On 10/28/24 7:22 AM, Christian Brauner wrote:
> On Sun, Oct 27, 2024 at 02:07:41AM +0800, Zorro Lang wrote:
>> Hi,
>>
>> Recently, I hit lots of fstests cases fail on overlayfs (xfs underlying, no
>> specific mount options), e.g.
>>
>> FSTYP -- overlay
>> PLATFORM -- Linux/s390x s390x-xxxx 6.12.0-rc4+ #1 SMP Fri Oct 25 14:29:18 EDT 2024
>> MKFS_OPTIONS -- -m crc=1,finobt=1,rmapbt=0,reflink=1,inobtcount=1,bigtime=1 /mnt/fstests/SCRATCH_DIR
>> MOUNT_OPTIONS -- -o context=system_u:object_r:root_t:s0 /mnt/fstests/SCRATCH_DIR /mnt/fstests/SCRATCH_DIR/ovl-mnt
>>
>> generic/294 [failed, exit status 1]- output mismatch (see /var/lib/xfstests/results//generic/294.out.bad)
>> --- tests/generic/294.out 2024-10-25 14:38:32.098692473 -0400
>> +++ /var/lib/xfstests/results//generic/294.out.bad 2024-10-25 15:02:34.698605062 -0400
>> @@ -1,5 +1,5 @@
>> QA output created by 294
>> -mknod: SCRATCH_MNT/294.test/testnode: File exists
>> -mkdir: cannot create directory 'SCRATCH_MNT/294.test/testdir': File exists
>> -touch: cannot touch 'SCRATCH_MNT/294.test/testtarget': Read-only file system
>> -ln: creating symbolic link 'SCRATCH_MNT/294.test/testlink': File exists
>> +mount: /mnt/fstests/SCRATCH_DIR/ovl-mnt: fsconfig system call failed: overlay: No changes allowed in reconfigure.
>> + dmesg(1) may have more information after failed mount system call.
>
> In the new mount api overlayfs has been changed to reject invalid mount
> option on remount whereas in the old mount api we just igorned them.
> If this a big problem then we need to change overlayfs to continue
> ignoring garbage mount options passed to it during remount.
>
It fails on /any/ overlayfs-specific options during reconfigure, invalid or
not, right?
if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
/*
* On remount overlayfs has always ignored all mount
* options no matter if malformed or not so for
* backwards compatibility we do the same here.
*/
if (fc->oldapi)
return 0;
/*
* Give us the freedom to allow changing mount options
* with the new mount api in the future. So instead of
* silently ignoring everything we report a proper
* error. This is only visible for users of the new
* mount api.
*/
return invalfc(fc, "No changes allowed in reconfigure");
}
opt = fs_parse(fc, ovl_parameter_spec, param, &result);
if (opt < 0)
return opt;
And because today mount(8) will re-specify everything it finds in
/proc/mounts during remount, presumably that's why all these tests are
failing - even a simple remount,ro will fail:
# mount -t overlay overlay -o lowerdir=lower,upperdir=upper,workdir=work merged
# strace -e fsconfig mount -o remount,ro merged
fsconfig(4, FSCONFIG_SET_FLAG, "seclabel", NULL, 0) = 0
fsconfig(4, FSCONFIG_SET_STRING, "lowerdir", "lower", 0) = -1 EINVAL (Invalid argument)
...
Surely mount -o remount,ro should continue to work for overlayfs when the new
API is used.
Maybe there's a third way: accept remount options as long as they match
current options, but fail if they try to modify anything? Not sure how tricky
that would be.
(side note: it's a bit worrisome that there is probably no consistency at
all across filesystems, here.)
-Eric
