blob: c6657a27118cfe1e707835a45bdc7680fd1c6290 [file] [log] [blame]
Anton Habegger040cc7b2015-01-22 22:29:11 +01001/*
2 * This file is part of UBIFS.
3 *
4 * Copyright (C) 2006-2008 Nokia Corporation.
5 *
6 * SPDX-License-Identifier: GPL-2.0
7 *
8 * Authors: Adrian Hunter
9 * Artem Bityutskiy (Битюцкий Артём)
10 */
11
12/*
13 * This file implements garbage collection. The procedure for garbage collection
14 * is different depending on whether a LEB as an index LEB (contains index
15 * nodes) or not. For non-index LEBs, garbage collection finds a LEB which
16 * contains a lot of dirty space (obsolete nodes), and copies the non-obsolete
17 * nodes to the journal, at which point the garbage-collected LEB is free to be
18 * reused. For index LEBs, garbage collection marks the non-obsolete index nodes
19 * dirty in the TNC, and after the next commit, the garbage-collected LEB is
20 * to be reused. Garbage collection will cause the number of dirty index nodes
21 * to grow, however sufficient space is reserved for the index to ensure the
22 * commit will never run out of space.
23 *
24 * Notes about dead watermark. At current UBIFS implementation we assume that
25 * LEBs which have less than @c->dead_wm bytes of free + dirty space are full
26 * and not worth garbage-collecting. The dead watermark is one min. I/O unit
27 * size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS
28 * Garbage Collector has to synchronize the GC head's write buffer before
29 * returning, so this is about wasting one min. I/O unit. However, UBIFS GC can
30 * actually reclaim even very small pieces of dirty space by garbage collecting
31 * enough dirty LEBs, but we do not bother doing this at this implementation.
32 *
33 * Notes about dark watermark. The results of GC work depends on how big are
34 * the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed,
35 * if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would
36 * have to waste large pieces of free space at the end of LEB B, because nodes
37 * from LEB A would not fit. And the worst situation is when all nodes are of
38 * maximum size. So dark watermark is the amount of free + dirty space in LEB
39 * which are guaranteed to be reclaimable. If LEB has less space, the GC might
40 * be unable to reclaim it. So, LEBs with free + dirty greater than dark
41 * watermark are "good" LEBs from GC's point of few. The other LEBs are not so
42 * good, and GC takes extra care when moving them.
43 */
44#ifndef __UBOOT__
45#include <linux/slab.h>
46#include <linux/pagemap.h>
47#include <linux/list_sort.h>
48#endif
49#include "ubifs.h"
50
51#ifndef __UBOOT__
52/*
53 * GC may need to move more than one LEB to make progress. The below constants
54 * define "soft" and "hard" limits on the number of LEBs the garbage collector
55 * may move.
56 */
57#define SOFT_LEBS_LIMIT 4
58#define HARD_LEBS_LIMIT 32
59
60/**
61 * switch_gc_head - switch the garbage collection journal head.
62 * @c: UBIFS file-system description object
63 * @buf: buffer to write
64 * @len: length of the buffer to write
65 * @lnum: LEB number written is returned here
66 * @offs: offset written is returned here
67 *
68 * This function switch the GC head to the next LEB which is reserved in
69 * @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required,
70 * and other negative error code in case of failures.
71 */
72static int switch_gc_head(struct ubifs_info *c)
73{
74 int err, gc_lnum = c->gc_lnum;
75 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
76
77 ubifs_assert(gc_lnum != -1);
78 dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)",
79 wbuf->lnum, wbuf->offs + wbuf->used, gc_lnum,
80 c->leb_size - wbuf->offs - wbuf->used);
81
82 err = ubifs_wbuf_sync_nolock(wbuf);
83 if (err)
84 return err;
85
86 /*
87 * The GC write-buffer was synchronized, we may safely unmap
88 * 'c->gc_lnum'.
89 */
90 err = ubifs_leb_unmap(c, gc_lnum);
91 if (err)
92 return err;
93
94 err = ubifs_wbuf_sync_nolock(wbuf);
95 if (err)
96 return err;
97
98 err = ubifs_add_bud_to_log(c, GCHD, gc_lnum, 0);
99 if (err)
100 return err;
101
102 c->gc_lnum = -1;
103 err = ubifs_wbuf_seek_nolock(wbuf, gc_lnum, 0);
104 return err;
105}
106
107/**
108 * data_nodes_cmp - compare 2 data nodes.
