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transaction handles everywhere
[btrfs-progs-unstable.git] / ctree.c
blob17a3ff2f182818d01a8bdeddb8ad348f740ae298
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 if (!parent_buf) {
298 struct btrfs_buffer *child;
299 u64 blocknr = mid_buf->blocknr;
300
301 if (btrfs_header_nritems(&mid->header) != 1)
302 return 0;
303
304 /* promote the child to a root */
305 child = read_node_slot(root, mid_buf, 0);
306 BUG_ON(!child);
307 root->node = child;
308 path->nodes[level] = NULL;
309 /* once for the path */
310 btrfs_block_release(root, mid_buf);
311 /* once for the root ptr */
312 btrfs_block_release(root, mid_buf);
313 clean_tree_block(trans, root, mid_buf);
314 return btrfs_free_extent(trans, root, blocknr, 1, 1);
315 }
316 parent = &parent_buf->node;
317
318 if (btrfs_header_nritems(&mid->header) >
319 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
320 return 0;
321
322 left_buf = read_node_slot(root, parent_buf, pslot - 1);
323 right_buf = read_node_slot(root, parent_buf, pslot + 1);
324
325 /* first, try to make some room in the middle buffer */
326 if (left_buf) {
327 btrfs_cow_block(trans, root, left_buf, parent_buf, pslot - 1,
328 &left_buf);
329 left = &left_buf->node;
330 orig_slot += btrfs_header_nritems(&left->header);
331 wret = push_node_left(trans, root, left_buf, mid_buf);
332 if (wret < 0)
333 ret = wret;
334 }
335
336 /*
337 * then try to empty the right most buffer into the middle
338 */
339 if (right_buf) {
340 btrfs_cow_block(trans, root, right_buf, parent_buf, pslot + 1,
341 &right_buf);
342 right = &right_buf->node;
343 wret = push_node_left(trans, root, mid_buf, right_buf);
344 if (wret < 0)
345 ret = wret;
346 if (btrfs_header_nritems(&right->header) == 0) {
347 u64 blocknr = right_buf->blocknr;
348 btrfs_block_release(root, right_buf);
349 clean_tree_block(trans, root, right_buf);
350 right_buf = NULL;
351 right = NULL;
352 wret = del_ptr(trans, root, path, level + 1, pslot +
353 1);
354 if (wret)
355 ret = wret;
356 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
357 if (wret)
358 ret = wret;
359 } else {
360 memcpy(&parent->ptrs[pslot + 1].key,
361 &right->ptrs[0].key,
362 sizeof(struct btrfs_disk_key));
363 BUG_ON(list_empty(&parent_buf->dirty));
364 }
365 }
366 if (btrfs_header_nritems(&mid->header) == 1) {
367 /*
368 * we're not allowed to leave a node with one item in the
369 * tree during a delete. A deletion from lower in the tree
370 * could try to delete the only pointer in this node.
371 * So, pull some keys from the left.
372 * There has to be a left pointer at this point because
373 * otherwise we would have pulled some pointers from the
374 * right
375 */
376 BUG_ON(!left_buf);
377 wret = balance_node_right(trans, root, mid_buf, left_buf);
378 if (wret < 0)
379 ret = wret;
380 BUG_ON(wret == 1);
381 }
382 if (btrfs_header_nritems(&mid->header) == 0) {
383 /* we've managed to empty the middle node, drop it */
384 u64 blocknr = mid_buf->blocknr;
385 btrfs_block_release(root, mid_buf);
386 clean_tree_block(trans, root, mid_buf);
387 mid_buf = NULL;
388 mid = NULL;
389 wret = del_ptr(trans, root, path, level + 1, pslot);
390 if (wret)
391 ret = wret;
392 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
393 if (wret)
394 ret = wret;
395 } else {
396 /* update the parent key to reflect our changes */
397 memcpy(&parent->ptrs[pslot].key, &mid->ptrs[0].key,
398 sizeof(struct btrfs_disk_key));
399 BUG_ON(list_empty(&parent_buf->dirty));
400 }
401
402 /* update the path */
403 if (left_buf) {
404 if (btrfs_header_nritems(&left->header) > orig_slot) {
405 left_buf->count++; // released below
406 path->nodes[level] = left_buf;
407 path->slots[level + 1] -= 1;
408 path->slots[level] = orig_slot;
409 if (mid_buf)
410 btrfs_block_release(root, mid_buf);
411 } else {
412 orig_slot -= btrfs_header_nritems(&left->header);
413 path->slots[level] = orig_slot;
414 }
415 }
416 /* double check we haven't messed things up */
417 check_block(root, path, level);
418 if (orig_ptr != btrfs_node_blockptr(&path->nodes[level]->node,
419 path->slots[level]))
420 BUG();
421
422 if (right_buf)
423 btrfs_block_release(root, right_buf);
424 if (left_buf)
425 btrfs_block_release(root, left_buf);
426 return ret;
427 }
428
429 /*
430 * look for key in the tree. path is filled in with nodes along the way
431 * if key is found, we return zero and you can find the item in the leaf
432 * level of the path (level 0)
433 *
434 * If the key isn't found, the path points to the slot where it should
435 * be inserted, and 1 is returned. If there are other errors during the
436 * search a negative error number is returned.
