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 refblocks that lag behind the merged data.
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 Fixes: 222b6f1291c1c ("dm-qcow2: Introduce driver to create block devices over QCOW2 files") Signed-off-by: Alexander Ivanov <[email protected]> --- drivers/md/dm-qcow2-cmd.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/md/dm-qcow2-cmd.c b/drivers/md/dm-qcow2-cmd.c index 45c517ce0ef8..3bccce090f01 100644 --- a/drivers/md/dm-qcow2-cmd.c +++ b/drivers/md/dm-qcow2-cmd.c @@ -330,6 +330,7 @@ void qcow2_merge_backward_work(struct work_struct *work) ret = qcow2_merge_common(tgt, qcow2); if (ret) { set_backward_merge_in_process(tgt, qcow2, false); + qcow2_flush_deferred_activity(tgt, lower); ret2 = qcow2_set_image_file_features(lower, false); if (ret2 < 0) QC_ERR(tgt->ti, "Can't unuse lower (%d)", ret2); -- 2.53.0 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
