[PATCH] CDRW packet writing support

This patch implements CDRW packet writing as a kernel block device.  Usage
instructions are in the packet-writing.txt file.

A hint: If you don't want to wait for a complete disc format, you can
format just a part of the disc.  For example:

        cdrwtool -d /dev/hdc -m 10240

This will format 10240 blocks, ie 20MB.
Signed-off-by: Peter Osterlund <petero2@telia.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Documentation/cdrom/00-INDEX

@@ -22,6 +22,8 @@ mcdx
 	- info on improved Mitsumi CD-ROM driver.
 optcd
 	- info on the Optics Storage 8000 AT CD-ROM driver
+packet-writing.txt
+	- Info on the CDRW packet writing module
 sbpcd
 	- info on the SoundBlaster/Panasonic CD-ROM interface driver.
 sjcd

Documentation/cdrom/packet-writing.txt

+Getting started quick
+---------------------
+
+- Select packet support in the block device section and UDF support in
+  the file system section.
+
+- Compile and install kernel and modules, reboot.
+
+- You need the udftools package (pktsetup, mkudffs, cdrwtool).
+  Download from http://sourceforge.net/projects/linux-udf/
+
+- Grab a new CD-RW disc and format it (assuming CD-RW is hdc, substitute
+  as appropriate):
+	# cdrwtool -d /dev/hdc -q
+
+- Setup your writer
+	# pktsetup dev_name /dev/hdc
+
+- Now you can mount /dev/pktcdvd/dev_name and copy files to it. Enjoy!
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD-RW media
+-------------------------------
+
+DVD-RW discs can be written to much like CD-RW discs if they are in
+the so called "restricted overwrite" mode. To put a disc in restricted
+overwrite mode, run:
+
+	# dvd+rw-format /dev/hdc
+
+You can then use the disc the same way you would use a CD-RW disc:
+
+	# pktsetup dev_name /dev/hdc
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Packet writing for DVD+RW media
+-------------------------------
+
+According to the DVD+RW specification, a drive supporting DVD+RW discs
+shall implement "true random writes with 2KB granularity", which means
+that it should be possible to put any filesystem with a block size >=
+2KB on such a disc. For example, it should be possible to do:
+
+	# mkudffs /dev/hdc
+	# mount /dev/hdc /cdrom -t udf -o rw,noatime
+
+However, some drives don't follow the specification and expect the
+host to perform aligned writes at 32KB boundaries. Other drives do
+follow the specification, but suffer bad performance problems if the
+writes are not 32KB aligned.
+
+Both problems can be solved by using the pktcdvd driver, which always
+generates aligned writes.
+
+	# pktsetup dev_name /dev/hdc
+	# mkudffs /dev/pktcdvd/dev_name
+	# mount /dev/pktcdvd/dev_name /cdrom -t udf -o rw,noatime
+
+
+Notes
+-----
+
+- CD-RW media can usually not be overwritten more than about 1000
+  times, so to avoid unnecessary wear on the media, you should always
+  use the noatime mount option.
+
+- Defect management (ie automatic remapping of bad sectors) has not
+  been implemented yet, so you are likely to get at least some
+  filesystem corruption if the disc wears out.
+
+- Since the pktcdvd driver makes the disc appear as a regular block
+  device with a 2KB block size, you can put any filesystem you like on
+  the disc. For example, run:
+
+	# /sbin/mke2fs /dev/pktcdvd/dev_name
+
+  to create an ext2 filesystem on the disc.
+
+
+Links
+-----
+
+See http://fy.chalmers.se/~appro/linux/DVD+RW/ for more information
+about DVD writing.

drivers/block/Kconfig

@@ -356,6 +356,39 @@ config LBD
 	  your machine, or if you want to have a raid or loopback device
 	  bigger than 2TB.  Otherwise say N.
 
