btrfs: move lockdep class setting out of extent_io_tree_init

The per-inode file extent tree was added in 41a2ee75 ("btrfs:
introduce per-inode file extent tree"), it's the only tree type
that requires the lockdep class. Move it to the file where it is
actually used.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/extent-io-tree.c

@@ -78,14 +78,6 @@ static inline void __btrfs_debug_check_extent_io_range(const char *caller,
 #define btrfs_debug_check_extent_io_range(c, s, e)	do {} while (0)
 #endif
 
-/*
- * For the file_extent_tree, we want to hold the inode lock when we lookup and
- * update the disk_i_size, but lockdep will complain because our io_tree we hold
- * the tree lock and get the inode lock when setting delalloc.  These two things
- * are unrelated, so make a class for the file_extent_tree so we don't get the
- * two locking patterns mixed up.
- */
-static struct lock_class_key file_extent_tree_class;
 
 void extent_io_tree_init(struct btrfs_fs_info *fs_info,
 			 struct extent_io_tree *tree, unsigned int owner)
@@ -95,8 +87,6 @@ void extent_io_tree_init(struct btrfs_fs_info *fs_info,
 	spin_lock_init(&tree->lock);
 	tree->inode = NULL;
 	tree->owner = owner;
-	if (owner == IO_TREE_INODE_FILE_EXTENT)
-		lockdep_set_class(&tree->lock, &file_extent_tree_class);
 }
 
 /*

fs/btrfs/inode.c

@@ -114,6 +114,15 @@ struct data_reloc_warn {
 	int mirror_num;
 };
 
+/*
+ * For the file_extent_tree, we want to hold the inode lock when we lookup and
+ * update the disk_i_size, but lockdep will complain because our io_tree we hold
+ * the tree lock and get the inode lock when setting delalloc. These two things
+ * are unrelated, so make a class for the file_extent_tree so we don't get the
+ * two locking patterns mixed up.
+ */
+static struct lock_class_key file_extent_tree_class;
+
 static const struct inode_operations btrfs_dir_inode_operations;
 static const struct inode_operations btrfs_symlink_inode_operations;
 static const struct inode_operations btrfs_special_inode_operations;
@@ -8506,6 +8515,8 @@ struct inode *btrfs_alloc_inode(struct super_block *sb)
 	ei->io_tree.inode = ei;
 	extent_io_tree_init(fs_info, &ei->file_extent_tree,
 			    IO_TREE_INODE_FILE_EXTENT);
+	/* Lockdep class is set only for the file extent tree. */
+	lockdep_set_class(&ei->file_extent_tree.lock, &file_extent_tree_class);
 	mutex_init(&ei->log_mutex);
 	spin_lock_init(&ei->ordered_tree_lock);
 	ei->ordered_tree = RB_ROOT;