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[deliverable/linux.git] / fs / btrfs / ctree.c
1 #include <stdio.h>
2 #include <stdlib.h>
3 #include "kerncompat.h"
4 #include "radix-tree.h"
5 #include "ctree.h"
6 #include "disk-io.h"
7 #include "print-tree.h"
8
9 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
10 *root, struct btrfs_path *path, int level);
11 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
12 *root, struct btrfs_path *path, int data_size);
13 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
14 *root, struct btrfs_buffer *dst, struct btrfs_buffer
15 *src);
16 static int balance_node_right(struct btrfs_trans_handle *trans, struct
17 btrfs_root *root, struct btrfs_buffer *dst_buf,
18 struct btrfs_buffer *src_buf);
19 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
20 struct btrfs_path *path, int level, int slot);
21
22 inline void btrfs_init_path(struct btrfs_path *p)
23 {
24 memset(p, 0, sizeof(*p));
25 }
26
27 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
28 {
29 int i;
30 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
31 if (!p->nodes[i])
32 break;
33 btrfs_block_release(root, p->nodes[i]);
34 }
35 memset(p, 0, sizeof(*p));
36 }
37
38 static int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
39 *root, struct btrfs_buffer *buf, struct btrfs_buffer
40 *parent, int parent_slot, struct btrfs_buffer
41 **cow_ret)
42 {
43 struct btrfs_buffer *cow;
44
45 if (!list_empty(&buf->dirty)) {
46 *cow_ret = buf;
47 return 0;
48 }
49 cow = btrfs_alloc_free_block(trans, root);
50 memcpy(&cow->node, &buf->node, root->blocksize);
51 btrfs_set_header_blocknr(&cow->node.header, cow->blocknr);
52 *cow_ret = cow;
53 btrfs_inc_ref(trans, root, buf);
54 if (buf == root->node) {
55 root->node = cow;
56 cow->count++;
57 if (buf != root->commit_root)
58 btrfs_free_extent(trans, root, buf->blocknr, 1, 1);
59 btrfs_block_release(root, buf);
60 } else {
61 btrfs_set_node_blockptr(&parent->node, parent_slot,
62 cow->blocknr);
63 BUG_ON(list_empty(&parent->dirty));
64 btrfs_free_extent(trans, root, buf->blocknr, 1, 1);
65 }
66 btrfs_block_release(root, buf);
67 return 0;
68 }
69
70 /*
71 * The leaf data grows from end-to-front in the node.
72 * this returns the address of the start of the last item,
73 * which is the stop of the leaf data stack
74 */
75 static inline unsigned int leaf_data_end(struct btrfs_root *root,
76 struct btrfs_leaf *leaf)
77 {
78 u32 nr = btrfs_header_nritems(&leaf->header);
79 if (nr == 0)
80 return BTRFS_LEAF_DATA_SIZE(root);
81 return btrfs_item_offset(leaf->items + nr - 1);
82 }
83
84 /*
85 * The space between the end of the leaf items and
86 * the start of the leaf data. IOW, how much room
87 * the leaf has left for both items and data
88 */
89 int btrfs_leaf_free_space(struct btrfs_root *root, struct btrfs_leaf *leaf)
90 {
91 int data_end = leaf_data_end(root, leaf);
92 int nritems = btrfs_header_nritems(&leaf->header);
93 char *items_end = (char *)(leaf->items + nritems + 1);
94 return (char *)(btrfs_leaf_data(leaf) + data_end) - (char *)items_end;
95 }
96
97 /*
98 * compare two keys in a memcmp fashion
99 */
100 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
101 {
102 struct btrfs_key k1;
103
104 btrfs_disk_key_to_cpu(&k1, disk);
105
106 if (k1.objectid > k2->objectid)
107 return 1;
108 if (k1.objectid < k2->objectid)
109 return -1;
110 if (k1.flags > k2->flags)
111 return 1;
112 if (k1.flags < k2->flags)
113 return -1;
114 if (k1.offset > k2->offset)
115 return 1;
116 if (k1.offset < k2->offset)
117 return -1;
118 return 0;
119 }
120
121 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
122 int level)
123 {
124 int i;
125 struct btrfs_node *parent = NULL;
126 struct btrfs_node *node = &path->nodes[level]->node;
127 int parent_slot;
128 u32 nritems = btrfs_header_nritems(&node->header);
129
130 if (path->nodes[level + 1])
131 parent = &path->nodes[level + 1]->node;
132 parent_slot = path->slots[level + 1];
133 BUG_ON(nritems == 0);
134 if (parent) {
135 struct btrfs_disk_key *parent_key;
136 parent_key = &parent->ptrs[parent_slot].key;
137 BUG_ON(memcmp(parent_key, &node->ptrs[0].key,
138 sizeof(struct btrfs_disk_key)));
139 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
140 btrfs_header_blocknr(&node->header));
141 }
142 BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
143 for (i = 0; nritems > 1 && i < nritems - 2; i++) {
144 struct btrfs_key cpukey;
145 btrfs_disk_key_to_cpu(&cpukey, &node->ptrs[i + 1].key);
146 BUG_ON(comp_keys(&node->ptrs[i].key, &cpukey) >= 0);
147 }
148 return 0;
149 }
150
151 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
152 int level)
153 {
154 int i;
155 struct btrfs_leaf *leaf = &path->nodes[level]->leaf;
156 struct btrfs_node *parent = NULL;
157 int parent_slot;
158 u32 nritems = btrfs_header_nritems(&leaf->header);
159
160 if (path->nodes[level + 1])
161 parent = &path->nodes[level + 1]->node;
162 parent_slot = path->slots[level + 1];
163 BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
164
165 if (nritems == 0)
166 return 0;
167
168 if (parent) {
169 struct btrfs_disk_key *parent_key;
170 parent_key = &parent->ptrs[parent_slot].key;
171 BUG_ON(memcmp(parent_key, &leaf->items[0].key,
172 sizeof(struct btrfs_disk_key)));
173 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
174 btrfs_header_blocknr(&leaf->header));
175 }
176 for (i = 0; nritems > 1 && i < nritems - 2; i++) {
177 struct btrfs_key cpukey;
178 btrfs_disk_key_to_cpu(&cpukey, &leaf->items[i + 1].key);
179 BUG_ON(comp_keys(&leaf->items[i].key,
180 &cpukey) >= 0);
181 BUG_ON(btrfs_item_offset(leaf->items + i) !=
182 btrfs_item_end(leaf->items + i + 1));
183 if (i == 0) {
184 BUG_ON(btrfs_item_offset(leaf->items + i) +
185 btrfs_item_size(leaf->items + i) !=
186 BTRFS_LEAF_DATA_SIZE(root));
187 }
188 }
189 return 0;
190 }
191
192 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
193 int level)
194 {
195 if (level == 0)
196 return check_leaf(root, path, level);
197 return check_node(root, path, level);
198 }
199
200 /*
201 * search for key in the array p. items p are item_size apart
202 * and there are 'max' items in p
203 * the slot in the array is returned via slot, and it points to
204 * the place where you would insert key if it is not found in
205 * the array.
