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From: "Darrick J. Wong" <darrick.wong-QHcLZuEGTsvQT0dZR+AlfA@public.gmane.org>
To: Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
Cc: david-FqsqvQoI3Ljby3iVrkZq2A@public.gmane.org,
	viro-3bDd1+5oDREiFSDQTTA3OLVCufUGDwFn@public.gmane.org,
	linux-xfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	xfs-VZNHf3L845pBDgjK7y7TUQ@public.gmane.org,
	linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [PATCH 3/6] vfs: support FS_XFLAG_REFLINK and FS_XFLAG_COWEXTSIZE
Date: Tue, 6 Sep 2016 12:15:15 -0700	[thread overview]
Message-ID: <20160906191515.GA26927@birch.djwong.org> (raw)
In-Reply-To: <20160905145622.GB7662-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>

On Mon, Sep 05, 2016 at 07:56:22AM -0700, Christoph Hellwig wrote:
> On Thu, Aug 25, 2016 at 04:31:00PM -0700, Darrick J. Wong wrote:
> > Introduce XFLAGs for the new XFS reflink inode flag and the CoW extent
> > size hint, and actually plumb the CoW extent size hint into the fsxattr
> > structure.
> 
> Just curious, but why would we even bother to expose the reflink flag
> to userspace?

So far I've put the reflink flag to use in xfs_scrub to look for
obvious signs of brokenness such as extents that overlap or have the
shared flag set but the inode flag is off; and to skip various kinds
of checks that don't have to happen when blocks don't overlap.

I doubt there's much of a use for the flag outside of the XFS utilities.
For a while I pondered only exposing the fsxattr flag if the caller had
CAP_SYS_ADMIN (the level of priviledge required to run scrub) but
decided that I wouldn't change the existing interface like that unless
I had a really good reason.

--D

  parent reply	other threads:[~2016-09-06 19:15 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-25 23:30 [PATCH v8 0/6] vfs: help support reflink for XFS Darrick J. Wong
2016-08-25 23:30 ` [PATCH 1/6] vfs: fix return type of ioctl_file_dedupe_range Darrick J. Wong
2016-08-25 23:30 ` [PATCH 2/6] vfs: cap dedupe request structure size at PAGE_SIZE Darrick J. Wong
     [not found]   ` <147216785429.525.1965983896010934181.stgit-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2016-09-05 14:55     ` Christoph Hellwig
     [not found]       ` <20160905145549.GA7662-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2016-09-13  1:16         ` Darrick J. Wong
2016-09-14 20:22           ` Christoph Hellwig
2016-08-25 23:31 ` [PATCH 3/6] vfs: support FS_XFLAG_REFLINK and FS_XFLAG_COWEXTSIZE Darrick J. Wong
     [not found]   ` <147216786073.525.16014208838990530622.stgit-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2016-09-05 14:56     ` Christoph Hellwig
     [not found]       ` <20160905145622.GB7662-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2016-09-06 19:15         ` Darrick J. Wong [this message]
2016-09-11 12:58           ` Christoph Hellwig
2016-09-12 19:12             ` Darrick J. Wong
2016-08-25 23:31 ` [PATCH 4/6] fs: add iomap_file_dirty Christoph Hellwig
2016-09-05 14:57   ` Christoph Hellwig
2016-09-06 17:34     ` Darrick J. Wong
2016-09-11 12:58       ` Christoph Hellwig
     [not found]     ` <20160905145751.GC7662-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2016-09-19  0:11       ` Dave Chinner
2016-08-25 23:31 ` [PATCH 5/6] iomap: don't set FIEMAP_EXTENT_MERGED for extent based filesystems Darrick J. Wong
     [not found] ` <147216784041.525.7722906502172299465.stgit-PTl6brltDGh4DFYR7WNSRA@public.gmane.org>
2016-08-25 23:31   ` [PATCH 6/6] iomap: add a flag to report shared extents Darrick J. Wong
2016-09-05 14:58     ` Christoph Hellwig

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