[PATCH 0/17] Make O_SYNC handling use standard syncing path (Version 2)

[PATCH 0/17] Make O_SYNC handling use standard syncing path (Version 2)

[Jan Kara]

   Hi,

  first, sorry for a few patches sent before this one - I forgot to give
--compose to git send-email and there was a bug in the third patch.
  This is the second version of my patch set improving O_SYNC implementation.
The changes against previous version are small. Most notably
generic_file_aio_write() now triggers fsync() even when it returns EIOCBQUEUED
so that we behave the same way as generic_file_direct_write() did. I've
added patch renaming generic_file_aio_write_nolock() to device_aio_write()
(since it's used by fs/block_dev.c and drivers/char/raw.c). And finally
I've optimized XFS syncing as Christoph has suggested.
  Any comments welcome and BTW I'd be happy if affected fs maintainers
had a look at those patches so that I can add their ack.
									Honza
---
  Here's some rationale for the patch set:
The patch set unifines O_SYNC handling with standard fsync() path.  After this,
we have just one place forcing a single file to disk so filesystems like ext3 /
ext4 don't have to force a transaction commit in ext?_file_write for O_SYNC
files / IS_SYNC inodes.  The code is also cleaner this way (actually about 150
lines shorter), we don't sync the inode several times as it happened previously
etc.

[PATCH 01/17] vfs: Introduce filemap_fdatawait_range

[Jan Kara]

This simple helper saves some filesystems conversion from byte offset
to page numbers and also makes the fdata* interface more complete.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 include/linux/fs.h |    2 ++
 mm/filemap.c       |   20 ++++++++++++++++++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 67888a9..cb365ad 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2076,6 +2076,8 @@ extern int write_inode_now(struct inode *, int);
 extern int filemap_fdatawrite(struct address_space *);
 extern int filemap_flush(struct address_space *);
 extern int filemap_fdatawait(struct address_space *);
+extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
+				   loff_t lend);
 extern int filemap_write_and_wait(struct address_space *mapping);
 extern int filemap_write_and_wait_range(struct address_space *mapping,
 				        loff_t lstart, loff_t lend);
diff --git a/mm/filemap.c b/mm/filemap.c
index ccea3b6..65b2e50 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -307,6 +307,26 @@ int wait_on_page_writeback_range(struct address_space *mapping,
 }
 
 /**
+ * filemap_fdatawait_range - wait for all under-writeback pages to complete in a given range
+ * @mapping: address space structure to wait for
+ * @start:	offset in bytes where the range starts
+ * @end:	offset in bytes where the range ends (inclusive)
+ *
+ * Walk the list of under-writeback pages of the given address space
+ * in the given range and wait for all of them.
+ *
+ * This is just a simple wrapper so that callers don't have to convert offsets
+ * to page indexes themselves
+ */
+int filemap_fdatawait_range(struct address_space *mapping, loff_t start,
+			    loff_t end)
+{
+	return wait_on_page_writeback_range(mapping, start >> PAGE_CACHE_SHIFT,
+					    end >> PAGE_CACHE_SHIFT);
+}
+EXPORT_SYMBOL(filemap_fdatawait_range);
+
+/**
  * sync_page_range - write and wait on all pages in the passed range
  * @inode:	target inode
  * @mapping:	target address_space
-- 
1.6.0.2

[PATCH 02/17] vfs: Export __generic_file_aio_write() and add some comments

[Jan Kara]

Rename __generic_file_aio_write_nolock() to __generic_file_aio_write(), add
comments to write helpers explaining how they should be used and export
__generic_file_aio_write() since it will be used by some filesystems.

CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 include/linux/fs.h |    2 +
 mm/filemap.c       |   57 +++++++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 52 insertions(+), 7 deletions(-)

diff --git a/include/linux/fs.h b/include/linux/fs.h
index cb365ad..1edd159 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2195,6 +2195,8 @@ extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
 extern int file_read_actor(read_descriptor_t * desc, struct page *page, unsigned long offset, unsigned long size);
 int generic_write_checks(struct file *file, loff_t *pos, size_t *count, int isblk);
 extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsigned long, loff_t);
+extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long,
+		loff_t *);
 extern ssize_t generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long, loff_t);
 extern ssize_t generic_file_aio_write_nolock(struct kiocb *, const struct iovec *,
 		unsigned long, loff_t);
diff --git a/mm/filemap.c b/mm/filemap.c
index 65b2e50..554a396 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2368,9 +2368,27 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
 }
 EXPORT_SYMBOL(generic_file_buffered_write);
 
-static ssize_t
-__generic_file_aio_write_nolock(struct kiocb *iocb, const struct iovec *iov,
-				unsigned long nr_segs, loff_t *ppos)
+/**
+ * __generic_file_aio_write - write data to a file
+ * @iocb:	IO state structure (file, offset, etc.)
+ * @iov:	vector with data to write
+ * @nr_segs:	number of segments in the vector
+ * @ppos:	position where to write
+ *
+ * This function does all the work needed for actually writing data to a
+ * file. It does all basic checks, removes SUID from the file, updates
+ * modification times and calls proper subroutines depending on whether we
+ * do direct IO or a standard buffered write.
+ *
+ * It expects i_mutex to be grabbed unless we work on a block device or similar
+ * object which does not need locking at all.
+ *
+ * This function does *not* take care of syncing data in case of O_SYNC write.
+ * A caller has to handle it. This is mainly due to the fact that we want to
+ * avoid syncing under i_mutex.
+ */
+ssize_t __generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
+				 unsigned long nr_segs, loff_t *ppos)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space * mapping = file->f_mapping;
@@ -2467,7 +2485,23 @@ out:
 	current->backing_dev_info = NULL;
 	return written ? written : err;
 }
+EXPORT_SYMBOL(__generic_file_aio_write);
+
 
+/**
+ * generic_file_aio_write_nolock - write data, usually to a device
+ * @iocb:	IO state structure
+ * @iov:	vector with data to write
+ * @nr_segs:	number of segments in the vector
+ * @pos:	position in file where to write
+ *
+ * This is a wrapper around __generic_file_aio_write() which takes care of
+ * syncing the file in case of O_SYNC file. It does not take i_mutex for the
+ * write itself but may do so during syncing. It is meant for users like block
+ * devices which do not need i_mutex during write. If your filesystem needs to
+ * do a write but already holds i_mutex, use __generic_file_aio_write()
+ * directly and then sync the file like generic_file_aio_write().
+ */
 ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
 		const struct iovec *iov, unsigned long nr_segs, loff_t pos)
 {
@@ -2478,8 +2512,7 @@ ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
 
 	BUG_ON(iocb->ki_pos != pos);
 
-	ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
-			&iocb->ki_pos);
+	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 
 	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
 		ssize_t err;
@@ -2492,6 +2525,17 @@ ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
 }
 EXPORT_SYMBOL(generic_file_aio_write_nolock);
 
+/**
+ * generic_file_aio_write - write data to a file
+ * @iocb:	IO state structure
+ * @iov:	vector with data to write
+ * @nr_segs:	number of segments in the vector
+ * @pos:	position in file where to write
+ *
+ * This is a wrapper around __generic_file_aio_write() to be used by most
+ * filesystems. It takes care of syncing the file in case of O_SYNC file
+ * and acquires i_mutex as needed.
+ */
 ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		unsigned long nr_segs, loff_t pos)
 {
@@ -2503,8 +2547,7 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	BUG_ON(iocb->ki_pos != pos);
 
 	mutex_lock(&inode->i_mutex);
-	ret = __generic_file_aio_write_nolock(iocb, iov, nr_segs,
-			&iocb->ki_pos);
+	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
 
 	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-- 
1.6.0.2

[PATCH 03/17] vfs: Remove syncing from generic_file_direct_write() and generic_file_buffered_write()

[Jan Kara]

generic_file_direct_write() and generic_file_buffered_write() called
generic_osync_inode() if it was called on O_SYNC file or IS_SYNC inode. But
this is superfluous since generic_file_aio_write() does the syncing as well.
Also XFS and OCFS2 which call these functions directly handle syncing
themselves. So let's have a single place where syncing happens:
generic_file_aio_write().

We slightly change the behavior by syncing only the range of file to which the
write happened for buffered writes but that should be all that is required.

CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
Signed-off-by: Jan Kara <jack@suse.cz>
---
 mm/filemap.c |   35 ++++++-----------------------------
 1 files changed, 6 insertions(+), 29 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 554a396..f863e1d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2187,20 +2187,7 @@ generic_file_direct_write(struct kiocb *iocb, const struct iovec *iov,
 		}
 		*ppos = end;
 	}
-
-	/*
-	 * Sync the fs metadata but not the minor inode changes and
-	 * of course not the data as we did direct DMA for the IO.
-	 * i_mutex is held, which protects generic_osync_inode() from
-	 * livelocking.  AIO O_DIRECT ops attempt to sync metadata here.
-	 */
 out:
-	if ((written >= 0 || written == -EIOCBQUEUED) &&
-	    ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-		int err = generic_osync_inode(inode, mapping, OSYNC_METADATA);
-		if (err < 0)
-			written = err;
-	}
 	return written;
 }
 EXPORT_SYMBOL(generic_file_direct_write);
@@ -2332,8 +2319,6 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
-	const struct address_space_operations *a_ops = mapping->a_ops;
-	struct inode *inode = mapping->host;
 	ssize_t status;
 	struct iov_iter i;
 
@@ -2343,16 +2328,6 @@ generic_file_buffered_write(struct kiocb *iocb, const struct iovec *iov,
 	if (likely(status >= 0)) {
 		written += status;
 		*ppos = pos + status;
-
-		/*
-		 * For now, when the user asks for O_SYNC, we'll actually give
-		 * O_DSYNC
-		 */
-		if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-			if (!a_ops->writepage || !is_sync_kiocb(iocb))
-				status = generic_osync_inode(inode, mapping,
-						OSYNC_METADATA|OSYNC_DATA);
-		}
   	}
 	
 	/*
@@ -2514,11 +2489,12 @@ ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
 
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 
-	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+	if ((ret > 0 || ret == -EIOCBQUEUED) &&
+	    ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
 		ssize_t err;
 
 		err = sync_page_range_nolock(inode, mapping, pos, ret);
-		if (err < 0)
+		if (err < 0 && ret > 0)
 			ret = err;
 	}
 	return ret;
@@ -2550,11 +2526,12 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
 
-	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+	if ((ret > 0 || ret == -EIOCBQUEUED) &&
+	    ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
 		ssize_t err;
 
 		err = sync_page_range(inode, mapping, pos, ret);
-		if (err < 0)
+		if (err < 0 && ret > 0)
 			ret = err;
 	}
 	return ret;
-- 
1.6.0.2

[PATCH 04/17] pohmelfs: Use __generic_file_aio_write instead of generic_file_aio_write_nolock

[Jan Kara]

Use new helper __generic_file_aio_write(). Since the fs takes care of syncing
by itself afterwards, there are no more changes needed.

CC: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/staging/pohmelfs/inode.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/staging/pohmelfs/inode.c b/drivers/staging/pohmelfs/inode.c
index 7b60579..17801a5 100644
--- a/drivers/staging/pohmelfs/inode.c
+++ b/drivers/staging/pohmelfs/inode.c
@@ -921,7 +921,7 @@ ssize_t pohmelfs_write(struct file *file, const char __user *buf,
 	if (ret)
 		goto err_out_unlock;
 
-	ret = generic_file_aio_write_nolock(&kiocb, &iov, 1, pos);
+	ret = __generic_file_aio_write(&kiocb, &iov, 1, &kiocb.ki_pos);
 	*ppos = kiocb.ki_pos;
 
 	mutex_unlock(&inode->i_mutex);
-- 
1.6.0.2

[PATCH 05/17] ocfs2: Use __generic_file_aio_write instead of generic_file_aio_write_nolock

[Jan Kara]

Use the new helper. We have to submit data pages ourselves in case of O_SYNC
write because __generic_file_aio_write does not do it for us. OCFS2 developpers
might think about moving the sync out of i_mutex which seems to be easily
possible but that's out of scope of this patch.

CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/file.c |   22 ++++++++++++----------
 1 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 62442e4..1c71f0a 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1870,8 +1870,7 @@ relock:
 			goto out_dio;
 		}
 	} else {
-		written = generic_file_aio_write_nolock(iocb, iov, nr_segs,
-							*ppos);
+		written = __generic_file_aio_write(iocb, iov, nr_segs, ppos);
 	}
 
 out_dio:
@@ -1879,18 +1878,21 @@ out_dio:
 	BUG_ON(ret == -EIOCBQUEUED && !(file->f_flags & O_DIRECT));
 
 	if ((file->f_flags & O_SYNC && !direct_io) || IS_SYNC(inode)) {
-		/*
-		 * The generic write paths have handled getting data
-		 * to disk, but since we don't make use of the dirty
-		 * inode list, a manual journal commit is necessary
-		 * here.
-		 */
-		if (old_size != i_size_read(inode) ||
-		    old_clusters != OCFS2_I(inode)->ip_clusters) {
+		ret = filemap_fdatawrite_range(file->f_mapping, pos,
+					       pos + count - 1);
+		if (ret < 0)
+			written = ret;
+
+		if (!ret && (old_size != i_size_read(inode) ||
+		    old_clusters != OCFS2_I(inode)->ip_clusters)) {
 			ret = jbd2_journal_force_commit(osb->journal->j_journal);
 			if (ret < 0)
 				written = ret;
 		}
+
+		if (!ret)
+			ret = filemap_fdatawait_range(file->f_mapping, pos,
+						      pos + count - 1);
 	}
 
 	/* 
-- 
1.6.0.2

Re: [PATCH 05/17] ocfs2: Use __generic_file_aio_write instead of generic_file_aio_write_nolock

[Joel Becker]

On Fri, Aug 21, 2009 at 07:23:55PM +0200, Jan Kara wrote:
> Use the new helper. We have to submit data pages ourselves in case of O_SYNC
> write because __generic_file_aio_write does not do it for us. OCFS2 developpers
> might think about moving the sync out of i_mutex which seems to be easily
> possible but that's out of scope of this patch.
> 
> CC: ocfs2-devel@oss.oracle.com
> CC: Joel Becker <joel.becker@oracle.com>
> Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Joel Becker <joel.becker@oracle.com>
 

-- 

"The real reason GNU ls is 8-bit-clean is so that they can
 start using ISO-8859-1 option characters."
	- Christopher Davis (ckd@loiosh.kei.com)

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127

[PATCH 06/17] vfs: Rename generic_file_aio_write_nolock

[Jan Kara]

generic_file_aio_write_nolock() is now used only by block devices and raw
character device. Filesystems should use __generic_file_aio_write() in case
generic_file_aio_write() doesn't suit them. So rename the function to
device_aio_write().

Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/char/raw.c |    2 +-
 fs/block_dev.c     |    2 +-
 include/linux/fs.h |    4 ++--
 mm/filemap.c       |    9 ++++-----
 4 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/char/raw.c b/drivers/char/raw.c
index 05f9d18..c43c7a7 100644
--- a/drivers/char/raw.c
+++ b/drivers/char/raw.c
@@ -246,7 +246,7 @@ static const struct file_operations raw_fops = {
 	.read	=	do_sync_read,
 	.aio_read = 	generic_file_aio_read,
 	.write	=	do_sync_write,
-	.aio_write = 	generic_file_aio_write_nolock,
+	.aio_write =	device_aio_write,
 	.open	=	raw_open,
 	.release=	raw_release,
 	.ioctl	=	raw_ioctl,
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 94dfda2..67fc1c9 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -1436,7 +1436,7 @@ const struct file_operations def_blk_fops = {
 	.read		= do_sync_read,
 	.write		= do_sync_write,
   	.aio_read	= generic_file_aio_read,
-  	.aio_write	= generic_file_aio_write_nolock,
+	.aio_write	= device_aio_write,
 	.mmap		= generic_file_mmap,
 	.fsync		= block_fsync,
 	.unlocked_ioctl	= block_ioctl,
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 1edd159..29fc8da 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2198,8 +2198,8 @@ extern ssize_t generic_file_aio_read(struct kiocb *, const struct iovec *, unsig
 extern ssize_t __generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long,
 		loff_t *);
 extern ssize_t generic_file_aio_write(struct kiocb *, const struct iovec *, unsigned long, loff_t);
-extern ssize_t generic_file_aio_write_nolock(struct kiocb *, const struct iovec *,
-		unsigned long, loff_t);
+extern ssize_t device_aio_write(struct kiocb *iocb, const struct iovec *iov,
+				unsigned long nr_segs, loff_t pos);
 extern ssize_t generic_file_direct_write(struct kiocb *, const struct iovec *,
 		unsigned long *, loff_t, loff_t *, size_t, size_t);
 extern ssize_t generic_file_buffered_write(struct kiocb *, const struct iovec *,
diff --git a/mm/filemap.c b/mm/filemap.c
index f863e1d..3955f7e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -2462,9 +2462,8 @@ out:
 }
 EXPORT_SYMBOL(__generic_file_aio_write);
 
