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TOMOYO Linux Cross Reference
Linux/arch/um/drivers/ubd_kern.c

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  1 /*
  2  * Copyright (C) 2015-2016 Anton Ivanov (aivanov@brocade.com)
  3  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
  4  * Licensed under the GPL
  5  */
  6 
  7 /* 2001-09-28...2002-04-17
  8  * Partition stuff by James_McMechan@hotmail.com
  9  * old style ubd by setting UBD_SHIFT to 0
 10  * 2002-09-27...2002-10-18 massive tinkering for 2.5
 11  * partitions have changed in 2.5
 12  * 2003-01-29 more tinkering for 2.5.59-1
 13  * This should now address the sysfs problems and has
 14  * the symlink for devfs to allow for booting with
 15  * the common /dev/ubd/discX/... names rather than
 16  * only /dev/ubdN/discN this version also has lots of
 17  * clean ups preparing for ubd-many.
 18  * James McMechan
 19  */
 20 
 21 #define UBD_SHIFT 4
 22 
 23 #include <linux/module.h>
 24 #include <linux/init.h>
 25 #include <linux/blkdev.h>
 26 #include <linux/ata.h>
 27 #include <linux/hdreg.h>
 28 #include <linux/cdrom.h>
 29 #include <linux/proc_fs.h>
 30 #include <linux/seq_file.h>
 31 #include <linux/ctype.h>
 32 #include <linux/slab.h>
 33 #include <linux/vmalloc.h>
 34 #include <linux/platform_device.h>
 35 #include <linux/scatterlist.h>
 36 #include <asm/tlbflush.h>
 37 #include <kern_util.h>
 38 #include "mconsole_kern.h"
 39 #include <init.h>
 40 #include <irq_kern.h>
 41 #include "ubd.h"
 42 #include <os.h>
 43 #include "cow.h"
 44 
 45 enum ubd_req { UBD_READ, UBD_WRITE, UBD_FLUSH };
 46 
 47 struct io_thread_req {
 48         struct request *req;
 49         enum ubd_req op;
 50         int fds[2];
 51         unsigned long offsets[2];
 52         unsigned long long offset;
 53         unsigned long length;
 54         char *buffer;
 55         int sectorsize;
 56         unsigned long sector_mask;
 57         unsigned long long cow_offset;
 58         unsigned long bitmap_words[2];
 59         int error;
 60 };
 61 
 62 
 63 static struct io_thread_req * (*irq_req_buffer)[];
 64 static struct io_thread_req *irq_remainder;
 65 static int irq_remainder_size;
 66 
 67 static struct io_thread_req * (*io_req_buffer)[];
 68 static struct io_thread_req *io_remainder;
 69 static int io_remainder_size;
 70 
 71 
 72 
 73 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
 74 {
 75         __u64 n;
 76         int bits, off;
 77 
 78         bits = sizeof(data[0]) * 8;
 79         n = bit / bits;
 80         off = bit % bits;
 81         return (data[n] & (1 << off)) != 0;
 82 }
 83 
 84 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
 85 {
 86         __u64 n;
 87         int bits, off;
 88 
 89         bits = sizeof(data[0]) * 8;
 90         n = bit / bits;
 91         off = bit % bits;
 92         data[n] |= (1 << off);
 93 }
 94 /*End stuff from ubd_user.h*/
 95 
 96 #define DRIVER_NAME "uml-blkdev"
 97 
 98 static DEFINE_MUTEX(ubd_lock);
 99 static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
100 
101 static int ubd_open(struct block_device *bdev, fmode_t mode);
102 static void ubd_release(struct gendisk *disk, fmode_t mode);
103 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
104                      unsigned int cmd, unsigned long arg);
105 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
106 
107 #define MAX_DEV (16)
108 
109 static const struct block_device_operations ubd_blops = {
110         .owner          = THIS_MODULE,
111         .open           = ubd_open,
112         .release        = ubd_release,
113         .ioctl          = ubd_ioctl,
114         .getgeo         = ubd_getgeo,
115 };
116 
117 /* Protected by ubd_lock */
118 static int fake_major = UBD_MAJOR;
119 static struct gendisk *ubd_gendisk[MAX_DEV];
120 static struct gendisk *fake_gendisk[MAX_DEV];
121 
122 #ifdef CONFIG_BLK_DEV_UBD_SYNC
123 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
124                                          .cl = 1 })
125 #else
126 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
127                                          .cl = 1 })
128 #endif
129 static struct openflags global_openflags = OPEN_FLAGS;
130 
131 struct cow {
132         /* backing file name */
133         char *file;
134         /* backing file fd */
135         int fd;
136         unsigned long *bitmap;
137         unsigned long bitmap_len;
138         int bitmap_offset;
139         int data_offset;
140 };
141 
142 #define MAX_SG 64
143 
144 struct ubd {
145         struct list_head restart;
146         /* name (and fd, below) of the file opened for writing, either the
147          * backing or the cow file. */
148         char *file;
149         int count;
150         int fd;
151         __u64 size;
152         struct openflags boot_openflags;
153         struct openflags openflags;
154         unsigned shared:1;
155         unsigned no_cow:1;
156         struct cow cow;
157         struct platform_device pdev;
158         struct request_queue *queue;
159         spinlock_t lock;
160         struct scatterlist sg[MAX_SG];
161         struct request *request;
162         int start_sg, end_sg;
163         sector_t rq_pos;
164 };
165 
166 #define DEFAULT_COW { \
167         .file =                 NULL, \
168         .fd =                   -1,     \
169         .bitmap =               NULL, \
170         .bitmap_offset =        0, \
171         .data_offset =          0, \
172 }
173 
174 #define DEFAULT_UBD { \
175         .file =                 NULL, \
176         .count =                0, \
177         .fd =                   -1, \
178         .size =                 -1, \
179         .boot_openflags =       OPEN_FLAGS, \
180         .openflags =            OPEN_FLAGS, \
181         .no_cow =               0, \
182         .shared =               0, \
183         .cow =                  DEFAULT_COW, \
184         .lock =                 __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
185         .request =              NULL, \
186         .start_sg =             0, \
187         .end_sg =               0, \
188         .rq_pos =               0, \
189 }
190 
191 /* Protected by ubd_lock */
192 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
193 
194 /* Only changed by fake_ide_setup which is a setup */
195 static int fake_ide = 0;
196 static struct proc_dir_entry *proc_ide_root = NULL;
197 static struct proc_dir_entry *proc_ide = NULL;
198 
199 static void make_proc_ide(void)
200 {
201         proc_ide_root = proc_mkdir("ide", NULL);
202         proc_ide = proc_mkdir("ide0", proc_ide_root);
203 }
204 
205 static int fake_ide_media_proc_show(struct seq_file *m, void *v)
206 {
207         seq_puts(m, "disk\n");
208         return 0;
209 }
210 
