Merge branch 'for-2.6.27' of git://git.marvell.com/mv643xx_eth into upstream-next
[linux-2.6] / 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/kernel.h"
24 #include "linux/module.h"
25 #include "linux/blkdev.h"
26 #include "linux/hdreg.h"
27 #include "linux/init.h"
28 #include "linux/cdrom.h"
29 #include "linux/proc_fs.h"
30 #include "linux/ctype.h"
31 #include "linux/capability.h"
32 #include "linux/mm.h"
33 #include "linux/vmalloc.h"
34 #include "linux/blkpg.h"
35 #include "linux/genhd.h"
36 #include "linux/spinlock.h"
37 #include "linux/platform_device.h"
38 #include "linux/scatterlist.h"
39 #include "asm/segment.h"
40 #include "asm/uaccess.h"
41 #include "asm/irq.h"
42 #include "asm/types.h"
43 #include "asm/tlbflush.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 "os.h"
53 #include "mem.h"
54 #include "mem_kern.h"
55 #include "cow.h"
56
57 enum ubd_req { UBD_READ, UBD_WRITE };
58
59 struct io_thread_req {
60         struct request *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 error;
72 };
73
74 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
75 {
76         __u64 n;
77         int bits, off;
78
79         bits = sizeof(data[0]) * 8;
80         n = bit / bits;
81         off = bit % bits;
82         return (data[n] & (1 << off)) != 0;
83 }
84
85 static inline void ubd_set_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         data[n] |= (1 << off);
94 }
95 /*End stuff from ubd_user.h*/
96
97 #define DRIVER_NAME "uml-blkdev"
98
99 static DEFINE_MUTEX(ubd_lock);
100
101 static int ubd_open(struct inode * inode, struct file * filp);
102 static int ubd_release(struct inode * inode, struct file * file);
103 static int ubd_ioctl(struct inode * inode, struct file * file,
104                      unsigned int cmd, unsigned long arg);
105 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
106
107 #define MAX_DEV (16)
108
109 static struct block_device_operations ubd_blops = {
110         .owner          = THIS_MODULE,
111         .open           = ubd_open,
112         .release        = ubd_release,
113         .ioctl          = ubd_ioctl,
114         .getgeo         = ubd_getgeo,
115 };
116
117 /* Protected by ubd_lock */
118 static int fake_major = MAJOR_NR;
119 static struct gendisk *ubd_gendisk[MAX_DEV];
120 static struct gendisk *fake_gendisk[MAX_DEV];
121
122 #ifdef CONFIG_BLK_DEV_UBD_SYNC
123 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
124                                          .cl = 1 })
125 #else
126 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
127                                          .cl = 1 })
128 #endif
129 static struct openflags global_openflags = OPEN_FLAGS;
130
131 struct cow {
132         /* backing file name */
133         char *file;
134         /* backing file fd */
135         int fd;
136         unsigned long *bitmap;
137         unsigned long bitmap_len;
138         int bitmap_offset;
139         int data_offset;
140 };
141
142 #define MAX_SG 64
143
144 struct ubd {
145         struct list_head restart;
146         /* name (and fd, below) of the file opened for writing, either the
147          * backing or the cow file. */
148         char *file;
149         int count;
150         int fd;
151         __u64 size;
152         struct openflags boot_openflags;
153         struct openflags openflags;
154         unsigned shared:1;
155         unsigned no_cow:1;
156         struct cow cow;
157         struct platform_device pdev;
158         struct request_queue *queue;
159         spinlock_t lock;
160         struct scatterlist sg[MAX_SG];
161         struct request *request;
162         int start_sg, end_sg;
163 };
164
165 #define DEFAULT_COW { \
166         .file =                 NULL, \
167         .fd =                   -1,     \
168         .bitmap =               NULL, \
169         .bitmap_offset =        0, \
170         .data_offset =          0, \
171 }
172
173 #define DEFAULT_UBD { \
174         .file =                 NULL, \
175         .count =                0, \
176         .fd =                   -1, \
177         .size =                 -1, \
178         .boot_openflags =       OPEN_FLAGS, \
179         .openflags =            OPEN_FLAGS, \
180         .no_cow =               0, \
181         .shared =               0, \
182         .cow =                  DEFAULT_COW, \
183         .lock =                 SPIN_LOCK_UNLOCKED,     \
184         .request =              NULL, \
185         .start_sg =             0, \
186         .end_sg =               0, \
187 }
188
189 /* Protected by ubd_lock */
190 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
191
192 /* Only changed by fake_ide_setup which is a setup */
193 static int fake_ide = 0;
194 static struct proc_dir_entry *proc_ide_root = NULL;
195 static struct proc_dir_entry *proc_ide = NULL;
196
197 static void make_proc_ide(void)
198 {
199         proc_ide_root = proc_mkdir("ide", NULL);
200         proc_ide = proc_mkdir("ide0", proc_ide_root);
201 }
202
203 static int proc_ide_read_media(char *page, char **start, off_t off, int count,
204                                int *eof, void *data)
205 {
206         int len;
207
208         strcpy(page, "disk\n");
209         len = strlen("disk\n");
210         len -= off;
211         if (len < count){
212                 *eof = 1;
213                 if (len <= 0) return 0;
214         }
215         else len = count;
216         *start = page + off;
217         return len;
218 }
219
220 static void make_ide_entries(const char *dev_name)
221 {
222         struct proc_dir_entry *dir, *ent;
223         char name[64];
224
225         if(proc_ide_root == NULL) make_proc_ide();
226
227         dir = proc_mkdir(dev_name, proc_ide);
228         if(!dir) return;
229
230         ent = create_proc_entry("media", S_IFREG|S_IRUGO, dir);
231         if(!ent) return;
232         ent->data = NULL;
233         ent->read_proc = proc_ide_read_media;
234         ent->write_proc = NULL;
235         snprintf(name, sizeof(name), "ide0/%s", dev_name);
236         proc_symlink(dev_name, proc_ide_root, name);
237 }
238
239 static int fake_ide_setup(char *str)
240 {
241         fake_ide = 1;
242         return 1;
243 }
244
245 __setup("fake_ide", fake_ide_setup);
246
247 __uml_help(fake_ide_setup,
248 "fake_ide\n"
249 "    Create ide0 entries that map onto ubd devices.\n\n"
250 );
251
252 static int parse_unit(char **ptr)
253 {
254         char *str = *ptr, *end;
255         int n = -1;
256
257         if(isdigit(*str)) {
258                 n = simple_strtoul(str, &end, 0);
259                 if(end == str)
260                         return -1;
261                 *ptr = end;
262         }
263         else if (('a' <= *str) && (*str <= 'z')) {
264                 n = *str - 'a';
265                 str++;
266                 *ptr = str;
267         }
268         return n;
269 }
270
271 /* If *index_out == -1 at exit, the passed option was a general one;
272  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
273  * should not be freed on exit.
