On Sun, Jun 21, 2020 at 9:33 PM Stefan Priebe - Profihost AG
<s.priebe@xxxxxxxxxxxx> wrote:
>
> Hi David,
>
> i did a git bisect and the breaking commit is:
>
> commit c30da2e981a703c6b1d49911511f7ade8dac20be
> Author: David Howells <dhowells@xxxxxxxxxx>
> Date: Mon Mar 25 16:38:31 2019 +0000
>
> fuse: convert to use the new mount API
>
> Convert the fuse filesystem to the new internal mount API as the old
> one will be obsoleted and removed. This allows greater flexibility in
> communication of mount parameters between userspace, the VFS and the
> filesystem.
>
> See Documentation/filesystems/mount_api.txt for more information.
>
> Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
>
> most probably due to the following diffences:
>
>
> old default:
> default:
> - return 0;
>
>
> new default:
> + default:
> + return -EINVAL;
>
>
> it seems the old API silently did ignore unknown parameters while the
> new one fails with EINVAL.
v4.19 has this:
static int parse_fuse_opt(char *opt, struct fuse_mount_data *d, int is_bdev,
struct user_namespace *user_ns)
{
[...]
while ((p = strsep(&opt, ",")) != NULL) {
[...]
token = match_token(p, tokens, args);
switch (token) {
[...]
default:
return 0;
and
static int fuse_fill_super(struct super_block *sb, void *data, int silent)
{
[...]
err = -EINVAL;
if (sb->s_flags & SB_MANDLOCK)
goto err;
sb->s_flags &= ~(SB_NOSEC | SB_I_VERSION);
if (!parse_fuse_opt(data, &d, is_bdev, sb->s_user_ns))
goto err;
[...]
err:
return err;
}
That looks like it returns -EINVAL for unknown options. Can you
perform a "strace" on the old and the new kernel to see what the
difference is?
BTW, the hard rule is: userspace regressions caused by kernel changes
must be fixed. It's just not clear where exactly this is coming from.
Thanks,
Miklos
