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From: Christoph Hellwig <hch@lst.de>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	avi@scylladb.com, Dave Chinner <dchinner@redhat.com>
Subject: Re: [PATCH 11/11] xfs: reduce exclusive locking on unaligned dio
Date: Wed, 20 Jan 2021 19:44:00 +0100
Message-ID: <20210120184400.GA29173@lst.de> (raw)
In-Reply-To: <20210120184056.GC3133414@magnolia>

[another full quote removed, guys please send properly formatted email]

On Wed, Jan 20, 2021 at 10:40:56AM -0800, Darrick J. Wong wrote:
> > +	if (!(flags & IOMAP_DIO_UNALIGNED))
> > +		inode_dio_wait(VFS_I(ip));
> 
> Er... this really confused me when I read it -- my first thought was
> "How can we be in the unaligned direct write function but DIO_UNALIGNED
> isn't set?  Wouldn't we be in some other function if we're doing an
> aligned direct write?"
> 
> Then I looked upthread to where Christph said he'd renamed it
> IOMAP_DIO_SUBBLOCK, but I didn't think that was sufficiently better:
> 
> 	if (!(flags & IOMAP_DIO_SUBBLOCK))
> 		iomap_dio_wait(...);
> 
> This flag doesn't have a 1:1 relationship with the iocb asking for an
> (fsblock-)unaligned write or the iocb saying that the write involves
> sub-block io -- this flag really means "I require a stable written
> mapping, no post-processing (of the disk block) allowed".

Would:

	if (flags & IOMAP_DIO_FORCE_WAIT)
		inode_dio_wait(VFS_I(ip));

look any better to you?  Behavior would be the same.

  reply index

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-18 19:35 reduce sub-block DIO serialisation v2 Christoph Hellwig
2021-01-18 19:35 ` [PATCH 01/11] xfs: factor out a xfs_ilock_iocb helper Christoph Hellwig
2021-01-20 18:41   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 02/11] xfs: make xfs_file_aio_write_checks IOCB_NOWAIT-aware Christoph Hellwig
     [not found]   ` <CACz=WeeaqMrGM53pJF0C_Wt2JuavTOnOV26-osPviYLUpqUmFw@mail.gmail.com>
2021-01-20 16:28     ` Christoph Hellwig
2021-01-20 18:42   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 03/11] xfs: cleanup the read/write helper naming Christoph Hellwig
2021-01-19 15:23   ` Brian Foster
2021-01-20 18:43   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 04/11] xfs: remove the buffered I/O fallback assert Christoph Hellwig
2021-01-19 15:23   ` Brian Foster
2021-01-20 18:43   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 05/11] xfs: simplify the read/write tracepoints Christoph Hellwig
2021-01-19 15:23   ` Brian Foster
2021-01-20 18:45   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 06/11] xfs: improve the reflink_bounce_dio_write tracepoint Christoph Hellwig
2021-01-19 15:23   ` Brian Foster
2021-01-20 18:45   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 07/11] xfs: split unaligned DIO write code out Christoph Hellwig
2021-01-19 15:23   ` Brian Foster
2021-01-20 18:46   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 08/11] iomap: rename the flags variable in __iomap_dio_rw Christoph Hellwig
2021-01-18 20:34   ` Dave Chinner
2021-01-19 15:23   ` Brian Foster
2021-01-20 18:46   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 09/11] iomap: pass a flags argument to iomap_dio_rw Christoph Hellwig
2021-01-19 15:23   ` Brian Foster
2021-01-20 18:17   ` Darrick J. Wong
2021-01-20 18:35     ` Christoph Hellwig
2021-01-18 19:35 ` [PATCH 10/11] iomap: add a IOMAP_DIO_UNALIGNED flag Christoph Hellwig
2021-01-18 20:45   ` Dave Chinner
2021-01-18 21:41   ` Matthew Wilcox
2021-01-20 16:40     ` Christoph Hellwig
2021-01-20 18:47   ` Darrick J. Wong
2021-01-18 19:35 ` [PATCH 11/11] xfs: reduce exclusive locking on unaligned dio Christoph Hellwig
2021-01-18 20:55   ` Dave Chinner
2021-01-20 16:36     ` Christoph Hellwig
2021-01-20 18:40   ` Darrick J. Wong
2021-01-20 18:44     ` Christoph Hellwig [this message]
2021-01-20 19:58       ` Darrick J. Wong
2021-01-21  8:58 reduce sub-block DIO serialisation v3 Christoph Hellwig
2021-01-21  8:59 ` [PATCH 11/11] xfs: reduce exclusive locking on unaligned dio Christoph Hellwig
2021-01-21  9:35   ` Dave Chinner
2021-01-22 10:20     ` Christoph Hellwig
2021-01-21 13:33   ` Brian Foster
2021-01-21 19:01     ` Darrick J. Wong
2021-01-22 16:20 reduce sub-block DIO serialisation v4 Christoph Hellwig
2021-01-22 16:20 ` [PATCH 11/11] xfs: reduce exclusive locking on unaligned dio Christoph Hellwig
2021-01-22 17:24   ` Darrick J. Wong

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