MS_BLOCK_MAX_SEGS
.max_segments = MS_BLOCK_MAX_SEGS,
sg_init_table(msb->prealloc_sg, MS_BLOCK_MAX_SEGS+1);
sg_init_table(msb->prealloc_sg, MS_BLOCK_MAX_SEGS+1);
struct scatterlist prealloc_sg[MS_BLOCK_MAX_SEGS+1];