206 *
207 * slot may point to max if the key is bigger than all of the keys
208 */
209 static int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
210 int max, int *slot)
211 {
212 int low = 0;
213 int high = max;
214 int mid;
215 int ret;
216 struct btrfs_disk_key *tmp;
217
218 while(low < high) {
219 mid = (low + high) / 2;
220 tmp = (struct btrfs_disk_key *)(p + mid * item_size);
221 ret = comp_keys(tmp, key);
222
223 if (ret < 0)
224 low = mid + 1;
225 else if (ret > 0)
226 high = mid;
227 else {
228 *slot = mid;
229 return 0;
230 }
231 }
232 *slot = low;
233 return 1;
234 }
235
236 /*
237 * simple bin_search frontend that does the right thing for
238 * leaves vs nodes
239 */
240 static int bin_search(struct btrfs_node *c, struct btrfs_key *key, int *slot)
241 {
242 if (btrfs_is_leaf(c)) {
243 struct btrfs_leaf *l = (struct btrfs_leaf *)c;
244 return generic_bin_search((void *)l->items,
245 sizeof(struct btrfs_item),
246 key, btrfs_header_nritems(&c->header),
247 slot);
248 } else {
249 return generic_bin_search((void *)c->ptrs,
250 sizeof(struct btrfs_key_ptr),
251 key, btrfs_header_nritems(&c->header),
252 slot);
253 }
254 return -1;
255 }
256
257 static struct btrfs_buffer *read_node_slot(struct btrfs_root *root,
258 struct btrfs_buffer *parent_buf,
259 int slot)
260 {
261 struct btrfs_node *node = &parent_buf->node;
262 if (slot < 0)
263 return NULL;
264 if (slot >= btrfs_header_nritems(&node->header))
265 return NULL;
266 return read_tree_block(root, btrfs_node_blockptr(node, slot));
267 }
268
269 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
270 *root, struct btrfs_path *path, int level)
271 {
272 struct btrfs_buffer *right_buf;
273 struct btrfs_buffer *mid_buf;
274 struct btrfs_buffer *left_buf;
275 struct btrfs_buffer *parent_buf = NULL;
276 struct btrfs_node *right = NULL;
277 struct btrfs_node *mid;
278 struct btrfs_node *left = NULL;
279 struct btrfs_node *parent = NULL;
280 int ret = 0;
281 int wret;
282 int pslot;
283 int orig_slot = path->slots[level];
284 u64 orig_ptr;
285
286 if (level == 0)
287 return 0;
288
289 mid_buf = path->nodes[level];
290 mid = &mid_buf->node;
291 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
292
293 if (level < BTRFS_MAX_LEVEL - 1)
294 parent_buf = path->nodes[level + 1];
295 pslot = path->slots[level + 1];
296
297 /*
298 * deal with the case where there is only one pointer in the root
299 * by promoting the node below to a root
300 */
301 if (!parent_buf) {
302 struct btrfs_buffer *child;
303 u64 blocknr = mid_buf->blocknr;
304
305 if (btrfs_header_nritems(&mid->header) != 1)
306 return 0;
307
308 /* promote the child to a root */
309 child = read_node_slot(root, mid_buf, 0);
310 BUG_ON(!child);
311 root->node = child;
312 path->nodes[level] = NULL;
313 /* once for the path */
314 btrfs_block_release(root, mid_buf);
315 /* once for the root ptr */
316 btrfs_block_release(root, mid_buf);
317 clean_tree_block(trans, root, mid_buf);
318 return btrfs_free_extent(trans, root, blocknr, 1, 1);
319 }
320 parent = &parent_buf->node;
321
322 if (btrfs_header_nritems(&mid->header) >
323 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
324 return 0;
325
326 left_buf = read_node_slot(root, parent_buf, pslot - 1);
327 right_buf = read_node_slot(root, parent_buf, pslot + 1);
328
329 /* first, try to make some room in the middle buffer */
330 if (left_buf) {
331 btrfs_cow_block(trans, root, left_buf, parent_buf, pslot - 1,
332 &left_buf);
333 left = &left_buf->node;
334 orig_slot += btrfs_header_nritems(&left->header);
335 wret = push_node_left(trans, root, left_buf, mid_buf);
336 if (wret < 0)
337 ret = wret;
338 }
339
340 /*
341 * then try to empty the right most buffer into the middle
342 */
343 if (right_buf) {
344 btrfs_cow_block(trans, root, right_buf, parent_buf, pslot + 1,
345 &right_buf);
346 right = &right_buf->node;
347 wret = push_node_left(trans, root, mid_buf, right_buf);
348 if (wret < 0)
349 ret = wret;
350 if (btrfs_header_nritems(&right->header) == 0) {
351 u64 blocknr = right_buf->blocknr;
352 btrfs_block_release(root, right_buf);
353 clean_tree_block(trans, root, right_buf);
354 right_buf = NULL;
355 right = NULL;
356 wret = del_ptr(trans, root, path, level + 1, pslot +
357 1);
358 if (wret)
359 ret = wret;
360 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
361 if (wret)
362 ret = wret;
363 } else {
364 memcpy(&parent->ptrs[pslot + 1].key,
365 &right->ptrs[0].key,
366 sizeof(struct btrfs_disk_key));
367 BUG_ON(list_empty(&parent_buf->dirty));
368 }
369 }
370 if (btrfs_header_nritems(&mid->header) == 1) {
371 /*
372 * we're not allowed to leave a node with one item in the
373 * tree during a delete. A deletion from lower in the tree
374 * could try to delete the only pointer in this node.
