Btrfs: remove extent mapping if we fail to add chunk

I got a double free error when unmounting a file system that failed to add a
chunk during its operation.  This is because we will kfree the mapping that
we created but leave the extent_map in the em_tree for chunks.  So to fix
this just remove the extent_map when we error out so we don't run into this
problem.  Thanks,

Signed-off-by: Josef Bacik <jbacik@fusionio.com>

1 files changed, 12 insertions, 2 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 13efbcf03122..c7843349c795 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -3821,9 +3821,10 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         write_lock(&em_tree->lock);
         ret = add_extent_mapping(em_tree, em);
         write_unlock(&em_tree->lock);
-        free_extent_map(em);
-        if (ret)
+        if (ret) {
+                free_extent_map(em);
                 goto error;
+        }
 
         for (i = 0; i < map->num_stripes; ++i) {
                 struct btrfs_device *device;
@@ -3848,6 +3849,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
                 goto error_dev_extent;
         }
 
+        free_extent_map(em);
         kfree(devices_info);
         return 0;
 
@@ -3863,6 +3865,14 @@ error_dev_extent:
                         break;
                 }
         }
+        write_lock(&em_tree->lock);
+        remove_extent_mapping(em_tree, em);
+        write_unlock(&em_tree->lock);
+
+        /* One for our allocation */
+        free_extent_map(em);
+        /* One for the tree reference */
+        free_extent_map(em);
 error:
         kfree(map);
         kfree(devices_info);