41bf72073cccafd9bbd918ded89e6263d6883b93
[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 UBD_SHIFT 4
21
22 #include <linux/module.h>
23 #include <linux/init.h>
24 #include <linux/blkdev.h>
25 #include <linux/ata.h>
26 #include <linux/hdreg.h>
27 #include <linux/cdrom.h>
28 #include <linux/proc_fs.h>
29 #include <linux/seq_file.h>
30 #include <linux/ctype.h>
31 #include <linux/slab.h>
32 #include <linux/vmalloc.h>
33 #include <linux/platform_device.h>
34 #include <linux/scatterlist.h>
35 #include <asm/tlbflush.h>
36 #include <kern_util.h>
37 #include "mconsole_kern.h"
38 #include <init.h>
39 #include <irq_kern.h>
40 #include "ubd.h"
41 #include <os.h>
42 #include "cow.h"
43
44 enum ubd_req { UBD_READ, UBD_WRITE };
45
46 struct io_thread_req {
47         struct request *req;
48         enum ubd_req op;
49         int fds[2];
50         unsigned long offsets[2];
51         unsigned long long offset;
52         unsigned long length;
53         char *buffer;
54         int sectorsize;
55         unsigned long sector_mask;
56         unsigned long long cow_offset;
57         unsigned long bitmap_words[2];
58         int error;
59 };
60
61 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
62 {
63         __u64 n;
64         int bits, off;
65
66         bits = sizeof(data[0]) * 8;
67         n = bit / bits;
68         off = bit % bits;
69         return (data[n] & (1 << off)) != 0;
70 }
71
72 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
73 {
74         __u64 n;
75         int bits, off;
76
77         bits = sizeof(data[0]) * 8;
78         n = bit / bits;
79         off = bit % bits;
80         data[n] |= (1 << off);
81 }
82 /*End stuff from ubd_user.h*/
83
84 #define DRIVER_NAME "uml-blkdev"
85
86 static DEFINE_MUTEX(ubd_lock);
87 static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
88
89 static int ubd_open(struct block_device *bdev, fmode_t mode);
90 static int ubd_release(struct gendisk *disk, fmode_t mode);
91 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
92                      unsigned int cmd, unsigned long arg);
93 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
94
95 #define MAX_DEV (16)
96
97 static const struct block_device_operations ubd_blops = {
98         .owner          = THIS_MODULE,
99         .open           = ubd_open,
100         .release        = ubd_release,
101         .ioctl          = ubd_ioctl,
102         .getgeo         = ubd_getgeo,
103 };
104
105 /* Protected by ubd_lock */
106 static int fake_major = UBD_MAJOR;
107 static struct gendisk *ubd_gendisk[MAX_DEV];
108 static struct gendisk *fake_gendisk[MAX_DEV];
109
110 #ifdef CONFIG_BLK_DEV_UBD_SYNC
111 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
112                                          .cl = 1 })
113 #else
114 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
115                                          .cl = 1 })
116 #endif
117 static struct openflags global_openflags = OPEN_FLAGS;
118
119 struct cow {
120         /* backing file name */
121         char *file;
122         /* backing file fd */
123         int fd;
124         unsigned long *bitmap;
125         unsigned long bitmap_len;
126         int bitmap_offset;
127         int data_offset;
128 };
129
130 #define MAX_SG 64
131
132 struct ubd {
133         struct list_head restart;
134         /* name (and fd, below) of the file opened for writing, either the
135          * backing or the cow file. */
136         char *file;
137         int count;
138         int fd;
139         __u64 size;
140         struct openflags boot_openflags;
141         struct openflags openflags;
142         unsigned shared:1;
143         unsigned no_cow:1;
144         struct cow cow;
145         struct platform_device pdev;
146         struct request_queue *queue;
147         spinlock_t lock;
148         struct scatterlist sg[MAX_SG];
149         struct request *request;
150         int start_sg, end_sg;
151         sector_t rq_pos;
152 };
153
154 #define DEFAULT_COW { \
155         .file =                 NULL, \
156         .fd =                   -1,     \
157         .bitmap =               NULL, \
158         .bitmap_offset =        0, \
159         .data_offset =          0, \
160 }
161
162 #define DEFAULT_UBD { \
163         .file =                 NULL, \
164         .count =                0, \
165         .fd =                   -1, \
166         .size =                 -1, \
167         .boot_openflags =       OPEN_FLAGS, \
168         .openflags =            OPEN_FLAGS, \
169         .no_cow =               0, \
170         .shared =               0, \
171         .cow =                  DEFAULT_COW, \
172         .lock =                 __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
173         .request =              NULL, \
174         .start_sg =             0, \
175         .end_sg =               0, \
176         .rq_pos =               0, \
177 }
178
179 /* Protected by ubd_lock */
180 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
181
182 /* Only changed by fake_ide_setup which is a setup */
183 static int fake_ide = 0;
184 static struct proc_dir_entry *proc_ide_root = NULL;
185 static struct proc_dir_entry *proc_ide = NULL;
186
187 static void make_proc_ide(void)
188 {
189         proc_ide_root = proc_mkdir("ide", NULL);
190         proc_ide = proc_mkdir("ide0", proc_ide_root);
191 }
192
193 static int fake_ide_media_proc_show(struct seq_file *m, void *v)
194 {
195         seq_puts(m, "disk\n");
196         return 0;
197 }
198
199 static int fake_ide_media_proc_open(struct inode *inode, struct file *file)
200 {
201         return single_open(file, fake_ide_media_proc_show, NULL);
202 }
203
204 static const struct file_operations fake_ide_media_proc_fops = {
205         .owner          = THIS_MODULE,
206         .open           = fake_ide_media_proc_open,
207         .read           = seq_read,
208         .llseek         = seq_lseek,
209         .release        = single_release,
210 };
211
212 static void make_ide_entries(const char *dev_name)
