ubifs: regression: unable to mount ubifs

[Hauke Mehrtens]

The commit 322ea0bb "mtd: switch ubi_open_volume_path() to vfs_stat()"
breaks mounting ubifs volumes for me.

On kernel 4.7-rc3 I am getting the following error when trying to mount
an ubifs volume. This volume in on a ubi file system which exports it as
a mtd partition.

root at lede:/# mkdir /tmp/test
root at lede:/# mount -t ubifs /dev/ubi0_10 /tmp/test/
[  178.782184] UBIFS error (pid: 955): cannot open "/dev/ubi0_10", error
-22mount: mounting /dev/ubi0_10 on /tmp/test/ failed: Invalid argument
root at lede:/#

In the function ubi_open_volume_path() the call to vfs_stat() returns
-EFAULT.

After I reverted commit 322ea0bb it works again.

Hauke