[PATCH 6.12.y] xfs: don't queue rmap update twice when reaping a fork

[Sasha Levin <sashal@kernel.org>]

From: "Darrick J. Wong" <djwong@kernel.org>

[ Upstream commit 219ff8a734d8438e24eb346a847c9b1ad9b7ab5d ]

LOLLM noticed that xrep_reap_bmapi_iter calls xfs_bmap_unmap_extent and
xfs_rmap_unmap_extent to remove a mapping from a file fork and its
reverse mapping.  However, xfs_bmap_del_extent_real also queues a
deferred rmap removal log item, which means that we incorrectly queue
two rmap removal operations.  Fix that by removing the extra call and
updating the comment to mention this subtlety that I forgot, having
written the code. :P

Cc: stable@vger.kernel.org # v6.10
Fixes: 5befb047b9f4de ("xfs: add the ability to reap entire inode forks")
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Assisted-by: LOLLM # finding obvious bugs
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Carlos Maiolino <cem@kernel.org>
[ sashal: Adapted rs->ip and rs->whichfork references to direct ip and whichfork arguments. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/xfs/scrub/reap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/xfs/scrub/reap.c b/fs/xfs/scrub/reap.c
index 4ce345ae4565e..0c827798ade67 100644
--- a/fs/xfs/scrub/reap.c
+++ b/fs/xfs/scrub/reap.c
@@ -905,12 +905,12 @@ xrep_reap_bmapi_iter(
 		/*
 		 * Schedule removal of the mapping from the fork.  We use
 		 * deferred log intents in this function to control the exact
-		 * sequence of metadata updates.
+		 * sequence of metadata updates.  The BUI queues a RUI to
+		 * remove the reverse mapping.
 		 */
 		xfs_bmap_unmap_extent(sc->tp, ip, whichfork, imap);
 		xfs_trans_mod_dquot_byino(sc->tp, ip, XFS_TRANS_DQ_BCOUNT,
 				-(int64_t)imap->br_blockcount);
-		xfs_rmap_unmap_extent(sc->tp, ip, whichfork, imap);
 		return 0;
 	}
 
-- 
2.53.0