linux-kernel - Re: [PATCH] ocfs2: avoid getting dlm lock of the target directory multiple times during reflink process

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Message-ID: <41bc413d-0926-0eae-6772-076314bbae53@linux.alibaba.com>
Date:   Mon, 6 Sep 2021 19:14:26 +0800
From:   Joseph Qi <joseph.qi@...ux.alibaba.com>
To:     Gang He <ghe@...e.com>, mark@...heh.com, jlbec@...lplan.org
Cc:     linux-kernel@...r.kernel.org, ocfs2-devel@....oracle.com,
        akpm@...ux-foundation.org
Subject: Re: [PATCH] ocfs2: avoid getting dlm lock of the target directory
 multiple times during reflink process

Hi Gang,


On 8/26/21 3:59 PM, Gang He wrote:
> During the reflink process, we should acquire the target directory
> inode dlm lock at the beginning, and hold this dlm lock until end
> of the function.
> With this patch, we avoid dlm lock ping-pong effect when clone
> files to the same directory simultaneously from multiple nodes.
> There is a typical user scenario, users regularly back up files
> to a specified directory through the reflink feature from the
> multiple nodes.
> 
Since now it take dir inode lock across the whole reflink, it may impact
other concurrent operations under the same directory.
Have you evaluated such cases?

Thanks,
Joseph