On Tue, Feb 06, 2024 at 08:58:49AM +1100, Dave Chinner wrote: > On Mon, Feb 05, 2024 at 03:05:12PM -0500, Kent Overstreet wrote: > > Some weird old filesytems have UUID-like things that we wish to expose > > as UUIDs, but are smaller; add a length field so that the new > > FS_IOC_(GET|SET)UUID ioctls can handle them in generic code. > > > > Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx> > > --- > > fs/super.c | 1 + > > include/linux/fs.h | 1 + > > 2 files changed, 2 insertions(+) > > > > diff --git a/fs/super.c b/fs/super.c > > index d35e85295489..ed688d2a58a7 100644 > > --- a/fs/super.c > > +++ b/fs/super.c > > @@ -375,6 +375,7 @@ static struct super_block *alloc_super(struct file_system_type *type, int flags, > > s->s_time_gran = 1000000000; > > s->s_time_min = TIME64_MIN; > > s->s_time_max = TIME64_MAX; > > + s->s_uuid_len = sizeof(s->s_uuid); > > So if the filesystem doesn't copy a uuid into sb->s_uuid, then we > allow those 16 bytes to be pulled from userspace? > > Shouldn't this only get set when the filesystem copies it's uuid > to the superblock? > > And then in the get uuid ioctl, if s_uuid_len is zero we can return > -ENOENT to indicate the filesystem doesn't have a UUID, rather that > require userspace to determine a filesystem doesn't have a valid > UUID somehow... *nod* this all falls out of your super_set_uuid() suggestion
