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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright (c) 2000-2002,2005 Silicon Graphics, Inc.
4 * Copyright (c) 2010 David Chinner.
5 * Copyright (c) 2011 Christoph Hellwig.
6 * All Rights Reserved.
7 */
8#include "xfs.h"
9#include "xfs_fs.h"
10#include "xfs_format.h"
11#include "xfs_log_format.h"
12#include "xfs_shared.h"
13#include "xfs_trans_resv.h"
14#include "xfs_sb.h"
15#include "xfs_mount.h"
16#include "xfs_alloc.h"
17#include "xfs_extent_busy.h"
18#include "xfs_trace.h"
19#include "xfs_trans.h"
20#include "xfs_log.h"
21
22void
23xfs_extent_busy_insert(
24 struct xfs_trans *tp,
25 xfs_agnumber_t agno,
26 xfs_agblock_t bno,
27 xfs_extlen_t len,
28 unsigned int flags)
29{
30 struct xfs_extent_busy *new;
31 struct xfs_extent_busy *busyp;
32 struct xfs_perag *pag;
33 struct rb_node **rbp;
34 struct rb_node *parent = NULL;
35
36 new = kmem_zalloc(sizeof(struct xfs_extent_busy), 0);
37 new->agno = agno;
38 new->bno = bno;
39 new->length = len;
40 INIT_LIST_HEAD(&new->list);
41 new->flags = flags;
42
43 /* trace before insert to be able to see failed inserts */
44 trace_xfs_extent_busy(tp->t_mountp, agno, bno, len);
45
46 pag = xfs_perag_get(tp->t_mountp, new->agno);
47 spin_lock(&pag->pagb_lock);
48 rbp = &pag->pagb_tree.rb_node;
49 while (*rbp) {
50 parent = *rbp;
51 busyp = rb_entry(parent, struct xfs_extent_busy, rb_node);
52
53 if (new->bno < busyp->bno) {
54 rbp = &(*rbp)->rb_left;
55 ASSERT(new->bno + new->length <= busyp->bno);
56 } else if (new->bno > busyp->bno) {
57 rbp = &(*rbp)->rb_right;
58 ASSERT(bno >= busyp->bno + busyp->length);
59 } else {
60 ASSERT(0);
61 }
62 }
63
64 rb_link_node(&new->rb_node, parent, rbp);
65 rb_insert_color(&new->rb_node, &pag->pagb_tree);
66
67 list_add(&new->list, &tp->t_busy);
68 spin_unlock(&pag->pagb_lock);
69 xfs_perag_put(pag);
70}
71
72/*
73 * Search for a busy extent within the range of the extent we are about to
74 * allocate. You need to be holding the busy extent tree lock when calling
75 * xfs_extent_busy_search(). This function returns 0 for no overlapping busy
76 * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact
77 * match. This is done so that a non-zero return indicates an overlap that
78 * will require a synchronous transaction, but it can still be
79 * used to distinguish between a partial or exact match.
80 */
81int
82xfs_extent_busy_search(
83 struct xfs_mount *mp,
84 xfs_agnumber_t agno,
85 xfs_agblock_t bno,
86 xfs_extlen_t len)
87{
88 struct xfs_perag *pag;
89 struct rb_node *rbp;
90 struct xfs_extent_busy *busyp;
91 int match = 0;
92
93 pag = xfs_perag_get(mp, agno);
94 spin_lock(&pag->pagb_lock);
95
96 rbp = pag->pagb_tree.rb_node;
97
98 /* find closest start bno overlap */
99 while (rbp) {
100 busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node);
101 if (bno < busyp->bno) {
102 /* may overlap, but exact start block is lower */
103 if (bno + len > busyp->bno)
104 match = -1;
105 rbp = rbp->rb_left;
106 } else if (bno > busyp->bno) {
107 /* may overlap, but exact start block is higher */
108 if (bno < busyp->bno + busyp->length)
109 match = -1;
110 rbp = rbp->rb_right;
111 } else {
112 /* bno matches busyp, length determines exact match */
113 match = (busyp->length == len) ? 1 : -1;
114 break;
115 }
116 }
117 spin_unlock(&pag->pagb_lock);
118 xfs_perag_put(pag);
119 return match;
120}
121
122/*
123 * The found free extent [fbno, fend] overlaps part or all of the given busy
124 * extent. If the overlap covers the beginning, the end, or all of the busy
125 * extent, the overlapping portion can be made unbusy and used for the
126 * allocation. We can't split a busy extent because we can't modify a
127 * transaction/CIL context busy list, but we can update an entry's block
128 * number or length.
129 *
130 * Returns true if the extent can safely be reused, or false if the search
131 * needs to be restarted.
