Linux-2.6.12-rc2v2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!

1 files changed, 4937 insertions, 0 deletions

diff --git a/drivers/ide/ide-tape.c b/drivers/ide/ide-tape.c
new file mode 100644
index 00000000000..48254485498
--- /dev/null
+++ b/drivers/ide/ide-tape.c
@@ -0,0 +1,4937 @@
+/*
+ * linux/drivers/ide/ide-tape.c		Version 1.19	Nov, 2003
+ *
+ * Copyright (C) 1995 - 1999 Gadi Oxman <gadio@netvision.net.il>
+ *
+ * $Header$
+ *
+ * This driver was constructed as a student project in the software laboratory
+ * of the faculty of electrical engineering in the Technion - Israel's
+ * Institute Of Technology, with the guide of Avner Lottem and Dr. Ilana David.
+ *
+ * It is hereby placed under the terms of the GNU general public license.
+ * (See linux/COPYING).
+ */
+ 
+/*
+ * IDE ATAPI streaming tape driver.
+ *
+ * This driver is a part of the Linux ide driver and works in co-operation
+ * with linux/drivers/block/ide.c.
+ *
+ * The driver, in co-operation with ide.c, basically traverses the 
+ * request-list for the block device interface. The character device
+ * interface, on the other hand, creates new requests, adds them
+ * to the request-list of the block device, and waits for their completion.
+ *
+ * Pipelined operation mode is now supported on both reads and writes.
+ *
+ * The block device major and minor numbers are determined from the
+ * tape's relative position in the ide interfaces, as explained in ide.c.
+ *
+ * The character device interface consists of the following devices:
+ *
+ * ht0		major 37, minor 0	first  IDE tape, rewind on close.
+ * ht1		major 37, minor 1	second IDE tape, rewind on close.
+ * ...
+ * nht0		major 37, minor 128	first  IDE tape, no rewind on close.
+ * nht1		major 37, minor 129	second IDE tape, no rewind on close.
+ * ...
+ *
+ * Run linux/scripts/MAKEDEV.ide to create the above entries.
+ *
+ * The general magnetic tape commands compatible interface, as defined by
+ * include/linux/mtio.h, is accessible through the character device.
+ *
+ * General ide driver configuration options, such as the interrupt-unmask
+ * flag, can be configured by issuing an ioctl to the block device interface,
+ * as any other ide device.
+ *
+ * Our own ide-tape ioctl's can be issued to either the block device or
+ * the character device interface.
+ *
+ * Maximal throughput with minimal bus load will usually be achieved in the
+ * following scenario:
+ *
+ *	1.	ide-tape is operating in the pipelined operation mode.
+ *	2.	No buffering is performed by the user backup program.
+ *
+ * Testing was done with a 2 GB CONNER CTMA 4000 IDE ATAPI Streaming Tape Drive.
+ * 
+ * Ver 0.1   Nov  1 95   Pre-working code :-)
+ * Ver 0.2   Nov 23 95   A short backup (few megabytes) and restore procedure
+ *                        was successful ! (Using tar cvf ... on the block
+ *                        device interface).
+ *                       A longer backup resulted in major swapping, bad
+ *                        overall Linux performance and eventually failed as
+ *                        we received non serial read-ahead requests from the
+ *                        buffer cache.
+ * Ver 0.3   Nov 28 95   Long backups are now possible, thanks to the
+ *                        character device interface. Linux's responsiveness
+ *                        and performance doesn't seem to be much affected
+ *                        from the background backup procedure.
+ *                       Some general mtio.h magnetic tape operations are
+ *                        now supported by our character device. As a result,
+ *                        popular tape utilities are starting to work with
+ *                        ide tapes :-)
+ *                       The following configurations were tested:
+ *                       	1. An IDE ATAPI TAPE shares the same interface
+ *                       	   and irq with an IDE ATAPI CDROM.
+ *                        	2. An IDE ATAPI TAPE shares the same interface
+ *                          	   and irq with a normal IDE disk.
+ *                        Both configurations seemed to work just fine !
+ *                        However, to be on the safe side, it is meanwhile
+ *                        recommended to give the IDE TAPE its own interface
+ *                        and irq.
+ *                       The one thing which needs to be done here is to
+ *                        add a "request postpone" feature to ide.c,
+ *                        so that we won't have to wait for the tape to finish
+ *                        performing a long media access (DSC) request (such
+ *                        as a rewind) before we can access the other device
+ *                        on the same interface. This effect doesn't disturb
+ *                        normal operation most of the time because read/write
+ *                        requests are relatively fast, and once we are
+ *                        performing one tape r/w request, a lot of requests
+ *                        from the other device can be queued and ide.c will
+ *			  service all of them after this single tape request.
+ * Ver 1.0   Dec 11 95   Integrated into Linux 1.3.46 development tree.
+ *                       On each read / write request, we now ask the drive
+ *                        if we can transfer a constant number of bytes
+ *                        (a parameter of the drive) only to its buffers,
+ *                        without causing actual media access. If we can't,
+ *                        we just wait until we can by polling the DSC bit.
+ *                        This ensures that while we are not transferring
+ *                        more bytes than the constant referred to above, the
+ *                        interrupt latency will not become too high and
+ *                        we won't cause an interrupt timeout, as happened
+ *                        occasionally in the previous version.
+ *                       While polling for DSC, the current request is
+ *                        postponed and ide.c is free to handle requests from
+ *                        the other device. This is handled transparently to
+ *                        ide.c. The hwgroup locking method which was used
+ *                        in the previous version was removed.
+ *                       Use of new general features which are provided by
+ *                        ide.c for use with atapi devices.
+ *                        (Programming done by Mark Lord)
+ *                       Few potential bug fixes (Again, suggested by Mark)
+ *                       Single character device data transfers are now
+ *                        not limited in size, as they were before.
+ *                       We are asking the tape about its recommended
+ *                        transfer unit and send a larger data transfer
+ *                        as several transfers of the above size.
+ *                        For best results, use an integral number of this
+ *                        basic unit (which is shown during driver
+ *                        initialization). I will soon add an ioctl to get
+ *                        this important parameter.
+ *                       Our data transfer buffer is allocated on startup,
+ *                        rather than before each data transfer. This should
+ *                        ensure that we will indeed have a data buffer.
+ * Ver 1.1   Dec 14 95   Fixed random problems which occurred when the tape
+ *                        shared an interface with another device.
+ *                        (poll_for_dsc was a complete mess).
+ *                       Removed some old (non-active) code which had
+ *                        to do with supporting buffer cache originated
+ *                        requests.
+ *                       The block device interface can now be opened, so
+ *                        that general ide driver features like the unmask
+ *                        interrupts flag can be selected with an ioctl.
+ *                        This is the only use of the block device interface.
+ *                       New fast pipelined operation mode (currently only on
+ *                        writes). When using the pipelined mode, the
+ *                        throughput can potentially reach the maximum
+ *                        tape supported throughput, regardless of the
+ *                        user backup program. On my tape drive, it sometimes
+ *                        boosted performance by a factor of 2. Pipelined
+ *                        mode is enabled by default, but since it has a few
+ *                        downfalls as well, you may want to disable it.
+ *                        A short explanation of the pipelined operation mode
+ *                        is available below.
+ * Ver 1.2   Jan  1 96   Eliminated pipelined mode race condition.
+ *                       Added pipeline read mode. As a result, restores
+ *                        are now as fast as backups.
+ *                       Optimized shared interface behavior. The new behavior
+ *                        typically results in better IDE bus efficiency and
+ *                        higher tape throughput.
+ *                       Pre-calculation of the expected read/write request
+ *                        service time, based on the tape's parameters. In
+ *                        the pipelined operation mode, this allows us to
+ *                        adjust our polling frequency to a much lower value,
+ *                        and thus to dramatically reduce our load on Linux,
+ *                        without any decrease in performance.
+ *                       Implemented additional mtio.h operations.
+ *                       The recommended user block size is returned by
+ *                        the MTIOCGET ioctl.
+ *                       Additional minor changes.
+ * Ver 1.3   Feb  9 96   Fixed pipelined read mode bug which prevented the
+ *                        use of some block sizes during a restore procedure.
+ *                       The character device interface will now present a
+ *                        continuous view of the media - any mix of block sizes
+ *                        during a backup/restore procedure is supported. The
+ *                        driver will buffer the requests internally and
+ *                        convert them to the tape's recommended transfer
+ *                        unit, making performance almost independent of the
+ *                        chosen user block size.
+ *                       Some improvements in error recovery.
+ *                       By cooperating with ide-dma.c, bus mastering DMA can
+ *                        now sometimes be used with IDE tape drives as well.
+ *                        Bus mastering DMA has the potential to dramatically
+ *                        reduce the CPU's overhead when accessing the device,
+ *                        and can be enabled by using hdparm -d1 on the tape's
+ *                        block device interface. For more info, read the
+ *                        comments in ide-dma.c.
+ * Ver 1.4   Mar 13 96   Fixed serialize support.
+ * Ver 1.5   Apr 12 96   Fixed shared interface operation, broken in 1.3.85.
+ *                       Fixed pipelined read mode inefficiency.
+ *                       Fixed nasty null dereferencing bug.
+ * Ver 1.6   Aug 16 96   Fixed FPU usage in the driver.
+ *                       Fixed end of media bug.
+ * Ver 1.7   Sep 10 96   Minor changes for the CONNER CTT8000-A model.
+ * Ver 1.8   Sep 26 96   Attempt to find a better balance between good
+ *                        interactive response and high system throughput.
+ * Ver 1.9   Nov  5 96   Automatically cross encountered filemarks rather
+ *                        than requiring an explicit FSF command.
+ *                       Abort pending requests at end of media.
+ *                       MTTELL was sometimes returning incorrect results.
+ *                       Return the real block size in the MTIOCGET ioctl.
+ *                       Some error recovery bug fixes.
+ * Ver 1.10  Nov  5 96   Major reorganization.
+ *                       Reduced CPU overhead a bit by eliminating internal
+ *                        bounce buffers.
+ *                       Added module support.
+ *                       Added multiple tape drives support.
+ *                       Added partition support.
+ *                       Rewrote DSC handling.
+ *                       Some portability fixes.
+ *                       Removed ide-tape.h.
+ *                       Additional minor changes.
+ * Ver 1.11  Dec  2 96   Bug fix in previous DSC timeout handling.
+ *                       Use ide_stall_queue() for DSC overlap.
+ *                       Use the maximum speed rather than the current speed
+ *                        to compute the request service time.
+ * Ver 1.12  Dec  7 97   Fix random memory overwriting and/or last block data
+ *                        corruption, which could occur if the total number
+ *                        of bytes written to the tape was not an integral
+ *                        number of tape blocks.
+ *                       Add support for INTERRUPT DRQ devices.
+ * Ver 1.13  Jan  2 98   Add "speed == 0" work-around for HP COLORADO 5GB
+ * Ver 1.14  Dec 30 98   Partial fixes for the Sony/AIWA tape drives.
+ *                       Replace cli()/sti() with hwgroup spinlocks.
+ * Ver 1.15  Mar 25 99   Fix SMP race condition by replacing hwgroup
+ *                        spinlock with private per-tape spinlock.
+ * Ver 1.16  Sep  1 99   Add OnStream tape support.
+ *                       Abort read pipeline on EOD.
+ *                       Wait for the tape to become ready in case it returns
+ *                        "in the process of becoming ready" on open().
+ *                       Fix zero padding of the last written block in
+ *                        case the tape block size is larger than PAGE_SIZE.
+ *                       Decrease the default disconnection time to tn.
+ * Ver 1.16e Oct  3 99   Minor fixes.
+ * Ver 1.16e1 Oct 13 99  Patches by Arnold Niessen,
+ *                          niessen@iae.nl / arnold.niessen@philips.com
+ *                   GO-1)  Undefined code in idetape_read_position
+ *				according to Gadi's email
+ *                   AJN-1) Minor fix asc == 11 should be asc == 0x11
+ *                               in idetape_issue_packet_command (did effect
+ *                               debugging output only)
+ *                   AJN-2) Added more debugging output, and
+ *                              added ide-tape: where missing. I would also
+ *				like to add tape->name where possible
+ *                   AJN-3) Added different debug_level's 
+ *                              via /proc/ide/hdc/settings
+ * 				"debug_level" determines amount of debugging output;
+ * 				can be changed using /proc/ide/hdx/settings
+ * 				0 : almost no debugging output
+ * 				1 : 0+output errors only
+ * 				2 : 1+output all sensekey/asc
+ * 				3 : 2+follow all chrdev related procedures
+ * 				4 : 3+follow all procedures
+ * 				5 : 4+include pc_stack rq_stack info
+ * 				6 : 5+USE_COUNT updates
+ *                   AJN-4) Fixed timeout for retension in idetape_queue_pc_tail
+ *				from 5 to 10 minutes
+ *                   AJN-5) Changed maximum number of blocks to skip when
+ *                              reading tapes with multiple consecutive write
+ *                              errors from 100 to 1000 in idetape_get_logical_blk
+ *                   Proposed changes to code:
+ *                   1) output "logical_blk_num" via /proc
+ *                   2) output "current_operation" via /proc
+ *                   3) Either solve or document the fact that `mt rewind' is
+ *                      required after reading from /dev/nhtx to be
+ *			able to rmmod the idetape module;
+ *			Also, sometimes an application finishes but the
+ *			device remains `busy' for some time. Same cause ?
+ *                   Proposed changes to release-notes:
+ *		     4) write a simple `quickstart' section in the
+ *                      release notes; I volunteer if you don't want to
+ * 		     5) include a pointer to video4linux in the doc
+ *                      to stimulate video applications
+ *                   6) release notes lines 331 and 362: explain what happens
+ *			if the application data rate is higher than 1100 KB/s; 
+ *			similar approach to lower-than-500 kB/s ?
+ *		     7) 6.6 Comparison; wouldn't it be better to allow different 
+ *			strategies for read and write ?
+ *			Wouldn't it be better to control the tape buffer
+ *			contents instead of the bandwidth ?
+ *		     8) line 536: replace will by would (if I understand
+ *			this section correctly, a hypothetical and unwanted situation
+ *			 is being described)
+ * Ver 1.16f Dec 15 99   Change place of the secondary OnStream header frames.
+ * Ver 1.17  Nov 2000 / Jan 2001  Marcel Mol, marcel@mesa.nl
+ *			- Add idetape_onstream_mode_sense_tape_parameter_page
+ *			  function to get tape capacity in frames: tape->capacity.
+ *			- Add support for DI-50 drives( or any DI- drive).
+ *			- 'workaround' for read error/blank block around block 3000.
+ *			- Implement Early warning for end of media for Onstream.
+ *			- Cosmetic code changes for readability.
+ *			- Idetape_position_tape should not use SKIP bit during
+ *			  Onstream read recovery.
+ *			- Add capacity, logical_blk_num and first/last_frame_position
+ *			  to /proc/ide/hd?/settings.
+ *			- Module use count was gone in the Linux 2.4 driver.
+ * Ver 1.17a Apr 2001 Willem Riede osst@riede.org
+ * 			- Get drive's actual block size from mode sense block descriptor
+ * 			- Limit size of pipeline
+ * Ver 1.17b Oct 2002   Alan Stern <stern@rowland.harvard.edu>
+ *			Changed IDETAPE_MIN_PIPELINE_STAGES to 1 and actually used
+ *			 it in the code!
+ *			Actually removed aborted stages in idetape_abort_pipeline
+ *			 instead of just changing the command code.
+ *			Made the transfer byte count for Request Sense equal to the
+ *			 actual length of the data transfer.
+ *			Changed handling of partial data transfers: they do not
+ *			 cause DMA errors.
+ *			Moved initiation of DMA transfers to the correct place.
+ *			Removed reference to unallocated memory.
+ *			Made __idetape_discard_read_pipeline return the number of
+ *			 sectors skipped, not the number of stages.
+ *			Replaced errant kfree() calls with __idetape_kfree_stage().
+ *			Fixed off-by-one error in testing the pipeline length.
+ *			Fixed handling of filemarks in the read pipeline.
+ *			Small code optimization for MTBSF and MTBSFM ioctls.
+ *			Don't try to unlock the door during device close if is
+ *			 already unlocked!
+ *			Cosmetic fixes to miscellaneous debugging output messages.
+ *			Set the minimum /proc/ide/hd?/settings values for "pipeline",
+ *			 "pipeline_min", and "pipeline_max" to 1.
+ *
+ * Here are some words from the first releases of hd.c, which are quoted
+ * in ide.c and apply here as well:
+ *
+ * | Special care is recommended.  Have Fun!
+ *
+ */
+
+/*
+ * An overview of the pipelined operation mode.
+ *
+ * In the pipelined write mode, we will usually just add requests to our
+ * pipeline and return immediately, before we even start to service them. The
+ * user program will then have enough time to prepare the next request while
+ * we are still busy servicing previous requests. In the pipelined read mode,
+ * the situation is similar - we add read-ahead requests into the pipeline,
+ * before the user even requested them.
+ *
+ * The pipeline can be viewed as a "safety net" which will be activated when
+ * the system load is high and prevents the user backup program from keeping up
+ * with the current tape speed. At this point, the pipeline will get
+ * shorter and shorter but the tape will still be streaming at the same speed.
+ * Assuming we have enough pipeline stages, the system load will hopefully
+ * decrease before the pipeline is completely empty, and the backup program
+ * will be able to "catch up" and refill the pipeline again.
+ * 
+ * When using the pipelined mode, it would be best to disable any type of
+ * buffering done by the user program, as ide-tape already provides all the
+ * benefits in the kernel, where it can be done in a more efficient way.
+ * As we will usually not block the user program on a request, the most
+ * efficient user code will then be a simple read-write-read-... cycle.
+ * Any additional logic will usually just slow down the backup process.
+ *
+ * Using the pipelined mode, I get a constant over 400 KBps throughput,
+ * which seems to be the maximum throughput supported by my tape.
+ *
+ * However, there are some downfalls:
+ *
+ *	1.	We use memory (for data buffers) in proportional to the number
+ *		of pipeline stages (each stage is about 26 KB with my tape).
+ *	2.	In the pipelined write mode, we cheat and postpone error codes
+ *		to the user task. In read mode, the actual tape position
+ *		will be a bit further than the last requested block.
+ *
+ * Concerning (1):
+ *
+ *	1.	We allocate stages dynamically only when we need them. When
+ *		we don't need them, we don't consume additional memory. In
+ *		case we can't allocate stages, we just manage without them
+ *		(at the expense of decreased throughput) so when Linux is
+ *		tight in memory, we will not pose additional difficulties.
+ *
+ *	2.	The maximum number of stages (which is, in fact, the maximum
+ *		amount of memory) which we allocate is limited by the compile
+ *		time parameter IDETAPE_MAX_PIPELINE_STAGES.
+ *
+ *	3.	The maximum number of stages is a controlled parameter - We
+ *		don't start from the user defined maximum number of stages
+ *		but from the lower IDETAPE_MIN_PIPELINE_STAGES (again, we
+ *		will not even allocate this amount of stages if the user
+ *		program can't handle the speed). We then implement a feedback
+ *		loop which checks if the pipeline is empty, and if it is, we
+ *		increase the maximum number of stages as necessary until we
+ *		reach the optimum value which just manages to keep the tape
+ *		busy with minimum allocated memory or until we reach
+ *		IDETAPE_MAX_PIPELINE_STAGES.
+ *
+ * Concerning (2):
+ *
+ *	In pipelined write mode, ide-tape can not return accurate error codes
+ *	to the user program since we usually just add the request to the
+ *      pipeline without waiting for it to be serviced. In case an error
+ *      occurs, I will report it on the next user request.
+ *
+ *	In the pipelined read mode, subsequent read requests or forward
+ *	filemark spacing will perform correctly, as we preserve all blocks
+ *	and filemarks which we encountered during our excess read-ahead.
+ * 
+ *	For accurate tape positioning and error reporting, disabling
+ *	pipelined mode might be the best option.
+ *
+ * You can enable/disable/tune the pipelined operation mode by adjusting
+ * the compile time parameters below.
+ */
+
+/*
+ *	Possible improvements.
+ *
+ *	1.	Support for the ATAPI overlap protocol.
+ *
+ *		In order to maximize bus throughput, we currently use the DSC
+ *		overlap method which enables ide.c to service requests from the
+ *		other device while the tape is busy executing a command. The
+ *		DSC overlap method involves polling the tape's status register
+ *		for the DSC bit, and servicing the other device while the tape
+ *		isn't ready.
+ *
+ *		In the current QIC development standard (December 1995),
+ *		it is recommended that new tape drives will *in addition* 
+ *		implement the ATAPI overlap protocol, which is used for the
+ *		same purpose - efficient use of the IDE bus, but is interrupt
+ *		driven and thus has much less CPU overhead.
+ *
+ *		ATAPI overlap is likely to be supported in most new ATAPI
+ *		devices, including new ATAPI cdroms, and thus provides us
+ *		a method by which we can achieve higher throughput when
+ *		sharing a (fast) ATA-2 disk with any (slow) new ATAPI device.
+ */
+
+#define IDETAPE_VERSION "1.19"
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/delay.h>
+#include <linux/timer.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/major.h>
+#include <linux/devfs_fs_kernel.h>
+#include <linux/errno.h>
+#include <linux/genhd.h>
+#include <linux/slab.h>
+#include <linux/pci.h>
+#include <linux/ide.h>
+#include <linux/smp_lock.h>
+#include <linux/completion.h>
+#include <linux/bitops.h>
+
+#include <asm/byteorder.h>
+#include <asm/irq.h>
+#include <asm/uaccess.h>
+#include <asm/io.h>
+#include <asm/unaligned.h>
+
+/*
+ * partition
+ */
+typedef struct os_partition_s {
+	__u8	partition_num;
+	__u8	par_desc_ver;
+	__u16	wrt_pass_cntr;
+	__u32	first_frame_addr;
+	__u32	last_frame_addr;
+	__u32	eod_frame_addr;
+} os_partition_t;
+
+/*
+ * DAT entry
+ */
+typedef struct os_dat_entry_s {
+	__u32	blk_sz;
+	__u16	blk_cnt;
+	__u8	flags;
+	__u8	reserved;
+} os_dat_entry_t;
+
+/*
+ * DAT
+ */
+#define OS_DAT_FLAGS_DATA	(0xc)
+#define OS_DAT_FLAGS_MARK	(0x1)
+
+typedef struct os_dat_s {
+	__u8		dat_sz;
+	__u8		reserved1;
+	__u8		entry_cnt;
+	__u8		reserved3;
+	os_dat_entry_t	dat_list[16];
+} os_dat_t;
+
+#include <linux/mtio.h>
+
+/**************************** Tunable parameters *****************************/
+
+
+/*
+ *	Pipelined mode parameters.
+ *
+ *	We try to use the minimum number of stages which is enough to
+ *	keep the tape constantly streaming. To accomplish that, we implement
+ *	a feedback loop around the maximum number of stages:
+ *
+ *	We start from MIN maximum stages (we will not even use MIN stages
+ *      if we don't need them), increment it by RATE*(MAX-MIN)
+ *	whenever we sense that the pipeline is empty, until we reach
+ *	the optimum value or until we reach MAX.
+ *
+ *	Setting the following parameter to 0 is illegal: the pipelined mode
+ *	cannot be disabled (calculate_speeds() divides by tape->max_stages.)
+ */
+#define IDETAPE_MIN_PIPELINE_STAGES	  1
+#define IDETAPE_MAX_PIPELINE_STAGES	400
+#define IDETAPE_INCREASE_STAGES_RATE	 20
+
+/*
+ *	The following are used to debug the driver:
+ *
+ *	Setting IDETAPE_DEBUG_INFO to 1 will report device capabilities.
+ *	Setting IDETAPE_DEBUG_LOG to 1 will log driver flow control.
+ *	Setting IDETAPE_DEBUG_BUGS to 1 will enable self-sanity checks in
+ *	some places.
+ *
+ *	Setting them to 0 will restore normal operation mode:
+ *
+ *		1.	Disable logging normal successful operations.
+ *		2.	Disable self-sanity checks.
+ *		3.	Errors will still be logged, of course.
+ *
+ *	All the #if DEBUG code will be removed some day, when the driver
+ *	is verified to be stable enough. This will make it much more
+ *	esthetic.
+ */
+#define IDETAPE_DEBUG_INFO		0
+#define IDETAPE_DEBUG_LOG		0
+#define IDETAPE_DEBUG_BUGS		1
+
+/*
+ *	After each failed packet command we issue a request sense command
+ *	and retry the packet command IDETAPE_MAX_PC_RETRIES times.
