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pktcdvd.c
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pktcdvd.c
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/*
* Copyright (C) 2000 Jens Axboe <[email protected]>
* Copyright (C) 2001-2004 Peter Osterlund <[email protected]>
* Copyright (C) 2006 Thomas Maier <[email protected]>
*
* 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,
* typically ide-cd.c or 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);
}
/*
* create and register a pktcdvd kernel object.
*/
static struct pktcdvd_kobj* pkt_kobj_create(struct pktcdvd_device *pd,
const char* name,
struct kobject* parent,
struct kobj_type* ktype)
{
struct pktcdvd_kobj *p;
int error;
p = kzalloc(sizeof(*p), GFP_KERNEL);
if (!p)
return NULL;
p->pd = pd;
error = kobject_init_and_add(&p->kobj, ktype, parent, "%s", name);
if (error) {
kobject_put(&p->kobj);
return NULL;
}
kobject_uevent(&p->kobj, KOBJ_ADD);
return p;
}
/*
* remove a pktcdvd kernel object.
*/
static void pkt_kobj_remove(struct pktcdvd_kobj *p)
{
if (p)
kobject_put(&p->kobj);
}
/*
* default release function for pktcdvd kernel objects.
*/
static void pkt_kobj_release(struct kobject *kobj)
{
kfree(to_pktcdvdkobj(kobj));
}
/**********************************************************
*
* sysfs interface for pktcdvd
* by (C) 2006 Thomas Maier <[email protected]>
*
**********************************************************/
#define DEF_ATTR(_obj,_name,_mode) \
static struct attribute _obj = { .name = _name, .mode = _mode }
/**********************************************************
/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
**********************************************************/
DEF_ATTR(kobj_pkt_attr_st1, "reset", 0200);
DEF_ATTR(kobj_pkt_attr_st2, "packets_started", 0444);
DEF_ATTR(kobj_pkt_attr_st3, "packets_finished", 0444);
DEF_ATTR(kobj_pkt_attr_st4, "kb_written", 0444);
DEF_ATTR(kobj_pkt_attr_st5, "kb_read", 0444);
DEF_ATTR(kobj_pkt_attr_st6, "kb_read_gather", 0444);
static struct attribute *kobj_pkt_attrs_stat[] = {
&kobj_pkt_attr_st1,
&kobj_pkt_attr_st2,
&kobj_pkt_attr_st3,
&kobj_pkt_attr_st4,
&kobj_pkt_attr_st5,
&kobj_pkt_attr_st6,
NULL
};
DEF_ATTR(kobj_pkt_attr_wq1, "size", 0444);
DEF_ATTR(kobj_pkt_attr_wq2, "congestion_off", 0644);
DEF_ATTR(kobj_pkt_attr_wq3, "congestion_on", 0644);
static struct attribute *kobj_pkt_attrs_wqueue[] = {
&kobj_pkt_attr_wq1,
&kobj_pkt_attr_wq2,
&kobj_pkt_attr_wq3,
NULL
};
static ssize_t kobj_pkt_show(struct kobject *kobj,
struct attribute *attr, char *data)
{
struct pktcdvd_device *pd = to_pktcdvdkobj(kobj)->pd;
int n = 0;
int v;
if (strcmp(attr->name, "packets_started") == 0) {
n = sprintf(data, "%lu\n", pd->stats.pkt_started);
} else if (strcmp(attr->name, "packets_finished") == 0) {
n = sprintf(data, "%lu\n", pd->stats.pkt_ended);
} else if (strcmp(attr->name, "kb_written") == 0) {
n = sprintf(data, "%lu\n", pd->stats.secs_w >> 1);
} else if (strcmp(attr->name, "kb_read") == 0) {
n = sprintf(data, "%lu\n", pd->stats.secs_r >> 1);
} else if (strcmp(attr->name, "kb_read_gather") == 0) {
n = sprintf(data, "%lu\n", pd->stats.secs_rg >> 1);
} else if (strcmp(attr->name, "size") == 0) {
