xfs: refactor log recovery buffer item dispatch for pass2 commit functions

Move the log buffer item pass2 commit code into the per-item source code
files and use the dispatch function to call it.  We do these one at a
time because there's a lot of code to move.  No functional changes.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

1 files changed, 790 insertions, 0 deletions

diff --git a/fs/xfs/xfs_buf_item_recover.c b/fs/xfs/xfs_buf_item_recover.c
index e2d9599f67df..4ba2e27a15ca 100644
--- a/fs/xfs/xfs_buf_item_recover.c
+++ b/fs/xfs/xfs_buf_item_recover.c
@@ -18,6 +18,10 @@
 #include "xfs_log.h"
 #include "xfs_log_priv.h"
 #include "xfs_log_recover.h"
+#include "xfs_error.h"
+#include "xfs_inode.h"
+#include "xfs_dir2.h"
+#include "xfs_quota.h"
 
 /*
  * Sort buffer items for log recovery.  Most buffer items should end up on the
@@ -82,9 +86,795 @@ xlog_recover_buf_commit_pass1(
 	return 0;
 }
 
+/*
+ * Validate the recovered buffer is of the correct type and attach the
+ * appropriate buffer operations to them for writeback. Magic numbers are in a
+ * few places:
+ *	the first 16 bits of the buffer (inode buffer, dquot buffer),
+ *	the first 32 bits of the buffer (most blocks),
+ *	inside a struct xfs_da_blkinfo at the start of the buffer.
+ */
+static void
+xlog_recover_validate_buf_type(
+	struct xfs_mount		*mp,
+	struct xfs_buf			*bp,
+	struct xfs_buf_log_format	*buf_f,
+	xfs_lsn_t			current_lsn)
+{
+	struct xfs_da_blkinfo		*info = bp->b_addr;
+	uint32_t			magic32;
+	uint16_t			magic16;
+	uint16_t			magicda;
+	char				*warnmsg = NULL;
+
+	/*
+	 * We can only do post recovery validation on items on CRC enabled
+	 * fielsystems as we need to know when the buffer was written to be able
+	 * to determine if we should have replayed the item. If we replay old
+	 * metadata over a newer buffer, then it will enter a temporarily
+	 * inconsistent state resulting in verification failures. Hence for now
+	 * just avoid the verification stage for non-crc filesystems
+	 */
+	if (!xfs_sb_version_hascrc(&mp->m_sb))
+		return;
+
+	magic32 = be32_to_cpu(*(__be32 *)bp->b_addr);
+	magic16 = be16_to_cpu(*(__be16*)bp->b_addr);
+	magicda = be16_to_cpu(info->magic);
+	switch (xfs_blft_from_flags(buf_f)) {
+	case XFS_BLFT_BTREE_BUF:
+		switch (magic32) {
+		case XFS_ABTB_CRC_MAGIC:
+		case XFS_ABTB_MAGIC:
+			bp->b_ops = &xfs_bnobt_buf_ops;
+			break;
+		case XFS_ABTC_CRC_MAGIC:
+		case XFS_ABTC_MAGIC:
+			bp->b_ops = &xfs_cntbt_buf_ops;
+			break;
+		case XFS_IBT_CRC_MAGIC:
+		case XFS_IBT_MAGIC:
+			bp->b_ops = &xfs_inobt_buf_ops;
+			break;
+		case XFS_FIBT_CRC_MAGIC:
+		case XFS_FIBT_MAGIC:
+			bp->b_ops = &xfs_finobt_buf_ops;
+			break;
+		case XFS_BMAP_CRC_MAGIC:
+		case XFS_BMAP_MAGIC:
+			bp->b_ops = &xfs_bmbt_buf_ops;
+			break;
+		case XFS_RMAP_CRC_MAGIC:
+			bp->b_ops = &xfs_rmapbt_buf_ops;
+			break;
+		case XFS_REFC_CRC_MAGIC:
+			bp->b_ops = &xfs_refcountbt_buf_ops;
+			break;
+		default:
+			warnmsg = "Bad btree block magic!";
+			break;
+		}
+		break;
+	case XFS_BLFT_AGF_BUF:
+		if (magic32 != XFS_AGF_MAGIC) {
+			warnmsg = "Bad AGF block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_agf_buf_ops;
+		break;
+	case XFS_BLFT_AGFL_BUF:
+		if (magic32 != XFS_AGFL_MAGIC) {
