xfs: store xfs_mount in the buftarg instead of in the xfs_buf

Each buffer contains both a buftarg pointer and a mount pointer. If
we add a mount pointer into the buftarg, we can avoid needing the
b_mount field in every buffer and grab it from the buftarg when
needed instead. This shrinks the xfs_buf by 8 bytes.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Alex Elder <aelder@sgi.com>

1 files changed, 1 insertions, 2 deletions

diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
index 1b09d7a280df..ee7557611b6e 100644
--- a/fs/xfs/xfs_buf_item.c
+++ b/fs/xfs/xfs_buf_item.c
@@ -692,8 +692,7 @@ xfs_buf_item_init(
          * the first.  If we do already have one, there is
          * nothing to do here so return.
          */
-        if (bp->b_mount != mp)
-                bp->b_mount = mp;
+        ASSERT(bp->b_target->bt_mount == mp);
         if (XFS_BUF_FSPRIVATE(bp, void *) != NULL) {
                 lip = XFS_BUF_FSPRIVATE(bp, xfs_log_item_t *);
                 if (lip->li_type == XFS_LI_BUF) {