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 <asm/tlbflush.h>
40	#include <kern_util.h>
41	#include "mconsole_kern.h"
42	#include <init.h>
43	#include <irq_kern.h>
44	#include "ubd.h"
45	#include <os.h>
46	#include "cow.h"
47
48	/* Max request size is determined by sector mask - 32K */
49	#define UBD_MAX_REQUEST (8 * sizeof(long))
50
51	struct io_desc {
52	char *buffer;
53	unsigned long length;
54	unsigned long sector_mask;
55	unsigned long long cow_offset;
56	unsigned long bitmap_words[2];
57	};
58
59	struct io_thread_req {
60	struct request *req;
61	int fds[2];
62	unsigned long offsets[2];
63	unsigned long long offset;
64	int sectorsize;
65	int error;
66
67	int desc_cnt;
68	/* io_desc has to be the last element of the struct */
69	struct io_desc io_desc[];
70	};
71
72
73	static struct io_thread_req * (*irq_req_buffer)[];
74	static struct io_thread_req *irq_remainder;
75	static int irq_remainder_size;
76
77	static struct io_thread_req * (*io_req_buffer)[];
78	static struct io_thread_req *io_remainder;
79	static int io_remainder_size;
80
81
82
83	static inline int ubd_test_bit(__u64 bit, unsigned char *data)
84	{
85	__u64 n;
86	int bits, off;
87
88	bits = sizeof(data[0]) * 8;
89	n = bit / bits;
90	off = bit % bits;
91	return (data[n] & (1 << off)) != 0;
92	}
93
94	static inline void ubd_set_bit(__u64 bit, unsigned char *data)
95	{
96	__u64 n;
97	int bits, off;
98
99	bits = sizeof(data[0]) * 8;
100	n = bit / bits;
101	off = bit % bits;
102	data[n] |= (1 << off);
103	}
104	/*End stuff from ubd_user.h*/
105
106	#define DRIVER_NAME "uml-blkdev"
107
108	static DEFINE_MUTEX(ubd_lock);
109	static DEFINE_MUTEX(ubd_mutex); /* replaces BKL, might not be needed */
110
111	static int ubd_ioctl(struct block_device *bdev, blk_mode_t mode,
112	unsigned int cmd, unsigned long arg);
113	static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo);
114
115	#define MAX_DEV (16)
116
117	static const struct block_device_operations ubd_blops = {
118	.owner = THIS_MODULE,
119	.ioctl = ubd_ioctl,
120	.compat_ioctl = blkdev_compat_ptr_ioctl,
121	.getgeo = ubd_getgeo,
122	};
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	char *serial;
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 gendisk *disk;
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	.serial = NULL, \
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	static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
191	const struct blk_mq_queue_data *bd);
192
193	static int fake_ide_setup(char *str)
194	{
195	pr_warn("The fake_ide option has been removed\n");
196	return 1;
197	}
198	__setup("fake_ide", fake_ide_setup);
199
200	__uml_help(fake_ide_setup,
201	"fake_ide\n"
202	" Obsolete stub.\n\n"
203	);
204
205	static int parse_unit(char **ptr)
206	{
207	char *str = *ptr, *end;
208	int n = -1;
209
210	if(isdigit(c: *str)) {
211	n = simple_strtoul(str, &end, 0);
212	if(end == str)
213	return -1;
214	*ptr = end;
215	}
216	else if (('a' <= *str) && (*str <= 'z')) {
217	n = *str - 'a';
218	str++;
219	*ptr = str;
220	}
221	return n;
222	}
223
224	/* If *index_out == -1 at exit, the passed option was a general one;
225	* otherwise, the str pointer is used (and owned) inside ubd_devs array, so it
226	* should not be freed on exit.
227	*/
228	static int ubd_setup_common(char *str, int *index_out, char **error_out)
229	{
230	struct ubd *ubd_dev;
231	struct openflags flags = global_openflags;
232	char *file, *backing_file, *serial;
233	int n, err = 0, i;
234
235	if(index_out) *index_out = -1;
236	n = *str;
237	if(n == '='){
238	str++;
239	if(!strcmp(str, "sync")){
240	global_openflags = of_sync(global_openflags);
241	return err;
242	}
243
244	pr_warn("fake major not supported any more\n");
245	return 0;
246	}
247
248	n = parse_unit(ptr: &str);
249	if(n < 0){
250	*error_out = "Couldn't parse device number";
251	return -EINVAL;
252	}
253	if(n >= MAX_DEV){
254	*error_out = "Device number out of range";
255	return 1;
256	}
257
258	err = -EBUSY;
259	mutex_lock(&ubd_lock);
260
261	ubd_dev = &ubd_devs[n];
262	if(ubd_dev->file != NULL){
263	*error_out = "Device is already configured";
264	goto out;
265	}
266
267	if (index_out)
268	*index_out = n;
269
270	err = -EINVAL;
271	for (i = 0; i < sizeof("rscdt="); i++) {
272	switch (*str) {
273	case 'r':
274	flags.w = 0;
275	break;
276	case 's':
277	flags.s = 1;
278	break;
279	case 'd':
280	ubd_dev->no_cow = 1;
281	break;
282	case 'c':
283	ubd_dev->shared = 1;
284	break;
285	case 't':
286	ubd_dev->no_trim = 1;
287	break;
288	case '=':
289	str++;
290	goto break_loop;
291	default:
292	*error_out = "Expected '=' or flag letter "
293	"(r, s, c, t or d)";
294	goto out;
295	}
296	str++;
297	}
298
299	if (*str == '=')
300	*error_out = "Too many flags specified";
301	else
302	*error_out = "Missing '='";
303	goto out;
304
305	break_loop:
306	file = strsep(&str, ",:");
307	if (*file == '\0')
308	file = NULL;
309
310	backing_file = strsep(&str, ",:");
311	if (backing_file && *backing_file == '\0')
312	backing_file = NULL;
313
314	serial = strsep(&str, ",:");
315	if (serial && *serial == '\0')
316	serial = NULL;
317
