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Wed, 26 Feb 2025 12:40:44 +0000 Received: from smtpav01.fra02v.mail.ibm.com (smtpav01.fra02v.mail.ibm.com [10.20.54.100]) by smtprelay07.fra02v.mail.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 51QCegaE46399924 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 Feb 2025 12:40:42 GMT Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 31AA320040; Wed, 26 Feb 2025 12:40:42 +0000 (GMT) Received: from smtpav01.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B47282004B; Wed, 26 Feb 2025 12:40:38 +0000 (GMT) Received: from li-c9696b4c-3419-11b2-a85c-f9edc3bf8a84.ibm.com.com (unknown [9.61.110.139]) by smtpav01.fra02v.mail.ibm.com (Postfix) with ESMTP; Wed, 26 Feb 2025 12:40:38 +0000 (GMT) From: Nilay Shroff To: linux-block@vger.kernel.org Cc: hch@lst.de, ming.lei@redhat.com, dlemoal@kernel.org, hare@suse.de, axboe@kernel.dk, gjoyce@ibm.com Subject: [PATCHv5 7/7] block: protect read_ahead_kb using q->limits_lock Date: Wed, 26 Feb 2025 18:10:00 +0530 Message-ID: <20250226124006.1593985-8-nilay@linux.ibm.com> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20250226124006.1593985-1-nilay@linux.ibm.com> References: <20250226124006.1593985-1-nilay@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ikhBmKJRMsDbMbHO5_T__WZOu6pclLoE X-Proofpoint-GUID: ikhBmKJRMsDbMbHO5_T__WZOu6pclLoE X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1057,Hydra:6.0.680,FMLib:17.12.68.34 definitions=2025-02-26_02,2025-02-26_01,2024-11-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 suspectscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 mlxlogscore=994 spamscore=0 mlxscore=0 malwarescore=0 adultscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.19.0-2502100000 definitions=main-2502260100 The bdi->ra_pages could be updated under q->limits_lock because it's usually calculated from the queue limits by queue_limits_commit_update. So protect reading/writing the sysfs attribute read_ahead_kb using q->limits_lock instead of q->sysfs_lock. Reviewed-by: Hannes Reinecke Signed-off-by: Nilay Shroff --- block/blk-sysfs.c | 16 ++++++++++------ include/linux/blkdev.h | 3 +++ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index 46033d640e30..67c5c4cee6b4 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -93,9 +93,9 @@ static ssize_t queue_ra_show(struct gendisk *disk, char *page) { ssize_t ret; - mutex_lock(&disk->queue->sysfs_lock); + mutex_lock(&disk->queue->limits_lock); ret = queue_var_show(disk->bdi->ra_pages << (PAGE_SHIFT - 10), page); - mutex_unlock(&disk->queue->sysfs_lock); + mutex_unlock(&disk->queue->limits_lock); return ret; } @@ -111,12 +111,15 @@ queue_ra_store(struct gendisk *disk, const char *page, size_t count) ret = queue_var_store(&ra_kb, page, count); if (ret < 0) return ret; - - mutex_lock(&q->sysfs_lock); + /* + * ->ra_pages is protected by ->limits_lock because it is usually + * calculated from the queue limits by queue_limits_commit_update. + */ + mutex_lock(&q->limits_lock); memflags = blk_mq_freeze_queue(q); disk->bdi->ra_pages = ra_kb >> (PAGE_SHIFT - 10); + mutex_unlock(&q->limits_lock); blk_mq_unfreeze_queue(q, memflags); - mutex_unlock(&q->sysfs_lock); return ret; } @@ -670,7 +673,8 @@ static struct attribute *queue_attrs[] = { &queue_dma_alignment_entry.attr, /* - * Attributes which are protected with q->sysfs_lock. + * Attributes which require some form of locking other than + * q->sysfs_lock. */ &queue_ra_entry.attr, diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h index 0ee3b5c9388e..3bee1b4858b6 100644 --- a/include/linux/blkdev.h +++ b/include/linux/blkdev.h @@ -571,6 +571,9 @@ struct request_queue { struct mutex elevator_lock; struct mutex sysfs_lock; + /* + * Protects queue limits and also sysfs attribute read_ahead_kb. + */ struct mutex limits_lock; /*