+			warnmsg = "Bad AGFL block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_agfl_buf_ops;
+		break;
+	case XFS_BLFT_AGI_BUF:
+		if (magic32 != XFS_AGI_MAGIC) {
+			warnmsg = "Bad AGI block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_agi_buf_ops;
+		break;
+	case XFS_BLFT_UDQUOT_BUF:
+	case XFS_BLFT_PDQUOT_BUF:
+	case XFS_BLFT_GDQUOT_BUF:
+#ifdef CONFIG_XFS_QUOTA
+		if (magic16 != XFS_DQUOT_MAGIC) {
+			warnmsg = "Bad DQUOT block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_dquot_buf_ops;
+#else
+		xfs_alert(mp,
+	"Trying to recover dquots without QUOTA support built in!");
+		ASSERT(0);
+#endif
+		break;
+	case XFS_BLFT_DINO_BUF:
+		if (magic16 != XFS_DINODE_MAGIC) {
+			warnmsg = "Bad INODE block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_inode_buf_ops;
+		break;
+	case XFS_BLFT_SYMLINK_BUF:
+		if (magic32 != XFS_SYMLINK_MAGIC) {
+			warnmsg = "Bad symlink block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_symlink_buf_ops;
+		break;
+	case XFS_BLFT_DIR_BLOCK_BUF:
+		if (magic32 != XFS_DIR2_BLOCK_MAGIC &&
+		    magic32 != XFS_DIR3_BLOCK_MAGIC) {
+			warnmsg = "Bad dir block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_dir3_block_buf_ops;
+		break;
+	case XFS_BLFT_DIR_DATA_BUF:
+		if (magic32 != XFS_DIR2_DATA_MAGIC &&
+		    magic32 != XFS_DIR3_DATA_MAGIC) {
+			warnmsg = "Bad dir data magic!";
+			break;
+		}
+		bp->b_ops = &xfs_dir3_data_buf_ops;
+		break;
+	case XFS_BLFT_DIR_FREE_BUF:
+		if (magic32 != XFS_DIR2_FREE_MAGIC &&
+		    magic32 != XFS_DIR3_FREE_MAGIC) {
+			warnmsg = "Bad dir3 free magic!";
+			break;
+		}
+		bp->b_ops = &xfs_dir3_free_buf_ops;
+		break;
+	case XFS_BLFT_DIR_LEAF1_BUF:
+		if (magicda != XFS_DIR2_LEAF1_MAGIC &&
+		    magicda != XFS_DIR3_LEAF1_MAGIC) {
+			warnmsg = "Bad dir leaf1 magic!";
+			break;
+		}
+		bp->b_ops = &xfs_dir3_leaf1_buf_ops;
+		break;
+	case XFS_BLFT_DIR_LEAFN_BUF:
+		if (magicda != XFS_DIR2_LEAFN_MAGIC &&
+		    magicda != XFS_DIR3_LEAFN_MAGIC) {
+			warnmsg = "Bad dir leafn magic!";
+			break;
+		}
+		bp->b_ops = &xfs_dir3_leafn_buf_ops;
+		break;
+	case XFS_BLFT_DA_NODE_BUF:
+		if (magicda != XFS_DA_NODE_MAGIC &&
+		    magicda != XFS_DA3_NODE_MAGIC) {
+			warnmsg = "Bad da node magic!";
+			break;
+		}
+		bp->b_ops = &xfs_da3_node_buf_ops;
+		break;
+	case XFS_BLFT_ATTR_LEAF_BUF:
+		if (magicda != XFS_ATTR_LEAF_MAGIC &&
+		    magicda != XFS_ATTR3_LEAF_MAGIC) {
+			warnmsg = "Bad attr leaf magic!";
+			break;
+		}
+		bp->b_ops = &xfs_attr3_leaf_buf_ops;
+		break;
+	case XFS_BLFT_ATTR_RMT_BUF:
+		if (magic32 != XFS_ATTR3_RMT_MAGIC) {
+			warnmsg = "Bad attr remote magic!";
+			break;
+		}
+		bp->b_ops = &xfs_attr3_rmt_buf_ops;
+		break;
+	case XFS_BLFT_SB_BUF:
+		if (magic32 != XFS_SB_MAGIC) {
+			warnmsg = "Bad SB block magic!";
+			break;
+		}
+		bp->b_ops = &xfs_sb_buf_ops;
+		break;
+#ifdef CONFIG_XFS_RT
+	case XFS_BLFT_RTBITMAP_BUF:
+	case XFS_BLFT_RTSUMMARY_BUF:
+		/* no magic numbers for verification of RT buffers */
+		bp->b_ops = &xfs_rtbuf_ops;
+		break;
+#endif /* CONFIG_XFS_RT */
+	default:
+		xfs_warn(mp, "Unknown buffer type %d!",
+			 xfs_blft_from_flags(buf_f));
+		break;
+	}
+
+	/*
+	 * Nothing else to do in the case of a NULL current LSN as this means
+	 * the buffer is more recent than the change in the log and will be
+	 * skipped.