-
 /**
- * generic_file_aio_write_nolock - write data, usually to a device
+ * device_aio_write - write data
  * @iocb:	IO state structure
  * @iov:	vector with data to write
  * @nr_segs:	number of segments in the vector
@@ -2477,8 +2476,8 @@ EXPORT_SYMBOL(__generic_file_aio_write);
  * do a write but already holds i_mutex, use __generic_file_aio_write()
  * directly and then sync the file like generic_file_aio_write().
  */
-ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
-		const struct iovec *iov, unsigned long nr_segs, loff_t pos)
+ssize_t device_aio_write(struct kiocb *iocb, const struct iovec *iov,
+			 unsigned long nr_segs, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
 	struct address_space *mapping = file->f_mapping;
@@ -2499,7 +2498,7 @@ ssize_t generic_file_aio_write_nolock(struct kiocb *iocb,
 	}
 	return ret;
 }
-EXPORT_SYMBOL(generic_file_aio_write_nolock);
+EXPORT_SYMBOL(device_aio_write);
 
 /**
  * generic_file_aio_write - write data to a file
-- 
1.6.0.2

Re: [PATCH 06/17] vfs: Rename generic_file_aio_write_nolock

[Christoph Hellwig]

On Fri, Aug 21, 2009 at 07:23:56PM +0200, Jan Kara wrote:
> generic_file_aio_write_nolock() is now used only by block devices and raw
> character device. Filesystems should use __generic_file_aio_write() in case
> generic_file_aio_write() doesn't suit them. So rename the function to
> device_aio_write().

This might turn into nitpicking, but it's really only useful for
writing to block devices.  Raw isn't a real character interface but
basically a convuled way to open a block device using O_DIRECT.

So I would recommend to renamed it to blkdev_aio_write, move it to
fs/block_dev.c and stop exporting it.

Re: [PATCH 06/17] vfs: Rename generic_file_aio_write_nolock

[Jan Kara]

On Fri 21-08-09 19:30:34, Christoph Hellwig wrote:
> On Fri, Aug 21, 2009 at 07:23:56PM +0200, Jan Kara wrote:
> > generic_file_aio_write_nolock() is now used only by block devices and raw
> > character device. Filesystems should use __generic_file_aio_write() in case
> > generic_file_aio_write() doesn't suit them. So rename the function to
> > device_aio_write().
> 
> This might turn into nitpicking, but it's really only useful for
> writing to block devices.  Raw isn't a real character interface but
> basically a convuled way to open a block device using O_DIRECT.
> 
> So I would recommend to renamed it to blkdev_aio_write, move it to
> fs/block_dev.c and stop exporting it.
  But what should 'raw' use then? It can be compiled as a module so it
needs to call something that's exported.

									Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: [PATCH 06/17] vfs: Rename generic_file_aio_write_nolock

[Christoph Hellwig]

On Fri, Aug 21, 2009 at 07:56:17PM +0200, Jan Kara wrote:
> On Fri 21-08-09 19:30:34, Christoph Hellwig wrote:
> > On Fri, Aug 21, 2009 at 07:23:56PM +0200, Jan Kara wrote:
> > > generic_file_aio_write_nolock() is now used only by block devices and raw
> > > character device. Filesystems should use __generic_file_aio_write() in case
> > > generic_file_aio_write() doesn't suit them. So rename the function to
> > > device_aio_write().
> > 
> > This might turn into nitpicking, but it's really only useful for
> > writing to block devices.  Raw isn't a real character interface but
> > basically a convuled way to open a block device using O_DIRECT.
> > 
> > So I would recommend to renamed it to blkdev_aio_write, move it to
> > fs/block_dev.c and stop exporting it.
>   But what should 'raw' use then? It can be compiled as a module so it
> needs to call something that's exported.

Oh, ouch - I didn't think that we would allow it to be modular.  We need
to keep exporting it then.  Hopefully the name change keeps people from
using it in filesystems.

[PATCH 07/17] vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode

[Jan Kara]

Introduce new function for generic inode syncing (generic_sync_file) and use
it from fsync() path. Introduce also new helper for syncing after a sync
write (generic_write_sync) using the generic function.

Use these new helpers for syncing from generic VFS functions. This makes
O_SYNC writes to block devices acquire i_mutex for syncing. If we really
care about this, we can make block_fsync() drop the i_mutex and reacquire
it before it returns.

CC: Evgeniy Polyakov <zbr@ioremap.net>
CC: ocfs2-devel@oss.oracle.com
CC: Joel Becker <joel.becker@oracle.com>
CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
CC: Anton Altaparmakov <aia21@cantab.net>
CC: linux-ntfs-dev@lists.sourceforge.net
CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
CC: linux-ext4@vger.kernel.org
CC: tytso@mit.edu
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/splice.c        |   22 ++++----------
 fs/sync.c          |   81 +++++++++++++++++++++++++++++++++++++++++++---------
 include/linux/fs.h |    7 ++++
 mm/filemap.c       |   18 ++++--------
 4 files changed, 86 insertions(+), 42 deletions(-)

diff --git a/fs/splice.c b/fs/splice.c
index 73766d2..8190237 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -976,25 +976,15 @@ generic_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
 
 	if (ret > 0) {
 		unsigned long nr_pages;
+		int err;
 
-		*ppos += ret;
 		nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
-		/*
-		 * If file or inode is SYNC and we actually wrote some data,
-		 * sync it.
-		 */
-		if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
-			int err;
-
-			mutex_lock(&inode->i_mutex);
-			err = generic_osync_inode(inode, mapping,
-						  OSYNC_METADATA|OSYNC_DATA);
-			mutex_unlock(&inode->i_mutex);
-
-			if (err)
-				ret = err;
-		}
+		err = generic_write_sync(out, *ppos, ret);
+		if (err)
+			ret = err;
+		else
+			*ppos += ret;
 		balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
 	}
 
diff --git a/fs/sync.c b/fs/sync.c
index 3422ba6..fc320aa 100644
--- a/fs/sync.c
+++ b/fs/sync.c
@@ -176,23 +176,30 @@ int file_fsync(struct file *filp, struct dentry *dentry, int datasync)
 }
 
 /**
- * vfs_fsync - perform a fsync or fdatasync on a file
+ * generic_sync_file - helper to sync data & metadata to disk
  * @file:		file to sync
  * @dentry:		dentry of @file
- * @data:		only perform a fdatasync operation
+ * @start:		offset in bytes of the beginning of data range to sync
+ * @end:		offset in bytes of the end of data range (inclusive)
+ * @what:		what should be synced
  *
- * Write back data and metadata for @file to disk.  If @datasync is
- * set only metadata needed to access modified file data is written.
+ * What the function exactly does is controlled by the @what parameter:
  *
- * In case this function is called from nfsd @file may be %NULL and
- * only @dentry is set.  This can only happen when the filesystem
- * implements the export_operations API.
+ * If SYNC_SUBMIT_DATA is set, the function submits all pages in the given
+ * range to disk.
+ *
+ * The function always calls ->fsync() callback of the filesystem. If
+ * SYNC_INODE is not set, we pass down the fact that it is just a datasync.
+ *
+ * If SYNC_WAIT_DATA is set, the function waits for writeback to finish
+ * in the given range.
  */
-int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+int generic_sync_file(struct file *file, struct dentry *dentry, loff_t start,
+		      loff_t end, int what)
 {
 	const struct file_operations *fop;
 	struct address_space *mapping;
-	int err, ret;
+	int err, ret = 0;
 
 	/*
 	 * Get mapping and operations from the file in case we have
@@ -212,23 +219,50 @@ int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
 		goto out;
 	}
 
