Add asynchronous command support to the pass(4) driver, and the new

camdd(8) utility.

CCBs may be queued to the driver via the new CAMIOQUEUE ioctl, and
completed CCBs may be retrieved via the CAMIOGET ioctl.  User
processes can use poll(2) or kevent(2) to get notification when
I/O has completed.

While the existing CAMIOCOMMAND blocking ioctl interface only
supports user virtual data pointers in a CCB (generally only
one per CCB), the new CAMIOQUEUE ioctl supports user virtual and
physical address pointers, as well as user virtual and physical
scatter/gather lists.  This allows user applications to have more
flexibility in their data handling operations.

Kernel memory for data transferred via the queued interface is
allocated from the zone allocator in MAXPHYS sized chunks, and user
data is copied in and out.  This is likely faster than the
vmapbuf()/vunmapbuf() method used by the CAMIOCOMMAND ioctl in
configurations with many processors (there are more TLB shootdowns
caused by the mapping/unmapping operation) but may not be as fast
as running with unmapped I/O.

The new memory handling model for user requests also allows
applications to send CCBs with request sizes that are larger than
MAXPHYS.  The pass(4) driver now limits queued requests to the I/O
size listed by the SIM driver in the maxio field in the Path
Inquiry (XPT_PATH_INQ) CCB.

There are some things things would be good to add:

1. Come up with a way to do unmapped I/O on multiple buffers.
   Currently the unmapped I/O interface operates on a struct bio,
   which includes only one address and length.  It would be nice
   to be able to send an unmapped scatter/gather list down to
   busdma.  This would allow eliminating the copy we currently do
   for data.

2. Add an ioctl to list currently outstanding CCBs in the various
   queues.

3. Add an ioctl to cancel a request, or use the XPT_ABORT CCB to do
   that.

4. Test physical address support.  Virtual pointers and scatter
   gather lists have been tested, but I have not yet tested
   physical addresses or scatter/gather lists.

5. Investigate multiple queue support.  At the moment there is one
   queue of commands per pass(4) device.  If multiple processes
   open the device, they will submit I/O into the same queue and
   get events for the same completions.  This is probably the right
   model for most applications, but it is something that could be
   changed later on.

Also, add a new utility, camdd(8) that uses the asynchronous pass(4)
driver interface.

This utility is intended to be a basic data transfer/copy utility,
a simple benchmark utility, and an example of how to use the
asynchronous pass(4) interface.

It can copy data to and from pass(4) devices using any target queue
depth, starting offset and blocksize for the input and ouptut devices.
It currently only supports SCSI devices, but could be easily extended
to support ATA devices.

It can also copy data to and from regular files, block devices, tape
devices, pipes, stdin, and stdout.  It does not support queueing
multiple commands to any of those targets, since it uses the standard
read(2)/write(2)/writev(2)/readv(2) system calls.

The I/O is done by two threads, one for the reader and one for the
writer.  The reader thread sends completed read requests to the
writer thread in strictly sequential order, even if they complete
out of order.  That could be modified later on for random I/O patterns
or slightly out of order I/O.

camdd(8) uses kqueue(2)/kevent(2) to get I/O completion events from
the pass(4) driver and also to send request notifications internally.

For pass(4) devcies, camdd(8) uses a single buffer (CAM_DATA_VADDR)
per CAM CCB on the reading side, and a scatter/gather list
(CAM_DATA_SG) on the writing side.  In addition to testing both
interfaces, this makes any potential reblocking of I/O easier.  No
data is copied between the reader and the writer, but rather the
reader's buffers are split into multiple I/O requests or combined
into a single I/O request depending on the input and output blocksize.

For the file I/O path, camdd(8) also uses a single buffer (read(2),
write(2), pread(2) or pwrite(2)) on reads, and a scatter/gather list
(readv(2), writev(2), preadv(2), pwritev(2)) on writes.

Things that would be nice to do for camdd(8) eventually:

1.  Add support for I/O pattern generation.  Patterns like all
    zeros, all ones, LBA-based patterns, random patterns, etc. Right
    Now you can always use /dev/zero, /dev/random, etc.

2.  Add support for a "sink" mode, so we do only reads with no
    writes.  Right now, you can use /dev/null.

3.  Add support for automatic queue depth probing, so that we can
    figure out the right queue depth on the input and output side
    for maximum throughput.  At the moment it defaults to 6.

4.  Add support for SATA device passthrough I/O.

5.  Add support for random LBAs and/or lengths on the input and
    output sides.

6.  Track average per-I/O latency and busy time.  The busy time
    and latency could also feed in to the automatic queue depth
    determination.

sys/cam/scsi/scsi_pass.h:
	Define two new ioctls, CAMIOQUEUE and CAMIOGET, that queue
	and fetch asynchronous CAM CCBs respectively.

	Although these ioctls do not have a declared argument, they
	both take a union ccb pointer.  If we declare a size here,
	the ioctl code in sys/kern/sys_generic.c will malloc and free
	a buffer for either the CCB or the CCB pointer (depending on
	how it is declared).  Since we have to keep a copy of the
	CCB (which is fairly large) anyway, having the ioctl malloc
	and free a CCB for each call is wasteful.

sys/cam/scsi/scsi_pass.c:
	Add asynchronous CCB support.

	Add two new ioctls, CAMIOQUEUE and CAMIOGET.

	CAMIOQUEUE adds a CCB to the incoming queue.  The CCB is
	executed immediately (and moved to the active queue) if it
	is an immediate CCB, but otherwise it will be executed
	in passstart() when a CCB is available from the transport layer.

	When CCBs are completed (because they are immediate or
	passdone() if they are queued), they are put on the done
	queue.

	If we get the final close on the device before all pending
	I/O is complete, all active I/O is moved to the abandoned
	queue and we increment the peripheral reference count so
	that the peripheral driver instance doesn't go away before
	all pending I/O is done.

	The new passcreatezone() function is called on the first
	call to the CAMIOQUEUE ioctl on a given device to allocate
	the UMA zones for I/O requests and S/G list buffers.  This
	may be good to move off to a taskqueue at some point.
	The new passmemsetup() function allocates memory and
	scatter/gather lists to hold the user's data, and copies
	in any data that needs to be written.  For virtual pointers
	(CAM_DATA_VADDR), the kernel buffer is malloced from the
	new pass(4) driver malloc bucket.  For virtual
	scatter/gather lists (CAM_DATA_SG), buffers are allocated
	from a new per-pass(9) UMA zone in MAXPHYS-sized chunks.
	Physical pointers are passed in unchanged.  We have support
	for up to 16 scatter/gather segments (for the user and
	kernel S/G lists) in the default struct pass_io_req, so
	requests with longer S/G lists require an extra kernel malloc.

	The new passcopysglist() function copies a user scatter/gather
	list to a kernel scatter/gather list.  The number of elements
	in each list may be different, but (obviously) the amount of data
	stored has to be identical.

	The new passmemdone() function copies data out for the
	CAM_DATA_VADDR and CAM_DATA_SG cases.

	The new passiocleanup() function restores data pointers in
	user CCBs and frees memory.

	Add new functions to support kqueue(2)/kevent(2):

	passreadfilt() tells kevent whether or not the done
	queue is empty.

	passkqfilter() adds a knote to our list.

	passreadfiltdetach() removes a knote from our list.

	Add a new function, passpoll(), for poll(2)/select(2)
	to use.

	Add devstat(9) support for the queued CCB path.

sys/cam/ata/ata_da.c:
	Add support for the BIO_VLIST bio type.

sys/cam/cam_ccb.h:
	Add a new enumeration for the xflags field in the CCB header.
	(This doesn't change the CCB header, just adds an enumeration to
	use.)

sys/cam/cam_xpt.c:
	Add a new function, xpt_setup_ccb_flags(), that allows specifying
	CCB flags.

sys/cam/cam_xpt.h:
	Add a prototype for xpt_setup_ccb_flags().

sys/cam/scsi/scsi_da.c:
	Add support for BIO_VLIST.

sys/dev/md/md.c:
	Add BIO_VLIST support to md(4).

sys/geom/geom_disk.c:
	Add BIO_VLIST support to the GEOM disk class.  Re-factor the I/O size
	limiting code in g_disk_start() a bit.

sys/kern/subr_bus_dma.c:
	Change _bus_dmamap_load_vlist() to take a starting offset and
	length.

	Add a new function, _bus_dmamap_load_pages(), that will load a list
	of physical pages starting at an offset.

	Update _bus_dmamap_load_bio() to allow loading BIO_VLIST bios.
	Allow unmapped I/O to start at an offset.

sys/kern/subr_uio.c:
	Add two new functions, physcopyin_vlist() and physcopyout_vlist().

sys/pc98/include/bus.h:
	Guard kernel-only parts of the pc98 machine/bus.h header with
	#ifdef _KERNEL.

	This allows userland programs to include <machine/bus.h> to get the
	definition of bus_addr_t and bus_size_t.

sys/sys/bio.h:
	Add a new bio flag, BIO_VLIST.

sys/sys/uio.h:
	Add prototypes for physcopyin_vlist() and physcopyout_vlist().

share/man/man4/pass.4:
	Document the CAMIOQUEUE and CAMIOGET ioctls.

usr.sbin/Makefile:
	Add camdd.

usr.sbin/camdd/Makefile:
	Add a makefile for camdd(8).

usr.sbin/camdd/camdd.8:
	Man page for camdd(8).

usr.sbin/camdd/camdd.c:
	The new camdd(8) utility.

