f2fs: compress: do sanity check on cluster

This patch adds f2fs_sanity_check_cluster() to support doing
sanity check on cluster of compressed file, it will be triggered
from below two paths:

- __f2fs_cluster_blocks()
- f2fs_map_blocks(F2FS_GET_BLOCK_FIEMAP)

And it can detect below three kind of cluster insanity status.

C: COMPRESS_ADDR
N: NULL_ADDR or NEW_ADDR
V: valid blkaddr
*: any value

1. [*|C|*|*]
2. [C|*|C|*]
3. [C|N|N|V]

Signed-off-by: Chao Yu <chao@kernel.org>
[Nathan Chancellor: fix missing inline warning]
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c
index 12cd63603137..e4e4eb800d2b 100644
--- a/fs/f2fs/data.c
+++ b/fs/f2fs/data.c
@@ -1552,6 +1552,13 @@ next_block:
 			map->m_flags |= F2FS_MAP_NEW;
 			blkaddr = dn.data_blkaddr;
 		} else {
+			if (f2fs_compressed_file(inode) &&
+					f2fs_sanity_check_cluster(&dn) &&
+					(flag != F2FS_GET_BLOCK_FIEMAP ||
+					IS_ENABLED(CONFIG_F2FS_CHECK_FS))) {
+				err = -EFSCORRUPTED;
+				goto sync_out;
+			}
 			if (flag == F2FS_GET_BLOCK_BMAP) {
 				map->m_pblk = 0;
 				goto sync_out;