diff --git a/sys/cam/ctl/ctl_backend_block.c b/sys/cam/ctl/ctl_backend_block.c
index d98bd3a5aac9..d7526127e445 100644
--- a/sys/cam/ctl/ctl_backend_block.c
+++ b/sys/cam/ctl/ctl_backend_block.c
@@ -103,6 +103,9 @@ __FBSDID("$FreeBSD$");
 #define DPRINTF(fmt, args...) do {} while(0)
 #endif
 
+#define PRIV(io)	\
+    ((struct ctl_ptr_len_flags *)&(io)->io_hdr.ctl_private[CTL_PRIV_BACKEND])
+
 SDT_PROVIDER_DEFINE(cbb);
 
 typedef enum {
@@ -356,9 +359,7 @@ ctl_be_block_move_done(union ctl_io *io)
 	struct bintime cur_bt;
 #endif  
 
-	beio = (struct ctl_be_block_io *)
-		io->io_hdr.ctl_private[CTL_PRIV_BACKEND].ptr;
-
+	beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
 	be_lun = beio->lun;
 
 	DPRINTF("entered\n");
@@ -932,7 +933,7 @@ ctl_be_block_cw_dispatch_ws(struct ctl_be_block_lun *be_lun,
 
 	DPRINTF("entered\n");
 
-	beio = io->io_hdr.ctl_private[CTL_PRIV_BACKEND].ptr;
+	beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
 	softc = be_lun->softc;
 	lbalen = (struct ctl_lba_len_flags *)&io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];
 
@@ -1039,7 +1040,7 @@ ctl_be_block_cw_dispatch_unmap(struct ctl_be_block_lun *be_lun,
 
 	DPRINTF("entered\n");
 
-	beio = io->io_hdr.ctl_private[CTL_PRIV_BACKEND].ptr;
+	beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
 	softc = be_lun->softc;
 	ptrlen = (struct ctl_ptr_len_flags *)&io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];
 
@@ -1114,7 +1115,7 @@ ctl_be_block_cw_dispatch(struct ctl_be_block_lun *be_lun,
 	beio->io = io;
 	beio->lun = be_lun;
 	beio->beio_cont = ctl_be_block_cw_done;
-	io->io_hdr.ctl_private[CTL_PRIV_BACKEND].ptr = beio;
+	PRIV(io)->ptr = (void *)beio;
 
 	switch (io->scsiio.cdb[0]) {
 	case SYNCHRONIZE_CACHE:
@@ -1181,7 +1182,8 @@ ctl_be_block_dispatch(struct ctl_be_block_lun *be_lun,
 	struct ctl_be_block_io *beio;
 	struct ctl_be_block_softc *softc;
 	struct ctl_lba_len *lbalen;
-	uint64_t len_left, lbaoff;
+	struct ctl_ptr_len_flags *bptrlen;
+	uint64_t len_left, lbas;
 	int i;
 
 	softc = be_lun->softc;
@@ -1197,7 +1199,8 @@ ctl_be_block_dispatch(struct ctl_be_block_lun *be_lun,
 	beio = ctl_alloc_beio(softc);
 	beio->io = io;
 	beio->lun = be_lun;
-	io->io_hdr.ctl_private[CTL_PRIV_BACKEND].ptr = beio;
+	bptrlen = PRIV(io);
+	bptrlen->ptr = (void *)beio;
 
 	/*
 	 * If the I/O came down with an ordered or head of queue tag, set
@@ -1243,12 +1246,12 @@ ctl_be_block_dispatch(struct ctl_be_block_lun *be_lun,
 	lbalen = (struct ctl_lba_len *)&io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];
 	DPRINTF("%s at LBA %jx len %u @%ju\n",
 	       (beio->bio_cmd == BIO_READ) ? "READ" : "WRITE",
-	       (uintmax_t)lbalen->lba, lbalen->len, lbaoff);
-	lbaoff = io->scsiio.kern_rel_offset / be_lun->blocksize;
-	beio->io_offset = (lbalen->lba + lbaoff) * be_lun->blocksize;
-	beio->io_len = MIN((lbalen->len - lbaoff) * be_lun->blocksize,
-	    CTLBLK_MAX_IO_SIZE);
-	beio->io_len -= beio->io_len % be_lun->blocksize;
+	       (uintmax_t)lbalen->lba, lbalen->len, bptrlen->len);
+	lbas = MIN(lbalen->len - bptrlen->len,
+	    CTLBLK_MAX_IO_SIZE / be_lun->blocksize);
+	beio->io_offset = (lbalen->lba + bptrlen->len) * be_lun->blocksize;
+	beio->io_len = lbas * be_lun->blocksize;
+	bptrlen->len += lbas;
 
