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TOMOYO Linux Cross Reference
Linux/arch/um/drivers/ubd_kern.c

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  1 /*
  2  * Copyright (C) 2018 Cambridge Greys Ltd
  3  * Copyright (C) 2015-2016 Anton Ivanov (aivanov@brocade.com)
  4  * Copyright (C) 2000 Jeff Dike (jdike@karaya.com)
  5  * Licensed under the GPL
  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/cdrom.h>
 31 #include <linux/proc_fs.h>
 32 #include <linux/seq_file.h>
 33 #include <linux/ctype.h>
 34 #include <linux/slab.h>
 35 #include <linux/vmalloc.h>
 36 #include <linux/platform_device.h>
 37 #include <linux/scatterlist.h>
 38 #include <asm/tlbflush.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_thread_req {
 51         struct request *req;
 52         int fds[2];
 53         unsigned long offsets[2];
 54         unsigned long long offset;
 55         unsigned long length;
 56         char *buffer;
 57         int sectorsize;
 58         unsigned long sector_mask;
 59         unsigned long long cow_offset;
 60         unsigned long bitmap_words[2];
 61         int error;
 62 };
 63 
 64 
 65 static struct io_thread_req * (*irq_req_buffer)[];
 66 static struct io_thread_req *irq_remainder;
 67 static int irq_remainder_size;
 68 
 69 static struct io_thread_req * (*io_req_buffer)[];
 70 static struct io_thread_req *io_remainder;
 71 static int io_remainder_size;
 72 
 73 
 74 
 75 static inline int ubd_test_bit(__u64 bit, unsigned char *data)
 76 {
 77         __u64 n;
 78         int bits, off;
 79 
 80         bits = sizeof(data[0]) * 8;
 81         n = bit / bits;
 82         off = bit % bits;
 83         return (data[n] & (1 << off)) != 0;
 84 }
 85 
 86 static inline void ubd_set_bit(__u64 bit, unsigned char *data)
 87 {
 88         __u64 n;
 89         int bits, off;
 90 
 91         bits = sizeof(data[0]) * 8;
 92         n = bit / bits;
 93         off = bit % bits;
 94         data[n] |= (1 << off);
 95 }
 96 /*End stuff from ubd_user.h*/
 97 
 98 #define DRIVER_NAME "uml-blkdev"
 99 
100 static DEFINE_MUTEX(ubd_lock);
101 static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
102 
103 static int ubd_open(struct block_device *bdev, fmode_t mode);
104 static void ubd_release(struct gendisk *disk, fmode_t mode);
105 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
106                      unsigned int cmd, unsigned long arg);
107 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
108 
109 #define MAX_DEV (16)
110 
111 static const struct block_device_operations ubd_blops = {
112         .owner          = THIS_MODULE,
113         .open           = ubd_open,
114         .release        = ubd_release,
115         .ioctl          = ubd_ioctl,
116         .getgeo         = ubd_getgeo,
117 };
118 
119 /* Protected by ubd_lock */
120 static int fake_major = UBD_MAJOR;
121 static struct gendisk *ubd_gendisk[MAX_DEV];
122 static struct gendisk *fake_gendisk[MAX_DEV];
123 
124 #ifdef CONFIG_BLK_DEV_UBD_SYNC
125 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 1, .c = 0, \
126                                          .cl = 1 })
127 #else
128 #define OPEN_FLAGS ((struct openflags) { .r = 1, .w = 1, .s = 0, .c = 0, \
129                                          .cl = 1 })
130 #endif
131 static struct openflags global_openflags = OPEN_FLAGS;
132 
133 struct cow {
134         /* backing file name */
135         char *file;
136         /* backing file fd */
137         int fd;
138         unsigned long *bitmap;
139         unsigned long bitmap_len;
140         int bitmap_offset;
141         int data_offset;
142 };
143 
144 #define MAX_SG 64
145 
146 struct ubd {
147         /* name (and fd, below) of the file opened for writing, either the
148          * backing or the cow file. */
149         char *file;
150         int count;
151         int fd;
152         __u64 size;
153         struct openflags boot_openflags;
154         struct openflags openflags;
155         unsigned shared:1;
156         unsigned no_cow:1;
157         unsigned no_trim:1;
158         struct cow cow;
159         struct platform_device pdev;
160         struct request_queue *queue;
161         struct blk_mq_tag_set tag_set;
162         spinlock_t lock;
163 };
164 
165 #define DEFAULT_COW { \
166         .file =                 NULL, \
167         .fd =                   -1,     \
168         .bitmap =               NULL, \
169         .bitmap_offset =        0, \
170         .data_offset =          0, \
171 }
172 
173 #define DEFAULT_UBD { \
174         .file =                 NULL, \
175         .count =                0, \
176         .fd =                   -1, \
177         .size =                 -1, \
178         .boot_openflags =       OPEN_FLAGS, \
179         .openflags =            OPEN_FLAGS, \
180         .no_cow =               0, \
181         .no_trim =              0, \
182         .shared =               0, \
183         .cow =                  DEFAULT_COW, \
184         .lock =                 __SPIN_LOCK_UNLOCKED(ubd_devs.lock), \
185 }
186 
187 /* Protected by ubd_lock */
188 static struct ubd ubd_devs[MAX_DEV] = { [0 ... MAX_DEV - 1] = DEFAULT_UBD };
189 
190 /* Only changed by fake_ide_setup which is a setup */
191 static int fake_ide = 0;
192 static struct proc_dir_entry *proc_ide_root = NULL;
193 static struct proc_dir_entry *proc_ide = NULL;
194 
195 static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
196                                  const struct blk_mq_queue_data *bd);
197 
198 static void make_proc_ide(void)
199 {
200         proc_ide_root = proc_mkdir("ide", NULL);
201         proc_ide = proc_mkdir("ide0", proc_ide_root);
202 }
203 
204 static int fake_ide_media_proc_show(struct seq_file *m, void *v)
205 {
206         seq_puts(m, "disk\n");
207         return 0;
208 }
209 
210 static void make_ide_entries(const char *dev_name)
211 {
212         struct proc_dir_entry *dir, *ent;
213         char name[64];
214 
215         if(proc_ide_root == NULL) make_proc_ide();
216 
217         dir = proc_mkdir(dev_name, proc_ide);
218         if(!dir) return;
219 
220         ent = proc_create_single("media", S_IRUGO, dir,
221                         fake_ide_media_proc_show);
222         if(!ent) return;
223         snprintf(name, sizeof(name), "ide0/%s", dev_name);
224         proc_symlink(dev_name, proc_ide_root, name);
225 }
226 
227 static int fake_ide_setup(char *str)
228 {
229         fake_ide = 1;
230         return 1;
231 }
232 
233 __setup("fake_ide", fake_ide_setup);
234 
235 __uml_help(fake_ide_setup,
236 "fake_ide\n"
237 "    Create ide0 entries that map onto ubd devices.\n\n"
238 );
239 
240 static int parse_unit(char **ptr)
241 {
242         char *str = *ptr, *end;
243         int n = -1;
244 
245         if(isdigit(*str)) {
246                 n = simple_strtoul(str, &end, 0);
247                 if(end == str)
248                         return -1;
249                 *ptr = end;
250         }
251         else if (('a' <= *str) && (*str <= 'z')) {
252                 n = *str - 'a';
253                 str++;
254                 *ptr = str;
255         }
256         return n;
257 }
258 
259 /* If *index_out == -1 at exit, the passed option was a general one;
260  * otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
261  * should not be freed on exit.
