
            flags = buf_f->blf_flags;
            break;
      }

      /*
       * If this isn't a cancel buffer item, then just return.
       */
      if (!(flags & XFS_BLI_CANCEL))
            return;

      /*
       * Insert an xfs_buf_cancel record into the hash table of
       * them.  If there is already an identical record, bump
       * its reference count.
       */
      bucket = &log->l_buf_cancel_table[(__uint64_t)blkno %
                                XLOG_BC_TABLE_SIZE];
      /*
       * If the hash bucket is empty then just insert a new record into
       * the bucket.
       */
      if (*bucket == NULL) {
            bcp = (xfs_buf_cancel_t *)kmem_alloc(sizeof(xfs_buf_cancel_t),
                                         KM_SLEEP);
            bcp->bc_blkno = blkno;
            bcp->bc_len = len;
            bcp->bc_refcount = 1;
            bcp->bc_next = NULL;
            *bucket = bcp;
            return;
      }

      /*
       * The hash bucket is not empty, so search for duplicates of our
       * record.  If we find one them just bump its refcount.  If not
       * then add us at the end of the list.
       */
      prevp = NULL;
      nextp = *bucket;
      while (nextp != NULL) {
            if (nextp->bc_blkno == blkno && nextp->bc_len == len) {
                  nextp->bc_refcount++;
                  return;
            }
            prevp = nextp;
            nextp = nextp->bc_next;
      }
      ASSERT(prevp != NULL);
      bcp = (xfs_buf_cancel_t *)kmem_alloc(sizeof(xfs_buf_cancel_t),
                                   KM_SLEEP);
      bcp->bc_blkno = blkno;
      bcp->bc_len = len;
      bcp->bc_refcount = 1;
      bcp->bc_next = NULL;
      prevp->bc_next = bcp;
}

/*
 * Check to see whether the buffer being recovered has a corresponding
 * entry in the buffer cancel record table.  If it does then return 1
 * so that it will be cancelled, otherwise return 0.  If the buffer is
 * actually a buffer cancel item (XFS_BLI_CANCEL is set), then decrement
 * the refcount on the entry in the table and remove it from the table
 * if this is the last reference.
 *
 * We remove the cancel record from the table when we encounter its
 * last occurrence in the log so that if the same buffer is re-used
 * again after its last cancellation we actually replay the changes
 * made at that point.
 */
STATIC int
xlog_check_buffer_cancelled(
      xlog_t                  *log,
      xfs_daddr_t       blkno,
      uint              len,
      ushort                  flags)
{
      xfs_buf_cancel_t  *bcp;
      xfs_buf_cancel_t  *prevp;
      xfs_buf_cancel_t  **bucket;

      if (log->l_buf_cancel_table == NULL) {
            /*
             * There is nothing in the table built in pass one,
             * so this buffer must not be cancelled.
             */
            ASSERT(!(flags & XFS_BLI_CANCEL));
            return 0;
      }

      bucket = &log->l_buf_cancel_table[(__uint64_t)blkno %
                                XLOG_BC_TABLE_SIZE];
      bcp = *bucket;
      if (bcp == NULL) {
            /*
             * There is no corresponding entry in the table built
             * in pass one, so this buffer has not been cancelled.
             */
            ASSERT(!(flags & XFS_BLI_CANCEL));
            return 0;
      }

      /*
       * Search for an entry in the buffer cancel table that
       * matches our buffer.
       */
      prevp = NULL;
      while (bcp != NULL) {
            if (bcp->bc_blkno == blkno && bcp->bc_len == len) {
                  /*
                   * We've go a match, so return 1 so that the
                   * recovery of this buffer is cancelled.
                   * If this buffer is actually a buffer cancel
                   * log item, then decrement the refcount on the
                   * one in the table and remove it if this is the
                   * last reference.
                   */
                  if (flags & XFS_BLI_CANCEL) {
                        bcp->bc_refcount--;
                        if (bcp->bc_refcount == 0) {
                              if (prevp == NULL) {
                                    *bucket = bcp->bc_next;
                              } else {
                                    prevp->bc_next = bcp->bc_next;
                              }
                              kmem_free(bcp);
                        }
                  }
                  return 1;
            }
            prevp = bcp;
            bcp = bcp->bc_next;
      }
      /*
       * We didn't find a corresponding entry in the table, so
       * return 0 so that the buffer is NOT cancelled.
       */
      ASSERT(!(flags & XFS_BLI_CANCEL));
      return 0;
}

STATIC int
xlog_recover_do_buffer_pass2(
      xlog_t                  *log,
      xfs_buf_log_format_t    *buf_f)
{
      xfs_daddr_t       blkno = 0;
      ushort                  flags = 0;
      uint              len = 0;

      switch (buf_f->blf_type) {
      case XFS_LI_BUF:
            blkno = buf_f->blf_blkno;
            flags = buf_f->blf_flags;
            len = buf_f->blf_len;
            break;
      }

      return xlog_check_buffer_cancelled(log, blkno, len, flags);
}

/*
 * Perform recovery for a buffer full of inodes.  In these buffers,
 * the only data which should be recovered is that which corresponds
 * to the di_next_unlinked pointers in the on disk inode structures.
 * The rest of the data for the inodes is always logged through the
 * inodes themselves rather than the inode buffer and is recovered
 * in xlog_recover_do_inode_trans().
 *
 * The only time when buffers full of inodes are fully recovered is
 * when the buffer is full of newly allocated inodes.  In this case
 * the buffer will not be marked as an inode buffer and so will be
 * sent to xlog_recover_do_reg_buffer() below during recovery.
 */
STATIC int
xlog_recover_do_inode_buffer(
      xfs_mount_t       *mp,
      xlog_recover_item_t     *item,
      xfs_buf_t         *bp,
      xfs_buf_log_format_t    *buf_f)
{
      int               i;
      int               item_index;
      int               bit;
      int               nbits;
      int               reg_buf_offset;
      int               reg_buf_bytes;
      int               next_unlinked_offset;
      int               inodes_per_buf;
      xfs_agino_t       *logged_nextp;
      xfs_agino_t       *buffer_nextp;
      unsigned int            *data_map = NULL;
      unsigned int            map_size = 0;

      switch (buf_f->blf_type) {
      case XFS_LI_BUF:
            data_map = buf_f->blf_data_map;
            map_size = buf_f->blf_map_size;
            break;
      }
      /*
       * Set the variables corresponding to the current region to
       * 0 so that we'll initialize them on the first pass through
       * the loop.
       */
      reg_buf_offset = 0;
      reg_buf_bytes = 0;
      bit = 0;
      nbits = 0;
      item_index = 0;
      inodes_per_buf = XFS_BUF_COUNT(bp) >> mp->m_sb.sb_inodelog;
      for (i = 0; i < inodes_per_buf; i++) {
            next_unlinked_offset = (i * mp->m_sb.sb_inodesize) +
                  offsetof(xfs_dinode_t, di_next_unlinked);

            while (next_unlinked_offset >=
                   (reg_buf_offset + reg_buf_bytes)) {
                  /*
                   * The next di_next_unlinked field is beyond
                   * the current logged region.  Find the next
                   * logged region that contains or is beyond
                   * the current di_next_unlinked field.
                   */
                  bit += nbits;
                  bit = xfs_next_bit(data_map, map_size, bit);

                  /*
                   * If there are no more logged regions in the
                   * buffer, then we're done.
                   */
                  if (bit == -1) {
                        return 0;
                  }

                  nbits = xfs_contig_bits(data_map, map_size,
                                           bit);
                  ASSERT(nbits > 0);
                  reg_buf_offset = bit << XFS_BLI_SHIFT;
                  reg_buf_bytes = nbits << XFS_BLI_SHIFT;
                  item_index++;
            }

            /*
             * If the current logged region starts after the current
             * di_next_unlinked field, then move on to the next
             * di_next_unlinked field.
             */
            if (next_unlinked_offset < reg_buf_offset) {
                  continue;
            }

            ASSERT(item->ri_buf[item_index].i_addr != NULL);
            ASSERT((item->ri_buf[item_index].i_len % XFS_BLI_CHUNK) == 0);
            ASSERT((reg_buf_offset + reg_buf_bytes) <= XFS_BUF_COUNT(bp));

            /*
             * The current logged region contains a copy of the
             * current di_next_unlinked field.  Extract its value
             * and copy it to the buffer copy.
             */
            logged_nextp = (xfs_agino_t *)
                         ((char *)(item->ri_buf[item_index].i_addr) +
                        (next_unlinked_offset - reg_buf_offset));
            if (unlikely(*logged_nextp == 0)) {
                  xfs_fs_cmn_err(CE_ALERT, mp,
                        "bad inode buffer log record (ptr = 0x%p, bp = 0x%p).  XFS trying to replay bad (0) inode di_next_unlinked field",
                        item, bp);
                  XFS_ERROR_REPORT("xlog_recover_do_inode_buf",
                               XFS_ERRLEVEL_LOW, mp);
                  return XFS_ERROR(EFSCORRUPTED);
            }

            buffer_nextp = (xfs_agino_t *)xfs_buf_offset(bp,
                                    next_unlinked_offset);
            *buffer_nextp = *logged_nextp;
      }

      return 0;
}

/*
 * Perform a 'normal' buffer recovery.  Each logged region of the
 * buffer should be copied over the corresponding region in the
 * given buffer.  The bitmap in the buf log format structure indicates
 * where to place the logged data.
 */
/*ARGSUSED*/
STATIC void
xlog_recover_do_reg_buffer(
      xlog_recover_item_t     *item,
      xfs_buf_t         *bp,
      xfs_buf_log_format_t    *buf_f)
{
      int               i;
      int               bit;
      int               nbits;
      unsigned int            *data_map = NULL;
      unsigned int            map_size = 0;
      int                     error;

      switch (buf_f->blf_type) {
      case XFS_LI_BUF:
            data_map = buf_f->blf_data_map;
            map_size = buf_f->blf_map_size;
            break;
      }
      bit = 0;
      i = 1;  /* 0 is the buf format structure */
      while (1) {
            bit = xfs_next_bit(data_map, map_size, bit);
            if (bit == -1)
                  break;
            nbits = xfs_contig_bits(data_map, map_size, bit);
            ASSERT(nbits > 0);
            ASSERT(item->ri_buf[i].i_addr != NULL);
            ASSERT(item->ri_buf[i].i_len % XFS_BLI_CHUNK == 0);
            ASSERT(XFS_BUF_COUNT(bp) >=
                   ((uint)bit << XFS_BLI_SHIFT)+(nbits<<XFS_BLI_SHIFT));

