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1 | /* -*- mode: c; c-basic-offset: 8; -*- |
2 | * vim: noexpandtab sw=8 ts=8 sts=0: | |
3 | * | |
4 | * reservations.c | |
5 | * | |
6 | * Allocation reservations implementation | |
7 | * | |
8 | * Some code borrowed from fs/ext3/balloc.c and is: | |
9 | * | |
10 | * Copyright (C) 1992, 1993, 1994, 1995 | |
11 | * Remy Card (card@masi.ibp.fr) | |
12 | * Laboratoire MASI - Institut Blaise Pascal | |
13 | * Universite Pierre et Marie Curie (Paris VI) | |
14 | * | |
15 | * The rest is copyright (C) 2010 Novell. All rights reserved. | |
16 | * | |
17 | * This program is free software; you can redistribute it and/or | |
18 | * modify it under the terms of the GNU General Public | |
19 | * License version 2 as published by the Free Software Foundation. | |
20 | * | |
21 | * This program is distributed in the hope that it will be useful, | |
22 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
23 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
24 | * General Public License for more details. | |
25 | */ | |
26 | ||
27 | #include <linux/fs.h> | |
28 | #include <linux/types.h> | |
29 | #include <linux/slab.h> | |
30 | #include <linux/highmem.h> | |
31 | #include <linux/bitops.h> | |
32 | #include <linux/list.h> | |
33 | ||
34 | #define MLOG_MASK_PREFIX ML_RESERVATIONS | |
35 | #include <cluster/masklog.h> | |
36 | ||
37 | #include "ocfs2.h" | |
38 | ||
39 | #ifdef CONFIG_OCFS2_DEBUG_FS | |
40 | #define OCFS2_CHECK_RESERVATIONS | |
41 | #endif | |
42 | ||
43 | DEFINE_SPINLOCK(resv_lock); | |
44 | ||
45 | #define OCFS2_MIN_RESV_WINDOW_BITS 8 | |
46 | #define OCFS2_MAX_RESV_WINDOW_BITS 1024 | |
47 | ||
48 | static unsigned int ocfs2_resv_window_bits(struct ocfs2_reservation_map *resmap, | |
49 | struct ocfs2_alloc_reservation *resv) | |
50 | { | |
51 | struct ocfs2_super *osb = resmap->m_osb; | |
52 | unsigned int bits; | |
53 | ||
54 | /* 8, 16, 32, 64, 128, 256, 512, 1024 */ | |
55 | bits = 4 << osb->osb_resv_level; | |
56 | ||
57 | return bits; | |
58 | } | |
59 | ||
60 | static inline unsigned int ocfs2_resv_end(struct ocfs2_alloc_reservation *resv) | |
61 | { | |
62 | if (resv->r_len) | |
63 | return resv->r_start + resv->r_len - 1; | |
64 | return resv->r_start; | |
65 | } | |
66 | ||
67 | static inline int ocfs2_resv_empty(struct ocfs2_alloc_reservation *resv) | |
68 | { | |
69 | return !!(resv->r_len == 0); | |
70 | } | |
71 | ||
72 | static inline int ocfs2_resmap_disabled(struct ocfs2_reservation_map *resmap) | |
73 | { | |
74 | if (resmap->m_osb->osb_resv_level == 0) | |
75 | return 1; | |
76 | return 0; | |
77 | } | |
78 | ||
79 | static void ocfs2_dump_resv(struct ocfs2_reservation_map *resmap) | |
80 | { | |
81 | struct ocfs2_super *osb = resmap->m_osb; | |
82 | struct rb_node *node; | |
83 | struct ocfs2_alloc_reservation *resv; | |
84 | int i = 0; | |
85 | ||
86 | mlog(ML_NOTICE, "Dumping resmap for device %s. Bitmap length: %u\n", | |
87 | osb->dev_str, resmap->m_bitmap_len); | |
88 | ||
89 | node = rb_first(&resmap->m_reservations); | |
90 | while (node) { | |
91 | resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); | |
92 | ||
93 | mlog(ML_NOTICE, "start: %u\tend: %u\tlen: %u\tlast_start: %u" | |
94 | "\tlast_len: %u\n", resv->r_start, | |
95 | ocfs2_resv_end(resv), resv->r_len, resv->r_last_start, | |
96 | resv->r_last_len); | |
97 | ||
98 | node = rb_next(node); | |
99 | i++; | |
100 | } | |
101 | ||
102 | mlog(ML_NOTICE, "%d reservations found. LRU follows\n", i); | |
