[PATCH] md/md-llbitmap: don't skip reshape ranges from bitmap state

[Yu Kuai <yukuai@kernel.org>]

From: Yu Kuai <yukuai@fygo.io>

Reshape progress is tracked by array metadata rather than llbitmap.
Do not let llbitmap skip_sync_blocks() suppress reshape ranges based on
stale bitmap state before the corresponding checkpoint is persisted.

Signed-off-by: Yu Kuai <yukuai@fygo.io>
---
 drivers/md/md-llbitmap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/md/md-llbitmap.c b/drivers/md/md-llbitmap.c
index 76621a9fd645..67e63d81a824 100644
--- a/drivers/md/md-llbitmap.c
+++ b/drivers/md/md-llbitmap.c
@@ -1644,10 +1644,18 @@ static sector_t llbitmap_skip_sync_blocks(struct mddev *mddev, sector_t offset)
 
 	if (p >= llbitmap->chunks)
 		return 0;
 	c = llbitmap_read(llbitmap, p);
 
+	/*
+	 * Reshape progress is tracked by array metadata rather than llbitmap.
+	 * Skipping reshape ranges from stale bitmap state can lose data after a
+	 * restart before the corresponding bits are checkpointed to disk.
+	 */
+	if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+		return 0;
+
 	/* always skip unwritten blocks */
 	if (c == BitUnwritten)
 		return blocks;
 
 	/* Skip CleanUnwritten - no user data, will be reset after recovery */
-- 
2.51.0