1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2018 Cambridge Greys Ltd
4 * Copyright (C) 2015-2016 Anton Ivanov (aivanov@brocade.com)
5 * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
6 */
7
8 /* 2001-09-28...2002-04-17
9 * Partition stuff by James_McMechan@hotmail.com
10 * old style ubd by setting UBD_SHIFT to 0
11 * 2002-09-27...2002-10-18 massive tinkering for 2.5
12 * partitions have changed in 2.5
13 * 2003-01-29 more tinkering for 2.5.59-1
14 * This should now address the sysfs problems and has
15 * the symlink for devfs to allow for booting with
16 * the common /dev/ubd/discX/... names rather than
17 * only /dev/ubdN/discN this version also has lots of
18 * clean ups preparing for ubd-many.
19 * James McMechan
20 */
21
22 #define UBD_SHIFT 4
23
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/blkdev.h>
27 #include <linux/blk-mq.h>
28 #include <linux/ata.h>
29 #include <linux/hdreg.h>
30 #include <linux/major.h>
31 #include <linux/cdrom.h>
32 #include <linux/proc_fs.h>
33 #include <linux/seq_file.h>
34 #include <linux/ctype.h>
35 #include <linux/slab.h>
36 #include <linux/vmalloc.h>
37 #include <linux/platform_device.h>
38 #include <linux/scatterlist.h>
39 #include <kern_util.h>
40 #include "mconsole_kern.h"
41 #include <init.h>
42 #include <irq_kern.h>
43 #include "ubd.h"
44 #include <os.h>
45 #include "cow.h"
46
47 /* Max request size is determined by sector mask - 32K */
48 #define UBD_MAX_REQUEST (8 * sizeof(long))
49
50 struct io_desc {
51 char *buffer;
52 unsigned long length;
53 unsigned long sector_mask;
54 unsigned long long cow_offset;
55 unsigned long bitmap_words[2];
56 };
57
58 struct io_thread_req {
59 struct request *req;
60 int fds[2];
61 unsigned long offsets[2];
62 unsigned long long offset;
63 int sectorsize;
64 int error;
65
66 int desc_cnt;
67 /* io_desc has to be the last element of the struct */
68 struct io_desc io_desc[];
69 };
70
71
72 static struct io_thread_req * (*irq_req_buffer)[];
73 static struct io_thread_req *irq_remainder;
74 static int irq_remainder_size;
75
76 static struct io_thread_req * (*io_req_buffer)[];
77 static struct io_thread_req *io_remainder;
78 static int io_remainder_size;
79
80
81
82 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
83 {
84 __u64 n;
85 int bits, off;
86
87 bits = sizeof(data[0]) * 8;
88 n = bit / bits;
89 off = bit % bits;
90 return (data[n] & (1 << off)) != 0;
91 }
92
93 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
94 {
95 __u64 n;
96 int bits, off;
97
98 bits = sizeof(data[0]) * 8;
99 n = bit / bits;
100 off = bit % bits;
101 data[n] |= (1 << off);
102 }
103 /*End stuff from ubd_user.h*/
104
105 #define DRIVER_NAME "uml-blkdev"
106
107 static DEFINE_MUTEX(ubd_lock);
108
109 static int ubd_ioctl(struct block_device *bdev, blk_mode_t mode,
110 unsigned int cmd, unsigned long arg);
111 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
112
113 #define MAX_DEV (16)
114
115 static const struct block_device_operations ubd_blops = {
116 .owner = THIS_MODULE,
117 .ioctl = ubd_ioctl,
118 .compat_ioctl = blkdev_compat_ptr_ioctl,
119 .getgeo = ubd_getgeo,
120 };
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 /* name (and fd, below) of the file opened for writing, either the
146 * backing or the cow file. */
147 char *file;
148 char *serial;
149 int fd;
150 __u64 size;
151 struct openflags boot_openflags;
152 struct openflags openflags;
153 unsigned shared:1;
154 unsigned no_cow:1;
155 unsigned no_trim:1;
156 struct cow cow;
157 struct platform_device pdev;
158 struct gendisk *disk;
159 struct blk_mq_tag_set tag_set;
160 spinlock_t lock;
161 };
162
163 #define DEFAULT_COW { \
164 .file = NULL, \
165 .fd = -1, \
166 .bitmap = NULL, \
167 .bitmap_offset = 0, \
168 .data_offset = 0, \
169 }
170
171 #define DEFAULT_UBD { \
172 .file = NULL, \
173 .serial = NULL, \
174 .fd = -1, \
175 .size = -1, \
176 .boot_openflags = OPEN_FLAGS, \
177 .openflags = OPEN_FLAGS, \
178 .no_cow = 0, \
179 .no_trim = 0, \
180 .shared = 0, \
181 .cow = DEFAULT_COW, \
182 .lock = __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
183 }
184
185 /* Protected by ubd_lock */
186 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
187
188 static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
189 const struct blk_mq_queue_data *bd);
190
191 static int fake_ide_setup(char *str)
192 {
193 pr_warn("The fake_ide option has been removed\n");
194 return 1;
195 }
196 __setup("fake_ide", fake_ide_setup);
197
198 __uml_help(fake_ide_setup,
199 "fake_ide\n"
200 " Obsolete stub.\n\n"
201 );
202
203 static int parse_unit(char **ptr)
204 {
205 char *str = *ptr, *end;
206 int n = -1;
207
208 if(isdigit(*str)) {
209 n = simple_strtoul(str, &end, 0);
210 if(end == str)
211 return -1;
212 *ptr = end;
213 }
214 else if (('a' <= *str) && (*str <= 'z')) {
215 n = *str - 'a';
216 str++;
217 *ptr = str;
218 }
219 return n;
220 }
221
222 /* If *index_out == -1 at exit, the passed option was a general one;
223 * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
224 * should not be freed on exit.