375 * So, pull some keys from the left.
376 * There has to be a left pointer at this point because
377 * otherwise we would have pulled some pointers from the
378 * right
379 */
380 BUG_ON(!left_buf);
381 wret = balance_node_right(trans, root, mid_buf, left_buf);
382 if (wret < 0)
383 ret = wret;
384 BUG_ON(wret == 1);
385 }
386 if (btrfs_header_nritems(&mid->header) == 0) {
387 /* we've managed to empty the middle node, drop it */
388 u64 blocknr = mid_buf->blocknr;
389 btrfs_block_release(root, mid_buf);
390 clean_tree_block(trans, root, mid_buf);
391 mid_buf = NULL;
392 mid = NULL;
393 wret = del_ptr(trans, root, path, level + 1, pslot);
394 if (wret)
395 ret = wret;
396 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
397 if (wret)
398 ret = wret;
399 } else {
400 /* update the parent key to reflect our changes */
401 memcpy(&parent->ptrs[pslot].key, &mid->ptrs[0].key,
402 sizeof(struct btrfs_disk_key));
403 BUG_ON(list_empty(&parent_buf->dirty));
404 }
405
406 /* update the path */
407 if (left_buf) {
408 if (btrfs_header_nritems(&left->header) > orig_slot) {
409 left_buf->count++; // released below
410 path->nodes[level] = left_buf;
411 path->slots[level + 1] -= 1;
412 path->slots[level] = orig_slot;
413 if (mid_buf)
414 btrfs_block_release(root, mid_buf);
415 } else {
416 orig_slot -= btrfs_header_nritems(&left->header);
417 path->slots[level] = orig_slot;
418 }
419 }
420 /* double check we haven't messed things up */
421 check_block(root, path, level);
422 if (orig_ptr != btrfs_node_blockptr(&path->nodes[level]->node,
423 path->slots[level]))
424 BUG();
425
426 if (right_buf)
427 btrfs_block_release(root, right_buf);
428 if (left_buf)
429 btrfs_block_release(root, left_buf);
430 return ret;
431 }
432
433 /*
434 * look for key in the tree. path is filled in with nodes along the way
435 * if key is found, we return zero and you can find the item in the leaf
436 * level of the path (level 0)
437 *
438 * If the key isn't found, the path points to the slot where it should
439 * be inserted, and 1 is returned. If there are other errors during the
440 * search a negative error number is returned.
441 *
442 * if ins_len > 0, nodes and leaves will be split as we walk down the
443 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
444 * possible)
445 */
446 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
447 *root, struct btrfs_key *key, struct btrfs_path *p, int
448 ins_len, int cow)
449 {
450 struct btrfs_buffer *b;
451 struct btrfs_buffer *cow_buf;
452 struct btrfs_node *c;
453 int slot;
454 int ret;
455 int level;
456
457 again:
458 b = root->node;
459 b->count++;
460 while (b) {
461 level = btrfs_header_level(&b->node.header);
462 if (cow) {
463 int wret;
464 wret = btrfs_cow_block(trans, root, b, p->nodes[level +
465 1], p->slots[level + 1],
466 &cow_buf);
467 b = cow_buf;
468 }
469 BUG_ON(!cow && ins_len);
470 c = &b->node;
471 p->nodes[level] = b;
472 ret = check_block(root, p, level);
473 if (ret)
474 return -1;
475 ret = bin_search(c, key, &slot);
476 if (!btrfs_is_leaf(c)) {
477 if (ret && slot > 0)
478 slot -= 1;
479 p->slots[level] = slot;
480 if (ins_len > 0 && btrfs_header_nritems(&c->header) ==
481 BTRFS_NODEPTRS_PER_BLOCK(root)) {
482 int sret = split_node(trans, root, p, level);
483 BUG_ON(sret > 0);
484 if (sret)
485 return sret;
486 b = p->nodes[level];
487 c = &b->node;
488 slot = p->slots[level];
489 } else if (ins_len < 0) {
490 int sret = balance_level(trans, root, p,
491 level);
492 if (sret)
493 return sret;
494 b = p->nodes[level];
495 if (!b)
496 goto again;
497 c = &b->node;
498 slot = p->slots[level];
499 BUG_ON(btrfs_header_nritems(&c->header) == 1);
500 }
501 b = read_tree_block(root, btrfs_node_blockptr(c, slot));
502 } else {
503 struct btrfs_leaf *l = (struct btrfs_leaf *)c;
504 p->slots[level] = slot;
505 if (ins_len > 0 && btrfs_leaf_free_space(root, l) <
506 sizeof(struct btrfs_item) + ins_len) {
507 int sret = split_leaf(trans, root, p, ins_len);
508 BUG_ON(sret > 0);
509 if (sret)
510 return sret;
511 }
512 BUG_ON(root->node->count == 1);
513 return ret;
514 }
515 }
516 BUG_ON(root->node->count == 1);
517 return 1;
518 }
519
520 /*
521 * adjust the pointers going up the tree, starting at level
522 * making sure the right key of each node is points to 'key'.
523 * This is used after shifting pointers to the left, so it stops
524 * fixing up pointers when a given leaf/node is not in slot 0 of the
525 * higher levels
526 *
527 * If this fails to write a tree block, it returns -1, but continues
528 * fixing up the blocks in ram so the tree is consistent.
529 */
530 static int fixup_low_keys(struct btrfs_trans_handle *trans, struct btrfs_root
531 *root, struct btrfs_path *path, struct btrfs_disk_key
532 *key, int level)
533 {
534 int i;
535 int ret = 0;
536 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
537 struct btrfs_node *t;
538 int tslot = path->slots[i];
539 if (!path->nodes[i])
540 break;
541 t = &path->nodes[i]->node;
542 memcpy(&t->ptrs[tslot].key, key, sizeof(*key));
543 BUG_ON(list_empty(&path->nodes[i]->dirty));
544 if (tslot != 0)
545 break;
546 }
547 return ret;
548 }
549
550 /*
551 * try to push data from one node into the next node left in the
552 * tree.
553 *
554 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
555 * error, and > 0 if there was no room in the left hand block.
