[PATCH] uml: fix I/O hang when multiple devices are in use
[linux-2.6.git] / arch / um / drivers / ubd_kern.c
1 /*
2  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
3  * Licensed under the GPL
4  */
5
6 /* 2001-09-28...2002-04-17
7  * Partition stuff by James_McMechan@hotmail.com
8  * old style ubd by setting UBD_SHIFT to 0
9  * 2002-09-27...2002-10-18 massive tinkering for 2.5
10  * partitions have changed in 2.5
11  * 2003-01-29 more tinkering for 2.5.59-1
12  * This should now address the sysfs problems and has
13  * the symlink for devfs to allow for booting with
14  * the common /dev/ubd/discX/... names rather than
15  * only /dev/ubdN/discN this version also has lots of
16  * clean ups preparing for ubd-many.
17  * James McMechan
18  */
19
20 #define MAJOR_NR UBD_MAJOR
21 #define UBD_SHIFT 4
22
23 #include "linux/module.h"
24 #include "linux/blkdev.h"
25 #include "linux/hdreg.h"
26 #include "linux/init.h"
27 #include "linux/cdrom.h"
28 #include "linux/proc_fs.h"
29 #include "linux/ctype.h"
30 #include "linux/capability.h"
31 #include "linux/mm.h"
32 #include "linux/vmalloc.h"
33 #include "linux/blkpg.h"
34 #include "linux/genhd.h"
35 #include "linux/spinlock.h"
36 #include "linux/platform_device.h"
37 #include "asm/segment.h"
38 #include "asm/uaccess.h"
39 #include "asm/irq.h"
40 #include "asm/types.h"
41 #include "asm/tlbflush.h"
42 #include "user_util.h"
43 #include "mem_user.h"
44 #include "kern_util.h"
45 #include "kern.h"
46 #include "mconsole_kern.h"
47 #include "init.h"
48 #include "irq_user.h"
49 #include "irq_kern.h"
50 #include "ubd_user.h"
51 #include "os.h"
52 #include "mem.h"
53 #include "mem_kern.h"
54 #include "cow.h"
55
56 enum ubd_req { UBD_READ, UBD_WRITE };
57
58 struct io_thread_req {
59         struct request *req;
60         enum ubd_req op;
61         int fds[2];
62         unsigned long offsets[2];
63         unsigned long long offset;
64         unsigned long length;
65         char *buffer;
66         int sectorsize;
67         unsigned long sector_mask;
68         unsigned long long cow_offset;
69         unsigned long bitmap_words[2];
70         int error;
71 };
72
73 extern int open_ubd_file(char *file, struct openflags *openflags, int shared,
74                          char **backing_file_out, int *bitmap_offset_out,
75                          unsigned long *bitmap_len_out, int *data_offset_out,
76                          int *create_cow_out);
77 extern int create_cow_file(char *cow_file, char *backing_file,
78                            struct openflags flags, int sectorsize,
79                            int alignment, int *bitmap_offset_out,
80                            unsigned long *bitmap_len_out,
81                            int *data_offset_out);
82 extern int read_cow_bitmap(int fd, void *buf, int offset, int len);
83 extern void do_io(struct io_thread_req *req);
84
85 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
86 {
87         __u64 n;
88         int bits, off;
89
90         bits = sizeof(data[0]) * 8;
91         n = bit / bits;
92         off = bit % bits;
93         return((data[n] & (1 << off)) != 0);
94 }
95
96 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
97 {
98         __u64 n;
99         int bits, off;
100
101         bits = sizeof(data[0]) * 8;
102         n = bit / bits;
103         off = bit % bits;
104         data[n] |= (1 << off);
105 }
106 /*End stuff from ubd_user.h*/
107
108 #define DRIVER_NAME "uml-blkdev"
109
110 static DEFINE_MUTEX(ubd_lock);
111
112 static int ubd_open(struct inode * inode, struct file * filp);
113 static int ubd_release(struct inode * inode, struct file * file);
114 static int ubd_ioctl(struct inode * inode, struct file * file,
115                      unsigned int cmd, unsigned long arg);
116 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
117
118 #define MAX_DEV (16)
119
120 static struct block_device_operations ubd_blops = {
121         .owner          = THIS_MODULE,
122         .open           = ubd_open,
123         .release        = ubd_release,
124         .ioctl          = ubd_ioctl,
125         .getgeo         = ubd_getgeo,
126 };
127
128 /* Protected by ubd_lock */
129 static int fake_major = MAJOR_NR;
130 static struct gendisk *ubd_gendisk[MAX_DEV];
131 static struct gendisk *fake_gendisk[MAX_DEV];
132
133 #ifdef CONFIG_BLK_DEV_UBD_SYNC
134 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
135                                          .cl = 1 })
136 #else
137 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
138                                          .cl = 1 })
139 #endif
140 static struct openflags global_openflags = OPEN_FLAGS;
141
142 struct cow {
143         /* backing file name */
144         char *file;
145         /* backing file fd */
146         int fd;
147         unsigned long *bitmap;
148         unsigned long bitmap_len;
149         int bitmap_offset;
150         int data_offset;
151 };
152
153 struct ubd {
154         /* name (and fd, below) of the file opened for writing, either the
155          * backing or the cow file. */
156         char *file;
157         int count;
158         int fd;
159         __u64 size;
160         struct openflags boot_openflags;
161         struct openflags openflags;
162         unsigned shared:1;
163         unsigned no_cow:1;
164         struct cow cow;
165         struct platform_device pdev;
166         struct request_queue *queue;
167         spinlock_t lock;
168         int active;
169 };
170
171 #define DEFAULT_COW { \
172         .file =                 NULL, \
173         .fd =                   -1, \
174         .bitmap =               NULL, \
175         .bitmap_offset =        0, \
176         .data_offset =          0, \
177 }
178
179 #define DEFAULT_UBD { \
