1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * This file is part of UBIFS. |
4 | * |
5 | * Copyright (C) 2006-2008 Nokia Corporation. |
6 | * |
7 | * Authors: Adrian Hunter |
8 | * Artem Bityutskiy (Битюцкий Артём) |
9 | */ |
10 | |
11 | /* |
12 | * This file implements garbage collection. The procedure for garbage collection |
13 | * is different depending on whether a LEB as an index LEB (contains index |
14 | * nodes) or not. For non-index LEBs, garbage collection finds a LEB which |
15 | * contains a lot of dirty space (obsolete nodes), and copies the non-obsolete |
16 | * nodes to the journal, at which point the garbage-collected LEB is free to be |
17 | * reused. For index LEBs, garbage collection marks the non-obsolete index nodes |
18 | * dirty in the TNC, and after the next commit, the garbage-collected LEB is |
19 | * to be reused. Garbage collection will cause the number of dirty index nodes |
20 | * to grow, however sufficient space is reserved for the index to ensure the |
21 | * commit will never run out of space. |
22 | * |
23 | * Notes about dead watermark. At current UBIFS implementation we assume that |
24 | * LEBs which have less than @c->dead_wm bytes of free + dirty space are full |
25 | * and not worth garbage-collecting. The dead watermark is one min. I/O unit |
26 | * size, or min. UBIFS node size, depending on what is greater. Indeed, UBIFS |
27 | * Garbage Collector has to synchronize the GC head's write buffer before |
28 | * returning, so this is about wasting one min. I/O unit. However, UBIFS GC can |
29 | * actually reclaim even very small pieces of dirty space by garbage collecting |
30 | * enough dirty LEBs, but we do not bother doing this at this implementation. |
31 | * |
32 | * Notes about dark watermark. The results of GC work depends on how big are |
33 | * the UBIFS nodes GC deals with. Large nodes make GC waste more space. Indeed, |
34 | * if GC move data from LEB A to LEB B and nodes in LEB A are large, GC would |
35 | * have to waste large pieces of free space at the end of LEB B, because nodes |
36 | * from LEB A would not fit. And the worst situation is when all nodes are of |
37 | * maximum size. So dark watermark is the amount of free + dirty space in LEB |
38 | * which are guaranteed to be reclaimable. If LEB has less space, the GC might |
39 | * be unable to reclaim it. So, LEBs with free + dirty greater than dark |
40 | * watermark are "good" LEBs from GC's point of view. The other LEBs are not so |
41 | * good, and GC takes extra care when moving them. |
42 | */ |
43 | |
44 | #include <linux/slab.h> |
45 | #include <linux/pagemap.h> |
46 | #include <linux/list_sort.h> |
47 | #include "ubifs.h" |
48 | |
49 | /* |
50 | * GC may need to move more than one LEB to make progress. The below constants |
51 | * define "soft" and "hard" limits on the number of LEBs the garbage collector |
52 | * may move. |
53 | */ |
54 | #define SOFT_LEBS_LIMIT 4 |
55 | #define HARD_LEBS_LIMIT 32 |
56 | |
57 | /** |
58 | * switch_gc_head - switch the garbage collection journal head. |
59 | * @c: UBIFS file-system description object |
60 | * |
61 | * This function switch the GC head to the next LEB which is reserved in |
62 | * @c->gc_lnum. Returns %0 in case of success, %-EAGAIN if commit is required, |
63 | * and other negative error code in case of failures. |
64 | */ |
65 | static int switch_gc_head(struct ubifs_info *c) |
66 | { |
67 | int err, gc_lnum = c->gc_lnum; |
68 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
69 | |
70 | ubifs_assert(c, gc_lnum != -1); |
71 | dbg_gc("switch GC head from LEB %d:%d to LEB %d (waste %d bytes)" , |
72 | wbuf->lnum, wbuf->offs + wbuf->used, gc_lnum, |
73 | c->leb_size - wbuf->offs - wbuf->used); |
74 | |
75 | err = ubifs_wbuf_sync_nolock(wbuf); |
76 | if (err) |
77 | return err; |
78 | |
79 | /* |
80 | * The GC write-buffer was synchronized, we may safely unmap |
81 | * 'c->gc_lnum'. |
82 | */ |
83 | err = ubifs_leb_unmap(c, lnum: gc_lnum); |
84 | if (err) |
85 | return err; |
86 | |
87 | err = ubifs_add_bud_to_log(c, GCHD, lnum: gc_lnum, offs: 0); |
88 | if (err) |
89 | return err; |
90 | |
91 | c->gc_lnum = -1; |
92 | err = ubifs_wbuf_seek_nolock(wbuf, lnum: gc_lnum, offs: 0); |
93 | return err; |
94 | } |
95 | |
96 | /** |
97 | * data_nodes_cmp - compare 2 data nodes. |
98 | * @priv: UBIFS file-system description object |
99 | * @a: first data node |
100 | * @b: second data node |
101 | * |
102 | * This function compares data nodes @a and @b. Returns %1 if @a has greater |
