block: use q->elevator with ->elevator_lock held in elv_iosched_show()

[ Upstream commit 94209d27d14104ed828ca88cd5403a99162fe51a ]

Use q->elevator with ->elevator_lock held in elv_iosched_show(), since
the local cached elevator reference may become stale after getting
->elevator_lock.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20250505141805.2751237-5-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/block/elevator.c b/block/elevator.c
index 43ba4ab1ada7fd2462a44d3582de9e115973e4be..1f76e9efd771702e78825627e50d5cc36c42f1ec 100644 (file)
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -752,7 +752,6 @@ ssize_t elv_iosched_store(struct gendisk *disk, const char *buf,
 ssize_t elv_iosched_show(struct gendisk *disk, char *name)
 {
        struct request_queue *q = disk->queue;
-       struct elevator_queue *eq = q->elevator;
        struct elevator_type *cur = NULL, *e;
        int len = 0;
 
@@ -763,7 +762,7 @@ ssize_t elv_iosched_show(struct gendisk *disk, char *name)
                len += sprintf(name+len, "[none] ");
        } else {
                len += sprintf(name+len, "none ");
-               cur = eq->type;
+               cur = q->elevator->type;
        }
 
        spin_lock(&elv_list_lock);