+ *
+ *	Setting IDETAPE_MAX_PC_RETRIES to 0 will disable retries.
+ */
+#define IDETAPE_MAX_PC_RETRIES		3
+
+/*
+ *	With each packet command, we allocate a buffer of
+ *	IDETAPE_PC_BUFFER_SIZE bytes. This is used for several packet
+ *	commands (Not for READ/WRITE commands).
+ */
+#define IDETAPE_PC_BUFFER_SIZE		256
+
+/*
+ *	In various places in the driver, we need to allocate storage
+ *	for packet commands and requests, which will remain valid while
+ *	we leave the driver to wait for an interrupt or a timeout event.
+ */
+#define IDETAPE_PC_STACK		(10 + IDETAPE_MAX_PC_RETRIES)
+
+/*
+ * Some drives (for example, Seagate STT3401A Travan) require a very long
+ * timeout, because they don't return an interrupt or clear their busy bit
+ * until after the command completes (even retension commands).
+ */
+#define IDETAPE_WAIT_CMD		(900*HZ)
+
+/*
+ *	The following parameter is used to select the point in the internal
+ *	tape fifo in which we will start to refill the buffer. Decreasing
+ *	the following parameter will improve the system's latency and
+ *	interactive response, while using a high value might improve sytem
+ *	throughput.
+ */
+#define IDETAPE_FIFO_THRESHOLD 		2
+
+/*
+ *	DSC polling parameters.
+ *
+ *	Polling for DSC (a single bit in the status register) is a very
+ *	important function in ide-tape. There are two cases in which we
+ *	poll for DSC:
+ *
+ *	1.	Before a read/write packet command, to ensure that we
+ *		can transfer data from/to the tape's data buffers, without
+ *		causing an actual media access. In case the tape is not
+ *		ready yet, we take out our request from the device
+ *		request queue, so that ide.c will service requests from
+ *		the other device on the same interface meanwhile.
+ *
+ *	2.	After the successful initialization of a "media access
+ *		packet command", which is a command which can take a long
+ *		time to complete (it can be several seconds or even an hour).
+ *
+ *		Again, we postpone our request in the middle to free the bus
+ *		for the other device. The polling frequency here should be
+ *		lower than the read/write frequency since those media access
+ *		commands are slow. We start from a "fast" frequency -
+ *		IDETAPE_DSC_MA_FAST (one second), and if we don't receive DSC
+ *		after IDETAPE_DSC_MA_THRESHOLD (5 minutes), we switch it to a
+ *		lower frequency - IDETAPE_DSC_MA_SLOW (1 minute).
+ *
+ *	We also set a timeout for the timer, in case something goes wrong.
+ *	The timeout should be longer then the maximum execution time of a
+ *	tape operation.
+ */
+ 
+/*
+ *	DSC timings.
+ */
+#define IDETAPE_DSC_RW_MIN		5*HZ/100	/* 50 msec */
+#define IDETAPE_DSC_RW_MAX		40*HZ/100	/* 400 msec */
+#define IDETAPE_DSC_RW_TIMEOUT		2*60*HZ		/* 2 minutes */
+#define IDETAPE_DSC_MA_FAST		2*HZ		/* 2 seconds */
+#define IDETAPE_DSC_MA_THRESHOLD	5*60*HZ		/* 5 minutes */
+#define IDETAPE_DSC_MA_SLOW		30*HZ		/* 30 seconds */
+#define IDETAPE_DSC_MA_TIMEOUT		2*60*60*HZ	/* 2 hours */
+
+/*************************** End of tunable parameters ***********************/
+
+/*
+ *	Debugging/Performance analysis
+ *
+ *	I/O trace support
+ */
+#define USE_IOTRACE	0
+#if USE_IOTRACE
+#include <linux/io_trace.h>
+#define IO_IDETAPE_FIFO	500
+#endif
+
+/*
+ *	Read/Write error simulation
+ */
+#define SIMULATE_ERRORS			0
+
+/*
+ *	For general magnetic tape device compatibility.
+ */
+typedef enum {
+	idetape_direction_none,
+	idetape_direction_read,
+	idetape_direction_write
+} idetape_chrdev_direction_t;
+
+struct idetape_bh {
+	unsigned short b_size;
+	atomic_t b_count;
+	struct idetape_bh *b_reqnext;
+	char *b_data;
+};
+
+/*
+ *	Our view of a packet command.
+ */
+typedef struct idetape_packet_command_s {
+	u8 c[12];				/* Actual packet bytes */
+	int retries;				/* On each retry, we increment retries */
+	int error;				/* Error code */
+	int request_transfer;			/* Bytes to transfer */
+	int actually_transferred;		/* Bytes actually transferred */
+	int buffer_size;			/* Size of our data buffer */
+	struct idetape_bh *bh;
+	char *b_data;
+	int b_count;
+	u8 *buffer;				/* Data buffer */
+	u8 *current_position;			/* Pointer into the above buffer */
+	ide_startstop_t (*callback) (ide_drive_t *);	/* Called when this packet command is completed */
+	u8 pc_buffer[IDETAPE_PC_BUFFER_SIZE];	/* Temporary buffer */
+	unsigned long flags;			/* Status/Action bit flags: long for set_bit */
+} idetape_pc_t;
+
+/*
+ *	Packet command flag bits.
+ */
+/* Set when an error is considered normal - We won't retry */
+#define	PC_ABORT			0
+/* 1 When polling for DSC on a media access command */
+#define PC_WAIT_FOR_DSC			1
+/* 1 when we prefer to use DMA if possible */
+#define PC_DMA_RECOMMENDED		2
+/* 1 while DMA in progress */
+#define	PC_DMA_IN_PROGRESS		3
+/* 1 when encountered problem during DMA */
+#define	PC_DMA_ERROR			4
+/* Data direction */
+#define	PC_WRITING			5
+
+/*
+ *	Capabilities and Mechanical Status Page
+ */
+typedef struct {
+	unsigned	page_code	:6;	/* Page code - Should be 0x2a */
+	__u8		reserved0_6	:1;
+	__u8		ps		:1;	/* parameters saveable */
+	__u8		page_length;		/* Page Length - Should be 0x12 */
+	__u8		reserved2, reserved3;
+	unsigned	ro		:1;	/* Read Only Mode */
+	unsigned	reserved4_1234	:4;
+	unsigned	sprev		:1;	/* Supports SPACE in the reverse direction */
+	unsigned	reserved4_67	:2;
+	unsigned	reserved5_012	:3;
+	unsigned	efmt		:1;	/* Supports ERASE command initiated formatting */
+	unsigned	reserved5_4	:1;
+	unsigned	qfa		:1;	/* Supports the QFA two partition formats */
+	unsigned	reserved5_67	:2;
+	unsigned	lock		:1;	/* Supports locking the volume */
+	unsigned	locked		:1;	/* The volume is locked */
+	unsigned	prevent		:1;	/* The device defaults in the prevent state after power up */	
+	unsigned	eject		:1;	/* The device can eject the volume */
+	__u8		disconnect	:1;	/* The device can break request > ctl */	
+	__u8		reserved6_5	:1;
+	unsigned	ecc		:1;	/* Supports error correction */
+	unsigned	cmprs		:1;	/* Supports data compression */
+	unsigned	reserved7_0	:1;
+	unsigned	blk512		:1;	/* Supports 512 bytes block size */
+	unsigned	blk1024		:1;	/* Supports 1024 bytes block size */
+	unsigned	reserved7_3_6	:4;
+	unsigned	blk32768	:1;	/* slowb - the device restricts the byte count for PIO */
+						/* transfers for slow buffer memory ??? */
+						/* Also 32768 block size in some cases */
+	__u16		max_speed;		/* Maximum speed supported in KBps */
+	__u8		reserved10, reserved11;
+	__u16		ctl;			/* Continuous Transfer Limit in blocks */
+	__u16		speed;			/* Current Speed, in KBps */
+	__u16		buffer_size;		/* Buffer Size, in 512 bytes */
+	__u8		reserved18, reserved19;
+} idetape_capabilities_page_t;
+
+/*
+ *	Block Size Page
+ */
+typedef struct {
+	unsigned	page_code	:6;	/* Page code - Should be 0x30 */
+	unsigned	reserved1_6	:1;
+	unsigned	ps		:1;
+	__u8		page_length;		/* Page Length - Should be 2 */
+	__u8		reserved2;
+	unsigned	play32		:1;
+	unsigned	play32_5	:1;
+	unsigned	reserved2_23	:2;
+	unsigned	record32	:1;
+	unsigned	record32_5	:1;
+	unsigned	reserved2_6	:1;
+	unsigned	one		:1;
+} idetape_block_size_page_t;
+
+/*
+ *	A pipeline stage.
+ */
+typedef struct idetape_stage_s {
+	struct request rq;			/* The corresponding request */
+	struct idetape_bh *bh;			/* The data buffers */
+	struct idetape_stage_s *next;		/* Pointer to the next stage */
+} idetape_stage_t;
+
+/*
+ *	REQUEST SENSE packet command result - Data Format.
+ */
+typedef struct {
+	unsigned	error_code	:7;	/* Current of deferred errors */
+	unsigned	valid		:1;	/* The information field conforms to QIC-157C */
+	__u8		reserved1	:8;	/* Segment Number - Reserved */
+	unsigned	sense_key	:4;	/* Sense Key */
+	unsigned	reserved2_4	:1;	/* Reserved */
+	unsigned	ili		:1;	/* Incorrect Length Indicator */
+	unsigned	eom		:1;	/* End Of Medium */
+	unsigned	filemark 	:1;	/* Filemark */
+	__u32		information __attribute__ ((packed));
+	__u8		asl;			/* Additional sense length (n-7) */
+	__u32		command_specific;	/* Additional command specific information */
+	__u8		asc;			/* Additional Sense Code */
+	__u8		ascq;			/* Additional Sense Code Qualifier */
+	__u8		replaceable_unit_code;	/* Field Replaceable Unit Code */
+	unsigned	sk_specific1 	:7;	/* Sense Key Specific */
+	unsigned	sksv		:1;	/* Sense Key Specific information is valid */
+	__u8		sk_specific2;		/* Sense Key Specific */
+	__u8		sk_specific3;		/* Sense Key Specific */
+	__u8		pad[2];			/* Padding to 20 bytes */
+} idetape_request_sense_result_t;
+
+
+/*
+ *	Most of our global data which we need to save even as we leave the
+ *	driver due to an interrupt or a timer event is stored in a variable
+ *	of type idetape_tape_t, defined below.
+ */
+typedef struct ide_tape_obj {
+	ide_drive_t	*drive;
+	ide_driver_t	*driver;
+	struct gendisk	*disk;
+	struct kref	kref;
+
+	/*
+	 *	Since a typical character device operation requires more
+	 *	than one packet command, we provide here enough memory
+	 *	for the maximum of interconnected packet commands.
+	 *	The packet commands are stored in the circular array pc_stack.
+	 *	pc_stack_index points to the last used entry, and warps around
+	 *	to the start when we get to the last array entry.
+	 *
+	 *	pc points to the current processed packet command.
+	 *
+	 *	failed_pc points to the last failed packet command, or contains
+	 *	NULL if we do not need to retry any packet command. This is
+	 *	required since an additional packet command is needed before the
+	 *	retry, to get detailed information on what went wrong.
+	 */
+	/* Current packet command */
+	idetape_pc_t *pc;
+	/* Last failed packet command */
+	idetape_pc_t *failed_pc;
+	/* Packet command stack */
+	idetape_pc_t pc_stack[IDETAPE_PC_STACK];
+	/* Next free packet command storage space */
+	int pc_stack_index;
+	struct request rq_stack[IDETAPE_PC_STACK];
+	/* We implement a circular array */
+	int rq_stack_index;
+
+	/*
+	 *	DSC polling variables.
+	 *
+	 *	While polling for DSC we use postponed_rq to postpone the
+	 *	current request so that ide.c will be able to service
+	 *	pending requests on the other device. Note that at most
+	 *	we will have only one DSC (usually data transfer) request
+	 *	in the device request queue. Additional requests can be
+	 *	queued in our internal pipeline, but they will be visible
+	 *	to ide.c only one at a time.
+	 */
+	struct request *postponed_rq;
+	/* The time in which we started polling for DSC */
+	unsigned long dsc_polling_start;
+	/* Timer used to poll for dsc */
+	struct timer_list dsc_timer;
+	/* Read/Write dsc polling frequency */
+	unsigned long best_dsc_rw_frequency;
+	/* The current polling frequency */
+	unsigned long dsc_polling_frequency;
+	/* Maximum waiting time */
+	unsigned long dsc_timeout;
+
+	/*
+	 *	Read position information
+	 */
+	u8 partition;
+	/* Current block */
+	unsigned int first_frame_position;
+	unsigned int last_frame_position;
+	unsigned int blocks_in_buffer;
+
+	/*
+	 *	Last error information
+	 */
+	u8 sense_key, asc, ascq;
+
+	/*
+	 *	Character device operation
+	 */
+	unsigned int minor;
+	/* device name */
+	char name[4];
+	/* Current character device data transfer direction */
+	idetape_chrdev_direction_t chrdev_direction;
+
+	/*
+	 *	Device information
+	 */
+	/* Usually 512 or 1024 bytes */
+	unsigned short tape_block_size;
+	int user_bs_factor;
+	/* Copy of the tape's Capabilities and Mechanical Page */
+	idetape_capabilities_page_t capabilities;
+
+	/*
+	 *	Active data transfer request parameters.
+	 *
+	 *	At most, there is only one ide-tape originated data transfer
+	 *	request in the device request queue. This allows ide.c to
+	 *	easily service requests from the other device when we
+	 *	postpone our active request. In the pipelined operation
+	 *	mode, we use our internal pipeline structure to hold
+	 *	more data requests.
+	 *
+	 *	The data buffer size is chosen based on the tape's
+	 *	recommendation.
+	 */
+	/* Pointer to the request which is waiting in the device request queue */
+	struct request *active_data_request;
+	/* Data buffer size (chosen based on the tape's recommendation */
+	int stage_size;
+	idetape_stage_t *merge_stage;
+	int merge_stage_size;
+	struct idetape_bh *bh;
+	char *b_data;
+	int b_count;
+	
+	/*
+	 *	Pipeline parameters.
+	 *
+	 *	To accomplish non-pipelined mode, we simply set the following
+	 *	variables to zero (or NULL, where appropriate).
+	 */
+	/* Number of currently used stages */
+	int nr_stages;
+	/* Number of pending stages */
+	int nr_pending_stages;
+	/* We will not allocate more than this number of stages */
+	int max_stages, min_pipeline, max_pipeline;
+	/* The first stage which will be removed from the pipeline */
+	idetape_stage_t *first_stage;
+	/* The currently active stage */
+	idetape_stage_t *active_stage;
+	/* Will be serviced after the currently active request */
+	idetape_stage_t *next_stage;
+	/* New requests will be added to the pipeline here */
+	idetape_stage_t *last_stage;
+	/* Optional free stage which we can use */
+	idetape_stage_t *cache_stage;
+	int pages_per_stage;
+	/* Wasted space in each stage */
+	int excess_bh_size;
+
+	/* Status/Action flags: long for set_bit */
+	unsigned long flags;
+	/* protects the ide-tape queue */
+	spinlock_t spinlock;
+
+	/*
+	 * Measures average tape speed
+	 */
+	unsigned long avg_time;
+	int avg_size;
+	int avg_speed;
+
+	/* last sense information */
+	idetape_request_sense_result_t sense;
+
+	char vendor_id[10];
+	char product_id[18];
+	char firmware_revision[6];
+	int firmware_revision_num;
+
+	/* the door is currently locked */
+	int door_locked;
+	/* the tape hardware is write protected */
+	char drv_write_prot;
+	/* the tape is write protected (hardware or opened as read-only) */
+	char write_prot;
+
+	/*
+	 * Limit the number of times a request can
+	 * be postponed, to avoid an infinite postpone
+	 * deadlock.
+	 */
+	/* request postpone count limit */
+	int postpone_cnt;
+
+	/*
+	 * Measures number of frames:
+	 *
+	 * 1. written/read to/from the driver pipeline (pipeline_head).
+	 * 2. written/read to/from the tape buffers (idetape_bh).
+	 * 3. written/read by the tape to/from the media (tape_head).
+	 */
+	int pipeline_head;
+	int buffer_head;
+	int tape_head;
+	int last_tape_head;
+
+	/*
+	 * Speed control at the tape buffers input/output
+	 */
+	unsigned long insert_time;
+	int insert_size;
+	int insert_speed;
+	int max_insert_speed;
+	int measure_insert_time;
+
+	/*
+	 * Measure tape still time, in milliseconds
+	 */
+	unsigned long tape_still_time_begin;
+	int tape_still_time;
+
+	/*
+	 * Speed regulation negative feedback loop
+	 */
+	int speed_control;
+	int pipeline_head_speed;
+	int controlled_pipeline_head_speed;
+	int uncontrolled_pipeline_head_speed;
+	int controlled_last_pipeline_head;
+	int uncontrolled_last_pipeline_head;
+	unsigned long uncontrolled_pipeline_head_time;
+	unsigned long controlled_pipeline_head_time;
+	int controlled_previous_pipeline_head;
+	int uncontrolled_previous_pipeline_head;
+	unsigned long controlled_previous_head_time;
+	unsigned long uncontrolled_previous_head_time;
+	int restart_speed_control_req;
+
+        /*
+         * Debug_level determines amount of debugging output;
+         * can be changed using /proc/ide/hdx/settings
+         * 0 : almost no debugging output
+         * 1 : 0+output errors only
+         * 2 : 1+output all sensekey/asc
+         * 3 : 2+follow all chrdev related procedures
+         * 4 : 3+follow all procedures
+         * 5 : 4+include pc_stack rq_stack info
+         * 6 : 5+USE_COUNT updates
+         */
+         int debug_level; 
+} idetape_tape_t;
+
+static DECLARE_MUTEX(idetape_ref_sem);
+
+#define to_ide_tape(obj) container_of(obj, struct ide_tape_obj, kref)
+
+#define ide_tape_g(disk) \
+	container_of((disk)->private_data, struct ide_tape_obj, driver)
+
+static struct ide_tape_obj *ide_tape_get(struct gendisk *disk)
+{
+	struct ide_tape_obj *tape = NULL;
+
+	down(&idetape_ref_sem);
+	tape = ide_tape_g(disk);
+	if (tape)
+		kref_get(&tape->kref);
+	up(&idetape_ref_sem);
+	return tape;
+}
+
+static void ide_tape_release(struct kref *);
+
+static void ide_tape_put(struct ide_tape_obj *tape)
+{
+	down(&idetape_ref_sem);
+	kref_put(&tape->kref, ide_tape_release);
+	up(&idetape_ref_sem);
+}
+
+/*
+ *	Tape door status
+ */
+#define DOOR_UNLOCKED			0
+#define DOOR_LOCKED			1
+#define DOOR_EXPLICITLY_LOCKED		2
+
+/*
+ *	Tape flag bits values.
+ */
+#define IDETAPE_IGNORE_DSC		0
+#define IDETAPE_ADDRESS_VALID		1	/* 0 When the tape position is unknown */
+#define IDETAPE_BUSY			2	/* Device already opened */
+#define IDETAPE_PIPELINE_ERROR		3	/* Error detected in a pipeline stage */
+#define IDETAPE_DETECT_BS		4	/* Attempt to auto-detect the current user block size */
+#define IDETAPE_FILEMARK		5	/* Currently on a filemark */
+#define IDETAPE_DRQ_INTERRUPT		6	/* DRQ interrupt device */
+#define IDETAPE_READ_ERROR		7
+#define IDETAPE_PIPELINE_ACTIVE		8	/* pipeline active */
+/* 0 = no tape is loaded, so we don't rewind after ejecting */
+#define IDETAPE_MEDIUM_PRESENT		9
+
+/*
+ *	Supported ATAPI tape drives packet commands
+ */
+#define IDETAPE_TEST_UNIT_READY_CMD	0x00
+#define IDETAPE_REWIND_CMD		0x01
+#define IDETAPE_REQUEST_SENSE_CMD	0x03
+#define IDETAPE_READ_CMD		0x08
+#define IDETAPE_WRITE_CMD		0x0a
+#define IDETAPE_WRITE_FILEMARK_CMD	0x10
+#define IDETAPE_SPACE_CMD		0x11
+#define IDETAPE_INQUIRY_CMD		0x12
+#define IDETAPE_ERASE_CMD		0x19
+#define IDETAPE_MODE_SENSE_CMD		0x1a
+#define IDETAPE_MODE_SELECT_CMD		0x15
+#define IDETAPE_LOAD_UNLOAD_CMD		0x1b
+#define IDETAPE_PREVENT_CMD		0x1e
+#define IDETAPE_LOCATE_CMD		0x2b
+#define IDETAPE_READ_POSITION_CMD	0x34
+#define IDETAPE_READ_BUFFER_CMD		0x3c
+#define IDETAPE_SET_SPEED_CMD		0xbb
+
+/*
+ *	Some defines for the READ BUFFER command
+ */
+#define IDETAPE_RETRIEVE_FAULTY_BLOCK	6
+
+/*
+ *	Some defines for the SPACE command
+ */
+#define IDETAPE_SPACE_OVER_FILEMARK	1
+#define IDETAPE_SPACE_TO_EOD		3
+
+/*
+ *	Some defines for the LOAD UNLOAD command
+ */
+#define IDETAPE_LU_LOAD_MASK		1
+#define IDETAPE_LU_RETENSION_MASK	2
+#define IDETAPE_LU_EOT_MASK		4
+
+/*
+ *	Special requests for our block device strategy routine.
+ *
+ *	In order to service a character device command, we add special
+ *	requests to the tail of our block device request queue and wait
+ *	for their completion.
+ */
+
+enum {
+	REQ_IDETAPE_PC1		= (1 << 0), /* packet command (first stage) */
+	REQ_IDETAPE_PC2		= (1 << 1), /* packet command (second stage) */
+	REQ_IDETAPE_READ	= (1 << 2),
+	REQ_IDETAPE_WRITE	= (1 << 3),
+	REQ_IDETAPE_READ_BUFFER	= (1 << 4),
+};
+
+/*
+ *	Error codes which are returned in rq->errors to the higher part
+ *	of the driver.
+ */
+#define	IDETAPE_ERROR_GENERAL		101
+#define	IDETAPE_ERROR_FILEMARK		102
+#define	IDETAPE_ERROR_EOD		103
+
+/*
+ *	The following is used to format the general configuration word of
+ *	the ATAPI IDENTIFY DEVICE command.
+ */
+struct idetape_id_gcw {	
+	unsigned packet_size		:2;	/* Packet Size */
+	unsigned reserved234		:3;	/* Reserved */
+	unsigned drq_type		:2;	/* Command packet DRQ type */
+	unsigned removable		:1;	/* Removable media */
+	unsigned device_type		:5;	/* Device type */
+	unsigned reserved13		:1;	/* Reserved */
+	unsigned protocol		:2;	/* Protocol type */
+};
+
+/*
+ *	INQUIRY packet command - Data Format (From Table 6-8 of QIC-157C)
+ */
+typedef struct {
+	unsigned	device_type	:5;	/* Peripheral Device Type */
+	unsigned	reserved0_765	:3;	/* Peripheral Qualifier - Reserved */
+	unsigned	reserved1_6t0	:7;	/* Reserved */
+	unsigned	rmb		:1;	/* Removable Medium Bit */
+	unsigned	ansi_version	:3;	/* ANSI Version */
+	unsigned	ecma_version	:3;	/* ECMA Version */
+	unsigned	iso_version	:2;	/* ISO Version */
+	unsigned	response_format :4;	/* Response Data Format */
+	unsigned	reserved3_45	:2;	/* Reserved */
+	unsigned	reserved3_6	:1;	/* TrmIOP - Reserved */
+	unsigned	reserved3_7	:1;	/* AENC - Reserved */
+	__u8		additional_length;	/* Additional Length (total_length-4) */
+	__u8		rsv5, rsv6, rsv7;	/* Reserved */
+	__u8		vendor_id[8];		/* Vendor Identification */
+	__u8		product_id[16];		/* Product Identification */
+	__u8		revision_level[4];	/* Revision Level */
+	__u8		vendor_specific[20];	/* Vendor Specific - Optional */
+	__u8		reserved56t95[40];	/* Reserved - Optional */
+						/* Additional information may be returned */
+} idetape_inquiry_result_t;
+
+/*
+ *	READ POSITION packet command - Data Format (From Table 6-57)
+ */
+typedef struct {
+	unsigned	reserved0_10	:2;	/* Reserved */
+	unsigned	bpu		:1;	/* Block Position Unknown */	
+	unsigned	reserved0_543	:3;	/* Reserved */
+	unsigned	eop		:1;	/* End Of Partition */
+	unsigned	bop		:1;	/* Beginning Of Partition */
+	u8		partition;		/* Partition Number */
+	u8		reserved2, reserved3;	/* Reserved */
+	u32		first_block;		/* First Block Location */
+	u32		last_block;		/* Last Block Location (Optional) */
+	u8		reserved12;		/* Reserved */
+	u8		blocks_in_buffer[3];	/* Blocks In Buffer - (Optional) */
+	u32		bytes_in_buffer;	/* Bytes In Buffer (Optional) */
+} idetape_read_position_result_t;
+
+/*
+ *	Follows structures which are related to the SELECT SENSE / MODE SENSE
+ *	packet commands. Those packet commands are still not supported
+ *	by ide-tape.