+config CDROM_PKTCDVD
+	tristate "Packet writing on CD/DVD media"
+	help
+	  If you have a CDROM drive that supports packet writing, say Y to
+	  include preliminary support. It should work with any MMC/Mt Fuji
+	  compliant ATAPI or SCSI drive, which is just about any newer CD
+	  writer.
+
+	  Currently only writing to CD-RW, DVD-RW and DVD+RW discs is possible.
+	  DVD-RW disks must be in restricted overwrite mode.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called pktcdvd.
+
+config CDROM_PKTCDVD_BUFFERS
+	int "Free buffers for data gathering"
+	depends on CDROM_PKTCDVD
+	default "8"
+	help
+	  This controls the maximum number of active concurrent packets. More
+	  concurrent packets can increase write performance, but also require
+	  more memory. Each concurrent packet will require approximately 64Kb
+	  of non-swappable kernel memory, memory which will be allocated at
+	  pktsetup time.
+
+config CDROM_PKTCDVD_WCACHE
+	bool "Enable write caching"
+	depends on CDROM_PKTCDVD
+	help
+	  If enabled, write caching will be set for the CD-R/W device. For now
+	  this option is dangerous unless the CD-RW media is known good, as we
+	  don't do deferred write error handling yet.
+
 source "drivers/s390/block/Kconfig"
 
 endmenu

drivers/block/Makefile

@@ -35,6 +35,7 @@ obj-$(CONFIG_BLK_DEV_XD)	+= xd.o
 obj-$(CONFIG_BLK_CPQ_DA)	+= cpqarray.o
 obj-$(CONFIG_BLK_CPQ_CISS_DA)  += cciss.o
 obj-$(CONFIG_BLK_DEV_DAC960)	+= DAC960.o
+obj-$(CONFIG_CDROM_PKTCDVD)	+= pktcdvd.o
 
 obj-$(CONFIG_BLK_DEV_UMEM)	+= umem.o
 obj-$(CONFIG_BLK_DEV_NBD)	+= nbd.o

drivers/cdrom/Makefile

@@ -8,6 +8,7 @@
 obj-$(CONFIG_BLK_DEV_IDECD)	+=              cdrom.o
 obj-$(CONFIG_BLK_DEV_SR)	+=              cdrom.o
 obj-$(CONFIG_PARIDE_PCD)	+=		cdrom.o
+obj-$(CONFIG_CDROM_PKTCDVD)	+=		cdrom.o
 
 obj-$(CONFIG_AZTCD)		+= aztcd.o
 obj-$(CONFIG_CDU31A)		+= cdu31a.o     cdrom.o

drivers/ide/ide-cd.c

@@ -2001,7 +2001,7 @@ ide_do_rw_cdrom (ide_drive_t *drive, struct request *rq, sector_t block)
 			}
 			CDROM_CONFIG_FLAGS(drive)->seeking = 0;
 		}
-		if (IDE_LARGE_SEEK(info->last_block, block, IDECD_SEEK_THRESHOLD) && drive->dsc_overlap) {
+		if ((rq_data_dir(rq) == READ) && IDE_LARGE_SEEK(info->last_block, block, IDECD_SEEK_THRESHOLD) && drive->dsc_overlap) {
 			action = cdrom_start_seek(drive, block);
 		} else {
 			if (rq_data_dir(rq) == READ)
@@ -2962,8 +2962,10 @@ int ide_cdrom_probe_capabilities (ide_drive_t *drive)
 		CDROM_CONFIG_FLAGS(drive)->no_eject = 0;
 	if (cap.cd_r_write)
 		CDROM_CONFIG_FLAGS(drive)->cd_r = 1;
-	if (cap.cd_rw_write)
+	if (cap.cd_rw_write) {
 		CDROM_CONFIG_FLAGS(drive)->cd_rw = 1;
+		CDROM_CONFIG_FLAGS(drive)->ram = 1;
+	}
 	if (cap.test_write)
 		CDROM_CONFIG_FLAGS(drive)->test_write = 1;
 	if (cap.dvd_ram_read || cap.dvd_r_read || cap.dvd_rom)

drivers/scsi/sr.c

@@ -876,10 +876,10 @@ static void get_capabilities(struct scsi_cd *cd)
 		cd->cdi.mask |= CDC_CLOSE_TRAY; */
 
