xfs: avoid shared rmap operations for attr fork extents

During code review, I noticed that the rmap code uses the (slower)
shared mappings rmap functions for any extent of a reflinked file, even
if those extents are for the attr fork, which doesn't support sharing.
We can speed up rmap a tiny bit by optimizing out this case.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Chandan Babu R <chandanrlinux@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_rmap.c

@@ -2505,12 +2505,15 @@ xfs_rmap_map_extent(
 	int			whichfork,
 	struct xfs_bmbt_irec	*PREV)
 {
+	enum xfs_rmap_intent_type type = XFS_RMAP_MAP;
+
 	if (!xfs_rmap_update_is_needed(tp->t_mountp, whichfork))
 		return;
 
-	__xfs_rmap_add(tp, xfs_is_reflink_inode(ip) ?
-			XFS_RMAP_MAP_SHARED : XFS_RMAP_MAP, ip->i_ino,
-			whichfork, PREV);
+	if (whichfork != XFS_ATTR_FORK && xfs_is_reflink_inode(ip))
+		type = XFS_RMAP_MAP_SHARED;
+
+	__xfs_rmap_add(tp, type, ip->i_ino, whichfork, PREV);
 }
 
 /* Unmap an extent out of a file. */
@@ -2521,12 +2524,15 @@ xfs_rmap_unmap_extent(
 	int			whichfork,
 	struct xfs_bmbt_irec	*PREV)
 {
+	enum xfs_rmap_intent_type type = XFS_RMAP_UNMAP;
+
 	if (!xfs_rmap_update_is_needed(tp->t_mountp, whichfork))
 		return;
 
-	__xfs_rmap_add(tp, xfs_is_reflink_inode(ip) ?
-			XFS_RMAP_UNMAP_SHARED : XFS_RMAP_UNMAP, ip->i_ino,
-			whichfork, PREV);
+	if (whichfork != XFS_ATTR_FORK && xfs_is_reflink_inode(ip))
+		type = XFS_RMAP_UNMAP_SHARED;
+
+	__xfs_rmap_add(tp, type, ip->i_ino, whichfork, PREV);
 }
 
 /*
@@ -2543,12 +2549,15 @@ xfs_rmap_convert_extent(
 	int			whichfork,
 	struct xfs_bmbt_irec	*PREV)
 {
+	enum xfs_rmap_intent_type type = XFS_RMAP_CONVERT;
+
 	if (!xfs_rmap_update_is_needed(mp, whichfork))
 		return;
 
-	__xfs_rmap_add(tp, xfs_is_reflink_inode(ip) ?
-			XFS_RMAP_CONVERT_SHARED : XFS_RMAP_CONVERT, ip->i_ino,
-			whichfork, PREV);
+	if (whichfork != XFS_ATTR_FORK && xfs_is_reflink_inode(ip))
+		type = XFS_RMAP_CONVERT_SHARED;
+
+	__xfs_rmap_add(tp, type, ip->i_ino, whichfork, PREV);
 }
 
 /* Schedule the creation of an rmap for non-file data. */