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9eefe2a2 SR |
1 | /* |
2 | * This file is part of UBIFS. | |
3 | * | |
4 | * Copyright (C) 2006-2008 Nokia Corporation. | |
5 | * | |
ff94bc40 | 6 | * SPDX-License-Identifier: GPL-2.0+ |
9eefe2a2 SR |
7 | * |
8 | * Authors: Adrian Hunter | |
9 | * Artem Bityutskiy (Битюцкий Артём) | |
10 | */ | |
11 | ||
12 | /* | |
13 | * This file implements the budgeting sub-system which is responsible for UBIFS | |
14 | * space management. | |
15 | * | |
16 | * Factors such as compression, wasted space at the ends of LEBs, space in other | |
17 | * journal heads, the effect of updates on the index, and so on, make it | |
18 | * impossible to accurately predict the amount of space needed. Consequently | |
19 | * approximations are used. | |
20 | */ | |
21 | ||
22 | #include "ubifs.h" | |
ff94bc40 HS |
23 | #ifndef __UBOOT__ |
24 | #include <linux/writeback.h> | |
25 | #else | |
26 | #include <linux/err.h> | |
27 | #endif | |
9eefe2a2 SR |
28 | #include <linux/math64.h> |
29 | ||
ff94bc40 HS |
30 | /* |
31 | * When pessimistic budget calculations say that there is no enough space, | |
32 | * UBIFS starts writing back dirty inodes and pages, doing garbage collection, | |
33 | * or committing. The below constant defines maximum number of times UBIFS | |
34 | * repeats the operations. | |
35 | */ | |
36 | #define MAX_MKSPC_RETRIES 3 | |
37 | ||
38 | /* | |
39 | * The below constant defines amount of dirty pages which should be written | |
40 | * back at when trying to shrink the liability. | |
41 | */ | |
42 | #define NR_TO_WRITE 16 | |
43 | ||
44 | #ifndef __UBOOT__ | |
45 | /** | |
46 | * shrink_liability - write-back some dirty pages/inodes. | |
47 | * @c: UBIFS file-system description object | |
48 | * @nr_to_write: how many dirty pages to write-back | |
49 | * | |
50 | * This function shrinks UBIFS liability by means of writing back some amount | |
51 | * of dirty inodes and their pages. | |
52 | * | |
53 | * Note, this function synchronizes even VFS inodes which are locked | |
54 | * (@i_mutex) by the caller of the budgeting function, because write-back does | |
55 | * not touch @i_mutex. | |
56 | */ | |
57 | static void shrink_liability(struct ubifs_info *c, int nr_to_write) | |
58 | { | |
59 | down_read(&c->vfs_sb->s_umount); | |
60 | writeback_inodes_sb(c->vfs_sb, WB_REASON_FS_FREE_SPACE); | |
61 | up_read(&c->vfs_sb->s_umount); | |
62 | } | |
63 | ||
64 | /** | |
65 | * run_gc - run garbage collector. | |
66 | * @c: UBIFS file-system description object | |
67 | * | |
68 | * This function runs garbage collector to make some more free space. Returns | |
69 | * zero if a free LEB has been produced, %-EAGAIN if commit is required, and a | |
70 | * negative error code in case of failure. | |
71 | */ | |
72 | static int run_gc(struct ubifs_info *c) | |
73 | { | |
74 | int err, lnum; | |
75 | ||
76 | /* Make some free space by garbage-collecting dirty space */ | |
77 | down_read(&c->commit_sem); | |
78 | lnum = ubifs_garbage_collect(c, 1); | |
79 | up_read(&c->commit_sem); | |
80 | if (lnum < 0) | |
81 | return lnum; | |
82 | ||
83 | /* GC freed one LEB, return it to lprops */ | |
84 | dbg_budg("GC freed LEB %d", lnum); | |
85 | err = ubifs_return_leb(c, lnum); | |
86 | if (err) | |
87 | return err; | |
88 | return 0; | |
89 | } | |
90 | ||
9eefe2a2 | 91 | /** |
ff94bc40 | 92 | * get_liability - calculate current liability. |
9eefe2a2 SR |
93 | * @c: UBIFS file-system description object |
94 | * | |
ff94bc40 HS |
95 | * This function calculates and returns current UBIFS liability, i.e. the |
96 | * amount of bytes UBIFS has "promised" to write to the media. | |
97 | */ | |
98 | static long long get_liability(struct ubifs_info *c) | |
99 | { | |
100 | long long liab; | |
101 | ||
