[Devel] [PATCH hci-8.1 v7 6/8] block/blk-cbt: walk cbt_list under SRCU

[no-reply at sashiko.virtuozzo.com]

> blk_cbt_bio_queue() walks q->cbt_list under rcu_read_lock(), but a cbt
> may need a bitmap page there: cbt_page_alloc() then drops the RCU lock
> around the sleeping allocation, pinning only the current cbt. A CBT stop
> or resize meanwhile can unlink it and free the next one, which the walk
> then reaches through the stale ->next.
> 
> Walk cbt_list and release cbts under SRCU instead, whose readers may
> sleep, so the allocation no longer drops the lock. Take it after the
> early exits of blk_cbt_bio_queue(), which need no lock.
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-149268
> Feature: cbt: changed block tracking (for backup)
> Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>

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

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261028-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v7-0-5c48672191c2@virtuozzo.com?part=6