Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 4098 insertions, 0 deletions

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
new file mode 100644
index 000000000000..9824b5bf0ec0
--- /dev/null
+++ b/fs/xfs/xfs_log_recover.c
@@ -0,0 +1,4098 @@
+/*
+ * Copyright (c) 2000-2003 Silicon Graphics, Inc.  All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of version 2 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.
+ *
+ * Further, this software is distributed without any warranty that it is
+ * free of the rightful claim of any third person regarding infringement
+ * or the like.  Any license provided herein, whether implied or
+ * otherwise, applies only to this software file.  Patent licenses, if
+ * any, provided herein do not apply to combinations of this program with
+ * other software, or any other product whatsoever.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write the Free Software Foundation, Inc., 59
+ * Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
+ * Mountain View, CA  94043, or:
+ *
+ * http://www.sgi.com
+ *
+ * For further information regarding this notice, see:
+ *
+ * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
+ */
+
+#include "xfs.h"
+#include "xfs_macros.h"
+#include "xfs_types.h"
+#include "xfs_inum.h"
+#include "xfs_log.h"
+#include "xfs_ag.h"
+#include "xfs_sb.h"
+#include "xfs_trans.h"
+#include "xfs_dir.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.h"
+#include "xfs_attr_sf.h"
+#include "xfs_dir_sf.h"
+#include "xfs_dir2_sf.h"
+#include "xfs_dinode.h"
+#include "xfs_imap.h"
+#include "xfs_inode_item.h"
+#include "xfs_inode.h"
+#include "xfs_ialloc_btree.h"
+#include "xfs_ialloc.h"
+#include "xfs_log_priv.h"
+#include "xfs_buf_item.h"
+#include "xfs_alloc_btree.h"
+#include "xfs_log_recover.h"
+#include "xfs_extfree_item.h"
+#include "xfs_trans_priv.h"
+#include "xfs_bit.h"
+#include "xfs_quota.h"
+#include "xfs_rw.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 *);
+STATIC void	xlog_recover_check_ail(xfs_mount_t *, xfs_log_item_t *, int);
+#else
+#define	xlog_recover_check_summary(log)
+#define	xlog_recover_check_ail(mp, lip, gen)
+#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		num_bblks)
+{
+	ASSERT(num_bblks > 0);
+
+	if (log->l_sectbb_log) {
+		if (num_bblks > 1)
+			num_bblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
+		num_bblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, num_bblks);
+	}
+	return xfs_buf_get_noaddr(BBTOB(num_bblks), log->l_mp->m_logdev_targp);
+}
+
+void
+xlog_put_bp(
+	xfs_buf_t	*bp)
+{
+	xfs_buf_free(bp);
+}
+
+
+/*
+ * nbblks should be uint, but oh well.  Just want to catch that 32-bit length.
+ */
+int
+xlog_bread(
+	xlog_t		*log,
+	xfs_daddr_t	blk_no,
+	int		nbblks,
+	xfs_buf_t	*bp)
+{
+	int		error;
+
+	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);
+	if ((error = xfs_iowait(bp)))
+		xfs_ioerror_alert("xlog_bread", log->l_mp,
+				  bp, XFS_BUF_ADDR(bp));
+	return error;
+}
+
+/*
+ * 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.
+ */
+int
+xlog_bwrite(
+	xlog_t		*log,
+	xfs_daddr_t	blk_no,
+	int		nbblks,
+	xfs_buf_t	*bp)
+{
+	int		error;
+
+	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;
+}
+
+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;
+}
+
+#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;
+
+	printk("%s:  SB : uuid = ", __FUNCTION__);
+	for (b = 0; b < 16; b++)
+		printk("%02x",((unsigned char *)&mp->m_sb.sb_uuid)[b]);
+	printk(", fmt = %d\n", XLOG_FMT);
+	printk("    log : uuid = ");
+	for (b = 0; b < 16; b++)
+		printk("%02x",((unsigned char *)&head->h_fs_uuid)[b]);
+	printk(", fmt = %d\n", INT_GET(head->h_fmt, ARCH_CONVERT));
+}
+#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(INT_GET(head->h_magicno, ARCH_CONVERT) == 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(INT_GET(head->h_fmt, ARCH_CONVERT) != 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(INT_GET(head->h_magicno, ARCH_CONVERT) == 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)
+{
+	xfs_mount_t	*mp;
+
+	ASSERT(XFS_BUF_FSPRIVATE(bp, void *));
+
+	if (XFS_BUF_GETERROR(bp)) {
+		/*
+		 * We're not going to bother about retrying
+		 * this during recovery. One strike!
+		 */
+		mp = XFS_BUF_FSPRIVATE(bp, xfs_mount_t *);
+		xfs_ioerror_alert("xlog_recover_iodone",
+				  mp, bp, XFS_BUF_ADDR(bp));
+		xfs_force_shutdown(mp, XFS_METADATA_IO_ERROR);
+	}
+	XFS_BUF_SET_FSPRIVATE(bp, 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.
+ */
+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) {
+		if ((error = xlog_bread(log, mid_blk, 1, bp)))
+			return error;
+		offset = xlog_align(log, mid_blk, 1, bp);
+		mid_cycle = GET_CYCLE(offset, ARCH_CONVERT);
+		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));
+
+		if ((error = xlog_bread(log, i, bcount, bp)))
+			goto out;
+
+		buf = xlog_align(log, i, bcount, bp);
+		for (j = 0; j < bcount; j++) {
+			cycle = GET_CYCLE(buf, ARCH_CONVERT);
+			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 {
+		if ((error = xlog_bread(log, start_blk, num_blks, bp)))
+			goto out;
+		offset = xlog_align(log, start_blk, num_blks, bp);
+		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) {
+			if ((error = xlog_bread(log, i, 1, bp)))
+				goto out;
+			offset = xlog_align(log, i, 1, bp);
+		}
+
+		head = (xlog_rec_header_t *)offset;
+
+		if (XLOG_HEADER_MAGIC_NUM ==
+		    INT_GET(head->h_magicno, ARCH_CONVERT))
+			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 = INT_GET(head->h_size, ARCH_CONVERT);
+
+		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(INT_GET(head->h_len, ARCH_CONVERT)) + 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.