262  */
263 static int ubd_setup_common(char *str, int *index_out, char **error_out)
264 {
265         struct ubd *ubd_dev;
266         struct openflags flags = global_openflags;
267         char *backing_file;
268         int n, err = 0, i;
269 
270         if(index_out) *index_out = -1;
271         n = *str;
272         if(n == '='){
273                 char *end;
274                 int major;
275 
276                 str++;
277                 if(!strcmp(str, "sync")){
278                         global_openflags = of_sync(global_openflags);
279                         goto out1;
280                 }
281 
282                 err = -EINVAL;
283                 major = simple_strtoul(str, &end, 0);
284                 if((*end != '\0') || (end == str)){
285                         *error_out = "Didn't parse major number";
286                         goto out1;
287                 }
288 
289                 mutex_lock(&ubd_lock);
290                 if (fake_major != UBD_MAJOR) {
291                         *error_out = "Can't assign a fake major twice";
292                         goto out1;
293                 }
294 
295                 fake_major = major;
296 
297                 printk(KERN_INFO "Setting extra ubd major number to %d\n",
298                        major);
299                 err = 0;
300         out1:
301                 mutex_unlock(&ubd_lock);
302                 return err;
303         }
304 
305         n = parse_unit(&str);
306         if(n < 0){
307                 *error_out = "Couldn't parse device number";
308                 return -EINVAL;
309         }
310         if(n >= MAX_DEV){
311                 *error_out = "Device number out of range";
312                 return 1;
313         }
314 
315         err = -EBUSY;
316         mutex_lock(&ubd_lock);
317 
318         ubd_dev = &ubd_devs[n];
319         if(ubd_dev->file != NULL){
320                 *error_out = "Device is already configured";
321                 goto out;
322         }
323 
324         if (index_out)
325                 *index_out = n;
326 
327         err = -EINVAL;
328         for (i = 0; i < sizeof("rscdt="); i++) {
329                 switch (*str) {
330                 case 'r':
331                         flags.w = 0;
332                         break;
333                 case 's':
334                         flags.s = 1;
335                         break;
336                 case 'd':
337                         ubd_dev->no_cow = 1;
338                         break;
339                 case 'c':
340                         ubd_dev->shared = 1;
341                         break;
342                 case 't':
343                         ubd_dev->no_trim = 1;
344                         break;
345                 case '=':
346                         str++;
347                         goto break_loop;
348                 default:
349                         *error_out = "Expected '=' or flag letter "
350                                 "(r, s, c, t or d)";
351                         goto out;
352                 }
353                 str++;
354         }
355 
356         if (*str == '=')
357                 *error_out = "Too many flags specified";
358         else
359                 *error_out = "Missing '='";
360         goto out;
361 
362 break_loop:
363         backing_file = strchr(str, ',');
364 
365         if (backing_file == NULL)
366                 backing_file = strchr(str, ':');
367 
368         if(backing_file != NULL){
369                 if(ubd_dev->no_cow){
370                         *error_out = "Can't specify both 'd' and a cow file";
371                         goto out;
372                 }
373                 else {
374                         *backing_file = '\0';
375                         backing_file++;
376                 }
377         }
378         err = 0;
379         ubd_dev->file = str;
380         ubd_dev->cow.file = backing_file;
381         ubd_dev->boot_openflags = flags;
382 out:
383         mutex_unlock(&ubd_lock);
384         return err;
385 }
386 
387 static int ubd_setup(char *str)
388 {
389         char *error;
390         int err;
391 
392         err = ubd_setup_common(str, NULL, &error);
393         if(err)
394                 printk(KERN_ERR "Failed to initialize device with \"%s\" : "
395                        "%s\n", str, error);
396         return 1;
397 }
398 
399 __setup("ubd", ubd_setup);
400 __uml_help(ubd_setup,
401 "ubd<n><flags>=<filename>[(:|,)<filename2>]\n"
402 "    This is used to associate a device with a file in the underlying\n"
403 "    filesystem. When specifying two filenames, the first one is the\n"
404 "    COW name and the second is the backing file name. As separator you can\n"
405 "    use either a ':' or a ',': the first one allows writing things like;\n"
406 "       ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
407 "    while with a ',' the shell would not expand the 2nd '~'.\n"
408 "    When using only one filename, UML will detect whether to treat it like\n"
409 "    a COW file or a backing file. To override this detection, add the 'd'\n"
410 "    flag:\n"
411 "       ubd0d=BackingFile\n"
412 "    Usually, there is a filesystem in the file, but \n"
413 "    that's not required. Swap devices containing swap files can be\n"
414 "    specified like this. Also, a file which doesn't contain a\n"
415 "    filesystem can have its contents read in the virtual \n"
416 "    machine by running 'dd' on the device. <n> must be in the range\n"
417 "    0 to 7. Appending an 'r' to the number will cause that device\n"
418 "    to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
419 "    an 's' will cause data to be written to disk on the host immediately.\n"
420 "    'c' will cause the device to be treated as being shared between multiple\n"
421 "    UMLs and file locking will be turned off - this is appropriate for a\n"
422 "    cluster filesystem and inappropriate at almost all other times.\n\n"
423 "    't' will disable trim/discard support on the device (enabled by default).\n\n"
424 );
425 
426 static int udb_setup(char *str)
427 {
428         printk("udb%s specified on command line is almost certainly a ubd -> "
429                "udb TYPO\n", str);
430         return 1;
431 }
432 
433 __setup("udb", udb_setup);
434 __uml_help(udb_setup,
435 "udb\n"
436 "    This option is here solely to catch ubd -> udb typos, which can be\n"
437 "    to impossible to catch visually unless you specifically look for\n"
438 "    them.  The only result of any option starting with 'udb' is an error\n"
439 "    in the boot output.\n\n"
440 );
441 
442 /* Only changed by ubd_init, which is an initcall. */
443 static int thread_fd = -1;
444 
445 /* Function to read several request pointers at a time
446 * handling fractional reads if (and as) needed
447 */
448 
449 static int bulk_req_safe_read(
450         int fd,
451         struct io_thread_req * (*request_buffer)[],
452         struct io_thread_req **remainder,
453         int *remainder_size,
454         int max_recs
455         )
456 {
457         int n = 0;
458         int res = 0;
459 
460         if (*remainder_size > 0) {
461                 memmove(
462                         (char *) request_buffer,
463                         (char *) remainder, *remainder_size
464                 );
465                 n = *remainder_size;
466         }
467 
468         res = os_read_file(
469                         fd,
470                         ((char *) request_buffer) + *remainder_size,