213 {
214         struct proc_dir_entry *dir, *ent;
215         char name[64];
216
217         if(proc_ide_root == NULL) make_proc_ide();
218
219         dir = proc_mkdir(dev_name, proc_ide);
220         if(!dir) return;
221
222         ent = proc_create("media", S_IRUGO, dir, &fake_ide_media_proc_fops);
223         if(!ent) return;
224         snprintf(name, sizeof(name), "ide0/%s", dev_name);
225         proc_symlink(dev_name, proc_ide_root, name);
226 }
227
228 static int fake_ide_setup(char *str)
229 {
230         fake_ide = 1;
231         return 1;
232 }
233
234 __setup("fake_ide", fake_ide_setup);
235
236 __uml_help(fake_ide_setup,
237 "fake_ide\n"
238 "    Create ide0 entries that map onto ubd devices.\n\n"
239 );
240
241 static int parse_unit(char **ptr)
242 {
243         char *str = *ptr, *end;
244         int n = -1;
245
246         if(isdigit(*str)) {
247                 n = simple_strtoul(str, &end, 0);
248                 if(end == str)
249                         return -1;
250                 *ptr = end;
251         }
252         else if (('a' <= *str) && (*str <= 'z')) {
253                 n = *str - 'a';
254                 str++;
255                 *ptr = str;
256         }
257         return n;
258 }
259
260 /* If *index_out == -1 at exit, the passed option was a general one;
261  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
262  * should not be freed on exit.
263  */
264 static int ubd_setup_common(char *str, int *index_out, char **error_out)
265 {
266         struct ubd *ubd_dev;
267         struct openflags flags = global_openflags;
268         char *backing_file;
269         int n, err = 0, i;
270
271         if(index_out) *index_out = -1;
272         n = *str;
273         if(n == '='){
274                 char *end;
275                 int major;
276
277                 str++;
278                 if(!strcmp(str, "sync")){
279                         global_openflags = of_sync(global_openflags);
280                         goto out1;
281                 }
282
283                 err = -EINVAL;
284                 major = simple_strtoul(str, &end, 0);
285                 if((*end != '\0') || (end == str)){
286                         *error_out = "Didn't parse major number";
287                         goto out1;
288                 }
289
290                 mutex_lock(&ubd_lock);
291                 if (fake_major != UBD_MAJOR) {
292                         *error_out = "Can't assign a fake major twice";
293                         goto out1;
294                 }
295
296                 fake_major = major;
297
298                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
299                        major);
300                 err = 0;
301         out1:
302                 mutex_unlock(&ubd_lock);
303                 return err;
304         }
305
306         n = parse_unit(&str);
307         if(n < 0){
308                 *error_out = "Couldn't parse device number";
309                 return -EINVAL;
310         }
311         if(n >= MAX_DEV){
312                 *error_out = "Device number out of range";
313                 return 1;
314         }
315
316         err = -EBUSY;
317         mutex_lock(&ubd_lock);
318
319         ubd_dev = &ubd_devs[n];
320         if(ubd_dev->file != NULL){
321                 *error_out = "Device is already configured";
322                 goto out;
323         }
324
325         if (index_out)
326                 *index_out = n;
327
328         err = -EINVAL;
329         for (i = 0; i < sizeof("rscd="); i++) {
330                 switch (*str) {
331                 case 'r':
332                         flags.w = 0;
333                         break;
334                 case 's':
335                         flags.s = 1;
336                         break;
337                 case 'd':
338                         ubd_dev->no_cow = 1;
339                         break;
340                 case 'c':
341                         ubd_dev->shared = 1;
342                         break;
343                 case '=':
344                         str++;
345                         goto break_loop;
346                 default:
347                         *error_out = "Expected '=' or flag letter "
348                                 "(r, s, c, or d)";
349                         goto out;
350                 }
351                 str++;
352         }
353
354         if (*str == '=')
355                 *error_out = "Too many flags specified";
356         else
357                 *error_out = "Missing '='";
358         goto out;
359
360 break_loop:
361         backing_file = strchr(str, ',');
362
363         if (backing_file == NULL)
364                 backing_file = strchr(str, ':');
365
366         if(backing_file != NULL){
367                 if(ubd_dev->no_cow){
368                         *error_out = "Can't specify both 'd' and a cow file";
369                         goto out;
370                 }
371                 else {
372                         *backing_file = '\0';
373                         backing_file++;
374                 }
375         }
376         err = 0;
377         ubd_dev->file = str;
378         ubd_dev->cow.file = backing_file;
379         ubd_dev->boot_openflags = flags;
380 out:
381         mutex_unlock(&ubd_lock);
382         return err;
383 }
384
385 static int ubd_setup(char *str)
386 {
387         char *error;
388         int err;
389
390         err = ubd_setup_common(str, NULL, &error);
391         if(err)
392                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
393                        "%s\n", str, error);
394         return 1;
395 }
396
397 __setup("ubd", ubd_setup);
398 __uml_help(ubd_setup,
399 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
400 "    This is used to associate a device with a file in the underlying\n"
401 "    filesystem. When specifying two filenames, the first one is the\n"
402 "    COW name and the second is the backing file name. As separator you can\n"
