Merge tag 'block-2023-01-06' of git://git.kernel.dk/linux

Pull block fixes from Jens Axboe:
 "The big change here is obviously the revert of the pktcdvd driver
  removal. Outside of that, just minor tweaks. In detail:

   - Re-instate the pktcdvd driver, which necessitates adding back
     bio_copy_data_iter() and the fops->devnode() hook for now (me)

   - Fix for splitting of a bio marked as NOWAIT, causing either nowait
     reads or writes to error with EAGAIN even if parts of the IO
     completed (me)

   - Fix for ublk, punting management commands to io-wq as they can all
     easily block for extended periods of time (Ming)

   - Removal of SRCU dependency for the block layer (Paul)"

* tag 'block-2023-01-06' of git://git.kernel.dk/linux:
  block: Remove "select SRCU"
  Revert "pktcdvd: remove driver."
  Revert "block: remove devnode callback from struct block_device_operations"
  Revert "block: bio_copy_data_iter"
  ublk: honor IO_URING_F_NONBLOCK for handling control command
  block: don't allow splitting of a REQ_NOWAIT bio
  block: handle bio_split_to_limits() NULL return

22 files changed, 3487 insertions, 18 deletions

diff --git a/Documentation/ABI/testing/debugfs-pktcdvd b/Documentation/ABI/testing/debugfs-pktcdvd
new file mode 100644
index 00000000000000..f6f65a4faea06c
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-pktcdvd
@@ -0,0 +1,18 @@
+What:           /sys/kernel/debug/pktcdvd/pktcdvd[0-7]
+Date:           Oct. 2006
+KernelVersion:  2.6.20
+Contact:        Thomas Maier <balagi@justmail.de>
+Description:
+
+The pktcdvd module (packet writing driver) creates
+these files in debugfs:
+
+/sys/kernel/debug/pktcdvd/pktcdvd[0-7]/
+
+    ====            ====== ====================================
+    info            0444   Lots of driver statistics and infos.
+    ====            ====== ====================================
+
+Example::
+
+    cat /sys/kernel/debug/pktcdvd/pktcdvd0/info
diff --git a/Documentation/ABI/testing/sysfs-class-pktcdvd b/Documentation/ABI/testing/sysfs-class-pktcdvd
new file mode 100644
index 00000000000000..ba1ce626591d9c
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-pktcdvd
@@ -0,0 +1,97 @@
+sysfs interface
+---------------
+The pktcdvd module (packet writing driver) creates the following files in the
+sysfs: (<devid> is in the format major:minor)
+
+What:		/sys/class/pktcdvd/add
+What:		/sys/class/pktcdvd/remove
+What:		/sys/class/pktcdvd/device_map
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+
+		==========	==============================================
+		add		(WO) Write a block device id (major:minor) to
+				create a new pktcdvd device and map it to the
+				block device.
+
+		remove		(WO) Write the pktcdvd device id (major:minor)
+				to remove the pktcdvd device.
+
+		device_map	(RO) Shows the device mapping in format:
+				pktcdvd[0-7] <pktdevid> <blkdevid>
+		==========	==============================================
+
+
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/dev
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/uevent
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+		dev:	(RO) Device id
+
+		uevent:	(WO) To send a uevent
+
+
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_started
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/packets_finished
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_written
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/kb_read_gather
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/stat/reset
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+		packets_started:	(RO) Number of started packets.
+
+		packets_finished:	(RO) Number of finished packets.
+
+		kb_written:		(RO) kBytes written.
+
+		kb_read:		(RO) kBytes read.
+
+		kb_read_gather:		(RO) kBytes read to fill write packets.
+
+		reset:			(WO) Write any value to it to reset
+					pktcdvd device statistic values, like
+					bytes read/written.
+
+
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/size
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_off
+What:		/sys/class/pktcdvd/pktcdvd[0-7]/write_queue/congestion_on
+Date:		Oct. 2006
+KernelVersion:	2.6.20
+Contact:	Thomas Maier <balagi@justmail.de>
+Description:
+		==============	================================================
+		size		(RO) Contains the size of the bio write queue.
+
+		congestion_off	(RW) If bio write queue size is below this mark,
+				accept new bio requests from the block layer.
+
+		congestion_on	(RW) If bio write queue size is higher as this
+				mark, do no longer accept bio write requests
+				from the block layer and wait till the pktcdvd
+				device has processed enough bio's so that bio
+				write queue size is below congestion off mark.
+				A value of <= 0 disables congestion control.
+		==============	================================================
+
+
+Example:
+--------
+To use the pktcdvd sysfs interface directly, you can do::
+
+    # create a new pktcdvd device mapped to /dev/hdc
+    echo "22:0" >/sys/class/pktcdvd/add
+    cat /sys/class/pktcdvd/device_map
+    # assuming device pktcdvd0 was created, look at stat's
+    cat /sys/class/pktcdvd/pktcdvd0/stat/kb_written
+    # print the device id of the mapped block device
+    fgrep pktcdvd0 /sys/class/pktcdvd/device_map
+    # remove device, using pktcdvd0 device id   253:0
+    echo "253:0" >/sys/class/pktcdvd/remove
diff --git a/MAINTAINERS b/MAINTAINERS
index ea941dc469fa1f..a36df9ed283d39 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -16610,6 +16610,13 @@ S:	Supported
 F:	Documentation/devicetree/bindings/input/pine64,pinephone-keyboard.yaml
 F:	drivers/input/keyboard/pinephone-keyboard.c
 
+PKTCDVD DRIVER
+M:	linux-block@vger.kernel.org
+S:	Orphan
+F:	drivers/block/pktcdvd.c
+F:	include/linux/pktcdvd.h
+F:	include/uapi/linux/pktcdvd.h
+
 PLANTOWER PMS7003 AIR POLLUTION SENSOR DRIVER
 M:	Tomasz Duszynski <tduszyns@gmail.com>
 S:	Maintained
diff --git a/block/Kconfig b/block/Kconfig
index 444c5ab3b67e2f..5d9d9c84d51657 100644
--- a/block/Kconfig
+++ b/block/Kconfig
@@ -6,7 +6,6 @@ menuconfig BLOCK
        bool "Enable the block layer" if EXPERT
        default y
        select SBITMAP
-       select SRCU
        help
 	 Provide block layer support for the kernel.
 
diff --git a/block/bio.c b/block/bio.c
index 5f96fcae3f7549..ab59a491a883e3 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1401,6 +1401,27 @@ void __bio_advance(struct bio *bio, unsigned bytes)
 }
 EXPORT_SYMBOL(__bio_advance);
 
+void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
+			struct bio *src, struct bvec_iter *src_iter)
+{
+	while (src_iter->bi_size && dst_iter->bi_size) {
+		struct bio_vec src_bv = bio_iter_iovec(src, *src_iter);
+		struct bio_vec dst_bv = bio_iter_iovec(dst, *dst_iter);
+		unsigned int bytes = min(src_bv.bv_len, dst_bv.bv_len);
+		void *src_buf = bvec_kmap_local(&src_bv);
+		void *dst_buf = bvec_kmap_local(&dst_bv);
+
+		memcpy(dst_buf, src_buf, bytes);
+
+		kunmap_local(dst_buf);
+		kunmap_local(src_buf);
+
+		bio_advance_iter_single(src, src_iter, bytes);
+		bio_advance_iter_single(dst, dst_iter, bytes);
+	}
+}
+EXPORT_SYMBOL(bio_copy_data_iter);
+
 /**
  * bio_copy_data - copy contents of data buffers from one bio to another
  * @src: source bio
@@ -1414,21 +1435,7 @@ void bio_copy_data(struct bio *dst, struct bio *src)
 	struct bvec_iter src_iter = src->bi_iter;
 	struct bvec_iter dst_iter = dst->bi_iter;
 
-	while (src_iter.bi_size && dst_iter.bi_size) {
-		struct bio_vec src_bv = bio_iter_iovec(src, src_iter);
-		struct bio_vec dst_bv = bio_iter_iovec(dst, dst_iter);
-		unsigned int bytes = min(src_bv.bv_len, dst_bv.bv_len);
-		void *src_buf = bvec_kmap_local(&src_bv);
-		void *dst_buf = bvec_kmap_local(&dst_bv);
-
-		memcpy(dst_buf, src_buf, bytes);
-
-		kunmap_local(dst_buf);
-		kunmap_local(src_buf);
-
-		bio_advance_iter_single(src, &src_iter, bytes);
-		bio_advance_iter_single(dst, &dst_iter, bytes);
-	}
+	bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
 }
 EXPORT_SYMBOL(bio_copy_data);
 
diff --git a/block/blk-merge.c b/block/blk-merge.c
index 35a8f75cc45d1c..b7c193d67185de 100644
--- a/block/blk-merge.c
+++ b/block/blk-merge.c
@@ -309,6 +309,16 @@ static struct bio *bio_split_rw(struct bio *bio, const struct queue_limits *lim,
 	*segs = nsegs;
 	return NULL;
 split:
+	/*
+	 * We can't sanely support splitting for a REQ_NOWAIT bio. End it
+	 * with EAGAIN if splitting is required and return an error pointer.
+	 */
+	if (bio->bi_opf & REQ_NOWAIT) {
+		bio->bi_status = BLK_STS_AGAIN;
+		bio_endio(bio);
+		return ERR_PTR(-EAGAIN);
+	}
+
 	*segs = nsegs;
 
 	/*
@@ -358,11 +368,13 @@ struct bio *__bio_split_to_limits(struct bio *bio,
 	default:
 		split = bio_split_rw(bio, lim, nr_segs, bs,
 				get_max_io_size(bio, lim) << SECTOR_SHIFT);
+		if (IS_ERR(split))
+			return NULL;
 		break;
 	}
 
 	if (split) {
-		/* there isn't chance to merge the splitted bio */
+		/* there isn't chance to merge the split bio */
 		split->bi_opf |= REQ_NOMERGE;
 
 		blkcg_bio_issue_init(split);
diff --git a/block/blk-mq.c b/block/blk-mq.c
index c5cf0dbca1db8d..2c49b4151da15d 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2951,8 +2951,11 @@ void blk_mq_submit_bio(struct bio *bio)
 	blk_status_t ret;
 
 	bio = blk_queue_bounce(bio, q);
-	if (bio_may_exceed_limits(bio, &q->limits))
+	if (bio_may_exceed_limits(bio, &q->limits)) {
 		bio = __bio_split_to_limits(bio, &q->limits, &nr_segs);
+		if (!bio)
+			return;
+	}
 
 	if (!bio_integrity_prep(bio))
 		return;
diff --git a/block/genhd.c b/block/genhd.c
index ab3cbe44196f77..23cf83b3331cde 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1201,10 +1201,21 @@ struct class block_class = {
 	.dev_uevent	= block_uevent,
 };
 
+static char *block_devnode(struct device *dev, umode_t *mode,
+			   kuid_t *uid, kgid_t *gid)
+{
+	struct gendisk *disk = dev_to_disk(dev);
+
+	if (disk->fops->devnode)
+		return disk->fops->devnode(disk, mode);
+	return NULL;
+}
+
 const struct device_type disk_type = {
 	.name		= "disk",
 	.groups		= disk_attr_groups,
 	.release	= disk_release,
+	.devnode	= block_devnode,
 };
 
 #ifdef CONFIG_PROC_FS
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index a2184b42849361..a41145d52de942 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -285,6 +285,49 @@ config BLK_DEV_RAM_SIZE
 	  The default value is 4096 kilobytes. Only change this if you know
 	  what you are doing.
 
+config CDROM_PKTCDVD
+	tristate "Packet writing on CD/DVD media (DEPRECATED)"
+	depends on !UML
+	depends on SCSI
+	select CDROM
+	help
+	  Note: This driver is deprecated and will be removed from the
+	  kernel in the near future!
+
+	  If you have a CDROM/DVD drive that supports packet writing, say
+	  Y to include support. It should work with any MMC/Mt Fuji
+	  compliant ATAPI or SCSI drive, which is just about any newer
+	  DVD/CD writer.
+
+	  Currently only writing to CD-RW, DVD-RW, DVD+RW and DVDRAM discs
+	  is possible.
+	  DVD-RW disks must be in restricted overwrite mode.
+
+	  See the file <file:Documentation/cdrom/packet-writing.rst>
+	  for further information on the use of this driver.
+
+	  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 when
+	  a disc is opened for writing.
+
+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.
+
 config ATA_OVER_ETH
 	tristate "ATA over Ethernet support"
 	depends on NET
diff --git a/drivers/block/Makefile b/drivers/block/Makefile
index 962ee65d8ca303..101612cba303a3 100644
--- a/drivers/block/Makefile
+++ b/drivers/block/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_AMIGA_Z2RAM)	+= z2ram.o
 obj-$(CONFIG_N64CART)		+= n64cart.o
 obj-$(CONFIG_BLK_DEV_RAM)	+= brd.o
 obj-$(CONFIG_BLK_DEV_LOOP)	+= loop.o
+obj-$(CONFIG_CDROM_PKTCDVD)	+= pktcdvd.o
 obj-$(CONFIG_SUNVDC)		+= sunvdc.o
 
 obj-$(CONFIG_BLK_DEV_NBD)	+= nbd.o
diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index eb14ec8ec04cfc..e36216d50753c8 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1607,6 +1607,8 @@ void drbd_submit_bio(struct bio *bio)
 	struct drbd_device *device = bio->bi_bdev->bd_disk->private_data;
 
 	bio = bio_split_to_limits(bio);
+	if (!bio)
+		return;
 