+ */
+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;
+	if ((error = xlog_bread(log, 0, 1, bp)))
+		goto bp_err;
+	offset = xlog_align(log, 0, 1, bp);
+	first_half_cycle = GET_CYCLE(offset, ARCH_CONVERT);
+
+	last_blk = head_blk = log_bbnum - 1;	/* get cycle # of last block */
+	if ((error = xlog_bread(log, last_blk, 1, bp)))
+		goto bp_err;
+	offset = xlog_align(log, last_blk, 1, bp);
+	last_half_cycle = GET_CYCLE(offset, ARCH_CONVERT);
+	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 somwhere 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,
+	int			readonly)
+{
+	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 */
+		if ((error = xlog_bread(log, 0, 1, bp)))
+			goto bread_err;
+		offset = xlog_align(log, 0, 1, bp);
+		if (GET_CYCLE(offset, ARCH_CONVERT) == 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--) {
+		if ((error = xlog_bread(log, i, 1, bp)))
+			goto bread_err;
+		offset = xlog_align(log, i, 1, bp);
+		if (XLOG_HEADER_MAGIC_NUM ==
+		    INT_GET(*(uint *)offset, ARCH_CONVERT)) {
+			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--) {
+			if ((error = xlog_bread(log, i, 1, bp)))
+				goto bread_err;
+			offset = xlog_align(log, i, 1, bp);
+			if (XLOG_HEADER_MAGIC_NUM ==
+			    INT_GET(*(uint*)offset, ARCH_CONVERT)) {
+				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(INT_GET(rhead->h_tail_lsn, ARCH_CONVERT));
+
+	/*
+	 * 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 = INT_GET(rhead->h_cycle, ARCH_CONVERT);
+	if (found == 2)
+		log->l_curr_cycle++;
+	log->l_tail_lsn = INT_GET(rhead->h_tail_lsn, ARCH_CONVERT);
+	log->l_last_sync_lsn = INT_GET(rhead->h_lsn, ARCH_CONVERT);
+	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 = INT_GET(rhead->h_size, ARCH_CONVERT);
+		int	h_version = INT_GET(rhead->h_version, ARCH_CONVERT);
+
+		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(INT_GET(rhead->h_len, ARCH_CONVERT))) % log->l_logBBsize;
+	tail_lsn = log->l_tail_lsn;
+	if (*head_blk == after_umount_blk &&
+	    INT_GET(rhead->h_num_logops, ARCH_CONVERT) == 1) {
+		umount_data_blk = (i + hblks) % log->l_logBBsize;
+		if ((error = xlog_bread(log, umount_data_blk, 1, bp))) {
+			goto bread_err;
+		}
+		offset = xlog_align(log, umount_data_blk, 1, bp);
+		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.
+			 */
+			ASSIGN_ANY_LSN_HOST(log->l_tail_lsn, log->l_curr_cycle,
+					after_umount_blk);
+			ASSIGN_ANY_LSN_HOST(log->l_last_sync_lsn, log->l_curr_cycle,
+					after_umount_blk);
+			*tail_blk = after_umount_blk;
+		}
+	}
+
+	/*
+	 * 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
+ */
+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;
+
+	/* check totally zeroed log */
+	bp = xlog_get_bp(log, 1);
+	if (!bp)
+		return ENOMEM;
+	if ((error = xlog_bread(log, 0, 1, bp)))
+		goto bp_err;
+	offset = xlog_align(log, 0, 1, bp);
+	first_cycle = GET_CYCLE(offset, ARCH_CONVERT);
+	if (first_cycle == 0) {		/* completely zeroed log */
+		*blk_no = 0;
+		xlog_put_bp(bp);
+		return -1;
+	}
+
+	/* check partially zeroed log */
+	if ((error = xlog_bread(log, log_bbnum-1, 1, bp)))
+		goto bp_err;
+	offset = xlog_align(log, log_bbnum-1, 1, bp);
+	last_cycle = GET_CYCLE(offset, ARCH_CONVERT);
+	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);
+	INT_SET(recp->h_magicno, ARCH_CONVERT, XLOG_HEADER_MAGIC_NUM);
+	INT_SET(recp->h_cycle, ARCH_CONVERT, cycle);
+	INT_SET(recp->h_version, ARCH_CONVERT,
+			XFS_SB_VERSION_HASLOGV2(&log->l_mp->m_sb) ? 2 : 1);
+	ASSIGN_ANY_LSN_DISK(recp->h_lsn, cycle, block);
+	ASSIGN_ANY_LSN_DISK(recp->h_tail_lsn, tail_cycle, tail_block);
+	INT_SET(recp->h_fmt, ARCH_CONVERT, 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) {
+		if ((error = xlog_bread(log, start_block, 1, bp))) {
+			xlog_put_bp(bp);
+			return error;
+		}
+		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);
+			XFS_BUF_SET_PTR(bp, offset + balign, BBTOB(sectbb));
+			if ((error = xlog_bread(log, ealign, sectbb, bp)))
+				break;
+			XFS_BUF_SET_PTR(bp, offset, bufblks);
+		}
+
+		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;
+	}
+	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 == 0) {
+		/* 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, 0);
+	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 == 0) {
+		ASSERT(*(uint *)dp == XFS_TRANS_HEADER_MAGIC);
+		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 */
+		item->ri_total	= in_f->ilf_size;
+		ASSERT(item->ri_total <= XLOG_MAX_REGIONS_IN_ITEM);
+		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 != 0);
+	if (trans == *q) {
+		*q = (*q)->r_next;
+	} else {
+		tp = *q;
+		while (tp != 0) {
+			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 == 0) {
+		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_t			*log,
+	xlog_recover_t		*trans)
+{
+	xlog_recover_item_t	*first_item, *itemq, *itemq_next;
+	xfs_buf_log_format_t	*buf_f;
+	xfs_buf_log_format_v1_t	*obuf_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;
+			break;
+		case XFS_LI_6_1_BUF:
+		case XFS_LI_5_3_BUF:
+			obuf_f = (xfs_buf_log_format_v1_t*)buf_f;
+			flags = obuf_f->blf_flags;
+			break;
+		}
+
+		switch (ITEM_TYPE(itemq)) {
+		case XFS_LI_BUF:
+		case XFS_LI_6_1_BUF:
+		case XFS_LI_5_3_BUF:
+			if (!(flags & XFS_BLI_CANCEL)) {
+				xlog_recover_insert_item_frontq(&trans->r_itemq,
+								itemq);
+				break;
+			}
+		case XFS_LI_INODE:
+		case XFS_LI_6_1_INODE:
+		case XFS_LI_5_3_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_buf_log_format_v1_t	*obuf_f;
+	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;
+	case XFS_LI_6_1_BUF:
+	case XFS_LI_5_3_BUF:
+		obuf_f = (xfs_buf_log_format_v1_t*)buf_f;
+		blkno = (xfs_daddr_t) obuf_f->blf_blkno;
+		len = obuf_f->blf_len;
+		flags = obuf_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,