            /*
             * Do a sanity check if this is a dquot buffer. Just checking
             * the first dquot in the buffer should do. XXXThis is
             * probably a good thing to do for other buf types also.
             */
            error = 0;
            if (buf_f->blf_flags &
               (XFS_BLI_UDQUOT_BUF|XFS_BLI_PDQUOT_BUF|XFS_BLI_GDQUOT_BUF)) {
                  if (item->ri_buf[i].i_addr == NULL) {
                        cmn_err(CE_ALERT,
                              "XFS: NULL dquot in %s.", __func__);
                        goto next;
                  }
                  if (item->ri_buf[i].i_len < sizeof(xfs_dqblk_t)) {
                        cmn_err(CE_ALERT,
                              "XFS: dquot too small (%d) in %s.",
                              item->ri_buf[i].i_len, __func__);
                        goto next;
                  }
                  error = xfs_qm_dqcheck((xfs_disk_dquot_t *)
                                     item->ri_buf[i].i_addr,
                                     -1, 0, XFS_QMOPT_DOWARN,
                                     "dquot_buf_recover");
                  if (error)
                        goto next;
            }

            memcpy(xfs_buf_offset(bp,
                  (uint)bit << XFS_BLI_SHIFT),  /* dest */
                  item->ri_buf[i].i_addr,       /* source */
                  nbits<<XFS_BLI_SHIFT);        /* length */
 next:
            i++;
            bit += nbits;
      }

      /* Shouldn't be any more regions */
      ASSERT(i == item->ri_total);
}

/*
 * Do some primitive error checking on ondisk dquot data structures.
 */
int
xfs_qm_dqcheck(
      xfs_disk_dquot_t *ddq,
      xfs_dqid_t   id,
      uint         type,        /* used only when IO_dorepair is true */
      uint         flags,
      char         *str)
{
      xfs_dqblk_t  *d = (xfs_dqblk_t *)ddq;
      int         errs = 0;

      /*
       * We can encounter an uninitialized dquot buffer for 2 reasons:
       * 1. If we crash while deleting the quotainode(s), and those blks got
       *    used for user data. This is because we take the path of regular
       *    file deletion; however, the size field of quotainodes is never
       *    updated, so all the tricks that we play in itruncate_finish
       *    don't quite matter.
       *
       * 2. We don't play the quota buffers when there's a quotaoff logitem.
       *    But the allocation will be replayed so we'll end up with an
       *    uninitialized quota block.
       *
       * This is all fine; things are still consistent, and we haven't lost
       * any quota information. Just don't complain about bad dquot blks.
       */
      if (be16_to_cpu(ddq->d_magic) != XFS_DQUOT_MAGIC) {
            if (flags & XFS_QMOPT_DOWARN)
                  cmn_err(CE_ALERT,
                  "%s : XFS dquot ID 0x%x, magic 0x%x != 0x%x",
                  str, id, be16_to_cpu(ddq->d_magic), XFS_DQUOT_MAGIC);
            errs++;
      }
      if (ddq->d_version != XFS_DQUOT_VERSION) {
            if (flags & XFS_QMOPT_DOWARN)
                  cmn_err(CE_ALERT,
                  "%s : XFS dquot ID 0x%x, version 0x%x != 0x%x",
                  str, id, ddq->d_version, XFS_DQUOT_VERSION);
            errs++;
      }

      if (ddq->d_flags != XFS_DQ_USER &&
          ddq->d_flags != XFS_DQ_PROJ &&
          ddq->d_flags != XFS_DQ_GROUP) {
            if (flags & XFS_QMOPT_DOWARN)
                  cmn_err(CE_ALERT,
                  "%s : XFS dquot ID 0x%x, unknown flags 0x%x",
                  str, id, ddq->d_flags);
            errs++;
      }

      if (id != -1 && id != be32_to_cpu(ddq->d_id)) {
            if (flags & XFS_QMOPT_DOWARN)
                  cmn_err(CE_ALERT,
                  "%s : ondisk-dquot 0x%p, ID mismatch: "
                  "0x%x expected, found id 0x%x",
                  str, ddq, id, be32_to_cpu(ddq->d_id));
            errs++;
      }

      if (!errs && ddq->d_id) {
            if (ddq->d_blk_softlimit &&
                be64_to_cpu(ddq->d_bcount) >=
                        be64_to_cpu(ddq->d_blk_softlimit)) {
                  if (!ddq->d_btimer) {
                        if (flags & XFS_QMOPT_DOWARN)
                              cmn_err(CE_ALERT,
                              "%s : Dquot ID 0x%x (0x%p) "
                              "BLK TIMER NOT STARTED",
                              str, (int)be32_to_cpu(ddq->d_id), ddq);
                        errs++;
                  }
            }
            if (ddq->d_ino_softlimit &&
                be64_to_cpu(ddq->d_icount) >=
                        be64_to_cpu(ddq->d_ino_softlimit)) {
                  if (!ddq->d_itimer) {
                        if (flags & XFS_QMOPT_DOWARN)
                              cmn_err(CE_ALERT,
                              "%s : Dquot ID 0x%x (0x%p) "
                              "INODE TIMER NOT STARTED",
                              str, (int)be32_to_cpu(ddq->d_id), ddq);
                        errs++;
                  }
            }
            if (ddq->d_rtb_softlimit &&
                be64_to_cpu(ddq->d_rtbcount) >=
                        be64_to_cpu(ddq->d_rtb_softlimit)) {
                  if (!ddq->d_rtbtimer) {
                        if (flags & XFS_QMOPT_DOWARN)
                              cmn_err(CE_ALERT,
                              "%s : Dquot ID 0x%x (0x%p) "
                              "RTBLK TIMER NOT STARTED",
                              str, (int)be32_to_cpu(ddq->d_id), ddq);
                        errs++;
                  }
            }
      }

      if (!errs || !(flags & XFS_QMOPT_DQREPAIR))
            return errs;

      if (flags & XFS_QMOPT_DOWARN)
            cmn_err(CE_NOTE, "Re-initializing dquot ID 0x%x", id);

      /*
       * Typically, a repair is only requested by quotacheck.
       */
      ASSERT(id != -1);
      ASSERT(flags & XFS_QMOPT_DQREPAIR);
      memset(d, 0, sizeof(xfs_dqblk_t));

      d->dd_diskdq.d_magic = cpu_to_be16(XFS_DQUOT_MAGIC);
      d->dd_diskdq.d_version = XFS_DQUOT_VERSION;
      d->dd_diskdq.d_flags = type;
      d->dd_diskdq.d_id = cpu_to_be32(id);

      return errs;
}

/*
 * Perform a dquot buffer recovery.
 * Simple algorithm: if we have found a QUOTAOFF logitem of the same type
 * (ie. USR or GRP), then just toss this buffer away; don't recover it.
 * Else, treat it as a regular buffer and do recovery.
 */
STATIC void
xlog_recover_do_dquot_buffer(
      xfs_mount_t       *mp,
      xlog_t                  *log,
      xlog_recover_item_t     *item,
      xfs_buf_t         *bp,
      xfs_buf_log_format_t    *buf_f)
{
      uint              type;

      /*
       * Filesystems are required to send in quota flags at mount time.
       */
      if (mp->m_qflags == 0) {
            return;
      }

      type = 0;
      if (buf_f->blf_flags & XFS_BLI_UDQUOT_BUF)
            type |= XFS_DQ_USER;
      if (buf_f->blf_flags & XFS_BLI_PDQUOT_BUF)
            type |= XFS_DQ_PROJ;
      if (buf_f->blf_flags & XFS_BLI_GDQUOT_BUF)
            type |= XFS_DQ_GROUP;
      /*
       * This type of quotas was turned off, so ignore this buffer
       */
      if (log->l_quotaoffs_flag & type)
            return;

      xlog_recover_do_reg_buffer(item, bp, buf_f);
}

/*
 * This routine replays a modification made to a buffer at runtime.
 * There are actually two types of buffer, regular and inode, which
 * are handled differently.  Inode buffers are handled differently
 * in that we only recover a specific set of data from them, namely
 * the inode di_next_unlinked fields.  This is because all other inode
 * data is actually logged via inode records and any data we replay
 * here which overlaps that may be stale.
 *
 * When meta-data buffers are freed at run time we log a buffer item
 * with the XFS_BLI_CANCEL bit set to indicate that previous copies
 * of the buffer in the log should not be replayed at recovery time.
 * This is so that if the blocks covered by the buffer are reused for
 * file data before we crash we don't end up replaying old, freed
 * meta-data into a user's file.
 *
 * To handle the cancellation of buffer log items, we make two passes
 * over the log during recovery.  During the first we build a table of
 * those buffers which have been cancelled, and during the second we
 * only replay those buffers which do not have corresponding cancel
 * records in the table.  See xlog_recover_do_buffer_pass[1,2] above
 * for more details on the implementation of the table of cancel records.
 */
STATIC int
xlog_recover_do_buffer_trans(
      xlog_t                  *log,
      xlog_recover_item_t     *item,
      int               pass)
{
      xfs_buf_log_format_t    *buf_f;
      xfs_mount_t       *mp;
      xfs_buf_t         *bp;
      int               error;
      int               cancel;
      xfs_daddr_t       blkno;
      int               len;
      ushort                  flags;

      buf_f = (xfs_buf_log_format_t *)item->ri_buf[0].i_addr;

      if (pass == XLOG_RECOVER_PASS1) {
            /*
             * In this pass we're only looking for buf items
             * with the XFS_BLI_CANCEL bit set.
             */
            xlog_recover_do_buffer_pass1(log, buf_f);
            return 0;
      } else {
            /*
             * In this pass we want to recover all the buffers
             * which have not been cancelled and are not
             * cancellation buffers themselves.  The routine
             * we call here will tell us whether or not to
             * continue with the replay of this buffer.
             */
            cancel = xlog_recover_do_buffer_pass2(log, buf_f);
            if (cancel) {
                  return 0;
            }
      }
      switch (buf_f->blf_type) {
      case XFS_LI_BUF:
            blkno = buf_f->blf_blkno;
            len = buf_f->blf_len;
            flags = buf_f->blf_flags;
            break;
      default:
            xfs_fs_cmn_err(CE_ALERT, log->l_mp,
                  "xfs_log_recover: unknown buffer type 0x%x, logdev %s",
                  buf_f->blf_type, log->l_mp->m_logname ?
                  log->l_mp->m_logname : "internal");
            XFS_ERROR_REPORT("xlog_recover_do_buffer_trans",
                         XFS_ERRLEVEL_LOW, log->l_mp);
            return XFS_ERROR(EFSCORRUPTED);
      }

      mp = log->l_mp;
      if (flags & XFS_BLI_INODE_BUF) {
            bp = xfs_buf_read_flags(mp->m_ddev_targp, blkno, len,
                                                XFS_BUF_LOCK);
      } else {
            bp = xfs_buf_read(mp->m_ddev_targp, blkno, len, 0);
      }
      if (XFS_BUF_ISERROR(bp)) {
            xfs_ioerror_alert("xlog_recover_do..(read#1)", log->l_mp,
                          bp, blkno);
            error = XFS_BUF_GETERROR(bp);
            xfs_buf_relse(bp);
            return error;
      }

      error = 0;
      if (flags & XFS_BLI_INODE_BUF) {
            error = xlog_recover_do_inode_buffer(mp, item, bp, buf_f);
      } else if (flags &
              (XFS_BLI_UDQUOT_BUF|XFS_BLI_PDQUOT_BUF|XFS_BLI_GDQUOT_BUF)) {
            xlog_recover_do_dquot_buffer(mp, log, item, bp, buf_f);
      } else {
            xlog_recover_do_reg_buffer(item, bp, buf_f);
      }
      if (error)
            return XFS_ERROR(error);

