1/*
2 * Copyright (C) 2001-2003 Sistina Software (UK) Limited.
3 *
4 * This file is released under the GPL.
5 */
6
7#include "dm.h"
8#include <linux/device-mapper.h>
9
10#include <linux/module.h>
11#include <linux/init.h>
12#include <linux/blkdev.h>
13#include <linux/bio.h>
14#include <linux/dax.h>
15#include <linux/slab.h>
16#include <linux/log2.h>
17
18#define DM_MSG_PREFIX "striped"
19#define DM_IO_ERROR_THRESHOLD 15
20
21struct stripe {
22 struct dm_dev *dev;
23 sector_t physical_start;
24
25 atomic_t error_count;
26};
27
28struct stripe_c {
29 uint32_t stripes;
30 int stripes_shift;
31
32 /* The size of this target / num. stripes */
33 sector_t stripe_width;
34
35 uint32_t chunk_size;
36 int chunk_size_shift;
37
38 /* Needed for handling events */
39 struct dm_target *ti;
40
41 /* Work struct used for triggering events*/
42 struct work_struct trigger_event;
43
44 struct stripe stripe[0];
45};
46
47/*
48 * An event is triggered whenever a drive
49 * drops out of a stripe volume.
50 */
51static void trigger_event(struct work_struct *work)
52{
53 struct stripe_c *sc = container_of(work, struct stripe_c,
54 trigger_event);
55 dm_table_event(sc->ti->table);
56}
57
58static inline struct stripe_c *alloc_context(unsigned int stripes)
59{
60 size_t len;
61
62 if (dm_array_too_big(sizeof(struct stripe_c), sizeof(struct stripe),
63 stripes))
64 return NULL;
65
66 len = sizeof(struct stripe_c) + (sizeof(struct stripe) * stripes);
67
68 return kmalloc(len, GFP_KERNEL);
69}
70
71/*
72 * Parse a single <dev> <sector> pair
73 */
74static int get_stripe(struct dm_target *ti, struct stripe_c *sc,
75 unsigned int stripe, char **argv)
76{
77 unsigned long long start;
78 char dummy;
79 int ret;
80
81 if (sscanf(argv[1], "%llu%c", &start, &dummy) != 1)
82 return -EINVAL;
83
84 ret = dm_get_device(ti, argv[0], dm_table_get_mode(ti->table),
85 &sc->stripe[stripe].dev);
86 if (ret)
87 return ret;
88
89 sc->stripe[stripe].physical_start = start;
90
91 return 0;
92}
93
94/*
95 * Construct a striped mapping.
96 * <number of stripes> <chunk size> [<dev_path> <offset>]+
97 */
98static int stripe_ctr(struct dm_target *ti, unsigned int argc, char **argv)
99{
100 struct stripe_c *sc;
101 sector_t width, tmp_len;
102 uint32_t stripes;
103 uint32_t chunk_size;
104 int r;
105 unsigned int i;
106
107 if (argc < 2) {
108 ti->error = "Not enough arguments";
109 return -EINVAL;
110 }
111
112 if (kstrtouint(argv[0], 10, &stripes) || !stripes) {
113 ti->error = "Invalid stripe count";
114 return -EINVAL;
115 }
116
117 if (kstrtouint(argv[1], 10, &chunk_size) || !chunk_size) {
118 ti->error = "Invalid chunk_size";
119 return -EINVAL;
120 }
121
122 width = ti->len;
123 if (sector_div(width, stripes)) {
124 ti->error = "Target length not divisible by "
125 "number of stripes";
126 return -EINVAL;
127 }
128
129 tmp_len = width;
130 if (sector_div(tmp_len, chunk_size)) {
131 ti->error = "Target length not divisible by "
132 "chunk size";
133 return -EINVAL;
134 }
135
136 /*
137 * Do we have enough arguments for that many stripes ?
