ubi: fastmap: Implement produce_free_peb()
[karo-tx-linux.git] / drivers / mtd / ubi / fastmap-wl.c
1 /*
2  * Copyright (c) 2012 Linutronix GmbH
3  * Copyright (c) 2014 sigma star gmbh
4  * Author: Richard Weinberger <richard@nod.at>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; version 2.
9  *
10  * This program is distributed in the hope that it will be useful,
11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See
13  * the GNU General Public License for more details.
14  *
15  */
16
17 /**
18  * update_fastmap_work_fn - calls ubi_update_fastmap from a work queue
19  * @wrk: the work description object
20  */
21 static void update_fastmap_work_fn(struct work_struct *wrk)
22 {
23         struct ubi_device *ubi = container_of(wrk, struct ubi_device, fm_work);
24
25         ubi_update_fastmap(ubi);
26         spin_lock(&ubi->wl_lock);
27         ubi->fm_work_scheduled = 0;
28         spin_unlock(&ubi->wl_lock);
29 }
30
31 /**
32  * find_anchor_wl_entry - find wear-leveling entry to used as anchor PEB.
33  * @root: the RB-tree where to look for
34  */
35 static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root)
36 {
37         struct rb_node *p;
38         struct ubi_wl_entry *e, *victim = NULL;
39         int max_ec = UBI_MAX_ERASECOUNTER;
40
41         ubi_rb_for_each_entry(p, e, root, u.rb) {
42                 if (e->pnum < UBI_FM_MAX_START && e->ec < max_ec) {
43                         victim = e;
44                         max_ec = e->ec;
45                 }
46         }
47
48         return victim;
49 }
50
51 /**
52  * return_unused_pool_pebs - returns unused PEB to the free tree.
53  * @ubi: UBI device description object
54  * @pool: fastmap pool description object
55  */
56 static void return_unused_pool_pebs(struct ubi_device *ubi,
57                                     struct ubi_fm_pool *pool)
58 {
59         int i;
60         struct ubi_wl_entry *e;
61
62         for (i = pool->used; i < pool->size; i++) {
63                 e = ubi->lookuptbl[pool->pebs[i]];
64                 wl_tree_add(e, &ubi->free);
65                 ubi->free_count++;
66         }
67 }
68
69 static int anchor_pebs_avalible(struct rb_root *root)
70 {
71         struct rb_node *p;
72         struct ubi_wl_entry *e;
73
74         ubi_rb_for_each_entry(p, e, root, u.rb)
75                 if (e->pnum < UBI_FM_MAX_START)
76                         return 1;
77
78         return 0;
79 }
80
81 /**
82  * ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
83  * @ubi: UBI device description object
84  * @anchor: This PEB will be used as anchor PEB by fastmap
85  *
86  * The function returns a physical erase block with a given maximal number
87  * and removes it from the wl subsystem.
88  * Must be called with wl_lock held!
89  */
90 struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor)
91 {
92         struct ubi_wl_entry *e = NULL;
93
94         if (!ubi->free.rb_node || (ubi->free_count - ubi->beb_rsvd_pebs < 1))
95                 goto out;
96
97         if (anchor)
98                 e = find_anchor_wl_entry(&ubi->free);
99         else
100                 e = find_mean_wl_entry(ubi, &ubi->free);
101
102         if (!e)
103                 goto out;
104
105         self_check_in_wl_tree(ubi, e, &ubi->free);
106
107         /* remove it from the free list,
108          * the wl subsystem does no longer know this erase block */
109         rb_erase(&e->u.rb, &ubi->free);
110         ubi->free_count--;
111 out:
112         return e;
113 }
114
115 /**
116  * ubi_refill_pools - refills all fastmap PEB pools.
