Btrfs: return gracefully from balance if fs tree is corrupted

commit 3561b9db70928f207be4570b48fc19898eeaef54 upstream.

When relocating tree blocks, we firstly get block information from
back references in the extent tree, we then search fs tree to try to
find all parents of a block.

However, if fs tree is corrupted, eg. if there're some missing
items, we could come across these WARN_ONs and BUG_ONs.

This makes us print some error messages and return gracefully
from balance.

Signed-off-by: Liu Bo <bo.li.liu@oracle.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c
index b4ca5454ef1a7ebc4fcb8eec476701bc8496a050..937d015422e0b4b4a438eb44625b0ea0dea8f735 100644 (file)
--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -921,9 +921,16 @@ again:
                        path2->slots[level]--;
 
                eb = path2->nodes[level];
-               WARN_ON(btrfs_node_blockptr(eb, path2->slots[level]) !=
-                       cur->bytenr);
-
+               if (btrfs_node_blockptr(eb, path2->slots[level]) !=
+                   cur->bytenr) {
+                       btrfs_err(root->fs_info,
+       "couldn't find block (%llu) (level %d) in tree (%llu) with key (%llu %u %llu)",
+                                 cur->bytenr, level - 1, root->objectid,
+                                 node_key->objectid, node_key->type,
+                                 node_key->offset);
+                       err = -ENOENT;
+                       goto out;
+               }
                lower = cur;
                need_check = true;
                for (; level < BTRFS_MAX_LEVEL; level++) {
@@ -2676,11 +2683,15 @@ static int do_relocation(struct btrfs_trans_handle *trans,
 
                if (!upper->eb) {
                        ret = btrfs_search_slot(trans, root, key, path, 0, 1);
-                       if (ret < 0) {
-                               err = ret;
+                       if (ret) {
+                               if (ret < 0)
+                                       err = ret;
+                               else
+                                       err = -ENOENT;
+
+                               btrfs_release_path(path);
                                break;
                        }
-                       BUG_ON(ret > 0);
 
                        if (!upper->eb) {
                                upper->eb = path->nodes[upper->level];