spin_lock(&pd->lock);
v = pd->bio_queue_size;
spin_unlock(&pd->lock);
n = sprintf(data, "%d\n", v);
} else if (strcmp(attr->name, "congestion_off") == 0) {
spin_lock(&pd->lock);
v = pd->write_congestion_off;
spin_unlock(&pd->lock);
n = sprintf(data, "%d\n", v);
} else if (strcmp(attr->name, "congestion_on") == 0) {
spin_lock(&pd->lock);
v = pd->write_congestion_on;
spin_unlock(&pd->lock);
n = sprintf(data, "%d\n", v);
}
return n;
}
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 kobj_pkt_store(struct kobject *kobj,
struct attribute *attr,
const char *data, size_t len)
{
struct pktcdvd_device *pd = to_pktcdvdkobj(kobj)->pd;
int val;
if (strcmp(attr->name, "reset") == 0 && 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;
} else if (strcmp(attr->name, "congestion_off") == 0
&& sscanf(data, "%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);
} else if (strcmp(attr->name, "congestion_on") == 0
&& sscanf(data, "%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 const struct sysfs_ops kobj_pkt_ops = {
.show = kobj_pkt_show,
.store = kobj_pkt_store
};
static struct kobj_type kobj_pkt_type_stat = {
.release = pkt_kobj_release,
.sysfs_ops = &kobj_pkt_ops,
.default_attrs = kobj_pkt_attrs_stat
};
static struct kobj_type kobj_pkt_type_wqueue = {
.release = pkt_kobj_release,
.sysfs_ops = &kobj_pkt_ops,
.default_attrs = kobj_pkt_attrs_wqueue
};
static void pkt_sysfs_dev_new(struct pktcdvd_device *pd)
{
if (class_pktcdvd) {
pd->dev = device_create(class_pktcdvd, NULL, MKDEV(0, 0), NULL,
"%s", pd->name);
if (IS_ERR(pd->dev))
pd->dev = NULL;
}
if (pd->dev) {
pd->kobj_stat = pkt_kobj_create(pd, "stat",
&pd->dev->kobj,
&kobj_pkt_type_stat);
pd->kobj_wqueue = pkt_kobj_create(pd, "write_queue",
&pd->dev->kobj,
&kobj_pkt_type_wqueue);
}
}
static void pkt_sysfs_dev_remove(struct pktcdvd_device *pd)
{
pkt_kobj_remove(pd->kobj_stat);
pkt_kobj_remove(pd->kobj_wqueue);
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(GFP_KERNEL, frames);
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++) {
struct bio *bio = bio_kmalloc(GFP_KERNEL, 1);
if (!bio)
goto no_rd_bio;
pkt->r_bios[i] = bio;
}
return pkt;
no_rd_bio:
for (i = 0; i < frames; i++) {
struct bio *bio = pkt->r_bios[i];
if (bio)
bio_put(bio);
}
no_page:
for (i = 0; i < frames / FRAMES_PER_PAGE; i++)
if (pkt->pages[i])
__free_page(pkt->pages[i]);
bio_put(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++) {
struct bio *bio = pkt->r_bios[i];
if (bio)
bio_put(bio);
}
for (i = 0; i < pkt->frames / FRAMES_PER_PAGE; i++)
__free_page(pkt->pages[i]);
bio_put(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 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);
if (cgc->buflen) {
ret = blk_rq_map_kern(q, rq, cgc->buffer, cgc->buflen,
GFP_NOIO);
if (ret)
goto out;
}
scsi_req(rq)->cmd_len = COMMAND_SIZE(cgc->cmd[0]);
memcpy(scsi_req(rq)->cmd, cgc->cmd, CDROM_PACKET_SIZE);
rq->timeout = 60*HZ;
if (cgc->quiet)
rq->rq_flags |= RQF_QUIET;
blk_execute_rq(pd->bdev->bd_disk, rq, 0);
if (scsi_req(rq)->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);
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++;
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));