+	 */
+	if (current_lsn == NULLCOMMITLSN)
+		return;
+
+	if (warnmsg) {
+		xfs_warn(mp, warnmsg);
+		ASSERT(0);
+	}
+
+	/*
+	 * We must update the metadata LSN of the buffer as it is written out to
+	 * ensure that older transactions never replay over this one and corrupt
+	 * the buffer. This can occur if log recovery is interrupted at some
+	 * point after the current transaction completes, at which point a
+	 * subsequent mount starts recovery from the beginning.
+	 *
+	 * Write verifiers update the metadata LSN from log items attached to
+	 * the buffer. Therefore, initialize a bli purely to carry the LSN to
+	 * the verifier. We'll clean it up in our ->iodone() callback.
+	 */
+	if (bp->b_ops) {
+		struct xfs_buf_log_item	*bip;
+
+		ASSERT(!bp->b_iodone || bp->b_iodone == xlog_recover_iodone);
+		bp->b_iodone = xlog_recover_iodone;
+		xfs_buf_item_init(bp, mp);
+		bip = bp->b_log_item;
+		bip->bli_item.li_lsn = current_lsn;
+	}
+}
+
+/*
+ * 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.
+ */
+STATIC void
+xlog_recover_do_reg_buffer(
+	struct xfs_mount		*mp,
+	struct xlog_recover_item	*item,
+	struct xfs_buf			*bp,
+	struct xfs_buf_log_format	*buf_f,
+	xfs_lsn_t			current_lsn)
+{
+	int			i;
+	int			bit;
+	int			nbits;
+	xfs_failaddr_t		fa;
+	const size_t		size_disk_dquot = sizeof(struct xfs_disk_dquot);
+
+	trace_xfs_log_recover_buf_reg_buf(mp->m_log, buf_f);
+
+	bit = 0;
+	i = 1;  /* 0 is the buf format structure */
+	while (1) {
+		bit = xfs_next_bit(buf_f->blf_data_map,
+				   buf_f->blf_map_size, bit);
+		if (bit == -1)
+			break;
+		nbits = xfs_contig_bits(buf_f->blf_data_map,
+					buf_f->blf_map_size, bit);
+		ASSERT(nbits > 0);
+		ASSERT(item->ri_buf[i].i_addr != NULL);
+		ASSERT(item->ri_buf[i].i_len % XFS_BLF_CHUNK == 0);
+		ASSERT(BBTOB(bp->b_length) >=
+		       ((uint)bit << XFS_BLF_SHIFT) + (nbits << XFS_BLF_SHIFT));
+
+		/*
+		 * The dirty regions logged in the buffer, even though
+		 * contiguous, may span multiple chunks. This is because the
+		 * dirty region may span a physical page boundary in a buffer
+		 * and hence be split into two separate vectors for writing into
+		 * the log. Hence we need to trim nbits back to the length of
+		 * the current region being copied out of the log.
+		 */
+		if (item->ri_buf[i].i_len < (nbits << XFS_BLF_SHIFT))
+			nbits = item->ri_buf[i].i_len >> XFS_BLF_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.
