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1e51764a AB |
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: Adrian Hunter | |
20 | * Artem Bityutskiy (Битюцкий Артём) | |
21 | */ | |
22 | ||
23 | /* | |
24 | * This file implements garbage collection. The procedure for garbage collection | |
25 | * is different depending on whether a LEB as an index LEB (contains index | |
26 | * nodes) or not. For non-index LEBs, garbage collection finds a LEB which | |
27 | * contains a lot of dirty space (obsolete nodes), and copies the non-obsolete | |
28 | * nodes to the journal, at which point the garbage-collected LEB is free to be | |
29 | * reused. For index LEBs, garbage collection marks the non-obsolete index nodes | |
30 | * dirty in the TNC, and after the next commit, the garbage-collected LEB is | |
31 | * to be reused. Garbage collection will cause the number of dirty index nodes | |
32 | * to grow, however sufficient space is reserved for the index to ensure the | |
33 | * commit will never run out of space. | |
7078202e AB |
34 | * |
35 | * Notes about dead watermark. At current UBIFS implementation we assume that | |
36 | * LEBs which have less than @c->dead_wm bytes of free + dirty space are full | |
37 | * and not worth garbage-collecting. The dead watermark is one min. I/O unit | |
38 | * size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS | |
39 | * Garbage Collector has to synchronize the GC head's write buffer before | |
40 | * returning, so this is about wasting one min. I/O unit. However, UBIFS GC can | |
41 | * actually reclaim even very small pieces of dirty space by garbage collecting | |
42 | * enough dirty LEBs, but we do not bother doing this at this implementation. | |
43 | * | |
44 | * Notes about dark watermark. The results of GC work depends on how big are | |
45 | * the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed, | |
46 | * if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would | |
47 | * have to waste large pieces of free space at the end of LEB B, because nodes | |
48 | * from LEB A would not fit. And the worst situation is when all nodes are of | |
49 | * maximum size. So dark watermark is the amount of free + dirty space in LEB | |
f10770f5 | 50 | * which are guaranteed to be reclaimable. If LEB has less space, the GC might |
7078202e AB |
51 | * be unable to reclaim it. So, LEBs with free + dirty greater than dark |
52 | * watermark are "good" LEBs from GC's point of few. The other LEBs are not so | |
53 | * good, and GC takes extra care when moving them. | |
1e51764a AB |
54 | */ |
55 | ||
56 | #include <linux/pagemap.h> | |
57 | #include "ubifs.h" | |
58 | ||
1e51764a | 59 | /* |
025dfdaf | 60 | * GC may need to move more than one LEB to make progress. The below constants |
1e51764a AB |
61 | * define "soft" and "hard" limits on the number of LEBs the garbage collector |
62 | * may move. | |
63 | */ | |
64 | #define SOFT_LEBS_LIMIT 4 | |
65 | #define HARD_LEBS_LIMIT 32 | |
66 | ||
67 | /** | |
68 | * switch_gc_head - switch the garbage collection journal head. | |
69 | * @c: UBIFS file-system description object | |
70 | * @buf: buffer to write | |
71 | * @len: length of the buffer to write | |
72 | * @lnum: LEB number written is returned here | |
73 | * @offs: offset written is returned here | |
74 | * | |
75 | * This function switch the GC head to the next LEB which is reserved in | |
76 | * @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required, | |
77 | * and other negative error code in case of failures. | |
78 | */ | |
79 | static int switch_gc_head(struct ubifs_info *c) | |
80 | { | |
81 | int err, gc_lnum = c->gc_lnum; | |
82 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; | |
83 | ||
84 | ubifs_assert(gc_lnum != -1); | |
85 | dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)", | |
86 | wbuf->lnum, wbuf->offs + wbuf->used, gc_lnum, | |
87 | c->leb_size - wbuf->offs - wbuf->used); | |
88 | ||
89 | err = ubifs_wbuf_sync_nolock(wbuf); | |
90 | if (err) | |
91 | return err; | |
92 | ||
93 | /* | |
94 | * The GC write-buffer was synchronized, we may safely unmap | |
95 | * 'c->gc_lnum'. | |
96 | */ | |
97 | err = ubifs_leb_unmap(c, gc_lnum); | |
98 | if (err) | |
99 | return err; | |
100 | ||
101 | err = ubifs_add_bud_to_log(c, GCHD, gc_lnum, 0); | |
102 | if (err) | |
103 | return err; | |
104 | ||
105 | c->gc_lnum = -1; | |
106 | err = ubifs_wbuf_seek_nolock(wbuf, gc_lnum, 0, UBI_LONGTERM); | |
107 | return err; | |
108 | } | |
109 | ||
46773be4 | 110 | /** |
f10770f5 AB |
111 | * list_sort - sort a list. |
112 | * @priv: private data, passed to @cmp | |
113 | * @head: the list to sort | |