403 "    use either a ':' or a ',': the first one allows writing things like;\n"
404 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
405 "    while with a ',' the shell would not expand the 2nd '~'.\n"
406 "    When using only one filename, UML will detect whether to treat it like\n"
407 "    a COW file or a backing file. To override this detection, add the 'd'\n"
408 "    flag:\n"
409 "       ubd0d=BackingFile\n"
410 "    Usually, there is a filesystem in the file, but \n"
411 "    that's not required. Swap devices containing swap files can be\n"
412 "    specified like this. Also, a file which doesn't contain a\n"
413 "    filesystem can have its contents read in the virtual \n"
414 "    machine by running 'dd' on the device. <n> must be in the range\n"
415 "    0 to 7. Appending an 'r' to the number will cause that device\n"
416 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
417 "    an 's' will cause data to be written to disk on the host immediately.\n"
418 "    'c' will cause the device to be treated as being shared between multiple\n"
419 "    UMLs and file locking will be turned off - this is appropriate for a\n"
420 "    cluster filesystem and inappropriate at almost all other times.\n\n"
421 );
422
423 static int udb_setup(char *str)
424 {
425         printk("udb%s specified on command line is almost certainly a ubd -> "
426                "udb TYPO\n", str);
427         return 1;
428 }
429
430 __setup("udb", udb_setup);
431 __uml_help(udb_setup,
432 "udb\n"
433 "    This option is here solely to catch ubd -> udb typos, which can be\n"
434 "    to impossible to catch visually unless you specifically look for\n"
435 "    them.  The only result of any option starting with 'udb' is an error\n"
436 "    in the boot output.\n\n"
437 );
438
439 static void do_ubd_request(struct request_queue * q);
440
441 /* Only changed by ubd_init, which is an initcall. */
442 static int thread_fd = -1;
443 static LIST_HEAD(restart);
444
445 /* XXX - move this inside ubd_intr. */
446 /* Called without dev->lock held, and only in interrupt context. */
447 static void ubd_handler(void)
448 {
449         struct io_thread_req *req;
450         struct ubd *ubd;
451         struct list_head *list, *next_ele;
452         unsigned long flags;
453         int n;
454
455         while(1){
456                 n = os_read_file(thread_fd, &req,
457                                  sizeof(struct io_thread_req *));
458                 if(n != sizeof(req)){
459                         if(n == -EAGAIN)
460                                 break;
461                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
462                                "err = %d\n", -n);
463                         return;
464                 }
465
466                 blk_end_request(req->req, 0, req->length);
467                 kfree(req);
468         }
469         reactivate_fd(thread_fd, UBD_IRQ);
470
471         list_for_each_safe(list, next_ele, &restart){
472                 ubd = container_of(list, struct ubd, restart);
473                 list_del_init(&ubd->restart);
474                 spin_lock_irqsave(&ubd->lock, flags);
475                 do_ubd_request(ubd->queue);
476                 spin_unlock_irqrestore(&ubd->lock, flags);
477         }
478 }
479
480 static irqreturn_t ubd_intr(int irq, void *dev)
481 {
482         ubd_handler();
483         return IRQ_HANDLED;
484 }
485
486 /* Only changed by ubd_init, which is an initcall. */
487 static int io_pid = -1;
488
489 static void kill_io_thread(void)
490 {
491         if(io_pid != -1)
492                 os_kill_process(io_pid, 1);
493 }
494
495 __uml_exitcall(kill_io_thread);
496
497 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
498 {
499         char *file;
500         int fd;
501         int err;
502
503         __u32 version;
504         __u32 align;
505         char *backing_file;
506         time_t mtime;
507         unsigned long long size;
508         int sector_size;
509         int bitmap_offset;
510
511         if (ubd_dev->file && ubd_dev->cow.file) {
512                 file = ubd_dev->cow.file;
513
514                 goto out;
515         }
516
517         fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
518         if (fd < 0)
519                 return fd;
520
521         err = read_cow_header(file_reader, &fd, &version, &backing_file, \
522                 &mtime, &size, &sector_size, &align, &bitmap_offset);
523         os_close_file(fd);
524
525         if(err == -EINVAL)
526                 file = ubd_dev->file;
527         else
528                 file = backing_file;
529
530 out:
531         return os_file_size(file, size_out);
532 }
533
534 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
535 {
536         int err;
537
538         err = os_seek_file(fd, offset);
539         if (err < 0)
540                 return err;
541
542         err = os_read_file(fd, buf, len);
543         if (err < 0)
544                 return err;
545
546         return 0;
547 }
548
549 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
550 {
551         unsigned long modtime;
552         unsigned long long actual;
553         int err;
554
555         err = os_file_modtime(file, &modtime);
556         if (err < 0) {
557                 printk(KERN_ERR "Failed to get modification time of backing "
558                        "file \"%s\", err = %d\n", file, -err);
559                 return err;
560         }
561
562         err = os_file_size(file, &actual);
563         if (err < 0) {
564                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
565                        "err = %d\n", file, -err);
566                 return err;
567         }
568
569         if (actual != size) {
570                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
571                  * the typecast.*/
572                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
573                        "vs backing file\n", (unsigned long long) size, actual);
574                 return -EINVAL;
575         }