103 | * inode or block number, and %-1 otherwise. |
104 | */ |
105 | static int data_nodes_cmp(void *priv, const struct list_head *a, |
106 | const struct list_head *b) |
107 | { |
108 | ino_t inuma, inumb; |
109 | struct ubifs_info *c = priv; |
110 | struct ubifs_scan_node *sa, *sb; |
111 | |
112 | cond_resched(); |
113 | if (a == b) |
114 | return 0; |
115 | |
116 | sa = list_entry(a, struct ubifs_scan_node, list); |
117 | sb = list_entry(b, struct ubifs_scan_node, list); |
118 | |
119 | ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DATA_KEY); |
120 | ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DATA_KEY); |
121 | ubifs_assert(c, sa->type == UBIFS_DATA_NODE); |
122 | ubifs_assert(c, sb->type == UBIFS_DATA_NODE); |
123 | |
124 | inuma = key_inum(c, k: &sa->key); |
125 | inumb = key_inum(c, k: &sb->key); |
126 | |
127 | if (inuma == inumb) { |
128 | unsigned int blka = key_block(c, key: &sa->key); |
129 | unsigned int blkb = key_block(c, key: &sb->key); |
130 | |
131 | if (blka <= blkb) |
132 | return -1; |
133 | } else if (inuma <= inumb) |
134 | return -1; |
135 | |
136 | return 1; |
137 | } |
138 | |
139 | /* |
140 | * nondata_nodes_cmp - compare 2 non-data nodes. |
141 | * @priv: UBIFS file-system description object |
142 | * @a: first node |
143 | * @a: second node |
144 | * |
145 | * This function compares nodes @a and @b. It makes sure that inode nodes go |
146 | * first and sorted by length in descending order. Directory entry nodes go |
147 | * after inode nodes and are sorted in ascending hash valuer order. |
148 | */ |
149 | static int nondata_nodes_cmp(void *priv, const struct list_head *a, |
150 | const struct list_head *b) |
151 | { |
152 | ino_t inuma, inumb; |
153 | struct ubifs_info *c = priv; |
154 | struct ubifs_scan_node *sa, *sb; |
155 | |
156 | cond_resched(); |
157 | if (a == b) |
158 | return 0; |
159 | |
160 | sa = list_entry(a, struct ubifs_scan_node, list); |
161 | sb = list_entry(b, struct ubifs_scan_node, list); |
162 | |
163 | ubifs_assert(c, key_type(c, &sa->key) != UBIFS_DATA_KEY && |
164 | key_type(c, &sb->key) != UBIFS_DATA_KEY); |
165 | ubifs_assert(c, sa->type != UBIFS_DATA_NODE && |
166 | sb->type != UBIFS_DATA_NODE); |
167 | |
168 | /* Inodes go before directory entries */ |
169 | if (sa->type == UBIFS_INO_NODE) { |
170 | if (sb->type == UBIFS_INO_NODE) |
171 | return sb->len - sa->len; |
172 | return -1; |
173 | } |
174 | if (sb->type == UBIFS_INO_NODE) |
175 | return 1; |
176 | |
177 | ubifs_assert(c, key_type(c, &sa->key) == UBIFS_DENT_KEY || |
178 | key_type(c, &sa->key) == UBIFS_XENT_KEY); |
179 | ubifs_assert(c, key_type(c, &sb->key) == UBIFS_DENT_KEY || |
180 | key_type(c, &sb->key) == UBIFS_XENT_KEY); |
181 | ubifs_assert(c, sa->type == UBIFS_DENT_NODE || |
182 | sa->type == UBIFS_XENT_NODE); |
183 | ubifs_assert(c, sb->type == UBIFS_DENT_NODE || |
184 | sb->type == UBIFS_XENT_NODE); |
185 | |
186 | inuma = key_inum(c, k: &sa->key); |
187 | inumb = key_inum(c, k: &sb->key); |
188 | |
189 | if (inuma == inumb) { |
190 | uint32_t hasha = key_hash(c, key: &sa->key); |
191 | uint32_t hashb = key_hash(c, key: &sb->key); |
192 | |
193 | if (hasha <= hashb) |
194 | return -1; |
195 | } else if (inuma <= inumb) |
196 | return -1; |
197 | |
198 | return 1; |
199 | } |
200 | |
201 | /** |
202 | * sort_nodes - sort nodes for GC. |
203 | * @c: UBIFS file-system description object |
204 | * @sleb: describes nodes to sort and contains the result on exit |
205 | * @nondata: contains non-data nodes on exit |
206 | * @min: minimum node size is returned here |
207 | * |
208 | * This function sorts the list of inodes to garbage collect. First of all, it |
209 | * kills obsolete nodes and separates data and non-data nodes to the |
210 | * @sleb->nodes and @nondata lists correspondingly. |
211 | * |
212 | * Data nodes are then sorted in block number order - this is important for |
213 | * bulk-read; data nodes with lower inode number go before data nodes with |
214 | * higher inode number, and data nodes with lower block number go before data |
215 | * nodes with higher block number; |
216 | * |
217 | * Non-data nodes are sorted as follows. |
218 | * o First go inode nodes - they are sorted in descending length order. |
219 | * o Then go directory entry nodes - they are sorted in hash order, which |
220 | * should supposedly optimize 'readdir()'. Direntry nodes with lower parent |
221 | * inode number go before direntry nodes with higher parent inode number, |