Sponsored by:	Spectra Logic
MFC after:	1 week

4 files changed, 3723 insertions, 0 deletions

diff --git a/usr.sbin/Makefile b/usr.sbin/Makefile
index 8cebd61..3bec616 100644
--- a/usr.sbin/Makefile
+++ b/usr.sbin/Makefile
@@ -7,6 +7,7 @@ SUBDIR=	adduser \
 	arp \
 	binmiscctl \
 	bsdconfig \
+	camdd \
 	cdcontrol \
 	chkgrp \
 	chown \
diff --git a/usr.sbin/camdd/Makefile b/usr.sbin/camdd/Makefile
new file mode 100644
index 0000000..0028668
--- /dev/null
+++ b/usr.sbin/camdd/Makefile
@@ -0,0 +1,11 @@
+# $FreeBSD$
+
+PROG=	camdd
+SRCS=	camdd.c
+SDIR=	${.CURDIR}/../../sys
+DPADD=	${LIBCAM} ${LIBMT} ${LIBSBUF} ${LIBBSDXML} ${LIBUTIL} ${LIBTHR}
+LDADD=	-lcam -lmt -lsbuf -lbsdxml -lutil -lthr
+NO_WTHREAD_SAFETY=	1
+MAN=	camdd.8
+
+.include <bsd.prog.mk>
diff --git a/usr.sbin/camdd/camdd.8 b/usr.sbin/camdd/camdd.8
new file mode 100644
index 0000000..af556bb
--- /dev/null
+++ b/usr.sbin/camdd/camdd.8
@@ -0,0 +1,283 @@
+.\" 
+.\" Copyright (c) 2015 Spectra Logic Corporation
+.\" All rights reserved.
+.\" 
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions, and the following disclaimer,
+.\"    without modification.
+.\" 2. Redistributions in binary form must reproduce at minimum a disclaimer
+.\"    substantially similar to the "NO WARRANTY" disclaimer below
+.\"    ("Disclaimer") and any redistribution must be conditioned upon
+.\"    including a substantially similar Disclaimer requirement for further
+.\"    binary redistribution.
+.\" 
+.\" NO WARRANTY
+.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+.\" "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+.\" LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
+.\" A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+.\" HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+.\" IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+.\" POSSIBILITY OF SUCH DAMAGES.
+.\" 
+.\" Authors: Ken Merry           (Spectra Logic Corporation)
+.\" 
+.\" $FreeBSD$
+.\"
+.Dd November 11, 2015
+.Dt CAMDD 8
+.Os
+.Sh NAME
+.Nm camdd
+.Nd CAM data transfer utility
+.Sh SYNOPSIS
+.Nm
+.Aq Fl i|o Ar pass=pass_dev|file=filename,bs=blocksize,[...]
+.Op Fl C Ar retry_count
+.Op Fl E
+.Op Fl m Ar max_io
+.Op Fl t Ar timeout
+.Op Fl v
+.Op Fl h
+.Sh DESCRIPTION
+The
+.Nm
+utility is a sequential data transfer utility that offers standard
+.Xr read 2
+and
+.Xr write 2
+operation in addition to a mode that uses the asynchronous
+.Xr pass 4
+API.
+The asynchronous
+.Xr pass 4
+API allows multiple requests to be queued to a device simultaneously.
+.Pp
+.Nm
+collects performance information and will display it when the transfer
+completes, when
+.Nm
+is terminated or when it receives a SIGINFO signal.
+.Pp
+The following options are available:
+.Bl -tag -width 12n
+.It Fl i | o Ar args
+Specify the input and output device or file.
+Both 
+.Fl i
+and
+.Fl o
+must be specified.
+There are a number of parameters that can be specified.
+One of the first two (file or pass) MUST be specified to indicate which I/O
+method to use on the device in question.
+.Bl -tag -width 9n
+.It pass=dev
+Specify a
+.Xr pass 4
+device to operate on.
+This requests that
+.Nm
+access the device in question be accessed via the asynchronous
+.Xr pass 4
+interface.
+.Pp
+The device name can be a
+.Xr pass 4
+name and unit number, for instance
+.Dq pass0 ,
+or a regular peripheral driver name and unit number, for instance
+.Dq da5 .
+It can also be the path of a
+.Xr pass 4 
+or other disk device, like
+.Dq /dev/da5 .
+It may also be a bus:target:lun, for example:
+.Dq 0:5:0 .
+.Pp
+Only
+.Xr pass 4
+devices for
+.Tn SCSI
+disk-like devices are supported.
+.Tn ATA
+devices are not currently supported, but support could be added later.
+Specifically,
+.Tn SCSI
+Direct Access (type 0), WORM (type 4), CDROM (type 5), and RBC (Reduced
+Block Command, type 14) devices are supported.
+Tape drives, medium changers, enclosures etc. are not supported.
+.It file=path
+Specify a file or device to operate on.
+This requests that the file or device in question be accessed using the
+standard
+.Xr read 2
+and
+.Xr write 2
+system calls.
+The file interface does not support queueing multiple commands at a time.
+It does support probing disk sector size and capacity information, and tape
+blocksize and maximum transfer size information.
+The file interface supports standard files, disks, tape drives, special
+devices, pipes and standard input and output.
+If the file is specified as a 
+.Dq - ,
+standard input or standard output are used.
+For tape devices, the specified blocksize will be the size that
+.Nm
+attempts to use to write to or read from the tape.
+When writing to a tape device, the blocksize is treated like a disk sector
+size.
+So, that means
+.Nm
+will not write anything smaller than the sector size.
+At the end of a transfer, if there isn't sufficient data from the reader 
+to yield a full block,
+.Nm
+will add zeros on the end of the data from the reader to make up a full
+block.
+.It bs=N
+Specify the blocksize to use for transfers.
+.Nm
+will attempt to read or write using the requested blocksize.
+.Pp
+Note that the blocksize given only applies to either the input or the
+output path.
+To use the same blocksize for the input and output transfers, you must
+specify that blocksize with both the
+.Fl i
+and
+.Fl o
+arguments.
+.Pp
+The blocksize may be specified in bytes, or using any suffix (e.g. k, M, G)
+supported by
+.Xr expand_number 3 .
+.It offset=N
+Specify the starting offset for the input or output device or file.
+The offset may be specified in bytes, or by using any suffix (e.g. k, M, G)
+supported by
+.Xr expand_number 3 .
+.It depth=N
+Specify a desired queue depth for the input or output path.
+.Nm
+will attempt to keep the requested number of requests of the specified
+blocksize queued to the input or output device.
+Queue depths greater than 1 are only supported for the asynchronous
+.Xr pass 4 
+output method.
+The queue depth is maintained on a best effort basis, and may not be
+possible to maintain for especially fast devices.
+For writes, maintaining the queue depth also depends on a sufficiently
+fast reading device.
+.It mcs=N
+Specify the minimum command size to use for
+.Xr pass 4
+devices.
+Some devices do not support 6 byte
+.Tn SCSI
+commands.
+The
+.Xr da 4
+device handles this restriction automatically, but the
+.Xr pass 4
+device allows the user to specify the
+.Tn SCSI
+command used.
+If a device does not accept 6 byte
+.Tn SCSI
+READ/WRITE commands (which is the default at lower LBAs), it will generally
+accept 10 byte
+.Tn SCSI
+commands instead.
+.It debug=N
+Specify the debug level for this device.
+There is currently only one debug level setting, so setting this to any
+non-zero value will turn on debugging.
+The debug facility may be expanded in the future.
+.El
+.It Fl C Ar count
+Specify the retry count for commands sent via the asynchronous
+.Xr pass 4
+interface.
+This does not apply to commands sent via the file interface.
+.It Fl E
+Enable kernel error recovery for the
+.Xr pass 4
+driver.
+If error recovery is not enabled, unit attention conditions and other
+transient failures may cause the transfer to fail.
+.It Fl m Ar size
+Specify the maximum amount of data to be transferred.
+This may be specified in bytes, or by using any suffix (e.g. K, M, G)
+supported by
+.Xr expand_number 3 .
+.It Fl t Ar timeout
+Specify the command timeout in seconds to use for commands sent via the
+.Xr pass 4
+driver.
+.It Fl v
+Enable verbose reporting of errors.
+This is recommended to aid in debugging any
+.Tn SCSI
+issues that come up.
+.It Fl h
+Display the
+.Nm
+usage message.
+.El
+.Pp
+If
+.Nm
+receives a SIGINFO signal, it will print the current input and output byte
+counts, elapsed runtime and average throughput.
+If
+.Nm
+receives a SIGINT signal, it will print the current input and output byte
+counts, elapsed runtime and average throughput and then exit.
+.Sh EXAMPLES
+.Dl camdd -i pass=da8,bs=512k,depth=4 -o pass=da3,bs=512k,depth=4
+.Pp
+Copy all data from da8 to da3 using a blocksize of 512k for both drives,
+and attempt to maintain a queue depth of 4 on both the input and output
+devices.
+The transfer will stop when the end of either device is reached.
+.Pp
+.Dl camdd -i file=/dev/zero,bs=1M -o pass=da5,bs=1M,depth=4 -m 100M
+.Pp
+Read 1MB blocks of zeros from /dev/zero, and write them to da5 with a
+desired queue depth of 4.
+Stop the transfer after 100MB has been written.
+.Pp
+.Dl camdd -i pass=da8,bs=1M,depth=3 -o file=disk.img
+.Pp
+Copy disk da8 using a 1MB blocksize and desired queue depth of 3 to the
+file disk.img.
+.Pp
+.Dl camdd -i file=/etc/rc -o file=- 
+.Pp
+Read the file /etc/rc and write it to standard output.
+.Pp
+.Dl camdd -i pass=da10,bs=64k,depth=16 -o file=/dev/nsa0,bs=128k
+.Pp
+Copy 64K blocks from the disk da10 with a queue depth of 16, and write
+to the tape drive sa0 with a 128k blocksize.
+The copy will stop when either the end of the disk or tape is reached.
+.Sh SEE ALSO
+.Xr cam 3 ,
+.Xr cam 4 ,
+.Xr pass 4 ,
+.Xr camcontrol 8
+.Sh HISTORY
+.Nm
+first appeared in
+.Fx 10.2
+.Sh AUTHORS
+.An Kenneth Merry Aq Mt ken@FreeBSD.org
diff --git a/usr.sbin/camdd/camdd.c b/usr.sbin/camdd/camdd.c
new file mode 100644
index 0000000..b34e472
--- /dev/null
+++ b/usr.sbin/camdd/camdd.c
@@ -0,0 +1,3428 @@
+/*-
+ * Copyright (c) 1997-2007 Kenneth D. Merry
+ * Copyright (c) 2013, 2014, 2015 Spectra Logic Corporation
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions, and the following disclaimer,
+ *    without modification.
+ * 2. Redistributions in binary form must reproduce at minimum a disclaimer
+ *    substantially similar to the "NO WARRANTY" disclaimer below
+ *    ("Disclaimer") and any redistribution must be conditioned upon
+ *    including a substantially similar Disclaimer requirement for further
+ *    binary redistribution.
+ *
+ * NO WARRANTY
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGES.
+ *
+ * Authors: Ken Merry           (Spectra Logic Corporation)
+ */
+
+/*
+ * This is eventually intended to be:
+ * - A basic data transfer/copy utility
+ * - A simple benchmark utility
+ * - An example of how to use the asynchronous pass(4) driver interface.
+ */
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/ioctl.h>
+#include <sys/stdint.h>
+#include <sys/types.h>
+#include <sys/endian.h>
+#include <sys/param.h>
+#include <sys/sbuf.h>
+#include <sys/stat.h>
+#include <sys/event.h>
+#include <sys/time.h>
+#include <sys/uio.h>
+#include <vm/vm.h>
+#include <machine/bus.h>
+#include <sys/bus.h>
+#include <sys/bus_dma.h>
+#include <sys/mtio.h>
+#include <sys/conf.h>
+#include <sys/disk.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <semaphore.h>
+#include <string.h>
+#include <unistd.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <fcntl.h>
+#include <ctype.h>
+#include <err.h>
+#include <libutil.h>
+#include <pthread.h>
+#include <assert.h>
+#include <bsdxml.h>
+
+#include <cam/cam.h>
+#include <cam/cam_debug.h>
+#include <cam/cam_ccb.h>
+#include <cam/scsi/scsi_all.h>
+#include <cam/scsi/scsi_da.h>
+#include <cam/scsi/scsi_pass.h>
+#include <cam/scsi/scsi_message.h>
+#include <cam/scsi/smp_all.h>
+#include <camlib.h>
+#include <mtlib.h>
+#include <zlib.h>
+
+typedef enum {
+	CAMDD_CMD_NONE		= 0x00000000,
+	CAMDD_CMD_HELP		= 0x00000001,
+	CAMDD_CMD_WRITE		= 0x00000002,
+	CAMDD_CMD_READ		= 0x00000003
+} camdd_cmdmask;
+
+typedef enum {
+	CAMDD_ARG_NONE		= 0x00000000,
+	CAMDD_ARG_VERBOSE	= 0x00000001,
+	CAMDD_ARG_DEVICE	= 0x00000002,
+	CAMDD_ARG_BUS		= 0x00000004,
+	CAMDD_ARG_TARGET	= 0x00000008,
+	CAMDD_ARG_LUN		= 0x00000010,
+	CAMDD_ARG_UNIT		= 0x00000020,
+	CAMDD_ARG_TIMEOUT	= 0x00000040,
+	CAMDD_ARG_ERR_RECOVER	= 0x00000080,
+	CAMDD_ARG_RETRIES	= 0x00000100
+} camdd_argmask;
+
+typedef enum {
+	CAMDD_DEV_NONE		= 0x00,
+	CAMDD_DEV_PASS		= 0x01,
+	CAMDD_DEV_FILE		= 0x02
+} camdd_dev_type;
+
+struct camdd_io_opts {
+	camdd_dev_type	dev_type;
+	char		*dev_name;
+	uint64_t	blocksize;
+	uint64_t	queue_depth;
+	uint64_t	offset;
+	int		min_cmd_size;
+	int		write_dev;
+	uint64_t	debug;
+};
+
+typedef enum {
+	CAMDD_BUF_NONE,
+	CAMDD_BUF_DATA,
+	CAMDD_BUF_INDIRECT
+} camdd_buf_type;
+
+struct camdd_buf_indirect {
+	/*
+	 * Pointer to the source buffer.
+	 */
+	struct camdd_buf *src_buf;
+
+	/*
+	 * Offset into the source buffer, in bytes.
+	 */
+	uint64_t	  offset;
+	/*
+	 * Pointer to the starting point in the source buffer.
+	 */
+	uint8_t		 *start_ptr;
+
+	/*
+	 * Length of this chunk in bytes.
+	 */
+	size_t		  len;
+};
+
+struct camdd_buf_data {
+	/*
+	 * Buffer allocated when we allocate this camdd_buf.  This should
+	 * be the size of the blocksize for this device.
+	 */
+	uint8_t			*buf;
+
+	/*
+	 * The amount of backing store allocated in buf.  Generally this
+	 * will be the blocksize of the device.
+	 */
+	uint32_t		 alloc_len;
+
+	/*
+	 * The amount of data that was put into the buffer (on reads) or
+	 * the amount of data we have put onto the src_list so far (on
+	 * writes).
+	 */
+	uint32_t		 fill_len;
+
+	/*
+	 * The amount of data that was not transferred.
+	 */
+	uint32_t		 resid;
+
+	/*
+	 * Starting byte offset on the reader.
+	 */
+	uint64_t		 src_start_offset;
+	
+	/*
+	 * CCB used for pass(4) device targets.
+	 */
+	union ccb		 ccb;
+
+	/*
+	 * Number of scatter/gather segments.
+	 */
+	int			 sg_count;
+
+	/*
+	 * Set if we had to tack on an extra buffer to round the transfer
+	 * up to a sector size.
+	 */
+	int			 extra_buf;
+
+	/*
+	 * Scatter/gather list used generally when we're the writer for a
+	 * pass(4) device. 
+	 */
+	bus_dma_segment_t	*segs;
+
+	/*
+	 * Scatter/gather list used generally when we're the writer for a
+	 * file or block device;
+	 */
+	struct iovec		*iovec;
+};
+
+union camdd_buf_types {
+	struct camdd_buf_indirect	indirect;
+	struct camdd_buf_data		data;
+};
+
+typedef enum {
+	CAMDD_STATUS_NONE,
+	CAMDD_STATUS_OK,
+	CAMDD_STATUS_SHORT_IO,
+	CAMDD_STATUS_EOF,
+	CAMDD_STATUS_ERROR
+} camdd_buf_status;
+
+struct camdd_buf {
+	camdd_buf_type		 buf_type;
