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linux-zen-desktop/arch/um/drivers/ubd_kern.c

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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2018 Cambridge Greys Ltd
* Copyright (C) 2015-2016 Anton Ivanov (aivanov@brocade.com)
* Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
*/
/* 2001-09-28...2002-04-17
* Partition stuff by James_McMechan@hotmail.com
* old style ubd by setting UBD_SHIFT to 0
* 2002-09-27...2002-10-18 massive tinkering for 2.5
* partitions have changed in 2.5
* 2003-01-29 more tinkering for 2.5.59-1
* This should now address the sysfs problems and has
* the symlink for devfs to allow for booting with
* the common /dev/ubd/discX/... names rather than
* only /dev/ubdN/discN this version also has lots of
* clean ups preparing for ubd-many.
* James McMechan
*/
#define UBD_SHIFT 4
#include <linux/module.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/ata.h>
#include <linux/hdreg.h>
#include <linux/major.h>
#include <linux/cdrom.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/platform_device.h>
#include <linux/scatterlist.h>
#include <asm/tlbflush.h>
#include <kern_util.h>
#include "mconsole_kern.h"
#include <init.h>
#include <irq_kern.h>
#include "ubd.h"
#include <os.h>
#include "cow.h"
/* Max request size is determined by sector mask - 32K */
#define UBD_MAX_REQUEST (8 * sizeof(long))
struct io_desc {
char *buffer;
unsigned long length;
unsigned long sector_mask;
unsigned long long cow_offset;
unsigned long bitmap_words[2];
};
struct io_thread_req {
struct request *req;
int fds[2];
unsigned long offsets[2];
unsigned long long offset;
int sectorsize;
int error;
int desc_cnt;
/* io_desc has to be the last element of the struct */
struct io_desc io_desc[];
};
static struct io_thread_req * (*irq_req_buffer)[];
static struct io_thread_req *irq_remainder;
static int irq_remainder_size;
static struct io_thread_req * (*io_req_buffer)[];
static struct io_thread_req *io_remainder;
static int io_remainder_size;
static inline int ubd_test_bit(__u64 bit, unsigned char *data)
{
__u64 n;
int bits, off;
bits = sizeof(data[0]) * 8;
n = bit / bits;
off = bit % bits;
return (data[n] & (1 << off)) != 0;
}
static inline void ubd_set_bit(__u64 bit, unsigned char *data)
{
__u64 n;
int bits, off;
bits = sizeof(data[0]) * 8;
n = bit / bits;
off = bit % bits;
data[n] |= (1 << off);
}
/*End stuff from ubd_user.h*/
#define DRIVER_NAME "uml-blkdev"
static DEFINE_MUTEX(ubd_lock);
static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
static int ubd_open(struct gendisk *disk, blk_mode_t mode);
static void ubd_release(struct gendisk *disk);
static int ubd_ioctl(struct block_device *bdev, blk_mode_t mode,
unsigned int cmd, unsigned long arg);
static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
#define MAX_DEV (16)
static const struct block_device_operations ubd_blops = {
.owner = THIS_MODULE,
.open = ubd_open,
.release = ubd_release,
.ioctl = ubd_ioctl,
.compat_ioctl = blkdev_compat_ptr_ioctl,
.getgeo = ubd_getgeo,
};
/* Protected by ubd_lock */
static struct gendisk *ubd_gendisk[MAX_DEV];
#ifdef CONFIG_BLK_DEV_UBD_SYNC
#define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
.cl = 1 })
#else
#define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
.cl = 1 })
#endif
static struct openflags global_openflags = OPEN_FLAGS;
struct cow {
/* backing file name */
char *file;
/* backing file fd */
int fd;
unsigned long *bitmap;
unsigned long bitmap_len;
int bitmap_offset;
int data_offset;
};
#define MAX_SG 64
struct ubd {
/* name (and fd, below) of the file opened for writing, either the
* backing or the cow file. */
char *file;
char *serial;
int count;
int fd;
__u64 size;
struct openflags boot_openflags;
struct openflags openflags;
unsigned shared:1;
unsigned no_cow:1;
unsigned no_trim:1;
struct cow cow;
struct platform_device pdev;
struct request_queue *queue;
struct blk_mq_tag_set tag_set;
spinlock_t lock;
};
#define DEFAULT_COW { \
.file = NULL, \
.fd = -1, \
.bitmap = NULL, \
.bitmap_offset = 0, \
.data_offset = 0, \
}
#define DEFAULT_UBD { \
.file = NULL, \
.serial = NULL, \
.count = 0, \
.fd = -1, \
.size = -1, \
.boot_openflags = OPEN_FLAGS, \
.openflags = OPEN_FLAGS, \
.no_cow = 0, \
.no_trim = 0, \
.shared = 0, \
.cow = DEFAULT_COW, \
.lock = __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
}
/* Protected by ubd_lock */
static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd);
static int fake_ide_setup(char *str)
{
pr_warn("The fake_ide option has been removed\n");
return 1;
}
__setup("fake_ide", fake_ide_setup);
__uml_help(fake_ide_setup,
"fake_ide\n"
" Obsolete stub.\n\n"
);
static int parse_unit(char **ptr)
{
char *str = *ptr, *end;
int n = -1;
if(isdigit(*str)) {
n = simple_strtoul(str, &end, 0);
if(end == str)
return -1;
*ptr = end;
}
else if (('a' <= *str) && (*str <= 'z')) {
n = *str - 'a';
str++;
*ptr = str;
}
return n;
}
/* If *index_out == -1 at exit, the passed option was a general one;
* otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
* should not be freed on exit.
