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1/*
2 * This file is part of UBIFS.
3 *
4 * Copyright (C) 2006-2008 Nokia Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 *
19 * Authors: Artem Bityutskiy (Битюцкий Артём)
20 * Adrian Hunter
21 */
22
23/*
24 * This file contains functions for finding LEBs for various purposes e.g.
25 * garbage collection. In general, lprops category heaps and lists are used
26 * for fast access, falling back on scanning the LPT as a last resort.
27 */
28
29#include <linux/sort.h>
30#include "ubifs.h"
31
32/**
33 * struct scan_data - data provided to scan callback functions
34 * @min_space: minimum number of bytes for which to scan
35 * @pick_free: whether it is OK to scan for empty LEBs
36 * @lnum: LEB number found is returned here
37 * @exclude_index: whether to exclude index LEBs
38 */
39struct scan_data {
40 int min_space;
41 int pick_free;
42 int lnum;
43 int exclude_index;
44};
45
46/**
47 * valuable - determine whether LEB properties are valuable.
48 * @c: the UBIFS file-system description object
49 * @lprops: LEB properties
50 *
51 * This function return %1 if the LEB properties should be added to the LEB
52 * properties tree in memory. Otherwise %0 is returned.
53 */
54static int valuable(struct ubifs_info *c, const struct ubifs_lprops *lprops)
55{
56 int n, cat = lprops->flags & LPROPS_CAT_MASK;
57 struct ubifs_lpt_heap *heap;
58
59 switch (cat) {
60 case LPROPS_DIRTY:
61 case LPROPS_DIRTY_IDX:
62 case LPROPS_FREE:
63 heap = &c->lpt_heap[cat - 1];
64 if (heap->cnt < heap->max_cnt)
65 return 1;
66 if (lprops->free + lprops->dirty >= c->dark_wm)
67 return 1;
68 return 0;
69 case LPROPS_EMPTY:
70 n = c->lst.empty_lebs + c->freeable_cnt -
71 c->lst.taken_empty_lebs;
72 if (n < c->lsave_cnt)
73 return 1;
74 return 0;
75 case LPROPS_FREEABLE:
76 return 1;
77 case LPROPS_FRDI_IDX:
78 return 1;
79 }
80 return 0;
81}
82
83/**
84 * scan_for_dirty_cb - dirty space scan callback.
85 * @c: the UBIFS file-system description object
86 * @lprops: LEB properties to scan
87 * @in_tree: whether the LEB properties are in main memory
88 * @data: information passed to and from the caller of the scan
89 *
90 * This function returns a code that indicates whether the scan should continue
91 * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
92 * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
93 * (%LPT_SCAN_STOP).
94 */
95static int scan_for_dirty_cb(struct ubifs_info *c,
96 const struct ubifs_lprops *lprops, int in_tree,
97 struct scan_data *data)
98{
99 int ret = LPT_SCAN_CONTINUE;
100
101 /* Exclude LEBs that are currently in use */
102 if (lprops->flags & LPROPS_TAKEN)
103 return LPT_SCAN_CONTINUE;
104 /* Determine whether to add these LEB properties to the tree */
105 if (!in_tree && valuable(c, lprops))
106 ret |= LPT_SCAN_ADD;
107 /* Exclude LEBs with too little space */
108 if (lprops->free + lprops->dirty < data->min_space)
109 return ret;
110 /* If specified, exclude index LEBs */
111 if (data->exclude_index && lprops->flags & LPROPS_INDEX)
112 return ret;
113 /* If specified, exclude empty or freeable LEBs */
114 if (lprops->free + lprops->dirty == c->leb_size) {
115 if (!data->pick_free)
116 return ret;
117 /* Exclude LEBs with too little dirty space (unless it is empty) */
118 } else if (lprops->dirty < c->dead_wm)
119 return ret;
120 /* Finally we found space */
121 data->lnum = lprops->lnum;
122 return LPT_SCAN_ADD | LPT_SCAN_STOP;
123}
124
125/**
126 * scan_for_dirty - find a data LEB with free space.
127 * @c: the UBIFS file-system description object
128 * @min_space: minimum amount free plus dirty space the returned LEB has to
129 * have
130 * @pick_free: if it is OK to return a free or freeable LEB
131 * @exclude_index: whether to exclude index LEBs
132 *
133 * This function returns a pointer to the LEB properties found or a negative
134 * error code.