+	union camdd_buf_types	 buf_type_spec;
+
+	camdd_buf_status	 status;
+
+	uint64_t		 lba;
+	size_t			 len;
+
+	/*
+	 * A reference count of how many indirect buffers point to this
+	 * buffer.
+	 */
+	int			 refcount;
+
+	/*
+	 * A link back to our parent device.
+	 */
+	struct camdd_dev	*dev;
+	STAILQ_ENTRY(camdd_buf)  links;
+	STAILQ_ENTRY(camdd_buf)  work_links;
+
+	/*
+	 * A count of the buffers on the src_list.
+	 */
+	int			 src_count;
+
+	/*
+	 * List of buffers from our partner thread that are the components
+	 * of this buffer for the I/O.  Uses src_links.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 src_list;
+	STAILQ_ENTRY(camdd_buf)  src_links;
+};
+
+#define	NUM_DEV_TYPES	2
+
+struct camdd_dev_pass {
+	int			 scsi_dev_type;
+	struct cam_device	*dev;
+	uint64_t		 max_sector;
+	uint32_t		 block_len;
+	uint32_t		 cpi_maxio;
+};
+
+typedef enum {
+	CAMDD_FILE_NONE,
+	CAMDD_FILE_REG,
+	CAMDD_FILE_STD,
+	CAMDD_FILE_PIPE,
+	CAMDD_FILE_DISK,
+	CAMDD_FILE_TAPE,
+	CAMDD_FILE_TTY,
+	CAMDD_FILE_MEM
+} camdd_file_type;
+
+typedef enum {
+	CAMDD_FF_NONE 		= 0x00,
+	CAMDD_FF_CAN_SEEK	= 0x01
+} camdd_file_flags;
+
+struct camdd_dev_file {
+	int			 fd;
+	struct stat		 sb;
+	char			 filename[MAXPATHLEN + 1];
+	camdd_file_type		 file_type;
+	camdd_file_flags	 file_flags;
+	uint8_t			*tmp_buf;
+};
+
+struct camdd_dev_block {
+	int			 fd;
+	uint64_t		 size_bytes;
+	uint32_t		 block_len;
+};
+
+union camdd_dev_spec {
+	struct camdd_dev_pass	pass;
+	struct camdd_dev_file	file;
+	struct camdd_dev_block	block;
+};
+
+typedef enum {
+	CAMDD_DEV_FLAG_NONE		= 0x00,
+	CAMDD_DEV_FLAG_EOF		= 0x01,
+	CAMDD_DEV_FLAG_PEER_EOF		= 0x02,
+	CAMDD_DEV_FLAG_ACTIVE		= 0x04,
+	CAMDD_DEV_FLAG_EOF_SENT		= 0x08,
+	CAMDD_DEV_FLAG_EOF_QUEUED	= 0x10
+} camdd_dev_flags;
+
+struct camdd_dev {
+	camdd_dev_type		 dev_type;
+	union camdd_dev_spec	 dev_spec;
+	camdd_dev_flags		 flags;
+	char			 device_name[MAXPATHLEN+1];
+	uint32_t		 blocksize;
+	uint32_t		 sector_size;
+	uint64_t		 max_sector;
+	uint64_t		 sector_io_limit;
+	int			 min_cmd_size;
+	int			 write_dev;
+	int			 retry_count;
+	int			 io_timeout;
+	int			 debug;
+	uint64_t		 start_offset_bytes;
+	uint64_t		 next_io_pos_bytes;
+	uint64_t		 next_peer_pos_bytes;
+	uint64_t		 next_completion_pos_bytes;
+	uint64_t		 peer_bytes_queued;
+	uint64_t		 bytes_transferred;
+	uint32_t		 target_queue_depth;
+	uint32_t		 cur_active_io;
+	uint8_t			*extra_buf;
+	uint32_t		 extra_buf_len;
+	struct camdd_dev	*peer_dev;
+	pthread_mutex_t		 mutex;
+	pthread_cond_t		 cond;
+	int			 kq;
+
+	int			 (*run)(struct camdd_dev *dev);
+	int			 (*fetch)(struct camdd_dev *dev);
+
+	/*
+	 * Buffers that are available for I/O.  Uses links.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 free_queue;
+
+	/*
+	 * Free indirect buffers.  These are used for breaking a large
+	 * buffer into multiple pieces.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 free_indirect_queue;
+
+	/*
+	 * Buffers that have been queued to the kernel.  Uses links.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 active_queue;
+
+	/*
+	 * Will generally contain one of our buffers that is waiting for enough
+	 * I/O from our partner thread to be able to execute.  This will
+	 * generally happen when our per-I/O-size is larger than the
+	 * partner thread's per-I/O-size.  Uses links.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 pending_queue;
+
+	/*
+	 * Number of buffers on the pending queue
+	 */
+	int			 num_pending_queue;
+
+	/*
+	 * Buffers that are filled and ready to execute.  This is used when
+	 * our partner (reader) thread sends us blocks that are larger than
+	 * our blocksize, and so we have to split them into multiple pieces.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 run_queue;
+
+	/*
+	 * Number of buffers on the run queue.
+	 */
+	int			 num_run_queue;
+
+	STAILQ_HEAD(,camdd_buf)	 reorder_queue;
+
+	int			 num_reorder_queue;
+
+	/*
+	 * Buffers that have been queued to us by our partner thread
+	 * (generally the reader thread) to be written out.  Uses
+	 * work_links.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 work_queue;
+
+	/*
+	 * Buffers that have been completed by our partner thread.  Uses
+	 * work_links.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 peer_done_queue;
+
+	/*
+	 * Number of buffers on the peer done queue.
+	 */
+	uint32_t		 num_peer_done_queue;
+
+	/*
+	 * A list of buffers that we have queued to our peer thread.  Uses
+	 * links.
+	 */
+	STAILQ_HEAD(,camdd_buf)	 peer_work_queue;
+
+	/*
+	 * Number of buffers on the peer work queue.
+	 */
+	uint32_t		 num_peer_work_queue;
+};
+
+static sem_t camdd_sem;
+static int need_exit = 0;
+static int error_exit = 0;
+static int need_status = 0;
+
+#ifndef min
+#define	min(a, b) (a < b) ? a : b
+#endif
+
+/*
+ * XXX KDM private copy of timespecsub().  This is normally defined in
+ * sys/time.h, but is only enabled in the kernel.  If that definition is
+ * enabled in userland, it breaks the build of libnetbsd.
+ */
+#ifndef timespecsub
+#define	timespecsub(vvp, uvp)						\
+	do {								\
+		(vvp)->tv_sec -= (uvp)->tv_sec;				\
+		(vvp)->tv_nsec -= (uvp)->tv_nsec;			\
+		if ((vvp)->tv_nsec < 0) {				\
+			(vvp)->tv_sec--;				\
+			(vvp)->tv_nsec += 1000000000;			\
+		}							\
+	} while (0)
+#endif
+
+
+/* Generically usefull offsets into the peripheral private area */
+#define ppriv_ptr0 periph_priv.entries[0].ptr
+#define ppriv_ptr1 periph_priv.entries[1].ptr
+#define ppriv_field0 periph_priv.entries[0].field
+#define ppriv_field1 periph_priv.entries[1].field
+
+#define	ccb_buf	ppriv_ptr0
+
+#define	CAMDD_FILE_DEFAULT_BLOCK	524288
+#define	CAMDD_FILE_DEFAULT_DEPTH	1
+#define	CAMDD_PASS_MAX_BLOCK		1048576
+#define	CAMDD_PASS_DEFAULT_DEPTH	6
+#define	CAMDD_PASS_RW_TIMEOUT		60 * 1000
+
+static int parse_btl(char *tstr, int *bus, int *target, int *lun,
+		     camdd_argmask *arglst);
+void camdd_free_dev(struct camdd_dev *dev);
+struct camdd_dev *camdd_alloc_dev(camdd_dev_type dev_type,
+				  struct kevent *new_ke, int num_ke,
+				  int retry_count, int timeout);
+static struct camdd_buf *camdd_alloc_buf(struct camdd_dev *dev,
+					 camdd_buf_type buf_type);
+void camdd_release_buf(struct camdd_buf *buf);
+struct camdd_buf *camdd_get_buf(struct camdd_dev *dev, camdd_buf_type buf_type);
+int camdd_buf_sg_create(struct camdd_buf *buf, int iovec,
+			uint32_t sector_size, uint32_t *num_sectors_used,
+			int *double_buf_needed);
+uint32_t camdd_buf_get_len(struct camdd_buf *buf);
+void camdd_buf_add_child(struct camdd_buf *buf, struct camdd_buf *child_buf);
+int camdd_probe_tape(int fd, char *filename, uint64_t *max_iosize,
+		     uint64_t *max_blk, uint64_t *min_blk, uint64_t *blk_gran);
+struct camdd_dev *camdd_probe_file(int fd, struct camdd_io_opts *io_opts,
+				   int retry_count, int timeout);
+struct camdd_dev *camdd_probe_pass(struct cam_device *cam_dev,
+				   struct camdd_io_opts *io_opts,
+				   camdd_argmask arglist, int probe_retry_count,
+				   int probe_timeout, int io_retry_count,
+				   int io_timeout);
+void *camdd_file_worker(void *arg);
+camdd_buf_status camdd_ccb_status(union ccb *ccb);
+int camdd_queue_peer_buf(struct camdd_dev *dev, struct camdd_buf *buf);
+int camdd_complete_peer_buf(struct camdd_dev *dev, struct camdd_buf *peer_buf);
+void camdd_peer_done(struct camdd_buf *buf);
+void camdd_complete_buf(struct camdd_dev *dev, struct camdd_buf *buf,
+			int *error_count);
+int camdd_pass_fetch(struct camdd_dev *dev);
+int camdd_file_run(struct camdd_dev *dev);
+int camdd_pass_run(struct camdd_dev *dev);
+int camdd_get_next_lba_len(struct camdd_dev *dev, uint64_t *lba, ssize_t *len);
+int camdd_queue(struct camdd_dev *dev, struct camdd_buf *read_buf);
+void camdd_get_depth(struct camdd_dev *dev, uint32_t *our_depth,
+		     uint32_t *peer_depth, uint32_t *our_bytes,
+		     uint32_t *peer_bytes);
+void *camdd_worker(void *arg);
+void camdd_sig_handler(int sig);
+void camdd_print_status(struct camdd_dev *camdd_dev,
+			struct camdd_dev *other_dev,
+			struct timespec *start_time);
+int camdd_rw(struct camdd_io_opts *io_opts, int num_io_opts,
+	     uint64_t max_io, int retry_count, int timeout);
+int camdd_parse_io_opts(char *args, int is_write,
+			struct camdd_io_opts *io_opts);
+void usage(void);
+
+/*
+ * Parse out a bus, or a bus, target and lun in the following
+ * format:
+ * bus
+ * bus:target
+ * bus:target:lun
+ *
+ * Returns the number of parsed components, or 0.
+ */
+static int
+parse_btl(char *tstr, int *bus, int *target, int *lun, camdd_argmask *arglst)
+{
+	char *tmpstr;
+	int convs = 0;
+
+	while (isspace(*tstr) && (*tstr != '\0'))
+		tstr++;
+
+	tmpstr = (char *)strtok(tstr, ":");
+	if ((tmpstr != NULL) && (*tmpstr != '\0')) {
+		*bus = strtol(tmpstr, NULL, 0);
+		*arglst |= CAMDD_ARG_BUS;
+		convs++;
+		tmpstr = (char *)strtok(NULL, ":");
+		if ((tmpstr != NULL) && (*tmpstr != '\0')) {
+			*target = strtol(tmpstr, NULL, 0);
+			*arglst |= CAMDD_ARG_TARGET;
+			convs++;
+			tmpstr = (char *)strtok(NULL, ":");
+			if ((tmpstr != NULL) && (*tmpstr != '\0')) {
+				*lun = strtol(tmpstr, NULL, 0);
+				*arglst |= CAMDD_ARG_LUN;
+				convs++;
+			}
+		}
+	}
+
+	return convs;
+}
+
+/*
+ * XXX KDM clean up and free all of the buffers on the queue!
+ */
+void
+camdd_free_dev(struct camdd_dev *dev)
+{
+	if (dev == NULL)
+		return;
+
+	switch (dev->dev_type) {
+	case CAMDD_DEV_FILE: {
+		struct camdd_dev_file *file_dev = &dev->dev_spec.file;
+
+		if (file_dev->fd != -1)
+			close(file_dev->fd);
+		free(file_dev->tmp_buf);
+		break;
+	}
+	case CAMDD_DEV_PASS: {
+		struct camdd_dev_pass *pass_dev = &dev->dev_spec.pass;
+
+		if (pass_dev->dev != NULL)
+			cam_close_device(pass_dev->dev);
+		break;
+	}
+	default:
+		break;
+	}
+
+	free(dev);
+}
+
+struct camdd_dev *
+camdd_alloc_dev(camdd_dev_type dev_type, struct kevent *new_ke, int num_ke,
+		int retry_count, int timeout)
+{
+	struct camdd_dev *dev = NULL;
+	struct kevent *ke;
+	size_t ke_size;
+	int retval = 0;
+
+	dev = malloc(sizeof(*dev));
+	if (dev == NULL) {
+		warn("%s: unable to malloc %zu bytes", __func__, sizeof(*dev));
+		goto bailout;
+	}
+
+	bzero(dev, sizeof(*dev));
+
+	dev->dev_type = dev_type;
+	dev->io_timeout = timeout;
+	dev->retry_count = retry_count;
+	STAILQ_INIT(&dev->free_queue);
+	STAILQ_INIT(&dev->free_indirect_queue);
+	STAILQ_INIT(&dev->active_queue);
+	STAILQ_INIT(&dev->pending_queue);
+	STAILQ_INIT(&dev->run_queue);
+	STAILQ_INIT(&dev->reorder_queue);
+	STAILQ_INIT(&dev->work_queue);
+	STAILQ_INIT(&dev->peer_done_queue);
+	STAILQ_INIT(&dev->peer_work_queue);
+	retval = pthread_mutex_init(&dev->mutex, NULL);
+	if (retval != 0) {
+		warnc(retval, "%s: failed to initialize mutex", __func__);
+		goto bailout;
+	}
+
+	retval = pthread_cond_init(&dev->cond, NULL);
+	if (retval != 0) {
+		warnc(retval, "%s: failed to initialize condition variable",
+		      __func__);
+		goto bailout;
+	}
+
+	dev->kq = kqueue();
+	if (dev->kq == -1) {
+		warn("%s: Unable to create kqueue", __func__);
+		goto bailout;
+	}
+
+	ke_size = sizeof(struct kevent) * (num_ke + 4);
+	ke = malloc(ke_size);
+	if (ke == NULL) {
+		warn("%s: unable to malloc %zu bytes", __func__, ke_size);
+		goto bailout;
+	}
+	bzero(ke, ke_size);
+	if (num_ke > 0)
+		bcopy(new_ke, ke, num_ke * sizeof(struct kevent));
+
+	EV_SET(&ke[num_ke++], (uintptr_t)&dev->work_queue, EVFILT_USER,
+	       EV_ADD|EV_ENABLE|EV_CLEAR, 0,0, 0);
+	EV_SET(&ke[num_ke++], (uintptr_t)&dev->peer_done_queue, EVFILT_USER,
+	       EV_ADD|EV_ENABLE|EV_CLEAR, 0,0, 0);
+	EV_SET(&ke[num_ke++], SIGINFO, EVFILT_SIGNAL, EV_ADD|EV_ENABLE, 0,0,0);
+	EV_SET(&ke[num_ke++], SIGINT, EVFILT_SIGNAL, EV_ADD|EV_ENABLE, 0,0,0);
+
+	retval = kevent(dev->kq, ke, num_ke, NULL, 0, NULL);
+	if (retval == -1) {
+		warn("%s: Unable to register kevents", __func__);
+		goto bailout;
+	}
+
+
+	return (dev);
+
+bailout:
+	free(dev);
+
+	return (NULL);
+}
+
+static struct camdd_buf *
+camdd_alloc_buf(struct camdd_dev *dev, camdd_buf_type buf_type)
+{
+	struct camdd_buf *buf = NULL;
+	uint8_t *data_ptr = NULL;
+
+	/*
+	 * We only need to allocate data space for data buffers.
+	 */
+	switch (buf_type) {
+	case CAMDD_BUF_DATA:
+		data_ptr = malloc(dev->blocksize);
+		if (data_ptr == NULL) {
+			warn("unable to allocate %u bytes", dev->blocksize);
+			goto bailout_error;
+		}
+		break;
+	default:
+		break;
+	}
+	
+	buf = malloc(sizeof(*buf));
+	if (buf == NULL) {
+		warn("unable to allocate %zu bytes", sizeof(*buf));
+		goto bailout_error;
+	}
+
+	bzero(buf, sizeof(*buf));
+	buf->buf_type = buf_type;
+	buf->dev = dev;
+	switch (buf_type) {
+	case CAMDD_BUF_DATA: {
+		struct camdd_buf_data *data;
+
+		data = &buf->buf_type_spec.data;
+
+		data->alloc_len = dev->blocksize;
+		data->buf = data_ptr;
+		break;
+	}
+	case CAMDD_BUF_INDIRECT:
+		break;
+	default:
+		break;
+	}
+	STAILQ_INIT(&buf->src_list);
+
+	return (buf);
+
+bailout_error:
+	if (data_ptr != NULL)
+		free(data_ptr);
+
+	if (buf != NULL)
+		free(buf);
+
+	return (NULL);
+}
+
+void
+camdd_release_buf(struct camdd_buf *buf)
+{
+	struct camdd_dev *dev;
+
+	dev = buf->dev;
+
+	switch (buf->buf_type) {
+	case CAMDD_BUF_DATA: {
+		struct camdd_buf_data *data;
+
+		data = &buf->buf_type_spec.data;
+
+		if (data->segs != NULL) {
+			if (data->extra_buf != 0) {
+				void *extra_buf;
+
+				extra_buf = (void *)
+				    data->segs[data->sg_count - 1].ds_addr;
+				free(extra_buf);
+				data->extra_buf = 0;
+			}
+			free(data->segs);
+			data->segs = NULL;
+			data->sg_count = 0;
+		} else if (data->iovec != NULL) {
+			if (data->extra_buf != 0) {
+				free(data->iovec[data->sg_count - 1].iov_base);
+				data->extra_buf = 0;
+			}
+			free(data->iovec);
+			data->iovec = NULL;
+			data->sg_count = 0;
+		}
+		STAILQ_INSERT_TAIL(&dev->free_queue, buf, links);
+		break;
+	}
+	case CAMDD_BUF_INDIRECT:
+		STAILQ_INSERT_TAIL(&dev->free_indirect_queue, buf, links);
+		break;
+	default:
+		err(1, "%s: Invalid buffer type %d for released buffer",
+		    __func__, buf->buf_type);
+		break;
+	}
+}
+
+struct camdd_buf *
+camdd_get_buf(struct camdd_dev *dev, camdd_buf_type buf_type)