471                         sizeof(struct io_thread_req *)*max_recs
472                                 - *remainder_size
473                 );
474         if (res > 0) {
475                 n += res;
476                 if ((n % sizeof(struct io_thread_req *)) > 0) {
477                         /*
478                         * Read somehow returned not a multiple of dword
479                         * theoretically possible, but never observed in the
480                         * wild, so read routine must be able to handle it
481                         */
482                         *remainder_size = n % sizeof(struct io_thread_req *);
483                         WARN(*remainder_size > 0, "UBD IPC read returned a partial result");
484                         memmove(
485                                 remainder,
486                                 ((char *) request_buffer) +
487                                         (n/sizeof(struct io_thread_req *))*sizeof(struct io_thread_req *),
488                                 *remainder_size
489                         );
490                         n = n - *remainder_size;
491                 }
492         } else {
493                 n = res;
494         }
495         return n;
496 }
497 
498 /* Called without dev->lock held, and only in interrupt context. */
499 static void ubd_handler(void)
500 {
501         int n;
502         int count;
503 
504         while(1){
505                 n = bulk_req_safe_read(
506                         thread_fd,
507                         irq_req_buffer,
508                         &irq_remainder,
509                         &irq_remainder_size,
510                         UBD_REQ_BUFFER_SIZE
511                 );
512                 if (n < 0) {
513                         if(n == -EAGAIN)
514                                 break;
515                         printk(KERN_ERR "spurious interrupt in ubd_handler, "
516                                "err = %d\n", -n);
517                         return;
518                 }
519                 for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
520                         struct io_thread_req *io_req = (*irq_req_buffer)[count];
521 
522                         if ((io_req->error == BLK_STS_NOTSUPP) && (req_op(io_req->req) == REQ_OP_DISCARD)) {
523                                 blk_queue_max_discard_sectors(io_req->req->q, 0);
524                                 blk_queue_max_write_zeroes_sectors(io_req->req->q, 0);
525                                 blk_queue_flag_clear(QUEUE_FLAG_DISCARD, io_req->req->q);
526                         }
527                         if ((io_req->error) || (io_req->buffer == NULL))
528                                 blk_mq_end_request(io_req->req, io_req->error);
529                         else {
530                                 if (!blk_update_request(io_req->req, io_req->error, io_req->length))
531                                         __blk_mq_end_request(io_req->req, io_req->error);
532                         }
533                         kfree(io_req);
534                 }
535         }
536 }
537 
538 static irqreturn_t ubd_intr(int irq, void *dev)
539 {
540         ubd_handler();
541         return IRQ_HANDLED;
542 }
543 
544 /* Only changed by ubd_init, which is an initcall. */
545 static int io_pid = -1;
546 
547 static void kill_io_thread(void)
548 {
549         if(io_pid != -1)
550                 os_kill_process(io_pid, 1);
551 }
552 
553 __uml_exitcall(kill_io_thread);
554 
555 static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
556 {
557         char *file;
558         int fd;
559         int err;
560 
561         __u32 version;
562         __u32 align;
563         char *backing_file;
564         time_t mtime;
565         unsigned long long size;
566         int sector_size;
567         int bitmap_offset;
568 
569         if (ubd_dev->file && ubd_dev->cow.file) {
570                 file = ubd_dev->cow.file;
571 
572                 goto out;
573         }
574 
575         fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
576         if (fd < 0)
577                 return fd;
578 
579         err = read_cow_header(file_reader, &fd, &version, &backing_file, \
580                 &mtime, &size, &sector_size, &align, &bitmap_offset);
581         os_close_file(fd);
582 
583         if(err == -EINVAL)
584                 file = ubd_dev->file;
585         else
586                 file = backing_file;
587 
588 out:
589         return os_file_size(file, size_out);
590 }
591 
592 static int read_cow_bitmap(int fd, void *buf, int offset, int len)
593 {
594         int err;
595 
596         err = os_pread_file(fd, buf, len, offset);
597         if (err < 0)
598                 return err;
599 
600         return 0;
601 }
602 
603 static int backing_file_mismatch(char *file, __u64 size, time_t mtime)
604 {
605         unsigned long modtime;
606         unsigned long long actual;
607         int err;
608 
609         err = os_file_modtime(file, &modtime);
610         if (err < 0) {
611                 printk(KERN_ERR "Failed to get modification time of backing "
612                        "file \"%s\", err = %d\n", file, -err);
613                 return err;
614         }
615 
616         err = os_file_size(file, &actual);
617         if (err < 0) {
618                 printk(KERN_ERR "Failed to get size of backing file \"%s\", "
619                        "err = %d\n", file, -err);
620                 return err;
621         }
622 
623         if (actual != size) {
624                 /*__u64 can be a long on AMD64 and with %lu GCC complains; so
625                  * the typecast.*/
626                 printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
627                        "vs backing file\n", (unsigned long long) size, actual);
628                 return -EINVAL;
629         }
630         if (modtime != mtime) {
631                 printk(KERN_ERR "mtime mismatch (%ld vs %ld) of COW header vs "
632                        "backing file\n", mtime, modtime);
633                 return -EINVAL;
634         }
635         return 0;
636 }
637 
638 static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
639 {
640         struct uml_stat buf1, buf2;
641         int err;
642 
643         if (from_cmdline == NULL)
644                 return 0;
645         if (!strcmp(from_cmdline, from_cow))
646                 return 0;
647 
648         err = os_stat_file(from_cmdline, &buf1);
649         if (err < 0) {
650                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
651                        -err);
652                 return 0;
653         }
654         err = os_stat_file(from_cow, &buf2);
655         if (err < 0) {
656                 printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
657                        -err);
658                 return 1;
659         }
660         if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
661                 return 0;
662 
663         printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
664                "\"%s\" specified in COW header of \"%s\"\n",
665                from_cmdline, from_cow, cow);
666         return 1;
667 }
668 
669 static int open_ubd_file(char *file, struct openflags *openflags, int shared,
670                   char **backing_file_out, int *bitmap_offset_out,
671                   unsigned long *bitmap_len_out, int *data_offset_out,
672                   int *create_cow_out)
673 {
674         time_t mtime;