      /*
       * Perform delayed write on the buffer.  Asynchronous writes will be
       * slower when taking into account all the buffers to be flushed.
       *
       * Also make sure that only inode buffers with good sizes stay in
       * the buffer cache.  The kernel moves inodes in buffers of 1 block
       * or XFS_INODE_CLUSTER_SIZE bytes, whichever is bigger.  The inode
       * buffers in the log can be a different size if the log was generated
       * by an older kernel using unclustered inode buffers or a newer kernel
       * running with a different inode cluster size.  Regardless, if the
       * the inode buffer size isn't MAX(blocksize, XFS_INODE_CLUSTER_SIZE)
       * for *our* value of XFS_INODE_CLUSTER_SIZE, then we need to keep
       * the buffer out of the buffer cache so that the buffer won't
       * overlap with future reads of those inodes.
       */
      if (XFS_DINODE_MAGIC ==
          be16_to_cpu(*((__be16 *)xfs_buf_offset(bp, 0))) &&
          (XFS_BUF_COUNT(bp) != MAX(log->l_mp->m_sb.sb_blocksize,
                  (__uint32_t)XFS_INODE_CLUSTER_SIZE(log->l_mp)))) {
            XFS_BUF_STALE(bp);
            error = xfs_bwrite(mp, bp);
      } else {
            ASSERT(bp->b_mount == NULL || bp->b_mount == mp);
            bp->b_mount = mp;
            XFS_BUF_SET_IODONE_FUNC(bp, xlog_recover_iodone);
            xfs_bdwrite(mp, bp);
      }

      return (error);
}

STATIC int
xlog_recover_do_inode_trans(
      xlog_t                  *log,
      xlog_recover_item_t     *item,
      int               pass)
{
      xfs_inode_log_format_t  *in_f;
      xfs_mount_t       *mp;
      xfs_buf_t         *bp;
      xfs_dinode_t            *dip;
      xfs_ino_t         ino;
      int               len;
      xfs_caddr_t       src;
      xfs_caddr_t       dest;
      int               error;
      int               attr_index;
      uint              fields;
      xfs_icdinode_t          *dicp;
      int               need_free = 0;

      if (pass == XLOG_RECOVER_PASS1) {
            return 0;
      }

      if (item->ri_buf[0].i_len == sizeof(xfs_inode_log_format_t)) {
            in_f = (xfs_inode_log_format_t *)item->ri_buf[0].i_addr;
      } else {
            in_f = (xfs_inode_log_format_t *)kmem_alloc(
                  sizeof(xfs_inode_log_format_t), KM_SLEEP);
            need_free = 1;
            error = xfs_inode_item_format_convert(&item->ri_buf[0], in_f);
            if (error)
                  goto error;
      }
      ino = in_f->ilf_ino;
      mp = log->l_mp;

      /*
       * Inode buffers can be freed, look out for it,
       * and do not replay the inode.
       */
      if (xlog_check_buffer_cancelled(log, in_f->ilf_blkno,
                              in_f->ilf_len, 0)) {
            error = 0;
            goto error;
      }

      bp = xfs_buf_read_flags(mp->m_ddev_targp, in_f->ilf_blkno,
                        in_f->ilf_len, XFS_BUF_LOCK);
      if (XFS_BUF_ISERROR(bp)) {
            xfs_ioerror_alert("xlog_recover_do..(read#2)", mp,
                          bp, in_f->ilf_blkno);
            error = XFS_BUF_GETERROR(bp);
            xfs_buf_relse(bp);
            goto error;
      }
      error = 0;
      ASSERT(in_f->ilf_fields & XFS_ILOG_CORE);
      dip = (xfs_dinode_t *)xfs_buf_offset(bp, in_f->ilf_boffset);

      /*
       * Make sure the place we're flushing out to really looks
       * like an inode!
       */
      if (unlikely(be16_to_cpu(dip->di_magic) != XFS_DINODE_MAGIC)) {
            xfs_buf_relse(bp);
            xfs_fs_cmn_err(CE_ALERT, mp,
                  "xfs_inode_recover: Bad inode magic number, dino ptr = 0x%p, dino bp = 0x%p, ino = %Ld",
                  dip, bp, ino);
            XFS_ERROR_REPORT("xlog_recover_do_inode_trans(1)",
                         XFS_ERRLEVEL_LOW, mp);
            error = EFSCORRUPTED;
            goto error;
      }
      dicp = (xfs_icdinode_t *)(item->ri_buf[1].i_addr);
      if (unlikely(dicp->di_magic != XFS_DINODE_MAGIC)) {
            xfs_buf_relse(bp);
            xfs_fs_cmn_err(CE_ALERT, mp,
                  "xfs_inode_recover: Bad inode log record, rec ptr 0x%p, ino %Ld",
                  item, ino);
            XFS_ERROR_REPORT("xlog_recover_do_inode_trans(2)",
                         XFS_ERRLEVEL_LOW, mp);
            error = EFSCORRUPTED;
            goto error;
      }

      /* Skip replay when the on disk inode is newer than the log one */
      if (dicp->di_flushiter < be16_to_cpu(dip->di_flushiter)) {
            /*
             * Deal with the wrap case, DI_MAX_FLUSH is less
             * than smaller numbers
             */
            if (be16_to_cpu(dip->di_flushiter) == DI_MAX_FLUSH &&
                dicp->di_flushiter < (DI_MAX_FLUSH >> 1)) {
                  /* do nothing */
            } else {
                  xfs_buf_relse(bp);
                  error = 0;
                  goto error;
            }
      }
      /* Take the opportunity to reset the flush iteration count */
      dicp->di_flushiter = 0;

      if (unlikely((dicp->di_mode & S_IFMT) == S_IFREG)) {
            if ((dicp->di_format != XFS_DINODE_FMT_EXTENTS) &&
                (dicp->di_format != XFS_DINODE_FMT_BTREE)) {
                  XFS_CORRUPTION_ERROR("xlog_recover_do_inode_trans(3)",
                               XFS_ERRLEVEL_LOW, mp, dicp);
                  xfs_buf_relse(bp);
                  xfs_fs_cmn_err(CE_ALERT, mp,
                        "xfs_inode_recover: Bad regular inode log record, rec ptr 0x%p, ino ptr = 0x%p, ino bp = 0x%p, ino %Ld",
                        item, dip, bp, ino);
                  error = EFSCORRUPTED;
                  goto error;
            }
      } else if (unlikely((dicp->di_mode & S_IFMT) == S_IFDIR)) {
            if ((dicp->di_format != XFS_DINODE_FMT_EXTENTS) &&
                (dicp->di_format != XFS_DINODE_FMT_BTREE) &&
                (dicp->di_format != XFS_DINODE_FMT_LOCAL)) {
                  XFS_CORRUPTION_ERROR("xlog_recover_do_inode_trans(4)",
                                   XFS_ERRLEVEL_LOW, mp, dicp);
                  xfs_buf_relse(bp);
                  xfs_fs_cmn_err(CE_ALERT, mp,
                        "xfs_inode_recover: Bad dir inode log record, rec ptr 0x%p, ino ptr = 0x%p, ino bp = 0x%p, ino %Ld",
                        item, dip, bp, ino);
                  error = EFSCORRUPTED;
                  goto error;
            }
      }
      if (unlikely(dicp->di_nextents + dicp->di_anextents > dicp->di_nblocks)){
            XFS_CORRUPTION_ERROR("xlog_recover_do_inode_trans(5)",
                             XFS_ERRLEVEL_LOW, mp, dicp);
            xfs_buf_relse(bp);
            xfs_fs_cmn_err(CE_ALERT, mp,
                  "xfs_inode_recover: Bad inode log record, rec ptr 0x%p, dino ptr 0x%p, dino bp 0x%p, ino %Ld, total extents = %d, nblocks = %Ld",
                  item, dip, bp, ino,
                  dicp->di_nextents + dicp->di_anextents,
                  dicp->di_nblocks);
            error = EFSCORRUPTED;
            goto error;
      }
      if (unlikely(dicp->di_forkoff > mp->m_sb.sb_inodesize)) {
            XFS_CORRUPTION_ERROR("xlog_recover_do_inode_trans(6)",
                             XFS_ERRLEVEL_LOW, mp, dicp);
            xfs_buf_relse(bp);
            xfs_fs_cmn_err(CE_ALERT, mp,
                  "xfs_inode_recover: Bad inode log rec ptr 0x%p, dino ptr 0x%p, dino bp 0x%p, ino %Ld, forkoff 0x%x",
                  item, dip, bp, ino, dicp->di_forkoff);
            error = EFSCORRUPTED;
            goto error;
      }
      if (unlikely(item->ri_buf[1].i_len > sizeof(struct xfs_icdinode))) {
            XFS_CORRUPTION_ERROR("xlog_recover_do_inode_trans(7)",
                             XFS_ERRLEVEL_LOW, mp, dicp);
            xfs_buf_relse(bp);
            xfs_fs_cmn_err(CE_ALERT, mp,
                  "xfs_inode_recover: Bad inode log record length %d, rec ptr 0x%p",
                  item->ri_buf[1].i_len, item);
            error = EFSCORRUPTED;
            goto error;
      }

      /* The core is in in-core format */
      xfs_dinode_to_disk(dip, (xfs_icdinode_t *)item->ri_buf[1].i_addr);