+ */
+#define IDETAPE_BLOCK_DESCRIPTOR	0
+#define	IDETAPE_CAPABILITIES_PAGE	0x2a
+#define IDETAPE_PARAMTR_PAGE		0x2b   /* Onstream DI-x0 only */
+#define IDETAPE_BLOCK_SIZE_PAGE		0x30
+#define IDETAPE_BUFFER_FILLING_PAGE	0x33
+
+/*
+ *	Mode Parameter Header for the MODE SENSE packet command
+ */
+typedef struct {
+	__u8	mode_data_length;	/* Length of the following data transfer */
+	__u8	medium_type;		/* Medium Type */
+	__u8	dsp;			/* Device Specific Parameter */
+	__u8	bdl;			/* Block Descriptor Length */
+#if 0
+	/* data transfer page */
+	__u8	page_code	:6;
+	__u8	reserved0_6	:1;
+	__u8	ps		:1;	/* parameters saveable */
+	__u8	page_length;		/* page Length == 0x02 */
+	__u8	reserved2;
+	__u8	read32k		:1;	/* 32k blk size (data only) */
+	__u8	read32k5	:1;	/* 32.5k blk size (data&AUX) */
+	__u8	reserved3_23	:2;
+	__u8	write32k	:1;	/* 32k blk size (data only) */
+	__u8	write32k5	:1;	/* 32.5k blk size (data&AUX) */
+	__u8	reserved3_6	:1;
+	__u8	streaming	:1;	/* streaming mode enable */
+#endif
+} idetape_mode_parameter_header_t;
+
+/*
+ *	Mode Parameter Block Descriptor the MODE SENSE packet command
+ *
+ *	Support for block descriptors is optional.
+ */
+typedef struct {
+	__u8		density_code;		/* Medium density code */
+	__u8		blocks[3];		/* Number of blocks */
+	__u8		reserved4;		/* Reserved */
+	__u8		length[3];		/* Block Length */
+} idetape_parameter_block_descriptor_t;
+
+/*
+ *	The Data Compression Page, as returned by the MODE SENSE packet command.
+ */
+typedef struct {
+	unsigned	page_code	:6;	/* Page Code - Should be 0xf */
+	unsigned	reserved0	:1;	/* Reserved */
+	unsigned	ps		:1;
+	__u8		page_length;		/* Page Length - Should be 14 */
+	unsigned	reserved2	:6;	/* Reserved */
+	unsigned	dcc		:1;	/* Data Compression Capable */
+	unsigned	dce		:1;	/* Data Compression Enable */
+	unsigned	reserved3	:5;	/* Reserved */
+	unsigned	red		:2;	/* Report Exception on Decompression */
+	unsigned	dde		:1;	/* Data Decompression Enable */
+	__u32		ca;			/* Compression Algorithm */
+	__u32		da;			/* Decompression Algorithm */
+	__u8		reserved[4];		/* Reserved */
+} idetape_data_compression_page_t;
+
+/*
+ *	The Medium Partition Page, as returned by the MODE SENSE packet command.
+ */
+typedef struct {
+	unsigned	page_code	:6;	/* Page Code - Should be 0x11 */
+	unsigned	reserved1_6	:1;	/* Reserved */
+	unsigned	ps		:1;
+	__u8		page_length;		/* Page Length - Should be 6 */
+	__u8		map;			/* Maximum Additional Partitions - Should be 0 */
+	__u8		apd;			/* Additional Partitions Defined - Should be 0 */
+	unsigned	reserved4_012	:3;	/* Reserved */
+	unsigned	psum		:2;	/* Should be 0 */
+	unsigned	idp		:1;	/* Should be 0 */
+	unsigned	sdp		:1;	/* Should be 0 */
+	unsigned	fdp		:1;	/* Fixed Data Partitions */
+	__u8		mfr;			/* Medium Format Recognition */
+	__u8		reserved[2];		/* Reserved */
+} idetape_medium_partition_page_t;
+
+/*
+ *	Run time configurable parameters.
+ */
+typedef struct {
+	int	dsc_rw_frequency;
+	int	dsc_media_access_frequency;
+	int	nr_stages;
+} idetape_config_t;
+
+/*
+ *	The variables below are used for the character device interface.
+ *	Additional state variables are defined in our ide_drive_t structure.
+ */
+static struct ide_tape_obj * idetape_devs[MAX_HWIFS * MAX_DRIVES];
+
+#define ide_tape_f(file) ((file)->private_data)
+
+static struct ide_tape_obj *ide_tape_chrdev_get(unsigned int i)
+{
+	struct ide_tape_obj *tape = NULL;
+
+	down(&idetape_ref_sem);
+	tape = idetape_devs[i];
+	if (tape)
+		kref_get(&tape->kref);
+	up(&idetape_ref_sem);
+	return tape;
+}
+
+/*
+ *      Function declarations
+ *
+ */
+static int idetape_chrdev_release (struct inode *inode, struct file *filp);
+static void idetape_write_release (ide_drive_t *drive, unsigned int minor);
+
+/*
+ * Too bad. The drive wants to send us data which we are not ready to accept.
+ * Just throw it away.
+ */
+static void idetape_discard_data (ide_drive_t *drive, unsigned int bcount)
+{
+	while (bcount--)
+		(void) HWIF(drive)->INB(IDE_DATA_REG);
+}
+
+static void idetape_input_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
+{
+	struct idetape_bh *bh = pc->bh;
+	int count;
+
+	while (bcount) {
+#if IDETAPE_DEBUG_BUGS
+		if (bh == NULL) {
+			printk(KERN_ERR "ide-tape: bh == NULL in "
+				"idetape_input_buffers\n");
+			idetape_discard_data(drive, bcount);
+			return;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		count = min((unsigned int)(bh->b_size - atomic_read(&bh->b_count)), bcount);
+		HWIF(drive)->atapi_input_bytes(drive, bh->b_data + atomic_read(&bh->b_count), count);
+		bcount -= count;
+		atomic_add(count, &bh->b_count);
+		if (atomic_read(&bh->b_count) == bh->b_size) {
+			bh = bh->b_reqnext;
+			if (bh)
+				atomic_set(&bh->b_count, 0);
+		}
+	}
+	pc->bh = bh;
+}
+
+static void idetape_output_buffers (ide_drive_t *drive, idetape_pc_t *pc, unsigned int bcount)
+{
+	struct idetape_bh *bh = pc->bh;
+	int count;
+
+	while (bcount) {
+#if IDETAPE_DEBUG_BUGS
+		if (bh == NULL) {
+			printk(KERN_ERR "ide-tape: bh == NULL in "
+				"idetape_output_buffers\n");
+			return;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		count = min((unsigned int)pc->b_count, (unsigned int)bcount);
+		HWIF(drive)->atapi_output_bytes(drive, pc->b_data, count);
+		bcount -= count;
+		pc->b_data += count;
+		pc->b_count -= count;
+		if (!pc->b_count) {
+			pc->bh = bh = bh->b_reqnext;
+			if (bh) {
+				pc->b_data = bh->b_data;
+				pc->b_count = atomic_read(&bh->b_count);
+			}
+		}
+	}
+}
+
+static void idetape_update_buffers (idetape_pc_t *pc)
+{
+	struct idetape_bh *bh = pc->bh;
+	int count;
+	unsigned int bcount = pc->actually_transferred;
+
+	if (test_bit(PC_WRITING, &pc->flags))
+		return;
+	while (bcount) {
+#if IDETAPE_DEBUG_BUGS
+		if (bh == NULL) {
+			printk(KERN_ERR "ide-tape: bh == NULL in "
+				"idetape_update_buffers\n");
+			return;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		count = min((unsigned int)bh->b_size, (unsigned int)bcount);
+		atomic_set(&bh->b_count, count);
+		if (atomic_read(&bh->b_count) == bh->b_size)
+			bh = bh->b_reqnext;
+		bcount -= count;
+	}
+	pc->bh = bh;
+}
+
+/*
+ *	idetape_next_pc_storage returns a pointer to a place in which we can
+ *	safely store a packet command, even though we intend to leave the
+ *	driver. A storage space for a maximum of IDETAPE_PC_STACK packet
+ *	commands is allocated at initialization time.
+ */
+static idetape_pc_t *idetape_next_pc_storage (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 5)
+		printk(KERN_INFO "ide-tape: pc_stack_index=%d\n",
+			tape->pc_stack_index);
+#endif /* IDETAPE_DEBUG_LOG */
+	if (tape->pc_stack_index == IDETAPE_PC_STACK)
+		tape->pc_stack_index=0;
+	return (&tape->pc_stack[tape->pc_stack_index++]);
+}
+
+/*
+ *	idetape_next_rq_storage is used along with idetape_next_pc_storage.
+ *	Since we queue packet commands in the request queue, we need to
+ *	allocate a request, along with the allocation of a packet command.
+ */
+ 
+/**************************************************************
+ *                                                            *
+ *  This should get fixed to use kmalloc(.., GFP_ATOMIC)      *
+ *  followed later on by kfree().   -ml                       *
+ *                                                            *
+ **************************************************************/
+ 
+static struct request *idetape_next_rq_storage (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 5)
+		printk(KERN_INFO "ide-tape: rq_stack_index=%d\n",
+			tape->rq_stack_index);
+#endif /* IDETAPE_DEBUG_LOG */
+	if (tape->rq_stack_index == IDETAPE_PC_STACK)
+		tape->rq_stack_index=0;
+	return (&tape->rq_stack[tape->rq_stack_index++]);
+}
+
+/*
+ *	idetape_init_pc initializes a packet command.
+ */
+static void idetape_init_pc (idetape_pc_t *pc)
+{
+	memset(pc->c, 0, 12);
+	pc->retries = 0;
+	pc->flags = 0;
+	pc->request_transfer = 0;
+	pc->buffer = pc->pc_buffer;
+	pc->buffer_size = IDETAPE_PC_BUFFER_SIZE;
+	pc->bh = NULL;
+	pc->b_data = NULL;
+}
+
+/*
+ *	idetape_analyze_error is called on each failed packet command retry
+ *	to analyze the request sense. We currently do not utilize this
+ *	information.
+ */
+static void idetape_analyze_error (ide_drive_t *drive, idetape_request_sense_result_t *result)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t *pc = tape->failed_pc;
+
+	tape->sense     = *result;
+	tape->sense_key = result->sense_key;
+	tape->asc       = result->asc;
+	tape->ascq      = result->ascq;
+#if IDETAPE_DEBUG_LOG
+	/*
+	 *	Without debugging, we only log an error if we decided to
+	 *	give up retrying.
+	 */
+	if (tape->debug_level >= 1)
+		printk(KERN_INFO "ide-tape: pc = %x, sense key = %x, "
+			"asc = %x, ascq = %x\n",
+			pc->c[0], result->sense_key,
+			result->asc, result->ascq);
+#endif /* IDETAPE_DEBUG_LOG */
+
+	/*
+	 *	Correct pc->actually_transferred by asking the tape.
+	 */
+	if (test_bit(PC_DMA_ERROR, &pc->flags)) {
+		pc->actually_transferred = pc->request_transfer - tape->tape_block_size * ntohl(get_unaligned(&result->information));
+		idetape_update_buffers(pc);
+	}
+
+	/*
+	 * If error was the result of a zero-length read or write command,
+	 * with sense key=5, asc=0x22, ascq=0, let it slide.  Some drives
+	 * (i.e. Seagate STT3401A Travan) don't support 0-length read/writes.
+	 */
+	if ((pc->c[0] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD)
+	    && pc->c[4] == 0 && pc->c[3] == 0 && pc->c[2] == 0) { /* length==0 */
+		if (result->sense_key == 5) {
+			/* don't report an error, everything's ok */
+			pc->error = 0;
+			/* don't retry read/write */
+			set_bit(PC_ABORT, &pc->flags);
+		}
+	}
+	if (pc->c[0] == IDETAPE_READ_CMD && result->filemark) {
+		pc->error = IDETAPE_ERROR_FILEMARK;
+		set_bit(PC_ABORT, &pc->flags);
+	}
+	if (pc->c[0] == IDETAPE_WRITE_CMD) {
+		if (result->eom ||
+		    (result->sense_key == 0xd && result->asc == 0x0 &&
+		     result->ascq == 0x2)) {
+			pc->error = IDETAPE_ERROR_EOD;
+			set_bit(PC_ABORT, &pc->flags);
+		}
+	}
+	if (pc->c[0] == IDETAPE_READ_CMD || pc->c[0] == IDETAPE_WRITE_CMD) {
+		if (result->sense_key == 8) {
+			pc->error = IDETAPE_ERROR_EOD;
+			set_bit(PC_ABORT, &pc->flags);
+		}
+		if (!test_bit(PC_ABORT, &pc->flags) &&
+		    pc->actually_transferred)
+			pc->retries = IDETAPE_MAX_PC_RETRIES + 1;
+	}
+}
+
+/*
+ * idetape_active_next_stage will declare the next stage as "active".
+ */
+static void idetape_active_next_stage (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_stage_t *stage = tape->next_stage;
+	struct request *rq = &stage->rq;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_active_next_stage\n");
+#endif /* IDETAPE_DEBUG_LOG */
+#if IDETAPE_DEBUG_BUGS
+	if (stage == NULL) {
+		printk(KERN_ERR "ide-tape: bug: Trying to activate a non existing stage\n");
+		return;
+	}
+#endif /* IDETAPE_DEBUG_BUGS */	
+
+	rq->rq_disk = tape->disk;
+	rq->buffer = NULL;
+	rq->special = (void *)stage->bh;
+	tape->active_data_request = rq;
+	tape->active_stage = stage;
+	tape->next_stage = stage->next;
+}
+
+/*
+ *	idetape_increase_max_pipeline_stages is a part of the feedback
+ *	loop which tries to find the optimum number of stages. In the
+ *	feedback loop, we are starting from a minimum maximum number of
+ *	stages, and if we sense that the pipeline is empty, we try to
+ *	increase it, until we reach the user compile time memory limit.
+ */
+static void idetape_increase_max_pipeline_stages (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	int increase = (tape->max_pipeline - tape->min_pipeline) / 10;
+	
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk (KERN_INFO "ide-tape: Reached idetape_increase_max_pipeline_stages\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	tape->max_stages += max(increase, 1);
+	tape->max_stages = max(tape->max_stages, tape->min_pipeline);
+	tape->max_stages = min(tape->max_stages, tape->max_pipeline);
+}
+
+/*
+ *	idetape_kfree_stage calls kfree to completely free a stage, along with
+ *	its related buffers.
+ */
+static void __idetape_kfree_stage (idetape_stage_t *stage)
+{
+	struct idetape_bh *prev_bh, *bh = stage->bh;
+	int size;
+
+	while (bh != NULL) {
+		if (bh->b_data != NULL) {
+			size = (int) bh->b_size;
+			while (size > 0) {
+				free_page((unsigned long) bh->b_data);
+				size -= PAGE_SIZE;
+				bh->b_data += PAGE_SIZE;
+			}
+		}
+		prev_bh = bh;
+		bh = bh->b_reqnext;
+		kfree(prev_bh);
+	}
+	kfree(stage);
+}
+
+static void idetape_kfree_stage (idetape_tape_t *tape, idetape_stage_t *stage)
+{
+	__idetape_kfree_stage(stage);
+}
+
+/*
+ *	idetape_remove_stage_head removes tape->first_stage from the pipeline.
+ *	The caller should avoid race conditions.
+ */
+static void idetape_remove_stage_head (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_stage_t *stage;
+	
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_remove_stage_head\n");
+#endif /* IDETAPE_DEBUG_LOG */
+#if IDETAPE_DEBUG_BUGS
+	if (tape->first_stage == NULL) {
+		printk(KERN_ERR "ide-tape: bug: tape->first_stage is NULL\n");
+		return;		
+	}
+	if (tape->active_stage == tape->first_stage) {
+		printk(KERN_ERR "ide-tape: bug: Trying to free our active pipeline stage\n");
+		return;
+	}
+#endif /* IDETAPE_DEBUG_BUGS */
+	stage = tape->first_stage;
+	tape->first_stage = stage->next;
+	idetape_kfree_stage(tape, stage);
+	tape->nr_stages--;
+	if (tape->first_stage == NULL) {
+		tape->last_stage = NULL;
+#if IDETAPE_DEBUG_BUGS
+		if (tape->next_stage != NULL)
+			printk(KERN_ERR "ide-tape: bug: tape->next_stage != NULL\n");
+		if (tape->nr_stages)
+			printk(KERN_ERR "ide-tape: bug: nr_stages should be 0 now\n");
+#endif /* IDETAPE_DEBUG_BUGS */
+	}
+}
+
+/*
+ * This will free all the pipeline stages starting from new_last_stage->next
+ * to the end of the list, and point tape->last_stage to new_last_stage.
+ */
+static void idetape_abort_pipeline(ide_drive_t *drive,
+				   idetape_stage_t *new_last_stage)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_stage_t *stage = new_last_stage->next;
+	idetape_stage_t *nstage;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: %s: idetape_abort_pipeline called\n", tape->name);
+#endif
+	while (stage) {
+		nstage = stage->next;
+		idetape_kfree_stage(tape, stage);
+		--tape->nr_stages;
+		--tape->nr_pending_stages;
+		stage = nstage;
+	}
+	if (new_last_stage)
+		new_last_stage->next = NULL;
+	tape->last_stage = new_last_stage;
+	tape->next_stage = NULL;
+}
+
+/*
+ *	idetape_end_request is used to finish servicing a request, and to
+ *	insert a pending pipeline request into the main device queue.
+ */
+static int idetape_end_request(ide_drive_t *drive, int uptodate, int nr_sects)
+{
+	struct request *rq = HWGROUP(drive)->rq;
+	idetape_tape_t *tape = drive->driver_data;
+	unsigned long flags;
+	int error;
+	int remove_stage = 0;
+	idetape_stage_t *active_stage;
+
+#if IDETAPE_DEBUG_LOG
+        if (tape->debug_level >= 4)
+	printk(KERN_INFO "ide-tape: Reached idetape_end_request\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	switch (uptodate) {
+		case 0:	error = IDETAPE_ERROR_GENERAL; break;
+		case 1: error = 0; break;
+		default: error = uptodate;
+	}
+	rq->errors = error;
+	if (error)
+		tape->failed_pc = NULL;
+
+	spin_lock_irqsave(&tape->spinlock, flags);
+
+	/* The request was a pipelined data transfer request */
+	if (tape->active_data_request == rq) {
+		active_stage = tape->active_stage;
+		tape->active_stage = NULL;
+		tape->active_data_request = NULL;
+		tape->nr_pending_stages--;
+		if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
+			remove_stage = 1;
+			if (error) {
+				set_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
+				if (error == IDETAPE_ERROR_EOD)
+					idetape_abort_pipeline(drive, active_stage);
+			}
+		} else if (rq->cmd[0] & REQ_IDETAPE_READ) {
+			if (error == IDETAPE_ERROR_EOD) {
+				set_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
+				idetape_abort_pipeline(drive, active_stage);
+			}
+		}
+		if (tape->next_stage != NULL) {
+			idetape_active_next_stage(drive);
+
+			/*
+			 * Insert the next request into the request queue.
+			 */
+			(void) ide_do_drive_cmd(drive, tape->active_data_request, ide_end);
+		} else if (!error) {
+				idetape_increase_max_pipeline_stages(drive);
+		}
+	}
+	ide_end_drive_cmd(drive, 0, 0);
+//	blkdev_dequeue_request(rq);
+//	drive->rq = NULL;
+//	end_that_request_last(rq);
+
+	if (remove_stage)
+		idetape_remove_stage_head(drive);
+	if (tape->active_data_request == NULL)
+		clear_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
+	spin_unlock_irqrestore(&tape->spinlock, flags);
+	return 0;
+}
+
+static ide_startstop_t idetape_request_sense_callback (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_request_sense_callback\n");
+#endif /* IDETAPE_DEBUG_LOG */
+	if (!tape->pc->error) {
+		idetape_analyze_error(drive, (idetape_request_sense_result_t *) tape->pc->buffer);
+		idetape_end_request(drive, 1, 0);
+	} else {
+		printk(KERN_ERR "ide-tape: Error in REQUEST SENSE itself - Aborting request!\n");
+		idetape_end_request(drive, 0, 0);
+	}
+	return ide_stopped;
+}
+
+static void idetape_create_request_sense_cmd (idetape_pc_t *pc)
+{
+	idetape_init_pc(pc);	
+	pc->c[0] = IDETAPE_REQUEST_SENSE_CMD;
+	pc->c[4] = 20;
+	pc->request_transfer = 20;
+	pc->callback = &idetape_request_sense_callback;
+}
+
+static void idetape_init_rq(struct request *rq, u8 cmd)
+{
+	memset(rq, 0, sizeof(*rq));
+	rq->flags = REQ_SPECIAL;
+	rq->cmd[0] = cmd;
+}
+
+/*
+ *	idetape_queue_pc_head generates a new packet command request in front
+ *	of the request queue, before the current request, so that it will be
+ *	processed immediately, on the next pass through the driver.
+ *
+ *	idetape_queue_pc_head is called from the request handling part of
+ *	the driver (the "bottom" part). Safe storage for the request should
+ *	be allocated with idetape_next_pc_storage and idetape_next_rq_storage
+ *	before calling idetape_queue_pc_head.
+ *
+ *	Memory for those requests is pre-allocated at initialization time, and
+ *	is limited to IDETAPE_PC_STACK requests. We assume that we have enough
+ *	space for the maximum possible number of inter-dependent packet commands.
+ *
+ *	The higher level of the driver - The ioctl handler and the character
+ *	device handling functions should queue request to the lower level part
+ *	and wait for their completion using idetape_queue_pc_tail or
+ *	idetape_queue_rw_tail.
+ */
+static void idetape_queue_pc_head (ide_drive_t *drive, idetape_pc_t *pc,struct request *rq)
+{
+	struct ide_tape_obj *tape = drive->driver_data;
+
+	idetape_init_rq(rq, REQ_IDETAPE_PC1);
+	rq->buffer = (char *) pc;
+	rq->rq_disk = tape->disk;
+	(void) ide_do_drive_cmd(drive, rq, ide_preempt);
+}
+
+/*
+ *	idetape_retry_pc is called when an error was detected during the
+ *	last packet command. We queue a request sense packet command in
+ *	the head of the request list.
+ */
+static ide_startstop_t idetape_retry_pc (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t *pc;
+	struct request *rq;
+	atapi_error_t error;
+
+	error.all = HWIF(drive)->INB(IDE_ERROR_REG);
+	pc = idetape_next_pc_storage(drive);
+	rq = idetape_next_rq_storage(drive);
+	idetape_create_request_sense_cmd(pc);
+	set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
+	idetape_queue_pc_head(drive, pc, rq);
+	return ide_stopped;
+}
+
+/*
+ *	idetape_postpone_request postpones the current request so that
+ *	ide.c will be able to service requests from another device on
+ *	the same hwgroup while we are polling for DSC.
+ */
+static void idetape_postpone_request (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: idetape_postpone_request\n");
+#endif
+	tape->postponed_rq = HWGROUP(drive)->rq;
+	ide_stall_queue(drive, tape->dsc_polling_frequency);
+}
+
+/*
+ *	idetape_pc_intr is the usual interrupt handler which will be called
+ *	during a packet command. We will transfer some of the data (as
+ *	requested by the drive) and will re-point interrupt handler to us.
