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add generation to file extents
[btrfs-progs-unstable.git] / ctree.c
blobb0b13bca8c25977728eff88ecfab83730ec42d87
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_level(&split->header, btrfs_header_level(&c->header));
750 btrfs_set_header_blocknr(&split->header, split_buffer->blocknr);
751 btrfs_set_header_parentid(&split->header,
752 btrfs_header_parentid(&root->node->node.header));
753 mid = (c_nritems + 1) / 2;
754 memcpy(split->ptrs, c->ptrs + mid,
755 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
756 btrfs_set_header_nritems(&split->header, c_nritems - mid);
757 btrfs_set_header_nritems(&c->header, mid);
758 ret = 0;
759
760 BUG_ON(list_empty(&t->dirty));
761 wret = insert_ptr(trans, root, path, &split->ptrs[0].key,
762 split_buffer->blocknr, path->slots[level + 1] + 1,
763 level + 1);
764 if (wret)
765 ret = wret;
766
767 if (path->slots[level] >= mid) {
768 path->slots[level] -= mid;
769 btrfs_block_release(root, t);
770 path->nodes[level] = split_buffer;
771 path->slots[level + 1] += 1;
772 } else {
773 btrfs_block_release(root, split_buffer);
774 }
775 return ret;
776 }
777
778 /*
779 * how many bytes are required to store the items in a leaf. start
780 * and nr indicate which items in the leaf to check. This totals up the
781 * space used both by the item structs and the item data
782 */
783 static int leaf_space_used(struct btrfs_leaf *l, int start, int nr)
784 {
785 int data_len;
786 int end = start + nr - 1;
787
788 if (!nr)
789 return 0;
790 data_len = btrfs_item_end(l->items + start);
791 data_len = data_len - btrfs_item_offset(l->items + end);
792 data_len += sizeof(struct btrfs_item) * nr;
793 return data_len;
794 }
795
796 /*
797 * push some data in the path leaf to the right, trying to free up at
798 * least data_size bytes. returns zero if the push worked, nonzero otherwise
799 *
800 * returns 1 if the push failed because the other node didn't have enough
801 * room, 0 if everything worked out and < 0 if there were major errors.
802 */
803 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
804 *root, struct btrfs_path *path, int data_size)
805 {
806 struct btrfs_buffer *left_buf = path->nodes[0];
807 struct btrfs_leaf *left = &left_buf->leaf;
808 struct btrfs_leaf *right;
809 struct btrfs_buffer *right_buf;
810 struct btrfs_buffer *upper;
811 int slot;
812 int i;
813 int free_space;
814 int push_space = 0;
815 int push_items = 0;
816 struct btrfs_item *item;
817 u32 left_nritems;
818 u32 right_nritems;
819
820 slot = path->slots[1];
821 if (!path->nodes[1]) {
822 return 1;
823 }
824 upper = path->nodes[1];
825 if (slot >= btrfs_header_nritems(&upper->node.header) - 1) {
826 return 1;
827 }
828 right_buf = read_tree_block(root, btrfs_node_blockptr(&upper->node,
829 slot + 1));
830 right = &right_buf->leaf;
831 free_space = btrfs_leaf_free_space(root, right);
832 if (free_space < data_size + sizeof(struct btrfs_item)) {
833 btrfs_block_release(root, right_buf);
834 return 1;
835 }
836 /* cow and double check */
837 btrfs_cow_block(trans, root, right_buf, upper, slot + 1, &right_buf);
838 right = &right_buf->leaf;
839 free_space = btrfs_leaf_free_space(root, right);
840 if (free_space < data_size + sizeof(struct btrfs_item)) {
841 btrfs_block_release(root, right_buf);
842 return 1;
843 }
844
845 left_nritems = btrfs_header_nritems(&left->header);
846 for (i = left_nritems - 1; i >= 0; i--) {
847 item = left->items + i;
848 if (path->slots[0] == i)
849 push_space += data_size + sizeof(*item);
850 if (btrfs_item_size(item) + sizeof(*item) + push_space >
851 free_space)
852 break;
853 push_items++;
854 push_space += btrfs_item_size(item) + sizeof(*item);
855 }
856 if (push_items == 0) {
857 btrfs_block_release(root, right_buf);
858 return 1;
859 }
860 right_nritems = btrfs_header_nritems(&right->header);
861 /* push left to right */