114 | * @cmp: the elements comparison function | |
46773be4 | 115 | * |
f10770f5 AB |
116 | * This function has been implemented by Mark J Roberts <mjr@znex.org>. It |
117 | * implements "merge sort" which has O(nlog(n)) complexity. The list is sorted | |
118 | * in ascending order. | |
119 | * | |
120 | * The comparison function @cmp is supposed to return a negative value if @a is | |
121 | * than @b, and a positive value if @a is greater than @b. If @a and @b are | |
122 | * equivalent, then it does not matter what this function returns. | |
46773be4 | 123 | */ |
f10770f5 AB |
124 | static void list_sort(void *priv, struct list_head *head, |
125 | int (*cmp)(void *priv, struct list_head *a, | |
126 | struct list_head *b)) | |
46773be4 | 127 | { |
f10770f5 AB |
128 | struct list_head *p, *q, *e, *list, *tail, *oldhead; |
129 | int insize, nmerges, psize, qsize, i; | |
130 | ||
131 | if (list_empty(head)) | |
132 | return; | |
133 | ||
134 | list = head->next; | |
135 | list_del(head); | |
136 | insize = 1; | |
137 | for (;;) { | |
138 | p = oldhead = list; | |
139 | list = tail = NULL; | |
140 | nmerges = 0; | |
141 | ||
142 | while (p) { | |
143 | nmerges++; | |
144 | q = p; | |
145 | psize = 0; | |
146 | for (i = 0; i < insize; i++) { | |
147 | psize++; | |
148 | q = q->next == oldhead ? NULL : q->next; | |
149 | if (!q) | |
150 | break; | |
151 | } | |
46773be4 | 152 | |
f10770f5 AB |
153 | qsize = insize; |
154 | while (psize > 0 || (qsize > 0 && q)) { | |
155 | if (!psize) { | |
156 | e = q; | |
157 | q = q->next; | |
158 | qsize--; | |
159 | if (q == oldhead) | |
160 | q = NULL; | |
161 | } else if (!qsize || !q) { | |
162 | e = p; | |
163 | p = p->next; | |
164 | psize--; | |
165 | if (p == oldhead) | |
166 | p = NULL; | |
167 | } else if (cmp(priv, p, q) <= 0) { | |
168 | e = p; | |
169 | p = p->next; | |
170 | psize--; | |
171 | if (p == oldhead) | |
172 | p = NULL; | |
173 | } else { | |
174 | e = q; | |
175 | q = q->next; | |
176 | qsize--; | |
177 | if (q == oldhead) | |
178 | q = NULL; | |
179 | } | |
180 | if (tail) | |
181 | tail->next = e; | |
182 | else | |
183 | list = e; | |
184 | e->prev = tail; | |
185 | tail = e; | |
186 | } | |
187 | p = q; | |
188 | } | |
189 | ||
190 | tail->next = list; | |
191 | list->prev = tail; | |
192 | ||
193 | if (nmerges <= 1) | |
46773be4 | 194 | break; |
f10770f5 AB |
195 | |
196 | insize *= 2; | |
46773be4 | 197 | } |
f10770f5 AB |
198 | |
199 | head->next = list; | |
200 | head->prev = list->prev; | |
201 | list->prev->next = head; | |
202 | list->prev = head; | |
46773be4 AH |
203 | } |
204 | ||
1e51764a | 205 | /** |
f10770f5 AB |
206 | * data_nodes_cmp - compare 2 data nodes. |
207 | * @priv: UBIFS file-system description object | |
208 | * @a: first data node | |
209 | * @a: second data node | |
210 | * | |
211 | * This function compares data nodes @a and @b. Returns %1 if @a has greater | |
212 | * inode or block number, and %-1 otherwise. | |
213 | */ | |
214 | int data_nodes_cmp(void *priv, struct list_head *a, struct list_head *b) | |
215 | { | |
216 | ino_t inuma, inumb; | |
217 | struct ubifs_info *c = priv; | |
218 | struct ubifs_scan_node *sa, *sb; | |
219 | ||
220 | cond_resched(); | |
221 | sa = list_entry(a, struct ubifs_scan_node, list); | |
222 | sb = list_entry(b, struct ubifs_scan_node, list); | |
223 | ubifs_assert(key_type(c, &sa->key) == UBIFS_DATA_KEY); | |
224 | ubifs_assert(key_type(c, &sb->key) == UBIFS_DATA_KEY); | |
225 | ||
226 | inuma = key_inum(c, &sa->key); | |
227 | inumb = key_inum(c, &sb->key); | |
228 | ||
229 | if (inuma == inumb) { | |
230 | unsigned int blka = key_block(c, &sa->key); | |
231 | unsigned int blkb = key_block(c, &sb->key); | |
232 | ||
233 | if (blka <= blkb) | |
234 | return -1; | |
235 | } else if (inuma <= inumb) | |
236 | return -1; | |
237 | ||
238 | return 1; | |
239 | } | |
240 | ||
241 | /* | |
242 | * nondata_nodes_cmp - compare 2 non-data nodes. | |
243 | * @priv: UBIFS file-system description object | |
244 | * @a: first node | |
245 | * @a: second node | |
246 | * | |
247 | * This function compares nodes @a and @b. It makes sure that inode nodes go | |
248 | * first and sorted by length in descending order. Directory entry nodes go | |
249 | * after inode nodes and are sorted in ascending hash valuer order. | |
250 | */ | |
251 | int nondata_nodes_cmp(void *priv, struct list_head *a, struct list_head *b) | |
252 | { | |
253 | int typea, typeb; | |
254 | ino_t inuma, inumb; | |
255 | struct ubifs_info *c = priv; | |
256 | struct ubifs_scan_node *sa, *sb; | |
257 | ||
258 | cond_resched(); | |
259 | sa = list_entry(a, struct ubifs_scan_node, list); | |
260 | sb = list_entry(b, struct ubifs_scan_node, list); | |