+{
+	struct camdd_buf *buf = NULL;
+
+	switch (buf_type) {
+	case CAMDD_BUF_DATA:
+		buf = STAILQ_FIRST(&dev->free_queue);
+		if (buf != NULL) {
+			struct camdd_buf_data *data;
+			uint8_t *data_ptr;
+			uint32_t alloc_len;
+
+			STAILQ_REMOVE_HEAD(&dev->free_queue, links);
+			data = &buf->buf_type_spec.data;
+			data_ptr = data->buf;
+			alloc_len = data->alloc_len;
+			bzero(buf, sizeof(*buf));
+			data->buf = data_ptr;
+			data->alloc_len = alloc_len;
+		}
+		break;
+	case CAMDD_BUF_INDIRECT:
+		buf = STAILQ_FIRST(&dev->free_indirect_queue);
+		if (buf != NULL) {
+			STAILQ_REMOVE_HEAD(&dev->free_indirect_queue, links);
+
+			bzero(buf, sizeof(*buf));
+		}
+		break;
+	default:
+		warnx("Unknown buffer type %d requested", buf_type);
+		break;
+	}
+
+
+	if (buf == NULL)
+		return (camdd_alloc_buf(dev, buf_type));
+	else {
+		STAILQ_INIT(&buf->src_list);
+		buf->dev = dev;
+		buf->buf_type = buf_type;
+
+		return (buf);
+	}
+}
+
+int
+camdd_buf_sg_create(struct camdd_buf *buf, int iovec, uint32_t sector_size,
+		    uint32_t *num_sectors_used, int *double_buf_needed)
+{
+	struct camdd_buf *tmp_buf;
+	struct camdd_buf_data *data;
+	uint8_t *extra_buf = NULL;
+	size_t extra_buf_len = 0;
+	int i, retval = 0;
+
+	data = &buf->buf_type_spec.data;
+
+	data->sg_count = buf->src_count;
+	/*
+	 * Compose a scatter/gather list from all of the buffers in the list.
+	 * If the length of the buffer isn't a multiple of the sector size,
+	 * we'll have to add an extra buffer.  This should only happen
+	 * at the end of a transfer.
+	 */
+	if ((data->fill_len % sector_size) != 0) {
+		extra_buf_len = sector_size - (data->fill_len % sector_size);
+		extra_buf = calloc(extra_buf_len, 1);
+		if (extra_buf == NULL) {
+			warn("%s: unable to allocate %zu bytes for extra "
+			    "buffer space", __func__, extra_buf_len);
+			retval = 1;
+			goto bailout;
+		}
+		data->extra_buf = 1;
+		data->sg_count++;
+	}
+	if (iovec == 0) {
+		data->segs = calloc(data->sg_count, sizeof(bus_dma_segment_t));
+		if (data->segs == NULL) {
+			warn("%s: unable to allocate %zu bytes for S/G list",
+			    __func__, sizeof(bus_dma_segment_t) *
+			    data->sg_count);
+			retval = 1;
+			goto bailout;
+		}
+
+	} else {
+		data->iovec = calloc(data->sg_count, sizeof(struct iovec));
+		if (data->iovec == NULL) {
+			warn("%s: unable to allocate %zu bytes for S/G list",
+			    __func__, sizeof(struct iovec) * data->sg_count);
+			retval = 1;
+			goto bailout;
+		}
+	}
+
+	for (i = 0, tmp_buf = STAILQ_FIRST(&buf->src_list);
+	     i < buf->src_count && tmp_buf != NULL; i++,
+	     tmp_buf = STAILQ_NEXT(tmp_buf, src_links)) {
+
+		if (tmp_buf->buf_type == CAMDD_BUF_DATA) {
+			struct camdd_buf_data *tmp_data;
+
+			tmp_data = &tmp_buf->buf_type_spec.data;
+			if (iovec == 0) {
+				data->segs[i].ds_addr =
+				    (bus_addr_t) tmp_data->buf;
+				data->segs[i].ds_len = tmp_data->fill_len -
+				    tmp_data->resid;
+			} else {
+				data->iovec[i].iov_base = tmp_data->buf;
+				data->iovec[i].iov_len = tmp_data->fill_len -
+				    tmp_data->resid;
+			}
+			if (((tmp_data->fill_len - tmp_data->resid) %
+			     sector_size) != 0)
+				*double_buf_needed = 1;
+		} else {
+			struct camdd_buf_indirect *tmp_ind;
+
+			tmp_ind = &tmp_buf->buf_type_spec.indirect;
+			if (iovec == 0) {
+				data->segs[i].ds_addr =
+				    (bus_addr_t)tmp_ind->start_ptr;
+				data->segs[i].ds_len = tmp_ind->len;
+			} else {
+				data->iovec[i].iov_base = tmp_ind->start_ptr;
+				data->iovec[i].iov_len = tmp_ind->len;
+			}
+			if ((tmp_ind->len % sector_size) != 0)
+				*double_buf_needed = 1;
+		}
+	}
+
+	if (extra_buf != NULL) {
+		if (iovec == 0) {
+			data->segs[i].ds_addr = (bus_addr_t)extra_buf;
+			data->segs[i].ds_len = extra_buf_len;
+		} else {
+			data->iovec[i].iov_base = extra_buf;
+			data->iovec[i].iov_len = extra_buf_len;
+		}
+		i++;
+	}
+	if ((tmp_buf != NULL) || (i != data->sg_count)) {
+		warnx("buffer source count does not match "
+		      "number of buffers in list!");
+		retval = 1;
+		goto bailout;
+	}
+
+bailout:
+	if (retval == 0) {
+		*num_sectors_used = (data->fill_len + extra_buf_len) /
+		    sector_size;
+	}
+	return (retval);
+}
+
+uint32_t
+camdd_buf_get_len(struct camdd_buf *buf)
+{
+	uint32_t len = 0;
+
+	if (buf->buf_type != CAMDD_BUF_DATA) {
+		struct camdd_buf_indirect *indirect;
+
+		indirect = &buf->buf_type_spec.indirect;
+		len = indirect->len;
+	} else {
+		struct camdd_buf_data *data;
+
+		data = &buf->buf_type_spec.data;
+		len = data->fill_len;
+	}
+
+	return (len);
+}
+
+void
+camdd_buf_add_child(struct camdd_buf *buf, struct camdd_buf *child_buf)
+{
+	struct camdd_buf_data *data;
+
+	assert(buf->buf_type == CAMDD_BUF_DATA);
+
+	data = &buf->buf_type_spec.data;
+
+	STAILQ_INSERT_TAIL(&buf->src_list, child_buf, src_links);
+	buf->src_count++;
+
+	data->fill_len += camdd_buf_get_len(child_buf);
+}
+
+typedef enum {
+	CAMDD_TS_MAX_BLK,
+	CAMDD_TS_MIN_BLK,
+	CAMDD_TS_BLK_GRAN,
+	CAMDD_TS_EFF_IOSIZE
+} camdd_status_item_index;
+
+static struct camdd_status_items {
+	const char *name;
+	struct mt_status_entry *entry;
+} req_status_items[] = {
+	{ "max_blk", NULL },
+	{ "min_blk", NULL },
+	{ "blk_gran", NULL },
+	{ "max_effective_iosize", NULL }
+};
+
+int
+camdd_probe_tape(int fd, char *filename, uint64_t *max_iosize,
+		 uint64_t *max_blk, uint64_t *min_blk, uint64_t *blk_gran)
+{
+	struct mt_status_data status_data;
+	char *xml_str = NULL;
+	unsigned int i;
+	int retval = 0;
+	
+	retval = mt_get_xml_str(fd, MTIOCEXTGET, &xml_str);
+	if (retval != 0)
+		err(1, "Couldn't get XML string from %s", filename);
+
+	retval = mt_get_status(xml_str, &status_data);
+	if (retval != XML_STATUS_OK) {
+		warn("couldn't get status for %s", filename);
+		retval = 1;
+		goto bailout;
+	} else
+		retval = 0;
+
+	if (status_data.error != 0) {
+		warnx("%s", status_data.error_str);
+		retval = 1;
+		goto bailout;
+	}
+
+	for (i = 0; i < sizeof(req_status_items) /
+	     sizeof(req_status_items[0]); i++) {
+                char *name;
+
+		name = __DECONST(char *, req_status_items[i].name);
+		req_status_items[i].entry = mt_status_entry_find(&status_data,
+		    name);
+		if (req_status_items[i].entry == NULL) {
+			errx(1, "Cannot find status entry %s",
+			    req_status_items[i].name);
+		}
+	}
+
+	*max_iosize = req_status_items[CAMDD_TS_EFF_IOSIZE].entry->value_unsigned;
+	*max_blk= req_status_items[CAMDD_TS_MAX_BLK].entry->value_unsigned;
+	*min_blk= req_status_items[CAMDD_TS_MIN_BLK].entry->value_unsigned;
+	*blk_gran = req_status_items[CAMDD_TS_BLK_GRAN].entry->value_unsigned;
+bailout:
+
+	free(xml_str);
+	mt_status_free(&status_data);
+
+	return (retval);
+}
+
+struct camdd_dev *
+camdd_probe_file(int fd, struct camdd_io_opts *io_opts, int retry_count,
+    int timeout)
+{
+	struct camdd_dev *dev = NULL;
+	struct camdd_dev_file *file_dev;
+	uint64_t blocksize = io_opts->blocksize;
+
+	dev = camdd_alloc_dev(CAMDD_DEV_FILE, NULL, 0, retry_count, timeout);
+	if (dev == NULL)
+		goto bailout;
+
+	file_dev = &dev->dev_spec.file;
+	file_dev->fd = fd;
+	strlcpy(file_dev->filename, io_opts->dev_name,
+	    sizeof(file_dev->filename));
+	strlcpy(dev->device_name, io_opts->dev_name, sizeof(dev->device_name));
+	if (blocksize == 0)
+		dev->blocksize = CAMDD_FILE_DEFAULT_BLOCK;
+	else
+		dev->blocksize = blocksize;
+
+	if ((io_opts->queue_depth != 0)
+	 && (io_opts->queue_depth != 1)) {
+		warnx("Queue depth %ju for %s ignored, only 1 outstanding "
+		    "command supported", (uintmax_t)io_opts->queue_depth,
+		    io_opts->dev_name);
+	}
+	dev->target_queue_depth = CAMDD_FILE_DEFAULT_DEPTH;
+	dev->run = camdd_file_run;
+	dev->fetch = NULL;
+
+	/*
+	 * We can effectively access files on byte boundaries.  We'll reset
+	 * this for devices like disks that can be accessed on sector
+	 * boundaries.
+	 */
+	dev->sector_size = 1;
+
+	if ((fd != STDIN_FILENO)
+	 && (fd != STDOUT_FILENO)) {
+		int retval;
+
+		retval = fstat(fd, &file_dev->sb);
+		if (retval != 0) {
+			warn("Cannot stat %s", dev->device_name);
+			goto bailout;
+			camdd_free_dev(dev);
+			dev = NULL;
+		}
+		if (S_ISREG(file_dev->sb.st_mode)) {
+			file_dev->file_type = CAMDD_FILE_REG;
+		} else if (S_ISCHR(file_dev->sb.st_mode)) {
+			int type;
+
+			if (ioctl(fd, FIODTYPE, &type) == -1)
+				err(1, "FIODTYPE ioctl failed on %s",
+				    dev->device_name);
+			else {
+				if (type & D_TAPE)
+					file_dev->file_type = CAMDD_FILE_TAPE;
+				else if (type & D_DISK)
+					file_dev->file_type = CAMDD_FILE_DISK;
+				else if (type & D_MEM)
+					file_dev->file_type = CAMDD_FILE_MEM;
+				else if (type & D_TTY)
+					file_dev->file_type = CAMDD_FILE_TTY;
+			}
+		} else if (S_ISDIR(file_dev->sb.st_mode)) {
+			errx(1, "cannot operate on directory %s",
+			    dev->device_name);
+		} else if (S_ISFIFO(file_dev->sb.st_mode)) {
+			file_dev->file_type = CAMDD_FILE_PIPE;
+		} else
+			errx(1, "Cannot determine file type for %s",
+			    dev->device_name);
+
+		switch (file_dev->file_type) {
+		case CAMDD_FILE_REG:
+			if (file_dev->sb.st_size != 0)
+				dev->max_sector = file_dev->sb.st_size - 1;
+			else
+				dev->max_sector = 0;
+			file_dev->file_flags |= CAMDD_FF_CAN_SEEK;
+			break;
+		case CAMDD_FILE_TAPE: {
+			uint64_t max_iosize, max_blk, min_blk, blk_gran;
+			/*
+			 * Check block limits and maximum effective iosize.
+			 * Make sure the blocksize is within the block
+			 * limits (and a multiple of the minimum blocksize)
+			 * and that the blocksize is <= maximum effective
+			 * iosize.
+			 */
+			retval = camdd_probe_tape(fd, dev->device_name,
+			    &max_iosize, &max_blk, &min_blk, &blk_gran);
+			if (retval != 0)
+				errx(1, "Unable to probe tape %s",
+				    dev->device_name);
+
+			/*
+			 * The blocksize needs to be <= the maximum
+			 * effective I/O size of the tape device.  Note
+			 * that this also takes into account the maximum
+			 * blocksize reported by READ BLOCK LIMITS.
+			 */
+			if (dev->blocksize > max_iosize) {
+				warnx("Blocksize %u too big for %s, limiting "
+				    "to %ju", dev->blocksize, dev->device_name,
+				    max_iosize);
+				dev->blocksize = max_iosize;
+			}
+
+			/*
+			 * The blocksize needs to be at least min_blk;
+			 */
+			if (dev->blocksize < min_blk) {
+				warnx("Blocksize %u too small for %s, "
+				    "increasing to %ju", dev->blocksize,
+				    dev->device_name, min_blk);
+				dev->blocksize = min_blk;
+			}
+
+			/*
+			 * And the blocksize needs to be a multiple of
+			 * the block granularity.
+			 */
+			if ((blk_gran != 0)
+			 && (dev->blocksize % (1 << blk_gran))) {
+				warnx("Blocksize %u for %s not a multiple of "
+				    "%d, adjusting to %d", dev->blocksize,
+				    dev->device_name, (1 << blk_gran),
+				    dev->blocksize & ~((1 << blk_gran) - 1));
+				dev->blocksize &= ~((1 << blk_gran) - 1);
+			}
+
+			if (dev->blocksize == 0) {
+				errx(1, "Unable to derive valid blocksize for "
+				    "%s", dev->device_name);
+			}
+
+			/*
+			 * For tape drives, set the sector size to the
+			 * blocksize so that we make sure not to write
+			 * less than the blocksize out to the drive.
+			 */
+			dev->sector_size = dev->blocksize;
+			break;
+		}
+		case CAMDD_FILE_DISK: {
+			off_t media_size;
+			unsigned int sector_size;
+
+			file_dev->file_flags |= CAMDD_FF_CAN_SEEK;
+
+			if (ioctl(fd, DIOCGSECTORSIZE, &sector_size) == -1) {
+				err(1, "DIOCGSECTORSIZE ioctl failed on %s",
+				    dev->device_name);
+			}
+
+			if (sector_size == 0) {
+				errx(1, "DIOCGSECTORSIZE ioctl returned "
+				    "invalid sector size %u for %s",
+				    sector_size, dev->device_name);
+			}
+
+			if (ioctl(fd, DIOCGMEDIASIZE, &media_size) == -1) {
+				err(1, "DIOCGMEDIASIZE ioctl failed on %s",
+				    dev->device_name);
+			}
+
+			if (media_size == 0) {
+				errx(1, "DIOCGMEDIASIZE ioctl returned "
+				    "invalid media size %ju for %s",
+				    (uintmax_t)media_size, dev->device_name);
+			}
+
+			if (dev->blocksize % sector_size) {
+				errx(1, "%s blocksize %u not a multiple of "
+				    "sector size %u", dev->device_name,
+				    dev->blocksize, sector_size);
+			}
+
+			dev->sector_size = sector_size;
+			dev->max_sector = (media_size / sector_size) - 1;
+			break;
+		}
+		case CAMDD_FILE_MEM:
+			file_dev->file_flags |= CAMDD_FF_CAN_SEEK;
+			break;
+		default:
+			break;
+		}
+	}
+
+	if ((io_opts->offset != 0)
+	 && ((file_dev->file_flags & CAMDD_FF_CAN_SEEK) == 0)) {
+		warnx("Offset %ju specified for %s, but we cannot seek on %s",
+		    io_opts->offset, io_opts->dev_name, io_opts->dev_name);
+		goto bailout_error;
+	}
+#if 0
+	else if ((io_opts->offset != 0)
+		&& ((io_opts->offset % dev->sector_size) != 0)) {
+		warnx("Offset %ju for %s is not a multiple of the "
+		      "sector size %u", io_opts->offset, 
+		      io_opts->dev_name, dev->sector_size);
+		goto bailout_error;
+	} else {
+		dev->start_offset_bytes = io_opts->offset;
+	}
+#endif
+
+bailout:
+	return (dev);
+
+bailout_error:
+	camdd_free_dev(dev);
+	return (NULL);
+}
+
+/*
+ * Need to implement this.  Do a basic probe:
+ * - Check the inquiry data, make sure we're talking to a device that we
+ *   can reasonably expect to talk to -- direct, RBC, CD, WORM.
+ * - Send a test unit ready, make sure the device is available.
+ * - Get the capacity and block size.
+ */
+struct camdd_dev *
+camdd_probe_pass(struct cam_device *cam_dev, struct camdd_io_opts *io_opts,
+		 camdd_argmask arglist, int probe_retry_count,
+		 int probe_timeout, int io_retry_count, int io_timeout)
+{
+	union ccb *ccb;
+	uint64_t maxsector;
+	uint32_t cpi_maxio, max_iosize, pass_numblocks;
+	uint32_t block_len;
+	struct scsi_read_capacity_data rcap;
+	struct scsi_read_capacity_data_long rcaplong;
+	struct camdd_dev *dev;
+	struct camdd_dev_pass *pass_dev;
+	struct kevent ke;
+	int scsi_dev_type;
+	int retval;
+
+	dev = NULL;
+
+	scsi_dev_type = SID_TYPE(&cam_dev->inq_data);
+	maxsector = 0;
+	block_len = 0;
+
+	/*
+	 * For devices that support READ CAPACITY, we'll attempt to get the
+	 * capacity.  Otherwise, we really don't support tape or other
