Re: [PATCH 1/5] btrfs: fix comment its device list mutex not volume lock

[Nikolay Borisov <nborisov@suse.com>]

On 8.02.19 г. 9:16 ч., Anand Jain wrote:
> 
> 
> On 2/8/19 3:07 PM, Nikolay Borisov wrote:
>>
>>
>> On 8.02.19 г. 9:02 ч., Anand Jain wrote:
>>> We have killed volume mutex (commit: dccdb07bc996
>>> btrfs: kill btrfs_fs_info::volume_mutex) update comment. This a
>>> trival one
>>> seems to have escaped.
>>>
>>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>>> ---
>>>   fs/btrfs/volumes.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>>> index fe122e6099ae..8160749cd9ba 100644
>>> --- a/fs/btrfs/volumes.c
>>> +++ b/fs/btrfs/volumes.c
>>> @@ -1129,7 +1129,7 @@ static struct btrfs_fs_devices
>>> *clone_fs_devices(struct btrfs_fs_devices *orig)
>>>       mutex_lock(&orig->device_list_mutex);
>>>       fs_devices->total_devices = orig->total_devices;
>>>   -    /* We have held the volume lock, it is safe to get the
>>> devices. */
>>> +    /* We have held the device_list_mutex, it is safe to get the
>>> devices. */
>>
>> I'd rather have the comment replaced with lockdep_assert_held it's a lot
>> more eloquent.
> 
>   I agree if we don't acquire the required lock in the same function,
>   but here, we call the required mutex_lock(&orig->device_list_mutex);
>   just three lines above in the same function.
> 
>   Where do we need the lockdep_assert_held()?

You are right I missed that. In that case I'd say just remove the
comment it should be obvious what's happening.

> 
> -Anand
> 
>>>       list_for_each_entry(orig_dev, &orig->devices, dev_list) {
>>>           struct rcu_string *name;
>>>  
>