Commit 3c04ce01 authored by Miao Xie's avatar Miao Xie Committed by Chris Mason
Browse files

Btrfs: get write access when setting the default subvolume 



When wen want to set the default subvolume, we must get write access, or
we will change the R/O file system.

Signed-off-by: default avatarMiao Xie <miaox@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <chris.mason@fusionio.com>
parent 8cd2807f

fs/btrfs/ioctl.c

+28 −12
Original line number Diff line number Diff line
@@ -2843,12 +2843,19 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp) 
	struct btrfs_disk_key disk_key;

	u64 objectid = 0;

	u64 dir_id;

	int ret;



	if (!capable(CAP_SYS_ADMIN))

		return -EPERM;



	if (copy_from_user(&objectid, argp, sizeof(objectid)))

		return -EFAULT;

	ret = mnt_want_write_file(file);

	if (ret)

		return ret;



	if (copy_from_user(&objectid, argp, sizeof(objectid))) {

		ret = -EFAULT;

		goto out;

	}



	if (!objectid)

		objectid = root->root_key.objectid;
@@ -2858,21 +2865,28 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp) 
	location.offset = (u64)-1;



	new_root = btrfs_read_fs_root_no_name(root->fs_info, &location);

	if (IS_ERR(new_root))

		return PTR_ERR(new_root);

	if (IS_ERR(new_root)) {

		ret = PTR_ERR(new_root);

		goto out;

	}



	if (btrfs_root_refs(&new_root->root_item) == 0)

		return -ENOENT;

	if (btrfs_root_refs(&new_root->root_item) == 0) {

		ret = -ENOENT;

		goto out;

	}



	path = btrfs_alloc_path();

	if (!path)

		return -ENOMEM;

	if (!path) {

		ret = -ENOMEM;

		goto out;

	}

	path->leave_spinning = 1;



	trans = btrfs_start_transaction(root, 1);

	if (IS_ERR(trans)) {

		btrfs_free_path(path);

		return PTR_ERR(trans);

		ret = PTR_ERR(trans);

		goto out;

	}



	dir_id = btrfs_super_root_dir(root->fs_info->super_copy);
@@ -2883,7 +2897,8 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp) 
		btrfs_end_transaction(trans, root);

		printk(KERN_ERR "Umm, you don't have the default dir item, "

		       "this isn't going to work\n");

		return -ENOENT;

		ret = -ENOENT;

		goto out;

	}



	btrfs_cpu_key_to_disk(&disk_key, &new_root->root_key);
@@ -2893,8 +2908,9 @@ static long btrfs_ioctl_default_subvol(struct file *file, void __user *argp) 


	btrfs_set_fs_incompat(root->fs_info, DEFAULT_SUBVOL);

	btrfs_end_transaction(trans, root);



	return 0;

out:

	mnt_drop_write_file(file);

	return ret;

}



void btrfs_get_block_group_info(struct list_head *groups_list,