556 */
557 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
558 *root, struct btrfs_buffer *dst_buf, struct
559 btrfs_buffer *src_buf)
560 {
561 struct btrfs_node *src = &src_buf->node;
562 struct btrfs_node *dst = &dst_buf->node;
563 int push_items = 0;
564 int src_nritems;
565 int dst_nritems;
566 int ret = 0;
567
568 src_nritems = btrfs_header_nritems(&src->header);
569 dst_nritems = btrfs_header_nritems(&dst->header);
570 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
571 if (push_items <= 0) {
572 return 1;
573 }
574
575 if (src_nritems < push_items)
576 push_items = src_nritems;
577
578 memcpy(dst->ptrs + dst_nritems, src->ptrs,
579 push_items * sizeof(struct btrfs_key_ptr));
580 if (push_items < src_nritems) {
581 memmove(src->ptrs, src->ptrs + push_items,
582 (src_nritems - push_items) *
583 sizeof(struct btrfs_key_ptr));
584 }
585 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
586 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
587 BUG_ON(list_empty(&src_buf->dirty));
588 BUG_ON(list_empty(&dst_buf->dirty));
589 return ret;
590 }
591
592 /*
593 * try to push data from one node into the next node right in the
594 * tree.
595 *
596 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
597 * error, and > 0 if there was no room in the right hand block.
598 *
599 * this will only push up to 1/2 the contents of the left node over
600 */
601 static int balance_node_right(struct btrfs_trans_handle *trans, struct
602 btrfs_root *root, struct btrfs_buffer *dst_buf,
603 struct btrfs_buffer *src_buf)
604 {
605 struct btrfs_node *src = &src_buf->node;
606 struct btrfs_node *dst = &dst_buf->node;
607 int push_items = 0;
608 int max_push;
609 int src_nritems;
610 int dst_nritems;
611 int ret = 0;
612
613 src_nritems = btrfs_header_nritems(&src->header);
614 dst_nritems = btrfs_header_nritems(&dst->header);
615 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
616 if (push_items <= 0) {
617 return 1;
618 }
619
620 max_push = src_nritems / 2 + 1;
621 /* don't try to empty the node */
622 if (max_push > src_nritems)
623 return 1;
624 if (max_push < push_items)
625 push_items = max_push;
626
627 memmove(dst->ptrs + push_items, dst->ptrs,
628 dst_nritems * sizeof(struct btrfs_key_ptr));
629 memcpy(dst->ptrs, src->ptrs + src_nritems - push_items,
630 push_items * sizeof(struct btrfs_key_ptr));
631
632 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
633 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
634
635 BUG_ON(list_empty(&src_buf->dirty));
636 BUG_ON(list_empty(&dst_buf->dirty));
637 return ret;
638 }
639
640 /*
641 * helper function to insert a new root level in the tree.
642 * A new node is allocated, and a single item is inserted to
643 * point to the existing root
644 *
645 * returns zero on success or < 0 on failure.
646 */
647 static int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root
648 *root, struct btrfs_path *path, int level)
649 {
650 struct btrfs_buffer *t;
651 struct btrfs_node *lower;
652 struct btrfs_node *c;
653 struct btrfs_disk_key *lower_key;
654
655 BUG_ON(path->nodes[level]);
656 BUG_ON(path->nodes[level-1] != root->node);
657
658 t = btrfs_alloc_free_block(trans, root);
659 c = &t->node;
660 memset(c, 0, root->blocksize);
661 btrfs_set_header_nritems(&c->header, 1);
662 btrfs_set_header_level(&c->header, level);
663 btrfs_set_header_blocknr(&c->header, t->blocknr);
664 btrfs_set_header_parentid(&c->header,
665 btrfs_header_parentid(&root->node->node.header));
666 lower = &path->nodes[level-1]->node;
667 if (btrfs_is_leaf(lower))
668 lower_key = &((struct btrfs_leaf *)lower)->items[0].key;
669 else
670 lower_key = &lower->ptrs[0].key;
671 memcpy(&c->ptrs[0].key, lower_key, sizeof(struct btrfs_disk_key));
672 btrfs_set_node_blockptr(c, 0, path->nodes[level - 1]->blocknr);
673 /* the super has an extra ref to root->node */
674 btrfs_block_release(root, root->node);
675 root->node = t;
676 t->count++;
677 path->nodes[level] = t;
678 path->slots[level] = 0;
679 return 0;
680 }
681
682 /*
683 * worker function to insert a single pointer in a node.
684 * the node should have enough room for the pointer already
685 *
686 * slot and level indicate where you want the key to go, and
687 * blocknr is the block the key points to.
688 *
689 * returns zero on success and < 0 on any error
690 */
691 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
692 *root, struct btrfs_path *path, struct btrfs_disk_key
693 *key, u64 blocknr, int slot, int level)
694 {
695 struct btrfs_node *lower;
696 int nritems;
697
698 BUG_ON(!path->nodes[level]);
699 lower = &path->nodes[level]->node;
700 nritems = btrfs_header_nritems(&lower->header);
701 if (slot > nritems)
702 BUG();
703 if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
704 BUG();
705 if (slot != nritems) {
706 memmove(lower->ptrs + slot + 1, lower->ptrs + slot,
707 (nritems - slot) * sizeof(struct btrfs_key_ptr));
708 }
709 memcpy(&lower->ptrs[slot].key, key, sizeof(struct btrfs_disk_key));
710 btrfs_set_node_blockptr(lower, slot, blocknr);
711 btrfs_set_header_nritems(&lower->header, nritems + 1);
712 BUG_ON(list_empty(&path->nodes[level]->dirty));
713 return 0;
714 }
715
716 /*
717 * split the node at the specified level in path in two.
718 * The path is corrected to point to the appropriate node after the split
719 *
720 * Before splitting this tries to make some room in the node by pushing
721 * left and right, if either one works, it returns right away.