 	for (i = 0, len_left = beio->io_len; len_left > 0; i++) {
 		KASSERT(i < CTLBLK_MAX_SEGS, ("Too many segs (%d >= %d)",
@@ -1266,8 +1269,7 @@ ctl_be_block_dispatch(struct ctl_be_block_lun *be_lun,
 		beio->num_segs++;
 		len_left -= beio->sg_segs[i].len;
 	}
-	if (io->scsiio.kern_rel_offset + beio->io_len <
-	    io->scsiio.kern_total_len)
+	if (bptrlen->len < lbalen->len)
 		beio->beio_cont = ctl_be_block_next;
 	io->scsiio.be_move_done = ctl_be_block_move_done;
 	io->scsiio.kern_data_ptr = (uint8_t *)beio->sg_segs;
@@ -1318,8 +1320,7 @@ ctl_be_block_worker(void *context, int pending)
 
 			mtx_unlock(&be_lun->lock);
 
-			beio = (struct ctl_be_block_io *)
-			    io->io_hdr.ctl_private[CTL_PRIV_BACKEND].ptr;
+			beio = (struct ctl_be_block_io *)PRIV(io)->ptr;
 
 			be_lun->dispatch(be_lun, beio);
 
@@ -1391,6 +1392,8 @@ ctl_be_block_submit(union ctl_io *io)
 	KASSERT(io->io_hdr.io_type == CTL_IO_SCSI, ("Non-SCSI I/O (type "
 		"%#x) encountered", io->io_hdr.io_type));
 
+	PRIV(io)->len = 0;
+
 	mtx_lock(&be_lun->lock);
 	/*
 	 * XXX KDM make sure that links is okay to use at this point.
diff --git a/sys/cam/ctl/ctl_backend_ramdisk.c b/sys/cam/ctl/ctl_backend_ramdisk.c
index bf51a1866477..ac03f3acca60 100644
--- a/sys/cam/ctl/ctl_backend_ramdisk.c
+++ b/sys/cam/ctl/ctl_backend_ramdisk.c
@@ -241,7 +241,7 @@ ctl_backend_ramdisk_move_done(union ctl_io *io)
 	if ((io->io_hdr.port_status == 0)
 	 && ((io->io_hdr.flags & CTL_FLAG_ABORT) == 0)
 	 && ((io->io_hdr.status & CTL_STATUS_MASK) == CTL_STATUS_NONE)) {
-		if (io->scsiio.kern_rel_offset < io->scsiio.kern_total_len) {
+		if (io->io_hdr.ctl_private[CTL_PRIV_BACKEND].integer > 0) {
 			mtx_lock(&be_lun->lock);
 			STAILQ_INSERT_TAIL(&be_lun->cont_queue,
 			    &io->io_hdr, links);
@@ -274,7 +274,14 @@ ctl_backend_ramdisk_move_done(union ctl_io *io)
 static int
 ctl_backend_ramdisk_submit(union ctl_io *io)
 {
+	struct ctl_be_lun *ctl_be_lun;
+	struct ctl_lba_len *lbalen;
 
+	ctl_be_lun = (struct ctl_be_lun *)io->io_hdr.ctl_private[
+		CTL_PRIV_BACKEND_LUN].ptr;
+	lbalen = (struct ctl_lba_len *)&io->io_hdr.ctl_private[CTL_PRIV_LBA_LEN];
+	io->io_hdr.ctl_private[CTL_PRIV_BACKEND].integer =
+	    lbalen->len * ctl_be_lun->blocksize;
 	ctl_backend_ramdisk_continue(io);
 	return (CTL_RETVAL_COMPLETE);
 }
@@ -290,7 +297,7 @@ ctl_backend_ramdisk_continue(union ctl_io *io)
 #endif
 
 	softc = &rd_softc;
-	len = io->scsiio.kern_total_len - io->scsiio.kern_rel_offset;
+	len = io->io_hdr.ctl_private[CTL_PRIV_BACKEND].integer;
 #ifdef CTL_RAMDISK_PAGES
 	sg_filled = min(btoc(len), softc->num_pages);
 	if (sg_filled > 1) {
@@ -321,6 +328,7 @@ ctl_backend_ramdisk_continue(union ctl_io *io)
 	io->scsiio.kern_data_len = len_filled;
 	io->scsiio.kern_sg_entries = sg_filled;
 	io->io_hdr.flags |= CTL_FLAG_ALLOCATED;
+	io->io_hdr.ctl_private[CTL_PRIV_BACKEND].integer -= len_filled;
 #ifdef CTL_TIME_IO
 	getbintime(&io->io_hdr.dma_start_bt);
 #endif