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Artem Bityutskiy1e517642008-07-14 19:08:37 +03001/*
2 * This file is part of UBIFS.
3 *
4 * Copyright (C) 2006-2008 Nokia Corporation.
5 *
6 * This program is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 as published by
8 * the Free Software Foundation.
9 *
10 * This program is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 * more details.
14 *
15 * You should have received a copy of the GNU General Public License along with
16 * this program; if not, write to the Free Software Foundation, Inc., 51
17 * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18 *
19 * Authors: Adrian Hunter
20 * Artem Bityutskiy (Битюцкий Артём)
21 */
22
23/*
24 * This file implements the budgeting sub-system which is responsible for UBIFS
25 * space management.
26 *
27 * Factors such as compression, wasted space at the ends of LEBs, space in other
28 * journal heads, the effect of updates on the index, and so on, make it
29 * impossible to accurately predict the amount of space needed. Consequently
30 * approximations are used.
31 */
32
33#include "ubifs.h"
34#include <linux/writeback.h>
Artem Bityutskiy4d61db42008-12-18 14:06:51 +020035#include <linux/math64.h>
Artem Bityutskiy1e517642008-07-14 19:08:37 +030036
37/*
38 * When pessimistic budget calculations say that there is no enough space,
39 * UBIFS starts writing back dirty inodes and pages, doing garbage collection,
Artem Bityutskiy2acf8062008-12-09 11:04:40 -050040 * or committing. The below constant defines maximum number of times UBIFS
Artem Bityutskiy1e517642008-07-14 19:08:37 +030041 * repeats the operations.
42 */
Artem Bityutskiy2acf8062008-12-09 11:04:40 -050043#define MAX_MKSPC_RETRIES 3
Artem Bityutskiy1e517642008-07-14 19:08:37 +030044
45/*
46 * The below constant defines amount of dirty pages which should be written
47 * back at when trying to shrink the liability.
48 */
49#define NR_TO_WRITE 16
50
51/**
Artem Bityutskiy1e517642008-07-14 19:08:37 +030052 * shrink_liability - write-back some dirty pages/inodes.
53 * @c: UBIFS file-system description object
54 * @nr_to_write: how many dirty pages to write-back
55 *
56 * This function shrinks UBIFS liability by means of writing back some amount
Jens Axboeb6e51312009-09-16 15:13:54 +020057 * of dirty inodes and their pages.
Artem Bityutskiy1e517642008-07-14 19:08:37 +030058 *
59 * Note, this function synchronizes even VFS inodes which are locked
60 * (@i_mutex) by the caller of the budgeting function, because write-back does
61 * not touch @i_mutex.
62 */
Jens Axboeb6e51312009-09-16 15:13:54 +020063static void shrink_liability(struct ubifs_info *c, int nr_to_write)
Artem Bityutskiy1e517642008-07-14 19:08:37 +030064{
Christoph Hellwigcf37e972010-06-08 18:14:51 +020065 down_read(&c->vfs_sb->s_umount);
Jens Axboeb6e51312009-09-16 15:13:54 +020066 writeback_inodes_sb(c->vfs_sb);
Christoph Hellwigcf37e972010-06-08 18:14:51 +020067 up_read(&c->vfs_sb->s_umount);
Artem Bityutskiy1e517642008-07-14 19:08:37 +030068}
69
Artem Bityutskiy1e517642008-07-14 19:08:37 +030070/**
71 * run_gc - run garbage collector.
72 * @c: UBIFS file-system description object
73 *
74 * This function runs garbage collector to make some more free space. Returns
75 * zero if a free LEB has been produced, %-EAGAIN if commit is required, and a
76 * negative error code in case of failure.
77 */
78static int run_gc(struct ubifs_info *c)
79{
80 int err, lnum;
81
82 /* Make some free space by garbage-collecting dirty space */
83 down_read(&c->commit_sem);
84 lnum = ubifs_garbage_collect(c, 1);
85 up_read(&c->commit_sem);
86 if (lnum < 0)
87 return lnum;
88
89 /* GC freed one LEB, return it to lprops */
90 dbg_budg("GC freed LEB %d", lnum);
91 err = ubifs_return_leb(c, lnum);
92 if (err)
93 return err;
94 return 0;
95}
96
97/**
Artem Bityutskiy2acf8062008-12-09 11:04:40 -050098 * get_liability - calculate current liability.
