1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * dcssblk.c -- the S/390 block driver for dcss memory
4 *
5 * Authors: Carsten Otte, Stefan Weinhuber, Gerald Schaefer
6 */
7
8 #define KMSG_COMPONENT "dcssblk"
9 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
10
11 #include <linux/module.h>
12 #include <linux/moduleparam.h>
13 #include <linux/ctype.h>
14 #include <linux/errno.h>
15 #include <linux/init.h>
16 #include <linux/slab.h>
17 #include <linux/blkdev.h>
18 #include <linux/completion.h>
19 #include <linux/interrupt.h>
20 #include <linux/pfn_t.h>
21 #include <linux/uio.h>
22 #include <linux/dax.h>
23 #include <linux/io.h>
24 #include <asm/extmem.h>
25
26 #define DCSSBLK_NAME "dcssblk"
27 #define DCSSBLK_MINORS_PER_DISK 1
28 #define DCSSBLK_PARM_LEN 400
29 #define DCSS_BUS_ID_SIZE 20
30
31 static int dcssblk_open(struct gendisk *disk, blk_mode_t mode);
32 static void dcssblk_release(struct gendisk *disk);
33 static void dcssblk_submit_bio(struct bio *bio);
34 static long dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
35 long nr_pages, enum dax_access_mode mode, void **kaddr,
36 pfn_t *pfn);
37
38 static char dcssblk_segments[DCSSBLK_PARM_LEN] = "\0";
39
40 static int dcssblk_major;
41 static const struct block_device_operations dcssblk_devops = {
42 .owner = THIS_MODULE,
43 .submit_bio = dcssblk_submit_bio,
44 .open = dcssblk_open,
45 .release = dcssblk_release,
46 };
47
dcssblk_dax_zero_page_range(struct dax_device * dax_dev,pgoff_t pgoff,size_t nr_pages)48 static int dcssblk_dax_zero_page_range(struct dax_device *dax_dev,
49 pgoff_t pgoff, size_t nr_pages)
50 {
51 long rc;
52 void *kaddr;
53
54 rc = dax_direct_access(dax_dev, pgoff, nr_pages, DAX_ACCESS,
55 &kaddr, NULL);
56 if (rc < 0)
57 return dax_mem2blk_err(rc);
58
59 memset(kaddr, 0, nr_pages << PAGE_SHIFT);
60 dax_flush(dax_dev, kaddr, nr_pages << PAGE_SHIFT);
61 return 0;
62 }
63
64 static const struct dax_operations dcssblk_dax_ops = {
65 .direct_access = dcssblk_dax_direct_access,
66 .zero_page_range = dcssblk_dax_zero_page_range,
67 };
68
69 struct dcssblk_dev_info {
70 struct list_head lh;
71 struct device dev;
72 char segment_name[DCSS_BUS_ID_SIZE];
73 atomic_t use_count;
74 struct gendisk *gd;
75 unsigned long start;
76 unsigned long end;
77 int segment_type;
78 unsigned char save_pending;
79 unsigned char is_shared;
80 int num_of_segments;
81 struct list_head seg_list;
82 struct dax_device *dax_dev;
83 };
84
85 struct segment_info {
86 struct list_head lh;
87 char segment_name[DCSS_BUS_ID_SIZE];
88 unsigned long start;
89 unsigned long end;
90 int segment_type;
91 };
92
93 static ssize_t dcssblk_add_store(struct device * dev, struct device_attribute *attr, const char * buf,
94 size_t count);
95 static ssize_t dcssblk_remove_store(struct device * dev, struct device_attribute *attr, const char * buf,
96 size_t count);
97
98 static DEVICE_ATTR(add, S_IWUSR, NULL, dcssblk_add_store);
99 static DEVICE_ATTR(remove, S_IWUSR, NULL, dcssblk_remove_store);
100
101 static struct device *dcssblk_root_dev;
102
103 static LIST_HEAD(dcssblk_devices);
104 static struct rw_semaphore dcssblk_devices_sem;
105
106 /*
107 * release function for segment device.
108 */
109 static void
dcssblk_release_segment(struct device * dev)110 dcssblk_release_segment(struct device *dev)
111 {
112 struct dcssblk_dev_info *dev_info;
113 struct segment_info *entry, *temp;
114
115 dev_info = container_of(dev, struct dcssblk_dev_info, dev);
116 list_for_each_entry_safe(entry, temp, &dev_info->seg_list, lh) {
117 list_del(&entry->lh);
118 kfree(entry);
119 }
120 kfree(dev_info);
121 module_put(THIS_MODULE);
122 }
123
124 /*
125 * get a minor number. needs to be called with
126 * down_write(&dcssblk_devices_sem) and the
127 * device needs to be enqueued before the semaphore is
128 * freed.