211 static int fake_ide_media_proc_open(struct inode *inode, struct file *file)
212 {
213         return single_open(file, fake_ide_media_proc_show, NULL);
214 }
215 
216 static const struct file_operations fake_ide_media_proc_fops = {
217         .owner          = THIS_MODULE,
218         .open           = fake_ide_media_proc_open,
219         .read           = seq_read,
220         .llseek         = seq_lseek,
221         .release        = single_release,
222 };
223 
224 static void make_ide_entries(const char *dev_name)
225 {
226         struct proc_dir_entry *dir, *ent;
227         char name[64];
228 
229         if(proc_ide_root == NULL) make_proc_ide();
230 
231         dir = proc_mkdir(dev_name, proc_ide);
232         if(!dir) return;
233 
234         ent = proc_create("media", S_IRUGO, dir, &fake_ide_media_proc_fops);
235         if(!ent) return;
236         snprintf(name, sizeof(name), "ide0/%s", dev_name);
237         proc_symlink(dev_name, proc_ide_root, name);
238 }
239 
240 static int fake_ide_setup(char *str)
241 {
242         fake_ide = 1;
243         return 1;
244 }
245 
246 __setup("fake_ide", fake_ide_setup);
247 
248 __uml_help(fake_ide_setup,
249 "fake_ide\n"
250 "    Create ide0 entries that map onto ubd devices.\n\n"
251 );
252 
253 static int parse_unit(char **ptr)
254 {
255         char *str = *ptr, *end;
256         int n = -1;
257 
258         if(isdigit(*str)) {
259                 n = simple_strtoul(str, &end, 0);
260                 if(end == str)
261                         return -1;
262                 *ptr = end;
263         }
264         else if (('a' <= *str) && (*str <= 'z')) {
265                 n = *str - 'a';
266                 str++;
267                 *ptr = str;
268         }
269         return n;
270 }
271 
272 /* If *index_out == -1 at exit, the passed option was a general one;
273  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
274  * should not be freed on exit.
275  */
276 static int ubd_setup_common(char *str, int *index_out, char **error_out)
277 {
278         struct ubd *ubd_dev;
279         struct openflags flags = global_openflags;
280         char *backing_file;
281         int n, err = 0, i;
282 
283         if(index_out) *index_out = -1;
284         n = *str;
285         if(n == '='){
286                 char *end;
287                 int major;
288 
289                 str++;
290                 if(!strcmp(str, "sync")){
291                         global_openflags = of_sync(global_openflags);
292                         goto out1;
293                 }
294 
295                 err = -EINVAL;
296                 major = simple_strtoul(str, &end, 0);
297                 if((*end != '\0') || (end == str)){
298                         *error_out = "Didn't parse major number";
299                         goto out1;
300                 }
301 
302                 mutex_lock(&ubd_lock);
303                 if (fake_major != UBD_MAJOR) {
304                         *error_out = "Can't assign a fake major twice";
305                         goto out1;
306                 }
307 
308                 fake_major = major;
309 
310                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
311                        major);
312                 err = 0;
313         out1:
314                 mutex_unlock(&ubd_lock);
315                 return err;
316         }
317 
318         n = parse_unit(&str);
319         if(n < 0){
320                 *error_out = "Couldn't parse device number";
321                 return -EINVAL;
322         }
323         if(n >= MAX_DEV){
324                 *error_out = "Device number out of range";
325                 return 1;
326         }
327 
328         err = -EBUSY;
329         mutex_lock(&ubd_lock);
330 
331         ubd_dev = &ubd_devs[n];
332         if(ubd_dev->file != NULL){
333                 *error_out = "Device is already configured";
334                 goto out;
335         }
336 
337         if (index_out)
338                 *index_out = n;
339 
340         err = -EINVAL;
341         for (i = 0; i < sizeof("rscd="); i++) {
342                 switch (*str) {
343                 case 'r':
344                         flags.w = 0;
345                         break;
346                 case 's':
347                         flags.s = 1;
348                         break;
349                 case 'd':
350                         ubd_dev->no_cow = 1;
351                         break;
352                 case 'c':
353                         ubd_dev->shared = 1;
354                         break;
355                 case '=':
356                         str++;
357                         goto break_loop;
358                 default:
359                         *error_out = "Expected '=' or flag letter "
360                                 "(r, s, c, or d)";
361                         goto out;
362                 }
363                 str++;
364         }
365 
366         if (*str == '=')
367                 *error_out = "Too many flags specified";
368         else
369                 *error_out = "Missing '='";
370         goto out;
371 
372 break_loop:
373         backing_file = strchr(str, ',');
374 
375         if (backing_file == NULL)
376                 backing_file = strchr(str, ':');
377 
378         if(backing_file != NULL){
379                 if(ubd_dev->no_cow){
380                         *error_out = "Can't specify both 'd' and a cow file";
381                         goto out;
382                 }
383                 else {
384                         *backing_file = '\0';
385                         backing_file++;
386                 }
387         }
388         err = 0;
389         ubd_dev->file = str;
390         ubd_dev->cow.file = backing_file;
391         ubd_dev->boot_openflags = flags;
392 out:
393         mutex_unlock(&ubd_lock);
394         return err;
395 }
396 
397 static int ubd_setup(char *str)
398 {
399         char *error;
400         int err;
401 
402         err = ubd_setup_common(str, NULL, &error);
403         if(err)
404                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
405                        "%s\n", str, error);
406         return 1;
407 }
408 
409 __setup("ubd", ubd_setup);
410 __uml_help(ubd_setup,
411 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
412 "    This is used to associate a device with a file in the underlying\n"
413 "    filesystem. When specifying two filenames, the first one is the\n"
414 "    COW name and the second is the backing file name. As separator you can\n"
415 "    use either a ':' or a ',': the first one allows writing things like;\n"
416 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
417 "    while with a ',' the shell would not expand the 2nd '~'.\n"
418 "    When using only one filename, UML will detect whether to treat it like\n"
