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From: Matthew Bobrowski <mbobrowski@mbobrowski.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: tytso@mit.edu, jack@suse.cz, adilger.kernel@dilger.ca,
	linux-ext4@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	david@fromorbit.com, darrick.wong@oracle.com
Subject: Re: [PATCH v3 5/6] ext4: introduce direct IO write path using iomap infrastructure
Date: Fri, 20 Sep 2019 23:24:36 +1000	[thread overview]
Message-ID: <20190920132436.GA2863@bobrowski> (raw)
In-Reply-To: <20190917090613.GC29487@infradead.org>

On Tue, Sep 17, 2019 at 02:06:13AM -0700, Christoph Hellwig wrote:
> On Tue, Sep 17, 2019 at 08:37:41AM +1000, Matthew Bobrowski wrote:
> > > Independent of the error return issue you probably want to split
> > > modifying ext4_write_checks into a separate preparation patch.
> > 
> > Providing that there's no objections to introducing a possible performance
> > change with this separate preparation patch (overhead of calling
> > file_remove_privs/file_update_time twice), then I have no issues in doing so.
> 
> Well, we should avoid calling it twice.  But what caught my eye is that
> the buffered I/O path also called this function, so we are changing it as
> well here.  If that actually is safe (I didn't review these bits carefully
> and don't know ext4 that well) the overall refactoring of the write
> flow might belong into a separate prep patch (that is not relying
> on ->direct_IO, the checks changes, etc).

Yeah, no. Revisiting this again now and trying to implement the
ext4_write_checks() modifications as a pre-patch is a nightmare so to
speak. This is purely due to the way that ext4_file_write_iter() is currently
written and how both the current buffered I/O and direct I/O paths traverse
through and make use of it.

If anything, the changes applied to ext4_write_checks() should be a separate
patch that comes *after* the refactoring of the buffered and direct I/O write
flow. However, even then, there'd be code that we essentially introduce in the
write flow changes and then subsequently removed after the fact. Providing
that's OK, then sure, I can put this within a separate patch.

--<M>--

  parent reply	other threads:[~2019-09-20 13:24 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-12 11:03 [PATCH v3 0/6] ext4: port direct IO to iomap infrastructure Matthew Bobrowski
2019-09-12 11:03 ` [PATCH v3 1/6] ext4: introduce direct IO read path using " Matthew Bobrowski
2019-09-16 12:00   ` Christoph Hellwig
2019-09-16 13:07     ` Matthew Bobrowski
2019-09-12 11:04 ` [PATCH v3 2/6] ext4: move inode extension/truncate code out from ext4_iomap_end() Matthew Bobrowski
2019-09-23 16:21   ` Jan Kara
2019-09-24  9:50     ` Matthew Bobrowski
2019-09-24 13:13     ` Jan Kara
2019-09-12 11:04 ` [PATCH v3 3/6] iomap: split size and error for iomap_dio_rw ->end_io Matthew Bobrowski
2019-09-12 11:04 ` [PATCH v3 4/6] ext4: reorder map.m_flags checks in ext4_iomap_begin() Matthew Bobrowski
2019-09-16 12:05   ` Christoph Hellwig
2019-09-17 12:48     ` Matthew Bobrowski
2019-09-23 15:08   ` Jan Kara
2019-09-24  9:35     ` Matthew Bobrowski
2019-09-12 11:04 ` [PATCH v3 5/6] ext4: introduce direct IO write path using iomap infrastructure Matthew Bobrowski
2019-09-16  4:37   ` Ritesh Harjani
2019-09-16 10:14     ` Matthew Bobrowski
2019-09-16 12:12   ` Christoph Hellwig
2019-09-16 22:37     ` Matthew Bobrowski
2019-09-17  9:00       ` Ritesh Harjani
2019-09-17  9:02         ` Christoph Hellwig
2019-09-17 10:12           ` Ritesh Harjani
2019-09-17 12:39           ` Matthew Bobrowski
2019-09-24 10:57         ` Jan Kara
2019-09-17  9:06       ` Christoph Hellwig
2019-09-17 11:31         ` Matthew Bobrowski
2019-09-20 13:24         ` Matthew Bobrowski [this message]
2019-09-23 21:10   ` Jan Kara
2019-09-24 10:29     ` Matthew Bobrowski
2019-09-24 14:13       ` Jan Kara
2019-09-25  7:14         ` Matthew Bobrowski
2019-09-25  8:40           ` Jan Kara
2019-09-12 11:05 ` [PATCH v3 6/6] ext4: cleanup legacy buffer_head direct IO code Matthew Bobrowski
2019-09-16 12:06   ` Christoph Hellwig
2019-09-16 12:53     ` Matthew Bobrowski

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