222 | * and direntry nodes with lower name hash values go before direntry nodes |
223 | * with higher name hash values. |
224 | * |
225 | * This function returns zero in case of success and a negative error code in |
226 | * case of failure. |
227 | */ |
228 | static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb, |
229 | struct list_head *nondata, int *min) |
230 | { |
231 | int err; |
232 | struct ubifs_scan_node *snod, *tmp; |
233 | |
234 | *min = INT_MAX; |
235 | |
236 | /* Separate data nodes and non-data nodes */ |
237 | list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { |
238 | ubifs_assert(c, snod->type == UBIFS_INO_NODE || |
239 | snod->type == UBIFS_DATA_NODE || |
240 | snod->type == UBIFS_DENT_NODE || |
241 | snod->type == UBIFS_XENT_NODE || |
242 | snod->type == UBIFS_TRUN_NODE || |
243 | snod->type == UBIFS_AUTH_NODE); |
244 | |
245 | if (snod->type != UBIFS_INO_NODE && |
246 | snod->type != UBIFS_DATA_NODE && |
247 | snod->type != UBIFS_DENT_NODE && |
248 | snod->type != UBIFS_XENT_NODE) { |
249 | /* Probably truncation node, zap it */ |
250 | list_del(entry: &snod->list); |
251 | kfree(objp: snod); |
252 | continue; |
253 | } |
254 | |
255 | ubifs_assert(c, key_type(c, &snod->key) == UBIFS_DATA_KEY || |
256 | key_type(c, &snod->key) == UBIFS_INO_KEY || |
257 | key_type(c, &snod->key) == UBIFS_DENT_KEY || |
258 | key_type(c, &snod->key) == UBIFS_XENT_KEY); |
259 | |
260 | err = ubifs_tnc_has_node(c, key: &snod->key, level: 0, lnum: sleb->lnum, |
261 | offs: snod->offs, is_idx: 0); |
262 | if (err < 0) |
263 | return err; |
264 | |
265 | if (!err) { |
266 | /* The node is obsolete, remove it from the list */ |
267 | list_del(entry: &snod->list); |
268 | kfree(objp: snod); |
269 | continue; |
270 | } |
271 | |
272 | if (snod->len < *min) |
273 | *min = snod->len; |
274 | |
275 | if (key_type(c, key: &snod->key) != UBIFS_DATA_KEY) |
276 | list_move_tail(list: &snod->list, head: nondata); |
277 | } |
278 | |
279 | /* Sort data and non-data nodes */ |
280 | list_sort(priv: c, head: &sleb->nodes, cmp: &data_nodes_cmp); |
281 | list_sort(priv: c, head: nondata, cmp: &nondata_nodes_cmp); |
282 | |
283 | err = dbg_check_data_nodes_order(c, head: &sleb->nodes); |
284 | if (err) |
285 | return err; |
286 | err = dbg_check_nondata_nodes_order(c, head: nondata); |
287 | if (err) |
288 | return err; |
289 | return 0; |
290 | } |
291 | |
292 | /** |
293 | * move_node - move a node. |
294 | * @c: UBIFS file-system description object |
295 | * @sleb: describes the LEB to move nodes from |
296 | * @snod: the mode to move |
297 | * @wbuf: write-buffer to move node to |
298 | * |
299 | * This function moves node @snod to @wbuf, changes TNC correspondingly, and |
300 | * destroys @snod. Returns zero in case of success and a negative error code in |
301 | * case of failure. |
302 | */ |
303 | static int move_node(struct ubifs_info *c, struct ubifs_scan_leb *sleb, |
304 | struct ubifs_scan_node *snod, struct ubifs_wbuf *wbuf) |
305 | { |
306 | int err, new_lnum = wbuf->lnum, new_offs = wbuf->offs + wbuf->used; |
307 | |
308 | cond_resched(); |
309 | err = ubifs_wbuf_write_nolock(wbuf, buf: snod->node, len: snod->len); |
310 | if (err) |
311 | return err; |
312 | |
313 | err = ubifs_tnc_replace(c, key: &snod->key, old_lnum: sleb->lnum, |
314 | old_offs: snod->offs, lnum: new_lnum, offs: new_offs, |
315 | len: snod->len); |
316 | list_del(entry: &snod->list); |
317 | kfree(objp: snod); |
318 | return err; |
319 | } |
320 | |
321 | /** |
322 | * move_nodes - move nodes. |
323 | * @c: UBIFS file-system description object |
324 | * @sleb: describes the LEB to move nodes from |
325 | * |
326 | * This function moves valid nodes from data LEB described by @sleb to the GC |
327 | * journal head. This function returns zero in case of success, %-EAGAIN if |
328 | * commit is required, and other negative error codes in case of other |
329 | * failures. |
330 | */ |
331 | static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb) |
332 | { |
333 | int err, min; |
334 | LIST_HEAD(nondata); |
335 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
336 | |
337 | if (wbuf->lnum == -1) { |
338 | /* |
339 | * The GC journal head is not set, because it is the first GC |
340 | * invocation since mount. |
341 | */ |
342 | err = switch_gc_head(c); |
343 | if (err) |
344 | return err; |
345 | } |
346 | |
347 | err = sort_nodes(c, sleb, nondata: &nondata, min: &min); |
348 | if (err) |
349 | goto out; |
350 | |
