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9e0e252a VV |
1 | /* |
2 | * Bad block management | |
3 | * | |
4 | * - Heavily based on MD badblocks code from Neil Brown | |
5 | * | |
6 | * Copyright (c) 2015, Intel Corporation. | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or modify it | |
9 | * under the terms and conditions of the GNU General Public License, | |
10 | * version 2, as published by the Free Software Foundation. | |
11 | * | |
12 | * This program is distributed in the hope it will be useful, but WITHOUT | |
13 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
15 | * more details. | |
16 | */ | |
17 | ||
18 | #include <linux/badblocks.h> | |
19 | #include <linux/seqlock.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/module.h> | |
22 | #include <linux/stddef.h> | |
23 | #include <linux/types.h> | |
24 | #include <linux/slab.h> | |
25 | ||
26 | /** | |
27 | * badblocks_check() - check a given range for bad sectors | |
28 | * @bb: the badblocks structure that holds all badblock information | |
29 | * @s: sector (start) at which to check for badblocks | |
30 | * @sectors: number of sectors to check for badblocks | |
31 | * @first_bad: pointer to store location of the first badblock | |
32 | * @bad_sectors: pointer to store number of badblocks after @first_bad | |
33 | * | |
34 | * We can record which blocks on each device are 'bad' and so just | |
35 | * fail those blocks, or that stripe, rather than the whole device. | |
36 | * Entries in the bad-block table are 64bits wide. This comprises: | |
37 | * Length of bad-range, in sectors: 0-511 for lengths 1-512 | |
38 | * Start of bad-range, sector offset, 54 bits (allows 8 exbibytes) | |
39 | * A 'shift' can be set so that larger blocks are tracked and | |
40 | * consequently larger devices can be covered. | |
41 | * 'Acknowledged' flag - 1 bit. - the most significant bit. | |
42 | * | |
43 | * Locking of the bad-block table uses a seqlock so badblocks_check | |
44 | * might need to retry if it is very unlucky. | |
45 | * We will sometimes want to check for bad blocks in a bi_end_io function, | |
46 | * so we use the write_seqlock_irq variant. | |
47 | * | |
48 | * When looking for a bad block we specify a range and want to | |
49 | * know if any block in the range is bad. So we binary-search | |
50 | * to the last range that starts at-or-before the given endpoint, | |
51 | * (or "before the sector after the target range") | |
52 | * then see if it ends after the given start. | |
53 | * | |
54 | * Return: | |
55 | * 0: there are no known bad blocks in the range | |
56 | * 1: there are known bad block which are all acknowledged | |
57 | * -1: there are bad blocks which have not yet been acknowledged in metadata. | |
58 | * plus the start/length of the first bad section we overlap. | |
59 | */ | |
60 | int badblocks_check(struct badblocks *bb, sector_t s, int sectors, | |
61 | sector_t *first_bad, int *bad_sectors) | |
62 | { | |
63 | int hi; | |
64 | int lo; | |
65 | u64 *p = bb->page; | |
66 | int rv; | |
67 | sector_t target = s + sectors; | |
68 | unsigned seq; | |
69 | ||
70 | if (bb->shift > 0) { | |
71 | /* round the start down, and the end up */ | |
72 | s >>= bb->shift; | |
73 | target += (1<<bb->shift) - 1; | |
74 | target >>= bb->shift; | |
75 | sectors = target - s; | |
76 | } | |
77 | /* 'target' is now the first block after the bad range */ | |
78 | ||
79 | retry: | |
80 | seq = read_seqbegin(&bb->lock); | |
81 | lo = 0; | |
82 | rv = 0; | |
83 | hi = bb->count; | |
84 | ||
85 | /* Binary search between lo and hi for 'target' | |
86 | * i.e. for the last range that starts before 'target' | |
87 | */ | |
