From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Christoph Hellwig <hch@lst.de>
Cc: xfs@oss.sgi.com
Subject: Re: [PATCH] xfs: don't hand out pNFS layouts for reflink inodes
Date: Tue, 29 Mar 2016 17:08:42 -0700 [thread overview]
Message-ID: <20160330000842.GD5822@birch.djwong.org> (raw)
In-Reply-To: <20160329072128.GA14940@lst.de>
On Tue, Mar 29, 2016 at 09:21:28AM +0200, Christoph Hellwig wrote:
> On Mon, Mar 28, 2016 at 12:51:40PM -0700, Darrick J. Wong wrote:
> > > /*
> > > + * The pNFS block layout spec actually supports reflink like
> > > + * functionality, but the Linux pNFS server doesn't implement it yet.
> > > + */
> > > + if (!xfs_is_reflink_inode(ip))
> > > + return -ENXIO;
> >
> > /me isn't familiar with pNFS, but doesn't this make it so that
> > xfs_fs_map_blocks /only/ works on reflinked files? Maybe I'm misreading the
> > comment, but it sounds to me like Linux doesn't support reflinked files over
> > pNFS and therefore we want to disable this iomapping functionality any time we
> > find a reflinked file.
> >
> > But maybe there's a subtlety here that I'm missing?
>
> You jsut missed me fat fingering the check :)
Fair enough, I'll integrate this patch, but with:
if (xfs_is_reflink_inode(ip))
return -ENXIO;
> Btw, we'll need something similar to prevent swapfiles which just use
> ->bmap, but unfortunately swap just checks for the existences of method,
> so I'll probably have to do some VFS changes to properly support that.
Yes, please. ocfs2 will gladly let you call swapon on a reflinked file,
and totally fails to CoW it properly. :)
--D
>
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next prev parent reply other threads:[~2016-03-30 0:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-03-02 16:34 [PATCH] xfs: don't hand out pNFS layouts for reflink inodes Christoph Hellwig
2016-03-28 19:51 ` Darrick J. Wong
2016-03-29 7:21 ` Christoph Hellwig
2016-03-30 0:08 ` Darrick J. Wong [this message]
2016-03-30 17:26 ` Christoph Hellwig
2016-03-30 17:40 ` Darrick J. Wong
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