Commit b8522a1e authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: Factor out tree roots initialization during mount 



The code responsible for reading and initializing tree roots is
scattered in open_ctree among 2 labels, emulating a loop. This is rather
confusing to reason about. Instead, factor the code to a new function,
init_tree_roots which implements the same logical flow.

There are a couple of notable differences, namely:

* Instead of using next_backup_root it's using the newly introduced
  read_backup_root.

* If read_backup_root returns an error init_tree_roots propagates the
  error and there is no special handling of that case e.g. the code jumps
  straight to 'fail_tree_roots' label. The old code, however, was
  (erroneously) jumping to 'fail_block_groups' label if next_backup_root
  did fail, this was unnecessary since the tree roots init logic doesn't
  modify the state of block groups.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent bd2336b2

fs/btrfs/disk-io.c

+85 −57
Original line number Diff line number Diff line
@@ -2610,6 +2610,89 @@ out: 
	return ret;

}



int __cold init_tree_roots(struct btrfs_fs_info *fs_info)

{

	struct btrfs_super_block *sb = fs_info->super_copy;

	struct btrfs_root *tree_root = fs_info->tree_root;

	bool handle_error = false;

	int ret = 0;

	int i;



	for (i = 0; i < BTRFS_NUM_BACKUP_ROOTS; i++) {

		u64 generation;

		int level;



		if (handle_error) {

			if (!IS_ERR(tree_root->node))

				free_extent_buffer(tree_root->node);

			tree_root->node = NULL;



			if (!btrfs_test_opt(fs_info, USEBACKUPROOT))

				break;



			free_root_pointers(fs_info, 0);



			/*

			 * Don't use the log in recovery mode, it won't be

			 * valid

			 */

			btrfs_set_super_log_root(sb, 0);



			/* We can't trust the free space cache either */

			btrfs_set_opt(fs_info->mount_opt, CLEAR_CACHE);



			ret = read_backup_root(fs_info, i);

			if (ret < 0)

				return ret;

		}

		generation = btrfs_super_generation(sb);

		level = btrfs_super_root_level(sb);

		tree_root->node = read_tree_block(fs_info, btrfs_super_root(sb),

						  generation, level, NULL);

		if (IS_ERR(tree_root->node) ||

		    !extent_buffer_uptodate(tree_root->node)) {

			handle_error = true;



			if (IS_ERR(tree_root->node))

				ret = PTR_ERR(tree_root->node);

			else if (!extent_buffer_uptodate(tree_root->node))

				ret = -EUCLEAN;



			btrfs_warn(fs_info, "failed to read tree root");

			continue;

		}



		btrfs_set_root_node(&tree_root->root_item, tree_root->node);

		tree_root->commit_root = btrfs_root_node(tree_root);

		btrfs_set_root_refs(&tree_root->root_item, 1);



		mutex_lock(&tree_root->objectid_mutex);

		ret = btrfs_find_highest_objectid(tree_root,

						&tree_root->highest_objectid);

		if (ret < 0) {

			mutex_unlock(&tree_root->objectid_mutex);

			handle_error = true;

			continue;

		}



		ASSERT(tree_root->highest_objectid <= BTRFS_LAST_FREE_OBJECTID);

		mutex_unlock(&tree_root->objectid_mutex);



		ret = btrfs_read_roots(fs_info);

		if (ret < 0) {

			handle_error = true;

			continue;

		}



		/* All successful */

		fs_info->generation = generation;

		fs_info->last_trans_committed = generation;

		break;

	}



	return ret;

}



int __cold open_ctree(struct super_block *sb,

	       struct btrfs_fs_devices *fs_devices,

	       char *options)
@@ -2628,8 +2711,6 @@ int __cold open_ctree(struct super_block *sb, 
	struct btrfs_root *chunk_root;

	int ret;

	int err = -EINVAL;

	int num_backups_tried = 0;

	int backup_index = 0;

	int clear_free_space_tree = 0;

	int level;
@@ -3051,44 +3132,9 @@ int __cold open_ctree(struct super_block *sb, 
		goto fail_tree_roots;

	}



retry_root_backup:

	generation = btrfs_super_generation(disk_super);

	level = btrfs_super_root_level(disk_super);



	tree_root->node = read_tree_block(fs_info,

					  btrfs_super_root(disk_super),

					  generation, level, NULL);

	if (IS_ERR(tree_root->node) ||

	    !extent_buffer_uptodate(tree_root->node)) {

		btrfs_warn(fs_info, "failed to read tree root");

		if (!IS_ERR(tree_root->node))

			free_extent_buffer(tree_root->node);

		tree_root->node = NULL;

		goto recovery_tree_root;

	}



	btrfs_set_root_node(&tree_root->root_item, tree_root->node);

	tree_root->commit_root = btrfs_root_node(tree_root);

	btrfs_set_root_refs(&tree_root->root_item, 1);



	mutex_lock(&tree_root->objectid_mutex);

	ret = btrfs_find_highest_objectid(tree_root,

					&tree_root->highest_objectid);

	if (ret) {

		mutex_unlock(&tree_root->objectid_mutex);

		goto recovery_tree_root;

	}



	ASSERT(tree_root->highest_objectid <= BTRFS_LAST_FREE_OBJECTID);



	mutex_unlock(&tree_root->objectid_mutex);



	ret = btrfs_read_roots(fs_info);

	ret = init_tree_roots(fs_info);

	if (ret)

		goto recovery_tree_root;



	fs_info->generation = generation;

	fs_info->last_trans_committed = generation;

		goto fail_tree_roots;



	ret = btrfs_verify_dev_extents(fs_info);

	if (ret) {
@@ -3383,24 +3429,6 @@ fail: 
	btrfs_free_stripe_hash_table(fs_info);

	btrfs_close_devices(fs_info->fs_devices);

	return err;



recovery_tree_root:

	if (!btrfs_test_opt(fs_info, USEBACKUPROOT))

		goto fail_tree_roots;



	free_root_pointers(fs_info, false);



	/* don't use the log in recovery mode, it won't be valid */

	btrfs_set_super_log_root(disk_super, 0);



	/* we can't trust the free space cache either */

	btrfs_set_opt(fs_info->mount_opt, CLEAR_CACHE);



	ret = next_root_backup(fs_info, fs_info->super_copy,

			       &num_backups_tried, &backup_index);

	if (ret == -1)

		goto fail_block_groups;

	goto retry_root_backup;

}

ALLOW_ERROR_INJECTION(open_ctree, ERRNO);

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