Merge branches 'core-fixes-for-linus' and 'irq-fixes-for-linus' of git://git.kernel...
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / fs / ubifs / find.c
blob2559d174e0040a45578fcc2e7612522a08e99a2f
1 /*
2 * This file is part of UBIFS.
4 * Copyright (C) 2006-2008 Nokia Corporation.
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.
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.
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
19 * Authors: Artem Bityutskiy (Битюцкий Артём)
20 * Adrian Hunter
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.
29 #include <linux/sort.h>
30 #include "ubifs.h"
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
39 struct scan_data {
40 int min_space;
41 int pick_free;
42 int lnum;
43 int exclude_index;
46 /**
47 * valuable - determine whether LEB properties are valuable.
48 * @c: the UBIFS file-system description object
49 * @lprops: LEB properties
51 * This function return %1 if the LEB properties should be added to the LEB
52 * properties tree in memory. Otherwise %0 is returned.
54 static int valuable(struct ubifs_info *c, const struct ubifs_lprops *lprops)
56 int n, cat = lprops->flags & LPROPS_CAT_MASK;
57 struct ubifs_lpt_heap *heap;
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;
80 return 0;
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
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).
95 static int scan_for_dirty_cb(struct ubifs_info *c,
96 const struct ubifs_lprops *lprops, int in_tree,
97 struct scan_data *data)
99 int ret = LPT_SCAN_CONTINUE;
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;
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
133 * This function returns a pointer to the LEB properties found or a negative
134 * error code.
136 static const struct ubifs_lprops *scan_for_dirty(struct ubifs_info *c,
137 int min_space, int pick_free,
138 int exclude_index)
140 const struct ubifs_lprops *lprops;
141 struct ubifs_lpt_heap *heap;
142 struct scan_data data;
143 int err, i;
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;
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.
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;
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;
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
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.
214 * Note, LEBs which have less than dead watermark of free + dirty space are
215 * never picked by this function.
217 * The additional @pick_free argument controls if this function has to return a
218 * free or freeable LEB if one is present. For example, GC must to set it to %1,
219 * when called from the journal space reservation function, because the
220 * appearance of free space may coincide with the loss of enough dirty space
221 * for GC to succeed anyway.
223 * In contrast, if the Garbage Collector is called from budgeting, it should
224 * just make free space, not return LEBs which are already free or freeable.
226 * In addition @pick_free is set to %2 by the recovery process in order to
227 * recover gc_lnum in which case an index LEB must not be returned.
229 * This function returns zero and the LEB properties of found dirty LEB in case
230 * of success, %-ENOSPC if no dirty LEB was found and a negative error code in
231 * case of other failures. The returned LEB is marked as "taken".
233 int ubifs_find_dirty_leb(struct ubifs_info *c, struct ubifs_lprops *ret_lp,
234 int min_space, int pick_free)
236 int err = 0, sum, exclude_index = pick_free == 2 ? 1 : 0;
237 const struct ubifs_lprops *lp = NULL, *idx_lp = NULL;
238 struct ubifs_lpt_heap *heap, *idx_heap;
240 ubifs_get_lprops(c);
242 if (pick_free) {
243 int lebs, rsvd_idx_lebs = 0;
245 spin_lock(&c->space_lock);
246 lebs = c->lst.empty_lebs + c->idx_gc_cnt;
247 lebs += c->freeable_cnt - c->lst.taken_empty_lebs;
250 * Note, the index may consume more LEBs than have been reserved
251 * for it. It is OK because it might be consolidated by GC.
252 * But if the index takes fewer LEBs than it is reserved for it,
253 * this function must avoid picking those reserved LEBs.
255 if (c->bi.min_idx_lebs >= c->lst.idx_lebs) {
256 rsvd_idx_lebs = c->bi.min_idx_lebs - c->lst.idx_lebs;
257 exclude_index = 1;
259 spin_unlock(&c->space_lock);
261 /* Check if there are enough free LEBs for the index */
262 if (rsvd_idx_lebs < lebs) {
263 /* OK, try to find an empty LEB */
264 lp = ubifs_fast_find_empty(c);
265 if (lp)
266 goto found;
268 /* Or a freeable LEB */
269 lp = ubifs_fast_find_freeable(c);
270 if (lp)
271 goto found;
272 } else
274 * We cannot pick free/freeable LEBs in the below code.