225 */
226 static int ubd_setup_common(char *str, int *index_out, char **error_out)
227 {
228 struct ubd *ubd_dev;
229 struct openflags flags = global_openflags;
230 char *file, *backing_file, *serial;
231 int n, err = 0, i;
232
233 if(index_out) *index_out = -1;
234 n = *str;
235 if(n == '='){
236 str++;
237 if(!strcmp(str, "sync")){
238 global_openflags = of_sync(global_openflags);
239 return err;
240 }
241
242 pr_warn("fake major not supported any more\n");
243 return 0;
244 }
245
246 n = parse_unit(&str);
247 if(n < 0){
248 *error_out = "Couldn't parse device number";
249 return -EINVAL;
250 }
251 if(n >= MAX_DEV){
252 *error_out = "Device number out of range";
253 return 1;
254 }
255
256 err = -EBUSY;
257 mutex_lock(&ubd_lock);
258
259 ubd_dev = &ubd_devs[n];
260 if(ubd_dev->file != NULL){
261 *error_out = "Device is already configured";
262 goto out;
263 }
264
265 if (index_out)
266 *index_out = n;
267
268 err = -EINVAL;
269 for (i = 0; i < sizeof("rscdt="); i++) {
270 switch (*str) {
271 case 'r':
272 flags.w = 0;
273 break;
274 case 's':
275 flags.s = 1;
276 break;
277 case 'd':
278 ubd_dev->no_cow = 1;
279 break;
280 case 'c':
281 ubd_dev->shared = 1;
282 break;
283 case 't':
284 ubd_dev->no_trim = 1;
285 break;
286 case '=':
287 str++;
288 goto break_loop;
289 default:
290 *error_out = "Expected '=' or flag letter "
291 "(r, s, c, t or d)";
292 goto out;
293 }
294 str++;
295 }
296
297 if (*str == '=')
298 *error_out = "Too many flags specified";
299 else
300 *error_out = "Missing '='";
301 goto out;
302
303 break_loop:
304 file = strsep(&str, ",:");
305 if (*file == '\0')
306 file = NULL;
307
308 backing_file = strsep(&str, ",:");
309 if (backing_file && *backing_file == '\0')
310 backing_file = NULL;
311
312 serial = strsep(&str, ",:");
313 if (serial && *serial == '\0')
314 serial = NULL;
315
316 if (backing_file && ubd_dev->no_cow) {
317 *error_out = "Can't specify both 'd' and a cow file";
318 goto out;
319 }
320
321 err = 0;
322 ubd_dev->file = file;
323 ubd_dev->cow.file = backing_file;
324 ubd_dev->serial = serial;
325 ubd_dev->boot_openflags = flags;
326 out:
327 mutex_unlock(&ubd_lock);
328 return err;
329 }
330
331 static int ubd_setup(char *str)
332 {
333 char *error;
334 int err;
335
336 err = ubd_setup_common(str, NULL, &error);
337 if(err)
338 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
339 "%s\n", str, error);
340 return 1;
341 }
342
343 __setup("ubd", ubd_setup);
344 __uml_help(ubd_setup,
345 "ubd<n><flags>=<filename>[(:|,)<filename2>][(:|,)<serial>]\n"
346 " This is used to associate a device with a file in the underlying\n"
347 " filesystem. When specifying two filenames, the first one is the\n"
348 " COW name and the second is the backing file name. As separator you can\n"
349 " use either a ':' or a ',': the first one allows writing things like;\n"
350 " ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
351 " while with a ',' the shell would not expand the 2nd '~'.\n"
352 " When using only one filename, UML will detect whether to treat it like\n"
353 " a COW file or a backing file. To override this detection, add the 'd'\n"
354 " flag:\n"
355 " ubd0d=BackingFile\n"
356 " Usually, there is a filesystem in the file, but \n"
357 " that's not required. Swap devices containing swap files can be\n"
358 " specified like this. Also, a file which doesn't contain a\n"
359 " filesystem can have its contents read in the virtual \n"
360 " machine by running 'dd' on the device. <n> must be in the range\n"
361 " 0 to 7. Appending an 'r' to the number will cause that device\n"
362 " to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
363 " an 's' will cause data to be written to disk on the host immediately.\n"
364 " 'c' will cause the device to be treated as being shared between multiple\n"
365 " UMLs and file locking will be turned off - this is appropriate for a\n"
366 " cluster filesystem and inappropriate at almost all other times.\n\n"
367 " 't' will disable trim/discard support on the device (enabled by default).\n\n"
368 " An optional device serial number can be exposed using the serial parameter\n"
369 " on the cmdline which is exposed as a sysfs entry. This is particularly\n"
370 " useful when a unique number should be given to the device. Note when\n"
371 " specifying a label, the filename2 must be also presented. It can be\n"
372 " an empty string, in which case the backing file is not used:\n"
373 " ubd0=File,,Serial\n"
374 );
375
376 static int udb_setup(char *str)
377 {
378 printk("udb%s specified on command line is almost certainly a ubd -> "
379 "udb TYPO\n", str);
380 return 1;
381 }
382
383 __setup("udb", udb_setup);
384 __uml_help(udb_setup,
385 "udb\n"
386 " This option is here solely to catch ubd -> udb typos, which can be\n"
387 " to impossible to catch visually unless you specifically look for\n"
388 " them. The only result of any option starting with 'udb' is an error\n"
389 " in the boot output.\n\n"
390 );
391
392 /* Only changed by ubd_init, which is an initcall. */
393 static int thread_fd = -1;
394
395 /* Function to read several request pointers at a time
396 * handling fractional reads if (and as) needed
397 */
398
399 static int bulk_req_safe_read(