261 | typea = key_type(c, &sa->key); | |
262 | typeb = key_type(c, &sb->key); | |
263 | ubifs_assert(typea != UBIFS_DATA_KEY && typeb != UBIFS_DATA_KEY); | |
264 | ||
265 | /* Inodes go before directory entries */ | |
266 | if (typea == UBIFS_INO_KEY) { | |
267 | if (typeb == UBIFS_INO_KEY) | |
268 | return sb->len - sa->len; | |
269 | return -1; | |
270 | } | |
271 | if (typeb == UBIFS_INO_KEY) | |
272 | return 1; | |
273 | ||
274 | ubifs_assert(typea == UBIFS_DENT_KEY && typeb == UBIFS_DENT_KEY); | |
275 | inuma = key_inum(c, &sa->key); | |
276 | inumb = key_inum(c, &sb->key); | |
277 | ||
278 | if (inuma == inumb) { | |
279 | uint32_t hasha = key_hash(c, &sa->key); | |
280 | uint32_t hashb = key_hash(c, &sb->key); | |
281 | ||
282 | if (hasha <= hashb) | |
283 | return -1; | |
284 | } else if (inuma <= inumb) | |
285 | return -1; | |
286 | ||
287 | return 1; | |
288 | } | |
289 | ||
290 | /** | |
291 | * sort_nodes - sort nodes for GC. | |
1e51764a | 292 | * @c: UBIFS file-system description object |
f10770f5 AB |
293 | * @sleb: describes nodes to sort and contains the result on exit |
294 | * @nondata: contains non-data nodes on exit | |
295 | * @min: minimum node size is returned here | |
1e51764a | 296 | * |
f10770f5 AB |
297 | * This function sorts the list of inodes to garbage collect. First of all, it |
298 | * kills obsolete nodes and separates data and non-data nodes to the | |
299 | * @sleb->nodes and @nondata lists correspondingly. | |
1e51764a | 300 | * |
f10770f5 AB |
301 | * Data nodes are then sorted in block number order - this is important for |
302 | * bulk-read; data nodes with lower inode number go before data nodes with | |
303 | * higher inode number, and data nodes with lower block number go before data | |
304 | * nodes with higher block number; | |
1e51764a | 305 | * |
f10770f5 AB |
306 | * Non-data nodes are sorted as follows. |
307 | * o First go inode nodes - they are sorted in descending length order. | |
308 | * o Then go directory entry nodes - they are sorted in hash order, which | |
309 | * should supposedly optimize 'readdir()'. Direntry nodes with lower parent | |
310 | * inode number go before direntry nodes with higher parent inode number, | |
311 | * and direntry nodes with lower name hash values go before direntry nodes | |
312 | * with higher name hash values. | |
313 | * | |
314 | * This function returns zero in case of success and a negative error code in | |
315 | * case of failure. | |
1e51764a | 316 | */ |
f10770f5 AB |
317 | static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb, |
318 | struct list_head *nondata, int *min) | |
1e51764a AB |
319 | { |
320 | struct ubifs_scan_node *snod, *tmp; | |
1e51764a | 321 | |
f10770f5 | 322 | *min = INT_MAX; |
1e51764a | 323 | |
f10770f5 AB |
324 | /* Separate data nodes and non-data nodes */ |
325 | list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { | |
326 | int err; | |
1e51764a AB |
327 | |
328 | ubifs_assert(snod->type != UBIFS_IDX_NODE); | |
329 | ubifs_assert(snod->type != UBIFS_REF_NODE); | |
330 | ubifs_assert(snod->type != UBIFS_CS_NODE); | |
331 | ||
332 | err = ubifs_tnc_has_node(c, &snod->key, 0, sleb->lnum, | |
333 | snod->offs, 0); | |
334 | if (err < 0) | |
f10770f5 | 335 | return err; |
1e51764a | 336 | |
1e51764a AB |
337 | if (!err) { |
338 | /* The node is obsolete, remove it from the list */ | |
f10770f5 | 339 | list_del(&snod->list); |
1e51764a AB |
340 | kfree(snod); |
341 | continue; | |
342 | } | |
343 | ||
f10770f5 AB |
344 | if (snod->len < *min) |
345 | *min = snod->len; | |
346 | ||
347 | if (key_type(c, &snod->key) != UBIFS_DATA_KEY) | |
348 | list_move_tail(&snod->list, nondata); | |
1e51764a AB |
349 | } |
350 | ||
f10770f5 AB |
351 | /* Sort data and non-data nodes */ |
352 | list_sort(c, &sleb->nodes, &data_nodes_cmp); | |
353 | list_sort(c, nondata, &nondata_nodes_cmp); | |
354 | return 0; | |
355 | } | |
356 | ||
357 | /** | |
358 | * move_node - move a node. | |
359 | * @c: UBIFS file-system description object | |
360 | * @sleb: describes the LEB to move nodes from | |
361 | * @snod: the mode to move | |
362 | * @wbuf: write-buffer to move node to | |
363 | * | |
364 | * This function moves node @snod to @wbuf, changes TNC correspondingly, and | |
365 | * destroys @snod. Returns zero in case of success and a negative error code in | |
366 | * case of failure. | |
367 | */ | |
368 | static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb, | |
369 | struct ubifs_scan_node *snod, struct ubifs_wbuf *wbuf) | |
370 | { | |
371 | int err, new_lnum = wbuf->lnum, new_offs = wbuf->offs + wbuf->used; | |
372 | ||
373 | cond_resched(); | |