351 | /* Write nodes to their new location. Use the first-fit strategy */ |
352 | while (1) { |
353 | int avail, moved = 0; |
354 | struct ubifs_scan_node *snod, *tmp; |
355 | |
356 | /* Move data nodes */ |
357 | list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) { |
358 | avail = c->leb_size - wbuf->offs - wbuf->used - |
359 | ubifs_auth_node_sz(c); |
360 | if (snod->len > avail) |
361 | /* |
362 | * Do not skip data nodes in order to optimize |
363 | * bulk-read. |
364 | */ |
365 | break; |
366 | |
367 | err = ubifs_shash_update(c, desc: c->jheads[GCHD].log_hash, |
368 | buf: snod->node, len: snod->len); |
369 | if (err) |
370 | goto out; |
371 | |
372 | err = move_node(c, sleb, snod, wbuf); |
373 | if (err) |
374 | goto out; |
375 | moved = 1; |
376 | } |
377 | |
378 | /* Move non-data nodes */ |
379 | list_for_each_entry_safe(snod, tmp, &nondata, list) { |
380 | avail = c->leb_size - wbuf->offs - wbuf->used - |
381 | ubifs_auth_node_sz(c); |
382 | if (avail < min) |
383 | break; |
384 | |
385 | if (snod->len > avail) { |
386 | /* |
387 | * Keep going only if this is an inode with |
388 | * some data. Otherwise stop and switch the GC |
389 | * head. IOW, we assume that data-less inode |
390 | * nodes and direntry nodes are roughly of the |
391 | * same size. |
392 | */ |
393 | if (key_type(c, key: &snod->key) == UBIFS_DENT_KEY || |
394 | snod->len == UBIFS_INO_NODE_SZ) |
395 | break; |
396 | continue; |
397 | } |
398 | |
399 | err = ubifs_shash_update(c, desc: c->jheads[GCHD].log_hash, |
400 | buf: snod->node, len: snod->len); |
401 | if (err) |
402 | goto out; |
403 | |
404 | err = move_node(c, sleb, snod, wbuf); |
405 | if (err) |
406 | goto out; |
407 | moved = 1; |
408 | } |
409 | |
410 | if (ubifs_authenticated(c) && moved) { |
411 | struct ubifs_auth_node *auth; |
412 | |
413 | auth = kmalloc(size: ubifs_auth_node_sz(c), GFP_NOFS); |
414 | if (!auth) { |
415 | err = -ENOMEM; |
416 | goto out; |
417 | } |
418 | |
419 | err = ubifs_prepare_auth_node(c, node: auth, |
420 | inhash: c->jheads[GCHD].log_hash); |
421 | if (err) { |
422 | kfree(objp: auth); |
423 | goto out; |
424 | } |
425 | |
426 | err = ubifs_wbuf_write_nolock(wbuf, buf: auth, |
427 | len: ubifs_auth_node_sz(c)); |
428 | if (err) { |
429 | kfree(objp: auth); |
430 | goto out; |
431 | } |
432 | |
433 | ubifs_add_dirt(c, lnum: wbuf->lnum, dirty: ubifs_auth_node_sz(c)); |
434 | } |
435 | |
436 | if (list_empty(head: &sleb->nodes) && list_empty(head: &nondata)) |
437 | break; |
438 | |
439 | /* |
440 | * Waste the rest of the space in the LEB and switch to the |
441 | * next LEB. |
442 | */ |
443 | err = switch_gc_head(c); |
444 | if (err) |
445 | goto out; |
446 | } |
447 | |
448 | return 0; |
449 | |
450 | out: |
451 | list_splice_tail(list: &nondata, head: &sleb->nodes); |
452 | return err; |
453 | } |
454 | |
455 | /** |
456 | * gc_sync_wbufs - sync write-buffers for GC. |
457 | * @c: UBIFS file-system description object |
458 | * |
459 | * We must guarantee that obsoleting nodes are on flash. Unfortunately they may |
460 | * be in a write-buffer instead. That is, a node could be written to a |
461 | * write-buffer, obsoleting another node in a LEB that is GC'd. If that LEB is |
462 | * erased before the write-buffer is sync'd and then there is an unclean |
463 | * unmount, then an existing node is lost. To avoid this, we sync all |
464 | * write-buffers. |
465 | * |
466 | * This function returns %0 on success or a negative error code on failure. |
467 | */ |
468 | static int gc_sync_wbufs(struct ubifs_info *c) |
469 | { |
470 | int err, i; |
471 | |
472 | for (i = 0; i < c->jhead_cnt; i++) { |
473 | if (i == GCHD) |
474 | continue; |
475 | err = ubifs_wbuf_sync(wbuf: &c->jheads[i].wbuf); |
476 | if (err) |
477 | return err; |
478 | } |
479 | return 0; |
480 | } |
481 | |
482 | /** |
483 | * ubifs_garbage_collect_leb - garbage-collect a logical eraseblock. |
484 | * @c: UBIFS file-system description object |
485 | * @lp: describes the LEB to garbage collect |
486 | * |
487 | * This function garbage-collects an LEB and returns one of the @LEB_FREED, |
488 | * @LEB_RETAINED, etc positive codes in case of success, %-EAGAIN if commit is |
489 | * required, and other negative error codes in case of failures. |
490 | */ |
491 | int ubifs_garbage_collect_leb(struct ubifs_info *c, struct ubifs_lprops *lp) |
492 | { |
493 | struct ubifs_scan_leb *sleb; |
494 | struct ubifs_scan_node *snod; |
495 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
