xfs: rename xfs_buftarg structure members

In preparation for adding new members to the structure,
give these old ones more descriptive names:

	bt_ssize -> bt_meta_sectorsize
	bt_smask -> bt_meta_sectormask

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Ben Myers <bpm@sgi.com>

diff --git a/fs/xfs/xfs_buf.h b/fs/xfs/xfs_buf.h
index 4ef949a..d5d88dd 100644
--- a/fs/xfs/xfs_buf.h
+++ b/fs/xfs/xfs_buf.h
@@ -93,8 +93,8 @@
 	struct block_device	*bt_bdev;
 	struct backing_dev_info	*bt_bdi;
 	struct xfs_mount	*bt_mount;
-	unsigned int		bt_ssize;
-	size_t			bt_smask;
+	unsigned int		bt_meta_sectorsize;
+	size_t			bt_meta_sectormask;
 
 	/* LRU control structures */
 	struct shrinker		bt_shrinker;