From: Zheng Liu <gnehzuil.liu@gmail.com>
Date: Sat, 30 Jun 2012 23:12:57 +0000 (-0400)
Subject: ext4: honor O_(D)SYNC semantic in ext4_fallocate()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=f4e95b3316c4daa43224753bb98f41456fef86c7;p=GitHub%2Fexynos8895%2Fandroid_kernel_samsung_universal8895.git

ext4: honor O_(D)SYNC semantic in ext4_fallocate()

Ext4 must make sure the transaction to be commited to the disk when
user opens a file with O_(D)SYNC flag and do a fallocate(2) call.

This problem had been reported by Christoph Hellwig in this thread:
http://www.spinics.net/lists/linux-btrfs/msg13621.html

Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 91341ec6e06a..f1089cba913a 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4420,6 +4420,8 @@ retry:
 		ext4_falloc_update_inode(inode, mode, new_size,
 					 (map.m_flags & EXT4_MAP_NEW));
 		ext4_mark_inode_dirty(handle, inode);
+		if ((file->f_flags & O_SYNC) && ret >= max_blocks)
+			ext4_handle_sync(handle);
 		ret2 = ext4_journal_stop(handle);
 		if (ret2)
 			break;