102 | spin_lock(&c->space_lock); | |
103 | liab = c->bi.idx_growth + c->bi.data_growth + c->bi.dd_growth; | |
104 | spin_unlock(&c->space_lock); | |
105 | return liab; | |
106 | } | |
107 | ||
108 | /** | |
109 | * make_free_space - make more free space on the file-system. | |
110 | * @c: UBIFS file-system description object | |
111 | * | |
112 | * This function is called when an operation cannot be budgeted because there | |
113 | * is supposedly no free space. But in most cases there is some free space: | |
114 | * o budgeting is pessimistic, so it always budgets more than it is actually | |
115 | * needed, so shrinking the liability is one way to make free space - the | |
116 | * cached data will take less space then it was budgeted for; | |
117 | * o GC may turn some dark space into free space (budgeting treats dark space | |
118 | * as not available); | |
119 | * o commit may free some LEB, i.e., turn freeable LEBs into free LEBs. | |
120 | * | |
121 | * So this function tries to do the above. Returns %-EAGAIN if some free space | |
122 | * was presumably made and the caller has to re-try budgeting the operation. | |
123 | * Returns %-ENOSPC if it couldn't do more free space, and other negative error | |
124 | * codes on failures. | |
125 | */ | |
126 | static int make_free_space(struct ubifs_info *c) | |
127 | { | |
128 | int err, retries = 0; | |
129 | long long liab1, liab2; | |
130 | ||
131 | do { | |
132 | liab1 = get_liability(c); | |
133 | /* | |
134 | * We probably have some dirty pages or inodes (liability), try | |
135 | * to write them back. | |
136 | */ | |
137 | dbg_budg("liability %lld, run write-back", liab1); | |
138 | shrink_liability(c, NR_TO_WRITE); | |
139 | ||
140 | liab2 = get_liability(c); | |
141 | if (liab2 < liab1) | |
142 | return -EAGAIN; | |
143 | ||
144 | dbg_budg("new liability %lld (not shrunk)", liab2); | |
145 | ||
146 | /* Liability did not shrink again, try GC */ | |
147 | dbg_budg("Run GC"); | |
148 | err = run_gc(c); | |
149 | if (!err) | |
150 | return -EAGAIN; | |
151 | ||
152 | if (err != -EAGAIN && err != -ENOSPC) | |
153 | /* Some real error happened */ | |
154 | return err; | |
155 | ||
156 | dbg_budg("Run commit (retries %d)", retries); | |
157 | err = ubifs_run_commit(c); | |
158 | if (err) | |
159 | return err; | |
160 | } while (retries++ < MAX_MKSPC_RETRIES); | |
161 | ||
162 | return -ENOSPC; | |
163 | } | |
164 | #endif | |
165 | ||
166 | /** | |
167 | * ubifs_calc_min_idx_lebs - calculate amount of LEBs for the index. | |
168 | * @c: UBIFS file-system description object | |
169 | * | |
170 | * This function calculates and returns the number of LEBs which should be kept | |
171 | * for index usage. | |
9eefe2a2 SR |
172 | */ |
173 | int ubifs_calc_min_idx_lebs(struct ubifs_info *c) | |
174 | { | |
ff94bc40 | 175 | int idx_lebs; |
9eefe2a2 SR |
176 | long long idx_size; |
177 | ||
ff94bc40 | 178 | idx_size = c->bi.old_idx_sz + c->bi.idx_growth + c->bi.uncommitted_idx; |
9eefe2a2 | 179 | /* And make sure we have thrice the index size of space reserved */ |
ff94bc40 | 180 | idx_size += idx_size << 1; |
9eefe2a2 SR |
181 | /* |
182 | * We do not maintain 'old_idx_size' as 'old_idx_lebs'/'old_idx_bytes' | |
183 | * pair, nor similarly the two variables for the new index size, so we | |
184 | * have to do this costly 64-bit division on fast-path. | |
185 | */ | |
ff94bc40 | 186 | idx_lebs = div_u64(idx_size + c->idx_leb_size - 1, c->idx_leb_size); |
9eefe2a2 SR |
187 | /* |
188 | * The index head is not available for the in-the-gaps method, so add an | |
189 | * extra LEB to compensate. | |
190 | */ | |
191 | idx_lebs += 1; | |
192 | if (idx_lebs < MIN_INDEX_LEBS) | |
193 | idx_lebs = MIN_INDEX_LEBS; | |
194 | return idx_lebs; | |
195 | } | |
196 | ||
ff94bc40 HS |
