From: Julian Sun Date: Tue, 12 Aug 2025 15:42:57 +0000 (+0800) Subject: block: restore default wbt enablement X-Git-Tag: block-6.17-20250815^0 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=8f5845e0743bf3512b71b3cb8afe06c192d6acc4;p=linux-block.git block: restore default wbt enablement The commit 245618f8e45f ("block: protect wbt_lat_usec using q->elevator_lock") protected wbt_enable_default() with q->elevator_lock; however, it also placed wbt_enable_default() before blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q);, resulting in wbt failing to be enabled. Moreover, the protection of wbt_enable_default() by q->elevator_lock was removed in commit 78c271344b6f ("block: move wbt_enable_default() out of queue freezing from sched ->exit()"), so we can directly fix this issue by placing wbt_enable_default() after blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q);. Additionally, this issue also causes the inability to read the wbt_lat_usec file, and the scenario is as follows: root@q:/sys/block/sda/queue# cat wbt_lat_usec cat: wbt_lat_usec: Invalid argument root@q:/data00/sjc/linux# ls /sys/kernel/debug/block/sda/rqos cannot access '/sys/kernel/debug/block/sda/rqos': No such file or directory root@q:/data00/sjc/linux# find /sys -name wbt /sys/kernel/debug/tracing/events/wbt After testing with this patch, wbt can be enabled normally. Signed-off-by: Julian Sun Cc: stable@vger.kernel.org Fixes: 245618f8e45f ("block: protect wbt_lat_usec using q->elevator_lock") Reviewed-by: Nilay Shroff Reviewed-by: Yu Kuai Reviewed-by: Ming Lei Link: https://lore.kernel.org/r/20250812154257.57540-1-sunjunchao@bytedance.com Signed-off-by: Jens Axboe --- diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c index c5cf79a20842..4a7f1a349998 100644 --- a/block/blk-sysfs.c +++ b/block/blk-sysfs.c @@ -902,9 +902,9 @@ int blk_register_queue(struct gendisk *disk) if (queue_is_mq(q)) elevator_set_default(q); - wbt_enable_default(disk); blk_queue_flag_set(QUEUE_FLAG_REGISTERED, q); + wbt_enable_default(disk); /* Now everything is ready and send out KOBJ_ADD uevent */ kobject_uevent(&disk->queue_kobj, KOBJ_ADD);