276 pick_free = 0;
277 } else {
278 spin_lock(&c->space_lock);
279 exclude_index = (c->bi.min_idx_lebs >= c->lst.idx_lebs);
280 spin_unlock(&c->space_lock);
283 /* Look on the dirty and dirty index heaps */
284 heap = &c->lpt_heap[LPROPS_DIRTY - 1];
285 idx_heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
287 if (idx_heap->cnt && !exclude_index) {
288 idx_lp = idx_heap->arr[0];
289 sum = idx_lp->free + idx_lp->dirty;
291 * Since we reserve thrice as much space for the index than it
292 * actually takes, it does not make sense to pick indexing LEBs
293 * with less than, say, half LEB of dirty space. May be half is
294 * not the optimal boundary - this should be tested and
295 * checked. This boundary should determine how much we use
296 * in-the-gaps to consolidate the index comparing to how much
297 * we use garbage collector to consolidate it. The "half"
298 * criteria just feels to be fine.
300 if (sum < min_space || sum < c->half_leb_size)
301 idx_lp = NULL;
304 if (heap->cnt) {
305 lp = heap->arr[0];
306 if (lp->dirty + lp->free < min_space)
307 lp = NULL;
310 /* Pick the LEB with most space */
311 if (idx_lp && lp) {
312 if (idx_lp->free + idx_lp->dirty >= lp->free + lp->dirty)
313 lp = idx_lp;
314 } else if (idx_lp && !lp)
315 lp = idx_lp;
317 if (lp) {
318 ubifs_assert(lp->free + lp->dirty >= c->dead_wm);
319 goto found;
322 /* Did not find a dirty LEB on the dirty heaps, have to scan */
323 dbg_find("scanning LPT for a dirty LEB");
324 lp = scan_for_dirty(c, min_space, pick_free, exclude_index);
325 if (IS_ERR(lp)) {
326 err = PTR_ERR(lp);
327 goto out;
329 ubifs_assert(lp->dirty >= c->dead_wm ||
330 (pick_free && lp->free + lp->dirty == c->leb_size));
332 found:
333 dbg_find("found LEB %d, free %d, dirty %d, flags %#x",
334 lp->lnum, lp->free, lp->dirty, lp->flags);
336 lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
337 lp->flags | LPROPS_TAKEN, 0);
338 if (IS_ERR(lp)) {
339 err = PTR_ERR(lp);
340 goto out;
343 memcpy(ret_lp, lp, sizeof(struct ubifs_lprops));
345 out:
346 ubifs_release_lprops(c);
347 return err;
351 * scan_for_free_cb - free space scan callback.
352 * @c: the UBIFS file-system description object
353 * @lprops: LEB properties to scan
354 * @in_tree: whether the LEB properties are in main memory
355 * @data: information passed to and from the caller of the scan
357 * This function returns a code that indicates whether the scan should continue
358 * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
359 * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
360 * (%LPT_SCAN_STOP).
362 static int scan_for_free_cb(struct ubifs_info *c,
363 const struct ubifs_lprops *lprops, int in_tree,
364 struct scan_data *data)
366 int ret = LPT_SCAN_CONTINUE;
368 /* Exclude LEBs that are currently in use */
369 if (lprops->flags & LPROPS_TAKEN)
370 return LPT_SCAN_CONTINUE;
371 /* Determine whether to add these LEB properties to the tree */
372 if (!in_tree && valuable(c, lprops))
373 ret |= LPT_SCAN_ADD;
374 /* Exclude index LEBs */
375 if (lprops->flags & LPROPS_INDEX)
376 return ret;
377 /* Exclude LEBs with too little space */
378 if (lprops->free < data->min_space)
379 return ret;
380 /* If specified, exclude empty LEBs */
381 if (!data->pick_free && lprops->free == c->leb_size)
382 return ret;
384 * LEBs that have only free and dirty space must not be allocated
385 * because they may have been unmapped already or they may have data
386 * that is obsolete only because of nodes that are still sitting in a
387 * wbuf.
389 if (lprops->free + lprops->dirty == c->leb_size && lprops->dirty > 0)
390 return ret;
391 /* Finally we found space */
392 data->lnum = lprops->lnum;
393 return LPT_SCAN_ADD | LPT_SCAN_STOP;
397 * do_find_free_space - find a data LEB with free space.
