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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
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_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 */
104int
105xfs_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 */
156STATIC bool
157xfs_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
291out_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 */
303void
304xfs_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);
318restart:
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 */
348void
349xfs_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);
363restart:
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;
526fail:
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
537STATIC void
538xfs_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 */
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
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 */
595int
596xfs_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}
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_mount.h"
15#include "xfs_alloc.h"
16#include "xfs_extent_busy.h"
17#include "xfs_trace.h"
18#include "xfs_trans.h"
19#include "xfs_log.h"
20#include "xfs_ag.h"
21#include "xfs_rtgroup.h"
22
23struct xfs_extent_busy_tree {
24 spinlock_t eb_lock;
25 struct rb_root eb_tree;
26 unsigned int eb_gen;
27 wait_queue_head_t eb_wait;
28};
29
30static void
31xfs_extent_busy_insert_list(
32 struct xfs_group *xg,
33 xfs_agblock_t bno,
34 xfs_extlen_t len,
35 unsigned int flags,
36 struct list_head *busy_list)
37{
38 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
39 struct xfs_extent_busy *new;
40 struct xfs_extent_busy *busyp;
41 struct rb_node **rbp;
42 struct rb_node *parent = NULL;
43
44 new = kzalloc(sizeof(struct xfs_extent_busy),
45 GFP_KERNEL | __GFP_NOFAIL);
46 new->group = xfs_group_hold(xg);
47 new->bno = bno;
48 new->length = len;
49 INIT_LIST_HEAD(&new->list);
50 new->flags = flags;
51
52 /* trace before insert to be able to see failed inserts */
53 trace_xfs_extent_busy(xg, bno, len);
54
55 spin_lock(&eb->eb_lock);
56 rbp = &eb->eb_tree.rb_node;
57 while (*rbp) {
58 parent = *rbp;
59 busyp = rb_entry(parent, struct xfs_extent_busy, rb_node);
60
61 if (new->bno < busyp->bno) {
62 rbp = &(*rbp)->rb_left;
63 ASSERT(new->bno + new->length <= busyp->bno);
64 } else if (new->bno > busyp->bno) {
65 rbp = &(*rbp)->rb_right;
66 ASSERT(bno >= busyp->bno + busyp->length);
67 } else {
68 ASSERT(0);
69 }
70 }
71
72 rb_link_node(&new->rb_node, parent, rbp);
73 rb_insert_color(&new->rb_node, &eb->eb_tree);
74
75 /* always process discard lists in fifo order */
76 list_add_tail(&new->list, busy_list);
77 spin_unlock(&eb->eb_lock);
78}
79
80void
81xfs_extent_busy_insert(
82 struct xfs_trans *tp,
83 struct xfs_group *xg,
84 xfs_agblock_t bno,
85 xfs_extlen_t len,
86 unsigned int flags)
87{
88 xfs_extent_busy_insert_list(xg, bno, len, flags, &tp->t_busy);
89}
90
91void
92xfs_extent_busy_insert_discard(
93 struct xfs_group *xg,
94 xfs_agblock_t bno,
95 xfs_extlen_t len,
96 struct list_head *busy_list)
97{
98 xfs_extent_busy_insert_list(xg, bno, len, XFS_EXTENT_BUSY_DISCARDED,
99 busy_list);
100}
101
102/*
103 * Search for a busy extent within the range of the extent we are about to
104 * allocate. You need to be holding the busy extent tree lock when calling
105 * xfs_extent_busy_search(). This function returns 0 for no overlapping busy
106 * extent, -1 for an overlapping but not exact busy extent, and 1 for an exact
107 * match. This is done so that a non-zero return indicates an overlap that
108 * will require a synchronous transaction, but it can still be
109 * used to distinguish between a partial or exact match.
110 */
111int
112xfs_extent_busy_search(
113 struct xfs_group *xg,
114 xfs_agblock_t bno,
115 xfs_extlen_t len)
116{
117 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
118 struct rb_node *rbp;
119 struct xfs_extent_busy *busyp;
120 int match = 0;
121
122 /* find closest start bno overlap */
123 spin_lock(&eb->eb_lock);
124 rbp = eb->eb_tree.rb_node;
125 while (rbp) {
126 busyp = rb_entry(rbp, struct xfs_extent_busy, rb_node);
127 if (bno < busyp->bno) {
128 /* may overlap, but exact start block is lower */
129 if (bno + len > busyp->bno)
130 match = -1;
131 rbp = rbp->rb_left;
132 } else if (bno > busyp->bno) {
133 /* may overlap, but exact start block is higher */
134 if (bno < busyp->bno + busyp->length)
135 match = -1;
136 rbp = rbp->rb_right;
137 } else {
138 /* bno matches busyp, length determines exact match */
139 match = (busyp->length == len) ? 1 : -1;
140 break;
141 }
142 }
143 spin_unlock(&eb->eb_lock);
144 return match;
145}
146
147/*
148 * The found free extent [fbno, fend] overlaps part or all of the given busy
149 * extent. If the overlap covers the beginning, the end, or all of the busy
150 * extent, the overlapping portion can be made unbusy and used for the
151 * allocation. We can't split a busy extent because we can't modify a
152 * transaction/CIL context busy list, but we can update an entry's block
153 * number or length.
