btrfs: move the root freeing stuff into btrfs_put_root

There are a few different ways to free roots, either you allocated them
yourself and you just do

free_extent_buffer(root->node);
free_extent_buffer(root->commit_node);
btrfs_put_root(root);

Which is the pattern for log roots.  Or for snapshots/subvolumes that
are being dropped you simply call btrfs_free_fs_root() which does all
the cleanup for you.

Unify this all into btrfs_put_root(), so that we don't free up things
associated with the root until the last reference is dropped.  This
makes the root freeing code much more significant.

The only caveat is at close_ctree() time we have to free the extent
buffers for all of our main roots (extent_root, chunk_root, etc) because
we have to drop the btree_inode and we'll run into issues if we hold
onto those nodes until ->kill_sb() time.  This will be addressed in the
future when we kill the btree_inode.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>

fs/btrfs/disk-io.c

@@ -1255,11 +1255,8 @@ struct btrfs_root *btrfs_create_tree(struct btrfs_trans_handle *trans,
 	return root;
 
 fail:
-	if (leaf) {
+	if (leaf)
 		btrfs_tree_unlock(leaf);
-		free_extent_buffer(root->commit_root);
-		free_extent_buffer(leaf);
-	}
 	btrfs_put_root(root);
 
 	return ERR_PTR(ret);
@@ -1382,10 +1379,10 @@ struct btrfs_root *btrfs_read_tree_root(struct btrfs_root *tree_root,
 				     generation, level, NULL);
 	if (IS_ERR(root->node)) {
 		ret = PTR_ERR(root->node);
+		root->node = NULL;
 		goto find_fail;
 	} else if (!btrfs_buffer_uptodate(root->node, generation, 0)) {
 		ret = -EIO;
-		free_extent_buffer(root->node);
 		goto find_fail;
 	}
 	root->commit_root = btrfs_root_node(root);
@@ -1617,14 +1614,14 @@ struct btrfs_root *btrfs_get_fs_root(struct btrfs_fs_info *fs_info,
 	if (ret) {
 		btrfs_put_root(root);
 		if (ret == -EEXIST) {
-			btrfs_free_fs_root(root);
+			btrfs_put_root(root);
 			goto again;
 		}
 		goto fail;
 	}
 	return root;
 fail:
-	btrfs_free_fs_root(root);
+	btrfs_put_root(root);
 	return ERR_PTR(ret);
 }
 
@@ -1996,11 +1993,35 @@ static void free_root_pointers(struct btrfs_fs_info *info, bool free_chunk_root)
 	free_root_extent_buffers(info->csum_root);
 	free_root_extent_buffers(info->quota_root);
 	free_root_extent_buffers(info->uuid_root);
+	free_root_extent_buffers(info->fs_root);
 	if (free_chunk_root)
 		free_root_extent_buffers(info->chunk_root);
 	free_root_extent_buffers(info->free_space_root);
 }
 
+void btrfs_put_root(struct btrfs_root *root)
+{
+	if (!root)
+		return;
+
+	if (refcount_dec_and_test(&root->refs)) {
+		WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
+		if (root->anon_dev)
+			free_anon_bdev(root->anon_dev);
+		btrfs_drew_lock_destroy(&root->snapshot_lock);
+		free_extent_buffer(root->node);
+		free_extent_buffer(root->commit_root);
+		kfree(root->free_ino_ctl);
+		kfree(root->free_ino_pinned);
+#ifdef CONFIG_BTRFS_DEBUG
+		spin_lock(&root->fs_info->fs_roots_radix_lock);
+		list_del_init(&root->leak_list);
+		spin_unlock(&root->fs_info->fs_roots_radix_lock);
+#endif
+		kfree(root);
+	}
+}
+
 void btrfs_free_fs_roots(struct btrfs_fs_info *fs_info)
 {
 	int ret;
@@ -2012,14 +2033,11 @@ void btrfs_free_fs_roots(struct btrfs_fs_info *fs_info)
 				     struct btrfs_root, root_list);
 		list_del(&gang[0]->root_list);
 