437 *
438 * if ins_len > 0, nodes and leaves will be split as we walk down the
439 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
440 * possible)
441 */
442 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
443 *root, struct btrfs_key *key, struct btrfs_path *p, int
444 ins_len, int cow)
445 {
446 struct btrfs_buffer *b;
447 struct btrfs_buffer *cow_buf;
448 struct btrfs_node *c;
449 int slot;
450 int ret;
451 int level;
452
453 again:
454 b = root->node;
455 b->count++;
456 while (b) {
457 level = btrfs_header_level(&b->node.header);
458 if (cow) {
459 int wret;
460 wret = btrfs_cow_block(trans, root, b, p->nodes[level +
461 1], p->slots[level + 1],
462 &cow_buf);
463 b = cow_buf;
464 }
465 BUG_ON(!cow && ins_len);
466 c = &b->node;
467 p->nodes[level] = b;
468 ret = check_block(root, p, level);
469 if (ret)
470 return -1;
471 ret = bin_search(c, key, &slot);
472 if (!btrfs_is_leaf(c)) {
473 if (ret && slot > 0)
474 slot -= 1;
475 p->slots[level] = slot;
476 if (ins_len > 0 && btrfs_header_nritems(&c->header) ==
477 BTRFS_NODEPTRS_PER_BLOCK(root)) {
478 int sret = split_node(trans, root, p, level);
479 BUG_ON(sret > 0);
480 if (sret)
481 return sret;
482 b = p->nodes[level];
483 c = &b->node;
484 slot = p->slots[level];
485 } else if (ins_len < 0) {
486 int sret = balance_level(trans, root, p,
487 level);
488 if (sret)
489 return sret;
490 b = p->nodes[level];
491 if (!b)
492 goto again;
493 c = &b->node;
494 slot = p->slots[level];
495 BUG_ON(btrfs_header_nritems(&c->header) == 1);
496 }
497 b = read_tree_block(root, btrfs_node_blockptr(c, slot));
498 } else {
499 struct btrfs_leaf *l = (struct btrfs_leaf *)c;
500 p->slots[level] = slot;
501 if (ins_len > 0 && btrfs_leaf_free_space(root, l) <
502 sizeof(struct btrfs_item) + ins_len) {
503 int sret = split_leaf(trans, root, p, ins_len);
504 BUG_ON(sret > 0);
505 if (sret)
506 return sret;
507 }
508 BUG_ON(root->node->count == 1);
509 return ret;
510 }
511 }
512 BUG_ON(root->node->count == 1);
513 return 1;
514 }
515
516 /*
517 * adjust the pointers going up the tree, starting at level
518 * making sure the right key of each node is points to 'key'.
519 * This is used after shifting pointers to the left, so it stops
520 * fixing up pointers when a given leaf/node is not in slot 0 of the
521 * higher levels
522 *
523 * If this fails to write a tree block, it returns -1, but continues
524 * fixing up the blocks in ram so the tree is consistent.
525 */
526 static int fixup_low_keys(struct btrfs_trans_handle *trans, struct btrfs_root
527 *root, struct btrfs_path *path, struct btrfs_disk_key
528 *key, int level)
529 {
530 int i;
531 int ret = 0;
532 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
533 struct btrfs_node *t;
534 int tslot = path->slots[i];
535 if (!path->nodes[i])
536 break;
537 t = &path->nodes[i]->node;
538 memcpy(&t->ptrs[tslot].key, key, sizeof(*key));
539 BUG_ON(list_empty(&path->nodes[i]->dirty));
540 if (tslot != 0)
541 break;
542 }
543 return ret;
544 }
545
546 /*
547 * try to push data from one node into the next node left in the
548 * tree.
549 *
550 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
551 * error, and > 0 if there was no room in the left hand block.
552 */
553 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
554 *root, struct btrfs_buffer *dst_buf, struct
555 btrfs_buffer *src_buf)
556 {
557 struct btrfs_node *src = &src_buf->node;
558 struct btrfs_node *dst = &dst_buf->node;
559 int push_items = 0;
560 int src_nritems;
561 int dst_nritems;
562 int ret = 0;
563
564 src_nritems = btrfs_header_nritems(&src->header);
565 dst_nritems = btrfs_header_nritems(&dst->header);
566 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
567 if (push_items <= 0) {
568 return 1;
569 }
570
571 if (src_nritems < push_items)
572 push_items = src_nritems;
573
574 memcpy(dst->ptrs + dst_nritems, src->ptrs,
575 push_items * sizeof(struct btrfs_key_ptr));
576 if (push_items < src_nritems) {
577 memmove(src->ptrs, src->ptrs + push_items,
578 (src_nritems - push_items) *
579 sizeof(struct btrfs_key_ptr));
580 }
581 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
582 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
583 BUG_ON(list_empty(&src_buf->dirty));
584 BUG_ON(list_empty(&dst_buf->dirty));
585 return ret;
586 }
587
588 /*
589 * try to push data from one node into the next node right in the
590 * tree.
