1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (c) 2017 Christoph Hellwig.
4 */
5
6 #include "xfs.h"
7 #include "xfs_shared.h"
8 #include "xfs_format.h"
9 #include "xfs_bit.h"
10 #include "xfs_log_format.h"
11 #include "xfs_trans_resv.h"
12 #include "xfs_mount.h"
13 #include "xfs_inode.h"
14 #include "xfs_trace.h"
15
16 /*
17 * In-core extent record layout:
18 *
19 * +-------+----------------------------+
20 * | 00:53 | all 54 bits of startoff |
21 * | 54:63 | low 10 bits of startblock |
22 * +-------+----------------------------+
23 * | 00:20 | all 21 bits of length |
24 * | 21 | unwritten extent bit |
25 * | 22:63 | high 42 bits of startblock |
26 * +-------+----------------------------+
27 */
28 #define XFS_IEXT_STARTOFF_MASK xfs_mask64lo(BMBT_STARTOFF_BITLEN)
29 #define XFS_IEXT_LENGTH_MASK xfs_mask64lo(BMBT_BLOCKCOUNT_BITLEN)
30 #define XFS_IEXT_STARTBLOCK_MASK xfs_mask64lo(BMBT_STARTBLOCK_BITLEN)
31
32 struct xfs_iext_rec {
33 uint64_t lo;
34 uint64_t hi;
35 };
36
37 /*
38 * Given that the length can't be a zero, only an empty hi value indicates an
39 * unused record.
40 */
41 static bool xfs_iext_rec_is_empty(struct xfs_iext_rec *rec)
42 {
43 return rec->hi == 0;
44 }
45
46 static inline void xfs_iext_rec_clear(struct xfs_iext_rec *rec)
47 {
48 rec->lo = 0;
49 rec->hi = 0;
50 }
51
52 static void
53 xfs_iext_set(
54 struct xfs_iext_rec *rec,
55 struct xfs_bmbt_irec *irec)
56 {
57 ASSERT((irec->br_startoff & ~XFS_IEXT_STARTOFF_MASK) == 0);
58 ASSERT((irec->br_blockcount & ~XFS_IEXT_LENGTH_MASK) == 0);
59 ASSERT((irec->br_startblock & ~XFS_IEXT_STARTBLOCK_MASK) == 0);
60
61 rec->lo = irec->br_startoff & XFS_IEXT_STARTOFF_MASK;
62 rec->hi = irec->br_blockcount & XFS_IEXT_LENGTH_MASK;
63
64 rec->lo |= (irec->br_startblock << 54);
65 rec->hi |= ((irec->br_startblock & ~xfs_mask64lo(10)) << (22 - 10));
66
67 if (irec->br_state == XFS_EXT_UNWRITTEN)
68 rec->hi |= (1 << 21);
69 }
70
71 static void
72 xfs_iext_get(
73 struct xfs_bmbt_irec *irec,
74 struct xfs_iext_rec *rec)
75 {
76 irec->br_startoff = rec->lo & XFS_IEXT_STARTOFF_MASK;
77 irec->br_blockcount = rec->hi & XFS_IEXT_LENGTH_MASK;
78
79 irec->br_startblock = rec->lo >> 54;
80 irec->br_startblock |= (rec->hi & xfs_mask64hi(42)) >> (22 - 10);
81
82 if (rec->hi & (1 << 21))
83 irec->br_state = XFS_EXT_UNWRITTEN;
84 else
85 irec->br_state = XFS_EXT_NORM;
86 }
87
88 enum {
89 NODE_SIZE = 256,
90 KEYS_PER_NODE = NODE_SIZE / (sizeof(uint64_t) + sizeof(void *)),
91 RECS_PER_LEAF = (NODE_SIZE - (2 * sizeof(struct xfs_iext_leaf *))) /
92 sizeof(struct xfs_iext_rec),
93 };
94
95 /*
96 * In-core extent btree block layout:
97 *
98 * There are two types of blocks in the btree: leaf and inner (non-leaf) blocks.
99 *
100 * The leaf blocks are made up by %KEYS_PER_NODE extent records, which each
101 * contain the startoffset, blockcount, startblock and unwritten extent flag.
102 * See above for the exact format, followed by pointers to the previous and next
103 * leaf blocks (if there are any).
104 *
105 * The inner (non-leaf) blocks first contain KEYS_PER_NODE lookup keys, followed
106 * by an equal number of pointers to the btree blocks at the next lower level.