109 * @priv: UBIFS file-system description object
110 * @a: first data node
111 * @a: second data node
112 *
113 * This function compares data nodes @a and @b. Returns %1 if @a has greater
114 * inode or block number, and %-1 otherwise.
115 */
116static int data_nodes_cmp(void *priv, struct list_head *a, struct list_head *b)
117{
118 ino_t inuma, inumb;
119 struct ubifs_info *c = priv;
120 struct ubifs_scan_node *sa, *sb;
121
122 cond_resched();
123 if (a == b)
124 return 0;
125
126 sa = list_entry(a, struct ubifs_scan_node, list);
127 sb = list_entry(b, struct ubifs_scan_node, list);
128
129 ubifs_assert(key_type(c, &sa->key) == UBIFS_DATA_KEY);
130 ubifs_assert(key_type(c, &sb->key) == UBIFS_DATA_KEY);
131 ubifs_assert(sa->type == UBIFS_DATA_NODE);
132 ubifs_assert(sb->type == UBIFS_DATA_NODE);
133
134 inuma = key_inum(c, &sa->key);
135 inumb = key_inum(c, &sb->key);
136
137 if (inuma == inumb) {
138 unsigned int blka = key_block(c, &sa->key);
139 unsigned int blkb = key_block(c, &sb->key);
140
141 if (blka <= blkb)
142 return -1;
143 } else if (inuma <= inumb)
144 return -1;
145
146 return 1;
147}
148
149/*
150 * nondata_nodes_cmp - compare 2 non-data nodes.
151 * @priv: UBIFS file-system description object
152 * @a: first node
153 * @a: second node
154 *
155 * This function compares nodes @a and @b. It makes sure that inode nodes go
156 * first and sorted by length in descending order. Directory entry nodes go
157 * after inode nodes and are sorted in ascending hash valuer order.
158 */
159static int nondata_nodes_cmp(void *priv, struct list_head *a,
160 struct list_head *b)
161{
162 ino_t inuma, inumb;
163 struct ubifs_info *c = priv;
164 struct ubifs_scan_node *sa, *sb;
165
166 cond_resched();
167 if (a == b)
168 return 0;
169
170 sa = list_entry(a, struct ubifs_scan_node, list);
171 sb = list_entry(b, struct ubifs_scan_node, list);
172
173 ubifs_assert(key_type(c, &sa->key) != UBIFS_DATA_KEY &&
174 key_type(c, &sb->key) != UBIFS_DATA_KEY);
175 ubifs_assert(sa->type != UBIFS_DATA_NODE &&
176 sb->type != UBIFS_DATA_NODE);
177
178 /* Inodes go before directory entries */
179 if (sa->type == UBIFS_INO_NODE) {
180 if (sb->type == UBIFS_INO_NODE)
181 return sb->len - sa->len;
182 return -1;
183 }
184 if (sb->type == UBIFS_INO_NODE)
185 return 1;
186
187 ubifs_assert(key_type(c, &sa->key) == UBIFS_DENT_KEY ||
188 key_type(c, &sa->key) == UBIFS_XENT_KEY);
189 ubifs_assert(key_type(c, &sb->key) == UBIFS_DENT_KEY ||
190 key_type(c, &sb->key) == UBIFS_XENT_KEY);
191 ubifs_assert(sa->type == UBIFS_DENT_NODE ||
192 sa->type == UBIFS_XENT_NODE);
193 ubifs_assert(sb->type == UBIFS_DENT_NODE ||
194 sb->type == UBIFS_XENT_NODE);
195
196 inuma = key_inum(c, &sa->key);
197 inumb = key_inum(c, &sb->key);
198
199 if (inuma == inumb) {
200 uint32_t hasha = key_hash(c, &sa->key);
201 uint32_t hashb = key_hash(c, &sb->key);
202
203 if (hasha <= hashb)
204 return -1;
205 } else if (inuma <= inumb)
206 return -1;
207
208 return 1;
209}
210
211/**
212 * sort_nodes - sort nodes for GC.
213 * @c: UBIFS file-system description object
214 * @sleb: describes nodes to sort and contains the result on exit
215 * @nondata: contains non-data nodes on exit
216 * @min: minimum node size is returned here
217 *
218 * This function sorts the list of inodes to garbage collect. First of all, it
219 * kills obsolete nodes and separates data and non-data nodes to the
220 * @sleb->nodes and @nondata lists correspondingly.