 	/*
 	 * what we "blindly" assume:
diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
new file mode 100644
index 00000000000000..4cea3b08087ed0
--- /dev/null
+++ b/drivers/block/pktcdvd.c
@@ -0,0 +1,2944 @@
+/*
+ * Copyright (C) 2000 Jens Axboe <axboe@suse.de>
+ * Copyright (C) 2001-2004 Peter Osterlund <petero2@telia.com>
+ * Copyright (C) 2006 Thomas Maier <balagi@justmail.de>
+ *
+ * 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-RW, DVD+RW, DVD-RW and
+ * DVD-RAM devices.
+ *
+ * Theory of operation:
+ *
+ * At the lowest level, there is the standard driver for the CD/DVD device,
+ * such as drivers/scsi/sr.c. This driver can handle read and write requests,
+ * but it doesn't know anything about the special restrictions that apply to
+ * packet writing. One restriction is that write requests must be aligned to
+ * packet boundaries on the physical media, and the size of a write request
+ * must be equal to the packet size. Another restriction is that a
+ * GPCMD_FLUSH_CACHE command has to be issued to the drive before a read
+ * command, if the previous command was a write.
+ *
+ * The purpose of the packet writing driver is to hide these restrictions from
+ * higher layers, such as file systems, and present a block device that can be
+ * randomly read and written using 2kB-sized blocks.
+ *
+ * The lowest layer in the packet writing driver is the packet I/O scheduler.
+ * Its data is defined by the struct packet_iosched and includes two bio
+ * queues with pending read and write requests. These queues are processed
+ * by the pkt_iosched_process_queue() function. The write requests in this
+ * queue are already properly aligned and sized. This layer is responsible for
+ * issuing the flush cache commands and scheduling the I/O in a good order.
+ *
+ * The next layer transforms unaligned write requests to aligned writes. This
+ * transformation requires reading missing pieces of data from the underlying
+ * block device, assembling the pieces to full packets and queuing them to the
+ * packet I/O scheduler.
+ *
+ * At the top layer there is a custom ->submit_bio function that forwards
+ * read requests directly to the iosched queue and puts write requests in the
+ * unaligned write queue. A kernel thread performs the necessary read
+ * gathering to convert the unaligned writes to aligned writes and then feeds
+ * them to the packet I/O scheduler.
+ *
+ *************************************************************************/
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/pktcdvd.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/compat.h>
+#include <linux/kthread.h>
+#include <linux/errno.h>
+#include <linux/spinlock.h>
+#include <linux/file.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/miscdevice.h>
+#include <linux/freezer.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/backing-dev.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_ioctl.h>
+#include <scsi/scsi.h>
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/nospec.h>
+#include <linux/uaccess.h>
+
+#define DRIVER_NAME	"pktcdvd"
+
+#define pkt_err(pd, fmt, ...)						\
+	pr_err("%s: " fmt, pd->name, ##__VA_ARGS__)
+#define pkt_notice(pd, fmt, ...)					\
+	pr_notice("%s: " fmt, pd->name, ##__VA_ARGS__)
+#define pkt_info(pd, fmt, ...)						\
+	pr_info("%s: " fmt, pd->name, ##__VA_ARGS__)
+
+#define pkt_dbg(level, pd, fmt, ...)					\
+do {									\
+	if (level == 2 && PACKET_DEBUG >= 2)				\
+		pr_notice("%s: %s():" fmt,				\
+			  pd->name, __func__, ##__VA_ARGS__);		\
+	else if (level == 1 && PACKET_DEBUG >= 1)			\
+		pr_notice("%s: " fmt, pd->name, ##__VA_ARGS__);		\
+} while (0)
+
+#define MAX_SPEED 0xffff
+
+static DEFINE_MUTEX(pktcdvd_mutex);
+static struct pktcdvd_device *pkt_devs[MAX_WRITERS];
+static struct proc_dir_entry *pkt_proc;
+static int pktdev_major;
+static int write_congestion_on  = PKT_WRITE_CONGESTION_ON;
+static int write_congestion_off = PKT_WRITE_CONGESTION_OFF;
+static struct mutex ctl_mutex;	/* Serialize open/close/setup/teardown */
+static mempool_t psd_pool;
+static struct bio_set pkt_bio_set;
+
+static struct class	*class_pktcdvd = NULL;    /* /sys/class/pktcdvd */
+static struct dentry	*pkt_debugfs_root = NULL; /* /sys/kernel/debug/pktcdvd */
+
+/* forward declaration */
+static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev);
+static int pkt_remove_dev(dev_t pkt_dev);
+static int pkt_seq_show(struct seq_file *m, void *p);
+
+static sector_t get_zone(sector_t sector, struct pktcdvd_device *pd)
+{
+	return (sector + pd->offset) & ~(sector_t)(pd->settings.size - 1);
+}
+
+/**********************************************************
+ * sysfs interface for pktcdvd
+ * by (C) 2006  Thomas Maier <balagi@justmail.de>
+ 
+  /sys/class/pktcdvd/pktcdvd[0-7]/
+                     stat/reset
+                     stat/packets_started
+                     stat/packets_finished
+                     stat/kb_written
+                     stat/kb_read
+                     stat/kb_read_gather
+                     write_queue/size
+                     write_queue/congestion_off
+                     write_queue/congestion_on
+ **********************************************************/
+
+static ssize_t packets_started_show(struct device *dev,
+				    struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%lu\n", pd->stats.pkt_started);
+}
+static DEVICE_ATTR_RO(packets_started);
+
+static ssize_t packets_finished_show(struct device *dev,
+				     struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%lu\n", pd->stats.pkt_ended);
+}
+static DEVICE_ATTR_RO(packets_finished);
+
+static ssize_t kb_written_show(struct device *dev,
+			       struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%lu\n", pd->stats.secs_w >> 1);
+}
+static DEVICE_ATTR_RO(kb_written);
+
+static ssize_t kb_read_show(struct device *dev,
+			    struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%lu\n", pd->stats.secs_r >> 1);
+}
+static DEVICE_ATTR_RO(kb_read);
+
+static ssize_t kb_read_gather_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+
+	return sysfs_emit(buf, "%lu\n", pd->stats.secs_rg >> 1);
+}
+static DEVICE_ATTR_RO(kb_read_gather);
+
+static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
+			   const char *buf, size_t len)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+
+	if (len > 0) {
+		pd->stats.pkt_started = 0;
+		pd->stats.pkt_ended = 0;
+		pd->stats.secs_w = 0;
+		pd->stats.secs_rg = 0;
+		pd->stats.secs_r = 0;
+	}
+	return len;
+}
+static DEVICE_ATTR_WO(reset);
+
+static struct attribute *pkt_stat_attrs[] = {
+	&dev_attr_packets_finished.attr,
+	&dev_attr_packets_started.attr,
+	&dev_attr_kb_read.attr,
+	&dev_attr_kb_written.attr,
+	&dev_attr_kb_read_gather.attr,
+	&dev_attr_reset.attr,
+	NULL,
+};
+
+static const struct attribute_group pkt_stat_group = {
+	.name = "stat",
+	.attrs = pkt_stat_attrs,
+};
+
+static ssize_t size_show(struct device *dev,
+			 struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+	int n;
+
+	spin_lock(&pd->lock);
+	n = sysfs_emit(buf, "%d\n", pd->bio_queue_size);
+	spin_unlock(&pd->lock);
+	return n;
+}
+static DEVICE_ATTR_RO(size);
+
+static void init_write_congestion_marks(int* lo, int* hi)
+{
+	if (*hi > 0) {
+		*hi = max(*hi, 500);
+		*hi = min(*hi, 1000000);
+		if (*lo <= 0)
+			*lo = *hi - 100;
+		else {
+			*lo = min(*lo, *hi - 100);
+			*lo = max(*lo, 100);
+		}
+	} else {
+		*hi = -1;
+		*lo = -1;
+	}
+}
+
+static ssize_t congestion_off_show(struct device *dev,
+				   struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+	int n;
+
+	spin_lock(&pd->lock);
+	n = sysfs_emit(buf, "%d\n", pd->write_congestion_off);
+	spin_unlock(&pd->lock);
+	return n;
+}
+
+static ssize_t congestion_off_store(struct device *dev,
+				    struct device_attribute *attr,
+				    const char *buf, size_t len)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+	int val;
+
+	if (sscanf(buf, "%d", &val) == 1) {
+		spin_lock(&pd->lock);
+		pd->write_congestion_off = val;
+		init_write_congestion_marks(&pd->write_congestion_off,
+					&pd->write_congestion_on);
+		spin_unlock(&pd->lock);
+	}
+	return len;
+}
+static DEVICE_ATTR_RW(congestion_off);
+
+static ssize_t congestion_on_show(struct device *dev,
+				  struct device_attribute *attr, char *buf)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+	int n;
+
+	spin_lock(&pd->lock);
+	n = sysfs_emit(buf, "%d\n", pd->write_congestion_on);
+	spin_unlock(&pd->lock);
+	return n;
+}
+
+static ssize_t congestion_on_store(struct device *dev,
+				   struct device_attribute *attr,
+				   const char *buf, size_t len)
+{
+	struct pktcdvd_device *pd = dev_get_drvdata(dev);
+	int val;
+
+	if (sscanf(buf, "%d", &val) == 1) {
+		spin_lock(&pd->lock);
+		pd->write_congestion_on = val;
+		init_write_congestion_marks(&pd->write_congestion_off,
+					&pd->write_congestion_on);
+		spin_unlock(&pd->lock);
+	}
+	return len;
+}
+static DEVICE_ATTR_RW(congestion_on);
+
+static struct attribute *pkt_wq_attrs[] = {
+	&dev_attr_congestion_on.attr,
+	&dev_attr_congestion_off.attr,
+	&dev_attr_size.attr,
+	NULL,
+};
+
+static const struct attribute_group pkt_wq_group = {
+	.name = "write_queue",
+	.attrs = pkt_wq_attrs,
+};
+
+static const struct attribute_group *pkt_groups[] = {
+	&pkt_stat_group,
+	&pkt_wq_group,
+	NULL,
+};
+
+static void pkt_sysfs_dev_new(struct pktcdvd_device *pd)
+{
+	if (class_pktcdvd) {
+		pd->dev = device_create_with_groups(class_pktcdvd, NULL,
+						    MKDEV(0, 0), pd, pkt_groups,
+						    "%s", pd->name);
+		if (IS_ERR(pd->dev))
+			pd->dev = NULL;
+	}
+}
+
+static void pkt_sysfs_dev_remove(struct pktcdvd_device *pd)
+{
+	if (class_pktcdvd)
+		device_unregister(pd->dev);
+}
+
+
+/********************************************************************
+  /sys/class/pktcdvd/
+                     add            map block device
+                     remove         unmap packet dev
+                     device_map     show mappings
+ *******************************************************************/
+
+static void class_pktcdvd_release(struct class *cls)
+{
+	kfree(cls);
+}
+
+static ssize_t device_map_show(struct class *c, struct class_attribute *attr,
+			       char *data)
+{
+	int n = 0;
+	int idx;
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+	for (idx = 0; idx < MAX_WRITERS; idx++) {
+		struct pktcdvd_device *pd = pkt_devs[idx];
+		if (!pd)
+			continue;
+		n += sprintf(data+n, "%s %u:%u %u:%u\n",
+			pd->name,
+			MAJOR(pd->pkt_dev), MINOR(pd->pkt_dev),
+			MAJOR(pd->bdev->bd_dev),
+			MINOR(pd->bdev->bd_dev));
+	}
+	mutex_unlock(&ctl_mutex);
+	return n;
+}
+static CLASS_ATTR_RO(device_map);
+
+static ssize_t add_store(struct class *c, struct class_attribute *attr,
+			 const char *buf, size_t count)
+{
+	unsigned int major, minor;
+
+	if (sscanf(buf, "%u:%u", &major, &minor) == 2) {
+		/* pkt_setup_dev() expects caller to hold reference to self */
+		if (!try_module_get(THIS_MODULE))
+			return -ENODEV;
+
+		pkt_setup_dev(MKDEV(major, minor), NULL);
+
+		module_put(THIS_MODULE);
+
+		return count;
+	}
+
+	return -EINVAL;
+}
+static CLASS_ATTR_WO(add);
+
+static ssize_t remove_store(struct class *c, struct class_attribute *attr,
+			    const char *buf, size_t count)
+{
+	unsigned int major, minor;
+	if (sscanf(buf, "%u:%u", &major, &minor) == 2) {
+		pkt_remove_dev(MKDEV(major, minor));
+		return count;
+	}
+	return -EINVAL;
+}
+static CLASS_ATTR_WO(remove);
+
+static struct attribute *class_pktcdvd_attrs[] = {
+	&class_attr_add.attr,
+	&class_attr_remove.attr,
+	&class_attr_device_map.attr,
+	NULL,
+};
+ATTRIBUTE_GROUPS(class_pktcdvd);
+
+static int pkt_sysfs_init(void)
+{
+	int ret = 0;
+
+	/*
+	 * create control files in sysfs
+	 * /sys/class/pktcdvd/...
+	 */
+	class_pktcdvd = kzalloc(sizeof(*class_pktcdvd), GFP_KERNEL);
+	if (!class_pktcdvd)
+		return -ENOMEM;
+	class_pktcdvd->name = DRIVER_NAME;
+	class_pktcdvd->owner = THIS_MODULE;
+	class_pktcdvd->class_release = class_pktcdvd_release;
+	class_pktcdvd->class_groups = class_pktcdvd_groups;
+	ret = class_register(class_pktcdvd);
+	if (ret) {
+		kfree(class_pktcdvd);
+		class_pktcdvd = NULL;
+		pr_err("failed to create class pktcdvd\n");
+		return ret;
+	}
+	return 0;
+}
+
+static void pkt_sysfs_cleanup(void)
+{
+	if (class_pktcdvd)
+		class_destroy(class_pktcdvd);
+	class_pktcdvd = NULL;
+}
+
+/********************************************************************
+  entries in debugfs
+
+  /sys/kernel/debug/pktcdvd[0-7]/
+			info
+
+ *******************************************************************/
+
+static int pkt_debugfs_seq_show(struct seq_file *m, void *p)
+{
+	return pkt_seq_show(m, p);
+}
+
+static int pkt_debugfs_fops_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, pkt_debugfs_seq_show, inode->i_private);
+}
+
+static const struct file_operations debug_fops = {
+	.open		= pkt_debugfs_fops_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= single_release,
+	.owner		= THIS_MODULE,
+};
+
+static void pkt_debugfs_dev_new(struct pktcdvd_device *pd)
+{
+	if (!pkt_debugfs_root)
+		return;
+	pd->dfs_d_root = debugfs_create_dir(pd->name, pkt_debugfs_root);
+	if (!pd->dfs_d_root)
+		return;
+
+	pd->dfs_f_info = debugfs_create_file("info", 0444,
+					     pd->dfs_d_root, pd, &debug_fops);
+}
+
+static void pkt_debugfs_dev_remove(struct pktcdvd_device *pd)
+{
+	if (!pkt_debugfs_root)
+		return;
+	debugfs_remove(pd->dfs_f_info);
+	debugfs_remove(pd->dfs_d_root);
+	pd->dfs_f_info = NULL;
+	pd->dfs_d_root = NULL;
+}
+
+static void pkt_debugfs_init(void)
+{
+	pkt_debugfs_root = debugfs_create_dir(DRIVER_NAME, NULL);
+}
+
+static void pkt_debugfs_cleanup(void)
+{
+	debugfs_remove(pkt_debugfs_root);
+	pkt_debugfs_root = NULL;
+}
+
+/* ----------------------------------------------------------*/
+
+
+static void pkt_bio_finished(struct pktcdvd_device *pd)
+{
+	BUG_ON(atomic_read(&pd->cdrw.pending_bios) <= 0);
+	if (atomic_dec_and_test(&pd->cdrw.pending_bios)) {
+		pkt_dbg(2, pd, "queue empty\n");
+		atomic_set(&pd->iosched.attention, 1);
+		wake_up(&pd->wqueue);
+	}
+}
+
+/*
+ * Allocate a packet_data struct
+ */
+static struct packet_data *pkt_alloc_packet_data(int frames)
+{
+	int i;
+	struct packet_data *pkt;
+
+	pkt = kzalloc(sizeof(struct packet_data), GFP_KERNEL);
+	if (!pkt)
+		goto no_pkt;
+
+	pkt->frames = frames;
+	pkt->w_bio = bio_kmalloc(frames, GFP_KERNEL);
+	if (!pkt->w_bio)
+		goto no_bio;
+
+	for (i = 0; i < frames / FRAMES_PER_PAGE; i++) {
+		pkt->pages[i] = alloc_page(GFP_KERNEL|__GFP_ZERO);
+		if (!pkt->pages[i])
+			goto no_page;
+	}
+
+	spin_lock_init(&pkt->lock);
+	bio_list_init(&pkt->orig_bios);
+
+	for (i = 0; i < frames; i++) {
+		pkt->r_bios[i] = bio_kmalloc(1, GFP_KERNEL);
+		if (!pkt->r_bios[i])
+			goto no_rd_bio;
+	}
+
+	return pkt;
+
+no_rd_bio:
+	for (i = 0; i < frames; i++)
+		kfree(pkt->r_bios[i]);
+no_page:
+	for (i = 0; i < frames / FRAMES_PER_PAGE; i++)
+		if (pkt->pages[i])
+			__free_page(pkt->pages[i]);
+	kfree(pkt->w_bio);
+no_bio:
+	kfree(pkt);
+no_pkt:
+	return NULL;
+}
+
+/*
+ * Free a packet_data struct
+ */
+static void pkt_free_packet_data(struct packet_data *pkt)
+{
+	int i;
+
