Re: [RFC PATCH v1 06/17] blk-cgroup: support non-blocking bio association

Christoph Hellwig <[email protected]> Thu, 9 Jul 2026 08:13:49 +0200

Newsgroups	org.kernel.vger.linux-bcache,dev.linux.lists.dm-devel,org.infradead.lists.linux-nvme,org.kernel.vger.cgroups,org.kernel.vger.linux-block
Message-ID	<[email protected]>

On Sun, Jul 05, 2026 at 03:51:13AM +0800, Yu Kuai wrote:
> From: Yu Kuai <[email protected]>
> 
> Allow bio association helpers to be called from non-blocking paths by
> returning whether the association succeeded and by taking a nowait argument.
> The normal callers pass nowait=false and keep the existing behavior of
> creating missing blkgs.
> 
> For nowait=true, the helper only succeeds when the needed blkg already
> exists.  This lets callers set or clone a bio's bdev without entering the
> sleepable missing-blkg creation path.

I think this is not needed once we kill nonblocking bio allocations,
but if not please have a clearly visible separate API for the
non-blocking version.