400 int fd,
401 struct io_thread_req * (*request_buffer)[],
402 struct io_thread_req **remainder,
403 int *remainder_size,
404 int max_recs
405 )
406 {
407 int n = 0;
408 int res = 0;
409
410 if (*remainder_size > 0) {
411 memmove(
412 (char *) request_buffer,
413 (char *) remainder, *remainder_size
414 );
415 n = *remainder_size;
416 }
417
418 res = os_read_file(
419 fd,
420 ((char *) request_buffer) + *remainder_size,
421 sizeof(struct io_thread_req *)*max_recs
422 - *remainder_size
423 );
424 if (res > 0) {
425 n += res;
426 if ((n % sizeof(struct io_thread_req *)) > 0) {
427 /*
428 * Read somehow returned not a multiple of dword
429 * theoretically possible, but never observed in the
430 * wild, so read routine must be able to handle it
431 */
432 *remainder_size = n % sizeof(struct io_thread_req *);
433 WARN(*remainder_size > 0, "UBD IPC read returned a partial result");
434 memmove(
435 remainder,
436 ((char *) request_buffer) +
437 (n/sizeof(struct io_thread_req *))*sizeof(struct io_thread_req *),
438 *remainder_size
439 );
440 n = n - *remainder_size;
441 }
442 } else {
443 n = res;
444 }
445 return n;
446 }
447
448 static void ubd_end_request(struct io_thread_req *io_req)
449 {
450 if (io_req->error == BLK_STS_NOTSUPP) {
451 if (req_op(io_req->req) == REQ_OP_DISCARD)
452 blk_queue_disable_discard(io_req->req->q);
453 else if (req_op(io_req->req) == REQ_OP_WRITE_ZEROES)
454 blk_queue_disable_write_zeroes(io_req->req->q);
455 }
456 blk_mq_end_request(io_req->req, io_req->error);
457 kfree(io_req);
458 }
459
460 static irqreturn_t ubd_intr(int irq, void *dev)
461 {
462 int len, i;
463
464 while ((len = bulk_req_safe_read(thread_fd, irq_req_buffer,
465 &irq_remainder, &irq_remainder_size,
466 UBD_REQ_BUFFER_SIZE)) >= 0) {
467 for (i = 0; i < len / sizeof(struct io_thread_req *); i++)
468 ubd_end_request((*irq_req_buffer)[i]);
469 }
470
471 if (len < 0 && len != -EAGAIN)
472 pr_err("spurious interrupt in %s, err = %d\n", __func__, len);
473 return IRQ_HANDLED;
474 }
475
476 /* Only changed by ubd_init, which is an initcall. */
477 static int io_pid = -1;
478
479 static void kill_io_thread(void)
480 {
481 if(io_pid != -1)
482 os_kill_process(io_pid, 1);
483 }
484
485 __uml_exitcall(kill_io_thread);
486
487 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
488 {
489 char *file;
490 int fd;
491 int err;
492
493 __u32 version;
494 __u32 align;
495 char *backing_file;
496 time64_t mtime;
497 unsigned long long size;
498 int sector_size;
499 int bitmap_offset;
500
501 if (ubd_dev->file && ubd_dev->cow.file) {
502 file = ubd_dev->cow.file;
503
504 goto out;
505 }
506
507 fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
508 if (fd < 0)
509 return fd;
510
511 err = read_cow_header(file_reader, &fd, &version, &backing_file, \
512 &mtime, &size, §or_size, &align, &bitmap_offset);
513 os_close_file(fd);
514
515 if(err == -EINVAL)
516 file = ubd_dev->file;
517 else
518 file = backing_file;
519
520 out:
521 return os_file_size(file, size_out);
522 }
523
524 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
525 {
526 int err;
527
528 err = os_pread_file(fd, buf, len, offset);
529 if (err < 0)
530 return err;
531
532 return 0;
533 }
534
535 static int backing_file_mismatch(char *file, __u64 size, time64_t mtime)
536 {
537 time64_t modtime;
538 unsigned long long actual;
539 int err;
540
541 err = os_file_modtime(file, &modtime);
542 if (err < 0) {
543 printk(KERN_ERR "Failed to get modification time of backing "
544 "file \"%s\", err = %d\n", file, -err);
545 return err;
546 }
547
548 err = os_file_size(file, &actual);
549 if (err < 0) {
550 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
551 "err = %d\n", file, -err);
552 return err;
553 }
554
555 if (actual != size) {
556 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
557 * the typecast.*/
558 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
559 "vs backing file\n", (unsigned long long) size, actual);
560 return -EINVAL;
561 }
562 if (modtime != mtime) {
563 printk(KERN_ERR "mtime mismatch (%lld vs %lld) of COW header vs "
564 "backing file\n", mtime, modtime);
565 return -EINVAL;
566 }
567 return 0;
568 }
569
570 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
571 {
572 struct uml_stat buf1, buf2;
573 int err;
574
575 if (from_cmdline == NULL)
576 return 0;
577 if (!strcmp(from_cmdline, from_cow))
578 return 0;
579
580 err = os_stat_file(from_cmdline, &buf1);
581 if (err < 0) {
582 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
583 -err);
584 return 0;
585 }
586 err = os_stat_file(from_cow, &buf2);
587 if (err < 0) {
588 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
589 -err);
590 return 1;
591 }
592 if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
593 return 0;
594
595 printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
596 "\"%s\" specified in COW header of \"%s\"\n",
597 from_cmdline, from_cow, cow);
598 return 1;
599 }
600
601 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
602 char **backing_file_out, int *bitmap_offset_out,
603 unsigned long *bitmap_len_out, int *data_offset_out,
604 int *create_cow_out)
605 {
606 time64_t mtime;
607 unsigned long long size;
608 __u32 version, align;