+ *	When data transfer is finished, we will act according to the
+ *	algorithm described before idetape_issue_packet_command.
+ *
+ */
+static ide_startstop_t idetape_pc_intr (ide_drive_t *drive)
+{
+	ide_hwif_t *hwif = drive->hwif;
+	idetape_tape_t *tape = drive->driver_data;
+	atapi_status_t status;
+	atapi_bcount_t bcount;
+	atapi_ireason_t ireason;
+	idetape_pc_t *pc = tape->pc;
+
+	unsigned int temp;
+#if SIMULATE_ERRORS
+	static int error_sim_count = 0;
+#endif
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_pc_intr "
+				"interrupt handler\n");
+#endif /* IDETAPE_DEBUG_LOG */	
+
+	/* Clear the interrupt */
+	status.all = HWIF(drive)->INB(IDE_STATUS_REG);
+
+	if (test_bit(PC_DMA_IN_PROGRESS, &pc->flags)) {
+		if (HWIF(drive)->ide_dma_end(drive) || status.b.check) {
+			/*
+			 * A DMA error is sometimes expected. For example,
+			 * if the tape is crossing a filemark during a
+			 * READ command, it will issue an irq and position
+			 * itself before the filemark, so that only a partial
+			 * data transfer will occur (which causes the DMA
+			 * error). In that case, we will later ask the tape
+			 * how much bytes of the original request were
+			 * actually transferred (we can't receive that
+			 * information from the DMA engine on most chipsets).
+			 */
+
+			/*
+			 * On the contrary, a DMA error is never expected;
+			 * it usually indicates a hardware error or abort.
+			 * If the tape crosses a filemark during a READ
+			 * command, it will issue an irq and position itself
+			 * after the filemark (not before). Only a partial
+			 * data transfer will occur, but no DMA error.
+			 * (AS, 19 Apr 2001)
+			 */
+			set_bit(PC_DMA_ERROR, &pc->flags);
+		} else {
+			pc->actually_transferred = pc->request_transfer;
+			idetape_update_buffers(pc);
+		}
+#if IDETAPE_DEBUG_LOG
+		if (tape->debug_level >= 4)
+			printk(KERN_INFO "ide-tape: DMA finished\n");
+#endif /* IDETAPE_DEBUG_LOG */
+	}
+
+	/* No more interrupts */
+	if (!status.b.drq) {
+#if IDETAPE_DEBUG_LOG
+		if (tape->debug_level >= 2)
+			printk(KERN_INFO "ide-tape: Packet command completed, %d bytes transferred\n", pc->actually_transferred);
+#endif /* IDETAPE_DEBUG_LOG */
+		clear_bit(PC_DMA_IN_PROGRESS, &pc->flags);
+
+		local_irq_enable();
+
+#if SIMULATE_ERRORS
+		if ((pc->c[0] == IDETAPE_WRITE_CMD ||
+		     pc->c[0] == IDETAPE_READ_CMD) &&
+		    (++error_sim_count % 100) == 0) {
+			printk(KERN_INFO "ide-tape: %s: simulating error\n",
+				tape->name);
+			status.b.check = 1;
+		}
+#endif
+		if (status.b.check && pc->c[0] == IDETAPE_REQUEST_SENSE_CMD)
+			status.b.check = 0;
+		if (status.b.check || test_bit(PC_DMA_ERROR, &pc->flags)) {	/* Error detected */
+#if IDETAPE_DEBUG_LOG
+			if (tape->debug_level >= 1)
+				printk(KERN_INFO "ide-tape: %s: I/O error\n",
+					tape->name);
+#endif /* IDETAPE_DEBUG_LOG */
+			if (pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
+				printk(KERN_ERR "ide-tape: I/O error in request sense command\n");
+				return ide_do_reset(drive);
+			}
+#if IDETAPE_DEBUG_LOG
+			if (tape->debug_level >= 1)
+				printk(KERN_INFO "ide-tape: [cmd %x]: check condition\n", pc->c[0]);
+#endif
+			/* Retry operation */
+			return idetape_retry_pc(drive);
+		}
+		pc->error = 0;
+		if (test_bit(PC_WAIT_FOR_DSC, &pc->flags) &&
+		    !status.b.dsc) {
+			/* Media access command */
+			tape->dsc_polling_start = jiffies;
+			tape->dsc_polling_frequency = IDETAPE_DSC_MA_FAST;
+			tape->dsc_timeout = jiffies + IDETAPE_DSC_MA_TIMEOUT;
+			/* Allow ide.c to handle other requests */
+			idetape_postpone_request(drive);
+			return ide_stopped;
+		}
+		if (tape->failed_pc == pc)
+			tape->failed_pc = NULL;
+		/* Command finished - Call the callback function */
+		return pc->callback(drive);
+	}
+	if (test_and_clear_bit(PC_DMA_IN_PROGRESS, &pc->flags)) {
+		printk(KERN_ERR "ide-tape: The tape wants to issue more "
+				"interrupts in DMA mode\n");
+		printk(KERN_ERR "ide-tape: DMA disabled, reverting to PIO\n");
+		(void)__ide_dma_off(drive);
+		return ide_do_reset(drive);
+	}
+	/* Get the number of bytes to transfer on this interrupt. */
+	bcount.b.high = hwif->INB(IDE_BCOUNTH_REG);
+	bcount.b.low = hwif->INB(IDE_BCOUNTL_REG);
+
+	ireason.all = hwif->INB(IDE_IREASON_REG);
+
+	if (ireason.b.cod) {
+		printk(KERN_ERR "ide-tape: CoD != 0 in idetape_pc_intr\n");
+		return ide_do_reset(drive);
+	}
+	if (ireason.b.io == test_bit(PC_WRITING, &pc->flags)) {
+		/* Hopefully, we will never get here */
+		printk(KERN_ERR "ide-tape: We wanted to %s, ",
+			ireason.b.io ? "Write":"Read");
+		printk(KERN_ERR "ide-tape: but the tape wants us to %s !\n",
+			ireason.b.io ? "Read":"Write");
+		return ide_do_reset(drive);
+	}
+	if (!test_bit(PC_WRITING, &pc->flags)) {
+		/* Reading - Check that we have enough space */
+		temp = pc->actually_transferred + bcount.all;
+		if (temp > pc->request_transfer) {
+			if (temp > pc->buffer_size) {
+				printk(KERN_ERR "ide-tape: The tape wants to send us more data than expected - discarding data\n");
+				idetape_discard_data(drive, bcount.all);
+				ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
+				return ide_started;
+			}
+#if IDETAPE_DEBUG_LOG
+			if (tape->debug_level >= 2)
+				printk(KERN_NOTICE "ide-tape: The tape wants to send us more data than expected - allowing transfer\n");
+#endif /* IDETAPE_DEBUG_LOG */
+		}
+	}
+	if (test_bit(PC_WRITING, &pc->flags)) {
+		if (pc->bh != NULL)
+			idetape_output_buffers(drive, pc, bcount.all);
+		else
+			/* Write the current buffer */
+			HWIF(drive)->atapi_output_bytes(drive, pc->current_position, bcount.all);
+	} else {
+		if (pc->bh != NULL)
+			idetape_input_buffers(drive, pc, bcount.all);
+		else
+			/* Read the current buffer */
+			HWIF(drive)->atapi_input_bytes(drive, pc->current_position, bcount.all);
+	}
+	/* Update the current position */
+	pc->actually_transferred += bcount.all;
+	pc->current_position += bcount.all;
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 2)
+		printk(KERN_INFO "ide-tape: [cmd %x] transferred %d bytes on that interrupt\n", pc->c[0], bcount.all);
+#endif
+	/* And set the interrupt handler again */
+	ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
+	return ide_started;
+}
+
+/*
+ *	Packet Command Interface
+ *
+ *	The current Packet Command is available in tape->pc, and will not
+ *	change until we finish handling it. Each packet command is associated
+ *	with a callback function that will be called when the command is
+ *	finished.
+ *
+ *	The handling will be done in three stages:
+ *
+ *	1.	idetape_issue_packet_command will send the packet command to the
+ *		drive, and will set the interrupt handler to idetape_pc_intr.
+ *
+ *	2.	On each interrupt, idetape_pc_intr will be called. This step
+ *		will be repeated until the device signals us that no more
+ *		interrupts will be issued.
+ *
+ *	3.	ATAPI Tape media access commands have immediate status with a
+ *		delayed process. In case of a successful initiation of a
+ *		media access packet command, the DSC bit will be set when the
+ *		actual execution of the command is finished. 
+ *		Since the tape drive will not issue an interrupt, we have to
+ *		poll for this event. In this case, we define the request as
+ *		"low priority request" by setting rq_status to
+ *		IDETAPE_RQ_POSTPONED, 	set a timer to poll for DSC and exit
+ *		the driver.
+ *
+ *		ide.c will then give higher priority to requests which
+ *		originate from the other device, until will change rq_status
+ *		to RQ_ACTIVE.
+ *
+ *	4.	When the packet command is finished, it will be checked for errors.
+ *
+ *	5.	In case an error was found, we queue a request sense packet
+ *		command in front of the request queue and retry the operation
+ *		up to IDETAPE_MAX_PC_RETRIES times.
+ *
+ *	6.	In case no error was found, or we decided to give up and not
+ *		to retry again, the callback function will be called and then
+ *		we will handle the next request.
+ *
+ */
+static ide_startstop_t idetape_transfer_pc(ide_drive_t *drive)
+{
+	ide_hwif_t *hwif = drive->hwif;
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t *pc = tape->pc;
+	atapi_ireason_t ireason;
+	int retries = 100;
+	ide_startstop_t startstop;
+
+	if (ide_wait_stat(&startstop,drive,DRQ_STAT,BUSY_STAT,WAIT_READY)) {
+		printk(KERN_ERR "ide-tape: Strange, packet command initiated yet DRQ isn't asserted\n");
+		return startstop;
+	}
+	ireason.all = hwif->INB(IDE_IREASON_REG);
+	while (retries-- && (!ireason.b.cod || ireason.b.io)) {
+		printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while issuing "
+				"a packet command, retrying\n");
+		udelay(100);
+		ireason.all = hwif->INB(IDE_IREASON_REG);
+		if (retries == 0) {
+			printk(KERN_ERR "ide-tape: (IO,CoD != (0,1) while "
+					"issuing a packet command, ignoring\n");
+			ireason.b.cod = 1;
+			ireason.b.io = 0;
+		}
+	}
+	if (!ireason.b.cod || ireason.b.io) {
+		printk(KERN_ERR "ide-tape: (IO,CoD) != (0,1) while issuing "
+				"a packet command\n");
+		return ide_do_reset(drive);
+	}
+	/* Set the interrupt routine */
+	ide_set_handler(drive, &idetape_pc_intr, IDETAPE_WAIT_CMD, NULL);
+#ifdef CONFIG_BLK_DEV_IDEDMA
+	/* Begin DMA, if necessary */
+	if (test_bit(PC_DMA_IN_PROGRESS, &pc->flags))
+		hwif->dma_start(drive);
+#endif
+	/* Send the actual packet */
+	HWIF(drive)->atapi_output_bytes(drive, pc->c, 12);
+	return ide_started;
+}
+
+static ide_startstop_t idetape_issue_packet_command (ide_drive_t *drive, idetape_pc_t *pc)
+{
+	ide_hwif_t *hwif = drive->hwif;
+	idetape_tape_t *tape = drive->driver_data;
+	atapi_bcount_t bcount;
+	int dma_ok = 0;
+
+#if IDETAPE_DEBUG_BUGS
+	if (tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD &&
+	    pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
+		printk(KERN_ERR "ide-tape: possible ide-tape.c bug - "
+			"Two request sense in serial were issued\n");
+	}
+#endif /* IDETAPE_DEBUG_BUGS */
+
+	if (tape->failed_pc == NULL && pc->c[0] != IDETAPE_REQUEST_SENSE_CMD)
+		tape->failed_pc = pc;
+	/* Set the current packet command */
+	tape->pc = pc;
+
+	if (pc->retries > IDETAPE_MAX_PC_RETRIES ||
+	    test_bit(PC_ABORT, &pc->flags)) {
+		/*
+		 *	We will "abort" retrying a packet command in case
+		 *	a legitimate error code was received (crossing a
+		 *	filemark, or end of the media, for example).
+		 */
+		if (!test_bit(PC_ABORT, &pc->flags)) {
+			if (!(pc->c[0] == IDETAPE_TEST_UNIT_READY_CMD &&
+			      tape->sense_key == 2 && tape->asc == 4 &&
+			     (tape->ascq == 1 || tape->ascq == 8))) {
+				printk(KERN_ERR "ide-tape: %s: I/O error, "
+						"pc = %2x, key = %2x, "
+						"asc = %2x, ascq = %2x\n",
+						tape->name, pc->c[0],
+						tape->sense_key, tape->asc,
+						tape->ascq);
+			}
+			/* Giving up */
+			pc->error = IDETAPE_ERROR_GENERAL;
+		}
+		tape->failed_pc = NULL;
+		return pc->callback(drive);
+	}
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 2)
+		printk(KERN_INFO "ide-tape: Retry number - %d, cmd = %02X\n", pc->retries, pc->c[0]);
+#endif /* IDETAPE_DEBUG_LOG */
+
+	pc->retries++;
+	/* We haven't transferred any data yet */
+	pc->actually_transferred = 0;
+	pc->current_position = pc->buffer;
+	/* Request to transfer the entire buffer at once */
+	bcount.all = pc->request_transfer;
+
+	if (test_and_clear_bit(PC_DMA_ERROR, &pc->flags)) {
+		printk(KERN_WARNING "ide-tape: DMA disabled, "
+				"reverting to PIO\n");
+		(void)__ide_dma_off(drive);
+	}
+	if (test_bit(PC_DMA_RECOMMENDED, &pc->flags) && drive->using_dma)
+		dma_ok = !hwif->dma_setup(drive);
+
+	if (IDE_CONTROL_REG)
+		hwif->OUTB(drive->ctl, IDE_CONTROL_REG);
+	hwif->OUTB(dma_ok ? 1 : 0, IDE_FEATURE_REG);	/* Use PIO/DMA */
+	hwif->OUTB(bcount.b.high, IDE_BCOUNTH_REG);
+	hwif->OUTB(bcount.b.low, IDE_BCOUNTL_REG);
+	hwif->OUTB(drive->select.all, IDE_SELECT_REG);
+	if (dma_ok)			/* Will begin DMA later */
+		set_bit(PC_DMA_IN_PROGRESS, &pc->flags);
+	if (test_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags)) {
+		ide_set_handler(drive, &idetape_transfer_pc, IDETAPE_WAIT_CMD, NULL);
+		hwif->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
+		return ide_started;
+	} else {
+		hwif->OUTB(WIN_PACKETCMD, IDE_COMMAND_REG);
+		return idetape_transfer_pc(drive);
+	}
+}
+
+/*
+ *	General packet command callback function.
+ */
+static ide_startstop_t idetape_pc_callback (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_pc_callback\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	idetape_end_request(drive, tape->pc->error ? 0 : 1, 0);
+	return ide_stopped;
+}
+
+/*
+ *	A mode sense command is used to "sense" tape parameters.
+ */
+static void idetape_create_mode_sense_cmd (idetape_pc_t *pc, u8 page_code)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_MODE_SENSE_CMD;
+	if (page_code != IDETAPE_BLOCK_DESCRIPTOR)
+		pc->c[1] = 8;	/* DBD = 1 - Don't return block descriptors */
+	pc->c[2] = page_code;
+	/*
+	 * Changed pc->c[3] to 0 (255 will at best return unused info).
+	 *
+	 * For SCSI this byte is defined as subpage instead of high byte
+	 * of length and some IDE drives seem to interpret it this way
+	 * and return an error when 255 is used.
+	 */
+	pc->c[3] = 0;
+	pc->c[4] = 255;		/* (We will just discard data in that case) */
+	if (page_code == IDETAPE_BLOCK_DESCRIPTOR)
+		pc->request_transfer = 12;
+	else if (page_code == IDETAPE_CAPABILITIES_PAGE)
+		pc->request_transfer = 24;
+	else
+		pc->request_transfer = 50;
+	pc->callback = &idetape_pc_callback;
+}
+
+static void calculate_speeds(ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	int full = 125, empty = 75;
+
+	if (time_after(jiffies, tape->controlled_pipeline_head_time + 120 * HZ)) {
+		tape->controlled_previous_pipeline_head = tape->controlled_last_pipeline_head;
+		tape->controlled_previous_head_time = tape->controlled_pipeline_head_time;
+		tape->controlled_last_pipeline_head = tape->pipeline_head;
+		tape->controlled_pipeline_head_time = jiffies;
+	}
+	if (time_after(jiffies, tape->controlled_pipeline_head_time + 60 * HZ))
+		tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_last_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_pipeline_head_time);
+	else if (time_after(jiffies, tape->controlled_previous_head_time))
+		tape->controlled_pipeline_head_speed = (tape->pipeline_head - tape->controlled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->controlled_previous_head_time);
+
+	if (tape->nr_pending_stages < tape->max_stages /*- 1 */) {
+		/* -1 for read mode error recovery */
+		if (time_after(jiffies, tape->uncontrolled_previous_head_time + 10 * HZ)) {
+			tape->uncontrolled_pipeline_head_time = jiffies;
+			tape->uncontrolled_pipeline_head_speed = (tape->pipeline_head - tape->uncontrolled_previous_pipeline_head) * 32 * HZ / (jiffies - tape->uncontrolled_previous_head_time);
+		}
+	} else {
+		tape->uncontrolled_previous_head_time = jiffies;
+		tape->uncontrolled_previous_pipeline_head = tape->pipeline_head;
+		if (time_after(jiffies, tape->uncontrolled_pipeline_head_time + 30 * HZ)) {
+			tape->uncontrolled_pipeline_head_time = jiffies;
+		}
+	}
+	tape->pipeline_head_speed = max(tape->uncontrolled_pipeline_head_speed, tape->controlled_pipeline_head_speed);
+	if (tape->speed_control == 0) {
+		tape->max_insert_speed = 5000;
+	} else if (tape->speed_control == 1) {
+		if (tape->nr_pending_stages >= tape->max_stages / 2)
+			tape->max_insert_speed = tape->pipeline_head_speed +
+				(1100 - tape->pipeline_head_speed) * 2 * (tape->nr_pending_stages - tape->max_stages / 2) / tape->max_stages;
+		else
+			tape->max_insert_speed = 500 +
+				(tape->pipeline_head_speed - 500) * 2 * tape->nr_pending_stages / tape->max_stages;
+		if (tape->nr_pending_stages >= tape->max_stages * 99 / 100)
+			tape->max_insert_speed = 5000;
+	} else if (tape->speed_control == 2) {
+		tape->max_insert_speed = tape->pipeline_head_speed * empty / 100 +
+			(tape->pipeline_head_speed * full / 100 - tape->pipeline_head_speed * empty / 100) * tape->nr_pending_stages / tape->max_stages;
+	} else
+		tape->max_insert_speed = tape->speed_control;
+	tape->max_insert_speed = max(tape->max_insert_speed, 500);
+}
+
+static ide_startstop_t idetape_media_access_finished (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t *pc = tape->pc;
+	atapi_status_t status;
+
+	status.all = HWIF(drive)->INB(IDE_STATUS_REG);
+	if (status.b.dsc) {
+		if (status.b.check) {
+			/* Error detected */
+			if (pc->c[0] != IDETAPE_TEST_UNIT_READY_CMD)
+				printk(KERN_ERR "ide-tape: %s: I/O error, ",
+						tape->name);
+			/* Retry operation */
+			return idetape_retry_pc(drive);
+		}
+		pc->error = 0;
+		if (tape->failed_pc == pc)
+			tape->failed_pc = NULL;
+	} else {
+		pc->error = IDETAPE_ERROR_GENERAL;
+		tape->failed_pc = NULL;
+	}
+	return pc->callback(drive);
+}
+
+static ide_startstop_t idetape_rw_callback (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct request *rq = HWGROUP(drive)->rq;
+	int blocks = tape->pc->actually_transferred / tape->tape_block_size;
+
+	tape->avg_size += blocks * tape->tape_block_size;
+	tape->insert_size += blocks * tape->tape_block_size;
+	if (tape->insert_size > 1024 * 1024)
+		tape->measure_insert_time = 1;
+	if (tape->measure_insert_time) {
+		tape->measure_insert_time = 0;
+		tape->insert_time = jiffies;
+		tape->insert_size = 0;
+	}
+	if (time_after(jiffies, tape->insert_time))
+		tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
+	if (jiffies - tape->avg_time >= HZ) {
+		tape->avg_speed = tape->avg_size * HZ / (jiffies - tape->avg_time) / 1024;
+		tape->avg_size = 0;
+		tape->avg_time = jiffies;
+	}
+
+#if IDETAPE_DEBUG_LOG	
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_rw_callback\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	tape->first_frame_position += blocks;
+	rq->current_nr_sectors -= blocks;
+
+	if (!tape->pc->error)
+		idetape_end_request(drive, 1, 0);
+	else
+		idetape_end_request(drive, tape->pc->error, 0);
+	return ide_stopped;
+}
+
+static void idetape_create_read_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_READ_CMD;
+	put_unaligned(htonl(length), (unsigned int *) &pc->c[1]);
+	pc->c[1] = 1;
+	pc->callback = &idetape_rw_callback;
+	pc->bh = bh;
+	atomic_set(&bh->b_count, 0);
+	pc->buffer = NULL;
+	pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
+	if (pc->request_transfer == tape->stage_size)
+		set_bit(PC_DMA_RECOMMENDED, &pc->flags);
+}
+
+static void idetape_create_read_buffer_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
+{
+	int size = 32768;
+	struct idetape_bh *p = bh;
+
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_READ_BUFFER_CMD;
+	pc->c[1] = IDETAPE_RETRIEVE_FAULTY_BLOCK;
+	pc->c[7] = size >> 8;
+	pc->c[8] = size & 0xff;
+	pc->callback = &idetape_pc_callback;
+	pc->bh = bh;
+	atomic_set(&bh->b_count, 0);
+	pc->buffer = NULL;
+	while (p) {
+		atomic_set(&p->b_count, 0);
+		p = p->b_reqnext;
+	}
+	pc->request_transfer = pc->buffer_size = size;
+}
+
+static void idetape_create_write_cmd(idetape_tape_t *tape, idetape_pc_t *pc, unsigned int length, struct idetape_bh *bh)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_WRITE_CMD;
+	put_unaligned(htonl(length), (unsigned int *) &pc->c[1]);
+	pc->c[1] = 1;
+	pc->callback = &idetape_rw_callback;
+	set_bit(PC_WRITING, &pc->flags);
+	pc->bh = bh;
+	pc->b_data = bh->b_data;
+	pc->b_count = atomic_read(&bh->b_count);
+	pc->buffer = NULL;
+	pc->request_transfer = pc->buffer_size = length * tape->tape_block_size;
+	if (pc->request_transfer == tape->stage_size)
+		set_bit(PC_DMA_RECOMMENDED, &pc->flags);
+}
+
+/*
+ * idetape_do_request is our request handling function.	
+ */
+static ide_startstop_t idetape_do_request(ide_drive_t *drive,
+					  struct request *rq, sector_t block)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t *pc = NULL;
+	struct request *postponed_rq = tape->postponed_rq;
+	atapi_status_t status;
+
+#if IDETAPE_DEBUG_LOG
+#if 0
+	if (tape->debug_level >= 5)
+		printk(KERN_INFO "ide-tape: rq_status: %d, "
+			"dev: %s, cmd: %ld, errors: %d\n", rq->rq_status,
+			 rq->rq_disk->disk_name, rq->cmd[0], rq->errors);
+#endif
+	if (tape->debug_level >= 2)
+		printk(KERN_INFO "ide-tape: sector: %ld, "
+			"nr_sectors: %ld, current_nr_sectors: %d\n",
+			rq->sector, rq->nr_sectors, rq->current_nr_sectors);
+#endif /* IDETAPE_DEBUG_LOG */
+
+	if ((rq->flags & REQ_SPECIAL) == 0) {
+		/*
+		 * We do not support buffer cache originated requests.
