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From: Dave Chinner <david@fromorbit.com>
To: linux-xfs@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org,
	hch@lst.de, rdorr@microsoft.com
Subject: [PATCH 2/4] iomap: iomap_dio_rw() handles all sync writes
Date: Wed, 18 Apr 2018 14:08:26 +1000	[thread overview]
Message-ID: <20180418040828.18165-3-david@fromorbit.com> (raw)
In-Reply-To: <20180418040828.18165-1-david@fromorbit.com>

From: Dave Chinner <dchinner@redhat.com>

Currently iomap_dio_rw() only handles (data)sync write completions
for AIO. This means we can't optimised non-AIO IO to minimise device
flushes as we can't tell the caller whether a flush is required or
not.

To solve this problem and enable further optimisations, make
iomap_dio_rw responsible for data sync behaviour for all IO, not
just AIO.

In doing so, the sync operation is now accounted as part of the DIO
IO by inode_dio_end(), hence post-IO data stability updates will no
long race against operations that serialise via inode_dio_wait()
such as truncate or hole punch.

Signed-Off-By: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 fs/iomap.c        | 22 +++++++++++++++-------
 fs/xfs/xfs_file.c |  5 -----
 2 files changed, 15 insertions(+), 12 deletions(-)

diff --git a/fs/iomap.c b/fs/iomap.c
index afd163586aa0..1f59c2d9ade6 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -685,6 +685,7 @@ EXPORT_SYMBOL_GPL(iomap_seek_data);
  * Private flags for iomap_dio, must not overlap with the public ones in
  * iomap.h:
  */
+#define IOMAP_DIO_NEED_SYNC	(1 << 29)
 #define IOMAP_DIO_WRITE		(1 << 30)
 #define IOMAP_DIO_DIRTY		(1 << 31)
 
@@ -759,6 +760,13 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio)
 			dio_warn_stale_pagecache(iocb->ki_filp);
 	}
 
+	/*
+	 * If this is a DSYNC write, make sure we push it to stable storage now
+	 * that we've written data.
+	 */
+	if (ret > 0 && (dio->flags & IOMAP_DIO_NEED_SYNC))
+		ret = generic_write_sync(iocb, ret);
+
 	inode_dio_end(file_inode(iocb->ki_filp));
 	kfree(dio);
 
@@ -768,14 +776,8 @@ static ssize_t iomap_dio_complete(struct iomap_dio *dio)
 static void iomap_dio_complete_work(struct work_struct *work)
 {
 	struct iomap_dio *dio = container_of(work, struct iomap_dio, aio.work);
-	struct kiocb *iocb = dio->iocb;
-	bool is_write = (dio->flags & IOMAP_DIO_WRITE);
-	ssize_t ret;
 
-	ret = iomap_dio_complete(dio);
-	if (is_write && ret > 0)
-		ret = generic_write_sync(iocb, ret);
-	iocb->ki_complete(iocb, ret, 0);
+	dio->iocb->ki_complete(dio->iocb, iomap_dio_complete(dio), 0);
 }
 
 /*
@@ -961,6 +963,10 @@ iomap_dio_actor(struct inode *inode, loff_t pos, loff_t length,
 	return copied;
 }
 
+/*
+ * iomap_dio_rw() always completes O_[D]SYNC writes regardless of whether the IO
+ * is being issued as AIO or not.
+ */
 ssize_t
 iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, iomap_dio_end_io_t end_io)
@@ -1006,6 +1012,8 @@ 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)
+			dio->flags |= IOMAP_DIO_NEED_SYNC;
 		flags |= IOMAP_WRITE;
 	}
 
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 6f15027661b6..0c4b8313d544 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -570,11 +570,6 @@ xfs_file_dio_aio_write(
 	 * complete fully or fail.
 	 */
 	ASSERT(ret < 0 || ret == count);
-
-	if (ret > 0) {
-		/* Handle various SYNC-type writes */
-		ret = generic_write_sync(iocb, ret);
-	}
 	return ret;
 }
 
-- 
2.16.1

  parent reply	other threads:[~2018-04-18  4:11 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 ` Dave Chinner [this message]
2018-04-21 13:03   ` [PATCH 2/4] iomap: iomap_dio_rw() handles all sync writes 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
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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