576         if (modtime != mtime) {
577                 printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
578                        "backing file\n", mtime, modtime);
579                 return -EINVAL;
580         }
581         return 0;
582 }
583
584 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
585 {
586         struct uml_stat buf1, buf2;
587         int err;
588
589         if (from_cmdline == NULL)
590                 return 0;
591         if (!strcmp(from_cmdline, from_cow))
592                 return 0;
593
594         err = os_stat_file(from_cmdline, &buf1);
595         if (err < 0) {
596                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
597                        -err);
598                 return 0;
599         }
600         err = os_stat_file(from_cow, &buf2);
601         if (err < 0) {
602                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
603                        -err);
604                 return 1;
605         }
606         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
607                 return 0;
608
609         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
610                "\"%s\" specified in COW header of \"%s\"\n",
611                from_cmdline, from_cow, cow);
612         return 1;
613 }
614
615 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
616                   char **backing_file_out, int *bitmap_offset_out,
617                   unsigned long *bitmap_len_out, int *data_offset_out,
618                   int *create_cow_out)
619 {
620         time_t mtime;
621         unsigned long long size;
622         __u32 version, align;
623         char *backing_file;
624         int fd, err, sectorsize, asked_switch, mode = 0644;
625
626         fd = os_open_file(file, *openflags, mode);
627         if (fd < 0) {
628                 if ((fd == -ENOENT) && (create_cow_out != NULL))
629                         *create_cow_out = 1;
630                 if (!openflags->w ||
631                     ((fd != -EROFS) && (fd != -EACCES)))
632                         return fd;
633                 openflags->w = 0;
634                 fd = os_open_file(file, *openflags, mode);
635                 if (fd < 0)
636                         return fd;
637         }
638
639         if (shared)
640                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
641         else {
642                 err = os_lock_file(fd, openflags->w);
643                 if (err < 0) {
644                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
645                                file, -err);
646                         goto out_close;
647                 }
648         }
649
650         /* Successful return case! */
651         if (backing_file_out == NULL)
652                 return fd;
653
654         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
655                               &size, &sectorsize, &align, bitmap_offset_out);
656         if (err && (*backing_file_out != NULL)) {
657                 printk(KERN_ERR "Failed to read COW header from COW file "
658                        "\"%s\", errno = %d\n", file, -err);
659                 goto out_close;
660         }
661         if (err)
662                 return fd;
663
664         asked_switch = path_requires_switch(*backing_file_out, backing_file,
665                                             file);
666
667         /* Allow switching only if no mismatch. */
668         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
669                                                    mtime)) {
670                 printk(KERN_ERR "Switching backing file to '%s'\n",
671                        *backing_file_out);
672                 err = write_cow_header(file, fd, *backing_file_out,
673                                        sectorsize, align, &size);
674                 if (err) {
675                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
676                         goto out_close;
677                 }
678         } else {
679                 *backing_file_out = backing_file;
680                 err = backing_file_mismatch(*backing_file_out, size, mtime);
681                 if (err)
682                         goto out_close;
683         }
684
685         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
686                   bitmap_len_out, data_offset_out);
687
688         return fd;
689  out_close:
690         os_close_file(fd);
691         return err;
692 }
693
694 static int create_cow_file(char *cow_file, char *backing_file,
695                     struct openflags flags,
696                     int sectorsize, int alignment, int *bitmap_offset_out,
697                     unsigned long *bitmap_len_out, int *data_offset_out)
698 {
699         int err, fd;
700
701         flags.c = 1;
702         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
703         if (fd < 0) {
704                 err = fd;
705                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
706                        cow_file, -err);
707                 goto out;
708         }
709
710         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
711                             bitmap_offset_out, bitmap_len_out,
712                             data_offset_out);
713         if (!err)
714                 return fd;
715         os_close_file(fd);
716  out:
717         return err;
718 }
719
720 static void ubd_close_dev(struct ubd *ubd_dev)
721 {
722         os_close_file(ubd_dev->fd);
723         if(ubd_dev->cow.file == NULL)
724                 return;
725
726         os_close_file(ubd_dev->cow.fd);
727         vfree(ubd_dev->cow.bitmap);
728         ubd_dev->cow.bitmap = NULL;
729 }
730
731 static int ubd_open_dev(struct ubd *ubd_dev)
732 {
733         struct openflags flags;
734         char **back_ptr;
735         int err, create_cow, *create_ptr;
736         int fd;
737
738         ubd_dev->openflags = ubd_dev->boot_openflags;
739         create_cow = 0;
740         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