591 *
592 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
593 * error, and > 0 if there was no room in the right hand block.
594 *
595 * this will only push up to 1/2 the contents of the left node over
596 */
597 static int balance_node_right(struct btrfs_trans_handle *trans, struct
598 btrfs_root *root, struct btrfs_buffer *dst_buf,
599 struct btrfs_buffer *src_buf)
600 {
601 struct btrfs_node *src = &src_buf->node;
602 struct btrfs_node *dst = &dst_buf->node;
603 int push_items = 0;
604 int max_push;
605 int src_nritems;
606 int dst_nritems;
607 int ret = 0;
608
609 src_nritems = btrfs_header_nritems(&src->header);
610 dst_nritems = btrfs_header_nritems(&dst->header);
611 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
612 if (push_items <= 0) {
613 return 1;
614 }
615
616 max_push = src_nritems / 2 + 1;
617 /* don't try to empty the node */
618 if (max_push > src_nritems)
619 return 1;
620 if (max_push < push_items)
621 push_items = max_push;
622
623 memmove(dst->ptrs + push_items, dst->ptrs,
624 dst_nritems * sizeof(struct btrfs_key_ptr));
625 memcpy(dst->ptrs, src->ptrs + src_nritems - push_items,
626 push_items * sizeof(struct btrfs_key_ptr));
627
628 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
629 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
630
631 BUG_ON(list_empty(&src_buf->dirty));
632 BUG_ON(list_empty(&dst_buf->dirty));
633 return ret;
634 }
635
636 /*
637 * helper function to insert a new root level in the tree.
638 * A new node is allocated, and a single item is inserted to
639 * point to the existing root
640 *
641 * returns zero on success or < 0 on failure.
642 */
643 static int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root
644 *root, struct btrfs_path *path, int level)
645 {
646 struct btrfs_buffer *t;
647 struct btrfs_node *lower;
648 struct btrfs_node *c;
649 struct btrfs_disk_key *lower_key;
650
651 BUG_ON(path->nodes[level]);
652 BUG_ON(path->nodes[level-1] != root->node);
653
654 t = btrfs_alloc_free_block(trans, root);
655 c = &t->node;
656 memset(c, 0, root->blocksize);
657 btrfs_set_header_nritems(&c->header, 1);
658 btrfs_set_header_level(&c->header, level);
659 btrfs_set_header_blocknr(&c->header, t->blocknr);
660 btrfs_set_header_parentid(&c->header,
661 btrfs_header_parentid(&root->node->node.header));
662 lower = &path->nodes[level-1]->node;
663 if (btrfs_is_leaf(lower))
664 lower_key = &((struct btrfs_leaf *)lower)->items[0].key;
665 else
666 lower_key = &lower->ptrs[0].key;
667 memcpy(&c->ptrs[0].key, lower_key, sizeof(struct btrfs_disk_key));
668 btrfs_set_node_blockptr(c, 0, path->nodes[level - 1]->blocknr);
669 /* the super has an extra ref to root->node */
670 btrfs_block_release(root, root->node);
671 root->node = t;
672 t->count++;
673 path->nodes[level] = t;
674 path->slots[level] = 0;
675 return 0;
676 }
677
678 /*
679 * worker function to insert a single pointer in a node.
680 * the node should have enough room for the pointer already
681 *
682 * slot and level indicate where you want the key to go, and
683 * blocknr is the block the key points to.
684 *
685 * returns zero on success and < 0 on any error
686 */
687 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
688 *root, struct btrfs_path *path, struct btrfs_disk_key
689 *key, u64 blocknr, int slot, int level)
690 {
691 struct btrfs_node *lower;
692 int nritems;
693
694 BUG_ON(!path->nodes[level]);
695 lower = &path->nodes[level]->node;
696 nritems = btrfs_header_nritems(&lower->header);
697 if (slot > nritems)
698 BUG();
699 if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
700 BUG();
701 if (slot != nritems) {
702 memmove(lower->ptrs + slot + 1, lower->ptrs + slot,
703 (nritems - slot) * sizeof(struct btrfs_key_ptr));
704 }
705 memcpy(&lower->ptrs[slot].key, key, sizeof(struct btrfs_disk_key));
706 btrfs_set_node_blockptr(lower, slot, blocknr);
707 btrfs_set_header_nritems(&lower->header, nritems + 1);
708 BUG_ON(list_empty(&path->nodes[level]->dirty));
709 return 0;
710 }
711
712 /*
713 * split the node at the specified level in path in two.
714 * The path is corrected to point to the appropriate node after the split
715 *
716 * Before splitting this tries to make some room in the node by pushing
717 * left and right, if either one works, it returns right away.
