Re: [PATCH -next 2/3] md/raid10: convert resync_lock to use seqlock

[Guoqing Jiang]

On 9/2/22 2:41 AM, Logan Gunthorpe wrote:
> Hi,
>
> On 2022-08-29 07:15, Yu Kuai wrote:
> > From: Yu Kuai <yukuai3@xxxxxxxxxx>
> >
> > Currently, wait_barrier() will hold 'resync_lock' to read 'conf->barrier',
> > and io can't be dispatched until 'barrier' is dropped.
> >
> > Since holding the 'barrier' is not common, convert 'resync_lock' to use
> > seqlock so that holding lock can be avoided in fast path.
> >
> > Signed-off-by: Yu Kuai <yukuai3@xxxxxxxxxx>
> I've found some lockdep issues starting with this patch in md-next while
> running mdadm tests (specifically 00raid10 when run about 10 times in a
> row).
>
> I've seen a couple different lock dep errors. The first seems to be
> reproducible on this patch, then it possibly changes to the second on
> subsequent patches. Not sure exactly.

That's why I said "try mdadm test suites too to avoid regression." ...

Guoqing