+						  sizeof(xfs_buf_cancel_t));
+				}
+			}
+			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_buf_log_format_v1_t	*obuf_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;
+	case XFS_LI_6_1_BUF:
+	case XFS_LI_5_3_BUF:
+		obuf_f = (xfs_buf_log_format_v1_t*)buf_f;
+		blkno = (xfs_daddr_t) obuf_f->blf_blkno;
+		flags = obuf_f->blf_flags;
+		len = (xfs_daddr_t) obuf_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;
+	xfs_buf_log_format_v1_t	*obuf_f;
+	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;
+	case XFS_LI_6_1_BUF:
+	case XFS_LI_5_3_BUF:
+		obuf_f = (xfs_buf_log_format_v1_t*)buf_f;
+		data_map = obuf_f->blf_data_map;
+		map_size = obuf_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);
+		INT_SET(*buffer_nextp, ARCH_CONVERT, *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(
+	xfs_mount_t		*mp,
+	xlog_recover_item_t	*item,
+	xfs_buf_t		*bp,
+	xfs_buf_log_format_t	*buf_f)
+{
+	int			i;
+	int			bit;
+	int			nbits;
+	xfs_buf_log_format_v1_t	*obuf_f;
+	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;
+	case XFS_LI_6_1_BUF:
+	case XFS_LI_5_3_BUF:
+		obuf_f = (xfs_buf_log_format_v1_t*)buf_f;
+		data_map = obuf_f->blf_data_map;
+		map_size = obuf_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 != 0);
+		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_GDQUOT_BUF)) {
+			error = xfs_qm_dqcheck((xfs_disk_dquot_t *)
+					       item->ri_buf[i].i_addr,
+					       -1, 0, XFS_QMOPT_DOWARN,
+					       "dquot_buf_recover");
+		}
+		if (!error)
+			memcpy(xfs_buf_offset(bp,
+				(uint)bit << XFS_BLI_SHIFT),	/* dest */
+				item->ri_buf[i].i_addr,		/* source */
+				nbits<<XFS_BLI_SHIFT);		/* length */
+		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 (INT_GET(ddq->d_magic, ARCH_CONVERT) != 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,
+			INT_GET(ddq->d_magic, ARCH_CONVERT), XFS_DQUOT_MAGIC);
+		errs++;
+	}
+	if (INT_GET(ddq->d_version, ARCH_CONVERT) != 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,
+			INT_GET(ddq->d_magic, ARCH_CONVERT), XFS_DQUOT_VERSION);
+		errs++;
+	}
+
+	if (INT_GET(ddq->d_flags, ARCH_CONVERT) != XFS_DQ_USER &&
+	    INT_GET(ddq->d_flags, ARCH_CONVERT) != XFS_DQ_GROUP) {
+		if (flags & XFS_QMOPT_DOWARN)
+			cmn_err(CE_ALERT,
+			"%s : XFS dquot ID 0x%x, unknown flags 0x%x",
+			str, id, INT_GET(ddq->d_flags, ARCH_CONVERT));
+		errs++;
+	}
+
+	if (id != -1 && id != INT_GET(ddq->d_id, ARCH_CONVERT)) {
+		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, INT_GET(ddq->d_id, ARCH_CONVERT));
+		errs++;
+	}
+
+	if (!errs && ddq->d_id) {
+		if (INT_GET(ddq->d_blk_softlimit, ARCH_CONVERT) &&
+		    INT_GET(ddq->d_bcount, ARCH_CONVERT) >=
+				INT_GET(ddq->d_blk_softlimit, ARCH_CONVERT)) {
+			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)
+					INT_GET(ddq->d_id, ARCH_CONVERT), ddq);
+				errs++;
+			}
+		}
+		if (INT_GET(ddq->d_ino_softlimit, ARCH_CONVERT) &&
+		    INT_GET(ddq->d_icount, ARCH_CONVERT) >=
+				INT_GET(ddq->d_ino_softlimit, ARCH_CONVERT)) {
+			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)
+					INT_GET(ddq->d_id, ARCH_CONVERT), ddq);
+				errs++;
+			}
+		}
+		if (INT_GET(ddq->d_rtb_softlimit, ARCH_CONVERT) &&
+		    INT_GET(ddq->d_rtbcount, ARCH_CONVERT) >=
+				INT_GET(ddq->d_rtb_softlimit, ARCH_CONVERT)) {
+			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)
+					INT_GET(ddq->d_id, ARCH_CONVERT), 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));
+	INT_SET(d->dd_diskdq.d_magic, ARCH_CONVERT, XFS_DQUOT_MAGIC);
+	INT_SET(d->dd_diskdq.d_version, ARCH_CONVERT, XFS_DQUOT_VERSION);
+	INT_SET(d->dd_diskdq.d_id, ARCH_CONVERT, id);
+	INT_SET(d->dd_diskdq.d_flags, ARCH_CONVERT, type);
+
+	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_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(mp, 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_buf_log_format_v1_t	*obuf_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;
+	case XFS_LI_6_1_BUF:
+	case XFS_LI_5_3_BUF:
+		obuf_f = (xfs_buf_log_format_v1_t*)buf_f;
+		blkno = obuf_f->blf_blkno;
+		len = obuf_f->blf_len;
+		flags = obuf_f->blf_flags;
+		break;
+	default:
+		xfs_fs_cmn_err(CE_ALERT, log->l_mp,
+			"xfs_log_recover: unknown buffer type 0x%x, dev %s",
+			buf_f->blf_type, XFS_BUFTARG_NAME(log->l_targ));
+		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_GDQUOT_BUF)) {
+		xlog_recover_do_dquot_buffer(mp, log, item, bp, buf_f);
+	} else {
+		xlog_recover_do_reg_buffer(mp, 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 ==
+	    INT_GET(*((__uint16_t *)(xfs_buf_offset(bp, 0))), ARCH_CONVERT) &&
+	    (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(XFS_BUF_FSPRIVATE(bp, void *) == NULL ||
+		       XFS_BUF_FSPRIVATE(bp, xfs_mount_t *) == mp);
+		XFS_BUF_SET_FSPRIVATE(bp, 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_imap_t		imap;
+	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_dinode_core_t	*dicp;
+
+	if (pass == XLOG_RECOVER_PASS1) {
+		return 0;
+	}
+
+	in_f = (xfs_inode_log_format_t *)item->ri_buf[0].i_addr;
+	ino = in_f->ilf_ino;
+	mp = log->l_mp;
+	if (ITEM_TYPE(item) == XFS_LI_INODE) {
+		imap.im_blkno = (xfs_daddr_t)in_f->ilf_blkno;
+		imap.im_len = in_f->ilf_len;
+		imap.im_boffset = in_f->ilf_boffset;
+	} else {
+		/*
+		 * It's an old inode format record.  We don't know where
+		 * its cluster is located on disk, and we can't allow
+		 * xfs_imap() to figure it out because the inode btrees
+		 * are not ready to be used.  Therefore do not pass the
+		 * XFS_IMAP_LOOKUP flag to xfs_imap().  This will give
+		 * us only the single block in which the inode lives
+		 * rather than its cluster, so we must make sure to
+		 * invalidate the buffer when we write it out below.