      /* the rest is in on-disk format */
      if (item->ri_buf[1].i_len > sizeof(struct xfs_icdinode)) {
            memcpy((xfs_caddr_t) dip + sizeof(struct xfs_icdinode),
                  item->ri_buf[1].i_addr + sizeof(struct xfs_icdinode),
                  item->ri_buf[1].i_len  - sizeof(struct xfs_icdinode));
      }

      fields = in_f->ilf_fields;
      switch (fields & (XFS_ILOG_DEV | XFS_ILOG_UUID)) {
      case XFS_ILOG_DEV:
            xfs_dinode_put_rdev(dip, in_f->ilf_u.ilfu_rdev);
            break;
      case XFS_ILOG_UUID:
            memcpy(XFS_DFORK_DPTR(dip),
                   &in_f->ilf_u.ilfu_uuid,
                   sizeof(uuid_t));
            break;
      }

      if (in_f->ilf_size == 2)
            goto write_inode_buffer;
      len = item->ri_buf[2].i_len;
      src = item->ri_buf[2].i_addr;
      ASSERT(in_f->ilf_size <= 4);
      ASSERT((in_f->ilf_size == 3) || (fields & XFS_ILOG_AFORK));
      ASSERT(!(fields & XFS_ILOG_DFORK) ||
             (len == in_f->ilf_dsize));

      switch (fields & XFS_ILOG_DFORK) {
      case XFS_ILOG_DDATA:
      case XFS_ILOG_DEXT:
            memcpy(XFS_DFORK_DPTR(dip), src, len);
            break;

      case XFS_ILOG_DBROOT:
            xfs_bmbt_to_bmdr(mp, (struct xfs_btree_block *)src, len,
                         (xfs_bmdr_block_t *)XFS_DFORK_DPTR(dip),
                         XFS_DFORK_DSIZE(dip, mp));
            break;

      default:
            /*
             * There are no data fork flags set.
             */
            ASSERT((fields & XFS_ILOG_DFORK) == 0);
            break;
      }

      /*
       * If we logged any attribute data, recover it.  There may or
       * may not have been any other non-core data logged in this
       * transaction.
       */
      if (in_f->ilf_fields & XFS_ILOG_AFORK) {
            if (in_f->ilf_fields & XFS_ILOG_DFORK) {
                  attr_index = 3;
            } else {
                  attr_index = 2;
            }
            len = item->ri_buf[attr_index].i_len;
            src = item->ri_buf[attr_index].i_addr;
            ASSERT(len == in_f->ilf_asize);

            switch (in_f->ilf_fields & XFS_ILOG_AFORK) {
            case XFS_ILOG_ADATA:
            case XFS_ILOG_AEXT:
                  dest = XFS_DFORK_APTR(dip);
                  ASSERT(len <= XFS_DFORK_ASIZE(dip, mp));
                  memcpy(dest, src, len);
                  break;

            case XFS_ILOG_ABROOT:
                  dest = XFS_DFORK_APTR(dip);
                  xfs_bmbt_to_bmdr(mp, (struct xfs_btree_block *)src,
                               len, (xfs_bmdr_block_t*)dest,
                               XFS_DFORK_ASIZE(dip, mp));
                  break;

            default:
                  xlog_warn("XFS: xlog_recover_do_inode_trans: Invalid flag");
                  ASSERT(0);
                  xfs_buf_relse(bp);
                  error = EIO;
                  goto error;
            }
      }

write_inode_buffer:
      ASSERT(bp->b_mount == NULL || bp->b_mount == mp);
      bp->b_mount = mp;
      XFS_BUF_SET_IODONE_FUNC(bp, xlog_recover_iodone);
      xfs_bdwrite(mp, bp);
error:
      if (need_free)
            kmem_free(in_f);
      return XFS_ERROR(error);
}

/*
 * Recover QUOTAOFF records. We simply make a note of it in the xlog_t
 * structure, so that we know not to do any dquot item or dquot buffer recovery,
 * of that type.
 */
STATIC int
xlog_recover_do_quotaoff_trans(
      xlog_t                  *log,
      xlog_recover_item_t     *item,
      int               pass)
{
      xfs_qoff_logformat_t    *qoff_f;

      if (pass == XLOG_RECOVER_PASS2) {
            return (0);
      }

      qoff_f = (xfs_qoff_logformat_t *)item->ri_buf[0].i_addr;
      ASSERT(qoff_f);

      /*
       * The logitem format's flag tells us if this was user quotaoff,
       * group/project quotaoff or both.
       */
      if (qoff_f->qf_flags & XFS_UQUOTA_ACCT)
            log->l_quotaoffs_flag |= XFS_DQ_USER;
      if (qoff_f->qf_flags & XFS_PQUOTA_ACCT)
            log->l_quotaoffs_flag |= XFS_DQ_PROJ;
      if (qoff_f->qf_flags & XFS_GQUOTA_ACCT)
            log->l_quotaoffs_flag |= XFS_DQ_GROUP;

      return (0);
}

/*
 * Recover a dquot record
 */
STATIC int
xlog_recover_do_dquot_trans(
      xlog_t                  *log,
      xlog_recover_item_t     *item,
      int               pass)
{
      xfs_mount_t       *mp;
      xfs_buf_t         *bp;
      struct xfs_disk_dquot   *ddq, *recddq;
      int               error;
      xfs_dq_logformat_t      *dq_f;
      uint              type;

      if (pass == XLOG_RECOVER_PASS1) {
            return 0;
      }
      mp = log->l_mp;

      /*
       * Filesystems are required to send in quota flags at mount time.
       */
      if (mp->m_qflags == 0)
            return (0);

      recddq = (xfs_disk_dquot_t *)item->ri_buf[1].i_addr;

      if (item->ri_buf[1].i_addr == NULL) {
            cmn_err(CE_ALERT,
                  "XFS: NULL dquot in %s.", __func__);
            return XFS_ERROR(EIO);
      }
      if (item->ri_buf[1].i_len < sizeof(xfs_dqblk_t)) {
            cmn_err(CE_ALERT,
                  "XFS: dquot too small (%d) in %s.",
                  item->ri_buf[1].i_len, __func__);
            return XFS_ERROR(EIO);
      }

      /*
       * This type of quotas was turned off, so ignore this record.
       */
      type = recddq->d_flags & (XFS_DQ_USER | XFS_DQ_PROJ | XFS_DQ_GROUP);
      ASSERT(type);
      if (log->l_quotaoffs_flag & type)
            return (0);

      /*
       * At this point we know that quota was _not_ turned off.
       * Since the mount flags are not indicating to us otherwise, this
       * must mean that quota is on, and the dquot needs to be replayed.
       * Remember that we may not have fully recovered the superblock yet,
       * so we can't do the usual trick of looking at the SB quota bits.
       *
       * The other possibility, of course, is that the quota subsystem was
       * removed since the last mount - ENOSYS.
       */
      dq_f = (xfs_dq_logformat_t *)item->ri_buf[0].i_addr;
      ASSERT(dq_f);
      if ((error = xfs_qm_dqcheck(recddq,
                     dq_f->qlf_id,
                     0, XFS_QMOPT_DOWARN,
                     "xlog_recover_do_dquot_trans (log copy)"))) {
            return XFS_ERROR(EIO);
      }
      ASSERT(dq_f->qlf_len == 1);

      error = xfs_read_buf(mp, mp->m_ddev_targp,
                       dq_f->qlf_blkno,
                       XFS_FSB_TO_BB(mp, dq_f->qlf_len),
                       0, &bp);
      if (error) {
            xfs_ioerror_alert("xlog_recover_do..(read#3)", mp,
                          bp, dq_f->qlf_blkno);
            return error;
      }
      ASSERT(bp);
      ddq = (xfs_disk_dquot_t *)xfs_buf_offset(bp, dq_f->qlf_boffset);

      /*
       * At least the magic num portion should be on disk because this
       * was among a chunk of dquots created earlier, and we did some
       * minimal initialization then.
       */
      if (xfs_qm_dqcheck(ddq, dq_f->qlf_id, 0, XFS_QMOPT_DOWARN,
                     "xlog_recover_do_dquot_trans")) {
            xfs_buf_relse(bp);
            return XFS_ERROR(EIO);
      }

      memcpy(ddq, recddq, item->ri_buf[1].i_len);

      ASSERT(dq_f->qlf_size == 2);
      ASSERT(bp->b_mount == NULL || bp->b_mount == mp);
      bp->b_mount = mp;
      XFS_BUF_SET_IODONE_FUNC(bp, xlog_recover_iodone);
      xfs_bdwrite(mp, bp);

      return (0);
}

/*
 * This routine is called to create an in-core extent free intent
 * item from the efi format structure which was logged on disk.
 * It allocates an in-core efi, copies the extents from the format
 * structure into it, and adds the efi to the AIL with the given
 * LSN.
 */
STATIC int
xlog_recover_do_efi_trans(
      xlog_t                  *log,
      xlog_recover_item_t     *item,
      xfs_lsn_t         lsn,
      int               pass)
{
      int               error;
      xfs_mount_t       *mp;
      xfs_efi_log_item_t      *efip;
      xfs_efi_log_format_t    *efi_formatp;

      if (pass == XLOG_RECOVER_PASS1) {
            return 0;
      }

      efi_formatp = (xfs_efi_log_format_t *)item->ri_buf[0].i_addr;

      mp = log->l_mp;
      efip = xfs_efi_init(mp, efi_formatp->efi_nextents);
      if ((error = xfs_efi_copy_format(&(item->ri_buf[0]),
                               &(efip->efi_format)))) {
            xfs_efi_item_free(efip);
            return error;
      }
      efip->efi_next_extent = efi_formatp->efi_nextents;
      efip->efi_flags |= XFS_EFI_COMMITTED;

      spin_lock(&log->l_ailp->xa_lock);
      /*
       * xfs_trans_ail_update() drops the AIL lock.
       */
      xfs_trans_ail_update(log->l_ailp, (xfs_log_item_t *)efip, lsn);
      return 0;
}


/*
 * This routine is called when an efd format structure is found in
 * a committed transaction in the log.  It's purpose is to cancel
 * the corresponding efi if it was still in the log.  To do this
 * it searches the AIL for the efi with an id equal to that in the
 * efd format structure.  If we find it, we remove the efi from the
 * AIL and free it.
 */
STATIC void
xlog_recover_do_efd_trans(
      xlog_t                  *log,
      xlog_recover_item_t     *item,
      int               pass)
{
      xfs_efd_log_format_t    *efd_formatp;
      xfs_efi_log_item_t      *efip = NULL;
      xfs_log_item_t          *lip;
      __uint64_t        efi_id;
      struct xfs_ail_cursor   cur;
      struct xfs_ail          *ailp = log->l_ailp;

      if (pass == XLOG_RECOVER_PASS1) {
            return;
      }

      efd_formatp = (xfs_efd_log_format_t *)item->ri_buf[0].i_addr;
      ASSERT((item->ri_buf[0].i_len == (sizeof(xfs_efd_log_format_32_t) +
            ((efd_formatp->efd_nextents - 1) * sizeof(xfs_extent_32_t)))) ||
             (item->ri_buf[0].i_len == (sizeof(xfs_efd_log_format_64_t) +
            ((efd_formatp->efd_nextents - 1) * sizeof(xfs_extent_64_t)))));
      efi_id = efd_formatp->efd_efi_id;

