Commit 5ce14bbc authored by Chris Mason's avatar Chris Mason Committed by David Woodhouse
Browse files

Btrfs: Find and remove dead roots the first time a root is loaded. 



Dead roots are trees left over after a crash, and they were either in the
process of being removed or were waiting to be removed when the box crashed.
Before, a search of the entire tree of root pointers was done on mount
looking for dead roots.  Now, the search is done the first time we load
a root.

This makes mount faster when there are a large number of snapshots, and it
enables the block accounting code to properly update the block counts on
the latest root as old versions of the root are reaped after a crash.

Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 0e2752a7

fs/btrfs/ctree.h

+2 −1
Original line number Diff line number Diff line
@@ -1148,7 +1148,8 @@ int btrfs_update_root(struct btrfs_trans_handle *trans, struct btrfs_root 
		      *item);

int btrfs_find_last_root(struct btrfs_root *root, u64 objectid, struct

			 btrfs_root_item *item, struct btrfs_key *key);

int btrfs_find_dead_roots(struct btrfs_root *root);

int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,

			  struct btrfs_root *latest_root);

/* dir-item.c */

int btrfs_insert_dir_item(struct btrfs_trans_handle *trans, struct btrfs_root

			  *root, const char *name, int name_len, u64 dir,

fs/btrfs/disk-io.c

+4 −5
Original line number Diff line number Diff line
@@ -426,6 +426,10 @@ struct btrfs_root *btrfs_read_fs_root(struct btrfs_fs_info *fs_info, 
		return ERR_PTR(ret);

	}



	ret = btrfs_find_dead_roots(fs_info->tree_root,

				    root->root_key.objectid, root);

	BUG_ON(ret);



	return root;

}
@@ -522,11 +526,6 @@ struct btrfs_root *open_ctree(struct super_block *sb) 
	btrfs_read_block_groups(extent_root);



	fs_info->generation = btrfs_super_generation(disk_super) + 1;

	ret = btrfs_find_dead_roots(tree_root);

	if (ret) {

		mutex_unlock(&fs_info->fs_mutex);

		goto fail_tree_root;

	}

	mutex_unlock(&fs_info->fs_mutex);

	return tree_root;

fs/btrfs/root-tree.c

+13 −3
Original line number Diff line number Diff line
@@ -93,7 +93,8 @@ int btrfs_insert_root(struct btrfs_trans_handle *trans, struct btrfs_root 
	return ret;

}



int btrfs_find_dead_roots(struct btrfs_root *root)

int btrfs_find_dead_roots(struct btrfs_root *root, u64 objectid,

			  struct btrfs_root *latest)

{

	struct btrfs_root *dead_root;

	struct btrfs_item *item;
@@ -105,7 +106,7 @@ int btrfs_find_dead_roots(struct btrfs_root *root) 
	struct btrfs_leaf *leaf;

	int slot;



	key.objectid = 0;

	key.objectid = objectid;

	key.flags = 0;

	btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);

	key.offset = 0;
@@ -131,15 +132,24 @@ int btrfs_find_dead_roots(struct btrfs_root *root) 
		btrfs_disk_key_to_cpu(&key, &item->key);

		if (btrfs_key_type(&key) != BTRFS_ROOT_ITEM_KEY)

			goto next;



		if (key.objectid < objectid)

			goto next;



		if (key.objectid > objectid)

			break;



		ri = btrfs_item_ptr(leaf, slot, struct btrfs_root_item);

		if (btrfs_root_refs(ri) != 0)

			goto next;



		dead_root = btrfs_read_fs_root_no_radix(root->fs_info, &key);

		if (IS_ERR(dead_root)) {

			ret = PTR_ERR(dead_root);

			goto err;

		}

		ret = btrfs_add_dead_root(dead_root,



		ret = btrfs_add_dead_root(dead_root, latest,

					  &root->fs_info->dead_roots);

		if (ret)

			goto err;

fs/btrfs/transaction.c

+4 −2
Original line number Diff line number Diff line
@@ -239,7 +239,9 @@ struct dirty_root { 
	struct btrfs_root *latest_root;

};



int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list)

int btrfs_add_dead_root(struct btrfs_root *root,

			struct btrfs_root *latest,

			struct list_head *dead_list)

{

	struct dirty_root *dirty;
@@ -247,6 +249,7 @@ int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list) 
	if (!dirty)

		return -ENOMEM;

	dirty->root = root;

	dirty->latest_root = latest;

	list_add(&dirty->list, dead_list);

	return 0;

}
@@ -412,7 +415,6 @@ static int drop_dirty_roots(struct btrfs_root *tree_root, 


		while(1) {

			trans = btrfs_start_transaction(tree_root, 1);



			ret = btrfs_drop_snapshot(trans, dirty->root);

			if (ret != -EAGAIN) {

				break;

fs/btrfs/transaction.h

+2 −1
Original line number Diff line number Diff line
@@ -78,7 +78,8 @@ void btrfs_transaction_flush_work(struct btrfs_root *root); 
void btrfs_transaction_queue_work(struct btrfs_root *root, int delay);

void btrfs_init_transaction_sys(void);

void btrfs_exit_transaction_sys(void);

int btrfs_add_dead_root(struct btrfs_root *root, struct list_head *dead_list);

int btrfs_add_dead_root(struct btrfs_root *root, struct btrfs_root *latest,

			struct list_head *dead_list);

int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info);

int btrfs_defrag_root(struct btrfs_root *root, int cacheonly);

int btrfs_clean_old_snapshots(struct btrfs_root *root);

CRA Git | Maintained and supported by SUSTech CRA and CCSE