From 56fcad29d4b3cbcbb2ed47a9d3ceca3f57175417 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Tue, 8 Sep 2009 14:59:42 +0200
Subject: [PATCH] ext3: Flush disk caches on fsync when needed

In case we fsync() a file and inode is not dirty, we don't force a transaction
to disk and hence don't flush disk caches. Thus file data could be just in disk
caches and not on persistent storage. Fix the problem by flushing disk caches
if we didn't force a transaction commit.

Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/ext3/fsync.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/ext3/fsync.c b/fs/ext3/fsync.c
index d33634119e17e..451d166bbe93a 100644
--- a/fs/ext3/fsync.c
+++ b/fs/ext3/fsync.c
@@ -23,6 +23,7 @@
  */
 
 #include <linux/time.h>
+#include <linux/blkdev.h>
 #include <linux/fs.h>
 #include <linux/sched.h>
 #include <linux/writeback.h>
@@ -73,7 +74,7 @@ int ext3_sync_file(struct file * file, struct dentry *dentry, int datasync)
 	}
 
 	if (datasync && !(inode->i_state & I_DIRTY_DATASYNC))
-		goto out;
+		goto flush;
 
 	/*
 	 * The VFS has written the file data.  If the inode is unaltered
@@ -85,7 +86,16 @@ int ext3_sync_file(struct file * file, struct dentry *dentry, int datasync)
 			.nr_to_write = 0, /* sys_fsync did this */
 		};
 		ret = sync_inode(inode, &wbc);
+		goto out;
 	}
+flush:
+	/*
+	 * In case we didn't commit a transaction, we have to flush
+	 * disk caches manually so that data really is on persistent
+	 * storage
+	 */
+	if (test_opt(inode->i_sb, BARRIER))
+		blkdev_issue_flush(inode->i_sb->s_bdev, NULL);
 out:
 	return ret;
 }
-- 
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