      /*
       * Search for the efi with the id in the efd format structure
       * in the AIL.
       */
      spin_lock(&ailp->xa_lock);
      lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
      while (lip != NULL) {
            if (lip->li_type == XFS_LI_EFI) {
                  efip = (xfs_efi_log_item_t *)lip;
                  if (efip->efi_format.efi_id == efi_id) {
                        /*
                         * xfs_trans_ail_delete() drops the
                         * AIL lock.
                         */
                        xfs_trans_ail_delete(ailp, lip);
                        xfs_efi_item_free(efip);
                        spin_lock(&ailp->xa_lock);
                        break;
                  }
            }
            lip = xfs_trans_ail_cursor_next(ailp, &cur);
      }
      xfs_trans_ail_cursor_done(ailp, &cur);
      spin_unlock(&ailp->xa_lock);
}

/*
 * Perform the transaction
 *
 * If the transaction modifies a buffer or inode, do it now.  Otherwise,
 * EFIs and EFDs get queued up by adding entries into the AIL for them.
 */
STATIC int
xlog_recover_do_trans(
      xlog_t                  *log,
      xlog_recover_t          *trans,
      int               pass)
{
      int               error = 0;
      xlog_recover_item_t     *item, *first_item;

      error = xlog_recover_reorder_trans(trans);
      if (error)
            return error;

      first_item = item = trans->r_itemq;
      do {
            switch (ITEM_TYPE(item)) {
            case XFS_LI_BUF:
                  error = xlog_recover_do_buffer_trans(log, item, pass);
                  break;
            case XFS_LI_INODE:
                  error = xlog_recover_do_inode_trans(log, item, pass);
                  break;
            case XFS_LI_EFI:
                  error = xlog_recover_do_efi_trans(log, item,
                                            trans->r_lsn, pass);
                  break;
            case XFS_LI_EFD:
                  xlog_recover_do_efd_trans(log, item, pass);
                  error = 0;
                  break;
            case XFS_LI_DQUOT:
                  error = xlog_recover_do_dquot_trans(log, item, pass);
                  break;
            case XFS_LI_QUOTAOFF:
                  error = xlog_recover_do_quotaoff_trans(log, item,
                                                 pass);
                  break;
            default:
                  xlog_warn(
      "XFS: invalid item type (%d) xlog_recover_do_trans", ITEM_TYPE(item));
                  ASSERT(0);
                  error = XFS_ERROR(EIO);
                  break;
            }

            if (error)
                  return error;
            item = item->ri_next;
      } while (first_item != item);

      return 0;
}

/*
 * Free up any resources allocated by the transaction
 *
 * Remember that EFIs, EFDs, and IUNLINKs are handled later.
 */
STATIC void
xlog_recover_free_trans(
      xlog_recover_t          *trans)
{
      xlog_recover_item_t     *first_item, *item, *free_item;
      int               i;

      item = first_item = trans->r_itemq;
      do {
            free_item = item;
            item = item->ri_next;
             /* Free the regions in the item. */
            for (i = 0; i < free_item->ri_cnt; i++) {
                  kmem_free(free_item->ri_buf[i].i_addr);
            }
            /* Free the item itself */
            kmem_free(free_item->ri_buf);
            kmem_free(free_item);
      } while (first_item != item);
      /* Free the transaction recover structure */
      kmem_free(trans);
}

STATIC int
xlog_recover_commit_trans(
      xlog_t                  *log,
      xlog_recover_t          **q,
      xlog_recover_t          *trans,
      int               pass)
{
      int               error;

      if ((error = xlog_recover_unlink_tid(q, trans)))
            return error;
      if ((error = xlog_recover_do_trans(log, trans, pass)))
            return error;
      xlog_recover_free_trans(trans);                 /* no error */
      return 0;
}

STATIC int
xlog_recover_unmount_trans(
      xlog_recover_t          *trans)
{
      /* Do nothing now */
      xlog_warn("XFS: xlog_recover_unmount_trans: Unmount LR");
      return 0;
}

/*
 * There are two valid states of the r_state field.  0 indicates that the
 * transaction structure is in a normal state.  We have either seen the
 * start of the transaction or the last operation we added was not a partial
 * operation.  If the last operation we added to the transaction was a
 * partial operation, we need to mark r_state with XLOG_WAS_CONT_TRANS.
 *
 * NOTE: skip LRs with 0 data length.
 */
STATIC int
xlog_recover_process_data(
      xlog_t                  *log,
      xlog_recover_t          *rhash[],
      xlog_rec_header_t *rhead,
      xfs_caddr_t       dp,
      int               pass)
{
      xfs_caddr_t       lp;
      int               num_logops;
      xlog_op_header_t  *ohead;
      xlog_recover_t          *trans;
      xlog_tid_t        tid;
      int               error;
      unsigned long           hash;
      uint              flags;

      lp = dp + be32_to_cpu(rhead->h_len);
      num_logops = be32_to_cpu(rhead->h_num_logops);

      /* check the log format matches our own - else we can't recover */
      if (xlog_header_check_recover(log->l_mp, rhead))
            return (XFS_ERROR(EIO));

      while ((dp < lp) && num_logops) {
            ASSERT(dp + sizeof(xlog_op_header_t) <= lp);
            ohead = (xlog_op_header_t *)dp;
            dp += sizeof(xlog_op_header_t);
            if (ohead->oh_clientid != XFS_TRANSACTION &&
                ohead->oh_clientid != XFS_LOG) {
                  xlog_warn(
            "XFS: xlog_recover_process_data: bad clientid");
                  ASSERT(0);
                  return (XFS_ERROR(EIO));
            }
            tid = be32_to_cpu(ohead->oh_tid);
            hash = XLOG_RHASH(tid);
            trans = xlog_recover_find_tid(rhash[hash], tid);
            if (trans == NULL) {             /* not found; add new tid */
                  if (ohead->oh_flags & XLOG_START_TRANS)
                        xlog_recover_new_tid(&rhash[hash], tid,
                              be64_to_cpu(rhead->h_lsn));
            } else {
                  if (dp + be32_to_cpu(ohead->oh_len) > lp) {
                        xlog_warn(
                  "XFS: xlog_recover_process_data: bad length");
                        WARN_ON(1);
                        return (XFS_ERROR(EIO));
                  }
                  flags = ohead->oh_flags & ~XLOG_END_TRANS;
                  if (flags & XLOG_WAS_CONT_TRANS)
                        flags &= ~XLOG_CONTINUE_TRANS;
                  switch (flags) {
                  case XLOG_COMMIT_TRANS:
                        error = xlog_recover_commit_trans(log,
                                    &rhash[hash], trans, pass);
                        break;
                  case XLOG_UNMOUNT_TRANS:
                        error = xlog_recover_unmount_trans(trans);
                        break;
                  case XLOG_WAS_CONT_TRANS:
                        error = xlog_recover_add_to_cont_trans(trans,
                                    dp, be32_to_cpu(ohead->oh_len));
                        break;
                  case XLOG_START_TRANS:
                        xlog_warn(
                  "XFS: xlog_recover_process_data: bad transaction");
                        ASSERT(0);
                        error = XFS_ERROR(EIO);
                        break;
                  case 0:
                  case XLOG_CONTINUE_TRANS:
                        error = xlog_recover_add_to_trans(trans,
                                    dp, be32_to_cpu(ohead->oh_len));
                        break;
                  default:
                        xlog_warn(
                  "XFS: xlog_recover_process_data: bad flag");
                        ASSERT(0);
                        error = XFS_ERROR(EIO);
                        break;
                  }
                  if (error)
                        return error;
            }
            dp += be32_to_cpu(ohead->oh_len);
            num_logops--;
      }
      return 0;
}

/*
 * Process an extent free intent item that was recovered from
 * the log.  We need to free the extents that it describes.
 */
STATIC int
xlog_recover_process_efi(
      xfs_mount_t       *mp,
      xfs_efi_log_item_t      *efip)
{
      xfs_efd_log_item_t      *efdp;
      xfs_trans_t       *tp;
      int               i;
      int               error = 0;
      xfs_extent_t            *extp;
      xfs_fsblock_t           startblock_fsb;

      ASSERT(!(efip->efi_flags & XFS_EFI_RECOVERED));

      /*
       * First check the validity of the extents described by the
       * EFI.  If any are bad, then assume that all are bad and
       * just toss the EFI.
       */
      for (i = 0; i < efip->efi_format.efi_nextents; i++) {
            extp = &(efip->efi_format.efi_extents[i]);
            startblock_fsb = XFS_BB_TO_FSB(mp,
                           XFS_FSB_TO_DADDR(mp, extp->ext_start));
            if ((startblock_fsb == 0) ||
                (extp->ext_len == 0) ||
                (startblock_fsb >= mp->m_sb.sb_dblocks) ||
                (extp->ext_len >= mp->m_sb.sb_agblocks)) {
                  /*
                   * This will pull the EFI from the AIL and
                   * free the memory associated with it.
                   */
                  xfs_efi_release(efip, efip->efi_format.efi_nextents);
                  return XFS_ERROR(EIO);
            }
      }

      tp = xfs_trans_alloc(mp, 0);
      error = xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0, 0, 0);
      if (error)
            goto abort_error;
      efdp = xfs_trans_get_efd(tp, efip, efip->efi_format.efi_nextents);

      for (i = 0; i < efip->efi_format.efi_nextents; i++) {
            extp = &(efip->efi_format.efi_extents[i]);
            error = xfs_free_extent(tp, extp->ext_start, extp->ext_len);
            if (error)
                  goto abort_error;
            xfs_trans_log_efd_extent(tp, efdp, extp->ext_start,
                               extp->ext_len);
      }

      efip->efi_flags |= XFS_EFI_RECOVERED;
      error = xfs_trans_commit(tp, 0);
      return error;

abort_error:
      xfs_trans_cancel(tp, XFS_TRANS_ABORT);
      return error;
}

/*
 * When this is called, all of the EFIs which did not have
 * corresponding EFDs should be in the AIL.  What we do now
 * is free the extents associated with each one.
 *
 * Since we process the EFIs in normal transactions, they
 * will be removed at some point after the commit.  This prevents
 * us from just walking down the list processing each one.
 * We'll use a flag in the EFI to skip those that we've already
 * processed and use the AIL iteration mechanism's generation
 * count to try to speed this up at least a bit.
 *
 * When we start, we know that the EFIs are the only things in
 * the AIL.  As we process them, however, other items are added
 * to the AIL.  Since everything added to the AIL must come after
 * everything already in the AIL, we stop processing as soon as
 * we see something other than an EFI in the AIL.
 */
STATIC int
xlog_recover_process_efis(
      xlog_t                  *log)
{
      xfs_log_item_t          *lip;
      xfs_efi_log_item_t      *efip;
      int               error = 0;
      struct xfs_ail_cursor   cur;
      struct xfs_ail          *ailp;

      ailp = log->l_ailp;
      spin_lock(&ailp->xa_lock);
      lip = xfs_trans_ail_cursor_first(ailp, &cur, 0);
      while (lip != NULL) {
            /*
             * We're done when we see something other than an EFI.
             * There should be no EFIs left in the AIL now.
             */
            if (lip->li_type != XFS_LI_EFI) {
#ifdef DEBUG
                  for (; lip; lip = xfs_trans_ail_cursor_next(ailp, &cur))
                        ASSERT(lip->li_type != XFS_LI_EFI);
#endif
                  break;
            }