103 | ||
104 | i = 0; | |
105 | list_for_each_entry(resv, &resmap->m_lru, r_lru) { | |
106 | mlog(ML_NOTICE, "LRU(%d) start: %u\tend: %u\tlen: %u\t" | |
107 | "last_start: %u\tlast_len: %u\n", i, resv->r_start, | |
108 | ocfs2_resv_end(resv), resv->r_len, resv->r_last_start, | |
109 | resv->r_last_len); | |
110 | ||
111 | i++; | |
112 | } | |
113 | } | |
114 | ||
115 | #ifdef OCFS2_CHECK_RESERVATIONS | |
116 | static int ocfs2_validate_resmap_bits(struct ocfs2_reservation_map *resmap, | |
117 | int i, | |
118 | struct ocfs2_alloc_reservation *resv) | |
119 | { | |
120 | char *disk_bitmap = resmap->m_disk_bitmap; | |
121 | unsigned int start = resv->r_start; | |
122 | unsigned int end = ocfs2_resv_end(resv); | |
123 | ||
124 | while (start <= end) { | |
125 | if (ocfs2_test_bit(start, disk_bitmap)) { | |
126 | mlog(ML_ERROR, | |
127 | "reservation %d covers an allocated area " | |
128 | "starting at bit %u!\n", i, start); | |
129 | return 1; | |
130 | } | |
131 | ||
132 | start++; | |
133 | } | |
134 | return 0; | |
135 | } | |
136 | ||
137 | static void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap) | |
138 | { | |
139 | unsigned int off = 0; | |
140 | int i = 0; | |
141 | struct rb_node *node; | |
142 | struct ocfs2_alloc_reservation *resv; | |
143 | ||
144 | node = rb_first(&resmap->m_reservations); | |
145 | while (node) { | |
146 | resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); | |
147 | ||
148 | if (i > 0 && resv->r_start <= off) { | |
149 | mlog(ML_ERROR, "reservation %d has bad start off!\n", | |
150 | i); | |
151 | goto bad; | |
152 | } | |
153 | ||
154 | if (resv->r_len == 0) { | |
155 | mlog(ML_ERROR, "reservation %d has no length!\n", | |
156 | i); | |
157 | goto bad; | |
158 | } | |
159 | ||
160 | if (resv->r_start > ocfs2_resv_end(resv)) { | |
161 | mlog(ML_ERROR, "reservation %d has invalid range!\n", | |
162 | i); | |
163 | goto bad; | |
164 | } | |
165 | ||
166 | if (ocfs2_resv_end(resv) >= resmap->m_bitmap_len) { | |
167 | mlog(ML_ERROR, "reservation %d extends past bitmap!\n", | |
168 | i); | |
169 | goto bad; | |
170 | } | |
171 | ||
172 | if (ocfs2_validate_resmap_bits(resmap, i, resv)) | |
173 | goto bad; | |
174 | ||
175 | off = ocfs2_resv_end(resv); | |
176 | node = rb_next(node); | |
177 | ||
178 | i++; | |
179 | } | |
180 | return; | |
181 | ||
182 | bad: | |
183 | ocfs2_dump_resv(resmap); | |
184 | BUG(); | |
185 | } | |
186 | #else | |
187 | static inline void ocfs2_check_resmap(struct ocfs2_reservation_map *resmap) | |
188 | { | |
189 | ||
190 | } | |
191 | #endif | |
192 | ||
193 | void ocfs2_resv_init_once(struct ocfs2_alloc_reservation *resv) | |
194 | { | |
195 | memset(resv, 0, sizeof(*resv)); | |
196 | INIT_LIST_HEAD(&resv->r_lru); | |
197 | } | |
198 | ||
199 | void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv, | |
200 | unsigned int flags) | |
201 | { | |
202 | BUG_ON(flags & ~OCFS2_RESV_TYPES); | |
203 | ||
204 | resv->r_flags |= flags; | |
205 | } | |
206 | ||
207 | int ocfs2_resmap_init(struct ocfs2_super *osb, | |
208 | struct ocfs2_reservation_map *resmap) | |
209 | { | |
210 | memset(resmap, 0, sizeof(*resmap)); | |
211 | ||
212 | resmap->m_osb = osb; | |
213 | resmap->m_reservations = RB_ROOT; | |
214 | /* m_bitmap_len is initialized to zero by the above memset. */ | |
215 | INIT_LIST_HEAD(&resmap->m_lru); | |
216 | ||
217 | return 0; | |
218 | } | |
219 | ||
220 | static void ocfs2_resv_mark_lru(struct ocfs2_reservation_map *resmap, | |
