From: jiangyiwen <jiangyiwen@huawei.com>
Date: Fri, 6 Nov 2015 02:43:55 +0000 (-0800)
Subject: ocfs2: fill in the unused portion of the block with zeros by dio_zero_block()
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=4e357b932a665e62eb0642633057b8d7156ed8db;p=GitHub%2FLineageOS%2FG12%2Fandroid_kernel_amlogic_linux-4.9.git

ocfs2: fill in the unused portion of the block with zeros by dio_zero_block()

A simplified test case is (this case from Ryan):
1) dd if=/dev/zero of=/mnt/hello bs=512 count=1 oflag=direct;
2) truncate /mnt/hello -s 2097152
file 'hello' is not exist before test. After this command,
file 'hello' should be all zero. But 512~4096 is some random data.

Setting bh state to new when get a new block, if so,
direct_io_worker()->dio_zero_block() will fill-in the unused portion
of the block with zero.

Signed-off-by: Yiwen Jiang <jiangyiwen@huawei.com>
Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
Cc: Mark Fasheh <mfasheh@suse.de>
Cc: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/ocfs2/aops.c b/fs/ocfs2/aops.c
index f04914cc19a4..7f604727f487 100644
--- a/fs/ocfs2/aops.c
+++ b/fs/ocfs2/aops.c
@@ -589,6 +589,7 @@ static int ocfs2_direct_IO_get_blocks(struct inode *inode, sector_t iblock,
 			ret = -EIO;
 			goto bail;
 		}
+		set_buffer_new(bh_result);
 		up_write(&OCFS2_I(inode)->ip_alloc_sem);
 	}