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[linux-3.10.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/config.h"
24 #include "linux/module.h"
25 #include "linux/blkdev.h"
26 #include "linux/hdreg.h"
27 #include "linux/init.h"
28 #include "linux/devfs_fs_kernel.h"
29 #include "linux/cdrom.h"
30 #include "linux/proc_fs.h"
31 #include "linux/ctype.h"
32 #include "linux/capability.h"
33 #include "linux/mm.h"
34 #include "linux/vmalloc.h"
35 #include "linux/blkpg.h"
36 #include "linux/genhd.h"
37 #include "linux/spinlock.h"
38 #include "asm/segment.h"
39 #include "asm/uaccess.h"
40 #include "asm/irq.h"
41 #include "asm/types.h"
42 #include "asm/tlbflush.h"
43 #include "user_util.h"
44 #include "mem_user.h"
45 #include "kern_util.h"
46 #include "kern.h"
47 #include "mconsole_kern.h"
48 #include "init.h"
49 #include "irq_user.h"
50 #include "irq_kern.h"
51 #include "ubd_user.h"
52 #include "2_5compat.h"
53 #include "os.h"
54 #include "mem.h"
55 #include "mem_kern.h"
56 #include "cow.h"
57
58 enum ubd_req { UBD_READ, UBD_WRITE, UBD_MMAP };
59
60 struct io_thread_req {
61         enum ubd_req op;
62         int fds[2];
63         unsigned long offsets[2];
64         unsigned long long offset;
65         unsigned long length;
66         char *buffer;
67         int sectorsize;
68         unsigned long sector_mask;
69         unsigned long long cow_offset;
70         unsigned long bitmap_words[2];
71         int map_fd;
72         unsigned long long map_offset;
73         int error;
74 };
75
76 extern int open_ubd_file(char *file, struct openflags *openflags,
77                          char **backing_file_out, int *bitmap_offset_out,
78                          unsigned long *bitmap_len_out, int *data_offset_out,
79                          int *create_cow_out);
80 extern int create_cow_file(char *cow_file, char *backing_file,
81                            struct openflags flags, int sectorsize,
82                            int alignment, int *bitmap_offset_out,
83                            unsigned long *bitmap_len_out,
84                            int *data_offset_out);
85 extern int read_cow_bitmap(int fd, void *buf, int offset, int len);
86 extern void do_io(struct io_thread_req *req);
87
88 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
89 {
90         __u64 n;
91         int bits, off;
92
93         bits = sizeof(data[0]) * 8;
94         n = bit / bits;
95         off = bit % bits;
96         return((data[n] & (1 << off)) != 0);
97 }
98
99 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
100 {
101         __u64 n;
102         int bits, off;
103
104         bits = sizeof(data[0]) * 8;
105         n = bit / bits;
106         off = bit % bits;
107         data[n] |= (1 << off);
108 }
109 /*End stuff from ubd_user.h*/
110
111 #define DRIVER_NAME "uml-blkdev"
112
113 static DEFINE_SPINLOCK(ubd_io_lock);
114 static DEFINE_SPINLOCK(ubd_lock);
115
116 static void (*do_ubd)(void);
117
118 static int ubd_open(struct inode * inode, struct file * filp);
119 static int ubd_release(struct inode * inode, struct file * file);
120 static int ubd_ioctl(struct inode * inode, struct file * file,
121                      unsigned int cmd, unsigned long arg);
122
123 #define MAX_DEV (8)
124
125 /* Changed in early boot */
126 static int ubd_do_mmap = 0;
127 #define UBD_MMAP_BLOCK_SIZE PAGE_SIZE
128
129 static struct block_device_operations ubd_blops = {
130         .owner          = THIS_MODULE,
131         .open           = ubd_open,
132         .release        = ubd_release,
133         .ioctl          = ubd_ioctl,
134 };
135
136 /* Protected by the queue_lock */
137 static request_queue_t *ubd_queue;
138
139 /* Protected by ubd_lock */
140 static int fake_major = MAJOR_NR;
141
142 static struct gendisk *ubd_gendisk[MAX_DEV];
143 static struct gendisk *fake_gendisk[MAX_DEV];
144  
145 #ifdef CONFIG_BLK_DEV_UBD_SYNC
146 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
147                                          .cl = 1 })
148 #else
149 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
150                                          .cl = 1 })
151 #endif
152
153 /* Not protected - changed only in ubd_setup_common and then only to
154  * to enable O_SYNC.
155  */
156 static struct openflags global_openflags = OPEN_FLAGS;
157
158 struct cow {
159         /* This is the backing file, actually */
160         char *file;
161         int fd;
162         unsigned long *bitmap;
163         unsigned long bitmap_len;
164         int bitmap_offset;
165         int data_offset;
166 };
167
168 struct ubd {
169         char *file;
170         int count;
171         int fd;
172         __u64 size;
173         struct openflags boot_openflags;
174         struct openflags openflags;
175         int no_cow;
176         struct cow cow;
177         struct platform_device pdev;
178
179         int map_writes;
180         int map_reads;
181         int nomap_writes;
182         int nomap_reads;
183         int write_maps;
184 };
185
186 #define DEFAULT_COW { \
187         .file =                 NULL, \
188         .fd =                   -1, \
189         .bitmap =               NULL, \
190         .bitmap_offset =        0, \
191         .data_offset =          0, \
192 }
193
194 #define DEFAULT_UBD { \
195         .file =                 NULL, \
196         .count =                0, \
197         .fd =                   -1, \
198         .size =                 -1, \
199         .boot_openflags =       OPEN_FLAGS, \
200         .openflags =            OPEN_FLAGS, \
201         .no_cow =               0, \
202         .cow =                  DEFAULT_COW, \
203         .map_writes             = 0, \
204         .map_reads              = 0, \
205         .nomap_writes           = 0, \
206         .nomap_reads            = 0, \
207         .write_maps             = 0, \
208 }
209
210 struct ubd ubd_dev[MAX_DEV] = { [ 0 ... MAX_DEV - 1 ] = DEFAULT_UBD };
211
212 static int ubd0_init(void)
213 {
214         struct ubd *dev = &ubd_dev[0];
215
216         if(dev->file == NULL)
217                 dev->file = "root_fs";
218         return(0);
219 }
220
221 __initcall(ubd0_init);
222
223 /* Only changed by fake_ide_setup which is a setup */
224 static int fake_ide = 0;
225 static struct proc_dir_entry *proc_ide_root = NULL;
226 static struct proc_dir_entry *proc_ide = NULL;
227
228 static void make_proc_ide(void)
229 {
230         proc_ide_root = proc_mkdir("ide", NULL);
231         proc_ide = proc_mkdir("ide0", proc_ide_root);
232 }
233
234 static int proc_ide_read_media(char *page, char **start, off_t off, int count,
235                                int *eof, void *data)
236 {
237         int len;
238
239         strcpy(page, "disk\n");
240         len = strlen("disk\n");
241         len -= off;
242         if (len < count){
243                 *eof = 1;
244                 if (len <= 0) return 0;
245         }
246         else len = count;
247         *start = page + off;
248         return len;
249 }
250
251 static void make_ide_entries(char *dev_name)
252 {
253         struct proc_dir_entry *dir, *ent;
254         char name[64];
255
256         if(proc_ide_root == NULL) make_proc_ide();
257
258         dir = proc_mkdir(dev_name, proc_ide);
259         if(!dir) return;
260
261         ent = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
262         if(!ent) return;
263         ent->nlink = 1;
264         ent->data = NULL;
265         ent->read_proc = proc_ide_read_media;
266         ent->write_proc = NULL;
267         sprintf(name,"ide0/%s", dev_name);
268         proc_symlink(dev_name, proc_ide_root, name);