-		if (test_bit(BTRFS_ROOT_IN_RADIX, &gang[0]->state)) {
+		if (test_bit(BTRFS_ROOT_IN_RADIX, &gang[0]->state))
 			btrfs_drop_and_free_fs_root(fs_info, gang[0]);
-		} else {
-			free_extent_buffer(gang[0]->node);
-			free_extent_buffer(gang[0]->commit_root);
+		else
 			btrfs_put_root(gang[0]);
 	}
-	}
 
 	while (1) {
 		ret = radix_tree_gang_lookup(&fs_info->fs_roots_radix,
@@ -2223,11 +2241,11 @@ static int btrfs_replay_log(struct btrfs_fs_info *fs_info,
 	if (IS_ERR(log_tree_root->node)) {
 		btrfs_warn(fs_info, "failed to read log tree");
 		ret = PTR_ERR(log_tree_root->node);
+		log_tree_root->node = NULL;
 		btrfs_put_root(log_tree_root);
 		return ret;
 	} else if (!extent_buffer_uptodate(log_tree_root->node)) {
 		btrfs_err(fs_info, "failed to read log tree");
-		free_extent_buffer(log_tree_root->node);
 		btrfs_put_root(log_tree_root);
 		return -EIO;
 	}
@@ -2236,7 +2254,6 @@ static int btrfs_replay_log(struct btrfs_fs_info *fs_info,
 	if (ret) {
 		btrfs_handle_fs_error(fs_info, ret,
 				      "Failed to recover log tree");
-		free_extent_buffer(log_tree_root->node);
 		btrfs_put_root(log_tree_root);
 		return ret;
 	}
@@ -3901,8 +3918,6 @@ void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
 	if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 		btrfs_free_log(NULL, root);
 		if (root->reloc_root) {
-			free_extent_buffer(root->reloc_root->node);
-			free_extent_buffer(root->reloc_root->commit_root);
 			btrfs_put_root(root->reloc_root);
 			root->reloc_root = NULL;
 		}
@@ -3916,19 +3931,6 @@ void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
 		iput(root->ino_cache_inode);
 		root->ino_cache_inode = NULL;
 	}
-	btrfs_free_fs_root(root);
-}
-
-void btrfs_free_fs_root(struct btrfs_root *root)
-{
-	WARN_ON(!RB_EMPTY_ROOT(&root->inode_tree));
-	if (root->anon_dev)
-		free_anon_bdev(root->anon_dev);
-	btrfs_drew_lock_destroy(&root->snapshot_lock);
-	free_extent_buffer(root->node);
-	free_extent_buffer(root->commit_root);
-	kfree(root->free_ino_ctl);
-	kfree(root->free_ino_pinned);
 	btrfs_put_root(root);
 }
 
@@ -4093,8 +4095,6 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info)
 	btrfs_sysfs_remove_mounted(fs_info);
 	btrfs_sysfs_remove_fsid(fs_info->fs_devices);
 
-	btrfs_free_fs_roots(fs_info);
-
 	btrfs_put_block_group_cache(fs_info);
 
 	/*
@@ -4106,6 +4106,7 @@ void __cold close_ctree(struct btrfs_fs_info *fs_info)
 
 	clear_bit(BTRFS_FS_OPEN, &fs_info->flags);
 	free_root_pointers(fs_info, true);
+	btrfs_free_fs_roots(fs_info);
 
 	/*
 	 * We must free the block groups after dropping the fs_roots as we could

fs/btrfs/disk-io.h

@@ -76,7 +76,6 @@ void btrfs_btree_balance_dirty(struct btrfs_fs_info *fs_info);
 void btrfs_btree_balance_dirty_nodelay(struct btrfs_fs_info *fs_info);
 void btrfs_drop_and_free_fs_root(struct btrfs_fs_info *fs_info,
 				 struct btrfs_root *root);
-void btrfs_free_fs_root(struct btrfs_root *root);
 