398 * @c: the UBIFS file-system description object
399 * @min_space: minimum amount of free space required
400 * @pick_free: whether it is OK to scan for empty LEBs
401 * @squeeze: whether to try to find space in a non-empty LEB first
403 * This function returns a pointer to the LEB properties found or a negative
404 * error code.
406 static
407 const struct ubifs_lprops *do_find_free_space(struct ubifs_info *c,
408 int min_space, int pick_free,
409 int squeeze)
411 const struct ubifs_lprops *lprops;
412 struct ubifs_lpt_heap *heap;
413 struct scan_data data;
414 int err, i;
416 if (squeeze) {
417 lprops = ubifs_fast_find_free(c);
418 if (lprops && lprops->free >= min_space)
419 return lprops;
421 if (pick_free) {
422 lprops = ubifs_fast_find_empty(c);
423 if (lprops)
424 return lprops;
426 if (!squeeze) {
427 lprops = ubifs_fast_find_free(c);
428 if (lprops && lprops->free >= min_space)
429 return lprops;
431 /* There may be an LEB with enough free space on the dirty heap */
432 heap = &c->lpt_heap[LPROPS_DIRTY - 1];
433 for (i = 0; i < heap->cnt; i++) {
434 lprops = heap->arr[i];
435 if (lprops->free >= min_space)
436 return lprops;
439 * A LEB may have fallen off of the bottom of the free heap, and ended
440 * up as uncategorized even though it has enough free space for us now,
441 * so check the uncategorized list. N.B. neither empty nor freeable LEBs
442 * can end up as uncategorized because they are kept on lists not
443 * finite-sized heaps.
445 list_for_each_entry(lprops, &c->uncat_list, list) {
446 if (lprops->flags & LPROPS_TAKEN)
447 continue;
448 if (lprops->flags & LPROPS_INDEX)
449 continue;
450 if (lprops->free >= min_space)
451 return lprops;
453 /* We have looked everywhere in main memory, now scan the flash */
454 if (c->pnodes_have >= c->pnode_cnt)
455 /* All pnodes are in memory, so skip scan */
456 return ERR_PTR(-ENOSPC);
457 data.min_space = min_space;
458 data.pick_free = pick_free;
459 data.lnum = -1;
460 err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
461 (ubifs_lpt_scan_callback)scan_for_free_cb,
462 &data);
463 if (err)
464 return ERR_PTR(err);
465 ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
466 c->lscan_lnum = data.lnum;
467 lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
468 if (IS_ERR(lprops))
469 return lprops;
470 ubifs_assert(lprops->lnum == data.lnum);
471 ubifs_assert(lprops->free >= min_space);
472 ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
473 ubifs_assert(!(lprops->flags & LPROPS_INDEX));
474 return lprops;
478 * ubifs_find_free_space - find a data LEB with free space.
479 * @c: the UBIFS file-system description object
480 * @min_space: minimum amount of required free space
481 * @offs: contains offset of where free space starts on exit
482 * @squeeze: whether to try to find space in a non-empty LEB first
484 * This function looks for an LEB with at least @min_space bytes of free space.
485 * It tries to find an empty LEB if possible. If no empty LEBs are available,
486 * this function searches for a non-empty data LEB. The returned LEB is marked
487 * as "taken".
489 * This function returns found LEB number in case of success, %-ENOSPC if it
490 * failed to find a LEB with @min_space bytes of free space and other a negative
491 * error codes in case of failure.
493 int ubifs_find_free_space(struct ubifs_info *c, int min_space, int *offs,
494 int squeeze)
496 const struct ubifs_lprops *lprops;
497 int lebs, rsvd_idx_lebs, pick_free = 0, err, lnum, flags;
499 dbg_find("min_space %d", min_space);
500 ubifs_get_lprops(c);
502 /* Check if there are enough empty LEBs for commit */
503 spin_lock(&c->space_lock);
504 if (c->bi.min_idx_lebs > c->lst.idx_lebs)
505 rsvd_idx_lebs = c->bi.min_idx_lebs - c->lst.idx_lebs;
506 else
507 rsvd_idx_lebs = 0;
508 lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
509 c->lst.taken_empty_lebs;
510 if (rsvd_idx_lebs < lebs)
512 * OK to allocate an empty LEB, but we still don't want to go
513 * looking for one if there aren't any.
