Btrfs: handle a bogus chunk tree nicely

If you restore a btrfs-image file system and try to mount that file system we'll
panic.  That's because btrfs-image restores and just makes one big chunk to
envelope the whole disk, since they are really only meant to be messed with by
our btrfs-progs.  So fix up btrfs_rmap_block and the callers of it for mount so
that we no longer panic but instead just return an error and fail to mount.
Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 350b9b1..a8ff25a 100644 (file)
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -257,7 +257,8 @@ static int exclude_super_stripes(struct btrfs_root *root,
                cache->bytes_super += stripe_len;
                ret = add_excluded_extent(root, cache->key.objectid,
                                          stripe_len);
-               BUG_ON(ret); /* -ENOMEM */
+               if (ret)
+                       return ret;
        }
 
        for (i = 0; i < BTRFS_SUPER_MIRROR_MAX; i++) {
@@ -265,13 +266,17 @@ static int exclude_super_stripes(struct btrfs_root *root,
                ret = btrfs_rmap_block(&root->fs_info->mapping_tree,
                                       cache->key.objectid, bytenr,
                                       0, &logical, &nr, &stripe_len);
-               BUG_ON(ret); /* -ENOMEM */
+               if (ret)
+                       return ret;
 
                while (nr--) {
                        cache->bytes_super += stripe_len;
                        ret = add_excluded_extent(root, logical[nr],
                                                  stripe_len);
-                       BUG_ON(ret); /* -ENOMEM */
+                       if (ret) {
+                               kfree(logical);
+                               return ret;
+                       }
                }
 
                kfree(logical);
@@ -7964,7 +7969,17 @@ int btrfs_read_block_groups(struct btrfs_root *root)
                 * info has super bytes accounted for, otherwise we'll think
                 * we have more space than we actually do.
                 */
-               exclude_super_stripes(root, cache);
+               ret = exclude_super_stripes(root, cache);
+               if (ret) {
+                       /*
+                        * We may have excluded something, so call this just in
+                        * case.
+                        */
+                       free_excluded_extents(root, cache);
+                       kfree(cache->free_space_ctl);
+                       kfree(cache);
+                       goto error;
+               }
 
                /*
                 * check for two cases, either we are full, and therefore
@@ -8106,7 +8121,17 @@ int btrfs_make_block_group(struct btrfs_trans_handle *trans,
 
        cache->last_byte_to_unpin = (u64)-1;
        cache->cached = BTRFS_CACHE_FINISHED;
-       exclude_super_stripes(root, cache);
+       ret = exclude_super_stripes(root, cache);
+       if (ret) {
+               /*
+                * We may have excluded something, so call this just in
+                * case.
+                */
+               free_excluded_extents(root, cache);
+               kfree(cache->free_space_ctl);
+               kfree(cache);
+               return ret;
+       }
 
        add_new_free_space(cache, root->fs_info, chunk_offset,
                           chunk_offset + size);

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 5989a92..2854c82 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -4935,7 +4935,18 @@ int btrfs_rmap_block(struct btrfs_mapping_tree *map_tree,
        em = lookup_extent_mapping(em_tree, chunk_start, 1);
        read_unlock(&em_tree->lock);
 
-       BUG_ON(!em || em->start != chunk_start);
+       if (!em) {
+               printk(KERN_ERR "btrfs: couldn't find em for chunk %Lu\n",
+                      chunk_start);
+               return -EIO;
+       }
+
+       if (em->start != chunk_start) {
+               printk(KERN_ERR "btrfs: bad chunk start, em=%Lu, wanted=%Lu\n",
+                      em->start, chunk_start);
+               free_extent_map(em);
+               return -EIO;
+       }
        map = (struct map_lookup *)em->bdev;
 
        length = em->len;