138 */
139 if (argc != (2 + 2 * stripes)) {
140 ti->error = "Not enough destinations "
141 "specified";
142 return -EINVAL;
143 }
144
145 sc = alloc_context(stripes);
146 if (!sc) {
147 ti->error = "Memory allocation for striped context "
148 "failed";
149 return -ENOMEM;
150 }
151
152 INIT_WORK(&sc->trigger_event, trigger_event);
153
154 /* Set pointer to dm target; used in trigger_event */
155 sc->ti = ti;
156 sc->stripes = stripes;
157 sc->stripe_width = width;
158
159 if (stripes & (stripes - 1))
160 sc->stripes_shift = -1;
161 else
162 sc->stripes_shift = __ffs(stripes);
163
164 r = dm_set_target_max_io_len(ti, chunk_size);
165 if (r) {
166 kfree(sc);
167 return r;
168 }
169
170 ti->num_flush_bios = stripes;
171 ti->num_discard_bios = stripes;
172 ti->num_secure_erase_bios = stripes;
173 ti->num_write_same_bios = stripes;
174 ti->num_write_zeroes_bios = stripes;
175
176 sc->chunk_size = chunk_size;
177 if (chunk_size & (chunk_size - 1))
178 sc->chunk_size_shift = -1;
179 else
180 sc->chunk_size_shift = __ffs(chunk_size);
181
182 /*
183 * Get the stripe destinations.
184 */
185 for (i = 0; i < stripes; i++) {
186 argv += 2;
187
188 r = get_stripe(ti, sc, i, argv);
189 if (r < 0) {
190 ti->error = "Couldn't parse stripe destination";
191 while (i--)
192 dm_put_device(ti, sc->stripe[i].dev);
193 kfree(sc);
194 return r;
195 }
196 atomic_set(&(sc->stripe[i].error_count), 0);
197 }
198
199 ti->private = sc;
200
201 return 0;
202}
203
204static void stripe_dtr(struct dm_target *ti)
205{
206 unsigned int i;
207 struct stripe_c *sc = (struct stripe_c *) ti->private;
208
209 for (i = 0; i < sc->stripes; i++)
210 dm_put_device(ti, sc->stripe[i].dev);
211
212 flush_work(&sc->trigger_event);
213 kfree(sc);
214}
215
216static void stripe_map_sector(struct stripe_c *sc, sector_t sector,
217 uint32_t *stripe, sector_t *result)
218{
219 sector_t chunk = dm_target_offset(sc->ti, sector);
220 sector_t chunk_offset;
221
222 if (sc->chunk_size_shift < 0)
223 chunk_offset = sector_div(chunk, sc->chunk_size);
224 else {
225 chunk_offset = chunk & (sc->chunk_size - 1);
226 chunk >>= sc->chunk_size_shift;
227 }
228
229 if (sc->stripes_shift < 0)
230 *stripe = sector_div(chunk, sc->stripes);
231 else {
232 *stripe = chunk & (sc->stripes - 1);
233 chunk >>= sc->stripes_shift;
234 }
235
236 if (sc->chunk_size_shift < 0)
237 chunk *= sc->chunk_size;
238 else
239 chunk <<= sc->chunk_size_shift;
240
241 *result = chunk + chunk_offset;
242}
243
244static void stripe_map_range_sector(struct stripe_c *sc, sector_t sector,
245 uint32_t target_stripe, sector_t *result)
246{
247 uint32_t stripe;
248
249 stripe_map_sector(sc, sector, &stripe, result);
250 if (stripe == target_stripe)
251 return;
252
253 /* round down */
254 sector = *result;
255 if (sc->chunk_size_shift < 0)
256 *result -= sector_div(sector, sc->chunk_size);
257 else
258 *result = sector & ~(sector_t)(sc->chunk_size - 1);
259
260 if (target_stripe < stripe)
261 *result += sc->chunk_size; /* next chunk */
262}
263
264static int stripe_map_range(struct stripe_c *sc, struct bio *bio,
265 uint32_t target_stripe)
266{
267 sector_t begin, end;
268
269 stripe_map_range_sector(sc, bio->bi_iter.bi_sector,
270 target_stripe, &begin);
271 stripe_map_range_sector(sc, bio_end_sector(bio),
272 target_stripe, &end);
273 if (begin < end) {
274 bio_set_dev(bio, sc->stripe[target_stripe].dev->bdev);
275 bio->bi_iter.bi_sector = begin +
276 sc->stripe[target_stripe].physical_start;
277 bio->bi_iter.bi_size = to_bytes(end - begin);
278 return DM_MAPIO_REMAPPED;
279 } else {
280 /* The range doesn't map to the target stripe */
281 bio_endio(bio);
282 return DM_MAPIO_SUBMITTED;
283 }
284}
285
286static int stripe_map(struct dm_target *ti, struct bio *bio)
287{