318	if (backing_file && ubd_dev->no_cow) {
319	*error_out = "Can't specify both 'd' and a cow file";
320	goto out;
321	}
322
323	err = 0;
324	ubd_dev->file = file;
325	ubd_dev->cow.file = backing_file;
326	ubd_dev->serial = serial;
327	ubd_dev->boot_openflags = flags;
328	out:
329	mutex_unlock(lock: &ubd_lock);
330	return err;
331	}
332
333	static int ubd_setup(char *str)
334	{
335	char *error;
336	int err;
337
338	err = ubd_setup_common(str, NULL, error_out: &error);
339	if(err)
340	printk(KERN_ERR "Failed to initialize device with \"%s\" : "
341	"%s\n", str, error);
342	return 1;
343	}
344
345	__setup("ubd", ubd_setup);
346	__uml_help(ubd_setup,
347	"ubd<n><flags>=<filename>[(:|,)<filename2>][(:|,)<serial>]\n"
348	" This is used to associate a device with a file in the underlying\n"
349	" filesystem. When specifying two filenames, the first one is the\n"
350	" COW name and the second is the backing file name. As separator you can\n"
351	" use either a ':' or a ',': the first one allows writing things like;\n"
352	" ubd0=~/Uml/root_cow:~/Uml/root_backing_file\n"
353	" while with a ',' the shell would not expand the 2nd '~'.\n"
354	" When using only one filename, UML will detect whether to treat it like\n"
355	" a COW file or a backing file. To override this detection, add the 'd'\n"
356	" flag:\n"
357	" ubd0d=BackingFile\n"
358	" Usually, there is a filesystem in the file, but \n"
359	" that's not required. Swap devices containing swap files can be\n"
360	" specified like this. Also, a file which doesn't contain a\n"
361	" filesystem can have its contents read in the virtual \n"
362	" machine by running 'dd' on the device. <n> must be in the range\n"
363	" 0 to 7. Appending an 'r' to the number will cause that device\n"
364	" to be mounted read-only. For example ubd1r=./ext_fs. Appending\n"
365	" an 's' will cause data to be written to disk on the host immediately.\n"
366	" 'c' will cause the device to be treated as being shared between multiple\n"
367	" UMLs and file locking will be turned off - this is appropriate for a\n"
368	" cluster filesystem and inappropriate at almost all other times.\n\n"
369	" 't' will disable trim/discard support on the device (enabled by default).\n\n"
370	" An optional device serial number can be exposed using the serial parameter\n"
371	" on the cmdline which is exposed as a sysfs entry. This is particularly\n"
372	" useful when a unique number should be given to the device. Note when\n"
373	" specifying a label, the filename2 must be also presented. It can be\n"
374	" an empty string, in which case the backing file is not used:\n"
375	" ubd0=File,,Serial\n"
376	);
377
378	static int udb_setup(char *str)
379	{
380	printk("udb%s specified on command line is almost certainly a ubd -> "
381	"udb TYPO\n", str);
382	return 1;
383	}
384
385	__setup("udb", udb_setup);
386	__uml_help(udb_setup,
387	"udb\n"
388	" This option is here solely to catch ubd -> udb typos, which can be\n"
389	" to impossible to catch visually unless you specifically look for\n"
390	" them. The only result of any option starting with 'udb' is an error\n"
391	" in the boot output.\n\n"
392	);
393
394	/* Only changed by ubd_init, which is an initcall. */
395	static int thread_fd = -1;
396
397	/* Function to read several request pointers at a time
398	* handling fractional reads if (and as) needed
399	*/
400
401	static int bulk_req_safe_read(
402	int fd,
403	struct io_thread_req * (*request_buffer)[],
404	struct io_thread_req **remainder,
405	int *remainder_size,
406	int max_recs
407	)
408	{
409	int n = 0;
410	int res = 0;
411
412	if (*remainder_size > 0) {
413	memmove(
414	(char *) request_buffer,
415	(char *) remainder, *remainder_size
416	);
417	n = *remainder_size;
418	}
419
420	res = os_read_file(
421	fd,
422	((char *) request_buffer) + *remainder_size,
423	sizeof(struct io_thread_req *)*max_recs
424	- *remainder_size
425	);
426	if (res > 0) {
427	n += res;
428	if ((n % sizeof(struct io_thread_req *)) > 0) {
429	/*
430	* Read somehow returned not a multiple of dword
431	* theoretically possible, but never observed in the
432	* wild, so read routine must be able to handle it
433	*/
434	*remainder_size = n % sizeof(struct io_thread_req *);
435	WARN(*remainder_size > 0, "UBD IPC read returned a partial result");
436	memmove(
437	remainder,
438	((char *) request_buffer) +
439	(n/sizeof(struct io_thread_req *))*sizeof(struct io_thread_req *),
440	*remainder_size
441	);
442	n = n - *remainder_size;
443	}
444	} else {
445	n = res;
446	}
447	return n;
448	}
449
450	/* Called without dev->lock held, and only in interrupt context. */
451	static void ubd_handler(void)
452	{
453	int n;
454	int count;
455
456	while(1){
457	n = bulk_req_safe_read(
458	fd: thread_fd,
459	request_buffer: irq_req_buffer,
460	remainder: &irq_remainder,
461	remainder_size: &irq_remainder_size,
462	UBD_REQ_BUFFER_SIZE
463	);
464	if (n < 0) {
465	if(n == -EAGAIN)
466	break;
467	printk(KERN_ERR "spurious interrupt in ubd_handler, "
468	"err = %d\n", -n);
469	return;
470	}
471	for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
