Am 25.06.20 um 21:54 schrieb Miklos Szeredi:
> 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.
Does a userspace strace really help? I did a git bisect between kernel
v5.3 (working) und v5.4 (not working) and it shows
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>
as the regression commit.
Stefan
>
> Thanks,
> Miklos
>
