linux-kernel - Re: [PATCH 3/3] f2fs: support clone_file

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Date:	Mon, 18 Jul 2016 21:48:20 -0700
From:	Jaegeuk Kim <jaegeuk@...nel.org>
To:	Christoph Hellwig <hch@...radead.org>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net, linux-api@...r.kernel.org
Subject: Re: [PATCH 3/3] f2fs: support clone_file_range

On Mon, Jul 18, 2016 at 08:47:36PM -0700, Christoph Hellwig wrote:
> On Sat, Jul 16, 2016 at 11:24:27PM -0700, Jaegeuk Kim wrote:
> > This patch implements clone_file_range in f2fs.
> 
> [...]
> 
> > +int f2fs_clone_file_range(struct file *file_in, loff_t pos_in,
> > +		struct file *file_out, loff_t pos_out, u64 len)
> > +{
> > +	return f2fs_clone_files(file_in, pos_in, file_out, pos_out, len);
> > +}
> > +
> 
> Falling back from copy to clone should be done in the VFS.  I look into
> implementing the fallback, and the code is trivial, but we don't seem
> to have any useful coverage for copy_file_range yet, so I didn't dare
> to add it yet.  How did you test copy and clone in f2fs?  And how did
> you handle the difference in corner cases (e.g. the lacking 0 special
> case in copy)?

Frankly speaking, I confused the behaviors without being aware of corner cases.
And thus, I dropped the patches already. Instead, I realized that what I did
was moving a range of blocks from one file to another file. So, I've been
testing a new ioctl, F2FS_IOC_MOVE_RANGE.
In terms of coverage, I just did some unit tests only.

Thanks,