129 */
130 static int
dcssblk_assign_free_minor(struct dcssblk_dev_info * dev_info)131 dcssblk_assign_free_minor(struct dcssblk_dev_info *dev_info)
132 {
133 int minor, found;
134 struct dcssblk_dev_info *entry;
135
136 if (dev_info == NULL)
137 return -EINVAL;
138 for (minor = 0; minor < (1<<MINORBITS); minor++) {
139 found = 0;
140 // test if minor available
141 list_for_each_entry(entry, &dcssblk_devices, lh)
142 if (minor == entry->gd->first_minor)
143 found++;
144 if (!found) break; // got unused minor
145 }
146 if (found)
147 return -EBUSY;
148 dev_info->gd->first_minor = minor;
149 return 0;
150 }
151
152 /*
153 * get the struct dcssblk_dev_info from dcssblk_devices
154 * for the given name.
155 * down_read(&dcssblk_devices_sem) must be held.
156 */
157 static struct dcssblk_dev_info *
dcssblk_get_device_by_name(char * name)158 dcssblk_get_device_by_name(char *name)
159 {
160 struct dcssblk_dev_info *entry;
161
162 list_for_each_entry(entry, &dcssblk_devices, lh) {
163 if (!strcmp(name, entry->segment_name)) {
164 return entry;
165 }
166 }
167 return NULL;
168 }
169
170 /*
171 * get the struct segment_info from seg_list
172 * for the given name.
173 * down_read(&dcssblk_devices_sem) must be held.
174 */
175 static struct segment_info *
dcssblk_get_segment_by_name(char * name)176 dcssblk_get_segment_by_name(char *name)
177 {
178 struct dcssblk_dev_info *dev_info;
179 struct segment_info *entry;
180
181 list_for_each_entry(dev_info, &dcssblk_devices, lh) {
182 list_for_each_entry(entry, &dev_info->seg_list, lh) {
183 if (!strcmp(name, entry->segment_name))
184 return entry;
185 }
186 }
187 return NULL;
188 }
189
190 /*
191 * get the highest address of the multi-segment block.
192 */
193 static unsigned long
dcssblk_find_highest_addr(struct dcssblk_dev_info * dev_info)194 dcssblk_find_highest_addr(struct dcssblk_dev_info *dev_info)
195 {
196 unsigned long highest_addr;
197 struct segment_info *entry;
198
199 highest_addr = 0;
200 list_for_each_entry(entry, &dev_info->seg_list, lh) {
201 if (highest_addr < entry->end)
202 highest_addr = entry->end;
203 }
204 return highest_addr;
205 }
206
207 /*
208 * get the lowest address of the multi-segment block.
209 */
210 static unsigned long
dcssblk_find_lowest_addr(struct dcssblk_dev_info * dev_info)211 dcssblk_find_lowest_addr(struct dcssblk_dev_info *dev_info)
212 {
213 int set_first;
214 unsigned long lowest_addr;
215 struct segment_info *entry;
216
217 set_first = 0;
218 lowest_addr = 0;
219 list_for_each_entry(entry, &dev_info->seg_list, lh) {
220 if (set_first == 0) {
221 lowest_addr = entry->start;
222 set_first = 1;
223 } else {
224 if (lowest_addr > entry->start)
225 lowest_addr = entry->start;
226 }
227 }
228 return lowest_addr;
229 }
230
231 /*
232 * Check continuity of segments.
233 */
234 static int
dcssblk_is_continuous(struct dcssblk_dev_info * dev_info)235 dcssblk_is_continuous(struct dcssblk_dev_info *dev_info)
236 {
237 int i, j, rc;
238 struct segment_info *sort_list, *entry, temp;
239
240 if (dev_info->num_of_segments <= 1)
241 return 0;
242
243 sort_list = kcalloc(dev_info->num_of_segments,
244 sizeof(struct segment_info),
245 GFP_KERNEL);
246 if (sort_list == NULL)
247 return -ENOMEM;
248 i = 0;
249 list_for_each_entry(entry, &dev_info->seg_list, lh) {
250 memcpy(&sort_list[i], entry, sizeof(struct segment_info));
251 i++;
252 }
253
254 /* sort segments */
255 for (i = 0; i < dev_info->num_of_segments; i++)
256 for (j = 0; j < dev_info->num_of_segments; j++)
257 if (sort_list[j].start > sort_list[i].start) {
258 memcpy(&temp, &sort_list[i],
259 sizeof(struct segment_info));
260 memcpy(&sort_list[i], &sort_list[j],
261 sizeof(struct segment_info));
262 memcpy(&sort_list[j], &temp,
263 sizeof(struct segment_info));
264 }
265
266 /* check continuity */
267 for (i = 0; i < dev_info->num_of_segments - 1; i++) {
268 if ((sort_list[i].end + 1) != sort_list[i+1].start) {
269 pr_err("Adjacent DCSSs %s and %s are not "
270 "contiguous\n", sort_list[i].segment_name,
271 sort_list[i+1].segment_name);
272 rc = -EINVAL;
273 goto out;
274 }
275 /* EN and EW are allowed in a block device */
276 if (sort_list[i].segment_type != sort_list[i+1].segment_type) {
277 if (!(sort_list[i].segment_type & SEGMENT_EXCLUSIVE) ||
278 (sort_list[i].segment_type == SEG_TYPE_ER) ||
279 !(sort_list[i+1].segment_type &
280 SEGMENT_EXCLUSIVE) ||
281 (sort_list[i+1].segment_type == SEG_TYPE_ER)) {