274  */
275 static int ubd_setup_common(char *str, int *index_out, char **error_out)
276 {
277         struct ubd *ubd_dev;
278         struct openflags flags = global_openflags;
279         char *backing_file;
280         int n, err = 0, i;
281
282         if(index_out) *index_out = -1;
283         n = *str;
284         if(n == '='){
285                 char *end;
286                 int major;
287
288                 str++;
289                 if(!strcmp(str, "sync")){
290                         global_openflags = of_sync(global_openflags);
291                         goto out1;
292                 }
293
294                 err = -EINVAL;
295                 major = simple_strtoul(str, &end, 0);
296                 if((*end != '\0') || (end == str)){
297                         *error_out = "Didn't parse major number";
298                         goto out1;
299                 }
300
301                 mutex_lock(&ubd_lock);
302                 if(fake_major != MAJOR_NR){
303                         *error_out = "Can't assign a fake major twice";
304                         goto out1;
305                 }
306
307                 fake_major = major;
308
309                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
310                        major);
311                 err = 0;
312         out1:
313                 mutex_unlock(&ubd_lock);
314                 return err;
315         }
316
317         n = parse_unit(&str);
318         if(n < 0){
319                 *error_out = "Couldn't parse device number";
320                 return -EINVAL;
321         }
322         if(n >= MAX_DEV){
323                 *error_out = "Device number out of range";
324                 return 1;
325         }
326
327         err = -EBUSY;
328         mutex_lock(&ubd_lock);
329
330         ubd_dev = &ubd_devs[n];
331         if(ubd_dev->file != NULL){
332                 *error_out = "Device is already configured";
333                 goto out;
334         }
335
336         if (index_out)
337                 *index_out = n;
338
339         err = -EINVAL;
340         for (i = 0; i < sizeof("rscd="); i++) {
341                 switch (*str) {
342                 case 'r':
343                         flags.w = 0;
344                         break;
345                 case 's':
346                         flags.s = 1;
347                         break;
348                 case 'd':
349                         ubd_dev->no_cow = 1;
350                         break;
351                 case 'c':
352                         ubd_dev->shared = 1;
353                         break;
354                 case '=':
355                         str++;
356                         goto break_loop;
357                 default:
358                         *error_out = "Expected '=' or flag letter "
359                                 "(r, s, c, or d)";
360                         goto out;
361                 }
362                 str++;
363         }
364
365         if (*str == '=')
366                 *error_out = "Too many flags specified";
367         else
368                 *error_out = "Missing '='";
369         goto out;
370
371 break_loop:
372         backing_file = strchr(str, ',');
373
374         if (backing_file == NULL)
375                 backing_file = strchr(str, ':');
376
377         if(backing_file != NULL){
378                 if(ubd_dev->no_cow){
379                         *error_out = "Can't specify both 'd' and a cow file";
380                         goto out;
381                 }
382                 else {
383                         *backing_file = '\0';
384                         backing_file++;
385                 }
386         }
387         err = 0;
388         ubd_dev->file = str;
389         ubd_dev->cow.file = backing_file;
390         ubd_dev->boot_openflags = flags;
391 out:
392         mutex_unlock(&ubd_lock);
393         return err;
394 }
395
396 static int ubd_setup(char *str)
397 {
398         char *error;
399         int err;
400
401         err = ubd_setup_common(str, NULL, &error);
402         if(err)
403                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
404                        "%s\n", str, error);
405         return 1;
406 }
407
408 __setup("ubd", ubd_setup);
409 __uml_help(ubd_setup,
410 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
411 "    This is used to associate a device with a file in the underlying\n"
412 "    filesystem. When specifying two filenames, the first one is the\n"
413 "    COW name and the second is the backing file name. As separator you can\n"
414 "    use either a ':' or a ',': the first one allows writing things like;\n"
415 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
416 "    while with a ',' the shell would not expand the 2nd '~'.\n"
417 "    When using only one filename, UML will detect whether to treat it like\n"
418 "    a COW file or a backing file. To override this detection, add the 'd'\n"
419 "    flag:\n"
420 "       ubd0d=BackingFile\n"
421 "    Usually, there is a filesystem in the file, but \n"
422 "    that's not required. Swap devices containing swap files can be\n"
423 "    specified like this. Also, a file which doesn't contain a\n"
424 "    filesystem can have its contents read in the virtual \n"
425 "    machine by running 'dd' on the device. <n> must be in the range\n"
426 "    0 to 7. Appending an 'r' to the number will cause that device\n"
427 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
428 "    an 's' will cause data to be written to disk on the host immediately.\n"
429 "    'c' will cause the device to be treated as being shared between multiple\n"
430 "    UMLs and file locking will be turned off - this is appropriate for a\n"
431 "    cluster filesystem and inappropriate at almost all other times.\n\n"
432 );
433
434 static int udb_setup(char *str)
435 {
436         printk("udb%s specified on command line is almost certainly a ubd -> "
437                "udb TYPO\n", str);
438         return 1;
439 }
440
441 __setup("udb", udb_setup);
442 __uml_help(udb_setup,
443 "udb\n"
444 "    This option is here solely to catch ubd -> udb typos, which can be\n"
445 "    to impossible to catch visually unless you specifically look for\n"
446 "    them.  The only result of any option starting with 'udb' is an error\n"
447 "    in the boot output.\n\n"
448 );
449
450 static void do_ubd_request(struct request_queue * q);
