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 * 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 */
183static 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 */
206int 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
212again:
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);
252out:
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 */
260static 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 */
284int 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 */
320int 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 */
354int ubi_is_erase_work(struct ubi_work *wrk)
355{
356	return wrk->func == erase_worker;
357}
358
359static 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 */
382static 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}
392