472	struct io_thread_req *io_req = (*irq_req_buffer)[count];
473
474	if ((io_req->error == BLK_STS_NOTSUPP) && (req_op(req: io_req->req) == REQ_OP_DISCARD)) {
475	blk_queue_max_discard_sectors(q: io_req->req->q, max_discard_sectors: 0);
476	blk_queue_max_write_zeroes_sectors(q: io_req->req->q, max_write_same_sectors: 0);
477	}
478	blk_mq_end_request(rq: io_req->req, error: io_req->error);
479	kfree(objp: io_req);
480	}
481	}
482	}
483
484	static irqreturn_t ubd_intr(int irq, void *dev)
485	{
486	ubd_handler();
487	return IRQ_HANDLED;
488	}
489
490	/* Only changed by ubd_init, which is an initcall. */
491	static int io_pid = -1;
492
493	static void kill_io_thread(void)
494	{
495	if(io_pid != -1)
496	os_kill_process(io_pid, 1);
497	}
498
499	__uml_exitcall(kill_io_thread);
500
501	static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)
502	{
503	char *file;
504	int fd;
505	int err;
506
507	__u32 version;
508	__u32 align;
509	char *backing_file;
510	time64_t mtime;
511	unsigned long long size;
512	int sector_size;
513	int bitmap_offset;
514
515	if (ubd_dev->file && ubd_dev->cow.file) {
516	file = ubd_dev->cow.file;
517
518	goto out;
519	}
520
521	fd = os_open_file(ubd_dev->file, of_read(OPENFLAGS()), 0);
522	if (fd < 0)
523	return fd;
524
525	err = read_cow_header(reader: file_reader, arg: &fd, version_out: &version, backing_file_out: &backing_file, \
526	mtime_out: &mtime, size_out: &size, sectorsize_out: &sector_size, align_out: &align, bitmap_offset_out: &bitmap_offset);
527	os_close_file(fd);
528
529	if(err == -EINVAL)
530	file = ubd_dev->file;
531	else
532	file = backing_file;
533
534	out:
535	return os_file_size(file, size_out);
536	}
537
538	static int read_cow_bitmap(int fd, void *buf, int offset, int len)
539	{
540	int err;
541
542	err = os_pread_file(fd, buf, len, offset);
543	if (err < 0)
544	return err;
545
546	return 0;
547	}
548
549	static int backing_file_mismatch(char *file, __u64 size, time64_t mtime)
550	{
551	time64_t modtime;
552	unsigned long long actual;
553	int err;
554
555	err = os_file_modtime(file, &modtime);
556	if (err < 0) {
557	printk(KERN_ERR "Failed to get modification time of backing "
558	"file \"%s\", err = %d\n", file, -err);
559	return err;
560	}
561
562	err = os_file_size(file, &actual);
563	if (err < 0) {
564	printk(KERN_ERR "Failed to get size of backing file \"%s\", "
565	"err = %d\n", file, -err);
566	return err;
567	}
568
569	if (actual != size) {
570	/*__u64 can be a long on AMD64 and with %lu GCC complains; so
571	* the typecast.*/
572	printk(KERN_ERR "Size mismatch (%llu vs %llu) of COW header "
573	"vs backing file\n", (unsigned long long) size, actual);
574	return -EINVAL;
575	}
576	if (modtime != mtime) {
577	printk(KERN_ERR "mtime mismatch (%lld vs %lld) of COW header vs "
578	"backing file\n", mtime, modtime);
579	return -EINVAL;
580	}
581	return 0;
582	}
583
584	static int path_requires_switch(char *from_cmdline, char *from_cow, char *cow)
585	{
586	struct uml_stat buf1, buf2;
587	int err;
588
589	if (from_cmdline == NULL)
590	return 0;
591	if (!strcmp(from_cmdline, from_cow))
592	return 0;
593
594	err = os_stat_file(from_cmdline, &buf1);
595	if (err < 0) {
596	printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cmdline,
597	-err);
598	return 0;
599	}
600	err = os_stat_file(from_cow, &buf2);
601	if (err < 0) {
602	printk(KERN_ERR "Couldn't stat '%s', err = %d\n", from_cow,
603	-err);
604	return 1;
605	}
606	if ((buf1.ust_dev == buf2.ust_dev) && (buf1.ust_ino == buf2.ust_ino))
607	return 0;
608
609	printk(KERN_ERR "Backing file mismatch - \"%s\" requested, "
610	"\"%s\" specified in COW header of \"%s\"\n",
611	from_cmdline, from_cow, cow);
612	return 1;
613	}
614
615	static int open_ubd_file(char *file, struct openflags *openflags, int shared,
616	char **backing_file_out, int *bitmap_offset_out,
617	unsigned long *bitmap_len_out, int *data_offset_out,
618	int *create_cow_out)
619	{
620	time64_t mtime;
621	unsigned long long size;
622	__u32 version, align;
623	char *backing_file;
624	int fd, err, sectorsize, asked_switch, mode = 0644;
625
626	fd = os_open_file(file, *openflags, mode);
627	if (fd < 0) {
628	if ((fd == -ENOENT) && (create_cow_out != NULL))
629	*create_cow_out = 1;
630	if (!openflags->w ||
631	((fd != -EROFS) && (fd != -EACCES)))
632	return fd;
633	openflags->w = 0;
634	fd = os_open_file(file, *openflags, mode);
635	if (fd < 0)
636	return fd;
637	}
638
639	if (shared)
640	printk(KERN_INFO "Not locking \"%s\" on the host\n", file);
641	else {
642	err = os_lock_file(fd, openflags->w);
643	if (err < 0) {
644	printk(KERN_ERR "Failed to lock '%s', err = %d\n",
645	file, -err);
646	goto out_close;
647	}
648	}
649
650	/* Successful return case! */
651	if (backing_file_out == NULL)
652	return fd;
653
654	err = read_cow_header(reader: file_reader, arg: &fd, version_out: &version, backing_file_out: &backing_file, mtime_out: &mtime,
655	size_out: &size, sectorsize_out: &sectorsize, align_out: &align, bitmap_offset_out);
656	if (err && (*backing_file_out != NULL)) {
657	printk(KERN_ERR "Failed to read COW header from COW file "