180         .file =                 NULL, \
181         .count =                0, \
182         .fd =                   -1, \
183         .size =                 -1, \
184         .boot_openflags =       OPEN_FLAGS, \
185         .openflags =            OPEN_FLAGS, \
186         .no_cow =               0, \
187         .shared =               0, \
188         .cow =                  DEFAULT_COW, \
189         .lock =                 SPIN_LOCK_UNLOCKED,     \
190         .active =               0, \
191 }
192
193 /* Protected by ubd_lock */
194 struct ubd ubd_devs[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
195
196 /* Only changed by fake_ide_setup which is a setup */
197 static int fake_ide = 0;
198 static struct proc_dir_entry *proc_ide_root = NULL;
199 static struct proc_dir_entry *proc_ide = NULL;
200
201 static void make_proc_ide(void)
202 {
203         proc_ide_root = proc_mkdir("ide", NULL);
204         proc_ide = proc_mkdir("ide0", proc_ide_root);
205 }
206
207 static int proc_ide_read_media(char *page, char **start, off_t off, int count,
208                                int *eof, void *data)
209 {
210         int len;
211
212         strcpy(page, "disk\n");
213         len = strlen("disk\n");
214         len -= off;
215         if (len < count){
216                 *eof = 1;
217                 if (len <= 0) return 0;
218         }
219         else len = count;
220         *start = page + off;
221         return len;
222 }
223
224 static void make_ide_entries(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 = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
235         if(!ent) return;
236         ent->data = NULL;
237         ent->read_proc = proc_ide_read_media;
238         ent->write_proc = NULL;
239         sprintf(name,"ide0/%s", dev_name);
240         proc_symlink(dev_name, proc_ide_root, name);
241 }
242
243 static int fake_ide_setup(char *str)
244 {
245         fake_ide = 1;
246         return(1);
247 }
248
249 __setup("fake_ide", fake_ide_setup);
250
251 __uml_help(fake_ide_setup,
252 "fake_ide\n"
253 "    Create ide0 entries that map onto ubd devices.\n\n"
254 );
255
256 static int parse_unit(char **ptr)
257 {
258         char *str = *ptr, *end;
259         int n = -1;
260
261         if(isdigit(*str)) {
262                 n = simple_strtoul(str, &end, 0);
263                 if(end == str)
264                         return(-1);
265                 *ptr = end;
266         }
267         else if (('a' <= *str) && (*str <= 'z')) {
268                 n = *str - 'a';
269                 str++;
270                 *ptr = str;
271         }
272         return(n);
273 }
274
275 /* If *index_out == -1 at exit, the passed option was a general one;
276  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
277  * should not be freed on exit.
278  */
279 static int ubd_setup_common(char *str, int *index_out, char **error_out)
280 {
281         struct ubd *ubd_dev;
282         struct openflags flags = global_openflags;
283         char *backing_file;
284         int n, err = 0, i;
285
286         if(index_out) *index_out = -1;
287         n = *str;
288         if(n == '='){
289                 char *end;
290                 int major;
291
292                 str++;
293                 if(!strcmp(str, "sync")){
294                         global_openflags = of_sync(global_openflags);
295                         goto out1;
296                 }
297
298                 err = -EINVAL;
299                 major = simple_strtoul(str, &end, 0);
300                 if((*end != '\0') || (end == str)){
301                         *error_out = "Didn't parse major number";
302                         goto out1;
303                 }
304
305                 mutex_lock(&ubd_lock);
306                 if(fake_major != MAJOR_NR){
307                         *error_out = "Can't assign a fake major twice";
308                         goto out1;
309                 }
310
311                 fake_major = major;
312
313                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
314                        major);
315                 err = 0;
316         out1:
317                 mutex_unlock(&ubd_lock);
318                 return err;
319         }
320
321         n = parse_unit(&str);
322         if(n < 0){
323                 *error_out = "Couldn't parse device number";
324                 return -EINVAL;
325         }
326         if(n >= MAX_DEV){
327                 *error_out = "Device number out of range";
328                 return 1;
329         }
330
331         err = -EBUSY;
332         mutex_lock(&ubd_lock);
333
334         ubd_dev = &ubd_devs[n];
335         if(ubd_dev->file != NULL){
336                 *error_out = "Device is already configured";
337                 goto out;
338         }
339
340         if (index_out)
341                 *index_out = n;
342
343         err = -EINVAL;
344         for (i = 0; i < sizeof("rscd="); i++) {
345                 switch (*str) {
346                 case 'r':
347                         flags.w = 0;
348                         break;
349                 case 's':
350                         flags.s = 1;
351                         break;
352                 case 'd':
353                         ubd_dev->no_cow = 1;
354                         break;
355                 case 'c':
356                         ubd_dev->shared = 1;
357                         break;
358                 case '=':
359                         str++;
360                         goto break_loop;
361                 default:
362                         *error_out = "Expected '=' or flag letter "
363                                 "(r, s, c, or d)";
364                         goto out;
365                 }
366                 str++;
