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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 v7 8/8] block/blk-cbt: account a write request also when dm starts it
Date: Wed, 28 Oct 2026 10:25:14 +0000	[thread overview]
Message-ID: <010701a1820ae427-21518414-e96f-4127-8c5b-4310fe9a94c7-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261028-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v7-8-5c48672191c2@virtuozzo.com>

> CBT accounts a write at bio submission. dm suspend of request based dm
> waits only for started requests, so a request submitted before the
> suspend but dispatched after resume is accounted before a backup point
> taken under the suspend (BLKCBTSTART, CBT_SNAP_CREATE) while its data
> lands after it. push_backup then saves the old data, and no incremental
> backup copies the new one.
> 
> Account a write again when dm starts it. This runs under the dispatch
> rcu_read_lock(), so it can't allocate: it sets the bits directly in the
> bitmap pages, and the allocation of missing pages is now queued to the
> kblockd workqueue already at submission. If a page is still missing when
> dm starts the request (the work did not run yet, or the write was
> submitted before BLKCBTSTART), dm returns BLK_STS_RESOURCE, so that
> blk-mq dispatches the request again later.
> 
> 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/20261028-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v7-0-5c48672191c2@virtuozzo.com?part=8


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  reply	other threads:[~2026-10-28 10:26 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-28 10:11 [Devel] [PATCH hci-8.1 v7 0/8] block/blk-cbt: don't lose writes held across a dm suspend Pavel Tikhomirov
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 1/8] block/blk-cbt: don't read a released cbt in blk_cbt_update_size() Pavel Tikhomirov
2026-10-28 10:16   ` no-reply
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 2/8] block/blk-cbt: shift the block size as unsigned Pavel Tikhomirov
2026-10-28 10:16   ` no-reply
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 3/8] block/blk-throttle: account a throttled write in CBT Pavel Tikhomirov
2026-10-28 10:18   ` no-reply
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 4/8] block/blk-cbt: read a map slot once, publish a map page with release Pavel Tikhomirov
2026-10-28 10:18   ` no-reply
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 5/8] block/blk-cbt: don't overwrite a map page with CBT_PAGE_MISSED Pavel Tikhomirov
2026-10-28 10:21   ` no-reply
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 6/8] block/blk-cbt: walk cbt_list under SRCU Pavel Tikhomirov
2026-10-28 10:20   ` no-reply
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 7/8] block/blk-cbt: don't sleep in CBT for a REQ_NOWAIT write Pavel Tikhomirov
2026-10-28 10:23   ` no-reply
2026-10-28 10:11 ` [Devel] [PATCH hci-8.1 v7 8/8] block/blk-cbt: account a write request also when dm starts it Pavel Tikhomirov
2026-10-28 10:25   ` no-reply [this message]
2026-11-03 18:02   ` Konstantin Khorenko
2026-11-04 12:10   ` [Devel] [PATCH hci-8.1 v8 " Pavel Tikhomirov
2026-11-03 18:02 ` [Devel] [PATCH hci-8.1 v7 0/8] block/blk-cbt: don't lose writes held across a dm suspend Konstantin Khorenko

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