CONFIG_DM_BIO_PRISON (not configurable)

modulename: dm-bio-prison.ko

configname: CONFIG_DM_BIO_PRISON

Linux Kernel Configuration
└─>Device Drivers
└─>Multiple devices driver support (RAID and LVM)
└─>DM_BIO_PRISON
In linux kernel since version 3.1 (release Date: 2011-10-24)  
Some bio locking schemes used by other device-mapper targets
including thin provisioning.

source code:
drivers/md/