+	for (i = 0; i < pkt->frames; i++)
+		kfree(pkt->r_bios[i]);
+	for (i = 0; i < pkt->frames / FRAMES_PER_PAGE; i++)
+		__free_page(pkt->pages[i]);
+	kfree(pkt->w_bio);
+	kfree(pkt);
+}
+
+static void pkt_shrink_pktlist(struct pktcdvd_device *pd)
+{
+	struct packet_data *pkt, *next;
+
+	BUG_ON(!list_empty(&pd->cdrw.pkt_active_list));
+
+	list_for_each_entry_safe(pkt, next, &pd->cdrw.pkt_free_list, list) {
+		pkt_free_packet_data(pkt);
+	}
+	INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);
+}
+
+static int pkt_grow_pktlist(struct pktcdvd_device *pd, int nr_packets)
+{
+	struct packet_data *pkt;
+
+	BUG_ON(!list_empty(&pd->cdrw.pkt_free_list));
+
+	while (nr_packets > 0) {
+		pkt = pkt_alloc_packet_data(pd->settings.size >> 2);
+		if (!pkt) {
+			pkt_shrink_pktlist(pd);
+			return 0;
+		}
+		pkt->id = nr_packets;
+		pkt->pd = pd;
+		list_add(&pkt->list, &pd->cdrw.pkt_free_list);
+		nr_packets--;
+	}
+	return 1;
+}
+
+static inline struct pkt_rb_node *pkt_rbtree_next(struct pkt_rb_node *node)
+{
+	struct rb_node *n = rb_next(&node->rb_node);
+	if (!n)
+		return NULL;
+	return rb_entry(n, struct pkt_rb_node, rb_node);
+}
+
+static void pkt_rbtree_erase(struct pktcdvd_device *pd, struct pkt_rb_node *node)
+{
+	rb_erase(&node->rb_node, &pd->bio_queue);
+	mempool_free(node, &pd->rb_pool);
+	pd->bio_queue_size--;
+	BUG_ON(pd->bio_queue_size < 0);
+}
+
+/*
+ * Find the first node in the pd->bio_queue rb tree with a starting sector >= s.
+ */
+static struct pkt_rb_node *pkt_rbtree_find(struct pktcdvd_device *pd, sector_t s)
+{
+	struct rb_node *n = pd->bio_queue.rb_node;
+	struct rb_node *next;
+	struct pkt_rb_node *tmp;
+
+	if (!n) {
+		BUG_ON(pd->bio_queue_size > 0);
+		return NULL;
+	}
+
+	for (;;) {
+		tmp = rb_entry(n, struct pkt_rb_node, rb_node);
+		if (s <= tmp->bio->bi_iter.bi_sector)
+			next = n->rb_left;
+		else
+			next = n->rb_right;
+		if (!next)
+			break;
+		n = next;
+	}
+
+	if (s > tmp->bio->bi_iter.bi_sector) {
+		tmp = pkt_rbtree_next(tmp);
+		if (!tmp)
+			return NULL;
+	}
+	BUG_ON(s > tmp->bio->bi_iter.bi_sector);
+	return tmp;
+}
+
+/*
+ * Insert a node into the pd->bio_queue rb tree.
+ */
+static void pkt_rbtree_insert(struct pktcdvd_device *pd, struct pkt_rb_node *node)
+{
+	struct rb_node **p = &pd->bio_queue.rb_node;
+	struct rb_node *parent = NULL;
+	sector_t s = node->bio->bi_iter.bi_sector;
+	struct pkt_rb_node *tmp;
+
+	while (*p) {
+		parent = *p;
+		tmp = rb_entry(parent, struct pkt_rb_node, rb_node);
+		if (s < tmp->bio->bi_iter.bi_sector)
+			p = &(*p)->rb_left;
+		else
+			p = &(*p)->rb_right;
+	}
+	rb_link_node(&node->rb_node, parent, p);
+	rb_insert_color(&node->rb_node, &pd->bio_queue);
+	pd->bio_queue_size++;
+}
+
+/*
+ * Send a packet_command to the underlying block device and
+ * wait for completion.
+ */
+static int pkt_generic_packet(struct pktcdvd_device *pd, struct packet_command *cgc)
+{
+	struct request_queue *q = bdev_get_queue(pd->bdev);
+	struct scsi_cmnd *scmd;
+	struct request *rq;
+	int ret = 0;
+
+	rq = scsi_alloc_request(q, (cgc->data_direction == CGC_DATA_WRITE) ?
+			     REQ_OP_DRV_OUT : REQ_OP_DRV_IN, 0);
+	if (IS_ERR(rq))
+		return PTR_ERR(rq);
+	scmd = blk_mq_rq_to_pdu(rq);
+
+	if (cgc->buflen) {
+		ret = blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen,
+				      GFP_NOIO);
+		if (ret)
+			goto out;
+	}
+
+	scmd->cmd_len = COMMAND_SIZE(cgc->cmd[0]);
+	memcpy(scmd->cmnd, cgc->cmd, CDROM_PACKET_SIZE);
+
+	rq->timeout = 60*HZ;
+	if (cgc->quiet)
+		rq->rq_flags |= RQF_QUIET;
+
+	blk_execute_rq(rq, false);
+	if (scmd->result)
+		ret = -EIO;
+out:
+	blk_mq_free_request(rq);
+	return ret;
+}
+
+static const char *sense_key_string(__u8 index)
+{
+	static const char * const info[] = {
+		"No sense", "Recovered error", "Not ready",
+		"Medium error", "Hardware error", "Illegal request",
+		"Unit attention", "Data protect", "Blank check",
+	};
+
+	return index < ARRAY_SIZE(info) ? info[index] : "INVALID";
+}
+
+/*
+ * A generic sense dump / resolve mechanism should be implemented across
+ * all ATAPI + SCSI devices.
+ */
+static void pkt_dump_sense(struct pktcdvd_device *pd,
+			   struct packet_command *cgc)
+{
+	struct scsi_sense_hdr *sshdr = cgc->sshdr;
+
+	if (sshdr)
+		pkt_err(pd, "%*ph - sense %02x.%02x.%02x (%s)\n",
+			CDROM_PACKET_SIZE, cgc->cmd,
+			sshdr->sense_key, sshdr->asc, sshdr->ascq,
+			sense_key_string(sshdr->sense_key));
+	else
+		pkt_err(pd, "%*ph - no sense\n", CDROM_PACKET_SIZE, cgc->cmd);
+}
+
+/*
+ * flush the drive cache to media
+ */
+static int pkt_flush_cache(struct pktcdvd_device *pd)
+{
+	struct packet_command cgc;
+
+	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
+	cgc.cmd[0] = GPCMD_FLUSH_CACHE;
+	cgc.quiet = 1;
+
+	/*
+	 * the IMMED bit -- we default to not setting it, although that
+	 * would allow a much faster close, this is safer
+	 */
+#if 0
+	cgc.cmd[1] = 1 << 1;
+#endif
+	return pkt_generic_packet(pd, &cgc);
+}
+
+/*
+ * speed is given as the normal factor, e.g. 4 for 4x
+ */
+static noinline_for_stack int pkt_set_speed(struct pktcdvd_device *pd,
+				unsigned write_speed, unsigned read_speed)
+{
+	struct packet_command cgc;
+	struct scsi_sense_hdr sshdr;
+	int ret;
+
+	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
+	cgc.sshdr = &sshdr;
+	cgc.cmd[0] = GPCMD_SET_SPEED;
+	cgc.cmd[2] = (read_speed >> 8) & 0xff;
+	cgc.cmd[3] = read_speed & 0xff;
+	cgc.cmd[4] = (write_speed >> 8) & 0xff;
+	cgc.cmd[5] = write_speed & 0xff;
+
+	ret = pkt_generic_packet(pd, &cgc);
+	if (ret)
+		pkt_dump_sense(pd, &cgc);
+
+	return ret;
+}
+
+/*
+ * Queue a bio for processing by the low-level CD device. Must be called
+ * from process context.
+ */
+static void pkt_queue_bio(struct pktcdvd_device *pd, struct bio *bio)
+{
+	spin_lock(&pd->iosched.lock);
+	if (bio_data_dir(bio) == READ)
+		bio_list_add(&pd->iosched.read_queue, bio);
+	else
+		bio_list_add(&pd->iosched.write_queue, bio);
+	spin_unlock(&pd->iosched.lock);
+
+	atomic_set(&pd->iosched.attention, 1);
+	wake_up(&pd->wqueue);
+}
+
+/*
+ * Process the queued read/write requests. This function handles special
+ * requirements for CDRW drives:
+ * - A cache flush command must be inserted before a read request if the
+ *   previous request was a write.
+ * - Switching between reading and writing is slow, so don't do it more often
+ *   than necessary.
+ * - Optimize for throughput at the expense of latency. This means that streaming
+ *   writes will never be interrupted by a read, but if the drive has to seek
+ *   before the next write, switch to reading instead if there are any pending
+ *   read requests.
+ * - Set the read speed according to current usage pattern. When only reading
+ *   from the device, it's best to use the highest possible read speed, but
+ *   when switching often between reading and writing, it's better to have the
+ *   same read and write speeds.
+ */
+static void pkt_iosched_process_queue(struct pktcdvd_device *pd)
+{
+
+	if (atomic_read(&pd->iosched.attention) == 0)
+		return;
+	atomic_set(&pd->iosched.attention, 0);
+
+	for (;;) {
+		struct bio *bio;
+		int reads_queued, writes_queued;
+
+		spin_lock(&pd->iosched.lock);
+		reads_queued = !bio_list_empty(&pd->iosched.read_queue);
+		writes_queued = !bio_list_empty(&pd->iosched.write_queue);
+		spin_unlock(&pd->iosched.lock);
+
+		if (!reads_queued && !writes_queued)
+			break;
+
+		if (pd->iosched.writing) {
+			int need_write_seek = 1;
+			spin_lock(&pd->iosched.lock);
+			bio = bio_list_peek(&pd->iosched.write_queue);
+			spin_unlock(&pd->iosched.lock);
+			if (bio && (bio->bi_iter.bi_sector ==
+				    pd->iosched.last_write))
+				need_write_seek = 0;
+			if (need_write_seek && reads_queued) {
+				if (atomic_read(&pd->cdrw.pending_bios) > 0) {
+					pkt_dbg(2, pd, "write, waiting\n");
+					break;
+				}
+				pkt_flush_cache(pd);
+				pd->iosched.writing = 0;
+			}
+		} else {
+			if (!reads_queued && writes_queued) {
+				if (atomic_read(&pd->cdrw.pending_bios) > 0) {
+					pkt_dbg(2, pd, "read, waiting\n");
+					break;
+				}
+				pd->iosched.writing = 1;
+			}
+		}
+
+		spin_lock(&pd->iosched.lock);
+		if (pd->iosched.writing)
+			bio = bio_list_pop(&pd->iosched.write_queue);
+		else
+			bio = bio_list_pop(&pd->iosched.read_queue);
+		spin_unlock(&pd->iosched.lock);
+
+		if (!bio)
+			continue;
+
+		if (bio_data_dir(bio) == READ)
+			pd->iosched.successive_reads +=
+				bio->bi_iter.bi_size >> 10;
+		else {
+			pd->iosched.successive_reads = 0;
+			pd->iosched.last_write = bio_end_sector(bio);
+		}
+		if (pd->iosched.successive_reads >= HI_SPEED_SWITCH) {
+			if (pd->read_speed == pd->write_speed) {
+				pd->read_speed = MAX_SPEED;
+				pkt_set_speed(pd, pd->write_speed, pd->read_speed);
+			}
+		} else {
+			if (pd->read_speed != pd->write_speed) {
+				pd->read_speed = pd->write_speed;
+				pkt_set_speed(pd, pd->write_speed, pd->read_speed);
+			}
+		}
+
+		atomic_inc(&pd->cdrw.pending_bios);
+		submit_bio_noacct(bio);
+	}
+}
+
+/*
+ * Special care is needed if the underlying block device has a small
+ * max_phys_segments value.
+ */
+static int pkt_set_segment_merging(struct pktcdvd_device *pd, struct request_queue *q)
+{
+	if ((pd->settings.size << 9) / CD_FRAMESIZE
+	    <= queue_max_segments(q)) {
+		/*
+		 * The cdrom device can handle one segment/frame
+		 */
+		clear_bit(PACKET_MERGE_SEGS, &pd->flags);
+		return 0;
+	} else if ((pd->settings.size << 9) / PAGE_SIZE
+		   <= queue_max_segments(q)) {
+		/*
+		 * We can handle this case at the expense of some extra memory
+		 * copies during write operations
+		 */
+		set_bit(PACKET_MERGE_SEGS, &pd->flags);
+		return 0;
+	} else {
+		pkt_err(pd, "cdrom max_phys_segments too small\n");
+		return -EIO;
+	}
+}
+
+static void pkt_end_io_read(struct bio *bio)
+{
+	struct packet_data *pkt = bio->bi_private;
+	struct pktcdvd_device *pd = pkt->pd;
+	BUG_ON(!pd);
+
+	pkt_dbg(2, pd, "bio=%p sec0=%llx sec=%llx err=%d\n",
+		bio, (unsigned long long)pkt->sector,
+		(unsigned long long)bio->bi_iter.bi_sector, bio->bi_status);
+
+	if (bio->bi_status)
+		atomic_inc(&pkt->io_errors);
+	bio_uninit(bio);
+	if (atomic_dec_and_test(&pkt->io_wait)) {
+		atomic_inc(&pkt->run_sm);
+		wake_up(&pd->wqueue);
+	}
+	pkt_bio_finished(pd);
+}
+
+static void pkt_end_io_packet_write(struct bio *bio)
+{
+	struct packet_data *pkt = bio->bi_private;
+	struct pktcdvd_device *pd = pkt->pd;
+	BUG_ON(!pd);
+
+	pkt_dbg(2, pd, "id=%d, err=%d\n", pkt->id, bio->bi_status);
+
+	pd->stats.pkt_ended++;
+
+	bio_uninit(bio);
+	pkt_bio_finished(pd);
+	atomic_dec(&pkt->io_wait);
+	atomic_inc(&pkt->run_sm);
+	wake_up(&pd->wqueue);
+}
+
+/*
+ * Schedule reads for the holes in a packet
+ */
+static void pkt_gather_data(struct pktcdvd_device *pd, struct packet_data *pkt)
+{
+	int frames_read = 0;
+	struct bio *bio;
+	int f;
+	char written[PACKET_MAX_SIZE];
+
+	BUG_ON(bio_list_empty(&pkt->orig_bios));
+
+	atomic_set(&pkt->io_wait, 0);
+	atomic_set(&pkt->io_errors, 0);
+
+	/*
+	 * Figure out which frames we need to read before we can write.
+	 */
+	memset(written, 0, sizeof(written));
+	spin_lock(&pkt->lock);
+	bio_list_for_each(bio, &pkt->orig_bios) {
+		int first_frame = (bio->bi_iter.bi_sector - pkt->sector) /
+			(CD_FRAMESIZE >> 9);
+		int num_frames = bio->bi_iter.bi_size / CD_FRAMESIZE;
+		pd->stats.secs_w += num_frames * (CD_FRAMESIZE >> 9);
+		BUG_ON(first_frame < 0);
+		BUG_ON(first_frame + num_frames > pkt->frames);
+		for (f = first_frame; f < first_frame + num_frames; f++)
+			written[f] = 1;
+	}
+	spin_unlock(&pkt->lock);
+
+	if (pkt->cache_valid) {
+		pkt_dbg(2, pd, "zone %llx cached\n",
+			(unsigned long long)pkt->sector);
+		goto out_account;
+	}
+
+	/*
+	 * Schedule reads for missing parts of the packet.
+	 */
+	for (f = 0; f < pkt->frames; f++) {
+		int p, offset;
+
+		if (written[f])
+			continue;
+
+		bio = pkt->r_bios[f];
+		bio_init(bio, pd->bdev, bio->bi_inline_vecs, 1, REQ_OP_READ);
+		bio->bi_iter.bi_sector = pkt->sector + f * (CD_FRAMESIZE >> 9);
+		bio->bi_end_io = pkt_end_io_read;
+		bio->bi_private = pkt;
+
+		p = (f * CD_FRAMESIZE) / PAGE_SIZE;
+		offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
+		pkt_dbg(2, pd, "Adding frame %d, page:%p offs:%d\n",
+			f, pkt->pages[p], offset);
+		if (!bio_add_page(bio, pkt->pages[p], CD_FRAMESIZE, offset))
+			BUG();
+
+		atomic_inc(&pkt->io_wait);
+		pkt_queue_bio(pd, bio);
+		frames_read++;
+	}
+
+out_account:
+	pkt_dbg(2, pd, "need %d frames for zone %llx\n",
+		frames_read, (unsigned long long)pkt->sector);
+	pd->stats.pkt_started++;
+	pd->stats.secs_rg += frames_read * (CD_FRAMESIZE >> 9);
+}
+
+/*
+ * Find a packet matching zone, or the least recently used packet if
+ * there is no match.
+ */
+static struct packet_data *pkt_get_packet_data(struct pktcdvd_device *pd, int zone)
+{
+	struct packet_data *pkt;
+
+	list_for_each_entry(pkt, &pd->cdrw.pkt_free_list, list) {
+		if (pkt->sector == zone || pkt->list.next == &pd->cdrw.pkt_free_list) {
+			list_del_init(&pkt->list);
+			if (pkt->sector != zone)
+				pkt->cache_valid = 0;
+			return pkt;
+		}
+	}
+	BUG();
+	return NULL;
+}
+
+static void pkt_put_packet_data(struct pktcdvd_device *pd, struct packet_data *pkt)
+{
+	if (pkt->cache_valid) {
+		list_add(&pkt->list, &pd->cdrw.pkt_free_list);
+	} else {
+		list_add_tail(&pkt->list, &pd->cdrw.pkt_free_list);
+	}
+}
+
+static inline void pkt_set_state(struct packet_data *pkt, enum packet_data_state state)
+{
+#if PACKET_DEBUG > 1
+	static const char *state_name[] = {
+		"IDLE", "WAITING", "READ_WAIT", "WRITE_WAIT", "RECOVERY", "FINISHED"
+	};
+	enum packet_data_state old_state = pkt->state;
+	pkt_dbg(2, pd, "pkt %2d : s=%6llx %s -> %s\n",
+		pkt->id, (unsigned long long)pkt->sector,
+		state_name[old_state], state_name[state]);
+#endif
+	pkt->state = state;
+}
+
+/*
+ * Scan the work queue to see if we can start a new packet.
+ * returns non-zero if any work was done.
+ */
+static int pkt_handle_queue(struct pktcdvd_device *pd)
+{
+	struct packet_data *pkt, *p;
+	struct bio *bio = NULL;
+	sector_t zone = 0; /* Suppress gcc warning */
+	struct pkt_rb_node *node, *first_node;
+	struct rb_node *n;
+
+	atomic_set(&pd->scan_queue, 0);
+
+	if (list_empty(&pd->cdrw.pkt_free_list)) {
+		pkt_dbg(2, pd, "no pkt\n");
+		return 0;
+	}
+
+	/*
+	 * Try to find a zone we are not already working on.
+	 */
+	spin_lock(&pd->lock);
+	first_node = pkt_rbtree_find(pd, pd->current_sector);
+	if (!first_node) {
+		n = rb_first(&pd->bio_queue);
+		if (n)
+			first_node = rb_entry(n, struct pkt_rb_node, rb_node);
+	}
+	node = first_node;
+	while (node) {
+		bio = node->bio;
+		zone = get_zone(bio->bi_iter.bi_sector, pd);
+		list_for_each_entry(p, &pd->cdrw.pkt_active_list, list) {
+			if (p->sector == zone) {
+				bio = NULL;
+				goto try_next_bio;
+			}
+		}
+		break;
+try_next_bio:
+		node = pkt_rbtree_next(node);
+		if (!node) {
+			n = rb_first(&pd->bio_queue);
+			if (n)
+				node = rb_entry(n, struct pkt_rb_node, rb_node);
+		}
+		if (node == first_node)
+			node = NULL;
+	}
+	spin_unlock(&pd->lock);
+	if (!bio) {
+		pkt_dbg(2, pd, "no bio\n");
+		return 0;
+	}
+
+	pkt = pkt_get_packet_data(pd, zone);
+
+	pd->current_sector = zone + pd->settings.size;
