[PATCHv3 7/7] block: protect read_ahead_kb using q->limits_lock
From: Nilay Shroff <hidden>
Date: 2025-02-24 13:33:31
Subsystem:
block layer, the rest · Maintainers:
Jens Axboe, Linus Torvalds
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. Signed-off-by: Nilay Shroff <redacted> --- block/blk-sysfs.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c
index 8f47d9f30fbf..228f81a9060f 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 protected with q->sysfs_lock + * attributes which require some form of locking + * other than q->sysfs_lock */ &queue_ra_entry.attr,
--
2.47.1