132 */
133STATIC bool
134xfs_extent_busy_update_extent(
135 struct xfs_mount *mp,
136 struct xfs_perag *pag,
137 struct xfs_extent_busy *busyp,
138 xfs_agblock_t fbno,
139 xfs_extlen_t flen,
140 bool userdata) __releases(&pag->pagb_lock)
141 __acquires(&pag->pagb_lock)
142{
143 xfs_agblock_t fend = fbno + flen;
144 xfs_agblock_t bbno = busyp->bno;
145 xfs_agblock_t bend = bbno + busyp->length;
146
147 /*
148 * This extent is currently being discarded. Give the thread
149 * performing the discard a chance to mark the extent unbusy
150 * and retry.
151 */
152 if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) {
153 spin_unlock(&pag->pagb_lock);
154 delay(1);
155 spin_lock(&pag->pagb_lock);
156 return false;
157 }
158
159 /*
160 * If there is a busy extent overlapping a user allocation, we have
161 * no choice but to force the log and retry the search.
162 *
163 * Fortunately this does not happen during normal operation, but
164 * only if the filesystem is very low on space and has to dip into
165 * the AGFL for normal allocations.
166 */
167 if (userdata)
168 goto out_force_log;
169
170 if (bbno < fbno && bend > fend) {
171 /*
172 * Case 1:
173 * bbno bend
174 * +BBBBBBBBBBBBBBBBB+
175 * +---------+
176 * fbno fend
177 */
178
179 /*
180 * We would have to split the busy extent to be able to track
181 * it correct, which we cannot do because we would have to
182 * modify the list of busy extents attached to the transaction
183 * or CIL context, which is immutable.
184 *
185 * Force out the log to clear the busy extent and retry the
186 * search.
187 */
188 goto out_force_log;
189 } else if (bbno >= fbno && bend <= fend) {
190 /*
191 * Case 2:
192 * bbno bend
193 * +BBBBBBBBBBBBBBBBB+
194 * +-----------------+
195 * fbno fend
196 *
197 * Case 3:
198 * bbno bend
199 * +BBBBBBBBBBBBBBBBB+
200 * +--------------------------+
201 * fbno fend
202 *
203 * Case 4:
204 * bbno bend
205 * +BBBBBBBBBBBBBBBBB+
206 * +--------------------------+
207 * fbno fend
208 *
209 * Case 5:
210 * bbno bend
211 * +BBBBBBBBBBBBBBBBB+
212 * +-----------------------------------+
213 * fbno fend
214 *
215 */
216
217 /*
218 * The busy extent is fully covered by the extent we are
219 * allocating, and can simply be removed from the rbtree.
220 * However we cannot remove it from the immutable list
221 * tracking busy extents in the transaction or CIL context,
222 * so set the length to zero to mark it invalid.
223 *
224 * We also need to restart the busy extent search from the
225 * tree root, because erasing the node can rearrange the
226 * tree topology.
227 */
228 rb_erase(&busyp->rb_node, &pag->pagb_tree);
229 busyp->length = 0;
230 return false;
231 } else if (fend < bend) {
232 /*
233 * Case 6:
234 * bbno bend
235 * +BBBBBBBBBBBBBBBBB+
236 * +---------+
237 * fbno fend
238 *
239 * Case 7:
240 * bbno bend
241 * +BBBBBBBBBBBBBBBBB+
242 * +------------------+
243 * fbno fend
244 *
245 */
246 busyp->bno = fend;
247 } else if (bbno < fbno) {
248 /*
249 * Case 8:
250 * bbno bend
251 * +BBBBBBBBBBBBBBBBB+
252 * +-------------+
253 * fbno fend
254 *
255 * Case 9:
256 * bbno bend
257 * +BBBBBBBBBBBBBBBBB+
258 * +----------------------+
259 * fbno fend
260 */
261 busyp->length = fbno - busyp->bno;
262 } else {
263 ASSERT(0);
264 }
265
266 trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen);
267 return true;
268
269out_force_log:
270 spin_unlock(&pag->pagb_lock);
271 xfs_log_force(mp, XFS_LOG_SYNC);
272 trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen);
273 spin_lock(&pag->pagb_lock);
274 return false;
275}
276
277
278/*
279 * For a given extent [fbno, flen], make sure we can reuse it safely.
280 */
281void
282xfs_extent_busy_reuse(
283 struct xfs_mount *mp,
284 xfs_agnumber_t agno,
285 xfs_agblock_t fbno,
286 xfs_extlen_t flen,
287 bool userdata)
288{
289 struct xfs_perag *pag;
290 struct rb_node *rbp;
291
292 ASSERT(flen > 0);
293
294 pag = xfs_perag_get(mp, agno);
295 spin_lock(&pag->pagb_lock);
296restart:
297 rbp = pag->pagb_tree.rb_node;
298 while (rbp) {
299 struct xfs_extent_busy *busyp =
300 rb_entry(rbp, struct xfs_extent_busy, rb_node);
301 xfs_agblock_t bbno = busyp->bno;
302 xfs_agblock_t bend = bbno + busyp->length;
303
304 if (fbno + flen <= bbno) {
305 rbp = rbp->rb_left;
306 continue;
307 } else if (fbno >= bend) {
308 rbp = rbp->rb_right;
309 continue;
310 }
311
312 if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen,
313 userdata))
314 goto restart;
315 }
316 spin_unlock(&pag->pagb_lock);
317 xfs_perag_put(pag);
318}
319
320/*
321 * For a given extent [fbno, flen], search the busy extent list to find a
322 * subset of the extent that is not busy. If *rlen is smaller than
323 * args->minlen no suitable extent could be found, and the higher level
324 * code needs to force out the log and retry the allocation.
