Re: [PATCH 1/2] btrfs: Raise nobarrier log level to warn

[Qu Wenruo <quwenruo.btrfs@gmx.com>]

在 2025/5/26 03:15, Kyoji Ogasawara 写道:
> Sorry for sending piecemeal updates.
> 
> I've realized that if the log goes into btrfs_emit_options(), it'll
> only show up during remount operations.
> 
> So, I was thinking of adding the following code to open_ctree(), right
> after the btrfs_check_options() call.
> 
>         if (btrfs_test_opt(fs_info, NOBARRIER))
>                 btrfs_info(fs_info, "turning off barriers, use with care");
> 
> What do you think of this approach?
> 
> We could also set the log level to warning if that's preferred.

It turns out to be a more deeply involved bug.

The root cause is, we no longer use btrfs_parse_options() to output the 
mount option changes.

Before the fsconfig change, we have btrfs_parse_options() function, 
which will output an info line for each triggered option.
That function is utilized by both mount (open_ctree()) and remount 
(btrfs_remount())

But with the fsconfig migration, we use parse_param() helper, which now 
only handles the feature setting, no more messaging.
And btrfs_emit_options() to emit the message line.

The btrfs_emit_options() can handle empty @old context, thus it is 
designed to handle both mount and remount.

Unfortunately at mount time we do not call btrfs_emit_options(), this 
means we lost all the previous mount messages.

I'm not sure if this is intended or not, the fact we didn't notice the 
change until now means, most of the info lines are not that useful and 
no one is really noticing them.

So @josef, is it intended to skip all the mount option related info 
messages? Or it's just a bug?

Thanks,
Qu