282 pr_err("DCSS %s and DCSS %s have "
283 "incompatible types\n",
284 sort_list[i].segment_name,
285 sort_list[i+1].segment_name);
286 rc = -EINVAL;
287 goto out;
288 }
289 }
290 }
291 rc = 0;
292 out:
293 kfree(sort_list);
294 return rc;
295 }
296
297 /*
298 * Load a segment
299 */
300 static int
dcssblk_load_segment(char * name,struct segment_info ** seg_info)301 dcssblk_load_segment(char *name, struct segment_info **seg_info)
302 {
303 int rc;
304
305 /* already loaded? */
306 down_read(&dcssblk_devices_sem);
307 *seg_info = dcssblk_get_segment_by_name(name);
308 up_read(&dcssblk_devices_sem);
309 if (*seg_info != NULL)
310 return -EEXIST;
311
312 /* get a struct segment_info */
313 *seg_info = kzalloc(sizeof(struct segment_info), GFP_KERNEL);
314 if (*seg_info == NULL)
315 return -ENOMEM;
316
317 strcpy((*seg_info)->segment_name, name);
318
319 /* load the segment */
320 rc = segment_load(name, SEGMENT_SHARED,
321 &(*seg_info)->start, &(*seg_info)->end);
322 if (rc < 0) {
323 segment_warning(rc, (*seg_info)->segment_name);
324 kfree(*seg_info);
325 } else {
326 INIT_LIST_HEAD(&(*seg_info)->lh);
327 (*seg_info)->segment_type = rc;
328 }
329 return rc;
330 }
331
332 /*
333 * device attribute for switching shared/nonshared (exclusive)
334 * operation (show + store)
335 */
336 static ssize_t
dcssblk_shared_show(struct device * dev,struct device_attribute * attr,char * buf)337 dcssblk_shared_show(struct device *dev, struct device_attribute *attr, char *buf)
338 {
339 struct dcssblk_dev_info *dev_info;
340
341 dev_info = container_of(dev, struct dcssblk_dev_info, dev);
342 return sprintf(buf, dev_info->is_shared ? "1\n" : "0\n");
343 }
344
345 static ssize_t
dcssblk_shared_store(struct device * dev,struct device_attribute * attr,const char * inbuf,size_t count)346 dcssblk_shared_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
347 {
348 struct dcssblk_dev_info *dev_info;
349 struct segment_info *entry, *temp;
350 int rc;
351
352 if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
353 return -EINVAL;
354 down_write(&dcssblk_devices_sem);
355 dev_info = container_of(dev, struct dcssblk_dev_info, dev);
356 if (atomic_read(&dev_info->use_count)) {
357 rc = -EBUSY;
358 goto out;
359 }
360 if (inbuf[0] == '1') {
361 /* reload segments in shared mode */
362 list_for_each_entry(entry, &dev_info->seg_list, lh) {
363 rc = segment_modify_shared(entry->segment_name,
364 SEGMENT_SHARED);
365 if (rc < 0) {
366 BUG_ON(rc == -EINVAL);
367 if (rc != -EAGAIN)
368 goto removeseg;
369 }
370 }
371 dev_info->is_shared = 1;
372 switch (dev_info->segment_type) {
373 case SEG_TYPE_SR:
374 case SEG_TYPE_ER:
375 case SEG_TYPE_SC:
376 set_disk_ro(dev_info->gd, 1);
377 }
378 } else if (inbuf[0] == '0') {
379 /* reload segments in exclusive mode */
380 if (dev_info->segment_type == SEG_TYPE_SC) {
381 pr_err("DCSS %s is of type SC and cannot be "
382 "loaded as exclusive-writable\n",
383 dev_info->segment_name);
384 rc = -EINVAL;
385 goto out;
386 }
387 list_for_each_entry(entry, &dev_info->seg_list, lh) {
388 rc = segment_modify_shared(entry->segment_name,
389 SEGMENT_EXCLUSIVE);
390 if (rc < 0) {
391 BUG_ON(rc == -EINVAL);
392 if (rc != -EAGAIN)
393 goto removeseg;
394 }
395 }
396 dev_info->is_shared = 0;
397 set_disk_ro(dev_info->gd, 0);
398 } else {
399 rc = -EINVAL;
400 goto out;
401 }
402 rc = count;
403 goto out;
404
405 removeseg:
406 pr_err("DCSS device %s is removed after a failed access mode "
407 "change\n", dev_info->segment_name);
408 temp = entry;
409 list_for_each_entry(entry, &dev_info->seg_list, lh) {
410 if (entry != temp)
411 segment_unload(entry->segment_name);
412 }
413 list_del(&dev_info->lh);
414 up_write(&dcssblk_devices_sem);
415
416 dax_remove_host(dev_info->gd);
417 kill_dax(dev_info->dax_dev);
418 put_dax(dev_info->dax_dev);
419 del_gendisk(dev_info->gd);
420 put_disk(dev_info->gd);
421
422 if (device_remove_file_self(dev, attr)) {
423 device_unregister(dev);
424 put_device(dev);
425 }
426 return rc;
427 out:
428 up_write(&dcssblk_devices_sem);
429 return rc;
430 }
431 static DEVICE_ATTR(shared, S_IWUSR | S_IRUSR, dcssblk_shared_show,
432 dcssblk_shared_store);
433
434 /*
435 * device attribute for save operation on current copy
436 * of the segment. If the segment is busy, saving will
437 * become pending until it gets released, which can be
438 * undone by storing a non-true value to this entry.