107 *
108 * +-------+-------+-------+-------+-------+----------+----------+
109 * Leaf: | rec 1 | rec 2 | rec 3 | rec 4 | rec N | prev-ptr | next-ptr |
110 * +-------+-------+-------+-------+-------+----------+----------+
111 *
112 * +-------+-------+-------+-------+-------+-------+------+-------+
113 * Inner: | key 1 | key 2 | key 3 | key N | ptr 1 | ptr 2 | ptr3 | ptr N |
114 * +-------+-------+-------+-------+-------+-------+------+-------+
115 */
116 struct xfs_iext_node {
117 uint64_t keys[KEYS_PER_NODE];
118 #define XFS_IEXT_KEY_INVALID (1ULL << 63)
119 void *ptrs[KEYS_PER_NODE];
120 };
121
122 struct xfs_iext_leaf {
123 struct xfs_iext_rec recs[RECS_PER_LEAF];
124 struct xfs_iext_leaf *prev;
125 struct xfs_iext_leaf *next;
126 };
127
128 inline xfs_extnum_t xfs_iext_count(struct xfs_ifork *ifp)
129 {
130 return ifp->if_bytes / sizeof(struct xfs_iext_rec);
131 }
132
133 static inline int xfs_iext_max_recs(struct xfs_ifork *ifp)
134 {
135 if (ifp->if_height == 1)
136 return xfs_iext_count(ifp);
137 return RECS_PER_LEAF;
138 }
139
140 static inline struct xfs_iext_rec *cur_rec(struct xfs_iext_cursor *cur)
141 {
142 return &cur->leaf->recs[cur->pos];
143 }
144
145 static inline bool xfs_iext_valid(struct xfs_ifork *ifp,
146 struct xfs_iext_cursor *cur)
147 {
148 if (!cur->leaf)
149 return false;
150 if (cur->pos < 0 || cur->pos >= xfs_iext_max_recs(ifp))
151 return false;
152 if (xfs_iext_rec_is_empty(cur_rec(cur)))
153 return false;
154 return true;
155 }
156
157 static void *
158 xfs_iext_find_first_leaf(
159 struct xfs_ifork *ifp)
160 {
161 struct xfs_iext_node *node = ifp->if_data;
162 int height;
163
164 if (!ifp->if_height)
165 return NULL;
166
167 for (height = ifp->if_height; height > 1; height--) {
168 node = node->ptrs[0];
169 ASSERT(node);
170 }
171
172 return node;
173 }
174
175 static void *
176 xfs_iext_find_last_leaf(
177 struct xfs_ifork *ifp)
178 {
179 struct xfs_iext_node *node = ifp->if_data;
180 int height, i;
181
182 if (!ifp->if_height)
183 return NULL;
184
185 for (height = ifp->if_height; height > 1; height--) {
186 for (i = 1; i < KEYS_PER_NODE; i++)
187 if (!node->ptrs[i])
188 break;
189 node = node->ptrs[i - 1];
190 ASSERT(node);
191 }
192
193 return node;
194 }
195
196 void
197 xfs_iext_first(
198 struct xfs_ifork *ifp,
199 struct xfs_iext_cursor *cur)
200 {
201 cur->pos = 0;
202 cur->leaf = xfs_iext_find_first_leaf(ifp);
203 }
204
205 void
206 xfs_iext_last(
207 struct xfs_ifork *ifp,
208 struct xfs_iext_cursor *cur)
209 {
210 int i;
211
212 cur->leaf = xfs_iext_find_last_leaf(ifp);
213 if (!cur->leaf) {
214 cur->pos = 0;
215 return;
216 }
217
218 for (i = 1; i < xfs_iext_max_recs(ifp); i++) {
219 if (xfs_iext_rec_is_empty(&cur->leaf->recs[i]))
220 break;
221 }
222 cur->pos = i - 1;
223 }
224
225 void
226 xfs_iext_next(
227 struct xfs_ifork *ifp,
228 struct xfs_iext_cursor *cur)
229 {
230 if (!cur->leaf) {
231 ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
232 xfs_iext_first(ifp, cur);
233 return;
234 }
235
236 ASSERT(cur->pos >= 0);
237 ASSERT(cur->pos < xfs_iext_max_recs(ifp));
238
