Re: [PATCH 2/3] btrfs: Introduce the single-dev feature

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

On 30/08/2023 04:28, Guilherme G. Piccoli wrote:
> On 03/08/2023 12:43, Guilherme G. Piccoli wrote:
>> [...]
>>   fs/btrfs/disk-io.c         | 19 +++++++-
>>   fs/btrfs/fs.h              |  3 +-
>>   fs/btrfs/ioctl.c           | 18 +++++++
>>   fs/btrfs/super.c           |  8 ++--
>>   fs/btrfs/volumes.c         | 97 ++++++++++++++++++++++++++++++--------
>>   fs/btrfs/volumes.h         |  3 +-
>>   include/uapi/linux/btrfs.h |  7 +++
>>   7 files changed, 127 insertions(+), 28 deletions(-)
>>
> 
> Hi folks, while working the xfstests for this case, I've noticed the
> single-dev feature is not exposed in sysfs! Should we make it available
> there?
>  > A quick change here made me see it there, but it sticks to value 0 ...
> maybe I'm not really aware of how the sysfs/features directory should
> work, hence I appreciate if you could enlighten me if makes sense to
> have this feature there (and if it's OK showing zero or should flip in
> case a device makes use of the feature, maybe?).
> 

Yeah, we need sysfs entries for the new feature and test cases that 
generally rely on it to determine whether to skip or run the test case.

The paths would be:
- /sys/fs/btrfs/features/..
- /sys/fs/btrfs/<uuid>/features/..

These paths emit only output 0. The presence of the sysfs file indicates 
that the feature is supported.

Thanks,
Anand


> Thanks in advance,
> 
> 
> Guilherme