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[PATCH 2/2] xfs: fix the buffer log format for contiguous buffers

To: xfs@xxxxxxxxxxx
Subject: [PATCH 2/2] xfs: fix the buffer log format for contiguous buffers
From: Mark Tinguely <tinguely@xxxxxxx>
Date: Tue, 20 Nov 2012 16:41:22 -0600
References: <20121120224120.224166649@xxxxxxx>
User-agent: quilt/0.51-1
A few buffer log format clean-ups for contiguous buffers.

In xfs_buf_item_format_segment(), when a segment is not dirty in
the transaction, do not increment format vector pointer.

In xfs_buf_item_unlock(), every segment must be empty before
considering the buf item empty.

In xfs_trans_binval(), clear the correct buffer log format structure.

Signed-off-by: Mark Tinguely <tinguely@xxxxxxx>

---
 fs/xfs/xfs_buf_item.c  |   32 +++++++++++++++++++++++---------
 fs/xfs/xfs_trans_buf.c |    4 ++--
 2 files changed, 25 insertions(+), 11 deletions(-)

Index: b/fs/xfs/xfs_buf_item.c
===================================================================
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -71,7 +71,7 @@ xfs_buf_item_log_debug(
                chunk_num = byte >> XFS_BLF_SHIFT;
                word_num = chunk_num >> BIT_TO_WORD_SHIFT;
                bit_num = chunk_num & (NBWORD - 1);
-               wordp = &(bip->bli_format.blf_data_map[word_num]);
+               wordp = &(bip->bli_formats[0].blf_data_map[word_num]);
                bit_set = *wordp & (1 << bit_num);
                ASSERT(bit_set);
                byte++;
@@ -290,8 +290,6 @@ xfs_buf_item_format_segment(
        vecp->i_addr = blfp;
        vecp->i_len = base_size;
        vecp->i_type = XLOG_REG_TYPE_BFORMAT;
-       vecp++;
-       nvecs = 1;
 
        if (bip->bli_flags & XFS_BLI_STALE) {
                /*
@@ -301,7 +299,8 @@ xfs_buf_item_format_segment(
                 */
                trace_xfs_buf_item_format_stale(bip);
                ASSERT(blfp->blf_flags & XFS_BLF_CANCEL);
-               blfp->blf_size = nvecs;
+               vecp++;
+               blfp->blf_size = 1;
                return vecp;
        }
 
@@ -309,7 +308,16 @@ xfs_buf_item_format_segment(
         * Fill in an iovec for each set of contiguous chunks.
         */
        first_bit = xfs_next_bit(blfp->blf_data_map, blfp->blf_map_size, 0);
-       ASSERT(first_bit != -1);
+       if (first_bit == -1) {
+               /* If the map is not be dirty in the transaction, mark
+                * the size as zero and do not advance the vector pointer.
+                */
+               blfp->blf_size = 0;
+               return(vecp);
+       }
+
+       nvecs = 1;
+       vecp++;
        last_bit = first_bit;
        nbits = 1;
        for (;;) {
@@ -371,7 +379,7 @@ xfs_buf_item_format_segment(
                        nbits++;
                }
        }
-       bip->bli_format.blf_size = nvecs;
+       blfp->blf_size = nvecs;
        return vecp;
 }
 
@@ -601,7 +609,7 @@ xfs_buf_item_unlock(
 {
        struct xfs_buf_log_item *bip = BUF_ITEM(lip);
        struct xfs_buf          *bp = bip->bli_buf;
-       int                     aborted;
+       int                     aborted, empty, i;
        uint                    hold;
 
        /* Clear the buffer's association with this transaction. */
@@ -644,8 +652,14 @@ xfs_buf_item_unlock(
         * If the buf item isn't tracking any data, free it, otherwise drop the
         * reference we hold to it.
         */
-       if (xfs_bitmap_empty(bip->bli_format.blf_data_map,
-                            bip->bli_format.blf_map_size))
+       empty = 1;
+       for (i = 0; i < bip->bli_format_count; i++)
+               if (!xfs_bitmap_empty(bip->bli_formats[i].blf_data_map,
+                            bip->bli_formats[i].blf_map_size)) {
+                       empty = 0;
+                       break;
+               }
+       if (empty)
                xfs_buf_item_relse(bp);
        else
                atomic_dec(&bip->bli_refcount);
Index: b/fs/xfs/xfs_trans_buf.c
===================================================================
--- a/fs/xfs/xfs_trans_buf.c
+++ b/fs/xfs/xfs_trans_buf.c
@@ -670,8 +670,8 @@ xfs_trans_binval(
        bip->bli_flags &= ~(XFS_BLI_INODE_BUF | XFS_BLI_LOGGED | XFS_BLI_DIRTY);
        bip->bli_format.blf_flags &= ~XFS_BLF_INODE_BUF;
        bip->bli_format.blf_flags |= XFS_BLF_CANCEL;
-       memset((char *)(bip->bli_format.blf_data_map), 0,
-             (bip->bli_format.blf_map_size * sizeof(uint)));
+       memset((char *)(bip->bli_formats[0].blf_data_map), 0,
+             (bip->bli_formats[0].blf_map_size * sizeof(uint)));
        bip->bli_item.li_desc->lid_flags |= XFS_LID_DIRTY;
        tp->t_flags |= XFS_TRANS_DIRTY;
 }


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