Re: [PATCH] blk-merge: fix blk_recount_segments

Jens Axboe
2014-09-02T16:24:39Z

On 09/02/2014 09:02 AM, Ming Lei wrote:
> QUEUE_FLAG_NO_SG_MERGE is set at default for blk-mq devices,
> so bio->bi_phys_segment computed may be bigger than
> queue_max_segments(q) for blk-mq devices, then drivers will
> fail to handle the case, for example, BUG_ON() in
> virtio_queue_rq() can be triggerd for virtio-blk:
>
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1359146
>
> This patch fixes the issue by ignoring the QUEUE_FLAG_NO_SG_MERGE
> flag if the computed bio->bi_phys_segment is bigger than
> queue_max_segments(q), and the regression is caused by commit
> 05f1dd53152173(block: add queue flag for disabling SG merging).
>
> Reported-by: Kick In <pierre-andre.morey@canonical.com>
> Tested-by: Chris J Arges <chris.j.arges@canonical.com>
> Signed-off-by: Ming Lei <ming.lei@canonical.com>

Thanks Ming, this looks nice and clean. Will apply for 3.17.

--
Jens Axboe