221 *
222 * Data nodes are then sorted in block number order - this is important for
223 * bulk-read; data nodes with lower inode number go before data nodes with
224 * higher inode number, and data nodes with lower block number go before data
225 * nodes with higher block number;
226 *
227 * Non-data nodes are sorted as follows.
228 * o First go inode nodes - they are sorted in descending length order.
229 * o Then go directory entry nodes - they are sorted in hash order, which
230 * should supposedly optimize 'readdir()'. Direntry nodes with lower parent
231 * inode number go before direntry nodes with higher parent inode number,
232 * and direntry nodes with lower name hash values go before direntry nodes
233 * with higher name hash values.
234 *
235 * This function returns zero in case of success and a negative error code in
236 * case of failure.
237 */
238static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
239 struct list_head *nondata, int *min)
240{
241 int err;
242 struct ubifs_scan_node *snod, *tmp;
243
244 *min = INT_MAX;
245
246 /* Separate data nodes and non-data nodes */
247 list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
248 ubifs_assert(snod->type == UBIFS_INO_NODE ||
249 snod->type == UBIFS_DATA_NODE ||
250 snod->type == UBIFS_DENT_NODE ||
251 snod->type == UBIFS_XENT_NODE ||
252 snod->type == UBIFS_TRUN_NODE);
253
254 if (snod->type != UBIFS_INO_NODE &&
255 snod->type != UBIFS_DATA_NODE &&
256 snod->type != UBIFS_DENT_NODE &&
257 snod->type != UBIFS_XENT_NODE) {
258 /* Probably truncation node, zap it */
259 list_del(&snod->list);
260 kfree(snod);
261 continue;
262 }
263
264 ubifs_assert(key_type(c, &snod->key) == UBIFS_DATA_KEY ||
265 key_type(c, &snod->key) == UBIFS_INO_KEY ||
266 key_type(c, &snod->key) == UBIFS_DENT_KEY ||
267 key_type(c, &snod->key) == UBIFS_XENT_KEY);
268
269 err = ubifs_tnc_has_node(c, &snod->key, 0, sleb->lnum,
270 snod->offs, 0);
271 if (err < 0)
272 return err;
273
274 if (!err) {
275 /* The node is obsolete, remove it from the list */
276 list_del(&snod->list);
277 kfree(snod);
278 continue;
279 }
280
281 if (snod->len < *min)
282 *min = snod->len;
283
284 if (key_type(c, &snod->key) != UBIFS_DATA_KEY)
285 list_move_tail(&snod->list, nondata);
286 }
287
288 /* Sort data and non-data nodes */
289 list_sort(c, &sleb->nodes, &data_nodes_cmp);
290 list_sort(c, nondata, &nondata_nodes_cmp);
291
292 err = dbg_check_data_nodes_order(c, &sleb->nodes);
293 if (err)
294 return err;
295 err = dbg_check_nondata_nodes_order(c, nondata);
296 if (err)
297 return err;
298 return 0;
299}
300
301/**
302 * move_node - move a node.
303 * @c: UBIFS file-system description object
304 * @sleb: describes the LEB to move nodes from
305 * @snod: the mode to move
306 * @wbuf: write-buffer to move node to
307 *
308 * This function moves node @snod to @wbuf, changes TNC correspondingly, and
309 * destroys @snod. Returns zero in case of success and a negative error code in
310 * case of failure.
311 */
312static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
313 struct ubifs_scan_node *snod, struct ubifs_wbuf *wbuf)
314{
315 int err, new_lnum = wbuf->lnum, new_offs = wbuf->offs + wbuf->used;
316
317 cond_resched();
318 err = ubifs_wbuf_write_nolock(wbuf, snod->node, snod->len);
319 if (err)
320 return err;
321
322 err = ubifs_tnc_replace(c, &snod->key, sleb->lnum,
323 snod->offs, new_lnum, new_offs,
324 snod->len);
325 list_del(&snod->list);
326 kfree(snod);
327 return err;
328}
329
330/**
331 * move_nodes - move nodes.
332 * @c: UBIFS file-system description object
333 * @sleb: describes the LEB to move nodes from
334 *
335 * This function moves valid nodes from data LEB described by @sleb to the GC
336 * journal head. This function returns zero in case of success, %-EAGAIN if
337 * commit is required, and other negative error codes in case of other
338 * failures.
