On Thu, 10 Apr 2025, Yu Kuai wrote:
> Hi,
>
> 在 2025/04/10 16:06, LongPing Wei 写道:
> > On 2025/4/10 15:36, Christoph Hellwig wrote:
> > > On Thu, Apr 10, 2025 at 11:09:04AM +0800, LongPing Wei wrote:
> > > > Fix the compile error when dm-bufio is built as a module.
> > > >
> > > > 1. dm-bufio module use blk_flush_plug();
> > > > 2. blk_flush_plug is an inline function and it calls __blk_flush_plug.
> > >
> > > Then don't call blk_flush_plug from dm-bufio, as drivers should not
> > > micro-manage plug flushing.
> > >
> > > Note that at least in current upstream and linux-next dm-bufio does
> > > not actually call blk_flush_plug, so I'm not sure where your
> > > report comes from.
> > >
> > Hi, Christoph
> >
> > Stephen reported that a compile error happened when he tried merging
> > device-mapper tree.
> >
> > > Hi all,
> > >
> > > After merging the device-mapper tree, today's linux-next build (powerpc
> > > ppc64_defconfig) failed like this:
> > >
> > > ERROR: modpost: "__blk_flush_plug" [drivers/md/dm-bufio.ko] undefined!
> > >
> > > Caused by commit
> > >
> > > 713ff5c782f5 ("dm-bufio: improve the performance of
> > > __dm_bufio_prefetch")
> > >
> > > I have used the device-mapper tree from next-20250409 for today.
> >
> >
> > More details are here.
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/device-mapper/linux-dm.git/commit/?h=for-next&id=713ff5c782f5a497bd0e93ca19607daf5bf34005
> >
>
> So, this patch has compile problem, I think it should be removed from
> dm tree.
OK, I've just removed it.
Mikulas
> BTW, I don't get it from commit message, why you need to flush plug when
> bio is not contiguous. Other than bio merge, plug is also benefit from
> batch submitting:
>
> __blk_mq_flush_plug_list
> q->mq_ops->queue_rqs(&plug->mq_list)
>
> Thanks,
> Kuai
>
> >
> >
> > https://lore.kernel.org/dm-devel/66bf8a8e-0a7d-47b8-9676-dc2e8c596...@oppo.com/T/#t
> >
> >
> > Thanks
> >
> > LongPing
> >
> > .
> >
>