+	 * devices via SCSI passthrough, so just return an error in that case.
+	 */
+	switch (scsi_dev_type) {
+	case T_DIRECT:
+	case T_WORM:
+	case T_CDROM:
+	case T_OPTICAL:
+	case T_RBC:
+		break;
+	default:
+		errx(1, "Unsupported SCSI device type %d", scsi_dev_type);
+		break; /*NOTREACHED*/
+	}
+
+	ccb = cam_getccb(cam_dev);
+
+	if (ccb == NULL) {
+		warnx("%s: error allocating ccb", __func__);
+		goto bailout;
+	}
+
+	bzero(&(&ccb->ccb_h)[1],
+	      sizeof(struct ccb_scsiio) - sizeof(struct ccb_hdr));
+
+	scsi_read_capacity(&ccb->csio,
+			   /*retries*/ probe_retry_count,
+			   /*cbfcnp*/ NULL,
+			   /*tag_action*/ MSG_SIMPLE_Q_TAG,
+			   &rcap,
+			   SSD_FULL_SIZE,
+			   /*timeout*/ probe_timeout ? probe_timeout : 5000);
+
+	/* Disable freezing the device queue */
+	ccb->ccb_h.flags |= CAM_DEV_QFRZDIS;
+
+	if (arglist & CAMDD_ARG_ERR_RECOVER)
+		ccb->ccb_h.flags |= CAM_PASS_ERR_RECOVER;
+
+	if (cam_send_ccb(cam_dev, ccb) < 0) {
+		warn("error sending READ CAPACITY command");
+
+		cam_error_print(cam_dev, ccb, CAM_ESF_ALL,
+				CAM_EPF_ALL, stderr);
+
+		goto bailout;
+	}
+
+	if ((ccb->ccb_h.status & CAM_STATUS_MASK) != CAM_REQ_CMP) {
+		cam_error_print(cam_dev, ccb, CAM_ESF_ALL, CAM_EPF_ALL, stderr);
+		retval = 1;
+		goto bailout;
+	}
+
+	maxsector = scsi_4btoul(rcap.addr);
+	block_len = scsi_4btoul(rcap.length);
+
+	/*
+	 * A last block of 2^32-1 means that the true capacity is over 2TB,
+	 * and we need to issue the long READ CAPACITY to get the real
+	 * capacity.  Otherwise, we're all set.
+	 */
+	if (maxsector != 0xffffffff)
+		goto rcap_done;
+
+	scsi_read_capacity_16(&ccb->csio,
+			      /*retries*/ probe_retry_count,
+			      /*cbfcnp*/ NULL,
+			      /*tag_action*/ MSG_SIMPLE_Q_TAG,
+			      /*lba*/ 0,
+			      /*reladdr*/ 0,
+			      /*pmi*/ 0,
+			      (uint8_t *)&rcaplong,
+			      sizeof(rcaplong),
+			      /*sense_len*/ SSD_FULL_SIZE,
+			      /*timeout*/ probe_timeout ? probe_timeout : 5000);
+
+	/* Disable freezing the device queue */
+	ccb->ccb_h.flags |= CAM_DEV_QFRZDIS;
+
+	if (arglist & CAMDD_ARG_ERR_RECOVER)
+		ccb->ccb_h.flags |= CAM_PASS_ERR_RECOVER;
+
+	if (cam_send_ccb(cam_dev, ccb) < 0) {
+		warn("error sending READ CAPACITY (16) command");
+
+		cam_error_print(cam_dev, ccb, CAM_ESF_ALL,
+				CAM_EPF_ALL, stderr);
+
+		retval = 1;
+		goto bailout;
+	}
+
+	if ((ccb->ccb_h.status & CAM_STATUS_MASK) != CAM_REQ_CMP) {
+		cam_error_print(cam_dev, ccb, CAM_ESF_ALL, CAM_EPF_ALL, stderr);
+		goto bailout;
+	}
+
+	maxsector = scsi_8btou64(rcaplong.addr);
+	block_len = scsi_4btoul(rcaplong.length);
+
+rcap_done:
+
+	bzero(&(&ccb->ccb_h)[1],
+	      sizeof(struct ccb_scsiio) - sizeof(struct ccb_hdr));
+
+	ccb->ccb_h.func_code = XPT_PATH_INQ;
+	ccb->ccb_h.flags = CAM_DIR_NONE;
+	ccb->ccb_h.retry_count = 1;
+	
+	if (cam_send_ccb(cam_dev, ccb) < 0) {
+		warn("error sending XPT_PATH_INQ CCB");
+
+		cam_error_print(cam_dev, ccb, CAM_ESF_ALL,
+				CAM_EPF_ALL, stderr);
+		goto bailout;
+	}
+
+	EV_SET(&ke, cam_dev->fd, EVFILT_READ, EV_ADD|EV_ENABLE, 0, 0, 0);
+
+	dev = camdd_alloc_dev(CAMDD_DEV_PASS, &ke, 1, io_retry_count,
+			      io_timeout);
+	if (dev == NULL)
+		goto bailout;
+
+	pass_dev = &dev->dev_spec.pass;
+	pass_dev->scsi_dev_type = scsi_dev_type;
+	pass_dev->dev = cam_dev;
+	pass_dev->max_sector = maxsector;
+	pass_dev->block_len = block_len;
+	pass_dev->cpi_maxio = ccb->cpi.maxio;
+	snprintf(dev->device_name, sizeof(dev->device_name), "%s%u",
+		 pass_dev->dev->device_name, pass_dev->dev->dev_unit_num);
+	dev->sector_size = block_len;
+	dev->max_sector = maxsector;
+	
+
+	/*
+	 * Determine the optimal blocksize to use for this device.
+	 */
+
+	/*
+	 * If the controller has not specified a maximum I/O size,
+	 * just go with 128K as a somewhat conservative value.
+	 */
+	if (pass_dev->cpi_maxio == 0)
+		cpi_maxio = 131072;
+	else
+		cpi_maxio = pass_dev->cpi_maxio;
+
+	/*
+	 * If the controller has a large maximum I/O size, limit it
+	 * to something smaller so that the kernel doesn't have trouble
+	 * allocating buffers to copy data in and out for us.
+	 * XXX KDM this is until we have unmapped I/O support in the kernel.
+	 */
+	max_iosize = min(cpi_maxio, CAMDD_PASS_MAX_BLOCK);
+
+	/*
+	 * If we weren't able to get a block size for some reason,
+	 * default to 512 bytes.
+	 */
+	block_len = pass_dev->block_len;
+	if (block_len == 0)
+		block_len = 512;
+
+	/*
+	 * Figure out how many blocksize chunks will fit in the
+	 * maximum I/O size.
+	 */
+	pass_numblocks = max_iosize / block_len;
+
+	/*
+	 * And finally, multiple the number of blocks by the LBA
+	 * length to get our maximum block size;
+	 */
+	dev->blocksize = pass_numblocks * block_len;
+
+	if (io_opts->blocksize != 0) {
+		if ((io_opts->blocksize % dev->sector_size) != 0) {
+			warnx("Blocksize %ju for %s is not a multiple of "
+			      "sector size %u", (uintmax_t)io_opts->blocksize, 
+			      dev->device_name, dev->sector_size);
+			goto bailout_error;
+		}
+		dev->blocksize = io_opts->blocksize;
+	}
+	dev->target_queue_depth = CAMDD_PASS_DEFAULT_DEPTH;
+	if (io_opts->queue_depth != 0)
+		dev->target_queue_depth = io_opts->queue_depth;
+
+	if (io_opts->offset != 0) {
+		if (io_opts->offset > (dev->max_sector * dev->sector_size)) {
+			warnx("Offset %ju is past the end of device %s",
+			    io_opts->offset, dev->device_name);
+			goto bailout_error;
+		}
+#if 0
+		else if ((io_opts->offset % dev->sector_size) != 0) {
+			warnx("Offset %ju for %s is not a multiple of the "
+			      "sector size %u", io_opts->offset, 
+			      dev->device_name, dev->sector_size);
+			goto bailout_error;
+		}
+		dev->start_offset_bytes = io_opts->offset;
+#endif
+	}
+
+	dev->min_cmd_size = io_opts->min_cmd_size;
+
+	dev->run = camdd_pass_run;
+	dev->fetch = camdd_pass_fetch;
+
+bailout:
+	cam_freeccb(ccb);
+
+	return (dev);
+
+bailout_error:
+	cam_freeccb(ccb);
+
+	camdd_free_dev(dev);
+
+	return (NULL);
+}
+
+void *
+camdd_worker(void *arg)
+{
+	struct camdd_dev *dev = arg;
+	struct camdd_buf *buf;
+	struct timespec ts, *kq_ts;
+
+	ts.tv_sec = 0;
+	ts.tv_nsec = 0;
+
+	pthread_mutex_lock(&dev->mutex);
+
+	dev->flags |= CAMDD_DEV_FLAG_ACTIVE;
+
+	for (;;) {
+		struct kevent ke;
+		int retval = 0;
+
+		/*
+		 * XXX KDM check the reorder queue depth?
+		 */
+		if (dev->write_dev == 0) {
+			uint32_t our_depth, peer_depth, peer_bytes, our_bytes;
+			uint32_t target_depth = dev->target_queue_depth;
+			uint32_t peer_target_depth =
+			    dev->peer_dev->target_queue_depth;
+			uint32_t peer_blocksize = dev->peer_dev->blocksize;
+
+			camdd_get_depth(dev, &our_depth, &peer_depth,
+					&our_bytes, &peer_bytes);
+
+#if 0
+			while (((our_depth < target_depth)
+			     && (peer_depth < peer_target_depth))
+			    || ((peer_bytes + our_bytes) <
+				 (peer_blocksize * 2))) {
+#endif
+			while (((our_depth + peer_depth) <
+			        (target_depth + peer_target_depth))
+			    || ((peer_bytes + our_bytes) <
+				(peer_blocksize * 3))) {
+
+				retval = camdd_queue(dev, NULL);
+				if (retval == 1)
+					break;
+				else if (retval != 0) {
+					error_exit = 1;
+					goto bailout;
+				}
+
+				camdd_get_depth(dev, &our_depth, &peer_depth,
+						&our_bytes, &peer_bytes);
+			}
+		}
+		/*
+		 * See if we have any I/O that is ready to execute.
+		 */
+		buf = STAILQ_FIRST(&dev->run_queue);
+		if (buf != NULL) {
+			while (dev->target_queue_depth > dev->cur_active_io) {
+				retval = dev->run(dev);
+				if (retval == -1) {
+					dev->flags |= CAMDD_DEV_FLAG_EOF;
+					error_exit = 1;
+					break;
+				} else if (retval != 0) {
+					break;
+				}
+			}
+		}
+
+		/*
+		 * We've reached EOF, or our partner has reached EOF.
+		 */
+		if ((dev->flags & CAMDD_DEV_FLAG_EOF)
+		 || (dev->flags & CAMDD_DEV_FLAG_PEER_EOF)) {
+			if (dev->write_dev != 0) {
+			 	if ((STAILQ_EMPTY(&dev->work_queue))
+				 && (dev->num_run_queue == 0)
+				 && (dev->cur_active_io == 0)) {
+					goto bailout;
+				}
+			} else {
+				/*
+				 * If we're the reader, and the writer
+				 * got EOF, he is already done.  If we got
+				 * the EOF, then we need to wait until
+				 * everything is flushed out for the writer.
+				 */
+				if (dev->flags & CAMDD_DEV_FLAG_PEER_EOF) {
+					goto bailout;
+				} else if ((dev->num_peer_work_queue == 0)
+					&& (dev->num_peer_done_queue == 0)
+					&& (dev->cur_active_io == 0)
+					&& (dev->num_run_queue == 0)) {
+					goto bailout;
+				}
+			}
+			/*
+			 * XXX KDM need to do something about the pending
+			 * queue and cleanup resources.
+			 */
+		} 
+
+		if ((dev->write_dev == 0)
+		 && (dev->cur_active_io == 0)
+		 && (dev->peer_bytes_queued < dev->peer_dev->blocksize))
+			kq_ts = &ts;
+		else
+			kq_ts = NULL;
+
+		/*
+		 * Run kevent to see if there are events to process.
+		 */
+		pthread_mutex_unlock(&dev->mutex);
+		retval = kevent(dev->kq, NULL, 0, &ke, 1, kq_ts);
+		pthread_mutex_lock(&dev->mutex);
+		if (retval == -1) {
+			warn("%s: error returned from kevent",__func__);
+			goto bailout;
+		} else if (retval != 0) {
+			switch (ke.filter) {
+			case EVFILT_READ:
+				if (dev->fetch != NULL) {
+					retval = dev->fetch(dev);
+					if (retval == -1) {
+						error_exit = 1;
+						goto bailout;
+					}
+				}
+				break;
+			case EVFILT_SIGNAL:
+				/*
+				 * We register for this so we don't get
+				 * an error as a result of a SIGINFO or a
+				 * SIGINT.  It will actually get handled
+				 * by the signal handler.  If we get a
+				 * SIGINT, bail out without printing an
+				 * error message.  Any other signals 
+				 * will result in the error message above.
+				 */
+				if (ke.ident == SIGINT)
+					goto bailout;
+				break;
+			case EVFILT_USER:
+				retval = 0;
+				/*
+				 * Check to see if the other thread has
+				 * queued any I/O for us to do.  (In this
+				 * case we're the writer.)
+				 */
+				for (buf = STAILQ_FIRST(&dev->work_queue);
+				     buf != NULL;
+				     buf = STAILQ_FIRST(&dev->work_queue)) {
+					STAILQ_REMOVE_HEAD(&dev->work_queue,
+							   work_links);
+					retval = camdd_queue(dev, buf);
+					/*
+					 * We keep going unless we get an
+					 * actual error.  If we get EOF, we
+					 * still want to remove the buffers
+					 * from the queue and send the back
+					 * to the reader thread.
+					 */
+					if (retval == -1) {
+						error_exit = 1;
+						goto bailout;
+					} else
+						retval = 0;
+				}
+
+				/*
+				 * Next check to see if the other thread has
+				 * queued any completed buffers back to us.
+				 * (In this case we're the reader.)
+				 */
+				for (buf = STAILQ_FIRST(&dev->peer_done_queue);
+				     buf != NULL;
+				     buf = STAILQ_FIRST(&dev->peer_done_queue)){
+					STAILQ_REMOVE_HEAD(
+					    &dev->peer_done_queue, work_links);
+					dev->num_peer_done_queue--;
+					camdd_peer_done(buf);
+				}
+				break;
+			default:
+				warnx("%s: unknown kevent filter %d",
+				      __func__, ke.filter);
+				break;
+			}
+		}
+	}
+
+bailout:
+
+	dev->flags &= ~CAMDD_DEV_FLAG_ACTIVE;
+
+	/* XXX KDM cleanup resources here? */
+
+	pthread_mutex_unlock(&dev->mutex);
+
+	need_exit = 1;
+	sem_post(&camdd_sem);
+
+	return (NULL);
+}
+
+/*
+ * Simplistic translation of CCB status to our local status.
+ */
+camdd_buf_status
+camdd_ccb_status(union ccb *ccb)
+{
+	camdd_buf_status status = CAMDD_STATUS_NONE;
+	cam_status ccb_status;
+
+	ccb_status = ccb->ccb_h.status & CAM_STATUS_MASK;
+
+	switch (ccb_status) {
+	case CAM_REQ_CMP: {
+		if (ccb->csio.resid == 0) {
+			status = CAMDD_STATUS_OK;
+		} else if (ccb->csio.dxfer_len > ccb->csio.resid) {
+			status = CAMDD_STATUS_SHORT_IO;
+		} else {
+			status = CAMDD_STATUS_EOF;
+		}
+		break;
+	}
+	case CAM_SCSI_STATUS_ERROR: {
+		switch (ccb->csio.scsi_status) {
+		case SCSI_STATUS_OK:
+		case SCSI_STATUS_COND_MET:
+		case SCSI_STATUS_INTERMED:
+		case SCSI_STATUS_INTERMED_COND_MET:
+			status = CAMDD_STATUS_OK;
+			break;
+		case SCSI_STATUS_CMD_TERMINATED:
+		case SCSI_STATUS_CHECK_COND:
+		case SCSI_STATUS_QUEUE_FULL:
+		case SCSI_STATUS_BUSY:
+		case SCSI_STATUS_RESERV_CONFLICT:
+		default:
+			status = CAMDD_STATUS_ERROR;
+			break;
+		}
+		break;
+	}
+	default:
+		status = CAMDD_STATUS_ERROR;
+		break;
+	}
+
+	return (status);
+}
+
+/*
+ * Queue a buffer to our peer's work thread for writing.
+ *
+ * Returns 0 for success, -1 for failure, 1 if the other thread exited.
+ */
+int
+camdd_queue_peer_buf(struct camdd_dev *dev, struct camdd_buf *buf)
+{
+	struct kevent ke;
+	STAILQ_HEAD(, camdd_buf) local_queue;
+	struct camdd_buf *buf1, *buf2;
+	struct camdd_buf_data *data = NULL;
+	uint64_t peer_bytes_queued = 0;
+	int active = 1;
+	int retval = 0;
+
+	STAILQ_INIT(&local_queue);
+
+	/*
+	 * Since we're the reader, we need to queue our I/O to the writer
+	 * in sequential order in order to make sure it gets written out
+	 * in sequential order.
+	 *
+	 * Check the next expected I/O starting offset.  If this doesn't
+	 * match, put it on the reorder queue.
+	 */
+	if ((buf->lba * dev->sector_size) != dev->next_completion_pos_bytes) {
+
+		/*
+		 * If there is nothing on the queue, there is no sorting
+		 * needed.
+		 */
+		if (STAILQ_EMPTY(&dev->reorder_queue)) {
+			STAILQ_INSERT_TAIL(&dev->reorder_queue, buf, links);
+			dev->num_reorder_queue++;
+			goto bailout;
+		}
+
+		/*
+		 * Sort in ascending order by starting LBA.  There should
+		 * be no identical LBAs.
+		 */
+		for (buf1 = STAILQ_FIRST(&dev->reorder_queue); buf1 != NULL;
+		     buf1 = buf2) {
+			buf2 = STAILQ_NEXT(buf1, links);
+			if (buf->lba < buf1->lba) {
+				/*
+				 * If we're less than the first one, then
+				 * we insert at the head of the list
+				 * because this has to be the first element
+				 * on the list.
+				 */
+				STAILQ_INSERT_HEAD(&dev->reorder_queue,
+						   buf, links);
+				dev->num_reorder_queue++;
+				break;
+			} else if (buf->lba > buf1->lba) {
+				if (buf2 == NULL) {
+					STAILQ_INSERT_TAIL(&dev->reorder_queue, 
+					    buf, links);
+					dev->num_reorder_queue++;
+					break;
+				} else if (buf->lba < buf2->lba) {
+					STAILQ_INSERT_AFTER(&dev->reorder_queue,
+					    buf1, buf, links);
+					dev->num_reorder_queue++;