515 if (c->lst.empty_lebs - c->lst.taken_empty_lebs > 0) {
516 pick_free = 1;
518 * Because we release the space lock, we must account
519 * for this allocation here. After the LEB properties
520 * flags have been updated, we subtract one. Note, the
521 * result of this is that lprops also decreases
522 * @taken_empty_lebs in 'ubifs_change_lp()', so it is
523 * off by one for a short period of time which may
524 * introduce a small disturbance to budgeting
525 * calculations, but this is harmless because at the
526 * worst case this would make the budgeting subsystem
527 * be more pessimistic than needed.
529 * Fundamentally, this is about serialization of the
530 * budgeting and lprops subsystems. We could make the
531 * @space_lock a mutex and avoid dropping it before
532 * calling 'ubifs_change_lp()', but mutex is more
533 * heavy-weight, and we want budgeting to be as fast as
534 * possible.
536 c->lst.taken_empty_lebs += 1;
538 spin_unlock(&c->space_lock);
540 lprops = do_find_free_space(c, min_space, pick_free, squeeze);
541 if (IS_ERR(lprops)) {
542 err = PTR_ERR(lprops);
543 goto out;
546 lnum = lprops->lnum;
547 flags = lprops->flags | LPROPS_TAKEN;
549 lprops = ubifs_change_lp(c, lprops, LPROPS_NC, LPROPS_NC, flags, 0);
550 if (IS_ERR(lprops)) {
551 err = PTR_ERR(lprops);
552 goto out;
555 if (pick_free) {
556 spin_lock(&c->space_lock);
557 c->lst.taken_empty_lebs -= 1;
558 spin_unlock(&c->space_lock);
561 *offs = c->leb_size - lprops->free;
562 ubifs_release_lprops(c);
564 if (*offs == 0) {
566 * Ensure that empty LEBs have been unmapped. They may not have
567 * been, for example, because of an unclean unmount. Also
568 * LEBs that were freeable LEBs (free + dirty == leb_size) will
569 * not have been unmapped.
571 err = ubifs_leb_unmap(c, lnum);
572 if (err)
573 return err;
576 dbg_find("found LEB %d, free %d", lnum, c->leb_size - *offs);
577 ubifs_assert(*offs <= c->leb_size - min_space);
578 return lnum;
580 out:
581 if (pick_free) {
582 spin_lock(&c->space_lock);
583 c->lst.taken_empty_lebs -= 1;
584 spin_unlock(&c->space_lock);
586 ubifs_release_lprops(c);
587 return err;
591 * scan_for_idx_cb - callback used by the scan for a free LEB for the index.
592 * @c: the UBIFS file-system description object
593 * @lprops: LEB properties to scan
594 * @in_tree: whether the LEB properties are in main memory
595 * @data: information passed to and from the caller of the scan
597 * This function returns a code that indicates whether the scan should continue
598 * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
599 * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
600 * (%LPT_SCAN_STOP).
602 static int scan_for_idx_cb(struct ubifs_info *c,
603 const struct ubifs_lprops *lprops, int in_tree,
604 struct scan_data *data)
606 int ret = LPT_SCAN_CONTINUE;
608 /* Exclude LEBs that are currently in use */
609 if (lprops->flags & LPROPS_TAKEN)
610 return LPT_SCAN_CONTINUE;
611 /* Determine whether to add these LEB properties to the tree */
612 if (!in_tree && valuable(c, lprops))
613 ret |= LPT_SCAN_ADD;
614 /* Exclude index LEBS */
615 if (lprops->flags & LPROPS_INDEX)
616 return ret;
617 /* Exclude LEBs that cannot be made empty */
618 if (lprops->free + lprops->dirty != c->leb_size)
619 return ret;
621 * We are allocating for the index so it is safe to allocate LEBs with
622 * only free and dirty space, because write buffers are sync'd at commit
623 * start.
625 data->lnum = lprops->lnum;
626 return LPT_SCAN_ADD | LPT_SCAN_STOP;
630 * scan_for_leb_for_idx - scan for a free LEB for the index.
