Btrfs: fix leaking block group on balance

The block group structs are referenced in many different
places, and it's not safe to free while balancing.  So, those block
group structs were simply leaked instead.

This patch replaces the block group pointer in the inode with the starting byte
offset of the block group and adds reference counting to the block group
struct.

Signed-off-by: Yan Zheng <zheng.yan@oracle.com>

1 files changed, 9 insertions, 8 deletions

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 5b0c79d22c09..8733081d97a3 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -653,6 +653,9 @@ struct btrfs_block_group_cache {
 
 	/* for block groups in the same raid type */
 	struct list_head list;
+
+	/* usage count */
+	atomic_t count;
 };
 
 struct btrfs_leaf_ref_tree {
@@ -1706,10 +1709,8 @@ int btrfs_copy_pinned(struct btrfs_root *root, struct extent_io_tree *copy);
 struct btrfs_block_group_cache *btrfs_lookup_block_group(struct
 							 btrfs_fs_info *info,
 							 u64 bytenr);
-struct btrfs_block_group_cache *btrfs_find_block_group(struct btrfs_root *root,
-						 struct btrfs_block_group_cache
-						 *hint, u64 search_start,
-						 int data, int owner);
+u64 btrfs_find_block_group(struct btrfs_root *root,
+			   u64 search_start, u64 search_hint, int owner);
 struct extent_buffer *btrfs_alloc_free_block(struct btrfs_trans_handle *trans,
 					     struct btrfs_root *root,
 					     u32 blocksize, u64 parent,
@@ -1770,6 +1771,7 @@ int btrfs_update_extent_ref(struct btrfs_trans_handle *trans,
 			    u64 owner_objectid);
 int btrfs_write_dirty_block_groups(struct btrfs_trans_handle *trans,
 				    struct btrfs_root *root);
+int btrfs_extent_readonly(struct btrfs_root *root, u64 bytenr);
 int btrfs_free_block_groups(struct btrfs_fs_info *info);
 int btrfs_read_block_groups(struct btrfs_root *root);
 int btrfs_make_block_group(struct btrfs_trans_handle *trans,
@@ -2019,10 +2021,9 @@ int btrfs_start_delalloc_inodes(struct btrfs_root *root);
 int btrfs_set_extent_delalloc(struct inode *inode, u64 start, u64 end);
 int btrfs_writepages(struct address_space *mapping,
 		     struct writeback_control *wbc);
-int btrfs_create_subvol_root(struct btrfs_root *new_root, struct dentry *dentry,
-		struct btrfs_trans_handle *trans, u64 new_dirid,
-		struct btrfs_block_group_cache *block_group);
-
+int btrfs_create_subvol_root(struct btrfs_trans_handle *trans,
+			     struct btrfs_root *new_root, struct dentry *dentry,
+			     u64 new_dirid, u64 alloc_hint);
 int btrfs_merge_bio_hook(struct page *page, unsigned long offset,
 			 size_t size, struct bio *bio, unsigned long bio_flags);