From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
To: Jan Kara <jack@suse.cz>, Christoph Hellwig <hch@lst.de>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, Ming Lei <ming.lei@redhat.com>
Subject: Re: [PATCH 5/8] loop: only take lo_mutex for the first reference in lo_open
Date: Thu, 27 Jan 2022 19:31:26 +0900 [thread overview]
Message-ID: <60b17284-8baf-a0a4-c27c-3f8f1e21b93c@I-love.SAKURA.ne.jp> (raw)
In-Reply-To: <20220127102848.eyzf5wwbssbvgkim@quack3.lan>
On 2022/01/27 19:28, Jan Kara wrote:
> So this also relies on disk->open_mutex for correctness. Otherwise a race
> like:
>
> Thread1 Thread2
> lo_open()
> if (atomic_inc_return(&lo->lo_refcnt) > 1)
> mutex_lock_killable(&lo->lo_mutex);
> lo_open()
> if (atomic_inc_return(&lo->lo_refcnt) > 1)
> return 0;
> ..
>
> can result in Thread2 using the loop device before Thread1 actually did the
> "first open" checks. So perhaps one common comment for lo_open + lo_release
> explaining the locking?
Please see https://lkml.kernel.org/r/7bebf860-2415-7eb6-55a1-47dc4439d9e9@I-love.SAKURA.ne.jp .
next prev parent reply other threads:[~2022-01-27 10:31 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-26 15:50 yet another approach to fix loop autoclear for xfstets xfs/049 Christoph Hellwig
2022-01-26 15:50 ` [PATCH 1/8] loop: de-duplicate the idle worker freeing code Christoph Hellwig
2022-01-27 9:36 ` Jan Kara
2022-01-26 15:50 ` [PATCH 2/8] loop: initialize the worker tracking fields once Christoph Hellwig
2022-01-27 9:45 ` Jan Kara
2022-01-26 15:50 ` [PATCH 3/8] block: remove the racy bd_inode->i_mapping->nrpages asserts Christoph Hellwig
2022-01-27 9:47 ` Jan Kara
2022-01-27 9:49 ` Christoph Hellwig
2022-01-27 12:23 ` Jan Kara
2022-01-28 7:26 ` Christoph Hellwig
2022-01-28 11:45 ` Jan Kara
2022-01-26 15:50 ` [PATCH 4/8] loop: only take lo_mutex for the last reference in lo_release Christoph Hellwig
2022-01-27 9:48 ` Jan Kara
2022-01-27 10:19 ` Jan Kara
2022-01-27 10:28 ` Christoph Hellwig
2022-01-26 15:50 ` [PATCH 5/8] loop: only take lo_mutex for the first reference in lo_open Christoph Hellwig
2022-01-27 10:28 ` Jan Kara
2022-01-27 10:31 ` Tetsuo Handa [this message]
2022-01-26 15:50 ` [PATCH 6/8] loop: don't freeze the queue in lo_release Christoph Hellwig
2022-01-27 10:42 ` Jan Kara
2022-01-28 6:46 ` Christoph Hellwig
2022-01-26 15:50 ` [PATCH 7/8] loop: only freeze the queue in __loop_clr_fd when needed Christoph Hellwig
2022-01-27 11:01 ` Jan Kara
2022-01-28 6:48 ` Christoph Hellwig
2022-01-26 15:50 ` [PATCH 8/8] loop: make autoclear operation synchronous again Christoph Hellwig
2022-01-27 11:04 ` Jan Kara
2022-01-26 19:38 ` yet another approach to fix loop autoclear for xfstets xfs/049 Darrick J. Wong
2022-01-27 16:50 ` Darrick J. Wong
2022-01-27 1:05 ` Tetsuo Handa
2022-01-28 7:08 ` Christoph Hellwig
2022-01-28 9:52 ` Tetsuo Handa
2022-01-28 13:00 yet another approach to fix loop autoclear for xfstets xfs/049 v2 Christoph Hellwig
2022-01-28 13:00 ` [PATCH 5/8] loop: only take lo_mutex for the first reference in lo_open Christoph Hellwig
2022-01-28 13:13 ` Tetsuo Handa
2022-02-05 0:28 ` Tetsuo Handa
2022-02-06 7:10 ` Tetsuo Handa
2022-02-08 13:45 ` Jan Kara
2022-02-23 14:24 ` Tetsuo Handa
2022-01-28 13:38 ` Jan Kara
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