[Devel] [PATCH hci-8.1 1/4] dm-ploop: fix pio submission racing with the suspend and resume of a cmd

[no-reply at sashiko.virtuozzo.com]

> From: Denis V. Lunev <den at openvz.org>
> 
> ploop_submit_embedded_pio() tests stop_submitting_pios and then takes a
> ref on the current inflight_bios_ref index without deferred_lock. A cmd
> sets the flag and flips the index under that lock and then waits only
> for the refs of the old index, so:
> 
> - a pio that passed the check before the flag was set takes its ref on
>   the new index or on the already killed old one. The cmd does not
>   wait for it, and it runs while a merge, resize or delta index update
>   rewrites the BAT levels and deltas[];
> 
> - a pio that saw the flag set is added to llsuspended_pios after resume
>   has cleared the flag and drained the list. Nothing drains it until
>   the next cmd, the request never completes and a dm suspend of the
> [ ... ]
> Fixes: b90109c12b1c ("dm-ploop: convert the rest of the lists to use llist variant")
> Reported-by: Konstantin Khorenko <khorenko at virtuozzo.com>
> https://virtuozzo.atlassian.net/browse/VSTOR-152985
> Feature: dm-ploop: ploop target driver
> Signed-off-by: Denis V. Lunev <den at openvz.org>

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

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Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261103083642.130885-1-den@openvz.org?part=1