99 * @c: UBIFS file-system description object
100 *
101 * This function calculates and returns current UBIFS liability, i.e. the
102 * amount of bytes UBIFS has "promised" to write to the media.
103 */
104static long long get_liability(struct ubifs_info *c)
105{
106 long long liab;
107
108 spin_lock(&c->space_lock);
109 liab = c->budg_idx_growth + c->budg_data_growth + c->budg_dd_growth;
110 spin_unlock(&c->space_lock);
111 return liab;
112}
113
114/**
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300115 * make_free_space - make more free space on the file-system.
116 * @c: UBIFS file-system description object
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300117 *
118 * This function is called when an operation cannot be budgeted because there
119 * is supposedly no free space. But in most cases there is some free space:
Frederik Schwarzer025dfda2008-10-16 19:02:37 +0200120 * o budgeting is pessimistic, so it always budgets more than it is actually
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300121 * needed, so shrinking the liability is one way to make free space - the
122 * cached data will take less space then it was budgeted for;
123 * o GC may turn some dark space into free space (budgeting treats dark space
124 * as not available);
125 * o commit may free some LEB, i.e., turn freeable LEBs into free LEBs.
126 *
127 * So this function tries to do the above. Returns %-EAGAIN if some free space
128 * was presumably made and the caller has to re-try budgeting the operation.
129 * Returns %-ENOSPC if it couldn't do more free space, and other negative error
130 * codes on failures.
131 */
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500132static int make_free_space(struct ubifs_info *c)
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300133{
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500134 int err, retries = 0;
135 long long liab1, liab2;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300136
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500137 do {
138 liab1 = get_liability(c);
139 /*
140 * We probably have some dirty pages or inodes (liability), try
141 * to write them back.
142 */
143 dbg_budg("liability %lld, run write-back", liab1);
144 shrink_liability(c, NR_TO_WRITE);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300145
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500146 liab2 = get_liability(c);
147 if (liab2 < liab1)
148 return -EAGAIN;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300149
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500150 dbg_budg("new liability %lld (not shrinked)", liab2);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300151
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500152 /* Liability did not shrink again, try GC */
153 dbg_budg("Run GC");
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300154 err = run_gc(c);
155 if (!err)
156 return -EAGAIN;
157
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500158 if (err != -EAGAIN && err != -ENOSPC)
159 /* Some real error happened */
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300160 return err;
161
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500162 dbg_budg("Run commit (retries %d)", retries);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300163 err = ubifs_run_commit(c);
164 if (err)
165 return err;
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500166 } while (retries++ < MAX_MKSPC_RETRIES);
167
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300168 return -ENOSPC;
169}
170
171/**
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200172 * ubifs_calc_min_idx_lebs - calculate amount of LEBs for the index.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300173 * @c: UBIFS file-system description object
174 *
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200175 * This function calculates and returns the number of LEBs which should be kept
176 * for index usage.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300177 */
178int ubifs_calc_min_idx_lebs(struct ubifs_info *c)
179{
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200180 int idx_lebs;
Artem Bityutskiy4d61db42008-12-18 14:06:51 +0200181 long long idx_size;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300182
183 idx_size = c->old_idx_sz + c->budg_idx_growth + c->budg_uncommitted_idx;
Adrian Hunter3a132522008-07-30 12:18:02 +0300184 /* And make sure we have thrice the index size of space reserved */
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200185 idx_size += idx_size << 1;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300186 /*
187 * We do not maintain 'old_idx_size' as 'old_idx_lebs'/'old_idx_bytes'
188 * pair, nor similarly the two variables for the new index size, so we
189 * have to do this costly 64-bit division on fast-path.
190 */
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200191 idx_lebs = div_u64(idx_size + c->idx_leb_size - 1, c->idx_leb_size);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300192 /*
193 * The index head is not available for the in-the-gaps method, so add an
194 * extra LEB to compensate.