339 */
340static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
341{
342 int err, min;
343 LIST_HEAD(nondata);
344 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
345
346 if (wbuf->lnum == -1) {
347 /*
348 * The GC journal head is not set, because it is the first GC
349 * invocation since mount.
350 */
351 err = switch_gc_head(c);
352 if (err)
353 return err;
354 }
355
356 err = sort_nodes(c, sleb, &nondata, &min);
357 if (err)
358 goto out;
359
360 /* Write nodes to their new location. Use the first-fit strategy */
361 while (1) {
362 int avail;
363 struct ubifs_scan_node *snod, *tmp;
364
365 /* Move data nodes */
366 list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
367 avail = c->leb_size - wbuf->offs - wbuf->used;
368 if (snod->len > avail)
369 /*
370 * Do not skip data nodes in order to optimize
371 * bulk-read.
372 */
373 break;
374
375 err = move_node(c, sleb, snod, wbuf);
376 if (err)
377 goto out;
378 }
379
380 /* Move non-data nodes */
381 list_for_each_entry_safe(snod, tmp, &nondata, list) {
382 avail = c->leb_size - wbuf->offs - wbuf->used;
383 if (avail < min)
384 break;
385
386 if (snod->len > avail) {
387 /*
388 * Keep going only if this is an inode with
389 * some data. Otherwise stop and switch the GC
390 * head. IOW, we assume that data-less inode
391 * nodes and direntry nodes are roughly of the
392 * same size.
393 */
394 if (key_type(c, &snod->key) == UBIFS_DENT_KEY ||
395 snod->len == UBIFS_INO_NODE_SZ)
396 break;
397 continue;
398 }
399
400 err = move_node(c, sleb, snod, wbuf);
401 if (err)
402 goto out;
403 }
404
405 if (list_empty(&sleb->nodes) && list_empty(&nondata))
406 break;
407
408 /*
409 * Waste the rest of the space in the LEB and switch to the
410 * next LEB.
411 */
412 err = switch_gc_head(c);
413 if (err)
414 goto out;
415 }
416
417 return 0;
418
419out:
420 list_splice_tail(&nondata, &sleb->nodes);
421 return err;
422}
423
424/**
425 * gc_sync_wbufs - sync write-buffers for GC.
426 * @c: UBIFS file-system description object
427 *
428 * We must guarantee that obsoleting nodes are on flash. Unfortunately they may
429 * be in a write-buffer instead. That is, a node could be written to a
430 * write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is
431 * erased before the write-buffer is sync'd and then there is an unclean
432 * unmount, then an existing node is lost. To avoid this, we sync all
433 * write-buffers.
434 *
435 * This function returns %0 on success or a negative error code on failure.
436 */
437static int gc_sync_wbufs(struct ubifs_info *c)
438{
439 int err, i;
440
441 for (i = 0; i < c->jhead_cnt; i++) {
442 if (i == GCHD)
443 continue;
444 err = ubifs_wbuf_sync(&c->jheads[i].wbuf);
445 if (err)
446 return err;
447 }
448 return 0;
449}
450
451/**
452 * ubifs_garbage_collect_leb - garbage-collect a logical eraseblock.
453 * @c: UBIFS file-system description object
454 * @lp: describes the LEB to garbage collect
455 *
456 * This function garbage-collects an LEB and returns one of the @LEB_FREED,
457 * @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is
458 * required, and other negative error codes in case of failures.
459 */
460int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp)
461{
462 struct ubifs_scan_leb *sleb;
463 struct ubifs_scan_node *snod;
464 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
465 int err = 0, lnum = lp->lnum;
466
467 ubifs_assert(c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 ||
468 c->need_recovery);
469 ubifs_assert(c->gc_lnum != lnum);
470 ubifs_assert(wbuf->lnum != lnum);
471
472 if (lp->free + lp->dirty == c->leb_size) {
473 /* Special case - a free LEB */
474 dbg_gc("LEB %d is free, return it", lp->lnum);
475 ubifs_assert(!(lp->flags & LPROPS_INDEX));
476
477 if (lp->free != c->leb_size) {
478 /*
479 * Write buffers must be sync'd before unmapping
480 * freeable LEBs, because one of them may contain data
481 * which obsoletes something in 'lp->pnum'.