154 *
155 * Returns true if the extent can safely be reused, or false if the search
156 * needs to be restarted.
157 */
158STATIC bool
159xfs_extent_busy_update_extent(
160 struct xfs_group *xg,
161 struct xfs_extent_busy *busyp,
162 xfs_agblock_t fbno,
163 xfs_extlen_t flen,
164 bool userdata)
165 __releases(&eb->eb_lock)
166 __acquires(&eb->eb_lock)
167{
168 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
169 xfs_agblock_t fend = fbno + flen;
170 xfs_agblock_t bbno = busyp->bno;
171 xfs_agblock_t bend = bbno + busyp->length;
172
173 /*
174 * This extent is currently being discarded. Give the thread
175 * performing the discard a chance to mark the extent unbusy
176 * and retry.
177 */
178 if (busyp->flags & XFS_EXTENT_BUSY_DISCARDED) {
179 spin_unlock(&eb->eb_lock);
180 delay(1);
181 spin_lock(&eb->eb_lock);
182 return false;
183 }
184
185 /*
186 * If there is a busy extent overlapping a user allocation, we have
187 * no choice but to force the log and retry the search.
188 *
189 * Fortunately this does not happen during normal operation, but
190 * only if the filesystem is very low on space and has to dip into
191 * the AGFL for normal allocations.
192 */
193 if (userdata)
194 goto out_force_log;
195
196 if (bbno < fbno && bend > fend) {
197 /*
198 * Case 1:
199 * bbno bend
200 * +BBBBBBBBBBBBBBBBB+
201 * +---------+
202 * fbno fend
203 */
204
205 /*
206 * We would have to split the busy extent to be able to track
207 * it correct, which we cannot do because we would have to
208 * modify the list of busy extents attached to the transaction
209 * or CIL context, which is immutable.
210 *
211 * Force out the log to clear the busy extent and retry the
212 * search.
213 */
214 goto out_force_log;
215 } else if (bbno >= fbno && bend <= fend) {
216 /*
217 * Case 2:
218 * bbno bend
219 * +BBBBBBBBBBBBBBBBB+
220 * +-----------------+
221 * fbno fend
222 *
223 * Case 3:
224 * bbno bend
225 * +BBBBBBBBBBBBBBBBB+
226 * +--------------------------+
227 * fbno fend
228 *
229 * Case 4:
230 * bbno bend
231 * +BBBBBBBBBBBBBBBBB+
232 * +--------------------------+
233 * fbno fend
234 *
235 * Case 5:
236 * bbno bend
237 * +BBBBBBBBBBBBBBBBB+
238 * +-----------------------------------+
239 * fbno fend
240 *
241 */
242
243 /*
244 * The busy extent is fully covered by the extent we are
245 * allocating, and can simply be removed from the rbtree.
246 * However we cannot remove it from the immutable list
247 * tracking busy extents in the transaction or CIL context,
248 * so set the length to zero to mark it invalid.
249 *
250 * We also need to restart the busy extent search from the
251 * tree root, because erasing the node can rearrange the
252 * tree topology.
253 */
254 rb_erase(&busyp->rb_node, &eb->eb_tree);
255 busyp->length = 0;
256 return false;
257 } else if (fend < bend) {
258 /*
259 * Case 6:
260 * bbno bend
261 * +BBBBBBBBBBBBBBBBB+
262 * +---------+
263 * fbno fend
264 *
265 * Case 7:
266 * bbno bend
267 * +BBBBBBBBBBBBBBBBB+
268 * +------------------+
269 * fbno fend
270 *
271 */
272 busyp->bno = fend;
273 busyp->length = bend - fend;
274 } else if (bbno < fbno) {
275 /*
276 * Case 8:
277 * bbno bend
278 * +BBBBBBBBBBBBBBBBB+
279 * +-------------+
280 * fbno fend
281 *
282 * Case 9:
283 * bbno bend
284 * +BBBBBBBBBBBBBBBBB+
285 * +----------------------+
286 * fbno fend
287 */
288 busyp->length = fbno - busyp->bno;
289 } else {
290 ASSERT(0);
291 }
292
293 trace_xfs_extent_busy_reuse(xg, fbno, flen);
294 return true;
295
296out_force_log:
297 spin_unlock(&eb->eb_lock);
298 xfs_log_force(xg->xg_mount, XFS_LOG_SYNC);
299 trace_xfs_extent_busy_force(xg, fbno, flen);
300 spin_lock(&eb->eb_lock);
301 return false;
302}
303
304/*
305 * For a given extent [fbno, flen], make sure we can reuse it safely.
