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1 | /* |
2 | * Copyright (c) International Business Machines Corp., 2006 | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See | |
12 | * the GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
17 | * | |
18 | * Authors: Artem Bityutskiy (Битюцкий Артём), Thomas Gleixner | |
19 | */ | |
20 | ||
21 | /* | |
22 | * UBI wear-leveling unit. | |
23 | * | |
24 | * This unit is responsible for wear-leveling. It works in terms of physical | |
25 | * eraseblocks and erase counters and knows nothing about logical eraseblocks, | |
26 | * volumes, etc. From this unit's perspective all physical eraseblocks are of | |
27 | * two types - used and free. Used physical eraseblocks are those that were | |
28 | * "get" by the 'ubi_wl_get_peb()' function, and free physical eraseblocks are | |
29 | * those that were put by the 'ubi_wl_put_peb()' function. | |
30 | * | |
31 | * Physical eraseblocks returned by 'ubi_wl_get_peb()' have only erase counter | |
32 | * header. The rest of the physical eraseblock contains only 0xFF bytes. | |
33 | * | |
34 | * When physical eraseblocks are returned to the WL unit by means of the | |
35 | * 'ubi_wl_put_peb()' function, they are scheduled for erasure. The erasure is | |
36 | * done asynchronously in context of the per-UBI device background thread, | |
37 | * which is also managed by the WL unit. | |
38 | * | |
39 | * The wear-leveling is ensured by means of moving the contents of used | |
40 | * physical eraseblocks with low erase counter to free physical eraseblocks | |
41 | * with high erase counter. | |
42 | * | |
43 | * The 'ubi_wl_get_peb()' function accepts data type hints which help to pick | |
44 | * an "optimal" physical eraseblock. For example, when it is known that the | |
45 | * physical eraseblock will be "put" soon because it contains short-term data, | |
46 | * the WL unit may pick a free physical eraseblock with low erase counter, and | |
47 | * so forth. | |
48 | * | |
49 | * If the WL unit fails to erase a physical eraseblock, it marks it as bad. | |
50 | * | |
51 | * This unit is also responsible for scrubbing. If a bit-flip is detected in a | |
52 | * physical eraseblock, it has to be moved. Technically this is the same as | |
53 | * moving it for wear-leveling reasons. | |
54 | * | |
55 | * As it was said, for the UBI unit all physical eraseblocks are either "free" | |
56 | * or "used". Free eraseblock are kept in the @wl->free RB-tree, while used | |
57 | * eraseblocks are kept in a set of different RB-trees: @wl->used, | |
58 | * @wl->prot.pnum, @wl->prot.aec, and @wl->scrub. | |
59 | * | |
60 | * Note, in this implementation, we keep a small in-RAM object for each physical | |
61 | * eraseblock. This is surely not a scalable solution. But it appears to be good | |
62 | * enough for moderately large flashes and it is simple. In future, one may | |
63 | * re-work this unit and make it more scalable. | |
64 | * | |
65 | * At the moment this unit does not utilize the sequence number, which was | |
66 | * introduced relatively recently. But it would be wise to do this because the | |
67 | * sequence number of a logical eraseblock characterizes how old is it. For | |
68 | * example, when we move a PEB with low erase counter, and we need to pick the | |
69 | * target PEB, we pick a PEB with the highest EC if our PEB is "old" and we | |
70 | * pick target PEB with an average EC if our PEB is not very "old". This is a | |
71 | * room for future re-works of the WL unit. | |
72 | * | |
73 | * FIXME: looks too complex, should be simplified (later). | |
74 | */ | |
75 | ||
76 | #include <linux/slab.h> | |
77 | #include <linux/crc32.h> | |
78 | #include <linux/freezer.h> | |
79 | #include <linux/kthread.h> | |
80 | #include "ubi.h" | |
81 | ||
82 | /* Number of physical eraseblocks reserved for wear-leveling purposes */ | |
83 | #define WL_RESERVED_PEBS 1 | |
84 | ||
85 | /* | |
86 | * How many erase cycles are short term, unknown, and long term physical | |
87 | * eraseblocks protected. | |
88 | */ | |
89 | #define ST_PROTECTION 16 | |
90 | #define U_PROTECTION 10 | |
91 | #define LT_PROTECTION 4 | |
92 | ||
93 | /* | |
94 | * Maximum difference between two erase counters. If this threshold is | |
95 | * exceeded, the WL unit starts moving data from used physical eraseblocks with | |
96 | * low erase counter to free physical eraseblocks with high erase counter. | |
97 | */ | |
98 | #define UBI_WL_THRESHOLD CONFIG_MTD_UBI_WL_THRESHOLD | |
99 | ||
100 | /* | |
101 | * When a physical eraseblock is moved, the WL unit has to pick the target | |
102 | * physical eraseblock to move to. The simplest way would be just to pick the | |
103 | * one with the highest erase counter. But in certain workloads this could lead | |
104 | * to an unlimited wear of one or few physical eraseblock. Indeed, imagine a | |
105 | * situation when the picked physical eraseblock is constantly erased after the | |
106 | * data is written to it. So, we have a constant which limits the highest erase | |
107 | * counter of the free physical eraseblock to pick. Namely, the WL unit does | |
108 | * not pick eraseblocks with erase counter greater then the lowest erase | |
109 | * counter plus %WL_FREE_MAX_DIFF. | |
110 | */ | |
111 | #define WL_FREE_MAX_DIFF (2*UBI_WL_THRESHOLD) | |
112 | ||
113 | /* | |
114 | * Maximum number of consecutive background thread failures which is enough to | |
115 | * switch to read-only mode. | |
116 | */ | |
117 | #define WL_MAX_FAILURES 32 | |
118 | ||
119 | /** | |
120 | * struct ubi_wl_entry - wear-leveling entry. | |
121 | * @rb: link in the corresponding RB-tree | |
122 | * @ec: erase counter | |
123 | * @pnum: physical eraseblock number | |
124 | * | |
125 | * Each physical eraseblock has a corresponding &struct wl_entry object which | |
126 | * may be kept in different RB-trees. | |
127 | */ | |
128 | struct ubi_wl_entry { | |
129 | struct rb_node rb; | |
130 | int ec; | |
131 | int pnum; | |
132 | }; | |
133 | ||
134 | /** | |
135 | * struct ubi_wl_prot_entry - PEB protection entry. | |
136 | * @rb_pnum: link in the @wl->prot.pnum RB-tree | |
137 | * @rb_aec: link in the @wl->prot.aec RB-tree | |
138 | * @abs_ec: the absolute erase counter value when the protection ends | |
139 | * @e: the wear-leveling entry of the physical eraseblock under protection | |
140 | * | |
141 | * When the WL unit returns a physical eraseblock, the physical eraseblock is | |
142 | * protected from being moved for some "time". For this reason, the physical | |
143 | * eraseblock is not directly moved from the @wl->free tree to the @wl->used | |
144 | * tree. There is one more tree in between where this physical eraseblock is | |
145 | * temporarily stored (@wl->prot). | |
146 | * | |
147 | * All this protection stuff is needed because: | |
148 | * o we don't want to move physical eraseblocks just after we have given them | |
149 | * to the user; instead, we first want to let users fill them up with data; | |
150 | * | |
151 | * o there is a chance that the user will put the physical eraseblock very | |
152 | * soon, so it makes sense not to move it for some time, but wait; this is | |
153 | * especially important in case of "short term" physical eraseblocks. | |
154 | * | |
155 | * Physical eraseblocks stay protected only for limited time. But the "time" is | |