            /*
             * Skip EFIs that we've already processed.
             */
            efip = (xfs_efi_log_item_t *)lip;
            if (efip->efi_flags & XFS_EFI_RECOVERED) {
                  lip = xfs_trans_ail_cursor_next(ailp, &cur);
                  continue;
            }

            spin_unlock(&ailp->xa_lock);
            error = xlog_recover_process_efi(log->l_mp, efip);
            spin_lock(&ailp->xa_lock);
            if (error)
                  goto out;
            lip = xfs_trans_ail_cursor_next(ailp, &cur);
      }
out:
      xfs_trans_ail_cursor_done(ailp, &cur);
      spin_unlock(&ailp->xa_lock);
      return error;
}

/*
 * This routine performs a transaction to null out a bad inode pointer
 * in an agi unlinked inode hash bucket.
 */
STATIC void
xlog_recover_clear_agi_bucket(
      xfs_mount_t *mp,
      xfs_agnumber_t    agno,
      int         bucket)
{
      xfs_trans_t *tp;
      xfs_agi_t   *agi;
      xfs_buf_t   *agibp;
      int         offset;
      int         error;

      tp = xfs_trans_alloc(mp, XFS_TRANS_CLEAR_AGI_BUCKET);
      error = xfs_trans_reserve(tp, 0, XFS_CLEAR_AGI_BUCKET_LOG_RES(mp),
                          0, 0, 0);
      if (error)
            goto out_abort;

      error = xfs_read_agi(mp, tp, agno, &agibp);
      if (error)
            goto out_abort;

      agi = XFS_BUF_TO_AGI(agibp);
      agi->agi_unlinked[bucket] = cpu_to_be32(NULLAGINO);
      offset = offsetof(xfs_agi_t, agi_unlinked) +
             (sizeof(xfs_agino_t) * bucket);
      xfs_trans_log_buf(tp, agibp, offset,
                    (offset + sizeof(xfs_agino_t) - 1));

      error = xfs_trans_commit(tp, 0);
      if (error)
            goto out_error;
      return;

out_abort:
      xfs_trans_cancel(tp, XFS_TRANS_ABORT);
out_error:
      xfs_fs_cmn_err(CE_WARN, mp, "xlog_recover_clear_agi_bucket: "
                  "failed to clear agi %d. Continuing.", agno);
      return;
}

STATIC xfs_agino_t
xlog_recover_process_one_iunlink(
      struct xfs_mount        *mp,
      xfs_agnumber_t                agno,
      xfs_agino_t             agino,
      int                     bucket)
{
      struct xfs_buf                *ibp;
      struct xfs_dinode       *dip;
      struct xfs_inode        *ip;
      xfs_ino_t               ino;
      int                     error;

      ino = XFS_AGINO_TO_INO(mp, agno, agino);
      error = xfs_iget(mp, NULL, ino, 0, 0, &ip, 0);
      if (error)
            goto fail;

      /*
       * Get the on disk inode to find the next inode in the bucket.
       */
      error = xfs_itobp(mp, NULL, ip, &dip, &ibp, XFS_BUF_LOCK);
      if (error)
            goto fail_iput;

      ASSERT(ip->i_d.di_nlink == 0);
      ASSERT(ip->i_d.di_mode != 0);

      /* setup for the next pass */
      agino = be32_to_cpu(dip->di_next_unlinked);
      xfs_buf_relse(ibp);

      /*
       * Prevent any DMAPI event from being sent when the reference on
       * the inode is dropped.
       */
      ip->i_d.di_dmevmask = 0;

      IRELE(ip);
      return agino;

 fail_iput:
      IRELE(ip);
 fail:
      /*
       * We can't read in the inode this bucket points to, or this inode
       * is messed up.  Just ditch this bucket of inodes.  We will lose
       * some inodes and space, but at least we won't hang.
       *
       * Call xlog_recover_clear_agi_bucket() to perform a transaction to
       * clear the inode pointer in the bucket.
       */
      xlog_recover_clear_agi_bucket(mp, agno, bucket);
      return NULLAGINO;
}

/*
 * xlog_iunlink_recover
 *
 * This is called during recovery to process any inodes which
 * we unlinked but not freed when the system crashed.  These
 * inodes will be on the lists in the AGI blocks.  What we do
 * here is scan all the AGIs and fully truncate and free any
 * inodes found on the lists.  Each inode is removed from the
 * lists when it has been fully truncated and is freed.  The
 * freeing of the inode and its removal from the list must be
 * atomic.
 */
void
xlog_recover_process_iunlinks(
      xlog_t            *log)
{
      xfs_mount_t *mp;
      xfs_agnumber_t    agno;
      xfs_agi_t   *agi;
      xfs_buf_t   *agibp;
      xfs_agino_t agino;
      int         bucket;
      int         error;
      uint        mp_dmevmask;

      mp = log->l_mp;

      /*
       * Prevent any DMAPI event from being sent while in this function.
       */
      mp_dmevmask = mp->m_dmevmask;
      mp->m_dmevmask = 0;

      for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
            /*
             * Find the agi for this ag.
             */
            error = xfs_read_agi(mp, NULL, agno, &agibp);
            if (error) {
                  /*
                   * AGI is b0rked. Don't process it.
                   *
                   * We should probably mark the filesystem as corrupt
                   * after we've recovered all the ag's we can....
                   */
                  continue;
            }
            agi = XFS_BUF_TO_AGI(agibp);

            for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++) {
                  agino = be32_to_cpu(agi->agi_unlinked[bucket]);
                  while (agino != NULLAGINO) {
                        /*
                         * Release the agi buffer so that it can
                         * be acquired in the normal course of the
                         * transaction to truncate and free the inode.
                         */
                        xfs_buf_relse(agibp);

                        agino = xlog_recover_process_one_iunlink(mp,
                                          agno, agino, bucket);

                        /*
                         * Reacquire the agibuffer and continue around
                         * the loop. This should never fail as we know
                         * the buffer was good earlier on.
                         */
                        error = xfs_read_agi(mp, NULL, agno, &agibp);
                        ASSERT(error == 0);
                        agi = XFS_BUF_TO_AGI(agibp);
                  }
            }

            /*
             * Release the buffer for the current agi so we can
             * go on to the next one.
             */
            xfs_buf_relse(agibp);
      }

      mp->m_dmevmask = mp_dmevmask;
}


#ifdef DEBUG
STATIC void
xlog_pack_data_checksum(
      xlog_t            *log,
      xlog_in_core_t    *iclog,
      int         size)
{
      int         i;
      __be32            *up;
      uint        chksum = 0;

      up = (__be32 *)iclog->ic_datap;
      /* divide length by 4 to get # words */
      for (i = 0; i < (size >> 2); i++) {
            chksum ^= be32_to_cpu(*up);
            up++;
      }
      iclog->ic_header.h_chksum = cpu_to_be32(chksum);
}
#else
#define xlog_pack_data_checksum(log, iclog, size)
#endif

/*
 * Stamp cycle number in every block
 */
void
xlog_pack_data(
      xlog_t                  *log,
      xlog_in_core_t          *iclog,
      int               roundoff)
{
      int               i, j, k;
      int               size = iclog->ic_offset + roundoff;
      __be32                  cycle_lsn;
      xfs_caddr_t       dp;

      xlog_pack_data_checksum(log, iclog, size);

      cycle_lsn = CYCLE_LSN_DISK(iclog->ic_header.h_lsn);

      dp = iclog->ic_datap;
      for (i = 0; i < BTOBB(size) &&
            i < (XLOG_HEADER_CYCLE_SIZE / BBSIZE); i++) {
            iclog->ic_header.h_cycle_data[i] = *(__be32 *)dp;
            *(__be32 *)dp = cycle_lsn;
            dp += BBSIZE;
      }

      if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
            xlog_in_core_2_t *xhdr = iclog->ic_data;

            for ( ; i < BTOBB(size); i++) {
                  j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
                  k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
                  xhdr[j].hic_xheader.xh_cycle_data[k] = *(__be32 *)dp;
                  *(__be32 *)dp = cycle_lsn;
                  dp += BBSIZE;
            }

            for (i = 1; i < log->l_iclog_heads; i++) {
                  xhdr[i].hic_xheader.xh_cycle = cycle_lsn;
            }
      }
}

#if defined(DEBUG) && defined(XFS_LOUD_RECOVERY)
STATIC void
xlog_unpack_data_checksum(
      xlog_rec_header_t *rhead,
      xfs_caddr_t       dp,
      xlog_t                  *log)
{
      __be32                  *up = (__be32 *)dp;
      uint              chksum = 0;
      int               i;

      /* divide length by 4 to get # words */
      for (i=0; i < be32_to_cpu(rhead->h_len) >> 2; i++) {
            chksum ^= be32_to_cpu(*up);
            up++;
      }
      if (chksum != be32_to_cpu(rhead->h_chksum)) {
          if (rhead->h_chksum ||
            ((log->l_flags & XLOG_CHKSUM_MISMATCH) == 0)) {
                cmn_err(CE_DEBUG,
                  "XFS: LogR chksum mismatch: was (0x%x) is (0x%x)\n",
                      be32_to_cpu(rhead->h_chksum), chksum);
                cmn_err(CE_DEBUG,
"XFS: Disregard message if filesystem was created with non-DEBUG kernel");
                if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
                      cmn_err(CE_DEBUG,
                        "XFS: LogR this is a LogV2 filesystem\n");
                }
                log->l_flags |= XLOG_CHKSUM_MISMATCH;
          }
      }
}
#else
#define xlog_unpack_data_checksum(rhead, dp, log)
#endif