631 * @c: the UBIFS file-system description object
633 static const struct ubifs_lprops *scan_for_leb_for_idx(struct ubifs_info *c)
635 struct ubifs_lprops *lprops;
636 struct scan_data data;
637 int err;
639 data.lnum = -1;
640 err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
641 (ubifs_lpt_scan_callback)scan_for_idx_cb,
642 &data);
643 if (err)
644 return ERR_PTR(err);
645 ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
646 c->lscan_lnum = data.lnum;
647 lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
648 if (IS_ERR(lprops))
649 return lprops;
650 ubifs_assert(lprops->lnum == data.lnum);
651 ubifs_assert(lprops->free + lprops->dirty == c->leb_size);
652 ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
653 ubifs_assert(!(lprops->flags & LPROPS_INDEX));
654 return lprops;
658 * ubifs_find_free_leb_for_idx - find a free LEB for the index.
659 * @c: the UBIFS file-system description object
661 * This function looks for a free LEB and returns that LEB number. The returned
662 * LEB is marked as "taken", "index".
664 * Only empty LEBs are allocated. This is for two reasons. First, the commit
665 * calculates the number of LEBs to allocate based on the assumption that they
666 * will be empty. Secondly, free space at the end of an index LEB is not
667 * guaranteed to be empty because it may have been used by the in-the-gaps
668 * method prior to an unclean unmount.
670 * If no LEB is found %-ENOSPC is returned. For other failures another negative
671 * error code is returned.
673 int ubifs_find_free_leb_for_idx(struct ubifs_info *c)
675 const struct ubifs_lprops *lprops;
676 int lnum = -1, err, flags;
678 ubifs_get_lprops(c);
680 lprops = ubifs_fast_find_empty(c);
681 if (!lprops) {
682 lprops = ubifs_fast_find_freeable(c);
683 if (!lprops) {
684 ubifs_assert(c->freeable_cnt == 0);
685 if (c->lst.empty_lebs - c->lst.taken_empty_lebs > 0) {
686 lprops = scan_for_leb_for_idx(c);
687 if (IS_ERR(lprops)) {
688 err = PTR_ERR(lprops);
689 goto out;
695 if (!lprops) {
696 err = -ENOSPC;
697 goto out;
700 lnum = lprops->lnum;
702 dbg_find("found LEB %d, free %d, dirty %d, flags %#x",
703 lnum, lprops->free, lprops->dirty, lprops->flags);
705 flags = lprops->flags | LPROPS_TAKEN | LPROPS_INDEX;
706 lprops = ubifs_change_lp(c, lprops, c->leb_size, 0, flags, 0);
707 if (IS_ERR(lprops)) {
708 err = PTR_ERR(lprops);
709 goto out;
712 ubifs_release_lprops(c);
715 * Ensure that empty LEBs have been unmapped. They may not have been,
716 * for example, because of an unclean unmount. Also LEBs that were
717 * freeable LEBs (free + dirty == leb_size) will not have been unmapped.
719 err = ubifs_leb_unmap(c, lnum);
720 if (err) {
721 ubifs_change_one_lp(c, lnum, LPROPS_NC, LPROPS_NC, 0,
722 LPROPS_TAKEN | LPROPS_INDEX, 0);
723 return err;
726 return lnum;
728 out:
729 ubifs_release_lprops(c);
730 return err;
733 static int cmp_dirty_idx(const struct ubifs_lprops **a,
734 const struct ubifs_lprops **b)
736 const struct ubifs_lprops *lpa = *a;
737 const struct ubifs_lprops *lpb = *b;
739 return lpa->dirty + lpa->free - lpb->dirty - lpb->free;
742 static void swap_dirty_idx(struct ubifs_lprops **a, struct ubifs_lprops **b,
743 int size)
745 struct ubifs_lprops *t = *a;
747 *a = *b;
748 *b = t;
752 * ubifs_save_dirty_idx_lnums - save an array of the most dirty index LEB nos.
753 * @c: the UBIFS file-system description object
755 * This function is called each commit to create an array of LEB numbers of
756 * dirty index LEBs sorted in order of dirty and free space. This is used by
757 * the in-the-gaps method of TNC commit.