135 */
136static const struct ubifs_lprops *scan_for_dirty(struct ubifs_info *c,
137 int min_space, int pick_free,
138 int exclude_index)
139{
140 const struct ubifs_lprops *lprops;
141 struct ubifs_lpt_heap *heap;
142 struct scan_data data;
143 int err, i;
144
145 /* There may be an LEB with enough dirty space on the free heap */
146 heap = &c->lpt_heap[LPROPS_FREE - 1];
147 for (i = 0; i < heap->cnt; i++) {
148 lprops = heap->arr[i];
149 if (lprops->free + lprops->dirty < min_space)
150 continue;
151 if (lprops->dirty < c->dead_wm)
152 continue;
153 return lprops;
154 }
155 /*
156 * A LEB may have fallen off of the bottom of the dirty heap, and ended
157 * up as uncategorized even though it has enough dirty space for us now,
158 * so check the uncategorized list. N.B. neither empty nor freeable LEBs
159 * can end up as uncategorized because they are kept on lists not
160 * finite-sized heaps.
161 */
162 list_for_each_entry(lprops, &c->uncat_list, list) {
163 if (lprops->flags & LPROPS_TAKEN)
164 continue;
165 if (lprops->free + lprops->dirty < min_space)
166 continue;
167 if (exclude_index && (lprops->flags & LPROPS_INDEX))
168 continue;
169 if (lprops->dirty < c->dead_wm)
170 continue;
171 return lprops;
172 }
173 /* We have looked everywhere in main memory, now scan the flash */
174 if (c->pnodes_have >= c->pnode_cnt)
175 /* All pnodes are in memory, so skip scan */
176 return ERR_PTR(-ENOSPC);
177 data.min_space = min_space;
178 data.pick_free = pick_free;
179 data.lnum = -1;
180 data.exclude_index = exclude_index;
181 err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
182 (ubifs_lpt_scan_callback)scan_for_dirty_cb,
183 &data);
184 if (err)
185 return ERR_PTR(err);
186 ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
187 c->lscan_lnum = data.lnum;
188 lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
189 if (IS_ERR(lprops))
190 return lprops;
191 ubifs_assert(lprops->lnum == data.lnum);
192 ubifs_assert(lprops->free + lprops->dirty >= min_space);
193 ubifs_assert(lprops->dirty >= c->dead_wm ||
194 (pick_free &&
195 lprops->free + lprops->dirty == c->leb_size));
196 ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
197 ubifs_assert(!exclude_index || !(lprops->flags & LPROPS_INDEX));
198 return lprops;
199}
200
201/**
202 * ubifs_find_dirty_leb - find a dirty LEB for the Garbage Collector.
203 * @c: the UBIFS file-system description object
204 * @ret_lp: LEB properties are returned here on exit
205 * @min_space: minimum amount free plus dirty space the returned LEB has to
206 * have
207 * @pick_free: controls whether it is OK to pick empty or index LEBs
208 *
209 * This function tries to find a dirty logical eraseblock which has at least
210 * @min_space free and dirty space. It prefers to take an LEB from the dirty or
211 * dirty index heap, and it falls-back to LPT scanning if the heaps are empty
212 * or do not have an LEB which satisfies the @min_space criteria.
213 *
214 * Note:
215 * o LEBs which have less than dead watermark of dirty space are never picked
216 * by this function;
217 *
218 * Returns zero and the LEB properties of
219 * found dirty LEB in case of success, %-ENOSPC if no dirty LEB was found and a
220 * negative error code in case of other failures. The returned LEB is marked as
221 * "taken".
222 *
223 * The additional @pick_free argument controls if this function has to return a
224 * free or freeable LEB if one is present. For example, GC must to set it to %1,
225 * when called from the journal space reservation function, because the
226 * appearance of free space may coincide with the loss of enough dirty space
227 * for GC to succeed anyway.
228 *
229 * In contrast, if the Garbage Collector is called from budgeting, it should
230 * just make free space, not return LEBs which are already free or freeable.
231 *
232 * In addition @pick_free is set to %2 by the recovery process in order to
233 * recover gc_lnum in which case an index LEB must not be returned.
234 */
235int ubifs_find_dirty_leb(struct ubifs_info *c, struct ubifs_lprops *ret_lp,
236 int min_space, int pick_free)
237{
238 int err = 0, sum, exclude_index = pick_free == 2 ? 1 : 0;
239 const struct ubifs_lprops *lp = NULL, *idx_lp = NULL;
240 struct ubifs_lpt_heap *heap, *idx_heap;
241
242 ubifs_get_lprops(c);
243
244 if (pick_free) {
245 int lebs, rsvd_idx_lebs = 0;
246
247 spin_lock(&c->space_lock);
248 lebs = c->lst.empty_lebs;
249 lebs += c->freeable_cnt - c->lst.taken_empty_lebs;
250
251 /*
252 * Note, the index may consume more LEBs than have been reserved
253 * for it. It is OK because it might be consolidated by GC.