325 *
326 * Return the current busy generation for the AG if the extent is busy. This
327 * value can be used to wait for at least one of the currently busy extents
328 * to be cleared. Note that the busy list is not guaranteed to be empty after
329 * the gen is woken. The state of a specific extent must always be confirmed
330 * with another call to xfs_extent_busy_trim() before it can be used.
331 */
332bool
333xfs_extent_busy_trim(
334 struct xfs_alloc_arg *args,
335 xfs_agblock_t *bno,
336 xfs_extlen_t *len,
337 unsigned *busy_gen)
338{
339 xfs_agblock_t fbno;
340 xfs_extlen_t flen;
341 struct rb_node *rbp;
342 bool ret = false;
343
344 ASSERT(*len > 0);
345
346 spin_lock(&args->pag->pagb_lock);
347restart:
348 fbno = *bno;
349 flen = *len;
350 rbp = args->pag->pagb_tree.rb_node;
351 while (rbp && flen >= args->minlen) {
352 struct xfs_extent_busy *busyp =
353 rb_entry(rbp, struct xfs_extent_busy, rb_node);
354 xfs_agblock_t fend = fbno + flen;
355 xfs_agblock_t bbno = busyp->bno;
356 xfs_agblock_t bend = bbno + busyp->length;
357
358 if (fend <= bbno) {
359 rbp = rbp->rb_left;
360 continue;
361 } else if (fbno >= bend) {
362 rbp = rbp->rb_right;
363 continue;
364 }
365
366 /*
367 * If this is a metadata allocation, try to reuse the busy
368 * extent instead of trimming the allocation.
369 */
370 if (!xfs_alloc_is_userdata(args->datatype) &&
371 !(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) {
372 if (!xfs_extent_busy_update_extent(args->mp, args->pag,
373 busyp, fbno, flen,
374 false))
375 goto restart;
376 continue;
377 }
378
379 if (bbno <= fbno) {
380 /* start overlap */
381
382 /*
383 * Case 1:
384 * bbno bend
385 * +BBBBBBBBBBBBBBBBB+
386 * +---------+
387 * fbno fend
388 *
389 * Case 2:
390 * bbno bend
391 * +BBBBBBBBBBBBBBBBB+
392 * +-------------+
393 * fbno fend
394 *
395 * Case 3:
396 * bbno bend
397 * +BBBBBBBBBBBBBBBBB+
398 * +-------------+
399 * fbno fend
400 *
401 * Case 4:
402 * bbno bend
403 * +BBBBBBBBBBBBBBBBB+
404 * +-----------------+
405 * fbno fend
406 *
407 * No unbusy region in extent, return failure.
408 */
409 if (fend <= bend)
410 goto fail;
411
412 /*
413 * Case 5:
414 * bbno bend
415 * +BBBBBBBBBBBBBBBBB+
416 * +----------------------+
417 * fbno fend
418 *
419 * Case 6:
420 * bbno bend
421 * +BBBBBBBBBBBBBBBBB+
422 * +--------------------------+
423 * fbno fend
424 *
425 * Needs to be trimmed to:
426 * +-------+
427 * fbno fend
428 */
429 fbno = bend;
430 } else if (bend >= fend) {
431 /* end overlap */
432
433 /*
434 * Case 7:
435 * bbno bend
436 * +BBBBBBBBBBBBBBBBB+
437 * +------------------+
438 * fbno fend
439 *
440 * Case 8:
441 * bbno bend
442 * +BBBBBBBBBBBBBBBBB+
443 * +--------------------------+
444 * fbno fend
445 *
446 * Needs to be trimmed to:
447 * +-------+
448 * fbno fend
449 */
450 fend = bbno;
451 } else {
452 /* middle overlap */
453
454 /*
455 * Case 9:
456 * bbno bend
457 * +BBBBBBBBBBBBBBBBB+
458 * +-----------------------------------+
459 * fbno fend
460 *
461 * Can be trimmed to:
462 * +-------+ OR +-------+
463 * fbno fend fbno fend
464 *
465 * Backward allocation leads to significant
466 * fragmentation of directories, which degrades
467 * directory performance, therefore we always want to
468 * choose the option that produces forward allocation
469 * patterns.
470 * Preferring the lower bno extent will make the next
471 * request use "fend" as the start of the next
472 * allocation; if the segment is no longer busy at
473 * that point, we'll get a contiguous allocation, but
474 * even if it is still busy, we will get a forward
475 * allocation.
