On 2022/11/29 6:28, Theodore Ts'o wrote:
> On Tue, Nov 08, 2022 at 02:06:29PM +0000, Luís Henriques wrote:
>>> What makes you believe that? Look at how s_group_info is initialized
>>> in ext4_mb_alloc_groupinfo() in fs/ext4/mballoc.c. It's pretty
>>> careful to make sure this is not the case.
>> Right. I may be missing something, but I don't think we get that far.
>> __ext4_fill_super() will first call ext4_setup_system_zone() (which is
>> where this bug occurs) and only after that ext4_mb_init() will be invoked
>> (which is where ext4_mb_alloc_groupinfo() will eventually be called).
> I finally got around to taking a closer look at this, and I have a
> much better understandign of what is going on. For more details, and
> a suggested fix, please see:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=216541#c1
>
> - Ted
>
>
Hi Theodore,
In my opinion, the s_journal_inum should not be modified when the file
system is
mounted, especially after we have successfully loaded and replayed the
journal with
the current s_journal_inum. Even if the s_journal_inumon the disk is
modified, we should
use the current one. This is how journal_devnum is handled in
ext4_load_journal():
if (!really_read_only && journal_devnum &&
journal_devnum != le32_to_cpu(es->s_journal_dev)) {
es->s_journal_dev = cpu_to_le32(journal_devnum);
/* Make sure we flush the recovery flag to disk. */
ext4_commit_super(sb);
}
We can avoid this problem by adding a similar check for journal_inum in
ext4_load_journal().
--
With Best Regards,
Baokun Li