+					break;
+				}
+			} else {
+				errx(1, "Found buffers with duplicate LBA %ju!",
+				     buf->lba);
+			}
+		}
+		goto bailout;
+	} else {
+
+		/*
+		 * We're the next expected I/O completion, so put ourselves
+		 * on the local queue to be sent to the writer.  We use
+		 * work_links here so that we can queue this to the 
+		 * peer_work_queue before taking the buffer off of the
+		 * local_queue.
+		 */
+		dev->next_completion_pos_bytes += buf->len;
+		STAILQ_INSERT_TAIL(&local_queue, buf, work_links);
+
+		/*
+		 * Go through the reorder queue looking for more sequential
+		 * I/O and add it to the local queue.
+		 */
+		for (buf1 = STAILQ_FIRST(&dev->reorder_queue); buf1 != NULL;
+		     buf1 = STAILQ_FIRST(&dev->reorder_queue)) {
+			/*
+			 * As soon as we see an I/O that is out of sequence,
+			 * we're done.
+			 */
+			if ((buf1->lba * dev->sector_size) !=
+			     dev->next_completion_pos_bytes)
+				break;
+
+			STAILQ_REMOVE_HEAD(&dev->reorder_queue, links);
+			dev->num_reorder_queue--;
+			STAILQ_INSERT_TAIL(&local_queue, buf1, work_links);
+			dev->next_completion_pos_bytes += buf1->len;
+		}
+	}
+
+	/*
+	 * Setup the event to let the other thread know that it has work
+	 * pending.
+	 */
+	EV_SET(&ke, (uintptr_t)&dev->peer_dev->work_queue, EVFILT_USER, 0,
+	       NOTE_TRIGGER, 0, NULL);
+
+	/*
+	 * Put this on our shadow queue so that we know what we've queued
+	 * to the other thread.
+	 */
+	STAILQ_FOREACH_SAFE(buf1, &local_queue, work_links, buf2) {
+		if (buf1->buf_type != CAMDD_BUF_DATA) {
+			errx(1, "%s: should have a data buffer, not an "
+			    "indirect buffer", __func__);
+		}
+		data = &buf1->buf_type_spec.data;
+
+		/*
+		 * We only need to send one EOF to the writer, and don't
+		 * need to continue sending EOFs after that.
+		 */
+		if (buf1->status == CAMDD_STATUS_EOF) {
+			if (dev->flags & CAMDD_DEV_FLAG_EOF_SENT) {
+				STAILQ_REMOVE(&local_queue, buf1, camdd_buf,
+				    work_links);
+				camdd_release_buf(buf1);
+				retval = 1;
+				continue;
+			}
+			dev->flags |= CAMDD_DEV_FLAG_EOF_SENT;
+		}
+
+
+		STAILQ_INSERT_TAIL(&dev->peer_work_queue, buf1, links);
+		peer_bytes_queued += (data->fill_len - data->resid);
+		dev->peer_bytes_queued += (data->fill_len - data->resid);
+		dev->num_peer_work_queue++;
+	}
+
+	if (STAILQ_FIRST(&local_queue) == NULL)
+		goto bailout;
+
+	/*
+	 * Drop our mutex and pick up the other thread's mutex.  We need to
+	 * do this to avoid deadlocks.
+	 */
+	pthread_mutex_unlock(&dev->mutex);
+	pthread_mutex_lock(&dev->peer_dev->mutex);
+
+	if (dev->peer_dev->flags & CAMDD_DEV_FLAG_ACTIVE) {
+		/*
+		 * Put the buffers on the other thread's incoming work queue.
+		 */
+		for (buf1 = STAILQ_FIRST(&local_queue); buf1 != NULL;
+		     buf1 = STAILQ_FIRST(&local_queue)) {
+			STAILQ_REMOVE_HEAD(&local_queue, work_links);
+			STAILQ_INSERT_TAIL(&dev->peer_dev->work_queue, buf1,
+					   work_links);
+		}
+		/*
+		 * Send an event to the other thread's kqueue to let it know
+		 * that there is something on the work queue.
+		 */
+		retval = kevent(dev->peer_dev->kq, &ke, 1, NULL, 0, NULL);
+		if (retval == -1)
+			warn("%s: unable to add peer work_queue kevent",
+			     __func__);
+		else
+			retval = 0;
+	} else
+		active = 0;
+
+	pthread_mutex_unlock(&dev->peer_dev->mutex);
+	pthread_mutex_lock(&dev->mutex);
+
+	/*
+	 * If the other side isn't active, run through the queue and
+	 * release all of the buffers.
+	 */
+	if (active == 0) {
+		for (buf1 = STAILQ_FIRST(&local_queue); buf1 != NULL;
+		     buf1 = STAILQ_FIRST(&local_queue)) {
+			STAILQ_REMOVE_HEAD(&local_queue, work_links);
+			STAILQ_REMOVE(&dev->peer_work_queue, buf1, camdd_buf,
+				      links);
+			dev->num_peer_work_queue--;
+			camdd_release_buf(buf1);
+		}
+		dev->peer_bytes_queued -= peer_bytes_queued;
+		retval = 1;
+	}
+
+bailout:
+	return (retval);
+}
+
+/*
+ * Return a buffer to the reader thread when we have completed writing it.
+ */
+int
+camdd_complete_peer_buf(struct camdd_dev *dev, struct camdd_buf *peer_buf)
+{
+	struct kevent ke;
+	int retval = 0;
+
+	/*
+	 * Setup the event to let the other thread know that we have
+	 * completed a buffer.
+	 */
+	EV_SET(&ke, (uintptr_t)&dev->peer_dev->peer_done_queue, EVFILT_USER, 0,
+	       NOTE_TRIGGER, 0, NULL);
+
+	/*
+	 * Drop our lock and acquire the other thread's lock before
+	 * manipulating 
+	 */
+	pthread_mutex_unlock(&dev->mutex);
+	pthread_mutex_lock(&dev->peer_dev->mutex);
+
+	/*
+	 * Put the buffer on the reader thread's peer done queue now that
+	 * we have completed it.
+	 */
+	STAILQ_INSERT_TAIL(&dev->peer_dev->peer_done_queue, peer_buf,
+			   work_links);
+	dev->peer_dev->num_peer_done_queue++;
+
+	/*
+	 * Send an event to the peer thread to let it know that we've added
+	 * something to its peer done queue.
+	 */
+	retval = kevent(dev->peer_dev->kq, &ke, 1, NULL, 0, NULL);
+	if (retval == -1)
+		warn("%s: unable to add peer_done_queue kevent", __func__);
+	else
+		retval = 0;
+
+	/*
+	 * Drop the other thread's lock and reacquire ours.
+	 */
+	pthread_mutex_unlock(&dev->peer_dev->mutex);
+	pthread_mutex_lock(&dev->mutex);
+
+	return (retval);
+}
+
+/*
+ * Free a buffer that was written out by the writer thread and returned to
+ * the reader thread.
+ */
+void
+camdd_peer_done(struct camdd_buf *buf)
+{
+	struct camdd_dev *dev;
+	struct camdd_buf_data *data;
+
+	dev = buf->dev;
+	if (buf->buf_type != CAMDD_BUF_DATA) {
+		errx(1, "%s: should have a data buffer, not an "
+		    "indirect buffer", __func__);
+	}
+
+	data = &buf->buf_type_spec.data;
+
+	STAILQ_REMOVE(&dev->peer_work_queue, buf, camdd_buf, links);
+	dev->num_peer_work_queue--;
+	dev->peer_bytes_queued -= (data->fill_len - data->resid);
+
+	if (buf->status == CAMDD_STATUS_EOF)
+		dev->flags |= CAMDD_DEV_FLAG_PEER_EOF;
+
+	STAILQ_INSERT_TAIL(&dev->free_queue, buf, links);
+}
+
+/*
+ * Assumes caller holds the lock for this device.
+ */
+void
+camdd_complete_buf(struct camdd_dev *dev, struct camdd_buf *buf,
+		   int *error_count)
+{
+	int retval = 0;
+
+	/*
+	 * If we're the reader, we need to send the completed I/O
+	 * to the writer.  If we're the writer, we need to just
+	 * free up resources, or let the reader know if we've
+	 * encountered an error.
+	 */
+	if (dev->write_dev == 0) {
+		retval = camdd_queue_peer_buf(dev, buf);
+		if (retval != 0)
+			(*error_count)++;
+	} else {
+		struct camdd_buf *tmp_buf, *next_buf;
+
+		STAILQ_FOREACH_SAFE(tmp_buf, &buf->src_list, src_links,
+				    next_buf) {
+			struct camdd_buf *src_buf;
+			struct camdd_buf_indirect *indirect;
+
+			STAILQ_REMOVE(&buf->src_list, tmp_buf,
+				      camdd_buf, src_links);
+
+			tmp_buf->status = buf->status;
+
+			if (tmp_buf->buf_type == CAMDD_BUF_DATA) {
+				camdd_complete_peer_buf(dev, tmp_buf);
+				continue;
+			}
+
+			indirect = &tmp_buf->buf_type_spec.indirect;
+			src_buf = indirect->src_buf;
+			src_buf->refcount--;
+			/*
+			 * XXX KDM we probably need to account for
+			 * exactly how many bytes we were able to
+			 * write.  Allocate the residual to the
+			 * first N buffers?  Or just track the
+			 * number of bytes written?  Right now the reader
+			 * doesn't do anything with a residual.
+			 */
+			src_buf->status = buf->status;
+			if (src_buf->refcount <= 0)
+				camdd_complete_peer_buf(dev, src_buf);
+			STAILQ_INSERT_TAIL(&dev->free_indirect_queue,
+					   tmp_buf, links);
+		}
+
+		STAILQ_INSERT_TAIL(&dev->free_queue, buf, links);
+	}
+}
+
+/*
+ * Fetch all completed commands from the pass(4) device.
+ *
+ * Returns the number of commands received, or -1 if any of the commands
+ * completed with an error.  Returns 0 if no commands are available.
+ */
+int
+camdd_pass_fetch(struct camdd_dev *dev)
+{
+	struct camdd_dev_pass *pass_dev = &dev->dev_spec.pass;
+	union ccb ccb;
+	int retval = 0, num_fetched = 0, error_count = 0;
+
+	pthread_mutex_unlock(&dev->mutex);
+	/*
+	 * XXX KDM we don't distinguish between EFAULT and ENOENT.
+	 */
+	while ((retval = ioctl(pass_dev->dev->fd, CAMIOGET, &ccb)) != -1) {
+		struct camdd_buf *buf;
+		struct camdd_buf_data *data;
+		cam_status ccb_status;
+		union ccb *buf_ccb;
+
+		buf = ccb.ccb_h.ccb_buf;
+		data = &buf->buf_type_spec.data;
+		buf_ccb = &data->ccb;
+
+		num_fetched++;
+
+		/*
+		 * Copy the CCB back out so we get status, sense data, etc.
+		 */
+		bcopy(&ccb, buf_ccb, sizeof(ccb));
+
+		pthread_mutex_lock(&dev->mutex);
+
+		/*
+		 * We're now done, so take this off the active queue.
+		 */
+		STAILQ_REMOVE(&dev->active_queue, buf, camdd_buf, links);
+		dev->cur_active_io--;
+
+		ccb_status = ccb.ccb_h.status & CAM_STATUS_MASK;
+		if (ccb_status != CAM_REQ_CMP) {
+			cam_error_print(pass_dev->dev, &ccb, CAM_ESF_ALL,
+					CAM_EPF_ALL, stderr);
+		}
+
+		data->resid = ccb.csio.resid;
+		dev->bytes_transferred += (ccb.csio.dxfer_len - ccb.csio.resid);
+
+		if (buf->status == CAMDD_STATUS_NONE)
+			buf->status = camdd_ccb_status(&ccb);
+		if (buf->status == CAMDD_STATUS_ERROR)
+			error_count++;
+		else if (buf->status == CAMDD_STATUS_EOF) {
+			/*
+			 * Once we queue this buffer to our partner thread,
+			 * he will know that we've hit EOF.
+			 */
+			dev->flags |= CAMDD_DEV_FLAG_EOF;
+		}
+
+		camdd_complete_buf(dev, buf, &error_count);
+
+		/*
+		 * Unlock in preparation for the ioctl call.
+		 */
+		pthread_mutex_unlock(&dev->mutex);
+	}
+
+	pthread_mutex_lock(&dev->mutex);
+
+	if (error_count > 0)
+		return (-1);
+	else
+		return (num_fetched);
+}
+
+/*
+ * Returns -1 for error, 0 for success/continue, and 1 for resource
+ * shortage/stop processing.
+ */
+int
+camdd_file_run(struct camdd_dev *dev)
+{
+	struct camdd_dev_file *file_dev = &dev->dev_spec.file;
+	struct camdd_buf_data *data;
+	struct camdd_buf *buf;
+	off_t io_offset;
+	int retval = 0, write_dev = dev->write_dev;
+	int error_count = 0, no_resources = 0, double_buf_needed = 0;
+	uint32_t num_sectors = 0, db_len = 0;
+
+	buf = STAILQ_FIRST(&dev->run_queue);
+	if (buf == NULL) {
+		no_resources = 1;
+		goto bailout;
+	} else if ((dev->write_dev == 0)
+		&& (dev->flags & (CAMDD_DEV_FLAG_EOF |
+				  CAMDD_DEV_FLAG_EOF_SENT))) {
+		STAILQ_REMOVE(&dev->run_queue, buf, camdd_buf, links);
+		dev->num_run_queue--;
+		buf->status = CAMDD_STATUS_EOF;
+		error_count++;
+		goto bailout;
+	}
+
+	/*
+	 * If we're writing, we need to go through the source buffer list
+	 * and create an S/G list.
+	 */
+	if (write_dev != 0) {
+		retval = camdd_buf_sg_create(buf, /*iovec*/ 1,
+		    dev->sector_size, &num_sectors, &double_buf_needed);
+		if (retval != 0) {
+			no_resources = 1;
+			goto bailout;
+		}
+	}
+
+	STAILQ_REMOVE(&dev->run_queue, buf, camdd_buf, links);
+	dev->num_run_queue--;
+
+	data = &buf->buf_type_spec.data;
+
+	/*
+	 * pread(2) and pwrite(2) offsets are byte offsets.
+	 */
+	io_offset = buf->lba * dev->sector_size;
+
+	/*
+	 * Unlock the mutex while we read or write.
+	 */
+	pthread_mutex_unlock(&dev->mutex);
+
+	/*
+	 * Note that we don't need to double buffer if we're the reader
+	 * because in that case, we have allocated a single buffer of
+	 * sufficient size to do the read.  This copy is necessary on
+	 * writes because if one of the components of the S/G list is not
+	 * a sector size multiple, the kernel will reject the write.  This
+	 * is unfortunate but not surprising.  So this will make sure that
+	 * we're using a single buffer that is a multiple of the sector size.
+	 */
+	if ((double_buf_needed != 0)
+	 && (data->sg_count > 1)
+	 && (write_dev != 0)) {
+		uint32_t cur_offset;
+		int i;
+
+		if (file_dev->tmp_buf == NULL)
+			file_dev->tmp_buf = calloc(dev->blocksize, 1);
+		if (file_dev->tmp_buf == NULL) {
+			buf->status = CAMDD_STATUS_ERROR;
+			error_count++;
+			goto bailout;
+		}
+		for (i = 0, cur_offset = 0; i < data->sg_count; i++) {
+			bcopy(data->iovec[i].iov_base,
+			    &file_dev->tmp_buf[cur_offset],
+			    data->iovec[i].iov_len);
+			cur_offset += data->iovec[i].iov_len;
+		}
+		db_len = cur_offset;
+	}
+
+	if (file_dev->file_flags & CAMDD_FF_CAN_SEEK) {
+		if (write_dev == 0) {
+			/*
+			 * XXX KDM is there any way we would need a S/G
+			 * list here?
+			 */
+			retval = pread(file_dev->fd, data->buf,
+			    buf->len, io_offset);
+		} else {
+			if (double_buf_needed != 0) {
+				retval = pwrite(file_dev->fd, file_dev->tmp_buf,
+				    db_len, io_offset);
+			} else if (data->sg_count == 0) {
+				retval = pwrite(file_dev->fd, data->buf,
+				    data->fill_len, io_offset);
+			} else {
+				retval = pwritev(file_dev->fd, data->iovec,
+				    data->sg_count, io_offset);
+			}
+		}
+	} else {
+		if (write_dev == 0) {
+			/*
+			 * XXX KDM is there any way we would need a S/G
+			 * list here?
+			 */
+			retval = read(file_dev->fd, data->buf, buf->len);
+		} else {
+			if (double_buf_needed != 0) {
+				retval = write(file_dev->fd, file_dev->tmp_buf,
+				    db_len);
+			} else if (data->sg_count == 0) {
+				retval = write(file_dev->fd, data->buf,
+				    data->fill_len);
+			} else {
+				retval = writev(file_dev->fd, data->iovec,
+				    data->sg_count);
+			}
+		}
+	}
+
+	/* We're done, re-acquire the lock */
+	pthread_mutex_lock(&dev->mutex);
+
+	if (retval >= (ssize_t)data->fill_len) {
+		/*
+		 * If the bytes transferred is more than the request size,
+		 * that indicates an overrun, which should only happen at
+		 * the end of a transfer if we have to round up to a sector
+		 * boundary.
+		 */
+		if (buf->status == CAMDD_STATUS_NONE)
+			buf->status = CAMDD_STATUS_OK;
+		data->resid = 0;
+		dev->bytes_transferred += retval;
+	} else if (retval == -1) {
+		warn("Error %s %s", (write_dev) ? "writing to" :
+		    "reading from", file_dev->filename);
+
+		buf->status = CAMDD_STATUS_ERROR;
+		data->resid = data->fill_len;
+		error_count++;
+
+		if (dev->debug == 0)
+			goto bailout;
+
+		if ((double_buf_needed != 0)
+		 && (write_dev != 0)) {
+			fprintf(stderr, "%s: fd %d, DB buf %p, len %u lba %ju "
+			    "offset %ju\n", __func__, file_dev->fd,
+			    file_dev->tmp_buf, db_len, (uintmax_t)buf->lba,
+			    (uintmax_t)io_offset);
+		} else if (data->sg_count == 0) {
