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 @@ -1283,7 +1283,7 @@ static void one_flush_endio(struct bio * static void submit_one_flush(struct drbd_device *device, struct issue_flush_context *ctx) { struct bio *bio = bio_alloc(device->ldev->backing_bdev, 0, - REQ_OP_FLUSH | REQ_PREFLUSH, GFP_NOIO); + REQ_OP_WRITE | REQ_PREFLUSH, GFP_NOIO); struct one_flush_context *octx = kmalloc(sizeof(*octx), GFP_NOIO); if (!octx) {