*/
static int ubd_setup_common(char *str, int *index_out, char **error_out)
{
struct ubd *ubd_dev;
struct openflags flags = global_openflags;
char *file, *backing_file, *serial;
int n, err = 0, i;
if(index_out) *index_out = -1;
n = *str;
if(n == '='){
str++;
if(!strcmp(str, "sync")){
global_openflags = of_sync(global_openflags);
return err;
}
pr_warn("fake major not supported any more\n");
return 0;
}
n = parse_unit(&str);
if(n < 0){
*error_out = "Couldn't parse device number";
return -EINVAL;
}
if(n >= MAX_DEV){
*error_out = "Device number out of range";
return 1;
}
err = -EBUSY;
mutex_lock(&ubd_lock);
ubd_dev = &ubd_devs[n];
if(ubd_dev->file != NULL){
*error_out = "Device is already configured";
goto out;
}
if (index_out)
*index_out = n;
err = -EINVAL;
for (i = 0; i < sizeof("rscdt="); i++) {
switch (*str) {
case 'r':
flags.w = 0;
break;
case 's':
flags.s = 1;
break;
case 'd':
ubd_dev->no_cow = 1;
break;
case 'c':
ubd_dev->shared = 1;
break;
case 't':
ubd_dev->no_trim = 1;
break;
case '=':
str++;
goto break_loop;
default:
*error_out = "Expected '=' or flag letter "
"(r, s, c, t or d)";
goto out;
}
str++;
}
if (*str == '=')
*error_out = "Too many flags specified";
else
*error_out = "Missing '='";
goto out;
break_loop:
file = strsep(&str, ",:");
if (*file == '\0')
file = NULL;
backing_file = strsep(&str, ",:");
if (backing_file && *backing_file == '\0')
backing_file = NULL;
serial = strsep(&str, ",:");
if (serial && *serial == '\0')
serial = NULL;
if (backing_file && ubd_dev->no_cow) {
*error_out = "Can't specify both 'd' and a cow file";
goto out;
}
err = 0;
ubd_dev->file = file;
ubd_dev->cow.file = backing_file;
ubd_dev->serial = serial;
ubd_dev->boot_openflags = flags;
out:
mutex_unlock(&ubd_lock);
return err;
}
static int ubd_setup(char *str)
{
char *error;
int err;
err = ubd_setup_common(str, NULL, &error);
if(err)
printk(KERN_ERR "Failed to initialize device with \"%s\" : "
"%s\n", str, error);
return 1;
}
__setup("ubd", ubd_setup);
__uml_help(ubd_setup,
"ubd<n><flags>=<filename>[(:|,)<filename2>][(:|,)<serial>]\n"
" This is used to associate a device with a file in the underlying\n"
" filesystem. When specifying two filenames, the first one is the\n"
" COW name and the second is the backing file name. As separator you can\n"
" use either a ':' or a ',': the first one allows writing things like;\n"
" ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
" while with a ',' the shell would not expand the 2nd '~'.\n"
" When using only one filename, UML will detect whether to treat it like\n"
" a COW file or a backing file. To override this detection, add the 'd'\n"
" flag:\n"
" ubd0d=BackingFile\n"
" Usually, there is a filesystem in the file, but \n"
" that's not required. Swap devices containing swap files can be\n"
" specified like this. Also, a file which doesn't contain a\n"
" filesystem can have its contents read in the virtual \n"
" machine by running 'dd' on the device. <n> must be in the range\n"
" 0 to 7. Appending an 'r' to the number will cause that device\n"
" to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
" an 's' will cause data to be written to disk on the host immediately.\n"
" 'c' will cause the device to be treated as being shared between multiple\n"
" UMLs and file locking will be turned off - this is appropriate for a\n"
" cluster filesystem and inappropriate at almost all other times.\n\n"
" 't' will disable trim/discard support on the device (enabled by default).\n\n"
" An optional device serial number can be exposed using the serial parameter\n"
" on the cmdline which is exposed as a sysfs entry. This is particularly\n"
" useful when a unique number should be given to the device. Note when\n"
" specifying a label, the filename2 must be also presented. It can be\n"
" an empty string, in which case the backing file is not used:\n"
" ubd0=File,,Serial\n"
);
static int udb_setup(char *str)
{
printk("udb%s specified on command line is almost certainly a ubd -> "
"udb TYPO\n", str);
return 1;
}
__setup("udb", udb_setup);
__uml_help(udb_setup,
"udb\n"
" This option is here solely to catch ubd -> udb typos, which can be\n"
" to impossible to catch visually unless you specifically look for\n"
" them. The only result of any option starting with 'udb' is an error\n"
" in the boot output.\n\n"
);
/* Only changed by ubd_init, which is an initcall. */
static int thread_fd = -1;
/* Function to read several request pointers at a time
* handling fractional reads if (and as) needed