609 char *backing_file;
610 int fd, err, sectorsize, asked_switch, mode = 0644;
611
612 fd = os_open_file(file, *openflags, mode);
613 if (fd < 0) {
614 if ((fd == -ENOENT) && (create_cow_out != NULL))
615 *create_cow_out = 1;
616 if (!openflags->w ||
617 ((fd != -EROFS) && (fd != -EACCES)))
618 return fd;
619 openflags->w = 0;
620 fd = os_open_file(file, *openflags, mode);
621 if (fd < 0)
622 return fd;
623 }
624
625 if (shared)
626 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
627 else {
628 err = os_lock_file(fd, openflags->w);
629 if (err < 0) {
630 printk(KERN_ERR "Failed to lock '%s', err = %d\n",
631 file, -err);
632 goto out_close;
633 }
634 }
635
636 /* Successful return case! */
637 if (backing_file_out == NULL)
638 return fd;
639
640 err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
641 &size, §orsize, &align, bitmap_offset_out);
642 if (err && (*backing_file_out != NULL)) {
643 printk(KERN_ERR "Failed to read COW header from COW file "
644 "\"%s\", errno = %d\n", file, -err);
645 goto out_close;
646 }
647 if (err)
648 return fd;
649
650 asked_switch = path_requires_switch(*backing_file_out, backing_file,
651 file);
652
653 /* Allow switching only if no mismatch. */
654 if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
655 mtime)) {
656 printk(KERN_ERR "Switching backing file to '%s'\n",
657 *backing_file_out);
658 err = write_cow_header(file, fd, *backing_file_out,
659 sectorsize, align, &size);
660 if (err) {
661 printk(KERN_ERR "Switch failed, errno = %d\n", -err);
662 goto out_close;
663 }
664 } else {
665 *backing_file_out = backing_file;
666 err = backing_file_mismatch(*backing_file_out, size, mtime);
667 if (err)
668 goto out_close;
669 }
670
671 cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
672 bitmap_len_out, data_offset_out);
673
674 return fd;
675 out_close:
676 os_close_file(fd);
677 return err;
678 }
679
680 static int create_cow_file(char *cow_file, char *backing_file,
681 struct openflags flags,
682 int sectorsize, int alignment, int *bitmap_offset_out,
683 unsigned long *bitmap_len_out, int *data_offset_out)
684 {
685 int err, fd;
686
687 flags.c = 1;
688 fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
689 if (fd < 0) {
690 err = fd;
691 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
692 cow_file, -err);
693 goto out;
694 }
695
696 err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
697 bitmap_offset_out, bitmap_len_out,
698 data_offset_out);
699 if (!err)
700 return fd;
701 os_close_file(fd);
702 out:
703 return err;
704 }
705
706 static void ubd_close_dev(struct ubd *ubd_dev)
707 {
708 os_close_file(ubd_dev->fd);
709 if(ubd_dev->cow.file == NULL)
710 return;
711
712 os_close_file(ubd_dev->cow.fd);
713 vfree(ubd_dev->cow.bitmap);
714 ubd_dev->cow.bitmap = NULL;
715 }
716
717 static int ubd_open_dev(struct ubd *ubd_dev)
718 {
719 struct openflags flags;
720 char **back_ptr;
721 int err, create_cow, *create_ptr;
722 int fd;
723
724 ubd_dev->openflags = ubd_dev->boot_openflags;
725 create_cow = 0;
726 create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
727 back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
728
729 fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
730 back_ptr, &ubd_dev->cow.bitmap_offset,
731 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
732 create_ptr);
733
734 if((fd == -ENOENT) && create_cow){
735 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
736 ubd_dev->openflags, SECTOR_SIZE, PAGE_SIZE,
737 &ubd_dev->cow.bitmap_offset,
738 &ubd_dev->cow.bitmap_len,
739 &ubd_dev->cow.data_offset);
740 if(fd >= 0){
741 printk(KERN_INFO "Creating \"%s\" as COW file for "
742 "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
743 }
744 }
745
746 if(fd < 0){
747 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
748 -fd);
749 return fd;
750 }
751 ubd_dev->fd = fd;
752
753 if(ubd_dev->cow.file != NULL){
754 err = -ENOMEM;
755 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
756 if(ubd_dev->cow.bitmap == NULL){
757 printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
758 goto error;
759 }
760
761 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
762 ubd_dev->cow.bitmap_offset,
763 ubd_dev->cow.bitmap_len);
764 if(err < 0)
765 goto error;
766
767 flags = ubd_dev->openflags;
768 flags.w = 0;
769 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
770 NULL, NULL, NULL, NULL);
771 if(err < 0) goto error;
772 ubd_dev->cow.fd = err;
773 }
774 return 0;
775 error:
776 os_close_file(ubd_dev->fd);
777 return err;
778 }
779
780 static void ubd_device_release(struct device *dev)
781 {
782 struct ubd *ubd_dev = dev_get_drvdata(dev);
783
784 blk_mq_free_tag_set(&ubd_dev->tag_set);
785 *ubd_dev = ((struct ubd) DEFAULT_UBD);
786 }
787
788 static ssize_t serial_show(struct device *dev,
789 struct device_attribute *attr, char *buf)
790 {
791 struct gendisk *disk = dev_to_disk(dev);
792 struct ubd *ubd_dev = disk->private_data;
793
794 if (!ubd_dev)
795 return 0;
796
797 return sprintf(buf, "%s", ubd_dev->serial);
798 }
799
800 static DEVICE_ATTR_RO(serial);
801
802 static struct attribute *ubd_attrs[] = {
803 &dev_attr_serial.attr,
804 NULL,
805 };
806
807 static umode_t ubd_attrs_are_visible(struct kobject *kobj,