862 push_space = btrfs_item_end(left->items + left_nritems - push_items);
863 push_space -= leaf_data_end(root, left);
864 /* make room in the right data area */
865 memmove(btrfs_leaf_data(right) + leaf_data_end(root, right) -
866 push_space, btrfs_leaf_data(right) + leaf_data_end(root, right),
867 BTRFS_LEAF_DATA_SIZE(root) - leaf_data_end(root, right));
868 /* copy from the left data area */
869 memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) - push_space,
870 btrfs_leaf_data(left) + leaf_data_end(root, left), push_space);
871 memmove(right->items + push_items, right->items,
872 right_nritems * sizeof(struct btrfs_item));
873 /* copy the items from left to right */
874 memcpy(right->items, left->items + left_nritems - push_items,
875 push_items * sizeof(struct btrfs_item));
876
877 /* update the item pointers */
878 right_nritems += push_items;
879 btrfs_set_header_nritems(&right->header, right_nritems);
880 push_space = BTRFS_LEAF_DATA_SIZE(root);
881 for (i = 0; i < right_nritems; i++) {
882 btrfs_set_item_offset(right->items + i, push_space -
883 btrfs_item_size(right->items + i));
884 push_space = btrfs_item_offset(right->items + i);
885 }
886 left_nritems -= push_items;
887 btrfs_set_header_nritems(&left->header, left_nritems);
888
889 BUG_ON(list_empty(&left_buf->dirty));
890 BUG_ON(list_empty(&right_buf->dirty));
891 memcpy(&upper->node.ptrs[slot + 1].key,
892 &right->items[0].key, sizeof(struct btrfs_disk_key));
893 BUG_ON(list_empty(&upper->dirty));
894
895 /* then fixup the leaf pointer in the path */
896 if (path->slots[0] >= left_nritems) {
897 path->slots[0] -= left_nritems;
898 btrfs_block_release(root, path->nodes[0]);
899 path->nodes[0] = right_buf;
900 path->slots[1] += 1;
901 } else {
902 btrfs_block_release(root, right_buf);
903 }
904 return 0;
905 }
906 /*
907 * push some data in the path leaf to the left, trying to free up at
908 * least data_size bytes. returns zero if the push worked, nonzero otherwise
909 */
910 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
911 *root, struct btrfs_path *path, int data_size)
912 {
913 struct btrfs_buffer *right_buf = path->nodes[0];
914 struct btrfs_leaf *right = &right_buf->leaf;
915 struct btrfs_buffer *t;
916 struct btrfs_leaf *left;
917 int slot;
918 int i;
919 int free_space;
920 int push_space = 0;
921 int push_items = 0;
922 struct btrfs_item *item;
923 u32 old_left_nritems;
924 int ret = 0;
925 int wret;
926
927 slot = path->slots[1];
928 if (slot == 0) {
929 return 1;
930 }
931 if (!path->nodes[1]) {
932 return 1;
933 }
934 t = read_tree_block(root, btrfs_node_blockptr(&path->nodes[1]->node,
935 slot - 1));
936 left = &t->leaf;
937 free_space = btrfs_leaf_free_space(root, left);
938 if (free_space < data_size + sizeof(struct btrfs_item)) {
939 btrfs_block_release(root, t);
940 return 1;
941 }
942
943 /* cow and double check */
944 btrfs_cow_block(trans, root, t, path->nodes[1], slot - 1, &t);
945 left = &t->leaf;
946 free_space = btrfs_leaf_free_space(root, left);
947 if (free_space < data_size + sizeof(struct btrfs_item)) {
948 btrfs_block_release(root, t);
949 return 1;
950 }
951
952 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
953 item = right->items + i;
954 if (path->slots[0] == i)
955 push_space += data_size + sizeof(*item);
956 if (btrfs_item_size(item) + sizeof(*item) + push_space >
957 free_space)
958 break;
959 push_items++;
960 push_space += btrfs_item_size(item) + sizeof(*item);
961 }
962 if (push_items == 0) {
963 btrfs_block_release(root, t);
964 return 1;
965 }
966 /* push data from right to left */
967 memcpy(left->items + btrfs_header_nritems(&left->header),
968 right->items, push_items * sizeof(struct btrfs_item));
969 push_space = BTRFS_LEAF_DATA_SIZE(root) -
970 btrfs_item_offset(right->items + push_items -1);
971 memcpy(btrfs_leaf_data(left) + leaf_data_end(root, left) - push_space,
972 btrfs_leaf_data(right) +
973 btrfs_item_offset(right->items + push_items - 1),
