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 b4a6bb3a67 ("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@infradead.org>
Cc: stable@vger.kernel.org
Fixes: f9ff0da564 ("drbd: allow parallel flushes for multi-volume resources")
Reported-by: Thomas Voegtle <tv@lio96.de>
Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20230503121937.17232-1-christoph.boehmwalder@linbit.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
3899d94e38