From: no-reply@sashiko.virtuozzo.com
To: Konstantin Khorenko <khorenko@virtuozzo.com>,
Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 v5 4/6] block/blk-cbt: walk cbt_list under SRCU
Date: Tue, 27 Oct 2026 14:29:57 +0000 [thread overview]
Message-ID: <010701a17dc493c1-9de6fed0-6991-492f-a31e-6bf42ada4d11-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261027-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v5-4-88dccc74b48b@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.
>
> https://virtuozzo.atlassian.net/browse/VSTOR-149268
> Feature: cbt: changed block tracking (for backup)
> Signed-off-by: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>
Sashiko has reviewed this patch and found no issues. It looks great!
--
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261027-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v5-0-88dccc74b48b@virtuozzo.com?part=4
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next prev parent reply other threads:[~2026-10-27 14:31 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-27 14:23 [Devel] [PATCH hci-8.1 v5 0/6] block/blk-cbt: don't lose writes held across a dm suspend Pavel Tikhomirov
2026-10-27 14:23 ` [Devel] [PATCH hci-8.1 v5 1/6] block/blk-cbt: shift the block size as unsigned Pavel Tikhomirov
2026-10-27 14:27 ` no-reply
2026-10-27 14:23 ` [Devel] [PATCH hci-8.1 v5 2/6] block/blk-throttle: account a throttled write in CBT Pavel Tikhomirov
2026-10-27 14:27 ` no-reply
2026-10-27 14:23 ` [Devel] [PATCH hci-8.1 v5 3/6] block/blk-cbt: don't overwrite a map page with CBT_PAGE_MISSED Pavel Tikhomirov
2026-10-27 14:30 ` no-reply
2026-10-27 14:23 ` [Devel] [PATCH hci-8.1 v5 4/6] block/blk-cbt: walk cbt_list under SRCU Pavel Tikhomirov
2026-10-27 14:29 ` no-reply [this message]
2026-10-27 14:23 ` [Devel] [PATCH hci-8.1 v5 5/6] block/blk-cbt: don't sleep in CBT for a REQ_NOWAIT write Pavel Tikhomirov
2026-10-27 14:33 ` no-reply
2026-10-27 14:23 ` [Devel] [PATCH hci-8.1 v5 6/6] block/blk-cbt: account a write request also when dm starts it Pavel Tikhomirov
2026-10-27 14:33 ` no-reply
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