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Thu, 12 Nov 2026 05:47:02 -0800 (PST) Received: from jwang-ThinkPad-T14-Gen-6.fkb.profitbricks.net ([212.227.34.98]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-498367b99bcsm17665990f8f.51.2026.11.12.05.47.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 12 Nov 2026 05:47:02 -0800 (PST) From: Jack Wang To: Yu Kuai , Song Liu , Jens Axboe , Christoph Hellwig Cc: Li Nan , Xiao Ni , linux-raid@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v4 1/2] block: suspend bio based disks around queue limits updates Date: Thu, 12 Nov 2026 14:46:59 +0100 Message-ID: <20261112134700.372702-2-jinpu.wang@cloud.ionos.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261112134700.372702-1-jinpu.wang@cloud.ionos.com> References: <20261112134700.372702-1-jinpu.wang@cloud.ionos.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit queue_attr_store() freezes the queue under q->limits_lock. For md this can deadlock: a bio parked while the array is suspended still holds a q_usage_counter reference, so the freeze waits for it, while the suspender waits for reconfig_mutex held by md_start_sync(), which waits for q->limits_lock. Add optional ->suspend() and ->resume() block_device_operations. When present, queue_attr_store() and the integrity flag_store() suspend the disk before taking q->limits_lock and commit the limits without freezing the queue. Other disks behave as before. Fixes: c99f66e4084a ("block: fix queue freeze vs limits lock order in sysfs store methods") Suggested-by: Yu Kuai Signed-off-by: Jack Wang --- block/blk-integrity.c | 10 ++++++++-- block/blk-sysfs.c | 19 +++++++++++++------ block/blk.h | 20 ++++++++++++++++++++ include/linux/blkdev.h | 7 +++++++ 4 files changed, 48 insertions(+), 8 deletions(-) diff --git a/block/blk-integrity.c b/block/blk-integrity.c index 964eebbee14d..b449e7c04eea 100644 --- a/block/blk-integrity.c +++ b/block/blk-integrity.c @@ -226,7 +226,8 @@ EXPORT_SYMBOL_GPL(blk_integrity_profile_name); static ssize_t flag_store(struct device *dev, const char *page, size_t count, unsigned char flag) { - struct request_queue *q = dev_to_disk(dev)->queue; + struct gendisk *disk = dev_to_disk(dev); + struct request_queue *q = disk->queue; struct queue_limits lim; unsigned long val; int err; @@ -235,6 +236,10 @@ static ssize_t flag_store(struct device *dev, const char *page, size_t count, if (err) return err; + err = blk_disk_suspend(disk); + if (err) + return err; + /* note that the flags are inverted vs the values in the sysfs files */ lim = queue_limits_start_update(q); if (val) @@ -242,7 +247,8 @@ static ssize_t flag_store(struct device *dev, const char *page, size_t count, else lim.integrity.flags |= flag; - err = queue_limits_commit_update_frozen(q, &lim); + err = blk_disk_commit_limits(disk, &lim); + blk_disk_resume(disk); if (err) return err; return count; diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 520972676ab4..3cbe36d04699 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -887,20 +887,27 @@ queue_attr_store(struct kobject *kobj, struct attribute *attr, return -EIO; if (entry->store_limit) { + struct queue_limits lim; ssize_t res; - struct queue_limits lim = queue_limits_start_update(q); + res = blk_disk_suspend(disk); + if (res) + return res; + + lim = queue_limits_start_update(q); res = entry->store_limit(disk, page, length, &lim); if (res < 0) { queue_limits_cancel_update(q); - return res; + goto out_resume; } - res = queue_limits_commit_update_frozen(q, &lim); - if (res) - return res; - return length; + res = blk_disk_commit_limits(disk, &lim); + if (!res) + res = length; +out_resume: + blk_disk_resume(disk); + return res; } return entry->store(disk, page, length); diff --git a/block/blk.h b/block/blk.h index ed2172472622..1c214f0bc178 100644 --- a/block/blk.h +++ b/block/blk.h @@ -661,6 +661,26 @@ void drop_partition(struct block_device *part); void bdev_set_nr_sectors(struct block_device *bdev, sector_t sectors); +/* Suspend before queue_limits_start_update(), never under q->limits_lock. */ +static inline int blk_disk_suspend(struct gendisk *disk) +{ + return disk->fops->suspend ? disk->fops->suspend(disk) : 0; +} + +static inline void blk_disk_resume(struct gendisk *disk) +{ + if (disk->fops->suspend) + disk->fops->resume(disk); +} + +static inline int blk_disk_commit_limits(struct gendisk *disk, + struct queue_limits *lim) +{ + if (disk->fops->suspend) + return queue_limits_commit_update(disk->queue, lim); + return queue_limits_commit_update_frozen(disk->queue, lim); +} + struct gendisk *__alloc_disk_node(struct request_queue *q, int node_id, struct lock_class_key *lkclass); struct request_queue *blk_alloc_queue(struct queue_limits *lim, int node_id); diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 0c2010230632..0011b7c0740f 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -1601,6 +1601,13 @@ struct block_device_operations { enum blk_unique_id id_type); int (*init_dma_buf_io_ctx)(struct block_device *, struct dma_buf_io_ctx *); + /* + * Optional, for bio based drivers that cannot be frozen under + * q->limits_lock: stop I/O around a sysfs limits update. Called + * before q->limits_lock is taken, with no queue frozen. + */ + int (*suspend)(struct gendisk *disk); + void (*resume)(struct gendisk *disk); struct module *owner; const struct pr_ops *pr_ops; -- 2.43.0