374 | err = ubifs_wbuf_write_nolock(wbuf, snod->node, snod->len); | |
375 | if (err) | |
376 | return err; | |
377 | ||
378 | err = ubifs_tnc_replace(c, &snod->key, sleb->lnum, | |
379 | snod->offs, new_lnum, new_offs, | |
380 | snod->len); | |
381 | list_del(&snod->list); | |
382 | kfree(snod); | |
383 | return err; | |
384 | } | |
385 | ||
386 | /** | |
387 | * move_nodes - move nodes. | |
388 | * @c: UBIFS file-system description object | |
389 | * @sleb: describes the LEB to move nodes from | |
390 | * | |
391 | * This function moves valid nodes from data LEB described by @sleb to the GC | |
392 | * journal head. This function returns zero in case of success, %-EAGAIN if | |
393 | * commit is required, and other negative error codes in case of other | |
394 | * failures. | |
395 | */ | |
396 | static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb) | |
397 | { | |
398 | int err, min; | |
399 | LIST_HEAD(nondata); | |
400 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; | |
1e51764a AB |
401 | |
402 | if (wbuf->lnum == -1) { | |
403 | /* | |
404 | * The GC journal head is not set, because it is the first GC | |
405 | * invocation since mount. | |
406 | */ | |
407 | err = switch_gc_head(c); | |
408 | if (err) | |
f10770f5 | 409 | return err; |
1e51764a AB |
410 | } |
411 | ||
f10770f5 AB |
412 | err = sort_nodes(c, sleb, &nondata, &min); |
413 | if (err) | |
414 | goto out; | |
415 | ||
1e51764a AB |
416 | /* Write nodes to their new location. Use the first-fit strategy */ |
417 | while (1) { | |
f10770f5 AB |
418 | int avail; |
419 | struct ubifs_scan_node *snod, *tmp; | |
420 | ||
421 | /* Move data nodes */ | |
422 | list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { | |
423 | avail = c->leb_size - wbuf->offs - wbuf->used; | |
424 | if (snod->len > avail) | |
425 | /* | |
426 | * Do not skip data nodes in order to optimize | |
427 | * bulk-read. | |
428 | */ | |
429 | break; | |
430 | ||
431 | err = move_node(c, sleb, snod, wbuf); | |
432 | if (err) | |
433 | goto out; | |
434 | } | |
1e51764a | 435 | |
f10770f5 AB |
436 | /* Move non-data nodes */ |
437 | list_for_each_entry_safe(snod, tmp, &nondata, list) { | |
438 | avail = c->leb_size - wbuf->offs - wbuf->used; | |
1e51764a AB |
439 | if (avail < min) |
440 | break; | |
441 | ||
f10770f5 AB |
442 | if (snod->len > avail) { |
443 | /* | |
444 | * Keep going only if this is an inode with | |
445 | * some data. Otherwise stop and switch the GC | |
446 | * head. IOW, we assume that data-less inode | |
447 | * nodes and direntry nodes are roughly of the | |
448 | * same size. | |
449 | */ | |
450 | if (key_type(c, &snod->key) == UBIFS_DENT_KEY || | |
451 | snod->len == UBIFS_INO_NODE_SZ) | |
452 | break; | |
1e51764a | 453 | continue; |
f10770f5 | 454 | } |
1e51764a | 455 | |
f10770f5 | 456 | err = move_node(c, sleb, snod, wbuf); |
1e51764a AB |
457 | if (err) |
458 | goto out; | |
1e51764a AB |
459 | } |
460 | ||
f10770f5 | 461 | if (list_empty(&sleb->nodes) && list_empty(&nondata)) |
1e51764a AB |
462 | break; |
463 | ||
464 | /* | |
465 | * Waste the rest of the space in the LEB and switch to the | |
466 | * next LEB. | |
467 | */ | |
468 | err = switch_gc_head(c); | |
469 | if (err) | |
470 | goto out; | |
471 | } | |
472 | ||
473 | return 0; | |
474 | ||
475 | out: | |
f10770f5 | 476 | list_splice_tail(&nondata, &sleb->nodes); |
1e51764a AB |
477 | return err; |
478 | } | |
479 | ||
480 | /** | |
481 | * gc_sync_wbufs - sync write-buffers for GC. | |
482 | * @c: UBIFS file-system description object | |
483 | * | |
484 | * We must guarantee that obsoleting nodes are on flash. Unfortunately they may | |
485 | * be in a write-buffer instead. That is, a node could be written to a | |
486 | * write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is | |
487 | * erased before the write-buffer is sync'd and then there is an unclean | |
488 | * unmount, then an existing node is lost. To avoid this, we sync all | |
489 | * write-buffers. | |
490 | * | |
491 | * This function returns %0 on success or a negative error code on failure. | |
492 | */ | |
493 | static int gc_sync_wbufs(struct ubifs_info *c) | |
494 | { | |
495 | int err, i; | |
496 | ||
497 | for (i = 0; i < c->jhead_cnt; i++) { | |
498 | if (i == GCHD) | |
499 | continue; | |
500 | err = ubifs_wbuf_sync(&c->jheads[i].wbuf); | |
501 | if (err) | |
502 | return err; | |
503 | } | |
504 | return 0; | |
505 | } | |
506 | ||
507 | /** | |
508 | * ubifs_garbage_collect_leb - garbage-collect a logical eraseblock. | |
509 | * @c: UBIFS file-system description object | |
510 | * @lp: describes the LEB to garbage collect | |
511 | * | |
512 | * This function garbage-collects an LEB and returns one of the @LEB_FREED, | |