197 | #ifndef __UBOOT__ |
198 | /** | |
199 | * ubifs_calc_available - calculate available FS space. | |
200 | * @c: UBIFS file-system description object | |
201 | * @min_idx_lebs: minimum number of LEBs reserved for the index | |
202 | * | |
203 | * This function calculates and returns amount of FS space available for use. | |
204 | */ | |
205 | long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs) | |
206 | { | |
207 | int subtract_lebs; | |
208 | long long available; | |
209 | ||
210 | available = c->main_bytes - c->lst.total_used; | |
211 | ||
212 | /* | |
213 | * Now 'available' contains theoretically available flash space | |
214 | * assuming there is no index, so we have to subtract the space which | |
215 | * is reserved for the index. | |
216 | */ | |
217 | subtract_lebs = min_idx_lebs; | |
218 | ||
219 | /* Take into account that GC reserves one LEB for its own needs */ | |
220 | subtract_lebs += 1; | |
221 | ||
222 | /* | |
223 | * The GC journal head LEB is not really accessible. And since | |
224 | * different write types go to different heads, we may count only on | |
225 | * one head's space. | |
226 | */ | |
227 | subtract_lebs += c->jhead_cnt - 1; | |
228 | ||
229 | /* We also reserve one LEB for deletions, which bypass budgeting */ | |
230 | subtract_lebs += 1; | |
231 | ||
232 | available -= (long long)subtract_lebs * c->leb_size; | |
233 | ||
234 | /* Subtract the dead space which is not available for use */ | |
235 | available -= c->lst.total_dead; | |
236 | ||
237 | /* | |
238 | * Subtract dark space, which might or might not be usable - it depends | |
239 | * on the data which we have on the media and which will be written. If | |
240 | * this is a lot of uncompressed or not-compressible data, the dark | |
241 | * space cannot be used. | |
242 | */ | |
243 | available -= c->lst.total_dark; | |
244 | ||
245 | /* | |
246 | * However, there is more dark space. The index may be bigger than | |
247 | * @min_idx_lebs. Those extra LEBs are assumed to be available, but | |
248 | * their dark space is not included in total_dark, so it is subtracted | |
249 | * here. | |
250 | */ | |
251 | if (c->lst.idx_lebs > min_idx_lebs) { | |
252 | subtract_lebs = c->lst.idx_lebs - min_idx_lebs; | |
253 | available -= subtract_lebs * c->dark_wm; | |
254 | } | |
255 | ||
256 | /* The calculations are rough and may end up with a negative number */ | |
257 | return available > 0 ? available : 0; | |
258 | } | |
259 | ||
260 | /** | |
261 | * can_use_rp - check whether the user is allowed to use reserved pool. | |
262 | * @c: UBIFS file-system description object | |
263 | * | |
264 | * UBIFS has so-called "reserved pool" which is flash space reserved | |
265 | * for the superuser and for uses whose UID/GID is recorded in UBIFS superblock. | |
266 | * This function checks whether current user is allowed to use reserved pool. | |
267 | * Returns %1 current user is allowed to use reserved pool and %0 otherwise. | |
268 | */ | |
269 | static int can_use_rp(struct ubifs_info *c) | |
270 | { | |
271 | if (uid_eq(current_fsuid(), c->rp_uid) || capable(CAP_SYS_RESOURCE) || | |
272 | (!gid_eq(c->rp_gid, GLOBAL_ROOT_GID) && in_group_p(c->rp_gid))) | |
273 | return 1; | |
274 | return 0; | |
275 | } | |
276 | ||
277 | /** | |
278 | * do_budget_space - reserve flash space for index and data growth. | |
279 | * @c: UBIFS file-system description object | |
280 | * | |
281 | * This function makes sure UBIFS has enough free LEBs for index growth and | |
282 | * data. | |
283 | * | |
284 | * When budgeting index space, UBIFS reserves thrice as many LEBs as the index | |
285 | * would take if it was consolidated and written to the flash. This guarantees | |
286 | * that the "in-the-gaps" commit method always succeeds and UBIFS will always | |