482 */
483 err = gc_sync_wbufs(c);
484 if (err)
485 return err;
486 err = ubifs_change_one_lp(c, lp->lnum, c->leb_size,
487 0, 0, 0, 0);
488 if (err)
489 return err;
490 }
491 err = ubifs_leb_unmap(c, lp->lnum);
492 if (err)
493 return err;
494
495 if (c->gc_lnum == -1) {
496 c->gc_lnum = lnum;
497 return LEB_RETAINED;
498 }
499
500 return LEB_FREED;
501 }
502
503 /*
504 * We scan the entire LEB even though we only really need to scan up to
505 * (c->leb_size - lp->free).
506 */
507 sleb = ubifs_scan(c, lnum, 0, c->sbuf, 0);
508 if (IS_ERR(sleb))
509 return PTR_ERR(sleb);
510
511 ubifs_assert(!list_empty(&sleb->nodes));
512 snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list);
513
514 if (snod->type == UBIFS_IDX_NODE) {
515 struct ubifs_gced_idx_leb *idx_gc;
516
517 dbg_gc("indexing LEB %d (free %d, dirty %d)",
518 lnum, lp->free, lp->dirty);
519 list_for_each_entry(snod, &sleb->nodes, list) {
520 struct ubifs_idx_node *idx = snod->node;
521 int level = le16_to_cpu(idx->level);
522
523 ubifs_assert(snod->type == UBIFS_IDX_NODE);
524 key_read(c, ubifs_idx_key(c, idx), &snod->key);
525 err = ubifs_dirty_idx_node(c, &snod->key, level, lnum,
526 snod->offs);
527 if (err)
528 goto out;
529 }
530
531 idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);
532 if (!idx_gc) {
533 err = -ENOMEM;
534 goto out;
535 }
536
537 idx_gc->lnum = lnum;
538 idx_gc->unmap = 0;
539 list_add(&idx_gc->list, &c->idx_gc);
540
541 /*
542 * Don't release the LEB until after the next commit, because
543 * it may contain data which is needed for recovery. So
544 * although we freed this LEB, it will become usable only after
545 * the commit.
546 */
547 err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0,
548 LPROPS_INDEX, 1);
549 if (err)
550 goto out;
551 err = LEB_FREED_IDX;
552 } else {
553 dbg_gc("data LEB %d (free %d, dirty %d)",
554 lnum, lp->free, lp->dirty);
555
556 err = move_nodes(c, sleb);
557 if (err)
558 goto out_inc_seq;
559
560 err = gc_sync_wbufs(c);
561 if (err)
562 goto out_inc_seq;
563
564 err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, 0, 0);
565 if (err)
566 goto out_inc_seq;
567
568 /* Allow for races with TNC */
569 c->gced_lnum = lnum;
570 smp_wmb();
571 c->gc_seq += 1;
572 smp_wmb();
573
574 if (c->gc_lnum == -1) {
575 c->gc_lnum = lnum;
576 err = LEB_RETAINED;
577 } else {
578 err = ubifs_wbuf_sync_nolock(wbuf);
579 if (err)
580 goto out;
581
582 err = ubifs_leb_unmap(c, lnum);
583 if (err)
584 goto out;
585
586 err = LEB_FREED;
587 }
588 }
589
590out:
591 ubifs_scan_destroy(sleb);
592 return err;
593
594out_inc_seq:
595 /* We may have moved at least some nodes so allow for races with TNC */
596 c->gced_lnum = lnum;
597 smp_wmb();
598 c->gc_seq += 1;
599 smp_wmb();
600 goto out;
601}
602
603/**
604 * ubifs_garbage_collect - UBIFS garbage collector.
605 * @c: UBIFS file-system description object
606 * @anyway: do GC even if there are free LEBs
607 *
608 * This function does out-of-place garbage collection. The return codes are:
609 * o positive LEB number if the LEB has been freed and may be used;
610 * o %-EAGAIN if the caller has to run commit;
611 * o %-ENOSPC if GC failed to make any progress;
612 * o other negative error codes in case of other errors.
613 *
614 * Garbage collector writes data to the journal when GC'ing data LEBs, and just
615 * marking indexing nodes dirty when GC'ing indexing LEBs. Thus, at some point
616 * commit may be required. But commit cannot be run from inside GC, because the
617 * caller might be holding the commit lock, so %-EAGAIN is returned instead;
618 * And this error code means that the caller has to run commit, and re-run GC
619 * if there is still no free space.