*/
static int bulk_req_safe_read(
int fd,
struct io_thread_req * (*request_buffer)[],
struct io_thread_req **remainder,
int *remainder_size,
int max_recs
)
{
int n = 0;
int res = 0;
if (*remainder_size > 0) {
memmove(
(char *) request_buffer,
(char *) remainder, *remainder_size
);
n = *remainder_size;
}
res = os_read_file(
fd,
((char *) request_buffer) + *remainder_size,
sizeof(struct io_thread_req *)*max_recs
- *remainder_size
);
if (res > 0) {
n += res;
if ((n % sizeof(struct io_thread_req *)) > 0) {
/*
* Read somehow returned not a multiple of dword
* theoretically possible, but never observed in the
* wild, so read routine must be able to handle it
*/
*remainder_size = n % sizeof(struct io_thread_req *);
WARN(*remainder_size > 0, "UBD IPC read returned a partial result");
memmove(
remainder,
((char *) request_buffer) +
(n/sizeof(struct io_thread_req *))*sizeof(struct io_thread_req *),
*remainder_size
);
n = n - *remainder_size;
}
} else {
n = res;
}
return n;
}
/* Called without dev->lock held, and only in interrupt context. */
static void ubd_handler(void)
{
int n;
int count;
while(1){
n = bulk_req_safe_read(
thread_fd,
irq_req_buffer,
&irq_remainder,
&irq_remainder_size,
UBD_REQ_BUFFER_SIZE
);
if (n < 0) {
if(n == -EAGAIN)
break;
printk(KERN_ERR "spurious interrupt in ubd_handler, "
"err = %d\n", -n);
return;
}
for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
struct io_thread_req *io_req = (*irq_req_buffer)[count];
if ((io_req->error == BLK_STS_NOTSUPP) && (req_op(io_req->req) == REQ_OP_DISCARD)) {
blk_queue_max_discard_sectors(io_req->req->q, 0);
blk_queue_max_write_zeroes_sectors(io_req->req->q, 0);
}
blk_mq_end_request(io_req->req, io_req->error);
kfree(io_req);
}
}
}
static irqreturn_t ubd_intr(int irq, void *dev)
{
ubd_handler();
return IRQ_HANDLED;
}
/* Only changed by ubd_init, which is an initcall. */
static int io_pid = -1;
static void kill_io_thread(void)
{
if(io_pid != -1)
os_kill_process(io_pid, 1);
}
__uml_exitcall(kill_io_thread);
static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
{
char *file;
int fd;
int err;
__u32 version;
__u32 align;
char *backing_file;
time64_t mtime;
unsigned long long size;
int sector_size;
int bitmap_offset;
if (ubd_dev->file && ubd_dev->cow.file) {
file = ubd_dev->cow.file;
goto out;
}
fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
if (fd < 0)
return fd;
err = read_cow_header(file_reader, &fd, &version, &backing_file, \
&mtime, &size, &sector_size, &align, &bitmap_offset);
os_close_file(fd);
if(err == -EINVAL)
file = ubd_dev->file;
else
file = backing_file;
out:
return os_file_size(file, size_out);
}
static int read_cow_bitmap(int fd, void *buf, int offset, int len)
{
int err;
err = os_pread_file(fd, buf, len, offset);
if (err < 0)
return err;
return 0;
}
static int backing_file_mismatch(char *file, __u64 size, time64_t mtime)
{
time64_t modtime;
unsigned long long actual;
int err;
err = os_file_modtime(file, &modtime);
if (err < 0) {
printk(KERN_ERR "Failed to get modification time of backing "
"file \"%s\", err = %d\n", file, -err);
return err;
}
err = os_file_size(file, &actual);
if (err < 0) {
printk(KERN_ERR "Failed to get size of backing file \"%s\", "
"err = %d\n", file, -err);
return err;
}
if (actual != size) {
/*__u64 can be a long on AMD64 and with %lu GCC complains; so
* the typecast.*/
printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
"vs backing file\n", (unsigned long long) size, actual);
return -EINVAL;
}
if (modtime != mtime) {
printk(KERN_ERR "mtime mismatch (%lld vs %lld) of COW header vs "
"backing file\n", mtime, modtime);
return -EINVAL;
}
return 0;
}
static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
{
struct uml_stat buf1, buf2;
int err;
if (from_cmdline == NULL)
return 0;
if (!strcmp(from_cmdline, from_cow))
return 0;
err = os_stat_file(from_cmdline, &buf1);
if (err < 0) {
printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
-err);
return 0;
}
err = os_stat_file(from_cow, &buf2);
if (err < 0) {
printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
-err);
return 1;
}
if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
return 0;
printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
"\"%s\" specified in COW header of \"%s\"\n",
from_cmdline, from_cow, cow);
return 1;
}
static int open_ubd_file(char *file, struct openflags *openflags, int shared,
char **backing_file_out, int *bitmap_offset_out,
unsigned long *bitmap_len_out, int *data_offset_out,
int *create_cow_out)
