[PATCH 065/119] xfs: adjust refcount when unmapping file blocks

[Darrick J. Wong]

When we're unmapping blocks from a reflinked file, decrease the
refcount of the affected blocks and free the extents that are no
longer in use.

v2: Use deferred ops system to avoid deadlocks and running out of
transaction reservation.

Signed-off-by: Darrick J. Wong <darrick.wong at oracle.com>
---
 fs/xfs/libxfs/xfs_bmap.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)


diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
index 972dfc2..9044e39 100644
--- a/fs/xfs/libxfs/xfs_bmap.c
+++ b/fs/xfs/libxfs/xfs_bmap.c
@@ -48,6 +48,7 @@
 #include "xfs_filestream.h"
 #include "xfs_rmap_btree.h"
 #include "xfs_ag_resv.h"
+#include "xfs_refcount.h"
 
 
 kmem_zone_t		*xfs_bmap_free_item_zone;
@@ -5061,9 +5062,16 @@ xfs_bmap_del_extent(
 	/*
 	 * If we need to, add to list of extents to delete.
 	 */
-	if (do_fx)
-		xfs_bmap_add_free(mp, dfops, del->br_startblock,
-				  del->br_blockcount, NULL);
+	if (do_fx) {
+		if (xfs_is_reflink_inode(ip) && whichfork == XFS_DATA_FORK) {
+			error = xfs_refcount_decrease_extent(mp, dfops, del);
+			if (error)
+				goto done;
+		} else
+			xfs_bmap_add_free(mp, dfops, del->br_startblock,
+					  del->br_blockcount, NULL);
+	}
+
 	/*
 	 * Adjust inode # blocks in the file.
 	 */