+		 */
+		imap.im_blkno = 0;
+		xfs_imap(log->l_mp, NULL, ino, &imap, 0);
+	}
+
+	/*
+	 * Inode buffers can be freed, look out for it,
+	 * and do not replay the inode.
+	 */
+	if (xlog_check_buffer_cancelled(log, imap.im_blkno, imap.im_len, 0))
+		return 0;
+
+	bp = xfs_buf_read_flags(mp->m_ddev_targp, imap.im_blkno, imap.im_len,
+								XFS_BUF_LOCK);
+	if (XFS_BUF_ISERROR(bp)) {
+		xfs_ioerror_alert("xlog_recover_do..(read#2)", mp,
+				  bp, imap.im_blkno);
+		error = XFS_BUF_GETERROR(bp);
+		xfs_buf_relse(bp);
+		return error;
+	}
+	error = 0;
+	ASSERT(in_f->ilf_fields & XFS_ILOG_CORE);
+	dip = (xfs_dinode_t *)xfs_buf_offset(bp, imap.im_boffset);
+
+	/*
+	 * Make sure the place we're flushing out to really looks
+	 * like an inode!
+	 */
+	if (unlikely(INT_GET(dip->di_core.di_magic, ARCH_CONVERT) != 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);
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+	dicp = (xfs_dinode_core_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);
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+
+	/* Skip replay when the on disk inode is newer than the log one */
+	if (dicp->di_flushiter <
+	    INT_GET(dip->di_core.di_flushiter, ARCH_CONVERT)) {
+		/*
+		 * Deal with the wrap case, DI_MAX_FLUSH is less
+		 * than smaller numbers
+		 */
+		if ((INT_GET(dip->di_core.di_flushiter, ARCH_CONVERT)
+							== DI_MAX_FLUSH) &&
+		    (dicp->di_flushiter < (DI_MAX_FLUSH>>1))) {
+			/* do nothing */
+		} else {
+			xfs_buf_relse(bp);
+			return 0;
+		}
+	}
+	/* 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);
+			return XFS_ERROR(EFSCORRUPTED);
+		}
+	} 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);
+			return XFS_ERROR(EFSCORRUPTED);
+		}
+	}
+	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);
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+	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);
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+	if (unlikely(item->ri_buf[1].i_len > sizeof(xfs_dinode_core_t))) {
+		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);
+		return XFS_ERROR(EFSCORRUPTED);
+	}
+
+	/* The core is in in-core format */
+	xfs_xlate_dinode_core((xfs_caddr_t)&dip->di_core,
+			      (xfs_dinode_core_t*)item->ri_buf[1].i_addr, -1);
+
+	/* the rest is in on-disk format */
+	if (item->ri_buf[1].i_len > sizeof(xfs_dinode_core_t)) {
+		memcpy((xfs_caddr_t) dip + sizeof(xfs_dinode_core_t),
+			item->ri_buf[1].i_addr + sizeof(xfs_dinode_core_t),
+			item->ri_buf[1].i_len  - sizeof(xfs_dinode_core_t));
+	}
+
+	fields = in_f->ilf_fields;
+	switch (fields & (XFS_ILOG_DEV | XFS_ILOG_UUID)) {
+	case XFS_ILOG_DEV:
+		INT_SET(dip->di_u.di_dev, ARCH_CONVERT, in_f->ilf_u.ilfu_rdev);
+
+		break;
+	case XFS_ILOG_UUID:
+		dip->di_u.di_muuid = in_f->ilf_u.ilfu_uuid;
+		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(&dip->di_u, src, len);
+		break;
+
+	case XFS_ILOG_DBROOT:
+		xfs_bmbt_to_bmdr((xfs_bmbt_block_t *)src, len,
+				 &(dip->di_u.di_bmbt),
+				 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((xfs_bmbt_block_t *)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);
+			return XFS_ERROR(EIO);
+		}
+	}
+
+write_inode_buffer:
+	if (ITEM_TYPE(item) == XFS_LI_INODE) {
+		ASSERT(XFS_BUF_FSPRIVATE(bp, void *) == NULL ||
+		       XFS_BUF_FSPRIVATE(bp, xfs_mount_t *) == mp);
+		XFS_BUF_SET_FSPRIVATE(bp, mp);
+		XFS_BUF_SET_IODONE_FUNC(bp, xlog_recover_iodone);
+		xfs_bdwrite(mp, bp);
+	} else {
+		XFS_BUF_STALE(bp);
+		error = xfs_bwrite(mp, bp);
+	}
+
+	return (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 quotaoff or both.
+	 */
+	if (qoff_f->qf_flags & XFS_UQUOTA_ACCT)
+		log->l_quotaoffs_flag |= XFS_DQ_USER;
+	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;
+	ASSERT(recddq);
+	/*
+	 * This type of quotas was turned off, so ignore this record.