722 *
723 * returns 0 on success and < 0 on failure
724 */
725 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
726 *root, struct btrfs_path *path, int level)
727 {
728 struct btrfs_buffer *t;
729 struct btrfs_node *c;
730 struct btrfs_buffer *split_buffer;
731 struct btrfs_node *split;
732 int mid;
733 int ret;
734 int wret;
735 u32 c_nritems;
736
737 t = path->nodes[level];
738 c = &t->node;
739 if (t == root->node) {
740 /* trying to split the root, lets make a new one */
741 ret = insert_new_root(trans, root, path, level + 1);
742 if (ret)
743 return ret;
744 }
745 c_nritems = btrfs_header_nritems(&c->header);
746 split_buffer = btrfs_alloc_free_block(trans, root);
747 split = &split_buffer->node;
748 btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
749 btrfs_set_header_blocknr(&split->header, split_buffer->blocknr);
750 btrfs_set_header_parentid(&split->header,
751 btrfs_header_parentid(&root->node->node.header));
752 mid = (c_nritems + 1) / 2;
753 memcpy(split->ptrs, c->ptrs + mid,
754 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
755 btrfs_set_header_nritems(&split->header, c_nritems - mid);
756 btrfs_set_header_nritems(&c->header, mid);
757 ret = 0;
758
759 BUG_ON(list_empty(&t->dirty));
760 wret = insert_ptr(trans, root, path, &split->ptrs[0].key,
761 split_buffer->blocknr, path->slots[level + 1] + 1,
762 level + 1);
763 if (wret)
764 ret = wret;
765
766 if (path->slots[level] >= mid) {
767 path->slots[level] -= mid;
768 btrfs_block_release(root, t);
769 path->nodes[level] = split_buffer;
770 path->slots[level + 1] += 1;
771 } else {
772 btrfs_block_release(root, split_buffer);
773 }
774 return ret;
775 }
776
777 /*
778 * how many bytes are required to store the items in a leaf. start
779 * and nr indicate which items in the leaf to check. This totals up the
780 * space used both by the item structs and the item data
781 */
782 static int leaf_space_used(struct btrfs_leaf *l, int start, int nr)
783 {
784 int data_len;
785 int end = start + nr - 1;
786
787 if (!nr)
788 return 0;
789 data_len = btrfs_item_end(l->items + start);
790 data_len = data_len - btrfs_item_offset(l->items + end);
791 data_len += sizeof(struct btrfs_item) * nr;
792 return data_len;
793 }
794
795 /*
796 * push some data in the path leaf to the right, trying to free up at
797 * least data_size bytes. returns zero if the push worked, nonzero otherwise
798 *
799 * returns 1 if the push failed because the other node didn't have enough
800 * room, 0 if everything worked out and < 0 if there were major errors.
801 */
802 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
803 *root, struct btrfs_path *path, int data_size)
804 {
805 struct btrfs_buffer *left_buf = path->nodes[0];
806 struct btrfs_leaf *left = &left_buf->leaf;
807 struct btrfs_leaf *right;
808 struct btrfs_buffer *right_buf;
809 struct btrfs_buffer *upper;
810 int slot;
811 int i;
812 int free_space;
813 int push_space = 0;
814 int push_items = 0;
815 struct btrfs_item *item;
816 u32 left_nritems;
817 u32 right_nritems;
818
819 slot = path->slots[1];
820 if (!path->nodes[1]) {
821 return 1;
822 }
823 upper = path->nodes[1];
824 if (slot >= btrfs_header_nritems(&upper->node.header) - 1) {
825 return 1;
826 }
827 right_buf = read_tree_block(root, btrfs_node_blockptr(&upper->node,
828 slot + 1));
829 right = &right_buf->leaf;
830 free_space = btrfs_leaf_free_space(root, right);
831 if (free_space < data_size + sizeof(struct btrfs_item)) {
832 btrfs_block_release(root, right_buf);
833 return 1;
834 }
835 /* cow and double check */
836 btrfs_cow_block(trans, root, right_buf, upper, slot + 1, &right_buf);
837 right = &right_buf->leaf;
838 free_space = btrfs_leaf_free_space(root, right);
839 if (free_space < data_size + sizeof(struct btrfs_item)) {
840 btrfs_block_release(root, right_buf);
841 return 1;
842 }
843
844 left_nritems = btrfs_header_nritems(&left->header);
845 for (i = left_nritems - 1; i >= 0; i--) {
846 item = left->items + i;
847 if (path->slots[0] == i)
848 push_space += data_size + sizeof(*item);
849 if (btrfs_item_size(item) + sizeof(*item) + push_space >
850 free_space)
851 break;
852 push_items++;
853 push_space += btrfs_item_size(item) + sizeof(*item);
854 }
855 if (push_items == 0) {
856 btrfs_block_release(root, right_buf);
857 return 1;
858 }
859 right_nritems = btrfs_header_nritems(&right->header);
860 /* push left to right */
861 push_space = btrfs_item_end(left->items + left_nritems - push_items);
862 push_space -= leaf_data_end(root, left);
863 /* make room in the right data area */
864 memmove(btrfs_leaf_data(right) + leaf_data_end(root, right) -
865 push_space, btrfs_leaf_data(right) + leaf_data_end(root, right),
866 BTRFS_LEAF_DATA_SIZE(root) - leaf_data_end(root, right));
867 /* copy from the left data area */
868 memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - push_space,
869 btrfs_leaf_data(left) + leaf_data_end(root, left), push_space);
870 memmove(right->items + push_items, right->items,
871 right_nritems * sizeof(struct btrfs_item));
872 /* copy the items from left to right */
873 memcpy(right->items, left->items + left_nritems - push_items,
874 push_items * sizeof(struct btrfs_item));