419 "    a COW file or a backing file. To override this detection, add the 'd'\n"
420 "    flag:\n"
421 "       ubd0d=BackingFile\n"
422 "    Usually, there is a filesystem in the file, but \n"
423 "    that's not required. Swap devices containing swap files can be\n"
424 "    specified like this. Also, a file which doesn't contain a\n"
425 "    filesystem can have its contents read in the virtual \n"
426 "    machine by running 'dd' on the device. <n> must be in the range\n"
427 "    0 to 7. Appending an 'r' to the number will cause that device\n"
428 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
429 "    an 's' will cause data to be written to disk on the host immediately.\n"
430 "    'c' will cause the device to be treated as being shared between multiple\n"
431 "    UMLs and file locking will be turned off - this is appropriate for a\n"
432 "    cluster filesystem and inappropriate at almost all other times.\n\n"
433 );
434 
435 static int udb_setup(char *str)
436 {
437         printk("udb%s specified on command line is almost certainly a ubd -> "
438                "udb TYPO\n", str);
439         return 1;
440 }
441 
442 __setup("udb", udb_setup);
443 __uml_help(udb_setup,
444 "udb\n"
445 "    This option is here solely to catch ubd -> udb typos, which can be\n"
446 "    to impossible to catch visually unless you specifically look for\n"
447 "    them.  The only result of any option starting with 'udb' is an error\n"
448 "    in the boot output.\n\n"
449 );
450 
451 static void do_ubd_request(struct request_queue * q);
452 
453 /* Only changed by ubd_init, which is an initcall. */
454 static int thread_fd = -1;
455 static LIST_HEAD(restart);
456 
457 /* Function to read several request pointers at a time
458 * handling fractional reads if (and as) needed
459 */
460 
461 static int bulk_req_safe_read(
462         int fd,
463         struct io_thread_req * (*request_buffer)[],
464         struct io_thread_req **remainder,
465         int *remainder_size,
466         int max_recs
467         )
468 {
469         int n = 0;
470         int res = 0;
471 
472         if (*remainder_size > 0) {
473                 memmove(
474                         (char *) request_buffer,
475                         (char *) remainder, *remainder_size
476                 );
477                 n = *remainder_size;
478         }
479 
480         res = os_read_file(
481                         fd,
482                         ((char *) request_buffer) + *remainder_size,
483                         sizeof(struct io_thread_req *)*max_recs
484                                 - *remainder_size
485                 );
486         if (res > 0) {
487                 n += res;
488                 if ((n % sizeof(struct io_thread_req *)) > 0) {
489                         /*
490                         * Read somehow returned not a multiple of dword
491                         * theoretically possible, but never observed in the
492                         * wild, so read routine must be able to handle it
493                         */
494                         *remainder_size = n % sizeof(struct io_thread_req *);
495                         WARN(*remainder_size > 0, "UBD IPC read returned a partial result");
496                         memmove(
497                                 remainder,
498                                 ((char *) request_buffer) +
499                                         (n/sizeof(struct io_thread_req *))*sizeof(struct io_thread_req *),
500                                 *remainder_size
501                         );
502                         n = n - *remainder_size;
503                 }
504         } else {
505                 n = res;
506         }
507         return n;
508 }
509 
510 /* Called without dev->lock held, and only in interrupt context. */
511 static void ubd_handler(void)
512 {
513         struct ubd *ubd;
514         struct list_head *list, *next_ele;
515         unsigned long flags;
516         int n;
517         int count;
518 
519         while(1){
520                 n = bulk_req_safe_read(
521                         thread_fd,
522                         irq_req_buffer,
523                         &irq_remainder,
524                         &irq_remainder_size,
525                         UBD_REQ_BUFFER_SIZE
526                 );
527                 if (n < 0) {
528                         if(n == -EAGAIN)
529                                 break;
530                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
531                                "err = %d\n", -n);
532                         return;
533                 }
534                 for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
535                         blk_end_request(
536                                 (*irq_req_buffer)[count]->req,
537                                 0,
538                                 (*irq_req_buffer)[count]->length
539                         );
540                         kfree((*irq_req_buffer)[count]);
541                 }
542         }
543         reactivate_fd(thread_fd, UBD_IRQ);
544 
545         list_for_each_safe(list, next_ele, &restart){
546                 ubd = container_of(list, struct ubd, restart);
547                 list_del_init(&ubd->restart);
548                 spin_lock_irqsave(&ubd->lock, flags);
549                 do_ubd_request(ubd->queue);
550                 spin_unlock_irqrestore(&ubd->lock, flags);
551         }
552 }
553 
554 static irqreturn_t ubd_intr(int irq, void *dev)
555 {
556         ubd_handler();
557         return IRQ_HANDLED;
558 }
559 
560 /* Only changed by ubd_init, which is an initcall. */
561 static int io_pid = -1;
562 
563 static void kill_io_thread(void)
564 {
565         if(io_pid != -1)
566                 os_kill_process(io_pid, 1);
567 }
568 
569 __uml_exitcall(kill_io_thread);
570 
571 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
572 {
573         char *file;
574         int fd;
575         int err;
576 
577         __u32 version;
578         __u32 align;
579         char *backing_file;
580         time_t mtime;
581         unsigned long long size;
582         int sector_size;
583         int bitmap_offset;
584 
585         if (ubd_dev->file && ubd_dev->cow.file) {
586                 file = ubd_dev->cow.file;
587 
588                 goto out;
589         }
590 
591         fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
592         if (fd < 0)
593                 return fd;
594 
595         err = read_cow_header(file_reader, &fd, &version, &backing_file, \
596                 &mtime, &size, &sector_size, &align, &bitmap_offset);
597         os_close_file(fd);
598 
599         if(err == -EINVAL)
600                 file = ubd_dev->file;
601         else