195 */
Artem Bityutskiy4d61db42008-12-18 14:06:51 +0200196 idx_lebs += 1;
197 if (idx_lebs < MIN_INDEX_LEBS)
198 idx_lebs = MIN_INDEX_LEBS;
199 return idx_lebs;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300200}
201
202/**
203 * ubifs_calc_available - calculate available FS space.
204 * @c: UBIFS file-system description object
205 * @min_idx_lebs: minimum number of LEBs reserved for the index
206 *
207 * This function calculates and returns amount of FS space available for use.
208 */
209long long ubifs_calc_available(const struct ubifs_info *c, int min_idx_lebs)
210{
211 int subtract_lebs;
212 long long available;
213
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300214 available = c->main_bytes - c->lst.total_used;
215
216 /*
217 * Now 'available' contains theoretically available flash space
218 * assuming there is no index, so we have to subtract the space which
219 * is reserved for the index.
220 */
221 subtract_lebs = min_idx_lebs;
222
223 /* Take into account that GC reserves one LEB for its own needs */
224 subtract_lebs += 1;
225
226 /*
227 * The GC journal head LEB is not really accessible. And since
228 * different write types go to different heads, we may count only on
229 * one head's space.
230 */
231 subtract_lebs += c->jhead_cnt - 1;
232
233 /* We also reserve one LEB for deletions, which bypass budgeting */
234 subtract_lebs += 1;
235
236 available -= (long long)subtract_lebs * c->leb_size;
237
238 /* Subtract the dead space which is not available for use */
239 available -= c->lst.total_dead;
240
241 /*
242 * Subtract dark space, which might or might not be usable - it depends
243 * on the data which we have on the media and which will be written. If
244 * this is a lot of uncompressed or not-compressible data, the dark
245 * space cannot be used.
246 */
247 available -= c->lst.total_dark;
248
249 /*
250 * However, there is more dark space. The index may be bigger than
251 * @min_idx_lebs. Those extra LEBs are assumed to be available, but
252 * their dark space is not included in total_dark, so it is subtracted
253 * here.
254 */
255 if (c->lst.idx_lebs > min_idx_lebs) {
256 subtract_lebs = c->lst.idx_lebs - min_idx_lebs;
257 available -= subtract_lebs * c->dark_wm;
258 }
259
260 /* The calculations are rough and may end up with a negative number */
261 return available > 0 ? available : 0;
262}
263
264/**
265 * can_use_rp - check whether the user is allowed to use reserved pool.
266 * @c: UBIFS file-system description object
267 *
268 * UBIFS has so-called "reserved pool" which is flash space reserved
269 * for the superuser and for uses whose UID/GID is recorded in UBIFS superblock.
270 * This function checks whether current user is allowed to use reserved pool.
271 * Returns %1 current user is allowed to use reserved pool and %0 otherwise.
272 */
273static int can_use_rp(struct ubifs_info *c)
274{
David Howells26bf1942008-11-14 10:39:03 +1100275 if (current_fsuid() == c->rp_uid || capable(CAP_SYS_RESOURCE) ||
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300276 (c->rp_gid != 0 && in_group_p(c->rp_gid)))
277 return 1;
278 return 0;
279}
280
281/**
282 * do_budget_space - reserve flash space for index and data growth.
283 * @c: UBIFS file-system description object
284 *
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200285 * This function makes sure UBIFS has enough free LEBs for index growth and
286 * data.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300287 *
Adrian Hunter3a132522008-07-30 12:18:02 +0300288 * When budgeting index space, UBIFS reserves thrice as many LEBs as the index
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300289 * would take if it was consolidated and written to the flash. This guarantees
290 * that the "in-the-gaps" commit method always succeeds and UBIFS will always
291 * be able to commit dirty index. So this function basically adds amount of
Artem Bityutskiyb364b412008-07-25 14:38:51 +0300292 * budgeted index space to the size of the current index, multiplies this by 3,
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200293 * and makes sure this does not exceed the amount of free LEBs.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300294 *
295 * Notes about @c->min_idx_lebs and @c->lst.idx_lebs variables:
296 * o @c->lst.idx_lebs is the number of LEBs the index currently uses. It might
297 * be large, because UBIFS does not do any index consolidation as long as
298 * there is free space. IOW, the index may take a lot of LEBs, but the LEBs
299 * will contain a lot of dirt.