+		 */
+		printk(KERN_NOTICE "ide-tape: %s: Unsupported request in "
+			"request queue (%ld)\n", drive->name, rq->flags);
+		ide_end_request(drive, 0, 0);
+		return ide_stopped;
+	}
+
+	/*
+	 *	Retry a failed packet command
+	 */
+	if (tape->failed_pc != NULL &&
+	    tape->pc->c[0] == IDETAPE_REQUEST_SENSE_CMD) {
+		return idetape_issue_packet_command(drive, tape->failed_pc);
+	}
+#if IDETAPE_DEBUG_BUGS
+	if (postponed_rq != NULL)
+		if (rq != postponed_rq) {
+			printk(KERN_ERR "ide-tape: ide-tape.c bug - "
+					"Two DSC requests were queued\n");
+			idetape_end_request(drive, 0, 0);
+			return ide_stopped;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+
+	tape->postponed_rq = NULL;
+
+	/*
+	 * If the tape is still busy, postpone our request and service
+	 * the other device meanwhile.
+	 */
+	status.all = HWIF(drive)->INB(IDE_STATUS_REG);
+
+	if (!drive->dsc_overlap && !(rq->cmd[0] & REQ_IDETAPE_PC2))
+		set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
+
+	if (drive->post_reset == 1) {
+		set_bit(IDETAPE_IGNORE_DSC, &tape->flags);
+		drive->post_reset = 0;
+	}
+
+	if (tape->tape_still_time > 100 && tape->tape_still_time < 200)
+		tape->measure_insert_time = 1;
+	if (time_after(jiffies, tape->insert_time))
+		tape->insert_speed = tape->insert_size / 1024 * HZ / (jiffies - tape->insert_time);
+	calculate_speeds(drive);
+	if (!test_and_clear_bit(IDETAPE_IGNORE_DSC, &tape->flags) &&
+	    !status.b.dsc) {
+		if (postponed_rq == NULL) {
+			tape->dsc_polling_start = jiffies;
+			tape->dsc_polling_frequency = tape->best_dsc_rw_frequency;
+			tape->dsc_timeout = jiffies + IDETAPE_DSC_RW_TIMEOUT;
+		} else if (time_after(jiffies, tape->dsc_timeout)) {
+			printk(KERN_ERR "ide-tape: %s: DSC timeout\n",
+				tape->name);
+			if (rq->cmd[0] & REQ_IDETAPE_PC2) {
+				idetape_media_access_finished(drive);
+				return ide_stopped;
+			} else {
+				return ide_do_reset(drive);
+			}
+		} else if (jiffies - tape->dsc_polling_start > IDETAPE_DSC_MA_THRESHOLD)
+			tape->dsc_polling_frequency = IDETAPE_DSC_MA_SLOW;
+		idetape_postpone_request(drive);
+		return ide_stopped;
+	}
+	if (rq->cmd[0] & REQ_IDETAPE_READ) {
+		tape->buffer_head++;
+#if USE_IOTRACE
+		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
+#endif
+		tape->postpone_cnt = 0;
+		pc = idetape_next_pc_storage(drive);
+		idetape_create_read_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
+		goto out;
+	}
+	if (rq->cmd[0] & REQ_IDETAPE_WRITE) {
+		tape->buffer_head++;
+#if USE_IOTRACE
+		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
+#endif
+		tape->postpone_cnt = 0;
+		pc = idetape_next_pc_storage(drive);
+		idetape_create_write_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
+		goto out;
+	}
+	if (rq->cmd[0] & REQ_IDETAPE_READ_BUFFER) {
+		tape->postpone_cnt = 0;
+		pc = idetape_next_pc_storage(drive);
+		idetape_create_read_buffer_cmd(tape, pc, rq->current_nr_sectors, (struct idetape_bh *)rq->special);
+		goto out;
+	}
+	if (rq->cmd[0] & REQ_IDETAPE_PC1) {
+		pc = (idetape_pc_t *) rq->buffer;
+		rq->cmd[0] &= ~(REQ_IDETAPE_PC1);
+		rq->cmd[0] |= REQ_IDETAPE_PC2;
+		goto out;
+	}
+	if (rq->cmd[0] & REQ_IDETAPE_PC2) {
+		idetape_media_access_finished(drive);
+		return ide_stopped;
+	}
+	BUG();
+out:
+	return idetape_issue_packet_command(drive, pc);
+}
+
+/*
+ *	Pipeline related functions
+ */
+static inline int idetape_pipeline_active (idetape_tape_t *tape)
+{
+	int rc1, rc2;
+
+	rc1 = test_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
+	rc2 = (tape->active_data_request != NULL);
+	return rc1;
+}
+
+/*
+ *	idetape_kmalloc_stage uses __get_free_page to allocate a pipeline
+ *	stage, along with all the necessary small buffers which together make
+ *	a buffer of size tape->stage_size (or a bit more). We attempt to
+ *	combine sequential pages as much as possible.
+ *
+ *	Returns a pointer to the new allocated stage, or NULL if we
+ *	can't (or don't want to) allocate a stage.
+ *
+ *	Pipeline stages are optional and are used to increase performance.
+ *	If we can't allocate them, we'll manage without them.
+ */
+static idetape_stage_t *__idetape_kmalloc_stage (idetape_tape_t *tape, int full, int clear)
+{
+	idetape_stage_t *stage;
+	struct idetape_bh *prev_bh, *bh;
+	int pages = tape->pages_per_stage;
+	char *b_data = NULL;
+
+	if ((stage = (idetape_stage_t *) kmalloc (sizeof (idetape_stage_t),GFP_KERNEL)) == NULL)
+		return NULL;
+	stage->next = NULL;
+
+	bh = stage->bh = (struct idetape_bh *)kmalloc(sizeof(struct idetape_bh), GFP_KERNEL);
+	if (bh == NULL)
+		goto abort;
+	bh->b_reqnext = NULL;
+	if ((bh->b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
+		goto abort;
+	if (clear)
+		memset(bh->b_data, 0, PAGE_SIZE);
+	bh->b_size = PAGE_SIZE;
+	atomic_set(&bh->b_count, full ? bh->b_size : 0);
+
+	while (--pages) {
+		if ((b_data = (char *) __get_free_page (GFP_KERNEL)) == NULL)
+			goto abort;
+		if (clear)
+			memset(b_data, 0, PAGE_SIZE);
+		if (bh->b_data == b_data + PAGE_SIZE) {
+			bh->b_size += PAGE_SIZE;
+			bh->b_data -= PAGE_SIZE;
+			if (full)
+				atomic_add(PAGE_SIZE, &bh->b_count);
+			continue;
+		}
+		if (b_data == bh->b_data + bh->b_size) {
+			bh->b_size += PAGE_SIZE;
+			if (full)
+				atomic_add(PAGE_SIZE, &bh->b_count);
+			continue;
+		}
+		prev_bh = bh;
+		if ((bh = (struct idetape_bh *)kmalloc(sizeof(struct idetape_bh), GFP_KERNEL)) == NULL) {
+			free_page((unsigned long) b_data);
+			goto abort;
+		}
+		bh->b_reqnext = NULL;
+		bh->b_data = b_data;
+		bh->b_size = PAGE_SIZE;
+		atomic_set(&bh->b_count, full ? bh->b_size : 0);
+		prev_bh->b_reqnext = bh;
+	}
+	bh->b_size -= tape->excess_bh_size;
+	if (full)
+		atomic_sub(tape->excess_bh_size, &bh->b_count);
+	return stage;
+abort:
+	__idetape_kfree_stage(stage);
+	return NULL;
+}
+
+static idetape_stage_t *idetape_kmalloc_stage (idetape_tape_t *tape)
+{
+	idetape_stage_t *cache_stage = tape->cache_stage;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_kmalloc_stage\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	if (tape->nr_stages >= tape->max_stages)
+		return NULL;
+	if (cache_stage != NULL) {
+		tape->cache_stage = NULL;
+		return cache_stage;
+	}
+	return __idetape_kmalloc_stage(tape, 0, 0);
+}
+
+static void idetape_copy_stage_from_user (idetape_tape_t *tape, idetape_stage_t *stage, const char __user *buf, int n)
+{
+	struct idetape_bh *bh = tape->bh;
+	int count;
+
+	while (n) {
+#if IDETAPE_DEBUG_BUGS
+		if (bh == NULL) {
+			printk(KERN_ERR "ide-tape: bh == NULL in "
+				"idetape_copy_stage_from_user\n");
+			return;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		count = min((unsigned int)(bh->b_size - atomic_read(&bh->b_count)), (unsigned int)n);
+		copy_from_user(bh->b_data + atomic_read(&bh->b_count), buf, count);
+		n -= count;
+		atomic_add(count, &bh->b_count);
+		buf += count;
+		if (atomic_read(&bh->b_count) == bh->b_size) {
+			bh = bh->b_reqnext;
+			if (bh)
+				atomic_set(&bh->b_count, 0);
+		}
+	}
+	tape->bh = bh;
+}
+
+static void idetape_copy_stage_to_user (idetape_tape_t *tape, char __user *buf, idetape_stage_t *stage, int n)
+{
+	struct idetape_bh *bh = tape->bh;
+	int count;
+
+	while (n) {
+#if IDETAPE_DEBUG_BUGS
+		if (bh == NULL) {
+			printk(KERN_ERR "ide-tape: bh == NULL in "
+				"idetape_copy_stage_to_user\n");
+			return;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		count = min(tape->b_count, n);
+		copy_to_user(buf, tape->b_data, count);
+		n -= count;
+		tape->b_data += count;
+		tape->b_count -= count;
+		buf += count;
+		if (!tape->b_count) {
+			tape->bh = bh = bh->b_reqnext;
+			if (bh) {
+				tape->b_data = bh->b_data;
+				tape->b_count = atomic_read(&bh->b_count);
+			}
+		}
+	}
+}
+
+static void idetape_init_merge_stage (idetape_tape_t *tape)
+{
+	struct idetape_bh *bh = tape->merge_stage->bh;
+	
+	tape->bh = bh;
+	if (tape->chrdev_direction == idetape_direction_write)
+		atomic_set(&bh->b_count, 0);
+	else {
+		tape->b_data = bh->b_data;
+		tape->b_count = atomic_read(&bh->b_count);
+	}
+}
+
+static void idetape_switch_buffers (idetape_tape_t *tape, idetape_stage_t *stage)
+{
+	struct idetape_bh *tmp;
+
+	tmp = stage->bh;
+	stage->bh = tape->merge_stage->bh;
+	tape->merge_stage->bh = tmp;
+	idetape_init_merge_stage(tape);
+}
+
+/*
+ *	idetape_add_stage_tail adds a new stage at the end of the pipeline.
+ */
+static void idetape_add_stage_tail (ide_drive_t *drive,idetape_stage_t *stage)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	unsigned long flags;
+	
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk (KERN_INFO "ide-tape: Reached idetape_add_stage_tail\n");
+#endif /* IDETAPE_DEBUG_LOG */
+	spin_lock_irqsave(&tape->spinlock, flags);
+	stage->next = NULL;
+	if (tape->last_stage != NULL)
+		tape->last_stage->next=stage;
+	else
+		tape->first_stage = tape->next_stage=stage;
+	tape->last_stage = stage;
+	if (tape->next_stage == NULL)
+		tape->next_stage = tape->last_stage;
+	tape->nr_stages++;
+	tape->nr_pending_stages++;
+	spin_unlock_irqrestore(&tape->spinlock, flags);
+}
+
+/*
+ *	idetape_wait_for_request installs a completion in a pending request
+ *	and sleeps until it is serviced.
+ *
+ *	The caller should ensure that the request will not be serviced
+ *	before we install the completion (usually by disabling interrupts).
+ */
+static void idetape_wait_for_request (ide_drive_t *drive, struct request *rq)
+{
+	DECLARE_COMPLETION(wait);
+	idetape_tape_t *tape = drive->driver_data;
+
+#if IDETAPE_DEBUG_BUGS
+	if (rq == NULL || (rq->flags & REQ_SPECIAL) == 0) {
+		printk (KERN_ERR "ide-tape: bug: Trying to sleep on non-valid request\n");
+		return;
+	}
+#endif /* IDETAPE_DEBUG_BUGS */
+	rq->waiting = &wait;
+	rq->end_io = blk_end_sync_rq;
+	spin_unlock_irq(&tape->spinlock);
+	wait_for_completion(&wait);
+	/* The stage and its struct request have been deallocated */
+	spin_lock_irq(&tape->spinlock);
+}
+
+static ide_startstop_t idetape_read_position_callback (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_read_position_result_t *result;
+	
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_read_position_callback\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	if (!tape->pc->error) {
+		result = (idetape_read_position_result_t *) tape->pc->buffer;
+#if IDETAPE_DEBUG_LOG
+		if (tape->debug_level >= 2)
+			printk(KERN_INFO "ide-tape: BOP - %s\n",result->bop ? "Yes":"No");
+		if (tape->debug_level >= 2)
+			printk(KERN_INFO "ide-tape: EOP - %s\n",result->eop ? "Yes":"No");
+#endif /* IDETAPE_DEBUG_LOG */
+		if (result->bpu) {
+			printk(KERN_INFO "ide-tape: Block location is unknown to the tape\n");
+			clear_bit(IDETAPE_ADDRESS_VALID, &tape->flags);
+			idetape_end_request(drive, 0, 0);
+		} else {
+#if IDETAPE_DEBUG_LOG
+			if (tape->debug_level >= 2)
+				printk(KERN_INFO "ide-tape: Block Location - %u\n", ntohl(result->first_block));
+#endif /* IDETAPE_DEBUG_LOG */
+			tape->partition = result->partition;
+			tape->first_frame_position = ntohl(result->first_block);
+			tape->last_frame_position = ntohl(result->last_block);
+			tape->blocks_in_buffer = result->blocks_in_buffer[2];
+			set_bit(IDETAPE_ADDRESS_VALID, &tape->flags);
+			idetape_end_request(drive, 1, 0);
+		}
+	} else {
+		idetape_end_request(drive, 0, 0);
+	}
+	return ide_stopped;
+}
+
+/*
+ *	idetape_create_write_filemark_cmd will:
+ *
+ *		1.	Write a filemark if write_filemark=1.
+ *		2.	Flush the device buffers without writing a filemark
+ *			if write_filemark=0.
+ *
+ */
+static void idetape_create_write_filemark_cmd (ide_drive_t *drive, idetape_pc_t *pc,int write_filemark)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_WRITE_FILEMARK_CMD;
+	pc->c[4] = write_filemark;
+	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
+	pc->callback = &idetape_pc_callback;
+}
+
+static void idetape_create_test_unit_ready_cmd(idetape_pc_t *pc)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_TEST_UNIT_READY_CMD;
+	pc->callback = &idetape_pc_callback;
+}
+
+/*
+ *	idetape_queue_pc_tail is based on the following functions:
+ *
+ *	ide_do_drive_cmd from ide.c
+ *	cdrom_queue_request and cdrom_queue_packet_command from ide-cd.c
+ *
+ *	We add a special packet command request to the tail of the request
+ *	queue, and wait for it to be serviced.
+ *
+ *	This is not to be called from within the request handling part
+ *	of the driver ! We allocate here data in the stack, and it is valid
+ *	until the request is finished. This is not the case for the bottom
+ *	part of the driver, where we are always leaving the functions to wait
+ *	for an interrupt or a timer event.
+ *
+ *	From the bottom part of the driver, we should allocate safe memory
+ *	using idetape_next_pc_storage and idetape_next_rq_storage, and add
+ *	the request to the request list without waiting for it to be serviced !
+ *	In that case, we usually use idetape_queue_pc_head.
+ */
+static int __idetape_queue_pc_tail (ide_drive_t *drive, idetape_pc_t *pc)
+{
+	struct ide_tape_obj *tape = drive->driver_data;
+	struct request rq;
+
+	idetape_init_rq(&rq, REQ_IDETAPE_PC1);
+	rq.buffer = (char *) pc;
+	rq.rq_disk = tape->disk;
+	return ide_do_drive_cmd(drive, &rq, ide_wait);
+}
+
+static void idetape_create_load_unload_cmd (ide_drive_t *drive, idetape_pc_t *pc,int cmd)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_LOAD_UNLOAD_CMD;
+	pc->c[4] = cmd;
+	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
+	pc->callback = &idetape_pc_callback;
+}
+
+static int idetape_wait_ready(ide_drive_t *drive, unsigned long timeout)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t pc;
+	int load_attempted = 0;
+
+	/*
+	 * Wait for the tape to become ready
+	 */
+	set_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
+	timeout += jiffies;
+	while (time_before(jiffies, timeout)) {
+		idetape_create_test_unit_ready_cmd(&pc);
+		if (!__idetape_queue_pc_tail(drive, &pc))
+			return 0;
+		if ((tape->sense_key == 2 && tape->asc == 4 && tape->ascq == 2)
+		    || (tape->asc == 0x3A)) {	/* no media */
+			if (load_attempted)
+				return -ENOMEDIUM;
+			idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
+			__idetape_queue_pc_tail(drive, &pc);
+			load_attempted = 1;
+		/* not about to be ready */
+		} else if (!(tape->sense_key == 2 && tape->asc == 4 &&
+			     (tape->ascq == 1 || tape->ascq == 8)))
+			return -EIO;
+		current->state = TASK_INTERRUPTIBLE;
+  		schedule_timeout(HZ / 10);
+	}
+	return -EIO;
+}
+
+static int idetape_queue_pc_tail (ide_drive_t *drive,idetape_pc_t *pc)
+{
+	return __idetape_queue_pc_tail(drive, pc);
+}
+
+static int idetape_flush_tape_buffers (ide_drive_t *drive)
+{
+	idetape_pc_t pc;
+	int rc;
+
+	idetape_create_write_filemark_cmd(drive, &pc, 0);
+	if ((rc = idetape_queue_pc_tail(drive, &pc)))
+		return rc;
+	idetape_wait_ready(drive, 60 * 5 * HZ);
+	return 0;
+}
+
+static void idetape_create_read_position_cmd (idetape_pc_t *pc)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_READ_POSITION_CMD;
+	pc->request_transfer = 20;
+	pc->callback = &idetape_read_position_callback;
+}
+
+static int idetape_read_position (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t pc;
+	int position;
+
+#if IDETAPE_DEBUG_LOG
+        if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_read_position\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	idetape_create_read_position_cmd(&pc);
+	if (idetape_queue_pc_tail(drive, &pc))
+		return -1;
+	position = tape->first_frame_position;
+	return position;
+}
+
+static void idetape_create_locate_cmd (ide_drive_t *drive, idetape_pc_t *pc, unsigned int block, u8 partition, int skip)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_LOCATE_CMD;
+	pc->c[1] = 2;
+	put_unaligned(htonl(block), (unsigned int *) &pc->c[3]);
+	pc->c[8] = partition;
+	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
+	pc->callback = &idetape_pc_callback;
+}
+
+static int idetape_create_prevent_cmd (ide_drive_t *drive, idetape_pc_t *pc, int prevent)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	if (!tape->capabilities.lock)
+		return 0;
+
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_PREVENT_CMD;
+	pc->c[4] = prevent;
+	pc->callback = &idetape_pc_callback;
+	return 1;
+}
+
+static int __idetape_discard_read_pipeline (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	unsigned long flags;
+	int cnt;
+
+	if (tape->chrdev_direction != idetape_direction_read)
+		return 0;
+
+	/* Remove merge stage. */
+	cnt = tape->merge_stage_size / tape->tape_block_size;
+	if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
+		++cnt;		/* Filemarks count as 1 sector */
+	tape->merge_stage_size = 0;
+	if (tape->merge_stage != NULL) {
+		__idetape_kfree_stage(tape->merge_stage);
+		tape->merge_stage = NULL;
+	}
+
+	/* Clear pipeline flags. */
+	clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
+	tape->chrdev_direction = idetape_direction_none;
+
+	/* Remove pipeline stages. */
+	if (tape->first_stage == NULL)
+		return 0;
+
+	spin_lock_irqsave(&tape->spinlock, flags);
+	tape->next_stage = NULL;
+	if (idetape_pipeline_active(tape))
+		idetape_wait_for_request(drive, tape->active_data_request);
+	spin_unlock_irqrestore(&tape->spinlock, flags);
+
+	while (tape->first_stage != NULL) {
+		struct request *rq_ptr = &tape->first_stage->rq;
+
+		cnt += rq_ptr->nr_sectors - rq_ptr->current_nr_sectors; 
+		if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK)
+			++cnt;
+		idetape_remove_stage_head(drive);
+	}
+	tape->nr_pending_stages = 0;
+	tape->max_stages = tape->min_pipeline;
+	return cnt;
+}
+
+/*
+ *	idetape_position_tape positions the tape to the requested block
+ *	using the LOCATE packet command. A READ POSITION command is then
+ *	issued to check where we are positioned.
+ *
+ *	Like all higher level operations, we queue the commands at the tail
+ *	of the request queue and wait for their completion.
+ *	
+ */
+static int idetape_position_tape (ide_drive_t *drive, unsigned int block, u8 partition, int skip)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	int retval;
+	idetape_pc_t pc;
+
+	if (tape->chrdev_direction == idetape_direction_read)
+		__idetape_discard_read_pipeline(drive);
+	idetape_wait_ready(drive, 60 * 5 * HZ);
+	idetape_create_locate_cmd(drive, &pc, block, partition, skip);
+	retval = idetape_queue_pc_tail(drive, &pc);
+	if (retval)
+		return (retval);
+
+	idetape_create_read_position_cmd(&pc);
+	return (idetape_queue_pc_tail(drive, &pc));
+}
+
+static void idetape_discard_read_pipeline (ide_drive_t *drive, int restore_position)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	int cnt;
+	int seek, position;
+
+	cnt = __idetape_discard_read_pipeline(drive);
+	if (restore_position) {
+		position = idetape_read_position(drive);
+		seek = position > cnt ? position - cnt : 0;
+		if (idetape_position_tape(drive, seek, 0, 0)) {
+			printk(KERN_INFO "ide-tape: %s: position_tape failed in discard_pipeline()\n", tape->name);
+			return;
+		}
+	}
+}
+
+/*
+ * idetape_queue_rw_tail generates a read/write request for the block
+ * device interface and wait for it to be serviced.
+ */
+static int idetape_queue_rw_tail(ide_drive_t *drive, int cmd, int blocks, struct idetape_bh *bh)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct request rq;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 2)
+		printk(KERN_INFO "ide-tape: idetape_queue_rw_tail: cmd=%d\n",cmd);
+#endif /* IDETAPE_DEBUG_LOG */
+#if IDETAPE_DEBUG_BUGS
+	if (idetape_pipeline_active(tape)) {
+		printk(KERN_ERR "ide-tape: bug: the pipeline is active in idetape_queue_rw_tail\n");
+		return (0);
+	}
+#endif /* IDETAPE_DEBUG_BUGS */	
+
+	idetape_init_rq(&rq, cmd);
+	rq.rq_disk = tape->disk;
+	rq.special = (void *)bh;
+	rq.sector = tape->first_frame_position;
+	rq.nr_sectors = rq.current_nr_sectors = blocks;
+	(void) ide_do_drive_cmd(drive, &rq, ide_wait);
+
+	if ((cmd & (REQ_IDETAPE_READ | REQ_IDETAPE_WRITE)) == 0)
+		return 0;
+
+	if (tape->merge_stage)
+		idetape_init_merge_stage(tape);
+	if (rq.errors == IDETAPE_ERROR_GENERAL)
+		return -EIO;
+	return (tape->tape_block_size * (blocks-rq.current_nr_sectors));
+}
+
+/*
+ *	idetape_insert_pipeline_into_queue is used to start servicing the
+ *	pipeline stages, starting from tape->next_stage.