-	ret = filemap_fdatawrite(mapping);
+	if (what & SYNC_SUBMIT_DATA)
+		ret = filemap_fdatawrite_range(mapping, start, end);
 
 	/*
 	 * We need to protect against concurrent writers, which could cause
 	 * livelocks in fsync_buffers_list().
 	 */
 	mutex_lock(&mapping->host->i_mutex);
-	err = fop->fsync(file, dentry, datasync);
+	err = fop->fsync(file, dentry, !(what & SYNC_INODE));
 	if (!ret)
 		ret = err;
 	mutex_unlock(&mapping->host->i_mutex);
-	err = filemap_fdatawait(mapping);
-	if (!ret)
-		ret = err;
+
+	if (what & SYNC_WAIT_DATA) {
+		err = filemap_fdatawait_range(mapping, start, end);
+		if (!ret)
+			ret = err;
+	}
 out:
 	return ret;
 }
+EXPORT_SYMBOL(generic_sync_file);
+
+/**
+ * vfs_fsync - perform a fsync or fdatasync on a file
+ * @file:		file to sync
+ * @dentry:		dentry of @file
+ * @datasync:		only perform a fdatasync operation
+ *
+ * Write back data and metadata for @file to disk.  If @datasync is
+ * set only metadata needed to access modified file data is written.
+ *
+ * In case this function is called from nfsd @file may be %NULL and
+ * only @dentry is set.  This can only happen when the filesystem
+ * implements the export_operations API.
+ */
+int vfs_fsync(struct file *file, struct dentry *dentry, int datasync)
+{
+	int what = SYNC_SUBMIT_DATA | SYNC_WAIT_DATA;
+
+	if (!datasync)
+		what |= SYNC_INODE;
+	return generic_sync_file(file, dentry, 0, LLONG_MAX, what);
+}
 EXPORT_SYMBOL(vfs_fsync);
 
 static int do_fsync(unsigned int fd, int datasync)
@@ -254,6 +288,25 @@ SYSCALL_DEFINE1(fdatasync, unsigned int, fd)
 	return do_fsync(fd, 1);
 }
 
+/**
+ * generic_write_sync - perform syncing after a write if file / inode is sync
+ * @file:	file to which the write happened
+ * @pos:	offset where the write started
+ * @count:	length of the write
+ *
+ * This is just a simple wrapper about our general syncing function.
+ * FIXME: Make it inline?
+ */
+int generic_write_sync(struct file *file, loff_t pos, loff_t count)
+{
+	if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host))
+		return 0;
+	return generic_sync_file(file, file->f_path.dentry, pos,
+				 pos + count - 1,
+				 SYNC_SUBMIT_DATA | SYNC_WAIT_DATA);
+}
+EXPORT_SYMBOL(generic_write_sync);
+
 /*
  * sys_sync_file_range() permits finely controlled syncing over a segment of
  * a file in the range offset .. (offset+nbytes-1) inclusive.  If nbytes is
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 29fc8da..648001c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2088,7 +2088,14 @@ extern int __filemap_fdatawrite_range(struct address_space *mapping,
 extern int filemap_fdatawrite_range(struct address_space *mapping,
 				loff_t start, loff_t end);
 
+/* Flags for generic_sync_file */
+#define SYNC_INODE		1
+#define SYNC_SUBMIT_DATA	2
+#define SYNC_WAIT_DATA		4
+extern int generic_sync_file(struct file *file, struct dentry *dentry,
+			   loff_t start, loff_t end, int what);
 extern int vfs_fsync(struct file *file, struct dentry *dentry, int datasync);
+extern int generic_write_sync(struct file *file, loff_t pos, loff_t count);
 extern void sync_supers(void);
 extern void emergency_sync(void);
 extern void emergency_remount(void);
diff --git a/mm/filemap.c b/mm/filemap.c
index 3955f7e..70988a1 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -39,11 +39,10 @@
 /*
  * FIXME: remove all knowledge of the buffer layer from the core VM
  */
-#include <linux/buffer_head.h> /* for generic_osync_inode */
+#include <linux/buffer_head.h> /* for try_to_free_buffers */
 
 #include <asm/mman.h>
 
-
 /*
  * Shared mappings implemented 30.11.1994. It's not fully working yet,
  * though.
@@ -2480,19 +2479,16 @@ ssize_t device_aio_write(struct kiocb *iocb, const struct iovec *iov,
 			 unsigned long nr_segs, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
-	struct address_space *mapping = file->f_mapping;
-	struct inode *inode = mapping->host;
 	ssize_t ret;
 
 	BUG_ON(iocb->ki_pos != pos);
 
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 
-	if ((ret > 0 || ret == -EIOCBQUEUED) &&
-	    ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+	if (ret > 0 || ret == -EIOCBQUEUED) {
 		ssize_t err;
 
-		err = sync_page_range_nolock(inode, mapping, pos, ret);
+		err = generic_write_sync(file, pos, ret);
 		if (err < 0 && ret > 0)
 			ret = err;
 	}
@@ -2515,8 +2511,7 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 		unsigned long nr_segs, loff_t pos)
 {
 	struct file *file = iocb->ki_filp;
-	struct address_space *mapping = file->f_mapping;
-	struct inode *inode = mapping->host;
+	struct inode *inode = file->f_mapping->host;
 	ssize_t ret;
 
 	BUG_ON(iocb->ki_pos != pos);
@@ -2525,11 +2520,10 @@ ssize_t generic_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	ret = __generic_file_aio_write(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
 
-	if ((ret > 0 || ret == -EIOCBQUEUED) &&
-	    ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+	if (ret > 0 || ret == -EIOCBQUEUED) {
 		ssize_t err;
 
-		err = sync_page_range(inode, mapping, pos, ret);
+		err = generic_write_sync(file, pos, ret);
 		if (err < 0 && ret > 0)
 			ret = err;
 	}
-- 
1.6.0.2

Re: [PATCH 07/17] vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode

[Christoph Hellwig]

> +int generic_write_sync(struct file *file, loff_t pos, loff_t count)
> +{
> +	if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host))
> +		return 0;
> +	return generic_sync_file(file, file->f_path.dentry, pos,
> +				 pos + count - 1,
> +				 SYNC_SUBMIT_DATA | SYNC_WAIT_DATA);
> +}
> +EXPORT_SYMBOL(generic_write_sync);

>  
> +/* Flags for generic_sync_file */
> +#define SYNC_INODE		1
> +#define SYNC_SUBMIT_DATA	2
> +#define SYNC_WAIT_DATA		4

When I think about this more I really hate the latter two flags.
There's really no reason to just do only either the submit or wait.
I'd say kill the flags for now and just implement generic_write_sync
as:

int generic_write_sync(struct file *file, loff_t pos, loff_t count)
{
	if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host))
		return 0;
	return vfs_fsync_range(file, file->f_path.dentry, pos,
			       pos + count - 1, 1);
}

and we can look into replacing the datasync flag with something more
meaningfull later through the whole fsync stack.

Re: [PATCH 07/17] vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode

[Jamie Lokier]

Christoph Hellwig wrote:
> int generic_write_sync(struct file *file, loff_t pos, loff_t count)
> {
> 	if (!(file->f_flags & O_SYNC) && !IS_SYNC(file->f_mapping->host))
> 		return 0;
> 	return vfs_fsync_range(file, file->f_path.dentry, pos,
> 			       pos + count - 1, 1);
> }
> 
> and we can look into replacing the datasync flag with something more
> meaningfull later through the whole fsync stack.

I like that.  It looks really clear and self-documenting, if
vfs_fsync_range does what it sounds like, which is a nice change.