Artem Bityutskiy7d4e9cc2009-03-20 19:11:12 +0200300 * o @c->min_idx_lebs is the number of LEBS the index presumably takes. IOW,
301 * the index may be consolidated to take up to @c->min_idx_lebs LEBs.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300302 *
303 * This function returns zero in case of success, and %-ENOSPC in case of
304 * failure.
305 */
306static int do_budget_space(struct ubifs_info *c)
307{
308 long long outstanding, available;
309 int lebs, rsvd_idx_lebs, min_idx_lebs;
310
311 /* First budget index space */
312 min_idx_lebs = ubifs_calc_min_idx_lebs(c);
313
314 /* Now 'min_idx_lebs' contains number of LEBs to reserve */
315 if (min_idx_lebs > c->lst.idx_lebs)
316 rsvd_idx_lebs = min_idx_lebs - c->lst.idx_lebs;
317 else
318 rsvd_idx_lebs = 0;
319
320 /*
321 * The number of LEBs that are available to be used by the index is:
322 *
323 * @c->lst.empty_lebs + @c->freeable_cnt + @c->idx_gc_cnt -
324 * @c->lst.taken_empty_lebs
325 *
Artem Bityutskiy948cfb22008-08-20 11:56:33 +0300326 * @c->lst.empty_lebs are available because they are empty.
327 * @c->freeable_cnt are available because they contain only free and
328 * dirty space, @c->idx_gc_cnt are available because they are index
329 * LEBs that have been garbage collected and are awaiting the commit
330 * before they can be used. And the in-the-gaps method will grab these
331 * if it needs them. @c->lst.taken_empty_lebs are empty LEBs that have
332 * already been allocated for some purpose.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300333 *
Artem Bityutskiy948cfb22008-08-20 11:56:33 +0300334 * Note, @c->idx_gc_cnt is included to both @c->lst.empty_lebs (because
335 * these LEBs are empty) and to @c->lst.taken_empty_lebs (because they
336 * are taken until after the commit).
337 *
338 * Note, @c->lst.taken_empty_lebs may temporarily be higher by one
339 * because of the way we serialize LEB allocations and budgeting. See a
340 * comment in 'ubifs_find_free_space()'.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300341 */
342 lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
343 c->lst.taken_empty_lebs;
344 if (unlikely(rsvd_idx_lebs > lebs)) {
345 dbg_budg("out of indexing space: min_idx_lebs %d (old %d), "
346 "rsvd_idx_lebs %d", min_idx_lebs, c->min_idx_lebs,
347 rsvd_idx_lebs);
348 return -ENOSPC;
349 }
350
351 available = ubifs_calc_available(c, min_idx_lebs);
352 outstanding = c->budg_data_growth + c->budg_dd_growth;
353
354 if (unlikely(available < outstanding)) {
355 dbg_budg("out of data space: available %lld, outstanding %lld",
356 available, outstanding);
357 return -ENOSPC;
358 }
359
360 if (available - outstanding <= c->rp_size && !can_use_rp(c))
361 return -ENOSPC;
362
363 c->min_idx_lebs = min_idx_lebs;
364 return 0;
365}
366
367/**
368 * calc_idx_growth - calculate approximate index growth from budgeting request.
369 * @c: UBIFS file-system description object
370 * @req: budgeting request
371 *
372 * For now we assume each new node adds one znode. But this is rather poor
373 * approximation, though.
374 */
375static int calc_idx_growth(const struct ubifs_info *c,
376 const struct ubifs_budget_req *req)
377{
378 int znodes;
379
380 znodes = req->new_ino + (req->new_page << UBIFS_BLOCKS_PER_PAGE_SHIFT) +
381 req->new_dent;
382 return znodes * c->max_idx_node_sz;
383}
384
385/**
386 * calc_data_growth - calculate approximate amount of new data from budgeting
387 * request.