+ */
+static void idetape_insert_pipeline_into_queue (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	if (tape->next_stage == NULL)
+		return;
+	if (!idetape_pipeline_active(tape)) {
+		set_bit(IDETAPE_PIPELINE_ACTIVE, &tape->flags);
+		idetape_active_next_stage(drive);
+		(void) ide_do_drive_cmd(drive, tape->active_data_request, ide_end);
+	}
+}
+
+static void idetape_create_inquiry_cmd (idetape_pc_t *pc)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_INQUIRY_CMD;
+	pc->c[4] = pc->request_transfer = 254;
+	pc->callback = &idetape_pc_callback;
+}
+
+static void idetape_create_rewind_cmd (ide_drive_t *drive, idetape_pc_t *pc)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_REWIND_CMD;
+	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
+	pc->callback = &idetape_pc_callback;
+}
+
+#if 0
+static void idetape_create_mode_select_cmd (idetape_pc_t *pc, int length)
+{
+	idetape_init_pc(pc);
+	set_bit(PC_WRITING, &pc->flags);
+	pc->c[0] = IDETAPE_MODE_SELECT_CMD;
+	pc->c[1] = 0x10;
+	put_unaligned(htons(length), (unsigned short *) &pc->c[3]);
+	pc->request_transfer = 255;
+	pc->callback = &idetape_pc_callback;
+}
+#endif
+
+static void idetape_create_erase_cmd (idetape_pc_t *pc)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_ERASE_CMD;
+	pc->c[1] = 1;
+	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
+	pc->callback = &idetape_pc_callback;
+}
+
+static void idetape_create_space_cmd (idetape_pc_t *pc,int count, u8 cmd)
+{
+	idetape_init_pc(pc);
+	pc->c[0] = IDETAPE_SPACE_CMD;
+	put_unaligned(htonl(count), (unsigned int *) &pc->c[1]);
+	pc->c[1] = cmd;
+	set_bit(PC_WAIT_FOR_DSC, &pc->flags);
+	pc->callback = &idetape_pc_callback;
+}
+
+static void idetape_wait_first_stage (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	unsigned long flags;
+
+	if (tape->first_stage == NULL)
+		return;
+	spin_lock_irqsave(&tape->spinlock, flags);
+	if (tape->active_stage == tape->first_stage)
+		idetape_wait_for_request(drive, tape->active_data_request);
+	spin_unlock_irqrestore(&tape->spinlock, flags);
+}
+
+/*
+ *	idetape_add_chrdev_write_request tries to add a character device
+ *	originated write request to our pipeline. In case we don't succeed,
+ *	we revert to non-pipelined operation mode for this request.
+ *
+ *	1.	Try to allocate a new pipeline stage.
+ *	2.	If we can't, wait for more and more requests to be serviced
+ *		and try again each time.
+ *	3.	If we still can't allocate a stage, fallback to
+ *		non-pipelined operation mode for this request.
+ */
+static int idetape_add_chrdev_write_request (ide_drive_t *drive, int blocks)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_stage_t *new_stage;
+	unsigned long flags;
+	struct request *rq;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 3)
+		printk(KERN_INFO "ide-tape: Reached idetape_add_chrdev_write_request\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+     	/*
+     	 *	Attempt to allocate a new stage.
+	 *	Pay special attention to possible race conditions.
+	 */
+	while ((new_stage = idetape_kmalloc_stage(tape)) == NULL) {
+		spin_lock_irqsave(&tape->spinlock, flags);
+		if (idetape_pipeline_active(tape)) {
+			idetape_wait_for_request(drive, tape->active_data_request);
+			spin_unlock_irqrestore(&tape->spinlock, flags);
+		} else {
+			spin_unlock_irqrestore(&tape->spinlock, flags);
+			idetape_insert_pipeline_into_queue(drive);
+			if (idetape_pipeline_active(tape))
+				continue;
+			/*
+			 *	Linux is short on memory. Fallback to
+			 *	non-pipelined operation mode for this request.
+			 */
+			return idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
+		}
+	}
+	rq = &new_stage->rq;
+	idetape_init_rq(rq, REQ_IDETAPE_WRITE);
+	/* Doesn't actually matter - We always assume sequential access */
+	rq->sector = tape->first_frame_position;
+	rq->nr_sectors = rq->current_nr_sectors = blocks;
+
+	idetape_switch_buffers(tape, new_stage);
+	idetape_add_stage_tail(drive, new_stage);
+	tape->pipeline_head++;
+#if USE_IOTRACE
+	IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
+#endif
+	calculate_speeds(drive);
+
+	/*
+	 *	Estimate whether the tape has stopped writing by checking
+	 *	if our write pipeline is currently empty. If we are not
+	 *	writing anymore, wait for the pipeline to be full enough
+	 *	(90%) before starting to service requests, so that we will
+	 *	be able to keep up with the higher speeds of the tape.
+	 */
+	if (!idetape_pipeline_active(tape)) {
+		if (tape->nr_stages >= tape->max_stages * 9 / 10 ||
+		    tape->nr_stages >= tape->max_stages - tape->uncontrolled_pipeline_head_speed * 3 * 1024 / tape->tape_block_size) {
+			tape->measure_insert_time = 1;
+			tape->insert_time = jiffies;
+			tape->insert_size = 0;
+			tape->insert_speed = 0;
+			idetape_insert_pipeline_into_queue(drive);
+		}
+	}
+	if (test_and_clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
+		/* Return a deferred error */
+		return -EIO;
+	return blocks;
+}
+
+/*
+ *	idetape_wait_for_pipeline will wait until all pending pipeline
+ *	requests are serviced. Typically called on device close.
+ */
+static void idetape_wait_for_pipeline (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	unsigned long flags;
+
+	while (tape->next_stage || idetape_pipeline_active(tape)) {
+		idetape_insert_pipeline_into_queue(drive);
+		spin_lock_irqsave(&tape->spinlock, flags);
+		if (idetape_pipeline_active(tape))
+			idetape_wait_for_request(drive, tape->active_data_request);
+		spin_unlock_irqrestore(&tape->spinlock, flags);
+	}
+}
+
+static void idetape_empty_write_pipeline (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	int blocks, min;
+	struct idetape_bh *bh;
+	
+#if IDETAPE_DEBUG_BUGS
+	if (tape->chrdev_direction != idetape_direction_write) {
+		printk(KERN_ERR "ide-tape: bug: Trying to empty write pipeline, but we are not writing.\n");
+		return;
+	}
+	if (tape->merge_stage_size > tape->stage_size) {
+		printk(KERN_ERR "ide-tape: bug: merge_buffer too big\n");
+		tape->merge_stage_size = tape->stage_size;
+	}
+#endif /* IDETAPE_DEBUG_BUGS */
+	if (tape->merge_stage_size) {
+		blocks = tape->merge_stage_size / tape->tape_block_size;
+		if (tape->merge_stage_size % tape->tape_block_size) {
+			unsigned int i;
+
+			blocks++;
+			i = tape->tape_block_size - tape->merge_stage_size % tape->tape_block_size;
+			bh = tape->bh->b_reqnext;
+			while (bh) {
+				atomic_set(&bh->b_count, 0);
+				bh = bh->b_reqnext;
+			}
+			bh = tape->bh;
+			while (i) {
+				if (bh == NULL) {
+
+					printk(KERN_INFO "ide-tape: bug, bh NULL\n");
+					break;
+				}
+				min = min(i, (unsigned int)(bh->b_size - atomic_read(&bh->b_count)));
+				memset(bh->b_data + atomic_read(&bh->b_count), 0, min);
+				atomic_add(min, &bh->b_count);
+				i -= min;
+				bh = bh->b_reqnext;
+			}
+		}
+		(void) idetape_add_chrdev_write_request(drive, blocks);
+		tape->merge_stage_size = 0;
+	}
+	idetape_wait_for_pipeline(drive);
+	if (tape->merge_stage != NULL) {
+		__idetape_kfree_stage(tape->merge_stage);
+		tape->merge_stage = NULL;
+	}
+	clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
+	tape->chrdev_direction = idetape_direction_none;
+
+	/*
+	 *	On the next backup, perform the feedback loop again.
+	 *	(I don't want to keep sense information between backups,
+	 *	 as some systems are constantly on, and the system load
+	 *	 can be totally different on the next backup).
+	 */
+	tape->max_stages = tape->min_pipeline;
+#if IDETAPE_DEBUG_BUGS
+	if (tape->first_stage != NULL ||
+	    tape->next_stage != NULL ||
+	    tape->last_stage != NULL ||
+	    tape->nr_stages != 0) {
+		printk(KERN_ERR "ide-tape: ide-tape pipeline bug, "
+			"first_stage %p, next_stage %p, "
+			"last_stage %p, nr_stages %d\n",
+			tape->first_stage, tape->next_stage,
+			tape->last_stage, tape->nr_stages);
+	}
+#endif /* IDETAPE_DEBUG_BUGS */
+}
+
+static void idetape_restart_speed_control (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	tape->restart_speed_control_req = 0;
+	tape->pipeline_head = 0;
+	tape->controlled_last_pipeline_head = tape->uncontrolled_last_pipeline_head = 0;
+	tape->controlled_previous_pipeline_head = tape->uncontrolled_previous_pipeline_head = 0;
+	tape->pipeline_head_speed = tape->controlled_pipeline_head_speed = 5000;
+	tape->uncontrolled_pipeline_head_speed = 0;
+	tape->controlled_pipeline_head_time = tape->uncontrolled_pipeline_head_time = jiffies;
+	tape->controlled_previous_head_time = tape->uncontrolled_previous_head_time = jiffies;
+}
+
+static int idetape_initiate_read (ide_drive_t *drive, int max_stages)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_stage_t *new_stage;
+	struct request rq;
+	int bytes_read;
+	int blocks = tape->capabilities.ctl;
+
+	/* Initialize read operation */
+	if (tape->chrdev_direction != idetape_direction_read) {
+		if (tape->chrdev_direction == idetape_direction_write) {
+			idetape_empty_write_pipeline(drive);
+			idetape_flush_tape_buffers(drive);
+		}
+#if IDETAPE_DEBUG_BUGS
+		if (tape->merge_stage || tape->merge_stage_size) {
+			printk (KERN_ERR "ide-tape: merge_stage_size should be 0 now\n");
+			tape->merge_stage_size = 0;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		if ((tape->merge_stage = __idetape_kmalloc_stage(tape, 0, 0)) == NULL)
+			return -ENOMEM;
+		tape->chrdev_direction = idetape_direction_read;
+
+		/*
+		 *	Issue a read 0 command to ensure that DSC handshake
+		 *	is switched from completion mode to buffer available
+		 *	mode.
+		 *	No point in issuing this if DSC overlap isn't supported,
+		 *	some drives (Seagate STT3401A) will return an error.
+		 */
+		if (drive->dsc_overlap) {
+			bytes_read = idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, 0, tape->merge_stage->bh);
+			if (bytes_read < 0) {
+				__idetape_kfree_stage(tape->merge_stage);
+				tape->merge_stage = NULL;
+				tape->chrdev_direction = idetape_direction_none;
+				return bytes_read;
+			}
+		}
+	}
+	if (tape->restart_speed_control_req)
+		idetape_restart_speed_control(drive);
+	idetape_init_rq(&rq, REQ_IDETAPE_READ);
+	rq.sector = tape->first_frame_position;
+	rq.nr_sectors = rq.current_nr_sectors = blocks;
+	if (!test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags) &&
+	    tape->nr_stages < max_stages) {
+		new_stage = idetape_kmalloc_stage(tape);
+		while (new_stage != NULL) {
+			new_stage->rq = rq;
+			idetape_add_stage_tail(drive, new_stage);
+			if (tape->nr_stages >= max_stages)
+				break;
+			new_stage = idetape_kmalloc_stage(tape);
+		}
+	}
+	if (!idetape_pipeline_active(tape)) {
+		if (tape->nr_pending_stages >= 3 * max_stages / 4) {
+			tape->measure_insert_time = 1;
+			tape->insert_time = jiffies;
+			tape->insert_size = 0;
+			tape->insert_speed = 0;
+			idetape_insert_pipeline_into_queue(drive);
+		}
+	}
+	return 0;
+}
+
+/*
+ *	idetape_add_chrdev_read_request is called from idetape_chrdev_read
+ *	to service a character device read request and add read-ahead
+ *	requests to our pipeline.
+ */
+static int idetape_add_chrdev_read_request (ide_drive_t *drive,int blocks)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	unsigned long flags;
+	struct request *rq_ptr;
+	int bytes_read;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_add_chrdev_read_request, %d blocks\n", blocks);
+#endif /* IDETAPE_DEBUG_LOG */
+
+	/*
+	 * If we are at a filemark, return a read length of 0
+	 */
+	if (test_bit(IDETAPE_FILEMARK, &tape->flags))
+		return 0;
+
+	/*
+	 * Wait for the next block to be available at the head
+	 * of the pipeline
+	 */
+	idetape_initiate_read(drive, tape->max_stages);
+	if (tape->first_stage == NULL) {
+		if (test_bit(IDETAPE_PIPELINE_ERROR, &tape->flags))
+			return 0;
+		return idetape_queue_rw_tail(drive, REQ_IDETAPE_READ, blocks, tape->merge_stage->bh);
+	}
+	idetape_wait_first_stage(drive);
+	rq_ptr = &tape->first_stage->rq;
+	bytes_read = tape->tape_block_size * (rq_ptr->nr_sectors - rq_ptr->current_nr_sectors);
+	rq_ptr->nr_sectors = rq_ptr->current_nr_sectors = 0;
+
+
+	if (rq_ptr->errors == IDETAPE_ERROR_EOD)
+		return 0;
+	else {
+		idetape_switch_buffers(tape, tape->first_stage);
+		if (rq_ptr->errors == IDETAPE_ERROR_FILEMARK)
+			set_bit(IDETAPE_FILEMARK, &tape->flags);
+		spin_lock_irqsave(&tape->spinlock, flags);
+		idetape_remove_stage_head(drive);
+		spin_unlock_irqrestore(&tape->spinlock, flags);
+		tape->pipeline_head++;
+#if USE_IOTRACE
+		IO_trace(IO_IDETAPE_FIFO, tape->pipeline_head, tape->buffer_head, tape->tape_head, tape->minor);
+#endif
+		calculate_speeds(drive);
+	}
+#if IDETAPE_DEBUG_BUGS
+	if (bytes_read > blocks * tape->tape_block_size) {
+		printk(KERN_ERR "ide-tape: bug: trying to return more bytes than requested\n");
+		bytes_read = blocks * tape->tape_block_size;
+	}
+#endif /* IDETAPE_DEBUG_BUGS */
+	return (bytes_read);
+}
+
+static void idetape_pad_zeros (ide_drive_t *drive, int bcount)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	struct idetape_bh *bh;
+	int blocks;
+	
+	while (bcount) {
+		unsigned int count;
+
+		bh = tape->merge_stage->bh;
+		count = min(tape->stage_size, bcount);
+		bcount -= count;
+		blocks = count / tape->tape_block_size;
+		while (count) {
+			atomic_set(&bh->b_count, min(count, (unsigned int)bh->b_size));
+			memset(bh->b_data, 0, atomic_read(&bh->b_count));
+			count -= atomic_read(&bh->b_count);
+			bh = bh->b_reqnext;
+		}
+		idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, blocks, tape->merge_stage->bh);
+	}
+}
+
+static int idetape_pipeline_size (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_stage_t *stage;
+	struct request *rq;
+	int size = 0;
+
+	idetape_wait_for_pipeline(drive);
+	stage = tape->first_stage;
+	while (stage != NULL) {
+		rq = &stage->rq;
+		size += tape->tape_block_size * (rq->nr_sectors-rq->current_nr_sectors);
+		if (rq->errors == IDETAPE_ERROR_FILEMARK)
+			size += tape->tape_block_size;
+		stage = stage->next;
+	}
+	size += tape->merge_stage_size;
+	return size;
+}
+
+/*
+ *	Rewinds the tape to the Beginning Of the current Partition (BOP).
+ *
+ *	We currently support only one partition.
+ */ 
+static int idetape_rewind_tape (ide_drive_t *drive)
+{
+	int retval;
+	idetape_pc_t pc;
+#if IDETAPE_DEBUG_LOG
+	idetape_tape_t *tape = drive->driver_data;
+	if (tape->debug_level >= 2)
+		printk(KERN_INFO "ide-tape: Reached idetape_rewind_tape\n");
+#endif /* IDETAPE_DEBUG_LOG */	
+	
+	idetape_create_rewind_cmd(drive, &pc);
+	retval = idetape_queue_pc_tail(drive, &pc);
+	if (retval)
+		return retval;
+
+	idetape_create_read_position_cmd(&pc);
+	retval = idetape_queue_pc_tail(drive, &pc);
+	if (retval)
+		return retval;
+	return 0;
+}
+
+/*
+ *	Our special ide-tape ioctl's.
+ *
+ *	Currently there aren't any ioctl's.
+ *	mtio.h compatible commands should be issued to the character device
+ *	interface.
+ */
+static int idetape_blkdev_ioctl(ide_drive_t *drive, unsigned int cmd, unsigned long arg)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_config_t config;
+	void __user *argp = (void __user *)arg;
+
+#if IDETAPE_DEBUG_LOG	
+	if (tape->debug_level >= 4)
+		printk(KERN_INFO "ide-tape: Reached idetape_blkdev_ioctl\n");
+#endif /* IDETAPE_DEBUG_LOG */
+	switch (cmd) {
+		case 0x0340:
+			if (copy_from_user(&config, argp, sizeof (idetape_config_t)))
+				return -EFAULT;
+			tape->best_dsc_rw_frequency = config.dsc_rw_frequency;
+			tape->max_stages = config.nr_stages;
+			break;
+		case 0x0350:
+			config.dsc_rw_frequency = (int) tape->best_dsc_rw_frequency;
+			config.nr_stages = tape->max_stages; 
+			if (copy_to_user(argp, &config, sizeof (idetape_config_t)))
+				return -EFAULT;
+			break;
+		default:
+			return -EIO;
+	}
+	return 0;
+}
+
+/*
+ *	idetape_space_over_filemarks is now a bit more complicated than just
+ *	passing the command to the tape since we may have crossed some
+ *	filemarks during our pipelined read-ahead mode.
+ *
+ *	As a minor side effect, the pipeline enables us to support MTFSFM when
+ *	the filemark is in our internal pipeline even if the tape doesn't
+ *	support spacing over filemarks in the reverse direction.
+ */
+static int idetape_space_over_filemarks (ide_drive_t *drive,short mt_op,int mt_count)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t pc;
+	unsigned long flags;
+	int retval,count=0;
+
+	if (mt_count == 0)
+		return 0;
+	if (MTBSF == mt_op || MTBSFM == mt_op) {
+		if (!tape->capabilities.sprev)
+			return -EIO;
+		mt_count = - mt_count;
+	}
+
+	if (tape->chrdev_direction == idetape_direction_read) {
+		/*
+		 *	We have a read-ahead buffer. Scan it for crossed
+		 *	filemarks.
+		 */
+		tape->merge_stage_size = 0;
+		if (test_and_clear_bit(IDETAPE_FILEMARK, &tape->flags))
+			++count;
+		while (tape->first_stage != NULL) {
+			if (count == mt_count) {
+				if (mt_op == MTFSFM)
+					set_bit(IDETAPE_FILEMARK, &tape->flags);
+				return 0;
+			}
+			spin_lock_irqsave(&tape->spinlock, flags);
+			if (tape->first_stage == tape->active_stage) {
+				/*
+				 *	We have reached the active stage in the read pipeline.
+				 *	There is no point in allowing the drive to continue
+				 *	reading any farther, so we stop the pipeline.
+				 *
+				 *	This section should be moved to a separate subroutine,
+				 *	because a similar function is performed in
+				 *	__idetape_discard_read_pipeline(), for example.
+				 */
+				tape->next_stage = NULL;
+				spin_unlock_irqrestore(&tape->spinlock, flags);
+				idetape_wait_first_stage(drive);
+				tape->next_stage = tape->first_stage->next;
+			} else
+				spin_unlock_irqrestore(&tape->spinlock, flags);
+			if (tape->first_stage->rq.errors == IDETAPE_ERROR_FILEMARK)
+				++count;
+			idetape_remove_stage_head(drive);
+		}
+		idetape_discard_read_pipeline(drive, 0);
+	}
+
+	/*
+	 *	The filemark was not found in our internal pipeline.
+	 *	Now we can issue the space command.
+	 */
+	switch (mt_op) {
+		case MTFSF:
+		case MTBSF:
+			idetape_create_space_cmd(&pc,mt_count-count,IDETAPE_SPACE_OVER_FILEMARK);
+			return (idetape_queue_pc_tail(drive, &pc));
+		case MTFSFM:
+		case MTBSFM:
+			if (!tape->capabilities.sprev)
+				return (-EIO);
+			retval = idetape_space_over_filemarks(drive, MTFSF, mt_count-count);
+			if (retval) return (retval);
+			count = (MTBSFM == mt_op ? 1 : -1);
+			return (idetape_space_over_filemarks(drive, MTFSF, count));
+		default:
+			printk(KERN_ERR "ide-tape: MTIO operation %d not supported\n",mt_op);
+			return (-EIO);
+	}
+}
+
+
+/*
+ *	Our character device read / write functions.
+ *
+ *	The tape is optimized to maximize throughput when it is transferring
+ *	an integral number of the "continuous transfer limit", which is
+ *	a parameter of the specific tape (26 KB on my particular tape).
+ *      (32 kB for Onstream)
+ *
+ *	As of version 1.3 of the driver, the character device provides an
+ *	abstract continuous view of the media - any mix of block sizes (even 1
+ *	byte) on the same backup/restore procedure is supported. The driver
+ *	will internally convert the requests to the recommended transfer unit,
+ *	so that an unmatch between the user's block size to the recommended
+ *	size will only result in a (slightly) increased driver overhead, but
+ *	will no longer hit performance.
+ *      This is not applicable to Onstream.
+ */
+static ssize_t idetape_chrdev_read (struct file *file, char __user *buf,
+				    size_t count, loff_t *ppos)
+{
+	struct ide_tape_obj *tape = ide_tape_f(file);
+	ide_drive_t *drive = tape->drive;
+	ssize_t bytes_read,temp, actually_read = 0, rc;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 3)
+		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_read, count %Zd\n", count);
+#endif /* IDETAPE_DEBUG_LOG */
+
+	if (tape->chrdev_direction != idetape_direction_read) {
+		if (test_bit(IDETAPE_DETECT_BS, &tape->flags))
+			if (count > tape->tape_block_size &&
+			    (count % tape->tape_block_size) == 0)
+				tape->user_bs_factor = count / tape->tape_block_size;
+	}
+	if ((rc = idetape_initiate_read(drive, tape->max_stages)) < 0)
+		return rc;
+	if (count == 0)
+		return (0);
+	if (tape->merge_stage_size) {
+		actually_read = min((unsigned int)(tape->merge_stage_size), (unsigned int)count);
+		idetape_copy_stage_to_user(tape, buf, tape->merge_stage, actually_read);
+		buf += actually_read;
+		tape->merge_stage_size -= actually_read;
+		count -= actually_read;
+	}
+	while (count >= tape->stage_size) {
+		bytes_read = idetape_add_chrdev_read_request(drive, tape->capabilities.ctl);
+		if (bytes_read <= 0)
+			goto finish;
+		idetape_copy_stage_to_user(tape, buf, tape->merge_stage, bytes_read);
+		buf += bytes_read;
+		count -= bytes_read;
+		actually_read += bytes_read;
+	}
+	if (count) {
+		bytes_read = idetape_add_chrdev_read_request(drive, tape->capabilities.ctl);
+		if (bytes_read <= 0)
+			goto finish;
+		temp = min((unsigned long)count, (unsigned long)bytes_read);
+		idetape_copy_stage_to_user(tape, buf, tape->merge_stage, temp);
+		actually_read += temp;
+		tape->merge_stage_size = bytes_read-temp;
+	}
+finish:
+	if (!actually_read && test_bit(IDETAPE_FILEMARK, &tape->flags)) {
+#if IDETAPE_DEBUG_LOG
+		if (tape->debug_level >= 2)
+			printk(KERN_INFO "ide-tape: %s: spacing over filemark\n", tape->name);
+#endif
+		idetape_space_over_filemarks(drive, MTFSF, 1);
+		return 0;
+	}
+	return actually_read;
+}
+
+static ssize_t idetape_chrdev_write (struct file *file, const char __user *buf,
+				     size_t count, loff_t *ppos)
+{
+	struct ide_tape_obj *tape = ide_tape_f(file);
+	ide_drive_t *drive = tape->drive;
+	ssize_t retval, actually_written = 0;
+
+	/* The drive is write protected. */
+	if (tape->write_prot)
+		return -EACCES;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 3)
+		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_write, "
+			"count %Zd\n", count);
+#endif /* IDETAPE_DEBUG_LOG */
+
+	/* Initialize write operation */
+	if (tape->chrdev_direction != idetape_direction_write) {
+		if (tape->chrdev_direction == idetape_direction_read)
+			idetape_discard_read_pipeline(drive, 1);
+#if IDETAPE_DEBUG_BUGS
+		if (tape->merge_stage || tape->merge_stage_size) {
+			printk(KERN_ERR "ide-tape: merge_stage_size "
+				"should be 0 now\n");
+			tape->merge_stage_size = 0;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		if ((tape->merge_stage = __idetape_kmalloc_stage(tape, 0, 0)) == NULL)
+			return -ENOMEM;
+		tape->chrdev_direction = idetape_direction_write;
+		idetape_init_merge_stage(tape);
+
+		/*
+		 *	Issue a write 0 command to ensure that DSC handshake
+		 *	is switched from completion mode to buffer available
+		 *	mode.