808 struct attribute *a, int n)
809 {
810 return a->mode;
811 }
812
813 static const struct attribute_group ubd_attr_group = {
814 .attrs = ubd_attrs,
815 .is_visible = ubd_attrs_are_visible,
816 };
817
818 static const struct attribute_group *ubd_attr_groups[] = {
819 &ubd_attr_group,
820 NULL,
821 };
822
823 #define ROUND_BLOCK(n) ((n + (SECTOR_SIZE - 1)) & (-SECTOR_SIZE))
824
825 static const struct blk_mq_ops ubd_mq_ops = {
826 .queue_rq = ubd_queue_rq,
827 };
828
829 static int ubd_add(int n, char **error_out)
830 {
831 struct ubd *ubd_dev = &ubd_devs[n];
832 struct queue_limits lim = {
833 .max_segments = MAX_SG,
834 .seg_boundary_mask = PAGE_SIZE - 1,
835 .features = BLK_FEAT_WRITE_CACHE,
836 };
837 struct gendisk *disk;
838 int err = 0;
839
840 if(ubd_dev->file == NULL)
841 goto out;
842
843 if (ubd_dev->cow.file)
844 lim.max_hw_sectors = 8 * sizeof(long);
845 if (!ubd_dev->no_trim) {
846 lim.max_hw_discard_sectors = UBD_MAX_REQUEST;
847 lim.max_write_zeroes_sectors = UBD_MAX_REQUEST;
848 }
849
850 err = ubd_file_size(ubd_dev, &ubd_dev->size);
851 if(err < 0){
852 *error_out = "Couldn't determine size of device's file";
853 goto out;
854 }
855
856 err = ubd_open_dev(ubd_dev);
857 if (err) {
858 pr_err("ubd%c: Can't open \"%s\": errno = %d\n",
859 'a' + n, ubd_dev->file, -err);
860 goto out;
861 }
862
863 ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
864
865 ubd_dev->tag_set.ops = &ubd_mq_ops;
866 ubd_dev->tag_set.queue_depth = 64;
867 ubd_dev->tag_set.numa_node = NUMA_NO_NODE;
868 ubd_dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
869 ubd_dev->tag_set.driver_data = ubd_dev;
870 ubd_dev->tag_set.nr_hw_queues = 1;
871
872 err = blk_mq_alloc_tag_set(&ubd_dev->tag_set);
873 if (err)
874 goto out_close;
875
876 disk = blk_mq_alloc_disk(&ubd_dev->tag_set, &lim, ubd_dev);
877 if (IS_ERR(disk)) {
878 err = PTR_ERR(disk);
879 goto out_cleanup_tags;
880 }
881
882 disk->major = UBD_MAJOR;
883 disk->first_minor = n << UBD_SHIFT;
884 disk->minors = 1 << UBD_SHIFT;
885 disk->fops = &ubd_blops;
886 set_capacity(disk, ubd_dev->size / 512);
887 sprintf(disk->disk_name, "ubd%c", 'a' + n);
888 disk->private_data = ubd_dev;
889 set_disk_ro(disk, !ubd_dev->openflags.w);
890
891 ubd_dev->pdev.id = n;
892 ubd_dev->pdev.name = DRIVER_NAME;
893 ubd_dev->pdev.dev.release = ubd_device_release;
894 dev_set_drvdata(&ubd_dev->pdev.dev, ubd_dev);
895 platform_device_register(&ubd_dev->pdev);
896
897 err = device_add_disk(&ubd_dev->pdev.dev, disk, ubd_attr_groups);
898 if (err)
899 goto out_cleanup_disk;
900
901 return 0;
902
903 out_cleanup_disk:
904 put_disk(disk);
905 out_cleanup_tags:
906 blk_mq_free_tag_set(&ubd_dev->tag_set);
907 out_close:
908 ubd_close_dev(ubd_dev);
909 out:
910 return err;
911 }
912
913 static int ubd_config(char *str, char **error_out)
914 {
915 int n, ret;
916
917 /* This string is possibly broken up and stored, so it's only
918 * freed if ubd_setup_common fails, or if only general options
919 * were set.
920 */
921 str = kstrdup(str, GFP_KERNEL);
922 if (str == NULL) {
923 *error_out = "Failed to allocate memory";
924 return -ENOMEM;
925 }
926
927 ret = ubd_setup_common(str, &n, error_out);
928 if (ret)
929 goto err_free;
930
931 if (n == -1) {
932 ret = 0;
933 goto err_free;
934 }
935
936 mutex_lock(&ubd_lock);
937 ret = ubd_add(n, error_out);
938 if (ret)
939 ubd_devs[n].file = NULL;
940 mutex_unlock(&ubd_lock);
941
942 out:
943 return ret;
944
945 err_free:
946 kfree(str);
947 goto out;
948 }
949
950 static int ubd_get_config(char *name, char *str, int size, char **error_out)
951 {
952 struct ubd *ubd_dev;
953 int n, len = 0;
954
955 n = parse_unit(&name);
956 if((n >= MAX_DEV) || (n < 0)){
957 *error_out = "ubd_get_config : device number out of range";
958 return -1;
959 }
960
961 ubd_dev = &ubd_devs[n];
962 mutex_lock(&ubd_lock);
963
964 if(ubd_dev->file == NULL){
965 CONFIG_CHUNK(str, size, len, "", 1);
966 goto out;
967 }
968
969 CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
970
971 if(ubd_dev->cow.file != NULL){
972 CONFIG_CHUNK(str, size, len, ",", 0);
973 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
974 }
975 else CONFIG_CHUNK(str, size, len, "", 1);
976
977 out:
978 mutex_unlock(&ubd_lock);
979 return len;
980 }
981
982 static int ubd_id(char **str, int *start_out, int *end_out)
983 {
984 int n;
985
986 n = parse_unit(str);
987 *start_out = 0;
988 *end_out = MAX_DEV - 1;
989 return n;
990 }
991
992 static int ubd_remove(int n, char **error_out)
993 {
994 struct ubd *ubd_dev;
995 int err = -ENODEV;
996
997 mutex_lock(&ubd_lock);
998
999 ubd_dev = &ubd_devs[n];
1000
1001 if(ubd_dev->file == NULL)
1002 goto out;
1003
1004 if (ubd_dev->disk) {
1005 /* you cannot remove a open disk */
1006 err = -EBUSY;
1007 if (disk_openers(ubd_dev->disk))
1008 goto out;
1009
1010 del_gendisk(ubd_dev->disk);
1011 ubd_close_dev(ubd_dev);
1012 put_disk(ubd_dev->disk);
1013 }
1014
1015 err = 0;
1016 platform_device_unregister(&ubd_dev->pdev);
1017 out:
1018 mutex_unlock(&ubd_lock);
1019 return err;
1020 }
1021
1022 /* All these are called by mconsole in process context and without
1023 * ubd-specific locks. The structure itself is const except for .list.