+	 */
+	type = INT_GET(recddq->d_flags, ARCH_CONVERT) &
+			(XFS_DQ_USER | 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(XFS_BUF_FSPRIVATE(bp, void *) == NULL ||
+	       XFS_BUF_FSPRIVATE(bp, xfs_mount_t *) == mp);
+	XFS_BUF_SET_FSPRIVATE(bp, 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 void
+xlog_recover_do_efi_trans(
+	xlog_t			*log,
+	xlog_recover_item_t	*item,
+	xfs_lsn_t		lsn,
+	int			pass)
+{
+	xfs_mount_t		*mp;
+	xfs_efi_log_item_t	*efip;
+	xfs_efi_log_format_t	*efi_formatp;
+	SPLDECL(s);
+
+	if (pass == XLOG_RECOVER_PASS1) {
+		return;
+	}
+
+	efi_formatp = (xfs_efi_log_format_t *)item->ri_buf[0].i_addr;
+	ASSERT(item->ri_buf[0].i_len ==
+	       (sizeof(xfs_efi_log_format_t) +
+		((efi_formatp->efi_nextents - 1) * sizeof(xfs_extent_t))));
+
+	mp = log->l_mp;
+	efip = xfs_efi_init(mp, efi_formatp->efi_nextents);
+	memcpy((char *)&(efip->efi_format), (char *)efi_formatp,
+	      sizeof(xfs_efi_log_format_t) +
+	      ((efi_formatp->efi_nextents - 1) * sizeof(xfs_extent_t)));
+	efip->efi_next_extent = efi_formatp->efi_nextents;
+	efip->efi_flags |= XFS_EFI_COMMITTED;
+
+	AIL_LOCK(mp,s);
+	/*
+	 * xfs_trans_update_ail() drops the AIL lock.
+	 */
+	xfs_trans_update_ail(mp, (xfs_log_item_t *)efip, lsn, s);
+}
+
+
+/*
+ * 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_mount_t		*mp;
+	xfs_efd_log_format_t	*efd_formatp;
+	xfs_efi_log_item_t	*efip = NULL;
+	xfs_log_item_t		*lip;
+	int			gen;
+	int			nexts;
+	__uint64_t		efi_id;
+	SPLDECL(s);
+
+	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_t) +
+		((efd_formatp->efd_nextents - 1) * sizeof(xfs_extent_t))));
+	efi_id = efd_formatp->efd_efi_id;
+
+	/*
+	 * Search for the efi with the id in the efd format structure
+	 * in the AIL.
+	 */
+	mp = log->l_mp;
+	AIL_LOCK(mp,s);
+	lip = xfs_trans_first_ail(mp, &gen);
+	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_delete_ail() drops the
+				 * AIL lock.
+				 */
+				xfs_trans_delete_ail(mp, lip, s);
+				break;
+			}
+		}
+		lip = xfs_trans_next_ail(mp, lip, &gen, NULL);
+	}
+	if (lip == NULL) {
+		AIL_UNLOCK(mp, s);
+	}
+
+	/*
+	 * If we found it, then free it up.  If it wasn't there, it
+	 * must have been overwritten in the log.  Oh well.
+	 */
+	if (lip != NULL) {
+		nexts = efip->efi_format.efi_nextents;
+		if (nexts > XFS_EFI_MAX_FAST_EXTENTS) {
+			kmem_free(lip, sizeof(xfs_efi_log_item_t) +
+				  ((nexts - 1) * sizeof(xfs_extent_t)));
+		} else {
+			kmem_zone_free(xfs_efi_zone, efip);
+		}
+	}
+}
+
+/*
+ * 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;
+
+	if ((error = xlog_recover_reorder_trans(log, trans)))
+		return error;
+	first_item = item = trans->r_itemq;
+	do {
+		/*
+		 * we don't need to worry about the block number being
+		 * truncated in > 1 TB buffers because in user-land,
+		 * we're now n32 or 64-bit so xfs_daddr_t is 64-bits so
+		 * the blkno's will get through the user-mode buffer
+		 * cache properly.  The only bad case is o32 kernels
+		 * where xfs_daddr_t is 32-bits but mount will warn us
+		 * off a > 1 TB filesystem before we get here.
+		 */
+		if ((ITEM_TYPE(item) == XFS_LI_BUF) ||
+		    (ITEM_TYPE(item) == XFS_LI_6_1_BUF) ||
+		    (ITEM_TYPE(item) == XFS_LI_5_3_BUF)) {
+			if  ((error = xlog_recover_do_buffer_trans(log, item,
+								 pass)))
+				break;
+		} else if ((ITEM_TYPE(item) == XFS_LI_INODE) ||
+			   (ITEM_TYPE(item) == XFS_LI_6_1_INODE) ||
+			   (ITEM_TYPE(item) == XFS_LI_5_3_INODE)) {
+			if ((error = xlog_recover_do_inode_trans(log, item,
+								pass)))
+				break;
+		} else if (ITEM_TYPE(item) == XFS_LI_EFI) {
+			xlog_recover_do_efi_trans(log, item, trans->r_lsn,
+						  pass);
+		} else if (ITEM_TYPE(item) == XFS_LI_EFD) {
+			xlog_recover_do_efd_trans(log, item, pass);
+		} else if (ITEM_TYPE(item) == XFS_LI_DQUOT) {
+			if ((error = xlog_recover_do_dquot_trans(log, item,
+								   pass)))
+					break;
+		} else if ((ITEM_TYPE(item) == XFS_LI_QUOTAOFF)) {
+			if ((error = xlog_recover_do_quotaoff_trans(log, item,
+								   pass)))
+					break;
+		} else {
+			xlog_warn("XFS: xlog_recover_do_trans");
+			ASSERT(0);
+			error = XFS_ERROR(EIO);
+			break;
+		}
+		item = item->ri_next;
+	} while (first_item != item);
+
+	return error;
+}
+
+/*
+ * 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_item->ri_buf[i].i_len);
+		}
+		/* Free the item itself */
+		kmem_free(free_item->ri_buf,
+			  (free_item->ri_total * sizeof(xfs_log_iovec_t)));
+		kmem_free(free_item, sizeof(xlog_recover_item_t));
+	} while (first_item != item);
+	/* Free the transaction recover structure */
+	kmem_free(trans, sizeof(xlog_recover_t));
+}
+
+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 + INT_GET(rhead->h_len, ARCH_CONVERT);
+	num_logops = INT_GET(rhead->h_num_logops, ARCH_CONVERT);
+
+	/* 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 = INT_GET(ohead->oh_tid, ARCH_CONVERT);
+		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,
+					INT_GET(rhead->h_lsn, ARCH_CONVERT));
+		} else {
+			ASSERT(dp+INT_GET(ohead->oh_len, ARCH_CONVERT) <= lp);
+			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, INT_GET(ohead->oh_len,
+							ARCH_CONVERT));
+				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, INT_GET(ohead->oh_len,
+							ARCH_CONVERT));
+				break;
+			default:
+				xlog_warn(
+			"XFS: xlog_recover_process_data: bad flag");
+				ASSERT(0);
+				error = XFS_ERROR(EIO);
+				break;
+			}
+			if (error)
+				return error;
+		}
+		dp += INT_GET(ohead->oh_len, ARCH_CONVERT);
+		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 void
+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;
+	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;
+		}
+	}
+
+	tp = xfs_trans_alloc(mp, 0);
+	xfs_trans_reserve(tp, 0, XFS_ITRUNCATE_LOG_RES(mp), 0, 0, 0);
+	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]);
+		xfs_free_extent(tp, extp->ext_start, extp->ext_len);
+		xfs_trans_log_efd_extent(tp, efdp, extp->ext_start,
+					 extp->ext_len);
+	}
+
+	efip->efi_flags |= XFS_EFI_RECOVERED;
+	xfs_trans_commit(tp, 0, NULL);
+}
+
+/*
+ * Verify that once we've encountered something other than an EFI
+ * in the AIL that there are no more EFIs in the AIL.