+		 *	No point in issuing this if DSC overlap isn't supported,
+		 *	some drives (Seagate STT3401A) will return an error.
+		 */
+		if (drive->dsc_overlap) {
+			retval = idetape_queue_rw_tail(drive, REQ_IDETAPE_WRITE, 0, tape->merge_stage->bh);
+			if (retval < 0) {
+				__idetape_kfree_stage(tape->merge_stage);
+				tape->merge_stage = NULL;
+				tape->chrdev_direction = idetape_direction_none;
+				return retval;
+			}
+		}
+	}
+	if (count == 0)
+		return (0);
+	if (tape->restart_speed_control_req)
+		idetape_restart_speed_control(drive);
+	if (tape->merge_stage_size) {
+#if IDETAPE_DEBUG_BUGS
+		if (tape->merge_stage_size >= tape->stage_size) {
+			printk(KERN_ERR "ide-tape: bug: merge buffer too big\n");
+			tape->merge_stage_size = 0;
+		}
+#endif /* IDETAPE_DEBUG_BUGS */
+		actually_written = min((unsigned int)(tape->stage_size - tape->merge_stage_size), (unsigned int)count);
+		idetape_copy_stage_from_user(tape, tape->merge_stage, buf, actually_written);
+		buf += actually_written;
+		tape->merge_stage_size += actually_written;
+		count -= actually_written;
+
+		if (tape->merge_stage_size == tape->stage_size) {
+			tape->merge_stage_size = 0;
+			retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
+			if (retval <= 0)
+				return (retval);
+		}
+	}
+	while (count >= tape->stage_size) {
+		idetape_copy_stage_from_user(tape, tape->merge_stage, buf, tape->stage_size);
+		buf += tape->stage_size;
+		count -= tape->stage_size;
+		retval = idetape_add_chrdev_write_request(drive, tape->capabilities.ctl);
+		actually_written += tape->stage_size;
+		if (retval <= 0)
+			return (retval);
+	}
+	if (count) {
+		actually_written += count;
+		idetape_copy_stage_from_user(tape, tape->merge_stage, buf, count);
+		tape->merge_stage_size += count;
+	}
+	return (actually_written);
+}
+
+static int idetape_write_filemark (ide_drive_t *drive)
+{
+	idetape_pc_t pc;
+
+	/* Write a filemark */
+	idetape_create_write_filemark_cmd(drive, &pc, 1);
+	if (idetape_queue_pc_tail(drive, &pc)) {
+		printk(KERN_ERR "ide-tape: Couldn't write a filemark\n");
+		return -EIO;
+	}
+	return 0;
+}
+
+/*
+ *	idetape_mtioctop is called from idetape_chrdev_ioctl when
+ *	the general mtio MTIOCTOP ioctl is requested.
+ *
+ *	We currently support the following mtio.h operations:
+ *
+ *	MTFSF	-	Space over mt_count filemarks in the positive direction.
+ *			The tape is positioned after the last spaced filemark.
+ *
+ *	MTFSFM	-	Same as MTFSF, but the tape is positioned before the
+ *			last filemark.
+ *
+ *	MTBSF	-	Steps background over mt_count filemarks, tape is
+ *			positioned before the last filemark.
+ *
+ *	MTBSFM	-	Like MTBSF, only tape is positioned after the last filemark.
+ *
+ *	Note:
+ *
+ *		MTBSF and MTBSFM are not supported when the tape doesn't
+ *		support spacing over filemarks in the reverse direction.
+ *		In this case, MTFSFM is also usually not supported (it is
+ *		supported in the rare case in which we crossed the filemark
+ *		during our read-ahead pipelined operation mode).
+ *		
+ *	MTWEOF	-	Writes mt_count filemarks. Tape is positioned after
+ *			the last written filemark.
+ *
+ *	MTREW	-	Rewinds tape.
+ *
+ *	MTLOAD	-	Loads the tape.
+ *
+ *	MTOFFL	-	Puts the tape drive "Offline": Rewinds the tape and
+ *	MTUNLOAD	prevents further access until the media is replaced.
+ *
+ *	MTNOP	-	Flushes tape buffers.
+ *
+ *	MTRETEN	-	Retension media. This typically consists of one end
+ *			to end pass on the media.
+ *
+ *	MTEOM	-	Moves to the end of recorded data.
+ *
+ *	MTERASE	-	Erases tape.
+ *
+ *	MTSETBLK - 	Sets the user block size to mt_count bytes. If
+ *			mt_count is 0, we will attempt to autodetect
+ *			the block size.
+ *
+ *	MTSEEK	-	Positions the tape in a specific block number, where
+ *			each block is assumed to contain which user_block_size
+ *			bytes.
+ *
+ *	MTSETPART - 	Switches to another tape partition.
+ *
+ *	MTLOCK - 	Locks the tape door.
+ *
+ *	MTUNLOCK - 	Unlocks the tape door.
+ *
+ *	The following commands are currently not supported:
+ *
+ *	MTFSS, MTBSS, MTWSM, MTSETDENSITY,
+ *	MTSETDRVBUFFER, MT_ST_BOOLEANS, MT_ST_WRITE_THRESHOLD.
+ */
+static int idetape_mtioctop (ide_drive_t *drive,short mt_op,int mt_count)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t pc;
+	int i,retval;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 1)
+		printk(KERN_INFO "ide-tape: Handling MTIOCTOP ioctl: "
+			"mt_op=%d, mt_count=%d\n", mt_op, mt_count);
+#endif /* IDETAPE_DEBUG_LOG */
+	/*
+	 *	Commands which need our pipelined read-ahead stages.
+	 */
+	switch (mt_op) {
+		case MTFSF:
+		case MTFSFM:
+		case MTBSF:
+		case MTBSFM:
+			if (!mt_count)
+				return (0);
+			return (idetape_space_over_filemarks(drive,mt_op,mt_count));
+		default:
+			break;
+	}
+	switch (mt_op) {
+		case MTWEOF:
+			if (tape->write_prot)
+				return -EACCES;
+			idetape_discard_read_pipeline(drive, 1);
+			for (i = 0; i < mt_count; i++) {
+				retval = idetape_write_filemark(drive);
+				if (retval)
+					return retval;
+			}
+			return (0);
+		case MTREW:
+			idetape_discard_read_pipeline(drive, 0);
+			if (idetape_rewind_tape(drive))
+				return -EIO;
+			return 0;
+		case MTLOAD:
+			idetape_discard_read_pipeline(drive, 0);
+			idetape_create_load_unload_cmd(drive, &pc, IDETAPE_LU_LOAD_MASK);
+			return (idetape_queue_pc_tail(drive, &pc));
+		case MTUNLOAD:
+		case MTOFFL:
+			/*
+			 * If door is locked, attempt to unlock before
+			 * attempting to eject.
+			 */
+			if (tape->door_locked) {
+				if (idetape_create_prevent_cmd(drive, &pc, 0))
+					if (!idetape_queue_pc_tail(drive, &pc))
+						tape->door_locked = DOOR_UNLOCKED;
+			}
+			idetape_discard_read_pipeline(drive, 0);
+			idetape_create_load_unload_cmd(drive, &pc,!IDETAPE_LU_LOAD_MASK);
+			retval = idetape_queue_pc_tail(drive, &pc);
+			if (!retval)
+				clear_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags);
+			return retval;
+		case MTNOP:
+			idetape_discard_read_pipeline(drive, 0);
+			return (idetape_flush_tape_buffers(drive));
+		case MTRETEN:
+			idetape_discard_read_pipeline(drive, 0);
+			idetape_create_load_unload_cmd(drive, &pc,IDETAPE_LU_RETENSION_MASK | IDETAPE_LU_LOAD_MASK);
+			return (idetape_queue_pc_tail(drive, &pc));
+		case MTEOM:
+			idetape_create_space_cmd(&pc, 0, IDETAPE_SPACE_TO_EOD);
+			return (idetape_queue_pc_tail(drive, &pc));
+		case MTERASE:
+			(void) idetape_rewind_tape(drive);
+			idetape_create_erase_cmd(&pc);
+			return (idetape_queue_pc_tail(drive, &pc));
+		case MTSETBLK:
+			if (mt_count) {
+				if (mt_count < tape->tape_block_size || mt_count % tape->tape_block_size)
+					return -EIO;
+				tape->user_bs_factor = mt_count / tape->tape_block_size;
+				clear_bit(IDETAPE_DETECT_BS, &tape->flags);
+			} else
+				set_bit(IDETAPE_DETECT_BS, &tape->flags);
+			return 0;
+		case MTSEEK:
+			idetape_discard_read_pipeline(drive, 0);
+			return idetape_position_tape(drive, mt_count * tape->user_bs_factor, tape->partition, 0);
+		case MTSETPART:
+			idetape_discard_read_pipeline(drive, 0);
+			return (idetape_position_tape(drive, 0, mt_count, 0));
+		case MTFSR:
+		case MTBSR:
+		case MTLOCK:
+			if (!idetape_create_prevent_cmd(drive, &pc, 1))
+				return 0;
+			retval = idetape_queue_pc_tail(drive, &pc);
+			if (retval) return retval;
+			tape->door_locked = DOOR_EXPLICITLY_LOCKED;
+			return 0;
+		case MTUNLOCK:
+			if (!idetape_create_prevent_cmd(drive, &pc, 0))
+				return 0;
+			retval = idetape_queue_pc_tail(drive, &pc);
+			if (retval) return retval;
+			tape->door_locked = DOOR_UNLOCKED;
+			return 0;
+		default:
+			printk(KERN_ERR "ide-tape: MTIO operation %d not "
+				"supported\n", mt_op);
+			return (-EIO);
+	}
+}
+
+/*
+ *	Our character device ioctls.
+ *
+ *	General mtio.h magnetic io commands are supported here, and not in
+ *	the corresponding block interface.
+ *
+ *	The following ioctls are supported:
+ *
+ *	MTIOCTOP -	Refer to idetape_mtioctop for detailed description.
+ *
+ *	MTIOCGET - 	The mt_dsreg field in the returned mtget structure
+ *			will be set to (user block size in bytes <<
+ *			MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK.
+ *
+ *			The mt_blkno is set to the current user block number.
+ *			The other mtget fields are not supported.
+ *
+ *	MTIOCPOS -	The current tape "block position" is returned. We
+ *			assume that each block contains user_block_size
+ *			bytes.
+ *
+ *	Our own ide-tape ioctls are supported on both interfaces.
+ */
+static int idetape_chrdev_ioctl (struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
+{
+	struct ide_tape_obj *tape = ide_tape_f(file);
+	ide_drive_t *drive = tape->drive;
+	struct mtop mtop;
+	struct mtget mtget;
+	struct mtpos mtpos;
+	int block_offset = 0, position = tape->first_frame_position;
+	void __user *argp = (void __user *)arg;
+
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 3)
+		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_ioctl, "
+			"cmd=%u\n", cmd);
+#endif /* IDETAPE_DEBUG_LOG */
+
+	tape->restart_speed_control_req = 1;
+	if (tape->chrdev_direction == idetape_direction_write) {
+		idetape_empty_write_pipeline(drive);
+		idetape_flush_tape_buffers(drive);
+	}
+	if (cmd == MTIOCGET || cmd == MTIOCPOS) {
+		block_offset = idetape_pipeline_size(drive) / (tape->tape_block_size * tape->user_bs_factor);
+		if ((position = idetape_read_position(drive)) < 0)
+			return -EIO;
+	}
+	switch (cmd) {
+		case MTIOCTOP:
+			if (copy_from_user(&mtop, argp, sizeof (struct mtop)))
+				return -EFAULT;
+			return (idetape_mtioctop(drive,mtop.mt_op,mtop.mt_count));
+		case MTIOCGET:
+			memset(&mtget, 0, sizeof (struct mtget));
+			mtget.mt_type = MT_ISSCSI2;
+			mtget.mt_blkno = position / tape->user_bs_factor - block_offset;
+			mtget.mt_dsreg = ((tape->tape_block_size * tape->user_bs_factor) << MT_ST_BLKSIZE_SHIFT) & MT_ST_BLKSIZE_MASK;
+			if (tape->drv_write_prot) {
+				mtget.mt_gstat |= GMT_WR_PROT(0xffffffff);
+			}
+			if (copy_to_user(argp, &mtget, sizeof(struct mtget)))
+				return -EFAULT;
+			return 0;
+		case MTIOCPOS:
+			mtpos.mt_blkno = position / tape->user_bs_factor - block_offset;
+			if (copy_to_user(argp, &mtpos, sizeof(struct mtpos)))
+				return -EFAULT;
+			return 0;
+		default:
+			if (tape->chrdev_direction == idetape_direction_read)
+				idetape_discard_read_pipeline(drive, 1);
+			return idetape_blkdev_ioctl(drive, cmd, arg);
+	}
+}
+
+static void idetape_get_blocksize_from_block_descriptor(ide_drive_t *drive);
+
+/*
+ *	Our character device open function.
+ */
+static int idetape_chrdev_open (struct inode *inode, struct file *filp)
+{
+	unsigned int minor = iminor(inode), i = minor & ~0xc0;
+	ide_drive_t *drive;
+	idetape_tape_t *tape;
+	idetape_pc_t pc;
+	int retval;
+
+	/*
+	 * We really want to do nonseekable_open(inode, filp); here, but some
+	 * versions of tar incorrectly call lseek on tapes and bail out if that
+	 * fails.  So we disallow pread() and pwrite(), but permit lseeks.
+	 */
+	filp->f_mode &= ~(FMODE_PREAD | FMODE_PWRITE);
+
+#if IDETAPE_DEBUG_LOG
+	printk(KERN_INFO "ide-tape: Reached idetape_chrdev_open\n");
+#endif /* IDETAPE_DEBUG_LOG */
+	
+	if (i >= MAX_HWIFS * MAX_DRIVES)
+		return -ENXIO;
+
+	if (!(tape = ide_tape_chrdev_get(i)))
+		return -ENXIO;
+
+	drive = tape->drive;
+
+	filp->private_data = tape;
+
+	if (test_and_set_bit(IDETAPE_BUSY, &tape->flags)) {
+		retval = -EBUSY;
+		goto out_put_tape;
+	}
+
+	retval = idetape_wait_ready(drive, 60 * HZ);
+	if (retval) {
+		clear_bit(IDETAPE_BUSY, &tape->flags);
+		printk(KERN_ERR "ide-tape: %s: drive not ready\n", tape->name);
+		goto out_put_tape;
+	}
+
+	idetape_read_position(drive);
+	if (!test_bit(IDETAPE_ADDRESS_VALID, &tape->flags))
+		(void)idetape_rewind_tape(drive);
+
+	if (tape->chrdev_direction != idetape_direction_read)
+		clear_bit(IDETAPE_PIPELINE_ERROR, &tape->flags);
+
+	/* Read block size and write protect status from drive. */
+	idetape_get_blocksize_from_block_descriptor(drive);
+
+	/* Set write protect flag if device is opened as read-only. */
+	if ((filp->f_flags & O_ACCMODE) == O_RDONLY)
+		tape->write_prot = 1;
+	else
+		tape->write_prot = tape->drv_write_prot;
+
+	/* Make sure drive isn't write protected if user wants to write. */
+	if (tape->write_prot) {
+		if ((filp->f_flags & O_ACCMODE) == O_WRONLY ||
+		    (filp->f_flags & O_ACCMODE) == O_RDWR) {
+			clear_bit(IDETAPE_BUSY, &tape->flags);
+			retval = -EROFS;
+			goto out_put_tape;
+		}
+	}
+
+	/*
+	 * Lock the tape drive door so user can't eject.
+	 */
+	if (tape->chrdev_direction == idetape_direction_none) {
+		if (idetape_create_prevent_cmd(drive, &pc, 1)) {
+			if (!idetape_queue_pc_tail(drive, &pc)) {
+				if (tape->door_locked != DOOR_EXPLICITLY_LOCKED)
+					tape->door_locked = DOOR_LOCKED;
+			}
+		}
+	}
+	idetape_restart_speed_control(drive);
+	tape->restart_speed_control_req = 0;
+	return 0;
+
+out_put_tape:
+	ide_tape_put(tape);
+	return retval;
+}
+
+static void idetape_write_release (ide_drive_t *drive, unsigned int minor)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+	idetape_empty_write_pipeline(drive);
+	tape->merge_stage = __idetape_kmalloc_stage(tape, 1, 0);
+	if (tape->merge_stage != NULL) {
+		idetape_pad_zeros(drive, tape->tape_block_size * (tape->user_bs_factor - 1));
+		__idetape_kfree_stage(tape->merge_stage);
+		tape->merge_stage = NULL;
+	}
+	idetape_write_filemark(drive);
+	idetape_flush_tape_buffers(drive);
+	idetape_flush_tape_buffers(drive);
+}
+
+/*
+ *	Our character device release function.
+ */
+static int idetape_chrdev_release (struct inode *inode, struct file *filp)
+{
+	struct ide_tape_obj *tape = ide_tape_f(filp);
+	ide_drive_t *drive = tape->drive;
+	idetape_pc_t pc;
+	unsigned int minor = iminor(inode);
+
+	lock_kernel();
+	tape = drive->driver_data;
+#if IDETAPE_DEBUG_LOG
+	if (tape->debug_level >= 3)
+		printk(KERN_INFO "ide-tape: Reached idetape_chrdev_release\n");
+#endif /* IDETAPE_DEBUG_LOG */
+
+	if (tape->chrdev_direction == idetape_direction_write)
+		idetape_write_release(drive, minor);
+	if (tape->chrdev_direction == idetape_direction_read) {
+		if (minor < 128)
+			idetape_discard_read_pipeline(drive, 1);
+		else
+			idetape_wait_for_pipeline(drive);
+	}
+	if (tape->cache_stage != NULL) {
+		__idetape_kfree_stage(tape->cache_stage);
+		tape->cache_stage = NULL;
+	}
+	if (minor < 128 && test_bit(IDETAPE_MEDIUM_PRESENT, &tape->flags))
+		(void) idetape_rewind_tape(drive);
+	if (tape->chrdev_direction == idetape_direction_none) {
+		if (tape->door_locked == DOOR_LOCKED) {
+			if (idetape_create_prevent_cmd(drive, &pc, 0)) {
+				if (!idetape_queue_pc_tail(drive, &pc))
+					tape->door_locked = DOOR_UNLOCKED;
+			}
+		}
+	}
+	clear_bit(IDETAPE_BUSY, &tape->flags);
+	ide_tape_put(tape);
+	unlock_kernel();
+	return 0;
+}
+
+/*
+ *	idetape_identify_device is called to check the contents of the
+ *	ATAPI IDENTIFY command results. We return:
+ *
+ *	1	If the tape can be supported by us, based on the information
+ *		we have so far.
+ *
+ *	0 	If this tape driver is not currently supported by us.
+ */
+static int idetape_identify_device (ide_drive_t *drive)
+{
+	struct idetape_id_gcw gcw;
+	struct hd_driveid *id = drive->id;
+#if IDETAPE_DEBUG_INFO
+	unsigned short mask,i;
+#endif /* IDETAPE_DEBUG_INFO */
+
+	if (drive->id_read == 0)
+		return 1;
+
+	*((unsigned short *) &gcw) = id->config;
+
+#if IDETAPE_DEBUG_INFO
+	printk(KERN_INFO "ide-tape: Dumping ATAPI Identify Device tape parameters\n");
+	printk(KERN_INFO "ide-tape: Protocol Type: ");
+	switch (gcw.protocol) {
+		case 0: case 1: printk("ATA\n");break;
+		case 2:	printk("ATAPI\n");break;
+		case 3: printk("Reserved (Unknown to ide-tape)\n");break;
+	}
+	printk(KERN_INFO "ide-tape: Device Type: %x - ",gcw.device_type);	
+	switch (gcw.device_type) {
+		case 0: printk("Direct-access Device\n");break;
+		case 1: printk("Streaming Tape Device\n");break;
+		case 2: case 3: case 4: printk("Reserved\n");break;
+		case 5: printk("CD-ROM Device\n");break;
+		case 6: printk("Reserved\n");
+		case 7: printk("Optical memory Device\n");break;
+		case 0x1f: printk("Unknown or no Device type\n");break;
+		default: printk("Reserved\n");
+	}
+	printk(KERN_INFO "ide-tape: Removable: %s",gcw.removable ? "Yes\n":"No\n");	
+	printk(KERN_INFO "ide-tape: Command Packet DRQ Type: ");
+	switch (gcw.drq_type) {
+		case 0: printk("Microprocessor DRQ\n");break;
+		case 1: printk("Interrupt DRQ\n");break;
+		case 2: printk("Accelerated DRQ\n");break;
+		case 3: printk("Reserved\n");break;
+	}
+	printk(KERN_INFO "ide-tape: Command Packet Size: ");
+	switch (gcw.packet_size) {
+		case 0: printk("12 bytes\n");break;
+		case 1: printk("16 bytes\n");break;
+		default: printk("Reserved\n");break;
+	}
+	printk(KERN_INFO "ide-tape: Model: %.40s\n",id->model);
+	printk(KERN_INFO "ide-tape: Firmware Revision: %.8s\n",id->fw_rev);
+	printk(KERN_INFO "ide-tape: Serial Number: %.20s\n",id->serial_no);
+	printk(KERN_INFO "ide-tape: Write buffer size: %d bytes\n",id->buf_size*512);
+	printk(KERN_INFO "ide-tape: DMA: %s",id->capability & 0x01 ? "Yes\n":"No\n");
+	printk(KERN_INFO "ide-tape: LBA: %s",id->capability & 0x02 ? "Yes\n":"No\n");
+	printk(KERN_INFO "ide-tape: IORDY can be disabled: %s",id->capability & 0x04 ? "Yes\n":"No\n");
+	printk(KERN_INFO "ide-tape: IORDY supported: %s",id->capability & 0x08 ? "Yes\n":"Unknown\n");
+	printk(KERN_INFO "ide-tape: ATAPI overlap supported: %s",id->capability & 0x20 ? "Yes\n":"No\n");
+	printk(KERN_INFO "ide-tape: PIO Cycle Timing Category: %d\n",id->tPIO);
+	printk(KERN_INFO "ide-tape: DMA Cycle Timing Category: %d\n",id->tDMA);
+	printk(KERN_INFO "ide-tape: Single Word DMA supported modes: ");
+	for (i=0,mask=1;i<8;i++,mask=mask << 1) {
+		if (id->dma_1word & mask)
+			printk("%d ",i);
+		if (id->dma_1word & (mask << 8))
+			printk("(active) ");
+	}
+	printk("\n");
+	printk(KERN_INFO "ide-tape: Multi Word DMA supported modes: ");
+	for (i=0,mask=1;i<8;i++,mask=mask << 1) {
+		if (id->dma_mword & mask)
+			printk("%d ",i);
+		if (id->dma_mword & (mask << 8))
+			printk("(active) ");
+	}
+	printk("\n");
+	if (id->field_valid & 0x0002) {
+		printk(KERN_INFO "ide-tape: Enhanced PIO Modes: %s\n",
+			id->eide_pio_modes & 1 ? "Mode 3":"None");
+		printk(KERN_INFO "ide-tape: Minimum Multi-word DMA cycle per word: ");
+		if (id->eide_dma_min == 0)
+			printk("Not supported\n");
+		else
+			printk("%d ns\n",id->eide_dma_min);
+
+		printk(KERN_INFO "ide-tape: Manufacturer\'s Recommended Multi-word cycle: ");
+		if (id->eide_dma_time == 0)
+			printk("Not supported\n");
+		else
+			printk("%d ns\n",id->eide_dma_time);
+
+		printk(KERN_INFO "ide-tape: Minimum PIO cycle without IORDY: ");
+		if (id->eide_pio == 0)
+			printk("Not supported\n");
+		else
+			printk("%d ns\n",id->eide_pio);
+
+		printk(KERN_INFO "ide-tape: Minimum PIO cycle with IORDY: ");
+		if (id->eide_pio_iordy == 0)
+			printk("Not supported\n");
+		else
+			printk("%d ns\n",id->eide_pio_iordy);
+		
+	} else
+		printk(KERN_INFO "ide-tape: According to the device, fields 64-70 are not valid.\n");
+#endif /* IDETAPE_DEBUG_INFO */
+
+	/* Check that we can support this device */
+
+	if (gcw.protocol !=2 )
+		printk(KERN_ERR "ide-tape: Protocol is not ATAPI\n");
+	else if (gcw.device_type != 1)
+		printk(KERN_ERR "ide-tape: Device type is not set to tape\n");
+	else if (!gcw.removable)
+		printk(KERN_ERR "ide-tape: The removable flag is not set\n");
+	else if (gcw.packet_size != 0) {
+		printk(KERN_ERR "ide-tape: Packet size is not 12 bytes long\n");
+		if (gcw.packet_size == 1)
+			printk(KERN_ERR "ide-tape: Sorry, padding to 16 bytes is still not supported\n");
+	} else
+		return 1;
+	return 0;
+}
+
+/*
+ * Use INQUIRY to get the firmware revision
+ */
+static void idetape_get_inquiry_results (ide_drive_t *drive)
+{
+	char *r;
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t pc;
+	idetape_inquiry_result_t *inquiry;
+	
+	idetape_create_inquiry_cmd(&pc);
+	if (idetape_queue_pc_tail(drive, &pc)) {
+		printk(KERN_ERR "ide-tape: %s: can't get INQUIRY results\n", tape->name);
+		return;
+	}
+	inquiry = (idetape_inquiry_result_t *) pc.buffer;
+	memcpy(tape->vendor_id, inquiry->vendor_id, 8);
+	memcpy(tape->product_id, inquiry->product_id, 16);
+	memcpy(tape->firmware_revision, inquiry->revision_level, 4);
+	ide_fixstring(tape->vendor_id, 10, 0);
+	ide_fixstring(tape->product_id, 18, 0);
+	ide_fixstring(tape->firmware_revision, 6, 0);
+	r = tape->firmware_revision;
+	if (*(r + 1) == '.')
