Re: [PATCH 05/28] xfs: refactor log recovery buffer item dispatch for pass2 commit functions

[Chandan Babu R <chandanrlinux@gmail.com>]

On Tuesday 5 May 2020 6:41:03 AM IST Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@oracle.com>
> 
> 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.
>

Buffer item pass2 processing is functionally consistent with what was done
before this patch is applied.

Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>

> Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> ---
>  fs/xfs/libxfs/xfs_log_recover.h |   23 +
>  fs/xfs/xfs_buf_item_recover.c   |  790 +++++++++++++++++++++++++++++++++++++++
>  fs/xfs/xfs_log_recover.c        |  798 ---------------------------------------
>  3 files changed, 820 insertions(+), 791 deletions(-)
> 
> 
> diff --git a/fs/xfs/libxfs/xfs_log_recover.h b/fs/xfs/libxfs/xfs_log_recover.h
> index 384b70d58993..a45f6e9fa47b 100644
> --- a/fs/xfs/libxfs/xfs_log_recover.h
> +++ b/fs/xfs/libxfs/xfs_log_recover.h
> @@ -37,6 +37,26 @@ struct xlog_recover_item_ops {
>  
>  	/* Do whatever work we need to do for pass1, if provided. */
>  	int (*commit_pass1)(struct xlog *log, struct xlog_recover_item *item);
> +
> +	/*
> +	 * This function should do whatever work is needed for pass2 of log
> +	 * recovery, if provided.
> +	 *
> +	 * If the recovered item is an intent item, this function should parse
> +	 * the recovered item to construct an in-core log intent item and
> +	 * insert it into the AIL.  The in-core log intent item should have 1
> +	 * refcount so that the item is freed either (a) when we commit the
> +	 * recovered log item for the intent-done item; (b) replay the work and
> +	 * log a new intent-done item; or (c) recovery fails and we have to
> +	 * abort.
> +	 *
> +	 * If the recovered item is an intent-done item, this function should
> +	 * parse the recovered item to find the id of the corresponding intent
> +	 * log item.  Next, it should find the in-core log intent item in the
> +	 * AIL and release it.
> +	 */
> +	int (*commit_pass2)(struct xlog *log, struct list_head *buffer_list,
> +			    struct xlog_recover_item *item, xfs_lsn_t lsn);
>  };
>  
>  extern const struct xlog_recover_item_ops xlog_icreate_item_ops;
> @@ -101,5 +121,8 @@ struct xlog_recover {
>  void xlog_buf_readahead(struct xlog *log, xfs_daddr_t blkno, uint len,
>  		const struct xfs_buf_ops *ops);
>  bool xlog_add_buffer_cancelled(struct xlog *log, xfs_daddr_t blkno, uint len);
> +bool xlog_is_buffer_cancelled(struct xlog *log, xfs_daddr_t blkno, uint len);
> +bool xlog_put_buffer_cancelled(struct xlog *log, xfs_daddr_t blkno, uint len);
> +void xlog_recover_iodone(struct xfs_buf *bp);
>  
>  #endif	/* __XFS_LOG_RECOVER_H__ */
> diff --git a/fs/xfs/xfs_buf_item_recover.c b/fs/xfs/xfs_buf_item_recover.c
> index 802f2206516d..4ca6d47d6c95 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"
>  
>  STATIC enum xlog_recover_reorder
>  xlog_recover_buf_reorder(
> @@ -68,9 +72,795 @@ 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,
>  };
> diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
> index b3627ebf870e..d65dc3895a62 100644
> --- a/fs/xfs/xfs_log_recover.c
> +++ b/fs/xfs/xfs_log_recover.c
> @@ -284,7 +284,7 @@ xlog_header_check_mount(
>  	return 0;
>  }
>  
> -STATIC void
> +void
>  xlog_recover_iodone(
>  	struct xfs_buf	*bp)
>  {
> @@ -1985,7 +1985,7 @@ xlog_add_buffer_cancelled(
>  /*
>   * Check if there is and entry for blkno, len in the buffer cancel record table.
>   */
> -static bool
> +bool
>  xlog_is_buffer_cancelled(
>  	struct xlog		*log,
>  	xfs_daddr_t		blkno,
> @@ -2002,7 +2002,7 @@ xlog_is_buffer_cancelled(
>   * buffer is re-used again after its last cancellation we actually replay the
>   * changes made at that point.
>   */
> -static bool
> +bool
>  xlog_put_buffer_cancelled(
>  	struct xlog		*log,
>  	xfs_daddr_t		blkno,
> @@ -2034,791 +2034,6 @@ xlog_buf_readahead(
>  		xfs_buf_readahead(log->l_mp->m_ddev_targp, blkno, len, ops);
>  }
>  
> -/*
> - * 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,
> -	xfs_buf_log_format_t	*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;
> -
> -}
> -
> -/*
> - * 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,
> -	xfs_buf_log_format_t	*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,
> -	xfs_buf_log_format_t	*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;
> -}
> -
> -/*
> - * 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_buffer_pass[1,2] above
> - * for more details on the implementation of the table of cancel records.
> - */
> -STATIC int
> -xlog_recover_buffer_pass2(
> -	struct xlog			*log,
> -	struct list_head		*buffer_list,
> -	struct xlog_recover_item	*item,
> -	xfs_lsn_t			current_lsn)
> -{
> -	xfs_buf_log_format_t	*buf_f = item->ri_buf[0].i_addr;
> -	xfs_mount_t		*mp = log->l_mp;
> -	xfs_buf_t		*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;
> -}
> -
>  /*
>   * Inode fork owner changes
>   *
> @@ -3846,10 +3061,11 @@ xlog_recover_commit_pass2(
>  {
>  	trace_xfs_log_recover_item_recover(log, trans, item, XLOG_RECOVER_PASS2);
>  
> +	if (item->ri_ops && item->ri_ops->commit_pass2)
> +		return item->ri_ops->commit_pass2(log, buffer_list, item,
> +				trans->r_lsn);
> +
>  	switch (ITEM_TYPE(item)) {
> -	case XFS_LI_BUF:
> -		return xlog_recover_buffer_pass2(log, buffer_list, item,
> -						 trans->r_lsn);
>  	case XFS_LI_INODE:
>  		return xlog_recover_inode_pass2(log, buffer_list, item,
>  						 trans->r_lsn);
> 
> 


-- 
chandan