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Subject: Re: [PATCH] ocfs2: avoid getting dlm lock of the target directory
 multiple times during reflink process
To:     Gang He <ghe@suse.com>, mark@fasheh.com, jlbec@evilplan.org
Cc:     linux-kernel@vger.kernel.org, ocfs2-devel@oss.oracle.com,
        akpm@linux-foundation.org
References: <20210826075941.28480-1-ghe@suse.com>
From:   Joseph Qi <joseph.qi@linux.alibaba.com>
Message-ID: <41bc413d-0926-0eae-6772-076314bbae53@linux.alibaba.com>
Date:   Mon, 6 Sep 2021 19:14:26 +0800
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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