STATIC void
xlog_unpack_data(
      xlog_rec_header_t *rhead,
      xfs_caddr_t       dp,
      xlog_t                  *log)
{
      int               i, j, k;

      for (i = 0; i < BTOBB(be32_to_cpu(rhead->h_len)) &&
              i < (XLOG_HEADER_CYCLE_SIZE / BBSIZE); i++) {
            *(__be32 *)dp = *(__be32 *)&rhead->h_cycle_data[i];
            dp += BBSIZE;
      }

      if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
            xlog_in_core_2_t *xhdr = (xlog_in_core_2_t *)rhead;
            for ( ; i < BTOBB(be32_to_cpu(rhead->h_len)); i++) {
                  j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
                  k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
                  *(__be32 *)dp = xhdr[j].hic_xheader.xh_cycle_data[k];
                  dp += BBSIZE;
            }
      }

      xlog_unpack_data_checksum(rhead, dp, log);
}

STATIC int
xlog_valid_rec_header(
      xlog_t                  *log,
      xlog_rec_header_t *rhead,
      xfs_daddr_t       blkno)
{
      int               hlen;

      if (unlikely(be32_to_cpu(rhead->h_magicno) != XLOG_HEADER_MAGIC_NUM)) {
            XFS_ERROR_REPORT("xlog_valid_rec_header(1)",
                        XFS_ERRLEVEL_LOW, log->l_mp);
            return XFS_ERROR(EFSCORRUPTED);
      }
      if (unlikely(
          (!rhead->h_version ||
          (be32_to_cpu(rhead->h_version) & (~XLOG_VERSION_OKBITS))))) {
            xlog_warn("XFS: %s: unrecognised log version (%d).",
                  __func__, be32_to_cpu(rhead->h_version));
            return XFS_ERROR(EIO);
      }

      /* LR body must have data or it wouldn't have been written */
      hlen = be32_to_cpu(rhead->h_len);
      if (unlikely( hlen <= 0 || hlen > INT_MAX )) {
            XFS_ERROR_REPORT("xlog_valid_rec_header(2)",
                        XFS_ERRLEVEL_LOW, log->l_mp);
            return XFS_ERROR(EFSCORRUPTED);
      }
      if (unlikely( blkno > log->l_logBBsize || blkno > INT_MAX )) {
            XFS_ERROR_REPORT("xlog_valid_rec_header(3)",
                        XFS_ERRLEVEL_LOW, log->l_mp);
            return XFS_ERROR(EFSCORRUPTED);
      }
      return 0;
}

/*
 * Read the log from tail to head and process the log records found.
 * Handle the two cases where the tail and head are in the same cycle
 * and where the active portion of the log wraps around the end of
 * the physical log separately.  The pass parameter is passed through
 * to the routines called to process the data and is not looked at
 * here.
 */
STATIC int
xlog_do_recovery_pass(
      xlog_t                  *log,
      xfs_daddr_t       head_blk,
      xfs_daddr_t       tail_blk,
      int               pass)
{
      xlog_rec_header_t *rhead;
      xfs_daddr_t       blk_no;
      xfs_caddr_t       bufaddr, offset;
      xfs_buf_t         *hbp, *dbp;
      int               error = 0, h_size;
      int               bblks, split_bblks;
      int               hblks, split_hblks, wrapped_hblks;
      xlog_recover_t          *rhash[XLOG_RHASH_SIZE];

      ASSERT(head_blk != tail_blk);

      /*
       * Read the header of the tail block and get the iclog buffer size from
       * h_size.  Use this to tell how many sectors make up the log header.
       */
      if (xfs_sb_version_haslogv2(&log->l_mp->m_sb)) {
            /*
             * When using variable length iclogs, read first sector of
             * iclog header and extract the header size from it.  Get a
             * new hbp that is the correct size.
             */
            hbp = xlog_get_bp(log, 1);
            if (!hbp)
                  return ENOMEM;

            error = xlog_bread(log, tail_blk, 1, hbp, &offset);
            if (error)
                  goto bread_err1;

            rhead = (xlog_rec_header_t *)offset;
            error = xlog_valid_rec_header(log, rhead, tail_blk);
            if (error)
                  goto bread_err1;
            h_size = be32_to_cpu(rhead->h_size);
            if ((be32_to_cpu(rhead->h_version) & XLOG_VERSION_2) &&
                (h_size > XLOG_HEADER_CYCLE_SIZE)) {
                  hblks = h_size / XLOG_HEADER_CYCLE_SIZE;
                  if (h_size % XLOG_HEADER_CYCLE_SIZE)
                        hblks++;
                  xlog_put_bp(hbp);
                  hbp = xlog_get_bp(log, hblks);
            } else {
                  hblks = 1;
            }
      } else {
            ASSERT(log->l_sectbb_log == 0);
            hblks = 1;
            hbp = xlog_get_bp(log, 1);
            h_size = XLOG_BIG_RECORD_BSIZE;
      }

      if (!hbp)
            return ENOMEM;
      dbp = xlog_get_bp(log, BTOBB(h_size));
      if (!dbp) {
            xlog_put_bp(hbp);
            return ENOMEM;
      }

      memset(rhash, 0, sizeof(rhash));
      if (tail_blk <= head_blk) {
            for (blk_no = tail_blk; blk_no < head_blk; ) {
                  error = xlog_bread(log, blk_no, hblks, hbp, &offset);
                  if (error)
                        goto bread_err2;

                  rhead = (xlog_rec_header_t *)offset;
                  error = xlog_valid_rec_header(log, rhead, blk_no);
                  if (error)
                        goto bread_err2;

                  /* blocks in data section */
                  bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
                  error = xlog_bread(log, blk_no + hblks, bblks, dbp,
                                 &offset);
                  if (error)
                        goto bread_err2;

                  xlog_unpack_data(rhead, offset, log);
                  if ((error = xlog_recover_process_data(log,
                                    rhash, rhead, offset, pass)))
                        goto bread_err2;
                  blk_no += bblks + hblks;
            }
      } else {
            /*
             * Perform recovery around the end of the physical log.
             * When the head is not on the same cycle number as the tail,
             * we can't do a sequential recovery as above.
             */
            blk_no = tail_blk;
            while (blk_no < log->l_logBBsize) {
                  /*
                   * Check for header wrapping around physical end-of-log
                   */
                  offset = NULL;
                  split_hblks = 0;
                  wrapped_hblks = 0;
                  if (blk_no + hblks <= log->l_logBBsize) {
                        /* Read header in one read */
                        error = xlog_bread(log, blk_no, hblks, hbp,
                                       &offset);
                        if (error)
                              goto bread_err2;
                  } else {
                        /* This LR is split across physical log end */
                        if (blk_no != log->l_logBBsize) {
                              /* some data before physical log end */
                              ASSERT(blk_no <= INT_MAX);
                              split_hblks = log->l_logBBsize - (int)blk_no;
                              ASSERT(split_hblks > 0);
                              error = xlog_bread(log, blk_no,
                                             split_hblks, hbp,
                                             &offset);
                              if (error)
                                    goto bread_err2;
                        }

                        /*
                         * Note: this black magic still works with
                         * large sector sizes (non-512) only because:
                         * - we increased the buffer size originally
                         *   by 1 sector giving us enough extra space
                         *   for the second read;
                         * - the log start is guaranteed to be sector
                         *   aligned;
                         * - we read the log end (LR header start)
                         *   _first_, then the log start (LR header end)
                         *   - order is important.
                         */
                        wrapped_hblks = hblks - split_hblks;
                        bufaddr = XFS_BUF_PTR(hbp);
                        error = XFS_BUF_SET_PTR(hbp,
                                    bufaddr + BBTOB(split_hblks),
                                    BBTOB(hblks - split_hblks));
                        if (error)
                              goto bread_err2;

                        error = xlog_bread_noalign(log, 0,
                                             wrapped_hblks, hbp);
                        if (error)
                              goto bread_err2;

                        error = XFS_BUF_SET_PTR(hbp, bufaddr,
                                          BBTOB(hblks));
                        if (error)
                              goto bread_err2;

                        if (!offset)
                              offset = xlog_align(log, 0,
                                          wrapped_hblks, hbp);
                  }
                  rhead = (xlog_rec_header_t *)offset;
                  error = xlog_valid_rec_header(log, rhead,
                                    split_hblks ? blk_no : 0);
                  if (error)
                        goto bread_err2;

                  bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
                  blk_no += hblks;

                  /* Read in data for log record */
                  if (blk_no + bblks <= log->l_logBBsize) {
                        error = xlog_bread(log, blk_no, bblks, dbp,
                                       &offset);
                        if (error)
                              goto bread_err2;
                  } else {
                        /* This log record is split across the
                         * physical end of log */
                        offset = NULL;
                        split_bblks = 0;
                        if (blk_no != log->l_logBBsize) {
                              /* some data is before the physical
                               * end of log */
                              ASSERT(!wrapped_hblks);
                              ASSERT(blk_no <= INT_MAX);
                              split_bblks =
                                    log->l_logBBsize - (int)blk_no;
                              ASSERT(split_bblks > 0);
                              error = xlog_bread(log, blk_no,
                                          split_bblks, dbp,
                                          &offset);
                              if (error)
                                    goto bread_err2;
                        }

                        /*
                         * Note: this black magic still works with
                         * large sector sizes (non-512) only because:
                         * - we increased the buffer size originally
                         *   by 1 sector giving us enough extra space
                         *   for the second read;
                         * - the log start is guaranteed to be sector
                         *   aligned;
                         * - we read the log end (LR header start)
                         *   _first_, then the log start (LR header end)
                         *   - order is important.
                         */
                        bufaddr = XFS_BUF_PTR(dbp);
                        error = XFS_BUF_SET_PTR(dbp,
                                    bufaddr + BBTOB(split_bblks),
                                    BBTOB(bblks - split_bblks));
                        if (error)
                              goto bread_err2;

                        error = xlog_bread_noalign(log, wrapped_hblks,
                                    bblks - split_bblks,
                                    dbp);
                        if (error)
                              goto bread_err2;

                        error = XFS_BUF_SET_PTR(dbp, bufaddr, h_size);
                        if (error)
                              goto bread_err2;

                        if (!offset)
                              offset = xlog_align(log, wrapped_hblks,
                                    bblks - split_bblks, dbp);
                  }
                  xlog_unpack_data(rhead, offset, log);
                  if ((error = xlog_recover_process_data(log, rhash,
                                          rhead, offset, pass)))
                        goto bread_err2;
                  blk_no += bblks;
            }

            ASSERT(blk_no >= log->l_logBBsize);
            blk_no -= log->l_logBBsize;

            /* read first part of physical log */
            while (blk_no < head_blk) {
                  error = xlog_bread(log, blk_no, hblks, hbp, &offset);
                  if (error)
                        goto bread_err2;

                  rhead = (xlog_rec_header_t *)offset;
                  error = xlog_valid_rec_header(log, rhead, blk_no);
                  if (error)
                        goto bread_err2;

                  bblks = (int)BTOBB(be32_to_cpu(rhead->h_len));
                  error = xlog_bread(log, blk_no+hblks, bblks, dbp,
                                 &offset);
                  if (error)
                        goto bread_err2;

                  xlog_unpack_data(rhead, offset, log);
                  if ((error = xlog_recover_process_data(log, rhash,
                                          rhead, offset, pass)))
                        goto bread_err2;
                  blk_no += bblks + hblks;
            }
      }

 bread_err2:
      xlog_put_bp(dbp);
 bread_err1:
      xlog_put_bp(hbp);
      return error;
}