221 | struct ocfs2_alloc_reservation *resv) | |
222 | { | |
223 | assert_spin_locked(&resv_lock); | |
224 | ||
225 | if (!list_empty(&resv->r_lru)) | |
226 | list_del_init(&resv->r_lru); | |
227 | ||
228 | list_add_tail(&resv->r_lru, &resmap->m_lru); | |
229 | } | |
230 | ||
231 | static void __ocfs2_resv_trunc(struct ocfs2_alloc_reservation *resv) | |
232 | { | |
233 | resv->r_len = 0; | |
234 | resv->r_start = 0; | |
235 | } | |
236 | ||
237 | static void ocfs2_resv_remove(struct ocfs2_reservation_map *resmap, | |
238 | struct ocfs2_alloc_reservation *resv) | |
239 | { | |
240 | if (resv->r_flags & OCFS2_RESV_FLAG_INUSE) { | |
241 | list_del_init(&resv->r_lru); | |
242 | rb_erase(&resv->r_node, &resmap->m_reservations); | |
243 | resv->r_flags &= ~OCFS2_RESV_FLAG_INUSE; | |
244 | } | |
245 | } | |
246 | ||
247 | static void __ocfs2_resv_discard(struct ocfs2_reservation_map *resmap, | |
248 | struct ocfs2_alloc_reservation *resv) | |
249 | { | |
250 | assert_spin_locked(&resv_lock); | |
251 | ||
252 | __ocfs2_resv_trunc(resv); | |
253 | /* | |
254 | * last_len and last_start no longer make sense if | |
255 | * we're changing the range of our allocations. | |
256 | */ | |
257 | resv->r_last_len = resv->r_last_start = 0; | |
258 | ||
259 | ocfs2_resv_remove(resmap, resv); | |
260 | } | |
261 | ||
262 | /* does nothing if 'resv' is null */ | |
263 | void ocfs2_resv_discard(struct ocfs2_reservation_map *resmap, | |
264 | struct ocfs2_alloc_reservation *resv) | |
265 | { | |
266 | if (resv) { | |
267 | spin_lock(&resv_lock); | |
268 | __ocfs2_resv_discard(resmap, resv); | |
269 | spin_unlock(&resv_lock); | |
270 | } | |
271 | } | |
272 | ||
273 | static void ocfs2_resmap_clear_all_resv(struct ocfs2_reservation_map *resmap) | |
274 | { | |
275 | struct rb_node *node; | |
276 | struct ocfs2_alloc_reservation *resv; | |
277 | ||
278 | assert_spin_locked(&resv_lock); | |
279 | ||
280 | while ((node = rb_last(&resmap->m_reservations)) != NULL) { | |
281 | resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); | |
282 | ||
283 | __ocfs2_resv_discard(resmap, resv); | |
284 | } | |
285 | } | |
286 | ||
287 | void ocfs2_resmap_restart(struct ocfs2_reservation_map *resmap, | |
288 | unsigned int clen, char *disk_bitmap) | |
289 | { | |
290 | if (ocfs2_resmap_disabled(resmap)) | |
291 | return; | |
292 | ||
293 | spin_lock(&resv_lock); | |
294 | ||
295 | ocfs2_resmap_clear_all_resv(resmap); | |
296 | resmap->m_bitmap_len = clen; | |
297 | resmap->m_disk_bitmap = disk_bitmap; | |
298 | ||
299 | spin_unlock(&resv_lock); | |
300 | } | |
301 | ||
302 | void ocfs2_resmap_uninit(struct ocfs2_reservation_map *resmap) | |
303 | { | |
304 | /* Does nothing for now. Keep this around for API symmetry */ | |
305 | } | |
306 | ||
307 | static void ocfs2_resv_insert(struct ocfs2_reservation_map *resmap, | |
308 | struct ocfs2_alloc_reservation *new) | |
309 | { | |
310 | struct rb_root *root = &resmap->m_reservations; | |
311 | struct rb_node *parent = NULL; | |
312 | struct rb_node **p = &root->rb_node; | |
313 | struct ocfs2_alloc_reservation *tmp; | |
314 | ||
315 | assert_spin_locked(&resv_lock); | |
316 | ||
317 | mlog(0, "Insert reservation start: %u len: %u\n", new->r_start, | |
318 | new->r_len); | |
319 | ||
320 | while (*p) { | |
321 | parent = *p; | |
322 | ||
323 | tmp = rb_entry(parent, struct ocfs2_alloc_reservation, r_node); | |
324 | ||
325 | if (new->r_start < tmp->r_start) { | |
326 | p = &(*p)->rb_left; | |