+		tape->firmware_revision_num = (*r - '0') * 100 + (*(r + 2) - '0') * 10 + *(r + 3) - '0';
+	printk(KERN_INFO "ide-tape: %s <-> %s: %s %s rev %s\n", drive->name, tape->name, tape->vendor_id, tape->product_id, tape->firmware_revision);
+}
+
+/*
+ *	idetape_get_mode_sense_results asks the tape about its various
+ *	parameters. In particular, we will adjust our data transfer buffer
+ *	size to the recommended value as returned by the tape.
+ */
+static void idetape_get_mode_sense_results (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t pc;
+	idetape_mode_parameter_header_t *header;
+	idetape_capabilities_page_t *capabilities;
+	
+	idetape_create_mode_sense_cmd(&pc, IDETAPE_CAPABILITIES_PAGE);
+	if (idetape_queue_pc_tail(drive, &pc)) {
+		printk(KERN_ERR "ide-tape: Can't get tape parameters - assuming some default values\n");
+		tape->tape_block_size = 512;
+		tape->capabilities.ctl = 52;
+		tape->capabilities.speed = 450;
+		tape->capabilities.buffer_size = 6 * 52;
+		return;
+	}
+	header = (idetape_mode_parameter_header_t *) pc.buffer;
+	capabilities = (idetape_capabilities_page_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t) + header->bdl);
+
+	capabilities->max_speed = ntohs(capabilities->max_speed);
+	capabilities->ctl = ntohs(capabilities->ctl);
+	capabilities->speed = ntohs(capabilities->speed);
+	capabilities->buffer_size = ntohs(capabilities->buffer_size);
+
+	if (!capabilities->speed) {
+		printk(KERN_INFO "ide-tape: %s: overriding capabilities->speed (assuming 650KB/sec)\n", drive->name);
+		capabilities->speed = 650;
+	}
+	if (!capabilities->max_speed) {
+		printk(KERN_INFO "ide-tape: %s: overriding capabilities->max_speed (assuming 650KB/sec)\n", drive->name);
+		capabilities->max_speed = 650;
+	}
+
+	tape->capabilities = *capabilities;		/* Save us a copy */
+	if (capabilities->blk512)
+		tape->tape_block_size = 512;
+	else if (capabilities->blk1024)
+		tape->tape_block_size = 1024;
+
+#if IDETAPE_DEBUG_INFO
+	printk(KERN_INFO "ide-tape: Dumping the results of the MODE SENSE packet command\n");
+	printk(KERN_INFO "ide-tape: Mode Parameter Header:\n");
+	printk(KERN_INFO "ide-tape: Mode Data Length - %d\n",header->mode_data_length);
+	printk(KERN_INFO "ide-tape: Medium Type - %d\n",header->medium_type);
+	printk(KERN_INFO "ide-tape: Device Specific Parameter - %d\n",header->dsp);
+	printk(KERN_INFO "ide-tape: Block Descriptor Length - %d\n",header->bdl);
+	
+	printk(KERN_INFO "ide-tape: Capabilities and Mechanical Status Page:\n");
+	printk(KERN_INFO "ide-tape: Page code - %d\n",capabilities->page_code);
+	printk(KERN_INFO "ide-tape: Page length - %d\n",capabilities->page_length);
+	printk(KERN_INFO "ide-tape: Read only - %s\n",capabilities->ro ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports reverse space - %s\n",capabilities->sprev ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports erase initiated formatting - %s\n",capabilities->efmt ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports QFA two Partition format - %s\n",capabilities->qfa ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports locking the medium - %s\n",capabilities->lock ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: The volume is currently locked - %s\n",capabilities->locked ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: The device defaults in the prevent state - %s\n",capabilities->prevent ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports ejecting the medium - %s\n",capabilities->eject ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports error correction - %s\n",capabilities->ecc ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports data compression - %s\n",capabilities->cmprs ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports 512 bytes block size - %s\n",capabilities->blk512 ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports 1024 bytes block size - %s\n",capabilities->blk1024 ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Supports 32768 bytes block size / Restricted byte count for PIO transfers - %s\n",capabilities->blk32768 ? "Yes":"No");
+	printk(KERN_INFO "ide-tape: Maximum supported speed in KBps - %d\n",capabilities->max_speed);
+	printk(KERN_INFO "ide-tape: Continuous transfer limits in blocks - %d\n",capabilities->ctl);
+	printk(KERN_INFO "ide-tape: Current speed in KBps - %d\n",capabilities->speed);	
+	printk(KERN_INFO "ide-tape: Buffer size - %d\n",capabilities->buffer_size*512);
+#endif /* IDETAPE_DEBUG_INFO */
+}
+
+/*
+ *	ide_get_blocksize_from_block_descriptor does a mode sense page 0 with block descriptor
+ *	and if it succeeds sets the tape block size with the reported value
+ */
+static void idetape_get_blocksize_from_block_descriptor(ide_drive_t *drive)
+{
+
+	idetape_tape_t *tape = drive->driver_data;
+	idetape_pc_t pc;
+	idetape_mode_parameter_header_t *header;
+	idetape_parameter_block_descriptor_t *block_descrp;
+	
+	idetape_create_mode_sense_cmd(&pc, IDETAPE_BLOCK_DESCRIPTOR);
+	if (idetape_queue_pc_tail(drive, &pc)) {
+		printk(KERN_ERR "ide-tape: Can't get block descriptor\n");
+		if (tape->tape_block_size == 0) {
+			printk(KERN_WARNING "ide-tape: Cannot deal with zero block size, assume 32k\n");
+			tape->tape_block_size =  32768;
+		}
+		return;
+	}
+	header = (idetape_mode_parameter_header_t *) pc.buffer;
+	block_descrp = (idetape_parameter_block_descriptor_t *) (pc.buffer + sizeof(idetape_mode_parameter_header_t));
+	tape->tape_block_size =( block_descrp->length[0]<<16) + (block_descrp->length[1]<<8) + block_descrp->length[2];
+	tape->drv_write_prot = (header->dsp & 0x80) >> 7;
+
+#if IDETAPE_DEBUG_INFO
+	printk(KERN_INFO "ide-tape: Adjusted block size - %d\n", tape->tape_block_size);
+#endif /* IDETAPE_DEBUG_INFO */
+}
+static void idetape_add_settings (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+
+/*
+ *			drive	setting name	read/write	ioctl	ioctl		data type	min			max			mul_factor			div_factor			data pointer				set function
+ */
+	ide_add_setting(drive,	"buffer",	SETTING_READ,	-1,	-1,		TYPE_SHORT,	0,			0xffff,			1,				2,				&tape->capabilities.buffer_size,	NULL);
+	ide_add_setting(drive,	"pipeline_min",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->min_pipeline,			NULL);
+	ide_add_setting(drive,	"pipeline",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->max_stages,			NULL);
+	ide_add_setting(drive,	"pipeline_max",	SETTING_RW,	-1,	-1,		TYPE_INT,	1,			0xffff,			tape->stage_size / 1024,	1,				&tape->max_pipeline,			NULL);
+	ide_add_setting(drive,	"pipeline_used",SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			tape->stage_size / 1024,	1,				&tape->nr_stages,			NULL);
+	ide_add_setting(drive,	"pipeline_pending",SETTING_READ,-1,	-1,		TYPE_INT,	0,			0xffff,			tape->stage_size / 1024,	1,				&tape->nr_pending_stages,		NULL);
+	ide_add_setting(drive,	"speed",	SETTING_READ,	-1,	-1,		TYPE_SHORT,	0,			0xffff,			1,				1,				&tape->capabilities.speed,		NULL);
+	ide_add_setting(drive,	"stage",	SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1024,				&tape->stage_size,			NULL);
+	ide_add_setting(drive,	"tdsc",		SETTING_RW,	-1,	-1,		TYPE_INT,	IDETAPE_DSC_RW_MIN,	IDETAPE_DSC_RW_MAX,	1000,				HZ,				&tape->best_dsc_rw_frequency,		NULL);
+	ide_add_setting(drive,	"dsc_overlap",	SETTING_RW,	-1,	-1,		TYPE_BYTE,	0,			1,			1,				1,				&drive->dsc_overlap,			NULL);
+	ide_add_setting(drive,	"pipeline_head_speed_c",SETTING_READ,	-1,	-1,	TYPE_INT,	0,			0xffff,			1,				1,				&tape->controlled_pipeline_head_speed,	NULL);
+	ide_add_setting(drive,	"pipeline_head_speed_u",SETTING_READ,	-1,	-1,	TYPE_INT,	0,			0xffff,			1,				1,				&tape->uncontrolled_pipeline_head_speed,	NULL);
+	ide_add_setting(drive,	"avg_speed",	SETTING_READ,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1,				&tape->avg_speed,		NULL);
+	ide_add_setting(drive,	"debug_level",SETTING_RW,	-1,	-1,		TYPE_INT,	0,			0xffff,			1,				1,				&tape->debug_level,		NULL);
+}
+
+/*
+ *	ide_setup is called to:
+ *
+ *		1.	Initialize our various state variables.
+ *		2.	Ask the tape for its capabilities.
+ *		3.	Allocate a buffer which will be used for data
+ *			transfer. The buffer size is chosen based on
+ *			the recommendation which we received in step (2).
+ *
+ *	Note that at this point ide.c already assigned us an irq, so that
+ *	we can queue requests here and wait for their completion.
+ */
+static void idetape_setup (ide_drive_t *drive, idetape_tape_t *tape, int minor)
+{
+	unsigned long t1, tmid, tn, t;
+	int speed;
+	struct idetape_id_gcw gcw;
+	int stage_size;
+	struct sysinfo si;
+
+	spin_lock_init(&tape->spinlock);
+	drive->dsc_overlap = 1;
+#ifdef CONFIG_BLK_DEV_IDEPCI
+	if (HWIF(drive)->pci_dev != NULL) {
+		/*
+		 * These two ide-pci host adapters appear to need DSC overlap disabled.
+		 * This probably needs further analysis.
+		 */
+		if ((HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_ARTOP_ATP850UF) ||
+		    (HWIF(drive)->pci_dev->device == PCI_DEVICE_ID_TTI_HPT343)) {
+			printk(KERN_INFO "ide-tape: %s: disabling DSC overlap\n", tape->name);
+		    	drive->dsc_overlap = 0;
+		}
+	}
+#endif /* CONFIG_BLK_DEV_IDEPCI */
+	/* Seagate Travan drives do not support DSC overlap. */
+	if (strstr(drive->id->model, "Seagate STT3401"))
+		drive->dsc_overlap = 0;
+	tape->minor = minor;
+	tape->name[0] = 'h';
+	tape->name[1] = 't';
+	tape->name[2] = '0' + minor;
+	tape->chrdev_direction = idetape_direction_none;
+	tape->pc = tape->pc_stack;
+	tape->max_insert_speed = 10000;
+	tape->speed_control = 1;
+	*((unsigned short *) &gcw) = drive->id->config;
+	if (gcw.drq_type == 1)
+		set_bit(IDETAPE_DRQ_INTERRUPT, &tape->flags);
+
+	tape->min_pipeline = tape->max_pipeline = tape->max_stages = 10;
+	
+	idetape_get_inquiry_results(drive);
+	idetape_get_mode_sense_results(drive);
+	idetape_get_blocksize_from_block_descriptor(drive);
+	tape->user_bs_factor = 1;
+	tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
+	while (tape->stage_size > 0xffff) {
+		printk(KERN_NOTICE "ide-tape: decreasing stage size\n");
+		tape->capabilities.ctl /= 2;
+		tape->stage_size = tape->capabilities.ctl * tape->tape_block_size;
+	}
+	stage_size = tape->stage_size;
+	tape->pages_per_stage = stage_size / PAGE_SIZE;
+	if (stage_size % PAGE_SIZE) {
+		tape->pages_per_stage++;
+		tape->excess_bh_size = PAGE_SIZE - stage_size % PAGE_SIZE;
+	}
+
+	/*
+	 *	Select the "best" DSC read/write polling frequency
+	 *	and pipeline size.
+	 */
+	speed = max(tape->capabilities.speed, tape->capabilities.max_speed);
+
+	tape->max_stages = speed * 1000 * 10 / tape->stage_size;
+
+	/*
+	 * 	Limit memory use for pipeline to 10% of physical memory
+	 */
+	si_meminfo(&si);
+	if (tape->max_stages * tape->stage_size > si.totalram * si.mem_unit / 10)
+		tape->max_stages = si.totalram * si.mem_unit / (10 * tape->stage_size);
+	tape->max_stages   = min(tape->max_stages, IDETAPE_MAX_PIPELINE_STAGES);
+	tape->min_pipeline = min(tape->max_stages, IDETAPE_MIN_PIPELINE_STAGES);
+	tape->max_pipeline = min(tape->max_stages * 2, IDETAPE_MAX_PIPELINE_STAGES);
+	if (tape->max_stages == 0)
+		tape->max_stages = tape->min_pipeline = tape->max_pipeline = 1;
+
+	t1 = (tape->stage_size * HZ) / (speed * 1000);
+	tmid = (tape->capabilities.buffer_size * 32 * HZ) / (speed * 125);
+	tn = (IDETAPE_FIFO_THRESHOLD * tape->stage_size * HZ) / (speed * 1000);
+
+	if (tape->max_stages)
+		t = tn;
+	else
+		t = t1;
+
+	/*
+	 *	Ensure that the number we got makes sense; limit
+	 *	it within IDETAPE_DSC_RW_MIN and IDETAPE_DSC_RW_MAX.
+	 */
+	tape->best_dsc_rw_frequency = max_t(unsigned long, min_t(unsigned long, t, IDETAPE_DSC_RW_MAX), IDETAPE_DSC_RW_MIN);
+	printk(KERN_INFO "ide-tape: %s <-> %s: %dKBps, %d*%dkB buffer, "
+		"%dkB pipeline, %lums tDSC%s\n",
+		drive->name, tape->name, tape->capabilities.speed,
+		(tape->capabilities.buffer_size * 512) / tape->stage_size,
+		tape->stage_size / 1024,
+		tape->max_stages * tape->stage_size / 1024,
+		tape->best_dsc_rw_frequency * 1000 / HZ,
+		drive->using_dma ? ", DMA":"");
+
+	idetape_add_settings(drive);
+}
+
+static int idetape_cleanup (ide_drive_t *drive)
+{
+	idetape_tape_t *tape = drive->driver_data;
+	unsigned long flags;
+
+	spin_lock_irqsave(&ide_lock, flags);
+	if (test_bit(IDETAPE_BUSY, &tape->flags) || drive->usage ||
+	    tape->first_stage != NULL || tape->merge_stage_size) {
+		spin_unlock_irqrestore(&ide_lock, flags);
+		return 1;
+	}
+
+	spin_unlock_irqrestore(&ide_lock, flags);
+	DRIVER(drive)->busy = 0;
+	(void) ide_unregister_subdriver(drive);
+
+	ide_unregister_region(tape->disk);
+
+	ide_tape_put(tape);
+
+	return 0;
+}
+
+static void ide_tape_release(struct kref *kref)
+{
+	struct ide_tape_obj *tape = to_ide_tape(kref);
+	ide_drive_t *drive = tape->drive;
+	struct gendisk *g = tape->disk;
+
+	drive->dsc_overlap = 0;
+	drive->driver_data = NULL;
+	devfs_remove("%s/mt", drive->devfs_name);
+	devfs_remove("%s/mtn", drive->devfs_name);
+	devfs_unregister_tape(g->number);
+	idetape_devs[tape->minor] = NULL;
+	g->private_data = NULL;
+	put_disk(g);
+	kfree(tape);
+}
+
+#ifdef CONFIG_PROC_FS
+
+static int proc_idetape_read_name
+	(char *page, char **start, off_t off, int count, int *eof, void *data)
+{
+	ide_drive_t	*drive = (ide_drive_t *) data;
+	idetape_tape_t	*tape = drive->driver_data;
+	char		*out = page;
+	int		len;
+
+	len = sprintf(out, "%s\n", tape->name);
+	PROC_IDE_READ_RETURN(page, start, off, count, eof, len);
+}
+
+static ide_proc_entry_t idetape_proc[] = {
+	{ "capacity",	S_IFREG|S_IRUGO,	proc_ide_read_capacity, NULL },
+	{ "name",	S_IFREG|S_IRUGO,	proc_idetape_read_name,	NULL },
+	{ NULL, 0, NULL, NULL }
+};
+
+#else
+
+#define	idetape_proc	NULL
+
+#endif
+
+static int idetape_attach(ide_drive_t *drive);
+
+/*
+ *	IDE subdriver functions, registered with ide.c
+ */
+static ide_driver_t idetape_driver = {
+	.owner			= THIS_MODULE,
+	.name			= "ide-tape",
+	.version		= IDETAPE_VERSION,
+	.media			= ide_tape,
+	.busy			= 1,
+	.supports_dsc_overlap 	= 1,
+	.cleanup		= idetape_cleanup,
+	.do_request		= idetape_do_request,
+	.end_request		= idetape_end_request,
+	.error			= __ide_error,
+	.abort			= __ide_abort,
+	.proc			= idetape_proc,
+	.attach			= idetape_attach,
+	.drives			= LIST_HEAD_INIT(idetape_driver.drives),
+};
+
+/*
+ *	Our character device supporting functions, passed to register_chrdev.
+ */
+static struct file_operations idetape_fops = {
+	.owner		= THIS_MODULE,
+	.read		= idetape_chrdev_read,
+	.write		= idetape_chrdev_write,
+	.ioctl		= idetape_chrdev_ioctl,
+	.open		= idetape_chrdev_open,
+	.release	= idetape_chrdev_release,
+};
+
+static int idetape_open(struct inode *inode, struct file *filp)
+{
+	struct gendisk *disk = inode->i_bdev->bd_disk;
+	struct ide_tape_obj *tape;
+	ide_drive_t *drive;
+
+	if (!(tape = ide_tape_get(disk)))
+		return -ENXIO;
+
+	drive = tape->drive;
+
+	drive->usage++;
+
+	return 0;
+}
+
+static int idetape_release(struct inode *inode, struct file *filp)
+{
+	struct gendisk *disk = inode->i_bdev->bd_disk;
+	struct ide_tape_obj *tape = ide_tape_g(disk);
+	ide_drive_t *drive = tape->drive;
+
+	drive->usage--;
+
+	ide_tape_put(tape);
+
+	return 0;
+}
+
+static int idetape_ioctl(struct inode *inode, struct file *file,
+			unsigned int cmd, unsigned long arg)
+{
+	struct block_device *bdev = inode->i_bdev;
+	struct ide_tape_obj *tape = ide_tape_g(bdev->bd_disk);
+	ide_drive_t *drive = tape->drive;
+	int err = generic_ide_ioctl(drive, file, bdev, cmd, arg);
+	if (err == -EINVAL)
+		err = idetape_blkdev_ioctl(drive, cmd, arg);
+	return err;
+}
+
+static struct block_device_operations idetape_block_ops = {
+	.owner		= THIS_MODULE,
+	.open		= idetape_open,
+	.release	= idetape_release,
+	.ioctl		= idetape_ioctl,
+};
+
+static int idetape_attach (ide_drive_t *drive)
+{
+	idetape_tape_t *tape;
+	struct gendisk *g;
+	int minor;
+
+	if (!strstr("ide-tape", drive->driver_req))
+		goto failed;
+	if (!drive->present)
+		goto failed;
+	if (drive->media != ide_tape)
+		goto failed;
+	if (!idetape_identify_device (drive)) {
+		printk(KERN_ERR "ide-tape: %s: not supported by this version of ide-tape\n", drive->name);
+		goto failed;
+	}
+	if (drive->scsi) {
+		printk("ide-tape: passing drive %s to ide-scsi emulation.\n", drive->name);
+		goto failed;
+	}
+	if (strstr(drive->id->model, "OnStream DI-")) {
+		printk(KERN_WARNING "ide-tape: Use drive %s with ide-scsi emulation and osst.\n", drive->name);
+		printk(KERN_WARNING "ide-tape: OnStream support will be removed soon from ide-tape!\n");
+	}
+	tape = (idetape_tape_t *) kmalloc (sizeof (idetape_tape_t), GFP_KERNEL);
+	if (tape == NULL) {
+		printk(KERN_ERR "ide-tape: %s: Can't allocate a tape structure\n", drive->name);
+		goto failed;
+	}
+
+	g = alloc_disk(1 << PARTN_BITS);
+	if (!g)
+		goto out_free_tape;
+
+	ide_init_disk(g, drive);
+
+	if (ide_register_subdriver(drive, &idetape_driver)) {
+		printk(KERN_ERR "ide-tape: %s: Failed to register the driver with ide.c\n", drive->name);
+		goto out_put_disk;
+	}
+
+	memset(tape, 0, sizeof(*tape));
+
+	kref_init(&tape->kref);
+
+	tape->drive = drive;
+	tape->driver = &idetape_driver;
+	tape->disk = g;
+
+	g->private_data = &tape->driver;
+
+	drive->driver_data = tape;
+
+	down(&idetape_ref_sem);
+	for (minor = 0; idetape_devs[minor]; minor++)
+		;
+	idetape_devs[minor] = tape;
+	up(&idetape_ref_sem);
+
+	idetape_setup(drive, tape, minor);
+
+	devfs_mk_cdev(MKDEV(HWIF(drive)->major, minor),
+			S_IFCHR | S_IRUGO | S_IWUGO,
+			"%s/mt", drive->devfs_name);
+	devfs_mk_cdev(MKDEV(HWIF(drive)->major, minor + 128),
+			S_IFCHR | S_IRUGO | S_IWUGO,
+			"%s/mtn", drive->devfs_name);
+
+	g->number = devfs_register_tape(drive->devfs_name);
+	g->fops = &idetape_block_ops;
+	ide_register_region(g);
+
+	return 0;
+out_put_disk:
+	put_disk(g);
+out_free_tape:
+	kfree(tape);
+failed:
+	return 1;
+}
+
+MODULE_DESCRIPTION("ATAPI Streaming TAPE Driver");
+MODULE_LICENSE("GPL");
+
+static void __exit idetape_exit (void)
+{
+	ide_unregister_driver(&idetape_driver);
+	unregister_chrdev(IDETAPE_MAJOR, "ht");
+}
+
+/*
+ *	idetape_init will register the driver for each tape.
+ */
+static int idetape_init (void)
+{
+	if (register_chrdev(IDETAPE_MAJOR, "ht", &idetape_fops)) {
+		printk(KERN_ERR "ide-tape: Failed to register character device interface\n");
+		return -EBUSY;
+	}
+	ide_register_driver(&idetape_driver);
+	return 0;
+}
+
+module_init(idetape_init);
+module_exit(idetape_exit);
+MODULE_ALIAS_CHARDEV_MAJOR(IDETAPE_MAJOR);