496 | int err = 0, lnum = lp->lnum; |
497 | |
498 | ubifs_assert(c, c->gc_lnum != -1 || wbuf->offs + wbuf->used == 0 || |
499 | c->need_recovery); |
500 | ubifs_assert(c, c->gc_lnum != lnum); |
501 | ubifs_assert(c, wbuf->lnum != lnum); |
502 | |
503 | if (lp->free + lp->dirty == c->leb_size) { |
504 | /* Special case - a free LEB */ |
505 | dbg_gc("LEB %d is free, return it" , lp->lnum); |
506 | ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
507 | |
508 | if (lp->free != c->leb_size) { |
509 | /* |
510 | * Write buffers must be sync'd before unmapping |
511 | * freeable LEBs, because one of them may contain data |
512 | * which obsoletes something in 'lp->lnum'. |
513 | */ |
514 | err = gc_sync_wbufs(c); |
515 | if (err) |
516 | return err; |
517 | err = ubifs_change_one_lp(c, lnum: lp->lnum, free: c->leb_size, |
518 | dirty: 0, flags_set: 0, flags_clean: 0, idx_gc_cnt: 0); |
519 | if (err) |
520 | return err; |
521 | } |
522 | err = ubifs_leb_unmap(c, lnum: lp->lnum); |
523 | if (err) |
524 | return err; |
525 | |
526 | if (c->gc_lnum == -1) { |
527 | c->gc_lnum = lnum; |
528 | return LEB_RETAINED; |
529 | } |
530 | |
531 | return LEB_FREED; |
532 | } |
533 | |
534 | /* |
535 | * We scan the entire LEB even though we only really need to scan up to |
536 | * (c->leb_size - lp->free). |
537 | */ |
538 | sleb = ubifs_scan(c, lnum, offs: 0, sbuf: c->sbuf, quiet: 0); |
539 | if (IS_ERR(ptr: sleb)) |
540 | return PTR_ERR(ptr: sleb); |
541 | |
542 | ubifs_assert(c, !list_empty(&sleb->nodes)); |
543 | snod = list_entry(sleb->nodes.next, struct ubifs_scan_node, list); |
544 | |
545 | if (snod->type == UBIFS_IDX_NODE) { |
546 | struct ubifs_gced_idx_leb *idx_gc; |
547 | |
548 | dbg_gc("indexing LEB %d (free %d, dirty %d)" , |
549 | lnum, lp->free, lp->dirty); |
550 | list_for_each_entry(snod, &sleb->nodes, list) { |
551 | struct ubifs_idx_node *idx = snod->node; |
552 | int level = le16_to_cpu(idx->level); |
553 | |
554 | ubifs_assert(c, snod->type == UBIFS_IDX_NODE); |
555 | key_read(c, from: ubifs_idx_key(c, idx), to: &snod->key); |
556 | err = ubifs_dirty_idx_node(c, key: &snod->key, level, lnum, |
557 | offs: snod->offs); |
558 | if (err) |
559 | goto out; |
560 | } |
561 | |
562 | idx_gc = kmalloc(size: sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); |
563 | if (!idx_gc) { |
564 | err = -ENOMEM; |
565 | goto out; |
566 | } |
567 | |
568 | idx_gc->lnum = lnum; |
569 | idx_gc->unmap = 0; |
570 | list_add(new: &idx_gc->list, head: &c->idx_gc); |
571 | |
572 | /* |
573 | * Don't release the LEB until after the next commit, because |
574 | * it may contain data which is needed for recovery. So |
575 | * although we freed this LEB, it will become usable only after |
576 | * the commit. |
577 | */ |
578 | err = ubifs_change_one_lp(c, lnum, free: c->leb_size, dirty: 0, flags_set: 0, |
579 | flags_clean: LPROPS_INDEX, idx_gc_cnt: 1); |
580 | if (err) |
581 | goto out; |
582 | err = LEB_FREED_IDX; |
583 | } else { |
584 | dbg_gc("data LEB %d (free %d, dirty %d)" , |
585 | lnum, lp->free, lp->dirty); |
586 | |
587 | err = move_nodes(c, sleb); |
588 | if (err) |
589 | goto out_inc_seq; |
590 | |
591 | err = gc_sync_wbufs(c); |
592 | if (err) |
593 | goto out_inc_seq; |
594 | |
595 | err = ubifs_change_one_lp(c, lnum, free: c->leb_size, dirty: 0, flags_set: 0, flags_clean: 0, idx_gc_cnt: 0); |
596 | if (err) |
597 | goto out_inc_seq; |
598 | |
599 | /* Allow for races with TNC */ |
600 | c->gced_lnum = lnum; |
601 | smp_wmb(); |
602 | c->gc_seq += 1; |
603 | smp_wmb(); |
604 | |
605 | if (c->gc_lnum == -1) { |
606 | c->gc_lnum = lnum; |
607 | err = LEB_RETAINED; |
608 | } else { |
609 | err = ubifs_wbuf_sync_nolock(wbuf); |
610 | if (err) |
611 | goto out; |
612 | |
613 | err = ubifs_leb_unmap(c, lnum); |
614 | if (err) |
615 | goto out; |
616 | |
617 | err = LEB_FREED; |
618 | } |
619 | } |
620 | |
621 | out: |
622 | ubifs_scan_destroy(sleb); |
623 | return err; |
624 | |
625 | out_inc_seq: |
626 | /* We may have moved at least some nodes so allow for races with TNC */ |
627 | c->gced_lnum = lnum; |
628 | smp_wmb(); |
629 | c->gc_seq += 1; |
630 | smp_wmb(); |
631 | goto out; |
632 | } |
633 | |
634 | /** |
635 | * ubifs_garbage_collect - UBIFS garbage collector. |
636 | * @c: UBIFS file-system description object |
637 | * @anyway: do GC even if there are free LEBs |
638 | * |
639 | * This function does out-of-place garbage collection. The return codes are: |
640 | * o positive LEB number if the LEB has been freed and may be used; |
