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disable some mediatekl custom warnings
[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / xfs / xfs_extent_busy.c
1 /*
2 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
3 * Copyright (c) 2010 David Chinner.
4 * Copyright (c) 2011 Christoph Hellwig.
5 * All Rights Reserved.
6 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License as
9 * published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it would be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
19 */
20 #include "xfs.h"
21 #include "xfs_fs.h"
22 #include "xfs_types.h"
23 #include "xfs_log.h"
24 #include "xfs_trans.h"
25 #include "xfs_sb.h"
26 #include "xfs_ag.h"
27 #include "xfs_mount.h"
28 #include "xfs_bmap_btree.h"
29 #include "xfs_alloc.h"
30 #include "xfs_inode.h"
31 #include "xfs_extent_busy.h"
32 #include "xfs_trace.h"
33
34 void
35 xfs_extent_busy_insert(
36 struct xfs_trans *tp,
37 xfs_agnumber_t agno,
38 xfs_agblock_t bno,
39 xfs_extlen_t len,
40 unsigned int flags)
41 {
42 struct xfs_extent_busy *new;
43 struct xfs_extent_busy *busyp;
44 struct xfs_perag *pag;
45 struct rb_node **rbp;
46 struct rb_node *parent = NULL;
47
48 new = kmem_zalloc(sizeof(struct xfs_extent_busy), KM_MAYFAIL);
49 if (!new) {
50 /*
51 * No Memory! Since it is now not possible to track the free
52 * block, make this a synchronous transaction to insure that
53 * the block is not reused before this transaction commits.
54 */
55 trace_xfs_extent_busy_enomem(tp->t_mountp, agno, bno, len);
56 xfs_trans_set_sync(tp);
57 return;
58 }
59
60 new->agno = agno;
61 new->bno = bno;
62 new->length = len;
63 INIT_LIST_HEAD(&new->list);
64 new->flags = flags;
65
66 /* trace before insert to be able to see failed inserts */
67 trace_xfs_extent_busy(tp->t_mountp, agno, bno, len);
68
69 pag = xfs_perag_get(tp->t_mountp, new->agno);
70 spin_lock(&pag->pagb_lock);
71 rbp = &pag->pagb_tree.rb_node;
72 while (*rbp) {
73 parent = *rbp;
74 busyp = rb_entry(parent, struct xfs_extent_busy, rb_node);
75
76 if (new->bno < busyp->bno) {
77 rbp = &(*rbp)->rb_left;
78 ASSERT(new->bno + new->length <= busyp->bno);
79 } else if (new->bno > busyp->bno) {
80 rbp = &(*rbp)->rb_right;
81 ASSERT(bno >= busyp->bno + busyp->length);
82 } else {
83 ASSERT(0);
84 }
85 }
86
87 rb_link_node(&new->rb_node, parent, rbp);
88 rb_insert_color(&new->rb_node, &pag->pagb_tree);
89
90 list_add(&new->list, &tp->t_busy);
91 spin_unlock(&pag->pagb_lock);
92 xfs_perag_put(pag);
93 }
94
95 /*
96 * Search for a busy extent within the range of the extent we are about to
97 * allocate. You need to be holding the busy extent tree lock when calling
98 * xfs_extent_busy_search(). This function returns 0 for no overlapping busy
99 * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact
100 * match. This is done so that a non-zero return indicates an overlap that
101 * will require a synchronous transaction, but it can still be
102 * used to distinguish between a partial or exact match.
103 */
104 int
105 xfs_extent_busy_search(
106 struct xfs_mount *mp,
107 xfs_agnumber_t agno,
108 xfs_agblock_t bno,
109 xfs_extlen_t len)
110 {
111 struct xfs_perag *pag;
112 struct rb_node *rbp;
113 struct xfs_extent_busy *busyp;
114 int match = 0;
115
116 pag = xfs_perag_get(mp, agno);
117 spin_lock(&pag->pagb_lock);
118
119 rbp = pag->pagb_tree.rb_node;
120
121 /* find closest start bno overlap */
122 while (rbp) {
123 busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node);
124 if (bno < busyp->bno) {
125 /* may overlap, but exact start block is lower */
126 if (bno + len > busyp->bno)
127 match = -1;
128 rbp = rbp->rb_left;
129 } else if (bno > busyp->bno) {
130 /* may overlap, but exact start block is higher */
131 if (bno < busyp->bno + busyp->length)
132 match = -1;
133 rbp = rbp->rb_right;
134 } else {
135 /* bno matches busyp, length determines exact match */
136 match = (busyp->length == len) ? 1 : -1;
137 break;
138 }
139 }
140 spin_unlock(&pag->pagb_lock);
141 xfs_perag_put(pag);
142 return match;
143 }
144
145 /*
146 * The found free extent [fbno, fend] overlaps part or all of the given busy
147 * extent. If the overlap covers the beginning, the end, or all of the busy
148 * extent, the overlapping portion can be made unbusy and used for the
149 * allocation. We can't split a busy extent because we can't modify a
150 * transaction/CIL context busy list, but we can update an entries block
151 * number or length.
