Comment # 1 on bug 1000907 from Aurelien Aptel

This is probably due to a regression introduced with my prefix path patch :(

Fix is commit 8d3ba6b in git://git.samba.org/sfrench/cifs-2.6.git for-next.

You most likely want these too (apply first, in that order)

348c1bf - Move check for prefix path to within cifs_get_root()
c1d8b24 - Compare prepaths when comparing superblocks
4214ebf - Fix memory leaks in cifs_do_mount()