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Wed, 02 Apr 2025 03:56:04 -0400 X-MC-Unique: P2iQS-ofMpiCrfJmsleAaw-1 X-Mimecast-MFC-AGG-ID: P2iQS-ofMpiCrfJmsleAaw_1743580563 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id EF9C91800A36; Wed, 2 Apr 2025 07:56:02 +0000 (UTC) Received: from fedora (unknown [10.72.120.32]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 6858D195609D; Wed, 2 Apr 2025 07:55:57 +0000 (UTC) Date: Wed, 2 Apr 2025 15:55:51 +0800 From: Ming Lei To: Jens Axboe , linux-block@vger.kernel.org Cc: Valdis =?utf-8?Q?Kl=C4=93tnieks?= , Nilay Shroff , Christoph Hellwig Subject: Re: [PATCH 1/3] block: add blk_mq_enter_no_io() and blk_mq_exit_no_io() Message-ID: References: <20250402043851.946498-1-ming.lei@redhat.com> <20250402043851.946498-2-ming.lei@redhat.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250402043851.946498-2-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On Wed, Apr 02, 2025 at 12:38:47PM +0800, Ming Lei wrote: > Add blk_mq_enter_no_io() and blk_mq_exit_no_io() for preventing queue > from handling any FS or passthrough IO, meantime the queue is kept in > non-freeze state. > > The added two APIs are for avoiding many potential lock risk related > with freeze lock. > > Also add two variants of memsave version. > > Signed-off-by: Ming Lei > --- > block/blk-core.c | 6 ++++-- > block/blk-mq.c | 18 ++++++++++++++++-- > block/blk-mq.h | 19 +++++++++++++++++++ > block/blk.h | 5 +++-- > include/linux/blkdev.h | 8 ++++++++ > 5 files changed, 50 insertions(+), 6 deletions(-) > > diff --git a/block/blk-core.c b/block/blk-core.c > index 4623de79effa..a54a18fada8a 100644 > --- a/block/blk-core.c > +++ b/block/blk-core.c > @@ -319,7 +319,8 @@ int blk_queue_enter(struct request_queue *q, blk_mq_req_flags_t flags) > smp_rmb(); > wait_event(q->mq_freeze_wq, > (!q->mq_freeze_depth && > - blk_pm_resume_queue(pm, q)) || > + (blk_pm_resume_queue(pm, q) || > + !blk_queue_no_io(q))) || > blk_queue_dying(q)); > if (blk_queue_dying(q)) > return -ENODEV; > @@ -352,7 +353,8 @@ int __bio_queue_enter(struct request_queue *q, struct bio *bio) > smp_rmb(); > wait_event(q->mq_freeze_wq, > (!q->mq_freeze_depth && > - blk_pm_resume_queue(false, q)) || > + (blk_pm_resume_queue(false, q) || Here the above '||' should have been '&&'. > + !blk_queue_no_io(q))) || > test_bit(GD_DEAD, &disk->state)); > if (test_bit(GD_DEAD, &disk->state)) > goto dead; > diff --git a/block/blk-mq.c b/block/blk-mq.c > index ae8494d88897..075ee51066b3 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -222,8 +222,7 @@ bool __blk_mq_unfreeze_queue(struct request_queue *q, bool force_atomic) > bool unfreeze; > > mutex_lock(&q->mq_freeze_lock); > - if (force_atomic) > - q->q_usage_counter.data->force_atomic = true; > + q->q_usage_counter.data->force_atomic = force_atomic; > q->mq_freeze_depth--; > WARN_ON_ONCE(q->mq_freeze_depth < 0); > if (!q->mq_freeze_depth) { > @@ -278,6 +277,21 @@ void blk_mq_quiesce_queue_nowait(struct request_queue *q) > } > EXPORT_SYMBOL_GPL(blk_mq_quiesce_queue_nowait); > > +void blk_mq_enter_no_io(struct request_queue *q) > +{ > + blk_mq_freeze_queue_nomemsave(q); > + q->no_io = true; > + if (__blk_mq_unfreeze_queue(q, true)) > + blk_unfreeze_release_lock(q); > +} > + > +void blk_mq_exit_no_io(struct request_queue *q) > +{ > + blk_mq_freeze_queue_nomemsave(q); > + q->no_io = false; > + blk_mq_unfreeze_queue_nomemrestore(q); > +} > + > /** > * blk_mq_wait_quiesce_done() - wait until in-progress quiesce is done > * @set: tag_set to wait on > diff --git a/block/blk-mq.h b/block/blk-mq.h > index 3011a78cf16a..f49070c8c05f 100644 > --- a/block/blk-mq.h > +++ b/block/blk-mq.h > @@ -452,4 +452,23 @@ static inline bool blk_mq_can_poll(struct request_queue *q) > q->tag_set->map[HCTX_TYPE_POLL].nr_queues; > } > > +void blk_mq_enter_no_io(struct request_queue *q); > +void blk_mq_exit_no_io(struct request_queue *q); > + > +static inline unsigned int __must_check > +blk_mq_enter_no_io_memsave(struct request_queue *q) > +{ > + unsigned int memflags = memalloc_noio_save(); > + > + blk_mq_enter_no_io(q); > + return memflags; > +} > + > +static inline void > +blk_mq_exit_no_io_memrestore(struct request_queue *q, unsigned int memflags) > +{ > + blk_mq_exit_no_io(q); > + memalloc_noio_restore(memflags); > +} > + > #endif > diff --git a/block/blk.h b/block/blk.h > index 006e3be433d2..7d0994c1d3ad 100644 > --- a/block/blk.h > +++ b/block/blk.h > @@ -56,8 +56,9 @@ static inline bool blk_try_enter_queue(struct request_queue *q, bool pm) > * The code that increments the pm_only counter must ensure that the > * counter is globally visible before the queue is unfrozen. > */ > - if (blk_queue_pm_only(q) && > - (!pm || queue_rpm_status(q) == RPM_SUSPENDED)) > + if ((blk_queue_pm_only(q) && > + (!pm || queue_rpm_status(q) == RPM_SUSPENDED)) || Same with above. Thanks, Ming