306 */
307void
308xfs_extent_busy_reuse(
309 struct xfs_group *xg,
310 xfs_agblock_t fbno,
311 xfs_extlen_t flen,
312 bool userdata)
313{
314 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
315 struct rb_node *rbp;
316
317 ASSERT(flen > 0);
318 spin_lock(&eb->eb_lock);
319restart:
320 rbp = eb->eb_tree.rb_node;
321 while (rbp) {
322 struct xfs_extent_busy *busyp =
323 rb_entry(rbp, struct xfs_extent_busy, rb_node);
324 xfs_agblock_t bbno = busyp->bno;
325 xfs_agblock_t bend = bbno + busyp->length;
326
327 if (fbno + flen <= bbno) {
328 rbp = rbp->rb_left;
329 continue;
330 } else if (fbno >= bend) {
331 rbp = rbp->rb_right;
332 continue;
333 }
334
335 if (!xfs_extent_busy_update_extent(xg, busyp, fbno, flen,
336 userdata))
337 goto restart;
338 }
339 spin_unlock(&eb->eb_lock);
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 * Return the current busy generation for the group if the extent is busy. This
349 * value can be used to wait for at least one of the currently busy extents
350 * to be cleared. Note that the busy list is not guaranteed to be empty after
351 * the gen is woken. The state of a specific extent must always be confirmed
352 * with another call to xfs_extent_busy_trim() before it can be used.
353 */
354bool
355xfs_extent_busy_trim(
356 struct xfs_group *xg,
357 xfs_extlen_t minlen,
358 xfs_extlen_t maxlen,
359 xfs_agblock_t *bno,
360 xfs_extlen_t *len,
361 unsigned *busy_gen)
362{
363 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
364 xfs_agblock_t fbno;
365 xfs_extlen_t flen;
366 struct rb_node *rbp;
367 bool ret = false;
368
369 ASSERT(*len > 0);
370
371 spin_lock(&eb->eb_lock);
372 fbno = *bno;
373 flen = *len;
374 rbp = eb->eb_tree.rb_node;
375 while (rbp && flen >= minlen) {
376 struct xfs_extent_busy *busyp =
377 rb_entry(rbp, struct xfs_extent_busy, rb_node);
378 xfs_agblock_t fend = fbno + flen;
379 xfs_agblock_t bbno = busyp->bno;
380 xfs_agblock_t bend = bbno + busyp->length;
381
382 if (fend <= bbno) {
383 rbp = rbp->rb_left;
384 continue;
385 } else if (fbno >= bend) {
386 rbp = rbp->rb_right;
387 continue;
388 }
389
390 if (bbno <= fbno) {
391 /* start overlap */
392
393 /*
394 * Case 1:
395 * bbno bend
396 * +BBBBBBBBBBBBBBBBB+
397 * +---------+
398 * fbno fend
399 *
400 * Case 2:
401 * bbno bend
402 * +BBBBBBBBBBBBBBBBB+
403 * +-------------+
404 * fbno fend
405 *
406 * Case 3:
407 * bbno bend
408 * +BBBBBBBBBBBBBBBBB+
409 * +-------------+
410 * fbno fend
411 *
412 * Case 4:
413 * bbno bend
414 * +BBBBBBBBBBBBBBBBB+
415 * +-----------------+
416 * fbno fend
417 *
418 * No unbusy region in extent, return failure.
