xfs: add xfs_ilock_attr_map_shared

Equivalent to xfs_ilock_data_map_shared, except for the attribute fork.

Make xfs_getbmap use it if called for the attribute fork instead of
xfs_ilock_data_map_shared.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ben Myers <bpm@sgi.com>
Signed-off-by: Ben Myers <bpm@sgi.com>


diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h
index fde3686..65e2350 100644
--- a/fs/xfs/xfs_inode.h
+++ b/fs/xfs/xfs_inode.h
@@ -338,6 +338,7 @@
 void		xfs_ilock_demote(xfs_inode_t *, uint);
 int		xfs_isilocked(xfs_inode_t *, uint);
 uint		xfs_ilock_data_map_shared(struct xfs_inode *);
+uint		xfs_ilock_attr_map_shared(struct xfs_inode *);
 int		xfs_ialloc(struct xfs_trans *, xfs_inode_t *, umode_t,
 			   xfs_nlink_t, xfs_dev_t, prid_t, int,
 			   struct xfs_buf **, xfs_inode_t **);