88 | /* INVARIANT: ranges before 'lo' and at-or-after 'hi' | |
89 | * are known not to be the last range before target. | |
90 | * VARIANT: hi-lo is the number of possible | |
91 | * ranges, and decreases until it reaches 1 | |
92 | */ | |
93 | while (hi - lo > 1) { | |
94 | int mid = (lo + hi) / 2; | |
95 | sector_t a = BB_OFFSET(p[mid]); | |
96 | ||
97 | if (a < target) | |
98 | /* This could still be the one, earlier ranges | |
99 | * could not. | |
100 | */ | |
101 | lo = mid; | |
102 | else | |
103 | /* This and later ranges are definitely out. */ | |
104 | hi = mid; | |
105 | } | |
106 | /* 'lo' might be the last that started before target, but 'hi' isn't */ | |
107 | if (hi > lo) { | |
108 | /* need to check all range that end after 's' to see if | |
109 | * any are unacknowledged. | |
110 | */ | |
111 | while (lo >= 0 && | |
112 | BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) { | |
113 | if (BB_OFFSET(p[lo]) < target) { | |
114 | /* starts before the end, and finishes after | |
115 | * the start, so they must overlap | |
116 | */ | |
117 | if (rv != -1 && BB_ACK(p[lo])) | |
118 | rv = 1; | |
119 | else | |
120 | rv = -1; | |
121 | *first_bad = BB_OFFSET(p[lo]); | |
122 | *bad_sectors = BB_LEN(p[lo]); | |
123 | } | |
124 | lo--; | |
125 | } | |
126 | } | |
127 | ||
128 | if (read_seqretry(&bb->lock, seq)) | |
129 | goto retry; | |
130 | ||
131 | return rv; | |
132 | } | |
133 | EXPORT_SYMBOL_GPL(badblocks_check); | |
134 | ||
135 | /** | |
136 | * badblocks_set() - Add a range of bad blocks to the table. | |
137 | * @bb: the badblocks structure that holds all badblock information | |
138 | * @s: first sector to mark as bad | |
139 | * @sectors: number of sectors to mark as bad | |
140 | * @acknowledged: weather to mark the bad sectors as acknowledged | |
141 | * | |
142 | * This might extend the table, or might contract it if two adjacent ranges | |
143 | * can be merged. We binary-search to find the 'insertion' point, then | |
144 | * decide how best to handle it. | |
145 | * | |
146 | * Return: | |
147 | * 0: success | |
148 | * 1: failed to set badblocks (out of space) | |
149 | */ | |
150 | int badblocks_set(struct badblocks *bb, sector_t s, int sectors, | |
151 | int acknowledged) | |
152 | { | |
153 | u64 *p; | |
154 | int lo, hi; | |
155 | int rv = 0; | |
156 | unsigned long flags; | |
157 | ||
158 | if (bb->shift < 0) | |
159 | /* badblocks are disabled */ | |
160 | return 0; | |
161 | ||
162 | if (bb->shift) { | |
163 | /* round the start down, and the end up */ | |
164 | sector_t next = s + sectors; | |
165 | ||
166 | s >>= bb->shift; | |
167 | next += (1<<bb->shift) - 1; | |
168 | next >>= bb->shift; | |
169 | sectors = next - s; | |
170 | } | |
171 | ||
172 | write_seqlock_irqsave(&bb->lock, flags); | |
173 | ||
174 | p = bb->page; | |
175 | lo = 0; | |
176 | hi = bb->count; | |
177 | /* Find the last range that starts at-or-before 's' */ | |
178 | while (hi - lo > 1) { | |
179 | int mid = (lo + hi) / 2; | |
180 | sector_t a = BB_OFFSET(p[mid]); | |
181 | ||
182 | if (a <= s) | |
183 | lo = mid; | |
184 | else | |
185 | hi = mid; | |
186 | } | |
187 | if (hi > lo && BB_OFFSET(p[lo]) > s) | |
188 | hi = lo; | |
189 | ||
190 | if (hi > lo) { | |
191 | /* we found a range that might merge with the start | |
192 | * of our new range | |
193 | */ | |
194 | sector_t a = BB_OFFSET(p[lo]); | |
195 | sector_t e = a + BB_LEN(p[lo]); | |
196 | int ack = BB_ACK(p[lo]); | |
197 | ||
198 | if (e >= s) { | |
199 | /* Yes, we can merge with a previous range */ | |
200 | if (s == a && s + sectors >= e) | |
201 | /* new range covers old */ | |
202 | ack = acknowledged; | |
203 | else | |
204 | ack = ack && acknowledged; | |
205 | ||