+	pkt->sector = zone;
+	BUG_ON(pkt->frames != pd->settings.size >> 2);
+	pkt->write_size = 0;
+
+	/*
+	 * Scan work queue for bios in the same zone and link them
+	 * to this packet.
+	 */
+	spin_lock(&pd->lock);
+	pkt_dbg(2, pd, "looking for zone %llx\n", (unsigned long long)zone);
+	while ((node = pkt_rbtree_find(pd, zone)) != NULL) {
+		bio = node->bio;
+		pkt_dbg(2, pd, "found zone=%llx\n", (unsigned long long)
+			get_zone(bio->bi_iter.bi_sector, pd));
+		if (get_zone(bio->bi_iter.bi_sector, pd) != zone)
+			break;
+		pkt_rbtree_erase(pd, node);
+		spin_lock(&pkt->lock);
+		bio_list_add(&pkt->orig_bios, bio);
+		pkt->write_size += bio->bi_iter.bi_size / CD_FRAMESIZE;
+		spin_unlock(&pkt->lock);
+	}
+	/* check write congestion marks, and if bio_queue_size is
+	 * below, wake up any waiters
+	 */
+	if (pd->congested &&
+	    pd->bio_queue_size <= pd->write_congestion_off) {
+		pd->congested = false;
+		wake_up_var(&pd->congested);
+	}
+	spin_unlock(&pd->lock);
+
+	pkt->sleep_time = max(PACKET_WAIT_TIME, 1);
+	pkt_set_state(pkt, PACKET_WAITING_STATE);
+	atomic_set(&pkt->run_sm, 1);
+
+	spin_lock(&pd->cdrw.active_list_lock);
+	list_add(&pkt->list, &pd->cdrw.pkt_active_list);
+	spin_unlock(&pd->cdrw.active_list_lock);
+
+	return 1;
+}
+
+/**
+ * bio_list_copy_data - copy contents of data buffers from one chain of bios to
+ * another
+ * @src: source bio list
+ * @dst: destination bio list
+ *
+ * Stops when it reaches the end of either the @src list or @dst list - that is,
+ * copies min(src->bi_size, dst->bi_size) bytes (or the equivalent for lists of
+ * bios).
+ */
+static void bio_list_copy_data(struct bio *dst, struct bio *src)
+{
+	struct bvec_iter src_iter = src->bi_iter;
+	struct bvec_iter dst_iter = dst->bi_iter;
+
+	while (1) {
+		if (!src_iter.bi_size) {
+			src = src->bi_next;
+			if (!src)
+				break;
+
+			src_iter = src->bi_iter;
+		}
+
+		if (!dst_iter.bi_size) {
+			dst = dst->bi_next;
+			if (!dst)
+				break;
+
+			dst_iter = dst->bi_iter;
+		}
+
+		bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
+	}
+}
+
+/*
+ * Assemble a bio to write one packet and queue the bio for processing
+ * by the underlying block device.
+ */
+static void pkt_start_write(struct pktcdvd_device *pd, struct packet_data *pkt)
+{
+	int f;
+
+	bio_init(pkt->w_bio, pd->bdev, pkt->w_bio->bi_inline_vecs, pkt->frames,
+		 REQ_OP_WRITE);
+	pkt->w_bio->bi_iter.bi_sector = pkt->sector;
+	pkt->w_bio->bi_end_io = pkt_end_io_packet_write;
+	pkt->w_bio->bi_private = pkt;
+
+	/* XXX: locking? */
+	for (f = 0; f < pkt->frames; f++) {
+		struct page *page = pkt->pages[(f * CD_FRAMESIZE) / PAGE_SIZE];
+		unsigned offset = (f * CD_FRAMESIZE) % PAGE_SIZE;
+
+		if (!bio_add_page(pkt->w_bio, page, CD_FRAMESIZE, offset))
+			BUG();
+	}
+	pkt_dbg(2, pd, "vcnt=%d\n", pkt->w_bio->bi_vcnt);
+
+	/*
+	 * Fill-in bvec with data from orig_bios.
+	 */
+	spin_lock(&pkt->lock);
+	bio_list_copy_data(pkt->w_bio, pkt->orig_bios.head);
+
+	pkt_set_state(pkt, PACKET_WRITE_WAIT_STATE);
+	spin_unlock(&pkt->lock);
+
+	pkt_dbg(2, pd, "Writing %d frames for zone %llx\n",
+		pkt->write_size, (unsigned long long)pkt->sector);
+
+	if (test_bit(PACKET_MERGE_SEGS, &pd->flags) || (pkt->write_size < pkt->frames))
+		pkt->cache_valid = 1;
+	else
+		pkt->cache_valid = 0;
+
+	/* Start the write request */
+	atomic_set(&pkt->io_wait, 1);
+	pkt_queue_bio(pd, pkt->w_bio);
+}
+
+static void pkt_finish_packet(struct packet_data *pkt, blk_status_t status)
+{
+	struct bio *bio;
+
+	if (status)
+		pkt->cache_valid = 0;
+
+	/* Finish all bios corresponding to this packet */
+	while ((bio = bio_list_pop(&pkt->orig_bios))) {
+		bio->bi_status = status;
+		bio_endio(bio);
+	}
+}
+
+static void pkt_run_state_machine(struct pktcdvd_device *pd, struct packet_data *pkt)
+{
+	pkt_dbg(2, pd, "pkt %d\n", pkt->id);
+
+	for (;;) {
+		switch (pkt->state) {
+		case PACKET_WAITING_STATE:
+			if ((pkt->write_size < pkt->frames) && (pkt->sleep_time > 0))
+				return;
+
+			pkt->sleep_time = 0;
+			pkt_gather_data(pd, pkt);
+			pkt_set_state(pkt, PACKET_READ_WAIT_STATE);
+			break;
+
+		case PACKET_READ_WAIT_STATE:
+			if (atomic_read(&pkt->io_wait) > 0)
+				return;
+
+			if (atomic_read(&pkt->io_errors) > 0) {
+				pkt_set_state(pkt, PACKET_RECOVERY_STATE);
+			} else {
+				pkt_start_write(pd, pkt);
+			}
+			break;
+
+		case PACKET_WRITE_WAIT_STATE:
+			if (atomic_read(&pkt->io_wait) > 0)
+				return;
+
+			if (!pkt->w_bio->bi_status) {
+				pkt_set_state(pkt, PACKET_FINISHED_STATE);
+			} else {
+				pkt_set_state(pkt, PACKET_RECOVERY_STATE);
+			}
+			break;
+
+		case PACKET_RECOVERY_STATE:
+			pkt_dbg(2, pd, "No recovery possible\n");
+			pkt_set_state(pkt, PACKET_FINISHED_STATE);
+			break;
+
+		case PACKET_FINISHED_STATE:
+			pkt_finish_packet(pkt, pkt->w_bio->bi_status);
+			return;
+
+		default:
+			BUG();
+			break;
+		}
+	}
+}
+
+static void pkt_handle_packets(struct pktcdvd_device *pd)
+{
+	struct packet_data *pkt, *next;
+
+	/*
+	 * Run state machine for active packets
+	 */
+	list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
+		if (atomic_read(&pkt->run_sm) > 0) {
+			atomic_set(&pkt->run_sm, 0);
+			pkt_run_state_machine(pd, pkt);
+		}
+	}
+
+	/*
+	 * Move no longer active packets to the free list
+	 */
+	spin_lock(&pd->cdrw.active_list_lock);
+	list_for_each_entry_safe(pkt, next, &pd->cdrw.pkt_active_list, list) {
+		if (pkt->state == PACKET_FINISHED_STATE) {
+			list_del(&pkt->list);
+			pkt_put_packet_data(pd, pkt);
+			pkt_set_state(pkt, PACKET_IDLE_STATE);
+			atomic_set(&pd->scan_queue, 1);
+		}
+	}
+	spin_unlock(&pd->cdrw.active_list_lock);
+}
+
+static void pkt_count_states(struct pktcdvd_device *pd, int *states)
+{
+	struct packet_data *pkt;
+	int i;
+
+	for (i = 0; i < PACKET_NUM_STATES; i++)
+		states[i] = 0;
+
+	spin_lock(&pd->cdrw.active_list_lock);
+	list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
+		states[pkt->state]++;
+	}
+	spin_unlock(&pd->cdrw.active_list_lock);
+}
+
+/*
+ * kcdrwd is woken up when writes have been queued for one of our
+ * registered devices
+ */
+static int kcdrwd(void *foobar)
+{
+	struct pktcdvd_device *pd = foobar;
+	struct packet_data *pkt;
+	long min_sleep_time, residue;
+
+	set_user_nice(current, MIN_NICE);
+	set_freezable();
+
+	for (;;) {
+		DECLARE_WAITQUEUE(wait, current);
+
+		/*
+		 * Wait until there is something to do
+		 */
+		add_wait_queue(&pd->wqueue, &wait);
+		for (;;) {
+			set_current_state(TASK_INTERRUPTIBLE);
+
+			/* Check if we need to run pkt_handle_queue */
+			if (atomic_read(&pd->scan_queue) > 0)
+				goto work_to_do;
+
+			/* Check if we need to run the state machine for some packet */
+			list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
+				if (atomic_read(&pkt->run_sm) > 0)
+					goto work_to_do;
+			}
+
+			/* Check if we need to process the iosched queues */
+			if (atomic_read(&pd->iosched.attention) != 0)
+				goto work_to_do;
+
+			/* Otherwise, go to sleep */
+			if (PACKET_DEBUG > 1) {
+				int states[PACKET_NUM_STATES];
+				pkt_count_states(pd, states);
+				pkt_dbg(2, pd, "i:%d ow:%d rw:%d ww:%d rec:%d fin:%d\n",
+					states[0], states[1], states[2],
+					states[3], states[4], states[5]);
+			}
+
+			min_sleep_time = MAX_SCHEDULE_TIMEOUT;
+			list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
+				if (pkt->sleep_time && pkt->sleep_time < min_sleep_time)
+					min_sleep_time = pkt->sleep_time;
+			}
+
+			pkt_dbg(2, pd, "sleeping\n");
+			residue = schedule_timeout(min_sleep_time);
+			pkt_dbg(2, pd, "wake up\n");
+
+			/* make swsusp happy with our thread */
+			try_to_freeze();
+
+			list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
+				if (!pkt->sleep_time)
+					continue;
+				pkt->sleep_time -= min_sleep_time - residue;
+				if (pkt->sleep_time <= 0) {
+					pkt->sleep_time = 0;
+					atomic_inc(&pkt->run_sm);
+				}
+			}
+
+			if (kthread_should_stop())
+				break;
+		}
+work_to_do:
+		set_current_state(TASK_RUNNING);
+		remove_wait_queue(&pd->wqueue, &wait);
+
+		if (kthread_should_stop())
+			break;
+
+		/*
+		 * if pkt_handle_queue returns true, we can queue
+		 * another request.
+		 */
+		while (pkt_handle_queue(pd))
+			;
+
+		/*
+		 * Handle packet state machine
+		 */
+		pkt_handle_packets(pd);
+
+		/*
+		 * Handle iosched queues
+		 */
+		pkt_iosched_process_queue(pd);
+	}
+
+	return 0;
+}
+
+static void pkt_print_settings(struct pktcdvd_device *pd)
+{
+	pkt_info(pd, "%s packets, %u blocks, Mode-%c disc\n",
+		 pd->settings.fp ? "Fixed" : "Variable",
+		 pd->settings.size >> 2,
+		 pd->settings.block_mode == 8 ? '1' : '2');
+}
+
+static int pkt_mode_sense(struct pktcdvd_device *pd, struct packet_command *cgc, int page_code, int page_control)
+{
+	memset(cgc->cmd, 0, sizeof(cgc->cmd));
+
+	cgc->cmd[0] = GPCMD_MODE_SENSE_10;
+	cgc->cmd[2] = page_code | (page_control << 6);
+	cgc->cmd[7] = cgc->buflen >> 8;
+	cgc->cmd[8] = cgc->buflen & 0xff;
+	cgc->data_direction = CGC_DATA_READ;
+	return pkt_generic_packet(pd, cgc);
+}
+
+static int pkt_mode_select(struct pktcdvd_device *pd, struct packet_command *cgc)
+{
+	memset(cgc->cmd, 0, sizeof(cgc->cmd));
+	memset(cgc->buffer, 0, 2);
+	cgc->cmd[0] = GPCMD_MODE_SELECT_10;
+	cgc->cmd[1] = 0x10;		/* PF */
+	cgc->cmd[7] = cgc->buflen >> 8;
+	cgc->cmd[8] = cgc->buflen & 0xff;
+	cgc->data_direction = CGC_DATA_WRITE;
+	return pkt_generic_packet(pd, cgc);
+}
+
+static int pkt_get_disc_info(struct pktcdvd_device *pd, disc_information *di)
+{
+	struct packet_command cgc;
+	int ret;
+
+	/* set up command and get the disc info */
+	init_cdrom_command(&cgc, di, sizeof(*di), CGC_DATA_READ);
+	cgc.cmd[0] = GPCMD_READ_DISC_INFO;
+	cgc.cmd[8] = cgc.buflen = 2;
+	cgc.quiet = 1;
+
+	ret = pkt_generic_packet(pd, &cgc);
+	if (ret)
+		return ret;
+
+	/* not all drives have the same disc_info length, so requeue
+	 * packet with the length the drive tells us it can supply
+	 */
+	cgc.buflen = be16_to_cpu(di->disc_information_length) +
+		     sizeof(di->disc_information_length);
+
+	if (cgc.buflen > sizeof(disc_information))
+		cgc.buflen = sizeof(disc_information);
+
+	cgc.cmd[8] = cgc.buflen;
+	return pkt_generic_packet(pd, &cgc);
+}
+
+static int pkt_get_track_info(struct pktcdvd_device *pd, __u16 track, __u8 type, track_information *ti)
+{
+	struct packet_command cgc;
+	int ret;
+
+	init_cdrom_command(&cgc, ti, 8, CGC_DATA_READ);
+	cgc.cmd[0] = GPCMD_READ_TRACK_RZONE_INFO;
+	cgc.cmd[1] = type & 3;
+	cgc.cmd[4] = (track & 0xff00) >> 8;
+	cgc.cmd[5] = track & 0xff;
+	cgc.cmd[8] = 8;
+	cgc.quiet = 1;
+
+	ret = pkt_generic_packet(pd, &cgc);
+	if (ret)
+		return ret;
+
+	cgc.buflen = be16_to_cpu(ti->track_information_length) +
+		     sizeof(ti->track_information_length);
+
+	if (cgc.buflen > sizeof(track_information))
+		cgc.buflen = sizeof(track_information);
+
+	cgc.cmd[8] = cgc.buflen;
+	return pkt_generic_packet(pd, &cgc);
+}
+
+static noinline_for_stack int pkt_get_last_written(struct pktcdvd_device *pd,
+						long *last_written)
+{
+	disc_information di;
+	track_information ti;
+	__u32 last_track;
+	int ret;
+
+	ret = pkt_get_disc_info(pd, &di);
+	if (ret)
+		return ret;
+
+	last_track = (di.last_track_msb << 8) | di.last_track_lsb;
+	ret = pkt_get_track_info(pd, last_track, 1, &ti);
+	if (ret)
+		return ret;
+
+	/* if this track is blank, try the previous. */
+	if (ti.blank) {
+		last_track--;
+		ret = pkt_get_track_info(pd, last_track, 1, &ti);
+		if (ret)
+			return ret;
+	}
+
+	/* if last recorded field is valid, return it. */
+	if (ti.lra_v) {
+		*last_written = be32_to_cpu(ti.last_rec_address);
+	} else {
+		/* make it up instead */
+		*last_written = be32_to_cpu(ti.track_start) +
+				be32_to_cpu(ti.track_size);
+		if (ti.free_blocks)
+			*last_written -= (be32_to_cpu(ti.free_blocks) + 7);
+	}
+	return 0;
+}
+
+/*
+ * write mode select package based on pd->settings
+ */
+static noinline_for_stack int pkt_set_write_settings(struct pktcdvd_device *pd)
+{
+	struct packet_command cgc;
+	struct scsi_sense_hdr sshdr;
+	write_param_page *wp;
+	char buffer[128];
+	int ret, size;
+
+	/* doesn't apply to DVD+RW or DVD-RAM */
+	if ((pd->mmc3_profile == 0x1a) || (pd->mmc3_profile == 0x12))
+		return 0;
+
+	memset(buffer, 0, sizeof(buffer));
+	init_cdrom_command(&cgc, buffer, sizeof(*wp), CGC_DATA_READ);
+	cgc.sshdr = &sshdr;
+	ret = pkt_mode_sense(pd, &cgc, GPMODE_WRITE_PARMS_PAGE, 0);
+	if (ret) {
+		pkt_dump_sense(pd, &cgc);
+		return ret;
+	}
+
+	size = 2 + ((buffer[0] << 8) | (buffer[1] & 0xff));
+	pd->mode_offset = (buffer[6] << 8) | (buffer[7] & 0xff);
+	if (size > sizeof(buffer))
+		size = sizeof(buffer);
+
+	/*
+	 * now get it all
+	 */
+	init_cdrom_command(&cgc, buffer, size, CGC_DATA_READ);
+	cgc.sshdr = &sshdr;
+	ret = pkt_mode_sense(pd, &cgc, GPMODE_WRITE_PARMS_PAGE, 0);
+	if (ret) {
+		pkt_dump_sense(pd, &cgc);
+		return ret;
+	}
+
+	/*
+	 * write page is offset header + block descriptor length
+	 */
+	wp = (write_param_page *) &buffer[sizeof(struct mode_page_header) + pd->mode_offset];
+
+	wp->fp = pd->settings.fp;
+	wp->track_mode = pd->settings.track_mode;
+	wp->write_type = pd->settings.write_type;
+	wp->data_block_type = pd->settings.block_mode;
+
+	wp->multi_session = 0;
+
+#ifdef PACKET_USE_LS
+	wp->link_size = 7;
+	wp->ls_v = 1;
+#endif
+
+	if (wp->data_block_type == PACKET_BLOCK_MODE1) {
+		wp->session_format = 0;
+		wp->subhdr2 = 0x20;
+	} else if (wp->data_block_type == PACKET_BLOCK_MODE2) {
+		wp->session_format = 0x20;
+		wp->subhdr2 = 8;
+#if 0
+		wp->mcn[0] = 0x80;
+		memcpy(&wp->mcn[1], PACKET_MCN, sizeof(wp->mcn) - 1);
+#endif
+	} else {
+		/*
+		 * paranoia
+		 */
+		pkt_err(pd, "write mode wrong %d\n", wp->data_block_type);
+		return 1;
+	}
+	wp->packet_size = cpu_to_be32(pd->settings.size >> 2);
+
+	cgc.buflen = cgc.cmd[8] = size;
+	ret = pkt_mode_select(pd, &cgc);
+	if (ret) {
+		pkt_dump_sense(pd, &cgc);
+		return ret;
+	}
+
+	pkt_print_settings(pd);
+	return 0;
+}
+
+/*
+ * 1 -- we can write to this track, 0 -- we can't
+ */
+static int pkt_writable_track(struct pktcdvd_device *pd, track_information *ti)
+{
+	switch (pd->mmc3_profile) {
+		case 0x1a: /* DVD+RW */
+		case 0x12: /* DVD-RAM */
+			/* The track is always writable on DVD+RW/DVD-RAM */
+			return 1;
+		default:
+			break;
+	}
+
+	if (!ti->packet || !ti->fp)
+		return 0;
+
+	/*
+	 * "good" settings as per Mt Fuji.
+	 */
+	if (ti->rt == 0 && ti->blank == 0)
+		return 1;
+
+	if (ti->rt == 0 && ti->blank == 1)
+		return 1;
+
+	if (ti->rt == 1 && ti->blank == 0)
+		return 1;
+
+	pkt_err(pd, "bad state %d-%d-%d\n", ti->rt, ti->blank, ti->packet);
+	return 0;
+}
+
+/*
+ * 1 -- we can write to this disc, 0 -- we can't
+ */
+static int pkt_writable_disc(struct pktcdvd_device *pd, disc_information *di)
+{
+	switch (pd->mmc3_profile) {
+		case 0x0a: /* CD-RW */
+		case 0xffff: /* MMC3 not supported */
+			break;
+		case 0x1a: /* DVD+RW */
+		case 0x13: /* DVD-RW */
+		case 0x12: /* DVD-RAM */
+			return 1;
+		default:
+			pkt_dbg(2, pd, "Wrong disc profile (%x)\n",
+				pd->mmc3_profile);
+			return 0;
+	}
+
+	/*
+	 * for disc type 0xff we should probably reserve a new track.
+	 * but i'm not sure, should we leave this to user apps? probably.
+	 */
