[PATCH 2/6] xfs: fix short ifork reaping computation in xreap_bmapi_binval

From: Darrick J. Wong <[email protected]>

LOLLM got really confused about the update to imap->br_blockcount in
xreap_bmapi_binval if xreap_inc_binval returns false.  The intent of
this code is that we shorten the imap to whatever length of space we
invalidated so that the next iteration through the loop will start
wherever we left off.  Unfortunately, the calculation sets br_blockcount
to the amount of *unfinished* work, which means that we pointlessly
re-scan blocks that we already reaped.  This is benign, but we should
fix the computation anyway.

Cc: <[email protected]> # v6.10
Fixes: 5befb047b9f4de ("xfs: add the ability to reap entire inode forks")
Signed-off-by: "Darrick J. Wong" <[email protected]>
Assisted-by: LOLLM # finding obvious bugs
---
 fs/xfs/scrub/reap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)


diff --git a/fs/xfs/scrub/reap.c b/fs/xfs/scrub/reap.c
index 496c6eab555e91..f698b9be3dd1df 100644
--- a/fs/xfs/scrub/reap.c
+++ b/fs/xfs/scrub/reap.c
@@ -1399,7 +1399,7 @@ xreap_bmapi_binval(
 			 * far we've gotten.
 			 */
 			if (!xreap_inc_binval(rs)) {
-				imap->br_blockcount = agbno_next - bno;
+				imap->br_blockcount = bno - agbno;
 				goto out;
 			}
 		}