1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2012 Linutronix GmbH
4 * Copyright (c) 2014 sigma star gmbh
5 * Author: Richard Weinberger <richard@nod.at>
6 */
7
8/**
9 * update_fastmap_work_fn - calls ubi_update_fastmap from a work queue
10 * @wrk: the work description object
11 */
12static void update_fastmap_work_fn(struct work_struct *wrk)
13{
14	struct ubi_device *ubi = container_of(wrk, struct ubi_device, fm_work);
15
16	ubi_update_fastmap(ubi);
17	spin_lock(&ubi->wl_lock);
18	ubi->fm_work_scheduled = 0;
19	spin_unlock(&ubi->wl_lock);
20}
21
22/**
23 * find_anchor_wl_entry - find wear-leveling entry to used as anchor PEB.
24 * @root: the RB-tree where to look for
25 */
26static struct ubi_wl_entry *find_anchor_wl_entry(struct rb_root *root)
27{
28	struct rb_node *p;
29	struct ubi_wl_entry *e, *victim = NULL;
30	int max_ec = UBI_MAX_ERASECOUNTER;
31
32	ubi_rb_for_each_entry(p, e, root, u.rb) {
33		if (e->pnum < UBI_FM_MAX_START && e->ec < max_ec) {
34			victim = e;
35			max_ec = e->ec;
36		}
37	}
38
39	return victim;
40}
41
42static inline void return_unused_peb(struct ubi_device *ubi,
43				     struct ubi_wl_entry *e)
44{
45	wl_tree_add(e, &ubi->free);
46	ubi->free_count++;
47}
48
49/**
50 * return_unused_pool_pebs - returns unused PEB to the free tree.
51 * @ubi: UBI device description object
52 * @pool: fastmap pool description object
53 */
54static void return_unused_pool_pebs(struct ubi_device *ubi,
55				    struct ubi_fm_pool *pool)
56{
57	int i;
58	struct ubi_wl_entry *e;
59
60	for (i = pool->used; i < pool->size; i++) {
61		e = ubi->lookuptbl[pool->pebs[i]];
62		return_unused_peb(ubi, e);
63	}
64}
65
66/**
67 * ubi_wl_get_fm_peb - find a physical erase block with a given maximal number.
68 * @ubi: UBI device description object
69 * @anchor: This PEB will be used as anchor PEB by fastmap
70 *
71 * The function returns a physical erase block with a given maximal number
72 * and removes it from the wl subsystem.
73 * Must be called with wl_lock held!
74 */
75struct ubi_wl_entry *ubi_wl_get_fm_peb(struct ubi_device *ubi, int anchor)
76{
77	struct ubi_wl_entry *e = NULL;
78
79	if (!ubi->free.rb_node || (ubi->free_count - ubi->beb_rsvd_pebs < 1))
80		goto out;
81
82	if (anchor)
83		e = find_anchor_wl_entry(&ubi->free);
84	else
85		e = find_mean_wl_entry(ubi, &ubi->free);
86
87	if (!e)
88		goto out;
89
90	self_check_in_wl_tree(ubi, e, &ubi->free);
91
92	/* remove it from the free list,
93	 * the wl subsystem does no longer know this erase block */
94	rb_erase(&e->u.rb, &ubi->free);
95	ubi->free_count--;
96out:
97	return e;
98}
99
100/*
101 * has_enough_free_count - whether ubi has enough free pebs to fill fm pools
102 * @ubi: UBI device description object
103 * @is_wl_pool: whether UBI is filling wear leveling pool
104 *
105 * This helper function checks whether there are enough free pebs (deducted
106 * by fastmap pebs) to fill fm_pool and fm_wl_pool, above rule works after
107 * there is at least one of free pebs is filled into fm_wl_pool.
108 * For wear leveling pool, UBI should also reserve free pebs for bad pebs
109 * handling, because there maybe no enough free pebs for user volumes after
110 * producing new bad pebs.
111 */
112static bool has_enough_free_count(struct ubi_device *ubi, bool is_wl_pool)
113{
114	int fm_used = 0;	// fastmap non anchor pebs.
115	int beb_rsvd_pebs;
116
117	if (!ubi->free.rb_node)
118		return false;
119
120	beb_rsvd_pebs = is_wl_pool ? ubi->beb_rsvd_pebs : 0;
121	if (ubi->fm_wl_pool.size > 0 && !(ubi->ro_mode || ubi->fm_disabled))
122		fm_used = ubi->fm_size / ubi->leb_size - 1;
123
124	return ubi->free_count - beb_rsvd_pebs > fm_used;
125}
126
127/**
128 * ubi_refill_pools - refills all fastmap PEB pools.