117  * @ubi: UBI device description object
118  */
119 void ubi_refill_pools(struct ubi_device *ubi)
120 {
121         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
122         struct ubi_fm_pool *pool = &ubi->fm_pool;
123         struct ubi_wl_entry *e;
124         int enough;
125
126         spin_lock(&ubi->wl_lock);
127
128         return_unused_pool_pebs(ubi, wl_pool);
129         return_unused_pool_pebs(ubi, pool);
130
131         wl_pool->size = 0;
132         pool->size = 0;
133
134         for (;;) {
135                 enough = 0;
136                 if (pool->size < pool->max_size) {
137                         if (!ubi->free.rb_node)
138                                 break;
139
140                         e = wl_get_wle(ubi);
141                         if (!e)
142                                 break;
143
144                         pool->pebs[pool->size] = e->pnum;
145                         pool->size++;
146                 } else
147                         enough++;
148
149                 if (wl_pool->size < wl_pool->max_size) {
150                         if (!ubi->free.rb_node ||
151                            (ubi->free_count - ubi->beb_rsvd_pebs < 5))
152                                 break;
153
154                         e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
155                         self_check_in_wl_tree(ubi, e, &ubi->free);
156                         rb_erase(&e->u.rb, &ubi->free);
157                         ubi->free_count--;
158
159                         wl_pool->pebs[wl_pool->size] = e->pnum;
160                         wl_pool->size++;
161                 } else
162                         enough++;
163
164                 if (enough == 2)
165                         break;
166         }
167
168         wl_pool->used = 0;
169         pool->used = 0;
170
171         spin_unlock(&ubi->wl_lock);
172 }
173
174 /**
175  * produce_free_peb - produce a free physical eraseblock.
176  * @ubi: UBI device description object
177  *
178  * This function tries to make a free PEB by means of synchronous execution of
179  * pending works. This may be needed if, for example the background thread is
180  * disabled. Returns zero in case of success and a negative error code in case
181  * of failure.
182  */
183 static int produce_free_peb(struct ubi_device *ubi)
184 {
185         int err;
186
187         while (!ubi->free.rb_node && ubi->works_count) {
188                 dbg_wl("do one work synchronously");
189                 err = do_work(ubi);
190
191                 if (err)
192                         return err;
193         }
194
195         return 0;
196 }
197
198 /**
199  * ubi_wl_get_peb - get a physical eraseblock.
200  * @ubi: UBI device description object
201  *
202  * This function returns a physical eraseblock in case of success and a
203  * negative error code in case of failure.
204  * Returns with ubi->fm_eba_sem held in read mode!
205  */
206 int ubi_wl_get_peb(struct ubi_device *ubi)
207 {
208         int ret, retried = 0;
209         struct ubi_fm_pool *pool = &ubi->fm_pool;
210         struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
211
212 again:
213         down_read(&ubi->fm_eba_sem);
214         spin_lock(&ubi->wl_lock);
215
216         /* We check here also for the WL pool because at this point we can
217          * refill the WL pool synchronous. */
218         if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
219                 spin_unlock(&ubi->wl_lock);
220                 up_read(&ubi->fm_eba_sem);
221                 ret = ubi_update_fastmap(ubi);
222                 if (ret) {
223                         ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
224                         down_read(&ubi->fm_eba_sem);
225                         return -ENOSPC;
226                 }
227                 down_read(&ubi->fm_eba_sem);
228                 spin_lock(&ubi->wl_lock);
229         }
230
231         if (pool->used == pool->size) {
232                 spin_unlock(&ubi->wl_lock);
233                 if (retried) {
234                         ubi_err(ubi, "Unable to get a free PEB from user WL pool");
235                         ret = -ENOSPC;
236                         goto out;
237                 }
238                 retried = 1;
239                 up_read(&ubi->fm_eba_sem);
240                 ret = produce_free_peb(ubi);
241                 if (ret < 0) {
242                         down_read(&ubi->fm_eba_sem);
243                         goto out;
244                 }
245                 goto again;
246         }
247
248         ubi_assert(pool->used < pool->size);
249         ret = pool->pebs[pool->used++];
250         prot_queue_add(ubi, ubi->lookuptbl[ret]);
251         spin_unlock(&ubi->wl_lock);
252 out:
253         return ret;
254 }
255
256 /* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
257  *
258  * @ubi: UBI device description object
259  */
260 static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
261 {
262         struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
263         int pnum;
264
265         if (pool->used == pool->size) {
266                 /* We cannot update the fastmap here because this
267                  * function is called in atomic context.
