Re: [PATCH] Btrfs: remove rcu_barrier in btrfs_close_devices

[Anand Jain <anand.jain@oracle.com>]

On 10/11/2017 02:11 PM, Anand Jain wrote:
> 
> 
> On 10/11/2017 05:51 AM, Liu Bo wrote:
>> It was introduced because btrfs used to do blkdev_put in a deferred
>> work, now that btrfs has put blkdev in place, this rcu_barrier can be
>> removed.

  On the 2nd thought, modprobe -r btrfs would still need rcu_barrier(), 
some where else outside of umount context ?

Thanks, Anand


>   Reviewed-by: Anand Jain <anand.jain@oracle.com>
> 
> Thanks, Anand
> 
> 
>> Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
>> ---
>>   fs/btrfs/volumes.c | 6 ------
>>   1 file changed, 6 deletions(-)
>>
>> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
>> index 0e8f16c..d983cea 100644
>> --- a/fs/btrfs/volumes.c
>> +++ b/fs/btrfs/volumes.c
>> @@ -958,12 +958,6 @@ int btrfs_close_devices(struct btrfs_fs_devices 
>> *fs_devices)
>>           __btrfs_close_devices(fs_devices);
>>           free_fs_devices(fs_devices);
>>       }
>> -    /*
>> -     * Wait for rcu kworkers under __btrfs_close_devices
>> -     * to finish all blkdev_puts so device is really
>> -     * free when umount is done.
>> -     */
>> -    rcu_barrier();
>>       return ret;
>>   }
>>