641 | * o %-EAGAIN if the caller has to run commit; |
642 | * o %-ENOSPC if GC failed to make any progress; |
643 | * o other negative error codes in case of other errors. |
644 | * |
645 | * Garbage collector writes data to the journal when GC'ing data LEBs, and just |
646 | * marking indexing nodes dirty when GC'ing indexing LEBs. Thus, at some point |
647 | * commit may be required. But commit cannot be run from inside GC, because the |
648 | * caller might be holding the commit lock, so %-EAGAIN is returned instead; |
649 | * And this error code means that the caller has to run commit, and re-run GC |
650 | * if there is still no free space. |
651 | * |
652 | * There are many reasons why this function may return %-EAGAIN: |
653 | * o the log is full and there is no space to write an LEB reference for |
654 | * @c->gc_lnum; |
655 | * o the journal is too large and exceeds size limitations; |
656 | * o GC moved indexing LEBs, but they can be used only after the commit; |
657 | * o the shrinker fails to find clean znodes to free and requests the commit; |
658 | * o etc. |
659 | * |
660 | * Note, if the file-system is close to be full, this function may return |
661 | * %-EAGAIN infinitely, so the caller has to limit amount of re-invocations of |
662 | * the function. E.g., this happens if the limits on the journal size are too |
663 | * tough and GC writes too much to the journal before an LEB is freed. This |
664 | * might also mean that the journal is too large, and the TNC becomes to big, |
665 | * so that the shrinker is constantly called, finds not clean znodes to free, |
666 | * and requests commit. Well, this may also happen if the journal is all right, |
667 | * but another kernel process consumes too much memory. Anyway, infinite |
668 | * %-EAGAIN may happen, but in some extreme/misconfiguration cases. |
669 | */ |
670 | int ubifs_garbage_collect(struct ubifs_info *c, int anyway) |
671 | { |
672 | int i, err, ret, min_space = c->dead_wm; |
673 | struct ubifs_lprops lp; |
674 | struct ubifs_wbuf *wbuf = &c->jheads[GCHD].wbuf; |
675 | |
676 | ubifs_assert_cmt_locked(c); |
677 | ubifs_assert(c, !c->ro_media && !c->ro_mount); |
678 | |
679 | if (ubifs_gc_should_commit(c)) |
680 | return -EAGAIN; |
681 | |
682 | mutex_lock_nested(lock: &wbuf->io_mutex, subclass: wbuf->jhead); |
683 | |
684 | if (c->ro_error) { |
685 | ret = -EROFS; |
686 | goto out_unlock; |
687 | } |
688 | |
689 | /* We expect the write-buffer to be empty on entry */ |
690 | ubifs_assert(c, !wbuf->used); |
691 | |
692 | for (i = 0; ; i++) { |
693 | int space_before, space_after; |
694 | |
695 | /* Maybe continue after find and break before find */ |
696 | lp.lnum = -1; |
697 | |
698 | cond_resched(); |
699 | |
700 | /* Give the commit an opportunity to run */ |
701 | if (ubifs_gc_should_commit(c)) { |
702 | ret = -EAGAIN; |
703 | break; |
704 | } |
705 | |
706 | if (i > SOFT_LEBS_LIMIT && !list_empty(head: &c->idx_gc)) { |
707 | /* |
708 | * We've done enough iterations. Indexing LEBs were |
709 | * moved and will be available after the commit. |
710 | */ |
711 | dbg_gc("soft limit, some index LEBs GC'ed, -EAGAIN" ); |
712 | ubifs_commit_required(c); |
713 | ret = -EAGAIN; |
714 | break; |
715 | } |
716 | |
717 | if (i > HARD_LEBS_LIMIT) { |
718 | /* |
719 | * We've moved too many LEBs and have not made |
720 | * progress, give up. |
721 | */ |
722 | dbg_gc("hard limit, -ENOSPC" ); |
723 | ret = -ENOSPC; |
724 | break; |
725 | } |
726 | |
727 | /* |
728 | * Empty and freeable LEBs can turn up while we waited for |
729 | * the wbuf lock, or while we have been running GC. In that |
730 | * case, we should just return one of those instead of |
731 | * continuing to GC dirty LEBs. Hence we request |
732 | * 'ubifs_find_dirty_leb()' to return an empty LEB if it can. |
733 | */ |
734 | ret = ubifs_find_dirty_leb(c, ret_lp: &lp, min_space, pick_free: anyway ? 0 : 1); |
735 | if (ret) { |
736 | if (ret == -ENOSPC) |
737 | dbg_gc("no more dirty LEBs" ); |
738 | break; |
739 | } |
740 | |
741 | dbg_gc("found LEB %d: free %d, dirty %d, sum %d (min. space %d)" , |
742 | lp.lnum, lp.free, lp.dirty, lp.free + lp.dirty, |
743 | min_space); |
744 | |
745 | space_before = c->leb_size - wbuf->offs - wbuf->used; |
746 | if (wbuf->lnum == -1) |
747 | space_before = 0; |
748 | |
749 | ret = ubifs_garbage_collect_leb(c, lp: &lp); |
750 | if (ret < 0) { |
751 | if (ret == -EAGAIN) { |
752 | /* |
753 | * This is not error, so we have to return the |
