[PATCH] md/raid1,raid10: don't fail devices for invalid IO errors

[Keith Busch <kbusch@meta.com>]

From: Keith Busch <kbusch@kernel.org>

BLK_STS_INVAL indicates the IO request itself was invalid, not that the
device has failed. When raid1 treats this as a device error, it retries
on alternate mirrors which fail the same way, eventually exceeding the
read error threshold and removing the device from the array.

This happens when stacking configurations bypass bio_split_to_limits()
in the IO path: dm-raid calls md_handle_request() directly without going
through md_submit_bio(), skipping the alignment validation that would
otherwise reject invalid bios early. The invalid bio reaches the
lower block layers, which fail the bio with  BLK_STS_INVAL, and raid1
wrongly interprets this as a device failure.

Add BLK_STS_INVAL to raid1_should_handle_error() so that invalid IO
errors are propagated back to the caller rather than triggering device
removal. This is consistent with the previous kernel behavior when
alignment checks were done earlier in the direct-io path.

Fixes: 5ff3f74e145adc7 ("block: simplify direct io validity check")
Link: https://lore.kernel.org/linux-block/2982107.4sosBPzcNG@electra/
Reported-by: Tomáš Trnka <trnka@scm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/md/raid1-10.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/md/raid1-10.c b/drivers/md/raid1-10.c
index c33099925f230..56a56a4da4f83 100644
--- a/drivers/md/raid1-10.c
+++ b/drivers/md/raid1-10.c
@@ -293,8 +293,13 @@ static inline bool raid1_should_read_first(struct mddev *mddev,
  * bio with REQ_RAHEAD or REQ_NOWAIT can fail at anytime, before such IO is
  * submitted to the underlying disks, hence don't record badblocks or retry
  * in this case.
+ *
+ * BLK_STS_INVAL means the bio was not valid for the underlying device. This
+ * is a user error, not a device failure, so retrying or recording bad blocks
+ * would be wrong.
  */
 static inline bool raid1_should_handle_error(struct bio *bio)
 {
-	return !(bio->bi_opf & (REQ_RAHEAD | REQ_NOWAIT));
+	return !(bio->bi_opf & (REQ_RAHEAD | REQ_NOWAIT)) &&
+		bio->bi_status != BLK_STS_INVAL;
 }
-- 
2.52.0