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS
 struct btrfs_root *btrfs_alloc_dummy_root(struct btrfs_fs_info *fs_info);
@@ -98,20 +97,7 @@ static inline struct btrfs_root *btrfs_grab_root(struct btrfs_root *root)
 	return NULL;
 }
 
-static inline void btrfs_put_root(struct btrfs_root *root)
-{
-	if (!root)
-		return;
-	if (refcount_dec_and_test(&root->refs)) {
-#ifdef CONFIG_BTRFS_DEBUG
-		spin_lock(&root->fs_info->fs_roots_radix_lock);
-		list_del_init(&root->leak_list);
-		spin_unlock(&root->fs_info->fs_roots_radix_lock);
-#endif
-		kfree(root);
-	}
-}
-
+void btrfs_put_root(struct btrfs_root *root);
 void btrfs_mark_buffer_dirty(struct extent_buffer *buf);
 int btrfs_buffer_uptodate(struct extent_buffer *buf, u64 parent_transid,
 			  int atomic);

fs/btrfs/extent-tree.c

@@ -5485,13 +5485,10 @@ int btrfs_drop_snapshot(struct btrfs_root *root, int update_ref, int for_reloc)
 		}
 	}
 
-	if (test_bit(BTRFS_ROOT_IN_RADIX, &root->state)) {
+	if (test_bit(BTRFS_ROOT_IN_RADIX, &root->state))
 		btrfs_add_dropped_root(trans, root);
-	} else {
-		free_extent_buffer(root->node);
-		free_extent_buffer(root->commit_root);
+	else
 		btrfs_put_root(root);
-	}
 	root_dropped = true;
 out_end_trans:
 	btrfs_end_transaction_throttle(trans);

fs/btrfs/extent_io.c

@@ -64,12 +64,21 @@ void btrfs_extent_buffer_leak_debug_check(struct btrfs_fs_info *fs_info)
 	struct extent_buffer *eb;
 	unsigned long flags;
 
+	/*
+	 * If we didn't get into open_ctree our allocated_ebs will not be
+	 * initialized, so just skip this.
+	 */
+	if (!fs_info->allocated_ebs.next)
+		return;
+
 	spin_lock_irqsave(&fs_info->eb_leak_lock, flags);
 	while (!list_empty(&fs_info->allocated_ebs)) {
 		eb = list_first_entry(&fs_info->allocated_ebs,
 				      struct extent_buffer, leak_list);
-		pr_err("BTRFS: buffer leak start %llu len %lu refs %d bflags %lu\n",
-		       eb->start, eb->len, atomic_read(&eb->refs), eb->bflags);
+		pr_err(
+	"BTRFS: buffer leak start %llu len %lu refs %d bflags %lu owner %llu\n",
+		       eb->start, eb->len, atomic_read(&eb->refs), eb->bflags,
+		       btrfs_header_owner(eb));
 		list_del(&eb->leak_list);
 		kmem_cache_free(extent_buffer_cache, eb);
 	}
@@ -4875,7 +4884,6 @@ int extent_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 
 static void __free_extent_buffer(struct extent_buffer *eb)
 {
-	btrfs_leak_debug_del(&eb->fs_info->eb_leak_lock, &eb->leak_list);
 	kmem_cache_free(extent_buffer_cache, eb);
 }
 
@@ -4941,6 +4949,7 @@ static void btrfs_release_extent_buffer_pages(struct extent_buffer *eb)
 static inline void btrfs_release_extent_buffer(struct extent_buffer *eb)
 {
 	btrfs_release_extent_buffer_pages(eb);
+	btrfs_leak_debug_del(&eb->fs_info->eb_leak_lock, &eb->leak_list);
 	__free_extent_buffer(eb);
 }
 
@@ -5329,6 +5338,7 @@ static int release_extent_buffer(struct extent_buffer *eb)
 			spin_unlock(&eb->refs_lock);
 		}
 
