Re: linux-next: build failure after merge of the btrfs tree

[Qu Wenruo]

在 2024/10/24 11:17, David Sterba 写道:
> On Thu, Oct 24, 2024 at 08:58:58AM +1030, Qu Wenruo wrote:
> > 在 2024/10/24 08:27, Stephen Rothwell 写道:
> > > Hi all,
> > >
> > > After merging the btrfs tree, today's linux-next build (x86_64
> > > allmodconfig) failed like this:
> > >
> > > fs/btrfs/super.c: In function 'btrfs_reconfigure_for_mount':
> > > fs/btrfs/super.c:2011:56: error: suggest parentheses around '&&' within '||' [-Werror=parentheses]
> > >    2011 |         if (!fc->oldapi || !(fc->sb_flags & SB_RDONLY) && (mnt->mnt_sb->s_flags & SB_RDONLY))
> > >         |                            ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > > cc1: all warnings being treated as errors
> > >
> > > Caused by commit
> > >
> > >     4642e430c55b ("btrfs: fix mount failure due to remount races")
> >
> > My bad, in fact a new patch is going to remove the oldapi check
> > completely as newer mount using new API will break the per-subvolume
> > RO/RW again.
> >
> > Thus a new patch is needed to remove the oldapi check first
> > (https://lore.kernel.org/linux-btrfs/e1a70aa6dd0fc9ba6c7050a5befb3bd5b75a1377.1729664802.git.wqu@xxxxxxxx/),
> > then the newer v2 patch
> > (https://lore.kernel.org/linux-btrfs/08e45ca0-5ed9-4684-940f-1e956a936628@xxxxxxx/T/#t)
> > will be completely fine.
>
> I probably missed the v2 and picked the patch with warning that I did
> not consider too serious but it seems linux-next builds with -Werrror.
> Meanwhile I've updated the for-next snapshot branch and dropped the
> patch.

I'd prefer to pick the v2 and its dependency ("btrfs: fix per-subvolume 
RO/RW flags with new mount API") for early testing.

As I'm pretty sure the rolling distros are already rolling out new mount 
using the fsconfig API, and breaking our per-subvolume RO/RW mount.

The promise that new mount API will solve the per-subvolume RO/RW 
without reconfiguration is mostly a lie.
The reality is, RO mount is still passed with both 
fsconfig(FSCONFIG_SET_FLAG, "ro") and  mount_setattr(MOUNT_ATTR_RDONLY), 
doing exactly the same thing as the old mount.

Thanks,
Qu