269 }
270
271 static int fake_ide_setup(char *str)
272 {
273         fake_ide = 1;
274         return(1);
275 }
276
277 __setup("fake_ide", fake_ide_setup);
278
279 __uml_help(fake_ide_setup,
280 "fake_ide\n"
281 "    Create ide0 entries that map onto ubd devices.\n\n"
282 );
283
284 static int parse_unit(char **ptr)
285 {
286         char *str = *ptr, *end;
287         int n = -1;
288
289         if(isdigit(*str)) {
290                 n = simple_strtoul(str, &end, 0);
291                 if(end == str)
292                         return(-1);
293                 *ptr = end;
294         }
295         else if (('a' <= *str) && (*str <= 'h')) {
296                 n = *str - 'a';
297                 str++;
298                 *ptr = str;
299         }
300         return(n);
301 }
302
303 static int ubd_setup_common(char *str, int *index_out)
304 {
305         struct ubd *dev;
306         struct openflags flags = global_openflags;
307         char *backing_file;
308         int n, err, i;
309
310         if(index_out) *index_out = -1;
311         n = *str;
312         if(n == '='){
313                 char *end;
314                 int major;
315
316                 str++;
317                 if(!strcmp(str, "mmap")){
318                         CHOOSE_MODE(printk("mmap not supported by the ubd "
319                                            "driver in tt mode\n"),
320                                     ubd_do_mmap = 1);
321                         return(0);
322                 }
323
324                 if(!strcmp(str, "sync")){
325                         global_openflags = of_sync(global_openflags);
326                         return(0);
327                 }
328                 major = simple_strtoul(str, &end, 0);
329                 if((*end != '\0') || (end == str)){
330                         printk(KERN_ERR 
331                                "ubd_setup : didn't parse major number\n");
332                         return(1);
333                 }
334
335                 err = 1;
336                 spin_lock(&ubd_lock);
337                 if(fake_major != MAJOR_NR){
338                         printk(KERN_ERR "Can't assign a fake major twice\n");
339                         goto out1;
340                 }
341  
342                 fake_major = major;
343
344                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
345                        major);
346                 err = 0;
347         out1:
348                 spin_unlock(&ubd_lock);
349                 return(err);
350         }
351
352         n = parse_unit(&str);
353         if(n < 0){
354                 printk(KERN_ERR "ubd_setup : couldn't parse unit number "
355                        "'%s'\n", str);
356                 return(1);
357         }
358         if(n >= MAX_DEV){
359                 printk(KERN_ERR "ubd_setup : index %d out of range "
360                        "(%d devices, from 0 to %d)\n", n, MAX_DEV, MAX_DEV - 1);
361                 return(1);
362         }
363
364         err = 1;
365         spin_lock(&ubd_lock);
366
367         dev = &ubd_dev[n];
368         if(dev->file != NULL){
369                 printk(KERN_ERR "ubd_setup : device already configured\n");
370                 goto out;
371         }
372
373         if (index_out)
374                 *index_out = n;
375
376         for (i = 0; i < 4; i++) {
377                 switch (*str) {
378                 case 'r':
379                         flags.w = 0;
380                         break;
381                 case 's':
382                         flags.s = 1;
383                         break;
384                 case 'd':
385                         dev->no_cow = 1;
386                         break;
387                 case '=':
388                         str++;
389                         goto break_loop;
390                 default:
391                         printk(KERN_ERR "ubd_setup : Expected '=' or flag letter (r,s or d)\n");
392                         goto out;
393                 }
394                 str++;
395         }
396
397         if (*str == '=')
398                 printk(KERN_ERR "ubd_setup : Too many flags specified\n");
399         else
400                 printk(KERN_ERR "ubd_setup : Expected '='\n");
401         goto out;
402
403 break_loop:
404         err = 0;
405         backing_file = strchr(str, ',');
406
407         if (!backing_file) {
408                 backing_file = strchr(str, ':');
409         }
410
411         if(backing_file){
412                 if(dev->no_cow)
413                         printk(KERN_ERR "Can't specify both 'd' and a "
414                                "cow file\n");
415                 else {
416                         *backing_file = '\0';
417                         backing_file++;
418                 }
419         }
420         dev->file = str;
421         dev->cow.file = backing_file;
422         dev->boot_openflags = flags;
423 out:
424         spin_unlock(&ubd_lock);
425         return(err);
426 }
427
428 static int ubd_setup(char *str)
429 {
430         ubd_setup_common(str, NULL);
431         return(1);
432 }
433
434 __setup("ubd", ubd_setup);
435 __uml_help(ubd_setup,
436 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
437 "    This is used to associate a device with a file in the underlying\n"
438 "    filesystem. When specifying two filenames, the first one is the\n"
439 "    COW name and the second is the backing file name. As separator you can\n"
440 "    use either a ':' or a ',': the first one allows writing things like;\n"
441 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
442 "    while with a ',' the shell would not expand the 2nd '~'.\n"
443 "    When using only one filename, UML will detect whether to thread it like\n"
444 "    a COW file or a backing file. To override this detection, add the 'd'\n"
445 "    flag:\n"
446 "       ubd0d=BackingFile\n"
447 "    Usually, there is a filesystem in the file, but \n"
448 "    that's not required. Swap devices containing swap files can be\n"
449 "    specified like this. Also, a file which doesn't contain a\n"
450 "    filesystem can have its contents read in the virtual \n"
451 "    machine by running 'dd' on the device. <n> must be in the range\n"
452 "    0 to 7. Appending an 'r' to the number will cause that device\n"
453 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
454 "    an 's' will cause data to be written to disk on the host immediately.\n\n"
455 );
456
457 static int udb_setup(char *str)
458 {
459         printk("udb%s specified on command line is almost certainly a ubd -> "
460                "udb TYPO\n", str);
461         return(1);
462 }
463
464 __setup("udb", udb_setup);
465 __uml_help(udb_setup,
466 "udb\n"
467 "    This option is here solely to catch ubd -> udb typos, which can be\n\n"
468 "    to impossible to catch visually unless you specifically look for\n\n"
469 "    them.  The only result of any option starting with 'udb' is an error\n\n"
470 "    in the boot output.\n\n"
471 );
472
473 static int fakehd_set = 0;
474 static int fakehd(char *str)
475 {
476         printk(KERN_INFO "fakehd : Changing ubd name to \"hd\".\n");
477         fakehd_set = 1;
478         return 1;
479 }
480
481 __setup("fakehd", fakehd);
482 __uml_help(fakehd,
483 "fakehd\n"
484 "    Change the ubd device name to \"hd\".\n\n"
485 );
486
487 static void do_ubd_request(request_queue_t * q);
488
489 /* Only changed by ubd_init, which is an initcall. */
490 int thread_fd = -1;
491
492 /* Changed by ubd_handler, which is serialized because interrupts only
493  * happen on CPU 0.