156 | * measured in erase cycles in this case. This is implemented with help of the | |
157 | * absolute erase counter (@wl->abs_ec). When it reaches certain value, the | |
158 | * physical eraseblocks are moved from the protection trees (@wl->prot.*) to | |
159 | * the @wl->used tree. | |
160 | * | |
161 | * Protected physical eraseblocks are searched by physical eraseblock number | |
162 | * (when they are put) and by the absolute erase counter (to check if it is | |
163 | * time to move them to the @wl->used tree). So there are actually 2 RB-trees | |
164 | * storing the protected physical eraseblocks: @wl->prot.pnum and | |
165 | * @wl->prot.aec. They are referred to as the "protection" trees. The | |
166 | * first one is indexed by the physical eraseblock number. The second one is | |
167 | * indexed by the absolute erase counter. Both trees store | |
168 | * &struct ubi_wl_prot_entry objects. | |
169 | * | |
170 | * Each physical eraseblock has 2 main states: free and used. The former state | |
171 | * corresponds to the @wl->free tree. The latter state is split up on several | |
172 | * sub-states: | |
173 | * o the WL movement is allowed (@wl->used tree); | |
174 | * o the WL movement is temporarily prohibited (@wl->prot.pnum and | |
175 | * @wl->prot.aec trees); | |
176 | * o scrubbing is needed (@wl->scrub tree). | |
177 | * | |
178 | * Depending on the sub-state, wear-leveling entries of the used physical | |
179 | * eraseblocks may be kept in one of those trees. | |
180 | */ | |
181 | struct ubi_wl_prot_entry { | |
182 | struct rb_node rb_pnum; | |
183 | struct rb_node rb_aec; | |
184 | unsigned long long abs_ec; | |
185 | struct ubi_wl_entry *e; | |
186 | }; | |
187 | ||
188 | /** | |
189 | * struct ubi_work - UBI work description data structure. | |
190 | * @list: a link in the list of pending works | |
191 | * @func: worker function | |
192 | * @priv: private data of the worker function | |
193 | * | |
194 | * @e: physical eraseblock to erase | |
195 | * @torture: if the physical eraseblock has to be tortured | |
196 | * | |
197 | * The @func pointer points to the worker function. If the @cancel argument is | |
198 | * not zero, the worker has to free the resources and exit immediately. The | |
199 | * worker has to return zero in case of success and a negative error code in | |
200 | * case of failure. | |
201 | */ | |
202 | struct ubi_work { | |
203 | struct list_head list; | |
204 | int (*func)(struct ubi_device *ubi, struct ubi_work *wrk, int cancel); | |
205 | /* The below fields are only relevant to erasure works */ | |
206 | struct ubi_wl_entry *e; | |
207 | int torture; | |
208 | }; | |
209 | ||
210 | #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID | |
211 | static int paranoid_check_ec(const struct ubi_device *ubi, int pnum, int ec); | |
212 | static int paranoid_check_in_wl_tree(struct ubi_wl_entry *e, | |
213 | struct rb_root *root); | |
214 | #else | |
215 | #define paranoid_check_ec(ubi, pnum, ec) 0 | |
216 | #define paranoid_check_in_wl_tree(e, root) | |
217 | #endif | |
218 | ||
219 | /* Slab cache for wear-leveling entries */ | |
220 | static struct kmem_cache *wl_entries_slab; | |
221 | ||
222 | /** | |
223 | * tree_empty - a helper function to check if an RB-tree is empty. | |
224 | * @root: the root of the tree | |
225 | * | |
226 | * This function returns non-zero if the RB-tree is empty and zero if not. | |
227 | */ | |
228 | static inline int tree_empty(struct rb_root *root) | |
229 | { | |
230 | return root->rb_node == NULL; | |
231 | } | |
232 | ||
233 | /** | |
234 | * wl_tree_add - add a wear-leveling entry to a WL RB-tree. | |
235 | * @e: the wear-leveling entry to add | |
236 | * @root: the root of the tree | |
237 | * | |
238 | * Note, we use (erase counter, physical eraseblock number) pairs as keys in | |
239 | * the @ubi->used and @ubi->free RB-trees. | |
240 | */ | |
241 | static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root) | |
242 | { | |
243 | struct rb_node **p, *parent = NULL; | |
244 | ||
245 | p = &root->rb_node; | |
246 | while (*p) { | |
247 | struct ubi_wl_entry *e1; | |
248 | ||
249 | parent = *p; | |
250 | e1 = rb_entry(parent, struct ubi_wl_entry, rb); | |
251 | ||
252 | if (e->ec < e1->ec) | |
253 | p = &(*p)->rb_left; | |
254 | else if (e->ec > e1->ec) | |
255 | p = &(*p)->rb_right; | |
256 | else { | |
257 | ubi_assert(e->pnum != e1->pnum); | |
258 | if (e->pnum < e1->pnum) | |
259 | p = &(*p)->rb_left; | |
260 | else | |
261 | p = &(*p)->rb_right; | |
262 | } | |
263 | } | |
264 | ||
265 | rb_link_node(&e->rb, parent, p); | |
266 | rb_insert_color(&e->rb, root); | |
267 | } | |
268 | ||
269 | ||
270 | /* | |
271 | * Helper functions to add and delete wear-leveling entries from different | |
272 | * trees. | |
273 | */ | |
274 | ||
275 | static void free_tree_add(struct ubi_device *ubi, struct ubi_wl_entry *e) | |
276 | { | |
277 | wl_tree_add(e, &ubi->free); | |
278 | } | |
279 | static inline void used_tree_add(struct ubi_device *ubi, | |
280 | struct ubi_wl_entry *e) | |
281 | { | |
282 | wl_tree_add(e, &ubi->used); | |
283 | } | |
284 | static inline void scrub_tree_add(struct ubi_device *ubi, | |
285 | struct ubi_wl_entry *e) | |
286 | { | |
287 | wl_tree_add(e, &ubi->scrub); | |
288 | } | |
289 | static inline void free_tree_del(struct ubi_device *ubi, | |
290 | struct ubi_wl_entry *e) | |
291 | { | |
292 | paranoid_check_in_wl_tree(e, &ubi->free); | |
293 | rb_erase(&e->rb, &ubi->free); | |
294 | } | |
295 | static inline void used_tree_del(struct ubi_device *ubi, | |
296 | struct ubi_wl_entry *e) | |
297 | { | |
298 | paranoid_check_in_wl_tree(e, &ubi->used); | |
299 | rb_erase(&e->rb, &ubi->used); | |
300 | } | |
301 | static inline void scrub_tree_del(struct ubi_device *ubi, | |
302 | struct ubi_wl_entry *e) | |
303 | { | |
304 | paranoid_check_in_wl_tree(e, &ubi->scrub); | |
305 | rb_erase(&e->rb, &ubi->scrub); | |
306 | } | |
307 | ||
308 | /** | |
309 | * do_work - do one pending work. | |
310 | * @ubi: UBI device description object | |
311 | * | |
312 | * This function returns zero in case of success and a negative error code in | |
313 | * case of failure. | |
314 | */ | |
315 | static int do_work(struct ubi_device *ubi) | |
316 | { | |
317 | int err; | |
318 | struct ubi_work *wrk; | |
319 | ||
320 | spin_lock(&ubi->wl_lock); | |
321 | ||
322 | if (list_empty(&ubi->works)) { | |
323 | spin_unlock(&ubi->wl_lock); | |
324 | return 0; | |
325 | } | |
326 | ||
327 | wrk = list_entry(ubi->works.next, struct ubi_work, list); | |
328 | list_del(&wrk->list); | |
329 | spin_unlock(&ubi->wl_lock); | |
330 | ||
331 | /* | |
332 | * Call the worker function. Do not touch the work structure | |
333 | * after this call as it will have been freed or reused by that | |
334 | * time by the worker function. | |
335 | */ | |
336 | err = wrk->func(ubi, wrk, 0); | |
337 | if (err) | |
338 | ubi_err("work failed with error code %d", err); | |
339 | ||
340 | spin_lock(&ubi->wl_lock); | |
341 | ubi->works_count -= 1; | |
342 | ubi_assert(ubi->works_count >= 0); | |
343 | spin_unlock(&ubi->wl_lock); | |
344 | return err; | |
345 | } | |
346 | ||
347 | /** | |
348 | * produce_free_peb - produce a free physical eraseblock. | |
349 | * @ubi: UBI device description object | |
350 | * | |
351 | * This function tries to make a free PEB by means of synchronous execution of | |
