Now we detect the looped node chain by comparing the loop counter with
free blocks. While it may take tens of seconds to quit when the free
blocks are large enough. We can use Floyd's cycle detection algorithm to
make it more efficient.
Below is the log we encounter on a 256GB UFS storage and it takes about
25 seconds to detect looped node chain. After changing the algorithm, it
takes about 20ms to finish the same job.
[ 10.822904] fsck.f2fs: Info: version timestamp cur: 17, prev: 430
[ 10.822949] fsck.f2fs: [update_superblock: 762] Info: Done to
update superblock
[ 10.822953] fsck.f2fs: Info: superblock features = 1499 :
encrypt verity extra_attr project_quota quota_ino casefold
[ 10.822956] fsck.f2fs: Info: superblock encrypt level = 0, salt =
00000000000000000000000000000000
[ 10.822960] fsck.f2fs: Info: total FS sectors = 59249811 (231444
MB)
[ 35.852827] fsck.f2fs: detect looped node chain,
blkaddr:1114802, next:1114803
[ 35.852842] fsck.f2fs: [f2fs_do_mount:3846] record_fsync_data
failed
[ 35.856106] fsck.f2fs: fsck.f2fs terminated by exit(255)
Signed-off-by: Chunhai Guo <guochun...@vivo.com>
---
fsck/mount.c | 57 ++++++++++++++++++++++++++++++++++++++++++----------
1 file changed, 46 insertions(+), 11 deletions(-)
diff --git a/fsck/mount.c b/fsck/mount.c
index df0314d..2e919d9 100644
--- a/fsck/mount.c
+++ b/fsck/mount.c
@@ -3394,22 +3394,48 @@ static void destroy_fsync_dnodes(struct list_head *head)
del_fsync_inode(entry);
}
+static int find_node_blk_fast(struct f2fs_sb_info *sbi, block_t *blkaddr_fast,
+ struct f2fs_node *node_blk_fast, bool *is_detecting)
+{
+ int i, err;
+
+ for (i = 0; i < 2; i++) {
+ if (!f2fs_is_valid_blkaddr(sbi, *blkaddr_fast, META_POR)) {
+ *is_detecting = false;
+ return 0;
+ }
+
+ err = dev_read_block(node_blk_fast, *blkaddr_fast);
+ if (err)
+ return err;
+
+ if (!is_recoverable_dnode(sbi, node_blk_fast)) {
+ *is_detecting = false;
+ return 0;
+ }
+
+ *blkaddr_fast = next_blkaddr_of_node(node_blk_fast);
+ }
+
+ return 0;
+}
+
static int find_fsync_inode(struct f2fs_sb_info *sbi, struct list_head *head)
{
struct curseg_info *curseg;
- struct f2fs_node *node_blk;
- block_t blkaddr;
- unsigned int loop_cnt = 0;
- unsigned int free_blocks = MAIN_SEGS(sbi) * sbi->blocks_per_seg -
- sbi->total_valid_block_count;
+ struct f2fs_node *node_blk, *node_blk_fast;
+ block_t blkaddr, blkaddr_fast;
+ bool is_detecting = true;
int err = 0;
/* get node pages in the current segment */
curseg = CURSEG_I(sbi, CURSEG_WARM_NODE);
blkaddr = NEXT_FREE_BLKADDR(sbi, curseg);
+ blkaddr_fast = blkaddr;
node_blk = calloc(F2FS_BLKSIZE, 1);
- ASSERT(node_blk);
+ node_blk_fast = calloc(F2FS_BLKSIZE, 1);
+ ASSERT(node_blk && node_blk_fast);
while (1) {
struct fsync_inode_entry *entry;
@@ -3424,6 +3450,16 @@ static int find_fsync_inode(struct f2fs_sb_info *sbi,
struct list_head *head)
if (!is_recoverable_dnode(sbi, node_blk))
break;
+ /* Here we use Floyd's cycle detection algorithm to detect
+ * looped node chain more effeciently.
+ */
+ if (is_detecting) {
+ err = find_node_blk_fast(sbi, &blkaddr_fast,
+ node_blk_fast, &is_detecting);
+ if (err)
+ break;
+ }
+
if (!is_fsync_dnode(node_blk))
goto next;
@@ -3441,11 +3477,9 @@ static int find_fsync_inode(struct f2fs_sb_info *sbi,
struct list_head *head)
entry->last_dentry = blkaddr;
next:
/* sanity check in order to detect looped node chain */
- if (++loop_cnt >= free_blocks ||
- blkaddr == next_blkaddr_of_node(node_blk)) {
- MSG(0, "\tdetect looped node chain, blkaddr:%u,
next:%u\n",
- blkaddr,
- next_blkaddr_of_node(node_blk));
+ if (is_detecting && (blkaddr_fast == blkaddr)) {
+ MSG(0, "\tdetect looped node chain, blkaddr:%u\n",
+ blkaddr);
err = -1;
break;
}
@@ -3453,6 +3487,7 @@ next:
blkaddr = next_blkaddr_of_node(node_blk);
}
+ free(node_blk_fast);
free(node_blk);
return err;
}
--
2.25.1
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