{
time64_t mtime;
unsigned long long size;
__u32 version, align;
char *backing_file;
int fd, err, sectorsize, asked_switch, mode = 0644;
fd = os_open_file(file, *openflags, mode);
if (fd < 0) {
if ((fd == -ENOENT) && (create_cow_out != NULL))
*create_cow_out = 1;
if (!openflags->w ||
((fd != -EROFS) && (fd != -EACCES)))
return fd;
openflags->w = 0;
fd = os_open_file(file, *openflags, mode);
if (fd < 0)
return fd;
}
if (shared)
printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
else {
err = os_lock_file(fd, openflags->w);
if (err < 0) {
printk(KERN_ERR "Failed to lock '%s', err = %d\n",
file, -err);
goto out_close;
}
}
/* Successful return case! */
if (backing_file_out == NULL)
return fd;
err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
&size, &sectorsize, &align, bitmap_offset_out);
if (err && (*backing_file_out != NULL)) {
printk(KERN_ERR "Failed to read COW header from COW file "
"\"%s\", errno = %d\n", file, -err);
goto out_close;
}
if (err)
return fd;
asked_switch = path_requires_switch(*backing_file_out, backing_file,
file);
/* Allow switching only if no mismatch. */
if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
mtime)) {
printk(KERN_ERR "Switching backing file to '%s'\n",
*backing_file_out);
err = write_cow_header(file, fd, *backing_file_out,
sectorsize, align, &size);
if (err) {
printk(KERN_ERR "Switch failed, errno = %d\n", -err);
goto out_close;
}
} else {
*backing_file_out = backing_file;
err = backing_file_mismatch(*backing_file_out, size, mtime);
if (err)
goto out_close;
}
cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
bitmap_len_out, data_offset_out);
return fd;
out_close:
os_close_file(fd);
return err;
}
static int create_cow_file(char *cow_file, char *backing_file,
struct openflags flags,
int sectorsize, int alignment, int *bitmap_offset_out,
unsigned long *bitmap_len_out, int *data_offset_out)
{
int err, fd;
flags.c = 1;
fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
if (fd < 0) {
err = fd;
printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
cow_file, -err);
goto out;
}
err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
bitmap_offset_out, bitmap_len_out,
data_offset_out);
if (!err)
return fd;
os_close_file(fd);
out:
return err;
}
static void ubd_close_dev(struct ubd *ubd_dev)
{
os_close_file(ubd_dev->fd);
if(ubd_dev->cow.file == NULL)
return;
os_close_file(ubd_dev->cow.fd);
vfree(ubd_dev->cow.bitmap);
ubd_dev->cow.bitmap = NULL;
}
static int ubd_open_dev(struct ubd *ubd_dev)
{
struct openflags flags;
char **back_ptr;
int err, create_cow, *create_ptr;
int fd;
ubd_dev->openflags = ubd_dev->boot_openflags;
create_cow = 0;
create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
back_ptr, &ubd_dev->cow.bitmap_offset,
&ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
create_ptr);
if((fd == -ENOENT) && create_cow){
fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
ubd_dev->openflags, SECTOR_SIZE, PAGE_SIZE,
&ubd_dev->cow.bitmap_offset,
&ubd_dev->cow.bitmap_len,
&ubd_dev->cow.data_offset);
if(fd >= 0){
printk(KERN_INFO "Creating \"%s\" as COW file for "
"\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
}
}
if(fd < 0){
printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
-fd);
return fd;
}
ubd_dev->fd = fd;
if(ubd_dev->cow.file != NULL){
blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
err = -ENOMEM;
ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
if(ubd_dev->cow.bitmap == NULL){
printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
goto error;
}
flush_tlb_kernel_vm();
err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
ubd_dev->cow.bitmap_offset,
ubd_dev->cow.bitmap_len);
if(err < 0)
goto error;
flags = ubd_dev->openflags;
flags.w = 0;
err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
NULL, NULL, NULL, NULL);
if(err < 0) goto error;
ubd_dev->cow.fd = err;
}
if (ubd_dev->no_trim == 0) {
ubd_dev->queue->limits.discard_granularity = SECTOR_SIZE;
blk_queue_max_discard_sectors(ubd_dev->queue, UBD_MAX_REQUEST);
blk_queue_max_write_zeroes_sectors(ubd_dev->queue, UBD_MAX_REQUEST);
}
blk_queue_flag_set(QUEUE_FLAG_NONROT, ubd_dev->queue);
return 0;
error:
os_close_file(ubd_dev->fd);
return err;
}
static void ubd_device_release(struct device *dev)
{
struct ubd *ubd_dev = dev_get_drvdata(dev);
blk_mq_free_tag_set(&ubd_dev->tag_set);
*ubd_dev = ((struct ubd) DEFAULT_UBD);
}
static ssize_t serial_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct gendisk *disk = dev_to_disk(dev);