254 * But if the index takes fewer LEBs than it is reserved for it,
255 * this function must avoid picking those reserved LEBs.
256 */
257 if (c->min_idx_lebs >= c->lst.idx_lebs) {
258 rsvd_idx_lebs = c->min_idx_lebs - c->lst.idx_lebs;
259 exclude_index = 1;
260 }
261 spin_unlock(&c->space_lock);
262
263 /* Check if there are enough free LEBs for the index */
264 if (rsvd_idx_lebs < lebs) {
265 /* OK, try to find an empty LEB */
266 lp = ubifs_fast_find_empty(c);
267 if (lp)
268 goto found;
269
270 /* Or a freeable LEB */
271 lp = ubifs_fast_find_freeable(c);
272 if (lp)
273 goto found;
274 } else
275 /*
276 * We cannot pick free/freeable LEBs in the below code.
277 */
278 pick_free = 0;
279 } else {
280 spin_lock(&c->space_lock);
281 exclude_index = (c->min_idx_lebs >= c->lst.idx_lebs);
282 spin_unlock(&c->space_lock);
283 }
284
285 /* Look on the dirty and dirty index heaps */
286 heap = &c->lpt_heap[LPROPS_DIRTY - 1];
287 idx_heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
288
289 if (idx_heap->cnt && !exclude_index) {
290 idx_lp = idx_heap->arr[0];
291 sum = idx_lp->free + idx_lp->dirty;
292 /*
293 * Since we reserve twice as more space for the index than it
294 * actually takes, it does not make sense to pick indexing LEBs
295 * with less than half LEB of dirty space.
296 */
297 if (sum < min_space || sum < c->half_leb_size)
298 idx_lp = NULL;
299 }
300
301 if (heap->cnt) {
302 lp = heap->arr[0];
303 if (lp->dirty + lp->free < min_space)
304 lp = NULL;
305 }
306
307 /* Pick the LEB with most space */
308 if (idx_lp && lp) {
309 if (idx_lp->free + idx_lp->dirty >= lp->free + lp->dirty)
310 lp = idx_lp;
311 } else if (idx_lp && !lp)
312 lp = idx_lp;
313
314 if (lp) {
315 ubifs_assert(lp->dirty >= c->dead_wm);
316 goto found;
317 }
318
319 /* Did not find a dirty LEB on the dirty heaps, have to scan */
320 dbg_find("scanning LPT for a dirty LEB");
321 lp = scan_for_dirty(c, min_space, pick_free, exclude_index);
322 if (IS_ERR(lp)) {
323 err = PTR_ERR(lp);
324 goto out;
325 }
326 ubifs_assert(lp->dirty >= c->dead_wm ||
327 (pick_free && lp->free + lp->dirty == c->leb_size));
328
329found:
330 dbg_find("found LEB %d, free %d, dirty %d, flags %#x",
331 lp->lnum, lp->free, lp->dirty, lp->flags);
332
333 lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
334 lp->flags | LPROPS_TAKEN, 0);
335 if (IS_ERR(lp)) {
336 err = PTR_ERR(lp);
337 goto out;
338 }
339
340 memcpy(ret_lp, lp, sizeof(struct ubifs_lprops));
341
342out:
343 ubifs_release_lprops(c);
344 return err;
345}
346
347/**
348 * scan_for_free_cb - free space scan callback.
349 * @c: the UBIFS file-system description object
350 * @lprops: LEB properties to scan
351 * @in_tree: whether the LEB properties are in main memory
352 * @data: information passed to and from the caller of the scan
353 *
354 * This function returns a code that indicates whether the scan should continue
355 * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
356 * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
357 * (%LPT_SCAN_STOP).
358 */
359static int scan_for_free_cb(struct ubifs_info *c,
360 const struct ubifs_lprops *lprops, int in_tree,
361 struct scan_data *data)
362{
363 int ret = LPT_SCAN_CONTINUE;
364
365 /* Exclude LEBs that are currently in use */
366 if (lprops->flags & LPROPS_TAKEN)
367 return LPT_SCAN_CONTINUE;
368 /* Determine whether to add these LEB properties to the tree */
369 if (!in_tree && valuable(c, lprops))
370 ret |= LPT_SCAN_ADD;
371 /* Exclude index LEBs */
372 if (lprops->flags & LPROPS_INDEX)
373 return ret;
374 /* Exclude LEBs with too little space */
375 if (lprops->free < data->min_space)
376 return ret;
377 /* If specified, exclude empty LEBs */
378 if (!data->pick_free && lprops->free == c->leb_size)
379 return ret;
380 /*
381 * LEBs that have only free and dirty space must not be allocated
382 * because they may have been unmapped already or they may have data
383 * that is obsolete only because of nodes that are still sitting in a
384 * wbuf.