494  */
495 int intr_count = 0;
496
497 /* call ubd_finish if you need to serialize */
498 static void __ubd_finish(struct request *req, int error)
499 {
500         int nsect;
501
502         if(error){
503                 end_request(req, 0);
504                 return;
505         }
506         nsect = req->current_nr_sectors;
507         req->sector += nsect;
508         req->buffer += nsect << 9;
509         req->errors = 0;
510         req->nr_sectors -= nsect;
511         req->current_nr_sectors = 0;
512         end_request(req, 1);
513 }
514
515 static inline void ubd_finish(struct request *req, int error)
516 {
517         spin_lock(&ubd_io_lock);
518         __ubd_finish(req, error);
519         spin_unlock(&ubd_io_lock);
520 }
521
522 /* Called without ubd_io_lock held */
523 static void ubd_handler(void)
524 {
525         struct io_thread_req req;
526         struct request *rq = elv_next_request(ubd_queue);
527         int n, err;
528
529         do_ubd = NULL;
530         intr_count++;
531         n = os_read_file(thread_fd, &req, sizeof(req));
532         if(n != sizeof(req)){
533                 printk(KERN_ERR "Pid %d - spurious interrupt in ubd_handler, "
534                        "err = %d\n", os_getpid(), -n);
535                 spin_lock(&ubd_io_lock);
536                 end_request(rq, 0);
537                 spin_unlock(&ubd_io_lock);
538                 return;
539         }
540         
541         if((req.op != UBD_MMAP) &&
542            ((req.offset != ((__u64) (rq->sector)) << 9) ||
543             (req.length != (rq->current_nr_sectors) << 9)))
544                 panic("I/O op mismatch");
545         
546         if(req.map_fd != -1){
547                 err = physmem_subst_mapping(req.buffer, req.map_fd,
548                                             req.map_offset, 1);
549                 if(err)
550                         printk("ubd_handler - physmem_subst_mapping failed, "
551                                "err = %d\n", -err);
552         }
553
554         ubd_finish(rq, req.error);
555         reactivate_fd(thread_fd, UBD_IRQ);      
556         do_ubd_request(ubd_queue);
557 }
558
559 static irqreturn_t ubd_intr(int irq, void *dev, struct pt_regs *unused)
560 {
561         ubd_handler();
562         return(IRQ_HANDLED);
563 }
564
565 /* Only changed by ubd_init, which is an initcall. */
566 static int io_pid = -1;
567
568 void kill_io_thread(void)
569 {
570         if(io_pid != -1) 
571                 os_kill_process(io_pid, 1);
572 }
573
574 __uml_exitcall(kill_io_thread);
575
576 static int ubd_file_size(struct ubd *dev, __u64 *size_out)
577 {
578         char *file;
579
580         file = dev->cow.file ? dev->cow.file : dev->file;
581         return(os_file_size(file, size_out));
582 }
583
584 static void ubd_close(struct ubd *dev)
585 {
586         if(ubd_do_mmap)
587                 physmem_forget_descriptor(dev->fd);
588         os_close_file(dev->fd);
589         if(dev->cow.file == NULL)
590                 return;
591
592         if(ubd_do_mmap)
593                 physmem_forget_descriptor(dev->cow.fd);
594         os_close_file(dev->cow.fd);
595         vfree(dev->cow.bitmap);
596         dev->cow.bitmap = NULL;
597 }
598
599 static int ubd_open_dev(struct ubd *dev)
600 {
601         struct openflags flags;
602         char **back_ptr;
603         int err, create_cow, *create_ptr;
604
605         dev->openflags = dev->boot_openflags;
606         create_cow = 0;
607         create_ptr = (dev->cow.file != NULL) ? &create_cow : NULL;
608         back_ptr = dev->no_cow ? NULL : &dev->cow.file;
609         dev->fd = open_ubd_file(dev->file, &dev->openflags, back_ptr,
610                                 &dev->cow.bitmap_offset, &dev->cow.bitmap_len, 
611                                 &dev->cow.data_offset, create_ptr);
612
613         if((dev->fd == -ENOENT) && create_cow){
614                 dev->fd = create_cow_file(dev->file, dev->cow.file, 
615                                           dev->openflags, 1 << 9, PAGE_SIZE,
616                                           &dev->cow.bitmap_offset, 
617                                           &dev->cow.bitmap_len,
618                                           &dev->cow.data_offset);
619                 if(dev->fd >= 0){
620                         printk(KERN_INFO "Creating \"%s\" as COW file for "
621                                "\"%s\"\n", dev->file, dev->cow.file);
622                 }
623         }
624
625         if(dev->fd < 0){
626                 printk("Failed to open '%s', errno = %d\n", dev->file,
627                        -dev->fd);
628                 return(dev->fd);
629         }
630
631         if(dev->cow.file != NULL){
632                 err = -ENOMEM;
633                 dev->cow.bitmap = (void *) vmalloc(dev->cow.bitmap_len);
634                 if(dev->cow.bitmap == NULL){
635                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
636                         goto error;
637                 }
638                 flush_tlb_kernel_vm();
639
640                 err = read_cow_bitmap(dev->fd, dev->cow.bitmap, 
641                                       dev->cow.bitmap_offset, 
642                                       dev->cow.bitmap_len);
643                 if(err < 0)
644                         goto error;
645
646                 flags = dev->openflags;
647                 flags.w = 0;
648                 err = open_ubd_file(dev->cow.file, &flags, NULL, NULL, NULL, 
649                                     NULL, NULL);
650                 if(err < 0) goto error;
651                 dev->cow.fd = err;
652         }
653         return(0);
654  error:
655         os_close_file(dev->fd);
656         return(err);
657 }
658
659 static int ubd_new_disk(int major, u64 size, int unit,
660                         struct gendisk **disk_out)
661                         
662 {
663         struct gendisk *disk;
664         char from[sizeof("ubd/nnnnn\0")], to[sizeof("discnnnnn/disc\0")];
665         int err;
666
667         disk = alloc_disk(1 << UBD_SHIFT);
668         if(disk == NULL)
669                 return(-ENOMEM);
670
671         disk->major = major;
672         disk->first_minor = unit << UBD_SHIFT;
673         disk->fops = &ubd_blops;
674         set_capacity(disk, size / 512);
675         if(major == MAJOR_NR){
676                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
677                 sprintf(disk->devfs_name, "ubd/disc%d", unit);
678                 sprintf(from, "ubd/%d", unit);
679                 sprintf(to, "disc%d/disc", unit);
680                 err = devfs_mk_symlink(from, to);
681                 if(err)
682                         printk("ubd_new_disk failed to make link from %s to "
683                                "%s, error = %d\n", from, to, err);
684         }
685         else {
686                 sprintf(disk->disk_name, "ubd_fake%d", unit);
687                 sprintf(disk->devfs_name, "ubd_fake/disc%d", unit);
688         }
689
690         /* sysfs register (not for ide fake devices) */
691         if (major == MAJOR_NR) {
692                 ubd_dev[unit].pdev.id   = unit;
693                 ubd_dev[unit].pdev.name = DRIVER_NAME;
694                 platform_device_register(&ubd_dev[unit].pdev);
695                 disk->driverfs_dev = &ubd_dev[unit].pdev.dev;