352 | * pending works. This may be needed if, for example the background thread is | |
353 | * disabled. Returns zero in case of success and a negative error code in case | |
354 | * of failure. | |
355 | */ | |
356 | static int produce_free_peb(struct ubi_device *ubi) | |
357 | { | |
358 | int err; | |
359 | ||
360 | spin_lock(&ubi->wl_lock); | |
361 | while (tree_empty(&ubi->free)) { | |
362 | spin_unlock(&ubi->wl_lock); | |
363 | ||
364 | dbg_wl("do one work synchronously"); | |
365 | err = do_work(ubi); | |
366 | if (err) | |
367 | return err; | |
368 | ||
369 | spin_lock(&ubi->wl_lock); | |
370 | } | |
371 | spin_unlock(&ubi->wl_lock); | |
372 | ||
373 | return 0; | |
374 | } | |
375 | ||
376 | /** | |
377 | * in_wl_tree - check if wear-leveling entry is present in a WL RB-tree. | |
378 | * @e: the wear-leveling entry to check | |
379 | * @root: the root of the tree | |
380 | * | |
381 | * This function returns non-zero if @e is in the @root RB-tree and zero if it | |
382 | * is not. | |
383 | */ | |
384 | static int in_wl_tree(struct ubi_wl_entry *e, struct rb_root *root) | |
385 | { | |
386 | struct rb_node *p; | |
387 | ||
388 | p = root->rb_node; | |
389 | while (p) { | |
390 | struct ubi_wl_entry *e1; | |
391 | ||
392 | e1 = rb_entry(p, struct ubi_wl_entry, rb); | |
393 | ||
394 | if (e->pnum == e1->pnum) { | |
395 | ubi_assert(e == e1); | |
396 | return 1; | |
397 | } | |
398 | ||
399 | if (e->ec < e1->ec) | |
400 | p = p->rb_left; | |
401 | else if (e->ec > e1->ec) | |
402 | p = p->rb_right; | |
403 | else { | |
404 | ubi_assert(e->pnum != e1->pnum); | |
405 | if (e->pnum < e1->pnum) | |
406 | p = p->rb_left; | |
407 | else | |
408 | p = p->rb_right; | |
409 | } | |
410 | } | |
411 | ||
412 | return 0; | |
413 | } | |
414 | ||
415 | /** | |
416 | * prot_tree_add - add physical eraseblock to protection trees. | |
417 | * @ubi: UBI device description object | |
418 | * @e: the physical eraseblock to add | |
419 | * @pe: protection entry object to use | |
420 | * @abs_ec: absolute erase counter value when this physical eraseblock has | |
421 | * to be removed from the protection trees. | |
422 | * | |
423 | * @wl->lock has to be locked. | |
424 | */ | |
425 | static void prot_tree_add(struct ubi_device *ubi, struct ubi_wl_entry *e, | |
426 | struct ubi_wl_prot_entry *pe, int abs_ec) | |
427 | { | |
428 | struct rb_node **p, *parent = NULL; | |
429 | struct ubi_wl_prot_entry *pe1; | |
430 | ||
431 | pe->e = e; | |
432 | pe->abs_ec = ubi->abs_ec + abs_ec; | |
433 | ||
434 | p = &ubi->prot.pnum.rb_node; | |
435 | while (*p) { | |
436 | parent = *p; | |
437 | pe1 = rb_entry(parent, struct ubi_wl_prot_entry, rb_pnum); | |
438 | ||
439 | if (e->pnum < pe1->e->pnum) | |
440 | p = &(*p)->rb_left; | |
441 | else | |
442 | p = &(*p)->rb_right; | |
443 | } | |
444 | rb_link_node(&pe->rb_pnum, parent, p); | |
445 | rb_insert_color(&pe->rb_pnum, &ubi->prot.pnum); | |
446 | ||
447 | p = &ubi->prot.aec.rb_node; | |
448 | parent = NULL; | |
449 | while (*p) { | |
450 | parent = *p; | |
451 | pe1 = rb_entry(parent, struct ubi_wl_prot_entry, rb_aec); | |
452 | ||
453 | if (pe->abs_ec < pe1->abs_ec) | |
454 | p = &(*p)->rb_left; | |
455 | else | |
456 | p = &(*p)->rb_right; | |
457 | } | |
458 | rb_link_node(&pe->rb_aec, parent, p); | |
459 | rb_insert_color(&pe->rb_aec, &ubi->prot.aec); | |
460 | } | |
461 | ||
462 | /** | |
463 | * find_wl_entry - find wear-leveling entry closest to certain erase counter. | |
464 | * @root: the RB-tree where to look for | |
465 | * @max: highest possible erase counter | |
466 | * | |
467 | * This function looks for a wear leveling entry with erase counter closest to | |
468 | * @max and less then @max. | |
469 | */ | |
470 | static struct ubi_wl_entry *find_wl_entry(struct rb_root *root, int max) | |
471 | { | |
472 | struct rb_node *p; | |
473 | struct ubi_wl_entry *e; | |
474 | ||
475 | e = rb_entry(rb_first(root), struct ubi_wl_entry, rb); | |
476 | max += e->ec; | |
477 | ||
478 | p = root->rb_node; | |
479 | while (p) { | |
480 | struct ubi_wl_entry *e1; | |
481 | ||
482 | e1 = rb_entry(p, struct ubi_wl_entry, rb); | |
483 | if (e1->ec >= max) | |
484 | p = p->rb_left; | |
485 | else { | |
486 | p = p->rb_right; | |
487 | e = e1; | |
488 | } | |
489 | } | |
490 | ||
491 | return e; | |
492 | } | |
493 | ||
494 | /** | |
495 | * ubi_wl_get_peb - get a physical eraseblock. | |
496 | * @ubi: UBI device description object | |
497 | * @dtype: type of data which will be stored in this physical eraseblock | |
498 | * | |
499 | * This function returns a physical eraseblock in case of success and a | |
500 | * negative error code in case of failure. Might sleep. | |
501 | */ | |
502 | int ubi_wl_get_peb(struct ubi_device *ubi, int dtype) | |
503 | { | |
504 | int err, protect, medium_ec; | |
505 | struct ubi_wl_entry *e, *first, *last; | |
506 | struct ubi_wl_prot_entry *pe; | |
507 | ||
508 | ubi_assert(dtype == UBI_LONGTERM || dtype == UBI_SHORTTERM || | |
509 | dtype == UBI_UNKNOWN); | |
510 | ||
511 | pe = kmalloc(sizeof(struct ubi_wl_prot_entry), GFP_KERNEL); | |
512 | if (!pe) | |
513 | return -ENOMEM; | |
514 | ||
515 | retry: | |
516 | spin_lock(&ubi->wl_lock); | |
517 | if (tree_empty(&ubi->free)) { | |
518 | if (ubi->works_count == 0) { | |
519 | ubi_assert(list_empty(&ubi->works)); | |
520 | ubi_err("no free eraseblocks"); | |
521 | spin_unlock(&ubi->wl_lock); | |
522 | kfree(pe); | |
523 | return -ENOSPC; | |
524 | } | |
525 | spin_unlock(&ubi->wl_lock); | |
526 | ||
527 | err = produce_free_peb(ubi); | |
528 | if (err < 0) { | |
529 | kfree(pe); | |
530 | return err; | |
531 | } | |
532 | goto retry; | |
533 | } | |
534 | ||
535 | switch (dtype) { | |
536 | case UBI_LONGTERM: | |
537 | /* | |
538 | * For long term data we pick a physical eraseblock | |
539 | * with high erase counter. But the highest erase | |
540 | * counter we can pick is bounded by the the lowest | |
541 | * erase counter plus %WL_FREE_MAX_DIFF. | |
542 | */ | |
543 | e = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF); | |
544 | protect = LT_PROTECTION; | |
545 | break; | |
546 | case UBI_UNKNOWN: | |
547 | /* | |
548 | * For unknown data we pick a physical eraseblock with | |
549 | * medium erase counter. But we by no means can pick a | |
550 | * physical eraseblock with erase counter greater or | |
551 | * equivalent than the lowest erase counter plus | |
552 | * %WL_FREE_MAX_DIFF. | |
553 | */ | |
554 | first = rb_entry(rb_first(&ubi->free), | |
555 | struct ubi_wl_entry, rb); | |
556 | last = rb_entry(rb_last(&ubi->free), | |
557 | struct ubi_wl_entry, rb); | |
558 | ||
559 | if (last->ec - first->ec < WL_FREE_MAX_DIFF) | |
560 | e = rb_entry(ubi->free.rb_node, | |
561 | struct ubi_wl_entry, rb); | |
562 | else { | |
563 | medium_ec = (first->ec + WL_FREE_MAX_DIFF)/2; | |
564 | e = find_wl_entry(&ubi->free, medium_ec); | |
565 | } | |
566 | protect = U_PROTECTION; | |
567 | break; | |
568 | case UBI_SHORTTERM: | |
569 | /* | |
570 | * For short term data we pick a physical eraseblock | |
571 | * with the lowest erase counter as we expect it will | |
572 | * be erased soon. | |
573 | */ | |
574 | e = rb_entry(rb_first(&ubi->free), | |
575 | struct ubi_wl_entry, rb); | |
576 | protect = ST_PROTECTION; | |
577 | break; | |
578 | default: | |
579 | protect = 0; | |
580 | e = NULL; | |