385 */
386 if (lprops->free + lprops->dirty == c->leb_size && lprops->dirty > 0)
387 return ret;
388 /* Finally we found space */
389 data->lnum = lprops->lnum;
390 return LPT_SCAN_ADD | LPT_SCAN_STOP;
391}
392
393/**
394 * do_find_free_space - find a data LEB with free space.
395 * @c: the UBIFS file-system description object
396 * @min_space: minimum amount of free space required
397 * @pick_free: whether it is OK to scan for empty LEBs
398 * @squeeze: whether to try to find space in a non-empty LEB first
399 *
400 * This function returns a pointer to the LEB properties found or a negative
401 * error code.
402 */
403static
404const struct ubifs_lprops *do_find_free_space(struct ubifs_info *c,
405 int min_space, int pick_free,
406 int squeeze)
407{
408 const struct ubifs_lprops *lprops;
409 struct ubifs_lpt_heap *heap;
410 struct scan_data data;
411 int err, i;
412
413 if (squeeze) {
414 lprops = ubifs_fast_find_free(c);
415 if (lprops && lprops->free >= min_space)
416 return lprops;
417 }
418 if (pick_free) {
419 lprops = ubifs_fast_find_empty(c);
420 if (lprops)
421 return lprops;
422 }
423 if (!squeeze) {
424 lprops = ubifs_fast_find_free(c);
425 if (lprops && lprops->free >= min_space)
426 return lprops;
427 }
428 /* There may be an LEB with enough free space on the dirty heap */
429 heap = &c->lpt_heap[LPROPS_DIRTY - 1];
430 for (i = 0; i < heap->cnt; i++) {
431 lprops = heap->arr[i];
432 if (lprops->free >= min_space)
433 return lprops;
434 }
435 /*
436 * A LEB may have fallen off of the bottom of the free heap, and ended
437 * up as uncategorized even though it has enough free space for us now,
438 * so check the uncategorized list. N.B. neither empty nor freeable LEBs
439 * can end up as uncategorized because they are kept on lists not
440 * finite-sized heaps.
441 */
442 list_for_each_entry(lprops, &c->uncat_list, list) {
443 if (lprops->flags & LPROPS_TAKEN)
444 continue;
445 if (lprops->flags & LPROPS_INDEX)
446 continue;
447 if (lprops->free >= min_space)
448 return lprops;
449 }
450 /* We have looked everywhere in main memory, now scan the flash */
451 if (c->pnodes_have >= c->pnode_cnt)
452 /* All pnodes are in memory, so skip scan */
453 return ERR_PTR(-ENOSPC);
454 data.min_space = min_space;
455 data.pick_free = pick_free;
456 data.lnum = -1;
457 err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
458 (ubifs_lpt_scan_callback)scan_for_free_cb,
459 &data);
460 if (err)
461 return ERR_PTR(err);
462 ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
463 c->lscan_lnum = data.lnum;
464 lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
465 if (IS_ERR(lprops))
466 return lprops;
467 ubifs_assert(lprops->lnum == data.lnum);
468 ubifs_assert(lprops->free >= min_space);
469 ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
470 ubifs_assert(!(lprops->flags & LPROPS_INDEX));
471 return lprops;
472}
473
474/**
475 * ubifs_find_free_space - find a data LEB with free space.
476 * @c: the UBIFS file-system description object
477 * @min_space: minimum amount of required free space
478 * @free: contains amount of free space in the LEB on exit
479 * @squeeze: whether to try to find space in a non-empty LEB first
480 *
481 * This function looks for an LEB with at least @min_space bytes of free space.
482 * It tries to find an empty LEB if possible. If no empty LEBs are available,
483 * this function searches for a non-empty data LEB. The returned LEB is marked
484 * as "taken".
485 *
486 * This function returns found LEB number in case of success, %-ENOSPC if it
487 * failed to find a LEB with @min_space bytes of free space and other a negative
488 * error codes in case of failure.