 	/*
-	 * if DVD-RAM of MRW-W, we are randomly writeable
+	 * if DVD-RAM, MRW-W or CD-RW, we are randomly writable
 	 */
-	if ((cd->cdi.mask & (CDC_DVD_RAM | CDC_MRW_W | CDC_RAM)) !=
-			(CDC_DVD_RAM | CDC_MRW_W | CDC_RAM)) {
+	if ((cd->cdi.mask & (CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) !=
+			(CDC_DVD_RAM | CDC_MRW_W | CDC_RAM | CDC_CD_RW)) {
 		cd->device->writeable = 1;
 	}
 

fs/compat_ioctl.c

@@ -115,6 +115,7 @@
 #include <linux/random.h>
 #include <linux/filter.h>
 #include <linux/msdos_fs.h>
+#include <linux/pktcdvd.h>
 
 #include <linux/hiddev.h>
 

include/linux/cdrom.h

@@ -499,6 +499,7 @@ struct cdrom_generic_command
 #define GPMODE_VENDOR_PAGE		0x00
 #define GPMODE_R_W_ERROR_PAGE		0x01
 #define GPMODE_WRITE_PARMS_PAGE		0x05
+#define GPMODE_WCACHING_PAGE		0x08
 #define GPMODE_AUDIO_CTL_PAGE		0x0e
 #define GPMODE_POWER_PAGE		0x1a
 #define GPMODE_FAULT_FAIL_PAGE		0x1c

include/linux/compat_ioctl.h

@@ -382,6 +382,8 @@ COMPATIBLE_IOCTL(CDROMREADALL)
 COMPATIBLE_IOCTL(DVD_READ_STRUCT)
 COMPATIBLE_IOCTL(DVD_WRITE_STRUCT)
 COMPATIBLE_IOCTL(DVD_AUTH)
+/* pktcdvd */
+COMPATIBLE_IOCTL(PACKET_CTRL_CMD)
 /* Big L */
 ULONG_IOCTL(LOOP_SET_FD)
 ULONG_IOCTL(LOOP_CHANGE_FD)