+	if (di->disc_type == 0xff) {
+		pkt_notice(pd, "unknown disc - no track?\n");
+		return 0;
+	}
+
+	if (di->disc_type != 0x20 && di->disc_type != 0) {
+		pkt_err(pd, "wrong disc type (%x)\n", di->disc_type);
+		return 0;
+	}
+
+	if (di->erasable == 0) {
+		pkt_notice(pd, "disc not erasable\n");
+		return 0;
+	}
+
+	if (di->border_status == PACKET_SESSION_RESERVED) {
+		pkt_err(pd, "can't write to last track (reserved)\n");
+		return 0;
+	}
+
+	return 1;
+}
+
+static noinline_for_stack int pkt_probe_settings(struct pktcdvd_device *pd)
+{
+	struct packet_command cgc;
+	unsigned char buf[12];
+	disc_information di;
+	track_information ti;
+	int ret, track;
+
+	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
+	cgc.cmd[0] = GPCMD_GET_CONFIGURATION;
+	cgc.cmd[8] = 8;
+	ret = pkt_generic_packet(pd, &cgc);
+	pd->mmc3_profile = ret ? 0xffff : buf[6] << 8 | buf[7];
+
+	memset(&di, 0, sizeof(disc_information));
+	memset(&ti, 0, sizeof(track_information));
+
+	ret = pkt_get_disc_info(pd, &di);
+	if (ret) {
+		pkt_err(pd, "failed get_disc\n");
+		return ret;
+	}
+
+	if (!pkt_writable_disc(pd, &di))
+		return -EROFS;
+
+	pd->type = di.erasable ? PACKET_CDRW : PACKET_CDR;
+
+	track = 1; /* (di.last_track_msb << 8) | di.last_track_lsb; */
+	ret = pkt_get_track_info(pd, track, 1, &ti);
+	if (ret) {
+		pkt_err(pd, "failed get_track\n");
+		return ret;
+	}
+
+	if (!pkt_writable_track(pd, &ti)) {
+		pkt_err(pd, "can't write to this track\n");
+		return -EROFS;
+	}
+
+	/*
+	 * we keep packet size in 512 byte units, makes it easier to
+	 * deal with request calculations.
+	 */
+	pd->settings.size = be32_to_cpu(ti.fixed_packet_size) << 2;
+	if (pd->settings.size == 0) {
+		pkt_notice(pd, "detected zero packet size!\n");
+		return -ENXIO;
+	}
+	if (pd->settings.size > PACKET_MAX_SECTORS) {
+		pkt_err(pd, "packet size is too big\n");
+		return -EROFS;
+	}
+	pd->settings.fp = ti.fp;
+	pd->offset = (be32_to_cpu(ti.track_start) << 2) & (pd->settings.size - 1);
+
+	if (ti.nwa_v) {
+		pd->nwa = be32_to_cpu(ti.next_writable);
+		set_bit(PACKET_NWA_VALID, &pd->flags);
+	}
+
+	/*
+	 * in theory we could use lra on -RW media as well and just zero
+	 * blocks that haven't been written yet, but in practice that
+	 * is just a no-go. we'll use that for -R, naturally.
+	 */
+	if (ti.lra_v) {
+		pd->lra = be32_to_cpu(ti.last_rec_address);
+		set_bit(PACKET_LRA_VALID, &pd->flags);
+	} else {
+		pd->lra = 0xffffffff;
+		set_bit(PACKET_LRA_VALID, &pd->flags);
+	}
+
+	/*
+	 * fine for now
+	 */
+	pd->settings.link_loss = 7;
+	pd->settings.write_type = 0;	/* packet */
+	pd->settings.track_mode = ti.track_mode;
+
+	/*
+	 * mode1 or mode2 disc
+	 */
+	switch (ti.data_mode) {
+		case PACKET_MODE1:
+			pd->settings.block_mode = PACKET_BLOCK_MODE1;
+			break;
+		case PACKET_MODE2:
+			pd->settings.block_mode = PACKET_BLOCK_MODE2;
+			break;
+		default:
+			pkt_err(pd, "unknown data mode\n");
+			return -EROFS;
+	}
+	return 0;
+}
+
+/*
+ * enable/disable write caching on drive
+ */
+static noinline_for_stack int pkt_write_caching(struct pktcdvd_device *pd,
+						int set)
+{
+	struct packet_command cgc;
+	struct scsi_sense_hdr sshdr;
+	unsigned char buf[64];
+	int ret;
+
+	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_READ);
+	cgc.sshdr = &sshdr;
+	cgc.buflen = pd->mode_offset + 12;
+
+	/*
+	 * caching mode page might not be there, so quiet this command
+	 */
+	cgc.quiet = 1;
+
+	ret = pkt_mode_sense(pd, &cgc, GPMODE_WCACHING_PAGE, 0);
+	if (ret)
+		return ret;
+
+	buf[pd->mode_offset + 10] |= (!!set << 2);
+
+	cgc.buflen = cgc.cmd[8] = 2 + ((buf[0] << 8) | (buf[1] & 0xff));
+	ret = pkt_mode_select(pd, &cgc);
+	if (ret) {
+		pkt_err(pd, "write caching control failed\n");
+		pkt_dump_sense(pd, &cgc);
+	} else if (!ret && set)
+		pkt_notice(pd, "enabled write caching\n");
+	return ret;
+}
+
+static int pkt_lock_door(struct pktcdvd_device *pd, int lockflag)
+{
+	struct packet_command cgc;
+
+	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
+	cgc.cmd[0] = GPCMD_PREVENT_ALLOW_MEDIUM_REMOVAL;
+	cgc.cmd[4] = lockflag ? 1 : 0;
+	return pkt_generic_packet(pd, &cgc);
+}
+
+/*
+ * Returns drive maximum write speed
+ */
+static noinline_for_stack int pkt_get_max_speed(struct pktcdvd_device *pd,
+						unsigned *write_speed)
+{
+	struct packet_command cgc;
+	struct scsi_sense_hdr sshdr;
+	unsigned char buf[256+18];
+	unsigned char *cap_buf;
+	int ret, offset;
+
+	cap_buf = &buf[sizeof(struct mode_page_header) + pd->mode_offset];
+	init_cdrom_command(&cgc, buf, sizeof(buf), CGC_DATA_UNKNOWN);
+	cgc.sshdr = &sshdr;
+
+	ret = pkt_mode_sense(pd, &cgc, GPMODE_CAPABILITIES_PAGE, 0);
+	if (ret) {
+		cgc.buflen = pd->mode_offset + cap_buf[1] + 2 +
+			     sizeof(struct mode_page_header);
+		ret = pkt_mode_sense(pd, &cgc, GPMODE_CAPABILITIES_PAGE, 0);
+		if (ret) {
+			pkt_dump_sense(pd, &cgc);
+			return ret;
+		}
+	}
+
+	offset = 20;			    /* Obsoleted field, used by older drives */
+	if (cap_buf[1] >= 28)
+		offset = 28;		    /* Current write speed selected */
+	if (cap_buf[1] >= 30) {
+		/* If the drive reports at least one "Logical Unit Write
+		 * Speed Performance Descriptor Block", use the information
+		 * in the first block. (contains the highest speed)
+		 */
+		int num_spdb = (cap_buf[30] << 8) + cap_buf[31];
+		if (num_spdb > 0)
+			offset = 34;
+	}
+
+	*write_speed = (cap_buf[offset] << 8) | cap_buf[offset + 1];
+	return 0;
+}
+
+/* These tables from cdrecord - I don't have orange book */
+/* standard speed CD-RW (1-4x) */
+static char clv_to_speed[16] = {
+	/* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
+	   0, 2, 4, 6, 8, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+/* high speed CD-RW (-10x) */
+static char hs_clv_to_speed[16] = {
+	/* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
+	   0, 2, 4, 6, 10, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
+};
+/* ultra high speed CD-RW */
+static char us_clv_to_speed[16] = {
+	/* 0  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 */
+	   0, 2, 4, 8, 0, 0,16, 0,24,32,40,48, 0, 0, 0, 0
+};
+
+/*
+ * reads the maximum media speed from ATIP
+ */
+static noinline_for_stack int pkt_media_speed(struct pktcdvd_device *pd,
+						unsigned *speed)
+{
+	struct packet_command cgc;
+	struct scsi_sense_hdr sshdr;
+	unsigned char buf[64];
+	unsigned int size, st, sp;
+	int ret;
+
+	init_cdrom_command(&cgc, buf, 2, CGC_DATA_READ);
+	cgc.sshdr = &sshdr;
+	cgc.cmd[0] = GPCMD_READ_TOC_PMA_ATIP;
+	cgc.cmd[1] = 2;
+	cgc.cmd[2] = 4; /* READ ATIP */
+	cgc.cmd[8] = 2;
+	ret = pkt_generic_packet(pd, &cgc);
+	if (ret) {
+		pkt_dump_sense(pd, &cgc);
+		return ret;
+	}
+	size = ((unsigned int) buf[0]<<8) + buf[1] + 2;
+	if (size > sizeof(buf))
+		size = sizeof(buf);
+
+	init_cdrom_command(&cgc, buf, size, CGC_DATA_READ);
+	cgc.sshdr = &sshdr;
+	cgc.cmd[0] = GPCMD_READ_TOC_PMA_ATIP;
+	cgc.cmd[1] = 2;
+	cgc.cmd[2] = 4;
+	cgc.cmd[8] = size;
+	ret = pkt_generic_packet(pd, &cgc);
+	if (ret) {
+		pkt_dump_sense(pd, &cgc);
+		return ret;
+	}
+
+	if (!(buf[6] & 0x40)) {
+		pkt_notice(pd, "disc type is not CD-RW\n");
+		return 1;
+	}
+	if (!(buf[6] & 0x4)) {
+		pkt_notice(pd, "A1 values on media are not valid, maybe not CDRW?\n");
+		return 1;
+	}
+
+	st = (buf[6] >> 3) & 0x7; /* disc sub-type */
+
+	sp = buf[16] & 0xf; /* max speed from ATIP A1 field */
+
+	/* Info from cdrecord */
+	switch (st) {
+		case 0: /* standard speed */
+			*speed = clv_to_speed[sp];
+			break;
+		case 1: /* high speed */
+			*speed = hs_clv_to_speed[sp];
+			break;
+		case 2: /* ultra high speed */
+			*speed = us_clv_to_speed[sp];
+			break;
+		default:
+			pkt_notice(pd, "unknown disc sub-type %d\n", st);
+			return 1;
+	}
+	if (*speed) {
+		pkt_info(pd, "maximum media speed: %d\n", *speed);
+		return 0;
+	} else {
+		pkt_notice(pd, "unknown speed %d for sub-type %d\n", sp, st);
+		return 1;
+	}
+}
+
+static noinline_for_stack int pkt_perform_opc(struct pktcdvd_device *pd)
+{
+	struct packet_command cgc;
+	struct scsi_sense_hdr sshdr;
+	int ret;
+
+	pkt_dbg(2, pd, "Performing OPC\n");
+
+	init_cdrom_command(&cgc, NULL, 0, CGC_DATA_NONE);
+	cgc.sshdr = &sshdr;
+	cgc.timeout = 60*HZ;
+	cgc.cmd[0] = GPCMD_SEND_OPC;
+	cgc.cmd[1] = 1;
+	ret = pkt_generic_packet(pd, &cgc);
+	if (ret)
+		pkt_dump_sense(pd, &cgc);
+	return ret;
+}
+
+static int pkt_open_write(struct pktcdvd_device *pd)
+{
+	int ret;
+	unsigned int write_speed, media_write_speed, read_speed;
+
+	ret = pkt_probe_settings(pd);
+	if (ret) {
+		pkt_dbg(2, pd, "failed probe\n");
+		return ret;
+	}
+
+	ret = pkt_set_write_settings(pd);
+	if (ret) {
+		pkt_dbg(1, pd, "failed saving write settings\n");
+		return -EIO;
+	}
+
+	pkt_write_caching(pd, USE_WCACHING);
+
+	ret = pkt_get_max_speed(pd, &write_speed);
+	if (ret)
+		write_speed = 16 * 177;
+	switch (pd->mmc3_profile) {
+		case 0x13: /* DVD-RW */
+		case 0x1a: /* DVD+RW */
+		case 0x12: /* DVD-RAM */
+			pkt_dbg(1, pd, "write speed %ukB/s\n", write_speed);
+			break;
+		default:
+			ret = pkt_media_speed(pd, &media_write_speed);
+			if (ret)
+				media_write_speed = 16;
+			write_speed = min(write_speed, media_write_speed * 177);
+			pkt_dbg(1, pd, "write speed %ux\n", write_speed / 176);
+			break;
+	}
+	read_speed = write_speed;
+
+	ret = pkt_set_speed(pd, write_speed, read_speed);
+	if (ret) {
+		pkt_dbg(1, pd, "couldn't set write speed\n");
+		return -EIO;
+	}
+	pd->write_speed = write_speed;
+	pd->read_speed = read_speed;
+
+	ret = pkt_perform_opc(pd);
+	if (ret) {
+		pkt_dbg(1, pd, "Optimum Power Calibration failed\n");
+	}
+
+	return 0;
+}
+
+/*
+ * called at open time.
+ */
+static int pkt_open_dev(struct pktcdvd_device *pd, fmode_t write)
+{
+	int ret;
+	long lba;
+	struct request_queue *q;
+	struct block_device *bdev;
+
+	/*
+	 * We need to re-open the cdrom device without O_NONBLOCK to be able
+	 * to read/write from/to it. It is already opened in O_NONBLOCK mode
+	 * so open should not fail.
+	 */
+	bdev = blkdev_get_by_dev(pd->bdev->bd_dev, FMODE_READ | FMODE_EXCL, pd);
+	if (IS_ERR(bdev)) {
+		ret = PTR_ERR(bdev);
+		goto out;
+	}
+
+	ret = pkt_get_last_written(pd, &lba);
+	if (ret) {
+		pkt_err(pd, "pkt_get_last_written failed\n");
+		goto out_putdev;
+	}
+
+	set_capacity(pd->disk, lba << 2);
+	set_capacity_and_notify(pd->bdev->bd_disk, lba << 2);
+
+	q = bdev_get_queue(pd->bdev);
+	if (write) {
+		ret = pkt_open_write(pd);
+		if (ret)
+			goto out_putdev;
+		/*
+		 * Some CDRW drives can not handle writes larger than one packet,
+		 * even if the size is a multiple of the packet size.
+		 */
+		blk_queue_max_hw_sectors(q, pd->settings.size);
+		set_bit(PACKET_WRITABLE, &pd->flags);
+	} else {
+		pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);
+		clear_bit(PACKET_WRITABLE, &pd->flags);
+	}
+
+	ret = pkt_set_segment_merging(pd, q);
+	if (ret)
+		goto out_putdev;
+
+	if (write) {
+		if (!pkt_grow_pktlist(pd, CONFIG_CDROM_PKTCDVD_BUFFERS)) {
+			pkt_err(pd, "not enough memory for buffers\n");
+			ret = -ENOMEM;
+			goto out_putdev;
+		}
+		pkt_info(pd, "%lukB available on disc\n", lba << 1);
+	}
+
+	return 0;
+
+out_putdev:
+	blkdev_put(bdev, FMODE_READ | FMODE_EXCL);
+out:
+	return ret;
+}
+
+/*
+ * called when the device is closed. makes sure that the device flushes
+ * the internal cache before we close.
+ */
+static void pkt_release_dev(struct pktcdvd_device *pd, int flush)
+{
+	if (flush && pkt_flush_cache(pd))
+		pkt_dbg(1, pd, "not flushing cache\n");
+
+	pkt_lock_door(pd, 0);
+
+	pkt_set_speed(pd, MAX_SPEED, MAX_SPEED);
+	blkdev_put(pd->bdev, FMODE_READ | FMODE_EXCL);
+
+	pkt_shrink_pktlist(pd);
+}
+
+static struct pktcdvd_device *pkt_find_dev_from_minor(unsigned int dev_minor)
+{
+	if (dev_minor >= MAX_WRITERS)
+		return NULL;
+
+	dev_minor = array_index_nospec(dev_minor, MAX_WRITERS);
+	return pkt_devs[dev_minor];
+}
+
+static int pkt_open(struct block_device *bdev, fmode_t mode)
+{
+	struct pktcdvd_device *pd = NULL;
+	int ret;
+
+	mutex_lock(&pktcdvd_mutex);
+	mutex_lock(&ctl_mutex);
+	pd = pkt_find_dev_from_minor(MINOR(bdev->bd_dev));
+	if (!pd) {
+		ret = -ENODEV;
+		goto out;
+	}
+	BUG_ON(pd->refcnt < 0);
+
+	pd->refcnt++;
+	if (pd->refcnt > 1) {
+		if ((mode & FMODE_WRITE) &&
+		    !test_bit(PACKET_WRITABLE, &pd->flags)) {
+			ret = -EBUSY;
+			goto out_dec;
+		}
+	} else {
+		ret = pkt_open_dev(pd, mode & FMODE_WRITE);
+		if (ret)
+			goto out_dec;
+		/*
+		 * needed here as well, since ext2 (among others) may change
+		 * the blocksize at mount time
+		 */
+		set_blocksize(bdev, CD_FRAMESIZE);
+	}
+
+	mutex_unlock(&ctl_mutex);
+	mutex_unlock(&pktcdvd_mutex);
+	return 0;
+
+out_dec:
+	pd->refcnt--;
+out:
+	mutex_unlock(&ctl_mutex);
+	mutex_unlock(&pktcdvd_mutex);
+	return ret;
+}
+
+static void pkt_close(struct gendisk *disk, fmode_t mode)
+{
+	struct pktcdvd_device *pd = disk->private_data;
+
+	mutex_lock(&pktcdvd_mutex);
+	mutex_lock(&ctl_mutex);
+	pd->refcnt--;
+	BUG_ON(pd->refcnt < 0);
+	if (pd->refcnt == 0) {
+		int flush = test_bit(PACKET_WRITABLE, &pd->flags);
+		pkt_release_dev(pd, flush);
+	}
+	mutex_unlock(&ctl_mutex);
+	mutex_unlock(&pktcdvd_mutex);
+}
+
+
+static void pkt_end_io_read_cloned(struct bio *bio)
+{
+	struct packet_stacked_data *psd = bio->bi_private;
+	struct pktcdvd_device *pd = psd->pd;
+
+	psd->bio->bi_status = bio->bi_status;
+	bio_put(bio);
+	bio_endio(psd->bio);
+	mempool_free(psd, &psd_pool);
+	pkt_bio_finished(pd);
+}
+
+static void pkt_make_request_read(struct pktcdvd_device *pd, struct bio *bio)
+{
+	struct bio *cloned_bio =
+		bio_alloc_clone(pd->bdev, bio, GFP_NOIO, &pkt_bio_set);
+	struct packet_stacked_data *psd = mempool_alloc(&psd_pool, GFP_NOIO);
+
+	psd->pd = pd;
+	psd->bio = bio;
+	cloned_bio->bi_private = psd;
+	cloned_bio->bi_end_io = pkt_end_io_read_cloned;
+	pd->stats.secs_r += bio_sectors(bio);
+	pkt_queue_bio(pd, cloned_bio);
+}
+
+static void pkt_make_request_write(struct request_queue *q, struct bio *bio)
+{
+	struct pktcdvd_device *pd = q->queuedata;
+	sector_t zone;
+	struct packet_data *pkt;
+	int was_empty, blocked_bio;
+	struct pkt_rb_node *node;
+
+	zone = get_zone(bio->bi_iter.bi_sector, pd);
+
+	/*
+	 * If we find a matching packet in state WAITING or READ_WAIT, we can
+	 * just append this bio to that packet.
+	 */
+	spin_lock(&pd->cdrw.active_list_lock);
+	blocked_bio = 0;
+	list_for_each_entry(pkt, &pd->cdrw.pkt_active_list, list) {
+		if (pkt->sector == zone) {
+			spin_lock(&pkt->lock);
+			if ((pkt->state == PACKET_WAITING_STATE) ||
+			    (pkt->state == PACKET_READ_WAIT_STATE)) {
+				bio_list_add(&pkt->orig_bios, bio);
+				pkt->write_size +=
+					bio->bi_iter.bi_size / CD_FRAMESIZE;
+				if ((pkt->write_size >= pkt->frames) &&
+				    (pkt->state == PACKET_WAITING_STATE)) {
+					atomic_inc(&pkt->run_sm);
+					wake_up(&pd->wqueue);
+				}
+				spin_unlock(&pkt->lock);
+				spin_unlock(&pd->cdrw.active_list_lock);
+				return;
+			} else {
+				blocked_bio = 1;
+			}
+			spin_unlock(&pkt->lock);
+		}
+	}
+	spin_unlock(&pd->cdrw.active_list_lock);
+
+	/*
+	 * Test if there is enough room left in the bio work queue
+	 * (queue size >= congestion on mark).
+	 * If not, wait till the work queue size is below the congestion off mark.
+	 */