419 */
420 if (fend <= bend)
421 goto fail;
422
423 /*
424 * Case 5:
425 * bbno bend
426 * +BBBBBBBBBBBBBBBBB+
427 * +----------------------+
428 * fbno fend
429 *
430 * Case 6:
431 * bbno bend
432 * +BBBBBBBBBBBBBBBBB+
433 * +--------------------------+
434 * fbno fend
435 *
436 * Needs to be trimmed to:
437 * +-------+
438 * fbno fend
439 */
440 fbno = bend;
441 } else if (bend >= fend) {
442 /* end overlap */
443
444 /*
445 * Case 7:
446 * bbno bend
447 * +BBBBBBBBBBBBBBBBB+
448 * +------------------+
449 * fbno fend
450 *
451 * Case 8:
452 * bbno bend
453 * +BBBBBBBBBBBBBBBBB+
454 * +--------------------------+
455 * fbno fend
456 *
457 * Needs to be trimmed to:
458 * +-------+
459 * fbno fend
460 */
461 fend = bbno;
462 } else {
463 /* middle overlap */
464
465 /*
466 * Case 9:
467 * bbno bend
468 * +BBBBBBBBBBBBBBBBB+
469 * +-----------------------------------+
470 * fbno fend
471 *
472 * Can be trimmed to:
473 * +-------+ OR +-------+
474 * fbno fend fbno fend
475 *
476 * Backward allocation leads to significant
477 * fragmentation of directories, which degrades
478 * directory performance, therefore we always want to
479 * choose the option that produces forward allocation
480 * patterns.
481 * Preferring the lower bno extent will make the next
482 * request use "fend" as the start of the next
483 * allocation; if the segment is no longer busy at
484 * that point, we'll get a contiguous allocation, but
485 * even if it is still busy, we will get a forward
486 * allocation.
487 * We try to avoid choosing the segment at "bend",
488 * because that can lead to the next allocation
489 * taking the segment at "fbno", which would be a
490 * backward allocation. We only use the segment at
491 * "fbno" if it is much larger than the current
492 * requested size, because in that case there's a
493 * good chance subsequent allocations will be
494 * contiguous.
495 */
496 if (bbno - fbno >= maxlen) {
497 /* left candidate fits perfect */
498 fend = bbno;
499 } else if (fend - bend >= maxlen * 4) {
500 /* right candidate has enough free space */
501 fbno = bend;
502 } else if (bbno - fbno >= minlen) {
503 /* left candidate fits minimum requirement */
504 fend = bbno;
505 } else {
506 goto fail;
507 }
508 }
509
510 flen = fend - fbno;
511 }
512out:
513
514 if (fbno != *bno || flen != *len) {
515 trace_xfs_extent_busy_trim(xg, *bno, *len, fbno, flen);
516 *bno = fbno;
517 *len = flen;
518 *busy_gen = eb->eb_gen;
519 ret = true;
520 }
521 spin_unlock(&eb->eb_lock);
522 return ret;
523fail:
524 /*
525 * Return a zero extent length as failure indications. All callers
526 * re-check if the trimmed extent satisfies the minlen requirement.
527 */
528 flen = 0;
529 goto out;
530}
531
532static bool
533xfs_extent_busy_clear_one(
534 struct xfs_extent_busy *busyp,
535 bool do_discard)
536{
537 struct xfs_extent_busy_tree *eb = busyp->group->xg_busy_extents;
538
539 if (busyp->length) {
540 if (do_discard &&
541 !(busyp->flags & XFS_EXTENT_BUSY_SKIP_DISCARD)) {
542 busyp->flags = XFS_EXTENT_BUSY_DISCARDED;
543 return false;
544 }
545 trace_xfs_extent_busy_clear(busyp->group, busyp->bno,
546 busyp->length);
547 rb_erase(&busyp->rb_node, &eb->eb_tree);
548 }
549
550 list_del_init(&busyp->list);
551 xfs_group_put(busyp->group);
552 kfree(busyp);
553 return true;
554}
555
556/*
557 * Remove all extents on the passed in list from the busy extents tree.
558 * If do_discard is set skip extents that need to be discarded, and mark
559 * these as undergoing a discard operation instead.
560 */
561void
562xfs_extent_busy_clear(
563 struct list_head *list,
564 bool do_discard)
565{
566 struct xfs_extent_busy *busyp, *next;
567
568 busyp = list_first_entry_or_null(list, typeof(*busyp), list);
569 if (!busyp)
570 return;
571
572 do {
573 struct xfs_group *xg = xfs_group_hold(busyp->group);
574 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
575 bool wakeup = false;
576
577 spin_lock(&eb->eb_lock);
578 do {
579 next = list_next_entry(busyp, list);
580 if (xfs_extent_busy_clear_one(busyp, do_discard))
581 wakeup = true;
582 busyp = next;
583 } while (!list_entry_is_head(busyp, list, list) &&
584 busyp->group == xg);
585
586 if (wakeup) {
587 eb->eb_gen++;
588 wake_up_all(&eb->eb_wait);
589 }
590 spin_unlock(&eb->eb_lock);
591 xfs_group_put(xg);
592 } while (!list_entry_is_head(busyp, list, list));
593}
594
595/*
596 * Flush out all busy extents for this group.