602                 file = backing_file;
603 
604 out:
605         return os_file_size(file, size_out);
606 }
607 
608 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
609 {
610         int err;
611 
612         err = os_pread_file(fd, buf, len, offset);
613         if (err < 0)
614                 return err;
615 
616         return 0;
617 }
618 
619 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
620 {
621         unsigned long modtime;
622         unsigned long long actual;
623         int err;
624 
625         err = os_file_modtime(file, &modtime);
626         if (err < 0) {
627                 printk(KERN_ERR "Failed to get modification time of backing "
628                        "file \"%s\", err = %d\n", file, -err);
629                 return err;
630         }
631 
632         err = os_file_size(file, &actual);
633         if (err < 0) {
634                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
635                        "err = %d\n", file, -err);
636                 return err;
637         }
638 
639         if (actual != size) {
640                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
641                  * the typecast.*/
642                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
643                        "vs backing file\n", (unsigned long long) size, actual);
644                 return -EINVAL;
645         }
646         if (modtime != mtime) {
647                 printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
648                        "backing file\n", mtime, modtime);
649                 return -EINVAL;
650         }
651         return 0;
652 }
653 
654 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
655 {
656         struct uml_stat buf1, buf2;
657         int err;
658 
659         if (from_cmdline == NULL)
660                 return 0;
661         if (!strcmp(from_cmdline, from_cow))
662                 return 0;
663 
664         err = os_stat_file(from_cmdline, &buf1);
665         if (err < 0) {
666                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
667                        -err);
668                 return 0;
669         }
670         err = os_stat_file(from_cow, &buf2);
671         if (err < 0) {
672                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
673                        -err);
674                 return 1;
675         }
676         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
677                 return 0;
678 
679         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
680                "\"%s\" specified in COW header of \"%s\"\n",
681                from_cmdline, from_cow, cow);
682         return 1;
683 }
684 
685 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
686                   char **backing_file_out, int *bitmap_offset_out,
687                   unsigned long *bitmap_len_out, int *data_offset_out,
688                   int *create_cow_out)
689 {
690         time_t mtime;
691         unsigned long long size;
692         __u32 version, align;
693         char *backing_file;
694         int fd, err, sectorsize, asked_switch, mode = 0644;
695 
696         fd = os_open_file(file, *openflags, mode);
697         if (fd < 0) {
698                 if ((fd == -ENOENT) && (create_cow_out != NULL))
699                         *create_cow_out = 1;
700                 if (!openflags->w ||
701                     ((fd != -EROFS) && (fd != -EACCES)))
702                         return fd;
703                 openflags->w = 0;
704                 fd = os_open_file(file, *openflags, mode);
705                 if (fd < 0)
706                         return fd;
707         }
708 
709         if (shared)
710                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
711         else {
712                 err = os_lock_file(fd, openflags->w);
713                 if (err < 0) {
714                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
715                                file, -err);
716                         goto out_close;
717                 }
718         }
719 
720         /* Successful return case! */
721         if (backing_file_out == NULL)
722                 return fd;
723 
724         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
725                               &size, &sectorsize, &align, bitmap_offset_out);
726         if (err && (*backing_file_out != NULL)) {
727                 printk(KERN_ERR "Failed to read COW header from COW file "
728                        "\"%s\", errno = %d\n", file, -err);
729                 goto out_close;
730         }
731         if (err)
732                 return fd;
733 
734         asked_switch = path_requires_switch(*backing_file_out, backing_file,
735                                             file);
736 
737         /* Allow switching only if no mismatch. */
738         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
739                                                    mtime)) {
740                 printk(KERN_ERR "Switching backing file to '%s'\n",
741                        *backing_file_out);
742                 err = write_cow_header(file, fd, *backing_file_out,
743                                        sectorsize, align, &size);
744                 if (err) {
745                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
746                         goto out_close;
747                 }
748         } else {
749                 *backing_file_out = backing_file;
750                 err = backing_file_mismatch(*backing_file_out, size, mtime);
751                 if (err)
752                         goto out_close;
753         }
754 
755         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
756                   bitmap_len_out, data_offset_out);
757 
758         return fd;
759  out_close:
760         os_close_file(fd);
761         return err;
762 }
763 
764 static int create_cow_file(char *cow_file, char *backing_file,
765                     struct openflags flags,
766                     int sectorsize, int alignment, int *bitmap_offset_out,
767                     unsigned long *bitmap_len_out, int *data_offset_out)
768 {
769         int err, fd;
770 
771         flags.c = 1;
772         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
773         if (fd < 0) {
774                 err = fd;
775                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
776                        cow_file, -err);
777                 goto out;
778         }
779 
780         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
781                             bitmap_offset_out, bitmap_len_out,
782                             data_offset_out);
783         if (!err)
784                 return fd;
785         os_close_file(fd);
786  out:
787         return err;
788 }
789 
790 static void ubd_close_dev(struct ubd *ubd_dev)
791 {
792         os_close_file(ubd_dev->fd);
793         if(ubd_dev->cow.file == NULL)
794                 return;
795 
796         os_close_file(ubd_dev->cow.fd);
797         vfree(ubd_dev->cow.bitmap);
798         ubd_dev->cow.bitmap = NULL;
799 }
800 
801 static int ubd_open_dev(struct ubd *ubd_dev)
802 {
803         struct openflags flags;
804         char **back_ptr;
805         int err, create_cow, *create_ptr;
806         int fd;
807 
808         ubd_dev->openflags = ubd_dev->boot_openflags;
809         create_cow = 0;
810         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
811         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
812 
813         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
814                                 back_ptr, &ubd_dev->cow.bitmap_offset,
815                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
816                                 create_ptr);
817 
818         if((fd == -ENOENT) && create_cow){
819                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
820                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
821                                           &ubd_dev->cow.bitmap_offset,
822                                           &ubd_dev->cow.bitmap_len,
823                                           &ubd_dev->cow.data_offset);
824                 if(fd >= 0){
825                         printk(KERN_INFO "Creating \"%s\" as COW file for "
826                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
827                 }
828         }
829 
830         if(fd < 0){
831                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
832                        -fd);
833                 return fd;
834         }
835         ubd_dev->fd = fd;
836 
837         if(ubd_dev->cow.file != NULL){
838                 blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
839 
840                 err = -ENOMEM;
841                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
842                 if(ubd_dev->cow.bitmap == NULL){
843                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
844                         goto error;
845                 }
846                 flush_tlb_kernel_vm();
847 
848                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
849                                       ubd_dev->cow.bitmap_offset,
850                                       ubd_dev->cow.bitmap_len);
851                 if(err < 0)
852                         goto error;
853 
854                 flags = ubd_dev->openflags;
855                 flags.w = 0;
856                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
857                                     NULL, NULL, NULL, NULL);
858                 if(err < 0) goto error;
859                 ubd_dev->cow.fd = err;
860         }
861         return 0;
862  error:
863         os_close_file(ubd_dev->fd);
864         return err;
865 }
866 
867 static void ubd_device_release(struct device *dev)
868 {
869         struct ubd *ubd_dev = dev_get_drvdata(dev);
870 
871         blk_cleanup_queue(ubd_dev->queue);
872         *ubd_dev = ((struct ubd) DEFAULT_UBD);
873 }
874 
875 static int ubd_disk_register(int major, u64 size, int unit,
876                              struct gendisk **disk_out)
877 {
878         struct device *parent = NULL;
879         struct gendisk *disk;
880 
881         disk = alloc_disk(1 << UBD_SHIFT);
882         if(disk == NULL)
883                 return -ENOMEM;
884 
885         disk->major = major;
886         disk->first_minor = unit << UBD_SHIFT;
887         disk->fops = &ubd_blops;
888         set_capacity(disk, size / 512);
889         if (major == UBD_MAJOR)
890                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
891         else
892                 sprintf(disk->disk_name, "ubd_fake%d", unit);
893 
894         /* sysfs register (not for ide fake devices) */
895         if (major == UBD_MAJOR) {
896                 ubd_devs[unit].pdev.id   = unit;
897                 ubd_devs[unit].pdev.name = DRIVER_NAME;
898                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
899                 dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
900                 platform_device_register(&ubd_devs[unit].pdev);
901                 parent = &ubd_devs[unit].pdev.dev;
902         }
903 
904         disk->private_data = &ubd_devs[unit];
905         disk->queue = ubd_devs[unit].queue;
906         device_add_disk(parent, disk);
907 
908         *disk_out = disk;
909         return 0;
910 }
911 
912 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
913 
914 static int ubd_add(int n, char **error_out)
915 {
916         struct ubd *ubd_dev = &ubd_devs[n];
917         int err = 0;
918 
919         if(ubd_dev->file == NULL)
920                 goto out;
921 
922         err = ubd_file_size(ubd_dev, &ubd_dev->size);
923         if(err < 0){
924                 *error_out = "Couldn't determine size of device's file";
925                 goto out;
926         }
927 
928         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
929 
930         INIT_LIST_HEAD(&ubd_dev->restart);
931         sg_init_table(ubd_dev->sg, MAX_SG);
932 
933         err = -ENOMEM;
934         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
935         if (ubd_dev->queue == NULL) {
936                 *error_out = "Failed to initialize device queue";
937                 goto out;
938         }
939         ubd_dev->queue->queuedata = ubd_dev;
940         blk_queue_write_cache(ubd_dev->queue, true, false);
941 
942         blk_queue_max_segments(ubd_dev->queue, MAX_SG);
943         err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
944         if(err){
945                 *error_out = "Failed to register device";
946                 goto out_cleanup;
947         }
948 
949         if (fake_major != UBD_MAJOR)
950                 ubd_disk_register(fake_major, ubd_dev->size, n,
951                                   &fake_gendisk[n]);
952 
953         /*
954          * Perhaps this should also be under the "if (fake_major)" above
955          * using the fake_disk->disk_name
956          */
957         if (fake_ide)
958                 make_ide_entries(ubd_gendisk[n]->disk_name);
959 
960         err = 0;
961 out:
962         return err;
963 
964 out_cleanup:
965         blk_cleanup_queue(ubd_dev->queue);
966         goto out;
967 }
968 
969 static int ubd_config(char *str, char **error_out)
970 {
971         int n, ret;
972 
973         /* This string is possibly broken up and stored, so it's only
974          * freed if ubd_setup_common fails, or if only general options
975          * were set.