620 *
621 * There are many reasons why this function may return %-EAGAIN:
622 * o the log is full and there is no space to write an LEB reference for
623 * @c->gc_lnum;
624 * o the journal is too large and exceeds size limitations;
625 * o GC moved indexing LEBs, but they can be used only after the commit;
626 * o the shrinker fails to find clean znodes to free and requests the commit;
627 * o etc.
628 *
629 * Note, if the file-system is close to be full, this function may return
630 * %-EAGAIN infinitely, so the caller has to limit amount of re-invocations of
631 * the function. E.g., this happens if the limits on the journal size are too
632 * tough and GC writes too much to the journal before an LEB is freed. This
633 * might also mean that the journal is too large, and the TNC becomes to big,
634 * so that the shrinker is constantly called, finds not clean znodes to free,
635 * and requests commit. Well, this may also happen if the journal is all right,
636 * but another kernel process consumes too much memory. Anyway, infinite
637 * %-EAGAIN may happen, but in some extreme/misconfiguration cases.
638 */
639int ubifs_garbage_collect(struct ubifs_info *c, int anyway)
640{
641 int i, err, ret, min_space = c->dead_wm;
642 struct ubifs_lprops lp;
643 struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf;
644
645 ubifs_assert_cmt_locked(c);
646 ubifs_assert(!c->ro_media && !c->ro_mount);
647
648 if (ubifs_gc_should_commit(c))
649 return -EAGAIN;
650
651 mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
652
653 if (c->ro_error) {
654 ret = -EROFS;
655 goto out_unlock;
656 }
657
658 /* We expect the write-buffer to be empty on entry */
659 ubifs_assert(!wbuf->used);
660
661 for (i = 0; ; i++) {
662 int space_before, space_after;
663
664 cond_resched();
665
666 /* Give the commit an opportunity to run */
667 if (ubifs_gc_should_commit(c)) {
668 ret = -EAGAIN;
669 break;
670 }
671
672 if (i > SOFT_LEBS_LIMIT && !list_empty(&c->idx_gc)) {
673 /*
674 * We've done enough iterations. Indexing LEBs were
675 * moved and will be available after the commit.
676 */
677 dbg_gc("soft limit, some index LEBs GC'ed, -EAGAIN");
678 ubifs_commit_required(c);
679 ret = -EAGAIN;
680 break;
681 }
682
683 if (i > HARD_LEBS_LIMIT) {
684 /*
685 * We've moved too many LEBs and have not made
686 * progress, give up.
687 */
688 dbg_gc("hard limit, -ENOSPC");
689 ret = -ENOSPC;
690 break;
691 }
692
693 /*
694 * Empty and freeable LEBs can turn up while we waited for
695 * the wbuf lock, or while we have been running GC. In that
696 * case, we should just return one of those instead of
697 * continuing to GC dirty LEBs. Hence we request
698 * 'ubifs_find_dirty_leb()' to return an empty LEB if it can.
699 */
700 ret = ubifs_find_dirty_leb(c, &lp, min_space, anyway ? 0 : 1);
701 if (ret) {
702 if (ret == -ENOSPC)
703 dbg_gc("no more dirty LEBs");
704 break;
705 }
706
707 dbg_gc("found LEB %d: free %d, dirty %d, sum %d (min. space %d)",
708 lp.lnum, lp.free, lp.dirty, lp.free + lp.dirty,
709 min_space);
710
711 space_before = c->leb_size - wbuf->offs - wbuf->used;
712 if (wbuf->lnum == -1)
713 space_before = 0;
714
715 ret = ubifs_garbage_collect_leb(c, &lp);
716 if (ret < 0) {
717 if (ret == -EAGAIN) {
718 /*
719 * This is not error, so we have to return the
720 * LEB to lprops. But if 'ubifs_return_leb()'
721 * fails, its failure code is propagated to the
722 * caller instead of the original '-EAGAIN'.
723 */
724 err = ubifs_return_leb(c, lp.lnum);
725 if (err)
726 ret = err;
727 break;
728 }
729 goto out;
730 }
731
732 if (ret == LEB_FREED) {
733 /* An LEB has been freed and is ready for use */
734 dbg_gc("LEB %d freed, return", lp.lnum);
735 ret = lp.lnum;
736 break;
737 }
738
739 if (ret == LEB_FREED_IDX) {
740 /*
741 * This was an indexing LEB and it cannot be
742 * immediately used. And instead of requesting the
743 * commit straight away, we try to garbage collect some
744 * more.