129 * @ubi: UBI device description object
130 */
131void ubi_refill_pools(struct ubi_device *ubi)
132{
133	struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
134	struct ubi_fm_pool *pool = &ubi->fm_pool;
135	struct ubi_wl_entry *e;
136	int enough;
137
138	spin_lock(&ubi->wl_lock);
139
140	return_unused_pool_pebs(ubi, wl_pool);
141	return_unused_pool_pebs(ubi, pool);
142
143	wl_pool->size = 0;
144	pool->size = 0;
145
146	if (ubi->fm_anchor) {
147		wl_tree_add(ubi->fm_anchor, &ubi->free);
148		ubi->free_count++;
149		ubi->fm_anchor = NULL;
150	}
151
152	if (!ubi->fm_disabled)
153		/*
154		 * All available PEBs are in ubi->free, now is the time to get
155		 * the best anchor PEBs.
156		 */
157		ubi->fm_anchor = ubi_wl_get_fm_peb(ubi, 1);
158
159	for (;;) {
160		enough = 0;
161		if (pool->size < pool->max_size) {
162			if (!has_enough_free_count(ubi, false))
163				break;
164
165			e = wl_get_wle(ubi);
166			if (!e)
167				break;
168
169			pool->pebs[pool->size] = e->pnum;
170			pool->size++;
171		} else
172			enough++;
173
174		if (wl_pool->size < wl_pool->max_size) {
175			if (!has_enough_free_count(ubi, true))
176				break;
177
178			e = find_wl_entry(ubi, &ubi->free, WL_FREE_MAX_DIFF);
179			self_check_in_wl_tree(ubi, e, &ubi->free);
180			rb_erase(&e->u.rb, &ubi->free);
181			ubi->free_count--;
182
183			wl_pool->pebs[wl_pool->size] = e->pnum;
184			wl_pool->size++;
185		} else
186			enough++;
187
188		if (enough == 2)
189			break;
190	}
191
192	wl_pool->used = 0;
193	pool->used = 0;
194
195	spin_unlock(&ubi->wl_lock);
196}
197
198/**
199 * produce_free_peb - produce a free physical eraseblock.
200 * @ubi: UBI device description object
201 *
202 * This function tries to make a free PEB by means of synchronous execution of
203 * pending works. This may be needed if, for example the background thread is
204 * disabled. Returns zero in case of success and a negative error code in case
205 * of failure.
206 */
207static int produce_free_peb(struct ubi_device *ubi)
208{
209	int err;
210
211	while (!ubi->free.rb_node && ubi->works_count) {
212		dbg_wl("do one work synchronously");
213		err = do_work(ubi);
214
215		if (err)
216			return err;
217	}
218
219	return 0;
220}
221
222/**
223 * ubi_wl_get_peb - get a physical eraseblock.
224 * @ubi: UBI device description object
225 *
226 * This function returns a physical eraseblock in case of success and a
227 * negative error code in case of failure.
228 * Returns with ubi->fm_eba_sem held in read mode!
229 */
230int ubi_wl_get_peb(struct ubi_device *ubi)
231{
232	int ret, attempts = 0;
233	struct ubi_fm_pool *pool = &ubi->fm_pool;
234	struct ubi_fm_pool *wl_pool = &ubi->fm_wl_pool;
235
236again:
237	down_read(&ubi->fm_eba_sem);
238	spin_lock(&ubi->wl_lock);
239
240	/* We check here also for the WL pool because at this point we can
241	 * refill the WL pool synchronous. */
242	if (pool->used == pool->size || wl_pool->used == wl_pool->size) {
243		spin_unlock(&ubi->wl_lock);
244		up_read(&ubi->fm_eba_sem);
245		ret = ubi_update_fastmap(ubi);
246		if (ret) {
247			ubi_msg(ubi, "Unable to write a new fastmap: %i", ret);
248			down_read(&ubi->fm_eba_sem);
249			return -ENOSPC;
250		}
251		down_read(&ubi->fm_eba_sem);
252		spin_lock(&ubi->wl_lock);
253	}
254
255	if (pool->used == pool->size) {
256		spin_unlock(&ubi->wl_lock);
257		attempts++;
258		if (attempts == 10) {
259			ubi_err(ubi, "Unable to get a free PEB from user WL pool");
260			ret = -ENOSPC;
261			goto out;
262		}
263		up_read(&ubi->fm_eba_sem);
264		ret = produce_free_peb(ubi);
265		if (ret < 0) {
266			down_read(&ubi->fm_eba_sem);
267			goto out;
268		}
269		goto again;
270	}
271
272	ubi_assert(pool->used < pool->size);
273	ret = pool->pebs[pool->used++];
274	prot_queue_add(ubi, ubi->lookuptbl[ret]);
275	spin_unlock(&ubi->wl_lock);
276out:
277	return ret;
278}
279
280/* get_peb_for_wl - returns a PEB to be used internally by the WL sub-system.
281 *
282 * @ubi: UBI device description object
283 */
284static struct ubi_wl_entry *get_peb_for_wl(struct ubi_device *ubi)
285{
286	struct ubi_fm_pool *pool = &ubi->fm_wl_pool;
287	int pnum;
288
289	ubi_assert(rwsem_is_locked(&ubi->fm_eba_sem));
290
291	if (pool->used == pool->size) {
292		/* We cannot update the fastmap here because this
293		 * function is called in atomic context.