152 *
153 * Returns true if the extent can safely be reused, or false if the search
154 * needs to be restarted.
155 */
156 STATIC bool
157 xfs_extent_busy_update_extent(
158 struct xfs_mount *mp,
159 struct xfs_perag *pag,
160 struct xfs_extent_busy *busyp,
161 xfs_agblock_t fbno,
162 xfs_extlen_t flen,
163 bool userdata)
164 {
165 xfs_agblock_t fend = fbno + flen;
166 xfs_agblock_t bbno = busyp->bno;
167 xfs_agblock_t bend = bbno + busyp->length;
168
169 /*
170 * This extent is currently being discarded. Give the thread
171 * performing the discard a chance to mark the extent unbusy
172 * and retry.
173 */
174 if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) {
175 spin_unlock(&pag->pagb_lock);
176 delay(1);
177 spin_lock(&pag->pagb_lock);
178 return false;
179 }
180
181 /*
182 * If there is a busy extent overlapping a user allocation, we have
183 * no choice but to force the log and retry the search.
184 *
185 * Fortunately this does not happen during normal operation, but
186 * only if the filesystem is very low on space and has to dip into
187 * the AGFL for normal allocations.
188 */
189 if (userdata)
190 goto out_force_log;
191
192 if (bbno < fbno && bend > fend) {
193 /*
194 * Case 1:
195 * bbno bend
196 * +BBBBBBBBBBBBBBBBB+
197 * +---------+
198 * fbno fend
199 */
200
201 /*
202 * We would have to split the busy extent to be able to track
203 * it correct, which we cannot do because we would have to
204 * modify the list of busy extents attached to the transaction
205 * or CIL context, which is immutable.
206 *
207 * Force out the log to clear the busy extent and retry the
208 * search.
209 */
210 goto out_force_log;
211 } else if (bbno >= fbno && bend <= fend) {
212 /*
213 * Case 2:
214 * bbno bend
215 * +BBBBBBBBBBBBBBBBB+
216 * +-----------------+
217 * fbno fend
218 *
219 * Case 3:
220 * bbno bend
221 * +BBBBBBBBBBBBBBBBB+
222 * +--------------------------+
223 * fbno fend
224 *
225 * Case 4:
226 * bbno bend
227 * +BBBBBBBBBBBBBBBBB+
228 * +--------------------------+
229 * fbno fend
230 *
231 * Case 5:
232 * bbno bend
233 * +BBBBBBBBBBBBBBBBB+
234 * +-----------------------------------+
235 * fbno fend
236 *
237 */
238
239 /*
240 * The busy extent is fully covered by the extent we are
241 * allocating, and can simply be removed from the rbtree.
242 * However we cannot remove it from the immutable list
243 * tracking busy extents in the transaction or CIL context,
244 * so set the length to zero to mark it invalid.
245 *
246 * We also need to restart the busy extent search from the
247 * tree root, because erasing the node can rearrange the
248 * tree topology.
249 */
250 rb_erase(&busyp->rb_node, &pag->pagb_tree);
251 busyp->length = 0;
252 return false;
253 } else if (fend < bend) {
254 /*
255 * Case 6:
256 * bbno bend
257 * +BBBBBBBBBBBBBBBBB+
258 * +---------+
259 * fbno fend
260 *
261 * Case 7:
262 * bbno bend
263 * +BBBBBBBBBBBBBBBBB+
264 * +------------------+
265 * fbno fend
266 *
267 */
268 busyp->bno = fend;
269 } else if (bbno < fbno) {
270 /*
271 * Case 8:
272 * bbno bend
273 * +BBBBBBBBBBBBBBBBB+
274 * +-------------+
275 * fbno fend
276 *
277 * Case 9:
278 * bbno bend
279 * +BBBBBBBBBBBBBBBBB+
280 * +----------------------+
281 * fbno fend
282 */
283 busyp->length = fbno - busyp->bno;
284 } else {
285 ASSERT(0);
286 }
287
288 trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen);
289 return true;
290
291 out_force_log:
292 spin_unlock(&pag->pagb_lock);
293 xfs_log_force(mp, XFS_LOG_SYNC);
294 trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen);
295 spin_lock(&pag->pagb_lock);
296 return false;
297 }
298
299
300 /*
301 * For a given extent [fbno, flen], make sure we can reuse it safely.
