Re: [PATCH] btrfs: always scan a single device when mounted

[David Sterba <dsterba@suse.cz>]

On Tue, Feb 06, 2024 at 04:21:15PM -0800, Boris Burkov wrote:
> On Mon, Feb 05, 2024 at 06:43:39PM +0100, David Sterba wrote:
> > --- a/fs/btrfs/volumes.c
> > +++ b/fs/btrfs/volumes.c
> > @@ -738,6 +738,7 @@ static noinline struct btrfs_device *device_list_add(const char *path,
> >  	bool same_fsid_diff_dev = false;
> >  	bool has_metadata_uuid = (btrfs_super_incompat_flags(disk_super) &
> >  		BTRFS_FEATURE_INCOMPAT_METADATA_UUID);
> > +	bool can_create_new = *new_device_added;
> 
> It took me quite a while to figure out all the intended logic with the
> now in/out parameter. I think it's probably too cute? Why not just add
> another parameter "can_create_new_device"? I think it feels kind of
> weird on the caller side too, to set "new_device_added" to true, but
> then still rely on it to actually get set to true.
> 
> Once I got past this, the logic made sense, so definitely don't block
> yourself on this nit.

I had the separate parameter for the debugging version and removed for
the final but I agree that it makes things less clear. Also there's
something wrong with the device matching so the meaning of the parameter
will be unchanged.