675         unsigned long long size;
676         __u32 version, align;
677         char *backing_file;
678         int fd, err, sectorsize, asked_switch, mode = 0644;
679 
680         fd = os_open_file(file, *openflags, mode);
681         if (fd < 0) {
682                 if ((fd == -ENOENT) && (create_cow_out != NULL))
683                         *create_cow_out = 1;
684                 if (!openflags->w ||
685                     ((fd != -EROFS) && (fd != -EACCES)))
686                         return fd;
687                 openflags->w = 0;
688                 fd = os_open_file(file, *openflags, mode);
689                 if (fd < 0)
690                         return fd;
691         }
692 
693         if (shared)
694                 printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
695         else {
696                 err = os_lock_file(fd, openflags->w);
697                 if (err < 0) {
698                         printk(KERN_ERR "Failed to lock '%s', err = %d\n",
699                                file, -err);
700                         goto out_close;
701                 }
702         }
703 
704         /* Successful return case! */
705         if (backing_file_out == NULL)
706                 return fd;
707 
708         err = read_cow_header(file_reader, &fd, &version, &backing_file, &mtime,
709                               &size, &sectorsize, &align, bitmap_offset_out);
710         if (err && (*backing_file_out != NULL)) {
711                 printk(KERN_ERR "Failed to read COW header from COW file "
712                        "\"%s\", errno = %d\n", file, -err);
713                 goto out_close;
714         }
715         if (err)
716                 return fd;
717 
718         asked_switch = path_requires_switch(*backing_file_out, backing_file,
719                                             file);
720 
721         /* Allow switching only if no mismatch. */
722         if (asked_switch && !backing_file_mismatch(*backing_file_out, size,
723                                                    mtime)) {
724                 printk(KERN_ERR "Switching backing file to '%s'\n",
725                        *backing_file_out);
726                 err = write_cow_header(file, fd, *backing_file_out,
727                                        sectorsize, align, &size);
728                 if (err) {
729                         printk(KERN_ERR "Switch failed, errno = %d\n", -err);
730                         goto out_close;
731                 }
732         } else {
733                 *backing_file_out = backing_file;
734                 err = backing_file_mismatch(*backing_file_out, size, mtime);
735                 if (err)
736                         goto out_close;
737         }
738 
739         cow_sizes(version, size, sectorsize, align, *bitmap_offset_out,
740                   bitmap_len_out, data_offset_out);
741 
742         return fd;
743  out_close:
744         os_close_file(fd);
745         return err;
746 }
747 
748 static int create_cow_file(char *cow_file, char *backing_file,
749                     struct openflags flags,
750                     int sectorsize, int alignment, int *bitmap_offset_out,
751                     unsigned long *bitmap_len_out, int *data_offset_out)
752 {
753         int err, fd;
754 
755         flags.c = 1;
756         fd = open_ubd_file(cow_file, &flags, 0, NULL, NULL, NULL, NULL, NULL);
757         if (fd < 0) {
758                 err = fd;
759                 printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
760                        cow_file, -err);
761                 goto out;
762         }
763 
764         err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
765                             bitmap_offset_out, bitmap_len_out,
766                             data_offset_out);
767         if (!err)
768                 return fd;
769         os_close_file(fd);
770  out:
771         return err;
772 }
773 
774 static void ubd_close_dev(struct ubd *ubd_dev)
775 {
776         os_close_file(ubd_dev->fd);
777         if(ubd_dev->cow.file == NULL)
778                 return;
779 
780         os_close_file(ubd_dev->cow.fd);
781         vfree(ubd_dev->cow.bitmap);
782         ubd_dev->cow.bitmap = NULL;
783 }
784 
785 static int ubd_open_dev(struct ubd *ubd_dev)
786 {
787         struct openflags flags;
788         char **back_ptr;
789         int err, create_cow, *create_ptr;
790         int fd;
791 
792         ubd_dev->openflags = ubd_dev->boot_openflags;
793         create_cow = 0;
794         create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
795         back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
796 
797         fd = open_ubd_file(ubd_dev->file, &ubd_dev->openflags, ubd_dev->shared,
798                                 back_ptr, &ubd_dev->cow.bitmap_offset,
799                                 &ubd_dev->cow.bitmap_len, &ubd_dev->cow.data_offset,
800                                 create_ptr);
801 
802         if((fd == -ENOENT) && create_cow){
803                 fd = create_cow_file(ubd_dev->file, ubd_dev->cow.file,
804                                           ubd_dev->openflags, SECTOR_SIZE, PAGE_SIZE,
805                                           &ubd_dev->cow.bitmap_offset,
806                                           &ubd_dev->cow.bitmap_len,
807                                           &ubd_dev->cow.data_offset);
808                 if(fd >= 0){
809                         printk(KERN_INFO "Creating \"%s\" as COW file for "
810                                "\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
811                 }
812         }
813 
814         if(fd < 0){
815                 printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
816                        -fd);
817                 return fd;
818         }
819         ubd_dev->fd = fd;
820 
821         if(ubd_dev->cow.file != NULL){
822                 blk_queue_max_hw_sectors(ubd_dev->queue, 8 * sizeof(long));
823 
824                 err = -ENOMEM;
825                 ubd_dev->cow.bitmap = vmalloc(ubd_dev->cow.bitmap_len);
826                 if(ubd_dev->cow.bitmap == NULL){
827                         printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
828                         goto error;
829                 }
830                 flush_tlb_kernel_vm();
831 
832                 err = read_cow_bitmap(ubd_dev->fd, ubd_dev->cow.bitmap,
833                                       ubd_dev->cow.bitmap_offset,
834                                       ubd_dev->cow.bitmap_len);
835                 if(err < 0)
836                         goto error;
837 
838                 flags = ubd_dev->openflags;
839                 flags.w = 0;
840                 err = open_ubd_file(ubd_dev->cow.file, &flags, ubd_dev->shared, NULL,
841                                     NULL, NULL, NULL, NULL);
842                 if(err < 0) goto error;
843                 ubd_dev->cow.fd = err;
844         }
845         if (ubd_dev->no_trim == 0) {
846                 ubd_dev->queue->limits.discard_granularity = SECTOR_SIZE;
847                 ubd_dev->queue->limits.discard_alignment = SECTOR_SIZE;
848                 blk_queue_max_discard_sectors(ubd_dev->queue, UBD_MAX_REQUEST);
849                 blk_queue_max_write_zeroes_sectors(ubd_dev->queue, UBD_MAX_REQUEST);
850                 blk_queue_flag_set(QUEUE_FLAG_DISCARD, ubd_dev->queue);
851         }
852         blk_queue_flag_set(QUEUE_FLAG_NONROT, ubd_dev->queue);
853         return 0;
854  error:
855         os_close_file(ubd_dev->fd);
856         return err;
857 }
858 
859 static void ubd_device_release(struct device *dev)
860 {
861         struct ubd *ubd_dev = dev_get_drvdata(dev);
862 
863         blk_cleanup_queue(ubd_dev->queue);
864         blk_mq_free_tag_set(&ubd_dev->tag_set);
865         *ubd_dev = ((struct ubd) DEFAULT_UBD);
866 }
867 
868 static int ubd_disk_register(int major, u64 size, int unit,
869                              struct gendisk **disk_out)
870 {
871         struct device *parent = NULL;
872         struct gendisk *disk;
873 
874         disk = alloc_disk(1 << UBD_SHIFT);
875         if(disk == NULL)
876                 return -ENOMEM;
877 
878         disk->major = major;
879         disk->first_minor = unit << UBD_SHIFT;
880         disk->fops = &ubd_blops;
881         set_capacity(disk, size / 512);
882         if (major == UBD_MAJOR)
883                 sprintf(disk->disk_name, "ubd%c", 'a' + unit);
884         else
885                 sprintf(disk->disk_name, "ubd_fake%d", unit);
886 
887         /* sysfs register (not for ide fake devices) */
888         if (major == UBD_MAJOR) {
889                 ubd_devs[unit].pdev.id   = unit;
890                 ubd_devs[unit].pdev.name = DRIVER_NAME;
891                 ubd_devs[unit].pdev.dev.release = ubd_device_release;
892                 dev_set_drvdata(&ubd_devs[unit].pdev.dev, &ubd_devs[unit]);
893                 platform_device_register(&ubd_devs[unit].pdev);
894                 parent = &ubd_devs[unit].pdev.dev;
895         }
896 
897         disk->private_data = &ubd_devs[unit];
898         disk->queue = ubd_devs[unit].queue;
899         device_add_disk(parent, disk, NULL);
900 
901         *disk_out = disk;
902         return 0;
903 }
904 
905 #define ROUND_BLOCK(n) ((n + (SECTOR_SIZE - 1)) & (-SECTOR_SIZE))
906 
907 static const struct blk_mq_ops ubd_mq_ops = {
908         .queue_rq = ubd_queue_rq,
909 };
910 
911 static int ubd_add(int n, char **error_out)
912 {
913         struct ubd *ubd_dev = &ubd_devs[n];
914         int err = 0;
915 
916         if(ubd_dev->file == NULL)
917                 goto out;
918 
919         err = ubd_file_size(ubd_dev, &ubd_dev->size);
920         if(err < 0){
921                 *error_out = "Couldn't determine size of device's file";
922                 goto out;
923         }
924 
925         ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
926 
927         ubd_dev->tag_set.ops = &ubd_mq_ops;
928         ubd_dev->tag_set.queue_depth = 64;
929         ubd_dev->tag_set.numa_node = NUMA_NO_NODE;
930         ubd_dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
931         ubd_dev->tag_set.driver_data = ubd_dev;
932         ubd_dev->tag_set.nr_hw_queues = 1;
933 
934         err = blk_mq_alloc_tag_set(&ubd_dev->tag_set);
935         if (err)
936                 goto out;
937 
938         ubd_dev->queue = blk_mq_init_queue(&ubd_dev->tag_set);
939         if (IS_ERR(ubd_dev->queue)) {
940                 err = PTR_ERR(ubd_dev->queue);
941                 goto out_cleanup;
942         }
943 
944         ubd_dev->queue->queuedata = ubd_dev;
945         blk_queue_write_cache(ubd_dev->queue, true, false);
946 
947         blk_queue_max_segments(ubd_dev->queue, MAX_SG);
948         err = ubd_disk_register(UBD_MAJOR, ubd_dev->size, n, &ubd_gendisk[n]);
949         if(err){
950                 *error_out = "Failed to register device";
951                 goto out_cleanup_tags;
952         }
953 
954         if (fake_major != UBD_MAJOR)
955                 ubd_disk_register(fake_major, ubd_dev->size, n,
956                                   &fake_gendisk[n]);
957 
958         /*
959          * Perhaps this should also be under the "if (fake_major)" above
960          * using the fake_disk->disk_name
961          */
962         if (fake_ide)
963                 make_ide_entries(ubd_gendisk[n]->disk_name);
964 
965         err = 0;
966 out:
967         return err;
968 
969 out_cleanup_tags:
970         blk_mq_free_tag_set(&ubd_dev->tag_set);
971 out_cleanup:
972         blk_cleanup_queue(ubd_dev->queue);
973         goto out;
974 }
975 
976 static int ubd_config(char *str, char **error_out)
977 {
978         int n, ret;
979 
980         /* This string is possibly broken up and stored, so it's only
981          * freed if ubd_setup_common fails, or if only general options
982          * were set.
983          */
984         str = kstrdup(str, GFP_KERNEL);
985         if (str == NULL) {
986                 *error_out = "Failed to allocate memory";
987                 return -ENOMEM;
988         }
989 
990         ret = ubd_setup_common(str, &n, error_out);
991         if (ret)
992                 goto err_free;
993 
994         if (n == -1) {
995                 ret = 0;
996                 goto err_free;
997         }
998 
999         mutex_lock(&ubd_lock);
1000         ret = ubd_add(n, error_out);
1001         if (ret)
1002                 ubd_devs[n].file = NULL;
1003         mutex_unlock(&ubd_lock);
1004 
1005 out:
1006         return ret;
1007 
1008 err_free:
1009         kfree(str);
1010         goto out;
1011 }
1012 
1013 static int ubd_get_config(char *name, char *str, int size, char **error_out)
1014 {
1015         struct ubd *ubd_dev;
1016         int n, len = 0;
1017 
1018         n = parse_unit(&name);
1019         if((n >= MAX_DEV) || (n < 0)){
1020                 *error_out = "ubd_get_config : device number out of range";
1021                 return -1;
1022         }
1023 
1024         ubd_dev = &ubd_devs[n];
1025         mutex_lock(&ubd_lock);
1026 
1027         if(ubd_dev->file == NULL){
1028                 CONFIG_CHUNK(str, size, len, "", 1);
1029                 goto out;
1030         }
1031 
1032         CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
1033 
1034         if(ubd_dev->cow.file != NULL){
1035                 CONFIG_CHUNK(str, size, len, ",", 0);
1036                 CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
1037         }
1038         else CONFIG_CHUNK(str, size, len, "", 1);
1039 
1040  out:
1041         mutex_unlock(&ubd_lock);
1042         return len;
1043 }
1044 
1045 static int ubd_id(char **str, int *start_out, int *end_out)
1046 {
1047         int n;
1048 
1049         n = parse_unit(str);
1050         *start_out = 0;
1051         *end_out = MAX_DEV - 1;
1052         return n;
1053 }
1054 
1055 static int ubd_remove(int n, char **error_out)
1056 {
1057         struct gendisk *disk = ubd_gendisk[n];
1058         struct ubd *ubd_dev;
1059         int err = -ENODEV;
1060 
1061         mutex_lock(&ubd_lock);
1062 
1063         ubd_dev = &ubd_devs[n];
1064 
1065         if(ubd_dev->file == NULL)
1066                 goto out;
1067 
1068         /* you cannot remove a open disk */
1069         err = -EBUSY;
1070         if(ubd_dev->count > 0)
1071                 goto out;
1072 
1073         ubd_gendisk[n] = NULL;
1074         if(disk != NULL){
1075                 del_gendisk(disk);
1076                 put_disk(disk);
1077         }
1078 
1079         if(fake_gendisk[n] != NULL){
1080                 del_gendisk(fake_gendisk[n]);
1081                 put_disk(fake_gendisk[n]);
1082                 fake_gendisk[n] = NULL;
1083         }
1084 
1085         err = 0;
1086         platform_device_unregister(&ubd_dev->pdev);
1087 out:
1088         mutex_unlock(&ubd_lock);
1089         return err;
1090 }
1091 
1092 /* All these are called by mconsole in process context and without
1093  * ubd-specific locks.  The structure itself is const except for .list.