451
452 /* Only changed by ubd_init, which is an initcall. */
453 static int thread_fd = -1;
454
455 static void ubd_end_request(struct request *req, int bytes, int error)
456 {
457         blk_end_request(req, error, bytes);
458 }
459
460 /* Callable only from interrupt context - otherwise you need to do
461  * spin_lock_irq()/spin_lock_irqsave() */
462 static inline void ubd_finish(struct request *req, int bytes)
463 {
464         if(bytes < 0){
465                 ubd_end_request(req, 0, -EIO);
466                 return;
467         }
468         ubd_end_request(req, bytes, 0);
469 }
470
471 static LIST_HEAD(restart);
472
473 /* XXX - move this inside ubd_intr. */
474 /* Called without dev->lock held, and only in interrupt context. */
475 static void ubd_handler(void)
476 {
477         struct io_thread_req *req;
478         struct request *rq;
479         struct ubd *ubd;
480         struct list_head *list, *next_ele;
481         unsigned long flags;
482         int n;
483
484         while(1){
485                 n = os_read_file(thread_fd, &req,
486                                  sizeof(struct io_thread_req *));
487                 if(n != sizeof(req)){
488                         if(n == -EAGAIN)
489                                 break;
490                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
491                                "err = %d\n", -n);
492                         return;
493                 }
494
495                 rq = req->req;
496                 rq->nr_sectors -= req->length >> 9;
497                 if(rq->nr_sectors == 0)
498                         ubd_finish(rq, rq->hard_nr_sectors << 9);
499                 kfree(req);
500         }
501         reactivate_fd(thread_fd, UBD_IRQ);
502
503         list_for_each_safe(list, next_ele, &restart){
504                 ubd = container_of(list, struct ubd, restart);
505                 list_del_init(&ubd->restart);
506                 spin_lock_irqsave(&ubd->lock, flags);
507                 do_ubd_request(ubd->queue);
508                 spin_unlock_irqrestore(&ubd->lock, flags);
509         }
510 }
511
512 static irqreturn_t ubd_intr(int irq, void *dev)
513 {
514         ubd_handler();
515         return IRQ_HANDLED;
516 }
517
518 /* Only changed by ubd_init, which is an initcall. */
519 static int io_pid = -1;
520
521 static void kill_io_thread(void)
522 {
523         if(io_pid != -1)
524                 os_kill_process(io_pid, 1);
525 }
526
527 __uml_exitcall(kill_io_thread);
528
529 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
530 {
531         char *file;
532
533         file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;
534         return os_file_size(file, size_out);
535 }
536
537 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
538 {
539         int err;
540
541         err = os_seek_file(fd, offset);
542         if (err < 0)
543                 return err;
544
545         err = os_read_file(fd, buf, len);
546         if (err < 0)
547                 return err;
548
549         return 0;
550 }
551
552 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
553 {
554         unsigned long modtime;
555         unsigned long long actual;
556         int err;
557
558         err = os_file_modtime(file, &modtime);
559         if (err < 0) {
560                 printk(KERN_ERR "Failed to get modification time of backing "
561                        "file \"%s\", err = %d\n", file, -err);
562                 return err;
563         }
564
565         err = os_file_size(file, &actual);
566         if (err < 0) {
567                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
568                        "err = %d\n", file, -err);
569                 return err;
570         }
571
572         if (actual != size) {
573                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
574                  * the typecast.*/
575                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
576                        "vs backing file\n", (unsigned long long) size, actual);
577                 return -EINVAL;
578         }
579         if (modtime != mtime) {
580                 printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
581                        "backing file\n", mtime, modtime);
582                 return -EINVAL;
583         }
584         return 0;
585 }
586
587 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
588 {
589         struct uml_stat buf1, buf2;
590         int err;
591
592         if (from_cmdline == NULL)
593                 return 0;
594         if (!strcmp(from_cmdline, from_cow))
595                 return 0;
596
597         err = os_stat_file(from_cmdline, &buf1);
598         if (err < 0) {
599                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
600                        -err);
601                 return 0;
602         }
603         err = os_stat_file(from_cow, &buf2);
604         if (err < 0) {
605                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
606                        -err);
607                 return 1;
608         }
609         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
610                 return 0;
611
612         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
613                "\"%s\" specified in COW header of \"%s\"\n",
614                from_cmdline, from_cow, cow);
615         return 1;
616 }
617
618 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
619                   char **backing_file_out, int *bitmap_offset_out,
620                   unsigned long *bitmap_len_out, int *data_offset_out,
621                   int *create_cow_out)
622 {
623         time_t mtime;
624         unsigned long long size;
625         __u32 version, align;
626         char *backing_file;
627         int fd, err, sectorsize, asked_switch, mode = 0644;
628
629         fd = os_open_file(file, *openflags, mode);
630         if (fd < 0) {
631                 if ((fd == -ENOENT) && (create_cow_out != NULL))
632                         *create_cow_out = 1;
633                 if (!openflags->w ||
634                     ((fd != -EROFS) && (fd != -EACCES)))
635                         return fd;
636                 openflags->w = 0;
637                 fd = os_open_file(file, *openflags, mode);
638                 if (fd < 0)
639                         return fd;
640         }
641