include/linux/pktcdvd.h

+/*
+ * Copyright (C) 2000 Jens Axboe <axboe@suse.de>
+ * Copyright (C) 2001-2004 Peter Osterlund <petero2@telia.com>
+ *
+ * May be copied or modified under the terms of the GNU General Public
+ * License.  See linux/COPYING for more information.
+ *
+ * Packet writing layer for ATAPI and SCSI CD-R, CD-RW, DVD-R, and
+ * DVD-RW devices.
+ *
+ */
+#ifndef __PKTCDVD_H
+#define __PKTCDVD_H
+
+#include <linux/types.h>
+
+/*
+ * 1 for normal debug messages, 2 is very verbose. 0 to turn it off.
+ */
+#define PACKET_DEBUG		1
+
+#define	MAX_WRITERS		8
+
+#define PKT_RB_POOL_SIZE	512
+
+/*
+ * How long we should hold a non-full packet before starting data gathering.
+ */
+#define PACKET_WAIT_TIME	(HZ * 5 / 1000)
+
+/*
+ * use drive write caching -- we need deferred error handling to be
+ * able to sucessfully recover with this option (drive will return good
+ * status as soon as the cdb is validated).
+ */
+#if defined(CONFIG_CDROM_PKTCDVD_WCACHE)
+#define USE_WCACHING		1
+#else
+#define USE_WCACHING		0
+#endif
+
+/*
+ * No user-servicable parts beyond this point ->
+ */
+
+/*
+ * device types
+ */
+#define PACKET_CDR		1
+#define	PACKET_CDRW		2
+#define PACKET_DVDR		3
+#define PACKET_DVDRW		4
+
+/*
+ * flags
+ */
+#define PACKET_WRITABLE		1	/* pd is writable */
+#define PACKET_NWA_VALID	2	/* next writable address valid */
+#define PACKET_LRA_VALID	3	/* last recorded address valid */
+#define PACKET_MERGE_SEGS	4	/* perform segment merging to keep */
+					/* underlying cdrom device happy */
+
+/*
+ * Disc status -- from READ_DISC_INFO
+ */
+#define PACKET_DISC_EMPTY	0
+#define PACKET_DISC_INCOMPLETE	1
+#define PACKET_DISC_COMPLETE	2
+#define PACKET_DISC_OTHER	3
+
+/*
+ * write type, and corresponding data block type
+ */
+#define PACKET_MODE1		1
+#define PACKET_MODE2		2
+#define PACKET_BLOCK_MODE1	8
+#define PACKET_BLOCK_MODE2	10
+
+/*
+ * Last session/border status
+ */
+#define PACKET_SESSION_EMPTY		0
+#define PACKET_SESSION_INCOMPLETE	1
+#define PACKET_SESSION_RESERVED		2
+#define PACKET_SESSION_COMPLETE		3
+
+#define PACKET_MCN			"4a656e734178626f65323030300000"
+
+#undef PACKET_USE_LS
+
+#define PKT_CTRL_CMD_SETUP	0
+#define PKT_CTRL_CMD_TEARDOWN	1
+#define PKT_CTRL_CMD_STATUS	2
+
+struct pkt_ctrl_command {
+	__u32 command;				/* in: Setup, teardown, status */
+	__u32 dev_index;			/* in/out: Device index */
+	__u32 dev;				/* in/out: Device nr for cdrw device */
+	__u32 pkt_dev;				/* in/out: Device nr for packet device */
+	__u32 num_devices;			/* out: Largest device index + 1 */
+	__u32 padding;				/* Not used */
+};
+
+/*
+ * packet ioctls
+ */
+#define PACKET_IOCTL_MAGIC	('X')
+#define PACKET_CTRL_CMD		_IOWR(PACKET_IOCTL_MAGIC, 1, struct pkt_ctrl_command)
+
+#ifdef __KERNEL__
+#include <linux/blkdev.h>
+#include <linux/completion.h>
+#include <linux/cdrom.h>
+
+struct packet_settings
+{
+	__u8			size;		/* packet size in (512 byte) sectors */
+	__u8			fp;		/* fixed packets */
+	__u8			link_loss;	/* the rest is specified
+						 * as per Mt Fuji */
+	__u8			write_type;
+	__u8			track_mode;
+	__u8			block_mode;
+};
+
+/*
+ * Very crude stats for now
+ */
+struct packet_stats
+{
+	unsigned long		pkt_started;
+	unsigned long		pkt_ended;
+	unsigned long		secs_w;
+	unsigned long		secs_rg;
+	unsigned long		secs_r;
+};
+
+struct packet_cdrw
+{
+	struct list_head	pkt_free_list;
+	struct list_head	pkt_active_list;
+	spinlock_t		active_list_lock; /* Serialize access to pkt_active_list */
+	struct task_struct	*thread;
+	atomic_t		pending_bios;
+};
+
+/*
+ * Switch to high speed reading after reading this many kilobytes
+ * with no interspersed writes.
+ */
+#define HI_SPEED_SWITCH 512
+
+struct packet_iosched
+{
+	atomic_t		attention;	/* Set to non-zero when queue processing is needed */
+	int			writing;	/* Non-zero when writing, zero when reading */
+	spinlock_t		lock;		/* Protecting read/write queue manipulations */