718 *
719 * returns 0 on success and < 0 on failure
720 */
721 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
722 *root, struct btrfs_path *path, int level)
723 {
724 struct btrfs_buffer *t;
725 struct btrfs_node *c;
726 struct btrfs_buffer *split_buffer;
727 struct btrfs_node *split;
728 int mid;
729 int ret;
730 int wret;
731 u32 c_nritems;
732
733 t = path->nodes[level];
734 c = &t->node;
735 if (t == root->node) {
736 /* trying to split the root, lets make a new one */
737 ret = insert_new_root(trans, root, path, level + 1);
738 if (ret)
739 return ret;
740 }
741 c_nritems = btrfs_header_nritems(&c->header);
742 split_buffer = btrfs_alloc_free_block(trans, root);
743 split = &split_buffer->node;
744 btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
745 btrfs_set_header_blocknr(&split->header, split_buffer->blocknr);
746 btrfs_set_header_parentid(&split->header,
747 btrfs_header_parentid(&root->node->node.header));
748 mid = (c_nritems + 1) / 2;
749 memcpy(split->ptrs, c->ptrs + mid,
750 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
751 btrfs_set_header_nritems(&split->header, c_nritems - mid);
752 btrfs_set_header_nritems(&c->header, mid);
753 ret = 0;
754
755 BUG_ON(list_empty(&t->dirty));
756 wret = insert_ptr(trans, root, path, &split->ptrs[0].key,
757 split_buffer->blocknr, path->slots[level + 1] + 1,
758 level + 1);
759 if (wret)
760 ret = wret;
761
762 if (path->slots[level] >= mid) {
763 path->slots[level] -= mid;
764 btrfs_block_release(root, t);
765 path->nodes[level] = split_buffer;
766 path->slots[level + 1] += 1;
767 } else {
768 btrfs_block_release(root, split_buffer);
769 }
770 return ret;
771 }
772
773 /*
774 * how many bytes are required to store the items in a leaf. start
775 * and nr indicate which items in the leaf to check. This totals up the
776 * space used both by the item structs and the item data
777 */
778 static int leaf_space_used(struct btrfs_leaf *l, int start, int nr)
779 {
780 int data_len;
781 int end = start + nr - 1;
782
783 if (!nr)
784 return 0;
785 data_len = btrfs_item_end(l->items + start);
786 data_len = data_len - btrfs_item_offset(l->items + end);
787 data_len += sizeof(struct btrfs_item) * nr;
788 return data_len;
789 }
790
791 /*
792 * push some data in the path leaf to the right, trying to free up at
793 * least data_size bytes. returns zero if the push worked, nonzero otherwise
794 *
795 * returns 1 if the push failed because the other node didn't have enough
796 * room, 0 if everything worked out and < 0 if there were major errors.
797 */
798 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
799 *root, struct btrfs_path *path, int data_size)
800 {
801 struct btrfs_buffer *left_buf = path->nodes[0];
802 struct btrfs_leaf *left = &left_buf->leaf;
803 struct btrfs_leaf *right;
804 struct btrfs_buffer *right_buf;
805 struct btrfs_buffer *upper;
806 int slot;
807 int i;
808 int free_space;
809 int push_space = 0;
810 int push_items = 0;
811 struct btrfs_item *item;
812 u32 left_nritems;
813 u32 right_nritems;
814
815 slot = path->slots[1];
816 if (!path->nodes[1]) {
817 return 1;
818 }
819 upper = path->nodes[1];
820 if (slot >= btrfs_header_nritems(&upper->node.header) - 1) {
821 return 1;
822 }
823 right_buf = read_tree_block(root, btrfs_node_blockptr(&upper->node,
824 slot + 1));
825 right = &right_buf->leaf;
826 free_space = btrfs_leaf_free_space(root, right);
827 if (free_space < data_size + sizeof(struct btrfs_item)) {
828 btrfs_block_release(root, right_buf);
829 return 1;
830 }
831 /* cow and double check */
832 btrfs_cow_block(trans, root, right_buf, upper, slot + 1, &right_buf);
833 right = &right_buf->leaf;
834 free_space = btrfs_leaf_free_space(root, right);
835 if (free_space < data_size + sizeof(struct btrfs_item)) {
836 btrfs_block_release(root, right_buf);
837 return 1;
838 }
839
840 left_nritems = btrfs_header_nritems(&left->header);
841 for (i = left_nritems - 1; i >= 0; i--) {
842 item = left->items + i;
843 if (path->slots[0] == i)
844 push_space += data_size + sizeof(*item);
845 if (btrfs_item_size(item) + sizeof(*item) + push_space >
846 free_space)
847 break;
848 push_items++;
849 push_space += btrfs_item_size(item) + sizeof(*item);
850 }
851 if (push_items == 0) {
852 btrfs_block_release(root, right_buf);
853 return 1;
854 }
855 right_nritems = btrfs_header_nritems(&right->header);
856 /* push left to right */
857 push_space = btrfs_item_end(left->items + left_nritems - push_items);
858 push_space -= leaf_data_end(root, left);
859 /* make room in the right data area */
860 memmove(btrfs_leaf_data(right) + leaf_data_end(root, right) -
861 push_space, btrfs_leaf_data(right) + leaf_data_end(root, right),
862 BTRFS_LEAF_DATA_SIZE(root) - leaf_data_end(root, right));
863 /* copy from the left data area */
864 memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - push_space,
865 btrfs_leaf_data(left) + leaf_data_end(root, left), push_space);
866 memmove(right->items + push_items, right->items,
867 right_nritems * sizeof(struct btrfs_item));
868 /* copy the items from left to right */
869 memcpy(right->items, left->items + left_nritems - push_items,