642         if (shared)
643                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
644         else {
645                 err = os_lock_file(fd, openflags->w);
646                 if (err < 0) {
647                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
648                                file, -err);
649                         goto out_close;
650                 }
651         }
652
653         /* Successful return case! */
654         if (backing_file_out == NULL)
655                 return fd;
656
657         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
658                               &size, &sectorsize, &align, bitmap_offset_out);
659         if (err && (*backing_file_out != NULL)) {
660                 printk(KERN_ERR "Failed to read COW header from COW file "
661                        "\"%s\", errno = %d\n", file, -err);
662                 goto out_close;
663         }
664         if (err)
665                 return fd;
666
667         asked_switch = path_requires_switch(*backing_file_out, backing_file,
668                                             file);
669
670         /* Allow switching only if no mismatch. */
671         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
672                                                    mtime)) {
673                 printk(KERN_ERR "Switching backing file to '%s'\n",
674                        *backing_file_out);
675                 err = write_cow_header(file, fd, *backing_file_out,
676                                        sectorsize, align, &size);
677                 if (err) {
678                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
679                         goto out_close;
680                 }
681         } else {
682                 *backing_file_out = backing_file;
683                 err = backing_file_mismatch(*backing_file_out, size, mtime);
684                 if (err)
685                         goto out_close;
686         }
687
688         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
689                   bitmap_len_out, data_offset_out);
690
691         return fd;
692  out_close:
693         os_close_file(fd);
694         return err;
695 }
696
697 static int create_cow_file(char *cow_file, char *backing_file,
698                     struct openflags flags,
699                     int sectorsize, int alignment, int *bitmap_offset_out,
700                     unsigned long *bitmap_len_out, int *data_offset_out)
701 {
702         int err, fd;
703
704         flags.c = 1;
705         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
706         if (fd < 0) {
707                 err = fd;
708                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
709                        cow_file, -err);
710                 goto out;
711         }
712
713         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
714                             bitmap_offset_out, bitmap_len_out,
715                             data_offset_out);
716         if (!err)
717                 return fd;
718         os_close_file(fd);
719  out:
720         return err;
721 }
722
723 static void ubd_close_dev(struct ubd *ubd_dev)
724 {
725         os_close_file(ubd_dev->fd);
726         if(ubd_dev->cow.file == NULL)
727                 return;
728
729         os_close_file(ubd_dev->cow.fd);
730         vfree(ubd_dev->cow.bitmap);
731         ubd_dev->cow.bitmap = NULL;
732 }
733
734 static int ubd_open_dev(struct ubd *ubd_dev)
735 {
736         struct openflags flags;
737         char **back_ptr;
738         int err, create_cow, *create_ptr;
739         int fd;
740
741         ubd_dev->openflags = ubd_dev->boot_openflags;
742         create_cow = 0;
743         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
744         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
745
746         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
747                                 back_ptr, &ubd_dev->cow.bitmap_offset,
748                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
749                                 create_ptr);
750
751         if((fd == -ENOENT) && create_cow){
752                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
753                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
754                                           &ubd_dev->cow.bitmap_offset,
755                                           &ubd_dev->cow.bitmap_len,
756                                           &ubd_dev->cow.data_offset);
757                 if(fd >= 0){
758                         printk(KERN_INFO "Creating \"%s\" as COW file for "
759                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
760                 }
761         }
762
763         if(fd < 0){
764                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
765                        -fd);
766                 return fd;
767         }
768         ubd_dev->fd = fd;
769
770         if(ubd_dev->cow.file != NULL){
771                 blk_queue_max_sectors(ubd_dev->queue, 8 * sizeof(long));
772
773                 err = -ENOMEM;
774                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
775                 if(ubd_dev->cow.bitmap == NULL){
776                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
777                         goto error;
778                 }
779                 flush_tlb_kernel_vm();
780
781                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
782                                       ubd_dev->cow.bitmap_offset,
783                                       ubd_dev->cow.bitmap_len);
784                 if(err < 0)
785                         goto error;
786
787                 flags = ubd_dev->openflags;
788                 flags.w = 0;
789                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
790                                     NULL, NULL, NULL, NULL);
791                 if(err < 0) goto error;
792                 ubd_dev->cow.fd = err;
793         }
794         return 0;
795  error:
796         os_close_file(ubd_dev->fd);
797         return err;
798 }
799
800 static void ubd_device_release(struct device *dev)
801 {
802         struct ubd *ubd_dev = dev->driver_data;
803
804         blk_cleanup_queue(ubd_dev->queue);
805         *ubd_dev = ((struct ubd) DEFAULT_UBD);
806 }
807
808 static int ubd_disk_register(int major, u64 size, int unit,