974 push_space);
975 old_left_nritems = btrfs_header_nritems(&left->header);
976 BUG_ON(old_left_nritems < 0);
977
978 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
979 u32 ioff = btrfs_item_offset(left->items + i);
980 btrfs_set_item_offset(left->items + i, ioff -
981 (BTRFS_LEAF_DATA_SIZE(root) -
982 btrfs_item_offset(left->items +
983 old_left_nritems - 1)));
984 }
985 btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
986
987 /* fixup right node */
988 push_space = btrfs_item_offset(right->items + push_items - 1) -
989 leaf_data_end(root, right);
990 memmove(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
991 push_space, btrfs_leaf_data(right) +
992 leaf_data_end(root, right), push_space);
993 memmove(right->items, right->items + push_items,
994 (btrfs_header_nritems(&right->header) - push_items) *
995 sizeof(struct btrfs_item));
996 btrfs_set_header_nritems(&right->header,
997 btrfs_header_nritems(&right->header) -
998 push_items);
999 push_space = BTRFS_LEAF_DATA_SIZE(root);
1000
1001 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1002 btrfs_set_item_offset(right->items + i, push_space -
1003 btrfs_item_size(right->items + i));
1004 push_space = btrfs_item_offset(right->items + i);
1005 }
1006
1007 BUG_ON(list_empty(&t->dirty));
1008 BUG_ON(list_empty(&right_buf->dirty));
1009
1010 wret = fixup_low_keys(trans, root, path, &right->items[0].key, 1);
1011 if (wret)
1012 ret = wret;
1013
1014 /* then fixup the leaf pointer in the path */
1015 if (path->slots[0] < push_items) {
1016 path->slots[0] += old_left_nritems;
1017 btrfs_block_release(root, path->nodes[0]);
1018 path->nodes[0] = t;
1019 path->slots[1] -= 1;
1020 } else {
1021 btrfs_block_release(root, t);
1022 path->slots[0] -= push_items;
1023 }
1024 BUG_ON(path->slots[0] < 0);
1025 return ret;
1026 }
1027
1028 /*
1029 * split the path's leaf in two, making sure there is at least data_size
1030 * available for the resulting leaf level of the path.
1031 *
1032 * returns 0 if all went well and < 0 on failure.
1033 */
1034 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1035 *root, struct btrfs_path *path, int data_size)
1036 {
1037 struct btrfs_buffer *l_buf;
1038 struct btrfs_leaf *l;
1039 u32 nritems;
1040 int mid;
1041 int slot;
1042 struct btrfs_leaf *right;
1043 struct btrfs_buffer *right_buffer;
1044 int space_needed = data_size + sizeof(struct btrfs_item);
1045 int data_copy_size;
1046 int rt_data_off;
1047 int i;
1048 int ret;
1049 int wret;
1050
1051 /* first try to make some room by pushing left and right */
1052 wret = push_leaf_left(trans, root, path, data_size);
1053 if (wret < 0)
1054 return wret;
1055 if (wret) {
1056 wret = push_leaf_right(trans, root, path, data_size);
1057 if (wret < 0)
1058 return wret;
1059 }
1060 l_buf = path->nodes[0];
1061 l = &l_buf->leaf;
1062
1063 /* did the pushes work? */
1064 if (btrfs_leaf_free_space(root, l) >=
1065 sizeof(struct btrfs_item) + data_size)
1066 return 0;
1067
1068 if (!path->nodes[1]) {
1069 ret = insert_new_root(trans, root, path, 1);
1070 if (ret)
1071 return ret;
1072 }
1073 slot = path->slots[0];
1074 nritems = btrfs_header_nritems(&l->header);
1075 mid = (nritems + 1)/ 2;
1076 right_buffer = btrfs_alloc_free_block(trans, root);
1077 BUG_ON(!right_buffer);
1078 BUG_ON(mid == nritems);
1079 right = &right_buffer->leaf;
1080 memset(&right->header, 0, sizeof(right->header));
1081 if (mid <= slot) {
1082 /* FIXME, just alloc a new leaf here */
1083 if (leaf_space_used(l, mid, nritems - mid) + space_needed >
1084 BTRFS_LEAF_DATA_SIZE(root))
1085 BUG();
1086 } else {
1087 /* FIXME, just alloc a new leaf here */
1088 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1089 BTRFS_LEAF_DATA_SIZE(root))
1090 BUG();
1091 }
1092 btrfs_set_header_nritems(&right->header, nritems - mid);
1093 btrfs_set_header_blocknr(&right->header, right_buffer->blocknr);
1094 btrfs_set_header_level(&right->header, 0);