696         }
697
698         disk->private_data = &ubd_dev[unit];
699         disk->queue = ubd_queue;
700         add_disk(disk);
701
702         *disk_out = disk;
703         return 0;
704 }
705
706 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
707
708 static int ubd_add(int n)
709 {
710         struct ubd *dev = &ubd_dev[n];
711         int err;
712
713         if(dev->file == NULL)
714                 return(-ENODEV);
715
716         if (ubd_open_dev(dev))
717                 return(-ENODEV);
718
719         err = ubd_file_size(dev, &dev->size);
720         if(err < 0)
721                 return(err);
722
723         dev->size = ROUND_BLOCK(dev->size);
724
725         err = ubd_new_disk(MAJOR_NR, dev->size, n, &ubd_gendisk[n]);
726         if(err) 
727                 return(err);
728  
729         if(fake_major != MAJOR_NR)
730                 ubd_new_disk(fake_major, dev->size, n, 
731                              &fake_gendisk[n]);
732
733         /* perhaps this should also be under the "if (fake_major)" above */
734         /* using the fake_disk->disk_name and also the fakehd_set name */
735         if (fake_ide)
736                 make_ide_entries(ubd_gendisk[n]->disk_name);
737
738         ubd_close(dev);
739         return 0;
740 }
741
742 static int ubd_config(char *str)
743 {
744         int n, err;
745
746         str = uml_strdup(str);
747         if(str == NULL){
748                 printk(KERN_ERR "ubd_config failed to strdup string\n");
749                 return(1);
750         }
751         err = ubd_setup_common(str, &n);
752         if(err){
753                 kfree(str);
754                 return(-1);
755         }
756         if(n == -1) return(0);
757
758         spin_lock(&ubd_lock);
759         err = ubd_add(n);
760         if(err)
761                 ubd_dev[n].file = NULL;
762         spin_unlock(&ubd_lock);
763
764         return(err);
765 }
766
767 static int ubd_get_config(char *name, char *str, int size, char **error_out)
768 {
769         struct ubd *dev;
770         int n, len = 0;
771
772         n = parse_unit(&name);
773         if((n >= MAX_DEV) || (n < 0)){
774                 *error_out = "ubd_get_config : device number out of range";
775                 return(-1);
776         }
777
778         dev = &ubd_dev[n];
779         spin_lock(&ubd_lock);
780
781         if(dev->file == NULL){
782                 CONFIG_CHUNK(str, size, len, "", 1);
783                 goto out;
784         }
785
786         CONFIG_CHUNK(str, size, len, dev->file, 0);
787
788         if(dev->cow.file != NULL){
789                 CONFIG_CHUNK(str, size, len, ",", 0);
790                 CONFIG_CHUNK(str, size, len, dev->cow.file, 1);
791         }
792         else CONFIG_CHUNK(str, size, len, "", 1);
793
794  out:
795         spin_unlock(&ubd_lock);
796         return(len);
797 }
798
799 static int ubd_remove(char *str)
800 {
801         struct ubd *dev;
802         int n, err = -ENODEV;
803
804         n = parse_unit(&str);
805
806         if((n < 0) || (n >= MAX_DEV))
807                 return(err);
808
809         dev = &ubd_dev[n];
810         if(dev->count > 0)
811                 return(-EBUSY); /* you cannot remove a open disk */
812
813         err = 0;
814         spin_lock(&ubd_lock);
815
816         if(ubd_gendisk[n] == NULL)
817                 goto out;
818
819         del_gendisk(ubd_gendisk[n]);
820         put_disk(ubd_gendisk[n]);
821         ubd_gendisk[n] = NULL;
822
823         if(fake_gendisk[n] != NULL){
824                 del_gendisk(fake_gendisk[n]);
825                 put_disk(fake_gendisk[n]);
826                 fake_gendisk[n] = NULL;
827         }
828
829         platform_device_unregister(&dev->pdev);
830         *dev = ((struct ubd) DEFAULT_UBD);
831         err = 0;
832  out:
833         spin_unlock(&ubd_lock);
834         return(err);
835 }
836
837 static struct mc_device ubd_mc = {
838         .name           = "ubd",
839         .config         = ubd_config,
840         .get_config     = ubd_get_config,
841         .remove         = ubd_remove,
842 };
843
844 static int ubd_mc_init(void)
845 {
846         mconsole_register_dev(&ubd_mc);
847         return 0;
848 }
849
850 __initcall(ubd_mc_init);
851
852 static struct device_driver ubd_driver = {
853         .name  = DRIVER_NAME,
854         .bus   = &platform_bus_type,
855 };
856
857 int ubd_init(void)
858 {
859         int i;
860
861         devfs_mk_dir("ubd");
862         if (register_blkdev(MAJOR_NR, "ubd"))
863                 return -1;
864
865         ubd_queue = blk_init_queue(do_ubd_request, &ubd_io_lock);
866         if (!ubd_queue) {
867                 unregister_blkdev(MAJOR_NR, "ubd");
868                 return -1;
869         }
870                 
871         if (fake_major != MAJOR_NR) {
872                 char name[sizeof("ubd_nnn\0")];
873
874                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
875                 devfs_mk_dir(name);
876                 if (register_blkdev(fake_major, "ubd"))
877                         return -1;
878         }
879         driver_register(&ubd_driver);
880         for (i = 0; i < MAX_DEV; i++) 
881                 ubd_add(i);
882         return 0;
883 }
884
885 late_initcall(ubd_init);
886
887 int ubd_driver_init(void){
888         unsigned long stack;
889         int err;
890
891         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
892         if(global_openflags.s){
893                 printk(KERN_INFO "ubd: Synchronous mode\n");
894                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
895                  * enough. So use anyway the io thread. */
896         }
897         stack = alloc_stack(0, 0);
898         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *), 
899                                  &thread_fd);
900         if(io_pid < 0){
901                 printk(KERN_ERR 
902                        "ubd : Failed to start I/O thread (errno = %d) - "
903                        "falling back to synchronous I/O\n", -io_pid);
904                 io_pid = -1;
905                 return(0);
906         }
907         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr, 
908                              SA_INTERRUPT, "ubd", ubd_dev);
909         if(err != 0)
910                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
911         return(err);
912 }
913
914 device_initcall(ubd_driver_init);
915
916 static int ubd_open(struct inode *inode, struct file *filp)
917 {
918         struct gendisk *disk = inode->i_bdev->bd_disk;
919         struct ubd *dev = disk->private_data;
920         int err = 0;
921
922         if(dev->count == 0){
923                 err = ubd_open_dev(dev);
924                 if(err){
925                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
926                                disk->disk_name, dev->file, -err);
927                         goto out;
928                 }
929         }
930         dev->count++;
931         set_disk_ro(disk, !dev->openflags.w);
932
933         /* This should no more be needed. And it didn't work anyway to exclude
934          * read-write remounting of filesystems.*/
935         /*if((filp->f_mode & FMODE_WRITE) && !dev->openflags.w){
936                 if(--dev->count == 0) ubd_close(dev);
937                 err = -EROFS;
938         }*/