809                              struct gendisk **disk_out)
810 {
811         struct gendisk *disk;
812
813         disk = alloc_disk(1 << UBD_SHIFT);
814         if(disk == NULL)
815                 return -ENOMEM;
816
817         disk->major = major;
818         disk->first_minor = unit << UBD_SHIFT;
819         disk->fops = &ubd_blops;
820         set_capacity(disk, size / 512);
821         if(major == MAJOR_NR)
822                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
823         else
824                 sprintf(disk->disk_name, "ubd_fake%d", unit);
825
826         /* sysfs register (not for ide fake devices) */
827         if (major == MAJOR_NR) {
828                 ubd_devs[unit].pdev.id   = unit;
829                 ubd_devs[unit].pdev.name = DRIVER_NAME;
830                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
831                 ubd_devs[unit].pdev.dev.driver_data = &ubd_devs[unit];
832                 platform_device_register(&ubd_devs[unit].pdev);
833                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
834         }
835
836         disk->private_data = &ubd_devs[unit];
837         disk->queue = ubd_devs[unit].queue;
838         add_disk(disk);
839
840         *disk_out = disk;
841         return 0;
842 }
843
844 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
845
846 static int ubd_add(int n, char **error_out)
847 {
848         struct ubd *ubd_dev = &ubd_devs[n];
849         int err = 0;
850
851         if(ubd_dev->file == NULL)
852                 goto out;
853
854         err = ubd_file_size(ubd_dev, &ubd_dev->size);
855         if(err < 0){
856                 *error_out = "Couldn't determine size of device's file";
857                 goto out;
858         }
859
860         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
861
862         INIT_LIST_HEAD(&ubd_dev->restart);
863         sg_init_table(ubd_dev->sg, MAX_SG);
864
865         err = -ENOMEM;
866         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
867         if (ubd_dev->queue == NULL) {
868                 *error_out = "Failed to initialize device queue";
869                 goto out;
870         }
871         ubd_dev->queue->queuedata = ubd_dev;
872
873         blk_queue_max_hw_segments(ubd_dev->queue, MAX_SG);
874         err = ubd_disk_register(MAJOR_NR, ubd_dev->size, n, &ubd_gendisk[n]);
875         if(err){
876                 *error_out = "Failed to register device";
877                 goto out_cleanup;
878         }
879
880         if(fake_major != MAJOR_NR)
881                 ubd_disk_register(fake_major, ubd_dev->size, n,
882                                   &fake_gendisk[n]);
883
884         /*
885          * Perhaps this should also be under the "if (fake_major)" above
886          * using the fake_disk->disk_name
887          */
888         if (fake_ide)
889                 make_ide_entries(ubd_gendisk[n]->disk_name);
890
891         err = 0;
892 out:
893         return err;
894
895 out_cleanup:
896         blk_cleanup_queue(ubd_dev->queue);
897         goto out;
898 }
899
900 static int ubd_config(char *str, char **error_out)
901 {
902         int n, ret;
903
904         /* This string is possibly broken up and stored, so it's only
905          * freed if ubd_setup_common fails, or if only general options
906          * were set.
907          */
908         str = kstrdup(str, GFP_KERNEL);
909         if (str == NULL) {
910                 *error_out = "Failed to allocate memory";
911                 return -ENOMEM;
912         }
913
914         ret = ubd_setup_common(str, &n, error_out);
915         if (ret)
916                 goto err_free;
917
918         if (n == -1) {
919                 ret = 0;
920                 goto err_free;
921         }
922
923         mutex_lock(&ubd_lock);
924         ret = ubd_add(n, error_out);
925         if (ret)
926                 ubd_devs[n].file = NULL;
927         mutex_unlock(&ubd_lock);
928
929 out:
930         return ret;
931
932 err_free:
933         kfree(str);
934         goto out;
935 }
936
937 static int ubd_get_config(char *name, char *str, int size, char **error_out)
938 {
939         struct ubd *ubd_dev;
940         int n, len = 0;
941
942         n = parse_unit(&name);
943         if((n >= MAX_DEV) || (n < 0)){
944                 *error_out = "ubd_get_config : device number out of range";
945                 return -1;
946         }
947
948         ubd_dev = &ubd_devs[n];
949         mutex_lock(&ubd_lock);
950
951         if(ubd_dev->file == NULL){
952                 CONFIG_CHUNK(str, size, len, "", 1);
953                 goto out;
954         }
955
956         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
957
958         if(ubd_dev->cow.file != NULL){
959                 CONFIG_CHUNK(str, size, len, ",", 0);
960                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
961         }
962         else CONFIG_CHUNK(str, size, len, "", 1);
963
964  out:
965         mutex_unlock(&ubd_lock);
966         return len;
967 }
968
969 static int ubd_id(char **str, int *start_out, int *end_out)
970 {
971         int n;
972
973         n = parse_unit(str);
974         *start_out = 0;
975         *end_out = MAX_DEV - 1;
976         return n;
977 }
978
979 static int ubd_remove(int n, char **error_out)
980 {
981         struct gendisk *disk = ubd_gendisk[n];
982         struct ubd *ubd_dev;
983         int err = -ENODEV;
984
985         mutex_lock(&ubd_lock);
986
987         ubd_dev = &ubd_devs[n];
988
989         if(ubd_dev->file == NULL)
990                 goto out;
991
992         /* you cannot remove a open disk */
993         err = -EBUSY;
994         if(ubd_dev->count > 0)
995                 goto out;
996
997         ubd_gendisk[n] = NULL;
998         if(disk != NULL){
999                 del_gendisk(disk);
1000                 put_disk(disk);
1001         }
1002
1003         if(fake_gendisk[n] != NULL){
1004                 del_gendisk(fake_gendisk[n]);
1005                 put_disk(fake_gendisk[n]);
1006                 fake_gendisk[n] = NULL;
1007         }
1008
1009         err = 0;
1010         platform_device_unregister(&ubd_dev->pdev);
1011 out:
1012         mutex_unlock(&ubd_lock);
1013         return err;
1014 }
1015
1016 /* All these are called by mconsole in process context and without
1017  * ubd-specific locks.  The structure itself is const except for .list.
