Re: [Devel] [PATCH hci-8.1 v10 03/10] dm-qcow2: extend the file for a new refblock in allocate_cluster()

[no-reply@sashiko.virtuozzo.com]

> place_r2() links a new refblock into R1, but moves neither file_size
> nor file_preallocated_area_start. The refblock stays at or above the
> watermark if truncate_prealloc_safe() in allocate_cluster() fails
> after place_r2(), or if a parallel mark_cluster_unused() lowers
> free_cluster_search_pos before the second pass of
> find_unused_cluster(). Truncation of preallocations on suspend then
> cuts the file under the refblock: R1 on disk points past EOF, and
> the next session gets -EIO on allocations in the range it covers.
> 
> Make find_unused_cluster() report a position not covered by R2
> instead of placing the refblock there itself. allocate_cluster()
> prepares that cluster the same way as a data cluster, with the punch,
> extend and watermark update moved into prepare_unused_cluster(), and
> calls place_r2() before searching again.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-148171
> Feature: dm-qcow2: block device over QCOW2 files driver
> Fixes: 222b6f1291c1c ("dm-qcow2: Introduce driver to create block devices over QCOW2 files")
> 
> Signed-off-by: Alexander Ivanov <alexander.ivanov@virtuozzo.com>

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

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261109115856.1362416-1-alexander.ivanov@virtuozzo.com?part=3


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