[PATCH AUTOSEL 4.19 69/81] f2fs: fix to data block override node segment by mistake

Sasha Levin
2019-05-07T05:55:46Z

From: zhengliang <zhengliang6@huawei.com>

[ Upstream commit a0770e13c8da83bdb64738c0209ab02dd3cfff8b ]

v4: Rearrange the previous three versions.

The following scenario could lead to data block override by mistake.

TASK A | TASK kworker | TASK B | TASK C
| | |
open | | |
write | | |
close | | |
| f2fs_write_data_pages | |
| f2fs_write_cache_pages | |
| f2fs_outplace_write_data | |
| f2fs_allocate_data_block (get block in seg S, | |
| S is full, and only | |
| have this valid data | |
| block) | |
| allocate_segment | |
| locate_dirty_segment (mark S as PRE) | |
| f2fs_submit_page_write (submit but is not | |
| written on dev) | |
unlink | | |
iput_final | | |
f2fs_drop_inode | | |
f2fs_truncate | | |
(not evict) | | |
| | write_checkpoint |
| | flush merged bio but not wait file data writeback |
| | set_prefree_as_free (mark S as FREE) |
| | | update NODE/DATA
| | | allocate_segment (select S)
| writeback done | |

So we need to guarantee io complete before truncate inode in f2fs_drop_inode.

Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Zheng Liang <zhengliang6@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
fs/f2fs/super.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index 2264f27fd26d..036eb1e0d557 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -890,6 +890,10 @@ static int f2fs_drop_inode(struct inode *inode)
sb_start_intwrite(inode->i_sb);
f2fs_i_size_write(inode, 0);

+ f2fs_submit_merged_write_cond(F2FS_I_SB(inode),
+ inode, NULL, 0, DATA);
+ truncate_inode_pages_final(inode->i_mapping);
+
if (F2FS_HAS_BLOCKS(inode))
f2fs_truncate(inode);

--
2.20.1