513 | * @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is | |
514 | * required, and other negative error codes in case of failures. | |
515 | */ | |
516 | int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp) | |
517 | { | |
518 | struct ubifs_scan_leb *sleb; | |
519 | struct ubifs_scan_node *snod; | |
520 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; | |
521 | int err = 0, lnum = lp->lnum; | |
522 | ||
523 | ubifs_assert(c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 || | |
524 | c->need_recovery); | |
525 | ubifs_assert(c->gc_lnum != lnum); | |
526 | ubifs_assert(wbuf->lnum != lnum); | |
527 | ||
528 | /* | |
529 | * We scan the entire LEB even though we only really need to scan up to | |
530 | * (c->leb_size - lp->free). | |
531 | */ | |
532 | sleb = ubifs_scan(c, lnum, 0, c->sbuf); | |
533 | if (IS_ERR(sleb)) | |
534 | return PTR_ERR(sleb); | |
535 | ||
536 | ubifs_assert(!list_empty(&sleb->nodes)); | |
537 | snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list); | |
538 | ||
539 | if (snod->type == UBIFS_IDX_NODE) { | |
540 | struct ubifs_gced_idx_leb *idx_gc; | |
541 | ||
542 | dbg_gc("indexing LEB %d (free %d, dirty %d)", | |
543 | lnum, lp->free, lp->dirty); | |
544 | list_for_each_entry(snod, &sleb->nodes, list) { | |
545 | struct ubifs_idx_node *idx = snod->node; | |
546 | int level = le16_to_cpu(idx->level); | |
547 | ||
548 | ubifs_assert(snod->type == UBIFS_IDX_NODE); | |
549 | key_read(c, ubifs_idx_key(c, idx), &snod->key); | |
550 | err = ubifs_dirty_idx_node(c, &snod->key, level, lnum, | |
551 | snod->offs); | |
552 | if (err) | |
553 | goto out; | |
554 | } | |
555 | ||
556 | idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); | |
557 | if (!idx_gc) { | |
558 | err = -ENOMEM; | |
559 | goto out; | |
560 | } | |
561 | ||
562 | idx_gc->lnum = lnum; | |
563 | idx_gc->unmap = 0; | |
564 | list_add(&idx_gc->list, &c->idx_gc); | |
565 | ||
566 | /* | |
567 | * Don't release the LEB until after the next commit, because | |
227c75c9 | 568 | * it may contain data which is needed for recovery. So |
1e51764a AB |
569 | * although we freed this LEB, it will become usable only after |
570 | * the commit. | |
571 | */ | |
572 | err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, | |
573 | LPROPS_INDEX, 1); | |
574 | if (err) | |
575 | goto out; | |
576 | err = LEB_FREED_IDX; | |
577 | } else { | |
578 | dbg_gc("data LEB %d (free %d, dirty %d)", | |
579 | lnum, lp->free, lp->dirty); | |
580 | ||
581 | err = move_nodes(c, sleb); | |
582 | if (err) | |
6dcfac4f | 583 | goto out_inc_seq; |
1e51764a AB |
584 | |
585 | err = gc_sync_wbufs(c); | |
586 | if (err) | |
6dcfac4f | 587 | goto out_inc_seq; |
1e51764a AB |
588 | |
589 | err = ubifs_change_one_lp(c, lnum, c->leb_size, 0, 0, 0, 0); | |
590 | if (err) | |
6dcfac4f | 591 | goto out_inc_seq; |
1e51764a | 592 | |
601c0bc4 AH |
593 | /* Allow for races with TNC */ |
594 | c->gced_lnum = lnum; | |
595 | smp_wmb(); | |
596 | c->gc_seq += 1; | |
597 | smp_wmb(); | |
598 | ||
1e51764a AB |
599 | if (c->gc_lnum == -1) { |
600 | c->gc_lnum = lnum; | |
601 | err = LEB_RETAINED; | |
602 | } else { | |
603 | err = ubifs_wbuf_sync_nolock(wbuf); | |
604 | if (err) | |
605 | goto out; | |
606 | ||
607 | err = ubifs_leb_unmap(c, lnum); | |
608 | if (err) | |
609 | goto out; | |
610 | ||
611 | err = LEB_FREED; | |
612 | } | |
613 | } | |
614 | ||
615 | out: | |
616 | ubifs_scan_destroy(sleb); | |
617 | return err; | |
6dcfac4f AH |
618 | |
619 | out_inc_seq: | |
620 | /* We may have moved at least some nodes so allow for races with TNC */ | |
621 | c->gced_lnum = lnum; | |
622 | smp_wmb(); | |
623 | c->gc_seq += 1; | |
624 | smp_wmb(); | |
625 | goto out; | |
1e51764a AB |
626 | } |
627 | ||
628 | /** | |
629 | * ubifs_garbage_collect - UBIFS garbage collector. | |
630 | * @c: UBIFS file-system description object | |
631 | * @anyway: do GC even if there are free LEBs | |
632 | * | |
633 | * This function does out-of-place garbage collection. The return codes are: | |
634 | * o positive LEB number if the LEB has been freed and may be used; | |
635 | * o %-EAGAIN if the caller has to run commit; | |
636 | * o %-ENOSPC if GC failed to make any progress; | |
637 | * o other negative error codes in case of other errors. | |
638 | * | |
639 | * Garbage collector writes data to the journal when GC'ing data LEBs, and just | |
640 | * marking indexing nodes dirty when GC'ing indexing LEBs. Thus, at some point | |
641 | * commit may be required. But commit cannot be run from inside GC, because the | |
642 | * caller might be holding the commit lock, so %-EAGAIN is returned instead; | |