+		 */
+		fa = NULL;
+		if (buf_f->blf_flags &
+		   (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
+			if (item->ri_buf[i].i_addr == NULL) {
+				xfs_alert(mp,
+					"XFS: NULL dquot in %s.", __func__);
+				goto next;
+			}
+			if (item->ri_buf[i].i_len < size_disk_dquot) {
+				xfs_alert(mp,
+					"XFS: dquot too small (%d) in %s.",
+					item->ri_buf[i].i_len, __func__);
+				goto next;
+			}
+			fa = xfs_dquot_verify(mp, item->ri_buf[i].i_addr,
+					       -1, 0);
+			if (fa) {
+				xfs_alert(mp,
+	"dquot corrupt at %pS trying to replay into block 0x%llx",
+					fa, bp->b_bn);
+				goto next;
+			}
+		}
+
+		memcpy(xfs_buf_offset(bp,
+			(uint)bit << XFS_BLF_SHIFT),	/* dest */
+			item->ri_buf[i].i_addr,		/* source */
+			nbits<<XFS_BLF_SHIFT);		/* length */
+ next:
+		i++;
+		bit += nbits;
+	}
+
+	/* Shouldn't be any more regions */
+	ASSERT(i == item->ri_total);
+
+	xlog_recover_validate_buf_type(mp, bp, buf_f, current_lsn);
+}
+
+/*
+ * Perform a dquot buffer recovery.
+ * Simple algorithm: if we have found a QUOTAOFF log item 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.
+ *
+ * Return false if the buffer was tossed and true if we recovered the buffer to
+ * indicate to the caller if the buffer needs writing.
+ */
+STATIC bool
+xlog_recover_do_dquot_buffer(
+	struct xfs_mount		*mp,
+	struct xlog			*log,
+	struct xlog_recover_item	*item,
+	struct xfs_buf			*bp,
+	struct xfs_buf_log_format	*buf_f)
+{
+	uint			type;
+
+	trace_xfs_log_recover_buf_dquot_buf(log, buf_f);
+
+	/*
+	 * Filesystems are required to send in quota flags at mount time.
+	 */
+	if (!mp->m_qflags)
+		return false;
+
+	type = 0;
+	if (buf_f->blf_flags & XFS_BLF_UDQUOT_BUF)
+		type |= XFS_DQ_USER;
+	if (buf_f->blf_flags & XFS_BLF_PDQUOT_BUF)
+		type |= XFS_DQ_PROJ;
+	if (buf_f->blf_flags & XFS_BLF_GDQUOT_BUF)
+		type |= XFS_DQ_GROUP;
+	/*
+	 * This type of quotas was turned off, so ignore this buffer
+	 */
+	if (log->l_quotaoffs_flag & type)
+		return false;
+
+	xlog_recover_do_reg_buffer(mp, item, bp, buf_f, NULLCOMMITLSN);
+	return true;
+}
+
+/*
+ * 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_inode_pass2().
+ *
+ * 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(
+	struct xfs_mount		*mp,
+	struct xlog_recover_item	*item,
+	struct xfs_buf			*bp,
+	struct xfs_buf_log_format	*buf_f)
+{
+	int				i;
+	int				item_index = 0;
+	int				bit = 0;
+	int				nbits = 0;
+	int				reg_buf_offset = 0;
+	int				reg_buf_bytes = 0;
+	int				next_unlinked_offset;
+	int				inodes_per_buf;
+	xfs_agino_t			*logged_nextp;
+	xfs_agino_t			*buffer_nextp;
+
+	trace_xfs_log_recover_buf_inode_buf(mp->m_log, buf_f);
+
+	/*
+	 * Post recovery validation only works properly on CRC enabled
+	 * filesystems.
+	 */
+	if (xfs_sb_version_hascrc(&mp->m_sb))
+		bp->b_ops = &xfs_inode_buf_ops;
+
+	inodes_per_buf = BBTOB(bp->b_length) >> 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(buf_f->blf_data_map,
+					   buf_f->blf_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(buf_f->blf_data_map,
+						buf_f->blf_map_size, bit);
+			ASSERT(nbits > 0);
+			reg_buf_offset = bit << XFS_BLF_SHIFT;
+			reg_buf_bytes = nbits << XFS_BLF_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_BLF_CHUNK) == 0);
+		ASSERT((reg_buf_offset + reg_buf_bytes) <= BBTOB(bp->b_length));
+
+		/*
+		 * 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 = item->ri_buf[item_index].i_addr +
+				next_unlinked_offset - reg_buf_offset;
+		if (XFS_IS_CORRUPT(mp, *logged_nextp == 0)) {
+			xfs_alert(mp,
+		"Bad inode buffer log record (ptr = "PTR_FMT", bp = "PTR_FMT"). "
+		"Trying to replay bad (0) inode di_next_unlinked field.",
+				item, bp);
+			return -EFSCORRUPTED;
+		}
+
+		buffer_nextp = xfs_buf_offset(bp, next_unlinked_offset);
+		*buffer_nextp = *logged_nextp;
+
+		/*
+		 * If necessary, recalculate the CRC in the on-disk inode. We
+		 * have to leave the inode in a consistent state for whoever
+		 * reads it next....