658	"\"%s\", errno = %d\n", file, -err);
659	goto out_close;
660	}
661	if (err)
662	return fd;
663
664	asked_switch = path_requires_switch(from_cmdline: *backing_file_out, from_cow: backing_file,
665	cow: file);
666
667	/* Allow switching only if no mismatch. */
668	if (asked_switch && !backing_file_mismatch(file: *backing_file_out, size,
669	mtime)) {
670	printk(KERN_ERR "Switching backing file to '%s'\n",
671	*backing_file_out);
672	err = write_cow_header(cow_file: file, fd, backing_file: *backing_file_out,
673	sectorsize, alignment: align, size: &size);
674	if (err) {
675	printk(KERN_ERR "Switch failed, errno = %d\n", -err);
676	goto out_close;
677	}
678	} else {
679	*backing_file_out = backing_file;
680	err = backing_file_mismatch(file: *backing_file_out, size, mtime);
681	if (err)
682	goto out_close;
683	}
684
685	cow_sizes(version, size, sectorsize, align, bitmap_offset: *bitmap_offset_out,
686	bitmap_len_out, data_offset_out);
687
688	return fd;
689	out_close:
690	os_close_file(fd);
691	return err;
692	}
693
694	static int create_cow_file(char *cow_file, char *backing_file,
695	struct openflags flags,
696	int sectorsize, int alignment, int *bitmap_offset_out,
697	unsigned long *bitmap_len_out, int *data_offset_out)
698	{
699	int err, fd;
700
701	flags.c = 1;
702	fd = open_ubd_file(file: cow_file, openflags: &flags, shared: 0, NULL, NULL, NULL, NULL, NULL);
703	if (fd < 0) {
704	err = fd;
705	printk(KERN_ERR "Open of COW file '%s' failed, errno = %d\n",
706	cow_file, -err);
707	goto out;
708	}
709
710	err = init_cow_file(fd, cow_file, backing_file, sectorsize, alignment,
711	bitmap_offset_out, bitmap_len_out,
712	data_offset_out);
713	if (!err)
714	return fd;
715	os_close_file(fd);
716	out:
717	return err;
718	}
719
720	static void ubd_close_dev(struct ubd *ubd_dev)
721	{
722	os_close_file(ubd_dev->fd);
723	if(ubd_dev->cow.file == NULL)
724	return;
725
726	os_close_file(ubd_dev->cow.fd);
727	vfree(addr: ubd_dev->cow.bitmap);
728	ubd_dev->cow.bitmap = NULL;
729	}
730
731	static int ubd_open_dev(struct ubd *ubd_dev)
732	{
733	struct openflags flags;
734	char **back_ptr;
735	int err, create_cow, *create_ptr;
736	int fd;
737
738	ubd_dev->openflags = ubd_dev->boot_openflags;
739	create_cow = 0;
740	create_ptr = (ubd_dev->cow.file != NULL) ? &create_cow : NULL;
741	back_ptr = ubd_dev->no_cow ? NULL : &ubd_dev->cow.file;
742
743	fd = open_ubd_file(file: ubd_dev->file, openflags: &ubd_dev->openflags, shared: ubd_dev->shared,
744	backing_file_out: back_ptr, bitmap_offset_out: &ubd_dev->cow.bitmap_offset,
745	bitmap_len_out: &ubd_dev->cow.bitmap_len, data_offset_out: &ubd_dev->cow.data_offset,
746	create_cow_out: create_ptr);
747
748	if((fd == -ENOENT) && create_cow){
749	fd = create_cow_file(cow_file: ubd_dev->file, backing_file: ubd_dev->cow.file,
750	flags: ubd_dev->openflags, SECTOR_SIZE, PAGE_SIZE,
751	bitmap_offset_out: &ubd_dev->cow.bitmap_offset,
752	bitmap_len_out: &ubd_dev->cow.bitmap_len,
753	data_offset_out: &ubd_dev->cow.data_offset);
754	if(fd >= 0){
755	printk(KERN_INFO "Creating \"%s\" as COW file for "
756	"\"%s\"\n", ubd_dev->file, ubd_dev->cow.file);
757	}
758	}
759
760	if(fd < 0){
761	printk("Failed to open '%s', errno = %d\n", ubd_dev->file,
762	-fd);
763	return fd;
764	}
765	ubd_dev->fd = fd;
766
767	if(ubd_dev->cow.file != NULL){
768	err = -ENOMEM;
769	ubd_dev->cow.bitmap = vmalloc(size: ubd_dev->cow.bitmap_len);
770	if(ubd_dev->cow.bitmap == NULL){
771	printk(KERN_ERR "Failed to vmalloc COW bitmap\n");
772	goto error;
773	}
774	flush_tlb_kernel_vm();
775
776	err = read_cow_bitmap(fd: ubd_dev->fd, buf: ubd_dev->cow.bitmap,
777	offset: ubd_dev->cow.bitmap_offset,
778	len: ubd_dev->cow.bitmap_len);
779	if(err < 0)
780	goto error;
781
782	flags = ubd_dev->openflags;
783	flags.w = 0;
784	err = open_ubd_file(file: ubd_dev->cow.file, openflags: &flags, shared: ubd_dev->shared, NULL,
785	NULL, NULL, NULL, NULL);
786	if(err < 0) goto error;
787	ubd_dev->cow.fd = err;
788	}
789	return 0;
790	error:
791	os_close_file(ubd_dev->fd);
792	return err;
793	}
794
795	static void ubd_device_release(struct device *dev)
796	{
797	struct ubd *ubd_dev = dev_get_drvdata(dev);
798
799	blk_mq_free_tag_set(set: &ubd_dev->tag_set);
800	*ubd_dev = ((struct ubd) DEFAULT_UBD);
801	}
802
803	static ssize_t serial_show(struct device *dev,
804	struct device_attribute *attr, char *buf)
805	{
806	struct gendisk *disk = dev_to_disk(dev);
807	struct ubd *ubd_dev = disk->private_data;
808
809	if (!ubd_dev)
810	return 0;
811
812	return sprintf(buf, fmt: "%s", ubd_dev->serial);
813	}
814
815	static DEVICE_ATTR_RO(serial);
816
817	static struct attribute *ubd_attrs[] = {
818	&dev_attr_serial.attr,
819	NULL,
820	};
821
822	static umode_t ubd_attrs_are_visible(struct kobject *kobj,
823	struct attribute *a, int n)
824	{
825	return a->mode;
826	}
827
828	static const struct attribute_group ubd_attr_group = {
829	.attrs = ubd_attrs,
830	.is_visible = ubd_attrs_are_visible,
831	};
832
833	static const struct attribute_group *ubd_attr_groups[] = {
834	&ubd_attr_group,
835	NULL,
836	};
837