1095 btrfs_set_header_parentid(&right->header,
1096 btrfs_header_parentid(&root->node->node.header));
1097 data_copy_size = btrfs_item_end(l->items + mid) -
1098 leaf_data_end(root, l);
1099 memcpy(right->items, l->items + mid,
1100 (nritems - mid) * sizeof(struct btrfs_item));
1101 memcpy(btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1102 data_copy_size, btrfs_leaf_data(l) +
1103 leaf_data_end(root, l), data_copy_size);
1104 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1105 btrfs_item_end(l->items + mid);
1106
1107 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1108 u32 ioff = btrfs_item_offset(right->items + i);
1109 btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
1110 }
1111
1112 btrfs_set_header_nritems(&l->header, mid);
1113 ret = 0;
1114 wret = insert_ptr(trans, root, path, &right->items[0].key,
1115 right_buffer->blocknr, path->slots[1] + 1, 1);
1116 if (wret)
1117 ret = wret;
1118 BUG_ON(list_empty(&right_buffer->dirty));
1119 BUG_ON(list_empty(&l_buf->dirty));
1120 BUG_ON(path->slots[0] != slot);
1121 if (mid <= slot) {
1122 btrfs_block_release(root, path->nodes[0]);
1123 path->nodes[0] = right_buffer;
1124 path->slots[0] -= mid;
1125 path->slots[1] += 1;
1126 } else
1127 btrfs_block_release(root, right_buffer);
1128 BUG_ON(path->slots[0] < 0);
1129 return ret;
1130 }
1131
1132 /*
1133 * Given a key and some data, insert an item into the tree.
1134 * This does all the path init required, making room in the tree if needed.
1135 */
1136 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
1137 *root, struct btrfs_path *path, struct btrfs_key
1138 *cpu_key, u32 data_size)
1139 {
1140 int ret = 0;
1141 int slot;
1142 int slot_orig;
1143 struct btrfs_leaf *leaf;
1144 struct btrfs_buffer *leaf_buf;
1145 u32 nritems;
1146 unsigned int data_end;
1147 struct btrfs_disk_key disk_key;
1148
1149 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1150
1151 /* create a root if there isn't one */
1152 if (!root->node)
1153 BUG();
1154 ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
1155 if (ret == 0) {
1156 btrfs_release_path(root, path);
1157 return -EEXIST;
1158 }
1159 if (ret < 0)
1160 goto out;
1161
1162 slot_orig = path->slots[0];
1163 leaf_buf = path->nodes[0];
1164 leaf = &leaf_buf->leaf;
1165
1166 nritems = btrfs_header_nritems(&leaf->header);
1167 data_end = leaf_data_end(root, leaf);
1168
1169 if (btrfs_leaf_free_space(root, leaf) <
1170 sizeof(struct btrfs_item) + data_size)
1171 BUG();
1172
1173 slot = path->slots[0];
1174 BUG_ON(slot < 0);
1175 if (slot != nritems) {
1176 int i;
1177 unsigned int old_data = btrfs_item_end(leaf->items + slot);
1178
1179 /*
1180 * item0..itemN ... dataN.offset..dataN.size .. data0.size
1181 */
1182 /* first correct the data pointers */
1183 for (i = slot; i < nritems; i++) {
1184 u32 ioff = btrfs_item_offset(leaf->items + i);
1185 btrfs_set_item_offset(leaf->items + i,
1186 ioff - data_size);
1187 }
1188
1189 /* shift the items */
1190 memmove(leaf->items + slot + 1, leaf->items + slot,
1191 (nritems - slot) * sizeof(struct btrfs_item));
1192
1193 /* shift the data */
1194 memmove(btrfs_leaf_data(leaf) + data_end - data_size,
1195 btrfs_leaf_data(leaf) +
1196 data_end, old_data - data_end);
1197 data_end = old_data;
1198 }
1199 /* setup the item for the new data */
1200 memcpy(&leaf->items[slot].key, &disk_key,
1201 sizeof(struct btrfs_disk_key));
1202 btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
1203 btrfs_set_item_size(leaf->items + slot, data_size);
1204 btrfs_set_header_nritems(&leaf->header, nritems + 1);
1205
1206 ret = 0;
1207 if (slot == 0)
1208 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
1209
1210 BUG_ON(list_empty(&leaf_buf->dirty));
1211 if (btrfs_leaf_free_space(root, leaf) < 0)
1212 BUG();
1213 check_leaf(root, path, 0);
1214 out:
1215 return ret;
1216 }
1217
1218 /*
1219 * Given a key and some data, insert an item into the tree.