302 */
303 void
304 xfs_extent_busy_reuse(
305 struct xfs_mount *mp,
306 xfs_agnumber_t agno,
307 xfs_agblock_t fbno,
308 xfs_extlen_t flen,
309 bool userdata)
310 {
311 struct xfs_perag *pag;
312 struct rb_node *rbp;
313
314 ASSERT(flen > 0);
315
316 pag = xfs_perag_get(mp, agno);
317 spin_lock(&pag->pagb_lock);
318 restart:
319 rbp = pag->pagb_tree.rb_node;
320 while (rbp) {
321 struct xfs_extent_busy *busyp =
322 rb_entry(rbp, struct xfs_extent_busy, rb_node);
323 xfs_agblock_t bbno = busyp->bno;
324 xfs_agblock_t bend = bbno + busyp->length;
325
326 if (fbno + flen <= bbno) {
327 rbp = rbp->rb_left;
328 continue;
329 } else if (fbno >= bend) {
330 rbp = rbp->rb_right;
331 continue;
332 }
333
334 if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen,
335 userdata))
336 goto restart;
337 }
338 spin_unlock(&pag->pagb_lock);
339 xfs_perag_put(pag);
340 }
341
342 /*
343 * For a given extent [fbno, flen], search the busy extent list to find a
344 * subset of the extent that is not busy. If *rlen is smaller than
345 * args->minlen no suitable extent could be found, and the higher level
346 * code needs to force out the log and retry the allocation.
347 */
348 void
349 xfs_extent_busy_trim(
350 struct xfs_alloc_arg *args,
351 xfs_agblock_t bno,
352 xfs_extlen_t len,
353 xfs_agblock_t *rbno,
354 xfs_extlen_t *rlen)
355 {
356 xfs_agblock_t fbno;
357 xfs_extlen_t flen;
358 struct rb_node *rbp;
359
360 ASSERT(len > 0);
361
362 spin_lock(&args->pag->pagb_lock);
363 restart:
364 fbno = bno;
365 flen = len;
366 rbp = args->pag->pagb_tree.rb_node;
367 while (rbp && flen >= args->minlen) {
368 struct xfs_extent_busy *busyp =
369 rb_entry(rbp, struct xfs_extent_busy, rb_node);
370 xfs_agblock_t fend = fbno + flen;
371 xfs_agblock_t bbno = busyp->bno;
372 xfs_agblock_t bend = bbno + busyp->length;
373
374 if (fend <= bbno) {
375 rbp = rbp->rb_left;
376 continue;
377 } else if (fbno >= bend) {
378 rbp = rbp->rb_right;
379 continue;
380 }
381
382 /*
383 * If this is a metadata allocation, try to reuse the busy
384 * extent instead of trimming the allocation.
385 */
386 if (!args->userdata &&
387 !(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) {
388 if (!xfs_extent_busy_update_extent(args->mp, args->pag,
389 busyp, fbno, flen,
390 false))
391 goto restart;
392 continue;
393 }
394
395 if (bbno <= fbno) {
396 /* start overlap */
397
398 /*
399 * Case 1:
400 * bbno bend
401 * +BBBBBBBBBBBBBBBBB+
402 * +---------+
403 * fbno fend
404 *
405 * Case 2:
406 * bbno bend
407 * +BBBBBBBBBBBBBBBBB+
408 * +-------------+
409 * fbno fend
410 *
411 * Case 3:
412 * bbno bend
413 * +BBBBBBBBBBBBBBBBB+
414 * +-------------+
415 * fbno fend
416 *
417 * Case 4:
418 * bbno bend
419 * +BBBBBBBBBBBBBBBBB+
420 * +-----------------+
421 * fbno fend
422 *
423 * No unbusy region in extent, return failure.
424 */
425 if (fend <= bend)
426 goto fail;
427
428 /*
429 * Case 5:
430 * bbno bend
431 * +BBBBBBBBBBBBBBBBB+
432 * +----------------------+
433 * fbno fend
434 *
435 * Case 6:
436 * bbno bend
437 * +BBBBBBBBBBBBBBBBB+
438 * +--------------------------+
439 * fbno fend
440 *
441 * Needs to be trimmed to:
442 * +-------+
443 * fbno fend
444 */
445 fbno = bend;
446 } else if (bend >= fend) {
447 /* end overlap */
448
449 /*
450 * Case 7:
451 * bbno bend
452 * +BBBBBBBBBBBBBBBBB+
453 * +------------------+
454 * fbno fend
455 *
456 * Case 8:
457 * bbno bend
458 * +BBBBBBBBBBBBBBBBB+
459 * +--------------------------+
460 * fbno fend
461 *
462 * Needs to be trimmed to:
463 * +-------+
464 * fbno fend
465 */
466 fend = bbno;
467 } else {
468 /* middle overlap */
469
470 /*
471 * Case 9:
472 * bbno bend
473 * +BBBBBBBBBBBBBBBBB+
474 * +-----------------------------------+
475 * fbno fend
476 *
477 * Can be trimmed to:
478 * +-------+ OR +-------+
479 * fbno fend fbno fend
480 *
481 * Backward allocation leads to significant
482 * fragmentation of directories, which degrades
483 * directory performance, therefore we always want to
484 * choose the option that produces forward allocation
485 * patterns.