439 * (show + store)
440 */
441 static ssize_t
dcssblk_save_show(struct device * dev,struct device_attribute * attr,char * buf)442 dcssblk_save_show(struct device *dev, struct device_attribute *attr, char *buf)
443 {
444 struct dcssblk_dev_info *dev_info;
445
446 dev_info = container_of(dev, struct dcssblk_dev_info, dev);
447 return sprintf(buf, dev_info->save_pending ? "1\n" : "0\n");
448 }
449
450 static ssize_t
dcssblk_save_store(struct device * dev,struct device_attribute * attr,const char * inbuf,size_t count)451 dcssblk_save_store(struct device *dev, struct device_attribute *attr, const char *inbuf, size_t count)
452 {
453 struct dcssblk_dev_info *dev_info;
454 struct segment_info *entry;
455
456 if ((count > 1) && (inbuf[1] != '\n') && (inbuf[1] != '\0'))
457 return -EINVAL;
458 dev_info = container_of(dev, struct dcssblk_dev_info, dev);
459
460 down_write(&dcssblk_devices_sem);
461 if (inbuf[0] == '1') {
462 if (atomic_read(&dev_info->use_count) == 0) {
463 // device is idle => we save immediately
464 pr_info("All DCSSs that map to device %s are "
465 "saved\n", dev_info->segment_name);
466 list_for_each_entry(entry, &dev_info->seg_list, lh) {
467 if (entry->segment_type == SEG_TYPE_EN ||
468 entry->segment_type == SEG_TYPE_SN)
469 pr_warn("DCSS %s is of type SN or EN"
470 " and cannot be saved\n",
471 entry->segment_name);
472 else
473 segment_save(entry->segment_name);
474 }
475 } else {
476 // device is busy => we save it when it becomes
477 // idle in dcssblk_release
478 pr_info("Device %s is in use, its DCSSs will be "
479 "saved when it becomes idle\n",
480 dev_info->segment_name);
481 dev_info->save_pending = 1;
482 }
483 } else if (inbuf[0] == '0') {
484 if (dev_info->save_pending) {
485 // device is busy & the user wants to undo his save
486 // request
487 dev_info->save_pending = 0;
488 pr_info("A pending save request for device %s "
489 "has been canceled\n",
490 dev_info->segment_name);
491 }
492 } else {
493 up_write(&dcssblk_devices_sem);
494 return -EINVAL;
495 }
496 up_write(&dcssblk_devices_sem);
497 return count;
498 }
499 static DEVICE_ATTR(save, S_IWUSR | S_IRUSR, dcssblk_save_show,
500 dcssblk_save_store);
501
502 /*
503 * device attribute for showing all segments in a device
504 */
505 static ssize_t
dcssblk_seglist_show(struct device * dev,struct device_attribute * attr,char * buf)506 dcssblk_seglist_show(struct device *dev, struct device_attribute *attr,
507 char *buf)
508 {
509 int i;
510
511 struct dcssblk_dev_info *dev_info;
512 struct segment_info *entry;
513
514 down_read(&dcssblk_devices_sem);
515 dev_info = container_of(dev, struct dcssblk_dev_info, dev);
516 i = 0;
517 buf[0] = '\0';
518 list_for_each_entry(entry, &dev_info->seg_list, lh) {
519 strcpy(&buf[i], entry->segment_name);
520 i += strlen(entry->segment_name);
521 buf[i] = '\n';
522 i++;
523 }
524 up_read(&dcssblk_devices_sem);
525 return i;
526 }
527 static DEVICE_ATTR(seglist, S_IRUSR, dcssblk_seglist_show, NULL);
528
529 static struct attribute *dcssblk_dev_attrs[] = {
530 &dev_attr_shared.attr,
531 &dev_attr_save.attr,
532 &dev_attr_seglist.attr,
533 NULL,
534 };
535 static struct attribute_group dcssblk_dev_attr_group = {
536 .attrs = dcssblk_dev_attrs,
537 };
538 static const struct attribute_group *dcssblk_dev_attr_groups[] = {