939  out:
940         return(err);
941 }
942
943 static int ubd_release(struct inode * inode, struct file * file)
944 {
945         struct gendisk *disk = inode->i_bdev->bd_disk;
946         struct ubd *dev = disk->private_data;
947
948         if(--dev->count == 0)
949                 ubd_close(dev);
950         return(0);
951 }
952
953 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
954                           __u64 *cow_offset, unsigned long *bitmap,
955                           __u64 bitmap_offset, unsigned long *bitmap_words,
956                           __u64 bitmap_len)
957 {
958         __u64 sector = io_offset >> 9;
959         int i, update_bitmap = 0;
960
961         for(i = 0; i < length >> 9; i++){
962                 if(cow_mask != NULL)
963                         ubd_set_bit(i, (unsigned char *) cow_mask);
964                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
965                         continue;
966
967                 update_bitmap = 1;
968                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
969         }
970
971         if(!update_bitmap)
972                 return;
973
974         *cow_offset = sector / (sizeof(unsigned long) * 8);
975
976         /* This takes care of the case where we're exactly at the end of the
977          * device, and *cow_offset + 1 is off the end.  So, just back it up
978          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
979          * for the original diagnosis.
980          */
981         if(*cow_offset == ((bitmap_len + sizeof(unsigned long) - 1) /
982                            sizeof(unsigned long) - 1))
983                 (*cow_offset)--;
984
985         bitmap_words[0] = bitmap[*cow_offset];
986         bitmap_words[1] = bitmap[*cow_offset + 1];
987
988         *cow_offset *= sizeof(unsigned long);
989         *cow_offset += bitmap_offset;
990 }
991
992 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
993                        __u64 bitmap_offset, __u64 bitmap_len)
994 {
995         __u64 sector = req->offset >> 9;
996         int i;
997
998         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
999                 panic("Operation too long");
1000
1001         if(req->op == UBD_READ) {
1002                 for(i = 0; i < req->length >> 9; i++){
1003                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1004                                 ubd_set_bit(i, (unsigned char *) 
1005                                             &req->sector_mask);
1006                 }
1007         }
1008         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1009                            &req->cow_offset, bitmap, bitmap_offset,
1010                            req->bitmap_words, bitmap_len);
1011 }
1012
1013 static int mmap_fd(struct request *req, struct ubd *dev, __u64 offset)
1014 {
1015         __u64 sector;
1016         unsigned char *bitmap;
1017         int bit, i;
1018
1019         /* mmap must have been requested on the command line */
1020         if(!ubd_do_mmap)
1021                 return(-1);
1022
1023         /* The buffer must be page aligned */
1024         if(((unsigned long) req->buffer % UBD_MMAP_BLOCK_SIZE) != 0)
1025                 return(-1);
1026
1027         /* The request must be a page long */
1028         if((req->current_nr_sectors << 9) != PAGE_SIZE)
1029                 return(-1);
1030
1031         if(dev->cow.file == NULL)
1032                 return(dev->fd);
1033
1034         sector = offset >> 9;
1035         bitmap = (unsigned char *) dev->cow.bitmap;
1036         bit = ubd_test_bit(sector, bitmap);
1037
1038         for(i = 1; i < req->current_nr_sectors; i++){
1039                 if(ubd_test_bit(sector + i, bitmap) != bit)
1040                         return(-1);
1041         }
1042
1043         if(bit || (rq_data_dir(req) == WRITE))
1044                 offset += dev->cow.data_offset;
1045
1046         /* The data on disk must be page aligned */
1047         if((offset % UBD_MMAP_BLOCK_SIZE) != 0)
1048                 return(-1);
1049
1050         return(bit ? dev->fd : dev->cow.fd);
1051 }
1052
1053 static int prepare_mmap_request(struct ubd *dev, int fd, __u64 offset,
1054                                 struct request *req,
1055                                 struct io_thread_req *io_req)
1056 {
1057         int err;
1058
1059         if(rq_data_dir(req) == WRITE){
1060                 /* Writes are almost no-ops since the new data is already in the
1061                  * host page cache
1062                  */
1063                 dev->map_writes++;
1064                 if(dev->cow.file != NULL)
1065                         cowify_bitmap(io_req->offset, io_req->length,
1066                                       &io_req->sector_mask, &io_req->cow_offset,
1067                                       dev->cow.bitmap, dev->cow.bitmap_offset,
1068                                       io_req->bitmap_words,
1069                                       dev->cow.bitmap_len);
1070         }
1071         else {
1072                 int w;
1073
1074                 if((dev->cow.file != NULL) && (fd == dev->cow.fd))
1075                         w = 0;
1076                 else w = dev->openflags.w;
1077
1078                 if((dev->cow.file != NULL) && (fd == dev->fd))
1079                         offset += dev->cow.data_offset;
1080
1081                 err = physmem_subst_mapping(req->buffer, fd, offset, w);
1082                 if(err){
1083                         printk("physmem_subst_mapping failed, err = %d\n",
1084                                -err);
1085                         return(1);
1086                 }
1087                 dev->map_reads++;
1088         }
1089         io_req->op = UBD_MMAP;
1090         io_req->buffer = req->buffer;
1091         return(0);
1092 }
1093
1094 /* Called with ubd_io_lock held */
1095 static int prepare_request(struct request *req, struct io_thread_req *io_req)
1096 {
1097         struct gendisk *disk = req->rq_disk;
1098         struct ubd *dev = disk->private_data;
1099         __u64 offset;
1100         int len, fd;
1101
1102         if(req->rq_status == RQ_INACTIVE) return(1);
1103
1104         /* This should be impossible now */
1105         if((rq_data_dir(req) == WRITE) && !dev->openflags.w){
1106                 printk("Write attempted on readonly ubd device %s\n", 
1107                        disk->disk_name);
1108                 end_request(req, 0);
1109                 return(1);
1110         }
1111
1112         offset = ((__u64) req->sector) << 9;
1113         len = req->current_nr_sectors << 9;
1114
1115         io_req->fds[0] = (dev->cow.file != NULL) ? dev->cow.fd : dev->fd;
1116         io_req->fds[1] = dev->fd;
1117         io_req->map_fd = -1;
1118         io_req->cow_offset = -1;
1119         io_req->offset = offset;
1120         io_req->length = len;
1121         io_req->error = 0;
1122         io_req->sector_mask = 0;
1123
1124         fd = mmap_fd(req, dev, io_req->offset);
1125         if(fd > 0){
1126                 /* If mmapping is otherwise OK, but the first access to the
1127                  * page is a write, then it's not mapped in yet.  So we have
1128                  * to write the data to disk first, then we can map the disk
1129                  * page in and continue normally from there.
