Re: [PATCH] btrfs: no need to check return value of debugfs_create functions

[David Sterba <dsterba@suse.cz>]

On Fri, Jan 04, 2019 at 02:25:20PM +0100, Greg Kroah-Hartman wrote:
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.
> 
> Cc: Chris Mason <clm@fb.com>
> Cc: Josef Bacik <josef@toxicpanda.com>
> Cc: David Sterba <dsterba@suse.com>
> Cc: linux-btrfs@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  fs/btrfs/sysfs.c | 10 ++--------
>  1 file changed, 2 insertions(+), 8 deletions(-)
> 
> Meta-comment, why is there a btrfs debugfs directory at all?  All you
> have here is a single "test" file that doesn't do anything except expose
> a variable that never changes.  What is this directory and single file
> for?  Can I just delete the whole thing?

As explained in the commit that introduces the function
(1bae30982bc86ab66d61ccb):

  Help during debugging to export various interesting infromation and
  tunables without the need of extra mount options or ioctls.

  Usage:
  * declare your variable in sysfs.h, and include where you need it
  * define the variable in sysfs.c and make it visible via
    debugfs_create_TYPE

  Depends on CONFIG_DEBUG_FS.

It's there for developers, so don't delete it. Which also means the
error code should be handled and not ignored.

I can enhance the comment so it's explained in-place and not too
tempting to remove it. This is not the first time somebody wants to
remove it
(https://lore.kernel.org/linux-btrfs/d6715b5b-0aa3-3032-43c6-eccd907a60b8@redhat.com/),