f2fs: fix to handle looped node chain during recovery

There is no checksum in node block now, so bit-transition from hardware
can make node_footer.next_blkaddr being corrupted w/o any detection,
result in node chain becoming looped one.

For this condition, during recovery, in order to avoid running into dead
loop, let's detect it and just skip out.

Signed-off-by: Yunlei He <heyunlei@huawei.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/fs/f2fs/recovery.c b/fs/f2fs/recovery.c
index c5e5c45130b5..1b23d3febe4c 100644
--- a/fs/f2fs/recovery.c
+++ b/fs/f2fs/recovery.c
@@ -242,6 +242,9 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
         struct curseg_info *curseg;
         struct page *page = NULL;
         block_t blkaddr;
+        unsigned int loop_cnt = 0;
+        unsigned int free_blocks = sbi->user_block_count -
+                                        valid_user_blocks(sbi);
         int err = 0;
 
         /* get node pages in the current segment */
@@ -294,6 +297,17 @@ static int find_fsync_dnodes(struct f2fs_sb_info *sbi, struct list_head *head,
                 if (IS_INODE(page) && is_dent_dnode(page))
                         entry->last_dentry = blkaddr;
 next:
+                /* sanity check in order to detect looped node chain */
+                if (++loop_cnt >= free_blocks ||
+                        blkaddr == next_blkaddr_of_node(page)) {
+                        f2fs_msg(sbi->sb, KERN_NOTICE,
+                                "%s: detect looped node chain, "
+                                "blkaddr:%u, next:%u",
+                                __func__, blkaddr, next_blkaddr_of_node(page));
+                        err = -EINVAL;
+                        break;
+                }
+
                 /* check next segment */
                 blkaddr = next_blkaddr_of_node(page);
                 f2fs_put_page(page, 1);