1094  */
1095 static struct mc_device ubd_mc = {
1096         .list           = LIST_HEAD_INIT(ubd_mc.list),
1097         .name           = "ubd",
1098         .config         = ubd_config,
1099         .get_config     = ubd_get_config,
1100         .id             = ubd_id,
1101         .remove         = ubd_remove,
1102 };
1103 
1104 static int __init ubd_mc_init(void)
1105 {
1106         mconsole_register_dev(&ubd_mc);
1107         return 0;
1108 }
1109 
1110 __initcall(ubd_mc_init);
1111 
1112 static int __init ubd0_init(void)
1113 {
1114         struct ubd *ubd_dev = &ubd_devs[0];
1115 
1116         mutex_lock(&ubd_lock);
1117         if(ubd_dev->file == NULL)
1118                 ubd_dev->file = "root_fs";
1119         mutex_unlock(&ubd_lock);
1120 
1121         return 0;
1122 }
1123 
1124 __initcall(ubd0_init);
1125 
1126 /* Used in ubd_init, which is an initcall */
1127 static struct platform_driver ubd_driver = {
1128         .driver = {
1129                 .name  = DRIVER_NAME,
1130         },
1131 };
1132 
1133 static int __init ubd_init(void)
1134 {
1135         char *error;
1136         int i, err;
1137 
1138         if (register_blkdev(UBD_MAJOR, "ubd"))
1139                 return -1;
1140 
1141         if (fake_major != UBD_MAJOR) {
1142                 char name[sizeof("ubd_nnn\0")];
1143 
1144                 snprintf(name, sizeof(name), "ubd_%d", fake_major);
1145                 if (register_blkdev(fake_major, "ubd"))
1146                         return -1;
1147         }
1148 
1149         irq_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1150                                        sizeof(struct io_thread_req *),
1151                                        GFP_KERNEL
1152                 );
1153         irq_remainder = 0;
1154 
1155         if (irq_req_buffer == NULL) {
1156                 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1157                 return -1;
1158         }
1159         io_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1160                                       sizeof(struct io_thread_req *),
1161                                       GFP_KERNEL
1162                 );
1163 
1164         io_remainder = 0;
1165 
1166         if (io_req_buffer == NULL) {
1167                 printk(KERN_ERR "Failed to initialize ubd buffering\n");
1168                 return -1;
1169         }
1170         platform_driver_register(&ubd_driver);
1171         mutex_lock(&ubd_lock);
1172         for (i = 0; i < MAX_DEV; i++){
1173                 err = ubd_add(i, &error);
1174                 if(err)
1175                         printk(KERN_ERR "Failed to initialize ubd device %d :"
1176                                "%s\n", i, error);
1177         }
1178         mutex_unlock(&ubd_lock);
1179         return 0;
1180 }
1181 
1182 late_initcall(ubd_init);
1183 
1184 static int __init ubd_driver_init(void){
1185         unsigned long stack;
1186         int err;
1187 
1188         /* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1189         if(global_openflags.s){
1190                 printk(KERN_INFO "ubd: Synchronous mode\n");
1191                 /* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1192                  * enough. So use anyway the io thread. */
1193         }
1194         stack = alloc_stack(0, 0);
1195         io_pid = start_io_thread(stack + PAGE_SIZE - sizeof(void *),
1196                                  &thread_fd);
1197         if(io_pid < 0){
1198                 printk(KERN_ERR
1199                        "ubd : Failed to start I/O thread (errno = %d) - "
1200                        "falling back to synchronous I/O\n", -io_pid);
1201                 io_pid = -1;
1202                 return 0;
1203         }
1204         err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1205                              0, "ubd", ubd_devs);
1206         if(err != 0)
1207                 printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1208         return 0;
1209 }
1210 
1211 device_initcall(ubd_driver_init);
1212 
1213 static int ubd_open(struct block_device *bdev, fmode_t mode)
1214 {
1215         struct gendisk *disk = bdev->bd_disk;
1216         struct ubd *ubd_dev = disk->private_data;
1217         int err = 0;
1218 
1219         mutex_lock(&ubd_mutex);
1220         if(ubd_dev->count == 0){
1221                 err = ubd_open_dev(ubd_dev);
1222                 if(err){
1223                         printk(KERN_ERR "%s: Can't open \"%s\": errno = %d\n",
1224                                disk->disk_name, ubd_dev->file, -err);
1225                         goto out;
1226                 }
1227         }
1228         ubd_dev->count++;
1229         set_disk_ro(disk, !ubd_dev->openflags.w);
1230 
1231         /* This should no more be needed. And it didn't work anyway to exclude
1232          * read-write remounting of filesystems.*/
1233         /*if((mode & FMODE_WRITE) && !ubd_dev->openflags.w){
1234                 if(--ubd_dev->count == 0) ubd_close_dev(ubd_dev);
1235                 err = -EROFS;
1236         }*/
1237 out:
1238         mutex_unlock(&ubd_mutex);
1239         return err;
1240 }
1241 
1242 static void ubd_release(struct gendisk *disk, fmode_t mode)
1243 {
1244         struct ubd *ubd_dev = disk->private_data;
1245 
1246         mutex_lock(&ubd_mutex);
1247         if(--ubd_dev->count == 0)
1248                 ubd_close_dev(ubd_dev);
1249         mutex_unlock(&ubd_mutex);
1250 }
1251 
1252 static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1253                           __u64 *cow_offset, unsigned long *bitmap,
1254                           __u64 bitmap_offset, unsigned long *bitmap_words,
1255                           __u64 bitmap_len)
1256 {
1257         __u64 sector = io_offset >> SECTOR_SHIFT;
1258         int i, update_bitmap = 0;
1259 
1260         for (i = 0; i < length >> SECTOR_SHIFT; i++) {
1261                 if(cow_mask != NULL)
1262                         ubd_set_bit(i, (unsigned char *) cow_mask);
1263                 if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1264                         continue;
1265 
1266                 update_bitmap = 1;
1267                 ubd_set_bit(sector + i, (unsigned char *) bitmap);
1268         }
1269 
1270         if(!update_bitmap)
1271                 return;
1272 
1273         *cow_offset = sector / (sizeof(unsigned long) * 8);
1274 
1275         /* This takes care of the case where we're exactly at the end of the
1276          * device, and *cow_offset + 1 is off the end.  So, just back it up
1277          * by one word.  Thanks to Lynn Kerby for the fix and James McMechan
1278          * for the original diagnosis.