239 cur->pos++;
240 if (ifp->if_height > 1 && !xfs_iext_valid(ifp, cur) &&
241 cur->leaf->next) {
242 cur->leaf = cur->leaf->next;
243 cur->pos = 0;
244 }
245 }
246
247 void
248 xfs_iext_prev(
249 struct xfs_ifork *ifp,
250 struct xfs_iext_cursor *cur)
251 {
252 if (!cur->leaf) {
253 ASSERT(cur->pos <= 0 || cur->pos >= RECS_PER_LEAF);
254 xfs_iext_last(ifp, cur);
255 return;
256 }
257
258 ASSERT(cur->pos >= 0);
259 ASSERT(cur->pos <= RECS_PER_LEAF);
260
261 recurse:
262 do {
263 cur->pos--;
264 if (xfs_iext_valid(ifp, cur))
265 return;
266 } while (cur->pos > 0);
267
268 if (ifp->if_height > 1 && cur->leaf->prev) {
269 cur->leaf = cur->leaf->prev;
270 cur->pos = RECS_PER_LEAF;
271 goto recurse;
272 }
273 }
274
275 static inline int
276 xfs_iext_key_cmp(
277 struct xfs_iext_node *node,
278 int n,
279 xfs_fileoff_t offset)
280 {
281 if (node->keys[n] > offset)
282 return 1;
283 if (node->keys[n] < offset)
284 return -1;
285 return 0;
286 }
287
288 static inline int
289 xfs_iext_rec_cmp(
290 struct xfs_iext_rec *rec,
291 xfs_fileoff_t offset)
292 {
293 uint64_t rec_offset = rec->lo & XFS_IEXT_STARTOFF_MASK;
294 uint32_t rec_len = rec->hi & XFS_IEXT_LENGTH_MASK;
295
296 if (rec_offset > offset)
297 return 1;
298 if (rec_offset + rec_len <= offset)
299 return -1;
300 return 0;
301 }
302
303 static void *
304 xfs_iext_find_level(
305 struct xfs_ifork *ifp,
306 xfs_fileoff_t offset,
307 int level)
308 {
309 struct xfs_iext_node *node = ifp->if_data;
310 int height, i;
311
312 if (!ifp->if_height)
313 return NULL;
314
315 for (height = ifp->if_height; height > level; height--) {
316 for (i = 1; i < KEYS_PER_NODE; i++)
317 if (xfs_iext_key_cmp(node, i, offset) > 0)
318 break;
319
320 node = node->ptrs[i - 1];
321 if (!node)
322 break;
323 }
324
325 return node;
326 }
327
328 static int
329 xfs_iext_node_pos(
330 struct xfs_iext_node *node,
331 xfs_fileoff_t offset)
332 {
333 int i;
334
335 for (i = 1; i < KEYS_PER_NODE; i++) {
336 if (xfs_iext_key_cmp(node, i, offset) > 0)
337 break;
338 }
339
340 return i - 1;
341 }
342
343 static int
344 xfs_iext_node_insert_pos(
345 struct xfs_iext_node *node,
346 xfs_fileoff_t offset)
347 {
348 int i;
349
350 for (i = 0; i < KEYS_PER_NODE; i++) {
351 if (xfs_iext_key_cmp(node, i, offset) > 0)
352 return i;
353 }
354
355 return KEYS_PER_NODE;
356 }
357
358 static int
359 xfs_iext_node_nr_entries(
360 struct xfs_iext_node *node,
361 int start)
362 {
363 int i;
364
365 for (i = start; i < KEYS_PER_NODE; i++) {
366 if (node->keys[i] == XFS_IEXT_KEY_INVALID)
367 break;
368 }
369
370 return i;
371 }
372
373 static int
374 xfs_iext_leaf_nr_entries(
375 struct xfs_ifork *ifp,
376 struct xfs_iext_leaf *leaf,
377 int start)
378 {
379 int i;
380
381 for (i = start; i < xfs_iext_max_recs(ifp); i++) {
382 if (xfs_iext_rec_is_empty(&leaf->recs[i]))
383 break;
384 }
385
386 return i;
387 }
388
389 static inline uint64_t
390 xfs_iext_leaf_key(
391 struct xfs_iext_leaf *leaf,
392 int n)
393 {
394 return leaf->recs[n].lo & XFS_IEXT_STARTOFF_MASK;
395 }
396
397 static inline void *
398 xfs_iext_alloc_node(
399 int size)
