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From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-fsdevel@vger.kernel.org, hch@lst.de, adilger@dilger.ca,
	jaegeuk@kernel.org, miklos@szeredi.hu, rpeterso@redhat.com,
	linux-xfs@vger.kernel.org
Subject: Re: [PATCH 8/9] Use FIEMAP for FIBMAP calls
Date: Tue, 6 Aug 2019 07:46:04 +0200	[thread overview]
Message-ID: <20190806054604.GK13409@lst.de> (raw)
In-Reply-To: <20190802152902.GI7138@magnolia>

On Fri, Aug 02, 2019 at 08:29:02AM -0700, Darrick J. Wong wrote:
> It's harder for me to tell when I don't have a branch containing the
> final product to look at, but I'd have thought that _fill_kernel fills
> out an in-kernel fiemap extent; and then _fill_user would declare one on
> the stack, call _fill_kernel to set the fields, and then copy_to_user?

That works fine for small, fixed-sized structures.  But for large
variable sized structures it is very inefficient, as we need to do a
possibly large kernel allocation and just copy it on.  Thus I told Carlos
to follow the readdir model with the ->actor (used to be ->filldir)
callback that can fill out the actual kernel or user data directly.
Another example of this high-level model is our struct iov_iter used
in the I/O path.

  parent reply	other threads:[~2019-08-06  5:46 UTC|newest]

Thread overview: 51+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-31 14:12 [PATCH 0/9 V4] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2019-07-31 14:12 ` [PATCH 1/9] fs: Enable bmap() function to properly return errors Carlos Maiolino
2019-07-31 14:12 ` [PATCH 2/9] cachefiles: drop direct usage of ->bmap method Carlos Maiolino
2019-07-31 14:12 ` [PATCH 3/9] ecryptfs: drop direct calls to ->bmap Carlos Maiolino
2019-07-31 14:12 ` [PATCH 4/9] fibmap: Use bmap instead of ->bmap method in ioctl_fibmap Carlos Maiolino
2019-07-31 23:12   ` Darrick J. Wong
2019-08-02  9:19     ` Carlos Maiolino
2019-08-02 15:14       ` Darrick J. Wong
2019-08-05 10:27         ` Carlos Maiolino
2019-08-05 15:12           ` Darrick J. Wong
2019-08-06  5:38             ` Christoph Hellwig
2019-08-06 12:07               ` Carlos Maiolino
2019-08-06 14:48                 ` Darrick J. Wong
2019-08-08  7:17                   ` Carlos Maiolino
2019-08-06 12:02             ` Carlos Maiolino
2019-08-06 22:41             ` Luis Chamberlain
2019-08-07 14:42               ` Darrick J. Wong
2019-08-08  7:12               ` Carlos Maiolino
2019-08-08 18:53                 ` Andreas Dilger
2019-08-19 10:10                   ` Carlos Maiolino
2019-07-31 14:12 ` [PATCH 5/9] fs: Move start and length fiemap fields into fiemap_extent_info Carlos Maiolino
2019-07-31 23:28   ` Darrick J. Wong
2019-08-02  9:51     ` Carlos Maiolino
2019-08-02 15:15       ` Darrick J. Wong
2019-08-05  9:40         ` Carlos Maiolino
2019-08-06  5:39       ` Christoph Hellwig
2019-07-31 14:12 ` [PATCH 6/9] iomap: Remove length and start fields from iomap_fiemap Carlos Maiolino
2019-07-31 23:24   ` Darrick J. Wong
2019-07-31 14:12 ` [PATCH 7/9] fiemap: Use a callback to fill fiemap extents Carlos Maiolino
2019-07-31 23:26   ` Darrick J. Wong
2019-07-31 14:12 ` [PATCH 8/9] Use FIEMAP for FIBMAP calls Carlos Maiolino
2019-07-31 23:22   ` Darrick J. Wong
2019-07-31 23:31     ` Darrick J. Wong
2019-08-02 13:52       ` Carlos Maiolino
2019-08-06  5:41       ` Christoph Hellwig
2019-08-02 13:48     ` Carlos Maiolino
2019-08-02 15:29       ` Darrick J. Wong
2019-08-05 10:38         ` Carlos Maiolino
2019-08-06  5:46         ` Christoph Hellwig [this message]
2019-07-31 14:12 ` [PATCH 9/9] xfs: Get rid of ->bmap Carlos Maiolino
2019-07-31 23:30   ` Darrick J. Wong
2019-08-02 10:20 ` [PATCH 0/9 V4] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2019-08-08  8:27 [PATCH 0/9 V5] " Carlos Maiolino
2019-08-08  8:27 ` [PATCH 8/9] Use FIEMAP for FIBMAP calls Carlos Maiolino
2019-08-09  1:56   ` kbuild test robot
2019-08-14 11:18   ` Christoph Hellwig
2019-08-20 13:01     ` Carlos Maiolino
2019-08-29  7:15       ` Christoph Hellwig
2019-09-10 12:28         ` Carlos Maiolino
2019-09-16 15:58           ` Darrick J. Wong
2019-09-11 13:43 [PATCH 0/9 V6] New ->fiemap infrastructure and ->bmap removal Carlos Maiolino
2019-09-11 13:43 ` [PATCH 8/9] Use FIEMAP for FIBMAP calls Carlos Maiolino
2019-09-16 17:44   ` Darrick J. Wong

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