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From: Carlos Maiolino <cmaiolino@redhat.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Andreas Dilger <adilger@dilger.ca>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Eric Sandeen <sandeen@redhat.com>,
	david@fromorbit.com
Subject: Re: [PATCH 09/10 V2] Use FIEMAP for FIBMAP calls
Date: Fri, 8 Feb 2019 11:36:17 +0100
Message-ID: <20190208103617.dlhbal7xwglgujdu@hades.usersys.redhat.com> (raw)
In-Reply-To: <20190208084612.GB23194@lst.de>

On Fri, Feb 08, 2019 at 09:46:12AM +0100, Christoph Hellwig wrote:
> On Thu, Feb 07, 2019 at 02:25:01PM -0700, Andreas Dilger wrote:
> > Do we really need to be this way, about reserving a single flag for Lustre,
> > which will likely also be useful for other filesystems?  It's not like
> > Lustre is some closed-source binary module for which we need to make life
> > difficult, it is used by many thousands of the largest computers at labs
> > and universities and companies around the world.  We are working to clean
> > up the code outside the staging tree and resubmit it.  Not reserving a flag
> > just means we will continue to use random values in Lustre before it can
> > be merged, which will make life harder when we try to merge again.
> 
> No, it is available in source, but otherwise just as bad.  And we generally
> only define APIs for in-kernel usage.
> 
> If we can come up with a good API for in-kernel filesystems we can do
> that, otherwise hell no.  And staging for that matter qualifies as out
> of tree.
> 
> That being said I'm really worried about these FIEMAP extensions as
> userspace has no business poking into details of the placement (vs
> just the layout).
> 
I tend to say that identifying on which device an extent is is better than
simply saying 'it maps to physical blocks X-Z, but it's your problem to identify
which device X-Z belongs to'.

> But all that belongs into a separate dicussion instead of dragging down
> this series where it does not belong at all.

Agreed, but now I'm on a kind of dead-end :P

Darrick's concerns are valid, regarding letting currently unsupported
filesystems to suddenly allow FIBMAP calls, but on the other hand, his proposed
solution, which is also valid, requires a new discussion/patchset to discuss an
improvement of the FIEMAP infra-structure, and 'fix' the problem mentioned.
Using a flag to identify FIBMAP calls has been rejected. So, I'd accept
suggestions on how to move this patch forward, without requiring the
improvements suggested by Darrick, and, without using a flag to tag FIBMAP
calls, as suggested by me, I'm kind of running out of ideas by now :(

Cheers

-- 
Carlos

  reply index

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-12-05  9:17 [PATCH 00/10 V2] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2018-12-05  9:17 ` [PATCH 01/10] fs: Enable bmap() function to properly return errors Carlos Maiolino
2018-12-05  9:17 ` [PATCH 02/10] cachefiles: drop direct usage of ->bmap method Carlos Maiolino
2018-12-05  9:17 ` [PATCH 03/10] ecryptfs: drop direct calls to ->bmap Carlos Maiolino
2018-12-05  9:17 ` [PATCH 04/10 V2] fibmap: Use bmap instead of ->bmap method in ioctl_fibmap Carlos Maiolino
2019-01-14 16:49   ` Christoph Hellwig
2019-02-04 11:34     ` Carlos Maiolino
2018-12-05  9:17 ` [PATCH 05/10] fs: Move start and length fiemap fields into fiemap_extent_info Carlos Maiolino
2019-01-14 16:50   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 06/10] iomap: Remove length and start fields from iomap_fiemap Carlos Maiolino
2019-01-14 16:51   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 07/10] fs: Use a void pointer to store fiemap_extent Carlos Maiolino
2019-01-14 16:53   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 08/10 V2] fiemap: Use a callback to fill fiemap extents Carlos Maiolino
2019-01-14 16:53   ` Christoph Hellwig
2018-12-05  9:17 ` [PATCH 09/10 V2] Use FIEMAP for FIBMAP calls Carlos Maiolino
2018-12-05 17:36   ` Darrick J. Wong
2018-12-07  9:09     ` Carlos Maiolino
2018-12-07 20:14       ` Andreas Dilger
2019-02-04 15:11     ` Carlos Maiolino
2019-02-04 18:27       ` Darrick J. Wong
2019-02-06 13:37         ` Carlos Maiolino
2019-02-06 20:44           ` Darrick J. Wong
2019-02-06 21:13             ` Andreas Dilger
2019-02-07  9:52               ` Carlos Maiolino
2019-02-08  8:43                 ` Christoph Hellwig
2019-02-11 12:57                   ` Christoph Hellwig
2019-02-11 16:21                     ` Carlos Maiolino
2019-02-11 16:48                       ` Christoph Hellwig
2019-02-07 11:59             ` Carlos Maiolino
2019-02-07 17:02               ` Darrick J. Wong
2019-02-07 21:25                 ` Andreas Dilger
2019-02-08  8:46                   ` Christoph Hellwig
2019-02-08 10:36                     ` Carlos Maiolino [this message]
2019-02-08 21:03                       ` Andreas Dilger
2019-02-08  9:08                   ` Carlos Maiolino
2019-02-08  9:03                 ` Carlos Maiolino
2019-02-07 12:36             ` Carlos Maiolino
2019-02-07 18:16               ` Darrick J. Wong
2019-02-08  8:58                 ` Carlos Maiolino
2019-02-06 21:04           ` Andreas Dilger
2019-01-14 16:56   ` Christoph Hellwig
2019-02-05  9:56     ` Carlos Maiolino
2019-02-05 18:25       ` Christoph Hellwig
2019-02-06  9:50         ` Carlos Maiolino
2018-12-05  9:17 ` [PATCH 10/10] xfs: Get rid of ->bmap Carlos Maiolino
2018-12-05 17:37   ` Darrick J. Wong
2018-12-06 13:06     ` Carlos Maiolino
2018-12-06 18:56 ` [PATCH 00/10 V2] New ->fiemap infrastructure and ->bmap removal Andreas Grünbacher
2018-12-07  9:34   ` Carlos Maiolino
2019-01-14 16:50     ` Christoph Hellwig
2019-01-14 17:56       ` Andreas Grünbacher
2019-01-14 17:58         ` Christoph Hellwig

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