400 {
401 return kzalloc(size, GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
402 }
403
404 static void
405 xfs_iext_grow(
406 struct xfs_ifork *ifp)
407 {
408 struct xfs_iext_node *node = xfs_iext_alloc_node(NODE_SIZE);
409 int i;
410
411 if (ifp->if_height == 1) {
412 struct xfs_iext_leaf *prev = ifp->if_data;
413
414 node->keys[0] = xfs_iext_leaf_key(prev, 0);
415 node->ptrs[0] = prev;
416 } else {
417 struct xfs_iext_node *prev = ifp->if_data;
418
419 ASSERT(ifp->if_height > 1);
420
421 node->keys[0] = prev->keys[0];
422 node->ptrs[0] = prev;
423 }
424
425 for (i = 1; i < KEYS_PER_NODE; i++)
426 node->keys[i] = XFS_IEXT_KEY_INVALID;
427
428 ifp->if_data = node;
429 ifp->if_height++;
430 }
431
432 static void
433 xfs_iext_update_node(
434 struct xfs_ifork *ifp,
435 xfs_fileoff_t old_offset,
436 xfs_fileoff_t new_offset,
437 int level,
438 void *ptr)
439 {
440 struct xfs_iext_node *node = ifp->if_data;
441 int height, i;
442
443 for (height = ifp->if_height; height > level; height--) {
444 for (i = 0; i < KEYS_PER_NODE; i++) {
445 if (i > 0 && xfs_iext_key_cmp(node, i, old_offset) > 0)
446 break;
447 if (node->keys[i] == old_offset)
448 node->keys[i] = new_offset;
449 }
450 node = node->ptrs[i - 1];
451 ASSERT(node);
452 }
453
454 ASSERT(node == ptr);
455 }
456
457 static struct xfs_iext_node *
458 xfs_iext_split_node(
459 struct xfs_iext_node **nodep,
460 int *pos,
461 int *nr_entries)
462 {
463 struct xfs_iext_node *node = *nodep;
464 struct xfs_iext_node *new = xfs_iext_alloc_node(NODE_SIZE);
465 const int nr_move = KEYS_PER_NODE / 2;
466 int nr_keep = nr_move + (KEYS_PER_NODE & 1);
467 int i = 0;
468
469 /* for sequential append operations just spill over into the new node */
470 if (*pos == KEYS_PER_NODE) {
471 *nodep = new;
472 *pos = 0;
473 *nr_entries = 0;
474 goto done;
475 }
476
477
478 for (i = 0; i < nr_move; i++) {
479 new->keys[i] = node->keys[nr_keep + i];
480 new->ptrs[i] = node->ptrs[nr_keep + i];
481
482 node->keys[nr_keep + i] = XFS_IEXT_KEY_INVALID;
483 node->ptrs[nr_keep + i] = NULL;
484 }
485
486 if (*pos >= nr_keep) {
487 *nodep = new;
488 *pos -= nr_keep;
489 *nr_entries = nr_move;
490 } else {
491 *nr_entries = nr_keep;
492 }
493 done:
494 for (; i < KEYS_PER_NODE; i++)
495 new->keys[i] = XFS_IEXT_KEY_INVALID;
496 return new;
497 }
498
499 static void
500 xfs_iext_insert_node(
501 struct xfs_ifork *ifp,
502 uint64_t offset,
503 void *ptr,
504 int level)
505 {
506 struct xfs_iext_node *node, *new;
507 int i, pos, nr_entries;
508
509 again:
510 if (ifp->if_height < level)
511 xfs_iext_grow(ifp);
512
513 new = NULL;
514 node = xfs_iext_find_level(ifp, offset, level);
515 pos = xfs_iext_node_insert_pos(node, offset);
516 nr_entries = xfs_iext_node_nr_entries(node, pos);
517
518 ASSERT(pos >= nr_entries || xfs_iext_key_cmp(node, pos, offset) != 0);
519 ASSERT(nr_entries <= KEYS_PER_NODE);
520
521 if (nr_entries == KEYS_PER_NODE)
522 new = xfs_iext_split_node(&node, &pos, &nr_entries);
523
524 /*
525 * Update the pointers in higher levels if the first entry changes
526 * in an existing node.