388 * @c: UBIFS file-system description object
389 * @req: budgeting request
390 */
391static int calc_data_growth(const struct ubifs_info *c,
392 const struct ubifs_budget_req *req)
393{
394 int data_growth;
395
396 data_growth = req->new_ino ? c->inode_budget : 0;
397 if (req->new_page)
398 data_growth += c->page_budget;
399 if (req->new_dent)
400 data_growth += c->dent_budget;
401 data_growth += req->new_ino_d;
402 return data_growth;
403}
404
405/**
406 * calc_dd_growth - calculate approximate amount of data which makes other data
407 * dirty from budgeting request.
408 * @c: UBIFS file-system description object
409 * @req: budgeting request
410 */
411static int calc_dd_growth(const struct ubifs_info *c,
412 const struct ubifs_budget_req *req)
413{
414 int dd_growth;
415
416 dd_growth = req->dirtied_page ? c->page_budget : 0;
417
418 if (req->dirtied_ino)
419 dd_growth += c->inode_budget << (req->dirtied_ino - 1);
420 if (req->mod_dent)
421 dd_growth += c->dent_budget;
422 dd_growth += req->dirtied_ino_d;
423 return dd_growth;
424}
425
426/**
427 * ubifs_budget_space - ensure there is enough space to complete an operation.
428 * @c: UBIFS file-system description object
429 * @req: budget request
430 *
431 * This function allocates budget for an operation. It uses pessimistic
432 * approximation of how much flash space the operation needs. The goal of this
433 * function is to make sure UBIFS always has flash space to flush all dirty
434 * pages, dirty inodes, and dirty znodes (liability). This function may force
435 * commit, garbage-collection or write-back. Returns zero in case of success,
436 * %-ENOSPC if there is no free space and other negative error codes in case of
437 * failures.
438 */
439int ubifs_budget_space(struct ubifs_info *c, struct ubifs_budget_req *req)
440{
441 int uninitialized_var(cmt_retries), uninitialized_var(wb_retries);
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500442 int err, idx_growth, data_growth, dd_growth, retried = 0;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300443
Artem Bityutskiy547000d2008-07-24 14:42:05 +0300444 ubifs_assert(req->new_page <= 1);
445 ubifs_assert(req->dirtied_page <= 1);
446 ubifs_assert(req->new_dent <= 1);
447 ubifs_assert(req->mod_dent <= 1);
448 ubifs_assert(req->new_ino <= 1);
449 ubifs_assert(req->new_ino_d <= UBIFS_MAX_INO_DATA);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300450 ubifs_assert(req->dirtied_ino <= 4);
451 ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4);
Artem Bityutskiydab4b4d2008-07-24 14:52:45 +0300452 ubifs_assert(!(req->new_ino_d & 7));
453 ubifs_assert(!(req->dirtied_ino_d & 7));
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300454
455 data_growth = calc_data_growth(c, req);
456 dd_growth = calc_dd_growth(c, req);
457 if (!data_growth && !dd_growth)
458 return 0;
459 idx_growth = calc_idx_growth(c, req);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300460
461again:
462 spin_lock(&c->space_lock);
463 ubifs_assert(c->budg_idx_growth >= 0);
464 ubifs_assert(c->budg_data_growth >= 0);
465 ubifs_assert(c->budg_dd_growth >= 0);
466
467 if (unlikely(c->nospace) && (c->nospace_rp || !can_use_rp(c))) {
468 dbg_budg("no space");
469 spin_unlock(&c->space_lock);
470 return -ENOSPC;
471 }
472
473 c->budg_idx_growth += idx_growth;
474 c->budg_data_growth += data_growth;
475 c->budg_dd_growth += dd_growth;
476
477 err = do_budget_space(c);
478 if (likely(!err)) {
479 req->idx_growth = idx_growth;
480 req->data_growth = data_growth;
481 req->dd_growth = dd_growth;
482 spin_unlock(&c->space_lock);
483 return 0;
484 }
485
486 /* Restore the old values */
487 c->budg_idx_growth -= idx_growth;
488 c->budg_data_growth -= data_growth;
489 c->budg_dd_growth -= dd_growth;
490 spin_unlock(&c->space_lock);
491
492 if (req->fast) {
493 dbg_budg("no space for fast budgeting");
494 return err;
495 }
496
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500497 err = make_free_space(c);
498 cond_resched();
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300499 if (err == -EAGAIN) {
500 dbg_budg("try again");
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300501 goto again;
502 } else if (err == -ENOSPC) {
Artem Bityutskiy2acf8062008-12-09 11:04:40 -0500503 if (!retried) {
504 retried = 1;
505 dbg_budg("-ENOSPC, but anyway try once again");
506 goto again;
507 }
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300508 dbg_budg("FS is full, -ENOSPC");
509 c->nospace = 1;
510 if (can_use_rp(c) || c->rp_size == 0)
511 c->nospace_rp = 1;
512 smp_wmb();
513 } else
514 ubifs_err("cannot budget space, error %d", err);
515 return err;
516}
517
518/**
519 * ubifs_release_budget - release budgeted free space.