976          */
977         str = kstrdup(str, GFP_KERNEL);
978         if (str == NULL) {
979                 *error_out = "Failed to allocate memory";
980                 return -ENOMEM;
981         }
982 
983         ret = ubd_setup_common(str, &n, error_out);
984         if (ret)
985                 goto err_free;
986 
987         if (n == -1) {
988                 ret = 0;
989                 goto err_free;
990         }
991 
992         mutex_lock(&ubd_lock);
993         ret = ubd_add(n, error_out);
994         if (ret)
995                 ubd_devs[n].file = NULL;
996         mutex_unlock(&ubd_lock);
997 
998 out:
999         return ret;
1000 
1001 err_free:
1002         kfree(str);
1003         goto out;
1004 }
1005 
1006 static int ubd_get_config(char *name, char *str, int size, char **error_out)
1007 {
1008         struct ubd *ubd_dev;
1009         int n, len = 0;
1010 
1011         n = parse_unit(&name);
1012         if((n >= MAX_DEV) || (n < 0)){
1013                 *error_out = "ubd_get_config : device number out of range";
1014                 return -1;
1015         }
1016 
1017         ubd_dev = &ubd_devs[n];
1018         mutex_lock(&ubd_lock);
1019 
1020         if(ubd_dev->file == NULL){
1021                 CONFIG_CHUNK(str, size, len, "", 1);
1022                 goto out;
1023         }
1024 
1025         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
1026 
1027         if(ubd_dev->cow.file != NULL){
1028                 CONFIG_CHUNK(str, size, len, ",", 0);
1029                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
1030         }
1031         else CONFIG_CHUNK(str, size, len, "", 1);
1032 
1033  out:
1034         mutex_unlock(&ubd_lock);
1035         return len;
1036 }
1037 
1038 static int ubd_id(char **str, int *start_out, int *end_out)
1039 {
1040         int n;
1041 
1042         n = parse_unit(str);
1043         *start_out = 0;
1044         *end_out = MAX_DEV - 1;
1045         return n;
1046 }
1047 
1048 static int ubd_remove(int n, char **error_out)
1049 {
1050         struct gendisk *disk = ubd_gendisk[n];
1051         struct ubd *ubd_dev;
1052         int err = -ENODEV;
1053 
1054         mutex_lock(&ubd_lock);
1055 
1056         ubd_dev = &ubd_devs[n];
1057 
1058         if(ubd_dev->file == NULL)
1059                 goto out;
1060 
1061         /* you cannot remove a open disk */
1062         err = -EBUSY;
1063         if(ubd_dev->count > 0)
1064                 goto out;
1065 
1066         ubd_gendisk[n] = NULL;
1067         if(disk != NULL){
1068                 del_gendisk(disk);
1069                 put_disk(disk);
1070         }
1071 
1072         if(fake_gendisk[n] != NULL){
1073                 del_gendisk(fake_gendisk[n]);
1074                 put_disk(fake_gendisk[n]);
1075                 fake_gendisk[n] = NULL;
1076         }
1077 
1078         err = 0;
1079         platform_device_unregister(&ubd_dev->pdev);
1080 out:
1081         mutex_unlock(&ubd_lock);
1082         return err;
1083 }
1084 
1085 /* All these are called by mconsole in process context and without
1086  * ubd-specific locks.  The structure itself is const except for .list.
1087  */
1088 static struct mc_device ubd_mc = {
1089         .list           = LIST_HEAD_INIT(ubd_mc.list),
1090         .name           = "ubd",
1091         .config         = ubd_config,
1092         .get_config     = ubd_get_config,
1093         .id             = ubd_id,
1094         .remove         = ubd_remove,
1095 };
1096 
1097 static int __init ubd_mc_init(void)
1098 {
1099         mconsole_register_dev(&ubd_mc);
1100         return 0;
1101 }
1102 
1103 __initcall(ubd_mc_init);
1104 
1105 static int __init ubd0_init(void)
1106 {
1107         struct ubd *ubd_dev = &ubd_devs[0];
1108 
1109         mutex_lock(&ubd_lock);
1110         if(ubd_dev->file == NULL)
1111                 ubd_dev->file = "root_fs";
1112         mutex_unlock(&ubd_lock);
1113 
1114         return 0;
1115 }
1116 
1117 __initcall(ubd0_init);
1118 
1119 /* Used in ubd_init, which is an initcall */
1120 static struct platform_driver ubd_driver = {
1121         .driver = {
1122                 .name  = DRIVER_NAME,
1123         },
1124 };
1125 
1126 static int __init ubd_init(void)
1127 {
1128         char *error;
1129         int i, err;
1130 
1131         if (register_blkdev(UBD_MAJOR, "ubd"))
1132                 return -1;
1133 
1134         if (fake_major != UBD_MAJOR) {
1135                 char name[sizeof("ubd_nnn\0")];
1136 
1137                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1138                 if (register_blkdev(fake_major, "ubd"))
1139                         return -1;
1140         }
1141 
1142         irq_req_buffer = kmalloc(
1143                         sizeof(struct io_thread_req *) * UBD_REQ_BUFFER_SIZE,
1144                         GFP_KERNEL
1145                 );
1146         irq_remainder = 0;
1147 
1148         if (irq_req_buffer == NULL) {
1149                 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1150                 return -1;
1151         }
1152         io_req_buffer = kmalloc(
1153                         sizeof(struct io_thread_req *) * UBD_REQ_BUFFER_SIZE,
1154                         GFP_KERNEL
1155                 );
1156 
1157         io_remainder = 0;
1158 
1159         if (io_req_buffer == NULL) {
1160                 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1161                 return -1;
1162         }
1163         platform_driver_register(&ubd_driver);
1164         mutex_lock(&ubd_lock);
1165         for (i = 0; i < MAX_DEV; i++){
1166                 err = ubd_add(i, &error);
1167                 if(err)
1168                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1169                                "%s\n", i, error);
1170         }
1171         mutex_unlock(&ubd_lock);
1172         return 0;
1173 }
1174 
1175 late_initcall(ubd_init);
1176 
1177 static int __init ubd_driver_init(void){
1178         unsigned long stack;
1179         int err;
1180 
1181         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1182         if(global_openflags.s){
1183                 printk(KERN_INFO "ubd: Synchronous mode\n");
1184                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1185                  * enough. So use anyway the io thread. */
1186         }
1187         stack = alloc_stack(0, 0);
1188         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1189                                  &thread_fd);
1190         if(io_pid < 0){
1191                 printk(KERN_ERR
1192                        "ubd : Failed to start I/O thread (errno = %d) - "
1193                        "falling back to synchronous I/O\n", -io_pid);
1194                 io_pid = -1;
1195                 return 0;
1196         }
1197         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1198                              0, "ubd", ubd_devs);
1199         if(err != 0)
1200                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1201         return 0;
1202 }
1203 
1204 device_initcall(ubd_driver_init);
1205 
1206 static int ubd_open(struct block_device *bdev, fmode_t mode)
1207 {
1208         struct gendisk *disk = bdev->bd_disk;
1209         struct ubd *ubd_dev = disk->private_data;
1210         int err = 0;
1211 
1212         mutex_lock(&ubd_mutex);
1213         if(ubd_dev->count == 0){
1214                 err = ubd_open_dev(ubd_dev);
1215                 if(err){
1216                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1217                                disk->disk_name, ubd_dev->file, -err);
1218                         goto out;
1219                 }
1220         }
1221         ubd_dev->count++;
1222         set_disk_ro(disk, !ubd_dev->openflags.w);
1223 
1224         /* This should no more be needed. And it didn't work anyway to exclude
1225          * read-write remounting of filesystems.*/
1226         /*if((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1227                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1228                 err = -EROFS;
1229         }*/
1230 out:
1231         mutex_unlock(&ubd_mutex);
1232         return err;
1233 }
1234 
1235 static void ubd_release(struct gendisk *disk, fmode_t mode)
1236 {
1237         struct ubd *ubd_dev = disk->private_data;
1238 
1239         mutex_lock(&ubd_mutex);
1240         if(--ubd_dev->count == 0)
1241                 ubd_close_dev(ubd_dev);
1242         mutex_unlock(&ubd_mutex);
1243 }
1244 
1245 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1246                           __u64 *cow_offset, unsigned long *bitmap,
1247                           __u64 bitmap_offset, unsigned long *bitmap_words,
1248                           __u64 bitmap_len)
1249 {
1250         __u64 sector = io_offset >> 9;
1251         int i, update_bitmap = 0;
1252 
1253         for(i = 0; i < length >> 9; i++){
1254                 if(cow_mask != NULL)
1255                         ubd_set_bit(i, (unsigned char *) cow_mask);
1256                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1257                         continue;
1258 
1259                 update_bitmap = 1;
1260                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1261         }
1262 
1263         if(!update_bitmap)
1264                 return;
1265 
1266         *cow_offset = sector / (sizeof(unsigned long) * 8);
1267 
1268         /* This takes care of the case where we're exactly at the end of the
1269          * device, and *cow_offset + 1 is off the end.  So, just back it up
1270          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1271          * for the original diagnosis.