581 | BUG(); | |
582 | } | |
583 | ||
584 | /* | |
585 | * Move the physical eraseblock to the protection trees where it will | |
586 | * be protected from being moved for some time. | |
587 | */ | |
588 | free_tree_del(ubi, e); | |
589 | prot_tree_add(ubi, e, pe, protect); | |
590 | ||
591 | dbg_wl("PEB %d EC %d, protection %d", e->pnum, e->ec, protect); | |
592 | spin_unlock(&ubi->wl_lock); | |
593 | ||
594 | return e->pnum; | |
595 | } | |
596 | ||
597 | /** | |
598 | * prot_tree_del - remove a physical eraseblock from the protection trees | |
599 | * @ubi: UBI device description object | |
600 | * @pnum: the physical eraseblock to remove | |
601 | */ | |
602 | static void prot_tree_del(struct ubi_device *ubi, int pnum) | |
603 | { | |
604 | struct rb_node *p; | |
605 | struct ubi_wl_prot_entry *pe = NULL; | |
606 | ||
607 | p = ubi->prot.pnum.rb_node; | |
608 | while (p) { | |
609 | ||
610 | pe = rb_entry(p, struct ubi_wl_prot_entry, rb_pnum); | |
611 | ||
612 | if (pnum == pe->e->pnum) | |
613 | break; | |
614 | ||
615 | if (pnum < pe->e->pnum) | |
616 | p = p->rb_left; | |
617 | else | |
618 | p = p->rb_right; | |
619 | } | |
620 | ||
621 | ubi_assert(pe->e->pnum == pnum); | |
622 | rb_erase(&pe->rb_aec, &ubi->prot.aec); | |
623 | rb_erase(&pe->rb_pnum, &ubi->prot.pnum); | |
624 | kfree(pe); | |
625 | } | |
626 | ||
627 | /** | |
628 | * sync_erase - synchronously erase a physical eraseblock. | |
629 | * @ubi: UBI device description object | |
630 | * @e: the the physical eraseblock to erase | |
631 | * @torture: if the physical eraseblock has to be tortured | |
632 | * | |
633 | * This function returns zero in case of success and a negative error code in | |
634 | * case of failure. | |
635 | */ | |
636 | static int sync_erase(struct ubi_device *ubi, struct ubi_wl_entry *e, int torture) | |
637 | { | |
638 | int err; | |
639 | struct ubi_ec_hdr *ec_hdr; | |
640 | unsigned long long ec = e->ec; | |
641 | ||
642 | dbg_wl("erase PEB %d, old EC %llu", e->pnum, ec); | |
643 | ||
644 | err = paranoid_check_ec(ubi, e->pnum, e->ec); | |
645 | if (err > 0) | |
646 | return -EINVAL; | |
647 | ||
648 | ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL); | |
649 | if (!ec_hdr) | |
650 | return -ENOMEM; | |
651 | ||
652 | err = ubi_io_sync_erase(ubi, e->pnum, torture); | |
653 | if (err < 0) | |
654 | goto out_free; | |
655 | ||
656 | ec += err; | |
657 | if (ec > UBI_MAX_ERASECOUNTER) { | |
658 | /* | |
659 | * Erase counter overflow. Upgrade UBI and use 64-bit | |
660 | * erase counters internally. | |
661 | */ | |
662 | ubi_err("erase counter overflow at PEB %d, EC %llu", | |
663 | e->pnum, ec); | |
664 | err = -EINVAL; | |
665 | goto out_free; | |
666 | } | |
667 | ||
668 | dbg_wl("erased PEB %d, new EC %llu", e->pnum, ec); | |
669 | ||
3261ebd7 | 670 | ec_hdr->ec = cpu_to_be64(ec); |
801c135c AB |
671 | |
672 | err = ubi_io_write_ec_hdr(ubi, e->pnum, ec_hdr); | |
673 | if (err) | |
674 | goto out_free; | |
675 | ||
676 | e->ec = ec; | |
677 | spin_lock(&ubi->wl_lock); | |
678 | if (e->ec > ubi->max_ec) | |
679 | ubi->max_ec = e->ec; | |
680 | spin_unlock(&ubi->wl_lock); | |
681 | ||
682 | out_free: | |
683 | kfree(ec_hdr); | |
684 | return err; | |
685 | } | |
686 | ||
687 | /** | |
688 | * check_protection_over - check if it is time to stop protecting some | |
689 | * physical eraseblocks. | |
690 | * @ubi: UBI device description object | |
691 | * | |
692 | * This function is called after each erase operation, when the absolute erase | |
693 | * counter is incremented, to check if some physical eraseblock have not to be | |
694 | * protected any longer. These physical eraseblocks are moved from the | |
695 | * protection trees to the used tree. | |
696 | */ | |
697 | static void check_protection_over(struct ubi_device *ubi) | |
698 | { | |
699 | struct ubi_wl_prot_entry *pe; | |
700 | ||
701 | /* | |
702 | * There may be several protected physical eraseblock to remove, | |
703 | * process them all. | |
704 | */ | |
705 | while (1) { | |
706 | spin_lock(&ubi->wl_lock); | |
707 | if (tree_empty(&ubi->prot.aec)) { | |
708 | spin_unlock(&ubi->wl_lock); | |
709 | break; | |
710 | } | |
711 | ||
712 | pe = rb_entry(rb_first(&ubi->prot.aec), | |
713 | struct ubi_wl_prot_entry, rb_aec); | |
714 | ||
715 | if (pe->abs_ec > ubi->abs_ec) { | |
716 | spin_unlock(&ubi->wl_lock); | |
717 | break; | |
718 | } | |
719 | ||
720 | dbg_wl("PEB %d protection over, abs_ec %llu, PEB abs_ec %llu", | |
721 | pe->e->pnum, ubi->abs_ec, pe->abs_ec); | |
722 | rb_erase(&pe->rb_aec, &ubi->prot.aec); | |
723 | rb_erase(&pe->rb_pnum, &ubi->prot.pnum); | |
724 | used_tree_add(ubi, pe->e); | |
725 | spin_unlock(&ubi->wl_lock); | |
726 | ||
727 | kfree(pe); | |
728 | cond_resched(); | |
729 | } | |
730 | } | |
731 | ||
732 | /** | |
733 | * schedule_ubi_work - schedule a work. | |
734 | * @ubi: UBI device description object | |
735 | * @wrk: the work to schedule | |
736 | * | |
737 | * This function enqueues a work defined by @wrk to the tail of the pending | |
738 | * works list. | |
739 | */ | |
740 | static void schedule_ubi_work(struct ubi_device *ubi, struct ubi_work *wrk) | |
741 | { | |
742 | spin_lock(&ubi->wl_lock); | |
743 | list_add_tail(&wrk->list, &ubi->works); | |
744 | ubi_assert(ubi->works_count >= 0); | |
745 | ubi->works_count += 1; | |
746 | if (ubi->thread_enabled) | |
747 | wake_up_process(ubi->bgt_thread); | |
748 | spin_unlock(&ubi->wl_lock); | |
749 | } | |
750 | ||
751 | static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, | |
752 | int cancel); | |
753 | ||
754 | /** | |
755 | * schedule_erase - schedule an erase work. | |
756 | * @ubi: UBI device description object | |
757 | * @e: the WL entry of the physical eraseblock to erase | |
758 | * @torture: if the physical eraseblock has to be tortured | |
759 | * | |
760 | * This function returns zero in case of success and a %-ENOMEM in case of | |
761 | * failure. | |
762 | */ | |
763 | static int schedule_erase(struct ubi_device *ubi, struct ubi_wl_entry *e, | |
764 | int torture) | |
765 | { | |
766 | struct ubi_work *wl_wrk; | |
767 | ||
768 | dbg_wl("schedule erasure of PEB %d, EC %d, torture %d", | |
769 | e->pnum, e->ec, torture); | |
770 | ||
771 | wl_wrk = kmalloc(sizeof(struct ubi_work), GFP_KERNEL); | |
772 | if (!wl_wrk) | |
773 | return -ENOMEM; | |
774 | ||
775 | wl_wrk->func = &erase_worker; | |
776 | wl_wrk->e = e; | |
777 | wl_wrk->torture = torture; | |
778 | ||
779 | schedule_ubi_work(ubi, wl_wrk); | |
780 | return 0; | |
781 | } | |
782 | ||
783 | /** | |
784 | * wear_leveling_worker - wear-leveling worker function. | |
785 | * @ubi: UBI device description object | |
786 | * @wrk: the work object | |
787 | * @cancel: non-zero if the worker has to free memory and exit | |
788 | * | |
789 | * This function copies a more worn out physical eraseblock to a less worn out | |
790 | * one. Returns zero in case of success and a negative error code in case of | |
791 | * failure. | |
792 | */ | |
793 | static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk, | |
794 | int cancel) | |
795 | { | |
796 | int err, put = 0; | |
797 | struct ubi_wl_entry *e1, *e2; | |
798 | struct ubi_vid_hdr *vid_hdr; | |
799 | ||
800 | kfree(wrk); | |
801 | ||
802 | if (cancel) | |
803 | return 0; | |
804 | ||
805 | vid_hdr = ubi_zalloc_vid_hdr(ubi); | |
806 | if (!vid_hdr) | |