597 *
598 * If the current transaction is holding busy extents, the caller may not want
599 * to wait for committed busy extents to resolve. If we are being told just to
600 * try a flush or progress has been made since we last skipped a busy extent,
601 * return immediately to allow the caller to try again.
602 *
603 * If we are freeing extents, we might actually be holding the only free extents
604 * in the transaction busy list and the log force won't resolve that situation.
605 * In this case, we must return -EAGAIN to avoid a deadlock by informing the
606 * caller it needs to commit the busy extents it holds before retrying the
607 * extent free operation.
608 */
609int
610xfs_extent_busy_flush(
611 struct xfs_trans *tp,
612 struct xfs_group *xg,
613 unsigned busy_gen,
614 uint32_t alloc_flags)
615{
616 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
617 DEFINE_WAIT (wait);
618 int error;
619
620 error = xfs_log_force(tp->t_mountp, XFS_LOG_SYNC);
621 if (error)
622 return error;
623
624 /* Avoid deadlocks on uncommitted busy extents. */
625 if (!list_empty(&tp->t_busy)) {
626 if (alloc_flags & XFS_ALLOC_FLAG_TRYFLUSH)
627 return 0;
628
629 if (busy_gen != READ_ONCE(eb->eb_gen))
630 return 0;
631
632 if (alloc_flags & XFS_ALLOC_FLAG_FREEING)
633 return -EAGAIN;
634 }
635
636 /* Wait for committed busy extents to resolve. */
637 do {
638 prepare_to_wait(&eb->eb_wait, &wait, TASK_KILLABLE);
639 if (busy_gen != READ_ONCE(eb->eb_gen))
640 break;
641 schedule();
642 } while (1);
643
644 finish_wait(&eb->eb_wait, &wait);
645 return 0;
646}
647
648static void
649xfs_extent_busy_wait_group(
650 struct xfs_group *xg)
651{
652 DEFINE_WAIT (wait);
653 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
654
655 do {
656 prepare_to_wait(&eb->eb_wait, &wait, TASK_KILLABLE);
657 if (RB_EMPTY_ROOT(&eb->eb_tree))
658 break;
659 schedule();
660 } while (1);
661 finish_wait(&eb->eb_wait, &wait);
662}
663
664void
665xfs_extent_busy_wait_all(
666 struct xfs_mount *mp)
667{
668 struct xfs_perag *pag = NULL;
669 struct xfs_rtgroup *rtg = NULL;
670
671 while ((pag = xfs_perag_next(mp, pag)))
672 xfs_extent_busy_wait_group(pag_group(pag));
673
674 if (xfs_has_rtgroups(mp))
675 while ((rtg = xfs_rtgroup_next(mp, rtg)))
676 xfs_extent_busy_wait_group(rtg_group(rtg));
677}
678
679/*
680 * Callback for list_sort to sort busy extents by the group they reside in.
681 */
682int
683xfs_extent_busy_ag_cmp(
684 void *priv,
685 const struct list_head *l1,
686 const struct list_head *l2)
687{
688 struct xfs_extent_busy *b1 =
689 container_of(l1, struct xfs_extent_busy, list);
690 struct xfs_extent_busy *b2 =
691 container_of(l2, struct xfs_extent_busy, list);
692 s32 diff;
693
694 diff = b1->group->xg_gno - b2->group->xg_gno;
695 if (!diff)
696 diff = b1->bno - b2->bno;
697 return diff;
698}
699
700/* Are there any busy extents in this group? */
701bool
702xfs_extent_busy_list_empty(
703 struct xfs_group *xg,
704 unsigned *busy_gen)
705{
706 struct xfs_extent_busy_tree *eb = xg->xg_busy_extents;
707 bool res;
708
709 spin_lock(&eb->eb_lock);
710 res = RB_EMPTY_ROOT(&eb->eb_tree);
711 *busy_gen = READ_ONCE(eb->eb_gen);
712 spin_unlock(&eb->eb_lock);
713 return res;
714}
715
716struct xfs_extent_busy_tree *
717xfs_extent_busy_alloc(void)
718{
719 struct xfs_extent_busy_tree *eb;
720
721 eb = kzalloc(sizeof(*eb), GFP_KERNEL);
722 if (!eb)
723 return NULL;
724 spin_lock_init(&eb->eb_lock);
725 init_waitqueue_head(&eb->eb_wait);
726 eb->eb_tree = RB_ROOT;
727 return eb;
728}