206 | if (e < s + sectors) | |
207 | e = s + sectors; | |
208 | if (e - a <= BB_MAX_LEN) { | |
209 | p[lo] = BB_MAKE(a, e-a, ack); | |
210 | s = e; | |
211 | } else { | |
212 | /* does not all fit in one range, | |
213 | * make p[lo] maximal | |
214 | */ | |
215 | if (BB_LEN(p[lo]) != BB_MAX_LEN) | |
216 | p[lo] = BB_MAKE(a, BB_MAX_LEN, ack); | |
217 | s = a + BB_MAX_LEN; | |
218 | } | |
219 | sectors = e - s; | |
220 | } | |
221 | } | |
222 | if (sectors && hi < bb->count) { | |
223 | /* 'hi' points to the first range that starts after 's'. | |
224 | * Maybe we can merge with the start of that range | |
225 | */ | |
226 | sector_t a = BB_OFFSET(p[hi]); | |
227 | sector_t e = a + BB_LEN(p[hi]); | |
228 | int ack = BB_ACK(p[hi]); | |
229 | ||
230 | if (a <= s + sectors) { | |
231 | /* merging is possible */ | |
232 | if (e <= s + sectors) { | |
233 | /* full overlap */ | |
234 | e = s + sectors; | |
235 | ack = acknowledged; | |
236 | } else | |
237 | ack = ack && acknowledged; | |
238 | ||
239 | a = s; | |
240 | if (e - a <= BB_MAX_LEN) { | |
241 | p[hi] = BB_MAKE(a, e-a, ack); | |
242 | s = e; | |
243 | } else { | |
244 | p[hi] = BB_MAKE(a, BB_MAX_LEN, ack); | |
245 | s = a + BB_MAX_LEN; | |
246 | } | |
247 | sectors = e - s; | |
248 | lo = hi; | |
249 | hi++; | |
250 | } | |
251 | } | |
252 | if (sectors == 0 && hi < bb->count) { | |
253 | /* we might be able to combine lo and hi */ | |
254 | /* Note: 's' is at the end of 'lo' */ | |
255 | sector_t a = BB_OFFSET(p[hi]); | |
256 | int lolen = BB_LEN(p[lo]); | |
257 | int hilen = BB_LEN(p[hi]); | |
258 | int newlen = lolen + hilen - (s - a); | |
259 | ||
260 | if (s >= a && newlen < BB_MAX_LEN) { | |
261 | /* yes, we can combine them */ | |
262 | int ack = BB_ACK(p[lo]) && BB_ACK(p[hi]); | |
263 | ||
264 | p[lo] = BB_MAKE(BB_OFFSET(p[lo]), newlen, ack); | |
265 | memmove(p + hi, p + hi + 1, | |
266 | (bb->count - hi - 1) * 8); | |
267 | bb->count--; | |
268 | } | |
269 | } | |
270 | while (sectors) { | |
271 | /* didn't merge (it all). | |
272 | * Need to add a range just before 'hi' | |
273 | */ | |
274 | if (bb->count >= MAX_BADBLOCKS) { | |
275 | /* No room for more */ | |
276 | rv = 1; | |
277 | break; | |
278 | } else { | |
279 | int this_sectors = sectors; | |
280 | ||
281 | memmove(p + hi + 1, p + hi, | |
282 | (bb->count - hi) * 8); | |
283 | bb->count++; | |
284 | ||
285 | if (this_sectors > BB_MAX_LEN) | |
286 | this_sectors = BB_MAX_LEN; | |
287 | p[hi] = BB_MAKE(s, this_sectors, acknowledged); | |
288 | sectors -= this_sectors; | |
289 | s += this_sectors; | |
290 | } | |
291 | } | |
292 | ||
293 | bb->changed = 1; | |
294 | if (!acknowledged) | |
295 | bb->unacked_exist = 1; | |
296 | write_sequnlock_irqrestore(&bb->lock, flags); | |
297 | ||
298 | return rv; | |
299 | } | |
300 | EXPORT_SYMBOL_GPL(badblocks_set); | |
301 | ||
302 | /** | |
303 | * badblocks_clear() - Remove a range of bad blocks to the table. | |
304 | * @bb: the badblocks structure that holds all badblock information | |
305 | * @s: first sector to mark as bad | |
306 | * @sectors: number of sectors to mark as bad | |
307 | * | |
308 | * This may involve extending the table if we spilt a region, | |
309 | * but it must not fail. So if the table becomes full, we just | |
310 | * drop the remove request. | |
311 | * | |
312 | * Return: | |
313 | * 0: success | |
314 | * 1: failed to clear badblocks | |
315 | */ | |
316 | int badblocks_clear(struct badblocks *bb, sector_t s, int sectors) | |
317 | { | |
318 | u64 *p; | |
319 | int lo, hi; | |
320 | sector_t target = s + sectors; | |
321 | int rv = 0; | |
322 | ||
323 | if (bb->shift > 0) { | |
324 | /* When clearing we round the start up and the end down. | |