539 &dcssblk_dev_attr_group,
540 NULL,
541 };
542
543 /*
544 * device attribute for adding devices
545 */
546 static ssize_t
dcssblk_add_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)547 dcssblk_add_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
548 {
549 int rc, i, j, num_of_segments;
550 struct dcssblk_dev_info *dev_info;
551 struct segment_info *seg_info, *temp;
552 char *local_buf;
553 unsigned long seg_byte_size;
554
555 dev_info = NULL;
556 seg_info = NULL;
557 if (dev != dcssblk_root_dev) {
558 rc = -EINVAL;
559 goto out_nobuf;
560 }
561 if ((count < 1) || (buf[0] == '\0') || (buf[0] == '\n')) {
562 rc = -ENAMETOOLONG;
563 goto out_nobuf;
564 }
565
566 local_buf = kmalloc(count + 1, GFP_KERNEL);
567 if (local_buf == NULL) {
568 rc = -ENOMEM;
569 goto out_nobuf;
570 }
571
572 /*
573 * parse input
574 */
575 num_of_segments = 0;
576 for (i = 0; (i < count && (buf[i] != '\0') && (buf[i] != '\n')); i++) {
577 for (j = i; j < count &&
578 (buf[j] != ':') &&
579 (buf[j] != '\0') &&
580 (buf[j] != '\n'); j++) {
581 local_buf[j-i] = toupper(buf[j]);
582 }
583 local_buf[j-i] = '\0';
584 if (((j - i) == 0) || ((j - i) > 8)) {
585 rc = -ENAMETOOLONG;
586 goto seg_list_del;
587 }
588
589 rc = dcssblk_load_segment(local_buf, &seg_info);
590 if (rc < 0)
591 goto seg_list_del;
592 /*
593 * get a struct dcssblk_dev_info
594 */
595 if (num_of_segments == 0) {
596 dev_info = kzalloc(sizeof(struct dcssblk_dev_info),
597 GFP_KERNEL);
598 if (dev_info == NULL) {
599 rc = -ENOMEM;
600 goto out;
601 }
602 strcpy(dev_info->segment_name, local_buf);
603 dev_info->segment_type = seg_info->segment_type;
604 INIT_LIST_HEAD(&dev_info->seg_list);
605 }
606 list_add_tail(&seg_info->lh, &dev_info->seg_list);
607 num_of_segments++;
608 i = j;
609
610 if ((buf[j] == '\0') || (buf[j] == '\n'))
611 break;
612 }
613
614 /* no trailing colon at the end of the input */
615 if ((i > 0) && (buf[i-1] == ':')) {
616 rc = -ENAMETOOLONG;
617 goto seg_list_del;
618 }
619 strscpy(local_buf, buf, i + 1);
620 dev_info->num_of_segments = num_of_segments;
621 rc = dcssblk_is_continuous(dev_info);
622 if (rc < 0)
623 goto seg_list_del;
624
625 dev_info->start = dcssblk_find_lowest_addr(dev_info);
626 dev_info->end = dcssblk_find_highest_addr(dev_info);
627
628 dev_set_name(&dev_info->dev, "%s", dev_info->segment_name);
629 dev_info->dev.release = dcssblk_release_segment;
630 dev_info->dev.groups = dcssblk_dev_attr_groups;
631 INIT_LIST_HEAD(&dev_info->lh);
632 dev_info->gd = blk_alloc_disk(NUMA_NO_NODE);
633 if (dev_info->gd == NULL) {
634 rc = -ENOMEM;
635 goto seg_list_del;
636 }
637 dev_info->gd->major = dcssblk_major;
638 dev_info->gd->minors = DCSSBLK_MINORS_PER_DISK;
639 dev_info->gd->fops = &dcssblk_devops;
640 dev_info->gd->private_data = dev_info;
641 dev_info->gd->flags |= GENHD_FL_NO_PART;
642 blk_queue_logical_block_size(dev_info->gd->queue, 4096);
643 blk_queue_flag_set(QUEUE_FLAG_DAX, dev_info->gd->queue);
644
645 seg_byte_size = (dev_info->end - dev_info->start + 1);
646 set_capacity(dev_info->gd, seg_byte_size >> 9); // size in sectors
647 pr_info("Loaded %s with total size %lu bytes and capacity %lu "
648 "sectors\n", local_buf, seg_byte_size, seg_byte_size >> 9);
649
650 dev_info->save_pending = 0;
651 dev_info->is_shared = 1;
