From: Andrew Morton <akpm@osdl.org>

Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
---

 fs/fat/inode.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff -puN fs/fat/inode.c~fs-prepare_write-fixes-fat-fix fs/fat/inode.c
--- a/fs/fat/inode.c~fs-prepare_write-fixes-fat-fix
+++ a/fs/fat/inode.c
@@ -151,7 +151,8 @@ static int fat_commit_write(struct file 
 {
 	struct inode *inode = page->mapping->host;
 	int err;
-	if (to - from > 0)
+
+	if (to - from == 0)
 		return 0;
 
 	err = generic_commit_write(file, page, from, to);
_