On Tue, Feb 6, 2024 at 11:49 PM Dave Chinner <david@xxxxxxxxxxxxx> wrote:
>
> On Tue, Feb 06, 2024 at 03:18:50PM -0500, Kent Overstreet wrote:
> > We don't want to be settingc sb->s_uuid directly anymore, as there's a
> > length field that also has to be set, and this conversion was not
> > completely trivial.
> >
> > Signed-off-by: Kent Overstreet <kent.overstreet@xxxxxxxxx>
> > Cc: Miklos Szeredi <miklos@xxxxxxxxxx>
> > Cc: Amir Goldstein <amir73il@xxxxxxxxx>
> > Cc: linux-unionfs@xxxxxxxxxxxxxxx
> > ---
> > fs/overlayfs/util.c | 14 +++++++++-----
> > 1 file changed, 9 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/overlayfs/util.c b/fs/overlayfs/util.c
> > index 0217094c23ea..f1f0ee9a9dff 100644
> > --- a/fs/overlayfs/util.c
> > +++ b/fs/overlayfs/util.c
> > @@ -760,13 +760,14 @@ bool ovl_init_uuid_xattr(struct super_block *sb, struct ovl_fs *ofs,
> > const struct path *upperpath)
> > {
> > bool set = false;
> > + uuid_t uuid;
> > int res;
> >
> > /* Try to load existing persistent uuid */
> > - res = ovl_path_getxattr(ofs, upperpath, OVL_XATTR_UUID, sb->s_uuid.b,
> > + res = ovl_path_getxattr(ofs, upperpath, OVL_XATTR_UUID, uuid.b,
> > UUID_SIZE);
> > if (res == UUID_SIZE)
> > - return true;
> > + goto success;
> >
> > if (res != -ENODATA)
> > goto fail;
> > @@ -794,14 +795,14 @@ bool ovl_init_uuid_xattr(struct super_block *sb, struct ovl_fs *ofs,
> > }
> >
> > /* Generate overlay instance uuid */
> > - uuid_gen(&sb->s_uuid);
> > + uuid_gen(&uuid);
> >
> > /* Try to store persistent uuid */
> > set = true;
> > - res = ovl_setxattr(ofs, upperpath->dentry, OVL_XATTR_UUID, sb->s_uuid.b,
> > + res = ovl_setxattr(ofs, upperpath->dentry, OVL_XATTR_UUID, uuid.b,
> > UUID_SIZE);
> > if (res == 0)
> > - return true;
> > + goto success;
>
> This is a bit weird. Normally the success case is in line, and we
> jump out of line for the fail case. I think this is more better:
>
> if (res)
> goto fail;
> success:
> super_set_uuid(sb, uuid.b, sizeof(uuid));
> return true;
> >
> > fail:
> > memset(sb->s_uuid.b, 0, UUID_SIZE);
>
> And then the fail case follows naturally.
>
I agree. Please use the label name
set_uuid:
Also the memset() in fail: case is not needed anymore, because
with your change we do not dirty sb->s_uuid in this function.
Thanks,
Amir.