741         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
742
743         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
744                                 back_ptr, &ubd_dev->cow.bitmap_offset,
745                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
746                                 create_ptr);
747
748         if((fd == -ENOENT) && create_cow){
749                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
750                                           ubd_dev->openflags, 1 << 9, PAGE_SIZE,
751                                           &ubd_dev->cow.bitmap_offset,
752                                           &ubd_dev->cow.bitmap_len,
753                                           &ubd_dev->cow.data_offset);
754                 if(fd >= 0){
755                         printk(KERN_INFO "Creating \"%s\" as COW file for "
756                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
757                 }
758         }
759
760         if(fd < 0){
761                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
762                        -fd);
763                 return fd;
764         }
765         ubd_dev->fd = fd;
766
767         if(ubd_dev->cow.file != NULL){
768                 blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
769
770                 err = -ENOMEM;
771                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
772                 if(ubd_dev->cow.bitmap == NULL){
773                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
774                         goto error;
775                 }
776                 flush_tlb_kernel_vm();
777
778                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
779                                       ubd_dev->cow.bitmap_offset,
780                                       ubd_dev->cow.bitmap_len);
781                 if(err < 0)
782                         goto error;
783
784                 flags = ubd_dev->openflags;
785                 flags.w = 0;
786                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
787                                     NULL, NULL, NULL, NULL);
788                 if(err < 0) goto error;
789                 ubd_dev->cow.fd = err;
790         }
791         return 0;
792  error:
793         os_close_file(ubd_dev->fd);
794         return err;
795 }
796
797 static void ubd_device_release(struct device *dev)
798 {
799         struct ubd *ubd_dev = dev_get_drvdata(dev);
800
801         blk_cleanup_queue(ubd_dev->queue);
802         *ubd_dev = ((struct ubd) DEFAULT_UBD);
803 }
804
805 static int ubd_disk_register(int major, u64 size, int unit,
806                              struct gendisk **disk_out)
807 {
808         struct gendisk *disk;
809
810         disk = alloc_disk(1 << UBD_SHIFT);
811         if(disk == NULL)
812                 return -ENOMEM;
813
814         disk->major = major;
815         disk->first_minor = unit << UBD_SHIFT;
816         disk->fops = &ubd_blops;
817         set_capacity(disk, size / 512);
818         if (major == UBD_MAJOR)
819                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
820         else
821                 sprintf(disk->disk_name, "ubd_fake%d", unit);
822
823         /* sysfs register (not for ide fake devices) */
824         if (major == UBD_MAJOR) {
825                 ubd_devs[unit].pdev.id   = unit;
826                 ubd_devs[unit].pdev.name = DRIVER_NAME;
827                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
828                 dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
829                 platform_device_register(&ubd_devs[unit].pdev);
830                 disk->driverfs_dev = &ubd_devs[unit].pdev.dev;
831         }
832
833         disk->private_data = &ubd_devs[unit];
834         disk->queue = ubd_devs[unit].queue;
835         add_disk(disk);
836
837         *disk_out = disk;
838         return 0;
839 }
840
841 #define ROUND_BLOCK(n) ((n + ((1 << 9) - 1)) & (-1 << 9))
842
843 static int ubd_add(int n, char **error_out)
844 {
845         struct ubd *ubd_dev = &ubd_devs[n];
846         int err = 0;
847
848         if(ubd_dev->file == NULL)
849                 goto out;
850
851         err = ubd_file_size(ubd_dev, &ubd_dev->size);
852         if(err < 0){
853                 *error_out = "Couldn't determine size of device's file";
854                 goto out;
855         }
856
857         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
858
859         INIT_LIST_HEAD(&ubd_dev->restart);
860         sg_init_table(ubd_dev->sg, MAX_SG);
861
862         err = -ENOMEM;
863         ubd_dev->queue = blk_init_queue(do_ubd_request, &ubd_dev->lock);
864         if (ubd_dev->queue == NULL) {
865                 *error_out = "Failed to initialize device queue";
866                 goto out;
867         }
868         ubd_dev->queue->queuedata = ubd_dev;
869
870         blk_queue_max_segments(ubd_dev->queue, MAX_SG);
871         err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
872         if(err){
873                 *error_out = "Failed to register device";
874                 goto out_cleanup;
875         }
876
877         if (fake_major != UBD_MAJOR)
878                 ubd_disk_register(fake_major, ubd_dev->size, n,
879                                   &fake_gendisk[n]);
880
881         /*
882          * Perhaps this should also be under the "if (fake_major)" above
883          * using the fake_disk->disk_name
884          */
885         if (fake_ide)
886                 make_ide_entries(ubd_gendisk[n]->disk_name);
887
888         err = 0;
889 out:
890         return err;
891
892 out_cleanup:
893         blk_cleanup_queue(ubd_dev->queue);
894         goto out;
895 }
896
897 static int ubd_config(char *str, char **error_out)
898 {
899         int n, ret;
900
901         /* This string is possibly broken up and stored, so it's only
902          * freed if ubd_setup_common fails, or if only general options
903          * were set.
