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btrfs-progs: fix infinite loop when bad key order repair fails 

An infinite loop can be triggered during fuzz/003:

  ====== RUN MAYFAIL btrfs check --repair tests/fuzz-tests/images/bko-199833-reloc-recovery-crash.raw.restored
  [1/7] checking root items
  Fixed 0 roots.
  [2/7] checking extents
  ctree.c:1650: leaf_space_used: Warning: assertion `data_len < 0` failed, value 1
  bad key ordering 18 19
  ctree.c:1650: leaf_space_used: Warning: assertion `data_len < 0` failed, value 1
  bad key ordering 18 19
  ctree.c:1650: leaf_space_used: Warning: assertion `data_len < 0` failed, value 1
  bad key ordering 18 19

[CAUSE]
In try_to_fix_bad_block() it's possible that btrfs_find_all_roots()
finds no root referring to that tree block, thus we can't do any repair.

However in that case, we still return 0 since the last caller assigning
@ret is btrfs_find_all_roots(), and the ulist while loop doesn't get run
at all.

And since try_to_fix_bad_block() returns 0, check_block() in
check/main.c will return -EAGAIN to re-check the tree block.

This leads to the infinite loop.

[FIX]
Change the default return value from 0 to -EIO in
try_to_fix_bad_block(), so if there is no tree referring to the bad tree
block, it won't cause infinite loop anymore.

Signed-off-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
master
Qu Wenruo 2018-08-03 13:50:20 +08:00 committed by David Sterba
parent 6dbc43b867
commit b02b426a78
1 changed files with 5 additions and 0 deletions
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5
check/main.c
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@ -4051,6 +4051,11 @@ static int try_to_fix_bad_block(struct btrfs_root *root,
btrfs_init_path(&path);
ULIST_ITER_INIT(&iter);
/*
* If we found no roots referrening to this tree block, there is no
* chance to fix. So our default ret is -EIO.
*/
ret = -EIO;
while ((node = ulist_next(roots, &iter))) {
root_key.objectid = node->val;
root_key.type = BTRFS_ROOT_ITEM_KEY;