870 push_items * sizeof(struct btrfs_item));
871
872 /* update the item pointers */
873 right_nritems += push_items;
874 btrfs_set_header_nritems(&right->header, right_nritems);
875 push_space = BTRFS_LEAF_DATA_SIZE(root);
876 for (i = 0; i < right_nritems; i++) {
877 btrfs_set_item_offset(right->items + i, push_space -
878 btrfs_item_size(right->items + i));
879 push_space = btrfs_item_offset(right->items + i);
880 }
881 left_nritems -= push_items;
882 btrfs_set_header_nritems(&left->header, left_nritems);
883
884 BUG_ON(list_empty(&left_buf->dirty));
885 BUG_ON(list_empty(&right_buf->dirty));
886 memcpy(&upper->node.ptrs[slot + 1].key,
887 &right->items[0].key, sizeof(struct btrfs_disk_key));
888 BUG_ON(list_empty(&upper->dirty));
889
890 /* then fixup the leaf pointer in the path */
891 if (path->slots[0] >= left_nritems) {
892 path->slots[0] -= left_nritems;
893 btrfs_block_release(root, path->nodes[0]);
894 path->nodes[0] = right_buf;
895 path->slots[1] += 1;
896 } else {
897 btrfs_block_release(root, right_buf);
898 }
899 return 0;
900 }
901 /*
902 * push some data in the path leaf to the left, trying to free up at
903 * least data_size bytes. returns zero if the push worked, nonzero otherwise
904 */
905 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
906 *root, struct btrfs_path *path, int data_size)
907 {
908 struct btrfs_buffer *right_buf = path->nodes[0];
909 struct btrfs_leaf *right = &right_buf->leaf;
910 struct btrfs_buffer *t;
911 struct btrfs_leaf *left;
912 int slot;
913 int i;
914 int free_space;
915 int push_space = 0;
916 int push_items = 0;
917 struct btrfs_item *item;
918 u32 old_left_nritems;
919 int ret = 0;
920 int wret;
921
922 slot = path->slots[1];
923 if (slot == 0) {
924 return 1;
925 }
926 if (!path->nodes[1]) {
927 return 1;
928 }
929 t = read_tree_block(root, btrfs_node_blockptr(&path->nodes[1]->node,
930 slot - 1));
931 left = &t->leaf;
932 free_space = btrfs_leaf_free_space(root, left);
933 if (free_space < data_size + sizeof(struct btrfs_item)) {
934 btrfs_block_release(root, t);
935 return 1;
936 }
937
938 /* cow and double check */
939 btrfs_cow_block(trans, root, t, path->nodes[1], slot - 1, &t);
940 left = &t->leaf;
941 free_space = btrfs_leaf_free_space(root, left);
942 if (free_space < data_size + sizeof(struct btrfs_item)) {
943 btrfs_block_release(root, t);
944 return 1;
945 }
946
947 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
948 item = right->items + i;
949 if (path->slots[0] == i)
950 push_space += data_size + sizeof(*item);
951 if (btrfs_item_size(item) + sizeof(*item) + push_space >
952 free_space)
953 break;
954 push_items++;
955 push_space += btrfs_item_size(item) + sizeof(*item);
956 }
957 if (push_items == 0) {
958 btrfs_block_release(root, t);
959 return 1;
960 }
961 /* push data from right to left */
962 memcpy(left->items + btrfs_header_nritems(&left->header),
963 right->items, push_items * sizeof(struct btrfs_item));
964 push_space = BTRFS_LEAF_DATA_SIZE(root) -
965 btrfs_item_offset(right->items + push_items -1);
966 memcpy(btrfs_leaf_data(left) + leaf_data_end(root, left) - push_space,
967 btrfs_leaf_data(right) +
968 btrfs_item_offset(right->items + push_items - 1),
969 push_space);
970 old_left_nritems = btrfs_header_nritems(&left->header);
971 BUG_ON(old_left_nritems < 0);
972
973 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
974 u32 ioff = btrfs_item_offset(left->items + i);
975 btrfs_set_item_offset(left->items + i, ioff -
976 (BTRFS_LEAF_DATA_SIZE(root) -
977 btrfs_item_offset(left->items +
978 old_left_nritems - 1)));
979 }
980 btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
981
982 /* fixup right node */
983 push_space = btrfs_item_offset(right->items + push_items - 1) -
984 leaf_data_end(root, right);
985 memmove(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
986 push_space, btrfs_leaf_data(right) +
987 leaf_data_end(root, right), push_space);
988 memmove(right->items, right->items + push_items,
989 (btrfs_header_nritems(&right->header) - push_items) *
990 sizeof(struct btrfs_item));
991 btrfs_set_header_nritems(&right->header,
992 btrfs_header_nritems(&right->header) -
993 push_items);
994 push_space = BTRFS_LEAF_DATA_SIZE(root);
995
996 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
997 btrfs_set_item_offset(right->items + i, push_space -
998 btrfs_item_size(right->items + i));
999 push_space = btrfs_item_offset(right->items + i);
1000 }
1001
1002 BUG_ON(list_empty(&t->dirty));
1003 BUG_ON(list_empty(&right_buf->dirty));
1004
1005 wret = fixup_low_keys(trans, root, path, &right->items[0].key, 1);
1006 if (wret)
1007 ret = wret;
1008
1009 /* then fixup the leaf pointer in the path */
1010 if (path->slots[0] < push_items) {
1011 path->slots[0] += old_left_nritems;
1012 btrfs_block_release(root, path->nodes[0]);
1013 path->nodes[0] = t;
1014 path->slots[1] -= 1;
1015 } else {
1016 btrfs_block_release(root, t);
1017 path->slots[0] -= push_items;
1018 }
1019 BUG_ON(path->slots[0] < 0);
1020 return ret;
1021 }
1022
1023 /*
1024 * split the path's leaf in two, making sure there is at least data_size
1025 * available for the resulting leaf level of the path.