476 * We try to avoid choosing the segment at "bend",
477 * because that can lead to the next allocation
478 * taking the segment at "fbno", which would be a
479 * backward allocation. We only use the segment at
480 * "fbno" if it is much larger than the current
481 * requested size, because in that case there's a
482 * good chance subsequent allocations will be
483 * contiguous.
484 */
485 if (bbno - fbno >= args->maxlen) {
486 /* left candidate fits perfect */
487 fend = bbno;
488 } else if (fend - bend >= args->maxlen * 4) {
489 /* right candidate has enough free space */
490 fbno = bend;
491 } else if (bbno - fbno >= args->minlen) {
492 /* left candidate fits minimum requirement */
493 fend = bbno;
494 } else {
495 goto fail;
496 }
497 }
498
499 flen = fend - fbno;
500 }
501out:
502
503 if (fbno != *bno || flen != *len) {
504 trace_xfs_extent_busy_trim(args->mp, args->agno, *bno, *len,
505 fbno, flen);
506 *bno = fbno;
507 *len = flen;
508 *busy_gen = args->pag->pagb_gen;
509 ret = true;
510 }
511 spin_unlock(&args->pag->pagb_lock);
512 return ret;
513fail:
514 /*
515 * Return a zero extent length as failure indications. All callers
516 * re-check if the trimmed extent satisfies the minlen requirement.
517 */
518 flen = 0;
519 goto out;
520}
521
522STATIC void
523xfs_extent_busy_clear_one(
524 struct xfs_mount *mp,
525 struct xfs_perag *pag,
526 struct xfs_extent_busy *busyp)
527{
528 if (busyp->length) {
529 trace_xfs_extent_busy_clear(mp, busyp->agno, busyp->bno,
530 busyp->length);
531 rb_erase(&busyp->rb_node, &pag->pagb_tree);
532 }
533
534 list_del_init(&busyp->list);
535 kmem_free(busyp);
536}
537
538static void
539xfs_extent_busy_put_pag(
540 struct xfs_perag *pag,
541 bool wakeup)
542 __releases(pag->pagb_lock)
543{
544 if (wakeup) {
545 pag->pagb_gen++;
546 wake_up_all(&pag->pagb_wait);
547 }
548
549 spin_unlock(&pag->pagb_lock);
550 xfs_perag_put(pag);
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 */
558void
559xfs_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 bool wakeup = false;
568
569 list_for_each_entry_safe(busyp, n, list, list) {
570 if (busyp->agno != agno) {
571 if (pag)
572 xfs_extent_busy_put_pag(pag, wakeup);
573 agno = busyp->agno;
574 pag = xfs_perag_get(mp, agno);
575 spin_lock(&pag->pagb_lock);
576 wakeup = false;
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 wakeup = true;
585 }
586 }
587
588 if (pag)
589 xfs_extent_busy_put_pag(pag, wakeup);
590}
591
592/*
593 * Flush out all busy extents for this AG.
594 */
595void
596xfs_extent_busy_flush(
597 struct xfs_mount *mp,
598 struct xfs_perag *pag,
599 unsigned busy_gen)
600{
601 DEFINE_WAIT (wait);
602 int error;
603
604 error = xfs_log_force(mp, XFS_LOG_SYNC);
605 if (error)
606 return;
607
608 do {
609 prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE);
610 if (busy_gen != READ_ONCE(pag->pagb_gen))
611 break;
612 schedule();
613 } while (1);
614
615 finish_wait(&pag->pagb_wait, &wait);
616}
617
618void
619xfs_extent_busy_wait_all(
620 struct xfs_mount *mp)
621{
622 DEFINE_WAIT (wait);
623 xfs_agnumber_t agno;
624
625 for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
626 struct xfs_perag *pag = xfs_perag_get(mp, agno);
627
628 do {
629 prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE);
630 if (RB_EMPTY_ROOT(&pag->pagb_tree))
631 break;
632 schedule();
633 } while (1);
634 finish_wait(&pag->pagb_wait, &wait);
635
636 xfs_perag_put(pag);
637 }
638}
639
640/*
641 * Callback for list_sort to sort busy extents by the AG they reside in.
