[PATCH 42/44] xfs: check for shared rt extents when rebuilding rt file's data fork

["Darrick J. Wong" <djwong@xxxxxxxxxx>]

From: Darrick J. Wong <djwong@xxxxxxxxxx>

When we're rebuilding the data fork of a realtime file, we need to
cross-reference each mapping with the rt refcount btree to ensure that
the reflink flag is set if there are any shared extents found.

Signed-off-by: Darrick J. Wong <djwong@xxxxxxxxxx>
---
 fs/xfs/scrub/bmap_repair.c |   23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)


diff --git a/fs/xfs/scrub/bmap_repair.c b/fs/xfs/scrub/bmap_repair.c
index 98618821ad975..c4f9a8ba8cf73 100644
--- a/fs/xfs/scrub/bmap_repair.c
+++ b/fs/xfs/scrub/bmap_repair.c
@@ -101,14 +101,23 @@ xrep_bmap_discover_shared(
 	xfs_filblks_t		blockcount)
 {
 	struct xfs_scrub	*sc = rb->sc;
+	struct xfs_btree_cur	*cur;
 	xfs_agblock_t		agbno;
 	xfs_agblock_t		fbno;
 	xfs_extlen_t		flen;
 	int			error;
 
-	agbno = XFS_FSB_TO_AGBNO(sc->mp, startblock);
-	error = xfs_refcount_find_shared(sc->sa.refc_cur, agbno, blockcount,
-			&fbno, &flen, false);
+	if (XFS_IS_REALTIME_INODE(sc->ip)) {
+		xfs_rgnumber_t		rgno;
+
+		agbno = xfs_rtb_to_rgbno(sc->mp, startblock, &rgno);
+		cur = sc->sr.refc_cur;
+	} else {
+		agbno = XFS_FSB_TO_AGBNO(sc->mp, startblock);
+		cur = sc->sa.refc_cur;
+	}
+	error = xfs_refcount_find_shared(cur, agbno, blockcount, &fbno, &flen,
+			false);
 	if (error)
 		return error;
 
@@ -456,7 +465,9 @@ xrep_bmap_scan_rtgroup(
 		return 0;
 
 	error = xrep_rtgroup_init(sc, rtg, &sc->sr,
-			XFS_RTGLOCK_RMAP | XFS_RTGLOCK_BITMAP_SHARED);
+			XFS_RTGLOCK_RMAP |
+			XFS_RTGLOCK_REFCOUNT |
+			XFS_RTGLOCK_BITMAP_SHARED);
 	if (error)
 		return error;
 
@@ -900,10 +911,6 @@ xrep_bmap_init_reflink_scan(
 	if (whichfork != XFS_DATA_FORK)
 		return RLS_IRRELEVANT;
 
-	/* cannot share realtime extents */
-	if (XFS_IS_REALTIME_INODE(sc->ip))
-		return RLS_IRRELEVANT;
-
 	return RLS_UNKNOWN;
 }