Re: [PATCH] drbd: always set BLK_FEAT_STABLE_WRITES

Christoph Hellwig <[email protected]> Thu, 12 Feb 2026 22:05:54 -0800

Newsgroups	dev.linux.lists.drbd-dev,org.kernel.vger.linux-block,org.kernel.vger.linux-kernel
Message-ID	<[email protected]>

On Thu, Feb 12, 2026 at 04:01:43PM +0100, Christoph BÃ¶hmwalder wrote:
> The current block layer logic actually seems correct to me. The
> underlying device may or may not require stable writes, but regardless
> of that, DRBD itself definitely does need it. In blk_stack_limits, DRBD
> is the top device, and DRBD's backing disk is the bottom device. If the
> backing disk happens to require stable writes, this would indeed be
> correctly inherited.
> 
> So the only missing logic is that DRBD still wants to enable stable
> writes for itself even if the backing disk does *not* request it.
> So it seems to me that this patch is the correct fix for DRBD's special
> case.
> 
> Is it not supposed to work like that?

No, I guess I just misunderstood your report.