If I've guessed right what that code does, proper O_RSYNC will be easy:

int generic_sync_before_read(struct file *file, loff_t pos, loff_t count)
{
	int is_sync = ((file->f_flags & O_SYNC)
		       || IS_SYNC(file->f_mapping->host));
	int is_dsync = is_sync || (file->f_flags & O_DSYNC);

	if (!is_dsync || !(file->f_flags & O_RSYNC))
		return 0;
	return vfs_fsync_range(file, file->f_ath.denty, pos,
			       pos + count - 1, is_sync);
}

(By the way, did I mention Irix has range-fsync and range-fdatasync
system calls too :-) (actually fcntls))

-- Jamie

Re: [PATCH 07/17] vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode

[Christoph Hellwig]

On Sun, Aug 30, 2009 at 05:35:51PM +0100, Jamie Lokier wrote:
> I like that.  It looks really clear and self-documenting, if
> vfs_fsync_range does what it sounds like, which is a nice change.
> 
> If I've guessed right what that code does, proper O_RSYNC will be easy:
> 
> int generic_sync_before_read(struct file *file, loff_t pos, loff_t count)
> {
> 	int is_sync = ((file->f_flags & O_SYNC)
> 		       || IS_SYNC(file->f_mapping->host));
> 	int is_dsync = is_sync || (file->f_flags & O_DSYNC);
> 
> 	if (!is_dsync || !(file->f_flags & O_RSYNC))
> 		return 0;
> 	return vfs_fsync_range(file, file->f_ath.denty, pos,
> 			       pos + count - 1, is_sync);
> }

Yes. something like this.

> (By the way, did I mention Irix has range-fsync and range-fdatasync
> system calls too :-) (actually fcntls))

Linux has sync_file_range which currently is a perfect way to lose your
synced' data, but with two more flags and calls to ->fsync we could
turn it into range-fsync/fdatasync.  I'm not sure if that's a good
idea or if we should just add a sys_fdatasync_rage systems call.

I don't quite see the point of a range-fsync, but it could be easily
implemented as a flag.

Re: [PATCH 07/17] vfs: Introduce new helpers for syncing after writing to O_SYNC file or IS_SYNC inode

[Jamie Lokier]

Christoph Hellwig wrote:
> Linux has sync_file_range which currently is a perfect way to lose your
> synced' data, but with two more flags and calls to ->fsync we could
> turn it into range-fsync/fdatasync.

Apart from the way it loses your data, the man page for
sync_file_range never manages to explain quite why you should use the
existing flags in various combinations.  It's only obvious if you've
worked on a kernel yourself.

Having asked this before, it appears one of the reasons for
sync_file_range working as it does is to give the application more
control over writeback order and to some extent, reduce the amount of
blocking.

But it's really difficult to manage the amount of blocking with it.
You need to know the request queue size among other things, and even
if you do it's dynamic.  Writeback order would be as easy with
fdatasync_range, and if you want to reduce blocking, a good
implementation of aio_fsync would be more useful.  Or, you have to use
application writeback threads anyway, so fdatasync_range again.

The one thing sync_file_range can do is let you submit multiple ranges
which the elevators can sort for the hardware.  You can't do that with
sequential calls to fdatasync_range, and it's not clear that aio_fsync
is implemented well enough (but it's a fairly good API for it).

Nick Piggin's idea to let fdatasync_range take multiple ranges might
help with that, but it's not clear how much.

> I'm not sure if that's a good
> idea or if we should just add a sys_fdatasync_rage systems call.

fdatasync_range has the advantage of being comprehensible.  People
will use it because it makes sense.

sync_file_range could be hijacked with new flags to implement
fdatasync_range.  If that's done, I'd rename the system call, but keep
it compatible with sync_file_range's flags, which would never be set
when userspace uses the new functionality.

> I don't quite see the point of a range-fsync, but it could be easily
> implemented as a flag.

A flags argument would be good anyway: to indicate if we want an
ordinary fdatasync, or something which flushes the relevant bit of
volatile hardware caches too.  With that as a capability, it is useful
to offer fsync, because that'd be the only way to get a volatile
hardware cache flush (or maybe the only way not to?).

For that reason, it should be permitted to give an infinitely large range.

I don't see the point of range-fsync either, but I'm not sure if I see
any harm in it.  If permitted, range-fsync with a zero-byte range
would flush just the inode state and none of the data.  If that's
technically available, maybe O_ISYNC and "#define O_SYNC
(O_DATASYNC|O_ISYNC)" isn't such as daft idea.

I'd call it fsync_range for consistency with aio_fsync (POSIX), which
takes flags O_DSYNC or O_SYNC to indicate the type of sync.  But I'd
use new flag names, to keep the space clear for other flags.  Just
sketching some ideas:

/* One of FSYNC_RANGE_SYNC or FSYNC_RANGE_DATASYNC must be set. */

#define FSYNC_RANGE_SYNC	(1 << 0)	/* Like fsync, O_SYNC. */
#define FSYNC_RANGE_DATASYNC	(1 << 1)	/* Like fdatasync, O_DSYNC. */
#define FSYNC_RANGE_NO_HWCACHE	(1 << 2)	/* Not hardware caches. */

-- Jamie

[PATCH 08/17] ext2: Update comment about generic_osync_inode

[Jan Kara]

We rely on generic_write_sync() now.

CC: linux-ext4@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext2/inode.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index e271303..1c1638f 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -482,7 +482,7 @@ static int ext2_alloc_branch(struct inode *inode,
 		unlock_buffer(bh);
 		mark_buffer_dirty_inode(bh, inode);
 		/* We used to sync bh here if IS_SYNC(inode).
-		 * But we now rely upon generic_osync_inode()
+		 * But we now rely upon generic_write_sync()
 		 * and b_inode_buffers.  But not for directories.
 		 */
 		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode))
-- 
1.6.0.2

[PATCH 09/17] ext3: Remove syncing logic from ext3_file_write

[Jan Kara]

Syncing is now properly done by generic_file_aio_write() so no special logic is
needed in ext3.

CC: linux-ext4@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext3/file.c |   61 +-------------------------------------------------------
 1 files changed, 1 insertions(+), 60 deletions(-)

diff --git a/fs/ext3/file.c b/fs/ext3/file.c
index 5b49704..51fee5f 100644
--- a/fs/ext3/file.c
+++ b/fs/ext3/file.c
@@ -51,71 +51,12 @@ static int ext3_release_file (struct inode * inode, struct file * filp)
 	return 0;
 }
 
-static ssize_t
-ext3_file_write(struct kiocb *iocb, const struct iovec *iov,
-		unsigned long nr_segs, loff_t pos)
-{
-	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_path.dentry->d_inode;
-	ssize_t ret;
-	int err;
-
-	ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
-
-	/*
-	 * Skip flushing if there was an error, or if nothing was written.
-	 */
-	if (ret <= 0)
-		return ret;
-
-	/*
-	 * If the inode is IS_SYNC, or is O_SYNC and we are doing data
-	 * journalling then we need to make sure that we force the transaction
-	 * to disk to keep all metadata uptodate synchronously.
-	 */
-	if (file->f_flags & O_SYNC) {
-		/*
-		 * If we are non-data-journaled, then the dirty data has
-		 * already been flushed to backing store by generic_osync_inode,
-		 * and the inode has been flushed too if there have been any
-		 * modifications other than mere timestamp updates.
-		 *
-		 * Open question --- do we care about flushing timestamps too
-		 * if the inode is IS_SYNC?
-		 */
-		if (!ext3_should_journal_data(inode))
-			return ret;
-
-		goto force_commit;
-	}
-
-	/*
-	 * So we know that there has been no forced data flush.  If the inode
-	 * is marked IS_SYNC, we need to force one ourselves.
-	 */
-	if (!IS_SYNC(inode))
-		return ret;
-
-	/*
-	 * Open question #2 --- should we force data to disk here too?  If we
-	 * don't, the only impact is that data=writeback filesystems won't
-	 * flush data to disk automatically on IS_SYNC, only metadata (but
-	 * historically, that is what ext2 has done.)
-	 */
-
-force_commit:
-	err = ext3_force_commit(inode->i_sb);
-	if (err)
-		return err;
-	return ret;
-}
-
 const struct file_operations ext3_file_operations = {
 	.llseek		= generic_file_llseek,
 	.read		= do_sync_read,
 	.write		= do_sync_write,
 	.aio_read	= generic_file_aio_read,
-	.aio_write	= ext3_file_write,
+	.aio_write	= generic_file_aio_write,
 	.unlocked_ioctl	= ext3_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= ext3_compat_ioctl,
-- 
1.6.0.2

[PATCH 10/17] ext4: Remove syncing logic from ext4_file_write

[Jan Kara]

The syncing is now properly handled by generic_file_aio_write() so
no special ext4 code is needed.