327 | ||
328 | /* | |
329 | * This is a good place to check for | |
330 | * overlapping reservations. | |
331 | */ | |
332 | BUG_ON(ocfs2_resv_end(new) >= tmp->r_start); | |
333 | } else if (new->r_start > ocfs2_resv_end(tmp)) { | |
334 | p = &(*p)->rb_right; | |
335 | } else { | |
336 | /* This should never happen! */ | |
337 | mlog(ML_ERROR, "Duplicate reservation window!\n"); | |
338 | BUG(); | |
339 | } | |
340 | } | |
341 | ||
342 | rb_link_node(&new->r_node, parent, p); | |
343 | rb_insert_color(&new->r_node, root); | |
344 | new->r_flags |= OCFS2_RESV_FLAG_INUSE; | |
345 | ||
346 | ocfs2_resv_mark_lru(resmap, new); | |
347 | ||
348 | ocfs2_check_resmap(resmap); | |
349 | } | |
350 | ||
351 | /** | |
352 | * ocfs2_find_resv_lhs() - find the window which contains goal | |
353 | * @resmap: reservation map to search | |
354 | * @goal: which bit to search for | |
355 | * | |
356 | * If a window containing that goal is not found, we return the window | |
357 | * which comes before goal. Returns NULL on empty rbtree or no window | |
358 | * before goal. | |
359 | */ | |
360 | static struct ocfs2_alloc_reservation * | |
361 | ocfs2_find_resv_lhs(struct ocfs2_reservation_map *resmap, unsigned int goal) | |
362 | { | |
363 | struct ocfs2_alloc_reservation *resv = NULL; | |
364 | struct ocfs2_alloc_reservation *prev_resv = NULL; | |
365 | struct rb_node *node = resmap->m_reservations.rb_node; | |
366 | struct rb_node *prev = NULL; | |
367 | ||
368 | assert_spin_locked(&resv_lock); | |
369 | ||
370 | if (!node) | |
371 | return NULL; | |
372 | ||
373 | node = rb_first(&resmap->m_reservations); | |
374 | while (node) { | |
375 | resv = rb_entry(node, struct ocfs2_alloc_reservation, r_node); | |
376 | ||
377 | if (resv->r_start <= goal && ocfs2_resv_end(resv) >= goal) | |
378 | break; | |
379 | ||
380 | /* Check if we overshot the reservation just before goal? */ | |
381 | if (resv->r_start > goal) { | |
382 | resv = prev_resv; | |
383 | break; | |
384 | } | |
385 | ||
386 | prev_resv = resv; | |
387 | prev = node; | |
388 | node = rb_next(node); | |
389 | } | |
390 | ||
391 | return resv; | |
392 | } | |
393 | ||
394 | /* | |
395 | * We are given a range within the bitmap, which corresponds to a gap | |
396 | * inside the reservations tree (search_start, search_len). The range | |
397 | * can be anything from the whole bitmap, to a gap between | |
398 | * reservations. | |
399 | * | |
400 | * The start value of *rstart is insignificant. | |
401 | * | |
402 | * This function searches the bitmap range starting at search_start | |
403 | * with length csearch_len for a set of contiguous free bits. We try | |
404 | * to find up to 'wanted' bits, but can sometimes return less. | |
405 | * | |
406 | * Returns the length of allocation, 0 if no free bits are found. | |
407 | * | |
408 | * *cstart and *clen will also be populated with the result. | |
409 | */ | |
410 | static int ocfs2_resmap_find_free_bits(struct ocfs2_reservation_map *resmap, | |
411 | unsigned int wanted, | |
412 | unsigned int search_start, | |
413 | unsigned int search_len, | |
414 | unsigned int *rstart, | |
415 | unsigned int *rlen) | |
416 | { | |
417 | void *bitmap = resmap->m_disk_bitmap; | |
418 | unsigned int best_start, best_len = 0; | |
419 | int offset, start, found; | |
420 | ||
421 | mlog(0, "Find %u bits within range (%u, len %u) resmap len: %u\n", | |
422 | wanted, search_start, search_len, resmap->m_bitmap_len); | |
423 | ||