1024 */
1025 static struct mc_device ubd_mc = {
1026 .list = LIST_HEAD_INIT(ubd_mc.list),
1027 .name = "ubd",
1028 .config = ubd_config,
1029 .get_config = ubd_get_config,
1030 .id = ubd_id,
1031 .remove = ubd_remove,
1032 };
1033
1034 static int __init ubd_mc_init(void)
1035 {
1036 mconsole_register_dev(&ubd_mc);
1037 return 0;
1038 }
1039
1040 __initcall(ubd_mc_init);
1041
1042 static int __init ubd0_init(void)
1043 {
1044 struct ubd *ubd_dev = &ubd_devs[0];
1045
1046 mutex_lock(&ubd_lock);
1047 if(ubd_dev->file == NULL)
1048 ubd_dev->file = "root_fs";
1049 mutex_unlock(&ubd_lock);
1050
1051 return 0;
1052 }
1053
1054 __initcall(ubd0_init);
1055
1056 /* Used in ubd_init, which is an initcall */
1057 static struct platform_driver ubd_driver = {
1058 .driver = {
1059 .name = DRIVER_NAME,
1060 },
1061 };
1062
1063 static int __init ubd_init(void)
1064 {
1065 char *error;
1066 int i, err;
1067
1068 if (register_blkdev(UBD_MAJOR, "ubd"))
1069 return -1;
1070
1071 irq_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1072 sizeof(struct io_thread_req *),
1073 GFP_KERNEL
1074 );
1075 irq_remainder = 0;
1076
1077 if (irq_req_buffer == NULL) {
1078 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1079 return -ENOMEM;
1080 }
1081 io_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1082 sizeof(struct io_thread_req *),
1083 GFP_KERNEL
1084 );
1085
1086 io_remainder = 0;
1087
1088 if (io_req_buffer == NULL) {
1089 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1090 return -ENOMEM;
1091 }
1092 platform_driver_register(&ubd_driver);
1093 mutex_lock(&ubd_lock);
1094 for (i = 0; i < MAX_DEV; i++){
1095 err = ubd_add(i, &error);
1096 if(err)
1097 printk(KERN_ERR "Failed to initialize ubd device %d :"
1098 "%s\n", i, error);
1099 }
1100 mutex_unlock(&ubd_lock);
1101 return 0;
1102 }
1103
1104 late_initcall(ubd_init);
1105
1106 static int __init ubd_driver_init(void){
1107 unsigned long stack;
1108 int err;
1109
1110 /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1111 if(global_openflags.s){
1112 printk(KERN_INFO "ubd: Synchronous mode\n");
1113 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1114 * enough. So use anyway the io thread. */
1115 }
1116 stack = alloc_stack(0, 0);
1117 io_pid = start_io_thread(stack + PAGE_SIZE, &thread_fd);
1118 if(io_pid < 0){
1119 printk(KERN_ERR
1120 "ubd : Failed to start I/O thread (errno = %d) - "
1121 "falling back to synchronous I/O\n", -io_pid);
1122 io_pid = -1;
1123 return 0;
1124 }
1125 err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1126 0, "ubd", ubd_devs);
1127 if(err < 0)
1128 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1129 return 0;
1130 }
1131
1132 device_initcall(ubd_driver_init);
1133
1134 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1135 __u64 *cow_offset, unsigned long *bitmap,
1136 __u64 bitmap_offset, unsigned long *bitmap_words,
1137 __u64 bitmap_len)
1138 {
1139 __u64 sector = io_offset >> SECTOR_SHIFT;
1140 int i, update_bitmap = 0;
1141
1142 for (i = 0; i < length >> SECTOR_SHIFT; i++) {
1143 if(cow_mask != NULL)
1144 ubd_set_bit(i, (unsigned char *) cow_mask);
1145 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1146 continue;
1147
1148 update_bitmap = 1;
1149 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1150 }
1151
1152 if(!update_bitmap)
1153 return;
1154
1155 *cow_offset = sector / (sizeof(unsigned long) * 8);
1156
1157 /* This takes care of the case where we're exactly at the end of the
1158 * device, and *cow_offset + 1 is off the end. So, just back it up
1159 * by one word. Thanks to Lynn Kerby for the fix and James McMechan
1160 * for the original diagnosis.