+	spin_lock(&pd->lock);
+	if (pd->write_congestion_on > 0
+	    && pd->bio_queue_size >= pd->write_congestion_on) {
+		struct wait_bit_queue_entry wqe;
+
+		init_wait_var_entry(&wqe, &pd->congested, 0);
+		for (;;) {
+			prepare_to_wait_event(__var_waitqueue(&pd->congested),
+					      &wqe.wq_entry,
+					      TASK_UNINTERRUPTIBLE);
+			if (pd->bio_queue_size <= pd->write_congestion_off)
+				break;
+			pd->congested = true;
+			spin_unlock(&pd->lock);
+			schedule();
+			spin_lock(&pd->lock);
+		}
+	}
+	spin_unlock(&pd->lock);
+
+	/*
+	 * No matching packet found. Store the bio in the work queue.
+	 */
+	node = mempool_alloc(&pd->rb_pool, GFP_NOIO);
+	node->bio = bio;
+	spin_lock(&pd->lock);
+	BUG_ON(pd->bio_queue_size < 0);
+	was_empty = (pd->bio_queue_size == 0);
+	pkt_rbtree_insert(pd, node);
+	spin_unlock(&pd->lock);
+
+	/*
+	 * Wake up the worker thread.
+	 */
+	atomic_set(&pd->scan_queue, 1);
+	if (was_empty) {
+		/* This wake_up is required for correct operation */
+		wake_up(&pd->wqueue);
+	} else if (!list_empty(&pd->cdrw.pkt_free_list) && !blocked_bio) {
+		/*
+		 * This wake up is not required for correct operation,
+		 * but improves performance in some cases.
+		 */
+		wake_up(&pd->wqueue);
+	}
+}
+
+static void pkt_submit_bio(struct bio *bio)
+{
+	struct pktcdvd_device *pd = bio->bi_bdev->bd_disk->queue->queuedata;
+	struct bio *split;
+
+	bio = bio_split_to_limits(bio);
+
+	pkt_dbg(2, pd, "start = %6llx stop = %6llx\n",
+		(unsigned long long)bio->bi_iter.bi_sector,
+		(unsigned long long)bio_end_sector(bio));
+
+	/*
+	 * Clone READ bios so we can have our own bi_end_io callback.
+	 */
+	if (bio_data_dir(bio) == READ) {
+		pkt_make_request_read(pd, bio);
+		return;
+	}
+
+	if (!test_bit(PACKET_WRITABLE, &pd->flags)) {
+		pkt_notice(pd, "WRITE for ro device (%llu)\n",
+			   (unsigned long long)bio->bi_iter.bi_sector);
+		goto end_io;
+	}
+
+	if (!bio->bi_iter.bi_size || (bio->bi_iter.bi_size % CD_FRAMESIZE)) {
+		pkt_err(pd, "wrong bio size\n");
+		goto end_io;
+	}
+
+	do {
+		sector_t zone = get_zone(bio->bi_iter.bi_sector, pd);
+		sector_t last_zone = get_zone(bio_end_sector(bio) - 1, pd);
+
+		if (last_zone != zone) {
+			BUG_ON(last_zone != zone + pd->settings.size);
+
+			split = bio_split(bio, last_zone -
+					  bio->bi_iter.bi_sector,
+					  GFP_NOIO, &pkt_bio_set);
+			bio_chain(split, bio);
+		} else {
+			split = bio;
+		}
+
+		pkt_make_request_write(bio->bi_bdev->bd_disk->queue, split);
+	} while (split != bio);
+
+	return;
+end_io:
+	bio_io_error(bio);
+}
+
+static void pkt_init_queue(struct pktcdvd_device *pd)
+{
+	struct request_queue *q = pd->disk->queue;
+
+	blk_queue_logical_block_size(q, CD_FRAMESIZE);
+	blk_queue_max_hw_sectors(q, PACKET_MAX_SECTORS);
+	q->queuedata = pd;
+}
+
+static int pkt_seq_show(struct seq_file *m, void *p)
+{
+	struct pktcdvd_device *pd = m->private;
+	char *msg;
+	int states[PACKET_NUM_STATES];
+
+	seq_printf(m, "Writer %s mapped to %pg:\n", pd->name, pd->bdev);
+
+	seq_printf(m, "\nSettings:\n");
+	seq_printf(m, "\tpacket size:\t\t%dkB\n", pd->settings.size / 2);
+
+	if (pd->settings.write_type == 0)
+		msg = "Packet";
+	else
+		msg = "Unknown";
+	seq_printf(m, "\twrite type:\t\t%s\n", msg);
+
+	seq_printf(m, "\tpacket type:\t\t%s\n", pd->settings.fp ? "Fixed" : "Variable");
+	seq_printf(m, "\tlink loss:\t\t%d\n", pd->settings.link_loss);
+
+	seq_printf(m, "\ttrack mode:\t\t%d\n", pd->settings.track_mode);
+
+	if (pd->settings.block_mode == PACKET_BLOCK_MODE1)
+		msg = "Mode 1";
+	else if (pd->settings.block_mode == PACKET_BLOCK_MODE2)
+		msg = "Mode 2";
+	else
+		msg = "Unknown";
+	seq_printf(m, "\tblock mode:\t\t%s\n", msg);
+
+	seq_printf(m, "\nStatistics:\n");
+	seq_printf(m, "\tpackets started:\t%lu\n", pd->stats.pkt_started);
+	seq_printf(m, "\tpackets ended:\t\t%lu\n", pd->stats.pkt_ended);
+	seq_printf(m, "\twritten:\t\t%lukB\n", pd->stats.secs_w >> 1);
+	seq_printf(m, "\tread gather:\t\t%lukB\n", pd->stats.secs_rg >> 1);
+	seq_printf(m, "\tread:\t\t\t%lukB\n", pd->stats.secs_r >> 1);
+
+	seq_printf(m, "\nMisc:\n");
+	seq_printf(m, "\treference count:\t%d\n", pd->refcnt);
+	seq_printf(m, "\tflags:\t\t\t0x%lx\n", pd->flags);
+	seq_printf(m, "\tread speed:\t\t%ukB/s\n", pd->read_speed);
+	seq_printf(m, "\twrite speed:\t\t%ukB/s\n", pd->write_speed);
+	seq_printf(m, "\tstart offset:\t\t%lu\n", pd->offset);
+	seq_printf(m, "\tmode page offset:\t%u\n", pd->mode_offset);
+
+	seq_printf(m, "\nQueue state:\n");
+	seq_printf(m, "\tbios queued:\t\t%d\n", pd->bio_queue_size);
+	seq_printf(m, "\tbios pending:\t\t%d\n", atomic_read(&pd->cdrw.pending_bios));
+	seq_printf(m, "\tcurrent sector:\t\t0x%llx\n", (unsigned long long)pd->current_sector);
+
+	pkt_count_states(pd, states);
+	seq_printf(m, "\tstate:\t\t\ti:%d ow:%d rw:%d ww:%d rec:%d fin:%d\n",
+		   states[0], states[1], states[2], states[3], states[4], states[5]);
+
+	seq_printf(m, "\twrite congestion marks:\toff=%d on=%d\n",
+			pd->write_congestion_off,
+			pd->write_congestion_on);
+	return 0;
+}
+
+static int pkt_new_dev(struct pktcdvd_device *pd, dev_t dev)
+{
+	int i;
+	struct block_device *bdev;
+	struct scsi_device *sdev;
+
+	if (pd->pkt_dev == dev) {
+		pkt_err(pd, "recursive setup not allowed\n");
+		return -EBUSY;
+	}
+	for (i = 0; i < MAX_WRITERS; i++) {
+		struct pktcdvd_device *pd2 = pkt_devs[i];
+		if (!pd2)
+			continue;
+		if (pd2->bdev->bd_dev == dev) {
+			pkt_err(pd, "%pg already setup\n", pd2->bdev);
+			return -EBUSY;
+		}
+		if (pd2->pkt_dev == dev) {
+			pkt_err(pd, "can't chain pktcdvd devices\n");
+			return -EBUSY;
+		}
+	}
+
+	bdev = blkdev_get_by_dev(dev, FMODE_READ | FMODE_NDELAY, NULL);
+	if (IS_ERR(bdev))
+		return PTR_ERR(bdev);
+	sdev = scsi_device_from_queue(bdev->bd_disk->queue);
+	if (!sdev) {
+		blkdev_put(bdev, FMODE_READ | FMODE_NDELAY);
+		return -EINVAL;
+	}
+	put_device(&sdev->sdev_gendev);
+
+	/* This is safe, since we have a reference from open(). */
+	__module_get(THIS_MODULE);
+
+	pd->bdev = bdev;
+	set_blocksize(bdev, CD_FRAMESIZE);
+
+	pkt_init_queue(pd);
+
+	atomic_set(&pd->cdrw.pending_bios, 0);
+	pd->cdrw.thread = kthread_run(kcdrwd, pd, "%s", pd->name);
+	if (IS_ERR(pd->cdrw.thread)) {
+		pkt_err(pd, "can't start kernel thread\n");
+		goto out_mem;
+	}
+
+	proc_create_single_data(pd->name, 0, pkt_proc, pkt_seq_show, pd);
+	pkt_dbg(1, pd, "writer mapped to %pg\n", bdev);
+	return 0;
+
+out_mem:
+	blkdev_put(bdev, FMODE_READ | FMODE_NDELAY);
+	/* This is safe: open() is still holding a reference. */
+	module_put(THIS_MODULE);
+	return -ENOMEM;
+}
+
+static int pkt_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long arg)
+{
+	struct pktcdvd_device *pd = bdev->bd_disk->private_data;
+	int ret;
+
+	pkt_dbg(2, pd, "cmd %x, dev %d:%d\n",
+		cmd, MAJOR(bdev->bd_dev), MINOR(bdev->bd_dev));
+
+	mutex_lock(&pktcdvd_mutex);
+	switch (cmd) {
+	case CDROMEJECT:
+		/*
+		 * The door gets locked when the device is opened, so we
+		 * have to unlock it or else the eject command fails.
+		 */
+		if (pd->refcnt == 1)
+			pkt_lock_door(pd, 0);
+		fallthrough;
+	/*
+	 * forward selected CDROM ioctls to CD-ROM, for UDF
+	 */
+	case CDROMMULTISESSION:
+	case CDROMREADTOCENTRY:
+	case CDROM_LAST_WRITTEN:
+	case CDROM_SEND_PACKET:
+	case SCSI_IOCTL_SEND_COMMAND:
+		if (!bdev->bd_disk->fops->ioctl)
+			ret = -ENOTTY;
+		else
+			ret = bdev->bd_disk->fops->ioctl(bdev, mode, cmd, arg);
+		break;
+	default:
+		pkt_dbg(2, pd, "Unknown ioctl (%x)\n", cmd);
+		ret = -ENOTTY;
+	}
+	mutex_unlock(&pktcdvd_mutex);
+
+	return ret;
+}
+
+static unsigned int pkt_check_events(struct gendisk *disk,
+				     unsigned int clearing)
+{
+	struct pktcdvd_device *pd = disk->private_data;
+	struct gendisk *attached_disk;
+
+	if (!pd)
+		return 0;
+	if (!pd->bdev)
+		return 0;
+	attached_disk = pd->bdev->bd_disk;
+	if (!attached_disk || !attached_disk->fops->check_events)
+		return 0;
+	return attached_disk->fops->check_events(attached_disk, clearing);
+}
+
+static char *pkt_devnode(struct gendisk *disk, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "pktcdvd/%s", disk->disk_name);
+}
+
+static const struct block_device_operations pktcdvd_ops = {
+	.owner =		THIS_MODULE,
+	.submit_bio =		pkt_submit_bio,
+	.open =			pkt_open,
+	.release =		pkt_close,
+	.ioctl =		pkt_ioctl,
+	.compat_ioctl =		blkdev_compat_ptr_ioctl,
+	.check_events =		pkt_check_events,
+	.devnode =		pkt_devnode,
+};
+
+/*
+ * Set up mapping from pktcdvd device to CD-ROM device.
+ */
+static int pkt_setup_dev(dev_t dev, dev_t* pkt_dev)
+{
+	int idx;
+	int ret = -ENOMEM;
+	struct pktcdvd_device *pd;
+	struct gendisk *disk;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	for (idx = 0; idx < MAX_WRITERS; idx++)
+		if (!pkt_devs[idx])
+			break;
+	if (idx == MAX_WRITERS) {
+		pr_err("max %d writers supported\n", MAX_WRITERS);
+		ret = -EBUSY;
+		goto out_mutex;
+	}
+
+	pd = kzalloc(sizeof(struct pktcdvd_device), GFP_KERNEL);
+	if (!pd)
+		goto out_mutex;
+
+	ret = mempool_init_kmalloc_pool(&pd->rb_pool, PKT_RB_POOL_SIZE,
+					sizeof(struct pkt_rb_node));
+	if (ret)
+		goto out_mem;
+
+	INIT_LIST_HEAD(&pd->cdrw.pkt_free_list);
+	INIT_LIST_HEAD(&pd->cdrw.pkt_active_list);
+	spin_lock_init(&pd->cdrw.active_list_lock);
+
+	spin_lock_init(&pd->lock);
+	spin_lock_init(&pd->iosched.lock);
+	bio_list_init(&pd->iosched.read_queue);
+	bio_list_init(&pd->iosched.write_queue);
+	sprintf(pd->name, DRIVER_NAME"%d", idx);
+	init_waitqueue_head(&pd->wqueue);
+	pd->bio_queue = RB_ROOT;
+
+	pd->write_congestion_on  = write_congestion_on;
+	pd->write_congestion_off = write_congestion_off;
+
+	ret = -ENOMEM;
+	disk = blk_alloc_disk(NUMA_NO_NODE);
+	if (!disk)
+		goto out_mem;
+	pd->disk = disk;
+	disk->major = pktdev_major;
+	disk->first_minor = idx;
+	disk->minors = 1;
+	disk->fops = &pktcdvd_ops;
+	disk->flags = GENHD_FL_REMOVABLE | GENHD_FL_NO_PART;
+	strcpy(disk->disk_name, pd->name);
+	disk->private_data = pd;
+
+	pd->pkt_dev = MKDEV(pktdev_major, idx);
+	ret = pkt_new_dev(pd, dev);
+	if (ret)
+		goto out_mem2;
+
+	/* inherit events of the host device */
+	disk->events = pd->bdev->bd_disk->events;
+
+	ret = add_disk(disk);
+	if (ret)
+		goto out_mem2;
+
+	pkt_sysfs_dev_new(pd);
+	pkt_debugfs_dev_new(pd);
+
+	pkt_devs[idx] = pd;
+	if (pkt_dev)
+		*pkt_dev = pd->pkt_dev;
+
+	mutex_unlock(&ctl_mutex);
+	return 0;
+
+out_mem2:
+	put_disk(disk);
+out_mem:
+	mempool_exit(&pd->rb_pool);
+	kfree(pd);
+out_mutex:
+	mutex_unlock(&ctl_mutex);
+	pr_err("setup of pktcdvd device failed\n");
+	return ret;
+}
+
+/*
+ * Tear down mapping from pktcdvd device to CD-ROM device.
+ */
+static int pkt_remove_dev(dev_t pkt_dev)
+{
+	struct pktcdvd_device *pd;
+	int idx;
+	int ret = 0;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	for (idx = 0; idx < MAX_WRITERS; idx++) {
+		pd = pkt_devs[idx];
+		if (pd && (pd->pkt_dev == pkt_dev))
+			break;
+	}
+	if (idx == MAX_WRITERS) {
+		pr_debug("dev not setup\n");
+		ret = -ENXIO;
+		goto out;
+	}
+
+	if (pd->refcnt > 0) {
+		ret = -EBUSY;
+		goto out;
+	}
+	if (!IS_ERR(pd->cdrw.thread))
+		kthread_stop(pd->cdrw.thread);
+
+	pkt_devs[idx] = NULL;
+
+	pkt_debugfs_dev_remove(pd);
+	pkt_sysfs_dev_remove(pd);
+
+	blkdev_put(pd->bdev, FMODE_READ | FMODE_NDELAY);
+
+	remove_proc_entry(pd->name, pkt_proc);
+	pkt_dbg(1, pd, "writer unmapped\n");
+
+	del_gendisk(pd->disk);
+	put_disk(pd->disk);
+
+	mempool_exit(&pd->rb_pool);
+	kfree(pd);
+
+	/* This is safe: open() is still holding a reference. */
+	module_put(THIS_MODULE);
+
+out:
+	mutex_unlock(&ctl_mutex);
+	return ret;
+}
+
+static void pkt_get_status(struct pkt_ctrl_command *ctrl_cmd)
+{
+	struct pktcdvd_device *pd;
+
+	mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
+
+	pd = pkt_find_dev_from_minor(ctrl_cmd->dev_index);
+	if (pd) {
+		ctrl_cmd->dev = new_encode_dev(pd->bdev->bd_dev);
+		ctrl_cmd->pkt_dev = new_encode_dev(pd->pkt_dev);
+	} else {
+		ctrl_cmd->dev = 0;
+		ctrl_cmd->pkt_dev = 0;
+	}
+	ctrl_cmd->num_devices = MAX_WRITERS;
+
+	mutex_unlock(&ctl_mutex);
+}
+
+static long pkt_ctl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	struct pkt_ctrl_command ctrl_cmd;
+	int ret = 0;
+	dev_t pkt_dev = 0;
+
+	if (cmd != PACKET_CTRL_CMD)
+		return -ENOTTY;
+
+	if (copy_from_user(&ctrl_cmd, argp, sizeof(struct pkt_ctrl_command)))
+		return -EFAULT;
+
+	switch (ctrl_cmd.command) {
+	case PKT_CTRL_CMD_SETUP:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		ret = pkt_setup_dev(new_decode_dev(ctrl_cmd.dev), &pkt_dev);
+		ctrl_cmd.pkt_dev = new_encode_dev(pkt_dev);
+		break;
+	case PKT_CTRL_CMD_TEARDOWN:
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		ret = pkt_remove_dev(new_decode_dev(ctrl_cmd.pkt_dev));
+		break;
+	case PKT_CTRL_CMD_STATUS:
+		pkt_get_status(&ctrl_cmd);
+		break;
+	default:
+		return -ENOTTY;
+	}
+
+	if (copy_to_user(argp, &ctrl_cmd, sizeof(struct pkt_ctrl_command)))
+		return -EFAULT;
+	return ret;
+}
+
+#ifdef CONFIG_COMPAT
+static long pkt_ctl_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+{
+	return pkt_ctl_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static const struct file_operations pkt_ctl_fops = {
+	.open		= nonseekable_open,
+	.unlocked_ioctl	= pkt_ctl_ioctl,
+#ifdef CONFIG_COMPAT
+	.compat_ioctl	= pkt_ctl_compat_ioctl,
+#endif
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+};
+
+static struct miscdevice pkt_misc = {
+	.minor 		= MISC_DYNAMIC_MINOR,
+	.name  		= DRIVER_NAME,
+	.nodename	= "pktcdvd/control",
+	.fops  		= &pkt_ctl_fops
+};
+
+static int __init pkt_init(void)
+{
+	int ret;
+
+	mutex_init(&ctl_mutex);
+
+	ret = mempool_init_kmalloc_pool(&psd_pool, PSD_POOL_SIZE,
+				    sizeof(struct packet_stacked_data));
+	if (ret)
+		return ret;
+	ret = bioset_init(&pkt_bio_set, BIO_POOL_SIZE, 0, 0);
+	if (ret) {
+		mempool_exit(&psd_pool);
+		return ret;
+	}
+
+	ret = register_blkdev(pktdev_major, DRIVER_NAME);
+	if (ret < 0) {
+		pr_err("unable to register block device\n");
+		goto out2;
+	}
+	if (!pktdev_major)
+		pktdev_major = ret;
+
+	ret = pkt_sysfs_init();
+	if (ret)
+		goto out;
+
+	pkt_debugfs_init();
+
+	ret = misc_register(&pkt_misc);
+	if (ret) {
+		pr_err("unable to register misc device\n");
+		goto out_misc;
+	}
+
+	pkt_proc = proc_mkdir("driver/"DRIVER_NAME, NULL);
+
+	return 0;
+
+out_misc:
+	pkt_debugfs_cleanup();
+	pkt_sysfs_cleanup();
+out:
+	unregister_blkdev(pktdev_major, DRIVER_NAME);
+out2:
+	mempool_exit(&psd_pool);
+	bioset_exit(&pkt_bio_set);
+	return ret;
+}
+
+static void __exit pkt_exit(void)
+{
+	remove_proc_entry("driver/"DRIVER_NAME, NULL);
+	misc_deregister(&pkt_misc);
+
+	pkt_debugfs_cleanup();
+	pkt_sysfs_cleanup();
+
+	unregister_blkdev(pktdev_major, DRIVER_NAME);
+	mempool_exit(&psd_pool);
+	bioset_exit(&pkt_bio_set);
+}
+
+MODULE_DESCRIPTION("Packet writing layer for CD/DVD drives");
+MODULE_AUTHOR("Jens Axboe <axboe@suse.de>");
+MODULE_LICENSE("GPL");
+
+module_init(pkt_init);
+module_exit(pkt_exit);
diff --git a/drivers/block/ps3vram.c b/drivers/block/ps3vram.c
index c76e0148eada33..574e470b220b09 100644
--- a/drivers/block/ps3vram.c
+++ b/drivers/block/ps3vram.c
@@ -587,6 +587,8 @@ static void ps3vram_submit_bio(struct bio *bio)
 	dev_dbg(&dev->core, "%s\n", __func__);
 