struct ubd *ubd_dev = disk->private_data;
if (!ubd_dev)
return 0;
return sprintf(buf, "%s", ubd_dev->serial);
}
static DEVICE_ATTR_RO(serial);
static struct attribute *ubd_attrs[] = {
&dev_attr_serial.attr,
NULL,
};
static umode_t ubd_attrs_are_visible(struct kobject *kobj,
struct attribute *a, int n)
{
return a->mode;
}
static const struct attribute_group ubd_attr_group = {
.attrs = ubd_attrs,
.is_visible = ubd_attrs_are_visible,
};
static const struct attribute_group *ubd_attr_groups[] = {
&ubd_attr_group,
NULL,
};
static int ubd_disk_register(int major, u64 size, int unit,
struct gendisk *disk)
{
disk->major = major;
disk->first_minor = unit << UBD_SHIFT;
disk->minors = 1 << UBD_SHIFT;
disk->fops = &ubd_blops;
set_capacity(disk, size / 512);
sprintf(disk->disk_name, "ubd%c", 'a' + unit);
ubd_devs[unit].pdev.id = unit;
ubd_devs[unit].pdev.name = DRIVER_NAME;
ubd_devs[unit].pdev.dev.release = ubd_device_release;
dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
platform_device_register(&ubd_devs[unit].pdev);
disk->private_data = &ubd_devs[unit];
disk->queue = ubd_devs[unit].queue;
return device_add_disk(&ubd_devs[unit].pdev.dev, disk, ubd_attr_groups);
}
#define ROUND_BLOCK(n) ((n + (SECTOR_SIZE - 1)) & (-SECTOR_SIZE))
static const struct blk_mq_ops ubd_mq_ops = {
.queue_rq = ubd_queue_rq,
};
static int ubd_add(int n, char **error_out)
{
struct ubd *ubd_dev = &ubd_devs[n];
struct gendisk *disk;
int err = 0;
if(ubd_dev->file == NULL)
goto out;
err = ubd_file_size(ubd_dev, &ubd_dev->size);
if(err < 0){
*error_out = "Couldn't determine size of device's file";
goto out;
}
ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
ubd_dev->tag_set.ops = &ubd_mq_ops;
ubd_dev->tag_set.queue_depth = 64;
ubd_dev->tag_set.numa_node = NUMA_NO_NODE;
ubd_dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
ubd_dev->tag_set.driver_data = ubd_dev;
ubd_dev->tag_set.nr_hw_queues = 1;
err = blk_mq_alloc_tag_set(&ubd_dev->tag_set);
if (err)
goto out;
disk = blk_mq_alloc_disk(&ubd_dev->tag_set, ubd_dev);
if (IS_ERR(disk)) {
err = PTR_ERR(disk);
goto out_cleanup_tags;
}
ubd_dev->queue = disk->queue;
blk_queue_write_cache(ubd_dev->queue, true, false);
blk_queue_max_segments(ubd_dev->queue, MAX_SG);
blk_queue_segment_boundary(ubd_dev->queue, PAGE_SIZE - 1);
err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, disk);
if (err)
goto out_cleanup_disk;
ubd_gendisk[n] = disk;
return 0;
out_cleanup_disk:
put_disk(disk);
out_cleanup_tags:
blk_mq_free_tag_set(&ubd_dev->tag_set);
out:
return err;
}
static int ubd_config(char *str, char **error_out)
{
int n, ret;
/* This string is possibly broken up and stored, so it's only
* freed if ubd_setup_common fails, or if only general options
* were set.
*/
str = kstrdup(str, GFP_KERNEL);
if (str == NULL) {
*error_out = "Failed to allocate memory";
return -ENOMEM;
}
ret = ubd_setup_common(str, &n, error_out);
if (ret)
goto err_free;
if (n == -1) {
ret = 0;
goto err_free;
}
mutex_lock(&ubd_lock);
ret = ubd_add(n, error_out);
if (ret)
ubd_devs[n].file = NULL;
mutex_unlock(&ubd_lock);
out:
return ret;
err_free:
kfree(str);
goto out;
}
static int ubd_get_config(char *name, char *str, int size, char **error_out)
{
struct ubd *ubd_dev;
int n, len = 0;
n = parse_unit(&name);
if((n >= MAX_DEV) || (n < 0)){
*error_out = "ubd_get_config : device number out of range";
return -1;
}
ubd_dev = &ubd_devs[n];
mutex_lock(&ubd_lock);
if(ubd_dev->file == NULL){
CONFIG_CHUNK(str, size, len, "", 1);
goto out;
}
CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
if(ubd_dev->cow.file != NULL){
CONFIG_CHUNK(str, size, len, ",", 0);
CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
}
else CONFIG_CHUNK(str, size, len, "", 1);
out:
mutex_unlock(&ubd_lock);
return len;
}
static int ubd_id(char **str, int *start_out, int *end_out)
{
int n;
n = parse_unit(str);
*start_out = 0;
*end_out = MAX_DEV - 1;
return n;
}
static int ubd_remove(int n, char **error_out)
{
struct gendisk *disk = ubd_gendisk[n];
struct ubd *ubd_dev;
int err = -ENODEV;
mutex_lock(&ubd_lock);
ubd_dev = &ubd_devs[n];
if(ubd_dev->file == NULL)
goto out;
/* you cannot remove a open disk */
err = -EBUSY;
if(ubd_dev->count > 0)
goto out;
ubd_gendisk[n] = NULL;
if(disk != NULL){
del_gendisk(disk);
put_disk(disk);
}
err = 0;
platform_device_unregister(&ubd_dev->pdev);
out:
mutex_unlock(&ubd_lock);
return err;
}
/* All these are called by mconsole in process context and without
* ubd-specific locks. The structure itself is const except for .list.