754 | * LEB to lprops. But if 'ubifs_return_leb()' |
755 | * fails, its failure code is propagated to the |
756 | * caller instead of the original '-EAGAIN'. |
757 | */ |
758 | err = ubifs_return_leb(c, lnum: lp.lnum); |
759 | if (err) { |
760 | ret = err; |
761 | /* |
762 | * An LEB may always be "taken", |
763 | * so setting ubifs to read-only, |
764 | * and then executing sync wbuf will |
765 | * return -EROFS and enter the "out" |
766 | * error branch. |
767 | */ |
768 | ubifs_ro_mode(c, err: ret); |
769 | } |
770 | /* Maybe double return LEB if goto out */ |
771 | lp.lnum = -1; |
772 | break; |
773 | } |
774 | goto out; |
775 | } |
776 | |
777 | if (ret == LEB_FREED) { |
778 | /* An LEB has been freed and is ready for use */ |
779 | dbg_gc("LEB %d freed, return" , lp.lnum); |
780 | ret = lp.lnum; |
781 | break; |
782 | } |
783 | |
784 | if (ret == LEB_FREED_IDX) { |
785 | /* |
786 | * This was an indexing LEB and it cannot be |
787 | * immediately used. And instead of requesting the |
788 | * commit straight away, we try to garbage collect some |
789 | * more. |
790 | */ |
791 | dbg_gc("indexing LEB %d freed, continue" , lp.lnum); |
792 | continue; |
793 | } |
794 | |
795 | ubifs_assert(c, ret == LEB_RETAINED); |
796 | space_after = c->leb_size - wbuf->offs - wbuf->used; |
797 | dbg_gc("LEB %d retained, freed %d bytes" , lp.lnum, |
798 | space_after - space_before); |
799 | |
800 | if (space_after > space_before) { |
801 | /* GC makes progress, keep working */ |
802 | min_space >>= 1; |
803 | if (min_space < c->dead_wm) |
804 | min_space = c->dead_wm; |
805 | continue; |
806 | } |
807 | |
808 | dbg_gc("did not make progress" ); |
809 | |
810 | /* |
811 | * GC moved an LEB bud have not done any progress. This means |
812 | * that the previous GC head LEB contained too few free space |
813 | * and the LEB which was GC'ed contained only large nodes which |
814 | * did not fit that space. |
815 | * |
816 | * We can do 2 things: |
817 | * 1. pick another LEB in a hope it'll contain a small node |
818 | * which will fit the space we have at the end of current GC |
819 | * head LEB, but there is no guarantee, so we try this out |
820 | * unless we have already been working for too long; |
821 | * 2. request an LEB with more dirty space, which will force |
822 | * 'ubifs_find_dirty_leb()' to start scanning the lprops |
823 | * table, instead of just picking one from the heap |
824 | * (previously it already picked the dirtiest LEB). |
825 | */ |
826 | if (i < SOFT_LEBS_LIMIT) { |
827 | dbg_gc("try again" ); |
828 | continue; |
829 | } |
830 | |
831 | min_space <<= 1; |
832 | if (min_space > c->dark_wm) |
833 | min_space = c->dark_wm; |
834 | dbg_gc("set min. space to %d" , min_space); |
835 | } |
836 | |
837 | if (ret == -ENOSPC && !list_empty(head: &c->idx_gc)) { |
838 | dbg_gc("no space, some index LEBs GC'ed, -EAGAIN" ); |
839 | ubifs_commit_required(c); |
840 | ret = -EAGAIN; |
841 | } |
842 | |
843 | err = ubifs_wbuf_sync_nolock(wbuf); |
844 | if (!err) |
845 | err = ubifs_leb_unmap(c, lnum: c->gc_lnum); |
846 | if (err) { |
847 | ret = err; |
848 | goto out; |
849 | } |
850 | out_unlock: |
851 | mutex_unlock(lock: &wbuf->io_mutex); |
852 | return ret; |
853 | |
854 | out: |
855 | ubifs_assert(c, ret < 0); |
856 | ubifs_assert(c, ret != -ENOSPC && ret != -EAGAIN); |
857 | ubifs_wbuf_sync_nolock(wbuf); |
858 | ubifs_ro_mode(c, err: ret); |
859 | mutex_unlock(lock: &wbuf->io_mutex); |
860 | if (lp.lnum != -1) |
861 | ubifs_return_leb(c, lnum: lp.lnum); |
862 | return ret; |
863 | } |
864 | |
865 | /** |
866 | * ubifs_gc_start_commit - garbage collection at start of commit. |
867 | * @c: UBIFS file-system description object |
868 | * |
869 | * If a LEB has only dirty and free space, then we may safely unmap it and make |
870 | * it free. Note, we cannot do this with indexing LEBs because dirty space may |
871 | * correspond index nodes that are required for recovery. In that case, the |
872 | * LEB cannot be unmapped until after the next commit. |
873 | * |
874 | * This function returns %0 upon success and a negative error code upon failure. |
875 | */ |
876 | int ubifs_gc_start_commit(struct ubifs_info *c) |
877 | { |
878 | struct ubifs_gced_idx_leb *idx_gc; |
879 | const struct ubifs_lprops *lp; |
880 | int err = 0, flags; |
881 | |
882 | ubifs_get_lprops(c); |
883 | |
884 | /* |
885 | * Unmap (non-index) freeable LEBs. Note that recovery requires that all |
886 | * wbufs are sync'd before this, which is done in 'do_commit()'. |