489 */
490int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *free,
491 int squeeze)
492{
493 const struct ubifs_lprops *lprops;
494 int lebs, rsvd_idx_lebs, pick_free = 0, err, lnum, flags;
495
496 dbg_find("min_space %d", min_space);
497 ubifs_get_lprops(c);
498
499 /* Check if there are enough empty LEBs for commit */
500 spin_lock(&c->space_lock);
501 if (c->min_idx_lebs > c->lst.idx_lebs)
502 rsvd_idx_lebs = c->min_idx_lebs - c->lst.idx_lebs;
503 else
504 rsvd_idx_lebs = 0;
505 lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
506 c->lst.taken_empty_lebs;
507 ubifs_assert(lebs + c->lst.idx_lebs >= c->min_idx_lebs);
508 if (rsvd_idx_lebs < lebs)
509 /*
510 * OK to allocate an empty LEB, but we still don't want to go
511 * looking for one if there aren't any.
512 */
513 if (c->lst.empty_lebs - c->lst.taken_empty_lebs > 0) {
514 pick_free = 1;
515 /*
516 * Because we release the space lock, we must account
517 * for this allocation here. After the LEB properties
518 * flags have been updated, we subtract one. Note, the
519 * result of this is that lprops also decreases
520 * @taken_empty_lebs in 'ubifs_change_lp()', so it is
521 * off by one for a short period of time which may
522 * introduce a small disturbance to budgeting
523 * calculations, but this is harmless because at the
524 * worst case this would make the budgeting subsystem
525 * be more pessimistic than needed.
526 *
527 * Fundamentally, this is about serialization of the
528 * budgeting and lprops subsystems. We could make the
529 * @space_lock a mutex and avoid dropping it before
530 * calling 'ubifs_change_lp()', but mutex is more
531 * heavy-weight, and we want budgeting to be as fast as
532 * possible.
533 */
534 c->lst.taken_empty_lebs += 1;
535 }
536 spin_unlock(&c->space_lock);
537
538 lprops = do_find_free_space(c, min_space, pick_free, squeeze);
539 if (IS_ERR(lprops)) {
540 err = PTR_ERR(lprops);
541 goto out;
542 }
543
544 lnum = lprops->lnum;
545 flags = lprops->flags | LPROPS_TAKEN;
546
547 lprops = ubifs_change_lp(c, lprops, LPROPS_NC, LPROPS_NC, flags, 0);
548 if (IS_ERR(lprops)) {
549 err = PTR_ERR(lprops);
550 goto out;
551 }
552
553 if (pick_free) {
554 spin_lock(&c->space_lock);
555 c->lst.taken_empty_lebs -= 1;
556 spin_unlock(&c->space_lock);
557 }
558
559 *free = lprops->free;
560 ubifs_release_lprops(c);
561
562 if (*free == c->leb_size) {
563 /*
564 * Ensure that empty LEBs have been unmapped. They may not have
565 * been, for example, because of an unclean unmount. Also
566 * LEBs that were freeable LEBs (free + dirty == leb_size) will
567 * not have been unmapped.
568 */
569 err = ubifs_leb_unmap(c, lnum);
570 if (err)
571 return err;
572 }
573
574 dbg_find("found LEB %d, free %d", lnum, *free);
575 ubifs_assert(*free >= min_space);
576 return lnum;
577
578out:
579 if (pick_free) {
580 spin_lock(&c->space_lock);
581 c->lst.taken_empty_lebs -= 1;
582 spin_unlock(&c->space_lock);
583 }
584 ubifs_release_lprops(c);
585 return err;
586}
587
588/**
589 * scan_for_idx_cb - callback used by the scan for a free LEB for the index.
590 * @c: the UBIFS file-system description object
591 * @lprops: LEB properties to scan
592 * @in_tree: whether the LEB properties are in main memory
593 * @data: information passed to and from the caller of the scan
594 *
595 * This function returns a code that indicates whether the scan should continue
596 * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
597 * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
598 * (%LPT_SCAN_STOP).
599 */
600static int scan_for_idx_cb(struct ubifs_info *c,
601 const struct ubifs_lprops *lprops, int in_tree,
602 struct scan_data *data)
603{
604 int ret = LPT_SCAN_CONTINUE;
605
606 /* Exclude LEBs that are currently in use */
607 if (lprops->flags & LPROPS_TAKEN)
608 return LPT_SCAN_CONTINUE;
609 /* Determine whether to add these LEB properties to the tree */
610 if (!in_tree && valuable(c, lprops))
611 ret |= LPT_SCAN_ADD;
612 /* Exclude index LEBS */
613 if (lprops->flags & LPROPS_INDEX)
614 return ret;
615 /* Exclude LEBs that cannot be made empty */
616 if (lprops->free + lprops->dirty != c->leb_size)
617 return ret;
618 /*
619 * We are allocating for the index so it is safe to allocate LEBs with
620 * only free and dirty space, because write buffers are sync'd at commit
621 * start.