838	#define ROUND_BLOCK(n) ((n + (SECTOR_SIZE - 1)) & (-SECTOR_SIZE))
839
840	static const struct blk_mq_ops ubd_mq_ops = {
841	.queue_rq = ubd_queue_rq,
842	};
843
844	static int ubd_add(int n, char **error_out)
845	{
846	struct ubd *ubd_dev = &ubd_devs[n];
847	struct queue_limits lim = {
848	.max_segments = MAX_SG,
849	.seg_boundary_mask = PAGE_SIZE - 1,
850	};
851	struct gendisk *disk;
852	int err = 0;
853
854	if(ubd_dev->file == NULL)
855	goto out;
856
857	if (ubd_dev->cow.file)
858	lim.max_hw_sectors = 8 * sizeof(long);
859	if (!ubd_dev->no_trim) {
860	lim.max_hw_discard_sectors = UBD_MAX_REQUEST;
861	lim.max_write_zeroes_sectors = UBD_MAX_REQUEST;
862	}
863
864	err = ubd_file_size(ubd_dev, size_out: &ubd_dev->size);
865	if(err < 0){
866	*error_out = "Couldn't determine size of device's file";
867	goto out;
868	}
869
870	err = ubd_open_dev(ubd_dev);
871	if (err) {
872	pr_err("ubd%c: Can't open \"%s\": errno = %d\n",
873	'a' + n, ubd_dev->file, -err);
874	goto out;
875	}
876
877	ubd_dev->size = ROUND_BLOCK(ubd_dev->size);
878
879	ubd_dev->tag_set.ops = &ubd_mq_ops;
880	ubd_dev->tag_set.queue_depth = 64;
881	ubd_dev->tag_set.numa_node = NUMA_NO_NODE;
882	ubd_dev->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
883	ubd_dev->tag_set.driver_data = ubd_dev;
884	ubd_dev->tag_set.nr_hw_queues = 1;
885
886	err = blk_mq_alloc_tag_set(set: &ubd_dev->tag_set);
887	if (err)
888	goto out_close;
889
890	disk = blk_mq_alloc_disk(&ubd_dev->tag_set, &lim, ubd_dev);
891	if (IS_ERR(ptr: disk)) {
892	err = PTR_ERR(ptr: disk);
893	goto out_cleanup_tags;
894	}
895
896	blk_queue_flag_set(QUEUE_FLAG_NONROT, q: disk->queue);
897	blk_queue_write_cache(q: disk->queue, enabled: true, fua: false);
898	disk->major = UBD_MAJOR;
899	disk->first_minor = n << UBD_SHIFT;
900	disk->minors = 1 << UBD_SHIFT;
901	disk->fops = &ubd_blops;
902	set_capacity(disk, size: ubd_dev->size / 512);
903	sprintf(buf: disk->disk_name, fmt: "ubd%c", 'a' + n);
904	disk->private_data = ubd_dev;
905	set_disk_ro(disk, read_only: !ubd_dev->openflags.w);
906
907	ubd_dev->pdev.id = n;
908	ubd_dev->pdev.name = DRIVER_NAME;
909	ubd_dev->pdev.dev.release = ubd_device_release;
910	dev_set_drvdata(dev: &ubd_dev->pdev.dev, data: ubd_dev);
911	platform_device_register(&ubd_dev->pdev);
912
913	err = device_add_disk(parent: &ubd_dev->pdev.dev, disk, groups: ubd_attr_groups);
914	if (err)
915	goto out_cleanup_disk;
916
917	return 0;
918
919	out_cleanup_disk:
920	put_disk(disk);
921	out_cleanup_tags:
922	blk_mq_free_tag_set(set: &ubd_dev->tag_set);
923	out_close:
924	ubd_close_dev(ubd_dev);
925	out:
926	return err;
927	}
928
929	static int ubd_config(char *str, char **error_out)
930	{
931	int n, ret;
932
933	/* This string is possibly broken up and stored, so it's only
934	* freed if ubd_setup_common fails, or if only general options
935	* were set.
936	*/
937	str = kstrdup(s: str, GFP_KERNEL);
938	if (str == NULL) {
939	*error_out = "Failed to allocate memory";
940	return -ENOMEM;
941	}
942
943	ret = ubd_setup_common(str, index_out: &n, error_out);
944	if (ret)
945	goto err_free;
946
947	if (n == -1) {
948	ret = 0;
949	goto err_free;
950	}
951
952	mutex_lock(&ubd_lock);
953	ret = ubd_add(n, error_out);
954	if (ret)
955	ubd_devs[n].file = NULL;
956	mutex_unlock(lock: &ubd_lock);
957
958	out:
959	return ret;
960
961	err_free:
962	kfree(objp: str);
963	goto out;
964	}
965
966	static int ubd_get_config(char *name, char *str, int size, char **error_out)
967	{
968	struct ubd *ubd_dev;
969	int n, len = 0;
970
971	n = parse_unit(ptr: &name);
972	if((n >= MAX_DEV) || (n < 0)){
973	*error_out = "ubd_get_config : device number out of range";
974	return -1;
975	}
976
977	ubd_dev = &ubd_devs[n];
978	mutex_lock(&ubd_lock);
979
980	if(ubd_dev->file == NULL){
981	CONFIG_CHUNK(str, size, len, "", 1);
982	goto out;
983	}
984
985	CONFIG_CHUNK(str, size, len, ubd_dev->file, 0);
986
987	if(ubd_dev->cow.file != NULL){
988	CONFIG_CHUNK(str, size, len, ",", 0);
989	CONFIG_CHUNK(str, size, len, ubd_dev->cow.file, 1);
990	}
991	else CONFIG_CHUNK(str, size, len, "", 1);
992
993	out:
994	mutex_unlock(lock: &ubd_lock);
995	return len;
996	}
997
998	static int ubd_id(char **str, int *start_out, int *end_out)
999	{
1000	int n;
1001
1002	n = parse_unit(ptr: str);
1003	*start_out = 0;
1004	*end_out = MAX_DEV - 1;
1005	return n;
1006	}
1007
1008	static int ubd_remove(int n, char **error_out)
1009	{
1010	struct ubd *ubd_dev;
1011	int err = -ENODEV;
1012
1013	mutex_lock(&ubd_lock);
1014
1015	ubd_dev = &ubd_devs[n];
1016
1017	if(ubd_dev->file == NULL)
1018	goto out;
1019
1020	if (ubd_dev->disk) {
1021	/* you cannot remove a open disk */
1022	err = -EBUSY;
1023	if (disk_openers(disk: ubd_dev->disk))
1024	goto out;
1025
1026	del_gendisk(gp: ubd_dev->disk);
1027	ubd_close_dev(ubd_dev);
1028	put_disk(disk: ubd_dev->disk);
1029	}
1030
1031	err = 0;
1032	platform_device_unregister(&ubd_dev->pdev);
1033	out:
1034	mutex_unlock(lock: &ubd_lock);
1035	return err;
1036	}
1037
1038	/* All these are called by mconsole in process context and without
1039	* ubd-specific locks. The structure itself is const except for .list.