+		 */
+		xfs_dinode_calc_crc(mp,
+				xfs_buf_offset(bp, i * mp->m_sb.sb_inodesize));
+
+	}
+
+	return 0;
+}
+
+/*
+ * V5 filesystems know the age of the buffer on disk being recovered. We can
+ * have newer objects on disk than we are replaying, and so for these cases we
+ * don't want to replay the current change as that will make the buffer contents
+ * temporarily invalid on disk.
+ *
+ * The magic number might not match the buffer type we are going to recover
+ * (e.g. reallocated blocks), so we ignore the xfs_buf_log_format flags.  Hence
+ * extract the LSN of the existing object in the buffer based on it's current
+ * magic number.  If we don't recognise the magic number in the buffer, then
+ * return a LSN of -1 so that the caller knows it was an unrecognised block and
+ * so can recover the buffer.
+ *
+ * Note: we cannot rely solely on magic number matches to determine that the
+ * buffer has a valid LSN - we also need to verify that it belongs to this
+ * filesystem, so we need to extract the object's LSN and compare it to that
+ * which we read from the superblock. If the UUIDs don't match, then we've got a
+ * stale metadata block from an old filesystem instance that we need to recover
+ * over the top of.
+ */
+static xfs_lsn_t
+xlog_recover_get_buf_lsn(
+	struct xfs_mount	*mp,
+	struct xfs_buf		*bp)
+{
+	uint32_t		magic32;
+	uint16_t		magic16;
+	uint16_t		magicda;
+	void			*blk = bp->b_addr;
+	uuid_t			*uuid;
+	xfs_lsn_t		lsn = -1;
+
+	/* v4 filesystems always recover immediately */
+	if (!xfs_sb_version_hascrc(&mp->m_sb))
+		goto recover_immediately;
+
+	magic32 = be32_to_cpu(*(__be32 *)blk);
+	switch (magic32) {
+	case XFS_ABTB_CRC_MAGIC:
+	case XFS_ABTC_CRC_MAGIC:
+	case XFS_ABTB_MAGIC:
+	case XFS_ABTC_MAGIC:
+	case XFS_RMAP_CRC_MAGIC:
+	case XFS_REFC_CRC_MAGIC:
+	case XFS_IBT_CRC_MAGIC:
+	case XFS_IBT_MAGIC: {
+		struct xfs_btree_block *btb = blk;
+
+		lsn = be64_to_cpu(btb->bb_u.s.bb_lsn);
+		uuid = &btb->bb_u.s.bb_uuid;
+		break;
+	}
+	case XFS_BMAP_CRC_MAGIC:
+	case XFS_BMAP_MAGIC: {
+		struct xfs_btree_block *btb = blk;
+
+		lsn = be64_to_cpu(btb->bb_u.l.bb_lsn);
+		uuid = &btb->bb_u.l.bb_uuid;
+		break;
+	}
+	case XFS_AGF_MAGIC:
+		lsn = be64_to_cpu(((struct xfs_agf *)blk)->agf_lsn);
+		uuid = &((struct xfs_agf *)blk)->agf_uuid;
+		break;
+	case XFS_AGFL_MAGIC:
+		lsn = be64_to_cpu(((struct xfs_agfl *)blk)->agfl_lsn);
+		uuid = &((struct xfs_agfl *)blk)->agfl_uuid;
+		break;
+	case XFS_AGI_MAGIC:
+		lsn = be64_to_cpu(((struct xfs_agi *)blk)->agi_lsn);
+		uuid = &((struct xfs_agi *)blk)->agi_uuid;
+		break;
+	case XFS_SYMLINK_MAGIC:
+		lsn = be64_to_cpu(((struct xfs_dsymlink_hdr *)blk)->sl_lsn);
+		uuid = &((struct xfs_dsymlink_hdr *)blk)->sl_uuid;
+		break;
+	case XFS_DIR3_BLOCK_MAGIC:
+	case XFS_DIR3_DATA_MAGIC:
+	case XFS_DIR3_FREE_MAGIC:
+		lsn = be64_to_cpu(((struct xfs_dir3_blk_hdr *)blk)->lsn);
+		uuid = &((struct xfs_dir3_blk_hdr *)blk)->uuid;
+		break;
+	case XFS_ATTR3_RMT_MAGIC:
+		/*
+		 * Remote attr blocks are written synchronously, rather than
+		 * being logged. That means they do not contain a valid LSN
+		 * (i.e. transactionally ordered) in them, and hence any time we
+		 * see a buffer to replay over the top of a remote attribute
+		 * block we should simply do so.