287 | * be able to commit dirty index. So this function basically adds amount of | |
288 | * budgeted index space to the size of the current index, multiplies this by 3, | |
289 | * and makes sure this does not exceed the amount of free LEBs. | |
290 | * | |
291 | * Notes about @c->bi.min_idx_lebs and @c->lst.idx_lebs variables: | |
292 | * o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might | |
293 | * be large, because UBIFS does not do any index consolidation as long as | |
294 | * there is free space. IOW, the index may take a lot of LEBs, but the LEBs | |
295 | * will contain a lot of dirt. | |
296 | * o @c->bi.min_idx_lebs is the number of LEBS the index presumably takes. IOW, | |
297 | * the index may be consolidated to take up to @c->bi.min_idx_lebs LEBs. | |
298 | * | |
299 | * This function returns zero in case of success, and %-ENOSPC in case of | |
300 | * failure. | |
301 | */ | |
302 | static int do_budget_space(struct ubifs_info *c) | |
303 | { | |
304 | long long outstanding, available; | |
305 | int lebs, rsvd_idx_lebs, min_idx_lebs; | |
306 | ||
307 | /* First budget index space */ | |
308 | min_idx_lebs = ubifs_calc_min_idx_lebs(c); | |
309 | ||
310 | /* Now 'min_idx_lebs' contains number of LEBs to reserve */ | |
311 | if (min_idx_lebs > c->lst.idx_lebs) | |
312 | rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs; | |
313 | else | |
314 | rsvd_idx_lebs = 0; | |
315 | ||
316 | /* | |
317 | * The number of LEBs that are available to be used by the index is: | |
318 | * | |
319 | * @c->lst.empty_lebs + @c->freeable_cnt + @c->idx_gc_cnt - | |
320 | * @c->lst.taken_empty_lebs | |
321 | * | |
322 | * @c->lst.empty_lebs are available because they are empty. | |
323 | * @c->freeable_cnt are available because they contain only free and | |
324 | * dirty space, @c->idx_gc_cnt are available because they are index | |
325 | * LEBs that have been garbage collected and are awaiting the commit | |
326 | * before they can be used. And the in-the-gaps method will grab these | |
327 | * if it needs them. @c->lst.taken_empty_lebs are empty LEBs that have | |
328 | * already been allocated for some purpose. | |
329 | * | |
330 | * Note, @c->idx_gc_cnt is included to both @c->lst.empty_lebs (because | |
331 | * these LEBs are empty) and to @c->lst.taken_empty_lebs (because they | |
332 | * are taken until after the commit). | |
333 | * | |
334 | * Note, @c->lst.taken_empty_lebs may temporarily be higher by one | |
335 | * because of the way we serialize LEB allocations and budgeting. See a | |
336 | * comment in 'ubifs_find_free_space()'. | |
337 | */ | |
338 | lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt - | |
339 | c->lst.taken_empty_lebs; | |
340 | if (unlikely(rsvd_idx_lebs > lebs)) { | |
341 | dbg_budg("out of indexing space: min_idx_lebs %d (old %d), rsvd_idx_lebs %d", | |
342 | min_idx_lebs, c->bi.min_idx_lebs, rsvd_idx_lebs); | |
343 | return -ENOSPC; | |
344 | } | |
345 | ||
346 | available = ubifs_calc_available(c, min_idx_lebs); | |
347 | outstanding = c->bi.data_growth + c->bi.dd_growth; | |
348 | ||
349 | if (unlikely(available < outstanding)) { | |
350 | dbg_budg("out of data space: available %lld, outstanding %lld", | |
351 | available, outstanding); | |
352 | return -ENOSPC; | |
353 | } | |
354 | ||
355 | if (available - outstanding <= c->rp_size && !can_use_rp(c)) | |
356 | return -ENOSPC; | |
357 | ||
358 | c->bi.min_idx_lebs = min_idx_lebs; | |
359 | return 0; | |
360 | } | |
361 | ||
362 | /** | |
363 | * calc_idx_growth - calculate approximate index growth from budgeting request. | |
364 | * @c: UBIFS file-system description object | |
365 | * @req: budgeting request | |
366 | * | |
367 | * For now we assume each new node adds one znode. But this is rather poor | |
