[PATCH 3.16 027/245] Btrfs: check inconsistence between chunk and block group

Ben Hutchings
2020-04-23T23:23:52Z

From: Liu Bo <bo.li.liu@oracle.com>

commit 6fb37b756acce6d6e045f79c3764206033f617b4 upstream.

With btrfs-corrupt-block, one can drop one chunk item and mounting
will end up with a panic in btrfs_full_stripe_len().

This doesn't not remove the BUG_ON, but instead checks it a bit
earlier when we find the block group item.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/extent-tree.c | 17 ++++++++++++++++-
1 file changed, 16 insertions(+), 1 deletion(-)

--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -8571,7 +8571,22 @@ static int find_first_block_group(struct

if (found_key.objectid >= key->objectid &&
found_key.type == BTRFS_BLOCK_GROUP_ITEM_KEY) {
- ret = 0;
+ struct extent_map_tree *em_tree;
+ struct extent_map *em;
+
+ em_tree = &root->fs_info->mapping_tree.map_tree;
+ read_lock(&em_tree->lock);
+ em = lookup_extent_mapping(em_tree, found_key.objectid,
+ found_key.offset);
+ read_unlock(&em_tree->lock);
+ if (!em) {
+ btrfs_err(root->fs_info,
+ "logical %llu len %llu found bg but no related chunk",
+ found_key.objectid, found_key.offset);
+ ret = -ENOENT;
+ } else {
+ ret = 0;
+ }
goto out;
}
path->slots[0]++;