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From: Christoph Hellwig <hch@infradead.org>
To: Mark Fasheh <mark.fasheh@oracle.com>
Cc: Christoph Hellwig <hch@infradead.org>,
	Nick Piggin <npiggin@suse.de>,
	Linux Filesystems <linux-fsdevel@vger.kernel.org>,
	Linux Kernel <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [patch 2/3] fs: introduce perform_write aop
Date: Sat, 10 Mar 2007 09:25:41 +0000	[thread overview]
Message-ID: <20070310092541.GA22182@infradead.org> (raw)
In-Reply-To: <20070309233301.GC18555@ca-server1.us.oracle.com>

On Fri, Mar 09, 2007 at 03:33:01PM -0800, Mark Fasheh wrote:
> ->kernel_write() as opposed to genericizing ->perform_write() would be fine
> with me. Just so long as we get rid of ->prepare_write and ->commit_write in
> that other kernel code doesn't call them directly. That interface just
> doesn't work for Ocfs2.

It doesn't work for any filesystem that needs slightly fancy locking.
That and the reason that's an interface that doesn't fit into our
layering is why I want to get rid of it.  Note that fops->kernel_write
might in fact use ->perform_write with an actor as Nick suggested.
I'm not quite sure how it'll look like - I'd rather take care of the
buffered write path first and then handle this issue once the first
changes have stabilized.

> Right now I've got Ocfs2 implementing it's own lowest-level buffered write
> code - think generic_file_buffered_write() replacement for Ocfs2. With some
> duplicated code above that layer. What's nice is that I can abstract away
> the "copy data into some target pages" bits such that the majority of that
> code is re-usable for ocfs2's splice write operation. I'm not sure we could
> have that low a level of abstraction for anyhing above individual the file
> system though which also has to deal with non-kernel writes though. That's
> where a ->kernel_write() might come in handy.

Why do you need your own low level buffered write functionality?  As in
past times when filesystems want to come up I'd like to have a very
good exaplanation on why you think it's needed and whether we shouldn't
improve the generic buffered write code instead.  This codepath is so nasty
that any duplication will be a maintaince horror.


  reply	other threads:[~2007-03-10  9:25 UTC|newest]

Thread overview: 34+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-08 13:07 [rfc][patch 0/3] a faster buffered write deadlock fix? Nick Piggin
2007-02-08 13:07 ` [patch 1/3] fs: add an iovec iterator Nick Piggin
2007-02-08 19:49   ` Christoph Hellwig
2007-02-09  1:46     ` Nick Piggin
2007-02-09  2:03       ` Nate Diller
2007-02-09  3:31         ` Nick Piggin
2007-02-09 17:28           ` Zach Brown
2007-03-09 10:40         ` Christoph Hellwig
2007-02-08 23:04   ` Mark Fasheh
2007-02-08 13:07 ` [patch 2/3] fs: introduce perform_write aop Nick Piggin
2007-03-09 10:39   ` Christoph Hellwig
2007-03-09 12:52     ` Nick Piggin
2007-03-09 22:01       ` Anton Altaparmakov
2007-03-09 23:33     ` Mark Fasheh
2007-03-10  9:25       ` Christoph Hellwig [this message]
2007-03-12  2:13         ` Mark Fasheh
2007-03-14 13:30         ` Nick Piggin
2007-03-14 15:17           ` Christoph Hellwig
2007-02-08 13:07 ` [patch 3/3] ext2: use " Nick Piggin
2007-02-08 14:47   ` Dmitriy Monakhov
2007-02-09 19:14   ` Andrew Morton
2007-02-09 19:45     ` Andrew Morton
2007-02-10  1:34       ` Nick Piggin
2007-02-10  1:50         ` Andrew Morton
2007-02-09  0:38 ` [rfc][patch 0/3] a faster buffered write deadlock fix? Mark Fasheh
2007-02-09  2:04   ` Nick Piggin
2007-02-09  8:41 ` Andrew Morton
2007-02-09  9:54   ` Nick Piggin
2007-02-09 10:09     ` Andrew Morton
2007-02-09 10:32       ` Nick Piggin
2007-02-09 10:52         ` Andrew Morton
2007-02-09 11:31           ` Nick Piggin
2007-02-09 11:46             ` Andrew Morton
2007-02-09 12:11               ` Nick Piggin

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