CC: linux-ext4@vger.kernel.org
CC: tytso@mit.edu
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext4/file.c |   53 ++---------------------------------------------------
 1 files changed, 2 insertions(+), 51 deletions(-)

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index 3f1873f..aafe432 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -58,10 +58,7 @@ static ssize_t
 ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		unsigned long nr_segs, loff_t pos)
 {
-	struct file *file = iocb->ki_filp;
-	struct inode *inode = file->f_path.dentry->d_inode;
-	ssize_t ret;
-	int err;
+	struct inode *inode = iocb->ki_filp->f_path.dentry->d_inode;
 
 	/*
 	 * If we have encountered a bitmap-format file, the size limit
@@ -81,53 +78,7 @@ ext4_file_write(struct kiocb *iocb, const struct iovec *iov,
 		}
 	}
 
-	ret = generic_file_aio_write(iocb, iov, nr_segs, pos);
-	/*
-	 * Skip flushing if there was an error, or if nothing was written.
-	 */
-	if (ret <= 0)
-		return ret;
-
-	/*
-	 * If the inode is IS_SYNC, or is O_SYNC and we are doing data
-	 * journalling then we need to make sure that we force the transaction
-	 * to disk to keep all metadata uptodate synchronously.
-	 */
-	if (file->f_flags & O_SYNC) {
-		/*
-		 * If we are non-data-journaled, then the dirty data has
-		 * already been flushed to backing store by generic_osync_inode,
-		 * and the inode has been flushed too if there have been any
-		 * modifications other than mere timestamp updates.
-		 *
-		 * Open question --- do we care about flushing timestamps too
-		 * if the inode is IS_SYNC?
-		 */
-		if (!ext4_should_journal_data(inode))
-			return ret;
-
-		goto force_commit;
-	}
-
-	/*
-	 * So we know that there has been no forced data flush.  If the inode
-	 * is marked IS_SYNC, we need to force one ourselves.
-	 */
-	if (!IS_SYNC(inode))
-		return ret;
-
-	/*
-	 * Open question #2 --- should we force data to disk here too?  If we
-	 * don't, the only impact is that data=writeback filesystems won't
-	 * flush data to disk automatically on IS_SYNC, only metadata (but
-	 * historically, that is what ext2 has done.)
-	 */
-
-force_commit:
-	err = ext4_force_commit(inode->i_sb);
-	if (err)
-		return err;
-	return ret;
+	return generic_file_aio_write(iocb, iov, nr_segs, pos);
 }
 
 static struct vm_operations_struct ext4_file_vm_ops = {
-- 
1.6.0.2

[PATCH 11/17] ntfs: Use new syncing helpers and update comments

[Jan Kara]

Use new syncing helpers in .write and .aio_write functions. Also
remove superfluous syncing in ntfs_file_buffered_write() and update
comments about generic_osync_inode().

CC: Anton Altaparmakov <aia21@cantab.net>
CC: linux-ntfs-dev@lists.sourceforge.net
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ntfs/file.c |   16 ++++------------
 fs/ntfs/mft.c  |   13 ++++++-------
 2 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/fs/ntfs/file.c b/fs/ntfs/file.c
index 3140a44..4350d49 100644
--- a/fs/ntfs/file.c
+++ b/fs/ntfs/file.c
@@ -2076,14 +2076,6 @@ err_out:
 	*ppos = pos;
 	if (cached_page)
 		page_cache_release(cached_page);
-	/* For now, when the user asks for O_SYNC, we actually give O_DSYNC. */
-	if (likely(!status)) {
-		if (unlikely((file->f_flags & O_SYNC) || IS_SYNC(vi))) {
-			if (!mapping->a_ops->writepage || !is_sync_kiocb(iocb))
-				status = generic_osync_inode(vi, mapping,
-						OSYNC_METADATA|OSYNC_DATA);
-		}
-  	}
 	pagevec_lru_add_file(&lru_pvec);
 	ntfs_debug("Done.  Returning %s (written 0x%lx, status %li).",
 			written ? "written" : "status", (unsigned long)written,
@@ -2145,8 +2137,8 @@ static ssize_t ntfs_file_aio_write(struct kiocb *iocb, const struct iovec *iov,
 	mutex_lock(&inode->i_mutex);
 	ret = ntfs_file_aio_write_nolock(iocb, iov, nr_segs, &iocb->ki_pos);
 	mutex_unlock(&inode->i_mutex);
-	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-		int err = sync_page_range(inode, mapping, pos, ret);
+	if (ret > 0) {
+		int err = generic_write_sync(file, pos, ret);
 		if (err < 0)
 			ret = err;
 	}
@@ -2173,8 +2165,8 @@ static ssize_t ntfs_file_writev(struct file *file, const struct iovec *iov,
 	if (ret == -EIOCBQUEUED)
 		ret = wait_on_sync_kiocb(&kiocb);
 	mutex_unlock(&inode->i_mutex);
-	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
-		int err = sync_page_range(inode, mapping, *ppos - ret, ret);
+	if (ret > 0) {
+		int err = generic_write_sync(file, *ppos - ret, ret);
 		if (err < 0)
 			ret = err;
 	}
diff --git a/fs/ntfs/mft.c b/fs/ntfs/mft.c
index 23bf684..1caa0ef 100644
--- a/fs/ntfs/mft.c
+++ b/fs/ntfs/mft.c
@@ -384,13 +384,12 @@ unm_err_out:
  * it is dirty in the inode meta data rather than the data page cache of the
  * inode, and thus there are no data pages that need writing out.  Therefore, a
  * full mark_inode_dirty() is overkill.  A mark_inode_dirty_sync(), on the
- * other hand, is not sufficient, because I_DIRTY_DATASYNC needs to be set to
- * ensure ->write_inode is called from generic_osync_inode() and this needs to
- * happen or the file data would not necessarily hit the device synchronously,
- * even though the vfs inode has the O_SYNC flag set.  Also, I_DIRTY_DATASYNC
- * simply "feels" better than just I_DIRTY_SYNC, since the file data has not
- * actually hit the block device yet, which is not what I_DIRTY_SYNC on its own
- * would suggest.
+ * other hand, is not sufficient, because ->write_inode needs to be called even
+ * in case of fdatasync. This needs to happen or the file data would not
+ * necessarily hit the device synchronously, even though the vfs inode has the
+ * O_SYNC flag set.  Also, I_DIRTY_DATASYNC simply "feels" better than just
+ * I_DIRTY_SYNC, since the file data has not actually hit the block device yet,
+ * which is not what I_DIRTY_SYNC on its own would suggest.
  */
 void __mark_mft_record_dirty(ntfs_inode *ni)
 {
-- 
1.6.0.2

[PATCH 12/17] ocfs2: Update syncing after splicing to match generic version

[Jan Kara]

Update ocfs2 specific splicing code to use generic syncing helper. The sync now
does not happen under rw_lock because generic_write_sync() acquires i_mutex
which ranks above rw_lock. That should not matter because standard fsync path
does not hold it either.

CC: Joel Becker <Joel.Becker@oracle.com>
CC: ocfs2-devel@oss.oracle.com
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ocfs2/file.c |   27 ++++++---------------------
 1 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/fs/ocfs2/file.c b/fs/ocfs2/file.c
index 1c71f0a..bd7fdf8 100644
--- a/fs/ocfs2/file.c
+++ b/fs/ocfs2/file.c
@@ -1990,31 +1990,16 @@ static ssize_t ocfs2_file_splice_write(struct pipe_inode_info *pipe,
 
 	if (ret > 0) {
 		unsigned long nr_pages;
+		int err;
 
-		*ppos += ret;
 		nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 
-		/*
-		 * If file or inode is SYNC and we actually wrote some data,
-		 * sync it.
-		 */
-		if (unlikely((out->f_flags & O_SYNC) || IS_SYNC(inode))) {
-			int err;
-
-			mutex_lock(&inode->i_mutex);
-			err = ocfs2_rw_lock(inode, 1);
-			if (err < 0) {
-				mlog_errno(err);
-			} else {
-				err = generic_osync_inode(inode, mapping,
-						  OSYNC_METADATA|OSYNC_DATA);
-				ocfs2_rw_unlock(inode, 1);
-			}
-			mutex_unlock(&inode->i_mutex);
+		err = generic_write_sync(out, *ppos, ret);
+		if (err)
+			ret = err;
+		else
+			*ppos += ret;
 
-			if (err)
-				ret = err;
-		}
 		balance_dirty_pages_ratelimited_nr(mapping, nr_pages);
 	}
 
-- 
1.6.0.2

Re: [Ocfs2-devel] [PATCH 12/17] ocfs2: Update syncing after splicing to match generic version

[Mark Fasheh]

On Fri, Aug 21, 2009 at 07:24:02PM +0200, Jan Kara wrote:
> Update ocfs2 specific splicing code to use generic syncing helper. The sync now
> does not happen under rw_lock because generic_write_sync() acquires i_mutex
> which ranks above rw_lock. That should not matter because standard fsync path
> does not hold it either.