807 | return -ENOMEM; | |
808 | ||
809 | spin_lock(&ubi->wl_lock); | |
810 | ||
811 | /* | |
812 | * Only one WL worker at a time is supported at this implementation, so | |
813 | * make sure a PEB is not being moved already. | |
814 | */ | |
815 | if (ubi->move_to || tree_empty(&ubi->free) || | |
816 | (tree_empty(&ubi->used) && tree_empty(&ubi->scrub))) { | |
817 | /* | |
818 | * Only one WL worker at a time is supported at this | |
819 | * implementation, so if a LEB is already being moved, cancel. | |
820 | * | |
821 | * No free physical eraseblocks? Well, we cancel wear-leveling | |
822 | * then. It will be triggered again when a free physical | |
823 | * eraseblock appears. | |
824 | * | |
825 | * No used physical eraseblocks? They must be temporarily | |
826 | * protected from being moved. They will be moved to the | |
827 | * @ubi->used tree later and the wear-leveling will be | |
828 | * triggered again. | |
829 | */ | |
830 | dbg_wl("cancel WL, a list is empty: free %d, used %d", | |
831 | tree_empty(&ubi->free), tree_empty(&ubi->used)); | |
832 | ubi->wl_scheduled = 0; | |
833 | spin_unlock(&ubi->wl_lock); | |
834 | ubi_free_vid_hdr(ubi, vid_hdr); | |
835 | return 0; | |
836 | } | |
837 | ||
838 | if (tree_empty(&ubi->scrub)) { | |
839 | /* | |
840 | * Now pick the least worn-out used physical eraseblock and a | |
841 | * highly worn-out free physical eraseblock. If the erase | |
842 | * counters differ much enough, start wear-leveling. | |
843 | */ | |
844 | e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, rb); | |
845 | e2 = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF); | |
846 | ||
847 | if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) { | |
848 | dbg_wl("no WL needed: min used EC %d, max free EC %d", | |
849 | e1->ec, e2->ec); | |
850 | ubi->wl_scheduled = 0; | |
851 | spin_unlock(&ubi->wl_lock); | |
852 | ubi_free_vid_hdr(ubi, vid_hdr); | |
853 | return 0; | |
854 | } | |
855 | used_tree_del(ubi, e1); | |
856 | dbg_wl("move PEB %d EC %d to PEB %d EC %d", | |
857 | e1->pnum, e1->ec, e2->pnum, e2->ec); | |
858 | } else { | |
859 | e1 = rb_entry(rb_first(&ubi->scrub), struct ubi_wl_entry, rb); | |
860 | e2 = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF); | |
861 | scrub_tree_del(ubi, e1); | |
862 | dbg_wl("scrub PEB %d to PEB %d", e1->pnum, e2->pnum); | |
863 | } | |
864 | ||
865 | free_tree_del(ubi, e2); | |
866 | ubi_assert(!ubi->move_from && !ubi->move_to); | |
867 | ubi_assert(!ubi->move_to_put && !ubi->move_from_put); | |
868 | ubi->move_from = e1; | |
869 | ubi->move_to = e2; | |
870 | spin_unlock(&ubi->wl_lock); | |
871 | ||
872 | /* | |
873 | * Now we are going to copy physical eraseblock @e1->pnum to @e2->pnum. | |
874 | * We so far do not know which logical eraseblock our physical | |
875 | * eraseblock (@e1) belongs to. We have to read the volume identifier | |
876 | * header first. | |
877 | */ | |
878 | ||
879 | err = ubi_io_read_vid_hdr(ubi, e1->pnum, vid_hdr, 0); | |
880 | if (err && err != UBI_IO_BITFLIPS) { | |
881 | if (err == UBI_IO_PEB_FREE) { | |
882 | /* | |
883 | * We are trying to move PEB without a VID header. UBI | |
884 | * always write VID headers shortly after the PEB was | |
885 | * given, so we have a situation when it did not have | |
886 | * chance to write it down because it was preempted. | |
887 | * Just re-schedule the work, so that next time it will | |
888 | * likely have the VID header in place. | |
889 | */ | |
890 | dbg_wl("PEB %d has no VID header", e1->pnum); | |
891 | err = 0; | |
892 | } else { | |
893 | ubi_err("error %d while reading VID header from PEB %d", | |
894 | err, e1->pnum); | |
895 | if (err > 0) | |
896 | err = -EIO; | |
897 | } | |
898 | goto error; | |
899 | } | |
900 | ||
901 | err = ubi_eba_copy_leb(ubi, e1->pnum, e2->pnum, vid_hdr); | |
902 | if (err) { | |
903 | if (err == UBI_IO_BITFLIPS) | |
904 | err = 0; | |
905 | goto error; | |
906 | } | |
907 | ||
908 | ubi_free_vid_hdr(ubi, vid_hdr); | |
909 | spin_lock(&ubi->wl_lock); | |
910 | if (!ubi->move_to_put) | |
911 | used_tree_add(ubi, e2); | |
912 | else | |
913 | put = 1; | |
914 | ubi->move_from = ubi->move_to = NULL; | |
915 | ubi->move_from_put = ubi->move_to_put = 0; | |
916 | ubi->wl_scheduled = 0; | |
917 | spin_unlock(&ubi->wl_lock); | |
918 | ||
919 | if (put) { | |
920 | /* | |
921 | * Well, the target PEB was put meanwhile, schedule it for | |
922 | * erasure. | |
923 | */ | |
924 | dbg_wl("PEB %d was put meanwhile, erase", e2->pnum); | |
925 | err = schedule_erase(ubi, e2, 0); | |
926 | if (err) { | |
927 | kmem_cache_free(wl_entries_slab, e2); | |
928 | ubi_ro_mode(ubi); | |
929 | } | |
930 | } | |
931 | ||
932 | err = schedule_erase(ubi, e1, 0); | |
933 | if (err) { | |
934 | kmem_cache_free(wl_entries_slab, e1); | |
935 | ubi_ro_mode(ubi); | |
936 | } | |
937 | ||
938 | dbg_wl("done"); | |
939 | return err; | |
940 | ||
941 | /* | |
942 | * Some error occurred. @e1 was not changed, so return it back. @e2 | |
943 | * might be changed, schedule it for erasure. | |
944 | */ | |
945 | error: | |
946 | if (err) | |
947 | dbg_wl("error %d occurred, cancel operation", err); | |
948 | ubi_assert(err <= 0); | |
949 | ||
950 | ubi_free_vid_hdr(ubi, vid_hdr); | |
951 | spin_lock(&ubi->wl_lock); | |
952 | ubi->wl_scheduled = 0; | |
953 | if (ubi->move_from_put) | |
954 | put = 1; | |
955 | else | |
956 | used_tree_add(ubi, e1); | |
957 | ubi->move_from = ubi->move_to = NULL; | |
958 | ubi->move_from_put = ubi->move_to_put = 0; | |
959 | spin_unlock(&ubi->wl_lock); | |
960 | ||
961 | if (put) { | |
962 | /* | |
963 | * Well, the target PEB was put meanwhile, schedule it for | |
964 | * erasure. | |
965 | */ | |
966 | dbg_wl("PEB %d was put meanwhile, erase", e1->pnum); | |
967 | err = schedule_erase(ubi, e1, 0); | |
968 | if (err) { | |
969 | kmem_cache_free(wl_entries_slab, e1); | |
970 | ubi_ro_mode(ubi); | |
971 | } | |
972 | } | |
973 | ||
974 | err = schedule_erase(ubi, e2, 0); | |
975 | if (err) { | |
976 | kmem_cache_free(wl_entries_slab, e2); | |
977 | ubi_ro_mode(ubi); | |
978 | } | |
979 | ||
980 | yield(); | |
981 | return err; | |
982 | } | |
983 | ||
984 | /** | |
985 | * ensure_wear_leveling - schedule wear-leveling if it is needed. | |
986 | * @ubi: UBI device description object | |
987 | * | |
988 | * This function checks if it is time to start wear-leveling and schedules it | |
989 | * if yes. This function returns zero in case of success and a negative error | |
990 | * code in case of failure. | |
991 | */ | |
992 | static int ensure_wear_leveling(struct ubi_device *ubi) | |
993 | { | |
994 | int err = 0; | |
995 | struct ubi_wl_entry *e1; | |
996 | struct ubi_wl_entry *e2; | |
997 | struct ubi_work *wrk; | |
998 | ||
999 | spin_lock(&ubi->wl_lock); | |
1000 | if (ubi->wl_scheduled) | |
1001 | /* Wear-leveling is already in the work queue */ | |
1002 | goto out_unlock; | |
1003 | ||
1004 | /* | |
1005 | * If the ubi->scrub tree is not empty, scrubbing is needed, and the | |
1006 | * the WL worker has to be scheduled anyway. | |
1007 | */ | |
1008 | if (tree_empty(&ubi->scrub)) { | |
1009 | if (tree_empty(&ubi->used) || tree_empty(&ubi->free)) | |
1010 | /* No physical eraseblocks - no deal */ | |
1011 | goto out_unlock; | |
1012 | ||
1013 | /* | |
1014 | * We schedule wear-leveling only if the difference between the | |