1018  */
1019 static struct mc_device ubd_mc = {
1020         .list           = LIST_HEAD_INIT(ubd_mc.list),
1021         .name           = "ubd",
1022         .config         = ubd_config,
1023         .get_config     = ubd_get_config,
1024         .id             = ubd_id,
1025         .remove         = ubd_remove,
1026 };
1027
1028 static int __init ubd_mc_init(void)
1029 {
1030         mconsole_register_dev(&ubd_mc);
1031         return 0;
1032 }
1033
1034 __initcall(ubd_mc_init);
1035
1036 static int __init ubd0_init(void)
1037 {
1038         struct ubd *ubd_dev = &ubd_devs[0];
1039
1040         mutex_lock(&ubd_lock);
1041         if(ubd_dev->file == NULL)
1042                 ubd_dev->file = "root_fs";
1043         mutex_unlock(&ubd_lock);
1044
1045         return 0;
1046 }
1047
1048 __initcall(ubd0_init);
1049
1050 /* Used in ubd_init, which is an initcall */
1051 static struct platform_driver ubd_driver = {
1052         .driver = {
1053                 .name  = DRIVER_NAME,
1054         },
1055 };
1056
1057 static int __init ubd_init(void)
1058 {
1059         char *error;
1060         int i, err;
1061
1062         if (register_blkdev(MAJOR_NR, "ubd"))
1063                 return -1;
1064
1065         if (fake_major != MAJOR_NR) {
1066                 char name[sizeof("ubd_nnn\0")];
1067
1068                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1069                 if (register_blkdev(fake_major, "ubd"))
1070                         return -1;
1071         }
1072         platform_driver_register(&ubd_driver);
1073         mutex_lock(&ubd_lock);
1074         for (i = 0; i < MAX_DEV; i++){
1075                 err = ubd_add(i, &error);
1076                 if(err)
1077                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1078                                "%s\n", i, error);
1079         }
1080         mutex_unlock(&ubd_lock);
1081         return 0;
1082 }
1083
1084 late_initcall(ubd_init);
1085
1086 static int __init ubd_driver_init(void){
1087         unsigned long stack;
1088         int err;
1089
1090         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1091         if(global_openflags.s){
1092                 printk(KERN_INFO "ubd: Synchronous mode\n");
1093                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1094                  * enough. So use anyway the io thread. */
1095         }
1096         stack = alloc_stack(0, 0);
1097         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1098                                  &thread_fd);
1099         if(io_pid < 0){
1100                 printk(KERN_ERR
1101                        "ubd : Failed to start I/O thread (errno = %d) - "
1102                        "falling back to synchronous I/O\n", -io_pid);
1103                 io_pid = -1;
1104                 return 0;
1105         }
1106         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1107                              IRQF_DISABLED, "ubd", ubd_devs);
1108         if(err != 0)
1109                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1110         return 0;
1111 }
1112
1113 device_initcall(ubd_driver_init);
1114
1115 static int ubd_open(struct inode *inode, struct file *filp)
1116 {
1117         struct gendisk *disk = inode->i_bdev->bd_disk;
1118         struct ubd *ubd_dev = disk->private_data;
1119         int err = 0;
1120
1121         if(ubd_dev->count == 0){
1122                 err = ubd_open_dev(ubd_dev);
1123                 if(err){
1124                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1125                                disk->disk_name, ubd_dev->file, -err);
1126                         goto out;
1127                 }
1128         }
1129         ubd_dev->count++;
1130         set_disk_ro(disk, !ubd_dev->openflags.w);
1131
1132         /* This should no more be needed. And it didn't work anyway to exclude
1133          * read-write remounting of filesystems.*/
1134         /*if((filp->f_mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1135                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1136                 err = -EROFS;
1137         }*/
1138  out:
1139         return err;
1140 }
1141
1142 static int ubd_release(struct inode * inode, struct file * file)
1143 {
1144         struct gendisk *disk = inode->i_bdev->bd_disk;
1145         struct ubd *ubd_dev = disk->private_data;
1146
1147         if(--ubd_dev->count == 0)
1148                 ubd_close_dev(ubd_dev);
1149         return 0;
1150 }
1151
1152 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1153                           __u64 *cow_offset, unsigned long *bitmap,
1154                           __u64 bitmap_offset, unsigned long *bitmap_words,
1155                           __u64 bitmap_len)
1156 {
1157         __u64 sector = io_offset >> 9;
1158         int i, update_bitmap = 0;
1159
1160         for(i = 0; i < length >> 9; i++){
1161                 if(cow_mask != NULL)
1162                         ubd_set_bit(i, (unsigned char *) cow_mask);
1163                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1164                         continue;
1165
1166                 update_bitmap = 1;
1167                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1168         }
1169
1170         if(!update_bitmap)
1171                 return;
1172
1173         *cow_offset = sector / (sizeof(unsigned long) * 8);
1174
1175         /* This takes care of the case where we're exactly at the end of the
1176          * device, and *cow_offset + 1 is off the end.  So, just back it up
1177          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1178          * for the original diagnosis.
