From: Christoph Hellwig <hch@infradead.org>
To: Jan Kara <jack@suse.cz>
Cc: Dave Chinner <david@fromorbit.com>,
linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-block@vger.kernel.org, hch@lst.de, rdorr@microsoft.com
Subject: Re: [PATCH 4/4] iomap: Use FUA for pure data O_DSYNC DIO writes
Date: Tue, 24 Apr 2018 10:34:44 -0700 [thread overview]
Message-ID: <20180424173444.GA25233@infradead.org> (raw)
In-Reply-To: <20180421125405.hyx3bbkohdgvducq@quack2.suse.cz>
On Sat, Apr 21, 2018 at 02:54:05PM +0200, Jan Kara wrote:
> > - if (iocb->ki_flags & IOCB_DSYNC)
> > + if (iocb->ki_flags & IOCB_DSYNC) {
> > dio->flags |= IOMAP_DIO_NEED_SYNC;
> > + /*
> > + * We optimistically try using FUA for this IO. Any
> > + * non-FUA write that occurs will clear this flag, hence
> > + * we know before completion whether a cache flush is
> > + * necessary.
> > + */
> > + dio->flags |= IOMAP_DIO_WRITE_FUA;
> > + }
>
> So I don't think this is quite correct. IOCB_DSYNC gets set also for O_SYNC
> writes (in that case we also set IOCB_SYNC). And for those we cannot use
> the FUA optimization AFAICT (definitely IOMAP_F_DIRTY isn't a safe
> indicator of a need of full fsync for O_SYNC). Other than that the patch
> looks good to me.
Oops, good catch. I think the above if should just be
if (iocb->ki_flags & (IOCB_DSYNC | IOCB_SYNC) == IOCB_DSYNC)) {
and we are fine.
>
> Honza
> --
> Jan Kara <jack@suse.com>
> SUSE Labs, CR
> --
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---end quoted text---
next prev parent reply other threads:[~2018-04-24 17:34 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-18 4:08 [PATCH 0/4 V2] iomap: Use FUA for O_DSYNC DIO writes Dave Chinner
2018-04-18 4:08 ` [PATCH 1/4] xfs: move generic_write_sync calls inwards Dave Chinner
2018-04-18 4:08 ` [PATCH 2/4] iomap: iomap_dio_rw() handles all sync writes Dave Chinner
2018-04-21 13:03 ` Jan Kara
2018-05-02 2:45 ` Dave Chinner
2018-05-02 14:27 ` Robert Dorr
2018-05-03 13:34 ` Jan Kara
2018-05-03 12:51 ` Jan Kara
2018-04-18 4:08 ` [PATCH 3/4] blk: add blk_queue_fua() helper function Dave Chinner
2018-04-18 10:34 ` Christoph Hellwig
2018-04-18 12:18 ` Matthew Wilcox
2018-04-18 14:23 ` Jens Axboe
2018-04-18 4:08 ` [PATCH 4/4] iomap: Use FUA for pure data O_DSYNC DIO writes Dave Chinner
2018-04-21 12:54 ` Jan Kara
2018-04-24 17:34 ` Christoph Hellwig [this message]
2018-04-24 22:07 ` Holger Hoffstätte
2018-04-25 5:20 ` Christoph Hellwig
2018-04-25 13:02 ` Jan Kara
2018-05-02 2:34 ` Dave Chinner
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