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From: Christoph Hellwig <hch@lst.de>
To: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Dave Chinner <david@fromorbit.com>,
	cluster-devel <cluster-devel@redhat.com>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	Dave Chinner <dchinner@redhat.com>
Subject: Re: [PATCH v4 06/11] iomap: Add write_{begin,end} iomap operations
Date: Fri, 18 May 2018 18:04:58 +0200	[thread overview]
Message-ID: <20180518160458.GA3503@lst.de> (raw)
In-Reply-To: <CAHc6FU6kwz4ZsKUdTHjNX5BsLb3Z0csqwP-UV0fHbLNsm70cDg@mail.gmail.com>

On Tue, May 15, 2018 at 10:16:52AM +0200, Andreas Gruenbacher wrote:
> > Yes.  And from a quick look we can easily handle "stuffed" aka inline
> > data with the existing architecture.  We just need a new IOMAP_INLINE
> > flag for the extent type. Details will need to be worked out how to
> > pass that data, either a struct page or virtual address should probably
> > do it.
> 
> This is about data journaling, it has nothing to do with "stuffed"
> files per se. With journaled data writes, we need to do some special
> processing for each page so that the page ends up in the journal
> before it gets written back to its proper on-disk location. It just
> happens that since we need these per-page operations anyway, the
> "unstuffing" and "re-stuffing" nicely fits in those operations as
> well.

Your series makes two uses of the callbacks - one use case is to
deal with inline data.  The right way to deal with that is to make
inline data an explicit iomap type (done in my next posting of the
buffer head removal series), and then have iomap_begin find the data,
kmap it and return it in the iomap, with iomap_end doing any fixups.

For the data journaing I agree that we need a post-write per page
callout, but I think this should be just a simple optional callout
just for data journaling, which doesn't override the remaining
write_end handling.

> Been there. An earlier version of the patches did have a separate
> stuffed write path and the unstuffing and re-stuffing didn't happen in
> those per-page operations. The result was much messier overall.

Pointer, please.

  reply	other threads:[~2018-05-18 16:00 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-14 15:36 [PATCH v4 00/11] gfs2 iomap write support Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 01/11] gfs2: Update find_metapath comment Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 02/11] gfs2: hole_size improvement Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 03/11] gfs2: gfs2_stuffed_write_end cleanup Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 04/11] gfs2: Remove ordered write mode handling from gfs2_trans_add_data Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 05/11] gfs2: Iomap cleanups and improvements Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 06/11] iomap: Add write_{begin,end} iomap operations Andreas Gruenbacher
2018-05-15  1:11   ` Dave Chinner
2018-05-15  7:22     ` Christoph Hellwig
2018-05-15  8:16       ` Andreas Gruenbacher
2018-05-18 16:04         ` Christoph Hellwig [this message]
2018-05-25 17:58           ` Andreas Grünbacher
2018-05-28 13:02             ` Christoph Hellwig
2018-05-14 15:36 ` [PATCH v4 07/11] gfs2: iomap buffered write support Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 08/11] gfs2: gfs2_extent_length cleanup Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 09/11] gfs2: iomap direct I/O support Andreas Gruenbacher
2018-05-15  7:31   ` Christoph Hellwig
2018-05-16 20:36     ` Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 10/11] gfs2: Remove gfs2_write_{begin,end} Andreas Gruenbacher
2018-05-14 15:36 ` [PATCH v4 11/11] iomap: Complete partial direct I/O writes synchronously Andreas Gruenbacher
2018-05-15  7:24   ` Christoph Hellwig
2018-05-16 20:27     ` Andreas Gruenbacher
2018-05-18 15:56       ` Christoph Hellwig
2018-05-18 18:35         ` Andreas Grünbacher

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