367         }
368
369         if (*str == '=')
370                 *error_out = "Too many flags specified";
371         else
372                 *error_out = "Missing '='";
373         goto out;
374
375 break_loop:
376         backing_file = strchr(str, ',');
377
378         if (backing_file == NULL)
379                 backing_file = strchr(str, ':');
380
381         if(backing_file != NULL){
382                 if(ubd_dev->no_cow){
383                         *error_out = "Can't specify both 'd' and a cow file";
384                         goto out;
385                 }
386                 else {
387                         *backing_file = '\0';
388                         backing_file++;
389                 }
390         }
391         err = 0;
392         ubd_dev->file = str;
393         ubd_dev->cow.file = backing_file;
394         ubd_dev->boot_openflags = flags;
395 out:
396         mutex_unlock(&ubd_lock);
397         return err;
398 }
399
400 static int ubd_setup(char *str)
401 {
402         char *error;
403         int err;
404
405         err = ubd_setup_common(str, NULL, &error);
406         if(err)
407                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
408                        "%s\n", str, error);
409         return 1;
410 }
411
412 __setup("ubd", ubd_setup);
413 __uml_help(ubd_setup,
414 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
415 "    This is used to associate a device with a file in the underlying\n"
416 "    filesystem. When specifying two filenames, the first one is the\n"
417 "    COW name and the second is the backing file name. As separator you can\n"
418 "    use either a ':' or a ',': the first one allows writing things like;\n"
419 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
420 "    while with a ',' the shell would not expand the 2nd '~'.\n"
421 "    When using only one filename, UML will detect whether to treat it like\n"
422 "    a COW file or a backing file. To override this detection, add the 'd'\n"
423 "    flag:\n"
424 "       ubd0d=BackingFile\n"
425 "    Usually, there is a filesystem in the file, but \n"
426 "    that's not required. Swap devices containing swap files can be\n"
427 "    specified like this. Also, a file which doesn't contain a\n"
428 "    filesystem can have its contents read in the virtual \n"
429 "    machine by running 'dd' on the device. <n> must be in the range\n"
430 "    0 to 7. Appending an 'r' to the number will cause that device\n"
431 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
432 "    an 's' will cause data to be written to disk on the host immediately.\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 int fakehd_set = 0;
452 static int fakehd(char *str)
453 {
454         printk(KERN_INFO "fakehd : Changing ubd name to \"hd\".\n");
455         fakehd_set = 1;
456         return 1;
457 }
458
459 __setup("fakehd", fakehd);
460 __uml_help(fakehd,
461 "fakehd\n"
462 "    Change the ubd device name to \"hd\".\n\n"
463 );
464
465 static void do_ubd_request(request_queue_t * q);
466
467 /* Only changed by ubd_init, which is an initcall. */
468 int thread_fd = -1;
469
470 /* call ubd_finish if you need to serialize */
471 static void __ubd_finish(struct request *req, int error)
472 {
473         int nsect;
474
475         if(error){
476                 end_request(req, 0);
477                 return;
478         }
479         nsect = req->current_nr_sectors;
480         req->sector += nsect;
481         req->buffer += nsect << 9;
482         req->errors = 0;
483         req->nr_sectors -= nsect;
484         req->current_nr_sectors = 0;
485         end_request(req, 1);
486 }
487
488 /* Callable only from interrupt context - otherwise you need to do
489  * spin_lock_irq()/spin_lock_irqsave() */
490 static inline void ubd_finish(struct request *req, int error)
491 {
492         struct ubd *dev = req->rq_disk->private_data;
493
494         spin_lock(&dev->lock);
495         __ubd_finish(req, error);
496         spin_unlock(&dev->lock);
497 }
498
499 /* XXX - move this inside ubd_intr. */
500 /* Called without dev->lock held, and only in interrupt context. */
501 static void ubd_handler(void)
502 {
503         struct io_thread_req req;
504         struct request *rq;
505         struct ubd *dev;
506         int n;
507
508         n = os_read_file(thread_fd, &req, sizeof(req));
509         if(n != sizeof(req)){
510                 printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
511                        "err = %d\n", os_getpid(), -n);
512                 return;
513         }
514
515         rq = req.req;
516         dev = rq->rq_disk->private_data;
517         dev->active = 0;
518
519         ubd_finish(rq, req.error);
520         reactivate_fd(thread_fd, UBD_IRQ);
521         spin_lock(&dev->lock);
522         do_ubd_request(dev->queue);
523         spin_unlock(&dev->lock);
524 }
525
526 static irqreturn_t ubd_intr(int irq, void *dev)
527 {
528         ubd_handler();
529         return(IRQ_HANDLED);
530 }
531
532 /* Only changed by ubd_init, which is an initcall. */
533 static int io_pid = -1;
534
535 void kill_io_thread(void)
536 {
537         if(io_pid != -1)
538                 os_kill_process(io_pid, 1);
539 }
540
541 __uml_exitcall(kill_io_thread);
542
543 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
544 {
545         char *file;
546
547         file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
548         return(os_file_size(file, size_out));
549 }
550
551 static void ubd_close_dev(struct ubd *ubd_dev)
552 {
553         os_close_file(ubd_dev->fd);
554         if(ubd_dev->cow.file == NULL)
555                 return;
556
557         os_close_file(ubd_dev->cow.fd);
558         vfree(ubd_dev->cow.bitmap);