642 */
643int
644xfs_extent_busy_ag_cmp(
645 void *priv,
646 struct list_head *l1,
647 struct list_head *l2)
648{
649 struct xfs_extent_busy *b1 =
650 container_of(l1, struct xfs_extent_busy, list);
651 struct xfs_extent_busy *b2 =
652 container_of(l2, struct xfs_extent_busy, list);
653 s32 diff;
654
655 diff = b1->agno - b2->agno;
656 if (!diff)
657 diff = b1->bno - b2->bno;
658 return diff;
659}
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_format.h"
23#include "xfs_log_format.h"
24#include "xfs_shared.h"
25#include "xfs_trans_resv.h"
26#include "xfs_sb.h"
27#include "xfs_mount.h"
28#include "xfs_alloc.h"
29#include "xfs_extent_busy.h"
30#include "xfs_trace.h"
31#include "xfs_trans.h"
32#include "xfs_log.h"
33
34void
35xfs_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_SLEEP);
49 new->agno = agno;
50 new->bno = bno;
51 new->length = len;
52 INIT_LIST_HEAD(&new->list);
53 new->flags = flags;
54
55 /* trace before insert to be able to see failed inserts */
56 trace_xfs_extent_busy(tp->t_mountp, agno, bno, len);
57
58 pag = xfs_perag_get(tp->t_mountp, new->agno);
59 spin_lock(&pag->pagb_lock);
60 rbp = &pag->pagb_tree.rb_node;
61 while (*rbp) {
62 parent = *rbp;
63 busyp = rb_entry(parent, struct xfs_extent_busy, rb_node);
64
65 if (new->bno < busyp->bno) {
66 rbp = &(*rbp)->rb_left;
67 ASSERT(new->bno + new->length <= busyp->bno);
68 } else if (new->bno > busyp->bno) {
69 rbp = &(*rbp)->rb_right;
70 ASSERT(bno >= busyp->bno + busyp->length);
71 } else {
72 ASSERT(0);
73 }
74 }
75
76 rb_link_node(&new->rb_node, parent, rbp);
77 rb_insert_color(&new->rb_node, &pag->pagb_tree);
78
79 list_add(&new->list, &tp->t_busy);
80 spin_unlock(&pag->pagb_lock);
81 xfs_perag_put(pag);
82}
83
84/*
85 * Search for a busy extent within the range of the extent we are about to
86 * allocate. You need to be holding the busy extent tree lock when calling
87 * xfs_extent_busy_search(). This function returns 0 for no overlapping busy
88 * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact
89 * match. This is done so that a non-zero return indicates an overlap that
90 * will require a synchronous transaction, but it can still be
91 * used to distinguish between a partial or exact match.
92 */
93int
94xfs_extent_busy_search(
95 struct xfs_mount *mp,
96 xfs_agnumber_t agno,
97 xfs_agblock_t bno,
98 xfs_extlen_t len)
99{
100 struct xfs_perag *pag;
101 struct rb_node *rbp;
102 struct xfs_extent_busy *busyp;
103 int match = 0;
104
105 pag = xfs_perag_get(mp, agno);
106 spin_lock(&pag->pagb_lock);
107
108 rbp = pag->pagb_tree.rb_node;
109
110 /* find closest start bno overlap */
111 while (rbp) {
112 busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node);
113 if (bno < busyp->bno) {
114 /* may overlap, but exact start block is lower */
115 if (bno + len > busyp->bno)
116 match = -1;
117 rbp = rbp->rb_left;
118 } else if (bno > busyp->bno) {
119 /* may overlap, but exact start block is higher */
120 if (bno < busyp->bno + busyp->length)
121 match = -1;
122 rbp = rbp->rb_right;
123 } else {
124 /* bno matches busyp, length determines exact match */
125 match = (busyp->length == len) ? 1 : -1;
126 break;
127 }
128 }
129 spin_unlock(&pag->pagb_lock);
130 xfs_perag_put(pag);
131 return match;
132}
133
134/*
135 * The found free extent [fbno, fend] overlaps part or all of the given busy
136 * extent. If the overlap covers the beginning, the end, or all of the busy
137 * extent, the overlapping portion can be made unbusy and used for the
138 * allocation. We can't split a busy extent because we can't modify a
139 * transaction/CIL context busy list, but we can update an entry's block
140 * number or length.
141 *
142 * Returns true if the extent can safely be reused, or false if the search
143 * needs to be restarted.
144 */
145STATIC bool
146xfs_extent_busy_update_extent(
147 struct xfs_mount *mp,
148 struct xfs_perag *pag,
149 struct xfs_extent_busy *busyp,
150 xfs_agblock_t fbno,
151 xfs_extlen_t flen,
152 bool userdata) __releases(&pag->pagb_lock)
153 __acquires(&pag->pagb_lock)
154{
155 xfs_agblock_t fend = fbno + flen;
156 xfs_agblock_t bbno = busyp->bno;
157 xfs_agblock_t bend = bbno + busyp->length;
158
159 /*
160 * This extent is currently being discarded. Give the thread
161 * performing the discard a chance to mark the extent unbusy
162 * and retry.
163 */
164 if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) {
165 spin_unlock(&pag->pagb_lock);
166 delay(1);
167 spin_lock(&pag->pagb_lock);
168 return false;
169 }
170
171 /*
172 * If there is a busy extent overlapping a user allocation, we have
173 * no choice but to force the log and retry the search.
174 *
175 * Fortunately this does not happen during normal operation, but
176 * only if the filesystem is very low on space and has to dip into
177 * the AGFL for normal allocations.
