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From:   Pavel Tatashin <pasha.tatashin@soleen.com>
Date:   Tue, 26 Jan 2021 09:22:48 -0500
Message-ID: <CA+CK2bBVdVOP6TmJED4Wndovxf+dGbcbw=0LQ8neAGL_2=TEwA@mail.gmail.com>
Subject: Re: [PATCH v3 1/1] loop: scale loop device by introducing per device lock
To:     Petr Vorel <pvorel@suse.cz>
Cc:     Tyler Hicks <tyhicks@linux.microsoft.com>,
        Jens Axboe <axboe@kernel.dk>, linux-block@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Sasha Levin <sashal@kernel.org>,
        James Morris <jmorris@namei.org>, lukas.bulwahn@gmail.com,
        hch@lst.de, ming.lei@redhat.com, mzxreary@0pointer.de,
        mcgrof@kernel.org, zhengbin13@huawei.com, maco@android.com,
        Colin King <colin.king@canonical.com>, evgreen@chromium.org
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Precedence: bulk

On Tue, Jan 26, 2021 at 4:24 AM Petr Vorel <pvorel@suse.cz> wrote:
>
> Hi,
>
> > 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 the
> > fields in struct loop_device. Keep loop_ctl_mutex to protect global
> > data such as loop_index_idr, loop_lookup, loop_add.
>
> > Lock ordering: loop_ctl_mutex > lo_mutex.
>
> Reviewed-by: Petr Vorel <pvorel@suse.cz>

Thank you for reviewing this patch.

Pasha