Christian Brauner <brauner@xxxxxxxxxx> writes:
> On Wed, Feb 21, 2024 at 06:20:49PM +0000, Luis Henriques wrote:
>> Hi!
>>
>> The fstest generic/696 (and 697) fail on ext4 when the filesystem is
>> created with quota support (-O quota). It's really easy to reproduce, and
>> it fails when doing the idmapped tests (setgid_create_umask_idmapped() and
>> setgid_create_umask_idmapped_in_userns()).
>>
>> The failure happens when the test does an openat() with O_TMPFILE:
>>
>> ext4_tmpfile()
>> __ext4_new_inode()
>> dquot_initialize()
>> dqget()
>>
>> and at this point the error occurs:
>>
>> if (!qid_has_mapping(sb->s_user_ns, qid))
>> return ERR_PTR(-EINVAL);
>>
>> qid is '-1', which is invalid, but I'm failing to understand if it should
>> really be invalid or if dqget() should handle this invalid qid some other
>> way. Earlier, __ext4_new_inode() called inode_init_owner(), which indeed
>> sets inode->i_uid with '-1'.
>
> I think that's a misanalysis? The dquot_initialize happens to be before
> the inode creation for that tmpfile. Anyway, see below.
>
>>
>> I've been trying to figure it out, but it's very tricky to follow all the
>> details, so I decided to ask here and see if anyone has any idea. Is this
>> a known issue? Maybe the issue is with the test itself, and not with
>> ext4, quota or idmapped code.
>
> So good new is that it's neither an ext4, quota, or idmapped bug. It's
> just the test being broken because openat_tmpfile_supported() is called
> after we created an idmapped mount on the idmapped mount which means
> that the callers fs{g,u}id might not be mapped. That means
> make_kquid_*id() will return INVALID_*ID which will later fail that
> check whether the qid is mapped in dqget().
>
> I sent a patch to xfstests with you can ext4 Cced. I've tested it here
> and it's fixed. Feel free to test as well.
Wow! Awesome, thanks a lot for looking into this, Christian. I'll test
that patch, but from your description it looks like it should be fix.
Cheers,
--
Luís