/*
 * Do the recovery of the log.  We actually do this in two phases.
 * The two passes are necessary in order to implement the function
 * of cancelling a record written into the log.  The first pass
 * determines those things which have been cancelled, and the
 * second pass replays log items normally except for those which
 * have been cancelled.  The handling of the replay and cancellations
 * takes place in the log item type specific routines.
 *
 * The table of items which have cancel records in the log is allocated
 * and freed at this level, since only here do we know when all of
 * the log recovery has been completed.
 */
STATIC int
xlog_do_log_recovery(
      xlog_t            *log,
      xfs_daddr_t head_blk,
      xfs_daddr_t tail_blk)
{
      int         error;

      ASSERT(head_blk != tail_blk);

      /*
       * First do a pass to find all of the cancelled buf log items.
       * Store them in the buf_cancel_table for use in the second pass.
       */
      log->l_buf_cancel_table =
            (xfs_buf_cancel_t **)kmem_zalloc(XLOG_BC_TABLE_SIZE *
                                     sizeof(xfs_buf_cancel_t*),
                                     KM_SLEEP);
      error = xlog_do_recovery_pass(log, head_blk, tail_blk,
                              XLOG_RECOVER_PASS1);
      if (error != 0) {
            kmem_free(log->l_buf_cancel_table);
            log->l_buf_cancel_table = NULL;
            return error;
      }
      /*
       * Then do a second pass to actually recover the items in the log.
       * When it is complete free the table of buf cancel items.
       */
      error = xlog_do_recovery_pass(log, head_blk, tail_blk,
                              XLOG_RECOVER_PASS2);
#ifdef DEBUG
      if (!error) {
            int   i;

            for (i = 0; i < XLOG_BC_TABLE_SIZE; i++)
                  ASSERT(log->l_buf_cancel_table[i] == NULL);
      }
#endif      /* DEBUG */

      kmem_free(log->l_buf_cancel_table);
      log->l_buf_cancel_table = NULL;

      return error;
}

/*
 * Do the actual recovery
 */
STATIC int
xlog_do_recover(
      xlog_t            *log,
      xfs_daddr_t head_blk,
      xfs_daddr_t tail_blk)
{
      int         error;
      xfs_buf_t   *bp;
      xfs_sb_t    *sbp;

      /*
       * First replay the images in the log.
       */
      error = xlog_do_log_recovery(log, head_blk, tail_blk);
      if (error) {
            return error;
      }

      XFS_bflush(log->l_mp->m_ddev_targp);

      /*
       * If IO errors happened during recovery, bail out.
       */
      if (XFS_FORCED_SHUTDOWN(log->l_mp)) {
            return (EIO);
      }

      /*
       * We now update the tail_lsn since much of the recovery has completed
       * and there may be space available to use.  If there were no extent
       * or iunlinks, we can free up the entire log and set the tail_lsn to
       * be the last_sync_lsn.  This was set in xlog_find_tail to be the
       * lsn of the last known good LR on disk.  If there are extent frees
       * or iunlinks they will have some entries in the AIL; so we look at
       * the AIL to determine how to set the tail_lsn.
       */
      xlog_assign_tail_lsn(log->l_mp);

      /*
       * Now that we've finished replaying all buffer and inode
       * updates, re-read in the superblock.
       */
      bp = xfs_getsb(log->l_mp, 0);
      XFS_BUF_UNDONE(bp);
      ASSERT(!(XFS_BUF_ISWRITE(bp)));
      ASSERT(!(XFS_BUF_ISDELAYWRITE(bp)));
      XFS_BUF_READ(bp);
      XFS_BUF_UNASYNC(bp);
      xfsbdstrat(log->l_mp, bp);
      error = xfs_iowait(bp);
      if (error) {
            xfs_ioerror_alert("xlog_do_recover",
                          log->l_mp, bp, XFS_BUF_ADDR(bp));
            ASSERT(0);
            xfs_buf_relse(bp);
            return error;
      }

      /* Convert superblock from on-disk format */
      sbp = &log->l_mp->m_sb;
      xfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(bp));
      ASSERT(sbp->sb_magicnum == XFS_SB_MAGIC);
      ASSERT(xfs_sb_good_version(sbp));
      xfs_buf_relse(bp);

      /* We've re-read the superblock so re-initialize per-cpu counters */
      xfs_icsb_reinit_counters(log->l_mp);

      xlog_recover_check_summary(log);

      /* Normal transactions can now occur */
      log->l_flags &= ~XLOG_ACTIVE_RECOVERY;
      return 0;
}

/*
 * Perform recovery and re-initialize some log variables in xlog_find_tail.
 *
 * Return error or zero.
 */
int
xlog_recover(
      xlog_t            *log)
{
      xfs_daddr_t head_blk, tail_blk;
      int         error;

      /* find the tail of the log */
      if ((error = xlog_find_tail(log, &head_blk, &tail_blk)))
            return error;

      if (tail_blk != head_blk) {
            /* There used to be a comment here:
             *
             * disallow recovery on read-only mounts.  note -- mount
             * checks for ENOSPC and turns it into an intelligent
             * error message.
             * ...but this is no longer true.  Now, unless you specify
             * NORECOVERY (in which case this function would never be
             * called), we just go ahead and recover.  We do this all
             * under the vfs layer, so we can get away with it unless
             * the device itself is read-only, in which case we fail.
             */
            if ((error = xfs_dev_is_read_only(log->l_mp, "recovery"))) {
                  return error;
            }

            cmn_err(CE_NOTE,
                  "Starting XFS recovery on filesystem: %s (logdev: %s)",
                  log->l_mp->m_fsname, log->l_mp->m_logname ?
                  log->l_mp->m_logname : "internal");

            error = xlog_do_recover(log, head_blk, tail_blk);
            log->l_flags |= XLOG_RECOVERY_NEEDED;
      }
      return error;
}

/*
 * In the first part of recovery we replay inodes and buffers and build
 * up the list of extent free items which need to be processed.  Here
 * we process the extent free items and clean up the on disk unlinked
 * inode lists.  This is separated from the first part of recovery so
 * that the root and real-time bitmap inodes can be read in from disk in
 * between the two stages.  This is necessary so that we can free space
 * in the real-time portion of the file system.
 */
int
xlog_recover_finish(
      xlog_t            *log)
{
      /*
       * Now we're ready to do the transactions needed for the
       * rest of recovery.  Start with completing all the extent
       * free intent records and then process the unlinked inode
       * lists.  At this point, we essentially run in normal mode
       * except that we're still performing recovery actions
       * rather than accepting new requests.
       */
      if (log->l_flags & XLOG_RECOVERY_NEEDED) {
            int   error;
            error = xlog_recover_process_efis(log);
            if (error) {
                  cmn_err(CE_ALERT,
                        "Failed to recover EFIs on filesystem: %s",
                        log->l_mp->m_fsname);
                  return error;
            }
            /*
             * Sync the log to get all the EFIs out of the AIL.
             * This isn't absolutely necessary, but it helps in
             * case the unlink transactions would have problems
             * pushing the EFIs out of the way.
             */
            xfs_log_force(log->l_mp, (xfs_lsn_t)0,
                        (XFS_LOG_FORCE | XFS_LOG_SYNC));

            xlog_recover_process_iunlinks(log);

            xlog_recover_check_summary(log);

            cmn_err(CE_NOTE,
                  "Ending XFS recovery on filesystem: %s (logdev: %s)",
                  log->l_mp->m_fsname, log->l_mp->m_logname ?
                  log->l_mp->m_logname : "internal");
            log->l_flags &= ~XLOG_RECOVERY_NEEDED;
      } else {
            cmn_err(CE_DEBUG,
                  "!Ending clean XFS mount for filesystem: %s\n",
                  log->l_mp->m_fsname);
      }
      return 0;
}


#if defined(DEBUG)
/*
 * Read all of the agf and agi counters and check that they
 * are consistent with the superblock counters.
 */
void
xlog_recover_check_summary(
      xlog_t            *log)
{
      xfs_mount_t *mp;
      xfs_agf_t   *agfp;
      xfs_buf_t   *agfbp;
      xfs_buf_t   *agibp;
      xfs_buf_t   *sbbp;
#ifdef XFS_LOUD_RECOVERY
      xfs_sb_t    *sbp;
#endif
      xfs_agnumber_t    agno;
      __uint64_t  freeblks;
      __uint64_t  itotal;
      __uint64_t  ifree;
      int         error;

      mp = log->l_mp;

      freeblks = 0LL;
      itotal = 0LL;
      ifree = 0LL;
      for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
            error = xfs_read_agf(mp, NULL, agno, 0, &agfbp);
            if (error) {
                  xfs_fs_cmn_err(CE_ALERT, mp,
                              "xlog_recover_check_summary(agf)"
                              "agf read failed agno %d error %d",
                                          agno, error);
            } else {
                  agfp = XFS_BUF_TO_AGF(agfbp);
                  freeblks += be32_to_cpu(agfp->agf_freeblks) +
                            be32_to_cpu(agfp->agf_flcount);
                  xfs_buf_relse(agfbp);
            }

            error = xfs_read_agi(mp, NULL, agno, &agibp);
            if (!error) {
                  struct xfs_agi    *agi = XFS_BUF_TO_AGI(agibp);

                  itotal += be32_to_cpu(agi->agi_count);
                  ifree += be32_to_cpu(agi->agi_freecount);
                  xfs_buf_relse(agibp);
            }
      }

      sbbp = xfs_getsb(mp, 0);
#ifdef XFS_LOUD_RECOVERY
      sbp = &mp->m_sb;
      xfs_sb_from_disk(sbp, XFS_BUF_TO_SBP(sbbp));
      cmn_err(CE_NOTE,
            "xlog_recover_check_summary: sb_icount %Lu itotal %Lu",
            sbp->sb_icount, itotal);
      cmn_err(CE_NOTE,
            "xlog_recover_check_summary: sb_ifree %Lu itotal %Lu",
            sbp->sb_ifree, ifree);
      cmn_err(CE_NOTE,
            "xlog_recover_check_summary: sb_fdblocks %Lu freeblks %Lu",
            sbp->sb_fdblocks, freeblks);
#if 0
      /*
       * This is turned off until I account for the allocation
       * btree blocks which live in free space.
       */
      ASSERT(sbp->sb_icount == itotal);
      ASSERT(sbp->sb_ifree == ifree);
      ASSERT(sbp->sb_fdblocks == freeblks);
#endif
#endif
      xfs_buf_relse(sbbp);
}
#endif /* DEBUG */

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