+ */
+#if defined(DEBUG)
+STATIC void
+xlog_recover_check_ail(
+	xfs_mount_t		*mp,
+	xfs_log_item_t		*lip,
+	int			gen)
+{
+	int			orig_gen = gen;
+
+	do {
+		ASSERT(lip->li_type != XFS_LI_EFI);
+		lip = xfs_trans_next_ail(mp, lip, &gen, NULL);
+		/*
+		 * The check will be bogus if we restart from the
+		 * beginning of the AIL, so ASSERT that we don't.
+		 * We never should since we're holding the AIL lock
+		 * the entire time.
+		 */
+		ASSERT(gen == orig_gen);
+	} while (lip != NULL);
+}
+#endif	/* DEBUG */
+
+/*
+ * 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 void
+xlog_recover_process_efis(
+	xlog_t			*log)
+{
+	xfs_log_item_t		*lip;
+	xfs_efi_log_item_t	*efip;
+	int			gen;
+	xfs_mount_t		*mp;
+	SPLDECL(s);
+
+	mp = log->l_mp;
+	AIL_LOCK(mp,s);
+
+	lip = xfs_trans_first_ail(mp, &gen);
+	while (lip != NULL) {
+		/*
+		 * We're done when we see something other than an EFI.
+		 */
+		if (lip->li_type != XFS_LI_EFI) {
+			xlog_recover_check_ail(mp, lip, gen);
+			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_next_ail(mp, lip, &gen, NULL);
+			continue;
+		}
+
+		AIL_UNLOCK(mp, s);
+		xlog_recover_process_efi(mp, efip);
+		AIL_LOCK(mp,s);
+		lip = xfs_trans_next_ail(mp, lip, &gen, NULL);
+	}
+	AIL_UNLOCK(mp, s);
+}
+
+/*
+ * 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);
+	xfs_trans_reserve(tp, 0, XFS_CLEAR_AGI_BUCKET_LOG_RES(mp), 0, 0, 0);
+
+	error = xfs_trans_read_buf(mp, tp, mp->m_ddev_targp,
+				   XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
+				   XFS_FSS_TO_BB(mp, 1), 0, &agibp);
+	if (error) {
+		xfs_trans_cancel(tp, XFS_TRANS_ABORT);
+		return;
+	}
+
+	agi = XFS_BUF_TO_AGI(agibp);
+	if (INT_GET(agi->agi_magicnum, ARCH_CONVERT) != XFS_AGI_MAGIC) {
+		xfs_trans_cancel(tp, XFS_TRANS_ABORT);
+		return;
+	}
+	ASSERT(INT_GET(agi->agi_magicnum, ARCH_CONVERT) == XFS_AGI_MAGIC);
+
+	INT_SET(agi->agi_unlinked[bucket], ARCH_CONVERT, 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));
+
+	(void) xfs_trans_commit(tp, 0, NULL);
+}
+
+/*
+ * 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_buf_t	*ibp;
+	xfs_dinode_t	*dip;
+	xfs_inode_t	*ip;
+	xfs_agino_t	agino;
+	xfs_ino_t	ino;
+	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.
+		 */
+		agibp = xfs_buf_read(mp->m_ddev_targp,
+				XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)),
+				XFS_FSS_TO_BB(mp, 1), 0);
+		if (XFS_BUF_ISERROR(agibp)) {
+			xfs_ioerror_alert("xlog_recover_process_iunlinks(#1)",
+				log->l_mp, agibp,
+				XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp)));
+		}
+		agi = XFS_BUF_TO_AGI(agibp);
+		ASSERT(XFS_AGI_MAGIC ==
+			INT_GET(agi->agi_magicnum, ARCH_CONVERT));
+
+		for (bucket = 0; bucket < XFS_AGI_UNLINKED_BUCKETS; bucket++) {
+
+			agino = INT_GET(agi->agi_unlinked[bucket], ARCH_CONVERT);
+			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);
+
+				ino = XFS_AGINO_TO_INO(mp, agno, agino);
+				error = xfs_iget(mp, NULL, ino, 0, 0, &ip, 0);
+				ASSERT(error || (ip != NULL));
+
+				if (!error) {
+					/*
+					 * Get the on disk inode to find the
+					 * next inode in the bucket.
+					 */
+					error = xfs_itobp(mp, NULL, ip, &dip,
+							&ibp, 0);
+					ASSERT(error || (dip != NULL));
+				}
+
+				if (!error) {
+					ASSERT(ip->i_d.di_nlink == 0);
+
+					/* setup for the next pass */
+					agino = INT_GET(dip->di_next_unlinked,
+							ARCH_CONVERT);
+					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;
+
+					/*
+					 * If this is a new inode, handle
+					 * it specially.  Otherwise,
+					 * just drop our reference to the
+					 * inode.  If there are no
+					 * other references, this will
+					 * send the inode to
+					 * xfs_inactive() which will
+					 * truncate the file and free
+					 * the inode.