559         ubd_dev->cow.bitmap = NULL;
560 }
561
562 static int ubd_open_dev(struct ubd *ubd_dev)
563 {
564         struct openflags flags;
565         char **back_ptr;
566         int err, create_cow, *create_ptr;
567         int fd;
568
569         ubd_dev->openflags = ubd_dev->boot_openflags;
570         create_cow = 0;
571         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
572         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
573
574         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
575                                 back_ptr, &ubd_dev->cow.bitmap_offset,
576                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
577                                 create_ptr);
578
579         if((fd == -ENOENT) && create_cow){
580                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
581                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
582                                           &ubd_dev->cow.bitmap_offset,
583                                           &ubd_dev->cow.bitmap_len,
584                                           &ubd_dev->cow.data_offset);
585                 if(fd >= 0){
586                         printk(KERN_INFO "Creating \"%s\" as COW file for "
587                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
588                 }
589         }
590
591         if(fd < 0){
592                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
593                        -fd);
594                 return fd;
595         }
596         ubd_dev->fd = fd;
597
598         if(ubd_dev->cow.file != NULL){
599                 err = -ENOMEM;
600                 ubd_dev->cow.bitmap = (void *) vmalloc(ubd_dev->cow.bitmap_len);
601                 if(ubd_dev->cow.bitmap == NULL){
602                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
603                         goto error;
604                 }
605                 flush_tlb_kernel_vm();
606
607                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
608                                       ubd_dev->cow.bitmap_offset,
609                                       ubd_dev->cow.bitmap_len);
610                 if(err < 0)
611                         goto error;
612
613                 flags = ubd_dev->openflags;
614                 flags.w = 0;
615                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
616                                     NULL, NULL, NULL, NULL);
617                 if(err < 0) goto error;
618                 ubd_dev->cow.fd = err;
619         }
620         return(0);
621  error:
622         os_close_file(ubd_dev->fd);
623         return(err);
624 }
625
626 static int ubd_disk_register(int major, u64 size, int unit,
627                              struct gendisk **disk_out)
628 {
629         struct gendisk *disk;
630
631         disk = alloc_disk(1 << UBD_SHIFT);
632         if(disk == NULL)
633                 return(-ENOMEM);
634
635         disk->major = major;
636         disk->first_minor = unit << UBD_SHIFT;
637         disk->fops = &ubd_blops;
638         set_capacity(disk, size / 512);
639         if(major == MAJOR_NR)
640                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
641         else
642                 sprintf(disk->disk_name, "ubd_fake%d", unit);
643
644         /* sysfs register (not for ide fake devices) */
645         if (major == MAJOR_NR) {
646                 ubd_devs[unit].pdev.id   = unit;
647                 ubd_devs[unit].pdev.name = DRIVER_NAME;
648                 platform_device_register(&ubd_devs[unit].pdev);
649                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
650         }
651
652         disk->private_data = &ubd_devs[unit];
653         disk->queue = ubd_devs[unit].queue;
654         add_disk(disk);
655
656         *disk_out = disk;
657         return 0;
658 }
659
660 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
661
662 static int ubd_add(int n, char **error_out)
663 {
664         struct ubd *ubd_dev = &ubd_devs[n];
665         int err = 0;
666
667         if(ubd_dev->file == NULL)
668                 goto out;
669
670         err = ubd_file_size(ubd_dev, &ubd_dev->size);
671         if(err < 0){
672                 *error_out = "Couldn't determine size of device's file";
673                 goto out;
674         }
675
676         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
677
678         err = -ENOMEM;
679         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
680         if (ubd_dev->queue == NULL) {
681                 *error_out = "Failed to initialize device queue";
682                 goto out;
683         }
684         ubd_dev->queue->queuedata = ubd_dev;
685
686         err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
687         if(err){
688                 *error_out = "Failed to register device";
689                 goto out_cleanup;
690         }
691
692         if(fake_major != MAJOR_NR)
693                 ubd_disk_register(fake_major, ubd_dev->size, n,
694                                   &fake_gendisk[n]);
695
696         /* perhaps this should also be under the "if (fake_major)" above */
697         /* using the fake_disk->disk_name and also the fakehd_set name */
698         if (fake_ide)
699                 make_ide_entries(ubd_gendisk[n]->disk_name);
700
701         err = 0;
702 out:
703         return err;
704
705 out_cleanup:
706         blk_cleanup_queue(ubd_dev->queue);
707         goto out;
708 }
709
710 static int ubd_config(char *str, char **error_out)
711 {
712         int n, ret;
713
714         /* This string is possibly broken up and stored, so it's only
715          * freed if ubd_setup_common fails, or if only general options
716          * were set.
