From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Mark Fasheh <mfasheh@suse.de>
Cc: Carlos Maiolino <cmaiolino@redhat.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Eric Sandeen <sandeen@sandeen.net>,
linux-fsdevel@vger.kernel.org, david@fromorbit.com,
hch@infradead.org
Subject: Re: Ext4 fiemap implementation
Date: Tue, 12 Jun 2018 23:06:01 -0400 [thread overview]
Message-ID: <20180613030601.GB3340@thunk.org> (raw)
In-Reply-To: <20180612235203.GE28053@wotan.suse.de>
On Wed, Jun 13, 2018 at 01:52:03AM +0200, Mark Fasheh wrote:
> >
> > So, you are saying iomap implementation violates FIEMAP specs?
>
> Does iomap do this or just XFS? At any rate, the doc should be read
> as Ted suggests: '"Extents returned mirror those on disk" as meaning
> that the ext4 behavior is *mandated* by the docs.'
>
> So anything that's mainipulating the returned extents solely to
> 'fit' them into a request is wrong.
Well, or the FIEMAP specs could be changed. If I recall correctly the
FIEMAP implementation by the various file systems predates the
documentation. I suspect whoever wrote the docs looked at the
ext2/ext3/ext4 implementation and used that to write the
documentation. If other file systems were doing something else, I'd
be in favor of allowing either behavior, since userspace programs who
care will need to accomodate either behavior. Fortunately, I suspect
it matters for very few (if any) userspace programs.
- Ted
next prev parent reply other threads:[~2018-06-13 3:06 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-01 12:36 Ext4 fiemap implementation Carlos Maiolino
2018-06-01 15:01 ` Eric Sandeen
2018-06-03 3:28 ` Theodore Y. Ts'o
2018-06-04 16:43 ` Darrick J. Wong
2018-06-06 13:13 ` Carlos Maiolino
2018-06-06 14:40 ` Darrick J. Wong
2018-06-07 8:31 ` Carlos Maiolino
2018-06-07 16:25 ` Darrick J. Wong
2018-06-08 8:18 ` Carlos Maiolino
2018-06-08 22:41 ` Mark Fasheh
2018-06-11 7:28 ` Carlos Maiolino
2018-06-12 23:52 ` Mark Fasheh
2018-06-13 3:06 ` Theodore Y. Ts'o [this message]
2018-06-13 3:32 ` Dave Chinner
2018-06-13 5:04 ` Theodore Y. Ts'o
2018-06-13 7:41 ` Dave Chinner
2018-06-13 12:09 ` Christoph Hellwig
2018-06-14 8:14 ` Carlos Maiolino
2018-06-01 18:57 ` Andreas Dilger
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