1272          */
1273         if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1274                                          sizeof(unsigned long)) - 1))
1275                 (*cow_offset)--;
1276 
1277         bitmap_words[0] = bitmap[*cow_offset];
1278         bitmap_words[1] = bitmap[*cow_offset + 1];
1279 
1280         *cow_offset *= sizeof(unsigned long);
1281         *cow_offset += bitmap_offset;
1282 }
1283 
1284 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1285                        __u64 bitmap_offset, __u64 bitmap_len)
1286 {
1287         __u64 sector = req->offset >> 9;
1288         int i;
1289 
1290         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1291                 panic("Operation too long");
1292 
1293         if(req->op == UBD_READ) {
1294                 for(i = 0; i < req->length >> 9; i++){
1295                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1296                                 ubd_set_bit(i, (unsigned char *)
1297                                             &req->sector_mask);
1298                 }
1299         }
1300         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1301                            &req->cow_offset, bitmap, bitmap_offset,
1302                            req->bitmap_words, bitmap_len);
1303 }
1304 
1305 /* Called with dev->lock held */
1306 static void prepare_request(struct request *req, struct io_thread_req *io_req,
1307                             unsigned long long offset, int page_offset,
1308                             int len, struct page *page)
1309 {
1310         struct gendisk *disk = req->rq_disk;
1311         struct ubd *ubd_dev = disk->private_data;
1312 
1313         io_req->req = req;
1314         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1315                 ubd_dev->fd;
1316         io_req->fds[1] = ubd_dev->fd;
1317         io_req->cow_offset = -1;
1318         io_req->offset = offset;
1319         io_req->length = len;
1320         io_req->error = 0;
1321         io_req->sector_mask = 0;
1322 
1323         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1324         io_req->offsets[0] = 0;
1325         io_req->offsets[1] = ubd_dev->cow.data_offset;
1326         io_req->buffer = page_address(page) + page_offset;
1327         io_req->sectorsize = 1 << 9;
1328 
1329         if(ubd_dev->cow.file != NULL)
1330                 cowify_req(io_req, ubd_dev->cow.bitmap,
1331                            ubd_dev->cow.bitmap_offset, ubd_dev->cow.bitmap_len);
1332 
1333 }
1334 
1335 /* Called with dev->lock held */
1336 static void prepare_flush_request(struct request *req,
1337                                   struct io_thread_req *io_req)
1338 {
1339         struct gendisk *disk = req->rq_disk;
1340         struct ubd *ubd_dev = disk->private_data;
1341 
1342         io_req->req = req;
1343         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1344                 ubd_dev->fd;
1345         io_req->op = UBD_FLUSH;
1346 }
1347 
1348 static bool submit_request(struct io_thread_req *io_req, struct ubd *dev)
1349 {
1350         int n = os_write_file(thread_fd, &io_req,
1351                              sizeof(io_req));
1352         if (n != sizeof(io_req)) {
1353                 if (n != -EAGAIN)
1354                         printk("write to io thread failed, "
1355                                "errno = %d\n", -n);
1356                 else if (list_empty(&dev->restart))
1357                         list_add(&dev->restart, &restart);
1358 
1359                 kfree(io_req);
1360                 return false;
1361         }
1362         return true;
1363 }
1364 
1365 /* Called with dev->lock held */
1366 static void do_ubd_request(struct request_queue *q)
1367 {
1368         struct io_thread_req *io_req;
1369         struct request *req;
1370 
1371         while(1){
1372                 struct ubd *dev = q->queuedata;
1373                 if(dev->request == NULL){
1374                         struct request *req = blk_fetch_request(q);
1375                         if(req == NULL)
1376                                 return;
1377 
1378                         dev->request = req;
1379                         dev->rq_pos = blk_rq_pos(req);
1380                         dev->start_sg = 0;
1381                         dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
1382                 }
1383 
1384                 req = dev->request;
1385 
1386                 if (req_op(req) == REQ_OP_FLUSH) {
1387                         io_req = kmalloc(sizeof(struct io_thread_req),
1388                                          GFP_ATOMIC);
1389                         if (io_req == NULL) {
1390                                 if (list_empty(&dev->restart))
1391                                         list_add(&dev->restart, &restart);
1392                                 return;
1393                         }
1394                         prepare_flush_request(req, io_req);
1395                         if (submit_request(io_req, dev) == false)
1396                                 return;
1397                 }
1398 
1399                 while(dev->start_sg < dev->end_sg){
1400                         struct scatterlist *sg = &dev->sg[dev->start_sg];
1401 
1402                         io_req = kmalloc(sizeof(struct io_thread_req),
1403                                          GFP_ATOMIC);
1404                         if(io_req == NULL){
1405                                 if(list_empty(&dev->restart))
1406                                         list_add(&dev->restart, &restart);
1407                                 return;
1408                         }
1409                         prepare_request(req, io_req,
1410                                         (unsigned long long)dev->rq_pos << 9,
1411                                         sg->offset, sg->length, sg_page(sg));
1412 
1413                         if (submit_request(io_req, dev) == false)
1414                                 return;
1415 
1416                         dev->rq_pos += sg->length >> 9;
1417                         dev->start_sg++;
1418                 }
1419                 dev->end_sg = 0;
1420                 dev->request = NULL;
1421         }
1422 }
1423 
1424 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1425 {
1426         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1427 
1428         geo->heads = 128;
1429         geo->sectors = 32;
1430         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1431         return 0;
1432 }
1433 
1434 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
1435                      unsigned int cmd, unsigned long arg)
1436 {
1437         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1438         u16 ubd_id[ATA_ID_WORDS];
