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, 3 insertions, 2 deletions

diff --git a/fs/xfs/linux-2.6/xfs_buf.h b/fs/xfs/linux-2.6/xfs_buf.h
index 57eedc750ee6..def2cea2b4d6 100644
--- a/fs/xfs/linux-2.6/xfs_buf.h
+++ b/fs/xfs/linux-2.6/xfs_buf.h
@@ -132,6 +132,7 @@ typedef struct xfs_buftarg {
         dev_t                   bt_dev;
         struct block_device     *bt_bdev;
         struct address_space    *bt_mapping;
+        struct xfs_mount        *bt_mount;
         unsigned int            bt_bsize;
         unsigned int            bt_sshift;
         size_t                  bt_smask;
@@ -189,7 +190,6 @@ typedef struct xfs_buf {
         struct completion       b_iowait;       /* queue for I/O waiters */
         void                    *b_fspriv;
         void                    *b_fspriv2;
-        struct xfs_mount        *b_mount;
         unsigned short          b_error;        /* error code on I/O */
         unsigned int            b_page_count;   /* size of page array */
         unsigned int            b_offset;       /* page offset in first page */
@@ -377,7 +377,8 @@ static inline void xfs_buf_relse(xfs_buf_t *bp)
 /*
  *      Handling of buftargs.
  */
-extern xfs_buftarg_t *xfs_alloc_buftarg(struct block_device *, int, const char *);
+extern xfs_buftarg_t *xfs_alloc_buftarg(struct xfs_mount *,
+                        struct block_device *, int, const char *);
 extern void xfs_free_buftarg(struct xfs_mount *, struct xfs_buftarg *);
 extern void xfs_wait_buftarg(xfs_buftarg_t *);
 extern int xfs_setsize_buftarg(xfs_buftarg_t *, unsigned int, unsigned int);