520 * @c: UBIFS file-system description object
521 * @req: budget request
522 *
523 * This function releases the space budgeted by 'ubifs_budget_space()'. Note,
524 * since the index changes (which were budgeted for in @req->idx_growth) will
525 * only be written to the media on commit, this function moves the index budget
526 * from @c->budg_idx_growth to @c->budg_uncommitted_idx. The latter will be
527 * zeroed by the commit operation.
528 */
529void ubifs_release_budget(struct ubifs_info *c, struct ubifs_budget_req *req)
530{
Artem Bityutskiy547000d2008-07-24 14:42:05 +0300531 ubifs_assert(req->new_page <= 1);
532 ubifs_assert(req->dirtied_page <= 1);
533 ubifs_assert(req->new_dent <= 1);
534 ubifs_assert(req->mod_dent <= 1);
535 ubifs_assert(req->new_ino <= 1);
536 ubifs_assert(req->new_ino_d <= UBIFS_MAX_INO_DATA);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300537 ubifs_assert(req->dirtied_ino <= 4);
538 ubifs_assert(req->dirtied_ino_d <= UBIFS_MAX_INO_DATA * 4);
Artem Bityutskiydab4b4d2008-07-24 14:52:45 +0300539 ubifs_assert(!(req->new_ino_d & 7));
540 ubifs_assert(!(req->dirtied_ino_d & 7));
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300541 if (!req->recalculate) {
542 ubifs_assert(req->idx_growth >= 0);
543 ubifs_assert(req->data_growth >= 0);
544 ubifs_assert(req->dd_growth >= 0);
545 }
546
547 if (req->recalculate) {
548 req->data_growth = calc_data_growth(c, req);
549 req->dd_growth = calc_dd_growth(c, req);
550 req->idx_growth = calc_idx_growth(c, req);
551 }
552
553 if (!req->data_growth && !req->dd_growth)
554 return;
555
556 c->nospace = c->nospace_rp = 0;
557 smp_wmb();
558
559 spin_lock(&c->space_lock);
560 c->budg_idx_growth -= req->idx_growth;
561 c->budg_uncommitted_idx += req->idx_growth;
562 c->budg_data_growth -= req->data_growth;
563 c->budg_dd_growth -= req->dd_growth;
564 c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);
565
566 ubifs_assert(c->budg_idx_growth >= 0);
567 ubifs_assert(c->budg_data_growth >= 0);
Artem Bityutskiydab4b4d2008-07-24 14:52:45 +0300568 ubifs_assert(c->budg_dd_growth >= 0);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300569 ubifs_assert(c->min_idx_lebs < c->main_lebs);
Artem Bityutskiydab4b4d2008-07-24 14:52:45 +0300570 ubifs_assert(!(c->budg_idx_growth & 7));
571 ubifs_assert(!(c->budg_data_growth & 7));
572 ubifs_assert(!(c->budg_dd_growth & 7));
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300573 spin_unlock(&c->space_lock);
574}
575
576/**
577 * ubifs_convert_page_budget - convert budget of a new page.
578 * @c: UBIFS file-system description object
579 *
580 * This function converts budget which was allocated for a new page of data to
Frederik Schwarzer025dfda2008-10-16 19:02:37 +0200581 * the budget of changing an existing page of data. The latter is smaller than
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300582 * the former, so this function only does simple re-calculation and does not
583 * involve any write-back.