622 */
623 data->lnum = lprops->lnum;
624 return LPT_SCAN_ADD | LPT_SCAN_STOP;
625}
626
627/**
628 * scan_for_leb_for_idx - scan for a free LEB for the index.
629 * @c: the UBIFS file-system description object
630 */
631static const struct ubifs_lprops *scan_for_leb_for_idx(struct ubifs_info *c)
632{
633 struct ubifs_lprops *lprops;
634 struct scan_data data;
635 int err;
636
637 data.lnum = -1;
638 err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
639 (ubifs_lpt_scan_callback)scan_for_idx_cb,
640 &data);
641 if (err)
642 return ERR_PTR(err);
643 ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
644 c->lscan_lnum = data.lnum;
645 lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
646 if (IS_ERR(lprops))
647 return lprops;
648 ubifs_assert(lprops->lnum == data.lnum);
649 ubifs_assert(lprops->free + lprops->dirty == c->leb_size);
650 ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
651 ubifs_assert(!(lprops->flags & LPROPS_INDEX));
652 return lprops;
653}
654
655/**
656 * ubifs_find_free_leb_for_idx - find a free LEB for the index.
657 * @c: the UBIFS file-system description object
658 *
659 * This function looks for a free LEB and returns that LEB number. The returned
660 * LEB is marked as "taken", "index".
661 *
662 * Only empty LEBs are allocated. This is for two reasons. First, the commit
663 * calculates the number of LEBs to allocate based on the assumption that they
664 * will be empty. Secondly, free space at the end of an index LEB is not
665 * guaranteed to be empty because it may have been used by the in-the-gaps
666 * method prior to an unclean unmount.
667 *
668 * If no LEB is found %-ENOSPC is returned. For other failures another negative
669 * error code is returned.
670 */
671int ubifs_find_free_leb_for_idx(struct ubifs_info *c)
672{
673 const struct ubifs_lprops *lprops;
674 int lnum = -1, err, flags;
675
676 ubifs_get_lprops(c);
677
678 lprops = ubifs_fast_find_empty(c);
679 if (!lprops) {
680 lprops = ubifs_fast_find_freeable(c);
681 if (!lprops) {
682 ubifs_assert(c->freeable_cnt == 0);
683 if (c->lst.empty_lebs - c->lst.taken_empty_lebs > 0) {
684 lprops = scan_for_leb_for_idx(c);
685 if (IS_ERR(lprops)) {
686 err = PTR_ERR(lprops);
687 goto out;
688 }
689 }
690 }
691 }
692
693 if (!lprops) {
694 err = -ENOSPC;
695 goto out;
696 }
697
698 lnum = lprops->lnum;
699
700 dbg_find("found LEB %d, free %d, dirty %d, flags %#x",
701 lnum, lprops->free, lprops->dirty, lprops->flags);
702
703 flags = lprops->flags | LPROPS_TAKEN | LPROPS_INDEX;
704 lprops = ubifs_change_lp(c, lprops, c->leb_size, 0, flags, 0);
705 if (IS_ERR(lprops)) {
706 err = PTR_ERR(lprops);
707 goto out;
708 }
709
710 ubifs_release_lprops(c);
711
712 /*
713 * Ensure that empty LEBs have been unmapped. They may not have been,
714 * for example, because of an unclean unmount. Also LEBs that were
715 * freeable LEBs (free + dirty == leb_size) will not have been unmapped.
716 */
717 err = ubifs_leb_unmap(c, lnum);
718 if (err) {
719 ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
720 LPROPS_TAKEN | LPROPS_INDEX, 0);
721 return err;
722 }
723
724 return lnum;
725
726out:
727 ubifs_release_lprops(c);
728 return err;
729}
730
731static int cmp_dirty_idx(const struct ubifs_lprops **a,
732 const struct ubifs_lprops **b)
733{
734 const struct ubifs_lprops *lpa = *a;
735 const struct ubifs_lprops *lpb = *b;
736
737 return lpa->dirty + lpa->free - lpb->dirty - lpb->free;
738}
739
740static void swap_dirty_idx(struct ubifs_lprops **a, struct ubifs_lprops **b,
741 int size)
742{
743 struct ubifs_lprops *t = *a;
744
745 *a = *b;
746 *b = t;
747}
748
749/**
750 * ubifs_save_dirty_idx_lnums - save an array of the most dirty index LEB nos.
751 * @c: the UBIFS file-system description object
752 *
753 * This function is called each commit to create an array of LEB numbers of
754 * dirty index LEBs sorted in order of dirty and free space. This is used by
755 * the in-the-gaps method of TNC commit.