424 | found = best_start = best_len = 0; | |
425 | ||
426 | start = search_start; | |
427 | while ((offset = ocfs2_find_next_zero_bit(bitmap, resmap->m_bitmap_len, | |
428 | start)) != -1) { | |
429 | /* Search reached end of the region */ | |
430 | if (offset >= (search_start + search_len)) | |
431 | break; | |
432 | ||
433 | if (offset == start) { | |
434 | /* we found a zero */ | |
435 | found++; | |
436 | /* move start to the next bit to test */ | |
437 | start++; | |
438 | } else { | |
439 | /* got a zero after some ones */ | |
440 | found = 1; | |
441 | start = offset + 1; | |
442 | } | |
443 | if (found > best_len) { | |
444 | best_len = found; | |
445 | best_start = start - found; | |
446 | } | |
447 | ||
448 | if (found >= wanted) | |
449 | break; | |
450 | } | |
451 | ||
452 | if (best_len == 0) | |
453 | return 0; | |
454 | ||
455 | if (best_len >= wanted) | |
456 | best_len = wanted; | |
457 | ||
458 | *rlen = best_len; | |
459 | *rstart = best_start; | |
460 | ||
461 | mlog(0, "Found start: %u len: %u\n", best_start, best_len); | |
462 | ||
463 | return *rlen; | |
464 | } | |
465 | ||
466 | static void __ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap, | |
467 | struct ocfs2_alloc_reservation *resv, | |
468 | unsigned int goal, unsigned int wanted) | |
469 | { | |
470 | struct rb_root *root = &resmap->m_reservations; | |
471 | unsigned int gap_start, gap_end, gap_len; | |
472 | struct ocfs2_alloc_reservation *prev_resv, *next_resv; | |
473 | struct rb_node *prev, *next; | |
474 | unsigned int cstart, clen; | |
475 | unsigned int best_start = 0, best_len = 0; | |
476 | ||
477 | /* | |
478 | * Nasty cases to consider: | |
479 | * | |
480 | * - rbtree is empty | |
481 | * - our window should be first in all reservations | |
482 | * - our window should be last in all reservations | |
483 | * - need to make sure we don't go past end of bitmap | |
484 | */ | |
485 | ||
486 | mlog(0, "resv start: %u resv end: %u goal: %u wanted: %u\n", | |
487 | resv->r_start, ocfs2_resv_end(resv), goal, wanted); | |
488 | ||
489 | assert_spin_locked(&resv_lock); | |
490 | ||
491 | if (RB_EMPTY_ROOT(root)) { | |
492 | /* | |
493 | * Easiest case - empty tree. We can just take | |
494 | * whatever window of free bits we want. | |
495 | */ | |
496 | ||
497 | mlog(0, "Empty root\n"); | |
498 | ||
499 | clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal, | |
500 | resmap->m_bitmap_len - goal, | |
501 | &cstart, &clen); | |
502 | ||
503 | /* | |
504 | * This should never happen - the local alloc window | |
505 | * will always have free bits when we're called. | |
506 | */ | |
507 | BUG_ON(goal == 0 && clen == 0); | |
508 | ||
509 | if (clen == 0) | |
510 | return; | |
511 | ||
512 | resv->r_start = cstart; | |
513 | resv->r_len = clen; | |
514 | ||
515 | ocfs2_resv_insert(resmap, resv); | |
516 | return; | |
517 | } | |
518 | ||
519 | prev_resv = ocfs2_find_resv_lhs(resmap, goal); | |
520 | ||
521 | if (prev_resv == NULL) { | |
522 | mlog(0, "Goal on LHS of leftmost window\n"); | |
523 | ||
524 | /* | |
525 | * A NULL here means that the search code couldn't | |
526 | * find a window that starts before goal. | |
527 | * | |
528 | * However, we can take the first window after goal, | |
529 | * which is also by definition, the leftmost window in | |
530 | * the entire tree. If we can find free bits in the | |
531 | * gap between goal and the LHS window, then the | |
532 | * reservation can safely be placed there. | |
533 | * | |