1040	*/
1041	static struct mc_device ubd_mc = {
1042	.list = LIST_HEAD_INIT(ubd_mc.list),
1043	.name = "ubd",
1044	.config = ubd_config,
1045	.get_config = ubd_get_config,
1046	.id = ubd_id,
1047	.remove = ubd_remove,
1048	};
1049
1050	static int __init ubd_mc_init(void)
1051	{
1052	mconsole_register_dev(new: &ubd_mc);
1053	return 0;
1054	}
1055
1056	__initcall(ubd_mc_init);
1057
1058	static int __init ubd0_init(void)
1059	{
1060	struct ubd *ubd_dev = &ubd_devs[0];
1061
1062	mutex_lock(&ubd_lock);
1063	if(ubd_dev->file == NULL)
1064	ubd_dev->file = "root_fs";
1065	mutex_unlock(lock: &ubd_lock);
1066
1067	return 0;
1068	}
1069
1070	__initcall(ubd0_init);
1071
1072	/* Used in ubd_init, which is an initcall */
1073	static struct platform_driver ubd_driver = {
1074	.driver = {
1075	.name = DRIVER_NAME,
1076	},
1077	};
1078
1079	static int __init ubd_init(void)
1080	{
1081	char *error;
1082	int i, err;
1083
1084	if (register_blkdev(UBD_MAJOR, "ubd"))
1085	return -1;
1086
1087	irq_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1088	size: sizeof(struct io_thread_req *),
1089	GFP_KERNEL
1090	);
1091	irq_remainder = 0;
1092
1093	if (irq_req_buffer == NULL) {
1094	printk(KERN_ERR "Failed to initialize ubd buffering\n");
1095	return -1;
1096	}
1097	io_req_buffer = kmalloc_array(UBD_REQ_BUFFER_SIZE,
1098	size: sizeof(struct io_thread_req *),
1099	GFP_KERNEL
1100	);
1101
1102	io_remainder = 0;
1103
1104	if (io_req_buffer == NULL) {
1105	printk(KERN_ERR "Failed to initialize ubd buffering\n");
1106	return -1;
1107	}
1108	platform_driver_register(&ubd_driver);
1109	mutex_lock(&ubd_lock);
1110	for (i = 0; i < MAX_DEV; i++){
1111	err = ubd_add(n: i, error_out: &error);
1112	if(err)
1113	printk(KERN_ERR "Failed to initialize ubd device %d :"
1114	"%s\n", i, error);
1115	}
1116	mutex_unlock(lock: &ubd_lock);
1117	return 0;
1118	}
1119
1120	late_initcall(ubd_init);
1121
1122	static int __init ubd_driver_init(void){
1123	unsigned long stack;
1124	int err;
1125
1126	/* Set by CONFIG_BLK_DEV_UBD_SYNC or ubd=sync.*/
1127	if(global_openflags.s){
1128	printk(KERN_INFO "ubd: Synchronous mode\n");
1129	/* Letting ubd=sync be like using ubd#s= instead of ubd#= is
1130	* enough. So use anyway the io thread. */
1131	}
1132	stack = alloc_stack(0, 0);
1133	io_pid = start_io_thread(sp: stack + PAGE_SIZE, fds_out: &thread_fd);
1134	if(io_pid < 0){
1135	printk(KERN_ERR
1136	"ubd : Failed to start I/O thread (errno = %d) - "
1137	"falling back to synchronous I/O\n", -io_pid);
1138	io_pid = -1;
1139	return 0;
1140	}
1141	err = um_request_irq(UBD_IRQ, thread_fd, IRQ_READ, ubd_intr,
1142	0, "ubd", ubd_devs);
1143	if(err < 0)
1144	printk(KERN_ERR "um_request_irq failed - errno = %d\n", -err);
1145	return 0;
1146	}
1147
1148	device_initcall(ubd_driver_init);
1149
1150	static void cowify_bitmap(__u64 io_offset, int length, unsigned long *cow_mask,
1151	__u64 *cow_offset, unsigned long *bitmap,
1152	__u64 bitmap_offset, unsigned long *bitmap_words,
1153	__u64 bitmap_len)
1154	{
1155	__u64 sector = io_offset >> SECTOR_SHIFT;
1156	int i, update_bitmap = 0;
1157
1158	for (i = 0; i < length >> SECTOR_SHIFT; i++) {
1159	if(cow_mask != NULL)
1160	ubd_set_bit(bit: i, data: (unsigned char *) cow_mask);
1161	if(ubd_test_bit(bit: sector + i, data: (unsigned char *) bitmap))
1162	continue;
1163
1164	update_bitmap = 1;
1165	ubd_set_bit(bit: sector + i, data: (unsigned char *) bitmap);
1166	}
1167
1168	if(!update_bitmap)
1169	return;
1170
1171	*cow_offset = sector / (sizeof(unsigned long) * 8);
1172
1173	/* This takes care of the case where we're exactly at the end of the
1174	* device, and *cow_offset + 1 is off the end. So, just back it up
1175	* by one word. Thanks to Lynn Kerby for the fix and James McMechan
1176	* for the original diagnosis.