1279          */
1280         if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1281                                          sizeof(unsigned long)) - 1))
1282                 (*cow_offset)--;
1283 
1284         bitmap_words[0] = bitmap[*cow_offset];
1285         bitmap_words[1] = bitmap[*cow_offset + 1];
1286 
1287         *cow_offset *= sizeof(unsigned long);
1288         *cow_offset += bitmap_offset;
1289 }
1290 
1291 static void cowify_req(struct io_thread_req *req, unsigned long *bitmap,
1292                        __u64 bitmap_offset, __u64 bitmap_len)
1293 {
1294         __u64 sector = req->offset >> SECTOR_SHIFT;
1295         int i;
1296 
1297         if (req->length > (sizeof(req->sector_mask) * 8) << SECTOR_SHIFT)
1298                 panic("Operation too long");
1299 
1300         if (req_op(req->req) == REQ_OP_READ) {
1301                 for (i = 0; i < req->length >> SECTOR_SHIFT; i++) {
1302                         if(ubd_test_bit(sector + i, (unsigned char *) bitmap))
1303                                 ubd_set_bit(i, (unsigned char *)
1304                                             &req->sector_mask);
1305                 }
1306         }
1307         else cowify_bitmap(req->offset, req->length, &req->sector_mask,
1308                            &req->cow_offset, bitmap, bitmap_offset,
1309                            req->bitmap_words, bitmap_len);
1310 }
1311 
1312 static int ubd_queue_one_vec(struct blk_mq_hw_ctx *hctx, struct request *req,
1313                 u64 off, struct bio_vec *bvec)
1314 {
1315         struct ubd *dev = hctx->queue->queuedata;
1316         struct io_thread_req *io_req;
1317         int ret;
1318 
1319         io_req = kmalloc(sizeof(struct io_thread_req), GFP_ATOMIC);
1320         if (!io_req)
1321                 return -ENOMEM;
1322 
1323         io_req->req = req;
1324         if (dev->cow.file)
1325                 io_req->fds[0] = dev->cow.fd;
1326         else
1327                 io_req->fds[0] = dev->fd;
1328         io_req->error = 0;
1329 
1330         if (bvec != NULL) {
1331                 io_req->buffer = page_address(bvec->bv_page) + bvec->bv_offset;
1332                 io_req->length = bvec->bv_len;
1333         } else {
1334                 io_req->buffer = NULL;
1335                 io_req->length = blk_rq_bytes(req);
1336         }
1337 
1338         io_req->sectorsize = SECTOR_SIZE;
1339         io_req->fds[1] = dev->fd;
1340         io_req->cow_offset = -1;
1341         io_req->offset = off;
1342         io_req->sector_mask = 0;
1343         io_req->offsets[0] = 0;
1344         io_req->offsets[1] = dev->cow.data_offset;
1345 
1346         if (dev->cow.file)
1347                 cowify_req(io_req, dev->cow.bitmap,
1348                            dev->cow.bitmap_offset, dev->cow.bitmap_len);
1349 
1350         ret = os_write_file(thread_fd, &io_req, sizeof(io_req));
1351         if (ret != sizeof(io_req)) {
1352                 if (ret != -EAGAIN)
1353                         pr_err("write to io thread failed: %d\n", -ret);
1354                 kfree(io_req);
1355         }
1356         return ret;
1357 }
1358 
1359 static int queue_rw_req(struct blk_mq_hw_ctx *hctx, struct request *req)
1360 {
1361         struct req_iterator iter;
1362         struct bio_vec bvec;
1363         int ret;
1364         u64 off = (u64)blk_rq_pos(req) << SECTOR_SHIFT;
1365 
1366         rq_for_each_segment(bvec, req, iter) {
1367                 ret = ubd_queue_one_vec(hctx, req, off, &bvec);
1368                 if (ret < 0)
1369                         return ret;
1370                 off += bvec.bv_len;
1371         }
1372         return 0;
1373 }
1374 
1375 static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
1376                                  const struct blk_mq_queue_data *bd)
1377 {
1378         struct ubd *ubd_dev = hctx->queue->queuedata;
1379         struct request *req = bd->rq;
1380         int ret = 0, res = BLK_STS_OK;
1381 
1382         blk_mq_start_request(req);
1383 
1384         spin_lock_irq(&ubd_dev->lock);
1385 
1386         switch (req_op(req)) {
1387         /* operations with no lentgth/offset arguments */
1388         case REQ_OP_FLUSH:
1389                 ret = ubd_queue_one_vec(hctx, req, 0, NULL);
1390                 break;
1391         case REQ_OP_READ:
1392         case REQ_OP_WRITE:
1393                 ret = queue_rw_req(hctx, req);
1394                 break;
1395         case REQ_OP_DISCARD:
1396         case REQ_OP_WRITE_ZEROES:
1397                 ret = ubd_queue_one_vec(hctx, req, (u64)blk_rq_pos(req) << 9, NULL);
1398                 break;
1399         default:
1400                 WARN_ON_ONCE(1);
1401                 res = BLK_STS_NOTSUPP;
1402         }
1403 
1404         spin_unlock_irq(&ubd_dev->lock);
1405 
1406         if (ret < 0)
1407                 blk_mq_requeue_request(req, true);
1408 
1409         return res;
1410 }
1411 
1412 static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1413 {
1414         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1415 
1416         geo->heads = 128;
1417         geo->sectors = 32;
1418         geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1419         return 0;
1420 }
1421 
1422 static int ubd_ioctl(struct block_device *bdev, fmode_t mode,
1423                      unsigned int cmd, unsigned long arg)
1424 {
1425         struct ubd *ubd_dev = bdev->bd_disk->private_data;
1426         u16 ubd_id[ATA_ID_WORDS];
1427 
1428         switch (cmd) {
1429                 struct cdrom_volctrl volume;
1430         case HDIO_GET_IDENTITY:
1431                 memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1432                 ubd_id[ATA_ID_CYLS]     = ubd_dev->size / (128 * 32 * 512);
1433                 ubd_id[ATA_ID_HEADS]    = 128;
1434                 ubd_id[ATA_ID_SECTORS]  = 32;
1435                 if(copy_to_user((char __user *) arg, (char *) &ubd_id,
1436                                  sizeof(ubd_id)))
1437                         return -EFAULT;
1438                 return 0;
1439 
1440         case CDROMVOLREAD:
1441                 if(copy_from_user(&volume, (char __user *) arg, sizeof(volume)))
1442                         return -EFAULT;
1443                 volume.channel0 = 255;
1444                 volume.channel1 = 255;
1445                 volume.channel2 = 255;
1446                 volume.channel3 = 255;
1447                 if(copy_to_user((char __user *) arg, &volume, sizeof(volume)))
1448                         return -EFAULT;
1449                 return 0;
1450         }
1451         return -EINVAL;
1452 }
1453 
1454 static int map_error(int error_code)
1455 {
1456         switch (error_code) {
1457         case 0:
1458                 return BLK_STS_OK;
1459         case ENOSYS:
1460         case EOPNOTSUPP:
1461                 return BLK_STS_NOTSUPP;
1462         case ENOSPC:
1463                 return BLK_STS_NOSPC;
1464         }
1465         return BLK_STS_IOERR;
1466 }
1467 
1468 /*
1469  * Everything from here onwards *IS NOT PART OF THE KERNEL*
1470  *
1471  * The following functions are part of UML hypervisor code.