534 | * Otherwise we fall back to a linear search, checking | |
535 | * the gaps in between windows for a place to | |
536 | * allocate. | |
537 | */ | |
538 | ||
539 | next = rb_first(root); | |
540 | next_resv = rb_entry(next, struct ocfs2_alloc_reservation, | |
541 | r_node); | |
542 | ||
543 | /* | |
544 | * The search should never return such a window. (see | |
545 | * comment above | |
546 | */ | |
547 | if (next_resv->r_start <= goal) { | |
548 | mlog(ML_ERROR, "goal: %u next_resv: start %u len %u\n", | |
549 | goal, next_resv->r_start, next_resv->r_len); | |
550 | ocfs2_dump_resv(resmap); | |
551 | BUG(); | |
552 | } | |
553 | ||
554 | clen = ocfs2_resmap_find_free_bits(resmap, wanted, goal, | |
555 | next_resv->r_start - goal, | |
556 | &cstart, &clen); | |
557 | if (clen) { | |
558 | best_len = clen; | |
559 | best_start = cstart; | |
560 | if (best_len == wanted) | |
561 | goto out_insert; | |
562 | } | |
563 | ||
564 | prev_resv = next_resv; | |
565 | next_resv = NULL; | |
566 | } | |
567 | ||
568 | prev = &prev_resv->r_node; | |
569 | ||
570 | /* Now we do a linear search for a window, starting at 'prev_rsv' */ | |
571 | while (1) { | |
572 | next = rb_next(prev); | |
573 | if (next) { | |
574 | mlog(0, "One more resv found in linear search\n"); | |
575 | next_resv = rb_entry(next, | |
576 | struct ocfs2_alloc_reservation, | |
577 | r_node); | |
578 | ||
579 | gap_start = ocfs2_resv_end(prev_resv) + 1; | |
580 | gap_end = next_resv->r_start - 1; | |
581 | gap_len = gap_end - gap_start + 1; | |
582 | } else { | |
583 | mlog(0, "No next node\n"); | |
584 | /* | |
585 | * We're at the rightmost edge of the | |
586 | * tree. See if a reservation between this | |
587 | * window and the end of the bitmap will work. | |
588 | */ | |
589 | gap_start = ocfs2_resv_end(prev_resv) + 1; | |
590 | gap_len = resmap->m_bitmap_len - gap_start; | |
591 | gap_end = resmap->m_bitmap_len - 1; | |
592 | } | |
593 | ||
594 | /* | |
595 | * No need to check this gap if we have already found | |
596 | * a larger region of free bits. | |
597 | */ | |
598 | if (gap_len <= best_len) | |
599 | goto next_resv; | |
600 | ||
601 | clen = ocfs2_resmap_find_free_bits(resmap, wanted, gap_start, | |
602 | gap_len, &cstart, &clen); | |
603 | if (clen == wanted) { | |
604 | best_len = clen; | |
605 | best_start = cstart; | |
606 | goto out_insert; | |
607 | } else if (clen > best_len) { | |
608 | best_len = clen; | |
609 | best_start = cstart; | |
610 | } | |
611 | ||
612 | next_resv: | |
613 | if (!next) | |
614 | break; | |
615 | ||
616 | prev = next; | |
617 | prev_resv = rb_entry(prev, struct ocfs2_alloc_reservation, | |
618 | r_node); | |
619 | } | |
620 | ||
621 | out_insert: | |
622 | if (best_len) { | |
623 | resv->r_start = best_start; | |
624 | resv->r_len = best_len; | |
625 | ocfs2_resv_insert(resmap, resv); | |
626 | } | |
627 | } | |
628 | ||
629 | static void ocfs2_cannibalize_resv(struct ocfs2_reservation_map *resmap, | |
630 | struct ocfs2_alloc_reservation *resv, | |
631 | unsigned int wanted) | |
632 | { | |
633 | struct ocfs2_alloc_reservation *lru_resv; | |
634 | int tmpwindow = !!(resv->r_flags & OCFS2_RESV_FLAG_TMP); | |
635 | unsigned int min_bits; | |
636 | ||
637 | if (!tmpwindow) | |
638 | min_bits = ocfs2_resv_window_bits(resmap, resv) >> 1; | |
639 | else | |
640 | min_bits = wanted; /* We at know the temp window will use all | |
641 | * of these bits */ | |
642 | ||
643 | /* | |
644 | * Take the first reservation off the LRU as our 'target'. We | |
