From: Nix <nix@esperi.org.uk>
To: Coly Li <colyli@suse.de>
Cc: linux-bcache@vger.kernel.org, linux-block@vger.kernel.org,
Nikhil Kshirsagar <nkshirsagar@gmail.com>,
stable@vger.kernel.org
Subject: Re: [PATCH 4/4] bcache: avoid journal no-space deadlock by reserving 1 journal bucket
Date: Wed, 08 Jun 2022 21:45:55 +0100 [thread overview]
Message-ID: <8735geanp8.fsf@esperi.org.uk> (raw)
In-Reply-To: <20220521170502.20026-4-colyli@suse.de> (Coly Li's message of "Sun, 22 May 2022 01:05:02 +0800")
On 21 May 2022, Coly Li spake thusly:
> When all journal buckets are fully filled by active jset with heavy
> write I/O load, the cache set registration (after a reboot) will load
> all active jsets and inserting them into the btree again (which is
> called journal replay). If a journaled bkey is inserted into a btree
> node and results btree node split, new journal request might be
> triggered. For example, the btree grows one more level after the node
> split, then the root node record in cache device super block will be
> upgrade by bch_journal_meta() from bch_btree_set_root(). But there is no
> space in journal buckets, the journal replay has to wait for new journal
> bucket to be reclaimed after at least one journal bucket replayed. This
> is one example that how the journal no-space deadlock happens.
>
> The solution to avoid the deadlock is to reserve 1 journal bucket in
It seems to me that this could happen more than once in a single journal
replay (multiple nodes might be split, etc). Is one bucket actually
always enough, or is it merely enough nearly all the time?
--
NULL && (void)
next prev parent reply other threads:[~2022-06-08 21:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-21 17:04 [PATCH 1/4] bcache: improve multithreaded bch_btree_check() Coly Li
2022-05-21 17:05 ` [PATCH 2/4] bcache: improve multithreaded bch_sectors_dirty_init() Coly Li
2022-05-21 17:05 ` [PATCH 3/4] bcache: remove incremental dirty sector counting for bch_sectors_dirty_init() Coly Li
2022-05-21 17:05 ` [PATCH 4/4] bcache: avoid journal no-space deadlock by reserving 1 journal bucket Coly Li
2022-06-08 20:45 ` Nix [this message]
2022-06-09 13:54 ` Coly Li
2022-05-22 17:07 [PATCH 0/4] bcache patches for Linux v5.19 (1st wave) Coly Li
2022-05-22 17:07 ` [PATCH 4/4] bcache: avoid journal no-space deadlock by reserving 1 journal bucket Coly Li
2022-05-24 10:23 [Resend PATCH v2 0/4] bcache fixes for Linux v5.19 (1st wave) Coly Li
2022-05-24 10:23 ` [PATCH 4/4] bcache: avoid journal no-space deadlock by reserving 1 journal bucket Coly Li
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