1015 | * lowest erase counter of used physical eraseblocks and a high | |
1016 | * erase counter of free physical eraseblocks is greater then | |
1017 | * %UBI_WL_THRESHOLD. | |
1018 | */ | |
1019 | e1 = rb_entry(rb_first(&ubi->used), struct ubi_wl_entry, rb); | |
1020 | e2 = find_wl_entry(&ubi->free, WL_FREE_MAX_DIFF); | |
1021 | ||
1022 | if (!(e2->ec - e1->ec >= UBI_WL_THRESHOLD)) | |
1023 | goto out_unlock; | |
1024 | dbg_wl("schedule wear-leveling"); | |
1025 | } else | |
1026 | dbg_wl("schedule scrubbing"); | |
1027 | ||
1028 | ubi->wl_scheduled = 1; | |
1029 | spin_unlock(&ubi->wl_lock); | |
1030 | ||
1031 | wrk = kmalloc(sizeof(struct ubi_work), GFP_KERNEL); | |
1032 | if (!wrk) { | |
1033 | err = -ENOMEM; | |
1034 | goto out_cancel; | |
1035 | } | |
1036 | ||
1037 | wrk->func = &wear_leveling_worker; | |
1038 | schedule_ubi_work(ubi, wrk); | |
1039 | return err; | |
1040 | ||
1041 | out_cancel: | |
1042 | spin_lock(&ubi->wl_lock); | |
1043 | ubi->wl_scheduled = 0; | |
1044 | out_unlock: | |
1045 | spin_unlock(&ubi->wl_lock); | |
1046 | return err; | |
1047 | } | |
1048 | ||
1049 | /** | |
1050 | * erase_worker - physical eraseblock erase worker function. | |
1051 | * @ubi: UBI device description object | |
1052 | * @wl_wrk: the work object | |
1053 | * @cancel: non-zero if the worker has to free memory and exit | |
1054 | * | |
1055 | * This function erases a physical eraseblock and perform torture testing if | |
1056 | * needed. It also takes care about marking the physical eraseblock bad if | |
1057 | * needed. Returns zero in case of success and a negative error code in case of | |
1058 | * failure. | |
1059 | */ | |
1060 | static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk, | |
1061 | int cancel) | |
1062 | { | |
801c135c | 1063 | struct ubi_wl_entry *e = wl_wrk->e; |
784c1454 | 1064 | int pnum = e->pnum, err, need; |
801c135c AB |
1065 | |
1066 | if (cancel) { | |
1067 | dbg_wl("cancel erasure of PEB %d EC %d", pnum, e->ec); | |
1068 | kfree(wl_wrk); | |
1069 | kmem_cache_free(wl_entries_slab, e); | |
1070 | return 0; | |
1071 | } | |
1072 | ||
1073 | dbg_wl("erase PEB %d EC %d", pnum, e->ec); | |
1074 | ||
1075 | err = sync_erase(ubi, e, wl_wrk->torture); | |
1076 | if (!err) { | |
1077 | /* Fine, we've erased it successfully */ | |
1078 | kfree(wl_wrk); | |
1079 | ||
1080 | spin_lock(&ubi->wl_lock); | |
1081 | ubi->abs_ec += 1; | |
1082 | free_tree_add(ubi, e); | |
1083 | spin_unlock(&ubi->wl_lock); | |
1084 | ||
1085 | /* | |
1086 | * One more erase operation has happened, take care about protected | |
1087 | * physical eraseblocks. | |
1088 | */ | |
1089 | check_protection_over(ubi); | |
1090 | ||
1091 | /* And take care about wear-leveling */ | |
1092 | err = ensure_wear_leveling(ubi); | |
1093 | return err; | |
1094 | } | |
1095 | ||
8d2d4011 | 1096 | ubi_err("failed to erase PEB %d, error %d", pnum, err); |
801c135c AB |
1097 | kfree(wl_wrk); |
1098 | kmem_cache_free(wl_entries_slab, e); | |
1099 | ||
784c1454 AB |
1100 | if (err == -EINTR || err == -ENOMEM || err == -EAGAIN || |
1101 | err == -EBUSY) { | |
1102 | int err1; | |
1103 | ||
1104 | /* Re-schedule the LEB for erasure */ | |
1105 | err1 = schedule_erase(ubi, e, 0); | |
1106 | if (err1) { | |
1107 | err = err1; | |
1108 | goto out_ro; | |
1109 | } | |
1110 | return err; | |
1111 | } else if (err != -EIO) { | |
801c135c AB |
1112 | /* |
1113 | * If this is not %-EIO, we have no idea what to do. Scheduling | |
1114 | * this physical eraseblock for erasure again would cause | |
1115 | * errors again and again. Well, lets switch to RO mode. | |
1116 | */ | |
784c1454 | 1117 | goto out_ro; |
801c135c AB |
1118 | } |
1119 | ||
1120 | /* It is %-EIO, the PEB went bad */ | |
1121 | ||
1122 | if (!ubi->bad_allowed) { | |
1123 | ubi_err("bad physical eraseblock %d detected", pnum); | |
784c1454 AB |
1124 | goto out_ro; |
1125 | } | |
801c135c | 1126 | |
784c1454 AB |
1127 | spin_lock(&ubi->volumes_lock); |
1128 | need = ubi->beb_rsvd_level - ubi->beb_rsvd_pebs + 1; | |
1129 | if (need > 0) { | |
1130 | need = ubi->avail_pebs >= need ? need : ubi->avail_pebs; | |
1131 | ubi->avail_pebs -= need; | |
1132 | ubi->rsvd_pebs += need; | |
1133 | ubi->beb_rsvd_pebs += need; | |
1134 | if (need > 0) | |
1135 | ubi_msg("reserve more %d PEBs", need); | |
1136 | } | |
801c135c | 1137 | |
784c1454 | 1138 | if (ubi->beb_rsvd_pebs == 0) { |
801c135c | 1139 | spin_unlock(&ubi->volumes_lock); |
784c1454 AB |
1140 | ubi_err("no reserved physical eraseblocks"); |
1141 | goto out_ro; | |
1142 | } | |
801c135c | 1143 | |
784c1454 AB |
1144 | spin_unlock(&ubi->volumes_lock); |
1145 | ubi_msg("mark PEB %d as bad", pnum); | |
801c135c | 1146 | |
784c1454 AB |
1147 | err = ubi_io_mark_bad(ubi, pnum); |
1148 | if (err) | |
1149 | goto out_ro; | |
1150 | ||
1151 | spin_lock(&ubi->volumes_lock); | |
1152 | ubi->beb_rsvd_pebs -= 1; | |
1153 | ubi->bad_peb_count += 1; | |
1154 | ubi->good_peb_count -= 1; | |
1155 | ubi_calculate_reserved(ubi); | |
1156 | if (ubi->beb_rsvd_pebs == 0) | |
1157 | ubi_warn("last PEB from the reserved pool was used"); | |
1158 | spin_unlock(&ubi->volumes_lock); | |
1159 | ||
1160 | return err; | |
801c135c | 1161 | |
784c1454 AB |
1162 | out_ro: |
1163 | ubi_ro_mode(ubi); | |
801c135c AB |
1164 | return err; |
1165 | } | |
1166 | ||
1167 | /** | |
1168 | * ubi_wl_put_peb - return a physical eraseblock to the wear-leveling | |
1169 | * unit. | |
1170 | * @ubi: UBI device description object | |
1171 | * @pnum: physical eraseblock to return | |
1172 | * @torture: if this physical eraseblock has to be tortured | |
1173 | * | |
1174 | * This function is called to return physical eraseblock @pnum to the pool of | |
1175 | * free physical eraseblocks. The @torture flag has to be set if an I/O error | |
1176 | * occurred to this @pnum and it has to be tested. This function returns zero | |
1177 | * in case of success and a negative error code in case of failure. | |
1178 | */ | |
1179 | int ubi_wl_put_peb(struct ubi_device *ubi, int pnum, int torture) | |
1180 | { | |
1181 | int err; | |
1182 | struct ubi_wl_entry *e; | |
1183 | ||
1184 | dbg_wl("PEB %d", pnum); | |
1185 | ubi_assert(pnum >= 0); | |
1186 | ubi_assert(pnum < ubi->peb_count); | |
1187 | ||
1188 | spin_lock(&ubi->wl_lock); | |
1189 | ||
1190 | e = ubi->lookuptbl[pnum]; | |
1191 | if (e == ubi->move_from) { | |
1192 | /* | |
1193 | * User is putting the physical eraseblock which was selected to | |
1194 | * be moved. It will be scheduled for erasure in the | |
1195 | * wear-leveling worker. | |
1196 | */ | |
1197 | dbg_wl("PEB %d is being moved", pnum); | |
1198 | ubi_assert(!ubi->move_from_put); | |
1199 | ubi->move_from_put = 1; | |
1200 | spin_unlock(&ubi->wl_lock); | |
1201 | return 0; | |
1202 | } else if (e == ubi->move_to) { | |
1203 | /* | |
1204 | * User is putting the physical eraseblock which was selected | |
1205 | * as the target the data is moved to. It may happen if the EBA | |
1206 | * unit already re-mapped the LEB but the WL unit did has not | |
1207 | * put the PEB to the "used" tree. | |
1208 | */ | |
1209 | dbg_wl("PEB %d is the target of data moving", pnum); | |
1210 | ubi_assert(!ubi->move_to_put); | |
1211 | ubi->move_to_put = 1; | |
1212 | spin_unlock(&ubi->wl_lock); | |
1213 | return 0; | |
1214 | } else { | |
1215 | if (in_wl_tree(e, &ubi->used)) | |
1216 | used_tree_del(ubi, e); | |