904          */
905         str = kstrdup(str, GFP_KERNEL);
906         if (str == NULL) {
907                 *error_out = "Failed to allocate memory";
908                 return -ENOMEM;
909         }
910
911         ret = ubd_setup_common(str, &n, error_out);
912         if (ret)
913                 goto err_free;
914
915         if (n == -1) {
916                 ret = 0;
917                 goto err_free;
918         }
919
920         mutex_lock(&ubd_lock);
921         ret = ubd_add(n, error_out);
922         if (ret)
923                 ubd_devs[n].file = NULL;
924         mutex_unlock(&ubd_lock);
925
926 out:
927         return ret;
928
929 err_free:
930         kfree(str);
931         goto out;
932 }
933
934 static int ubd_get_config(char *name, char *str, int size, char **error_out)
935 {
936         struct ubd *ubd_dev;
937         int n, len = 0;
938
939         n = parse_unit(&name);
940         if((n >= MAX_DEV) || (n < 0)){
941                 *error_out = "ubd_get_config : device number out of range";
942                 return -1;
943         }
944
945         ubd_dev = &ubd_devs[n];
946         mutex_lock(&ubd_lock);
947
948         if(ubd_dev->file == NULL){
949                 CONFIG_CHUNK(str, size, len, "", 1);
950                 goto out;
951         }
952
953         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
954
955         if(ubd_dev->cow.file != NULL){
956                 CONFIG_CHUNK(str, size, len, ",", 0);
957                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
958         }
959         else CONFIG_CHUNK(str, size, len, "", 1);
960
961  out:
962         mutex_unlock(&ubd_lock);
963         return len;
964 }
965
966 static int ubd_id(char **str, int *start_out, int *end_out)
967 {
968         int n;
969
970         n = parse_unit(str);
971         *start_out = 0;
972         *end_out = MAX_DEV - 1;
973         return n;
974 }
975
976 static int ubd_remove(int n, char **error_out)
977 {
978         struct gendisk *disk = ubd_gendisk[n];
979         struct ubd *ubd_dev;
980         int err = -ENODEV;
981
982         mutex_lock(&ubd_lock);
983
984         ubd_dev = &ubd_devs[n];
985
986         if(ubd_dev->file == NULL)
987                 goto out;
988
989         /* you cannot remove a open disk */
990         err = -EBUSY;
991         if(ubd_dev->count > 0)
992                 goto out;
993
994         ubd_gendisk[n] = NULL;
995         if(disk != NULL){
996                 del_gendisk(disk);
997                 put_disk(disk);
998         }
999
1000         if(fake_gendisk[n] != NULL){
1001                 del_gendisk(fake_gendisk[n]);
1002                 put_disk(fake_gendisk[n]);
1003                 fake_gendisk[n] = NULL;
1004         }
1005
1006         err = 0;
1007         platform_device_unregister(&ubd_dev->pdev);
1008 out:
1009         mutex_unlock(&ubd_lock);
1010         return err;
1011 }
1012
1013 /* All these are called by mconsole in process context and without
1014  * ubd-specific locks.  The structure itself is const except for .list.
