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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 v7 7/8] block/blk-cbt: don't sleep in CBT for a REQ_NOWAIT write
Date: Wed, 28 Oct 2026 10:23:28 +0000	[thread overview]
Message-ID: <010701a18209473c-dc30e156-d8b3-4291-98bf-4ab089c48fc4-000000@eu-central-1.amazonses.com> (raw)
In-Reply-To: <20261028-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v7-7-5c48672191c2@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/20261028-ptikhomirov-vstor-149268-cbt-account-at-rq-start-v7-0-5c48672191c2@virtuozzo.com?part=7


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  reply	other threads:[~2026-10-28 10:24 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 [this message]
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
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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