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 */
21static 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 */
35static 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 */
56static 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
69static 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 */
90struct 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--;
111out:
112	return e;
113}
114
115/**
116 * ubi_refill_pools - refills all fastmap PEB pools.
117 * @ubi: UBI device description object
118 */
119void 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 * ubi_wl_get_peb - get a physical eraseblock.
176 * @ubi: UBI device description object
177 *
178 * This function returns a physical eraseblock in case of success and a
179 * negative error code in case of failure.
180 * Returns with ubi->fm_eba_sem held in read mode!
181 */
182int ubi_wl_get_peb(struct ubi_device *ubi)
183{
184	int ret, retried = 0;
185	struct ubi_fm_pool *pool = &ubi->fm_pool;
186	struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
187
188again:
189	down_read(&ubi->fm_eba_sem);
190	spin_lock(&ubi->wl_lock);
191
192	/* We check here also for the WL pool because at this point we can
193	 * refill the WL pool synchronous. */
194	if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
195		spin_unlock(&ubi->wl_lock);
196		up_read(&ubi->fm_eba_sem);
197		ret = ubi_update_fastmap(ubi);
198		if (ret) {
199			ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
200			down_read(&ubi->fm_eba_sem);
201			return -ENOSPC;
202		}
203		down_read(&ubi->fm_eba_sem);
204		spin_lock(&ubi->wl_lock);
205	}
206
207	if (pool->used == pool->size) {
208		spin_unlock(&ubi->wl_lock);
209		if (retried) {
210			ubi_err(ubi, "Unable to get a free PEB from user WL pool");
211			ret = -ENOSPC;
212			goto out;
213		}
214		retried = 1;
215		up_read(&ubi->fm_eba_sem);
216		goto again;
217	}
218
219	ubi_assert(pool->used < pool->size);
220	ret = pool->pebs[pool->used++];
221	prot_queue_add(ubi, ubi->lookuptbl[ret]);
222	spin_unlock(&ubi->wl_lock);
223out:
224	return ret;
225}
226
227/* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
228 *
229 * @ubi: UBI device description object
230 */
231static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
232{
233	struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
234	int pnum;
235
236	if (pool->used == pool->size) {
237		/* We cannot update the fastmap here because this
238		 * function is called in atomic context.
239		 * Let's fail here and refill/update it as soon as possible. */
240		if (!ubi->fm_work_scheduled) {
241			ubi->fm_work_scheduled = 1;
242			schedule_work(&ubi->fm_work);
243		}
244		return NULL;
245	}
246
247	pnum = pool->pebs[pool->used++];
248	return ubi->lookuptbl[pnum];
249}
250
251/**
252 * ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
253 * @ubi: UBI device description object
254 */
255int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
256{
257	struct ubi_work *wrk;
258
259	spin_lock(&ubi->wl_lock);
260	if (ubi->wl_scheduled) {
261		spin_unlock(&ubi->wl_lock);
262		return 0;
263	}
264	ubi->wl_scheduled = 1;
265	spin_unlock(&ubi->wl_lock);
266
267	wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
268	if (!wrk) {
269		spin_lock(&ubi->wl_lock);
270		ubi->wl_scheduled = 0;
271		spin_unlock(&ubi->wl_lock);
272		return -ENOMEM;
273	}
274
275	wrk->anchor = 1;
276	wrk->func = &wear_leveling_worker;
277	schedule_ubi_work(ubi, wrk);
278	return 0;
279}
280
281/**
282 * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
283 * sub-system.
284 * see: ubi_wl_put_peb()
285 *
286 * @ubi: UBI device description object
287 * @fm_e: physical eraseblock to return
288 * @lnum: the last used logical eraseblock number for the PEB
289 * @torture: if this physical eraseblock has to be tortured
290 */
291int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
292		      int lnum, int torture)
293{
294	struct ubi_wl_entry *e;
295	int vol_id, pnum = fm_e->pnum;
296
297	dbg_wl("PEB %d", pnum);
298
299	ubi_assert(pnum >= 0);
300	ubi_assert(pnum < ubi->peb_count);
301
302	spin_lock(&ubi->wl_lock);
303	e = ubi->lookuptbl[pnum];
304
305	/* This can happen if we recovered from a fastmap the very
306	 * first time and writing now a new one. In this case the wl system
307	 * has never seen any PEB used by the original fastmap.
308	 */
309	if (!e) {
310		e = fm_e;
311		ubi_assert(e->ec >= 0);
312		ubi->lookuptbl[pnum] = e;
313	}
314
315	spin_unlock(&ubi->wl_lock);
316
317	vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
318	return schedule_erase(ubi, e, vol_id, lnum, torture);
319}
320
321/**
322 * ubi_is_erase_work - checks whether a work is erase work.
323 * @wrk: The work object to be checked
324 */
325int ubi_is_erase_work(struct ubi_work *wrk)
326{
327	return wrk->func == erase_worker;
328}
329
330static void ubi_fastmap_close(struct ubi_device *ubi)
331{
332	int i;
333
334	flush_work(&ubi->fm_work);
335	return_unused_pool_pebs(ubi, &ubi->fm_pool);
336	return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
337
338	if (ubi->fm) {
339		for (i = 0; i < ubi->fm->used_blocks; i++)
340			kfree(ubi->fm->e[i]);
341	}
342	kfree(ubi->fm);
343}
344
345/**
346 * may_reserve_for_fm - tests whether a PEB shall be reserved for fastmap.
347 * See find_mean_wl_entry()
348 *
349 * @ubi: UBI device description object
350 * @e: physical eraseblock to return
351 * @root: RB tree to test against.
352 */
353static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
354					   struct ubi_wl_entry *e,
355					   struct rb_root *root) {
356	if (e && !ubi->fm_disabled && !ubi->fm &&
357	    e->pnum < UBI_FM_MAX_START)
358		e = rb_entry(rb_next(root->rb_node),
359			     struct ubi_wl_entry, u.rb);
360
361	return e;
362}
363