717          */
718         str = kstrdup(str, GFP_KERNEL);
719         if (str == NULL) {
720                 *error_out = "Failed to allocate memory";
721                 return -ENOMEM;
722         }
723
724         ret = ubd_setup_common(str, &n, error_out);
725         if (ret)
726                 goto err_free;
727
728         if (n == -1) {
729                 ret = 0;
730                 goto err_free;
731         }
732
733         mutex_lock(&ubd_lock);
734         ret = ubd_add(n, error_out);
735         if (ret)
736                 ubd_devs[n].file = NULL;
737         mutex_unlock(&ubd_lock);
738
739 out:
740         return ret;
741
742 err_free:
743         kfree(str);
744         goto out;
745 }
746
747 static int ubd_get_config(char *name, char *str, int size, char **error_out)
748 {
749         struct ubd *ubd_dev;
750         int n, len = 0;
751
752         n = parse_unit(&name);
753         if((n >= MAX_DEV) || (n < 0)){
754                 *error_out = "ubd_get_config : device number out of range";
755                 return(-1);
756         }
757
758         ubd_dev = &ubd_devs[n];
759         mutex_lock(&ubd_lock);
760
761         if(ubd_dev->file == NULL){
762                 CONFIG_CHUNK(str, size, len, "", 1);
763                 goto out;
764         }
765
766         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
767
768         if(ubd_dev->cow.file != NULL){
769                 CONFIG_CHUNK(str, size, len, ",", 0);
770                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
771         }
772         else CONFIG_CHUNK(str, size, len, "", 1);
773
774  out:
775         mutex_unlock(&ubd_lock);
776         return(len);
777 }
778
779 static int ubd_id(char **str, int *start_out, int *end_out)
780 {
781         int n;
782
783         n = parse_unit(str);
784         *start_out = 0;
785         *end_out = MAX_DEV - 1;
786         return n;
787 }
788
789 static int ubd_remove(int n, char **error_out)
790 {
791         struct ubd *ubd_dev;
792         int err = -ENODEV;
793
794         mutex_lock(&ubd_lock);
795
796         if(ubd_gendisk[n] == NULL)
797                 goto out;
798
799         ubd_dev = &ubd_devs[n];
800
801         if(ubd_dev->file == NULL)
802                 goto out;
803
804         /* you cannot remove a open disk */
805         err = -EBUSY;
806         if(ubd_dev->count > 0)
807                 goto out;
808
809         del_gendisk(ubd_gendisk[n]);
810         put_disk(ubd_gendisk[n]);
811         ubd_gendisk[n] = NULL;
812
813         if(fake_gendisk[n] != NULL){
814                 del_gendisk(fake_gendisk[n]);
815                 put_disk(fake_gendisk[n]);
816                 fake_gendisk[n] = NULL;
817         }
818
819         blk_cleanup_queue(ubd_dev->queue);
820         platform_device_unregister(&ubd_dev->pdev);
821         *ubd_dev = ((struct ubd) DEFAULT_UBD);
822         err = 0;
823 out:
824         mutex_unlock(&ubd_lock);
825         return err;
826 }
827
828 /* All these are called by mconsole in process context and without
829  * ubd-specific locks.  The structure itself is const except for .list.
830  */
831 static struct mc_device ubd_mc = {
832         .list           = LIST_HEAD_INIT(ubd_mc.list),
833         .name           = "ubd",
834         .config         = ubd_config,
835         .get_config     = ubd_get_config,
836         .id             = ubd_id,
837         .remove         = ubd_remove,
838 };
839
840 static int __init ubd_mc_init(void)
841 {
842         mconsole_register_dev(&ubd_mc);
843         return 0;
844 }
845
846 __initcall(ubd_mc_init);
847
848 static int __init ubd0_init(void)
849 {
850         struct ubd *ubd_dev = &ubd_devs[0];
851
852         mutex_lock(&ubd_lock);
853         if(ubd_dev->file == NULL)
854                 ubd_dev->file = "root_fs";
855         mutex_unlock(&ubd_lock);
856
857         return(0);
858 }
859
860 __initcall(ubd0_init);
861
862 /* Used in ubd_init, which is an initcall */
863 static struct platform_driver ubd_driver = {
864         .driver = {
865                 .name  = DRIVER_NAME,
866         },
867 };
868
869 static int __init ubd_init(void)
870 {
871         char *error;
872         int i, err;
873
874         if (register_blkdev(MAJOR_NR, "ubd"))
875                 return -1;
876
877         if (fake_major != MAJOR_NR) {
878                 char name[sizeof("ubd_nnn\0")];
879
880                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
881                 if (register_blkdev(fake_major, "ubd"))
882                         return -1;
883         }
884         platform_driver_register(&ubd_driver);
885         mutex_lock(&ubd_lock);
886         for (i = 0; i < MAX_DEV; i++){
887                 err = ubd_add(i, &error);
888                 if(err)
889                         printk(KERN_ERR "Failed to initialize ubd device %d :"
890                                "%s\n", i, error);
891         }
892         mutex_unlock(&ubd_lock);
893         return 0;
894 }
895
896 late_initcall(ubd_init);
897
898 static int __init ubd_driver_init(void){
899         unsigned long stack;
900         int err;
901
902         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
903         if(global_openflags.s){
904                 printk(KERN_INFO "ubd: Synchronous mode\n");
905                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
906                  * enough. So use anyway the io thread. */
907         }
908         stack = alloc_stack(0, 0);
909         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
910                                  &thread_fd);
911         if(io_pid < 0){
912                 printk(KERN_ERR
913                        "ubd : Failed to start I/O thread (errno = %d) - "
914                        "falling back to synchronous I/O\n", -io_pid);
915                 io_pid = -1;
916                 return(0);
917         }
918         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
919                              IRQF_DISABLED, "ubd", ubd_devs);
920         if(err != 0)
921                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
922         return 0;
923 }
924
925 device_initcall(ubd_driver_init);
926
927 static int ubd_open(struct inode *inode, struct file *filp)
928 {
929         struct gendisk *disk = inode->i_bdev->bd_disk;
930         struct ubd *ubd_dev = disk->private_data;
931         int err = 0;
932
933         if(ubd_dev->count == 0){
