> dm-qcow2 is a request-based target: REQ_NOWAIT handling is done by blk-mq > (tag allocation) before a request reaches us, and clone_and_map_rq() > never blocks. Still, the target does not declare DM_TARGET_NOWAIT, so > dm_table_set_restrictions() clears BLK_FEAT_NOWAIT on the mapped device > and the block device file gets no FMODE_NOWAIT. > > As a result io_uring cannot issue I/O in nowait mode and punts every > request to an io-wq worker thread. Declare DM_TARGET_NOWAIT, so io_uring > submits inline and saves a thread handoff per I/O. > > https://virtuozzo.atlassian.net/browse/VSTOR-95494 > Feature: dm-qcow2: block device over QCOW2 files driver > Signed-off-by: Andrey Zhadchenko <[email protected]>
This patch is unchanged since "[Devel] [PATCH hci-8.1 6/7] drivers/md/dm-qcow2: declare DM_TARGET_NOWAIT", which Sashiko reviewed and found no issues in. That review applies to this posting unaltered, so the patch has not been reviewed again. -- Sashiko AI review ยท https://sashiko.vzint.dev/#/patchset/[email protected]?part=6 _______________________________________________ Devel mailing list [email protected] https://lists.openvz.org/mailman/listinfo/devel
