Re: [PATCH 5.15.y] drbd: correctly submit flush bio on barrier

[Greg KH <greg@kroah.com>]

On Mon, May 08, 2023 at 12:55:47PM +0200, Christoph Böhmwalder wrote:
> 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@infradead.org>
> Cc: stable@vger.kernel.org
> 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>
> 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>
> (cherry picked from commit 3899d94e3831ee07ea6821c032dc297aec80586a)
> Signed-off-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com>
> ---
>  drivers/block/drbd/drbd_receiver.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

All now queued up, thanks!

greg k-h