759 int ubifs_save_dirty_idx_lnums(struct ubifs_info *c)
761 int i;
763 ubifs_get_lprops(c);
764 /* Copy the LPROPS_DIRTY_IDX heap */
765 c->dirty_idx.cnt = c->lpt_heap[LPROPS_DIRTY_IDX - 1].cnt;
766 memcpy(c->dirty_idx.arr, c->lpt_heap[LPROPS_DIRTY_IDX - 1].arr,
767 sizeof(void *) * c->dirty_idx.cnt);
768 /* Sort it so that the dirtiest is now at the end */
769 sort(c->dirty_idx.arr, c->dirty_idx.cnt, sizeof(void *),
770 (int (*)(const void *, const void *))cmp_dirty_idx,
771 (void (*)(void *, void *, int))swap_dirty_idx);
772 dbg_find("found %d dirty index LEBs", c->dirty_idx.cnt);
773 if (c->dirty_idx.cnt)
774 dbg_find("dirtiest index LEB is %d with dirty %d and free %d",
775 c->dirty_idx.arr[c->dirty_idx.cnt - 1]->lnum,
776 c->dirty_idx.arr[c->dirty_idx.cnt - 1]->dirty,
777 c->dirty_idx.arr[c->dirty_idx.cnt - 1]->free);
778 /* Replace the lprops pointers with LEB numbers */
779 for (i = 0; i < c->dirty_idx.cnt; i++)
780 c->dirty_idx.arr[i] = (void *)(size_t)c->dirty_idx.arr[i]->lnum;
781 ubifs_release_lprops(c);
782 return 0;
786 * scan_dirty_idx_cb - callback used by the scan for a dirty index LEB.
787 * @c: the UBIFS file-system description object
788 * @lprops: LEB properties to scan
789 * @in_tree: whether the LEB properties are in main memory
790 * @data: information passed to and from the caller of the scan
792 * This function returns a code that indicates whether the scan should continue
793 * (%LPT_SCAN_CONTINUE), whether the LEB properties should be added to the tree
794 * in main memory (%LPT_SCAN_ADD), or whether the scan should stop
795 * (%LPT_SCAN_STOP).
797 static int scan_dirty_idx_cb(struct ubifs_info *c,
798 const struct ubifs_lprops *lprops, int in_tree,
799 struct scan_data *data)
801 int ret = LPT_SCAN_CONTINUE;
803 /* Exclude LEBs that are currently in use */
804 if (lprops->flags & LPROPS_TAKEN)
805 return LPT_SCAN_CONTINUE;
806 /* Determine whether to add these LEB properties to the tree */
807 if (!in_tree && valuable(c, lprops))
808 ret |= LPT_SCAN_ADD;
809 /* Exclude non-index LEBs */
810 if (!(lprops->flags & LPROPS_INDEX))
811 return ret;
812 /* Exclude LEBs with too little space */
813 if (lprops->free + lprops->dirty < c->min_idx_node_sz)
814 return ret;
815 /* Finally we found space */
816 data->lnum = lprops->lnum;
817 return LPT_SCAN_ADD | LPT_SCAN_STOP;
821 * find_dirty_idx_leb - find a dirty index LEB.
822 * @c: the UBIFS file-system description object
824 * This function returns LEB number upon success and a negative error code upon
825 * failure. In particular, -ENOSPC is returned if a dirty index LEB is not
826 * found.
828 * Note that this function scans the entire LPT but it is called very rarely.
830 static int find_dirty_idx_leb(struct ubifs_info *c)
832 const struct ubifs_lprops *lprops;
833 struct ubifs_lpt_heap *heap;
834 struct scan_data data;
835 int err, i, ret;
837 /* Check all structures in memory first */
838 data.lnum = -1;
839 heap = &c->lpt_heap[LPROPS_DIRTY_IDX - 1];
840 for (i = 0; i < heap->cnt; i++) {
841 lprops = heap->arr[i];
842 ret = scan_dirty_idx_cb(c, lprops, 1, &data);
843 if (ret & LPT_SCAN_STOP)
844 goto found;
846 list_for_each_entry(lprops, &c->frdi_idx_list, list) {
847 ret = scan_dirty_idx_cb(c, lprops, 1, &data);
848 if (ret & LPT_SCAN_STOP)
849 goto found;
851 list_for_each_entry(lprops, &c->uncat_list, list) {
852 ret = scan_dirty_idx_cb(c, lprops, 1, &data);
853 if (ret & LPT_SCAN_STOP)
854 goto found;
856 if (c->pnodes_have >= c->pnode_cnt)
857 /* All pnodes are in memory, so skip scan */
858 return -ENOSPC;
859 err = ubifs_lpt_scan_nolock(c, -1, c->lscan_lnum,
860 (ubifs_lpt_scan_callback)scan_dirty_idx_cb,
861 &data);
862 if (err)
863 return err;
864 found:
865 ubifs_assert(data.lnum >= c->main_first && data.lnum < c->leb_cnt);
866 c->lscan_lnum = data.lnum;
867 lprops = ubifs_lpt_lookup_dirty(c, data.lnum);
868 if (IS_ERR(lprops))
869 return PTR_ERR(lprops);
870 ubifs_assert(lprops->lnum == data.lnum);
871 ubifs_assert(lprops->free + lprops->dirty >= c->min_idx_node_sz);
872 ubifs_assert(!(lprops->flags & LPROPS_TAKEN));
873 ubifs_assert((lprops->flags & LPROPS_INDEX));
875 dbg_find("found dirty LEB %d, free %d, dirty %d, flags %#x",
876 lprops->lnum, lprops->free, lprops->dirty, lprops->flags);
878 lprops = ubifs_change_lp(c, lprops, LPROPS_NC, LPROPS_NC,
879 lprops->flags | LPROPS_TAKEN, 0);
880 if (IS_ERR(lprops))
881 return PTR_ERR(lprops);
883 return lprops->lnum;
887 * get_idx_gc_leb - try to get a LEB number from trivial GC.