1179          */
1180         if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1181                                          sizeof(unsigned long)) - 1))
1182                 (*cow_offset)--;
1183
1184         bitmap_words[0] = bitmap[*cow_offset];
1185         bitmap_words[1] = bitmap[*cow_offset + 1];
1186
1187         *cow_offset *= sizeof(unsigned long);
1188         *cow_offset += bitmap_offset;
1189 }
1190
1191 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1192                        __u64 bitmap_offset, __u64 bitmap_len)
1193 {
1194         __u64 sector = req->offset >> 9;
1195         int i;
1196
1197         if(req->length > (sizeof(req->sector_mask) * 8) << 9)
1198                 panic("Operation too long");
1199
1200         if(req->op == UBD_READ) {
1201                 for(i = 0; i < req->length >> 9; i++){
1202                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1203                                 ubd_set_bit(i, (unsigned char *)
1204                                             &req->sector_mask);
1205                 }
1206         }
1207         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1208                            &req->cow_offset, bitmap, bitmap_offset,
1209                            req->bitmap_words, bitmap_len);
1210 }
1211
1212 /* Called with dev->lock held */
1213 static void prepare_request(struct request *req, struct io_thread_req *io_req,
1214                             unsigned long long offset, int page_offset,
1215                             int len, struct page *page)
1216 {
1217         struct gendisk *disk = req->rq_disk;
1218         struct ubd *ubd_dev = disk->private_data;
1219
1220         io_req->req = req;
1221         io_req->fds[0] = (ubd_dev->cow.file != NULL) ? ubd_dev->cow.fd :
1222                 ubd_dev->fd;
1223         io_req->fds[1] = ubd_dev->fd;
1224         io_req->cow_offset = -1;
1225         io_req->offset = offset;
1226         io_req->length = len;
1227         io_req->error = 0;
1228         io_req->sector_mask = 0;
1229
1230         io_req->op = (rq_data_dir(req) == READ) ? UBD_READ : UBD_WRITE;
1231         io_req->offsets[0] = 0;
1232         io_req->offsets[1] = ubd_dev->cow.data_offset;
1233         io_req->buffer = page_address(page) + page_offset;
1234         io_req->sectorsize = 1 << 9;
1235
1236         if(ubd_dev->cow.file != NULL)
1237                 cowify_req(io_req, ubd_dev->cow.bitmap,
1238                            ubd_dev->cow.bitmap_offset, ubd_dev->cow.bitmap_len);
1239
1240 }
1241
1242 /* Called with dev->lock held */
1243 static void do_ubd_request(struct request_queue *q)
1244 {
1245         struct io_thread_req *io_req;
1246         struct request *req;
1247         int n, last_sectors;
1248
1249         while(1){
1250                 struct ubd *dev = q->queuedata;
1251                 if(dev->end_sg == 0){
1252                         struct request *req = elv_next_request(q);
1253                         if(req == NULL)
1254                                 return;
1255
1256                         dev->request = req;
1257                         blkdev_dequeue_request(req);
1258                         dev->start_sg = 0;
1259                         dev->end_sg = blk_rq_map_sg(q, req, dev->sg);
1260                 }
1261
1262                 req = dev->request;
1263                 last_sectors = 0;
1264                 while(dev->start_sg < dev->end_sg){
1265                         struct scatterlist *sg = &dev->sg[dev->start_sg];
1266
1267                         req->sector += last_sectors;
1268                         io_req = kmalloc(sizeof(struct io_thread_req),
1269                                          GFP_ATOMIC);
1270                         if(io_req == NULL){
1271                                 if(list_empty(&dev->restart))
1272                                         list_add(&dev->restart, &restart);
1273                                 return;
1274                         }
1275                         prepare_request(req, io_req,
1276                                         (unsigned long long) req->sector << 9,
1277                                         sg->offset, sg->length, sg_page(sg));
1278
1279                         last_sectors = sg->length >> 9;
1280                         n = os_write_file(thread_fd, &io_req,
1281                                           sizeof(struct io_thread_req *));
1282                         if(n != sizeof(struct io_thread_req *)){
1283                                 if(n != -EAGAIN)
1284                                         printk("write to io thread failed, "
1285                                                "errno = %d\n", -n);
1286                                 else if(list_empty(&dev->restart))
1287                                         list_add(&dev->restart, &restart);
1288                                 kfree(io_req);
1289                                 return;
1290                         }
1291
1292                         dev->start_sg++;
1293                 }
1294                 dev->end_sg = 0;
1295                 dev->request = NULL;
1296         }
1297 }
1298
1299 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1300 {
1301         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1302
1303         geo->heads = 128;
1304         geo->sectors = 32;
1305         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1306         return 0;
1307 }
1308
1309 static int ubd_ioctl(struct inode * inode, struct file * file,
1310                      unsigned int cmd, unsigned long arg)
1311 {
1312         struct ubd *ubd_dev = inode->i_bdev->bd_disk->private_data;
1313         struct hd_driveid ubd_id = {
1314                 .cyls           = 0,
1315                 .heads          = 128,