486 * Preferring the lower bno extent will make the next
487 * request use "fend" as the start of the next
488 * allocation; if the segment is no longer busy at
489 * that point, we'll get a contiguous allocation, but
490 * even if it is still busy, we will get a forward
491 * allocation.
492 * We try to avoid choosing the segment at "bend",
493 * because that can lead to the next allocation
494 * taking the segment at "fbno", which would be a
495 * backward allocation. We only use the segment at
496 * "fbno" if it is much larger than the current
497 * requested size, because in that case there's a
498 * good chance subsequent allocations will be
499 * contiguous.
500 */
501 if (bbno - fbno >= args->maxlen) {
502 /* left candidate fits perfect */
503 fend = bbno;
504 } else if (fend - bend >= args->maxlen * 4) {
505 /* right candidate has enough free space */
506 fbno = bend;
507 } else if (bbno - fbno >= args->minlen) {
508 /* left candidate fits minimum requirement */
509 fend = bbno;
510 } else {
511 goto fail;
512 }
513 }
514
515 flen = fend - fbno;
516 }
517 spin_unlock(&args->pag->pagb_lock);
518
519 if (fbno != bno || flen != len) {
520 trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len,
521 fbno, flen);
522 }
523 *rbno = fbno;
524 *rlen = flen;
525 return;
526 fail:
527 /*
528 * Return a zero extent length as failure indications. All callers
529 * re-check if the trimmed extent satisfies the minlen requirement.
530 */
531 spin_unlock(&args->pag->pagb_lock);
532 trace_xfs_extent_busy_trim(args->mp, args->agno, bno, len, fbno, 0);
533 *rbno = fbno;
534 *rlen = 0;
535 }
536
537 STATIC void
538 xfs_extent_busy_clear_one(
539 struct xfs_mount *mp,
540 struct xfs_perag *pag,
541 struct xfs_extent_busy *busyp)
542 {
543 if (busyp->length) {
544 trace_xfs_extent_busy_clear(mp, busyp->agno, busyp->bno,
545 busyp->length);
546 rb_erase(&busyp->rb_node, &pag->pagb_tree);
547 }
548
549 list_del_init(&busyp->list);
550 kmem_free(busyp);
551 }
552
553 /*
554 * Remove all extents on the passed in list from the busy extents tree.
555 * If do_discard is set skip extents that need to be discarded, and mark
556 * these as undergoing a discard operation instead.
557 */
558 void
559 xfs_extent_busy_clear(
560 struct xfs_mount *mp,
561 struct list_head *list,
562 bool do_discard)
563 {
564 struct xfs_extent_busy *busyp, *n;
565 struct xfs_perag *pag = NULL;
566 xfs_agnumber_t agno = NULLAGNUMBER;
567
568 list_for_each_entry_safe(busyp, n, list, list) {
569 if (busyp->agno != agno) {
570 if (pag) {
571 spin_unlock(&pag->pagb_lock);
572 xfs_perag_put(pag);
573 }
574 pag = xfs_perag_get(mp, busyp->agno);
575 spin_lock(&pag->pagb_lock);
576 agno = busyp->agno;
577 }
578
579 if (do_discard && busyp->length &&
580 !(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD))
581 busyp->flags = XFS_EXTENT_BUSY_DISCARDED;
582 else
583 xfs_extent_busy_clear_one(mp, pag, busyp);
584 }
585
586 if (pag) {
587 spin_unlock(&pag->pagb_lock);
588 xfs_perag_put(pag);
589 }
590 }
591
592 /*
593 * Callback for list_sort to sort busy extents by the AG they reside in.
594 */
595 int
596 xfs_extent_busy_ag_cmp(
597 void *priv,
598 struct list_head *a,
599 struct list_head *b)
600 {
601 return container_of(a, struct xfs_extent_busy, list)->agno -
602 container_of(b, struct xfs_extent_busy, list)->agno;
603 }
kernel source for telekom puls (alcatel/mediatek)