Btrfs: fix wrong error returned by adding a device

Reproduce:
$ mkfs.btrfs /dev/sdb7
$ mount /dev/sdb7 /mnt/btrfs -o ro
$ btrfs dev add /dev/sdb8 /mnt/btrfs
ERROR: error adding the device '/dev/sdb8' - Invalid argument

Since we mount with readonly options, and /dev/sdb7 is not a seeding one,
a readonly notification is preferred.

Signed-off-by: Liu Bo <liubo2009@cn.fujitsu.com>
Reviewed-by: Josef Bacik <josef@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 1411b99555a4..48a06d1fc067 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -1633,7 +1633,7 @@ int btrfs_init_new_device(struct btrfs_root *root, char *device_path)
         int ret = 0;
 
         if ((sb->s_flags & MS_RDONLY) && !root->fs_info->fs_devices->seeding)
-                return -EINVAL;
+                return -EROFS;
 
         bdev = blkdev_get_by_path(device_path, FMODE_WRITE | FMODE_EXCL,
                                   root->fs_info->bdev_holder);