+			fprintf(stderr, "%s: fd %d, buf %p, len %u, lba %ju "
+			    "offset %ju\n", __func__, file_dev->fd, data->buf,
+			    data->fill_len, (uintmax_t)buf->lba,
+			    (uintmax_t)io_offset);
+		} else {
+			int i;
+
+			fprintf(stderr, "%s: fd %d, len %u, lba %ju "
+			    "offset %ju\n", __func__, file_dev->fd, 
+			    data->fill_len, (uintmax_t)buf->lba,
+			    (uintmax_t)io_offset);
+
+			for (i = 0; i < data->sg_count; i++) {
+				fprintf(stderr, "index %d ptr %p len %zu\n",
+				    i, data->iovec[i].iov_base,
+				    data->iovec[i].iov_len);
+			}
+		}
+	} else if (retval == 0) {
+		buf->status = CAMDD_STATUS_EOF;
+		if (dev->debug != 0)
+			printf("%s: got EOF from %s!\n", __func__,
+			    file_dev->filename);
+		data->resid = data->fill_len;
+		error_count++;
+	} else if (retval < (ssize_t)data->fill_len) {
+		if (buf->status == CAMDD_STATUS_NONE)
+			buf->status = CAMDD_STATUS_SHORT_IO;
+		data->resid = data->fill_len - retval;
+		dev->bytes_transferred += retval;
+	}
+
+bailout:
+	if (buf != NULL) {
+		if (buf->status == CAMDD_STATUS_EOF) {
+			struct camdd_buf *buf2;
+			dev->flags |= CAMDD_DEV_FLAG_EOF;
+			STAILQ_FOREACH(buf2, &dev->run_queue, links)
+				buf2->status = CAMDD_STATUS_EOF;
+		}
+
+		camdd_complete_buf(dev, buf, &error_count);
+	}
+
+	if (error_count != 0)
+		return (-1);
+	else if (no_resources != 0)
+		return (1);
+	else
+		return (0);
+}
+
+/*
+ * Execute one command from the run queue.  Returns 0 for success, 1 for
+ * stop processing, and -1 for error.
+ */
+int
+camdd_pass_run(struct camdd_dev *dev)
+{
+	struct camdd_buf *buf = NULL;
+	struct camdd_dev_pass *pass_dev = &dev->dev_spec.pass;
+	struct camdd_buf_data *data;
+	uint32_t num_blocks, sectors_used = 0;
+	union ccb *ccb;
+	int retval = 0, is_write = dev->write_dev;
+	int double_buf_needed = 0;
+
+	buf = STAILQ_FIRST(&dev->run_queue);
+	if (buf == NULL) {
+		retval = 1;
+		goto bailout;
+	}
+
+	/*
+	 * If we're writing, we need to go through the source buffer list
+	 * and create an S/G list.
+	 */
+	if (is_write != 0) {
+		retval = camdd_buf_sg_create(buf, /*iovec*/ 0,dev->sector_size,
+		    &sectors_used, &double_buf_needed);
+		if (retval != 0) {
+			retval = -1;
+			goto bailout;
+		}
+	}
+
+	STAILQ_REMOVE(&dev->run_queue, buf, camdd_buf, links);
+	dev->num_run_queue--;
+
+	data = &buf->buf_type_spec.data;
+
+	ccb = &data->ccb;
+	bzero(&(&ccb->ccb_h)[1],
+	      sizeof(struct ccb_scsiio) - sizeof(struct ccb_hdr));
+
+	/*
+	 * In almost every case the number of blocks should be the device
+	 * block size.  The exception may be at the end of an I/O stream
+	 * for a partial block or at the end of a device.
+	 */
+	if (is_write != 0)
+		num_blocks = sectors_used;
+	else
+		num_blocks = data->fill_len / pass_dev->block_len;
+
+	scsi_read_write(&ccb->csio,
+			/*retries*/ dev->retry_count,
+			/*cbfcnp*/ NULL,
+			/*tag_action*/ MSG_SIMPLE_Q_TAG,
+			/*readop*/ (dev->write_dev == 0) ? SCSI_RW_READ :
+				   SCSI_RW_WRITE,
+			/*byte2*/ 0,
+			/*minimum_cmd_size*/ dev->min_cmd_size,
+			/*lba*/ buf->lba,
+			/*block_count*/ num_blocks,
+			/*data_ptr*/ (data->sg_count != 0) ?
+				     (uint8_t *)data->segs : data->buf,
+			/*dxfer_len*/ (num_blocks * pass_dev->block_len),
+			/*sense_len*/ SSD_FULL_SIZE,
+			/*timeout*/ dev->io_timeout);
+
+	/* Disable freezing the device queue */
+	ccb->ccb_h.flags |= CAM_DEV_QFRZDIS;
+
+	if (dev->retry_count != 0)
+		ccb->ccb_h.flags |= CAM_PASS_ERR_RECOVER;
+
+	if (data->sg_count != 0) {
+		ccb->csio.sglist_cnt = data->sg_count;
+		ccb->ccb_h.flags |= CAM_DATA_SG;
+	}
+
+	/*
+	 * Store a pointer to the buffer in the CCB.  The kernel will
+	 * restore this when we get it back, and we'll use it to identify
+	 * the buffer this CCB came from.
+	 */
+	ccb->ccb_h.ccb_buf = buf;
+
+	/*
+	 * Unlock our mutex in preparation for issuing the ioctl.
+	 */
+	pthread_mutex_unlock(&dev->mutex);
+	/*
+	 * Queue the CCB to the pass(4) driver.
+	 */
+	if (ioctl(pass_dev->dev->fd, CAMIOQUEUE, ccb) == -1) {
+		pthread_mutex_lock(&dev->mutex);
+
+		warn("%s: error sending CAMIOQUEUE ioctl to %s%u", __func__,
+		     pass_dev->dev->device_name, pass_dev->dev->dev_unit_num);
+		warn("%s: CCB address is %p", __func__, ccb);
+		retval = -1;
+
+		STAILQ_INSERT_TAIL(&dev->free_queue, buf, links);
+	} else {
+		pthread_mutex_lock(&dev->mutex);
+
+		dev->cur_active_io++;
+		STAILQ_INSERT_TAIL(&dev->active_queue, buf, links);
+	}
+
+bailout:
+	return (retval);
+}
+
+int
+camdd_get_next_lba_len(struct camdd_dev *dev, uint64_t *lba, ssize_t *len)
+{
+	struct camdd_dev_pass *pass_dev;
+	uint32_t num_blocks;
+	int retval = 0;
+
+	pass_dev = &dev->dev_spec.pass;
+
+	*lba = dev->next_io_pos_bytes / dev->sector_size;
+	*len = dev->blocksize;
+	num_blocks = *len / dev->sector_size;
+
+	/*
+	 * If max_sector is 0, then we have no set limit.  This can happen
+	 * if we're writing to a file in a filesystem, or reading from
+	 * something like /dev/zero.
+	 */
+	if ((dev->max_sector != 0)
+	 || (dev->sector_io_limit != 0)) {
+		uint64_t max_sector;
+
+		if ((dev->max_sector != 0)
+		 && (dev->sector_io_limit != 0)) 
+			max_sector = min(dev->sector_io_limit, dev->max_sector);
+		else if (dev->max_sector != 0)
+			max_sector = dev->max_sector;
+		else
+			max_sector = dev->sector_io_limit;
+
+
+		/*
+		 * Check to see whether we're starting off past the end of
+		 * the device.  If so, we need to just send an EOF 	
+		 * notification to the writer.
+		 */
+		if (*lba > max_sector) {
+			*len = 0;
+			retval = 1;
+		} else if (((*lba + num_blocks) > max_sector + 1)
+			|| ((*lba + num_blocks) < *lba)) {
+			/*
+			 * If we get here (but pass the first check), we
+			 * can trim the request length down to go to the
+			 * end of the device.
+			 */
+			num_blocks = (max_sector + 1) - *lba;
+			*len = num_blocks * dev->sector_size;
+			retval = 1;
+		}
+	}
+
+	dev->next_io_pos_bytes += *len;
+
+	return (retval);
+}
+
+/*
+ * Returns 0 for success, 1 for EOF detected, and -1 for failure.
+ */
+int
+camdd_queue(struct camdd_dev *dev, struct camdd_buf *read_buf)
+{
+	struct camdd_buf *buf = NULL;
+	struct camdd_buf_data *data;
+	struct camdd_dev_pass *pass_dev;
+	size_t new_len;
+	struct camdd_buf_data *rb_data;
+	int is_write = dev->write_dev;
+	int eof_flush_needed = 0;
+	int retval = 0;
+	int error;
+
+	pass_dev = &dev->dev_spec.pass;
+
+	/*
+	 * If we've gotten EOF or our partner has, we should not continue
+	 * queueing I/O.  If we're a writer, though, we should continue
+	 * to write any buffers that don't have EOF status.
+	 */
+	if ((dev->flags & CAMDD_DEV_FLAG_EOF)
+	 || ((dev->flags & CAMDD_DEV_FLAG_PEER_EOF)
+	  && (is_write == 0))) {
+		/*
+		 * Tell the worker thread that we have seen EOF.
+		 */
+		retval = 1;
+
+		/*
+		 * If we're the writer, send the buffer back with EOF status.
+		 */
+		if (is_write) {
+			read_buf->status = CAMDD_STATUS_EOF;
+			
+			error = camdd_complete_peer_buf(dev, read_buf);
+		}
+		goto bailout;
+	}
+
+	if (is_write == 0) {
+		buf = camdd_get_buf(dev, CAMDD_BUF_DATA);
+		if (buf == NULL) {
+			retval = -1;
+			goto bailout;
+		}
+		data = &buf->buf_type_spec.data;
+
+		retval = camdd_get_next_lba_len(dev, &buf->lba, &buf->len);
+		if (retval != 0) {
+			buf->status = CAMDD_STATUS_EOF;
+
+		 	if ((buf->len == 0)
+			 && ((dev->flags & (CAMDD_DEV_FLAG_EOF_SENT |
+			     CAMDD_DEV_FLAG_EOF_QUEUED)) != 0)) {
+				camdd_release_buf(buf);
+				goto bailout;
+			}
+			dev->flags |= CAMDD_DEV_FLAG_EOF_QUEUED;
+		}
+
+		data->fill_len = buf->len;
+		data->src_start_offset = buf->lba * dev->sector_size;
+
+		/*
+		 * Put this on the run queue.
+		 */
+		STAILQ_INSERT_TAIL(&dev->run_queue, buf, links);
+		dev->num_run_queue++;
+
+		/* We're done. */
+		goto bailout;
+	}
+
+	/*
+	 * Check for new EOF status from the reader.
+	 */
+	if ((read_buf->status == CAMDD_STATUS_EOF)
+	 || (read_buf->status == CAMDD_STATUS_ERROR)) {
+		dev->flags |= CAMDD_DEV_FLAG_PEER_EOF;
+		if ((STAILQ_FIRST(&dev->pending_queue) == NULL)
+		 && (read_buf->len == 0)) {
+			camdd_complete_peer_buf(dev, read_buf);
+			retval = 1;
+			goto bailout;
+		} else
+			eof_flush_needed = 1;
+	}
+
+	/*
+	 * See if we have a buffer we're composing with pieces from our
+	 * partner thread.
+	 */
+	buf = STAILQ_FIRST(&dev->pending_queue);
+	if (buf == NULL) {
+		uint64_t lba;
+		ssize_t len;
+
+		retval = camdd_get_next_lba_len(dev, &lba, &len);
+		if (retval != 0) {
+			read_buf->status = CAMDD_STATUS_EOF;
+
+			if (len == 0) {
+				dev->flags |= CAMDD_DEV_FLAG_EOF;
+				error = camdd_complete_peer_buf(dev, read_buf);
+				goto bailout;
+			}
+		}
+
+		/*
+		 * If we don't have a pending buffer, we need to grab a new
+		 * one from the free list or allocate another one.
+		 */
+		buf = camdd_get_buf(dev, CAMDD_BUF_DATA);
+		if (buf == NULL) {
+			retval = 1;
+			goto bailout;
+		}
+
+		buf->lba = lba;
+		buf->len = len;
+
+		STAILQ_INSERT_TAIL(&dev->pending_queue, buf, links);
+		dev->num_pending_queue++;
+	}
+
+	data = &buf->buf_type_spec.data;
+
+	rb_data = &read_buf->buf_type_spec.data;
+
+	if ((rb_data->src_start_offset != dev->next_peer_pos_bytes)
+	 && (dev->debug != 0)) {
+		printf("%s: WARNING: reader offset %#jx != expected offset "
+		    "%#jx\n", __func__, (uintmax_t)rb_data->src_start_offset,
+		    (uintmax_t)dev->next_peer_pos_bytes);
+	}
+	dev->next_peer_pos_bytes = rb_data->src_start_offset +
+	    (rb_data->fill_len - rb_data->resid);
+
+	new_len = (rb_data->fill_len - rb_data->resid) + data->fill_len;
+	if (new_len < buf->len) {
+		/*
+		 * There are three cases here:
+		 * 1. We need more data to fill up a block, so we put 
+		 *    this I/O on the queue and wait for more I/O.
+		 * 2. We have a pending buffer in the queue that is
+		 *    smaller than our blocksize, but we got an EOF.  So we
+		 *    need to go ahead and flush the write out.
+		 * 3. We got an error.
+		 */
+
+		/*
+		 * Increment our fill length.
+		 */
+		data->fill_len += (rb_data->fill_len - rb_data->resid);
+
+		/*
+		 * Add the new read buffer to the list for writing.
+		 */
+		STAILQ_INSERT_TAIL(&buf->src_list, read_buf, src_links);
+
+		/* Increment the count */
+		buf->src_count++;
+
+		if (eof_flush_needed == 0) {
+			/*
+			 * We need to exit, because we don't have enough
+			 * data yet.
+			 */
+			goto bailout;
+		} else {
+			/*
+			 * Take the buffer off of the pending queue.
+			 */
+			STAILQ_REMOVE(&dev->pending_queue, buf, camdd_buf,
+				      links);
+			dev->num_pending_queue--;
+
+			/*
+			 * If we need an EOF flush, but there is no data
+			 * to flush, go ahead and return this buffer.
+			 */
+			if (data->fill_len == 0) {
+				camdd_complete_buf(dev, buf, /*error_count*/0);
+				retval = 1;
+				goto bailout;
+			}
+
+			/*
+			 * Put this on the next queue for execution.
+			 */
+			STAILQ_INSERT_TAIL(&dev->run_queue, buf, links);
+			dev->num_run_queue++;
+		}
+	} else if (new_len == buf->len) {
+		/*
+		 * We have enough data to completey fill one block,
+		 * so we're ready to issue the I/O.
+		 */
+
+		/*
+		 * Take the buffer off of the pending queue.
+		 */
+		STAILQ_REMOVE(&dev->pending_queue, buf, camdd_buf, links);
+		dev->num_pending_queue--;
+
+		/*
+		 * Add the new read buffer to the list for writing.
+		 */
+		STAILQ_INSERT_TAIL(&buf->src_list, read_buf, src_links);
+
+		/* Increment the count */
+		buf->src_count++;
+
+		/*
+		 * Increment our fill length.
+		 */
+		data->fill_len += (rb_data->fill_len - rb_data->resid);
+
+		/*
+		 * Put this on the next queue for execution.
+		 */
+		STAILQ_INSERT_TAIL(&dev->run_queue, buf, links);
+		dev->num_run_queue++;
+	} else {
+		struct camdd_buf *idb;
+		struct camdd_buf_indirect *indirect;
+		uint32_t len_to_go, cur_offset;
+
+		
+		idb = camdd_get_buf(dev, CAMDD_BUF_INDIRECT);
+		if (idb == NULL) {
+			retval = 1;
+			goto bailout;
+		}
+		indirect = &idb->buf_type_spec.indirect;
+		indirect->src_buf = read_buf;
+		read_buf->refcount++;
+		indirect->offset = 0;
+		indirect->start_ptr = rb_data->buf;
+		/*
+		 * We've already established that there is more
+		 * data in read_buf than we have room for in our
+		 * current write request.  So this particular chunk
+		 * of the request should just be the remainder
+		 * needed to fill up a block.
+		 */
+		indirect->len = buf->len - (data->fill_len - data->resid);
+
+		camdd_buf_add_child(buf, idb);
+
+		/*
+		 * This buffer is ready to execute, so we can take
+		 * it off the pending queue and put it on the run
+		 * queue.
+		 */
+		STAILQ_REMOVE(&dev->pending_queue, buf, camdd_buf,
+			      links);
+		dev->num_pending_queue--;
+		STAILQ_INSERT_TAIL(&dev->run_queue, buf, links);
+		dev->num_run_queue++;
+
+		cur_offset = indirect->offset + indirect->len;
+
+		/*
+		 * The resulting I/O would be too large to fit in
+		 * one block.  We need to split this I/O into
+		 * multiple pieces.  Allocate as many buffers as needed.
+		 */
+		for (len_to_go = rb_data->fill_len - rb_data->resid -
+		     indirect->len; len_to_go > 0;) {
+			struct camdd_buf *new_buf;
+			struct camdd_buf_data *new_data;
+			uint64_t lba;
+			ssize_t len;
+
+			retval = camdd_get_next_lba_len(dev, &lba, &len);
+			if ((retval != 0)
+			 && (len == 0)) {
+				/*
+				 * The device has already been marked
+				 * as EOF, and there is no space left.
+				 */
+				goto bailout;
+			}
+
+			new_buf = camdd_get_buf(dev, CAMDD_BUF_DATA);
+			if (new_buf == NULL) {
+				retval = 1;
+				goto bailout;
+			}
+
+			new_buf->lba = lba;
+			new_buf->len = len;
+
+			idb = camdd_get_buf(dev, CAMDD_BUF_INDIRECT);
+			if (idb == NULL) {
+				retval = 1;
+				goto bailout;
+			}
+
+			indirect = &idb->buf_type_spec.indirect;
+
+			indirect->src_buf = read_buf;
+			read_buf->refcount++;
+			indirect->offset = cur_offset;
+			indirect->start_ptr = rb_data->buf + cur_offset;
+			indirect->len = min(len_to_go, new_buf->len);
+#if 0
+			if (((indirect->len % dev->sector_size) != 0)
+			 || ((indirect->offset % dev->sector_size) != 0)) {
+				warnx("offset %ju len %ju not aligned with "
+				    "sector size %u", indirect->offset,