875
876 /* update the item pointers */
877 right_nritems += push_items;
878 btrfs_set_header_nritems(&right->header, right_nritems);
879 push_space = BTRFS_LEAF_DATA_SIZE(root);
880 for (i = 0; i < right_nritems; i++) {
881 btrfs_set_item_offset(right->items + i, push_space -
882 btrfs_item_size(right->items + i));
883 push_space = btrfs_item_offset(right->items + i);
884 }
885 left_nritems -= push_items;
886 btrfs_set_header_nritems(&left->header, left_nritems);
887
888 BUG_ON(list_empty(&left_buf->dirty));
889 BUG_ON(list_empty(&right_buf->dirty));
890 memcpy(&upper->node.ptrs[slot + 1].key,
891 &right->items[0].key, sizeof(struct btrfs_disk_key));
892 BUG_ON(list_empty(&upper->dirty));
893
894 /* then fixup the leaf pointer in the path */
895 if (path->slots[0] >= left_nritems) {
896 path->slots[0] -= left_nritems;
897 btrfs_block_release(root, path->nodes[0]);
898 path->nodes[0] = right_buf;
899 path->slots[1] += 1;
900 } else {
901 btrfs_block_release(root, right_buf);
902 }
903 return 0;
904 }
905 /*
906 * push some data in the path leaf to the left, trying to free up at
907 * least data_size bytes. returns zero if the push worked, nonzero otherwise
908 */
909 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
910 *root, struct btrfs_path *path, int data_size)
911 {
912 struct btrfs_buffer *right_buf = path->nodes[0];
913 struct btrfs_leaf *right = &right_buf->leaf;
914 struct btrfs_buffer *t;
915 struct btrfs_leaf *left;
916 int slot;
917 int i;
918 int free_space;
919 int push_space = 0;
920 int push_items = 0;
921 struct btrfs_item *item;
922 u32 old_left_nritems;
923 int ret = 0;
924 int wret;
925
926 slot = path->slots[1];
927 if (slot == 0) {
928 return 1;
929 }
930 if (!path->nodes[1]) {
931 return 1;
932 }
933 t = read_tree_block(root, btrfs_node_blockptr(&path->nodes[1]->node,
934 slot - 1));
935 left = &t->leaf;
936 free_space = btrfs_leaf_free_space(root, left);
937 if (free_space < data_size + sizeof(struct btrfs_item)) {
938 btrfs_block_release(root, t);
939 return 1;
940 }
941
942 /* cow and double check */
943 btrfs_cow_block(trans, root, t, path->nodes[1], slot - 1, &t);
944 left = &t->leaf;
945 free_space = btrfs_leaf_free_space(root, left);
946 if (free_space < data_size + sizeof(struct btrfs_item)) {
947 btrfs_block_release(root, t);
948 return 1;
949 }
950
951 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
952 item = right->items + i;
953 if (path->slots[0] == i)
954 push_space += data_size + sizeof(*item);
955 if (btrfs_item_size(item) + sizeof(*item) + push_space >
956 free_space)
957 break;
958 push_items++;
959 push_space += btrfs_item_size(item) + sizeof(*item);
960 }
961 if (push_items == 0) {
962 btrfs_block_release(root, t);
963 return 1;
964 }
965 /* push data from right to left */
966 memcpy(left->items + btrfs_header_nritems(&left->header),
967 right->items, push_items * sizeof(struct btrfs_item));
968 push_space = BTRFS_LEAF_DATA_SIZE(root) -
969 btrfs_item_offset(right->items + push_items -1);
970 memcpy(btrfs_leaf_data(left) + leaf_data_end(root, left) - push_space,
971 btrfs_leaf_data(right) +
972 btrfs_item_offset(right->items + push_items - 1),
973 push_space);
974 old_left_nritems = btrfs_header_nritems(&left->header);
975 BUG_ON(old_left_nritems < 0);
976
977 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
978 u32 ioff = btrfs_item_offset(left->items + i);
979 btrfs_set_item_offset(left->items + i, ioff -
980 (BTRFS_LEAF_DATA_SIZE(root) -
981 btrfs_item_offset(left->items +
982 old_left_nritems - 1)));
983 }
984 btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
985
986 /* fixup right node */
987 push_space = btrfs_item_offset(right->items + push_items - 1) -
988 leaf_data_end(root, right);
989 memmove(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
990 push_space, btrfs_leaf_data(right) +
991 leaf_data_end(root, right), push_space);
992 memmove(right->items, right->items + push_items,
993 (btrfs_header_nritems(&right->header) - push_items) *
994 sizeof(struct btrfs_item));
995 btrfs_set_header_nritems(&right->header,
996 btrfs_header_nritems(&right->header) -
997 push_items);
998 push_space = BTRFS_LEAF_DATA_SIZE(root);
999
1000 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1001 btrfs_set_item_offset(right->items + i, push_space -
1002 btrfs_item_size(right->items + i));
1003 push_space = btrfs_item_offset(right->items + i);
1004 }
1005
1006 BUG_ON(list_empty(&t->dirty));
1007 BUG_ON(list_empty(&right_buf->dirty));
1008
1009 wret = fixup_low_keys(trans, root, path, &right->items[0].key, 1);
1010 if (wret)
1011 ret = wret;
1012
1013 /* then fixup the leaf pointer in the path */
1014 if (path->slots[0] < push_items) {
1015 path->slots[0] += old_left_nritems;
1016 btrfs_block_release(root, path->nodes[0]);
1017 path->nodes[0] = t;
1018 path->slots[1] -= 1;
1019 } else {
1020 btrfs_block_release(root, t);
1021 path->slots[0] -= push_items;
1022 }
1023 BUG_ON(path->slots[0] < 0);
1024 return ret;
1025 }
1026
1027 /*
1028 * split the path's leaf in two, making sure there is at least data_size
1029 * available for the resulting leaf level of the path.
1030 *
1031 * returns 0 if all went well and < 0 on failure.