645 | * don't try to be smart about it. There might be a case for | |
646 | * searching based on size but I don't have enough data to be | |
647 | * sure. --Mark (3/16/2010) | |
648 | */ | |
649 | lru_resv = list_first_entry(&resmap->m_lru, | |
650 | struct ocfs2_alloc_reservation, r_lru); | |
651 | ||
652 | mlog(0, "lru resv: start: %u len: %u end: %u\n", lru_resv->r_start, | |
653 | lru_resv->r_len, ocfs2_resv_end(lru_resv)); | |
654 | ||
655 | /* | |
656 | * Cannibalize (some or all) of the target reservation and | |
657 | * feed it to the current window. | |
658 | */ | |
659 | if (lru_resv->r_len <= min_bits) { | |
660 | /* | |
661 | * Discard completely if size is less than or equal to a | |
662 | * reasonable threshold - 50% of window bits for non temporary | |
663 | * windows. | |
664 | */ | |
665 | resv->r_start = lru_resv->r_start; | |
666 | resv->r_len = lru_resv->r_len; | |
667 | ||
668 | __ocfs2_resv_discard(resmap, lru_resv); | |
669 | } else { | |
670 | unsigned int shrink; | |
671 | if (tmpwindow) | |
672 | shrink = min_bits; | |
673 | else | |
674 | shrink = lru_resv->r_len / 2; | |
675 | ||
676 | lru_resv->r_len -= shrink; | |
677 | ||
678 | resv->r_start = ocfs2_resv_end(lru_resv) + 1; | |
679 | resv->r_len = shrink; | |
680 | } | |
681 | ||
682 | mlog(0, "Reservation now looks like: r_start: %u r_end: %u " | |
683 | "r_len: %u r_last_start: %u r_last_len: %u\n", | |
684 | resv->r_start, ocfs2_resv_end(resv), resv->r_len, | |
685 | resv->r_last_start, resv->r_last_len); | |
686 | ||
687 | ocfs2_resv_insert(resmap, resv); | |
688 | } | |
689 | ||
690 | static void ocfs2_resv_find_window(struct ocfs2_reservation_map *resmap, | |
691 | struct ocfs2_alloc_reservation *resv, | |
692 | unsigned int wanted) | |
693 | { | |
694 | unsigned int goal = 0; | |
695 | ||
696 | BUG_ON(!ocfs2_resv_empty(resv)); | |
697 | ||
698 | /* | |
699 | * Begin by trying to get a window as close to the previous | |
700 | * one as possible. Using the most recent allocation as a | |
701 | * start goal makes sense. | |
702 | */ | |
703 | if (resv->r_last_len) { | |
704 | goal = resv->r_last_start + resv->r_last_len; | |
705 | if (goal >= resmap->m_bitmap_len) | |
706 | goal = 0; | |
707 | } | |
708 | ||
709 | __ocfs2_resv_find_window(resmap, resv, goal, wanted); | |
710 | ||
711 | /* Search from last alloc didn't work, try once more from beginning. */ | |
712 | if (ocfs2_resv_empty(resv) && goal != 0) | |
713 | __ocfs2_resv_find_window(resmap, resv, 0, wanted); | |
714 | ||
715 | if (ocfs2_resv_empty(resv)) { | |
716 | /* | |
717 | * Still empty? Pull oldest one off the LRU, remove it from | |
718 | * tree, put this one in it's place. | |
719 | */ | |
720 | ocfs2_cannibalize_resv(resmap, resv, wanted); | |
721 | } | |
722 | ||
723 | BUG_ON(ocfs2_resv_empty(resv)); | |
724 | } | |
725 | ||
726 | int ocfs2_resmap_resv_bits(struct ocfs2_reservation_map *resmap, | |
727 | struct ocfs2_alloc_reservation *resv, | |
728 | int *cstart, int *clen) | |
729 | { | |
730 | unsigned int wanted = *clen; | |
731 | ||
732 | if (resv == NULL || ocfs2_resmap_disabled(resmap)) | |
733 | return -ENOSPC; | |
734 | ||
735 | spin_lock(&resv_lock); | |
736 | ||
737 | /* | |
738 | * We don't want to over-allocate for temporary | |
739 | * windows. Otherwise, we run the risk of fragmenting the | |
740 | * allocation space. | |
741 | */ | |
742 | wanted = ocfs2_resv_window_bits(resmap, resv); | |