756 */
757int ubifs_save_dirty_idx_lnums(struct ubifs_info *c)
758{
759 int i;
760
761 ubifs_get_lprops(c);
762 /* Copy the LPROPS_DIRTY_IDX heap */
763 c->dirty_idx.cnt = c->lpt_heap[LPROPS_DIRTY_IDX - 1].cnt;
764 memcpy(c->dirty_idx.arr, c->lpt_heap[LPROPS_DIRTY_IDX - 1].arr,
765 sizeof(void *) * c->dirty_idx.cnt);
766 /* Sort it so that the dirtiest is now at the end */
767 sort(c->dirty_idx.arr, c->dirty_idx.cnt, sizeof(void *),
768 (int (*)(const void *, const void *))cmp_dirty_idx,
769 (void (*)(void *, void *, int))swap_dirty_idx);
770 dbg_find("found %d dirty index LEBs", c->dirty_idx.cnt);
771 if (c->dirty_idx.cnt)
772 dbg_find("dirtiest index LEB is %d with dirty %d and free %d",
773 c->dirty_idx.arr[c->dirty_idx.cnt - 1]->lnum,
774 c->dirty_idx.arr[c->dirty_idx.cnt - 1]->dirty,
775 c->dirty_idx.arr[c->dirty_idx.cnt - 1]->free);
776 /* Replace the lprops pointers with LEB numbers */
777 for (i = 0; i < c->dirty_idx.cnt; i++)
778 c->dirty_idx.arr[i] = (void *)(size_t)c->dirty_idx.arr[i]->lnum;
779 ubifs_release_lprops(c);
780 return 0;
781}
782
783/**
784 * scan_dirty_idx_cb - callback used by the scan for a dirty index LEB.
785 * @c: the UBIFS file-system description object
786 * @lprops: LEB properties to scan
787 * @in_tree: whether the LEB properties are in main memory
788 * @data: information passed to and from the caller of the scan
789 *
790 * This function returns a code that indicates whether the scan should continue
791 * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
792 * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
793 * (%LPT_SCAN_STOP).
794 */
795static int scan_dirty_idx_cb(struct ubifs_info *c,
796 const struct ubifs_lprops *lprops, int in_tree,
797 struct scan_data *data)
798{
799 int ret = LPT_SCAN_CONTINUE;
800
801 /* Exclude LEBs that are currently in use */
802 if (lprops->flags & LPROPS_TAKEN)
803 return LPT_SCAN_CONTINUE;
804 /* Determine whether to add these LEB properties to the tree */
805 if (!in_tree && valuable(c, lprops))
806 ret |= LPT_SCAN_ADD;
807 /* Exclude non-index LEBs */
808 if (!(lprops->flags & LPROPS_INDEX))
809 return ret;
810 /* Exclude LEBs with too little space */
811 if (lprops->free + lprops->dirty < c->min_idx_node_sz)
812 return ret;
813 /* Finally we found space */
814 data->lnum = lprops->lnum;
815 return LPT_SCAN_ADD | LPT_SCAN_STOP;
816}
817
818/**
819 * find_dirty_idx_leb - find a dirty index LEB.
820 * @c: the UBIFS file-system description object
821 *
822 * This function returns LEB number upon success and a negative error code upon
823 * failure. In particular, -ENOSPC is returned if a dirty index LEB is not
824 * found.
825 *
826 * Note that this function scans the entire LPT but it is called very rarely.