527 */
528 if (node != new && pos == 0 && nr_entries > 0)
529 xfs_iext_update_node(ifp, node->keys[0], offset, level, node);
530
531 for (i = nr_entries; i > pos; i--) {
532 node->keys[i] = node->keys[i - 1];
533 node->ptrs[i] = node->ptrs[i - 1];
534 }
535 node->keys[pos] = offset;
536 node->ptrs[pos] = ptr;
537
538 if (new) {
539 offset = new->keys[0];
540 ptr = new;
541 level++;
542 goto again;
543 }
544 }
545
546 static struct xfs_iext_leaf *
547 xfs_iext_split_leaf(
548 struct xfs_iext_cursor *cur,
549 int *nr_entries)
550 {
551 struct xfs_iext_leaf *leaf = cur->leaf;
552 struct xfs_iext_leaf *new = xfs_iext_alloc_node(NODE_SIZE);
553 const int nr_move = RECS_PER_LEAF / 2;
554 int nr_keep = nr_move + (RECS_PER_LEAF & 1);
555 int i;
556
557 /* for sequential append operations just spill over into the new node */
558 if (cur->pos == RECS_PER_LEAF) {
559 cur->leaf = new;
560 cur->pos = 0;
561 *nr_entries = 0;
562 goto done;
563 }
564
565 for (i = 0; i < nr_move; i++) {
566 new->recs[i] = leaf->recs[nr_keep + i];
567 xfs_iext_rec_clear(&leaf->recs[nr_keep + i]);
568 }
569
570 if (cur->pos >= nr_keep) {
571 cur->leaf = new;
572 cur->pos -= nr_keep;
573 *nr_entries = nr_move;
574 } else {
575 *nr_entries = nr_keep;
576 }
577 done:
578 if (leaf->next)
579 leaf->next->prev = new;
580 new->next = leaf->next;
581 new->prev = leaf;
582 leaf->next = new;
583 return new;
584 }
585
586 static void
587 xfs_iext_alloc_root(
588 struct xfs_ifork *ifp,
589 struct xfs_iext_cursor *cur)
590 {
591 ASSERT(ifp->if_bytes == 0);
592
593 ifp->if_data = xfs_iext_alloc_node(sizeof(struct xfs_iext_rec));
594 ifp->if_height = 1;
595
596 /* now that we have a node step into it */
597 cur->leaf = ifp->if_data;
598 cur->pos = 0;
599 }
600
601 static void
602 xfs_iext_realloc_root(
603 struct xfs_ifork *ifp,
604 struct xfs_iext_cursor *cur)
605 {
606 int64_t new_size = ifp->if_bytes + sizeof(struct xfs_iext_rec);
607 void *new;
608
609 /* account for the prev/next pointers */
610 if (new_size / sizeof(struct xfs_iext_rec) == RECS_PER_LEAF)
611 new_size = NODE_SIZE;
612
613 new = krealloc(ifp->if_data, new_size,
614 GFP_KERNEL | __GFP_NOLOCKDEP | __GFP_NOFAIL);
615 memset(new + ifp->if_bytes, 0, new_size - ifp->if_bytes);
616 ifp->if_data = new;
617 cur->leaf = new;
618 }
619
620 /*
621 * Increment the sequence counter on extent tree changes. If we are on a COW
622 * fork, this allows the writeback code to skip looking for a COW extent if the
623 * COW fork hasn't changed. We use WRITE_ONCE here to ensure the update to the
624 * sequence counter is seen before the modifications to the extent tree itself
625 * take effect.
626 */
627 static inline void xfs_iext_inc_seq(struct xfs_ifork *ifp)
628 {
629 WRITE_ONCE(ifp->if_seq, READ_ONCE(ifp->if_seq) + 1);
630 }
631
632 void
633 xfs_iext_insert_raw(
634 struct xfs_ifork *ifp,
635 struct xfs_iext_cursor *cur,
636 struct xfs_bmbt_irec *irec)
637 {
638 xfs_fileoff_t offset = irec->br_startoff;
639 struct xfs_iext_leaf *new = NULL;
640 int nr_entries, i;
641
642 xfs_iext_inc_seq(ifp);
643
644 if (ifp->if_height == 0)
645 xfs_iext_alloc_root(ifp, cur);
646 else if (ifp->if_height == 1)
647 xfs_iext_realloc_root(ifp, cur);
648
649 nr_entries = xfs_iext_leaf_nr_entries(ifp, cur->leaf, cur->pos);
650 ASSERT(nr_entries <= RECS_PER_LEAF);
651 ASSERT(cur->pos >= nr_entries ||
652 xfs_iext_rec_cmp(cur_rec(cur), irec->br_startoff) != 0);
653
654 if (nr_entries == RECS_PER_LEAF)
655 new = xfs_iext_split_leaf(cur, &nr_entries);
656
657 /*
658 * Update the pointers in higher levels if the first entry changes
659 * in an existing node.