1130                  */
1131                 if((rq_data_dir(req) == WRITE) && !is_remapped(req->buffer)){
1132                         io_req->map_fd = dev->fd;
1133                         io_req->map_offset = io_req->offset +
1134                                 dev->cow.data_offset;
1135                         dev->write_maps++;
1136                 }
1137                 else return(prepare_mmap_request(dev, fd, io_req->offset, req,
1138                                                  io_req));
1139         }
1140
1141         if(rq_data_dir(req) == READ)
1142                 dev->nomap_reads++;
1143         else dev->nomap_writes++;
1144
1145         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1146         io_req->offsets[0] = 0;
1147         io_req->offsets[1] = dev->cow.data_offset;
1148         io_req->buffer = req->buffer;
1149         io_req->sectorsize = 1 << 9;
1150
1151         if(dev->cow.file != NULL)
1152                 cowify_req(io_req, dev->cow.bitmap, dev->cow.bitmap_offset,
1153                            dev->cow.bitmap_len);
1154
1155         return(0);
1156 }
1157
1158 /* Called with ubd_io_lock held */
1159 static void do_ubd_request(request_queue_t *q)
1160 {
1161         struct io_thread_req io_req;
1162         struct request *req;
1163         int err, n;
1164
1165         if(thread_fd == -1){
1166                 while((req = elv_next_request(q)) != NULL){
1167                         err = prepare_request(req, &io_req);
1168                         if(!err){
1169                                 do_io(&io_req);
1170                                 __ubd_finish(req, io_req.error);
1171                         }
1172                 }
1173         }
1174         else {
1175                 if(do_ubd || (req = elv_next_request(q)) == NULL)
1176                         return;
1177                 err = prepare_request(req, &io_req);
1178                 if(!err){
1179                         do_ubd = ubd_handler;
1180                         n = os_write_file(thread_fd, (char *) &io_req,
1181                                          sizeof(io_req));
1182                         if(n != sizeof(io_req))
1183                                 printk("write to io thread failed, "
1184                                        "errno = %d\n", -n);
1185                 }
1186         }
1187 }
1188
1189 static int ubd_ioctl(struct inode * inode, struct file * file,
1190                      unsigned int cmd, unsigned long arg)
1191 {
1192         struct hd_geometry __user *loc = (struct hd_geometry __user *) arg;
1193         struct ubd *dev = inode->i_bdev->bd_disk->private_data;
1194         struct hd_driveid ubd_id = {
1195                 .cyls           = 0,
1196                 .heads          = 128,
1197                 .sectors        = 32,
1198         };
1199
1200         switch (cmd) {
1201                 struct hd_geometry g;
1202                 struct cdrom_volctrl volume;
1203         case HDIO_GETGEO:
1204                 if(!loc) return(-EINVAL);
1205                 g.heads = 128;
1206                 g.sectors = 32;
1207                 g.cylinders = dev->size / (128 * 32 * 512);
1208                 g.start = get_start_sect(inode->i_bdev);
1209                 return(copy_to_user(loc, &g, sizeof(g)) ? -EFAULT : 0);
1210
1211         case HDIO_GET_IDENTITY:
1212                 ubd_id.cyls = dev->size / (128 * 32 * 512);
1213                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1214                                  sizeof(ubd_id)))
1215                         return(-EFAULT);
1216                 return(0);
1217                 
1218         case CDROMVOLREAD:
1219                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1220                         return(-EFAULT);
1221                 volume.channel0 = 255;
1222                 volume.channel1 = 255;
1223                 volume.channel2 = 255;
1224                 volume.channel3 = 255;
1225                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1226                         return(-EFAULT);
1227                 return(0);
1228         }
1229         return(-EINVAL);
1230 }
1231
1232 static int ubd_check_remapped(int fd, unsigned long address, int is_write,
1233                               __u64 offset)
1234 {
1235         __u64 bitmap_offset;
1236         unsigned long new_bitmap[2];
1237         int i, err, n;
1238
1239         /* If it's not a write access, we can't do anything about it */
1240         if(!is_write)
1241                 return(0);
1242
1243         /* We have a write */
1244         for(i = 0; i < sizeof(ubd_dev) / sizeof(ubd_dev[0]); i++){
1245                 struct ubd *dev = &ubd_dev[i];
1246
1247                 if((dev->fd != fd) && (dev->cow.fd != fd))
1248                         continue;
1249
1250                 /* It's a write to a ubd device */
1251
1252                 /* This should be impossible now */
1253                 if(!dev->openflags.w){
1254                         /* It's a write access on a read-only device - probably
1255                          * shouldn't happen.  If the kernel is trying to change
1256                          * something with no intention of writing it back out,
1257                          * then this message will clue us in that this needs
1258                          * fixing
1259                          */
1260                         printk("Write access to mapped page from readonly ubd "
1261                                "device %d\n", i);
1262                         return(0);
1263                 }
1264
1265                 /* It's a write to a writeable ubd device - it must be COWed
1266                  * because, otherwise, the page would have been mapped in
1267                  * writeable
1268                  */
1269
1270                 if(!dev->cow.file)
1271                         panic("Write fault on writeable non-COW ubd device %d",
1272                               i);
1273
1274                 /* It should also be an access to the backing file since the
1275                  * COW pages should be mapped in read-write
1276                  */
1277
1278                 if(fd == dev->fd)
1279                         panic("Write fault on a backing page of ubd "
1280                               "device %d\n", i);
1281
1282                 /* So, we do the write, copying the backing data to the COW
1283                  * file...