*/
static struct mc_device ubd_mc = {
.list = LIST_HEAD_INIT(ubd_mc.list),
.name = "ubd",
.config = ubd_config,
.get_config = ubd_get_config,
.id = ubd_id,
.remove = ubd_remove,
};
static int __init ubd_mc_init(void)
{
mconsole_register_dev(&ubd_mc);
return 0;
}
__initcall(ubd_mc_init);
static int __init ubd0_init(void)
{
struct ubd *ubd_dev = &ubd_devs[0];
mutex_lock(&ubd_lock);
if(ubd_dev->file == NULL)
ubd_dev->file = "root_fs";
mutex_unlock(&ubd_lock);
return 0;
}
__initcall(ubd0_init);
/* Used in ubd_init, which is an initcall */
static struct platform_driver ubd_driver = {
.driver = {
.name = DRIVER_NAME,
},
};
static int __init ubd_init(void)
{
char *error;
int i, err;
if (register_blkdev(UBD_MAJOR, "ubd"))
return -1;
irq_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
sizeof(struct io_thread_req *),
GFP_KERNEL
);
irq_remainder = 0;
if (irq_req_buffer == NULL) {
printk(KERN_ERR "Failed to initialize ubd buffering\n");
return -1;
}
io_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
sizeof(struct io_thread_req *),
GFP_KERNEL
);
io_remainder = 0;
if (io_req_buffer == NULL) {
printk(KERN_ERR "Failed to initialize ubd buffering\n");
return -1;
}
platform_driver_register(&ubd_driver);
mutex_lock(&ubd_lock);
for (i = 0; i < MAX_DEV; i++){
err = ubd_add(i, &error);
if(err)
printk(KERN_ERR "Failed to initialize ubd device %d :"
"%s\n", i, error);
}
mutex_unlock(&ubd_lock);
return 0;
}
late_initcall(ubd_init);
static int __init ubd_driver_init(void){
unsigned long stack;
int err;
/* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
if(global_openflags.s){
printk(KERN_INFO "ubd: Synchronous mode\n");
/* Letting ubd=sync be like using ubd#s= instead of ubd#= is
* enough. So use anyway the io thread. */
}
stack = alloc_stack(0, 0);
io_pid = start_io_thread(stack + PAGE_SIZE, &thread_fd);
if(io_pid < 0){
printk(KERN_ERR
"ubd : Failed to start I/O thread (errno = %d) - "
"falling back to synchronous I/O\n", -io_pid);
io_pid = -1;
return 0;
}
err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
0, "ubd", ubd_devs);
if(err < 0)
printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
return 0;
}
device_initcall(ubd_driver_init);
static int ubd_open(struct gendisk *disk, blk_mode_t mode)
{
struct ubd *ubd_dev = disk->private_data;
int err = 0;
mutex_lock(&ubd_mutex);
if(ubd_dev->count == 0){
err = ubd_open_dev(ubd_dev);
if(err){
printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
disk->disk_name, ubd_dev->file, -err);
goto out;
}
}
ubd_dev->count++;
set_disk_ro(disk, !ubd_dev->openflags.w);
out:
mutex_unlock(&ubd_mutex);
return err;
}
static void ubd_release(struct gendisk *disk)
{
struct ubd *ubd_dev = disk->private_data;
mutex_lock(&ubd_mutex);
if(--ubd_dev->count == 0)
ubd_close_dev(ubd_dev);
mutex_unlock(&ubd_mutex);
}
static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
__u64 *cow_offset, unsigned long *bitmap,
__u64 bitmap_offset, unsigned long *bitmap_words,
__u64 bitmap_len)
{
__u64 sector = io_offset >> SECTOR_SHIFT;
int i, update_bitmap = 0;
for (i = 0; i < length >> SECTOR_SHIFT; i++) {
if(cow_mask != NULL)
ubd_set_bit(i, (unsigned char *) cow_mask);
if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
continue;
update_bitmap = 1;
ubd_set_bit(sector + i, (unsigned char *) bitmap);
}
if(!update_bitmap)
return;
*cow_offset = sector / (sizeof(unsigned long) * 8);
/* This takes care of the case where we're exactly at the end of the
* device, and *cow_offset + 1 is off the end. So, just back it up
* by one word. Thanks to Lynn Kerby for the fix and James McMechan
* for the original diagnosis.