+				    (uintmax_t)indirect->len, dev->sector_size);
+			}
+#endif
+			cur_offset += indirect->len;
+			len_to_go -= indirect->len;
+
+			camdd_buf_add_child(new_buf, idb);
+
+			new_data = &new_buf->buf_type_spec.data;
+
+			if ((new_data->fill_len == new_buf->len)
+			 || (eof_flush_needed != 0)) {
+				STAILQ_INSERT_TAIL(&dev->run_queue,
+						   new_buf, links);
+				dev->num_run_queue++;
+			} else if (new_data->fill_len < buf->len) {
+				STAILQ_INSERT_TAIL(&dev->pending_queue,
+					   	new_buf, links);
+				dev->num_pending_queue++;
+			} else {
+				warnx("%s: too much data in new "
+				      "buffer!", __func__);
+				retval = 1;
+				goto bailout;
+			}
+		}
+	}
+
+bailout:
+	return (retval);
+}
+
+void
+camdd_get_depth(struct camdd_dev *dev, uint32_t *our_depth,
+		uint32_t *peer_depth, uint32_t *our_bytes, uint32_t *peer_bytes)
+{
+	*our_depth = dev->cur_active_io + dev->num_run_queue;
+	if (dev->num_peer_work_queue >
+	    dev->num_peer_done_queue)
+		*peer_depth = dev->num_peer_work_queue -
+			      dev->num_peer_done_queue;
+	else
+		*peer_depth = 0;
+	*our_bytes = *our_depth * dev->blocksize;
+	*peer_bytes = dev->peer_bytes_queued;
+}
+
+void
+camdd_sig_handler(int sig)
+{
+	if (sig == SIGINFO)
+		need_status = 1;
+	else {
+		need_exit = 1;
+		error_exit = 1;
+	}
+
+	sem_post(&camdd_sem);
+}
+
+void
+camdd_print_status(struct camdd_dev *camdd_dev, struct camdd_dev *other_dev, 
+		   struct timespec *start_time)
+{
+	struct timespec done_time;
+	uint64_t total_ns;
+	long double mb_sec, total_sec;
+	int error = 0;
+
+	error = clock_gettime(CLOCK_MONOTONIC_PRECISE, &done_time);
+	if (error != 0) {
+		warn("Unable to get done time");
+		return;
+	}
+
+	timespecsub(&done_time, start_time);
+	
+	total_ns = done_time.tv_nsec + (done_time.tv_sec * 1000000000);
+	total_sec = total_ns;
+	total_sec /= 1000000000;
+
+	fprintf(stderr, "%ju bytes %s %s\n%ju bytes %s %s\n"
+		"%.4Lf seconds elapsed\n",
+		(uintmax_t)camdd_dev->bytes_transferred,
+		(camdd_dev->write_dev == 0) ?  "read from" : "written to",
+		camdd_dev->device_name,
+		(uintmax_t)other_dev->bytes_transferred,
+		(other_dev->write_dev == 0) ? "read from" : "written to",
+		other_dev->device_name, total_sec);
+
+	mb_sec = min(other_dev->bytes_transferred,camdd_dev->bytes_transferred);
+	mb_sec /= 1024 * 1024;
+	mb_sec *= 1000000000;
+	mb_sec /= total_ns;
+	fprintf(stderr, "%.2Lf MB/sec\n", mb_sec);
+}
+
+int
+camdd_rw(struct camdd_io_opts *io_opts, int num_io_opts, uint64_t max_io,
+	 int retry_count, int timeout)
+{
+	char *device = NULL;
+	struct cam_device *new_cam_dev = NULL;
+	struct camdd_dev *devs[2];
+	struct timespec start_time;
+	pthread_t threads[2];
+	int unit = 0;
+	int error = 0;
+	int i;
+
+	if (num_io_opts != 2) {
+		warnx("Must have one input and one output path");
+		error = 1;
+		goto bailout;
+	}
+
+	bzero(devs, sizeof(devs));
+
+	for (i = 0; i < num_io_opts; i++) {
+		switch (io_opts[i].dev_type) {
+		case CAMDD_DEV_PASS: {
+			camdd_argmask new_arglist = CAMDD_ARG_NONE;
+			int bus = 0, target = 0, lun = 0;
+			char name[30];
+			int rv;
+
+			if (isdigit(io_opts[i].dev_name[0])) {
+				/* device specified as bus:target[:lun] */
+				rv = parse_btl(io_opts[i].dev_name, &bus,
+				    &target, &lun, &new_arglist);
+				if (rv < 2) {
+					warnx("numeric device specification "
+					     "must be either bus:target, or "
+					     "bus:target:lun");
+					error = 1;
+					goto bailout;
+				}
+				/* default to 0 if lun was not specified */
+				if ((new_arglist & CAMDD_ARG_LUN) == 0) {
+					lun = 0;
+					new_arglist |= CAMDD_ARG_LUN;
+				}
+			} else {
+				if (cam_get_device(io_opts[i].dev_name, name,
+						   sizeof name, &unit) == -1) {
+					warnx("%s", cam_errbuf);
+					error = 1;
+					goto bailout;
+				}
+				device = strdup(name);
+				new_arglist |= CAMDD_ARG_DEVICE |CAMDD_ARG_UNIT;
+			}
+
+			if (new_arglist & (CAMDD_ARG_BUS | CAMDD_ARG_TARGET))
+				new_cam_dev = cam_open_btl(bus, target, lun,
+				    O_RDWR, NULL);
+			else
+				new_cam_dev = cam_open_spec_device(device, unit,
+				    O_RDWR, NULL);
+			if (new_cam_dev == NULL) {
+				warnx("%s", cam_errbuf);
+				error = 1;
+				goto bailout;
+			}
+
+			devs[i] = camdd_probe_pass(new_cam_dev,
+			    /*io_opts*/ &io_opts[i],
+			    CAMDD_ARG_ERR_RECOVER, 
+			    /*probe_retry_count*/ 3,
+			    /*probe_timeout*/ 5000,
+			    /*io_retry_count*/ retry_count,
+			    /*io_timeout*/ timeout);
+			if (devs[i] == NULL) {
+				warn("Unable to probe device %s%u",
+				     new_cam_dev->device_name,
+				     new_cam_dev->dev_unit_num);
+				error = 1;
+				goto bailout;
+			}
+			break;
+		}
+		case CAMDD_DEV_FILE: {
+			int fd = -1;
+
+			if (io_opts[i].dev_name[0] == '-') {
+				if (io_opts[i].write_dev != 0)
+					fd = STDOUT_FILENO;
+				else
+					fd = STDIN_FILENO;
+			} else {
+				if (io_opts[i].write_dev != 0) {
+					fd = open(io_opts[i].dev_name,
+					    O_RDWR | O_CREAT, S_IWUSR |S_IRUSR);
+				} else {
+					fd = open(io_opts[i].dev_name,
+					    O_RDONLY);
+				}
+			}
+			if (fd == -1) {
+				warn("error opening file %s",
+				    io_opts[i].dev_name);
+				error = 1;
+				goto bailout;
+			}
+
+			devs[i] = camdd_probe_file(fd, &io_opts[i],
+			    retry_count, timeout);
+			if (devs[i] == NULL) {
+				error = 1;
+				goto bailout;
+			}
+
+			break;
+		}
+		default:
+			warnx("Unknown device type %d (%s)",
+			    io_opts[i].dev_type, io_opts[i].dev_name);
+			error = 1;
+			goto bailout;
+			break; /*NOTREACHED */
+		}
+
+		devs[i]->write_dev = io_opts[i].write_dev;
+
+		devs[i]->start_offset_bytes = io_opts[i].offset;
+
+		if (max_io != 0) {
+			devs[i]->sector_io_limit =
+			    (devs[i]->start_offset_bytes /
+			    devs[i]->sector_size) +
+			    (max_io / devs[i]->sector_size) - 1;
+			devs[i]->sector_io_limit =
+			    (devs[i]->start_offset_bytes /
+			    devs[i]->sector_size) +
+			    (max_io / devs[i]->sector_size) - 1;
+		}
+
+		devs[i]->next_io_pos_bytes = devs[i]->start_offset_bytes;
+		devs[i]->next_completion_pos_bytes =devs[i]->start_offset_bytes;
+	}
+
+	devs[0]->peer_dev = devs[1];
+	devs[1]->peer_dev = devs[0];
+	devs[0]->next_peer_pos_bytes = devs[0]->peer_dev->next_io_pos_bytes;
+	devs[1]->next_peer_pos_bytes = devs[1]->peer_dev->next_io_pos_bytes;
+
+	sem_init(&camdd_sem, /*pshared*/ 0, 0);
+
+	signal(SIGINFO, camdd_sig_handler);
+	signal(SIGINT, camdd_sig_handler);
+
+	error = clock_gettime(CLOCK_MONOTONIC_PRECISE, &start_time);
+	if (error != 0) {
+		warn("Unable to get start time");
+		goto bailout;
+	}
+
+	for (i = 0; i < num_io_opts; i++) {
+		error = pthread_create(&threads[i], NULL, camdd_worker,
+				       (void *)devs[i]);
+		if (error != 0) {
+			warnc(error, "pthread_create() failed");
+			goto bailout;
+		}
+	}
+
+	for (;;) {
+		if ((sem_wait(&camdd_sem) == -1)
+		 || (need_exit != 0)) {
+			struct kevent ke;
+
+			for (i = 0; i < num_io_opts; i++) {
+				EV_SET(&ke, (uintptr_t)&devs[i]->work_queue,
+				    EVFILT_USER, 0, NOTE_TRIGGER, 0, NULL);
+
+				devs[i]->flags |= CAMDD_DEV_FLAG_EOF;
+
+				error = kevent(devs[i]->kq, &ke, 1, NULL, 0,
+						NULL);
+				if (error == -1)
+					warn("%s: unable to wake up thread",
+					    __func__);
+				error = 0;
+			}
+			break;
+		} else if (need_status != 0) {
+			camdd_print_status(devs[0], devs[1], &start_time);
+			need_status = 0;
+		}
+	} 
+	for (i = 0; i < num_io_opts; i++) {
+		pthread_join(threads[i], NULL);
+	}
+
+	camdd_print_status(devs[0], devs[1], &start_time);
+
+bailout:
+
+	for (i = 0; i < num_io_opts; i++)
+		camdd_free_dev(devs[i]);
+
+	return (error + error_exit);
+}
+
+void
+usage(void)
+{
+	fprintf(stderr,
+"usage:  camdd <-i|-o pass=pass0,bs=1M,offset=1M,depth=4>\n"
+"              <-i|-o file=/tmp/file,bs=512K,offset=1M>\n"
+"              <-i|-o file=/dev/da0,bs=512K,offset=1M>\n"
+"              <-i|-o file=/dev/nsa0,bs=512K>\n"
+"              [-C retry_count][-E][-m max_io_amt][-t timeout_secs][-v][-h]\n"
+"Option description\n"
+"-i <arg=val>  Specify input device/file and parameters\n"
+"-o <arg=val>  Specify output device/file and parameters\n"
+"Input and Output parameters\n"
+"pass=name     Specify a pass(4) device like pass0 or /dev/pass0\n"
+"file=name     Specify a file or device, src/usr.sbin/camdd/camdd.c, /dev/da0, /dev/null\n"
+"              or - for stdin/stdout\n"
+"bs=blocksize  Specify blocksize in bytes, or using K, M, G, etc. suffix\n"
+"offset=len    Specify starting offset in bytes or using K, M, G suffix\n"
+"              NOTE: offset cannot be specified on tapes, pipes, stdin/out\n"
+"depth=N       Specify a numeric queue depth.  This only applies to pass(4)\n"
+"mcs=N         Specify a minimum cmd size for pass(4) read/write commands\n"
+"Optional arguments\n"
+"-C retry_cnt  Specify a retry count for pass(4) devices\n"
+"-E            Enable CAM error recovery for pass(4) devices\n"
+"-m max_io     Specify the maximum amount to be transferred in bytes or\n"
+"              using K, G, M, etc. suffixes\n"
+"-t timeout    Specify the I/O timeout to use with pass(4) devices\n"
+"-v            Enable verbose error recovery\n"
+"-h            Print this message\n");
+}
+
+
+int
+camdd_parse_io_opts(char *args, int is_write, struct camdd_io_opts *io_opts)
+{
+	char *tmpstr, *tmpstr2;
+	char *orig_tmpstr = NULL;
+	int retval = 0;
+
+	io_opts->write_dev = is_write;
+
+	tmpstr = strdup(args);
+	if (tmpstr == NULL) {
+		warn("strdup failed");
+		retval = 1;
+		goto bailout;
+	}
+	orig_tmpstr = tmpstr;
+	while ((tmpstr2 = strsep(&tmpstr, ",")) != NULL) {
+		char *name, *value;
+
+		/*
+		 * If the user creates an empty parameter by putting in two
+		 * commas, skip over it and look for the next field.
+		 */
+		if (*tmpstr2 == '\0')
+			continue;
+
+		name = strsep(&tmpstr2, "=");
+		if (*name == '\0') {
+			warnx("Got empty I/O parameter name");
+			retval = 1;
+			goto bailout;
+		}
+		value = strsep(&tmpstr2, "=");
+		if ((value == NULL)
+		 || (*value == '\0')) {
+			warnx("Empty I/O parameter value for %s", name);
+			retval = 1;
+			goto bailout;
+		}
+		if (strncasecmp(name, "file", 4) == 0) {
+			io_opts->dev_type = CAMDD_DEV_FILE;
+			io_opts->dev_name = strdup(value);
+			if (io_opts->dev_name == NULL) {
+				warn("Error allocating memory");
+				retval = 1;
+				goto bailout;
+			}
+		} else if (strncasecmp(name, "pass", 4) == 0) {
+			io_opts->dev_type = CAMDD_DEV_PASS;
+			io_opts->dev_name = strdup(value);
+			if (io_opts->dev_name == NULL) {
+				warn("Error allocating memory");
+				retval = 1;
+				goto bailout;
+			}
+		} else if ((strncasecmp(name, "bs", 2) == 0)
+			|| (strncasecmp(name, "blocksize", 9) == 0)) {
+			retval = expand_number(value, &io_opts->blocksize);
+			if (retval == -1) {
+				warn("expand_number(3) failed on %s=%s", name,
+				    value);
+				retval = 1;
+				goto bailout;
+			}
+		} else if (strncasecmp(name, "depth", 5) == 0) {
+			char *endptr;
+
+			io_opts->queue_depth = strtoull(value, &endptr, 0);
+			if (*endptr != '\0') {
+				warnx("invalid queue depth %s", value);
+				retval = 1;
+				goto bailout;
+			}
+		} else if (strncasecmp(name, "mcs", 3) == 0) {
+			char *endptr;
+
+			io_opts->min_cmd_size = strtol(value, &endptr, 0);
+			if ((*endptr != '\0')
+			 || ((io_opts->min_cmd_size > 16)
+			  || (io_opts->min_cmd_size < 0))) {
+				warnx("invalid minimum cmd size %s", value);
+				retval = 1;
+				goto bailout;
+			}
+		} else if (strncasecmp(name, "offset", 6) == 0) {
+			retval = expand_number(value, &io_opts->offset);
+			if (retval == -1) {
+				warn("expand_number(3) failed on %s=%s", name,
+				    value);
+				retval = 1;
+				goto bailout;
+			}
+		} else if (strncasecmp(name, "debug", 5) == 0) {
+			char *endptr;
+
+			io_opts->debug = strtoull(value, &endptr, 0);
+			if (*endptr != '\0') {
+				warnx("invalid debug level %s", value);
+				retval = 1;
+				goto bailout;
+			}
+		} else {
+			warnx("Unrecognized parameter %s=%s", name, value);
+		}
+	}
+bailout:
+	free(orig_tmpstr);
+
+	return (retval);
+}
+
+int
+main(int argc, char **argv)
+{
+	int c;
+	camdd_argmask arglist = CAMDD_ARG_NONE;
+	int timeout = 0, retry_count = 1;
+	int error = 0;
+	uint64_t max_io = 0;
+	struct camdd_io_opts *opt_list = NULL;
+
+	if (argc == 1) {
+		usage();
+		exit(1);
+	}
+
+	opt_list = calloc(2, sizeof(struct camdd_io_opts));
+	if (opt_list == NULL) {
+		warn("Unable to allocate option list");
+		error = 1;
+		goto bailout;
+	}
+
+	while ((c = getopt(argc, argv, "C:Ehi:m:o:t:v")) != -1){
+		switch (c) {
+		case 'C':
+			retry_count = strtol(optarg, NULL, 0);
+			if (retry_count < 0)
+				errx(1, "retry count %d is < 0",
+				     retry_count);
+			arglist |= CAMDD_ARG_RETRIES;
+			break;
+		case 'E':
+			arglist |= CAMDD_ARG_ERR_RECOVER;
+			break;
+		case 'i':
+		case 'o':
+			if (((c == 'i')
+			  && (opt_list[0].dev_type != CAMDD_DEV_NONE))
+			 || ((c == 'o')
+			  && (opt_list[1].dev_type != CAMDD_DEV_NONE))) {
+				errx(1, "Only one input and output path "
+				    "allowed");
+			}
+			error = camdd_parse_io_opts(optarg, (c == 'o') ? 1 : 0,
+			    (c == 'o') ? &opt_list[1] : &opt_list[0]);
+			if (error != 0)
+				goto bailout;
+			break;
+		case 'm':
+			error = expand_number(optarg, &max_io);
+			if (error == -1) {
+				warn("invalid maximum I/O amount %s", optarg);
+				error = 1;
+				goto bailout;
+			}
+			break;
+		case 't':
+			timeout = strtol(optarg, NULL, 0);
+			if (timeout < 0)
+				errx(1, "invalid timeout %d", timeout);
+			/* Convert the timeout from seconds to ms */
+			timeout *= 1000;
+			arglist |= CAMDD_ARG_TIMEOUT;
+			break;
+		case 'v':
+			arglist |= CAMDD_ARG_VERBOSE;
+			break;
+		case 'h':
+		default:
+			usage();
+			exit(1);
+			break; /*NOTREACHED*/
+		}
+	}
+
+	if ((opt_list[0].dev_type == CAMDD_DEV_NONE)
+	 || (opt_list[1].dev_type == CAMDD_DEV_NONE))
+		errx(1, "Must specify both -i and -o");
+
+	/*
+	 * Set the timeout if the user hasn't specified one.
+	 */
+	if (timeout == 0)
+		timeout = CAMDD_PASS_RW_TIMEOUT;
+
+	error = camdd_rw(opt_list, 2, max_io, retry_count, timeout);
+
+bailout:
+	free(opt_list);
+
+	exit(error);
+}