368 | * approximation, though. | |
369 | */ | |
370 | static int calc_idx_growth(const struct ubifs_info *c, | |
371 | const struct ubifs_budget_req *req) | |
372 | { | |
373 | int znodes; | |
374 | ||
375 | znodes = req->new_ino + (req->new_page << UBIFS_BLOCKS_PER_PAGE_SHIFT) + | |
376 | req->new_dent; | |
377 | return znodes * c->max_idx_node_sz; | |
378 | } | |
379 | ||
380 | /** | |
381 | * calc_data_growth - calculate approximate amount of new data from budgeting | |
382 | * request. | |
383 | * @c: UBIFS file-system description object | |
384 | * @req: budgeting request | |
385 | */ | |
386 | static int calc_data_growth(const struct ubifs_info *c, | |
387 | const struct ubifs_budget_req *req) | |
388 | { | |
389 | int data_growth; | |
390 | ||
391 | data_growth = req->new_ino ? c->bi.inode_budget : 0; | |
392 | if (req->new_page) | |
393 | data_growth += c->bi.page_budget; | |
394 | if (req->new_dent) | |
395 | data_growth += c->bi.dent_budget; | |
396 | data_growth += req->new_ino_d; | |
397 | return data_growth; | |
398 | } | |
399 | ||
400 | /** | |
401 | * calc_dd_growth - calculate approximate amount of data which makes other data | |
402 | * dirty from budgeting request. | |
403 | * @c: UBIFS file-system description object | |
404 | * @req: budgeting request | |
405 | */ | |
406 | static int calc_dd_growth(const struct ubifs_info *c, | |
407 | const struct ubifs_budget_req *req) | |
408 | { | |
409 | int dd_growth; | |
410 | ||
411 | dd_growth = req->dirtied_page ? c->bi.page_budget : 0; | |
412 | ||
413 | if (req->dirtied_ino) | |
414 | dd_growth += c->bi.inode_budget << (req->dirtied_ino - 1); | |
415 | if (req->mod_dent) | |
416 | dd_growth += c->bi.dent_budget; | |
417 | dd_growth += req->dirtied_ino_d; | |
418 | return dd_growth; | |
419 | } | |
420 | ||
421 | /** | |
422 | * ubifs_budget_space - ensure there is enough space to complete an operation. | |
423 | * @c: UBIFS file-system description object | |
424 | * @req: budget request | |
425 | * | |
426 | * This function allocates budget for an operation. It uses pessimistic | |
427 | * approximation of how much flash space the operation needs. The goal of this | |
428 | * function is to make sure UBIFS always has flash space to flush all dirty | |
429 | * pages, dirty inodes, and dirty znodes (liability). This function may force | |
430 | * commit, garbage-collection or write-back. Returns zero in case of success, | |
431 | * %-ENOSPC if there is no free space and other negative error codes in case of | |
432 | * failures. | |
433 | */ | |
434 | int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req) | |
435 | { | |
ff94bc40 HS |
436 | int err, idx_growth, data_growth, dd_growth, retried = 0; |
437 | ||
438 | ubifs_assert(req->new_page <= 1); | |
439 | ubifs_assert(req->dirtied_page <= 1); | |
440 | ubifs_assert(req->new_dent <= 1); | |
441 | ubifs_assert(req->mod_dent <= 1); | |
442 | ubifs_assert(req->new_ino <= 1); | |
443 | ubifs_assert(req->new_ino_d <= UBIFS_MAX_INO_DATA); | |
444 | ubifs_assert(req->dirtied_ino <= 4); | |
445 | ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4); | |
446 | ubifs_assert(!(req->new_ino_d & 7)); | |
447 | ubifs_assert(!(req->dirtied_ino_d & 7)); | |
448 | ||
449 | data_growth = calc_data_growth(c, req); | |
450 | dd_growth = calc_dd_growth(c, req); | |
451 | if (!data_growth && !dd_growth) | |
452 | return 0; | |
453 | idx_growth = calc_idx_growth(c, req); | |
454 | ||
455 | again: | |
456 | spin_lock(&c->space_lock); | |
457 | ubifs_assert(c->bi.idx_growth >= 0); | |
458 | ubifs_assert(c->bi.data_growth >= 0); | |
459 | ubifs_assert(c->bi.dd_growth >= 0); | |
460 | ||
461 | if (unlikely(c->bi.nospace) && (c->bi.nospace_rp || !can_use_rp(c))) { | |
462 | dbg_budg("no space"); | |
463 | spin_unlock(&c->space_lock); | |
