| Message ID | 20230502092922.175857-1-christoph.boehmwalder@linbit.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drbd: do not set REQ_PREFLUSH when submitting barrier | expand |
On Tue, May 02, 2023 at 11:29:22AM +0200, Christoph Böhmwalder wrote: > struct bio *bio = bio_alloc(device->ldev->backing_bdev, 0, > - REQ_OP_FLUSH | REQ_PREFLUSH, GFP_NOIO); > + REQ_OP_FLUSH, GFP_NOIO); This isn't going to work. flush bios are (somewhat confusingly) implemented as writes with no data and the preflush flag. So this should be: REQ_OP_WRITE | REQ_PREFLUSH. and it looks like whatever flushing this does hasn't wroked for a long time.
Am 03.05.23 um 06:18 schrieb Christoph Hellwig: > On Tue, May 02, 2023 at 11:29:22AM +0200, Christoph Böhmwalder wrote: >> struct bio *bio = bio_alloc(device->ldev->backing_bdev, 0, >> - REQ_OP_FLUSH | REQ_PREFLUSH, GFP_NOIO); >> + REQ_OP_FLUSH, GFP_NOIO); > > This isn't going to work. flush bios are (somewhat confusingly) Indeed... > implemented as writes with no data and the preflush flag. So this > should be: > > REQ_OP_WRITE | REQ_PREFLUSH. > > and it looks like whatever flushing this does hasn't wroked for a long > time. Thanks for the hint. I'll prepare a v2 today.
diff --git a/drivers/block/drbd/drbd_receiver.c b/drivers/block/drbd/drbd_receiver.c index e54404c632e7..f2479c29197a 100644 --- 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 *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_FLUSH, GFP_NOIO); struct one_flush_context *octx = kmalloc(sizeof(*octx), GFP_NOIO); if (!octx) {
When we receive a flush command (or "barrier" in DRBD), we currently use a REQ_OP_FLUSH with the REQ_PREFLUSH flag set. REQ_OP_FLUSH is supposed to be an empty bio with the sole purpose of flushing the disk. REQ_PREFLUSH is used for REQ_OP_WRITE bios to additionally signal that a flush should be issued, so it is redundant here. Since commit b4a6bb3a67aa ("block: add a sanity check for non-write flush/fua bios"), this triggers a warning in the block layer. So remove the REQ_PREFLUSH flag when allocating the bio. Fixes: f9ff0da56437 ("drbd: allow parallel flushes for multi-volume resources") Reported-by: Thomas Voegtle <tv@lio96.de> Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> --- drivers/block/drbd/drbd_receiver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)