1284                  */
1285
1286                 err = os_seek_file(dev->fd, offset + dev->cow.data_offset);
1287                 if(err < 0)
1288                         panic("Couldn't seek to %lld in COW file of ubd "
1289                               "device %d, err = %d",
1290                               offset + dev->cow.data_offset, i, -err);
1291
1292                 n = os_write_file(dev->fd, (void *) address, PAGE_SIZE);
1293                 if(n != PAGE_SIZE)
1294                         panic("Couldn't copy data to COW file of ubd "
1295                               "device %d, err = %d", i, -n);
1296
1297                 /* ... updating the COW bitmap... */
1298
1299                 cowify_bitmap(offset, PAGE_SIZE, NULL, &bitmap_offset,
1300                               dev->cow.bitmap, dev->cow.bitmap_offset,
1301                               new_bitmap, dev->cow.bitmap_len);
1302
1303                 err = os_seek_file(dev->fd, bitmap_offset);
1304                 if(err < 0)
1305                         panic("Couldn't seek to %lld in COW file of ubd "
1306                               "device %d, err = %d", bitmap_offset, i, -err);
1307
1308                 n = os_write_file(dev->fd, new_bitmap, sizeof(new_bitmap));
1309                 if(n != sizeof(new_bitmap))
1310                         panic("Couldn't update bitmap  of ubd device %d, "
1311                               "err = %d", i, -n);
1312
1313                 /* Maybe we can map the COW page in, and maybe we can't.  If
1314                  * it is a pre-V3 COW file, we can't, since the alignment will
1315                  * be wrong.  If it is a V3 or later COW file which has been
1316                  * moved to a system with a larger page size, then maybe we
1317                  * can't, depending on the exact location of the page.
1318                  */
1319
1320                 offset += dev->cow.data_offset;
1321
1322                 /* Remove the remapping, putting the original anonymous page
1323                  * back.  If the COW file can be mapped in, that is done.
1324                  * Otherwise, the COW page is read in.
1325                  */
1326
1327                 if(!physmem_remove_mapping((void *) address))
1328                         panic("Address 0x%lx not remapped by ubd device %d",
1329                               address, i);
1330                 if((offset % UBD_MMAP_BLOCK_SIZE) == 0)
1331                         physmem_subst_mapping((void *) address, dev->fd,
1332                                               offset, 1);
1333                 else {
1334                         err = os_seek_file(dev->fd, offset);
1335                         if(err < 0)
1336                                 panic("Couldn't seek to %lld in COW file of "
1337                                       "ubd device %d, err = %d", offset, i,
1338                                       -err);
1339
1340                         n = os_read_file(dev->fd, (void *) address, PAGE_SIZE);
1341                         if(n != PAGE_SIZE)
1342                                 panic("Failed to read page from offset %llx of "
1343                                       "COW file of ubd device %d, err = %d",
1344                                       offset, i, -n);
1345                 }
1346
1347                 return(1);
1348         }
1349
1350         /* It's not a write on a ubd device */
1351         return(0);
1352 }
1353
1354 static struct remapper ubd_remapper = {
1355         .list   = LIST_HEAD_INIT(ubd_remapper.list),
1356         .proc   = ubd_check_remapped,
1357 };
1358
1359 static int ubd_remapper_setup(void)
1360 {
1361         if(ubd_do_mmap)
1362                 register_remapper(&ubd_remapper);
1363
1364         return(0);
1365 }
1366
1367 __initcall(ubd_remapper_setup);
1368
1369 static int same_backing_files(char *from_cmdline, char *from_cow, char *cow)
1370 {
1371         struct uml_stat buf1, buf2;
1372         int err;
1373
1374         if(from_cmdline == NULL) return(1);
1375         if(!strcmp(from_cmdline, from_cow)) return(1);
1376
1377         err = os_stat_file(from_cmdline, &buf1);
1378         if(err < 0){
1379                 printk("Couldn't stat '%s', err = %d\n", from_cmdline, -err);
1380                 return(1);
1381         }
1382         err = os_stat_file(from_cow, &buf2);
1383         if(err < 0){
1384                 printk("Couldn't stat '%s', err = %d\n", from_cow, -err);
1385                 return(1);
1386         }
1387         if((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
1388                 return(1);
1389
1390         printk("Backing file mismatch - \"%s\" requested,\n"
1391                "\"%s\" specified in COW header of \"%s\"\n",
1392                from_cmdline, from_cow, cow);
1393         return(0);
1394 }
1395
1396 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
1397 {
1398         unsigned long modtime;
1399         long long actual;
1400         int err;
1401
1402         err = os_file_modtime(file, &modtime);
1403         if(err < 0){
1404                 printk("Failed to get modification time of backing file "
1405                        "\"%s\", err = %d\n", file, -err);
1406                 return(err);
1407         }
1408
1409         err = os_file_size(file, &actual);
1410         if(err < 0){
1411                 printk("Failed to get size of backing file \"%s\", "
1412                        "err = %d\n", file, -err);
1413                 return(err);
1414         }
1415
1416         if(actual != size){
1417                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
1418                  * the typecast.*/
1419                 printk("Size mismatch (%llu vs %llu) of COW header vs backing "
1420                        "file\n", (unsigned long long) size, actual);
1421                 return(-EINVAL);
1422         }
1423         if(modtime != mtime){
1424                 printk("mtime mismatch (%ld vs %ld) of COW header vs backing "
1425                        "file\n", mtime, modtime);
1426                 return(-EINVAL);
1427         }
1428         return(0);
1429 }
1430
1431 int read_cow_bitmap(int fd, void *buf, int offset, int len)
1432 {
1433         int err;
1434
1435         err = os_seek_file(fd, offset);
1436         if(err < 0)
1437                 return(err);
1438
1439         err = os_read_file(fd, buf, len);
1440         if(err < 0)
1441                 return(err);
1442
1443         return(0);
1444 }
1445
1446 int open_ubd_file(char *file, struct openflags *openflags,
1447                   char **backing_file_out, int *bitmap_offset_out,
1448                   unsigned long *bitmap_len_out, int *data_offset_out,
1449                   int *create_cow_out)
1450 {
1451         time_t mtime;
1452         unsigned long long size;
1453         __u32 version, align;
1454         char *backing_file;
1455         int fd, err, sectorsize, same, mode = 0644;
1456
1457         fd = os_open_file(file, *openflags, mode);
1458         if(fd < 0){
1459                 if((fd == -ENOENT) && (create_cow_out != NULL))
1460                         *create_cow_out = 1;
1461                 if(!openflags->w ||
1462                    ((fd != -EROFS) && (fd != -EACCES))) return(fd);
1463                 openflags->w = 0;
1464                 fd = os_open_file(file, *openflags, mode);
1465                 if(fd < 0)
1466                         return(fd);
1467         }
1468
1469         err = os_lock_file(fd, openflags->w);
1470         if(err < 0){
1471                 printk("Failed to lock '%s', err = %d\n", file, -err);
1472                 goto out_close;
1473         }
1474
1475         if(backing_file_out == NULL) return(fd);
1476
1477         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