+		 */
+		goto recover_immediately;
+	case XFS_SB_MAGIC:
+		/*
+		 * superblock uuids are magic. We may or may not have a
+		 * sb_meta_uuid on disk, but it will be set in the in-core
+		 * superblock. We set the uuid pointer for verification
+		 * according to the superblock feature mask to ensure we check
+		 * the relevant UUID in the superblock.
+		 */
+		lsn = be64_to_cpu(((struct xfs_dsb *)blk)->sb_lsn);
+		if (xfs_sb_version_hasmetauuid(&mp->m_sb))
+			uuid = &((struct xfs_dsb *)blk)->sb_meta_uuid;
+		else
+			uuid = &((struct xfs_dsb *)blk)->sb_uuid;
+		break;
+	default:
+		break;
+	}
+
+	if (lsn != (xfs_lsn_t)-1) {
+		if (!uuid_equal(&mp->m_sb.sb_meta_uuid, uuid))
+			goto recover_immediately;
+		return lsn;
+	}
+
+	magicda = be16_to_cpu(((struct xfs_da_blkinfo *)blk)->magic);
+	switch (magicda) {
+	case XFS_DIR3_LEAF1_MAGIC:
+	case XFS_DIR3_LEAFN_MAGIC:
+	case XFS_DA3_NODE_MAGIC:
+		lsn = be64_to_cpu(((struct xfs_da3_blkinfo *)blk)->lsn);
+		uuid = &((struct xfs_da3_blkinfo *)blk)->uuid;
+		break;
+	default:
+		break;
+	}
+
+	if (lsn != (xfs_lsn_t)-1) {
+		if (!uuid_equal(&mp->m_sb.sb_uuid, uuid))
+			goto recover_immediately;
+		return lsn;
+	}
+
+	/*
+	 * We do individual object checks on dquot and inode buffers as they
+	 * have their own individual LSN records. Also, we could have a stale
+	 * buffer here, so we have to at least recognise these buffer types.
+	 *
+	 * A notd complexity here is inode unlinked list processing - it logs
+	 * the inode directly in the buffer, but we don't know which inodes have
+	 * been modified, and there is no global buffer LSN. Hence we need to
+	 * recover all inode buffer types immediately. This problem will be
+	 * fixed by logical logging of the unlinked list modifications.
+	 */
+	magic16 = be16_to_cpu(*(__be16 *)blk);
+	switch (magic16) {
+	case XFS_DQUOT_MAGIC:
+	case XFS_DINODE_MAGIC:
+		goto recover_immediately;
+	default:
+		break;
+	}
+
+	/* unknown buffer contents, recover immediately */
+
+recover_immediately:
+	return (xfs_lsn_t)-1;
+
+}
+
+/*
+ * 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_BLF_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_buf_pass[1,2] above
+ * for more details on the implementation of the table of cancel records.
+ */
+STATIC int
+xlog_recover_buf_commit_pass2(
+	struct xlog			*log,
+	struct list_head		*buffer_list,
+	struct xlog_recover_item	*item,
+	xfs_lsn_t			current_lsn)
+{
+	struct xfs_buf_log_format	*buf_f = item->ri_buf[0].i_addr;
+	struct xfs_mount		*mp = log->l_mp;
+	struct xfs_buf			*bp;
+	int				error;
+	uint				buf_flags;
+	xfs_lsn_t			lsn;
+
+	/*
+	 * In this pass we only want to recover all the buffers which have
+	 * not been cancelled and are not cancellation buffers themselves.