+	struct bio		*read_queue;
+	struct bio		*read_queue_tail;
+	struct bio		*write_queue;
+	struct bio		*write_queue_tail;
+	int			high_prio_read;	/* An important read request has been queued */
+	int			successive_reads;
+};
+
+/*
+ * 32 buffers of 2048 bytes
+ */
+#define PACKET_MAX_SIZE		32
+#define PAGES_PER_PACKET	(PACKET_MAX_SIZE * CD_FRAMESIZE / PAGE_SIZE)
+#define PACKET_MAX_SECTORS	(PACKET_MAX_SIZE * CD_FRAMESIZE >> 9)
+
+enum packet_data_state {
+	PACKET_IDLE_STATE,			/* Not used at the moment */
+	PACKET_WAITING_STATE,			/* Waiting for more bios to arrive, so */
+						/* we don't have to do as much */
+						/* data gathering */
+	PACKET_READ_WAIT_STATE,			/* Waiting for reads to fill in holes */
+	PACKET_WRITE_WAIT_STATE,		/* Waiting for the write to complete */
+	PACKET_RECOVERY_STATE,			/* Recover after read/write errors */
+	PACKET_FINISHED_STATE,			/* After write has finished */
+
+	PACKET_NUM_STATES			/* Number of possible states */
+};
+
+/*
+ * Information needed for writing a single packet
+ */
+struct pktcdvd_device;
+
+struct packet_data
+{
+	struct list_head	list;
+
+	spinlock_t		lock;		/* Lock protecting state transitions and */
+						/* orig_bios list */
+
+	struct bio		*orig_bios;	/* Original bios passed to pkt_make_request */
+	struct bio		*orig_bios_tail;/* that will be handled by this packet */
+	int			write_size;	/* Total size of all bios in the orig_bios */
+						/* list, measured in number of frames */
+
+	struct bio		*w_bio;		/* The bio we will send to the real CD */
+						/* device once we have all data for the */
+						/* packet we are going to write */
+	sector_t		sector;		/* First sector in this packet */
+	int			frames;		/* Number of frames in this packet */
+
+	enum packet_data_state	state;		/* Current state */
+	atomic_t		run_sm;		/* Incremented whenever the state */
+						/* machine needs to be run */
+	long			sleep_time;	/* Set this to non-zero to make the state */
+						/* machine run after this many jiffies. */
+
+	atomic_t		io_wait;	/* Number of pending IO operations */
+	atomic_t		io_errors;	/* Number of read/write errors during IO */
+
+	struct bio		*r_bios[PACKET_MAX_SIZE]; /* bios to use during data gathering */
+	struct page		*pages[PAGES_PER_PACKET];
+
+	int			cache_valid;	/* If non-zero, the data for the zone defined */
+						/* by the sector variable is completely cached */
+						/* in the pages[] vector. */
+
+	int			id;		/* ID number for debugging */
+	struct pktcdvd_device	*pd;
+};
+
+struct pkt_rb_node {
+	struct rb_node		rb_node;
+	struct bio		*bio;
+};
+
+struct packet_stacked_data
+{
+	struct bio		*bio;		/* Original read request bio */
+	struct pktcdvd_device	*pd;
+};
+#define PSD_POOL_SIZE		64
+
+struct pktcdvd_device
+{
+	struct block_device	*bdev;		/* dev attached */
+	dev_t			pkt_dev;	/* our dev */
+	char			name[20];
+	struct packet_settings	settings;
+	struct packet_stats	stats;
+	int			refcnt;		/* Open count */
+	int			write_speed;	/* current write speed, kB/s */
+	int			read_speed;	/* current read speed, kB/s */
+	unsigned long		offset;		/* start offset */
+	__u8			mode_offset;	/* 0 / 8 */
+	__u8			type;
+	unsigned long		flags;
+	__u16			mmc3_profile;
+	__u32			nwa;		/* next writable address */
+	__u32			lra;		/* last recorded address */
+	struct packet_cdrw	cdrw;
+	wait_queue_head_t	wqueue;
+
+	spinlock_t		lock;		/* Serialize access to bio_queue */
+	struct rb_root		bio_queue;	/* Work queue of bios we need to handle */
+	int			bio_queue_size;	/* Number of nodes in bio_queue */
+	sector_t		current_sector;	/* Keep track of where the elevator is */
+	atomic_t		scan_queue;	/* Set to non-zero when pkt_handle_queue */
+						/* needs to be run. */
+	mempool_t		*rb_pool;	/* mempool for pkt_rb_node allocations */
+
+	struct packet_iosched   iosched;
+	struct gendisk		*disk;
+};
+
+#endif /* __KERNEL__ */
+
+#endif /* __PKTCDVD_H */