934                 err = ubd_open_dev(ubd_dev);
935                 if(err){
936                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
937                                disk->disk_name, ubd_dev->file, -err);
938                         goto out;
939                 }
940         }
941         ubd_dev->count++;
942         set_disk_ro(disk, !ubd_dev->openflags.w);
943
944         /* This should no more be needed. And it didn't work anyway to exclude
945          * read-write remounting of filesystems.*/
946         /*if((filp->f_mode & FMODE_WRITE) && !ubd_dev->openflags.w){
947                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
948                 err = -EROFS;
949         }*/
950  out:
951         return(err);
952 }
953
954 static int ubd_release(struct inode * inode, struct file * file)
955 {
956         struct gendisk *disk = inode->i_bdev->bd_disk;
957         struct ubd *ubd_dev = disk->private_data;
958
959         if(--ubd_dev->count == 0)
960                 ubd_close_dev(ubd_dev);
961         return(0);
962 }
963
964 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
965                           __u64 *cow_offset, unsigned long *bitmap,
966                           __u64 bitmap_offset, unsigned long *bitmap_words,
967                           __u64 bitmap_len)
968 {
969         __u64 sector = io_offset >> 9;
970         int i, update_bitmap = 0;
971
972         for(i = 0; i < length >> 9; i++){
973                 if(cow_mask != NULL)
974                         ubd_set_bit(i, (unsigned char *) cow_mask);
975                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
976                         continue;
977
978                 update_bitmap = 1;
979                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
980         }
981
982         if(!update_bitmap)
983                 return;
984
985         *cow_offset = sector / (sizeof(unsigned long) * 8);
986
987         /* This takes care of the case where we're exactly at the end of the
988          * device, and *cow_offset + 1 is off the end.  So, just back it up
989          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
990          * for the original diagnosis.
991          */
992         if(*cow_offset == ((bitmap_len + sizeof(unsigned long) - 1) /
993                            sizeof(unsigned long) - 1))
994                 (*cow_offset)--;
995
996         bitmap_words[0] = bitmap[*cow_offset];
997         bitmap_words[1] = bitmap[*cow_offset + 1];
998
999         *cow_offset *= sizeof(unsigned long);
1000         *cow_offset += bitmap_offset;
1001 }
1002
1003 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1004                        __u64 bitmap_offset, __u64 bitmap_len)
1005 {
1006         __u64 sector = req->offset >> 9;
1007         int i;
1008
1009         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1010                 panic("Operation too long");
1011
1012         if(req->op == UBD_READ) {
1013                 for(i = 0; i < req->length >> 9; i++){
1014                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1015                                 ubd_set_bit(i, (unsigned char *)
1016                                             &req->sector_mask);
1017                 }
1018         }
1019         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1020                            &req->cow_offset, bitmap, bitmap_offset,
1021                            req->bitmap_words, bitmap_len);
1022 }
1023
1024 /* Called with dev->lock held */
1025 static int prepare_request(struct request *req, struct io_thread_req *io_req)
1026 {
1027         struct gendisk *disk = req->rq_disk;
1028         struct ubd *ubd_dev = disk->private_data;
1029         __u64 offset;
1030         int len;
1031
1032         /* This should be impossible now */
1033         if((rq_data_dir(req) == WRITE) && !ubd_dev->openflags.w){
1034                 printk("Write attempted on readonly ubd device %s\n",
1035                        disk->disk_name);
1036                 end_request(req, 0);
1037                 return(1);
1038         }
1039
1040         offset = ((__u64) req->sector) << 9;
1041         len = req->current_nr_sectors << 9;
1042
1043         io_req->req = req;
1044         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd : ubd_dev->fd;
1045         io_req->fds[1] = ubd_dev->fd;
1046         io_req->cow_offset = -1;
1047         io_req->offset = offset;
1048         io_req->length = len;
1049         io_req->error = 0;
1050         io_req->sector_mask = 0;
1051
1052         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1053         io_req->offsets[0] = 0;
1054         io_req->offsets[1] = ubd_dev->cow.data_offset;
1055         io_req->buffer = req->buffer;
1056         io_req->sectorsize = 1 << 9;
1057
1058         if(ubd_dev->cow.file != NULL)
1059                 cowify_req(io_req, ubd_dev->cow.bitmap, ubd_dev->cow.bitmap_offset,
1060                            ubd_dev->cow.bitmap_len);
1061
1062         return(0);
1063 }
1064
1065 /* Called with dev->lock held */
1066 static void do_ubd_request(request_queue_t *q)
1067 {
1068         struct io_thread_req io_req;
1069         struct request *req;
1070         int err, n;
1071
1072         if(thread_fd == -1){
1073                 while((req = elv_next_request(q)) != NULL){
1074                         err = prepare_request(req, &io_req);
1075                         if(!err){
1076                                 do_io(&io_req);
1077                                 __ubd_finish(req, io_req.error);
1078                         }
1079                 }
1080         }
1081         else {
1082                 struct ubd *dev = q->queuedata;
1083                 if(dev->active || (req = elv_next_request(q)) == NULL)
1084                         return;
1085                 err = prepare_request(req, &io_req);
1086                 if(!err){
1087                         dev->active = 1;
1088                         n = os_write_file(thread_fd, (char *) &io_req,
1089                                          sizeof(io_req));
1090                         if(n != sizeof(io_req))
1091                                 printk("write to io thread failed, "
1092                                        "errno = %d\n", -n);
1093                 }
1094         }
1095 }
1096
1097 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1098 {