1217 | else if (in_wl_tree(e, &ubi->scrub)) | |
1218 | scrub_tree_del(ubi, e); | |
1219 | else | |
1220 | prot_tree_del(ubi, e->pnum); | |
1221 | } | |
1222 | spin_unlock(&ubi->wl_lock); | |
1223 | ||
1224 | err = schedule_erase(ubi, e, torture); | |
1225 | if (err) { | |
1226 | spin_lock(&ubi->wl_lock); | |
1227 | used_tree_add(ubi, e); | |
1228 | spin_unlock(&ubi->wl_lock); | |
1229 | } | |
1230 | ||
1231 | return err; | |
1232 | } | |
1233 | ||
1234 | /** | |
1235 | * ubi_wl_scrub_peb - schedule a physical eraseblock for scrubbing. | |
1236 | * @ubi: UBI device description object | |
1237 | * @pnum: the physical eraseblock to schedule | |
1238 | * | |
1239 | * If a bit-flip in a physical eraseblock is detected, this physical eraseblock | |
1240 | * needs scrubbing. This function schedules a physical eraseblock for | |
1241 | * scrubbing which is done in background. This function returns zero in case of | |
1242 | * success and a negative error code in case of failure. | |
1243 | */ | |
1244 | int ubi_wl_scrub_peb(struct ubi_device *ubi, int pnum) | |
1245 | { | |
1246 | struct ubi_wl_entry *e; | |
1247 | ||
1248 | ubi_msg("schedule PEB %d for scrubbing", pnum); | |
1249 | ||
1250 | retry: | |
1251 | spin_lock(&ubi->wl_lock); | |
1252 | e = ubi->lookuptbl[pnum]; | |
1253 | if (e == ubi->move_from || in_wl_tree(e, &ubi->scrub)) { | |
1254 | spin_unlock(&ubi->wl_lock); | |
1255 | return 0; | |
1256 | } | |
1257 | ||
1258 | if (e == ubi->move_to) { | |
1259 | /* | |
1260 | * This physical eraseblock was used to move data to. The data | |
1261 | * was moved but the PEB was not yet inserted to the proper | |
1262 | * tree. We should just wait a little and let the WL worker | |
1263 | * proceed. | |
1264 | */ | |
1265 | spin_unlock(&ubi->wl_lock); | |
1266 | dbg_wl("the PEB %d is not in proper tree, retry", pnum); | |
1267 | yield(); | |
1268 | goto retry; | |
1269 | } | |
1270 | ||
1271 | if (in_wl_tree(e, &ubi->used)) | |
1272 | used_tree_del(ubi, e); | |
1273 | else | |
1274 | prot_tree_del(ubi, pnum); | |
1275 | ||
1276 | scrub_tree_add(ubi, e); | |
1277 | spin_unlock(&ubi->wl_lock); | |
1278 | ||
1279 | /* | |
1280 | * Technically scrubbing is the same as wear-leveling, so it is done | |
1281 | * by the WL worker. | |
1282 | */ | |
1283 | return ensure_wear_leveling(ubi); | |
1284 | } | |
1285 | ||
1286 | /** | |
1287 | * ubi_wl_flush - flush all pending works. | |
1288 | * @ubi: UBI device description object | |
1289 | * | |
1290 | * This function returns zero in case of success and a negative error code in | |
1291 | * case of failure. | |
1292 | */ | |
1293 | int ubi_wl_flush(struct ubi_device *ubi) | |
1294 | { | |
1295 | int err, pending_count; | |
1296 | ||
1297 | pending_count = ubi->works_count; | |
1298 | ||
1299 | dbg_wl("flush (%d pending works)", pending_count); | |
1300 | ||
1301 | /* | |
1302 | * Erase while the pending works queue is not empty, but not more then | |
1303 | * the number of currently pending works. | |
1304 | */ | |
1305 | while (pending_count-- > 0) { | |
1306 | err = do_work(ubi); | |
1307 | if (err) | |
1308 | return err; | |
1309 | } | |
1310 | ||
1311 | return 0; | |
1312 | } | |
1313 | ||
1314 | /** | |
1315 | * tree_destroy - destroy an RB-tree. | |
1316 | * @root: the root of the tree to destroy | |
1317 | */ | |
1318 | static void tree_destroy(struct rb_root *root) | |
1319 | { | |
1320 | struct rb_node *rb; | |
1321 | struct ubi_wl_entry *e; | |
1322 | ||
1323 | rb = root->rb_node; | |
1324 | while (rb) { | |
1325 | if (rb->rb_left) | |
1326 | rb = rb->rb_left; | |
1327 | else if (rb->rb_right) | |
1328 | rb = rb->rb_right; | |
1329 | else { | |
1330 | e = rb_entry(rb, struct ubi_wl_entry, rb); | |
1331 | ||
1332 | rb = rb_parent(rb); | |
1333 | if (rb) { | |
1334 | if (rb->rb_left == &e->rb) | |
1335 | rb->rb_left = NULL; | |
1336 | else | |
1337 | rb->rb_right = NULL; | |
1338 | } | |
1339 | ||
1340 | kmem_cache_free(wl_entries_slab, e); | |
1341 | } | |
1342 | } | |
1343 | } | |
1344 | ||
1345 | /** | |
1346 | * ubi_thread - UBI background thread. | |
1347 | * @u: the UBI device description object pointer | |
1348 | */ | |
1349 | static int ubi_thread(void *u) | |
1350 | { | |
1351 | int failures = 0; | |
1352 | struct ubi_device *ubi = u; | |
1353 | ||
1354 | ubi_msg("background thread \"%s\" started, PID %d", | |
1355 | ubi->bgt_name, current->pid); | |
1356 | ||
83144186 | 1357 | set_freezable(); |
801c135c AB |
1358 | for (;;) { |
1359 | int err; | |
1360 | ||
1361 | if (kthread_should_stop()) | |
1362 | goto out; | |
1363 | ||
1364 | if (try_to_freeze()) | |
1365 | continue; | |
1366 | ||
1367 | spin_lock(&ubi->wl_lock); | |
1368 | if (list_empty(&ubi->works) || ubi->ro_mode || | |
1369 | !ubi->thread_enabled) { | |
1370 | set_current_state(TASK_INTERRUPTIBLE); | |
1371 | spin_unlock(&ubi->wl_lock); | |
1372 | schedule(); | |
1373 | continue; | |
1374 | } | |
1375 | spin_unlock(&ubi->wl_lock); | |
1376 | ||
1377 | err = do_work(ubi); | |
1378 | if (err) { | |
1379 | ubi_err("%s: work failed with error code %d", | |
1380 | ubi->bgt_name, err); | |
1381 | if (failures++ > WL_MAX_FAILURES) { | |
1382 | /* | |
1383 | * Too many failures, disable the thread and | |
1384 | * switch to read-only mode. | |
1385 | */ | |
1386 | ubi_msg("%s: %d consecutive failures", | |
1387 | ubi->bgt_name, WL_MAX_FAILURES); | |
1388 | ubi_ro_mode(ubi); | |
1389 | break; | |
1390 | } | |
1391 | } else | |
1392 | failures = 0; | |
1393 | ||
1394 | cond_resched(); | |
1395 | } | |
1396 | ||
1397 | out: | |
1398 | dbg_wl("background thread \"%s\" is killed", ubi->bgt_name); | |
1399 | return 0; | |
1400 | } | |
1401 | ||
1402 | /** | |
1403 | * cancel_pending - cancel all pending works. | |
1404 | * @ubi: UBI device description object | |
1405 | */ | |
1406 | static void cancel_pending(struct ubi_device *ubi) | |
1407 | { | |
1408 | while (!list_empty(&ubi->works)) { | |
1409 | struct ubi_work *wrk; | |
1410 | ||
1411 | wrk = list_entry(ubi->works.next, struct ubi_work, list); | |
1412 | list_del(&wrk->list); | |
1413 | wrk->func(ubi, wrk, 1); | |
1414 | ubi->works_count -= 1; | |
1415 | ubi_assert(ubi->works_count >= 0); | |
1416 | } | |
1417 | } | |
1418 | ||
1419 | /** | |
1420 | * ubi_wl_init_scan - initialize the wear-leveling unit using scanning | |
1421 | * information. | |
1422 | * @ubi: UBI device description object | |
1423 | * @si: scanning information | |
1424 | * | |
1425 | * This function returns zero in case of success, and a negative error code in | |
1426 | * case of failure. | |
1427 | */ | |
1428 | int ubi_wl_init_scan(struct ubi_device *ubi, struct ubi_scan_info *si) | |
1429 | { | |
1430 | int err; | |
1431 | struct rb_node *rb1, *rb2; | |
1432 | struct ubi_scan_volume *sv; | |
1433 | struct ubi_scan_leb *seb, *tmp; | |
1434 | struct ubi_wl_entry *e; | |
1435 | ||
1436 | ||
1437 | ubi->used = ubi->free = ubi->scrub = RB_ROOT; | |
1438 | ubi->prot.pnum = ubi->prot.aec = RB_ROOT; | |
1439 | spin_lock_init(&ubi->wl_lock); | |
1440 | ubi->max_ec = si->max_ec; | |
1441 | INIT_LIST_HEAD(&ubi->works); | |
1442 | ||
1443 | sprintf(ubi->bgt_name, UBI_BGT_NAME_PATTERN, ubi->ubi_num); | |
1444 | ||
1445 | ubi->bgt_thread = kthread_create(ubi_thread, ubi, ubi->bgt_name); | |
1446 | if (IS_ERR(ubi->bgt_thread)) { | |
1447 | err = PTR_ERR(ubi->bgt_thread); | |
1448 | ubi_err("cannot spawn \"%s\", error %d", ubi->bgt_name, | |