 	bio = bio_split_to_limits(bio);
+	if (!bio)
+		return;
 
 	spin_lock_irq(&priv->lock);
 	busy = !bio_list_empty(&priv->list);
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index e9de9d846b7303..17b677b5d3b221 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1992,6 +1992,9 @@ static int ublk_ctrl_uring_cmd(struct io_uring_cmd *cmd,
 	struct ublksrv_ctrl_cmd *header = (struct ublksrv_ctrl_cmd *)cmd->cmd;
 	int ret = -EINVAL;
 
+	if (issue_flags & IO_URING_F_NONBLOCK)
+		return -EAGAIN;
+
 	ublk_ctrl_cmd_dump(cmd);
 
 	if (!(issue_flags & IO_URING_F_SQE128))
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index e1ea3a7bd9d9f8..b424a6ee27baf2 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1742,6 +1742,8 @@ static void dm_split_and_process_bio(struct mapped_device *md,
 		 * otherwise associated queue_limits won't be imposed.
 		 */
 		bio = bio_split_to_limits(bio);
+		if (!bio)
+			return;
 	}
 
 	init_clone_info(&ci, md, map, bio, is_abnormal);
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 775f1dde190a2e..8af639296b3c85 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -455,6 +455,8 @@ static void md_submit_bio(struct bio *bio)
 	}
 