745 */
746 dbg_gc("indexing LEB %d freed, continue", lp.lnum);
747 continue;
748 }
749
750 ubifs_assert(ret == LEB_RETAINED);
751 space_after = c->leb_size - wbuf->offs - wbuf->used;
752 dbg_gc("LEB %d retained, freed %d bytes", lp.lnum,
753 space_after - space_before);
754
755 if (space_after > space_before) {
756 /* GC makes progress, keep working */
757 min_space >>= 1;
758 if (min_space < c->dead_wm)
759 min_space = c->dead_wm;
760 continue;
761 }
762
763 dbg_gc("did not make progress");
764
765 /*
766 * GC moved an LEB bud have not done any progress. This means
767 * that the previous GC head LEB contained too few free space
768 * and the LEB which was GC'ed contained only large nodes which
769 * did not fit that space.
770 *
771 * We can do 2 things:
772 * 1. pick another LEB in a hope it'll contain a small node
773 * which will fit the space we have at the end of current GC
774 * head LEB, but there is no guarantee, so we try this out
775 * unless we have already been working for too long;
776 * 2. request an LEB with more dirty space, which will force
777 * 'ubifs_find_dirty_leb()' to start scanning the lprops
778 * table, instead of just picking one from the heap
779 * (previously it already picked the dirtiest LEB).
780 */
781 if (i < SOFT_LEBS_LIMIT) {
782 dbg_gc("try again");
783 continue;
784 }
785
786 min_space <<= 1;
787 if (min_space > c->dark_wm)
788 min_space = c->dark_wm;
789 dbg_gc("set min. space to %d", min_space);
790 }
791
792 if (ret == -ENOSPC && !list_empty(&c->idx_gc)) {
793 dbg_gc("no space, some index LEBs GC'ed, -EAGAIN");
794 ubifs_commit_required(c);
795 ret = -EAGAIN;
796 }
797
798 err = ubifs_wbuf_sync_nolock(wbuf);
799 if (!err)
800 err = ubifs_leb_unmap(c, c->gc_lnum);
801 if (err) {
802 ret = err;
803 goto out;
804 }
805out_unlock:
806 mutex_unlock(&wbuf->io_mutex);
807 return ret;
808
809out:
810 ubifs_assert(ret < 0);
811 ubifs_assert(ret != -ENOSPC && ret != -EAGAIN);
812 ubifs_wbuf_sync_nolock(wbuf);
813 ubifs_ro_mode(c, ret);
814 mutex_unlock(&wbuf->io_mutex);
815 ubifs_return_leb(c, lp.lnum);
816 return ret;
817}
818
819/**
820 * ubifs_gc_start_commit - garbage collection at start of commit.
821 * @c: UBIFS file-system description object
822 *
823 * If a LEB has only dirty and free space, then we may safely unmap it and make
824 * it free. Note, we cannot do this with indexing LEBs because dirty space may
825 * correspond index nodes that are required for recovery. In that case, the
826 * LEB cannot be unmapped until after the next commit.
827 *
828 * This function returns %0 upon success and a negative error code upon failure.
829 */
830int ubifs_gc_start_commit(struct ubifs_info *c)
831{
832 struct ubifs_gced_idx_leb *idx_gc;
833 const struct ubifs_lprops *lp;
834 int err = 0, flags;
835
836 ubifs_get_lprops(c);
837
838 /*
839 * Unmap (non-index) freeable LEBs. Note that recovery requires that all
840 * wbufs are sync'd before this, which is done in 'do_commit()'.