1449 | err); | |
1450 | return err; | |
1451 | } | |
1452 | ||
1453 | if (ubi_devices_cnt == 0) { | |
1454 | wl_entries_slab = kmem_cache_create("ubi_wl_entry_slab", | |
1455 | sizeof(struct ubi_wl_entry), | |
20c2df83 | 1456 | 0, 0, NULL); |
801c135c AB |
1457 | if (!wl_entries_slab) |
1458 | return -ENOMEM; | |
1459 | } | |
1460 | ||
1461 | err = -ENOMEM; | |
1462 | ubi->lookuptbl = kzalloc(ubi->peb_count * sizeof(void *), GFP_KERNEL); | |
1463 | if (!ubi->lookuptbl) | |
1464 | goto out_free; | |
1465 | ||
1466 | list_for_each_entry_safe(seb, tmp, &si->erase, u.list) { | |
1467 | cond_resched(); | |
1468 | ||
1469 | e = kmem_cache_alloc(wl_entries_slab, GFP_KERNEL); | |
1470 | if (!e) | |
1471 | goto out_free; | |
1472 | ||
1473 | e->pnum = seb->pnum; | |
1474 | e->ec = seb->ec; | |
1475 | ubi->lookuptbl[e->pnum] = e; | |
1476 | if (schedule_erase(ubi, e, 0)) { | |
1477 | kmem_cache_free(wl_entries_slab, e); | |
1478 | goto out_free; | |
1479 | } | |
1480 | } | |
1481 | ||
1482 | list_for_each_entry(seb, &si->free, u.list) { | |
1483 | cond_resched(); | |
1484 | ||
1485 | e = kmem_cache_alloc(wl_entries_slab, GFP_KERNEL); | |
1486 | if (!e) | |
1487 | goto out_free; | |
1488 | ||
1489 | e->pnum = seb->pnum; | |
1490 | e->ec = seb->ec; | |
1491 | ubi_assert(e->ec >= 0); | |
1492 | free_tree_add(ubi, e); | |
1493 | ubi->lookuptbl[e->pnum] = e; | |
1494 | } | |
1495 | ||
1496 | list_for_each_entry(seb, &si->corr, u.list) { | |
1497 | cond_resched(); | |
1498 | ||
1499 | e = kmem_cache_alloc(wl_entries_slab, GFP_KERNEL); | |
1500 | if (!e) | |
1501 | goto out_free; | |
1502 | ||
1503 | e->pnum = seb->pnum; | |
1504 | e->ec = seb->ec; | |
1505 | ubi->lookuptbl[e->pnum] = e; | |
1506 | if (schedule_erase(ubi, e, 0)) { | |
1507 | kmem_cache_free(wl_entries_slab, e); | |
1508 | goto out_free; | |
1509 | } | |
1510 | } | |
1511 | ||
1512 | ubi_rb_for_each_entry(rb1, sv, &si->volumes, rb) { | |
1513 | ubi_rb_for_each_entry(rb2, seb, &sv->root, u.rb) { | |
1514 | cond_resched(); | |
1515 | ||
1516 | e = kmem_cache_alloc(wl_entries_slab, GFP_KERNEL); | |
1517 | if (!e) | |
1518 | goto out_free; | |
1519 | ||
1520 | e->pnum = seb->pnum; | |
1521 | e->ec = seb->ec; | |
1522 | ubi->lookuptbl[e->pnum] = e; | |
1523 | if (!seb->scrub) { | |
1524 | dbg_wl("add PEB %d EC %d to the used tree", | |
1525 | e->pnum, e->ec); | |
1526 | used_tree_add(ubi, e); | |
1527 | } else { | |
1528 | dbg_wl("add PEB %d EC %d to the scrub tree", | |
1529 | e->pnum, e->ec); | |
1530 | scrub_tree_add(ubi, e); | |
1531 | } | |
1532 | } | |
1533 | } | |
1534 | ||
1535 | if (WL_RESERVED_PEBS > ubi->avail_pebs) { | |
1536 | ubi_err("no enough physical eraseblocks (%d, need %d)", | |
1537 | ubi->avail_pebs, WL_RESERVED_PEBS); | |
1538 | goto out_free; | |
1539 | } | |
1540 | ubi->avail_pebs -= WL_RESERVED_PEBS; | |
1541 | ubi->rsvd_pebs += WL_RESERVED_PEBS; | |
1542 | ||
1543 | /* Schedule wear-leveling if needed */ | |
1544 | err = ensure_wear_leveling(ubi); | |
1545 | if (err) | |
1546 | goto out_free; | |
1547 | ||
1548 | return 0; | |
1549 | ||
1550 | out_free: | |
1551 | cancel_pending(ubi); | |
1552 | tree_destroy(&ubi->used); | |
1553 | tree_destroy(&ubi->free); | |
1554 | tree_destroy(&ubi->scrub); | |
1555 | kfree(ubi->lookuptbl); | |
1556 | if (ubi_devices_cnt == 0) | |
1557 | kmem_cache_destroy(wl_entries_slab); | |
1558 | return err; | |
1559 | } | |
1560 | ||
1561 | /** | |
1562 | * protection_trees_destroy - destroy the protection RB-trees. | |
1563 | * @ubi: UBI device description object | |
1564 | */ | |
1565 | static void protection_trees_destroy(struct ubi_device *ubi) | |
1566 | { | |
1567 | struct rb_node *rb; | |
1568 | struct ubi_wl_prot_entry *pe; | |
1569 | ||
1570 | rb = ubi->prot.aec.rb_node; | |
1571 | while (rb) { | |
1572 | if (rb->rb_left) | |
1573 | rb = rb->rb_left; | |
1574 | else if (rb->rb_right) | |
1575 | rb = rb->rb_right; | |
1576 | else { | |
1577 | pe = rb_entry(rb, struct ubi_wl_prot_entry, rb_aec); | |
1578 | ||
1579 | rb = rb_parent(rb); | |
1580 | if (rb) { | |
1581 | if (rb->rb_left == &pe->rb_aec) | |
1582 | rb->rb_left = NULL; | |
1583 | else | |
1584 | rb->rb_right = NULL; | |
1585 | } | |
1586 | ||
1587 | kmem_cache_free(wl_entries_slab, pe->e); | |
1588 | kfree(pe); | |
1589 | } | |
1590 | } | |
1591 | } | |
1592 | ||
1593 | /** | |
1594 | * ubi_wl_close - close the wear-leveling unit. | |
1595 | * @ubi: UBI device description object | |
1596 | */ | |
1597 | void ubi_wl_close(struct ubi_device *ubi) | |
1598 | { | |
1599 | dbg_wl("disable \"%s\"", ubi->bgt_name); | |
1600 | if (ubi->bgt_thread) | |
1601 | kthread_stop(ubi->bgt_thread); | |
1602 | ||
1603 | dbg_wl("close the UBI wear-leveling unit"); | |
1604 | ||
1605 | cancel_pending(ubi); | |
1606 | protection_trees_destroy(ubi); | |
1607 | tree_destroy(&ubi->used); | |
1608 | tree_destroy(&ubi->free); | |
1609 | tree_destroy(&ubi->scrub); | |
1610 | kfree(ubi->lookuptbl); | |
1611 | if (ubi_devices_cnt == 1) | |
1612 | kmem_cache_destroy(wl_entries_slab); | |
1613 | } | |
1614 | ||
1615 | #ifdef CONFIG_MTD_UBI_DEBUG_PARANOID | |
1616 | ||
1617 | /** | |
1618 | * paranoid_check_ec - make sure that the erase counter of a physical eraseblock | |
1619 | * is correct. | |
1620 | * @ubi: UBI device description object | |
1621 | * @pnum: the physical eraseblock number to check | |
1622 | * @ec: the erase counter to check | |
1623 | * | |
1624 | * This function returns zero if the erase counter of physical eraseblock @pnum | |
1625 | * is equivalent to @ec, %1 if not, and a negative error code if an error | |
1626 | * occurred. | |
1627 | */ | |
1628 | static int paranoid_check_ec(const struct ubi_device *ubi, int pnum, int ec) | |
1629 | { | |
1630 | int err; | |
1631 | long long read_ec; | |
1632 | struct ubi_ec_hdr *ec_hdr; | |
1633 | ||
1634 | ec_hdr = kzalloc(ubi->ec_hdr_alsize, GFP_KERNEL); | |
1635 | if (!ec_hdr) | |
1636 | return -ENOMEM; | |
1637 | ||
1638 | err = ubi_io_read_ec_hdr(ubi, pnum, ec_hdr, 0); | |
1639 | if (err && err != UBI_IO_BITFLIPS) { | |
1640 | /* The header does not have to exist */ | |
1641 | err = 0; | |
1642 | goto out_free; | |
1643 | } | |
1644 | ||
3261ebd7 | 1645 | read_ec = be64_to_cpu(ec_hdr->ec); |
801c135c AB |
1646 | if (ec != read_ec) { |
1647 | ubi_err("paranoid check failed for PEB %d", pnum); | |
1648 | ubi_err("read EC is %lld, should be %d", read_ec, ec); | |
1649 | ubi_dbg_dump_stack(); | |
1650 | err = 1; | |
1651 | } else | |
1652 | err = 0; | |
1653 | ||
1654 | out_free: | |
1655 | kfree(ec_hdr); | |
1656 | return err; | |
1657 | } | |
1658 | ||
1659 | /** | |
1660 | * paranoid_check_in_wl_tree - make sure that a wear-leveling entry is present | |
1661 | * in a WL RB-tree. | |
1662 | * @e: the wear-leveling entry to check | |
1663 | * @root: the root of the tree | |
1664 | * | |
1665 | * This function returns zero if @e is in the @root RB-tree and %1 if it | |
1666 | * is not. | |
1667 | */ | |
1668 | static int paranoid_check_in_wl_tree(struct ubi_wl_entry *e, | |
1669 | struct rb_root *root) | |
1670 | { | |
1671 | if (in_wl_tree(e, root)) | |
1672 | return 0; | |
1673 | ||
1674 | ubi_err("paranoid check failed for PEB %d, EC %d, RB-tree %p ", | |
1675 | e->pnum, e->ec, root); | |
1676 | ubi_dbg_dump_stack(); | |
1677 | return 1; | |
1678 | } | |
1679 | ||
1680 | #endif /* CONFIG_MTD_UBI_DEBUG_PARANOID */ |