178 */
179 if (userdata)
180 goto out_force_log;
181
182 if (bbno < fbno && bend > fend) {
183 /*
184 * Case 1:
185 * bbno bend
186 * +BBBBBBBBBBBBBBBBB+
187 * +---------+
188 * fbno fend
189 */
190
191 /*
192 * We would have to split the busy extent to be able to track
193 * it correct, which we cannot do because we would have to
194 * modify the list of busy extents attached to the transaction
195 * or CIL context, which is immutable.
196 *
197 * Force out the log to clear the busy extent and retry the
198 * search.
199 */
200 goto out_force_log;
201 } else if (bbno >= fbno && bend <= fend) {
202 /*
203 * Case 2:
204 * bbno bend
205 * +BBBBBBBBBBBBBBBBB+
206 * +-----------------+
207 * fbno fend
208 *
209 * Case 3:
210 * bbno bend
211 * +BBBBBBBBBBBBBBBBB+
212 * +--------------------------+
213 * fbno fend
214 *
215 * Case 4:
216 * bbno bend
217 * +BBBBBBBBBBBBBBBBB+
218 * +--------------------------+
219 * fbno fend
220 *
221 * Case 5:
222 * bbno bend
223 * +BBBBBBBBBBBBBBBBB+
224 * +-----------------------------------+
225 * fbno fend
226 *
227 */
228
229 /*
230 * The busy extent is fully covered by the extent we are
231 * allocating, and can simply be removed from the rbtree.
232 * However we cannot remove it from the immutable list
233 * tracking busy extents in the transaction or CIL context,
234 * so set the length to zero to mark it invalid.
235 *
236 * We also need to restart the busy extent search from the
237 * tree root, because erasing the node can rearrange the
238 * tree topology.
239 */
240 rb_erase(&busyp->rb_node, &pag->pagb_tree);
241 busyp->length = 0;
242 return false;
243 } else if (fend < bend) {
244 /*
245 * Case 6:
246 * bbno bend
247 * +BBBBBBBBBBBBBBBBB+
248 * +---------+
249 * fbno fend
250 *
251 * Case 7:
252 * bbno bend
253 * +BBBBBBBBBBBBBBBBB+
254 * +------------------+
255 * fbno fend
256 *
257 */
258 busyp->bno = fend;
259 } else if (bbno < fbno) {
260 /*
261 * Case 8:
262 * bbno bend
263 * +BBBBBBBBBBBBBBBBB+
264 * +-------------+
265 * fbno fend
266 *
267 * Case 9:
268 * bbno bend
269 * +BBBBBBBBBBBBBBBBB+
270 * +----------------------+
271 * fbno fend
272 */
273 busyp->length = fbno - busyp->bno;
274 } else {
275 ASSERT(0);
276 }
277
278 trace_xfs_extent_busy_reuse(mp, pag->pag_agno, fbno, flen);
279 return true;
280
281out_force_log:
282 spin_unlock(&pag->pagb_lock);
283 xfs_log_force(mp, XFS_LOG_SYNC);
284 trace_xfs_extent_busy_force(mp, pag->pag_agno, fbno, flen);
285 spin_lock(&pag->pagb_lock);
286 return false;
287}
288
289
290/*
291 * For a given extent [fbno, flen], make sure we can reuse it safely.
292 */
293void
294xfs_extent_busy_reuse(
295 struct xfs_mount *mp,
296 xfs_agnumber_t agno,
297 xfs_agblock_t fbno,
298 xfs_extlen_t flen,
299 bool userdata)
300{
301 struct xfs_perag *pag;
302 struct rb_node *rbp;
303
304 ASSERT(flen > 0);
305
306 pag = xfs_perag_get(mp, agno);
307 spin_lock(&pag->pagb_lock);
308restart:
309 rbp = pag->pagb_tree.rb_node;
310 while (rbp) {
311 struct xfs_extent_busy *busyp =
312 rb_entry(rbp, struct xfs_extent_busy, rb_node);
313 xfs_agblock_t bbno = busyp->bno;
314 xfs_agblock_t bend = bbno + busyp->length;
315
316 if (fbno + flen <= bbno) {
317 rbp = rbp->rb_left;
318 continue;
319 } else if (fbno >= bend) {
320 rbp = rbp->rb_right;
321 continue;
322 }
323
324 if (!xfs_extent_busy_update_extent(mp, pag, busyp, fbno, flen,
325 userdata))
326 goto restart;
327 }
328 spin_unlock(&pag->pagb_lock);
329 xfs_perag_put(pag);
330}
331
332/*
333 * For a given extent [fbno, flen], search the busy extent list to find a
334 * subset of the extent that is not busy. If *rlen is smaller than
335 * args->minlen no suitable extent could be found, and the higher level
336 * code needs to force out the log and retry the allocation.