888 * @c: the UBIFS file-system description object
890 static int get_idx_gc_leb(struct ubifs_info *c)
892 const struct ubifs_lprops *lp;
893 int err, lnum;
895 err = ubifs_get_idx_gc_leb(c);
896 if (err < 0)
897 return err;
898 lnum = err;
900 * The LEB was due to be unmapped after the commit but
901 * it is needed now for this commit.
903 lp = ubifs_lpt_lookup_dirty(c, lnum);
904 if (IS_ERR(lp))
905 return PTR_ERR(lp);
906 lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
907 lp->flags | LPROPS_INDEX, -1);
908 if (IS_ERR(lp))
909 return PTR_ERR(lp);
910 dbg_find("LEB %d, dirty %d and free %d flags %#x",
911 lp->lnum, lp->dirty, lp->free, lp->flags);
912 return lnum;
916 * find_dirtiest_idx_leb - find dirtiest index LEB from dirtiest array.
917 * @c: the UBIFS file-system description object
919 static int find_dirtiest_idx_leb(struct ubifs_info *c)
921 const struct ubifs_lprops *lp;
922 int lnum;
924 while (1) {
925 if (!c->dirty_idx.cnt)
926 return -ENOSPC;
927 /* The lprops pointers were replaced by LEB numbers */
928 lnum = (size_t)c->dirty_idx.arr[--c->dirty_idx.cnt];
929 lp = ubifs_lpt_lookup(c, lnum);
930 if (IS_ERR(lp))
931 return PTR_ERR(lp);
932 if ((lp->flags & LPROPS_TAKEN) || !(lp->flags & LPROPS_INDEX))
933 continue;
934 lp = ubifs_change_lp(c, lp, LPROPS_NC, LPROPS_NC,
935 lp->flags | LPROPS_TAKEN, 0);
936 if (IS_ERR(lp))
937 return PTR_ERR(lp);
938 break;
940 dbg_find("LEB %d, dirty %d and free %d flags %#x", lp->lnum, lp->dirty,
941 lp->free, lp->flags);
942 ubifs_assert(lp->flags | LPROPS_TAKEN);
943 ubifs_assert(lp->flags | LPROPS_INDEX);
944 return lnum;
948 * ubifs_find_dirty_idx_leb - try to find dirtiest index LEB as at last commit.
949 * @c: the UBIFS file-system description object
951 * This function attempts to find an untaken index LEB with the most free and
952 * dirty space that can be used without overwriting index nodes that were in the
953 * last index committed.
955 int ubifs_find_dirty_idx_leb(struct ubifs_info *c)
957 int err;
959 ubifs_get_lprops(c);
962 * We made an array of the dirtiest index LEB numbers as at the start of
963 * last commit. Try that array first.
965 err = find_dirtiest_idx_leb(c);
967 /* Next try scanning the entire LPT */
968 if (err == -ENOSPC)
969 err = find_dirty_idx_leb(c);
971 /* Finally take any index LEBs awaiting trivial GC */
972 if (err == -ENOSPC)
973 err = get_idx_gc_leb(c);
975 ubifs_release_lprops(c);
976 return err;