Re: [PATCH] raid1: include bio_end_io_list in nr_queued to prevent freeze_array hang

[Shaohua Li <shli@kernel.org>]

On Sun, Mar 06, 2016 at 03:33:04PM -0800, Shaohua Li wrote:
> On Mon, Feb 29, 2016 at 10:43:58AM -0500, Nate Dailey wrote:
> > If raid1d is handling a mix of read and write errors, handle_read_error's
> > call to freeze_array can get stuck.
> > 
> > This can happen because, though the bio_end_io_list is initially drained,
> > writes can be added to it via handle_write_finished as the retry_list
> > is processed. These writes contribute to nr_pending but are not included
> > in nr_queued.
> > 
> > If a later entry on the retry_list triggers a call to handle_read_error,
> > freeze array hangs waiting for nr_pending == nr_queued+extra. The writes
> > on the bio_end_io_list aren't included in nr_queued so the condition will
> > never be satisfied.
> > 
> > To prevent the hang, include bio_end_io_list writes in nr_queued.
> > 
> > There's probably a better way to handle decrementing nr_queued, but this
> > seemed like the safest way to avoid breaking surrounding code.
> > 
> > I'm happy to supply the script I used to repro this hang.
> 
> Looks good. Could you please also fix raid10?

Alright, I applied the patch and added raid10 part so this can be applied to 4.6