337 *
338 * Return the current busy generation for the AG if the extent is busy. This
339 * value can be used to wait for at least one of the currently busy extents
340 * to be cleared. Note that the busy list is not guaranteed to be empty after
341 * the gen is woken. The state of a specific extent must always be confirmed
342 * with another call to xfs_extent_busy_trim() before it can be used.
343 */
344bool
345xfs_extent_busy_trim(
346 struct xfs_alloc_arg *args,
347 xfs_agblock_t *bno,
348 xfs_extlen_t *len,
349 unsigned *busy_gen)
350{
351 xfs_agblock_t fbno;
352 xfs_extlen_t flen;
353 struct rb_node *rbp;
354 bool ret = false;
355
356 ASSERT(*len > 0);
357
358 spin_lock(&args->pag->pagb_lock);
359restart:
360 fbno = *bno;
361 flen = *len;
362 rbp = args->pag->pagb_tree.rb_node;
363 while (rbp && flen >= args->minlen) {
364 struct xfs_extent_busy *busyp =
365 rb_entry(rbp, struct xfs_extent_busy, rb_node);
366 xfs_agblock_t fend = fbno + flen;
367 xfs_agblock_t bbno = busyp->bno;
368 xfs_agblock_t bend = bbno + busyp->length;
369
370 if (fend <= bbno) {
371 rbp = rbp->rb_left;
372 continue;
373 } else if (fbno >= bend) {
374 rbp = rbp->rb_right;
375 continue;
376 }
377
378 /*
379 * If this is a metadata allocation, try to reuse the busy
380 * extent instead of trimming the allocation.
381 */
382 if (!xfs_alloc_is_userdata(args->datatype) &&
383 !(busyp->flags & XFS_EXTENT_BUSY_DISCARDED)) {
384 if (!xfs_extent_busy_update_extent(args->mp, args->pag,
385 busyp, fbno, flen,
386 false))
387 goto restart;
388 continue;
389 }
390
391 if (bbno <= fbno) {
392 /* start overlap */
393
394 /*
395 * Case 1:
396 * bbno bend
397 * +BBBBBBBBBBBBBBBBB+
398 * +---------+
399 * fbno fend
400 *
401 * Case 2:
402 * bbno bend
403 * +BBBBBBBBBBBBBBBBB+
404 * +-------------+
405 * fbno fend
406 *
407 * Case 3:
408 * bbno bend
409 * +BBBBBBBBBBBBBBBBB+
410 * +-------------+
411 * fbno fend
412 *
413 * Case 4:
414 * bbno bend
415 * +BBBBBBBBBBBBBBBBB+
416 * +-----------------+
417 * fbno fend
418 *
419 * No unbusy region in extent, return failure.
420 */
421 if (fend <= bend)
422 goto fail;
423
424 /*
425 * Case 5:
426 * bbno bend
427 * +BBBBBBBBBBBBBBBBB+
428 * +----------------------+
429 * fbno fend
430 *
431 * Case 6:
432 * bbno bend
433 * +BBBBBBBBBBBBBBBBB+
434 * +--------------------------+
435 * fbno fend
436 *
437 * Needs to be trimmed to:
438 * +-------+
439 * fbno fend
440 */
441 fbno = bend;
442 } else if (bend >= fend) {
443 /* end overlap */
444
445 /*
446 * Case 7:
447 * bbno bend
448 * +BBBBBBBBBBBBBBBBB+
449 * +------------------+
450 * fbno fend
451 *
452 * Case 8:
453 * bbno bend
454 * +BBBBBBBBBBBBBBBBB+
455 * +--------------------------+
456 * fbno fend
457 *
458 * Needs to be trimmed to:
459 * +-------+
460 * fbno fend
461 */
462 fend = bbno;
463 } else {
464 /* middle overlap */
465
466 /*
467 * Case 9:
468 * bbno bend
469 * +BBBBBBBBBBBBBBBBB+
470 * +-----------------------------------+
471 * fbno fend
472 *
473 * Can be trimmed to:
474 * +-------+ OR +-------+
475 * fbno fend fbno fend
476 *
477 * Backward allocation leads to significant
478 * fragmentation of directories, which degrades
479 * directory performance, therefore we always want to
480 * choose the option that produces forward allocation
481 * patterns.
482 * Preferring the lower bno extent will make the next
483 * request use "fend" as the start of the next
484 * allocation; if the segment is no longer busy at
485 * that point, we'll get a contiguous allocation, but
486 * even if it is still busy, we will get a forward
487 * allocation.
488 * We try to avoid choosing the segment at "bend",
489 * because that can lead to the next allocation
490 * taking the segment at "fbno", which would be a
491 * backward allocation. We only use the segment at
492 * "fbno" if it is much larger than the current
493 * requested size, because in that case there's a
494 * good chance subsequent allocations will be
495 * contiguous.