 	bio = bio_split_to_limits(bio);
+	if (!bio)
+		return;
 
 	if (mddev->ro == MD_RDONLY && unlikely(rw == WRITE)) {
 		if (bio_sectors(bio) != 0)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
index c03093b6813c59..fc39d01e7b63be 100644
--- a/drivers/nvme/host/multipath.c
+++ b/drivers/nvme/host/multipath.c
@@ -376,6 +376,8 @@ static void nvme_ns_head_submit_bio(struct bio *bio)
 	 * pool from the original queue to allocate the bvecs from.
 	 */
 	bio = bio_split_to_limits(bio);
+	if (!bio)
+		return;
 
 	srcu_idx = srcu_read_lock(&head->srcu);
 	ns = nvme_find_path(head);
diff --git a/drivers/s390/block/dcssblk.c b/drivers/s390/block/dcssblk.c
index b392b9f5482e0e..c0f85ffb2b62de 100644
--- a/drivers/s390/block/dcssblk.c
+++ b/drivers/s390/block/dcssblk.c
@@ -865,6 +865,8 @@ dcssblk_submit_bio(struct bio *bio)
 	unsigned long bytes_done;
 
 	bio = bio_split_to_limits(bio);
+	if (!bio)
+		return;
 
 	bytes_done = 0;
 	dev_info = bio->bi_bdev->bd_disk->private_data;
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 22078a28d7cb13..c1da63f6c80800 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -475,6 +475,8 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty);
 extern void bio_set_pages_dirty(struct bio *bio);
 extern void bio_check_pages_dirty(struct bio *bio);
 
+extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
+			       struct bio *src, struct bvec_iter *src_iter);
 extern void bio_copy_data(struct bio *dst, struct bio *src);
 extern void bio_free_pages(struct bio *bio);
 void guard_bio_eod(struct bio *bio);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 301cf1cf4f2fac..43d4e073b1115e 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -1395,6 +1395,7 @@ struct block_device_operations {
 	void (*swap_slot_free_notify) (struct block_device *, unsigned long);
 	int (*report_zones)(struct gendisk *, sector_t sector,
 			unsigned int nr_zones, report_zones_cb cb, void *data);
+	char *(*devnode)(struct gendisk *disk, umode_t *mode);
 	/* returns the length of the identifier or a negative errno: */
 	int (*get_unique_id)(struct gendisk *disk, u8 id[16],
 			enum blk_unique_id id_type);
diff --git a/include/linux/pktcdvd.h b/include/linux/pktcdvd.h
new file mode 100644
index 00000000000000..f9c5ac80d59b39
--- /dev/null
+++ b/include/linux/pktcdvd.h
@@ -0,0 +1,197 @@
+/*
+ * 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/blkdev.h>
+#include <linux/completion.h>
+#include <linux/cdrom.h>
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
+#include <linux/mempool.h>
+#include <uapi/linux/pktcdvd.h>
+
+/* default bio write queue congestion marks */
+#define PKT_WRITE_CONGESTION_ON    10000
+#define PKT_WRITE_CONGESTION_OFF   9000
+
+
+struct packet_settings
+{
+	__u32			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_list		read_queue;
+	struct bio_list		write_queue;
+	sector_t		last_write;	/* The sector where the last write ended */
+	int			successive_reads;
+};
+
+/*
+ * 32 buffers of 2048 bytes
+ */
+#if (PAGE_SIZE % CD_FRAMESIZE) != 0
+#error "PAGE_SIZE must be a multiple of CD_FRAMESIZE"
+#endif
+#define PACKET_MAX_SIZE		128
+#define FRAMES_PER_PAGE		(PAGE_SIZE / CD_FRAMESIZE)
+#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_list		orig_bios;	/* Original bios passed to pkt_make_request */
+						/* 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[PACKET_MAX_SIZE / FRAMES_PER_PAGE];
+
+	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 */
+	bool			congested;	/* Someone is waiting for bio_queue_size
+						 * to drop. */
+	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;
+
+	int			write_congestion_off;
+	int			write_congestion_on;
+
+	struct device		*dev;		/* sysfs pktcdvd[0-7] dev */
+
+	struct dentry		*dfs_d_root;	/* debugfs: devname directory */
+	struct dentry		*dfs_f_info;	/* debugfs: info file */
+};
+
+#endif /* __PKTCDVD_H */
diff --git a/include/uapi/linux/pktcdvd.h b/include/uapi/linux/pktcdvd.h
new file mode 100644
index 00000000000000..9cbb55d21c94af
--- /dev/null
+++ b/include/uapi/linux/pktcdvd.h
@@ -0,0 +1,112 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * 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 _UAPI__PKTCDVD_H
+#define _UAPI__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 successfully 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)
+
+
+#endif /* _UAPI__PKTCDVD_H */