652 dev_info->dev.parent = dcssblk_root_dev;
653
654 /*
655 *get minor, add to list
656 */
657 down_write(&dcssblk_devices_sem);
658 if (dcssblk_get_segment_by_name(local_buf)) {
659 rc = -EEXIST;
660 goto release_gd;
661 }
662 rc = dcssblk_assign_free_minor(dev_info);
663 if (rc)
664 goto release_gd;
665 sprintf(dev_info->gd->disk_name, "dcssblk%d",
666 dev_info->gd->first_minor);
667 list_add_tail(&dev_info->lh, &dcssblk_devices);
668
669 if (!try_module_get(THIS_MODULE)) {
670 rc = -ENODEV;
671 goto dev_list_del;
672 }
673 /*
674 * register the device
675 */
676 rc = device_register(&dev_info->dev);
677 if (rc)
678 goto put_dev;
679
680 dev_info->dax_dev = alloc_dax(dev_info, &dcssblk_dax_ops);
681 if (IS_ERR(dev_info->dax_dev)) {
682 rc = PTR_ERR(dev_info->dax_dev);
683 dev_info->dax_dev = NULL;
684 goto put_dev;
685 }
686 set_dax_synchronous(dev_info->dax_dev);
687 rc = dax_add_host(dev_info->dax_dev, dev_info->gd);
688 if (rc)
689 goto out_dax;
690
691 get_device(&dev_info->dev);
692 rc = device_add_disk(&dev_info->dev, dev_info->gd, NULL);
693 if (rc)
694 goto out_dax_host;
695
696 switch (dev_info->segment_type) {
697 case SEG_TYPE_SR:
698 case SEG_TYPE_ER:
699 case SEG_TYPE_SC:
700 set_disk_ro(dev_info->gd,1);
701 break;
702 default:
703 set_disk_ro(dev_info->gd,0);
704 break;
705 }
706 up_write(&dcssblk_devices_sem);
707 rc = count;
708 goto out;
709
710 out_dax_host:
711 put_device(&dev_info->dev);
712 dax_remove_host(dev_info->gd);
713 out_dax:
714 kill_dax(dev_info->dax_dev);
715 put_dax(dev_info->dax_dev);
716 put_dev:
717 list_del(&dev_info->lh);
718 put_disk(dev_info->gd);
719 list_for_each_entry(seg_info, &dev_info->seg_list, lh) {
720 segment_unload(seg_info->segment_name);
721 }
722 put_device(&dev_info->dev);
723 up_write(&dcssblk_devices_sem);
724 goto out;
725 dev_list_del:
726 list_del(&dev_info->lh);
727 release_gd:
728 put_disk(dev_info->gd);
729 up_write(&dcssblk_devices_sem);
730 seg_list_del:
731 if (dev_info == NULL)
732 goto out;
733 list_for_each_entry_safe(seg_info, temp, &dev_info->seg_list, lh) {
734 list_del(&seg_info->lh);
735 segment_unload(seg_info->segment_name);
736 kfree(seg_info);
737 }
738 kfree(dev_info);
739 out:
740 kfree(local_buf);
741 out_nobuf:
742 return rc;
743 }
744
745 /*
746 * device attribute for removing devices
747 */
748 static ssize_t
dcssblk_remove_store(struct device * dev,struct device_attribute * attr,const char * buf,size_t count)749 dcssblk_remove_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t count)
750 {
751 struct dcssblk_dev_info *dev_info;
752 struct segment_info *entry;
753 int rc, i;
754 char *local_buf;
755
756 if (dev != dcssblk_root_dev) {
757 return -EINVAL;
758 }
759 local_buf = kmalloc(count + 1, GFP_KERNEL);
760 if (local_buf == NULL) {
761 return -ENOMEM;
762 }
763 /*
764 * parse input
765 */
766 for (i = 0; (i < count && (*(buf+i)!='\0') && (*(buf+i)!='\n')); i++) {
767 local_buf[i] = toupper(buf[i]);
768 }
769 local_buf[i] = '\0';
770 if ((i == 0) || (i > 8)) {
771 rc = -ENAMETOOLONG;
772 goto out_buf;
773 }
774
775 down_write(&dcssblk_devices_sem);
776 dev_info = dcssblk_get_device_by_name(local_buf);
777 if (dev_info == NULL) {
778 up_write(&dcssblk_devices_sem);
779 pr_warn("Device %s cannot be removed because it is not a known device\n",