660 */
661 if (cur->leaf != new && cur->pos == 0 && nr_entries > 0) {
662 xfs_iext_update_node(ifp, xfs_iext_leaf_key(cur->leaf, 0),
663 offset, 1, cur->leaf);
664 }
665
666 for (i = nr_entries; i > cur->pos; i--)
667 cur->leaf->recs[i] = cur->leaf->recs[i - 1];
668 xfs_iext_set(cur_rec(cur), irec);
669 ifp->if_bytes += sizeof(struct xfs_iext_rec);
670
671 if (new)
672 xfs_iext_insert_node(ifp, xfs_iext_leaf_key(new, 0), new, 2);
673 }
674
675 void
676 xfs_iext_insert(
677 struct xfs_inode *ip,
678 struct xfs_iext_cursor *cur,
679 struct xfs_bmbt_irec *irec,
680 int state)
681 {
682 struct xfs_ifork *ifp = xfs_iext_state_to_fork(ip, state);
683
684 xfs_iext_insert_raw(ifp, cur, irec);
685 trace_xfs_iext_insert(ip, cur, state, _RET_IP_);
686 }
687
688 static struct xfs_iext_node *
689 xfs_iext_rebalance_node(
690 struct xfs_iext_node *parent,
691 int *pos,
692 struct xfs_iext_node *node,
693 int nr_entries)
694 {
695 /*
696 * If the neighbouring nodes are completely full, or have different
697 * parents, we might never be able to merge our node, and will only
698 * delete it once the number of entries hits zero.
699 */
700 if (nr_entries == 0)
701 return node;
702
703 if (*pos > 0) {
704 struct xfs_iext_node *prev = parent->ptrs[*pos - 1];
705 int nr_prev = xfs_iext_node_nr_entries(prev, 0), i;
706
707 if (nr_prev + nr_entries <= KEYS_PER_NODE) {
708 for (i = 0; i < nr_entries; i++) {
709 prev->keys[nr_prev + i] = node->keys[i];
710 prev->ptrs[nr_prev + i] = node->ptrs[i];
711 }
712 return node;
713 }
714 }
715
716 if (*pos + 1 < xfs_iext_node_nr_entries(parent, *pos)) {
717 struct xfs_iext_node *next = parent->ptrs[*pos + 1];
718 int nr_next = xfs_iext_node_nr_entries(next, 0), i;
719
720 if (nr_entries + nr_next <= KEYS_PER_NODE) {
721 /*
722 * Merge the next node into this node so that we don't
723 * have to do an additional update of the keys in the
724 * higher levels.
725 */
726 for (i = 0; i < nr_next; i++) {
727 node->keys[nr_entries + i] = next->keys[i];
728 node->ptrs[nr_entries + i] = next->ptrs[i];
729 }
730
731 ++*pos;
732 return next;
733 }
734 }
735
736 return NULL;
737 }
738
739 static void
740 xfs_iext_remove_node(
741 struct xfs_ifork *ifp,
742 xfs_fileoff_t offset,
743 void *victim)
744 {
745 struct xfs_iext_node *node, *parent;
746 int level = 2, pos, nr_entries, i;
747
748 ASSERT(level <= ifp->if_height);
749 node = xfs_iext_find_level(ifp, offset, level);
750 pos = xfs_iext_node_pos(node, offset);
751 again:
752 ASSERT(node->ptrs[pos]);
753 ASSERT(node->ptrs[pos] == victim);
754 kfree(victim);
755
756 nr_entries = xfs_iext_node_nr_entries(node, pos) - 1;
757 offset = node->keys[0];
758 for (i = pos; i < nr_entries; i++) {
759 node->keys[i] = node->keys[i + 1];
760 node->ptrs[i] = node->ptrs[i + 1];
761 }
762 node->keys[nr_entries] = XFS_IEXT_KEY_INVALID;
763 node->ptrs[nr_entries] = NULL;
764
765 if (pos == 0 && nr_entries > 0) {
766 xfs_iext_update_node(ifp, offset, node->keys[0], level, node);
767 offset = node->keys[0];
768 }
769
770 if (nr_entries >= KEYS_PER_NODE / 2)
771 return;
772
773 if (level < ifp->if_height) {
774 /*
775 * If we aren't at the root yet try to find a neighbour node to
776 * merge with (or delete the node if it is empty), and then
777 * recurse up to the next level.
778 */
779 level++;
780 parent = xfs_iext_find_level(ifp, offset, level);
781 pos = xfs_iext_node_pos(parent, offset);
782
783 ASSERT(pos != KEYS_PER_NODE);
784 ASSERT(parent->ptrs[pos] == node);
785
786 node = xfs_iext_rebalance_node(parent, &pos, node, nr_entries);
787 if (node) {
788 victim = node;
789 node = parent;
790 goto again;
791 }
792 } else if (nr_entries == 1) {
793 /*
794 * If we are at the root and only one entry is left we can just
795 * free this node and update the root pointer.
796 */
797 ASSERT(node == ifp->if_data);
798 ifp->if_data = node->ptrs[0];
799 ifp->if_height--;
800 kfree(node);
801 }
802 }
803
804 static void
805 xfs_iext_rebalance_leaf(
806 struct xfs_ifork *ifp,
807 struct xfs_iext_cursor *cur,
808 struct xfs_iext_leaf *leaf,
809 xfs_fileoff_t offset,
810 int nr_entries)
811 {
812 /*
813 * If the neighbouring nodes are completely full we might never be able
814 * to merge our node, and will only delete it once the number of
815 * entries hits zero.
