From: Sebastian Riemer <sebastian.riemer@xxxxxxxxxxxxxxxx>
commit bbfa57c0f2243a7c31fd248d22e9861a2802cad5 upstream.
If an fsync occurs on a read-only array, we need to send a
completion for the IO and may not increment the active IO count.
Otherwise, we hit a bug trace and can't stop the MD array anymore.
By advice of Christoph Hellwig we return success upon a flush
request but we return -EROFS for other writes.
We detect flush requests by checking if the bio has zero sectors.
This patch is suitable to any -stable kernel to which it applies.
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Sebastian Riemer <sebastian.riemer@xxxxxxxxxxxxxxxx>
Reported-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Acked-by: Paul Menzel <paulepanter@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
[bwh: Backported to 3.0: md_make_request() returns 0 on error]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
I noticed you didn't apply this to 3.0.y. It looks like a simple enough
change - but this is compile-tested only.
Ben.
drivers/md/md.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 3db3d1b..1e634a6 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -299,6 +299,10 @@ static void md_make_request(struct request_queue *q, struct bio *bio)
bio_io_error(bio);
return 0;
}
+ if (mddev->ro == 1 && unlikely(rw == WRITE)) {
+ bio_endio(bio, bio_sectors(bio) == 0 ? 0 : -EROFS);
+ return 0;
+ }
smp_rmb(); /* Ensure implications of 'active' are visible */
rcu_read_lock();
if (mddev->suspended) {
--
Ben Hutchings
Humans are not rational beings; they are rationalising beings.
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