1177	*/
1178	if (*cow_offset == (DIV_ROUND_UP(bitmap_len,
1179	sizeof(unsigned long)) - 1))
1180	(*cow_offset)--;
1181
1182	bitmap_words[0] = bitmap[*cow_offset];
1183	bitmap_words[1] = bitmap[*cow_offset + 1];
1184
1185	*cow_offset *= sizeof(unsigned long);
1186	*cow_offset += bitmap_offset;
1187	}
1188
1189	static void cowify_req(struct io_thread_req *req, struct io_desc *segment,
1190	unsigned long offset, unsigned long *bitmap,
1191	__u64 bitmap_offset, __u64 bitmap_len)
1192	{
1193	__u64 sector = offset >> SECTOR_SHIFT;
1194	int i;
1195
1196	if (segment->length > (sizeof(segment->sector_mask) * 8) << SECTOR_SHIFT)
1197	panic(fmt: "Operation too long");
1198
1199	if (req_op(req: req->req) == REQ_OP_READ) {
1200	for (i = 0; i < segment->length >> SECTOR_SHIFT; i++) {
1201	if(ubd_test_bit(bit: sector + i, data: (unsigned char *) bitmap))
1202	ubd_set_bit(bit: i, data: (unsigned char *)
1203	&segment->sector_mask);
1204	}
1205	} else {
1206	cowify_bitmap(io_offset: offset, length: segment->length, cow_mask: &segment->sector_mask,
1207	cow_offset: &segment->cow_offset, bitmap, bitmap_offset,
1208	bitmap_words: segment->bitmap_words, bitmap_len);
1209	}
1210	}
1211
1212	static void ubd_map_req(struct ubd *dev, struct io_thread_req *io_req,
1213	struct request *req)
1214	{
1215	struct bio_vec bvec;
1216	struct req_iterator iter;
1217	int i = 0;
1218	unsigned long byte_offset = io_req->offset;
1219	enum req_op op = req_op(req);
1220
1221	if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD) {
1222	io_req->io_desc[0].buffer = NULL;
1223	io_req->io_desc[0].length = blk_rq_bytes(rq: req);
1224	} else {
1225	rq_for_each_segment(bvec, req, iter) {
1226	BUG_ON(i >= io_req->desc_cnt);
1227
1228	io_req->io_desc[i].buffer = bvec_virt(bvec: &bvec);
1229	io_req->io_desc[i].length = bvec.bv_len;
1230	i++;
1231	}
1232	}
1233
1234	if (dev->cow.file) {
1235	for (i = 0; i < io_req->desc_cnt; i++) {
1236	cowify_req(req: io_req, segment: &io_req->io_desc[i], offset: byte_offset,
1237	bitmap: dev->cow.bitmap, bitmap_offset: dev->cow.bitmap_offset,
1238	bitmap_len: dev->cow.bitmap_len);
1239	byte_offset += io_req->io_desc[i].length;
1240	}
1241
1242	}
1243	}
1244
1245	static struct io_thread_req *ubd_alloc_req(struct ubd *dev, struct request *req,
1246	int desc_cnt)
1247	{
1248	struct io_thread_req *io_req;
1249	int i;
1250
1251	io_req = kmalloc(size: sizeof(*io_req) +
1252	(desc_cnt * sizeof(struct io_desc)),
1253	GFP_ATOMIC);
1254	if (!io_req)
1255	return NULL;
1256
1257	io_req->req = req;
1258	if (dev->cow.file)
1259	io_req->fds[0] = dev->cow.fd;
1260	else
1261	io_req->fds[0] = dev->fd;
1262	io_req->error = 0;
1263	io_req->sectorsize = SECTOR_SIZE;
1264	io_req->fds[1] = dev->fd;
1265	io_req->offset = (u64) blk_rq_pos(rq: req) << SECTOR_SHIFT;
1266	io_req->offsets[0] = 0;
1267	io_req->offsets[1] = dev->cow.data_offset;
1268
1269	for (i = 0 ; i < desc_cnt; i++) {
1270	io_req->io_desc[i].sector_mask = 0;
1271	io_req->io_desc[i].cow_offset = -1;
1272	}
1273
1274	return io_req;
1275	}
1276
1277	static int ubd_submit_request(struct ubd *dev, struct request *req)
1278	{
1279	int segs = 0;
1280	struct io_thread_req *io_req;
1281	int ret;
1282	enum req_op op = req_op(req);
1283
1284	if (op == REQ_OP_FLUSH)
1285	segs = 0;
1286	else if (op == REQ_OP_WRITE_ZEROES || op == REQ_OP_DISCARD)
1287	segs = 1;
1288	else
1289	segs = blk_rq_nr_phys_segments(rq: req);
1290
1291	io_req = ubd_alloc_req(dev, req, desc_cnt: segs);
1292	if (!io_req)
1293	return -ENOMEM;
1294
1295	io_req->desc_cnt = segs;
1296	if (segs)
1297	ubd_map_req(dev, io_req, req);
1298
1299	ret = os_write_file(thread_fd, &io_req, sizeof(io_req));
1300	if (ret != sizeof(io_req)) {
1301	if (ret != -EAGAIN)
1302	pr_err("write to io thread failed: %d\n", -ret);
1303	kfree(objp: io_req);
1304	}
1305	return ret;
1306	}
1307
1308	static blk_status_t ubd_queue_rq(struct blk_mq_hw_ctx *hctx,
1309	const struct blk_mq_queue_data *bd)
1310	{
1311	struct ubd *ubd_dev = hctx->queue->queuedata;
1312	struct request *req = bd->rq;
1313	int ret = 0, res = BLK_STS_OK;
1314
1315	blk_mq_start_request(rq: req);
1316
1317	spin_lock_irq(lock: &ubd_dev->lock);
1318
1319	switch (req_op(req)) {
1320	case REQ_OP_FLUSH:
1321	case REQ_OP_READ:
1322	case REQ_OP_WRITE:
1323	case REQ_OP_DISCARD:
1324	case REQ_OP_WRITE_ZEROES:
1325	ret = ubd_submit_request(dev: ubd_dev, req);
1326	break;
1327	default:
1328	WARN_ON_ONCE(1);
1329	res = BLK_STS_NOTSUPP;
1330	}
1331
1332	spin_unlock_irq(lock: &ubd_dev->lock);
1333
1334	if (ret < 0) {
1335	if (ret == -ENOMEM)
1336	res = BLK_STS_RESOURCE;
1337	else
1338	res = BLK_STS_DEV_RESOURCE;
1339	}
1340
1341	return res;
1342	}
1343
1344	static int ubd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
1345	{
1346	struct ubd *ubd_dev = bdev->bd_disk->private_data;
1347
1348	geo->heads = 128;
1349	geo->sectors = 32;
1350	geo->cylinders = ubd_dev->size / (128 * 32 * 512);
1351	return 0;
1352	}
1353
1354	static int ubd_ioctl(struct block_device *bdev, blk_mode_t mode,
1355	unsigned int cmd, unsigned long arg)
1356	{
1357	struct ubd *ubd_dev = bdev->bd_disk->private_data;
1358	u16 ubd_id[ATA_ID_WORDS];
1359
1360	switch (cmd) {
1361	struct cdrom_volctrl volume;
1362	case HDIO_GET_IDENTITY:
1363	memset(&ubd_id, 0, ATA_ID_WORDS * 2);
1364	ubd_id[ATA_ID_CYLS] = ubd_dev->size / (128 * 32 * 512);
1365	ubd_id[ATA_ID_HEADS] = 128;
1366	ubd_id[ATA_ID_SECTORS] = 32;
1367	if(copy_to_user(to: (char __user *) arg, from: (char *) &ubd_id,
1368	n: sizeof(ubd_id)))
1369	return -EFAULT;
1370	return 0;
1371
1372	case CDROMVOLREAD:
1373	if(copy_from_user(to: &volume, from: (char __user *) arg, n: sizeof(volume)))
1374	return -EFAULT;
1375	volume.channel0 = 255;
1376	volume.channel1 = 255;
1377	volume.channel2 = 255;
1378	volume.channel3 = 255;
1379	if(copy_to_user(to: (char __user *) arg, from: &volume, n: sizeof(volume)))
1380	return -EFAULT;
1381	return 0;
1382	}
1383	return -EINVAL;
1384	}
1385
1386	static int map_error(int error_code)
1387	{
1388	switch (error_code) {
1389	case 0:
1390	return BLK_STS_OK;
1391	case ENOSYS:
1392	case EOPNOTSUPP:
1393	return BLK_STS_NOTSUPP;
1394	case ENOSPC:
1395	return BLK_STS_NOSPC;
1396	}
1397	return BLK_STS_IOERR;
1398	}
1399
1400	/*
1401	* Everything from here onwards *IS NOT PART OF THE KERNEL*
1402	*
1403	* The following functions are part of UML hypervisor code.