827 */
828static int find_dirty_idx_leb(struct ubifs_info *c)
829{
830 const struct ubifs_lprops *lprops;
831 struct ubifs_lpt_heap *heap;
832 struct scan_data data;
833 int err, i, ret;
834
835 /* Check all structures in memory first */
836 data.lnum = -1;
837 heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
838 for (i = 0; i < heap->cnt; i++) {
839 lprops = heap->arr[i];
840 ret = scan_dirty_idx_cb(c, lprops, 1, &data);
841 if (ret & LPT_SCAN_STOP)
842 goto found;
843 }
844 list_for_each_entry(lprops, &c->frdi_idx_list, list) {
845 ret = scan_dirty_idx_cb(c, lprops, 1, &data);
846 if (ret & LPT_SCAN_STOP)
847 goto found;
848 }
849 list_for_each_entry(lprops, &c->uncat_list, list) {
850 ret = scan_dirty_idx_cb(c, lprops, 1, &data);
851 if (ret & LPT_SCAN_STOP)
852 goto found;
853 }
854 if (c->pnodes_have >= c->pnode_cnt)
855 /* All pnodes are in memory, so skip scan */
856 return -ENOSPC;
857 err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
858 (ubifs_lpt_scan_callback)scan_dirty_idx_cb,
859 &data);
860 if (err)
861 return err;
862found:
863 ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
864 c->lscan_lnum = data.lnum;
865 lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
866 if (IS_ERR(lprops))
867 return PTR_ERR(lprops);
868 ubifs_assert(lprops->lnum == data.lnum);
869 ubifs_assert(lprops->free + lprops->dirty >= c->min_idx_node_sz);
870 ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
871 ubifs_assert((lprops->flags & LPROPS_INDEX));
872
873 dbg_find("found dirty LEB %d, free %d, dirty %d, flags %#x",
874 lprops->lnum, lprops->free, lprops->dirty, lprops->flags);
875
876 lprops = ubifs_change_lp(c, lprops, LPROPS_NC, LPROPS_NC,
877 lprops->flags | LPROPS_TAKEN, 0);
878 if (IS_ERR(lprops))
879 return PTR_ERR(lprops);
880
881 return lprops->lnum;
882}
883
884/**
885 * get_idx_gc_leb - try to get a LEB number from trivial GC.
886 * @c: the UBIFS file-system description object
887 */
888static int get_idx_gc_leb(struct ubifs_info *c)
889{
890 const struct ubifs_lprops *lp;
891 int err, lnum;
892
893 err = ubifs_get_idx_gc_leb(c);
894 if (err < 0)
895 return err;
896 lnum = err;
897 /*
898 * The LEB was due to be unmapped after the commit but
899 * it is needed now for this commit.
900 */
901 lp = ubifs_lpt_lookup_dirty(c, lnum);
902 if (unlikely(IS_ERR(lp)))
903 return PTR_ERR(lp);
904 lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
905 lp->flags | LPROPS_INDEX, -1);
906 if (unlikely(IS_ERR(lp)))
907 return PTR_ERR(lp);
908 dbg_find("LEB %d, dirty %d and free %d flags %#x",
909 lp->lnum, lp->dirty, lp->free, lp->flags);
910 return lnum;
911}
912
913/**
914 * find_dirtiest_idx_leb - find dirtiest index LEB from dirtiest array.
915 * @c: the UBIFS file-system description object
916 */
917static int find_dirtiest_idx_leb(struct ubifs_info *c)
918{
919 const struct ubifs_lprops *lp;
920 int lnum;
921
922 while (1) {
923 if (!c->dirty_idx.cnt)
924 return -ENOSPC;
925 /* The lprops pointers were replaced by LEB numbers */
926 lnum = (size_t)c->dirty_idx.arr[--c->dirty_idx.cnt];
927 lp = ubifs_lpt_lookup(c, lnum);
928 if (IS_ERR(lp))
929 return PTR_ERR(lp);
930 if ((lp->flags & LPROPS_TAKEN) || !(lp->flags & LPROPS_INDEX))
931 continue;
932 lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
933 lp->flags | LPROPS_TAKEN, 0);
934 if (IS_ERR(lp))
935 return PTR_ERR(lp);
936 break;
937 }
938 dbg_find("LEB %d, dirty %d and free %d flags %#x", lp->lnum, lp->dirty,
939 lp->free, lp->flags);
940 ubifs_assert(lp->flags | LPROPS_TAKEN);
941 ubifs_assert(lp->flags | LPROPS_INDEX);
942 return lnum;
943}
944
945/**
946 * ubifs_find_dirty_idx_leb - try to find dirtiest index LEB as at last commit.
947 * @c: the UBIFS file-system description object
948 *
949 * This function attempts to find an untaken index LEB with the most free and
950 * dirty space that can be used without overwriting index nodes that were in the
951 * last index committed.
952 */
953int ubifs_find_dirty_idx_leb(struct ubifs_info *c)
954{
955 int err;
956
957 ubifs_get_lprops(c);
958
959 /*
960 * We made an array of the dirtiest index LEB numbers as at the start of
961 * last commit. Try that array first.
962 */
963 err = find_dirtiest_idx_leb(c);
964
965 /* Next try scanning the entire LPT */
966 if (err == -ENOSPC)
967 err = find_dirty_idx_leb(c);
968
969 /* Finally take any index LEBs awaiting trivial GC */
970 if (err == -ENOSPC)
971 err = get_idx_gc_leb(c);
972
973 ubifs_release_lprops(c);
974 return err;
975}
generated by cgit v1.2.2 (git 2.25.0) at 2024-12-07 18:55:23 -0500