Re: [PATCH 7/9] btrfs: quiten warn if the replace is canceled at finish

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

On 11/15/2018 11:35 PM, David Sterba wrote:
> On Sun, Nov 11, 2018 at 10:22:22PM +0800, Anand Jain wrote:
>> When we successfully cancel the replace its scrub returns -ECANCELED,
>> which then passed to btrfs_dev_replace_finishing(), it cleans up based
>> on the scrub returned status and propagates the same -ECANCELED back
>> the parent function. As of now only user can cancel the replace-scrub,
>> so its ok to quieten the warn here.
>>
>> Signed-off-by: Anand Jain <anand.jain@oracle.com>
>> ---
>>   fs/btrfs/dev-replace.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/btrfs/dev-replace.c b/fs/btrfs/dev-replace.c
>> index 1dc8e86546db..9031a362921a 100644
>> --- a/fs/btrfs/dev-replace.c
>> +++ b/fs/btrfs/dev-replace.c
>> @@ -497,7 +497,7 @@ static int btrfs_dev_replace_start(struct btrfs_fs_info *fs_info,
>>   	ret = btrfs_dev_replace_finishing(fs_info, ret);
>>   	if (ret == -EINPROGRESS) {
>>   		ret = BTRFS_IOCTL_DEV_REPLACE_RESULT_SCRUB_INPROGRESS;
>> -	} else {
>> +	} else if (ret != -ECANCELED) {
>>   		WARN_ON(ret);
> 
> While this looks ok, can you please rework it so there are no WARN_ON at
> random places in device-replace, poorly substituting error handling?
> 
> The code flow in this case could be changed to make explicit checks for
> the know codes and then a catch-all branch like:
> 
> if (ret == -EINPROGRESS) {
> ...
> } else (if == -ESOMETHINGELSE) {
> ...
> } else {
> 	unknown error, print error and do a proper cleanup
> }
> 

As below..

>>   	}
>>   
>> @@ -954,7 +954,7 @@ static int btrfs_dev_replace_kthread(void *data)
>>   			      btrfs_device_get_total_bytes(dev_replace->srcdev),
>>   			      &dev_replace->scrub_progress, 0, 1);
>>   	ret = btrfs_dev_replace_finishing(fs_info, ret);
>> -	WARN_ON(ret);
>> +	WARN_ON(ret && ret != -ECANCELED);
> 
> This one too, thanks.


  btrfs_dev_scrub() can return quite a lot of errno, which is passed
  here through the btrfs_dev_replace_finishing(), so it won't be
  possible to code them all.

  (we use -ECANCELED only in replace and balance).

Thanks, Anand