From: no-reply@sashiko.virtuozzo.com
To: Pavel Tikhomirov <ptikhomirov@virtuozzo.com>,
Konstantin Khorenko <khorenko@virtuozzo.com>
Cc: devel@openvz.org
Subject: Re: [Devel] [PATCH hci-8.1 v6 6/7] block/blk-cbt: don't sleep in CBT for a REQ_NOWAIT write
Date: Tue, 27 Oct 2026 16:57:56 +0000 [thread overview]
Message-ID: <010701a17e4c1011-e4345a66-cfda-408c-9884-4f94ef121a12-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261027-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v6-6-f9870cf5c7eb@virtuozzo.com>
> Accounting a write in CBT may allocate a bitmap page with GFP_NOIO,
> either for the write itself or for the extent it evicts from the per-cpu
> cache, so a REQ_NOWAIT bio can sleep in submit_bio_noacct().
>
> For a REQ_NOWAIT write, skip the cache and set the bits directly, which
> doesn't allocate when all the pages are there. If one is missing, fail
> the bio with BLK_STS_AGAIN, for the submitter to retry it in a context
> that may block. The throttle dispatch work may sleep, so it doesn't use
> this.
>
> 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-v6-0-f9870cf5c7eb@virtuozzo.com?part=6
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next prev parent reply other threads:[~2026-10-27 16:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-27 16:48 [Devel] [PATCH hci-8.1 v6 0/7] block/blk-cbt: don't lose writes held across a dm suspend Pavel Tikhomirov
2026-10-27 16:48 ` [Devel] [PATCH hci-8.1 v6 1/7] block/blk-cbt: shift the block size as unsigned Pavel Tikhomirov
2026-10-27 16:53 ` no-reply
2026-10-27 16:48 ` [Devel] [PATCH hci-8.1 v6 2/7] block/blk-throttle: account a throttled write in CBT Pavel Tikhomirov
2026-10-27 16:53 ` no-reply
2026-10-27 16:48 ` [Devel] [PATCH hci-8.1 v6 3/7] block/blk-cbt: read a map slot once, publish a map page with release Pavel Tikhomirov
2026-10-27 16:55 ` no-reply
2026-10-27 16:48 ` [Devel] [PATCH hci-8.1 v6 4/7] block/blk-cbt: don't overwrite a map page with CBT_PAGE_MISSED Pavel Tikhomirov
2026-10-27 16:54 ` no-reply
2026-10-27 16:48 ` [Devel] [PATCH hci-8.1 v6 5/7] block/blk-cbt: walk cbt_list under SRCU Pavel Tikhomirov
2026-10-27 16:58 ` no-reply
2026-10-27 16:48 ` [Devel] [PATCH hci-8.1 v6 6/7] block/blk-cbt: don't sleep in CBT for a REQ_NOWAIT write Pavel Tikhomirov
2026-10-27 16:57 ` no-reply [this message]
2026-10-27 16:48 ` [Devel] [PATCH hci-8.1 v6 7/7] block/blk-cbt: account a write request also when dm starts it Pavel Tikhomirov
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