BVEC_POOL_BITS 243 include/linux/blk_types.h #define BVEC_POOL_OFFSET (16 - BVEC_POOL_BITS) BVEC_POOL_BITS 245 include/linux/blk_types.h #if (1<< BVEC_POOL_BITS) < (BVEC_POOL_NR+1)