584 */
585void ubifs_convert_page_budget(struct ubifs_info *c)
586{
587 spin_lock(&c->space_lock);
588 /* Release the index growth reservation */
589 c->budg_idx_growth -= c->max_idx_node_sz << UBIFS_BLOCKS_PER_PAGE_SHIFT;
590 /* Release the data growth reservation */
591 c->budg_data_growth -= c->page_budget;
592 /* Increase the dirty data growth reservation instead */
593 c->budg_dd_growth += c->page_budget;
594 /* And re-calculate the indexing space reservation */
595 c->min_idx_lebs = ubifs_calc_min_idx_lebs(c);
596 spin_unlock(&c->space_lock);
597}
598
599/**
600 * ubifs_release_dirty_inode_budget - release dirty inode budget.
601 * @c: UBIFS file-system description object
602 * @ui: UBIFS inode to release the budget for
603 *
604 * This function releases budget corresponding to a dirty inode. It is usually
605 * called when after the inode has been written to the media and marked as
Adrian Hunter6d6cb0d2009-04-08 14:07:57 +0200606 * clean. It also causes the "no space" flags to be cleared.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300607 */
608void ubifs_release_dirty_inode_budget(struct ubifs_info *c,
609 struct ubifs_inode *ui)
610{
Artem Bityutskiy182854b2008-07-18 18:54:29 +0300611 struct ubifs_budget_req req;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300612
Artem Bityutskiy182854b2008-07-18 18:54:29 +0300613 memset(&req, 0, sizeof(struct ubifs_budget_req));
Adrian Hunter6d6cb0d2009-04-08 14:07:57 +0200614 /* The "no space" flags will be cleared because dd_growth is > 0 */
Artem Bityutskiydab4b4d2008-07-24 14:52:45 +0300615 req.dd_growth = c->inode_budget + ALIGN(ui->data_len, 8);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300616 ubifs_release_budget(c, &req);
617}
618
619/**
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300620 * ubifs_reported_space - calculate reported free space.
621 * @c: the UBIFS file-system description object
622 * @free: amount of free space
623 *
624 * This function calculates amount of free space which will be reported to
625 * user-space. User-space application tend to expect that if the file-system
626 * (e.g., via the 'statfs()' call) reports that it has N bytes available, they
627 * are able to write a file of size N. UBIFS attaches node headers to each data
Artem Bityutskiy80736d42008-12-30 17:44:02 +0200628 * node and it has to write indexing nodes as well. This introduces additional
629 * overhead, and UBIFS has to report slightly less free space to meet the above
630 * expectations.
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300631 *
632 * This function assumes free space is made up of uncompressed data nodes and
633 * full index nodes (one per data node, tripled because we always allow enough
634 * space to write the index thrice).
635 *
636 * Note, the calculation is pessimistic, which means that most of the time
637 * UBIFS reports less space than it actually has.
638 */
Artem Bityutskiy4d61db42008-12-18 14:06:51 +0200639long long ubifs_reported_space(const struct ubifs_info *c, long long free)
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300640{
Artem Bityutskiyf171d4d2008-09-03 16:17:14 +0300641 int divisor, factor, f;
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300642
643 /*
644 * Reported space size is @free * X, where X is UBIFS block size
645 * divided by UBIFS block size + all overhead one data block
646 * introduces. The overhead is the node header + indexing overhead.
647 *
Artem Bityutskiyf171d4d2008-09-03 16:17:14 +0300648 * Indexing overhead calculations are based on the following formula:
649 * I = N/(f - 1) + 1, where I - number of indexing nodes, N - number
650 * of data nodes, f - fanout. Because effective UBIFS fanout is twice
651 * as less than maximum fanout, we assume that each data node
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300652 * introduces 3 * @c->max_idx_node_sz / (@c->fanout/2 - 1) bytes.
Artem Bityutskiy80736d42008-12-30 17:44:02 +0200653 * Note, the multiplier 3 is because UBIFS reserves thrice as more space
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300654 * for the index.
