This is a note to let you know that I've just added the patch titled drbd: correctly submit flush bio on barrier to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: drbd-correctly-submit-flush-bio-on-barrier.patch and it can be found in the queue-4.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 3899d94e3831ee07ea6821c032dc297aec80586a Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Christoph=20B=C3=B6hmwalder?= <christoph.boehmwalder@xxxxxxxxxx> Date: Wed, 3 May 2023 14:19:37 +0200 Subject: drbd: correctly submit flush bio on barrier MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Christoph Böhmwalder <christoph.boehmwalder@xxxxxxxxxx> commit 3899d94e3831ee07ea6821c032dc297aec80586a upstream. When we receive a flush command (or "barrier" in DRBD), we currently use a REQ_OP_FLUSH with the REQ_PREFLUSH flag set. The correct way to submit a flush bio is by using a REQ_OP_WRITE without any data, and set the REQ_PREFLUSH flag. Since commit b4a6bb3a67aa ("block: add a sanity check for non-write flush/fua bios"), this triggers a warning in the block layer, but this has been broken for quite some time before that. So use the correct set of flags to actually make the flush happen. Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Fixes: f9ff0da56437 ("drbd: allow parallel flushes for multi-volume resources") Reported-by: Thomas Voegtle <tv@xxxxxxxx> Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@xxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Link: https://lore.kernel.org/r/20230503121937.17232-1-christoph.boehmwalder@xxxxxxxxxx Signed-off-by: Jens Axboe <axboe@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/block/drbd/drbd_receiver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/block/drbd/drbd_receiver.c +++ b/drivers/block/drbd/drbd_receiver.c @@ -1309,7 +1309,7 @@ static void submit_one_flush(struct drbd bio_set_dev(bio, device->ldev->backing_bdev); bio->bi_private = octx; bio->bi_end_io = one_flush_endio; - bio->bi_opf = REQ_OP_FLUSH | REQ_PREFLUSH; + bio->bi_opf = REQ_OP_WRITE | REQ_PREFLUSH; device->flush_jif = jiffies; set_bit(FLUSH_PENDING, &device->flags); Patches currently in stable-queue which might be from christoph.boehmwalder@xxxxxxxxxx are queue-4.14/drbd-correctly-submit-flush-bio-on-barrier.patch