linux-kernel - Re: [PATCH v3 1/1] loop: scale loop device by introducing per device lock

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Date:   Tue, 26 Jan 2021 09:22:48 -0500
From:   Pavel Tatashin <pasha.tatashin@...een.com>
To:     Petr Vorel <pvorel@...e.cz>
Cc:     Tyler Hicks <tyhicks@...ux.microsoft.com>,
        Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        Sasha Levin <sashal@...nel.org>,
        James Morris <jmorris@...ei.org>, lukas.bulwahn@...il.com,
        hch@....de, ming.lei@...hat.com, mzxreary@...inter.de,
        mcgrof@...nel.org, zhengbin13@...wei.com, maco@...roid.com,
        Colin King <colin.king@...onical.com>, evgreen@...omium.org
Subject: Re: [PATCH v3 1/1] loop: scale loop device by introducing per device lock

On Tue, Jan 26, 2021 at 4:24 AM Petr Vorel <pvorel@...e.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@...e.cz>

Thank you for reviewing this patch.

Pasha