655 */
Artem Bityutskiyf171d4d2008-09-03 16:17:14 +0300656 f = c->fanout > 3 ? c->fanout >> 1 : 2;
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300657 factor = UBIFS_BLOCK_SIZE;
658 divisor = UBIFS_MAX_DATA_NODE_SZ;
Artem Bityutskiyf171d4d2008-09-03 16:17:14 +0300659 divisor += (c->max_idx_node_sz * 3) / (f - 1);
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300660 free *= factor;
Artem Bityutskiy4d61db42008-12-18 14:06:51 +0200661 return div_u64(free, divisor);
Artem Bityutskiy4b5f2762008-08-25 16:15:56 +0300662}
663
664/**
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200665 * ubifs_get_free_space_nolock - return amount of free space.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300666 * @c: UBIFS file-system description object
667 *
Artem Bityutskiy7dad1812008-08-25 18:58:19 +0300668 * This function calculates amount of free space to report to user-space.
669 *
670 * Because UBIFS may introduce substantial overhead (the index, node headers,
Artem Bityutskiyfb1cd012009-03-16 09:56:57 +0200671 * alignment, wastage at the end of LEBs, etc), it cannot report real amount of
672 * free flash space it has (well, because not all dirty space is reclaimable,
673 * UBIFS does not actually know the real amount). If UBIFS did so, it would
674 * bread user expectations about what free space is. Users seem to accustomed
675 * to assume that if the file-system reports N bytes of free space, they would
676 * be able to fit a file of N bytes to the FS. This almost works for
Artem Bityutskiy7dad1812008-08-25 18:58:19 +0300677 * traditional file-systems, because they have way less overhead than UBIFS.
678 * So, to keep users happy, UBIFS tries to take the overhead into account.
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300679 */
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200680long long ubifs_get_free_space_nolock(struct ubifs_info *c)
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300681{
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200682 int rsvd_idx_lebs, lebs;
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300683 long long available, outstanding, free;
684
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200685 ubifs_assert(c->min_idx_lebs == ubifs_calc_min_idx_lebs(c));
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300686 outstanding = c->budg_data_growth + c->budg_dd_growth;
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200687 available = ubifs_calc_available(c, c->min_idx_lebs);
Artem Bityutskiy7dad1812008-08-25 18:58:19 +0300688
689 /*
690 * When reporting free space to user-space, UBIFS guarantees that it is
691 * possible to write a file of free space size. This means that for
692 * empty LEBs we may use more precise calculations than
693 * 'ubifs_calc_available()' is using. Namely, we know that in empty
694 * LEBs we would waste only @c->leb_overhead bytes, not @c->dark_wm.
695 * Thus, amend the available space.
696 *
697 * Note, the calculations below are similar to what we have in
698 * 'do_budget_space()', so refer there for comments.
699 */
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200700 if (c->min_idx_lebs > c->lst.idx_lebs)
701 rsvd_idx_lebs = c->min_idx_lebs - c->lst.idx_lebs;
Artem Bityutskiy7dad1812008-08-25 18:58:19 +0300702 else
703 rsvd_idx_lebs = 0;
704 lebs = c->lst.empty_lebs + c->freeable_cnt + c->idx_gc_cnt -
705 c->lst.taken_empty_lebs;
706 lebs -= rsvd_idx_lebs;
707 available += lebs * (c->dark_wm - c->leb_overhead);
Artem Bityutskiy1e517642008-07-14 19:08:37 +0300708
709 if (available > outstanding)
710 free = ubifs_reported_space(c, available - outstanding);
711 else
712 free = 0;
713 return free;
714}
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200715
716/**
717 * ubifs_get_free_space - return amount of free space.
718 * @c: UBIFS file-system description object
719 *
Artem Bityutskiy055da1b2009-09-15 17:09:24 +0300720 * This function calculates and returns amount of free space to report to
Artem Bityutskiy84abf972009-01-23 14:54:59 +0200721 * user-space.
722 */
723long long ubifs_get_free_space(struct ubifs_info *c)
724{
725 long long free;
726
727 spin_lock(&c->space_lock);
728 free = ubifs_get_free_space_nolock(c);
729 spin_unlock(&c->space_lock);
730
731 return free;
732}