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Commit 4f8ff44b authored by Dave Chinner's avatar Dave Chinner Committed by Darrick J. Wong
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iomap: iomap_dio_rw() handles all sync writes 



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: default avatarDave Chinner <dchinner@redhat.com>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
parent ed5c3e66

fs/iomap.c

+15 −6
Original line number Diff line number Diff line
@@ -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);
@@ -769,13 +777,8 @@ 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);

	iocb->ki_complete(iocb, iomap_dio_complete(dio), 0);

}



/*
@@ -961,6 +964,10 @@ 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 +1013,8 @@ 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;

	}

fs/xfs/xfs_file.c

+0 −5
Original line number Diff line number Diff line
@@ -568,11 +568,6 @@ 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;

}