+		btrfs_leak_debug_del(&eb->fs_info->eb_leak_lock, &eb->leak_list);
 		/* Should be safe to release our pages at this point */
 		btrfs_release_extent_buffer_pages(eb);
 #ifdef CONFIG_BTRFS_FS_RUN_SANITY_TESTS

fs/btrfs/free-space-tree.c

@@ -1251,8 +1251,6 @@ int btrfs_clear_free_space_tree(struct btrfs_fs_info *fs_info)
 	btrfs_free_tree_block(trans, free_space_root, free_space_root->node,
 			      0, 1);
 
-	free_extent_buffer(free_space_root->node);
-	free_extent_buffer(free_space_root->commit_root);
 	btrfs_put_root(free_space_root);
 
 	return btrfs_commit_transaction(trans);

fs/btrfs/qgroup.c

@@ -1038,11 +1038,8 @@ int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
 out_free_path:
 	btrfs_free_path(path);
 out_free_root:
-	if (ret) {
-		free_extent_buffer(quota_root->node);
-		free_extent_buffer(quota_root->commit_root);
+	if (ret)
 		btrfs_put_root(quota_root);
-	}
 out:
 	if (ret) {
 		ulist_free(fs_info->qgroup_ulist);
@@ -1105,8 +1102,6 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
 	btrfs_tree_unlock(quota_root->node);
 	btrfs_free_tree_block(trans, quota_root, quota_root->node, 0, 1);
 
-	free_extent_buffer(quota_root->node);
-	free_extent_buffer(quota_root->commit_root);
 	btrfs_put_root(quota_root);
 
 end_trans:

fs/btrfs/relocation.c

@@ -2579,10 +2579,6 @@ void free_reloc_roots(struct list_head *list)
 		reloc_root = list_entry(list->next, struct btrfs_root,
 					root_list);
 		__del_reloc_root(reloc_root);
-		free_extent_buffer(reloc_root->node);
-		free_extent_buffer(reloc_root->commit_root);
-		reloc_root->node = NULL;
-		reloc_root->commit_root = NULL;
 	}
 }
 

fs/btrfs/tests/btrfs-tests.c

@@ -194,6 +194,7 @@ void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info)
 	cleanup_srcu_struct(&fs_info->subvol_srcu);
 	kfree(fs_info->super_copy);
 	btrfs_check_leaked_roots(fs_info);
+	btrfs_extent_buffer_leak_debug_check(fs_info);
 	kfree(fs_info->fs_devices);
 	kfree(fs_info);
 }
@@ -205,10 +206,6 @@ void btrfs_free_dummy_root(struct btrfs_root *root)
 	/* Will be freed by btrfs_free_fs_roots */
 	if (WARN_ON(test_bit(BTRFS_ROOT_IN_RADIX, &root->state)))
 		return;
-	if (root->node) {
-		/* One for allocate_extent_buffer */
-		free_extent_buffer(root->node);
-	}
 	btrfs_put_root(root);
 }
 

fs/btrfs/tree-log.c

@@ -3299,7 +3299,6 @@ static void free_log_tree(struct btrfs_trans_handle *trans,
 
 	clear_extent_bits(&log->dirty_log_pages, 0, (u64)-1,
 			  EXTENT_DIRTY | EXTENT_NEW | EXTENT_NEED_WAIT);
-	free_extent_buffer(log->node);
 	btrfs_put_root(log);
 }
 
@@ -6246,8 +6245,6 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 				ret = btrfs_pin_extent_for_log_replay(trans,
 							log->node->start,
 							log->node->len);
-			free_extent_buffer(log->node);
-			free_extent_buffer(log->commit_root);
 			btrfs_put_root(log);
 
 			if (!ret)
@@ -6285,8 +6282,6 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 
 		wc.replay_dest->log_root = NULL;
 		btrfs_put_root(wc.replay_dest);
-		free_extent_buffer(log->node);
-		free_extent_buffer(log->commit_root);
 		btrfs_put_root(log);
 
 		if (ret)
@@ -6318,7 +6313,6 @@ int btrfs_recover_log_trees(struct btrfs_root *log_root_tree)
 	if (ret)
 		return ret;
 
-	free_extent_buffer(log_root_tree->node);
 	log_root_tree->log_root = NULL;
 	clear_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags);
 	btrfs_put_root(log_root_tree);