743 | if ((resv->r_flags & OCFS2_RESV_FLAG_TMP) || wanted < *clen) | |
744 | wanted = *clen; | |
745 | ||
746 | if (ocfs2_resv_empty(resv)) { | |
747 | mlog(0, "empty reservation, find new window\n"); | |
748 | ||
749 | /* | |
750 | * Try to get a window here. If it works, we must fall | |
751 | * through and test the bitmap . This avoids some | |
752 | * ping-ponging of windows due to non-reserved space | |
753 | * being allocation before we initialize a window for | |
754 | * that inode. | |
755 | */ | |
756 | ocfs2_resv_find_window(resmap, resv, wanted); | |
757 | } | |
758 | ||
759 | BUG_ON(ocfs2_resv_empty(resv)); | |
760 | ||
761 | *cstart = resv->r_start; | |
762 | *clen = resv->r_len; | |
763 | ||
764 | spin_unlock(&resv_lock); | |
765 | return 0; | |
766 | } | |
767 | ||
768 | static void | |
769 | ocfs2_adjust_resv_from_alloc(struct ocfs2_reservation_map *resmap, | |
770 | struct ocfs2_alloc_reservation *resv, | |
771 | unsigned int start, unsigned int end) | |
772 | { | |
773 | unsigned int lhs = 0, rhs = 0; | |
774 | ||
775 | BUG_ON(start < resv->r_start); | |
776 | ||
777 | /* | |
778 | * Completely used? We can remove it then. | |
779 | */ | |
780 | if (ocfs2_resv_end(resv) <= end && resv->r_start >= start) { | |
781 | __ocfs2_resv_discard(resmap, resv); | |
782 | return; | |
783 | } | |
784 | ||
785 | if (end < ocfs2_resv_end(resv)) | |
786 | rhs = end - ocfs2_resv_end(resv); | |
787 | ||
788 | if (start > resv->r_start) | |
789 | lhs = start - resv->r_start; | |
790 | ||
791 | /* | |
792 | * This should have been trapped above. At the very least, rhs | |
793 | * should be non zero. | |
794 | */ | |
795 | BUG_ON(rhs == 0 && lhs == 0); | |
796 | ||
797 | if (rhs >= lhs) { | |
798 | unsigned int old_end = ocfs2_resv_end(resv); | |
799 | ||
800 | resv->r_start = end + 1; | |
801 | resv->r_len = old_end - resv->r_start + 1; | |
802 | } else { | |
803 | resv->r_len = start - resv->r_start; | |
804 | } | |
805 | } | |
806 | ||
807 | void ocfs2_resmap_claimed_bits(struct ocfs2_reservation_map *resmap, | |
808 | struct ocfs2_alloc_reservation *resv, | |
809 | u32 cstart, u32 clen) | |
810 | { | |
811 | unsigned int cend = cstart + clen - 1; | |
812 | ||
813 | if (resmap == NULL || ocfs2_resmap_disabled(resmap)) | |
814 | return; | |
815 | ||
816 | if (resv == NULL) | |
817 | return; | |
818 | ||
819 | spin_lock(&resv_lock); | |
820 | ||
821 | mlog(0, "claim bits: cstart: %u cend: %u clen: %u r_start: %u " | |
822 | "r_end: %u r_len: %u, r_last_start: %u r_last_len: %u\n", | |
823 | cstart, cend, clen, resv->r_start, ocfs2_resv_end(resv), | |
824 | resv->r_len, resv->r_last_start, resv->r_last_len); | |
825 | ||
826 | BUG_ON(cstart < resv->r_start); | |
827 | BUG_ON(cstart > ocfs2_resv_end(resv)); | |
828 | BUG_ON(cend > ocfs2_resv_end(resv)); | |
829 | ||
830 | ocfs2_adjust_resv_from_alloc(resmap, resv, cstart, cend); | |
831 | resv->r_last_start = cstart; | |
832 | resv->r_last_len = clen; | |
833 | ||
834 | /* | |
835 | * May have been discarded above from | |
836 | * ocfs2_adjust_resv_from_alloc(). | |
837 | */ | |
838 | if (!ocfs2_resv_empty(resv)) | |
839 | ocfs2_resv_mark_lru(resmap, resv); | |
840 | ||
841 | mlog(0, "Reservation now looks like: r_start: %u r_end: %u " | |
842 | "r_len: %u r_last_start: %u r_last_len: %u\n", | |
843 | resv->r_start, ocfs2_resv_end(resv), resv->r_len, | |
844 | resv->r_last_start, resv->r_last_len); | |
845 | ||
846 | ocfs2_check_resmap(resmap); | |
847 | ||
848 | spin_unlock(&resv_lock); | |
849 | } |