643 | * And this error code means that the caller has to run commit, and re-run GC | |
644 | * if there is still no free space. | |
645 | * | |
646 | * There are many reasons why this function may return %-EAGAIN: | |
647 | * o the log is full and there is no space to write an LEB reference for | |
648 | * @c->gc_lnum; | |
649 | * o the journal is too large and exceeds size limitations; | |
650 | * o GC moved indexing LEBs, but they can be used only after the commit; | |
651 | * o the shrinker fails to find clean znodes to free and requests the commit; | |
652 | * o etc. | |
653 | * | |
654 | * Note, if the file-system is close to be full, this function may return | |
655 | * %-EAGAIN infinitely, so the caller has to limit amount of re-invocations of | |
656 | * the function. E.g., this happens if the limits on the journal size are too | |
657 | * tough and GC writes too much to the journal before an LEB is freed. This | |
658 | * might also mean that the journal is too large, and the TNC becomes to big, | |
659 | * so that the shrinker is constantly called, finds not clean znodes to free, | |
660 | * and requests commit. Well, this may also happen if the journal is all right, | |
661 | * but another kernel process consumes too much memory. Anyway, infinite | |
662 | * %-EAGAIN may happen, but in some extreme/misconfiguration cases. | |
663 | */ | |
664 | int ubifs_garbage_collect(struct ubifs_info *c, int anyway) | |
665 | { | |
666 | int i, err, ret, min_space = c->dead_wm; | |
667 | struct ubifs_lprops lp; | |
668 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; | |
669 | ||
670 | ubifs_assert_cmt_locked(c); | |
671 | ||
672 | if (ubifs_gc_should_commit(c)) | |
673 | return -EAGAIN; | |
674 | ||
675 | mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead); | |
676 | ||
677 | if (c->ro_media) { | |
678 | ret = -EROFS; | |
679 | goto out_unlock; | |
680 | } | |
681 | ||
682 | /* We expect the write-buffer to be empty on entry */ | |
683 | ubifs_assert(!wbuf->used); | |
684 | ||
685 | for (i = 0; ; i++) { | |
686 | int space_before = c->leb_size - wbuf->offs - wbuf->used; | |
687 | int space_after; | |
688 | ||
689 | cond_resched(); | |
690 | ||
691 | /* Give the commit an opportunity to run */ | |
692 | if (ubifs_gc_should_commit(c)) { | |
693 | ret = -EAGAIN; | |
694 | break; | |
695 | } | |
696 | ||
697 | if (i > SOFT_LEBS_LIMIT && !list_empty(&c->idx_gc)) { | |
698 | /* | |
699 | * We've done enough iterations. Indexing LEBs were | |
700 | * moved and will be available after the commit. | |
701 | */ | |
702 | dbg_gc("soft limit, some index LEBs GC'ed, -EAGAIN"); | |
703 | ubifs_commit_required(c); | |
704 | ret = -EAGAIN; | |
705 | break; | |
706 | } | |
707 | ||
708 | if (i > HARD_LEBS_LIMIT) { | |
709 | /* | |
710 | * We've moved too many LEBs and have not made | |
711 | * progress, give up. | |
712 | */ | |
713 | dbg_gc("hard limit, -ENOSPC"); | |
714 | ret = -ENOSPC; | |
715 | break; | |
716 | } | |
717 | ||
718 | /* | |
719 | * Empty and freeable LEBs can turn up while we waited for | |
720 | * the wbuf lock, or while we have been running GC. In that | |
721 | * case, we should just return one of those instead of | |
722 | * continuing to GC dirty LEBs. Hence we request | |
723 | * 'ubifs_find_dirty_leb()' to return an empty LEB if it can. | |
724 | */ | |
725 | ret = ubifs_find_dirty_leb(c, &lp, min_space, anyway ? 0 : 1); | |
726 | if (ret) { | |
727 | if (ret == -ENOSPC) | |
728 | dbg_gc("no more dirty LEBs"); | |
729 | break; | |
730 | } | |
731 | ||
732 | dbg_gc("found LEB %d: free %d, dirty %d, sum %d " | |
733 | "(min. space %d)", lp.lnum, lp.free, lp.dirty, | |
734 | lp.free + lp.dirty, min_space); | |
735 | ||
736 | if (lp.free + lp.dirty == c->leb_size) { | |
737 | /* An empty LEB was returned */ | |
738 | dbg_gc("LEB %d is free, return it", lp.lnum); | |
739 | /* | |
740 | * ubifs_find_dirty_leb() doesn't return freeable index | |
741 | * LEBs. | |
742 | */ | |
743 | ubifs_assert(!(lp.flags & LPROPS_INDEX)); | |
744 | if (lp.free != c->leb_size) { | |
745 | /* | |
746 | * Write buffers must be sync'd before | |
747 | * unmapping freeable LEBs, because one of them | |
748 | * may contain data which obsoletes something | |
749 | * in 'lp.pnum'. | |
750 | */ | |
751 | ret = gc_sync_wbufs(c); | |
752 | if (ret) | |
753 | goto out; | |
754 | ret = ubifs_change_one_lp(c, lp.lnum, | |
755 | c->leb_size, 0, 0, 0, | |
756 | 0); | |
757 | if (ret) | |
758 | goto out; | |
759 | } | |
760 | ret = ubifs_leb_unmap(c, lp.lnum); | |
761 | if (ret) | |
762 | goto out; | |
763 | ret = lp.lnum; | |
764 | break; | |
765 | } | |
766 | ||
767 | space_before = c->leb_size - wbuf->offs - wbuf->used; | |