1404	* All functions from here onwards are executed as a helper
1405	* thread and are not allowed to execute any kernel functions.
1406	*
1407	* Any communication must occur strictly via shared memory and IPC.
1408	*
1409	* Do not add printks, locks, kernel memory operations, etc - it
1410	* will result in unpredictable behaviour and/or crashes.
1411	*/
1412
1413	static int update_bitmap(struct io_thread_req *req, struct io_desc *segment)
1414	{
1415	int n;
1416
1417	if (segment->cow_offset == -1)
1418	return map_error(error_code: 0);
1419
1420	n = os_pwrite_file(req->fds[1], &segment->bitmap_words,
1421	sizeof(segment->bitmap_words), segment->cow_offset);
1422	if (n != sizeof(segment->bitmap_words))
1423	return map_error(error_code: -n);
1424
1425	return map_error(error_code: 0);
1426	}
1427
1428	static void do_io(struct io_thread_req *req, struct io_desc *desc)
1429	{
1430	char *buf = NULL;
1431	unsigned long len;
1432	int n, nsectors, start, end, bit;
1433	__u64 off;
1434
1435	/* FLUSH is really a special case, we cannot "case" it with others */
1436
1437	if (req_op(req: req->req) == REQ_OP_FLUSH) {
1438	/* fds[0] is always either the rw image or our cow file */
1439	req->error = map_error(error_code: -os_sync_file(req->fds[0]));
1440	return;
1441	}
1442
1443	nsectors = desc->length / req->sectorsize;
1444	start = 0;
1445	do {
1446	bit = ubd_test_bit(bit: start, data: (unsigned char *) &desc->sector_mask);
1447	end = start;
1448	while((end < nsectors) &&
1449	(ubd_test_bit(bit: end, data: (unsigned char *) &desc->sector_mask) == bit))
1450	end++;
1451
1452	off = req->offset + req->offsets[bit] +
1453	start * req->sectorsize;
1454	len = (end - start) * req->sectorsize;
1455	if (desc->buffer != NULL)
1456	buf = &desc->buffer[start * req->sectorsize];
1457
1458	switch (req_op(req: req->req)) {
1459	case REQ_OP_READ:
1460	n = 0;
1461	do {
1462	buf = &buf[n];
1463	len -= n;
1464	n = os_pread_file(req->fds[bit], buf, len, off);
1465	if (n < 0) {
1466	req->error = map_error(error_code: -n);
1467	return;
1468	}
1469	} while((n < len) && (n != 0));
1470	if (n < len) memset(&buf[n], 0, len - n);
1471	break;
1472	case REQ_OP_WRITE:
1473	n = os_pwrite_file(req->fds[bit], buf, len, off);
1474	if(n != len){
1475	req->error = map_error(error_code: -n);
1476	return;
1477	}
1478	break;
1479	case REQ_OP_DISCARD:
1480	n = os_falloc_punch(req->fds[bit], off, len);
1481	if (n) {
1482	req->error = map_error(error_code: -n);
1483	return;
1484	}
1485	break;
1486	case REQ_OP_WRITE_ZEROES:
1487	n = os_falloc_zeroes(req->fds[bit], off, len);
1488	if (n) {
1489	req->error = map_error(error_code: -n);
1490	return;
1491	}
1492	break;
1493	default:
1494	WARN_ON_ONCE(1);
1495	req->error = BLK_STS_NOTSUPP;
1496	return;
1497	}
1498
1499	start = end;
1500	} while(start < nsectors);
1501
1502	req->offset += len;
1503	req->error = update_bitmap(req, segment: desc);
1504	}
1505
1506	/* Changed in start_io_thread, which is serialized by being called only
1507	* from ubd_init, which is an initcall.
1508	*/
1509	int kernel_fd = -1;
1510
1511	/* Only changed by the io thread. XXX: currently unused. */
1512	static int io_count;
1513
1514	int io_thread(void *arg)
1515	{
1516	int n, count, written, res;
1517
1518	os_fix_helper_signals();
1519
1520	while(1){
1521	n = bulk_req_safe_read(
1522	fd: kernel_fd,
1523	request_buffer: io_req_buffer,
1524	remainder: &io_remainder,
1525	remainder_size: &io_remainder_size,
1526	UBD_REQ_BUFFER_SIZE
1527	);
1528	if (n <= 0) {
1529	if (n == -EAGAIN)
1530	ubd_read_poll(timeout: -1);
1531
1532	continue;
1533	}
1534
1535	for (count = 0; count < n/sizeof(struct io_thread_req *); count++) {
1536	struct io_thread_req *req = (*io_req_buffer)[count];
1537	int i;
1538
1539	io_count++;
1540	for (i = 0; !req->error && i < req->desc_cnt; i++)
1541	do_io(req, desc: &(req->io_desc[i]));
1542
1543	}
1544
1545	written = 0;
1546
1547	do {
1548	res = os_write_file(kernel_fd,
1549	((char *) io_req_buffer) + written,
1550	n - written);
1551	if (res >= 0) {
1552	written += res;
1553	}
1554	if (written < n) {
1555	ubd_write_poll(timeout: -1);
1556	}
1557	} while (written < n);
1558	}
1559
1560	return 0;
1561	}
1562