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

[no-reply at sashiko.virtuozzo.com]

> When qcow2_merge_common() fails, qcow2_merge_backward_work() clears the
> dirty bit of the lower image right away. qcow2_service_iter() waits only
> for the service qios, so delayed md writeback of the lower image may
> still be pending. With kernel_sets_dirty_bit, a crash at that point
> 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.
> 
> Flush the deferred activity of the lower image before writing its
> header, as qcow2_merge_backward_complete() does.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-148171
> Feature: dm-qcow2: block device over QCOW2 files driver
> Signed-off-by: Alexander Ivanov <alexander.ivanov at virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261028150645.3222391-1-alexander.ivanov@virtuozzo.com?part=5