Hello Qu Wenruo,
The patch 4c98cc4b6d12: "btrfs: Expoert and move leaf/subtree qgroup
helpers to qgroup.c" from Oct 18, 2016, leads to the following static
checker warning:
fs/btrfs/qgroup.c:1682 btrfs_qgroup_trace_subtree()
error: buffer overflow 'path->nodes' 8 <= 8
fs/btrfs/qgroup.c
1641 int btrfs_qgroup_trace_subtree(struct btrfs_trans_handle *trans,
1642 struct btrfs_root *root,
1643 struct extent_buffer *root_eb,
1644 u64 root_gen, int root_level)
1645 {
1646 int ret = 0;
1647 int level;
1648 struct extent_buffer *eb = root_eb;
1649 struct btrfs_path *path = NULL;
1650
1651 BUG_ON(root_level < 0 || root_level > BTRFS_MAX_LEVEL);
You didn't really introduce the warning, just made it show up as a new
warning by moving the code around. Still, this should be
>= BTRFS_MAX_LEVEL shouldn't it?
1652 BUG_ON(root_eb == NULL);
1653
1654 if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &root->fs_info->flags))
1655 return 0;
1656
1657 if (!extent_buffer_uptodate(root_eb)) {
1658 ret = btrfs_read_buffer(root_eb, root_gen);
1659 if (ret)
1660 goto out;
1661 }
1662
1663 if (root_level == 0) {
1664 ret = btrfs_qgroup_trace_leaf_items(trans, root,
root_eb);
1665 goto out;
1666 }
1667
1668 path = btrfs_alloc_path();
1669 if (!path)
1670 return -ENOMEM;
1671
1672 /*
1673 * Walk down the tree. Missing extent blocks are filled in as
1674 * we go. Metadata is accounted every time we read a new
1675 * extent block.
1676 *
1677 * When we reach a leaf, we account for file extent items in it,
1678 * walk back up the tree (adjusting slot pointers as we go)
1679 * and restart the search process.
1680 */
1681 extent_buffer_get(root_eb); /* For path */
1682 path->nodes[root_level] = root_eb;
Otherwise, we're off by one.
1683 path->slots[root_level] = 0;
1684 path->locks[root_level] = 0; /* so release_path doesn't try to
unlock */
1685 walk_down:
regards,
dan carpenter
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