[PATCH v2] btrfs: drop uuid_mutex in btrfs_free_extra_devids()

[PATCH v2] btrfs: drop uuid_mutex in btrfs_free_extra_devids()

[Anand Jain]

btrfs_free_extra_devids() frees the orphan fsid::devid with in
btrfs_fs_devices::devices, so we dont need uuid_mutex, instead hold the
btrfs_fs_devices::device_list_mutex.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
---
v1->v2: replace uuid_mutex with device_list_mutex instead of delete.
	change log updated.

 fs/btrfs/volumes.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2b101dc49d91..b1e5ac419ca8 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -925,7 +925,7 @@ void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step)
 	struct btrfs_device *device, *next;
 	struct btrfs_device *latest_dev = NULL;
 
-	mutex_lock(&uuid_mutex);
+	mutex_lock(&fs_devices->device_list_mutex);
 again:
 	/* This is the initialized path, it is safe to release the devices. */
 	list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) {
@@ -979,8 +979,7 @@ void btrfs_free_extra_devids(struct btrfs_fs_devices *fs_devices, int step)
 	}
 
 	fs_devices->latest_bdev = latest_dev->bdev;
-
-	mutex_unlock(&uuid_mutex);
+	mutex_unlock(&fs_devices->device_list_mutex);
 }
 
 static void free_device_rcu(struct rcu_head *head)
-- 
2.7.0

Re: [PATCH v2] btrfs: drop uuid_mutex in btrfs_free_extra_devids()

[David Sterba]

On Tue, May 22, 2018 at 05:29:29PM +0800, Anand Jain wrote:
> btrfs_free_extra_devids() frees the orphan fsid::devid with in
> btrfs_fs_devices::devices, so we dont need uuid_mutex, instead hold the
> btrfs_fs_devices::device_list_mutex.

This still lacks the reason why, the text merely repeats what the code
change does.