1032 */
1033 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1034 *root, struct btrfs_path *path, int data_size)
1035 {
1036 struct btrfs_buffer *l_buf;
1037 struct btrfs_leaf *l;
1038 u32 nritems;
1039 int mid;
1040 int slot;
1041 struct btrfs_leaf *right;
1042 struct btrfs_buffer *right_buffer;
1043 int space_needed = data_size + sizeof(struct btrfs_item);
1044 int data_copy_size;
1045 int rt_data_off;
1046 int i;
1047 int ret;
1048 int wret;
1049
1050 /* first try to make some room by pushing left and right */
1051 wret = push_leaf_left(trans, root, path, data_size);
1052 if (wret < 0)
1053 return wret;
1054 if (wret) {
1055 wret = push_leaf_right(trans, root, path, data_size);
1056 if (wret < 0)
1057 return wret;
1058 }
1059 l_buf = path->nodes[0];
1060 l = &l_buf->leaf;
1061
1062 /* did the pushes work? */
1063 if (btrfs_leaf_free_space(root, l) >=
1064 sizeof(struct btrfs_item) + data_size)
1065 return 0;
1066
1067 if (!path->nodes[1]) {
1068 ret = insert_new_root(trans, root, path, 1);
1069 if (ret)
1070 return ret;
1071 }
1072 slot = path->slots[0];
1073 nritems = btrfs_header_nritems(&l->header);
1074 mid = (nritems + 1)/ 2;
1075 right_buffer = btrfs_alloc_free_block(trans, root);
1076 BUG_ON(!right_buffer);
1077 BUG_ON(mid == nritems);
1078 right = &right_buffer->leaf;
1079 memset(&right->header, 0, sizeof(right->header));
1080 if (mid <= slot) {
1081 /* FIXME, just alloc a new leaf here */
1082 if (leaf_space_used(l, mid, nritems - mid) + space_needed >
1083 BTRFS_LEAF_DATA_SIZE(root))
1084 BUG();
1085 } else {
1086 /* FIXME, just alloc a new leaf here */
1087 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1088 BTRFS_LEAF_DATA_SIZE(root))
1089 BUG();
1090 }
1091 btrfs_set_header_nritems(&right->header, nritems - mid);
1092 btrfs_set_header_blocknr(&right->header, right_buffer->blocknr);
1093 btrfs_set_header_level(&right->header, 0);
1094 btrfs_set_header_parentid(&right->header,
1095 btrfs_header_parentid(&root->node->node.header));
1096 data_copy_size = btrfs_item_end(l->items + mid) -
1097 leaf_data_end(root, l);
1098 memcpy(right->items, l->items + mid,
1099 (nritems - mid) * sizeof(struct btrfs_item));
1100 memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1101 data_copy_size, btrfs_leaf_data(l) +
1102 leaf_data_end(root, l), data_copy_size);
1103 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1104 btrfs_item_end(l->items + mid);
1105
1106 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1107 u32 ioff = btrfs_item_offset(right->items + i);
1108 btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
1109 }
1110
1111 btrfs_set_header_nritems(&l->header, mid);
1112 ret = 0;
1113 wret = insert_ptr(trans, root, path, &right->items[0].key,
1114 right_buffer->blocknr, path->slots[1] + 1, 1);
1115 if (wret)
1116 ret = wret;
1117 BUG_ON(list_empty(&right_buffer->dirty));
1118 BUG_ON(list_empty(&l_buf->dirty));
1119 BUG_ON(path->slots[0] != slot);
1120 if (mid <= slot) {
1121 btrfs_block_release(root, path->nodes[0]);
1122 path->nodes[0] = right_buffer;
1123 path->slots[0] -= mid;
1124 path->slots[1] += 1;
1125 } else
1126 btrfs_block_release(root, right_buffer);
1127 BUG_ON(path->slots[0] < 0);
1128 return ret;
1129 }
1130
1131 /*
1132 * Given a key and some data, insert an item into the tree.
1133 * This does all the path init required, making room in the tree if needed.
1134 */
1135 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
1136 *root, struct btrfs_path *path, struct btrfs_key
1137 *cpu_key, u32 data_size)
1138 {
1139 int ret = 0;
1140 int slot;
1141 int slot_orig;
1142 struct btrfs_leaf *leaf;
1143 struct btrfs_buffer *leaf_buf;
1144 u32 nritems;
1145 unsigned int data_end;
1146 struct btrfs_disk_key disk_key;
1147
1148 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1149
1150 /* create a root if there isn't one */
1151 if (!root->node)
1152 BUG();
1153 ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
1154 if (ret == 0) {
1155 btrfs_release_path(root, path);
1156 return -EEXIST;
1157 }
1158 if (ret < 0)
1159 goto out;
1160
1161 slot_orig = path->slots[0];
1162 leaf_buf = path->nodes[0];
1163 leaf = &leaf_buf->leaf;
1164
1165 nritems = btrfs_header_nritems(&leaf->header);
1166 data_end = leaf_data_end(root, leaf);
1167
1168 if (btrfs_leaf_free_space(root, leaf) <
1169 sizeof(struct btrfs_item) + data_size)
1170 BUG();
1171
1172 slot = path->slots[0];
1173 BUG_ON(slot < 0);
1174 if (slot != nritems) {
1175 int i;
1176 unsigned int old_data = btrfs_item_end(leaf->items + slot);
1177
1178 /*
1179 * item0..itemN ... dataN.offset..dataN.size .. data0.size
1180 */
1181 /* first correct the data pointers */
1182 for (i = slot; i < nritems; i++) {
1183 u32 ioff = btrfs_item_offset(leaf->items + i);
1184 btrfs_set_item_offset(leaf->items + i,
1185 ioff - data_size);
1186 }
1187
1188 /* shift the items */
1189 memmove(leaf->items + slot + 1, leaf->items + slot,
1190 (nritems - slot) * sizeof(struct btrfs_item));
1191
1192 /* shift the data */
1193 memmove(btrfs_leaf_data(leaf) + data_end - data_size,
1194 btrfs_leaf_data(leaf) +
1195 data_end, old_data - data_end);
1196 data_end = old_data;
1197 }
1198 /* setup the item for the new data */
1199 memcpy(&leaf->items[slot].key, &disk_key,
1200 sizeof(struct btrfs_disk_key));
1201 btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
1202 btrfs_set_item_size(leaf->items + slot, data_size);
1203 btrfs_set_header_nritems(&leaf->header, nritems + 1);
1204
1205 ret = 0;
1206 if (slot == 0)
1207 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
1208
1209 BUG_ON(list_empty(&leaf_buf->dirty));
1210 if (btrfs_leaf_free_space(root, leaf) < 0)
1211 BUG();
1212 check_leaf(root, path, 0);
1213 out:
1214 return ret;
1215 }
1216
1217 /*
1218 * Given a key and some data, insert an item into the tree.
1219 * This does all the path init required, making room in the tree if needed.
1220 */
1221 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
1222 *root, struct btrfs_key *cpu_key, void *data, u32
1223 data_size)
1224 {
1225 int ret = 0;
1226 struct btrfs_path path;
1227 u8 *ptr;
1228
1229 btrfs_init_path(&path);
1230 ret = btrfs_insert_empty_item(trans, root, &path, cpu_key, data_size);
1231 if (!ret) {
1232 ptr = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0], u8);
1233 memcpy(ptr, data, data_size);
1234 }
1235 btrfs_release_path(root, &path);
1236 return ret;
1237 }
1238
1239 /*
1240 * delete the pointer from a given node.
1241 *
1242 * If the delete empties a node, the node is removed from the tree,
1243 * continuing all the way the root if required. The root is converted into
1244 * a leaf if all the nodes are emptied.