1026 *
1027 * returns 0 if all went well and < 0 on failure.
1028 */
1029 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1030 *root, struct btrfs_path *path, int data_size)
1031 {
1032 struct btrfs_buffer *l_buf;
1033 struct btrfs_leaf *l;
1034 u32 nritems;
1035 int mid;
1036 int slot;
1037 struct btrfs_leaf *right;
1038 struct btrfs_buffer *right_buffer;
1039 int space_needed = data_size + sizeof(struct btrfs_item);
1040 int data_copy_size;
1041 int rt_data_off;
1042 int i;
1043 int ret;
1044 int wret;
1045
1046 wret = push_leaf_left(trans, root, path, data_size);
1047 if (wret < 0)
1048 return wret;
1049 if (wret) {
1050 wret = push_leaf_right(trans, root, path, data_size);
1051 if (wret < 0)
1052 return wret;
1053 }
1054 l_buf = path->nodes[0];
1055 l = &l_buf->leaf;
1056
1057 /* did the pushes work? */
1058 if (btrfs_leaf_free_space(root, l) >=
1059 sizeof(struct btrfs_item) + data_size)
1060 return 0;
1061
1062 if (!path->nodes[1]) {
1063 ret = insert_new_root(trans, root, path, 1);
1064 if (ret)
1065 return ret;
1066 }
1067 slot = path->slots[0];
1068 nritems = btrfs_header_nritems(&l->header);
1069 mid = (nritems + 1)/ 2;
1070 right_buffer = btrfs_alloc_free_block(trans, root);
1071 BUG_ON(!right_buffer);
1072 BUG_ON(mid == nritems);
1073 right = &right_buffer->leaf;
1074 memset(&right->header, 0, sizeof(right->header));
1075 if (mid <= slot) {
1076 /* FIXME, just alloc a new leaf here */
1077 if (leaf_space_used(l, mid, nritems - mid) + space_needed >
1078 BTRFS_LEAF_DATA_SIZE(root))
1079 BUG();
1080 } else {
1081 /* FIXME, just alloc a new leaf here */
1082 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1083 BTRFS_LEAF_DATA_SIZE(root))
1084 BUG();
1085 }
1086 btrfs_set_header_nritems(&right->header, nritems - mid);
1087 btrfs_set_header_blocknr(&right->header, right_buffer->blocknr);
1088 btrfs_set_header_level(&right->header, 0);
1089 btrfs_set_header_parentid(&right->header,
1090 btrfs_header_parentid(&root->node->node.header));
1091 data_copy_size = btrfs_item_end(l->items + mid) -
1092 leaf_data_end(root, l);
1093 memcpy(right->items, l->items + mid,
1094 (nritems - mid) * sizeof(struct btrfs_item));
1095 memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1096 data_copy_size, btrfs_leaf_data(l) +
1097 leaf_data_end(root, l), data_copy_size);
1098 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1099 btrfs_item_end(l->items + mid);
1100
1101 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1102 u32 ioff = btrfs_item_offset(right->items + i);
1103 btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
1104 }
1105
1106 btrfs_set_header_nritems(&l->header, mid);
1107 ret = 0;
1108 wret = insert_ptr(trans, root, path, &right->items[0].key,
1109 right_buffer->blocknr, path->slots[1] + 1, 1);
1110 if (wret)
1111 ret = wret;
1112 BUG_ON(list_empty(&right_buffer->dirty));
1113 BUG_ON(list_empty(&l_buf->dirty));
1114 BUG_ON(path->slots[0] != slot);
1115 if (mid <= slot) {
1116 btrfs_block_release(root, path->nodes[0]);
1117 path->nodes[0] = right_buffer;
1118 path->slots[0] -= mid;
1119 path->slots[1] += 1;
1120 } else
1121 btrfs_block_release(root, right_buffer);
1122 BUG_ON(path->slots[0] < 0);
1123 return ret;
1124 }
1125
1126 /*
1127 * Given a key and some data, insert an item into the tree.