268                  * Let's fail here and refill/update it as soon as possible. */
269                 if (!ubi->fm_work_scheduled) {
270                         ubi->fm_work_scheduled = 1;
271                         schedule_work(&ubi->fm_work);
272                 }
273                 return NULL;
274         }
275
276         pnum = pool->pebs[pool->used++];
277         return ubi->lookuptbl[pnum];
278 }
279
280 /**
281  * ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
282  * @ubi: UBI device description object
283  */
284 int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
285 {
286         struct ubi_work *wrk;
287
288         spin_lock(&ubi->wl_lock);
289         if (ubi->wl_scheduled) {
290                 spin_unlock(&ubi->wl_lock);
291                 return 0;
292         }
293         ubi->wl_scheduled = 1;
294         spin_unlock(&ubi->wl_lock);
295
296         wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
297         if (!wrk) {
298                 spin_lock(&ubi->wl_lock);
299                 ubi->wl_scheduled = 0;
300                 spin_unlock(&ubi->wl_lock);
301                 return -ENOMEM;
302         }
303
304         wrk->anchor = 1;
305         wrk->func = &wear_leveling_worker;
306         schedule_ubi_work(ubi, wrk);
307         return 0;
308 }
309
310 /**
311  * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
312  * sub-system.
313  * see: ubi_wl_put_peb()
314  *
315  * @ubi: UBI device description object
316  * @fm_e: physical eraseblock to return
317  * @lnum: the last used logical eraseblock number for the PEB
318  * @torture: if this physical eraseblock has to be tortured
319  */
320 int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
321                       int lnum, int torture)
322 {
323         struct ubi_wl_entry *e;
324         int vol_id, pnum = fm_e->pnum;
325
326         dbg_wl("PEB %d", pnum);
327
328         ubi_assert(pnum >= 0);
329         ubi_assert(pnum < ubi->peb_count);
330
331         spin_lock(&ubi->wl_lock);
332         e = ubi->lookuptbl[pnum];
333
334         /* This can happen if we recovered from a fastmap the very
335          * first time and writing now a new one. In this case the wl system
336          * has never seen any PEB used by the original fastmap.
337          */
338         if (!e) {
339                 e = fm_e;
340                 ubi_assert(e->ec >= 0);
341                 ubi->lookuptbl[pnum] = e;
342         }
343
344         spin_unlock(&ubi->wl_lock);
345
346         vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
347         return schedule_erase(ubi, e, vol_id, lnum, torture);
348 }
349
350 /**
351  * ubi_is_erase_work - checks whether a work is erase work.
352  * @wrk: The work object to be checked
353  */
354 int ubi_is_erase_work(struct ubi_work *wrk)
355 {
356         return wrk->func == erase_worker;
357 }
358
359 static void ubi_fastmap_close(struct ubi_device *ubi)
360 {
361         int i;
362
363         flush_work(&ubi->fm_work);
364         return_unused_pool_pebs(ubi, &ubi->fm_pool);
365         return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
366
367         if (ubi->fm) {
368                 for (i = 0; i < ubi->fm->used_blocks; i++)
369                         kfree(ubi->fm->e[i]);
370         }
371         kfree(ubi->fm);
372 }
373
374 /**
375  * may_reserve_for_fm - tests whether a PEB shall be reserved for fastmap.
376  * See find_mean_wl_entry()
377  *
378  * @ubi: UBI device description object
379  * @e: physical eraseblock to return
380  * @root: RB tree to test against.
381  */
382 static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
383                                            struct ubi_wl_entry *e,
384                                            struct rb_root *root) {
385         if (e && !ubi->fm_disabled && !ubi->fm &&
386             e->pnum < UBI_FM_MAX_START)
387                 e = rb_entry(rb_next(root->rb_node),
388                              struct ubi_wl_entry, u.rb);
389
390         return e;
391 }