1015  */
1016 static struct mc_device ubd_mc = {
1017         .list           = LIST_HEAD_INIT(ubd_mc.list),
1018         .name           = "ubd",
1019         .config         = ubd_config,
1020         .get_config     = ubd_get_config,
1021         .id             = ubd_id,
1022         .remove         = ubd_remove,
1023 };
1024
1025 static int __init ubd_mc_init(void)
1026 {
1027         mconsole_register_dev(&ubd_mc);
1028         return 0;
1029 }
1030
1031 __initcall(ubd_mc_init);
1032
1033 static int __init ubd0_init(void)
1034 {
1035         struct ubd *ubd_dev = &ubd_devs[0];
1036
1037         mutex_lock(&ubd_lock);
1038         if(ubd_dev->file == NULL)
1039                 ubd_dev->file = "root_fs";
1040         mutex_unlock(&ubd_lock);
1041
1042         return 0;
1043 }
1044
1045 __initcall(ubd0_init);
1046
1047 /* Used in ubd_init, which is an initcall */
1048 static struct platform_driver ubd_driver = {
1049         .driver = {
1050                 .name  = DRIVER_NAME,
1051         },
1052 };
1053
1054 static int __init ubd_init(void)
1055 {
1056         char *error;
1057         int i, err;
1058
1059         if (register_blkdev(UBD_MAJOR, "ubd"))
1060                 return -1;
1061
1062         if (fake_major != UBD_MAJOR) {
1063                 char name[sizeof("ubd_nnn\0")];
1064
1065                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1066                 if (register_blkdev(fake_major, "ubd"))
1067                         return -1;
1068         }
1069         platform_driver_register(&ubd_driver);
1070         mutex_lock(&ubd_lock);
1071         for (i = 0; i < MAX_DEV; i++){
1072                 err = ubd_add(i, &error);
1073                 if(err)
1074                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1075                                "%s\n", i, error);
1076         }
1077         mutex_unlock(&ubd_lock);
1078         return 0;
1079 }
1080
1081 late_initcall(ubd_init);
1082
1083 static int __init ubd_driver_init(void){
1084         unsigned long stack;
1085         int err;
1086
1087         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1088         if(global_openflags.s){
1089                 printk(KERN_INFO "ubd: Synchronous mode\n");
1090                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1091                  * enough. So use anyway the io thread. */
1092         }
1093         stack = alloc_stack(0, 0);
1094         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1095                                  &thread_fd);
1096         if(io_pid < 0){
1097                 printk(KERN_ERR
1098                        "ubd : Failed to start I/O thread (errno = %d) - "
1099                        "falling back to synchronous I/O\n", -io_pid);
1100                 io_pid = -1;
1101                 return 0;
1102         }
1103         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1104                              0, "ubd", ubd_devs);
1105         if(err != 0)
1106                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1107         return 0;
1108 }
1109
1110 device_initcall(ubd_driver_init);
1111
1112 static int ubd_open(struct block_device *bdev, fmode_t mode)
1113 {
1114         struct gendisk *disk = bdev->bd_disk;
1115         struct ubd *ubd_dev = disk->private_data;
1116         int err = 0;
1117
1118         mutex_lock(&ubd_mutex);
1119         if(ubd_dev->count == 0){
1120                 err = ubd_open_dev(ubd_dev);
1121                 if(err){
1122                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1123                                disk->disk_name, ubd_dev->file, -err);
1124                         goto out;
1125                 }
1126         }
1127         ubd_dev->count++;
1128         set_disk_ro(disk, !ubd_dev->openflags.w);
1129
1130         /* This should no more be needed. And it didn't work anyway to exclude
1131          * read-write remounting of filesystems.*/
1132         /*if((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1133                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1134                 err = -EROFS;
1135         }*/
1136 out:
1137         mutex_unlock(&ubd_mutex);
1138         return err;
1139 }
1140
1141 static int ubd_release(struct gendisk *disk, fmode_t mode)
1142 {
1143         struct ubd *ubd_dev = disk->private_data;
1144
1145         mutex_lock(&ubd_mutex);
1146         if(--ubd_dev->count == 0)
1147                 ubd_close_dev(ubd_dev);
1148         mutex_unlock(&ubd_mutex);
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;
1248
1249         while(1){
1250                 struct ubd *dev = q->queuedata;
1251                 if(dev->end_sg == 0){
1252                         struct request *req = blk_fetch_request(q);
1253                         if(req == NULL)
1254                                 return;
1255
1256                         dev->request = req;
1257                         dev->rq_pos = blk_rq_pos(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                 while(dev->start_sg < dev->end_sg){
1264                         struct scatterlist *sg = &dev->sg[dev->start_sg];
1265
1266                         io_req = kmalloc(sizeof(struct io_thread_req),
1267                                          GFP_ATOMIC);
1268                         if(io_req == NULL){
1269                                 if(list_empty(&dev->restart))
1270                                         list_add(&dev->restart, &restart);
1271                                 return;
1272                         }
1273                         prepare_request(req, io_req,
1274                                         (unsigned long long)dev->rq_pos << 9,
1275                                         sg->offset, sg->length, sg_page(sg));
1276
1277                         n = os_write_file(thread_fd, &io_req,
1278                                           sizeof(struct io_thread_req *));
1279                         if(n != sizeof(struct io_thread_req *)){
1280                                 if(n != -EAGAIN)
1281                                         printk("write to io thread failed, "
1282                                                "errno = %d\n", -n);
1283                                 else if(list_empty(&dev->restart))
1284                                         list_add(&dev->restart, &restart);
1285                                 kfree(io_req);
1286                                 return;
1287                         }
1288
1289                         dev->rq_pos += sg->length >> 9;
1290                         dev->start_sg++;
