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Subject: Re: [PATCH v4 1/1] loop: scale loop device by introducing per device
 lock
To:     Pavel Tatashin <pasha.tatashin@soleen.com>,
        tyhicks@linux.microsoft.com, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, sashal@kernel.org, jmorris@namei.org,
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        zhengbin13@huawei.com, maco@android.com, colin.king@canonical.com,
        evgreen@chromium.org
References: <20210126144630.230714-1-pasha.tatashin@soleen.com>
 <20210126144630.230714-2-pasha.tatashin@soleen.com>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <daf21294-f51e-3f03-8a46-d0181104d9e3@kernel.dk>
Date:   Tue, 26 Jan 2021 13:09:05 -0700
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On 1/26/21 7:46 AM, Pavel Tatashin wrote:
> Currently, loop device has only one global lock: loop_ctl_mutex.
> 
> This becomes hot in scenarios where many loop devices are used.
> 
> Scale it by introducing per-device lock: lo_mutex that protects
> modifications of all fields in struct loop_device.
> 
> Keep loop_ctl_mutex to protect global data: loop_index_idr, loop_lookup,
> loop_add.
> 
> The new lock ordering requirement is that loop_ctl_mutex must be taken
> before lo_mutex.

Applied, thanks.

-- 
Jens Axboe