816 */
817 if (nr_entries == 0)
818 goto remove_node;
819
820 if (leaf->prev) {
821 int nr_prev = xfs_iext_leaf_nr_entries(ifp, leaf->prev, 0), i;
822
823 if (nr_prev + nr_entries <= RECS_PER_LEAF) {
824 for (i = 0; i < nr_entries; i++)
825 leaf->prev->recs[nr_prev + i] = leaf->recs[i];
826
827 if (cur->leaf == leaf) {
828 cur->leaf = leaf->prev;
829 cur->pos += nr_prev;
830 }
831 goto remove_node;
832 }
833 }
834
835 if (leaf->next) {
836 int nr_next = xfs_iext_leaf_nr_entries(ifp, leaf->next, 0), i;
837
838 if (nr_entries + nr_next <= RECS_PER_LEAF) {
839 /*
840 * Merge the next node into this node so that we don't
841 * have to do an additional update of the keys in the
842 * higher levels.
843 */
844 for (i = 0; i < nr_next; i++) {
845 leaf->recs[nr_entries + i] =
846 leaf->next->recs[i];
847 }
848
849 if (cur->leaf == leaf->next) {
850 cur->leaf = leaf;
851 cur->pos += nr_entries;
852 }
853
854 offset = xfs_iext_leaf_key(leaf->next, 0);
855 leaf = leaf->next;
856 goto remove_node;
857 }
858 }
859
860 return;
861 remove_node:
862 if (leaf->prev)
863 leaf->prev->next = leaf->next;
864 if (leaf->next)
865 leaf->next->prev = leaf->prev;
866 xfs_iext_remove_node(ifp, offset, leaf);
867 }
868
869 static void
870 xfs_iext_free_last_leaf(
871 struct xfs_ifork *ifp)
872 {
873 ifp->if_height--;
874 kfree(ifp->if_data);
875 ifp->if_data = NULL;
876 }
877
878 void
879 xfs_iext_remove(
880 struct xfs_inode *ip,
881 struct xfs_iext_cursor *cur,
882 int state)
883 {
884 struct xfs_ifork *ifp = xfs_iext_state_to_fork(ip, state);
885 struct xfs_iext_leaf *leaf = cur->leaf;
886 xfs_fileoff_t offset = xfs_iext_leaf_key(leaf, 0);
887 int i, nr_entries;
888
889 trace_xfs_iext_remove(ip, cur, state, _RET_IP_);
890
891 ASSERT(ifp->if_height > 0);
892 ASSERT(ifp->if_data != NULL);
893 ASSERT(xfs_iext_valid(ifp, cur));
894
895 xfs_iext_inc_seq(ifp);
896
897 nr_entries = xfs_iext_leaf_nr_entries(ifp, leaf, cur->pos) - 1;
898 for (i = cur->pos; i < nr_entries; i++)
899 leaf->recs[i] = leaf->recs[i + 1];
900 xfs_iext_rec_clear(&leaf->recs[nr_entries]);
901 ifp->if_bytes -= sizeof(struct xfs_iext_rec);
902
903 if (cur->pos == 0 && nr_entries > 0) {
904 xfs_iext_update_node(ifp, offset, xfs_iext_leaf_key(leaf, 0), 1,
905 leaf);
906 offset = xfs_iext_leaf_key(leaf, 0);
907 } else if (cur->pos == nr_entries) {
908 if (ifp->if_height > 1 && leaf->next)
909 cur->leaf = leaf->next;
910 else
911 cur->leaf = NULL;
912 cur->pos = 0;
913 }
914
915 if (nr_entries >= RECS_PER_LEAF / 2)
916 return;
917
918 if (ifp->if_height > 1)
919 xfs_iext_rebalance_leaf(ifp, cur, leaf, offset, nr_entries);
920 else if (nr_entries == 0)
921 xfs_iext_free_last_leaf(ifp);
922 }
923
924 /*
925 * Lookup the extent covering bno.
926 *
927 * If there is an extent covering bno return the extent index, and store the
928 * expanded extent structure in *gotp, and the extent cursor in *cur.
929 * If there is no extent covering bno, but there is an extent after it (e.g.
930 * it lies in a hole) return that extent in *gotp and its cursor in *cur
931 * instead.
932 * If bno is beyond the last extent return false, and return an invalid
933 * cursor value.