1291                 }
1292                 dev->end_sg = 0;
1293                 dev->request = NULL;
1294         }
1295 }
1296
1297 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1298 {
1299         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1300
1301         geo->heads = 128;
1302         geo->sectors = 32;
1303         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1304         return 0;
1305 }
1306
1307 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
1308                      unsigned int cmd, unsigned long arg)
1309 {
1310         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1311         u16 ubd_id[ATA_ID_WORDS];
1312
1313         switch (cmd) {
1314                 struct cdrom_volctrl volume;
1315         case HDIO_GET_IDENTITY:
1316                 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1317                 ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
1318                 ubd_id[ATA_ID_HEADS]    = 128;
1319                 ubd_id[ATA_ID_SECTORS]  = 32;
1320                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1321                                  sizeof(ubd_id)))
1322                         return -EFAULT;
1323                 return 0;
1324
1325         case CDROMVOLREAD:
1326                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1327                         return -EFAULT;
1328                 volume.channel0 = 255;
1329                 volume.channel1 = 255;
1330                 volume.channel2 = 255;
1331                 volume.channel3 = 255;
1332                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1333                         return -EFAULT;
1334                 return 0;
1335         }
1336         return -EINVAL;
1337 }
1338
1339 static int update_bitmap(struct io_thread_req *req)
1340 {
1341         int n;
1342
1343         if(req->cow_offset == -1)
1344                 return 0;
1345
1346         n = os_seek_file(req->fds[1], req->cow_offset);
1347         if(n < 0){
1348                 printk("do_io - bitmap lseek failed : err = %d\n", -n);
1349                 return 1;
1350         }
1351
1352         n = os_write_file(req->fds[1], &req->bitmap_words,
1353                           sizeof(req->bitmap_words));
1354         if(n != sizeof(req->bitmap_words)){
1355                 printk("do_io - bitmap update failed, err = %d fd = %d\n", -n,
1356                        req->fds[1]);
1357                 return 1;
1358         }
1359
1360         return 0;
1361 }
1362
1363 static void do_io(struct io_thread_req *req)
1364 {
1365         char *buf;
1366         unsigned long len;
1367         int n, nsectors, start, end, bit;
1368         int err;
1369         __u64 off;
1370
1371         nsectors = req->length / req->sectorsize;
1372         start = 0;
1373         do {
1374                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1375                 end = start;
1376                 while((end < nsectors) &&
1377                       (ubd_test_bit(end, (unsigned char *)
1378                                     &req->sector_mask) == bit))
1379                         end++;
1380
1381                 off = req->offset + req->offsets[bit] +
1382                         start * req->sectorsize;
1383                 len = (end - start) * req->sectorsize;
1384                 buf = &req->buffer[start * req->sectorsize];
1385
1386                 err = os_seek_file(req->fds[bit], off);
1387                 if(err < 0){
1388                         printk("do_io - lseek failed : err = %d\n", -err);
1389                         req->error = 1;
1390                         return;
1391                 }
1392                 if(req->op == UBD_READ){
1393                         n = 0;
1394                         do {
1395                                 buf = &buf[n];
1396                                 len -= n;
1397                                 n = os_read_file(req->fds[bit], buf, len);
1398                                 if (n < 0) {
1399                                         printk("do_io - read failed, err = %d "
1400                                                "fd = %d\n", -n, req->fds[bit]);
1401                                         req->error = 1;
1402                                         return;
1403                                 }
1404                         } while((n < len) && (n != 0));
1405                         if (n < len) memset(&buf[n], 0, len - n);
1406                 } else {
1407                         n = os_write_file(req->fds[bit], buf, len);
1408                         if(n != len){
1409                                 printk("do_io - write failed err = %d "
1410                                        "fd = %d\n", -n, req->fds[bit]);
1411                                 req->error = 1;
1412                                 return;
1413                         }
1414                 }
1415
1416                 start = end;
1417         } while(start < nsectors);
1418
1419         req->error = update_bitmap(req);
1420 }
1421
1422 /* Changed in start_io_thread, which is serialized by being called only
1423  * from ubd_init, which is an initcall.
1424  */
1425 int kernel_fd = -1;
1426
1427 /* Only changed by the io thread. XXX: currently unused. */
1428 static int io_count = 0;
1429
1430 int io_thread(void *arg)
1431 {
1432         struct io_thread_req *req;
1433         int n;
1434
1435         ignore_sigwinch_sig();
1436         while(1){
1437                 n = os_read_file(kernel_fd, &req,
1438                                  sizeof(struct io_thread_req *));
1439                 if(n != sizeof(struct io_thread_req *)){
1440                         if(n < 0)
1441                                 printk("io_thread - read failed, fd = %d, "
1442                                        "err = %d\n", kernel_fd, -n);
1443                         else {
1444                                 printk("io_thread - short read, fd = %d, "
1445                                        "length = %d\n", kernel_fd, n);
1446                         }
1447                         continue;
1448                 }
1449                 io_count++;
1450                 do_io(req);
1451                 n = os_write_file(kernel_fd, &req,
1452                                   sizeof(struct io_thread_req *));
1453                 if(n != sizeof(struct io_thread_req *))
1454                         printk("io_thread - write failed, fd = %d, err = %d\n",
1455                                kernel_fd, -n);
1456         }
1457
1458         return 0;
1459 }