Thanks Jan,

Acked-by: Mark Fasheh <mfasheh@suse.com>

--
Mark Fasheh

Re: [Ocfs2-devel] [PATCH 12/17] ocfs2: Update syncing after splicing to match generic version

[Joel Becker]

On Mon, Aug 24, 2009 at 11:35:43AM -0700, Mark Fasheh wrote:
> On Fri, Aug 21, 2009 at 07:24:02PM +0200, Jan Kara wrote:
> > Update ocfs2 specific splicing code to use generic syncing helper. The sync now
> > does not happen under rw_lock because generic_write_sync() acquires i_mutex
> > which ranks above rw_lock. That should not matter because standard fsync path
> > does not hold it either.
> 
> Thanks Jan,
> 
> Acked-by: Mark Fasheh <mfasheh@suse.com>

<aol>Me too!</aol>
Acked-by: Joel Becker <joel.becker@oracle.com>

Joel

-- 

A good programming language should have features that make the
kind of people who use the phrase "software engineering" shake
their heads disapprovingly.
	- Paul Graham

Joel Becker
Principal Software Developer
Oracle
E-mail: joel.becker@oracle.com
Phone: (650) 506-8127

Re: [Ocfs2-devel] [PATCH 12/17] ocfs2: Update syncing after splicing to match generic version

[Jan Kara]

On Mon 24-08-09 11:40:09, Joel Becker wrote:
> On Mon, Aug 24, 2009 at 11:35:43AM -0700, Mark Fasheh wrote:
> > On Fri, Aug 21, 2009 at 07:24:02PM +0200, Jan Kara wrote:
> > > Update ocfs2 specific splicing code to use generic syncing helper. The sync now
> > > does not happen under rw_lock because generic_write_sync() acquires i_mutex
> > > which ranks above rw_lock. That should not matter because standard fsync path
> > > does not hold it either.
> > 
> > Thanks Jan,
> > 
> > Acked-by: Mark Fasheh <mfasheh@suse.com>
> 
> <aol>Me too!</aol>
> Acked-by: Joel Becker <joel.becker@oracle.com>
  Thanks. BTW: There's also the patch
ocfs2: Use __generic_file_aio_write instead of generic_file_aio_write_nolock
  in the series you might want to have a look at. Actually, I did a
straightforward opencoding of generic_osync_inode() but if you agree it's
a good thing to do, I can move the whole sync to the end of the function
out of i_mutex because AFAICS there's no real reason why
filemap_fdatawrite_range() or jbd2_journal_force_commit() should need any
cluster lock or mutex. We probably only need to decide under those locks,
whether we need to call jbd2_journal_force_commit() or not.

									Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

[PATCH 13/17] xfs: Convert sync_page_range() to simple fdatawrite_range()

[Jan Kara]

Christoph Hellwig says that it is enough for XFS to call
filemap_fdatawrite_range() instead of sync_page_range() because we do all the
waiting when forcing the log.

CC: Felix Blyakher <felixb@sgi.com>
CC: xfs@oss.sgi.com
CC: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/xfs/linux-2.6/xfs_lrw.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c
index 7078974..a68053c 100644
--- a/fs/xfs/linux-2.6/xfs_lrw.c
+++ b/fs/xfs/linux-2.6/xfs_lrw.c
@@ -817,7 +817,7 @@ write_retry:
 		xfs_iunlock(xip, iolock);
 		if (need_i_mutex)
 			mutex_unlock(&inode->i_mutex);
-		error2 = sync_page_range(inode, mapping, pos, ret);
+		error2 = filemap_fdatawrite_range(mapping, pos, pos + ret - 1);
 		if (!error)
 			error = error2;
 		if (need_i_mutex)
-- 
1.6.0.2

Re: [PATCH 13/17] xfs: Convert sync_page_range() to simple fdatawrite_range()

[Christoph Hellwig]

On Fri, Aug 21, 2009 at 07:24:03PM +0200, Jan Kara wrote:
> +		error2 = filemap_fdatawrite_range(mapping, pos, pos + ret - 1);

I think this should be a filemap_write_and_wait_range

Re: [PATCH 13/17] xfs: Convert sync_page_range() to simple fdatawrite_range()

[Jan Kara]

On Fri 21-08-09 19:28:01, Christoph Hellwig wrote:
> On Fri, Aug 21, 2009 at 07:24:03PM +0200, Jan Kara wrote:
> > +		error2 = filemap_fdatawrite_range(mapping, pos, pos + ret - 1);
> 
> I think this should be a filemap_write_and_wait_range
  Ah true, I somehow misinterpretted what xfs_write_sync_logforce() does.

									Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

[PATCH 14/17] pohmelfs: Use new syncing helper

[Jan Kara]

Use new generic_write_sync() helper instead of sync_page_range().

Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 drivers/staging/pohmelfs/inode.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/pohmelfs/inode.c b/drivers/staging/pohmelfs/inode.c
index 17801a5..a2e5eed 100644
--- a/drivers/staging/pohmelfs/inode.c
+++ b/drivers/staging/pohmelfs/inode.c
@@ -927,10 +927,10 @@ ssize_t pohmelfs_write(struct file *file, const char __user *buf,
 	mutex_unlock(&inode->i_mutex);
 	WARN_ON(ret < 0);
 
-	if (ret > 0 && ((file->f_flags & O_SYNC) || IS_SYNC(inode))) {
+	if (ret > 0) {
 		ssize_t err;
 
-		err = sync_page_range(inode, mapping, pos, ret);
+		err = generic_write_sync(file, pos, ret);
 		if (err < 0)
 			ret = err;
 		WARN_ON(ret < 0);
-- 
1.6.0.2

[PATCH 15/17] nfs: Remove reference to generic_osync_inode from a comment

[Jan Kara]

generic_file_direct_write() no longer calls generic_osync_inode() so remove the
comment.

CC: linux-nfs@vger.kernel.org
CC: Neil Brown <neilb@suse.de>
CC: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/nfs/direct.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 489fc01..fd5fcc9 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -934,9 +934,6 @@ out:
  * back into its cache.  We let the server do generic write
  * parameter checking and report problems.
  *
- * We also avoid an unnecessary invocation of generic_osync_inode(),
- * as it is fairly meaningless to sync the metadata of an NFS file.
- *
  * We eliminate local atime updates, see direct read above.
  *
  * We avoid unnecessary page cache invalidations for normal cached
-- 
1.6.0.2

Re: [PATCH 15/17] nfs: Remove reference to generic_osync_inode from a comment

[Trond Myklebust]

On Fri, 2009-08-21 at 19:24 +0200, Jan Kara wrote:
> generic_file_direct_write() no longer calls generic_osync_inode() so remove the
> comment.

Thanks. I've applied it to the nfs-for-2.6.32 branch.

Cheers
  Trond

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[PATCH 16/17] fat: Opencode sync_page_range_nolock()

[Jan Kara]

fat_cont_expand() is the only user of sync_page_range_nolock(). It's also the
only user of generic_osync_inode() which does not have a file open.  So
opencode needed actions for FAT so that we can convert generic_osync_inode() to
a standard syncing path.

Update a comment about generic_osync_inode().