*/
if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
sizeof(unsigned long)) - 1))
(*cow_offset)--;
bitmap_words[0] = bitmap[*cow_offset];
bitmap_words[1] = bitmap[*cow_offset + 1];
*cow_offset *= sizeof(unsigned long);
*cow_offset += bitmap_offset;
}
static void cowify_req(struct io_thread_req *req, struct io_desc *segment,
unsigned long offset, unsigned long *bitmap,
__u64 bitmap_offset, __u64 bitmap_len)
{
__u64 sector = offset >> SECTOR_SHIFT;
int i;
if (segment->length > (sizeof(segment->sector_mask) * 8) << SECTOR_SHIFT)
panic("Operation too long");
if (req_op(req->req) == REQ_OP_READ) {
for (i = 0; i < segment->length >> SECTOR_SHIFT; i++) {
if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
ubd_set_bit(i, (unsigned char *)
&segment->sector_mask);
}
} else {
cowify_bitmap(offset, segment->length, &segment->sector_mask,
&segment->cow_offset, bitmap, bitmap_offset,
segment->bitmap_words, bitmap_len);
}
}
static void ubd_map_req(struct ubd *dev, struct io_thread_req *io_req,
struct request *req)
{
struct bio_vec bvec;
struct req_iterator iter;
int i = 0;
unsigned long byte_offset = io_req->offset;
enum req_op op = req_op(req);
if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD) {
io_req->io_desc[0].buffer = NULL;
io_req->io_desc[0].length = blk_rq_bytes(req);
} else {
rq_for_each_segment(bvec, req, iter) {
BUG_ON(i >= io_req->desc_cnt);
io_req->io_desc[i].buffer = bvec_virt(&bvec);
io_req->io_desc[i].length = bvec.bv_len;
i++;
}
}
if (dev->cow.file) {
for (i = 0; i < io_req->desc_cnt; i++) {
cowify_req(io_req, &io_req->io_desc[i], byte_offset,
dev->cow.bitmap, dev->cow.bitmap_offset,
dev->cow.bitmap_len);
byte_offset += io_req->io_desc[i].length;
}
}
}
static struct io_thread_req *ubd_alloc_req(struct ubd *dev, struct request *req,
int desc_cnt)
{
struct io_thread_req *io_req;
int i;
io_req = kmalloc(sizeof(*io_req) +
(desc_cnt * sizeof(struct io_desc)),
GFP_ATOMIC);
if (!io_req)
return NULL;
io_req->req = req;
if (dev->cow.file)
io_req->fds[0] = dev->cow.fd;
else
io_req->fds[0] = dev->fd;
io_req->error = 0;
io_req->sectorsize = SECTOR_SIZE;
io_req->fds[1] = dev->fd;
io_req->offset = (u64) blk_rq_pos(req) << SECTOR_SHIFT;
io_req->offsets[0] = 0;
io_req->offsets[1] = dev->cow.data_offset;
for (i = 0 ; i < desc_cnt; i++) {
io_req->io_desc[i].sector_mask = 0;
io_req->io_desc[i].cow_offset = -1;
}
return io_req;
}
static int ubd_submit_request(struct ubd *dev, struct request *req)
{
int segs = 0;
struct io_thread_req *io_req;
int ret;
enum req_op op = req_op(req);
if (op == REQ_OP_FLUSH)
segs = 0;
else if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD)
segs = 1;
else
segs = blk_rq_nr_phys_segments(req);
io_req = ubd_alloc_req(dev, req, segs);
if (!io_req)
return -ENOMEM;
io_req->desc_cnt = segs;
if (segs)
ubd_map_req(dev, io_req, req);
ret = os_write_file(thread_fd, &io_req, sizeof(io_req));
if (ret != sizeof(io_req)) {
if (ret != -EAGAIN)
pr_err("write to io thread failed: %d\n", -ret);
kfree(io_req);
}
return ret;
}
static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
const struct blk_mq_queue_data *bd)
{
struct ubd *ubd_dev = hctx->queue->queuedata;
struct request *req = bd->rq;
int ret = 0, res = BLK_STS_OK;
blk_mq_start_request(req);
spin_lock_irq(&ubd_dev->lock);
switch (req_op(req)) {
case REQ_OP_FLUSH:
case REQ_OP_READ:
case REQ_OP_WRITE:
case REQ_OP_DISCARD:
case REQ_OP_WRITE_ZEROES:
ret = ubd_submit_request(ubd_dev, req);
break;
default:
WARN_ON_ONCE(1);
res = BLK_STS_NOTSUPP;
}
spin_unlock_irq(&ubd_dev->lock);
if (ret < 0) {
if (ret == -ENOMEM)
res = BLK_STS_RESOURCE;
else
res = BLK_STS_DEV_RESOURCE;
}
return res;
}
static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
{
struct ubd *ubd_dev = bdev->bd_disk->private_data;
geo->heads = 128;
geo->sectors = 32;
geo->cylinders = ubd_dev->size / (128 * 32 * 512);
return 0;
}
static int ubd_ioctl(struct block_device *bdev, blk_mode_t mode,
unsigned int cmd, unsigned long arg)
{
struct ubd *ubd_dev = bdev->bd_disk->private_data;
u16 ubd_id[ATA_ID_WORDS];
switch (cmd) {
struct cdrom_volctrl volume;
case HDIO_GET_IDENTITY:
memset(&ubd_id, 0, ATA_ID_WORDS * 2);
ubd_id[ATA_ID_CYLS] = ubd_dev->size / (128 * 32 * 512);
ubd_id[ATA_ID_HEADS] = 128;
ubd_id[ATA_ID_SECTORS] = 32;
if(copy_to_user((char __user *) arg, (char *) &ubd_id,
sizeof(ubd_id)))
return -EFAULT;
return 0;
case CDROMVOLREAD:
if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
return -EFAULT;
volume.channel0 = 255;
volume.channel1 = 255;
volume.channel2 = 255;
volume.channel3 = 255;
if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
return -EFAULT;
return 0;
}
return -EINVAL;
}
static int map_error(int error_code)
{
switch (error_code) {
case 0:
return BLK_STS_OK;
case ENOSYS:
case EOPNOTSUPP:
return BLK_STS_NOTSUPP;
case ENOSPC:
return BLK_STS_NOSPC;
}
return BLK_STS_IOERR;
}
/*
* Everything from here onwards *IS NOT PART OF THE KERNEL*
*
* The following functions are part of UML hypervisor code.