1128 * This does all the path init required, making room in the tree if needed.
1129 */
1130 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
1131 *root, struct btrfs_path *path, struct btrfs_key
1132 *cpu_key, u32 data_size)
1133 {
1134 int ret = 0;
1135 int slot;
1136 int slot_orig;
1137 struct btrfs_leaf *leaf;
1138 struct btrfs_buffer *leaf_buf;
1139 u32 nritems;
1140 unsigned int data_end;
1141 struct btrfs_disk_key disk_key;
1142
1143 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1144
1145 /* create a root if there isn't one */
1146 if (!root->node)
1147 BUG();
1148 ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
1149 if (ret == 0) {
1150 btrfs_release_path(root, path);
1151 return -EEXIST;
1152 }
1153 if (ret < 0)
1154 goto out;
1155
1156 slot_orig = path->slots[0];
1157 leaf_buf = path->nodes[0];
1158 leaf = &leaf_buf->leaf;
1159
1160 nritems = btrfs_header_nritems(&leaf->header);
1161 data_end = leaf_data_end(root, leaf);
1162
1163 if (btrfs_leaf_free_space(root, leaf) <
1164 sizeof(struct btrfs_item) + data_size)
1165 BUG();
1166
1167 slot = path->slots[0];
1168 BUG_ON(slot < 0);
1169 if (slot != nritems) {
1170 int i;
1171 unsigned int old_data = btrfs_item_end(leaf->items + slot);
1172
1173 /*
1174 * item0..itemN ... dataN.offset..dataN.size .. data0.size
1175 */
1176 /* first correct the data pointers */
1177 for (i = slot; i < nritems; i++) {
1178 u32 ioff = btrfs_item_offset(leaf->items + i);
1179 btrfs_set_item_offset(leaf->items + i,
1180 ioff - data_size);
1181 }
1182
1183 /* shift the items */
1184 memmove(leaf->items + slot + 1, leaf->items + slot,
1185 (nritems - slot) * sizeof(struct btrfs_item));
1186
1187 /* shift the data */
1188 memmove(btrfs_leaf_data(leaf) + data_end - data_size,
1189 btrfs_leaf_data(leaf) +
1190 data_end, old_data - data_end);
1191 data_end = old_data;
1192 }
1193 /* setup the item for the new data */
1194 memcpy(&leaf->items[slot].key, &disk_key,
1195 sizeof(struct btrfs_disk_key));
1196 btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
1197 btrfs_set_item_size(leaf->items + slot, data_size);
1198 btrfs_set_header_nritems(&leaf->header, nritems + 1);
1199
1200 ret = 0;
1201 if (slot == 0)
1202 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
1203
1204 BUG_ON(list_empty(&leaf_buf->dirty));
1205 if (btrfs_leaf_free_space(root, leaf) < 0)
1206 BUG();
1207 check_leaf(root, path, 0);
1208 out:
1209 return ret;
1210 }
1211
1212 /*
1213 * Given a key and some data, insert an item into the tree.
1214 * This does all the path init required, making room in the tree if needed.
1215 */
1216 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
1217 *root, struct btrfs_key *cpu_key, void *data, u32
1218 data_size)
1219 {
1220 int ret = 0;
1221 struct btrfs_path path;
1222 u8 *ptr;
1223
1224 btrfs_init_path(&path);
1225 ret = btrfs_insert_empty_item(trans, root, &path, cpu_key, data_size);
1226 if (!ret) {
1227 ptr = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0], u8);
1228 memcpy(ptr, data, data_size);
1229 }
1230 btrfs_release_path(root, &path);
1231 return ret;
1232 }
1233
1234 /*
1235 * delete the pointer from a given node.
1236 *
1237 * If the delete empties a node, the node is removed from the tree,
1238 * continuing all the way the root if required. The root is converted into
1239 * a leaf if all the nodes are emptied.