325 | * This should not matter as the shift should align with | |
326 | * the block size and no rounding should ever be needed. | |
327 | * However it is better the think a block is bad when it | |
328 | * isn't than to think a block is not bad when it is. | |
329 | */ | |
330 | s += (1<<bb->shift) - 1; | |
331 | s >>= bb->shift; | |
332 | target >>= bb->shift; | |
333 | sectors = target - s; | |
334 | } | |
335 | ||
336 | write_seqlock_irq(&bb->lock); | |
337 | ||
338 | p = bb->page; | |
339 | lo = 0; | |
340 | hi = bb->count; | |
341 | /* Find the last range that starts before 'target' */ | |
342 | while (hi - lo > 1) { | |
343 | int mid = (lo + hi) / 2; | |
344 | sector_t a = BB_OFFSET(p[mid]); | |
345 | ||
346 | if (a < target) | |
347 | lo = mid; | |
348 | else | |
349 | hi = mid; | |
350 | } | |
351 | if (hi > lo) { | |
352 | /* p[lo] is the last range that could overlap the | |
353 | * current range. Earlier ranges could also overlap, | |
354 | * but only this one can overlap the end of the range. | |
355 | */ | |
356 | if (BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > target) { | |
357 | /* Partial overlap, leave the tail of this range */ | |
358 | int ack = BB_ACK(p[lo]); | |
359 | sector_t a = BB_OFFSET(p[lo]); | |
360 | sector_t end = a + BB_LEN(p[lo]); | |
361 | ||
362 | if (a < s) { | |
363 | /* we need to split this range */ | |
364 | if (bb->count >= MAX_BADBLOCKS) { | |
365 | rv = -ENOSPC; | |
366 | goto out; | |
367 | } | |
368 | memmove(p+lo+1, p+lo, (bb->count - lo) * 8); | |
369 | bb->count++; | |
370 | p[lo] = BB_MAKE(a, s-a, ack); | |
371 | lo++; | |
372 | } | |
373 | p[lo] = BB_MAKE(target, end - target, ack); | |
374 | /* there is no longer an overlap */ | |
375 | hi = lo; | |
376 | lo--; | |
377 | } | |
378 | while (lo >= 0 && | |
379 | BB_OFFSET(p[lo]) + BB_LEN(p[lo]) > s) { | |
380 | /* This range does overlap */ | |
381 | if (BB_OFFSET(p[lo]) < s) { | |
382 | /* Keep the early parts of this range. */ | |
383 | int ack = BB_ACK(p[lo]); | |
384 | sector_t start = BB_OFFSET(p[lo]); | |
385 | ||
386 | p[lo] = BB_MAKE(start, s - start, ack); | |
387 | /* now low doesn't overlap, so.. */ | |
388 | break; | |
389 | } | |
390 | lo--; | |
391 | } | |
392 | /* 'lo' is strictly before, 'hi' is strictly after, | |
393 | * anything between needs to be discarded | |
394 | */ | |
395 | if (hi - lo > 1) { | |
396 | memmove(p+lo+1, p+hi, (bb->count - hi) * 8); | |
397 | bb->count -= (hi - lo - 1); | |
398 | } | |
399 | } | |
400 | ||
401 | bb->changed = 1; | |
402 | out: | |
403 | write_sequnlock_irq(&bb->lock); | |
404 | return rv; | |
405 | } | |
406 | EXPORT_SYMBOL_GPL(badblocks_clear); | |
407 | ||
408 | /** | |
409 | * ack_all_badblocks() - Acknowledge all bad blocks in a list. | |
410 | * @bb: the badblocks structure that holds all badblock information | |
411 | * | |
412 | * This only succeeds if ->changed is clear. It is used by | |
413 | * in-kernel metadata updates | |
414 | */ | |
415 | void ack_all_badblocks(struct badblocks *bb) | |
416 | { | |
417 | if (bb->page == NULL || bb->changed) | |
418 | /* no point even trying */ | |
419 | return; | |
420 | write_seqlock_irq(&bb->lock); | |
421 | ||
422 | if (bb->changed == 0 && bb->unacked_exist) { | |
423 | u64 *p = bb->page; | |
424 | int i; | |
425 | ||
426 | for (i = 0; i < bb->count ; i++) { | |
427 | if (!BB_ACK(p[i])) { | |
428 | sector_t start = BB_OFFSET(p[i]); | |
429 | int len = BB_LEN(p[i]); | |
430 | ||
431 | p[i] = BB_MAKE(start, len, 1); | |
432 | } | |
433 | } | |
434 | bb->unacked_exist = 0; | |
435 | } | |
436 | write_sequnlock_irq(&bb->lock); | |
437 | } | |
438 | EXPORT_SYMBOL_GPL(ack_all_badblocks); | |
439 | ||
440 | /** | |