1478                               &size, &sectorsize, &align, bitmap_offset_out);
1479         if(err && (*backing_file_out != NULL)){
1480                 printk("Failed to read COW header from COW file \"%s\", "
1481                        "errno = %d\n", file, -err);
1482                 goto out_close;
1483         }
1484         if(err) return(fd);
1485
1486         if(backing_file_out == NULL) return(fd);
1487
1488         same = same_backing_files(*backing_file_out, backing_file, file);
1489
1490         if(!same && !backing_file_mismatch(*backing_file_out, size, mtime)){
1491                 printk("Switching backing file to '%s'\n", *backing_file_out);
1492                 err = write_cow_header(file, fd, *backing_file_out,
1493                                        sectorsize, align, &size);
1494                 if(err){
1495                         printk("Switch failed, errno = %d\n", -err);
1496                         return(err);
1497                 }
1498         }
1499         else {
1500                 *backing_file_out = backing_file;
1501                 err = backing_file_mismatch(*backing_file_out, size, mtime);
1502                 if(err) goto out_close;
1503         }
1504
1505         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
1506                   bitmap_len_out, data_offset_out);
1507
1508         return(fd);
1509  out_close:
1510         os_close_file(fd);
1511         return(err);
1512 }
1513
1514 int create_cow_file(char *cow_file, char *backing_file, struct openflags flags,
1515                     int sectorsize, int alignment, int *bitmap_offset_out,
1516                     unsigned long *bitmap_len_out, int *data_offset_out)
1517 {
1518         int err, fd;
1519
1520         flags.c = 1;
1521         fd = open_ubd_file(cow_file, &flags, NULL, NULL, NULL, NULL, NULL);
1522         if(fd < 0){
1523                 err = fd;
1524                 printk("Open of COW file '%s' failed, errno = %d\n", cow_file,
1525                        -err);
1526                 goto out;
1527         }
1528
1529         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
1530                             bitmap_offset_out, bitmap_len_out,
1531                             data_offset_out);
1532         if(!err)
1533                 return(fd);
1534         os_close_file(fd);
1535  out:
1536         return(err);
1537 }
1538
1539 static int update_bitmap(struct io_thread_req *req)
1540 {
1541         int n;
1542
1543         if(req->cow_offset == -1)
1544                 return(0);
1545
1546         n = os_seek_file(req->fds[1], req->cow_offset);
1547         if(n < 0){
1548                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1549                 return(1);
1550         }
1551
1552         n = os_write_file(req->fds[1], &req->bitmap_words,
1553                           sizeof(req->bitmap_words));
1554         if(n != sizeof(req->bitmap_words)){
1555                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1556                        req->fds[1]);
1557                 return(1);
1558         }
1559
1560         return(0);
1561 }
1562
1563 void do_io(struct io_thread_req *req)
1564 {
1565         char *buf;
1566         unsigned long len;
1567         int n, nsectors, start, end, bit;
1568         int err;
1569         __u64 off;
1570
1571         if(req->op == UBD_MMAP){
1572                 /* Touch the page to force the host to do any necessary IO to
1573                  * get it into memory
1574                  */
1575                 n = *((volatile int *) req->buffer);
1576                 req->error = update_bitmap(req);
1577                 return;
1578         }
1579
1580         nsectors = req->length / req->sectorsize;
1581         start = 0;
1582         do {
1583                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1584                 end = start;
1585                 while((end < nsectors) &&
1586                       (ubd_test_bit(end, (unsigned char *)
1587                                     &req->sector_mask) == bit))
1588                         end++;
1589
1590                 off = req->offset + req->offsets[bit] +
1591                         start * req->sectorsize;
1592                 len = (end - start) * req->sectorsize;
1593                 buf = &req->buffer[start * req->sectorsize];
1594
1595                 err = os_seek_file(req->fds[bit], off);
1596                 if(err < 0){
1597                         printk("do_io - lseek failed : err = %d\n", -err);
1598                         req->error = 1;
1599                         return;
1600                 }
1601                 if(req->op == UBD_READ){
1602                         n = 0;
1603                         do {
1604                                 buf = &buf[n];
1605                                 len -= n;
1606                                 n = os_read_file(req->fds[bit], buf, len);
1607                                 if (n < 0) {
1608                                         printk("do_io - read failed, err = %d "
1609                                                "fd = %d\n", -n, req->fds[bit]);
1610                                         req->error = 1;
1611                                         return;
1612                                 }
1613                         } while((n < len) && (n != 0));
1614                         if (n < len) memset(&buf[n], 0, len - n);
1615                 } else {
1616                         n = os_write_file(req->fds[bit], buf, len);
1617                         if(n != len){
1618                                 printk("do_io - write failed err = %d "
1619                                        "fd = %d\n", -n, req->fds[bit]);
1620                                 req->error = 1;
1621                                 return;
1622                         }
1623                 }
1624
1625                 start = end;
1626         } while(start < nsectors);
1627
1628         req->error = update_bitmap(req);
1629 }
1630
1631 /* Changed in start_io_thread, which is serialized by being called only
1632  * from ubd_init, which is an initcall.
1633  */
1634 int kernel_fd = -1;
1635
1636 /* Only changed by the io thread */
1637 int io_count = 0;
1638
1639 int io_thread(void *arg)
1640 {
1641         struct io_thread_req req;
1642         int n;
1643
1644         ignore_sigwinch_sig();
1645         while(1){
1646                 n = os_read_file(kernel_fd, &req, sizeof(req));
1647                 if(n != sizeof(req)){
1648                         if(n < 0)
1649                                 printk("io_thread - read failed, fd = %d, "
1650                                        "err = %d\n", kernel_fd, -n);
1651                         else {
1652                                 printk("io_thread - short read, fd = %d, "
1653                                        "length = %d\n", kernel_fd, n);
1654                         }
1655                         continue;
1656                 }
1657                 io_count++;
1658                 do_io(&req);
1659                 n = os_write_file(kernel_fd, &req, sizeof(req));
1660                 if(n != sizeof(req))
1661                         printk("io_thread - write failed, fd = %d, err = %d\n",
1662                                kernel_fd, -n);
1663         }
1664 }
1665
1666 /*
1667  * Overrides for Emacs so that we follow Linus's tabbing style.
1668  * Emacs will notice this stuff at the end of the file and automatically
1669  * adjust the settings for this buffer only.  This must remain at the end
1670  * of the file.
1671  * ---------------------------------------------------------------------------
1672  * Local variables:
1673  * c-file-style: "linux"
1674  * End:
1675  */