768 | if (wbuf->lnum == -1) | |
769 | space_before = 0; | |
770 | ||
771 | ret = ubifs_garbage_collect_leb(c, &lp); | |
772 | if (ret < 0) { | |
773 | if (ret == -EAGAIN || ret == -ENOSPC) { | |
774 | /* | |
775 | * These codes are not errors, so we have to | |
776 | * return the LEB to lprops. But if the | |
777 | * 'ubifs_return_leb()' function fails, its | |
778 | * failure code is propagated to the caller | |
779 | * instead of the original '-EAGAIN' or | |
780 | * '-ENOSPC'. | |
781 | */ | |
782 | err = ubifs_return_leb(c, lp.lnum); | |
783 | if (err) | |
784 | ret = err; | |
785 | break; | |
786 | } | |
787 | goto out; | |
788 | } | |
789 | ||
790 | if (ret == LEB_FREED) { | |
791 | /* An LEB has been freed and is ready for use */ | |
792 | dbg_gc("LEB %d freed, return", lp.lnum); | |
793 | ret = lp.lnum; | |
794 | break; | |
795 | } | |
796 | ||
797 | if (ret == LEB_FREED_IDX) { | |
798 | /* | |
799 | * This was an indexing LEB and it cannot be | |
800 | * immediately used. And instead of requesting the | |
801 | * commit straight away, we try to garbage collect some | |
802 | * more. | |
803 | */ | |
804 | dbg_gc("indexing LEB %d freed, continue", lp.lnum); | |
805 | continue; | |
806 | } | |
807 | ||
808 | ubifs_assert(ret == LEB_RETAINED); | |
809 | space_after = c->leb_size - wbuf->offs - wbuf->used; | |
810 | dbg_gc("LEB %d retained, freed %d bytes", lp.lnum, | |
811 | space_after - space_before); | |
812 | ||
813 | if (space_after > space_before) { | |
814 | /* GC makes progress, keep working */ | |
815 | min_space >>= 1; | |
816 | if (min_space < c->dead_wm) | |
817 | min_space = c->dead_wm; | |
818 | continue; | |
819 | } | |
820 | ||
821 | dbg_gc("did not make progress"); | |
822 | ||
823 | /* | |
824 | * GC moved an LEB bud have not done any progress. This means | |
825 | * that the previous GC head LEB contained too few free space | |
826 | * and the LEB which was GC'ed contained only large nodes which | |
827 | * did not fit that space. | |
828 | * | |
829 | * We can do 2 things: | |
830 | * 1. pick another LEB in a hope it'll contain a small node | |
831 | * which will fit the space we have at the end of current GC | |
832 | * head LEB, but there is no guarantee, so we try this out | |
833 | * unless we have already been working for too long; | |
834 | * 2. request an LEB with more dirty space, which will force | |
835 | * 'ubifs_find_dirty_leb()' to start scanning the lprops | |
836 | * table, instead of just picking one from the heap | |
837 | * (previously it already picked the dirtiest LEB). | |
838 | */ | |
839 | if (i < SOFT_LEBS_LIMIT) { | |
840 | dbg_gc("try again"); | |
841 | continue; | |
842 | } | |
843 | ||
844 | min_space <<= 1; | |
845 | if (min_space > c->dark_wm) | |
846 | min_space = c->dark_wm; | |
847 | dbg_gc("set min. space to %d", min_space); | |
848 | } | |
849 | ||
850 | if (ret == -ENOSPC && !list_empty(&c->idx_gc)) { | |
851 | dbg_gc("no space, some index LEBs GC'ed, -EAGAIN"); | |
852 | ubifs_commit_required(c); | |
853 | ret = -EAGAIN; | |
854 | } | |
855 | ||
856 | err = ubifs_wbuf_sync_nolock(wbuf); | |
857 | if (!err) | |
858 | err = ubifs_leb_unmap(c, c->gc_lnum); | |
859 | if (err) { | |
860 | ret = err; | |
861 | goto out; | |
862 | } | |
863 | out_unlock: | |
864 | mutex_unlock(&wbuf->io_mutex); | |
865 | return ret; | |
866 | ||
867 | out: | |
868 | ubifs_assert(ret < 0); | |
869 | ubifs_assert(ret != -ENOSPC && ret != -EAGAIN); | |
870 | ubifs_ro_mode(c, ret); | |
871 | ubifs_wbuf_sync_nolock(wbuf); | |
872 | mutex_unlock(&wbuf->io_mutex); | |
873 | ubifs_return_leb(c, lp.lnum); | |
874 | return ret; | |
875 | } | |
876 | ||
877 | /** | |
878 | * ubifs_gc_start_commit - garbage collection at start of commit. | |
879 | * @c: UBIFS file-system description object | |
880 | * | |
881 | * If a LEB has only dirty and free space, then we may safely unmap it and make | |
882 | * it free. Note, we cannot do this with indexing LEBs because dirty space may | |
883 | * correspond index nodes that are required for recovery. In that case, the | |
884 | * LEB cannot be unmapped until after the next commit. | |
885 | * | |
886 | * This function returns %0 upon success and a negative error code upon failure. | |
887 | */ | |
888 | int ubifs_gc_start_commit(struct ubifs_info *c) | |
889 | { | |
890 | struct ubifs_gced_idx_leb *idx_gc; | |
891 | const struct ubifs_lprops *lp; | |
892 | int err = 0, flags; | |
893 | ||
894 | ubifs_get_lprops(c); | |
895 | ||
896 | /* | |
897 | * Unmap (non-index) freeable LEBs. Note that recovery requires that all | |
898 | * wbufs are sync'd before this, which is done in 'do_commit()'. | |
899 | */ | |
900 | while (1) { | |
