Re: [PATCH 13/18] btrfs: handle the ro->rw transition for mounting different subovls

[Josef Bacik <josef@toxicpanda.com>]

On Wed, Nov 08, 2023 at 09:41:33AM +0100, Christian Brauner wrote:
> On Mon, Nov 06, 2023 at 05:08:21PM -0500, Josef Bacik wrote:
> > This is an oddity that we've carried around since 0723a0473fb4 ("btrfs:
> > allow mounting btrfs subvolumes with different ro/rw options") where
> > we'll under the covers flip the file system to RW if you're mixing and
> > matching ro/rw options with different subvol mounts.  The first mount is
> > what the super gets setup as, so we'd handle this by remount the super
> > as rw under the covers to facilitate this behavior.
> > 
> > With the new mount API we can't really allow this, because user space
> > has the ability to specify the super block settings, and the mount
> > settings.  So if the user explicitly set the super block as read only,
> > and then tried to mount a rw mount with the super block we'll reject
> > this.  However the old API was less descriptive and thus we allowed this
> > kind of behavior.
> > 
> > This patch preserves this behavior for the old api calls.  This is
> > inspired by Christians work, and includes one of his comments, and thus
> > is included in the link below.
> > 
> > Link: https://lore.kernel.org/all/20230626-fs-btrfs-mount-api-v1-2-045e9735a00b@kernel.org/
> > Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> > ---
> 
> Looks good to me,
> Reviewed-by: Christian Brauner <brauner@kernel.org>
> 
> Just note that all capitalization was removed from the comment
> preceeding btrfs_reconfigure_for_mount() by accident. You might want to
> fix that up/recopy that comment.
> 

Oops, I accidentally did something with vim that killed capitalization in the
whole file, I thought I undid all of it properly but apparently I didn't.  I'll
fix it up, thanks,

Josef