CC: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/fat/file.c |   22 ++++++++++++++++++++--
 fs/fat/misc.c |    4 ++--
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/fs/fat/file.c b/fs/fat/file.c
index f042b96..e8c159d 100644
--- a/fs/fat/file.c
+++ b/fs/fat/file.c
@@ -176,8 +176,26 @@ static int fat_cont_expand(struct inode *inode, loff_t size)
 
 	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
 	mark_inode_dirty(inode);
-	if (IS_SYNC(inode))
-		err = sync_page_range_nolock(inode, mapping, start, count);
+	if (IS_SYNC(inode)) {
+		int err2;
+
+		/*
+		 * Opencode syncing since we don't have a file open to use
+		 * standard fsync path.
+		 */
+		err = filemap_fdatawrite_range(mapping, start,
+					       start + count - 1);
+		err2 = sync_mapping_buffers(mapping);
+		if (!err)
+			err = err2;
+		err2 = write_inode_now(inode, 1);
+		if (!err)
+			err = err2;
+		if (!err) {
+			err =  filemap_fdatawait_range(mapping, start,
+						       start + count - 1);
+		}
+	}
 out:
 	return err;
 }
diff --git a/fs/fat/misc.c b/fs/fat/misc.c
index a6c2047..4e35be8 100644
--- a/fs/fat/misc.c
+++ b/fs/fat/misc.c
@@ -119,8 +119,8 @@ int fat_chain_add(struct inode *inode, int new_dclus, int nr_cluster)
 		MSDOS_I(inode)->i_start = new_dclus;
 		MSDOS_I(inode)->i_logstart = new_dclus;
 		/*
-		 * Since generic_osync_inode() synchronize later if
-		 * this is not directory, we don't here.
+		 * Since generic_write_sync() synchronizes regular files later,
+		 * we sync here only directories.
 		 */
 		if (S_ISDIR(inode->i_mode) && IS_DIRSYNC(inode)) {
 			ret = fat_sync_inode(inode);
-- 
1.6.0.2

[PATCH 17/17] vfs: Remove generic_osync_inode() and sync_page_range{_nolock}()

[Jan Kara]

Remove these three functions since nobody uses them anymore.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/fs-writeback.c         |   54 --------------------------------------
 include/linux/fs.h        |    5 ---
 include/linux/writeback.h |    4 ---
 mm/filemap.c              |   64 ---------------------------------------------
 4 files changed, 0 insertions(+), 127 deletions(-)

diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
index c54226b..d8dbef0 100644
--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -737,57 +737,3 @@ int sync_inode(struct inode *inode, struct writeback_control *wbc)
 	return ret;
 }
 EXPORT_SYMBOL(sync_inode);
-
-/**
- * generic_osync_inode - flush all dirty data for a given inode to disk
- * @inode: inode to write
- * @mapping: the address_space that should be flushed
- * @what:  what to write and wait upon
- *
- * This can be called by file_write functions for files which have the
- * O_SYNC flag set, to flush dirty writes to disk.
- *
- * @what is a bitmask, specifying which part of the inode's data should be
- * written and waited upon.
- *
- *    OSYNC_DATA:     i_mapping's dirty data
- *    OSYNC_METADATA: the buffers at i_mapping->private_list
- *    OSYNC_INODE:    the inode itself
- */
-
-int generic_osync_inode(struct inode *inode, struct address_space *mapping, int what)
-{
-	int err = 0;
-	int need_write_inode_now = 0;
-	int err2;
-
-	if (what & OSYNC_DATA)
-		err = filemap_fdatawrite(mapping);
-	if (what & (OSYNC_METADATA|OSYNC_DATA)) {
-		err2 = sync_mapping_buffers(mapping);
-		if (!err)
-			err = err2;
-	}
-	if (what & OSYNC_DATA) {
-		err2 = filemap_fdatawait(mapping);
-		if (!err)
-			err = err2;
-	}
-
-	spin_lock(&inode_lock);
-	if ((inode->i_state & I_DIRTY) &&
-	    ((what & OSYNC_INODE) || (inode->i_state & I_DIRTY_DATASYNC)))
-		need_write_inode_now = 1;
-	spin_unlock(&inode_lock);
-
-	if (need_write_inode_now) {
-		err2 = write_inode_now(inode, 1);
-		if (!err)
-			err = err2;
-	}
-	else
-		inode_sync_wait(inode);
-
-	return err;
-}
-EXPORT_SYMBOL(generic_osync_inode);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 648001c..57b2866 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1458,11 +1458,6 @@ int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
 #define DT_SOCK		12
 #define DT_WHT		14
 
-#define OSYNC_METADATA	(1<<0)
-#define OSYNC_DATA	(1<<1)
-#define OSYNC_INODE	(1<<2)
-int generic_osync_inode(struct inode *, struct address_space *, int);
-
 /*
  * This is the "filldir" function type, used by readdir() to let
  * the kernel specify what kind of dirent layout it wants to have.
diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index 3224820..1446694 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -157,10 +157,6 @@ int write_cache_pages(struct address_space *mapping,
 		      struct writeback_control *wbc, writepage_t writepage,
 		      void *data);
 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
-int sync_page_range(struct inode *inode, struct address_space *mapping,
-			loff_t pos, loff_t count);
-int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
-			   loff_t pos, loff_t count);
 void set_page_dirty_balance(struct page *page, int page_mkwrite);
 void writeback_set_ratelimit(void);
 
diff --git a/mm/filemap.c b/mm/filemap.c
index 70988a1..854e10e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -326,70 +326,6 @@ int filemap_fdatawait_range(struct address_space *mapping, loff_t start,
 EXPORT_SYMBOL(filemap_fdatawait_range);
 
 /**
- * sync_page_range - write and wait on all pages in the passed range
- * @inode:	target inode
- * @mapping:	target address_space
- * @pos:	beginning offset in pages to write
- * @count:	number of bytes to write
- *
- * Write and wait upon all the pages in the passed range.  This is a "data
- * integrity" operation.  It waits upon in-flight writeout before starting and
- * waiting upon new writeout.  If there was an IO error, return it.
- *
- * We need to re-take i_mutex during the generic_osync_inode list walk because
- * it is otherwise livelockable.
- */
-int sync_page_range(struct inode *inode, struct address_space *mapping,
-			loff_t pos, loff_t count)
-{
-	pgoff_t start = pos >> PAGE_CACHE_SHIFT;
-	pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
-	int ret;
-
-	if (!mapping_cap_writeback_dirty(mapping) || !count)
-		return 0;
-	ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
-	if (ret == 0) {
-		mutex_lock(&inode->i_mutex);
-		ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
-		mutex_unlock(&inode->i_mutex);
-	}
-	if (ret == 0)
-		ret = wait_on_page_writeback_range(mapping, start, end);
-	return ret;
-}
-EXPORT_SYMBOL(sync_page_range);
-
-/**
- * sync_page_range_nolock - write & wait on all pages in the passed range without locking
- * @inode:	target inode
- * @mapping:	target address_space
- * @pos:	beginning offset in pages to write
- * @count:	number of bytes to write
- *
- * Note: Holding i_mutex across sync_page_range_nolock() is not a good idea
- * as it forces O_SYNC writers to different parts of the same file
- * to be serialised right until io completion.
- */
-int sync_page_range_nolock(struct inode *inode, struct address_space *mapping,
-			   loff_t pos, loff_t count)
-{
-	pgoff_t start = pos >> PAGE_CACHE_SHIFT;
-	pgoff_t end = (pos + count - 1) >> PAGE_CACHE_SHIFT;
-	int ret;
-
-	if (!mapping_cap_writeback_dirty(mapping) || !count)
-		return 0;
-	ret = filemap_fdatawrite_range(mapping, pos, pos + count - 1);
-	if (ret == 0)
-		ret = generic_osync_inode(inode, mapping, OSYNC_METADATA);
-	if (ret == 0)
-		ret = wait_on_page_writeback_range(mapping, start, end);
-	return ret;
-}
-EXPORT_SYMBOL(sync_page_range_nolock);
-
-/**
  * filemap_fdatawait - wait for all under-writeback pages to complete
  * @mapping: address space structure to wait for
  *
-- 
1.6.0.2

Re: [PATCH 0/17] Make O_SYNC handling use standard syncing path (Version 2)

[Jamie Lokier]

Jan Kara wrote:
> The patch set unifines O_SYNC handling with standard fsync() path.  After this,
> we have just one place forcing a single file to disk so filesystems like ext3 /
> ext4 don't have to force a transaction commit in ext?_file_write for O_SYNC
> files / IS_SYNC inodes.  The code is also cleaner this way (actually about 150
> lines shorter), we don't sync the inode several times as it happened previously
> etc.

Afaik, O_SYNC requires just the written data to be committed to disk,
but fsync() requires all dirty data for the file (including written by
other processes / descriptors) to be committed to disk.

So doing the equivalent of fsync() after write might be the wrong
thing to do.

-- Jamie