From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ming Lei Subject: Re: [PATCH 3/4] dm: fix missing bio_split() pattern code in __split_and_process_bio() Date: Mon, 21 Jan 2019 11:21:54 +0800 Message-ID: <20190121032153.GA24610@ming.t460p> References: <20190119180506.1300-1-snitzer@redhat.com> <20190119180506.1300-4-snitzer@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <20190119180506.1300-4-snitzer@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Mike Snitzer Cc: axboe@kernel.dk, linux-block@vger.kernel.org, dm-devel@redhat.com, NeilBrown List-Id: dm-devel.ids On Sat, Jan 19, 2019 at 01:05:05PM -0500, Mike Snitzer wrote: > Use the same BIO_QUEUE_ENTERED pattern that was established by commit > cd4a4ae4683dc ("block: don't use blocking queue entered for recursive > bio submits") by setting BIO_QUEUE_ENTERED after bio_split() and before > recursing via generic_make_request(). > > Also add trace_block_split() because it provides useful context about > bio splits in blktrace. > > Depends-on: cd4a4ae4683dc ("block: don't use blocking queue entered for recursive bio submits") > Fixes: 18a25da84354 ("dm: ensure bio submission follows a depth-first tree walk") > Cc: stable@vger.kernel.org # 4.16+ > Signed-off-by: Mike Snitzer > --- > drivers/md/dm.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/drivers/md/dm.c b/drivers/md/dm.c > index fbadda68e23b..6e29c2d99b99 100644 > --- a/drivers/md/dm.c > +++ b/drivers/md/dm.c > @@ -1654,7 +1654,9 @@ static blk_qc_t __split_and_process_bio(struct mapped_device *md, > sectors[op_stat_group(bio_op(bio))], ci.sector_count); > part_stat_unlock(); > > + bio_set_flag(bio, BIO_QUEUE_ENTERED); > bio_chain(b, bio); > + trace_block_split(md->queue, b, bio->bi_iter.bi_sector); > ret = generic_make_request(bio); > break; > } In theory, BIO_QUEUE_ENTERED is only required when __split_and_process_bio() is called from generic_make_request(). However, it may be called from dm_wq_work(), this way might cause trouble on operation to q->q_usage_counter. Thanks, Ming