1099         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1100
1101         geo->heads = 128;
1102         geo->sectors = 32;
1103         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1104         return 0;
1105 }
1106
1107 static int ubd_ioctl(struct inode * inode, struct file * file,
1108                      unsigned int cmd, unsigned long arg)
1109 {
1110         struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
1111         struct hd_driveid ubd_id = {
1112                 .cyls           = 0,
1113                 .heads          = 128,
1114                 .sectors        = 32,
1115         };
1116
1117         switch (cmd) {
1118                 struct cdrom_volctrl volume;
1119         case HDIO_GET_IDENTITY:
1120                 ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
1121                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1122                                  sizeof(ubd_id)))
1123                         return(-EFAULT);
1124                 return(0);
1125
1126         case CDROMVOLREAD:
1127                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1128                         return(-EFAULT);
1129                 volume.channel0 = 255;
1130                 volume.channel1 = 255;
1131                 volume.channel2 = 255;
1132                 volume.channel3 = 255;
1133                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1134                         return(-EFAULT);
1135                 return(0);
1136         }
1137         return(-EINVAL);
1138 }
1139
1140 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
1141 {
1142         struct uml_stat buf1, buf2;
1143         int err;
1144
1145         if(from_cmdline == NULL)
1146                 return 0;
1147         if(!strcmp(from_cmdline, from_cow))
1148                 return 0;
1149
1150         err = os_stat_file(from_cmdline, &buf1);
1151         if(err < 0){
1152                 printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
1153                 return 0;
1154         }
1155         err = os_stat_file(from_cow, &buf2);
1156         if(err < 0){
1157                 printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
1158                 return 1;
1159         }
1160         if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
1161                 return 0;
1162
1163         printk("Backing file mismatch - \"%s\" requested,\n"
1164                "\"%s\" specified in COW header of \"%s\"\n",
1165                from_cmdline, from_cow, cow);
1166         return 1;
1167 }
1168
1169 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
1170 {
1171         unsigned long modtime;
1172         unsigned long long actual;
1173         int err;
1174
1175         err = os_file_modtime(file, &modtime);
1176         if(err < 0){
1177                 printk("Failed to get modification time of backing file "
1178                        "\"%s\", err = %d\n", file, -err);
1179                 return(err);
1180         }
1181
1182         err = os_file_size(file, &actual);
1183         if(err < 0){
1184                 printk("Failed to get size of backing file \"%s\", "
1185                        "err = %d\n", file, -err);
1186                 return(err);
1187         }
1188
1189         if(actual != size){
1190                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
1191                  * the typecast.*/
1192                 printk("Size mismatch (%llu vs %llu) of COW header vs backing "
1193                        "file\n", (unsigned long long) size, actual);
1194                 return(-EINVAL);
1195         }
1196         if(modtime != mtime){
1197                 printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
1198                        "file\n", mtime, modtime);
1199                 return(-EINVAL);
1200         }
1201         return(0);
1202 }
1203
1204 int read_cow_bitmap(int fd, void *buf, int offset, int len)
1205 {
1206         int err;
1207
1208         err = os_seek_file(fd, offset);
1209         if(err < 0)
1210                 return(err);
1211
1212         err = os_read_file(fd, buf, len);
1213         if(err < 0)
1214                 return(err);
1215
1216         return(0);
1217 }
1218
1219 int open_ubd_file(char *file, struct openflags *openflags, int shared,
1220                   char **backing_file_out, int *bitmap_offset_out,
1221                   unsigned long *bitmap_len_out, int *data_offset_out,
1222                   int *create_cow_out)
1223 {
1224         time_t mtime;
1225         unsigned long long size;
1226         __u32 version, align;
1227         char *backing_file;
1228         int fd, err, sectorsize, asked_switch, mode = 0644;
1229
1230         fd = os_open_file(file, *openflags, mode);
1231         if (fd < 0) {
1232                 if ((fd == -ENOENT) && (create_cow_out != NULL))
1233                         *create_cow_out = 1;
1234                 if (!openflags->w ||
1235                    ((fd != -EROFS) && (fd != -EACCES)))
1236                         return fd;
1237                 openflags->w = 0;
1238                 fd = os_open_file(file, *openflags, mode);
1239                 if (fd < 0)
1240                         return fd;
1241         }
1242
1243         if(shared)
1244                 printk("Not locking \"%s\" on the host\n", file);
1245         else {
1246                 err = os_lock_file(fd, openflags->w);
1247                 if(err < 0){
1248                         printk("Failed to lock '%s', err = %d\n", file, -err);
1249                         goto out_close;
1250                 }
1251         }
1252
1253         /* Successful return case! */
1254         if(backing_file_out == NULL)
1255                 return(fd);
1256
1257         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
1258                               &size, &sectorsize, &align, bitmap_offset_out);
1259         if(err && (*backing_file_out != NULL)){
1260                 printk("Failed to read COW header from COW file \"%s\", "
1261                        "errno = %d\n", file, -err);
1262                 goto out_close;
1263         }
1264         if(err)
1265                 return(fd);
1266
1267         asked_switch = path_requires_switch(*backing_file_out, backing_file, file);
1268
1269         /* Allow switching only if no mismatch. */
1270         if (asked_switch && !backing_file_mismatch(*backing_file_out, size, mtime)) {