780 local_buf);
781 rc = -ENODEV;
782 goto out_buf;
783 }
784 if (atomic_read(&dev_info->use_count) != 0) {
785 up_write(&dcssblk_devices_sem);
786 pr_warn("Device %s cannot be removed while it is in use\n",
787 local_buf);
788 rc = -EBUSY;
789 goto out_buf;
790 }
791
792 list_del(&dev_info->lh);
793 /* unload all related segments */
794 list_for_each_entry(entry, &dev_info->seg_list, lh)
795 segment_unload(entry->segment_name);
796 up_write(&dcssblk_devices_sem);
797
798 dax_remove_host(dev_info->gd);
799 kill_dax(dev_info->dax_dev);
800 put_dax(dev_info->dax_dev);
801 del_gendisk(dev_info->gd);
802 put_disk(dev_info->gd);
803
804 device_unregister(&dev_info->dev);
805 put_device(&dev_info->dev);
806
807 rc = count;
808 out_buf:
809 kfree(local_buf);
810 return rc;
811 }
812
813 static int
dcssblk_open(struct gendisk * disk,blk_mode_t mode)814 dcssblk_open(struct gendisk *disk, blk_mode_t mode)
815 {
816 struct dcssblk_dev_info *dev_info = disk->private_data;
817 int rc;
818
819 if (NULL == dev_info) {
820 rc = -ENODEV;
821 goto out;
822 }
823 atomic_inc(&dev_info->use_count);
824 rc = 0;
825 out:
826 return rc;
827 }
828
829 static void
dcssblk_release(struct gendisk * disk)830 dcssblk_release(struct gendisk *disk)
831 {
832 struct dcssblk_dev_info *dev_info = disk->private_data;
833 struct segment_info *entry;
834
835 if (!dev_info) {
836 WARN_ON(1);
837 return;
838 }
839 down_write(&dcssblk_devices_sem);
840 if (atomic_dec_and_test(&dev_info->use_count)
841 && (dev_info->save_pending)) {
842 pr_info("Device %s has become idle and is being saved "
843 "now\n", dev_info->segment_name);
844 list_for_each_entry(entry, &dev_info->seg_list, lh) {
845 if (entry->segment_type == SEG_TYPE_EN ||
846 entry->segment_type == SEG_TYPE_SN)
847 pr_warn("DCSS %s is of type SN or EN and cannot"
848 " be saved\n", entry->segment_name);
849 else
850 segment_save(entry->segment_name);
851 }
852 dev_info->save_pending = 0;
853 }
854 up_write(&dcssblk_devices_sem);
855 }
856
857 static void
dcssblk_submit_bio(struct bio * bio)858 dcssblk_submit_bio(struct bio *bio)
859 {
860 struct dcssblk_dev_info *dev_info;
861 struct bio_vec bvec;
862 struct bvec_iter iter;
863 unsigned long index;
864 void *page_addr;
865 unsigned long source_addr;
866 unsigned long bytes_done;
867
868 bytes_done = 0;
869 dev_info = bio->bi_bdev->bd_disk->private_data;
870 if (dev_info == NULL)
871 goto fail;
872 if (!IS_ALIGNED(bio->bi_iter.bi_sector, 8) ||
873 !IS_ALIGNED(bio->bi_iter.bi_size, PAGE_SIZE))
874 /* Request is not page-aligned. */
875 goto fail;
876 /* verify data transfer direction */
877 if (dev_info->is_shared) {
878 switch (dev_info->segment_type) {
879 case SEG_TYPE_SR:
880 case SEG_TYPE_ER:
881 case SEG_TYPE_SC:
882 /* cannot write to these segments */
883 if (bio_data_dir(bio) == WRITE) {
884 pr_warn("Writing to %s failed because it is a read-only device\n",
885 dev_name(&dev_info->dev));
886 goto fail;
887 }
888 }
889 }
890
891 index = (bio->bi_iter.bi_sector >> 3);
892 bio_for_each_segment(bvec, bio, iter) {
893 page_addr = bvec_virt(&bvec);
894 source_addr = dev_info->start + (index<<12) + bytes_done;
895 if (unlikely(!IS_ALIGNED((unsigned long)page_addr, PAGE_SIZE) ||
896 !IS_ALIGNED(bvec.bv_len, PAGE_SIZE)))
897 // More paranoia.