1316                 .sectors        = 32,
1317         };
1318
1319         switch (cmd) {
1320                 struct cdrom_volctrl volume;
1321         case HDIO_GET_IDENTITY:
1322                 ubd_id.cyls = ubd_dev->size / (128 * 32 * 512);
1323                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1324                                  sizeof(ubd_id)))
1325                         return -EFAULT;
1326                 return 0;
1327
1328         case CDROMVOLREAD:
1329                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1330                         return -EFAULT;
1331                 volume.channel0 = 255;
1332                 volume.channel1 = 255;
1333                 volume.channel2 = 255;
1334                 volume.channel3 = 255;
1335                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1336                         return -EFAULT;
1337                 return 0;
1338         }
1339         return -EINVAL;
1340 }
1341
1342 static int update_bitmap(struct io_thread_req *req)
1343 {
1344         int n;
1345
1346         if(req->cow_offset == -1)
1347                 return 0;
1348
1349         n = os_seek_file(req->fds[1], req->cow_offset);
1350         if(n < 0){
1351                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1352                 return 1;
1353         }
1354
1355         n = os_write_file(req->fds[1], &req->bitmap_words,
1356                           sizeof(req->bitmap_words));
1357         if(n != sizeof(req->bitmap_words)){
1358                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1359                        req->fds[1]);
1360                 return 1;
1361         }
1362
1363         return 0;
1364 }
1365
1366 static void do_io(struct io_thread_req *req)
1367 {
1368         char *buf;
1369         unsigned long len;
1370         int n, nsectors, start, end, bit;
1371         int err;
1372         __u64 off;
1373
1374         nsectors = req->length / req->sectorsize;
1375         start = 0;
1376         do {
1377                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1378                 end = start;
1379                 while((end < nsectors) &&
1380                       (ubd_test_bit(end, (unsigned char *)
1381                                     &req->sector_mask) == bit))
1382                         end++;
1383
1384                 off = req->offset + req->offsets[bit] +
1385                         start * req->sectorsize;
1386                 len = (end - start) * req->sectorsize;
1387                 buf = &req->buffer[start * req->sectorsize];
1388
1389                 err = os_seek_file(req->fds[bit], off);
1390                 if(err < 0){
1391                         printk("do_io - lseek failed : err = %d\n", -err);
1392                         req->error = 1;
1393                         return;
1394                 }
1395                 if(req->op == UBD_READ){
1396                         n = 0;
1397                         do {
1398                                 buf = &buf[n];
1399                                 len -= n;
1400                                 n = os_read_file(req->fds[bit], buf, len);
1401                                 if (n < 0) {
1402                                         printk("do_io - read failed, err = %d "
1403                                                "fd = %d\n", -n, req->fds[bit]);
1404                                         req->error = 1;
1405                                         return;
1406                                 }
1407                         } while((n < len) && (n != 0));
1408                         if (n < len) memset(&buf[n], 0, len - n);
1409                 } else {
1410                         n = os_write_file(req->fds[bit], buf, len);
1411                         if(n != len){
1412                                 printk("do_io - write failed err = %d "
1413                                        "fd = %d\n", -n, req->fds[bit]);
1414                                 req->error = 1;
1415                                 return;
1416                         }
1417                 }
1418
1419                 start = end;
1420         } while(start < nsectors);
1421
1422         req->error = update_bitmap(req);
1423 }
1424
1425 /* Changed in start_io_thread, which is serialized by being called only
1426  * from ubd_init, which is an initcall.
1427  */
1428 int kernel_fd = -1;
1429
1430 /* Only changed by the io thread. XXX: currently unused. */
1431 static int io_count = 0;
1432
1433 int io_thread(void *arg)
1434 {
1435         struct io_thread_req *req;
1436         int n;
1437
1438         ignore_sigwinch_sig();
1439         while(1){
1440                 n = os_read_file(kernel_fd, &req,
1441                                  sizeof(struct io_thread_req *));
1442                 if(n != sizeof(struct io_thread_req *)){
1443                         if(n < 0)
1444                                 printk("io_thread - read failed, fd = %d, "
1445                                        "err = %d\n", kernel_fd, -n);
1446                         else {
1447                                 printk("io_thread - short read, fd = %d, "
1448                                        "length = %d\n", kernel_fd, n);
1449                         }
1450                         continue;
1451                 }
1452                 io_count++;
1453                 do_io(req);
1454                 n = os_write_file(kernel_fd, &req,
1455                                   sizeof(struct io_thread_req *));
1456                 if(n != sizeof(struct io_thread_req *))
1457                         printk("io_thread - write failed, fd = %d, err = %d\n",
1458                                kernel_fd, -n);
1459         }
1460
1461         return 0;
1462 }