1161 */
1162 if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1163 sizeof(unsigned long)) - 1))
1164 (*cow_offset)--;
1165
1166 bitmap_words[0] = bitmap[*cow_offset];
1167 bitmap_words[1] = bitmap[*cow_offset + 1];
1168
1169 *cow_offset *= sizeof(unsigned long);
1170 *cow_offset += bitmap_offset;
1171 }
1172
1173 static void cowify_req(struct io_thread_req *req, struct io_desc *segment,
1174 unsigned long offset, unsigned long *bitmap,
1175 __u64 bitmap_offset, __u64 bitmap_len)
1176 {
1177 __u64 sector = offset >> SECTOR_SHIFT;
1178 int i;
1179
1180 if (segment->length > (sizeof(segment->sector_mask) * 8) << SECTOR_SHIFT)
1181 panic("Operation too long");
1182
1183 if (req_op(req->req) == REQ_OP_READ) {
1184 for (i = 0; i < segment->length >> SECTOR_SHIFT; i++) {
1185 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1186 ubd_set_bit(i, (unsigned char *)
1187 &segment->sector_mask);
1188 }
1189 } else {
1190 cowify_bitmap(offset, segment->length, &segment->sector_mask,
1191 &segment->cow_offset, bitmap, bitmap_offset,
1192 segment->bitmap_words, bitmap_len);
1193 }
1194 }
1195
1196 static void ubd_map_req(struct ubd *dev, struct io_thread_req *io_req,
1197 struct request *req)
1198 {
1199 struct bio_vec bvec;
1200 struct req_iterator iter;
1201 int i = 0;
1202 unsigned long byte_offset = io_req->offset;
1203 enum req_op op = req_op(req);
1204
1205 if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD) {
1206 io_req->io_desc[0].buffer = NULL;
1207 io_req->io_desc[0].length = blk_rq_bytes(req);
1208 } else {
1209 rq_for_each_segment(bvec, req, iter) {
1210 BUG_ON(i >= io_req->desc_cnt);
1211
1212 io_req->io_desc[i].buffer = bvec_virt(&bvec);
1213 io_req->io_desc[i].length = bvec.bv_len;
1214 i++;
1215 }
1216 }
1217
1218 if (dev->cow.file) {
1219 for (i = 0; i < io_req->desc_cnt; i++) {
1220 cowify_req(io_req, &io_req->io_desc[i], byte_offset,
1221 dev->cow.bitmap, dev->cow.bitmap_offset,
1222 dev->cow.bitmap_len);
1223 byte_offset += io_req->io_desc[i].length;
1224 }
1225
1226 }
1227 }
1228
1229 static struct io_thread_req *ubd_alloc_req(struct ubd *dev, struct request *req,
1230 int desc_cnt)
1231 {
1232 struct io_thread_req *io_req;
1233 int i;
1234
1235 io_req = kmalloc(sizeof(*io_req) +
1236 (desc_cnt * sizeof(struct io_desc)),
1237 GFP_ATOMIC);
1238 if (!io_req)
1239 return NULL;
1240
1241 io_req->req = req;
1242 if (dev->cow.file)
1243 io_req->fds[0] = dev->cow.fd;
1244 else
1245 io_req->fds[0] = dev->fd;
1246 io_req->error = 0;
1247 io_req->sectorsize = SECTOR_SIZE;
1248 io_req->fds[1] = dev->fd;
1249 io_req->offset = (u64) blk_rq_pos(req) << SECTOR_SHIFT;
1250 io_req->offsets[0] = 0;
1251 io_req->offsets[1] = dev->cow.data_offset;
1252
1253 for (i = 0 ; i < desc_cnt; i++) {
1254 io_req->io_desc[i].sector_mask = 0;
1255 io_req->io_desc[i].cow_offset = -1;
1256 }
1257
1258 return io_req;
1259 }
1260
1261 static int ubd_submit_request(struct ubd *dev, struct request *req)
1262 {
1263 int segs = 0;
1264 struct io_thread_req *io_req;
1265 int ret;
1266 enum req_op op = req_op(req);
1267
1268 if (op == REQ_OP_FLUSH)
1269 segs = 0;
1270 else if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD)
1271 segs = 1;
1272 else
1273 segs = blk_rq_nr_phys_segments(req);
1274
1275 io_req = ubd_alloc_req(dev, req, segs);
1276 if (!io_req)
1277 return -ENOMEM;
1278
1279 io_req->desc_cnt = segs;
1280 if (segs)
1281 ubd_map_req(dev, io_req, req);
1282
1283 ret = os_write_file(thread_fd, &io_req, sizeof(io_req));
1284 if (ret != sizeof(io_req)) {
1285 if (ret != -EAGAIN)
1286 pr_err("write to io thread failed: %d\n", -ret);
1287 kfree(io_req);
1288 }
1289 return ret;
1290 }
1291
1292 static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
1293 const struct blk_mq_queue_data *bd)
1294 {
1295 struct ubd *ubd_dev = hctx->queue->queuedata;
1296 struct request *req = bd->rq;
1297 int ret = 0, res = BLK_STS_OK;
1298
1299 blk_mq_start_request(req);
1300
1301 spin_lock_irq(&ubd_dev->lock);
1302
1303 switch (req_op(req)) {
1304 case REQ_OP_FLUSH:
1305 case REQ_OP_READ:
1306 case REQ_OP_WRITE:
1307 case REQ_OP_DISCARD:
1308 case REQ_OP_WRITE_ZEROES:
1309 ret = ubd_submit_request(ubd_dev, req);
1310 break;
1311 default:
1312 WARN_ON_ONCE(1);
1313 res = BLK_STS_NOTSUPP;
1314 }
1315
1316 spin_unlock_irq(&ubd_dev->lock);
1317
1318 if (ret < 0) {
1319 if (ret == -ENOMEM)
1320 res = BLK_STS_RESOURCE;
1321 else
1322 res = BLK_STS_DEV_RESOURCE;
1323 }
1324
1325 return res;
1326 }
1327
1328 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1329 {
1330 struct ubd *ubd_dev = bdev->bd_disk->private_data;
1331
1332 geo->heads = 128;
1333 geo->sectors = 32;
1334 geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1335 return 0;
1336 }
1337
1338 static int ubd_ioctl(struct block_device *bdev, blk_mode_t mode,
1339 unsigned int cmd, unsigned long arg)
1340 {
1341 struct ubd *ubd_dev = bdev->bd_disk->private_data;
1342 u16 ubd_id[ATA_ID_WORDS];
1343
1344 switch (cmd) {
1345 struct cdrom_volctrl volume;
1346 case HDIO_GET_IDENTITY:
1347 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1348 ubd_id[ATA_ID_CYLS] = ubd_dev->size / (128 * 32 * 512);
1349 ubd_id[ATA_ID_HEADS] = 128;
1350 ubd_id[ATA_ID_SECTORS] = 32;
1351 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1352 sizeof(ubd_id)))
1353 return -EFAULT;
1354 return 0;
1355
1356 case CDROMVOLREAD:
1357 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1358 return -EFAULT;
1359 volume.channel0 = 255;
1360 volume.channel1 = 255;
1361 volume.channel2 = 255;
1362 volume.channel3 = 255;
1363 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1364 return -EFAULT;
1365 return 0;
1366 }
1367 return -EINVAL;
1368 }
1369
1370 static int map_error(int error_code)
1371 {
1372 switch (error_code) {
1373 case 0:
1374 return BLK_STS_OK;
1375 case ENOSYS:
1376 case EOPNOTSUPP:
1377 return BLK_STS_NOTSUPP;
1378 case ENOSPC:
1379 return BLK_STS_NOSPC;
1380 }
1381 return BLK_STS_IOERR;
1382 }
1383
1384 /*
1385 * Everything from here onwards *IS NOT PART OF THE KERNEL*
1386 *
1387 * The following functions are part of UML hypervisor code.