898 goto fail;
899 if (bio_data_dir(bio) == READ)
900 memcpy(page_addr, __va(source_addr), bvec.bv_len);
901 else
902 memcpy(__va(source_addr), page_addr, bvec.bv_len);
903 bytes_done += bvec.bv_len;
904 }
905 bio_endio(bio);
906 return;
907 fail:
908 bio_io_error(bio);
909 }
910
911 static long
__dcssblk_direct_access(struct dcssblk_dev_info * dev_info,pgoff_t pgoff,long nr_pages,void ** kaddr,pfn_t * pfn)912 __dcssblk_direct_access(struct dcssblk_dev_info *dev_info, pgoff_t pgoff,
913 long nr_pages, void **kaddr, pfn_t *pfn)
914 {
915 resource_size_t offset = pgoff * PAGE_SIZE;
916 unsigned long dev_sz;
917
918 dev_sz = dev_info->end - dev_info->start + 1;
919 if (kaddr)
920 *kaddr = (void *) dev_info->start + offset;
921 if (pfn)
922 *pfn = __pfn_to_pfn_t(PFN_DOWN(dev_info->start + offset),
923 PFN_DEV|PFN_SPECIAL);
924
925 return (dev_sz - offset) / PAGE_SIZE;
926 }
927
928 static long
dcssblk_dax_direct_access(struct dax_device * dax_dev,pgoff_t pgoff,long nr_pages,enum dax_access_mode mode,void ** kaddr,pfn_t * pfn)929 dcssblk_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
930 long nr_pages, enum dax_access_mode mode, void **kaddr,
931 pfn_t *pfn)
932 {
933 struct dcssblk_dev_info *dev_info = dax_get_private(dax_dev);
934
935 return __dcssblk_direct_access(dev_info, pgoff, nr_pages, kaddr, pfn);
936 }
937
938 static void
dcssblk_check_params(void)939 dcssblk_check_params(void)
940 {
941 int rc, i, j, k;
942 char buf[DCSSBLK_PARM_LEN + 1];
943 struct dcssblk_dev_info *dev_info;
944
945 for (i = 0; (i < DCSSBLK_PARM_LEN) && (dcssblk_segments[i] != '\0');
946 i++) {
947 for (j = i; (j < DCSSBLK_PARM_LEN) &&
948 (dcssblk_segments[j] != ',') &&
949 (dcssblk_segments[j] != '\0') &&
950 (dcssblk_segments[j] != '('); j++)
951 {
952 buf[j-i] = dcssblk_segments[j];
953 }
954 buf[j-i] = '\0';
955 rc = dcssblk_add_store(dcssblk_root_dev, NULL, buf, j-i);
956 if ((rc >= 0) && (dcssblk_segments[j] == '(')) {
957 for (k = 0; (buf[k] != ':') && (buf[k] != '\0'); k++)
958 buf[k] = toupper(buf[k]);
959 buf[k] = '\0';
960 if (!strncmp(&dcssblk_segments[j], "(local)", 7)) {
961 down_read(&dcssblk_devices_sem);
962 dev_info = dcssblk_get_device_by_name(buf);
963 up_read(&dcssblk_devices_sem);
964 if (dev_info)
965 dcssblk_shared_store(&dev_info->dev,
966 NULL, "0\n", 2);
967 }
968 }
969 while ((dcssblk_segments[j] != ',') &&
970 (dcssblk_segments[j] != '\0'))
971 {
972 j++;
973 }
974 if (dcssblk_segments[j] == '\0')
975 break;
976 i = j;
977 }
978 }
979
980 /*
981 * The init/exit functions.
982 */
983 static void __exit
dcssblk_exit(void)984 dcssblk_exit(void)
985 {
986 root_device_unregister(dcssblk_root_dev);
987 unregister_blkdev(dcssblk_major, DCSSBLK_NAME);
988 }
989
990 static int __init
dcssblk_init(void)991 dcssblk_init(void)
992 {
993 int rc;
994
995 dcssblk_root_dev = root_device_register("dcssblk");
996 if (IS_ERR(dcssblk_root_dev))
997 return PTR_ERR(dcssblk_root_dev);
998 rc = device_create_file(dcssblk_root_dev, &dev_attr_add);
999 if (rc)
1000 goto out_root;
1001 rc = device_create_file(dcssblk_root_dev, &dev_attr_remove);
1002 if (rc)
1003 goto out_root;
1004 rc = register_blkdev(0, DCSSBLK_NAME);
1005 if (rc < 0)
1006 goto out_root;
1007 dcssblk_major = rc;
1008 init_rwsem(&dcssblk_devices_sem);
1009
1010 dcssblk_check_params();
1011 return 0;
1012
1013 out_root:
1014 root_device_unregister(dcssblk_root_dev);
1015
1016 return rc;
1017 }
1018
1019 module_init(dcssblk_init);
1020 module_exit(dcssblk_exit);
1021
1022 module_param_string(segments, dcssblk_segments, DCSSBLK_PARM_LEN, 0444);
1023 MODULE_PARM_DESC(segments, "Name of DCSS segment(s) to be loaded, "
1024 "comma-separated list, names in each set separated "
1025 "by commas are separated by colons, each set contains "
1026 "names of contiguous segments and each name max. 8 chars.\n"
1027 "Adding \"(local)\" to the end of each set equals echoing 0 "
1028 "to /sys/devices/dcssblk/<device name>/shared after loading "
1029 "the contiguous segments - \n"
1030 "e.g. segments=\"mydcss1,mydcss2:mydcss3,mydcss4(local)\"");
1031
1032 MODULE_LICENSE("GPL");
1033