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, 4 insertions, 5 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.c b/fs/xfs/linux-2.6/xfs_buf.c
index 22c7bff77ad2..d6928970097f 100644
--- a/fs/xfs/linux-2.6/xfs_buf.c
+++ b/fs/xfs/linux-2.6/xfs_buf.c
@@ -894,7 +894,7 @@ xfs_buf_lock(
         trace_xfs_buf_lock(bp, _RET_IP_);
 
         if (atomic_read(&bp->b_pin_count) && (bp->b_flags & XBF_STALE))
-                xfs_log_force(bp->b_mount, 0);
+                xfs_log_force(bp->b_target->bt_mount, 0);
         if (atomic_read(&bp->b_io_remaining))
                 blk_run_address_space(bp->b_target->bt_mapping);
         down(&bp->b_sema);
@@ -1017,7 +1017,6 @@ xfs_bwrite(
 {
         int                     error;
 
-        bp->b_mount = mp;
         bp->b_flags |= XBF_WRITE;
         bp->b_flags &= ~(XBF_ASYNC | XBF_READ);
 
@@ -1038,8 +1037,6 @@ xfs_bdwrite(
 {
         trace_xfs_buf_bdwrite(bp, _RET_IP_);
 
-        bp->b_mount = mp;
-
         bp->b_flags &= ~XBF_READ;
         bp->b_flags |= (XBF_DELWRI | XBF_ASYNC);
 
@@ -1128,7 +1125,7 @@ int
 xfs_bdstrat_cb(
         struct xfs_buf  *bp)
 {
-        if (XFS_FORCED_SHUTDOWN(bp->b_mount)) {
+        if (XFS_FORCED_SHUTDOWN(bp->b_target->bt_mount)) {
                 trace_xfs_bdstrat_shut(bp, _RET_IP_);
                 /*
                  * Metadata write that didn't get logged but
@@ -1644,6 +1641,7 @@ out_error:
 
 xfs_buftarg_t *
 xfs_alloc_buftarg(
+        struct xfs_mount        *mp,
         struct block_device     *bdev,
         int                     external,
         const char              *fsname)
@@ -1652,6 +1650,7 @@ xfs_alloc_buftarg(
 
         btp = kmem_zalloc(sizeof(*btp), KM_SLEEP);
 
+        btp->bt_mount = mp;
         btp->bt_dev =  bdev->bd_dev;
         btp->bt_bdev = bdev;
         if (xfs_setsize_buftarg_early(btp, bdev))