464 | return -ENOSPC; | |
465 | } | |
466 | ||
467 | c->bi.idx_growth += idx_growth; | |
468 | c->bi.data_growth += data_growth; | |
469 | c->bi.dd_growth += dd_growth; | |
470 | ||
471 | err = do_budget_space(c); | |
472 | if (likely(!err)) { | |
473 | req->idx_growth = idx_growth; | |
474 | req->data_growth = data_growth; | |
475 | req->dd_growth = dd_growth; | |
476 | spin_unlock(&c->space_lock); | |
477 | return 0; | |
478 | } | |
479 | ||
480 | /* Restore the old values */ | |
481 | c->bi.idx_growth -= idx_growth; | |
482 | c->bi.data_growth -= data_growth; | |
483 | c->bi.dd_growth -= dd_growth; | |
484 | spin_unlock(&c->space_lock); | |
485 | ||
486 | if (req->fast) { | |
487 | dbg_budg("no space for fast budgeting"); | |
488 | return err; | |
489 | } | |
490 | ||
491 | err = make_free_space(c); | |
492 | cond_resched(); | |
493 | if (err == -EAGAIN) { | |
494 | dbg_budg("try again"); | |
495 | goto again; | |
496 | } else if (err == -ENOSPC) { | |
497 | if (!retried) { | |
498 | retried = 1; | |
499 | dbg_budg("-ENOSPC, but anyway try once again"); | |
500 | goto again; | |
501 | } | |
502 | dbg_budg("FS is full, -ENOSPC"); | |
503 | c->bi.nospace = 1; | |
504 | if (can_use_rp(c) || c->rp_size == 0) | |
505 | c->bi.nospace_rp = 1; | |
506 | smp_wmb(); | |
507 | } else | |
0195a7bb | 508 | ubifs_err(c, "cannot budget space, error %d", err); |
ff94bc40 HS |
509 | return err; |
510 | } | |
511 | ||
512 | /** | |
513 | * ubifs_release_budget - release budgeted free space. | |
514 | * @c: UBIFS file-system description object | |
515 | * @req: budget request | |
516 | * | |
517 | * This function releases the space budgeted by 'ubifs_budget_space()'. Note, | |
518 | * since the index changes (which were budgeted for in @req->idx_growth) will | |
519 | * only be written to the media on commit, this function moves the index budget | |
520 | * from @c->bi.idx_growth to @c->bi.uncommitted_idx. The latter will be zeroed | |
521 | * by the commit operation. | |
522 | */ | |
523 | void ubifs_release_budget(struct ubifs_info *c, struct ubifs_budget_req *req) | |
524 | { | |
525 | ubifs_assert(req->new_page <= 1); | |
526 | ubifs_assert(req->dirtied_page <= 1); | |
527 | ubifs_assert(req->new_dent <= 1); | |
528 | ubifs_assert(req->mod_dent <= 1); | |
529 | ubifs_assert(req->new_ino <= 1); | |
530 | ubifs_assert(req->new_ino_d <= UBIFS_MAX_INO_DATA); | |
531 | ubifs_assert(req->dirtied_ino <= 4); | |
532 | ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4); | |
533 | ubifs_assert(!(req->new_ino_d & 7)); | |
534 | ubifs_assert(!(req->dirtied_ino_d & 7)); | |
535 | if (!req->recalculate) { | |
536 | ubifs_assert(req->idx_growth >= 0); | |
537 | ubifs_assert(req->data_growth >= 0); | |
538 | ubifs_assert(req->dd_growth >= 0); | |
539 | } | |
540 | ||
541 | if (req->recalculate) { | |
542 | req->data_growth = calc_data_growth(c, req); | |
543 | req->dd_growth = calc_dd_growth(c, req); | |
544 | req->idx_growth = calc_idx_growth(c, req); | |
545 | } | |
546 | ||
547 | if (!req->data_growth && !req->dd_growth) | |
548 | return; | |
549 | ||
550 | c->bi.nospace = c->bi.nospace_rp = 0; | |
551 | smp_wmb(); | |
552 | ||
553 | spin_lock(&c->space_lock); | |
554 | c->bi.idx_growth -= req->idx_growth; | |
555 | c->bi.uncommitted_idx += req->idx_growth; | |
556 | c->bi.data_growth -= req->data_growth; | |
557 | c->bi.dd_growth -= req->dd_growth; | |
558 | c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c); | |
559 | ||
560 | ubifs_assert(c->bi.idx_growth >= 0); | |
561 | ubifs_assert(c->bi.data_growth >= 0); | |
562 | ubifs_assert(c->bi.dd_growth >= 0); | |
563 | ubifs_assert(c->bi.min_idx_lebs < c->main_lebs); | |
564 | ubifs_assert(!(c->bi.idx_growth & 7)); | |
565 | ubifs_assert(!(c->bi.data_growth & 7)); | |