294		 * Let's fail here and refill/update it as soon as possible. */
295		if (!ubi->fm_work_scheduled) {
296			ubi->fm_work_scheduled = 1;
297			schedule_work(&ubi->fm_work);
298		}
299		return NULL;
300	}
301
302	pnum = pool->pebs[pool->used++];
303	return ubi->lookuptbl[pnum];
304}
305
306/**
307 * ubi_ensure_anchor_pebs - schedule wear-leveling to produce an anchor PEB.
308 * @ubi: UBI device description object
309 */
310int ubi_ensure_anchor_pebs(struct ubi_device *ubi)
311{
312	struct ubi_work *wrk;
313	struct ubi_wl_entry *anchor;
314
315	spin_lock(&ubi->wl_lock);
316
317	/* Do we already have an anchor? */
318	if (ubi->fm_anchor) {
319		spin_unlock(&ubi->wl_lock);
320		return 0;
321	}
322
323	/* See if we can find an anchor PEB on the list of free PEBs */
324	anchor = ubi_wl_get_fm_peb(ubi, 1);
325	if (anchor) {
326		ubi->fm_anchor = anchor;
327		spin_unlock(&ubi->wl_lock);
328		return 0;
329	}
330
331	ubi->fm_do_produce_anchor = 1;
332	/* No luck, trigger wear leveling to produce a new anchor PEB. */
333	if (ubi->wl_scheduled) {
334		spin_unlock(&ubi->wl_lock);
335		return 0;
336	}
337	ubi->wl_scheduled = 1;
338	spin_unlock(&ubi->wl_lock);
339
340	wrk = kmalloc(sizeof(struct ubi_work), GFP_NOFS);
341	if (!wrk) {
342		spin_lock(&ubi->wl_lock);
343		ubi->wl_scheduled = 0;
344		spin_unlock(&ubi->wl_lock);
345		return -ENOMEM;
346	}
347
348	wrk->func = &wear_leveling_worker;
349	__schedule_ubi_work(ubi, wrk);
350	return 0;
351}
352
353/**
354 * ubi_wl_put_fm_peb - returns a PEB used in a fastmap to the wear-leveling
355 * sub-system.
356 * see: ubi_wl_put_peb()
357 *
358 * @ubi: UBI device description object
359 * @fm_e: physical eraseblock to return
360 * @lnum: the last used logical eraseblock number for the PEB
361 * @torture: if this physical eraseblock has to be tortured
362 */
363int ubi_wl_put_fm_peb(struct ubi_device *ubi, struct ubi_wl_entry *fm_e,
364		      int lnum, int torture)
365{
366	struct ubi_wl_entry *e;
367	int vol_id, pnum = fm_e->pnum;
368
369	dbg_wl("PEB %d", pnum);
370
371	ubi_assert(pnum >= 0);
372	ubi_assert(pnum < ubi->peb_count);
373
374	spin_lock(&ubi->wl_lock);
375	e = ubi->lookuptbl[pnum];
376
377	/* This can happen if we recovered from a fastmap the very
378	 * first time and writing now a new one. In this case the wl system
379	 * has never seen any PEB used by the original fastmap.
380	 */
381	if (!e) {
382		e = fm_e;
383		ubi_assert(e->ec >= 0);
384		ubi->lookuptbl[pnum] = e;
385	}
386
387	spin_unlock(&ubi->wl_lock);
388
389	vol_id = lnum ? UBI_FM_DATA_VOLUME_ID : UBI_FM_SB_VOLUME_ID;
390	return schedule_erase(ubi, e, vol_id, lnum, torture, true);
391}
392
393/**
394 * ubi_is_erase_work - checks whether a work is erase work.
395 * @wrk: The work object to be checked
396 */
397int ubi_is_erase_work(struct ubi_work *wrk)
398{
399	return wrk->func == erase_worker;
400}
401
402static void ubi_fastmap_close(struct ubi_device *ubi)
403{
404	int i;
405
406	return_unused_pool_pebs(ubi, &ubi->fm_pool);
407	return_unused_pool_pebs(ubi, &ubi->fm_wl_pool);
408
409	if (ubi->fm_anchor) {
410		return_unused_peb(ubi, ubi->fm_anchor);
411		ubi->fm_anchor = NULL;
412	}
413
414	if (ubi->fm) {
415		for (i = 0; i < ubi->fm->used_blocks; i++)
416			kfree(ubi->fm->e[i]);
417	}
418	kfree(ubi->fm);
419}
420
421/**
422 * may_reserve_for_fm - tests whether a PEB shall be reserved for fastmap.
423 * See find_mean_wl_entry()
424 *
425 * @ubi: UBI device description object
426 * @e: physical eraseblock to return
427 * @root: RB tree to test against.
428 */
429static struct ubi_wl_entry *may_reserve_for_fm(struct ubi_device *ubi,
430					   struct ubi_wl_entry *e,
431					   struct rb_root *root) {
432	if (e && !ubi->fm_disabled && !ubi->fm &&
433	    e->pnum < UBI_FM_MAX_START)
434		e = rb_entry(rb_next(root->rb_node),
435			     struct ubi_wl_entry, u.rb);
436
437	return e;
438}
439