+	 */
+	if (buf_f->blf_flags & XFS_BLF_CANCEL) {
+		if (xlog_put_buffer_cancelled(log, buf_f->blf_blkno,
+				buf_f->blf_len))
+			goto cancelled;
+	} else {
+
+		if (xlog_is_buffer_cancelled(log, buf_f->blf_blkno,
+				buf_f->blf_len))
+			goto cancelled;
+	}
+
+	trace_xfs_log_recover_buf_recover(log, buf_f);
+
+	buf_flags = 0;
+	if (buf_f->blf_flags & XFS_BLF_INODE_BUF)
+		buf_flags |= XBF_UNMAPPED;
+
+	error = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, buf_f->blf_len,
+			  buf_flags, &bp, NULL);
+	if (error)
+		return error;
+
+	/*
+	 * Recover the buffer only if we get an LSN from it and it's less than
+	 * the lsn of the transaction we are replaying.
+	 *
+	 * Note that we have to be extremely careful of readahead here.
+	 * Readahead does not attach verfiers to the buffers so if we don't
+	 * actually do any replay after readahead because of the LSN we found
+	 * in the buffer if more recent than that current transaction then we
+	 * need to attach the verifier directly. Failure to do so can lead to
+	 * future recovery actions (e.g. EFI and unlinked list recovery) can
+	 * operate on the buffers and they won't get the verifier attached. This
+	 * can lead to blocks on disk having the correct content but a stale
+	 * CRC.
+	 *
+	 * It is safe to assume these clean buffers are currently up to date.
+	 * If the buffer is dirtied by a later transaction being replayed, then
+	 * the verifier will be reset to match whatever recover turns that
+	 * buffer into.
+	 */
+	lsn = xlog_recover_get_buf_lsn(mp, bp);
+	if (lsn && lsn != -1 && XFS_LSN_CMP(lsn, current_lsn) >= 0) {
+		trace_xfs_log_recover_buf_skip(log, buf_f);
+		xlog_recover_validate_buf_type(mp, bp, buf_f, NULLCOMMITLSN);
+		goto out_release;
+	}
+
+	if (buf_f->blf_flags & XFS_BLF_INODE_BUF) {
+		error = xlog_recover_do_inode_buffer(mp, item, bp, buf_f);
+		if (error)
+			goto out_release;
+	} else if (buf_f->blf_flags &
+		  (XFS_BLF_UDQUOT_BUF|XFS_BLF_PDQUOT_BUF|XFS_BLF_GDQUOT_BUF)) {
+		bool	dirty;
+
+		dirty = xlog_recover_do_dquot_buffer(mp, log, item, bp, buf_f);
+		if (!dirty)
+			goto out_release;
+	} else {
+		xlog_recover_do_reg_buffer(mp, item, bp, buf_f, current_lsn);
+	}
+
+	/*
+	 * 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 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, inode_cluster_size)
+	 * for *our* value of inode_cluster_size, then we need to keep
+	 * the buffer out of the buffer cache so that the buffer won't
+	 * overlap with future reads of those inodes.
+	 */
+	if (XFS_DINODE_MAGIC ==
+	    be16_to_cpu(*((__be16 *)xfs_buf_offset(bp, 0))) &&
+	    (BBTOB(bp->b_length) != M_IGEO(log->l_mp)->inode_cluster_size)) {
+		xfs_buf_stale(bp);
+		error = xfs_bwrite(bp);
+	} else {
+		ASSERT(bp->b_mount == mp);
+		bp->b_iodone = xlog_recover_iodone;
+		xfs_buf_delwri_queue(bp, buffer_list);
+	}
+
+out_release:
+	xfs_buf_relse(bp);
+	return error;
+cancelled:
+	trace_xfs_log_recover_buf_cancel(log, buf_f);
+	return 0;
+}
+
 const struct xlog_recover_item_ops xlog_buf_item_ops = {
 	.item_type		= XFS_LI_BUF,
 	.reorder		= xlog_recover_buf_reorder,
 	.ra_pass2		= xlog_recover_buf_ra_pass2,
 	.commit_pass1		= xlog_recover_buf_commit_pass1,
+	.commit_pass2		= xlog_recover_buf_commit_pass2,
 };