+					 */
+					if (ip->i_d.di_mode == 0)
+						xfs_iput_new(ip, 0);
+					else
+						VN_RELE(XFS_ITOV(ip));
+				} else {
+					/*
+					 * 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);
+
+					agino = NULLAGINO;
+				}
+
+				/*
+				 * Reacquire the agibuffer and continue around
+				 * the loop.
+				 */
+				agibp = xfs_buf_read(mp->m_ddev_targp,
+						XFS_AG_DADDR(mp, agno,
+							XFS_AGI_DADDR(mp)),
+						XFS_FSS_TO_BB(mp, 1), 0);
+				if (XFS_BUF_ISERROR(agibp)) {
+					xfs_ioerror_alert(
+				"xlog_recover_process_iunlinks(#2)",
+						log->l_mp, agibp,
+						XFS_AG_DADDR(mp, agno,
+							XFS_AGI_DADDR(mp)));
+				}
+				agi = XFS_BUF_TO_AGI(agibp);
+				ASSERT(XFS_AGI_MAGIC == INT_GET(
+					agi->agi_magicnum, ARCH_CONVERT));
+			}
+		}
+
+		/*
+		 * 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;
+	uint		*up;
+	uint		chksum = 0;
+
+	up = (uint *)iclog->ic_datap;
+	/* divide length by 4 to get # words */
+	for (i = 0; i < (size >> 2); i++) {
+		chksum ^= INT_GET(*up, ARCH_CONVERT);
+		up++;
+	}
+	INT_SET(iclog->ic_header.h_chksum, ARCH_CONVERT, 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;
+	uint			cycle_lsn;
+	xfs_caddr_t		dp;
+	xlog_in_core_2_t	*xhdr;
+
+	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] = *(uint *)dp;
+		*(uint *)dp = cycle_lsn;
+		dp += BBSIZE;
+	}
+
+	if (XFS_SB_VERSION_HASLOGV2(&log->l_mp->m_sb)) {
+		xhdr = (xlog_in_core_2_t *)&iclog->ic_header;
+		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] = *(uint *)dp;
+			*(uint *)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)
+{
+	uint			*up = (uint *)dp;
+	uint			chksum = 0;
+	int			i;
+
+	/* divide length by 4 to get # words */
+	for (i=0; i < INT_GET(rhead->h_len, ARCH_CONVERT) >> 2; i++) {
+		chksum ^= INT_GET(*up, ARCH_CONVERT);
+		up++;
+	}
+	if (chksum != INT_GET(rhead->h_chksum, ARCH_CONVERT)) {
+	    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)",
+			    INT_GET(rhead->h_chksum, ARCH_CONVERT), 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");
+		    }
+		    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;
+	xlog_in_core_2_t	*xhdr;
+
+	for (i = 0; i < BTOBB(INT_GET(rhead->h_len, ARCH_CONVERT)) &&
+		  i < (XLOG_HEADER_CYCLE_SIZE / BBSIZE); i++) {
+		*(uint *)dp = *(uint *)&rhead->h_cycle_data[i];
+		dp += BBSIZE;
+	}
+
+	if (XFS_SB_VERSION_HASLOGV2(&log->l_mp->m_sb)) {
+		xhdr = (xlog_in_core_2_t *)rhead;
+		for ( ; i < BTOBB(INT_GET(rhead->h_len, ARCH_CONVERT)); i++) {
+			j = i / (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+			k = i % (XLOG_HEADER_CYCLE_SIZE / BBSIZE);
+			*(uint *)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(
+	    (INT_GET(rhead->h_magicno, ARCH_CONVERT) !=
+			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 ||
+	    (INT_GET(rhead->h_version, ARCH_CONVERT) &
+			(~XLOG_VERSION_OKBITS)) != 0))) {
+		xlog_warn("XFS: %s: unrecognised log version (%d).",
+			__FUNCTION__, INT_GET(rhead->h_version, ARCH_CONVERT));
+		return XFS_ERROR(EIO);
+	}
+
+	/* LR body must have data or it wouldn't have been written */
+	hlen = INT_GET(rhead->h_len, ARCH_CONVERT);
+	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;
+		if ((error = xlog_bread(log, tail_blk, 1, hbp)))
+			goto bread_err1;
+		offset = xlog_align(log, tail_blk, 1, hbp);
+		rhead = (xlog_rec_header_t *)offset;
+		error = xlog_valid_rec_header(log, rhead, tail_blk);
+		if (error)
+			goto bread_err1;
+		h_size = INT_GET(rhead->h_size, ARCH_CONVERT);
+		if ((INT_GET(rhead->h_version, ARCH_CONVERT)
+				& 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; ) {
+			if ((error = xlog_bread(log, blk_no, hblks, hbp)))
+				goto bread_err2;
+			offset = xlog_align(log, blk_no, hblks, hbp);
+			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(INT_GET(rhead->h_len, ARCH_CONVERT));
+			error = xlog_bread(log, blk_no + hblks, bblks, dbp);
+			if (error)
+				goto bread_err2;
+			offset = xlog_align(log, blk_no + hblks, 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 + 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);
+				if (error)
+					goto bread_err2;
+				offset = xlog_align(log, blk_no, hblks, hbp);
+			} 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);
+					if ((error = xlog_bread(log, blk_no,
+							split_hblks, hbp)))
+						goto bread_err2;
+					offset = xlog_align(log, blk_no,
+							split_hblks, hbp);
+				}
+				/*
+				 * 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(hbp);
+				XFS_BUF_SET_PTR(hbp,
+						bufaddr + BBTOB(split_hblks),
+						BBTOB(hblks - split_hblks));
+				wrapped_hblks = hblks - split_hblks;
+				error = xlog_bread(log, 0, wrapped_hblks, hbp);
+				if (error)
+					goto bread_err2;
+				XFS_BUF_SET_PTR(hbp, bufaddr, BBTOB(hblks));
+				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(INT_GET(rhead->h_len, ARCH_CONVERT));
+			blk_no += hblks;
