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

[Gang He]

Hi Joseph,

On 2021/9/6 19:14, Joseph Qi wrote:
> 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?
So far, I do not find there is any risk for taking dir inode lock across 
the reflink function, it will block getting that dir inode lock a little 
time, but avoid ping-pong effect during the reflink function.


Thanks
Gang


> Thanks,
> Joseph