496 */
497 if (bbno - fbno >= args->maxlen) {
498 /* left candidate fits perfect */
499 fend = bbno;
500 } else if (fend - bend >= args->maxlen * 4) {
501 /* right candidate has enough free space */
502 fbno = bend;
503 } else if (bbno - fbno >= args->minlen) {
504 /* left candidate fits minimum requirement */
505 fend = bbno;
506 } else {
507 goto fail;
508 }
509 }
510
511 flen = fend - fbno;
512 }
513out:
514
515 if (fbno != *bno || flen != *len) {
516 trace_xfs_extent_busy_trim(args->mp, args->agno, *bno, *len,
517 fbno, flen);
518 *bno = fbno;
519 *len = flen;
520 *busy_gen = args->pag->pagb_gen;
521 ret = true;
522 }
523 spin_unlock(&args->pag->pagb_lock);
524 return ret;
525fail:
526 /*
527 * Return a zero extent length as failure indications. All callers
528 * re-check if the trimmed extent satisfies the minlen requirement.
529 */
530 flen = 0;
531 goto out;
532}
533
534STATIC void
535xfs_extent_busy_clear_one(
536 struct xfs_mount *mp,
537 struct xfs_perag *pag,
538 struct xfs_extent_busy *busyp)
539{
540 if (busyp->length) {
541 trace_xfs_extent_busy_clear(mp, busyp->agno, busyp->bno,
542 busyp->length);
543 rb_erase(&busyp->rb_node, &pag->pagb_tree);
544 }
545
546 list_del_init(&busyp->list);
547 kmem_free(busyp);
548}
549
550static void
551xfs_extent_busy_put_pag(
552 struct xfs_perag *pag,
553 bool wakeup)
554 __releases(pag->pagb_lock)
555{
556 if (wakeup) {
557 pag->pagb_gen++;
558 wake_up_all(&pag->pagb_wait);
559 }
560
561 spin_unlock(&pag->pagb_lock);
562 xfs_perag_put(pag);
563}
564
565/*
566 * Remove all extents on the passed in list from the busy extents tree.
567 * If do_discard is set skip extents that need to be discarded, and mark
568 * these as undergoing a discard operation instead.
569 */
570void
571xfs_extent_busy_clear(
572 struct xfs_mount *mp,
573 struct list_head *list,
574 bool do_discard)
575{
576 struct xfs_extent_busy *busyp, *n;
577 struct xfs_perag *pag = NULL;
578 xfs_agnumber_t agno = NULLAGNUMBER;
579 bool wakeup = false;
580
581 list_for_each_entry_safe(busyp, n, list, list) {
582 if (busyp->agno != agno) {
583 if (pag)
584 xfs_extent_busy_put_pag(pag, wakeup);
585 agno = busyp->agno;
586 pag = xfs_perag_get(mp, agno);
587 spin_lock(&pag->pagb_lock);
588 wakeup = false;
589 }
590
591 if (do_discard && busyp->length &&
592 !(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD)) {
593 busyp->flags = XFS_EXTENT_BUSY_DISCARDED;
594 } else {
595 xfs_extent_busy_clear_one(mp, pag, busyp);
596 wakeup = true;
597 }
598 }
599
600 if (pag)
601 xfs_extent_busy_put_pag(pag, wakeup);
602}
603
604/*
605 * Flush out all busy extents for this AG.
606 */
607void
608xfs_extent_busy_flush(
609 struct xfs_mount *mp,
610 struct xfs_perag *pag,
611 unsigned busy_gen)
612{
613 DEFINE_WAIT (wait);
614 int error;
615
616 error = xfs_log_force(mp, XFS_LOG_SYNC);
617 if (error)
618 return;
619
620 do {
621 prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE);
622 if (busy_gen != READ_ONCE(pag->pagb_gen))
623 break;
624 schedule();
625 } while (1);
626
627 finish_wait(&pag->pagb_wait, &wait);
628}
629
630void
631xfs_extent_busy_wait_all(
632 struct xfs_mount *mp)
633{
634 DEFINE_WAIT (wait);
635 xfs_agnumber_t agno;
636
637 for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
638 struct xfs_perag *pag = xfs_perag_get(mp, agno);
639
640 do {
641 prepare_to_wait(&pag->pagb_wait, &wait, TASK_KILLABLE);
642 if (RB_EMPTY_ROOT(&pag->pagb_tree))
643 break;
644 schedule();
645 } while (1);
646 finish_wait(&pag->pagb_wait, &wait);
647
648 xfs_perag_put(pag);
649 }
650}
651
652/*
653 * Callback for list_sort to sort busy extents by the AG they reside in.
654 */
655int
656xfs_extent_busy_ag_cmp(
657 void *priv,
658 struct list_head *l1,
659 struct list_head *l2)
660{
661 struct xfs_extent_busy *b1 =
662 container_of(l1, struct xfs_extent_busy, list);
663 struct xfs_extent_busy *b2 =
664 container_of(l2, struct xfs_extent_busy, list);
665 s32 diff;
666
667 diff = b1->agno - b2->agno;
668 if (!diff)
669 diff = b1->bno - b2->bno;
670 return diff;
671}