1245 */
1246 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1247 struct btrfs_path *path, int level, int slot)
1248 {
1249 struct btrfs_node *node;
1250 struct btrfs_buffer *parent = path->nodes[level];
1251 u32 nritems;
1252 int ret = 0;
1253 int wret;
1254
1255 node = &parent->node;
1256 nritems = btrfs_header_nritems(&node->header);
1257 if (slot != nritems -1) {
1258 memmove(node->ptrs + slot, node->ptrs + slot + 1,
1259 sizeof(struct btrfs_key_ptr) * (nritems - slot - 1));
1260 }
1261 nritems--;
1262 btrfs_set_header_nritems(&node->header, nritems);
1263 if (nritems == 0 && parent == root->node) {
1264 BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
1265 /* just turn the root into a leaf and break */
1266 btrfs_set_header_level(&root->node->node.header, 0);
1267 } else if (slot == 0) {
1268 wret = fixup_low_keys(trans, root, path, &node->ptrs[0].key,
1269 level + 1);
1270 if (wret)
1271 ret = wret;
1272 }
1273 BUG_ON(list_empty(&parent->dirty));
1274 return ret;
1275 }
1276
1277 /*
1278 * delete the item at the leaf level in path. If that empties
1279 * the leaf, remove it from the tree
1280 */
1281 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1282 struct btrfs_path *path)
1283 {
1284 int slot;
1285 struct btrfs_leaf *leaf;
1286 struct btrfs_buffer *leaf_buf;
1287 int doff;
1288 int dsize;
1289 int ret = 0;
1290 int wret;
1291 u32 nritems;
1292
1293 leaf_buf = path->nodes[0];
1294 leaf = &leaf_buf->leaf;
1295 slot = path->slots[0];
1296 doff = btrfs_item_offset(leaf->items + slot);
1297 dsize = btrfs_item_size(leaf->items + slot);
1298 nritems = btrfs_header_nritems(&leaf->header);
1299
1300 if (slot != nritems - 1) {
1301 int i;
1302 int data_end = leaf_data_end(root, leaf);
1303 memmove(btrfs_leaf_data(leaf) + data_end + dsize,
1304 btrfs_leaf_data(leaf) + data_end,
1305 doff - data_end);
1306 for (i = slot + 1; i < nritems; i++) {
1307 u32 ioff = btrfs_item_offset(leaf->items + i);
1308 btrfs_set_item_offset(leaf->items + i, ioff + dsize);
1309 }
1310 memmove(leaf->items + slot, leaf->items + slot + 1,
1311 sizeof(struct btrfs_item) *
1312 (nritems - slot - 1));
1313 }
1314 btrfs_set_header_nritems(&leaf->header, nritems - 1);
1315 nritems--;
1316 /* delete the leaf if we've emptied it */
1317 if (nritems == 0) {
1318 if (leaf_buf == root->node) {
1319 btrfs_set_header_level(&leaf->header, 0);
1320 BUG_ON(list_empty(&leaf_buf->dirty));
1321 } else {
1322 clean_tree_block(trans, root, leaf_buf);
1323 wret = del_ptr(trans, root, path, 1, path->slots[1]);
1324 if (wret)
1325 ret = wret;
1326 wret = btrfs_free_extent(trans, root,
1327 leaf_buf->blocknr, 1, 1);
1328 if (wret)
1329 ret = wret;
1330 }
1331 } else {
1332 int used = leaf_space_used(leaf, 0, nritems);
1333 if (slot == 0) {
1334 wret = fixup_low_keys(trans, root, path,
1335 &leaf->items[0].key, 1);
1336 if (wret)
1337 ret = wret;
1338 }
1339 BUG_ON(list_empty(&leaf_buf->dirty));
1340
1341 /* delete the leaf if it is mostly empty */
1342 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
1343 /* push_leaf_left fixes the path.
1344 * make sure the path still points to our leaf
1345 * for possible call to del_ptr below
1346 */
1347 slot = path->slots[1];
1348 leaf_buf->count++;
1349 wret = push_leaf_left(trans, root, path, 1);
1350 if (wret < 0)
1351 ret = wret;
1352 if (path->nodes[0] == leaf_buf &&
1353 btrfs_header_nritems(&leaf->header)) {
1354 wret = push_leaf_right(trans, root, path, 1);
1355 if (wret < 0)
1356 ret = wret;
1357 }
1358 if (btrfs_header_nritems(&leaf->header) == 0) {
1359 u64 blocknr = leaf_buf->blocknr;
1360 clean_tree_block(trans, root, leaf_buf);
1361 wret = del_ptr(trans, root, path, 1, slot);
1362 if (wret)
1363 ret = wret;
1364 btrfs_block_release(root, leaf_buf);
1365 wret = btrfs_free_extent(trans, root, blocknr,
1366 1, 1);
1367 if (wret)
1368 ret = wret;
1369 } else {
1370 btrfs_block_release(root, leaf_buf);
1371 }
1372 }
1373 }
1374 return ret;
1375 }
1376
1377 /*
1378 * walk up the tree as far as required to find the next leaf.
1379 * returns 0 if it found something or 1 if there are no greater leaves.
1380 * returns < 0 on io errors.
1381 */
1382 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
1383 {
1384 int slot;
1385 int level = 1;
1386 u64 blocknr;
1387 struct btrfs_buffer *c;
1388 struct btrfs_buffer *next = NULL;
1389
1390 while(level < BTRFS_MAX_LEVEL) {
1391 if (!path->nodes[level])
1392 return 1;
1393 slot = path->slots[level] + 1;
1394 c = path->nodes[level];
1395 if (slot >= btrfs_header_nritems(&c->node.header)) {
1396 level++;
1397 continue;
1398 }
1399 blocknr = btrfs_node_blockptr(&c->node, slot);
1400 if (next)
1401 btrfs_block_release(root, next);
1402 next = read_tree_block(root, blocknr);
1403 break;
1404 }
1405 path->slots[level] = slot;
1406 while(1) {
1407 level--;
1408 c = path->nodes[level];
1409 btrfs_block_release(root, c);
1410 path->nodes[level] = next;
1411 path->slots[level] = 0;
1412 if (!level)
1413 break;
1414 next = read_tree_block(root,
1415 btrfs_node_blockptr(&next->node, 0));
1416 }
1417 return 0;
1418 }
Linux kernel - Deliverables
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