1388 * All functions from here onwards are executed as a helper
1389 * thread and are not allowed to execute any kernel functions.
1390 *
1391 * Any communication must occur strictly via shared memory and IPC.
1392 *
1393 * Do not add printks, locks, kernel memory operations, etc - it
1394 * will result in unpredictable behaviour and/or crashes.
1395 */
1396
1397 static int update_bitmap(struct io_thread_req *req, struct io_desc *segment)
1398 {
1399 int n;
1400
1401 if (segment->cow_offset == -1)
1402 return map_error(0);
1403
1404 n = os_pwrite_file(req->fds[1], &segment->bitmap_words,
1405 sizeof(segment->bitmap_words), segment->cow_offset);
1406 if (n != sizeof(segment->bitmap_words))
1407 return map_error(-n);
1408
1409 return map_error(0);
1410 }
1411
1412 static void do_io(struct io_thread_req *req, struct io_desc *desc)
1413 {
1414 char *buf = NULL;
1415 unsigned long len;
1416 int n, nsectors, start, end, bit;
1417 __u64 off;
1418
1419 /* FLUSH is really a special case, we cannot "case" it with others */
1420
1421 if (req_op(req->req) == REQ_OP_FLUSH) {
1422 /* fds[0] is always either the rw image or our cow file */
1423 req->error = map_error(-os_sync_file(req->fds[0]));
1424 return;
1425 }
1426
1427 nsectors = desc->length / req->sectorsize;
1428 start = 0;
1429 do {
1430 bit = ubd_test_bit(start, (unsigned char *) &desc->sector_mask);
1431 end = start;
1432 while((end < nsectors) &&
1433 (ubd_test_bit(end, (unsigned char *) &desc->sector_mask) == bit))
1434 end++;
1435
1436 off = req->offset + req->offsets[bit] +
1437 start * req->sectorsize;
1438 len = (end - start) * req->sectorsize;
1439 if (desc->buffer != NULL)
1440 buf = &desc->buffer[start * req->sectorsize];
1441
1442 switch (req_op(req->req)) {
1443 case REQ_OP_READ:
1444 n = 0;
1445 do {
1446 buf = &buf[n];
1447 len -= n;
1448 n = os_pread_file(req->fds[bit], buf, len, off);
1449 if (n < 0) {
1450 req->error = map_error(-n);
1451 return;
1452 }
1453 } while((n < len) && (n != 0));
1454 if (n < len) memset(&buf[n], 0, len - n);
1455 break;
1456 case REQ_OP_WRITE:
1457 n = os_pwrite_file(req->fds[bit], buf, len, off);
1458 if(n != len){
1459 req->error = map_error(-n);
1460 return;
1461 }
1462 break;
1463 case REQ_OP_DISCARD:
1464 n = os_falloc_punch(req->fds[bit], off, len);
1465 if (n) {
1466 req->error = map_error(-n);
1467 return;
1468 }
1469 break;
1470 case REQ_OP_WRITE_ZEROES:
1471 n = os_falloc_zeroes(req->fds[bit], off, len);
1472 if (n) {
1473 req->error = map_error(-n);
1474 return;
1475 }
1476 break;
1477 default:
1478 WARN_ON_ONCE(1);
1479 req->error = BLK_STS_NOTSUPP;
1480 return;
1481 }
1482
1483 start = end;
1484 } while(start < nsectors);
1485
1486 req->offset += len;
1487 req->error = update_bitmap(req, desc);
1488 }
1489
1490 /* Changed in start_io_thread, which is serialized by being called only
1491 * from ubd_init, which is an initcall.
1492 */
1493 int kernel_fd = -1;
1494
1495 /* Only changed by the io thread. XXX: currently unused. */
1496 static int io_count;
1497
1498 int io_thread(void *arg)
1499 {
1500 int n, count, written, res;
1501
1502 os_fix_helper_signals();
1503
1504 while(1){
1505 n = bulk_req_safe_read(
1506 kernel_fd,
1507 io_req_buffer,
1508 &io_remainder,
1509 &io_remainder_size,
1510 UBD_REQ_BUFFER_SIZE
1511 );
1512 if (n <= 0) {
1513 if (n == -EAGAIN)
1514 ubd_read_poll(-1);
1515
1516 continue;
1517 }
1518
1519 for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
1520 struct io_thread_req *req = (*io_req_buffer)[count];
1521 int i;
1522
1523 io_count++;
1524 for (i = 0; !req->error && i < req->desc_cnt; i++)
1525 do_io(req, &(req->io_desc[i]));
1526
1527 }
1528
1529 written = 0;
1530
1531 do {
1532 res = os_write_file(kernel_fd,
1533 ((char *) io_req_buffer) + written,
1534 n - written);
1535 if (res >= 0) {
1536 written += res;
1537 }
1538 if (written < n) {
1539 ubd_write_poll(-1);
1540 }
1541 } while (written < n);
1542 }
1543
1544 return 0;
1545 }
1546
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