From: Jan Kara <jack@suse.cz>
To: Dave Chinner <david@fromorbit.com>
Cc: 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: Sat, 21 Apr 2018 14:54:05 +0200 [thread overview]
Message-ID: <20180421125405.hyx3bbkohdgvducq@quack2.suse.cz> (raw)
In-Reply-To: <20180418040828.18165-5-david@fromorbit.com>
On Wed 18-04-18 14:08:28, Dave Chinner wrote:
> @@ -1012,8 +1035,16 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
> dio->flags |= IOMAP_DIO_DIRTY;
> } else {
> dio->flags |= IOMAP_DIO_WRITE;
> - 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.
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2018-04-21 23:19 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 [this message]
2018-04-24 17:34 ` Christoph Hellwig
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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