1240 */
1241 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1242 struct btrfs_path *path, int level, int slot)
1243 {
1244 struct btrfs_node *node;
1245 struct btrfs_buffer *parent = path->nodes[level];
1246 u32 nritems;
1247 int ret = 0;
1248 int wret;
1249
1250 node = &parent->node;
1251 nritems = btrfs_header_nritems(&node->header);
1252 if (slot != nritems -1) {
1253 memmove(node->ptrs + slot, node->ptrs + slot + 1,
1254 sizeof(struct btrfs_key_ptr) * (nritems - slot - 1));
1255 }
1256 nritems--;
1257 btrfs_set_header_nritems(&node->header, nritems);
1258 if (nritems == 0 && parent == root->node) {
1259 BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
1260 /* just turn the root into a leaf and break */
1261 btrfs_set_header_level(&root->node->node.header, 0);
1262 } else if (slot == 0) {
1263 wret = fixup_low_keys(trans, root, path, &node->ptrs[0].key,
1264 level + 1);
1265 if (wret)
1266 ret = wret;
1267 }
1268 BUG_ON(list_empty(&parent->dirty));
1269 return ret;
1270 }
1271
1272 /*
1273 * delete the item at the leaf level in path. If that empties
1274 * the leaf, remove it from the tree
1275 */
1276 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1277 struct btrfs_path *path)
1278 {
1279 int slot;
1280 struct btrfs_leaf *leaf;
1281 struct btrfs_buffer *leaf_buf;
1282 int doff;
1283 int dsize;
1284 int ret = 0;
1285 int wret;
1286 u32 nritems;
1287
1288 leaf_buf = path->nodes[0];
1289 leaf = &leaf_buf->leaf;
1290 slot = path->slots[0];
1291 doff = btrfs_item_offset(leaf->items + slot);
1292 dsize = btrfs_item_size(leaf->items + slot);
1293 nritems = btrfs_header_nritems(&leaf->header);
1294
1295 if (slot != nritems - 1) {
1296 int i;
1297 int data_end = leaf_data_end(root, leaf);
1298 memmove(btrfs_leaf_data(leaf) + data_end + dsize,
1299 btrfs_leaf_data(leaf) + data_end,
1300 doff - data_end);
1301 for (i = slot + 1; i < nritems; i++) {
1302 u32 ioff = btrfs_item_offset(leaf->items + i);
1303 btrfs_set_item_offset(leaf->items + i, ioff + dsize);
1304 }
1305 memmove(leaf->items + slot, leaf->items + slot + 1,
1306 sizeof(struct btrfs_item) *
1307 (nritems - slot - 1));
1308 }
1309 btrfs_set_header_nritems(&leaf->header, nritems - 1);
1310 nritems--;
1311 /* delete the leaf if we've emptied it */
1312 if (nritems == 0) {
1313 if (leaf_buf == root->node) {
1314 btrfs_set_header_level(&leaf->header, 0);
1315 BUG_ON(list_empty(&leaf_buf->dirty));
1316 } else {
1317 clean_tree_block(trans, root, leaf_buf);
1318 wret = del_ptr(trans, root, path, 1, path->slots[1]);
1319 if (wret)
1320 ret = wret;
1321 wret = btrfs_free_extent(trans, root,
1322 leaf_buf->blocknr, 1, 1);
1323 if (wret)
1324 ret = wret;
1325 }
1326 } else {
1327 int used = leaf_space_used(leaf, 0, nritems);
1328 if (slot == 0) {
1329 wret = fixup_low_keys(trans, root, path,
1330 &leaf->items[0].key, 1);
1331 if (wret)
1332 ret = wret;
1333 }
1334 BUG_ON(list_empty(&leaf_buf->dirty));
1335
1336 /* delete the leaf if it is mostly empty */
1337 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
1338 /* push_leaf_left fixes the path.
1339 * make sure the path still points to our leaf
1340 * for possible call to del_ptr below
1341 */
1342 slot = path->slots[1];
1343 leaf_buf->count++;
1344 wret = push_leaf_left(trans, root, path, 1);
1345 if (wret < 0)
1346 ret = wret;
1347 if (path->nodes[0] == leaf_buf &&
1348 btrfs_header_nritems(&leaf->header)) {
1349 wret = push_leaf_right(trans, root, path, 1);
1350 if (wret < 0)
1351 ret = wret;
1352 }
1353 if (btrfs_header_nritems(&leaf->header) == 0) {
1354 u64 blocknr = leaf_buf->blocknr;
1355 clean_tree_block(trans, root, leaf_buf);
1356 wret = del_ptr(trans, root, path, 1, slot);
1357 if (wret)
1358 ret = wret;
1359 btrfs_block_release(root, leaf_buf);
1360 wret = btrfs_free_extent(trans, root, blocknr,
1361 1, 1);
1362 if (wret)
1363 ret = wret;
1364 } else {
1365 btrfs_block_release(root, leaf_buf);
1366 }
1367 }
1368 }
1369 return ret;
1370 }
1371
1372 /*
1373 * walk up the tree as far as required to find the next leaf.
1374 * returns 0 if it found something or 1 if there are no greater leaves.
1375 * returns < 0 on io errors.
1376 */
1377 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
1378 {
1379 int slot;
1380 int level = 1;
1381 u64 blocknr;
1382 struct btrfs_buffer *c;
1383 struct btrfs_buffer *next = NULL;
1384
1385 while(level < BTRFS_MAX_LEVEL) {
1386 if (!path->nodes[level])
1387 return 1;
1388 slot = path->slots[level] + 1;
1389 c = path->nodes[level];
1390 if (slot >= btrfs_header_nritems(&c->node.header)) {
1391 level++;
1392 continue;
1393 }
1394 blocknr = btrfs_node_blockptr(&c->node, slot);
1395 if (next)
1396 btrfs_block_release(root, next);
1397 next = read_tree_block(root, blocknr);
1398 break;
1399 }
1400 path->slots[level] = slot;
1401 while(1) {
1402 level--;
1403 c = path->nodes[level];
1404 btrfs_block_release(root, c);
1405 path->nodes[level] = next;
1406 path->slots[level] = 0;
1407 if (!level)
1408 break;
1409 next = read_tree_block(root,
1410 btrfs_node_blockptr(&next->node, 0));
1411 }
1412 return 0;
1413 }
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