1472  * All functions from here onwards are executed as a helper
1473  * thread and are not allowed to execute any kernel functions.
1474  *
1475  * Any communication must occur strictly via shared memory and IPC.
1476  *
1477  * Do not add printks, locks, kernel memory operations, etc - it
1478  * will result in unpredictable behaviour and/or crashes.
1479  */
1480 
1481 static int update_bitmap(struct io_thread_req *req)
1482 {
1483         int n;
1484 
1485         if(req->cow_offset == -1)
1486                 return map_error(0);
1487 
1488         n = os_pwrite_file(req->fds[1], &req->bitmap_words,
1489                           sizeof(req->bitmap_words), req->cow_offset);
1490         if (n != sizeof(req->bitmap_words))
1491                 return map_error(-n);
1492 
1493         return map_error(0);
1494 }
1495 
1496 static void do_io(struct io_thread_req *req)
1497 {
1498         char *buf = NULL;
1499         unsigned long len;
1500         int n, nsectors, start, end, bit;
1501         __u64 off;
1502 
1503         /* FLUSH is really a special case, we cannot "case" it with others */
1504 
1505         if (req_op(req->req) == REQ_OP_FLUSH) {
1506                 /* fds[0] is always either the rw image or our cow file */
1507                 req->error = map_error(-os_sync_file(req->fds[0]));
1508                 return;
1509         }
1510 
1511         nsectors = req->length / req->sectorsize;
1512         start = 0;
1513         do {
1514                 bit = ubd_test_bit(start, (unsigned char *) &req->sector_mask);
1515                 end = start;
1516                 while((end < nsectors) &&
1517                       (ubd_test_bit(end, (unsigned char *)
1518                                     &req->sector_mask) == bit))
1519                         end++;
1520 
1521                 off = req->offset + req->offsets[bit] +
1522                         start * req->sectorsize;
1523                 len = (end - start) * req->sectorsize;
1524                 if (req->buffer != NULL)
1525                         buf = &req->buffer[start * req->sectorsize];
1526 
1527                 switch (req_op(req->req)) {
1528                 case REQ_OP_READ:
1529                         n = 0;
1530                         do {
1531                                 buf = &buf[n];
1532                                 len -= n;
1533                                 n = os_pread_file(req->fds[bit], buf, len, off);
1534                                 if (n < 0) {
1535                                         req->error = map_error(-n);
1536                                         return;
1537                                 }
1538                         } while((n < len) && (n != 0));
1539                         if (n < len) memset(&buf[n], 0, len - n);
1540                         break;
1541                 case REQ_OP_WRITE:
1542                         n = os_pwrite_file(req->fds[bit], buf, len, off);
1543                         if(n != len){
1544                                 req->error = map_error(-n);
1545                                 return;
1546                         }
1547                         break;
1548                 case REQ_OP_DISCARD:
1549                 case REQ_OP_WRITE_ZEROES:
1550                         n = os_falloc_punch(req->fds[bit], off, len);
1551                         if (n) {
1552                                 req->error = map_error(-n);
1553                                 return;
1554                         }
1555                         break;
1556                 default:
1557                         WARN_ON_ONCE(1);
1558                         req->error = BLK_STS_NOTSUPP;
1559                         return;
1560                 }
1561 
1562                 start = end;
1563         } while(start < nsectors);
1564 
1565         req->error = update_bitmap(req);
1566 }
1567 
1568 /* Changed in start_io_thread, which is serialized by being called only
1569  * from ubd_init, which is an initcall.
1570  */
1571 int kernel_fd = -1;
1572 
1573 /* Only changed by the io thread. XXX: currently unused. */
1574 static int io_count = 0;
1575 
1576 int io_thread(void *arg)
1577 {
1578         int n, count, written, res;
1579 
1580         os_fix_helper_signals();
1581 
1582         while(1){
1583                 n = bulk_req_safe_read(
1584                         kernel_fd,
1585                         io_req_buffer,
1586                         &io_remainder,
1587                         &io_remainder_size,
1588                         UBD_REQ_BUFFER_SIZE
1589                 );
1590                 if (n < 0) {
1591                         if (n == -EAGAIN) {
1592                                 ubd_read_poll(-1);
1593                                 continue;
1594                         }
1595                 }
1596 
1597                 for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
1598                         io_count++;
1599                         do_io((*io_req_buffer)[count]);
1600                 }
1601 
1602                 written = 0;
1603 
1604                 do {
1605                         res = os_write_file(kernel_fd, ((char *) io_req_buffer) + written, n);
1606                         if (res >= 0) {
1607                                 written += res;
1608                         }
1609                         if (written < n) {
1610                                 ubd_write_poll(-1);
1611                         }
1612                 } while (written < n);
1613         }
1614 
1615         return 0;
1616 }
1617 

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