841 */
842 while (1) {
843 lp = ubifs_fast_find_freeable(c);
844 if (IS_ERR(lp)) {
845 err = PTR_ERR(lp);
846 goto out;
847 }
848 if (!lp)
849 break;
850 ubifs_assert(!(lp->flags & LPROPS_TAKEN));
851 ubifs_assert(!(lp->flags & LPROPS_INDEX));
852 err = ubifs_leb_unmap(c, lp->lnum);
853 if (err)
854 goto out;
855 lp = ubifs_change_lp(c, lp, c->leb_size, 0, lp->flags, 0);
856 if (IS_ERR(lp)) {
857 err = PTR_ERR(lp);
858 goto out;
859 }
860 ubifs_assert(!(lp->flags & LPROPS_TAKEN));
861 ubifs_assert(!(lp->flags & LPROPS_INDEX));
862 }
863
864 /* Mark GC'd index LEBs OK to unmap after this commit finishes */
865 list_for_each_entry(idx_gc, &c->idx_gc, list)
866 idx_gc->unmap = 1;
867
868 /* Record index freeable LEBs for unmapping after commit */
869 while (1) {
870 lp = ubifs_fast_find_frdi_idx(c);
871 if (IS_ERR(lp)) {
872 err = PTR_ERR(lp);
873 goto out;
874 }
875 if (!lp)
876 break;
877 idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS);
878 if (!idx_gc) {
879 err = -ENOMEM;
880 goto out;
881 }
882 ubifs_assert(!(lp->flags & LPROPS_TAKEN));
883 ubifs_assert(lp->flags & LPROPS_INDEX);
884 /* Don't release the LEB until after the next commit */
885 flags = (lp->flags | LPROPS_TAKEN) ^ LPROPS_INDEX;
886 lp = ubifs_change_lp(c, lp, c->leb_size, 0, flags, 1);
887 if (IS_ERR(lp)) {
888 err = PTR_ERR(lp);
889 kfree(idx_gc);
890 goto out;
891 }
892 ubifs_assert(lp->flags & LPROPS_TAKEN);
893 ubifs_assert(!(lp->flags & LPROPS_INDEX));
894 idx_gc->lnum = lp->lnum;
895 idx_gc->unmap = 1;
896 list_add(&idx_gc->list, &c->idx_gc);
897 }
898out:
899 ubifs_release_lprops(c);
900 return err;
901}
902
903/**
904 * ubifs_gc_end_commit - garbage collection at end of commit.
905 * @c: UBIFS file-system description object
906 *
907 * This function completes out-of-place garbage collection of index LEBs.
908 */
909int ubifs_gc_end_commit(struct ubifs_info *c)
910{
911 struct ubifs_gced_idx_leb *idx_gc, *tmp;
912 struct ubifs_wbuf *wbuf;
913 int err = 0;
914
915 wbuf = &c->jheads[GCHD].wbuf;
916 mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead);
917 list_for_each_entry_safe(idx_gc, tmp, &c->idx_gc, list)
918 if (idx_gc->unmap) {
919 dbg_gc("LEB %d", idx_gc->lnum);
920 err = ubifs_leb_unmap(c, idx_gc->lnum);
921 if (err)
922 goto out;
923 err = ubifs_change_one_lp(c, idx_gc->lnum, LPROPS_NC,
924 LPROPS_NC, 0, LPROPS_TAKEN, -1);
925 if (err)
926 goto out;
927 list_del(&idx_gc->list);
928 kfree(idx_gc);
929 }
930out:
931 mutex_unlock(&wbuf->io_mutex);
932 return err;
933}
934#endif
935/**
936 * ubifs_destroy_idx_gc - destroy idx_gc list.
937 * @c: UBIFS file-system description object
938 *
939 * This function destroys the @c->idx_gc list. It is called when unmounting
940 * so locks are not needed. Returns zero in case of success and a negative
941 * error code in case of failure.
942 */
943void ubifs_destroy_idx_gc(struct ubifs_info *c)
944{
945 while (!list_empty(&c->idx_gc)) {
946 struct ubifs_gced_idx_leb *idx_gc;
947
948 idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb,
949 list);
950 c->idx_gc_cnt -= 1;
951 list_del(&idx_gc->list);
952 kfree(idx_gc);
953 }
954}
955#ifndef __UBOOT__
956/**
957 * ubifs_get_idx_gc_leb - get a LEB from GC'd index LEB list.
958 * @c: UBIFS file-system description object
959 *
960 * Called during start commit so locks are not needed.
961 */
962int ubifs_get_idx_gc_leb(struct ubifs_info *c)
963{
964 struct ubifs_gced_idx_leb *idx_gc;
965 int lnum;
966
967 if (list_empty(&c->idx_gc))
968 return -ENOSPC;
969 idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, list);
970 lnum = idx_gc->lnum;
971 /* c->idx_gc_cnt is updated by the caller when lprops are updated */
972 list_del(&idx_gc->list);
973 kfree(idx_gc);
974 return lnum;
975}
976#endif