Comment 7 for bug 1377142

Hm, it was helping in my case. So here from my re-run with utopic KVM host:

# lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 16G 0 disk
└─bcache0 251:0 0 8G 0 disk /mnt
sdb 8:16 0 8G 0 disk
└─bcache0 251:0 0 8G 0 disk /mnt

# bcache-super-show /dev/sda
sb.magic ok
sb.first_sector 8 [match]
sb.csum 29533C7B4D0F16EA [match]
sb.version 3 [cache device]

dev.label (empty)
dev.uuid 91706fc8-39ae-4cbd-b0a0-8a202ee6a377
dev.sectors_per_block 1
dev.sectors_per_bucket 1024
dev.cache.first_sector 1024
dev.cache.cache_sectors 33553408
dev.cache.total_sectors 33554432
dev.cache.ordered yes
dev.cache.discard yes
dev.cache.pos 0
dev.cache.replacement 0 [lru]

cset.uuid a8f70bd1-48df-462f-9a2c-ca4b8af9059c

# bcache-super-show /dev/sdb
sb.magic ok
sb.first_sector 8 [match]
sb.csum 81BB0342C7270559 [match]
sb.version 1 [backing device]

dev.label (empty)
dev.uuid 4ae46f48-d11d-45ca-a1ec-905eaf8e1da8
dev.sectors_per_block 1
dev.sectors_per_bucket 1024
dev.data.first_sector 16
dev.data.cache_mode 1 [writeback]
dev.data.cache_state 1 [clean]

cset.uuid a8f70bd1-48df-462f-9a2c-ca4b8af9059c