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: Miao Xie <miaox@cn.fujitsu.com>
Signed-off-by: Chris Mason <chris.mason@fusionio.com>
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index 7b1f614..10bc65e 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -2843,12 +2843,19 @@
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 @@
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 @@
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 @@
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,