1439 
1440         switch (cmd) {
1441                 struct cdrom_volctrl volume;
1442         case HDIO_GET_IDENTITY:
1443                 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1444                 ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
1445                 ubd_id[ATA_ID_HEADS]    = 128;
1446                 ubd_id[ATA_ID_SECTORS]  = 32;
1447                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1448                                  sizeof(ubd_id)))
1449                         return -EFAULT;
1450                 return 0;
1451 
1452         case CDROMVOLREAD:
1453                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1454                         return -EFAULT;
1455                 volume.channel0 = 255;
1456                 volume.channel1 = 255;
1457                 volume.channel2 = 255;
1458                 volume.channel3 = 255;
1459                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1460                         return -EFAULT;
1461                 return 0;
1462         }
1463         return -EINVAL;
1464 }
1465 
1466 static int update_bitmap(struct io_thread_req *req)
1467 {
1468         int n;
1469 
1470         if(req->cow_offset == -1)
1471                 return 0;
1472 
1473         n = os_pwrite_file(req->fds[1], &req->bitmap_words,
1474                           sizeof(req->bitmap_words), req->cow_offset);
1475         if(n != sizeof(req->bitmap_words)){
1476                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1477                        req->fds[1]);
1478                 return 1;
1479         }
1480 
1481         return 0;
1482 }
1483 
1484 static void do_io(struct io_thread_req *req)
1485 {
1486         char *buf;
1487         unsigned long len;
1488         int n, nsectors, start, end, bit;
1489         __u64 off;
1490 
1491         if (req->op == UBD_FLUSH) {
1492                 /* fds[0] is always either the rw image or our cow file */
1493                 n = os_sync_file(req->fds[0]);
1494                 if (n != 0) {
1495                         printk("do_io - sync failed err = %d "
1496                                "fd = %d\n", -n, req->fds[0]);
1497                         req->error = 1;
1498                 }
1499                 return;
1500         }
1501 
1502         nsectors = req->length / req->sectorsize;
1503         start = 0;
1504         do {
1505                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1506                 end = start;
1507                 while((end < nsectors) &&
1508                       (ubd_test_bit(end, (unsigned char *)
1509                                     &req->sector_mask) == bit))
1510                         end++;
1511 
1512                 off = req->offset + req->offsets[bit] +
1513                         start * req->sectorsize;
1514                 len = (end - start) * req->sectorsize;
1515                 buf = &req->buffer[start * req->sectorsize];
1516 
1517                 if(req->op == UBD_READ){
1518                         n = 0;
1519                         do {
1520                                 buf = &buf[n];
1521                                 len -= n;
1522                                 n = os_pread_file(req->fds[bit], buf, len, off);
1523                                 if (n < 0) {
1524                                         printk("do_io - read failed, err = %d "
1525                                                "fd = %d\n", -n, req->fds[bit]);
1526                                         req->error = 1;
1527                                         return;
1528                                 }
1529                         } while((n < len) && (n != 0));
1530                         if (n < len) memset(&buf[n], 0, len - n);
1531                 } else {
1532                         n = os_pwrite_file(req->fds[bit], buf, len, off);
1533                         if(n != len){
1534                                 printk("do_io - write failed err = %d "
1535                                        "fd = %d\n", -n, req->fds[bit]);
1536                                 req->error = 1;
1537                                 return;
1538                         }
1539                 }
1540 
1541                 start = end;
1542         } while(start < nsectors);
1543 
1544         req->error = update_bitmap(req);
1545 }
1546 
1547 /* Changed in start_io_thread, which is serialized by being called only
1548  * from ubd_init, which is an initcall.
1549  */
1550 int kernel_fd = -1;
1551 
1552 /* Only changed by the io thread. XXX: currently unused. */
1553 static int io_count = 0;
1554 
1555 int io_thread(void *arg)
1556 {
1557         int n, count, written, res;
1558 
1559         os_fix_helper_signals();
1560 
1561         while(1){
1562                 n = bulk_req_safe_read(
1563                         kernel_fd,
1564                         io_req_buffer,
1565                         &io_remainder,
1566                         &io_remainder_size,
1567                         UBD_REQ_BUFFER_SIZE
1568                 );
1569                 if (n < 0) {
1570                         if (n == -EAGAIN) {
1571                                 ubd_read_poll(-1);
1572                                 continue;
1573                         } else {
1574                                 printk("io_thread - read failed, fd = %d, "
1575                                        "err = %d,"
1576                                        "reminder = %d\n",
1577                                        kernel_fd, -n, io_remainder_size);
1578                         }
1579                 }
1580 
1581                 for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
1582                         io_count++;
1583                         do_io((*io_req_buffer)[count]);
1584                 }
1585 
1586                 written = 0;
1587 
1588                 do {
1589                         res = os_write_file(kernel_fd, ((char *) io_req_buffer) + written, n);
1590                         if (res > 0) {
1591                                 written += res;
1592                         } else {
1593                                 if (res != -EAGAIN) {
1594                                         printk("io_thread - read failed, fd = %d, "
1595                                                "err = %d\n", kernel_fd, -n);
1596                                 }
1597                         }
1598                         if (written < n) {
1599                                 ubd_write_poll(-1);
1600                         }
1601                 } while (written < n);
1602         }
1603 
1604         return 0;
1605 }
1606 

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