* All functions from here onwards are executed as a helper
* thread and are not allowed to execute any kernel functions.
*
* Any communication must occur strictly via shared memory and IPC.
*
* Do not add printks, locks, kernel memory operations, etc - it
* will result in unpredictable behaviour and/or crashes.
*/
static int update_bitmap(struct io_thread_req *req, struct io_desc *segment)
{
int n;
if (segment->cow_offset == -1)
return map_error(0);
n = os_pwrite_file(req->fds[1], &segment->bitmap_words,
sizeof(segment->bitmap_words), segment->cow_offset);
if (n != sizeof(segment->bitmap_words))
return map_error(-n);
return map_error(0);
}
static void do_io(struct io_thread_req *req, struct io_desc *desc)
{
char *buf = NULL;
unsigned long len;
int n, nsectors, start, end, bit;
__u64 off;
/* FLUSH is really a special case, we cannot "case" it with others */
if (req_op(req->req) == REQ_OP_FLUSH) {
/* fds[0] is always either the rw image or our cow file */
req->error = map_error(-os_sync_file(req->fds[0]));
return;
}
nsectors = desc->length / req->sectorsize;
start = 0;
do {
bit = ubd_test_bit(start, (unsigned char *) &desc->sector_mask);
end = start;
while((end < nsectors) &&
(ubd_test_bit(end, (unsigned char *) &desc->sector_mask) == bit))
end++;
off = req->offset + req->offsets[bit] +
start * req->sectorsize;
len = (end - start) * req->sectorsize;
if (desc->buffer != NULL)
buf = &desc->buffer[start * req->sectorsize];
switch (req_op(req->req)) {
case REQ_OP_READ:
n = 0;
do {
buf = &buf[n];
len -= n;
n = os_pread_file(req->fds[bit], buf, len, off);
if (n < 0) {
req->error = map_error(-n);
return;
}
} while((n < len) && (n != 0));
if (n < len) memset(&buf[n], 0, len - n);
break;
case REQ_OP_WRITE:
n = os_pwrite_file(req->fds[bit], buf, len, off);
if(n != len){
req->error = map_error(-n);
return;
}
break;
case REQ_OP_DISCARD:
n = os_falloc_punch(req->fds[bit], off, len);
if (n) {
req->error = map_error(-n);
return;
}
break;
case REQ_OP_WRITE_ZEROES:
n = os_falloc_zeroes(req->fds[bit], off, len);
if (n) {
req->error = map_error(-n);
return;
}
break;
default:
WARN_ON_ONCE(1);
req->error = BLK_STS_NOTSUPP;
return;
}
start = end;
} while(start < nsectors);
req->offset += len;
req->error = update_bitmap(req, desc);
}
/* Changed in start_io_thread, which is serialized by being called only
* from ubd_init, which is an initcall.
*/
int kernel_fd = -1;
/* Only changed by the io thread. XXX: currently unused. */
static int io_count;
int io_thread(void *arg)
{
int n, count, written, res;
os_fix_helper_signals();
while(1){
n = bulk_req_safe_read(
kernel_fd,
io_req_buffer,
&io_remainder,
&io_remainder_size,
UBD_REQ_BUFFER_SIZE
);
if (n <= 0) {
if (n == -EAGAIN)
ubd_read_poll(-1);
continue;
}
for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
struct io_thread_req *req = (*io_req_buffer)[count];
int i;
io_count++;
for (i = 0; !req->error && i < req->desc_cnt; i++)
do_io(req, &(req->io_desc[i]));
}
written = 0;
do {
res = os_write_file(kernel_fd,
((char *) io_req_buffer) + written,
n - written);
if (res >= 0) {
written += res;
}
if (written < n) {
ubd_write_poll(-1);
}
} while (written < n);
}
return 0;
}
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