[XFS] replace b_fspriv with b_mount

Replace the b_fspriv pointer and it's ugly accessors with a properly types
xfs_mount pointer.  Also switch log reocvery over to it instead of using
b_fspriv for the mount pointer.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
diff --git a/fs/xfs/xfs_rw.c b/fs/xfs/xfs_rw.c
index 3a82576..36f3a21 100644
--- a/fs/xfs/xfs_rw.c
+++ b/fs/xfs/xfs_rw.c
@@ -406,7 +406,7 @@
 	 * XXXsup how does this work for quotas.
 	 */
 	XFS_BUF_SET_BDSTRAT_FUNC(bp, xfs_bdstrat_cb);
-	XFS_BUF_SET_FSPRIVATE3(bp, mp);
+	bp->b_mount = mp;
 	XFS_BUF_WRITE(bp);
 
 	if ((error = XFS_bwrite(bp))) {