288 struct stripe_c *sc = ti->private;
289 uint32_t stripe;
290 unsigned target_bio_nr;
291
292 if (bio->bi_opf & REQ_PREFLUSH) {
293 target_bio_nr = dm_bio_get_target_bio_nr(bio);
294 BUG_ON(target_bio_nr >= sc->stripes);
295 bio_set_dev(bio, sc->stripe[target_bio_nr].dev->bdev);
296 return DM_MAPIO_REMAPPED;
297 }
298 if (unlikely(bio_op(bio) == REQ_OP_DISCARD) ||
299 unlikely(bio_op(bio) == REQ_OP_SECURE_ERASE) ||
300 unlikely(bio_op(bio) == REQ_OP_WRITE_ZEROES) ||
301 unlikely(bio_op(bio) == REQ_OP_WRITE_SAME)) {
302 target_bio_nr = dm_bio_get_target_bio_nr(bio);
303 BUG_ON(target_bio_nr >= sc->stripes);
304 return stripe_map_range(sc, bio, target_bio_nr);
305 }
306
307 stripe_map_sector(sc, bio->bi_iter.bi_sector,
308 &stripe, &bio->bi_iter.bi_sector);
309
310 bio->bi_iter.bi_sector += sc->stripe[stripe].physical_start;
311 bio_set_dev(bio, sc->stripe[stripe].dev->bdev);
312
313 return DM_MAPIO_REMAPPED;
314}
315
316#if IS_ENABLED(CONFIG_DAX_DRIVER)
317static long stripe_dax_direct_access(struct dm_target *ti, pgoff_t pgoff,
318 long nr_pages, void **kaddr, pfn_t *pfn)
319{
320 sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
321 struct stripe_c *sc = ti->private;
322 struct dax_device *dax_dev;
323 struct block_device *bdev;
324 uint32_t stripe;
325 long ret;
326
327 stripe_map_sector(sc, sector, &stripe, &dev_sector);
328 dev_sector += sc->stripe[stripe].physical_start;
329 dax_dev = sc->stripe[stripe].dev->dax_dev;
330 bdev = sc->stripe[stripe].dev->bdev;
331
332 ret = bdev_dax_pgoff(bdev, dev_sector, nr_pages * PAGE_SIZE, &pgoff);
333 if (ret)
334 return ret;
335 return dax_direct_access(dax_dev, pgoff, nr_pages, kaddr, pfn);
336}
337
338static size_t stripe_dax_copy_from_iter(struct dm_target *ti, pgoff_t pgoff,
339 void *addr, size_t bytes, struct iov_iter *i)
340{
341 sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
342 struct stripe_c *sc = ti->private;
343 struct dax_device *dax_dev;
344 struct block_device *bdev;
345 uint32_t stripe;
346
347 stripe_map_sector(sc, sector, &stripe, &dev_sector);
348 dev_sector += sc->stripe[stripe].physical_start;
349 dax_dev = sc->stripe[stripe].dev->dax_dev;
350 bdev = sc->stripe[stripe].dev->bdev;
351
352 if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
353 return 0;
354 return dax_copy_from_iter(dax_dev, pgoff, addr, bytes, i);
355}
356
357static size_t stripe_dax_copy_to_iter(struct dm_target *ti, pgoff_t pgoff,
358 void *addr, size_t bytes, struct iov_iter *i)
359{
360 sector_t dev_sector, sector = pgoff * PAGE_SECTORS;
361 struct stripe_c *sc = ti->private;
362 struct dax_device *dax_dev;
363 struct block_device *bdev;
364 uint32_t stripe;
365
366 stripe_map_sector(sc, sector, &stripe, &dev_sector);
367 dev_sector += sc->stripe[stripe].physical_start;
368 dax_dev = sc->stripe[stripe].dev->dax_dev;
369 bdev = sc->stripe[stripe].dev->bdev;
370
371 if (bdev_dax_pgoff(bdev, dev_sector, ALIGN(bytes, PAGE_SIZE), &pgoff))
372 return 0;
373 return dax_copy_to_iter(dax_dev, pgoff, addr, bytes, i);
374}
375
376#else
377#define stripe_dax_direct_access NULL
378#define stripe_dax_copy_from_iter NULL
379#define stripe_dax_copy_to_iter NULL
380#endif
381
382/*
383 * Stripe status:
384 *
385 * INFO
386 * #stripes [stripe_name <stripe_name>] [group word count]
387 * [error count 'A|D' <error count 'A|D'>]
388 *
389 * TABLE
390 * #stripes [stripe chunk size]
391 * [stripe_name physical_start <stripe_name physical_start>]
392 *
393 */
394
395static void stripe_status(struct dm_target *ti, status_type_t type,
396 unsigned status_flags, char *result, unsigned maxlen)
397{
398 struct stripe_c *sc = (struct stripe_c *) ti->private;
399 unsigned int sz = 0;
400 unsigned int i;
401
402 switch (type) {
403 case STATUSTYPE_INFO:
404 DMEMIT("%d ", sc->stripes);
405 for (i = 0; i < sc->stripes; i++) {
406 DMEMIT("%s ", sc->stripe[i].dev->name);
407 }
408 DMEMIT("1 ");
409 for (i = 0; i < sc->stripes; i++) {
410 DMEMIT("%c", atomic_read(&(sc->stripe[i].error_count)) ?
411 'D' : 'A');
412 }
413 break;
414
415 case STATUSTYPE_TABLE:
416 DMEMIT("%d %llu", sc->stripes,
417 (unsigned long long)sc->chunk_size);
418 for (i = 0; i < sc->stripes; i++)
419 DMEMIT(" %s %llu", sc->stripe[i].dev->name,
420 (unsigned long long)sc->stripe[i].physical_start);
421 break;
422 }
423}
424
425static int stripe_end_io(struct dm_target *ti, struct bio *bio,
426 blk_status_t *error)
427{
428 unsigned i;
429 char major_minor[16];
430 struct stripe_c *sc = ti->private;
431
432 if (!*error)
433 return DM_ENDIO_DONE; /* I/O complete */
434
435 if (bio->bi_opf & REQ_RAHEAD)
436 return DM_ENDIO_DONE;
437
438 if (*error == BLK_STS_NOTSUPP)
439 return DM_ENDIO_DONE;
440
441 memset(major_minor, 0, sizeof(major_minor));
442 sprintf(major_minor, "%d:%d", MAJOR(bio_dev(bio)), MINOR(bio_dev(bio)));
443
444 /*
445 * Test to see which stripe drive triggered the event
446 * and increment error count for all stripes on that device.
447 * If the error count for a given device exceeds the threshold
448 * value we will no longer trigger any further events.
449 */
450 for (i = 0; i < sc->stripes; i++)
451 if (!strcmp(sc->stripe[i].dev->name, major_minor)) {
452 atomic_inc(&(sc->stripe[i].error_count));
453 if (atomic_read(&(sc->stripe[i].error_count)) <
454 DM_IO_ERROR_THRESHOLD)
455 schedule_work(&sc->trigger_event);
456 }
457
458 return DM_ENDIO_DONE;
459}
460
461static int stripe_iterate_devices(struct dm_target *ti,
462 iterate_devices_callout_fn fn, void *data)
463{
464 struct stripe_c *sc = ti->private;
465 int ret = 0;
466 unsigned i = 0;
467
468 do {
469 ret = fn(ti, sc->stripe[i].dev,
470 sc->stripe[i].physical_start,
471 sc->stripe_width, data);
472 } while (!ret && ++i < sc->stripes);
473
474 return ret;
475}
476
477static void stripe_io_hints(struct dm_target *ti,
478 struct queue_limits *limits)
479{
480 struct stripe_c *sc = ti->private;
481 unsigned chunk_size = sc->chunk_size << SECTOR_SHIFT;
482
483 blk_limits_io_min(limits, chunk_size);
484 blk_limits_io_opt(limits, chunk_size * sc->stripes);
485}
486
487static struct target_type stripe_target = {
488 .name = "striped",
489 .version = {1, 6, 0},
490 .features = DM_TARGET_PASSES_INTEGRITY,
491 .module = THIS_MODULE,
492 .ctr = stripe_ctr,
493 .dtr = stripe_dtr,
494 .map = stripe_map,
495 .end_io = stripe_end_io,
496 .status = stripe_status,
497 .iterate_devices = stripe_iterate_devices,
498 .io_hints = stripe_io_hints,
499 .direct_access = stripe_dax_direct_access,
500 .dax_copy_from_iter = stripe_dax_copy_from_iter,
501 .dax_copy_to_iter = stripe_dax_copy_to_iter,
502};
503
504int __init dm_stripe_init(void)
505{
506 int r;
507
508 r = dm_register_target(&stripe_target);
509 if (r < 0)
510 DMWARN("target registration failed");
511
512 return r;
513}
514
515void dm_stripe_exit(void)
516{
517 dm_unregister_target(&stripe_target);
518}
519