901 | lp = ubifs_fast_find_freeable(c); | |
8d47aef4 | 902 | if (IS_ERR(lp)) { |
1e51764a AB |
903 | err = PTR_ERR(lp); |
904 | goto out; | |
905 | } | |
906 | if (!lp) | |
907 | break; | |
908 | ubifs_assert(!(lp->flags & LPROPS_TAKEN)); | |
909 | ubifs_assert(!(lp->flags & LPROPS_INDEX)); | |
910 | err = ubifs_leb_unmap(c, lp->lnum); | |
911 | if (err) | |
912 | goto out; | |
913 | lp = ubifs_change_lp(c, lp, c->leb_size, 0, lp->flags, 0); | |
8d47aef4 | 914 | if (IS_ERR(lp)) { |
1e51764a AB |
915 | err = PTR_ERR(lp); |
916 | goto out; | |
917 | } | |
918 | ubifs_assert(!(lp->flags & LPROPS_TAKEN)); | |
919 | ubifs_assert(!(lp->flags & LPROPS_INDEX)); | |
920 | } | |
921 | ||
922 | /* Mark GC'd index LEBs OK to unmap after this commit finishes */ | |
923 | list_for_each_entry(idx_gc, &c->idx_gc, list) | |
924 | idx_gc->unmap = 1; | |
925 | ||
926 | /* Record index freeable LEBs for unmapping after commit */ | |
927 | while (1) { | |
928 | lp = ubifs_fast_find_frdi_idx(c); | |
8d47aef4 | 929 | if (IS_ERR(lp)) { |
1e51764a AB |
930 | err = PTR_ERR(lp); |
931 | goto out; | |
932 | } | |
933 | if (!lp) | |
934 | break; | |
935 | idx_gc = kmalloc(sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); | |
936 | if (!idx_gc) { | |
937 | err = -ENOMEM; | |
938 | goto out; | |
939 | } | |
940 | ubifs_assert(!(lp->flags & LPROPS_TAKEN)); | |
941 | ubifs_assert(lp->flags & LPROPS_INDEX); | |
942 | /* Don't release the LEB until after the next commit */ | |
943 | flags = (lp->flags | LPROPS_TAKEN) ^ LPROPS_INDEX; | |
944 | lp = ubifs_change_lp(c, lp, c->leb_size, 0, flags, 1); | |
8d47aef4 | 945 | if (IS_ERR(lp)) { |
1e51764a AB |
946 | err = PTR_ERR(lp); |
947 | kfree(idx_gc); | |
948 | goto out; | |
949 | } | |
950 | ubifs_assert(lp->flags & LPROPS_TAKEN); | |
951 | ubifs_assert(!(lp->flags & LPROPS_INDEX)); | |
952 | idx_gc->lnum = lp->lnum; | |
953 | idx_gc->unmap = 1; | |
954 | list_add(&idx_gc->list, &c->idx_gc); | |
955 | } | |
956 | out: | |
957 | ubifs_release_lprops(c); | |
958 | return err; | |
959 | } | |
960 | ||
961 | /** | |
962 | * ubifs_gc_end_commit - garbage collection at end of commit. | |
963 | * @c: UBIFS file-system description object | |
964 | * | |
965 | * This function completes out-of-place garbage collection of index LEBs. | |
966 | */ | |
967 | int ubifs_gc_end_commit(struct ubifs_info *c) | |
968 | { | |
969 | struct ubifs_gced_idx_leb *idx_gc, *tmp; | |
970 | struct ubifs_wbuf *wbuf; | |
971 | int err = 0; | |
972 | ||
973 | wbuf = &c->jheads[GCHD].wbuf; | |
974 | mutex_lock_nested(&wbuf->io_mutex, wbuf->jhead); | |
975 | list_for_each_entry_safe(idx_gc, tmp, &c->idx_gc, list) | |
976 | if (idx_gc->unmap) { | |
977 | dbg_gc("LEB %d", idx_gc->lnum); | |
978 | err = ubifs_leb_unmap(c, idx_gc->lnum); | |
979 | if (err) | |
980 | goto out; | |
981 | err = ubifs_change_one_lp(c, idx_gc->lnum, LPROPS_NC, | |
982 | LPROPS_NC, 0, LPROPS_TAKEN, -1); | |
983 | if (err) | |
984 | goto out; | |
985 | list_del(&idx_gc->list); | |
986 | kfree(idx_gc); | |
987 | } | |
988 | out: | |
989 | mutex_unlock(&wbuf->io_mutex); | |
990 | return err; | |
991 | } | |
992 | ||
993 | /** | |
994 | * ubifs_destroy_idx_gc - destroy idx_gc list. | |
995 | * @c: UBIFS file-system description object | |
996 | * | |
b466f17d AH |
997 | * This function destroys the @c->idx_gc list. It is called when unmounting |
998 | * so locks are not needed. Returns zero in case of success and a negative | |
999 | * error code in case of failure. | |
1e51764a | 1000 | */ |
b466f17d | 1001 | void ubifs_destroy_idx_gc(struct ubifs_info *c) |
1e51764a AB |
1002 | { |
1003 | while (!list_empty(&c->idx_gc)) { | |
1004 | struct ubifs_gced_idx_leb *idx_gc; | |
1005 | ||
1006 | idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, | |
1007 | list); | |
b466f17d | 1008 | c->idx_gc_cnt -= 1; |
1e51764a AB |
1009 | list_del(&idx_gc->list); |
1010 | kfree(idx_gc); | |
1011 | } | |
1e51764a AB |
1012 | } |
1013 | ||
1014 | /** | |
1015 | * ubifs_get_idx_gc_leb - get a LEB from GC'd index LEB list. | |
1016 | * @c: UBIFS file-system description object | |
1017 | * | |
1018 | * Called during start commit so locks are not needed. | |
1019 | */ | |
1020 | int ubifs_get_idx_gc_leb(struct ubifs_info *c) | |
1021 | { | |
1022 | struct ubifs_gced_idx_leb *idx_gc; | |
1023 | int lnum; | |
1024 | ||
1025 | if (list_empty(&c->idx_gc)) | |
1026 | return -ENOSPC; | |
1027 | idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, list); | |
1028 | lnum = idx_gc->lnum; | |
1029 | /* c->idx_gc_cnt is updated by the caller when lprops are updated */ | |
1030 | list_del(&idx_gc->list); | |
1031 | kfree(idx_gc); | |
1032 | return lnum; | |
1033 | } |