Revert "btrfs: let btrfs_delete_unused_bgs() to clean relocated bgs"

This reverts commit 5d8eb6fe517583f9c6d5b94faf2254a0207a45c9.

When we remove devices, we free the device structures.  Delaying
btfs_remove_chunk() ends up hitting a use-after-free on them.

Signed-off-by: Chris Mason <clm@fb.com>

2 files changed, 15 insertions, 11 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 11802eaaab54..210c94ac8818 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -10849,7 +10849,7 @@ void btrfs_delete_unused_bgs(struct btrfs_fs_info *fs_info)
                 spin_lock(&block_group->lock);
                 if (block_group->reserved ||
                     btrfs_block_group_used(&block_group->item) ||
-                    (block_group->ro && !block_group->removed) ||
+                    block_group->ro ||
                     list_is_singular(&block_group->list)) {
                         /*
                          * We want to bail if we made new allocations or have
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index b4048c1b3d9b..71a60cc01451 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -2906,8 +2906,8 @@ out:
 static int btrfs_relocate_chunk(struct btrfs_root *root, u64 chunk_offset)
 {
         struct btrfs_root *extent_root;
+        struct btrfs_trans_handle *trans;
         int ret;
-        struct btrfs_block_group_cache *block_group;
 
         root = root->fs_info->chunk_root;
         extent_root = root->fs_info->extent_root;
@@ -2937,17 +2937,21 @@ static int btrfs_relocate_chunk(struct btrfs_root *root, u64 chunk_offset)
         if (ret)
                 return ret;
 
+        trans = btrfs_start_trans_remove_block_group(root->fs_info,
+                                                     chunk_offset);
+        if (IS_ERR(trans)) {
+                ret = PTR_ERR(trans);
+                btrfs_handle_fs_error(root->fs_info, ret, NULL);
+                return ret;
+        }
+
         /*
-         * step two, flag the chunk as removed and let
-         * btrfs_delete_unused_bgs() remove it.
+         * step two, delete the device extents and the
+         * chunk tree entries
          */
-        block_group = btrfs_lookup_block_group(root->fs_info, chunk_offset);
-        spin_lock(&block_group->lock);
-        block_group->removed = 1;
-        spin_unlock(&block_group->lock);
-        btrfs_put_block_group(block_group);
-
-        return 0;
+        ret = btrfs_remove_chunk(trans, root, chunk_offset);
+        btrfs_end_transaction(trans, extent_root);
+        return ret;
 }
 
 static int btrfs_relocate_sys_chunks(struct btrfs_root *root)