[zfs] Cache on SD stops working after updating to 11-CURRENT r291458 amd64

Hi,

I use a SD card as cache for a laptop pool sys:

# zpool status -v

 pool: sys

state: ONLINE

 scan: scrub repaired 0 in 1h13m with 0 errors on Mon Jan  4 00:02:42 2016

config:

       NAME         STATE     READ WRITE CKSUM

       sys          ONLINE       0     0     0

         gpt/sys0   ONLINE       0     0     0

       cache

         gpt/cache  ONLINE       0     0     0


After updating 11.0-CURRENT from r291458 to r293055 the cache stops working.

I am running:

# uname -a

FreeBSD ativ 11.0-CURRENT FreeBSD 11.0-CURRENT #0 r293055: Sun Jan  3
00:15:33 CET 2016     root_at_ativ:/usr/obj/usr/src/sys/GENERIC  amd64

Fault cache status after the boot:

# zpool status -v


 pool: sys

state: ONLINE

status: One or more devices could not be opened.  Sufficient replicas exist
for

       the pool to continue functioning in a degraded state.

action: Attach the missing device and online it using 'zpool online'.

  see: http://illumos.org/msg/ZFS-8000-2Q

 scan: scrub repaired 0 in 1h13m with 0 errors on Mon Jan  4 00:02:42 2016

config:

       NAME                   STATE     READ WRITE CKSUM

       sys                    ONLINE       0     0     0

         gpt/sys0             ONLINE       0     0     0

       cache

         1553023247900193278  UNAVAIL      0     0     0  was /dev/gpt/cache

errors: No known data errors


Trying to online the cache I have the error:

# zpool online sys gpt/cache

warning: device 'gpt/cache' onlined, but remains in faulted state

use 'zpool replace' to replace devices that are no longer present


To use the cache I need to remove & add it:

# zpool remove sys gpt/cache

# zpool add sys cache gpt/cache

--
Maurizio