934 */
935 bool
936 xfs_iext_lookup_extent(
937 struct xfs_inode *ip,
938 struct xfs_ifork *ifp,
939 xfs_fileoff_t offset,
940 struct xfs_iext_cursor *cur,
941 struct xfs_bmbt_irec *gotp)
942 {
943 XFS_STATS_INC(ip->i_mount, xs_look_exlist);
944
945 cur->leaf = xfs_iext_find_level(ifp, offset, 1);
946 if (!cur->leaf) {
947 cur->pos = 0;
948 return false;
949 }
950
951 for (cur->pos = 0; cur->pos < xfs_iext_max_recs(ifp); cur->pos++) {
952 struct xfs_iext_rec *rec = cur_rec(cur);
953
954 if (xfs_iext_rec_is_empty(rec))
955 break;
956 if (xfs_iext_rec_cmp(rec, offset) >= 0)
957 goto found;
958 }
959
960 /* Try looking in the next node for an entry > offset */
961 if (ifp->if_height == 1 || !cur->leaf->next)
962 return false;
963 cur->leaf = cur->leaf->next;
964 cur->pos = 0;
965 if (!xfs_iext_valid(ifp, cur))
966 return false;
967 found:
968 xfs_iext_get(gotp, cur_rec(cur));
969 return true;
970 }
971
972 /*
973 * Returns the last extent before end, and if this extent doesn't cover
974 * end, update end to the end of the extent.
975 */
976 bool
977 xfs_iext_lookup_extent_before(
978 struct xfs_inode *ip,
979 struct xfs_ifork *ifp,
980 xfs_fileoff_t *end,
981 struct xfs_iext_cursor *cur,
982 struct xfs_bmbt_irec *gotp)
983 {
984 /* could be optimized to not even look up the next on a match.. */
985 if (xfs_iext_lookup_extent(ip, ifp, *end - 1, cur, gotp) &&
986 gotp->br_startoff <= *end - 1)
987 return true;
988 if (!xfs_iext_prev_extent(ifp, cur, gotp))
989 return false;
990 *end = gotp->br_startoff + gotp->br_blockcount;
991 return true;
992 }
993
994 void
995 xfs_iext_update_extent(
996 struct xfs_inode *ip,
997 int state,
998 struct xfs_iext_cursor *cur,
999 struct xfs_bmbt_irec *new)
1000 {
1001 struct xfs_ifork *ifp = xfs_iext_state_to_fork(ip, state);
1002
1003 xfs_iext_inc_seq(ifp);
1004
1005 if (cur->pos == 0) {
1006 struct xfs_bmbt_irec old;
1007
1008 xfs_iext_get(&old, cur_rec(cur));
1009 if (new->br_startoff != old.br_startoff) {
1010 xfs_iext_update_node(ifp, old.br_startoff,
1011 new->br_startoff, 1, cur->leaf);
1012 }
1013 }
1014
1015 trace_xfs_bmap_pre_update(ip, cur, state, _RET_IP_);
1016 xfs_iext_set(cur_rec(cur), new);
1017 trace_xfs_bmap_post_update(ip, cur, state, _RET_IP_);
1018 }
1019
1020 /*
1021 * Return true if the cursor points at an extent and return the extent structure
1022 * in gotp. Else return false.
1023 */
1024 bool
1025 xfs_iext_get_extent(
1026 struct xfs_ifork *ifp,
1027 struct xfs_iext_cursor *cur,
1028 struct xfs_bmbt_irec *gotp)
1029 {
1030 if (!xfs_iext_valid(ifp, cur))
1031 return false;
1032 xfs_iext_get(gotp, cur_rec(cur));
1033 return true;
1034 }
1035
1036 /*
1037 * This is a recursive function, because of that we need to be extremely
1038 * careful with stack usage.
1039 */
1040 static void
1041 xfs_iext_destroy_node(
1042 struct xfs_iext_node *node,
1043 int level)
1044 {
1045 int i;
1046
1047 if (level > 1) {
1048 for (i = 0; i < KEYS_PER_NODE; i++) {
1049 if (node->keys[i] == XFS_IEXT_KEY_INVALID)
1050 break;
1051 xfs_iext_destroy_node(node->ptrs[i], level - 1);
1052 }
1053 }
1054
1055 kfree(node);
1056 }
1057
1058 void
1059 xfs_iext_destroy(
1060 struct xfs_ifork *ifp)
1061 {
1062 xfs_iext_destroy_node(ifp->if_data, ifp->if_height);
1063
1064 ifp->if_bytes = 0;
1065 ifp->if_height = 0;
1066 ifp->if_data = NULL;
1067 }
1068
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