+
+			/* Read in data for log record */
+			if (blk_no + bblks <= log->l_logBBsize) {
+				error = xlog_bread(log, blk_no, bblks, dbp);
+				if (error)
+					goto bread_err2;
+				offset = xlog_align(log, blk_no, bblks, dbp);
+			} 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);
+					if ((error = xlog_bread(log, blk_no,
+							split_bblks, dbp)))
+						goto bread_err2;
+					offset = xlog_align(log, blk_no,
+							split_bblks, dbp);
+				}
+				/*
+				 * 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);
+				XFS_BUF_SET_PTR(dbp,
+						bufaddr + BBTOB(split_bblks),
+						BBTOB(bblks - split_bblks));
+				if ((error = xlog_bread(log, wrapped_hblks,
+						bblks - split_bblks, dbp)))
+					goto bread_err2;
+				XFS_BUF_SET_PTR(dbp, bufaddr, h_size);
+				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) {
+			if ((error = xlog_bread(log, blk_no, hblks, hbp)))
+				goto bread_err2;
+			offset = xlog_align(log, blk_no, hblks, hbp);
+			rhead = (xlog_rec_header_t *)offset;
+			error = xlog_valid_rec_header(log, rhead, blk_no);
+			if (error)
+				goto bread_err2;
+			bblks = (int)BTOBB(INT_GET(rhead->h_len, ARCH_CONVERT));
+			if ((error = xlog_bread(log, blk_no+hblks, bblks, dbp)))
+				goto bread_err2;
+			offset = xlog_align(log, blk_no+hblks, 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 + 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,
+			  XLOG_BC_TABLE_SIZE * sizeof(xfs_buf_cancel_t*));
+		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
+	{
+		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,
+		  XLOG_BC_TABLE_SIZE * sizeof(xfs_buf_cancel_t*));
+	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);
+	XFS_BUF_READ(bp);
+	xfsbdstrat(log->l_mp, bp);
+	if ((error = xfs_iowait(bp))) {
+		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_xlatesb(XFS_BUF_TO_SBP(bp), sbp, 1, XFS_SB_ALL_BITS);
+	ASSERT(sbp->sb_magicnum == XFS_SB_MAGIC);
+	ASSERT(XFS_SB_GOOD_VERSION(sbp));
+	xfs_buf_relse(bp);
+
+	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,
+	int		readonly)
+{
+	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, readonly)))
+		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 required"))) {
+			return error;
+		}
+
+		cmn_err(CE_NOTE,
+			"Starting XFS recovery on filesystem: %s (dev: %s)",
+			log->l_mp->m_fsname, XFS_BUFTARG_NAME(log->l_targ));
+
+		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,
+	int		mfsi_flags)
+{
+	/*
+	 * 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) {
+		xlog_recover_process_efis(log);
+		/*
+		 * 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));
+
+		if ( (mfsi_flags & XFS_MFSI_NOUNLINK) == 0 ) {
+			xlog_recover_process_iunlinks(log);
+		}
+
+		xlog_recover_check_summary(log);
+
+		cmn_err(CE_NOTE,
+			"Ending XFS recovery on filesystem: %s (dev: %s)",
+			log->l_mp->m_fsname, XFS_BUFTARG_NAME(log->l_targ));
+		log->l_flags &= ~XLOG_RECOVERY_NEEDED;
+	} else {
+		cmn_err(CE_DEBUG,
+			"!Ending clean XFS mount for filesystem: %s",
+			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_agi_t	*agip;
+	xfs_buf_t	*agfbp;
+	xfs_buf_t	*agibp;
+	xfs_daddr_t	agfdaddr;
+	xfs_daddr_t	agidaddr;
+	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;
+
+	mp = log->l_mp;
+
+	freeblks = 0LL;
+	itotal = 0LL;
+	ifree = 0LL;
+	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
+		agfdaddr = XFS_AG_DADDR(mp, agno, XFS_AGF_DADDR(mp));
+		agfbp = xfs_buf_read(mp->m_ddev_targp, agfdaddr,
+				XFS_FSS_TO_BB(mp, 1), 0);
+		if (XFS_BUF_ISERROR(agfbp)) {
+			xfs_ioerror_alert("xlog_recover_check_summary(agf)",
+						mp, agfbp, agfdaddr);
+		}
+		agfp = XFS_BUF_TO_AGF(agfbp);
+		ASSERT(XFS_AGF_MAGIC ==
+			INT_GET(agfp->agf_magicnum, ARCH_CONVERT));
+		ASSERT(XFS_AGF_GOOD_VERSION(
+			INT_GET(agfp->agf_versionnum, ARCH_CONVERT)));
+		ASSERT(INT_GET(agfp->agf_seqno, ARCH_CONVERT) == agno);
+
+		freeblks += INT_GET(agfp->agf_freeblks, ARCH_CONVERT) +
+			    INT_GET(agfp->agf_flcount, ARCH_CONVERT);
+		xfs_buf_relse(agfbp);
+
+		agidaddr = XFS_AG_DADDR(mp, agno, XFS_AGI_DADDR(mp));
+		agibp = xfs_buf_read(mp->m_ddev_targp, agidaddr,
+				XFS_FSS_TO_BB(mp, 1), 0);
+		if (XFS_BUF_ISERROR(agibp)) {
+			xfs_ioerror_alert("xlog_recover_check_summary(agi)",
+					  mp, agibp, agidaddr);
+		}
+		agip = XFS_BUF_TO_AGI(agibp);
+		ASSERT(XFS_AGI_MAGIC ==
+			INT_GET(agip->agi_magicnum, ARCH_CONVERT));
+		ASSERT(XFS_AGI_GOOD_VERSION(
+			INT_GET(agip->agi_versionnum, ARCH_CONVERT)));
+		ASSERT(INT_GET(agip->agi_seqno, ARCH_CONVERT) == agno);
+
+		itotal += INT_GET(agip->agi_count, ARCH_CONVERT);
+		ifree += INT_GET(agip->agi_freecount, ARCH_CONVERT);
+		xfs_buf_relse(agibp);
+	}
+
+	sbbp = xfs_getsb(mp, 0);
+#ifdef XFS_LOUD_RECOVERY
+	sbp = &mp->m_sb;
+	xfs_xlatesb(XFS_BUF_TO_SBP(sbbp), sbp, 1, XFS_SB_ALL_BITS);
+	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 */