1271                 printk("Switching backing file to '%s'\n", *backing_file_out);
1272                 err = write_cow_header(file, fd, *backing_file_out,
1273                                        sectorsize, align, &size);
1274                 if (err) {
1275                         printk("Switch failed, errno = %d\n", -err);
1276                         goto out_close;
1277                 }
1278         } else {
1279                 *backing_file_out = backing_file;
1280                 err = backing_file_mismatch(*backing_file_out, size, mtime);
1281                 if (err)
1282                         goto out_close;
1283         }
1284
1285         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
1286                   bitmap_len_out, data_offset_out);
1287
1288         return fd;
1289  out_close:
1290         os_close_file(fd);
1291         return err;
1292 }
1293
1294 int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
1295                     int sectorsize, int alignment, int *bitmap_offset_out,
1296                     unsigned long *bitmap_len_out, int *data_offset_out)
1297 {
1298         int err, fd;
1299
1300         flags.c = 1;
1301         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
1302         if(fd < 0){
1303                 err = fd;
1304                 printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
1305                        -err);
1306                 goto out;
1307         }
1308
1309         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
1310                             bitmap_offset_out, bitmap_len_out,
1311                             data_offset_out);
1312         if(!err)
1313                 return(fd);
1314         os_close_file(fd);
1315  out:
1316         return(err);
1317 }
1318
1319 static int update_bitmap(struct io_thread_req *req)
1320 {
1321         int n;
1322
1323         if(req->cow_offset == -1)
1324                 return(0);
1325
1326         n = os_seek_file(req->fds[1], req->cow_offset);
1327         if(n < 0){
1328                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1329                 return(1);
1330         }
1331
1332         n = os_write_file(req->fds[1], &req->bitmap_words,
1333                           sizeof(req->bitmap_words));
1334         if(n != sizeof(req->bitmap_words)){
1335                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1336                        req->fds[1]);
1337                 return(1);
1338         }
1339
1340         return(0);
1341 }
1342
1343 void do_io(struct io_thread_req *req)
1344 {
1345         char *buf;
1346         unsigned long len;
1347         int n, nsectors, start, end, bit;
1348         int err;
1349         __u64 off;
1350
1351         nsectors = req->length / req->sectorsize;
1352         start = 0;
1353         do {
1354                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1355                 end = start;
1356                 while((end < nsectors) &&
1357                       (ubd_test_bit(end, (unsigned char *)
1358                                     &req->sector_mask) == bit))
1359                         end++;
1360
1361                 off = req->offset + req->offsets[bit] +
1362                         start * req->sectorsize;
1363                 len = (end - start) * req->sectorsize;
1364                 buf = &req->buffer[start * req->sectorsize];
1365
1366                 err = os_seek_file(req->fds[bit], off);
1367                 if(err < 0){
1368                         printk("do_io - lseek failed : err = %d\n", -err);
1369                         req->error = 1;
1370                         return;
1371                 }
1372                 if(req->op == UBD_READ){
1373                         n = 0;
1374                         do {
1375                                 buf = &buf[n];
1376                                 len -= n;
1377                                 n = os_read_file(req->fds[bit], buf, len);
1378                                 if (n < 0) {
1379                                         printk("do_io - read failed, err = %d "
1380                                                "fd = %d\n", -n, req->fds[bit]);
1381                                         req->error = 1;
1382                                         return;
1383                                 }
1384                         } while((n < len) && (n != 0));
1385                         if (n < len) memset(&buf[n], 0, len - n);
1386                 } else {
1387                         n = os_write_file(req->fds[bit], buf, len);
1388                         if(n != len){
1389                                 printk("do_io - write failed err = %d "
1390                                        "fd = %d\n", -n, req->fds[bit]);
1391                                 req->error = 1;
1392                                 return;
1393                         }
1394                 }
1395
1396                 start = end;
1397         } while(start < nsectors);
1398
1399         req->error = update_bitmap(req);
1400 }
1401
1402 /* Changed in start_io_thread, which is serialized by being called only
1403  * from ubd_init, which is an initcall.
1404  */
1405 int kernel_fd = -1;
1406
1407 /* Only changed by the io thread. XXX: currently unused. */
1408 static int io_count = 0;
1409
1410 int io_thread(void *arg)
1411 {
1412         struct io_thread_req req;
1413         int n;
1414
1415         ignore_sigwinch_sig();
1416         while(1){
1417                 n = os_read_file(kernel_fd, &req, sizeof(req));
1418                 if(n != sizeof(req)){
1419                         if(n < 0)
1420                                 printk("io_thread - read failed, fd = %d, "
1421                                        "err = %d\n", kernel_fd, -n);
1422                         else {
1423                                 printk("io_thread - short read, fd = %d, "
1424                                        "length = %d\n", kernel_fd, n);
1425                         }
1426                         continue;
1427                 }
1428                 io_count++;
1429                 do_io(&req);
1430                 n = os_write_file(kernel_fd, &req, sizeof(req));
1431                 if(n != sizeof(req))
1432                         printk("io_thread - write failed, fd = %d, err = %d\n",
1433                                kernel_fd, -n);
1434         }
1435
1436         return 0;
1437 }