566 | ubifs_assert(!(c->bi.dd_growth & 7)); | |
567 | spin_unlock(&c->space_lock); | |
568 | } | |
569 | ||
570 | /** | |
571 | * ubifs_convert_page_budget - convert budget of a new page. | |
572 | * @c: UBIFS file-system description object | |
573 | * | |
574 | * This function converts budget which was allocated for a new page of data to | |
575 | * the budget of changing an existing page of data. The latter is smaller than | |
576 | * the former, so this function only does simple re-calculation and does not | |
577 | * involve any write-back. | |
578 | */ | |
579 | void ubifs_convert_page_budget(struct ubifs_info *c) | |
580 | { | |
581 | spin_lock(&c->space_lock); | |
582 | /* Release the index growth reservation */ | |
583 | c->bi.idx_growth -= c->max_idx_node_sz << UBIFS_BLOCKS_PER_PAGE_SHIFT; | |
584 | /* Release the data growth reservation */ | |
585 | c->bi.data_growth -= c->bi.page_budget; | |
586 | /* Increase the dirty data growth reservation instead */ | |
587 | c->bi.dd_growth += c->bi.page_budget; | |
588 | /* And re-calculate the indexing space reservation */ | |
589 | c->bi.min_idx_lebs = ubifs_calc_min_idx_lebs(c); | |
590 | spin_unlock(&c->space_lock); | |
591 | } | |
592 | ||
593 | /** | |
594 | * ubifs_release_dirty_inode_budget - release dirty inode budget. | |
595 | * @c: UBIFS file-system description object | |
596 | * @ui: UBIFS inode to release the budget for | |
597 | * | |
598 | * This function releases budget corresponding to a dirty inode. It is usually | |
599 | * called when after the inode has been written to the media and marked as | |
600 | * clean. It also causes the "no space" flags to be cleared. | |
601 | */ | |
602 | void ubifs_release_dirty_inode_budget(struct ubifs_info *c, | |
603 | struct ubifs_inode *ui) | |
604 | { | |
605 | struct ubifs_budget_req req; | |
606 | ||
607 | memset(&req, 0, sizeof(struct ubifs_budget_req)); | |
608 | /* The "no space" flags will be cleared because dd_growth is > 0 */ | |
609 | req.dd_growth = c->bi.inode_budget + ALIGN(ui->data_len, 8); | |
610 | ubifs_release_budget(c, &req); | |
611 | } | |
612 | #endif | |
613 | ||
9eefe2a2 SR |
614 | /** |
615 | * ubifs_reported_space - calculate reported free space. | |
616 | * @c: the UBIFS file-system description object | |
617 | * @free: amount of free space | |
618 | * | |
619 | * This function calculates amount of free space which will be reported to | |
620 | * user-space. User-space application tend to expect that if the file-system | |
621 | * (e.g., via the 'statfs()' call) reports that it has N bytes available, they | |
622 | * are able to write a file of size N. UBIFS attaches node headers to each data | |
623 | * node and it has to write indexing nodes as well. This introduces additional | |
624 | * overhead, and UBIFS has to report slightly less free space to meet the above | |
625 | * expectations. | |
626 | * | |
627 | * This function assumes free space is made up of uncompressed data nodes and | |
628 | * full index nodes (one per data node, tripled because we always allow enough | |
629 | * space to write the index thrice). | |
630 | * | |
631 | * Note, the calculation is pessimistic, which means that most of the time | |
632 | * UBIFS reports less space than it actually has. | |
633 | */ | |
634 | long long ubifs_reported_space(const struct ubifs_info *c, long long free) | |
635 | { | |
636 | int divisor, factor, f; | |
637 | ||
638 | /* | |
639 | * Reported space size is @free * X, where X is UBIFS block size | |
640 | * divided by UBIFS block size + all overhead one data block | |
641 | * introduces. The overhead is the node header + indexing overhead. | |
642 | * | |
643 | * Indexing overhead calculations are based on the following formula: | |
644 | * I = N/(f - 1) + 1, where I - number of indexing nodes, N - number | |
