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-rw-r--r--include/linux/blkdev.h10
1 files changed, 6 insertions, 4 deletions
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 31b1b635c710..3e66ad016a23 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -561,10 +561,12 @@ struct request_queue {
struct list_head flush_list;
/*
- * Protects against I/O scheduler switching, specifically when
- * updating q->elevator. To ensure proper locking order during
- * an elevator update, first freeze the queue, then acquire
- * ->elevator_lock.
+ * Protects against I/O scheduler switching, particularly when
+ * updating q->elevator. Since the elevator update code path may
+ * also modify q->nr_requests, this lock also protects the sysfs
+ * attribute nr_requests.
+ * To ensure proper locking order during an elevator update, first
+ * freeze the queue, then acquire ->elevator_lock.
*/
struct mutex elevator_lock;