Commit 4addc1ff authored by David Sterba's avatar David Sterba
Browse files

btrfs: qgroup: preallocate memory before adding a relation 



There's a transaction joined in the qgroup relation add/remove ioctl and
any error will lead to abort/error. We could lift the allocation from
btrfs_add_qgroup_relation() and move it outside of the transaction
context. The relation deletion does not need that.

The ownership of the structure is moved to the add relation handler.

Reviewed-by: default avatarQu Wenruo <wqu@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 7733b8dd

fs/btrfs/ioctl.c

+16 −1
Original line number Diff line number Diff line
@@ -3829,6 +3829,7 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg) 
	struct btrfs_fs_info *fs_info = inode_to_fs_info(inode);

	struct btrfs_root *root = BTRFS_I(inode)->root;

	struct btrfs_ioctl_qgroup_assign_args *sa;

	struct btrfs_qgroup_list *prealloc = NULL;

	struct btrfs_trans_handle *trans;

	int ret;

	int err;
@@ -3849,14 +3850,27 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg) 
		goto drop_write;

	}



	if (sa->assign) {

		prealloc = kzalloc(sizeof(*prealloc), GFP_KERNEL);

		if (!prealloc) {

			ret = -ENOMEM;

			goto drop_write;

		}

	}



	trans = btrfs_join_transaction(root);

	if (IS_ERR(trans)) {

		ret = PTR_ERR(trans);

		goto out;

	}



	/*

	 * Prealloc ownership is moved to the relation handler, there it's used

	 * or freed on error.

	 */

	if (sa->assign) {

		ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst);

		ret = btrfs_add_qgroup_relation(trans, sa->src, sa->dst, prealloc);

		prealloc = NULL;

	} else {

		ret = btrfs_del_qgroup_relation(trans, sa->src, sa->dst);

	}
@@ -3873,6 +3887,7 @@ static long btrfs_ioctl_qgroup_assign(struct file *file, void __user *arg) 
		ret = err;



out:

	kfree(prealloc);

	kfree(sa);

drop_write:

	mnt_drop_write_file(file);

fs/btrfs/qgroup.c

+8 −17
Original line number Diff line number Diff line
@@ -155,16 +155,6 @@ static inline u64 btrfs_qgroup_get_new_refcnt(const struct btrfs_qgroup *qg, u64 
	return qg->new_refcnt - seq;

}



/*

 * glue structure to represent the relations between qgroups.

 */

struct btrfs_qgroup_list {

	struct list_head next_group;

	struct list_head next_member;

	struct btrfs_qgroup *group;

	struct btrfs_qgroup *member;

};



static int

qgroup_rescan_init(struct btrfs_fs_info *fs_info, u64 progress_objectid,

		   int init_flags);
@@ -1569,15 +1559,21 @@ static int quick_update_accounting(struct btrfs_fs_info *fs_info, 
	return ret;

}



int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst)

/*

 * Add relation between @src and @dst qgroup. The @prealloc is allocated by the

 * callers and transferred here (either used or freed on error).

 */

int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst,

			      struct btrfs_qgroup_list *prealloc)

{

	struct btrfs_fs_info *fs_info = trans->fs_info;

	struct btrfs_qgroup *parent;

	struct btrfs_qgroup *member;

	struct btrfs_qgroup_list *list;

	struct btrfs_qgroup_list *prealloc = NULL;

	int ret = 0;



	ASSERT(prealloc);



	/* Check the level of src and dst first */

	if (btrfs_qgroup_level(src) >= btrfs_qgroup_level(dst))

		return -EINVAL;
@@ -1602,11 +1598,6 @@ int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst 
		}

	}



	prealloc = kzalloc(sizeof(*list), GFP_NOFS);

	if (!prealloc) {

		ret = -ENOMEM;

		goto out;

	}

	ret = add_qgroup_relation_item(trans, src, dst);

	if (ret)

		goto out;

fs/btrfs/qgroup.h

+10 −1
Original line number Diff line number Diff line
@@ -278,6 +278,14 @@ struct btrfs_qgroup { 
	struct kobject kobj;

};



/* Glue structure to represent the relations between qgroups. */

struct btrfs_qgroup_list {

	struct list_head next_group;

	struct list_head next_member;

	struct btrfs_qgroup *group;

	struct btrfs_qgroup *member;

};



struct btrfs_squota_delta {

	/* The fstree root this delta counts against. */

	u64 root;
@@ -321,7 +329,8 @@ int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info); 
void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);

int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,

				     bool interruptible);

int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst);

int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans, u64 src, u64 dst,

			      struct btrfs_qgroup_list *prealloc);

int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans, u64 src,

			      u64 dst);

int btrfs_create_qgroup(struct btrfs_trans_handle *trans, u64 qgroupid);