Re: [PATCH] null_blk: fix spurious IO errors after failed past-wp access

[Christoph Hellwig <hch@infradead.org>]

On Wed, Feb 12, 2020 at 11:23:20PM +0300, Alexey Dobriyan wrote:
> Steps to reproduce:
> 
> 	BLKRESETZONE zone 0
> 
> 	// force EIO
> 	pwrite(fd, buf, 4096, 4096);
> 
> 	[issue more IO including zone ioctls]
> 
> It will start failing randomly including IO to unrelated zones because of
> ->error "reuse". Trigger can be partition detection as well if test is not
> run immediately which is even more entertaining.
> 
> The fix is of course to clear ->error where necessary.
> 
> Signed-off-by: Alexey Dobriyan (SK hynix) <adobriyan@gmail.com>
> ---
> 
>  drivers/block/null_blk_main.c |    2 ++
>  1 file changed, 2 insertions(+)
> 
> --- a/drivers/block/null_blk_main.c
> +++ b/drivers/block/null_blk_main.c
> @@ -605,6 +605,7 @@ static struct nullb_cmd *__alloc_cmd(struct nullb_queue *nq)
>  	if (tag != -1U) {
>  		cmd = &nq->cmds[tag];
>  		cmd->tag = tag;
> +		cmd->error = BLK_STS_OK;

I'd place this line in null_queue_bio to match the blk-mq patch
more closely.

Otherwise this looks fine:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Can you add your testcase to blktests?