441 | * badblocks_show() - sysfs access to bad-blocks list | |
442 | * @bb: the badblocks structure that holds all badblock information | |
443 | * @page: buffer received from sysfs | |
444 | * @unack: weather to show unacknowledged badblocks | |
445 | * | |
446 | * Return: | |
447 | * Length of returned data | |
448 | */ | |
449 | ssize_t badblocks_show(struct badblocks *bb, char *page, int unack) | |
450 | { | |
451 | size_t len; | |
452 | int i; | |
453 | u64 *p = bb->page; | |
454 | unsigned seq; | |
455 | ||
456 | if (bb->shift < 0) | |
457 | return 0; | |
458 | ||
459 | retry: | |
460 | seq = read_seqbegin(&bb->lock); | |
461 | ||
462 | len = 0; | |
463 | i = 0; | |
464 | ||
465 | while (len < PAGE_SIZE && i < bb->count) { | |
466 | sector_t s = BB_OFFSET(p[i]); | |
467 | unsigned int length = BB_LEN(p[i]); | |
468 | int ack = BB_ACK(p[i]); | |
469 | ||
470 | i++; | |
471 | ||
472 | if (unack && ack) | |
473 | continue; | |
474 | ||
475 | len += snprintf(page+len, PAGE_SIZE-len, "%llu %u\n", | |
476 | (unsigned long long)s << bb->shift, | |
477 | length << bb->shift); | |
478 | } | |
479 | if (unack && len == 0) | |
480 | bb->unacked_exist = 0; | |
481 | ||
482 | if (read_seqretry(&bb->lock, seq)) | |
483 | goto retry; | |
484 | ||
485 | return len; | |
486 | } | |
487 | EXPORT_SYMBOL_GPL(badblocks_show); | |
488 | ||
489 | /** | |
490 | * badblocks_store() - sysfs access to bad-blocks list | |
491 | * @bb: the badblocks structure that holds all badblock information | |
492 | * @page: buffer received from sysfs | |
493 | * @len: length of data received from sysfs | |
494 | * @unack: weather to show unacknowledged badblocks | |
495 | * | |
496 | * Return: | |
497 | * Length of the buffer processed or -ve error. | |
498 | */ | |
499 | ssize_t badblocks_store(struct badblocks *bb, const char *page, size_t len, | |
500 | int unack) | |
501 | { | |
502 | unsigned long long sector; | |
503 | int length; | |
504 | char newline; | |
505 | ||
506 | switch (sscanf(page, "%llu %d%c", §or, &length, &newline)) { | |
507 | case 3: | |
508 | if (newline != '\n') | |
509 | return -EINVAL; | |
510 | case 2: | |
511 | if (length <= 0) | |
512 | return -EINVAL; | |
513 | break; | |
514 | default: | |
515 | return -EINVAL; | |
516 | } | |
517 | ||
518 | if (badblocks_set(bb, sector, length, !unack)) | |
519 | return -ENOSPC; | |
520 | else | |
521 | return len; | |
522 | } | |
523 | EXPORT_SYMBOL_GPL(badblocks_store); | |
524 | ||
525 | /** | |
526 | * badblocks_init() - initialize the badblocks structure | |
527 | * @bb: the badblocks structure that holds all badblock information | |
528 | * @enable: weather to enable badblocks accounting | |
529 | * | |
530 | * Return: | |
531 | * 0: success | |
532 | * -ve errno: on error | |
533 | */ | |
534 | int badblocks_init(struct badblocks *bb, int enable) | |
535 | { | |
536 | bb->count = 0; | |
537 | if (enable) | |
538 | bb->shift = 0; | |
539 | else | |
540 | bb->shift = -1; | |
541 | bb->page = kzalloc(PAGE_SIZE, GFP_KERNEL); | |
542 | if (bb->page == (u64 *)0) { | |
543 | bb->shift = -1; | |
544 | return -ENOMEM; | |
545 | } | |
546 | seqlock_init(&bb->lock); | |
547 | ||
548 | return 0; | |
549 | } | |
550 | EXPORT_SYMBOL_GPL(badblocks_init); | |
551 | ||
552 | /** | |
d3b407fb | 553 | * badblocks_exit() - free the badblocks structure |
9e0e252a VV |
554 | * @bb: the badblocks structure that holds all badblock information |
555 | */ | |
d3b407fb | 556 | void badblocks_exit(struct badblocks *bb) |
9e0e252a | 557 | { |
20a308f0 DW |
558 | if (!bb) |
559 | return; | |
9e0e252a VV |
560 | kfree(bb->page); |
561 | bb->page = NULL; | |
562 | } | |
d3b407fb | 563 | EXPORT_SYMBOL_GPL(badblocks_exit); |