From 84be0f189cf043ea40850378a8de77b9cffbc5c0 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 26 Jan 2022 15:23:45 +0100 Subject: [PATCH] loop: only take lo_mutex for the first reference in lo_open lo_refcnt is only incremented in lo_open and decremented in lo_release, and thus protected by open_mutex. Only take lo_mutex when lo_open is called the first time, as only for the first open there is any affect on the driver state (incremental opens on partitions don't end up in lo_open at all already). Signed-off-by: Christoph Hellwig --- drivers/block/loop.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 43980ec69dfd..4b0058a67c48 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1725,13 +1725,16 @@ static int lo_open(struct block_device *bdev, fmode_t mode) struct loop_device *lo = bdev->bd_disk->private_data; int err; + if (atomic_inc_return(&lo->lo_refcnt) > 1) + return 0; + err = mutex_lock_killable(&lo->lo_mutex); if (err) return err; - if (lo->lo_state == Lo_deleting) + if (lo->lo_state == Lo_deleting) { + atomic_dec(&lo->lo_refcnt); err = -ENXIO; - else - atomic_inc(&lo->lo_refcnt); + } mutex_unlock(&lo->lo_mutex); return err; } -- 2.50.1