887 | */ |
888 | while (1) { |
889 | lp = ubifs_fast_find_freeable(c); |
890 | if (!lp) |
891 | break; |
892 | ubifs_assert(c, !(lp->flags & LPROPS_TAKEN)); |
893 | ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
894 | err = ubifs_leb_unmap(c, lnum: lp->lnum); |
895 | if (err) |
896 | goto out; |
897 | lp = ubifs_change_lp(c, lp, free: c->leb_size, dirty: 0, flags: lp->flags, idx_gc_cnt: 0); |
898 | if (IS_ERR(ptr: lp)) { |
899 | err = PTR_ERR(ptr: lp); |
900 | goto out; |
901 | } |
902 | ubifs_assert(c, !(lp->flags & LPROPS_TAKEN)); |
903 | ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
904 | } |
905 | |
906 | /* Mark GC'd index LEBs OK to unmap after this commit finishes */ |
907 | list_for_each_entry(idx_gc, &c->idx_gc, list) |
908 | idx_gc->unmap = 1; |
909 | |
910 | /* Record index freeable LEBs for unmapping after commit */ |
911 | while (1) { |
912 | lp = ubifs_fast_find_frdi_idx(c); |
913 | if (IS_ERR(ptr: lp)) { |
914 | err = PTR_ERR(ptr: lp); |
915 | goto out; |
916 | } |
917 | if (!lp) |
918 | break; |
919 | idx_gc = kmalloc(size: sizeof(struct ubifs_gced_idx_leb), GFP_NOFS); |
920 | if (!idx_gc) { |
921 | err = -ENOMEM; |
922 | goto out; |
923 | } |
924 | ubifs_assert(c, !(lp->flags & LPROPS_TAKEN)); |
925 | ubifs_assert(c, lp->flags & LPROPS_INDEX); |
926 | /* Don't release the LEB until after the next commit */ |
927 | flags = (lp->flags | LPROPS_TAKEN) ^ LPROPS_INDEX; |
928 | lp = ubifs_change_lp(c, lp, free: c->leb_size, dirty: 0, flags, idx_gc_cnt: 1); |
929 | if (IS_ERR(ptr: lp)) { |
930 | err = PTR_ERR(ptr: lp); |
931 | kfree(objp: idx_gc); |
932 | goto out; |
933 | } |
934 | ubifs_assert(c, lp->flags & LPROPS_TAKEN); |
935 | ubifs_assert(c, !(lp->flags & LPROPS_INDEX)); |
936 | idx_gc->lnum = lp->lnum; |
937 | idx_gc->unmap = 1; |
938 | list_add(new: &idx_gc->list, head: &c->idx_gc); |
939 | } |
940 | out: |
941 | ubifs_release_lprops(c); |
942 | return err; |
943 | } |
944 | |
945 | /** |
946 | * ubifs_gc_end_commit - garbage collection at end of commit. |
947 | * @c: UBIFS file-system description object |
948 | * |
949 | * This function completes out-of-place garbage collection of index LEBs. |
950 | */ |
951 | int ubifs_gc_end_commit(struct ubifs_info *c) |
952 | { |
953 | struct ubifs_gced_idx_leb *idx_gc, *tmp; |
954 | struct ubifs_wbuf *wbuf; |
955 | int err = 0; |
956 | |
957 | wbuf = &c->jheads[GCHD].wbuf; |
958 | mutex_lock_nested(lock: &wbuf->io_mutex, subclass: wbuf->jhead); |
959 | list_for_each_entry_safe(idx_gc, tmp, &c->idx_gc, list) |
960 | if (idx_gc->unmap) { |
961 | dbg_gc("LEB %d" , idx_gc->lnum); |
962 | err = ubifs_leb_unmap(c, lnum: idx_gc->lnum); |
963 | if (err) |
964 | goto out; |
965 | err = ubifs_change_one_lp(c, lnum: idx_gc->lnum, LPROPS_NC, |
966 | LPROPS_NC, flags_set: 0, flags_clean: LPROPS_TAKEN, idx_gc_cnt: -1); |
967 | if (err) |
968 | goto out; |
969 | list_del(entry: &idx_gc->list); |
970 | kfree(objp: idx_gc); |
971 | } |
972 | out: |
973 | mutex_unlock(lock: &wbuf->io_mutex); |
974 | return err; |
975 | } |
976 | |
977 | /** |
978 | * ubifs_destroy_idx_gc - destroy idx_gc list. |
979 | * @c: UBIFS file-system description object |
980 | * |
981 | * This function destroys the @c->idx_gc list. It is called when unmounting |
982 | * so locks are not needed. Returns zero in case of success and a negative |
983 | * error code in case of failure. |
984 | */ |
985 | void ubifs_destroy_idx_gc(struct ubifs_info *c) |
986 | { |
987 | while (!list_empty(head: &c->idx_gc)) { |
988 | struct ubifs_gced_idx_leb *idx_gc; |
989 | |
990 | idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, |
991 | list); |
992 | c->idx_gc_cnt -= 1; |
993 | list_del(entry: &idx_gc->list); |
994 | kfree(objp: idx_gc); |
995 | } |
996 | } |
997 | |
998 | /** |
999 | * ubifs_get_idx_gc_leb - get a LEB from GC'd index LEB list. |
1000 | * @c: UBIFS file-system description object |
1001 | * |
1002 | * Called during start commit so locks are not needed. |
1003 | */ |
1004 | int ubifs_get_idx_gc_leb(struct ubifs_info *c) |
1005 | { |
1006 | struct ubifs_gced_idx_leb *idx_gc; |
1007 | int lnum; |
1008 | |
1009 | if (list_empty(head: &c->idx_gc)) |
1010 | return -ENOSPC; |
1011 | idx_gc = list_entry(c->idx_gc.next, struct ubifs_gced_idx_leb, list); |
1012 | lnum = idx_gc->lnum; |
1013 | /* c->idx_gc_cnt is updated by the caller when lprops are updated */ |
1014 | list_del(entry: &idx_gc->list); |
1015 | kfree(objp: idx_gc); |
1016 | return lnum; |
1017 | } |
1018 | |