[Devel] [PATCH hci-8.1 v9 05/10] dm-qcow2: flush lower metadata before clearing its dirty bit on merge failure

[Alexander Ivanov]

Rewrote.

On 11/3/26 18:50, Konstantin Khorenko wrote:
> I won't apply this version, please send v10 with the changes below.
>
> On 10/28/26 16:06, Alexander Ivanov wrote:
>> leaves the lower image marked clean on disk with L2 tables and refblocks
>> that lag behind the merged data.
>>
>> A failed md writeback of the lower image is also missed:
>> md_writeback_error is set only by qcow2_flush_deferred_activity(), so
>> the next resume is not refused.
> - Drop the second paragraph.
> - Say refblocks only, not "L2 tables and refblocks".
> - Shorten the subject, it is 77 columns.
>
> The next postsuspend flushes the lower image as well:
> qcow2_flush_deferred_activity_all() walks tgt->top and every ->lower
> and sets md_writeback_error on a failed write. So that resume is
> refused already. What the patch adds is the order: the flush now comes
> before the header write that clears the dirty bit.
>
> Merge writes wait for their L2 writeback before they complete, so L2
> does not lag. Only the refblocks are in the delayed writeback.
>