645 | * of data nodes, f - fanout. Because effective UBIFS fanout is twice | |
646 | * as less than maximum fanout, we assume that each data node | |
647 | * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes. | |
648 | * Note, the multiplier 3 is because UBIFS reserves thrice as more space | |
649 | * for the index. | |
650 | */ | |
651 | f = c->fanout > 3 ? c->fanout >> 1 : 2; | |
652 | factor = UBIFS_BLOCK_SIZE; | |
653 | divisor = UBIFS_MAX_DATA_NODE_SZ; | |
654 | divisor += (c->max_idx_node_sz * 3) / (f - 1); | |
655 | free *= factor; | |
656 | return div_u64(free, divisor); | |
657 | } | |
ff94bc40 HS |
658 | |
659 | #ifndef __UBOOT__ | |
660 | /** | |
661 | * ubifs_get_free_space_nolock - return amount of free space. | |
662 | * @c: UBIFS file-system description object | |
663 | * | |
664 | * This function calculates amount of free space to report to user-space. | |
665 | * | |
666 | * Because UBIFS may introduce substantial overhead (the index, node headers, | |
667 | * alignment, wastage at the end of LEBs, etc), it cannot report real amount of | |
668 | * free flash space it has (well, because not all dirty space is reclaimable, | |
669 | * UBIFS does not actually know the real amount). If UBIFS did so, it would | |
670 | * bread user expectations about what free space is. Users seem to accustomed | |
671 | * to assume that if the file-system reports N bytes of free space, they would | |
672 | * be able to fit a file of N bytes to the FS. This almost works for | |
673 | * traditional file-systems, because they have way less overhead than UBIFS. | |
674 | * So, to keep users happy, UBIFS tries to take the overhead into account. | |
675 | */ | |
676 | long long ubifs_get_free_space_nolock(struct ubifs_info *c) | |
677 | { | |
678 | int rsvd_idx_lebs, lebs; | |
679 | long long available, outstanding, free; | |
680 | ||
681 | ubifs_assert(c->bi.min_idx_lebs == ubifs_calc_min_idx_lebs(c)); | |
682 | outstanding = c->bi.data_growth + c->bi.dd_growth; | |
683 | available = ubifs_calc_available(c, c->bi.min_idx_lebs); | |
684 | ||
685 | /* | |
686 | * When reporting free space to user-space, UBIFS guarantees that it is | |
687 | * possible to write a file of free space size. This means that for | |
688 | * empty LEBs we may use more precise calculations than | |
689 | * 'ubifs_calc_available()' is using. Namely, we know that in empty | |
690 | * LEBs we would waste only @c->leb_overhead bytes, not @c->dark_wm. | |
691 | * Thus, amend the available space. | |
692 | * | |
693 | * Note, the calculations below are similar to what we have in | |
694 | * 'do_budget_space()', so refer there for comments. | |
695 | */ | |
696 | if (c->bi.min_idx_lebs > c->lst.idx_lebs) | |
697 | rsvd_idx_lebs = c->bi.min_idx_lebs - c->lst.idx_lebs; | |
698 | else | |
699 | rsvd_idx_lebs = 0; | |
700 | lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt - | |
701 | c->lst.taken_empty_lebs; | |
702 | lebs -= rsvd_idx_lebs; | |
703 | available += lebs * (c->dark_wm - c->leb_overhead); | |
704 | ||
705 | if (available > outstanding) | |
706 | free = ubifs_reported_space(c, available - outstanding); | |
707 | else | |
708 | free = 0; | |
709 | return free; | |
710 | } | |
711 | ||
712 | /** | |
713 | * ubifs_get_free_space - return amount of free space. | |
714 | * @c: UBIFS file-system description object | |
715 | * | |
716 | * This function calculates and returns amount of free space to report to | |
717 | * user-space. | |
718 | */ | |
719 | long long ubifs_get_free_space(struct ubifs_info *c) | |
720 | { | |
721 | long long free; | |
722 | ||
723 | spin_lock(&c->space_lock); | |
724 | free = ubifs_get_free_space_nolock(c); | |
725 | spin_unlock(&c->space_lock); | |
726 | ||
727 | return free; | |
728 | } | |
729 | #endif |