1220 * This does all the path init required, making room in the tree if needed.
1221 */
1222 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
1223 *root, struct btrfs_key *cpu_key, void *data, u32
1224 data_size)
1225 {
1226 int ret = 0;
1227 struct btrfs_path path;
1228 u8 *ptr;
1229
1230 btrfs_init_path(&path);
1231 ret = btrfs_insert_empty_item(trans, root, &path, cpu_key, data_size);
1232 if (!ret) {
1233 ptr = btrfs_item_ptr(&path.nodes[0]->leaf, path.slots[0], u8);
1234 memcpy(ptr, data, data_size);
1235 }
1236 btrfs_release_path(root, &path);
1237 return ret;
1238 }
1239
1240 /*
1241 * delete the pointer from a given node.
1242 *
1243 * If the delete empties a node, the node is removed from the tree,
1244 * continuing all the way the root if required. The root is converted into
1245 * a leaf if all the nodes are emptied.
1246 */
1247 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1248 struct btrfs_path *path, int level, int slot)
1249 {
1250 struct btrfs_node *node;
1251 struct btrfs_buffer *parent = path->nodes[level];
1252 u32 nritems;
1253 int ret = 0;
1254 int wret;
1255
1256 node = &parent->node;
1257 nritems = btrfs_header_nritems(&node->header);
1258 if (slot != nritems -1) {
1259 memmove(node->ptrs + slot, node->ptrs + slot + 1,
1260 sizeof(struct btrfs_key_ptr) * (nritems - slot - 1));
1261 }
1262 nritems--;
1263 btrfs_set_header_nritems(&node->header, nritems);
1264 if (nritems == 0 && parent == root->node) {
1265 BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
1266 /* just turn the root into a leaf and break */
1267 btrfs_set_header_level(&root->node->node.header, 0);
1268 } else if (slot == 0) {
1269 wret = fixup_low_keys(trans, root, path, &node->ptrs[0].key,
1270 level + 1);
1271 if (wret)
1272 ret = wret;
1273 }
1274 BUG_ON(list_empty(&parent->dirty));
1275 return ret;
1276 }
1277
1278 /*
1279 * delete the item at the leaf level in path. If that empties
1280 * the leaf, remove it from the tree
1281 */
1282 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1283 struct btrfs_path *path)
1284 {
1285 int slot;
1286 struct btrfs_leaf *leaf;
1287 struct btrfs_buffer *leaf_buf;
1288 int doff;
1289 int dsize;
1290 int ret = 0;
1291 int wret;
1292 u32 nritems;
1293
1294 leaf_buf = path->nodes[0];
1295 leaf = &leaf_buf->leaf;
1296 slot = path->slots[0];
1297 doff = btrfs_item_offset(leaf->items + slot);
1298 dsize = btrfs_item_size(leaf->items + slot);
1299 nritems = btrfs_header_nritems(&leaf->header);
1300
1301 if (slot != nritems - 1) {
1302 int i;
1303 int data_end = leaf_data_end(root, leaf);
1304 memmove(btrfs_leaf_data(leaf) + data_end + dsize,
1305 btrfs_leaf_data(leaf) + data_end,
1306 doff - data_end);
1307 for (i = slot + 1; i < nritems; i++) {
1308 u32 ioff = btrfs_item_offset(leaf->items + i);
1309 btrfs_set_item_offset(leaf->items + i, ioff + dsize);
1310 }
1311 memmove(leaf->items + slot, leaf->items + slot + 1,
1312 sizeof(struct btrfs_item) *
1313 (nritems - slot - 1));
1314 }
1315 btrfs_set_header_nritems(&leaf->header, nritems - 1);
1316 nritems--;
1317 /* delete the leaf if we've emptied it */
1318 if (nritems == 0) {
1319 if (leaf_buf == root->node) {
1320 btrfs_set_header_level(&leaf->header, 0);
1321 BUG_ON(list_empty(&leaf_buf->dirty));
1322 } else {
1323 clean_tree_block(trans, root, leaf_buf);
1324 wret = del_ptr(trans, root, path, 1, path->slots[1]);
1325 if (wret)
1326 ret = wret;
1327 wret = btrfs_free_extent(trans, root,
1328 leaf_buf->blocknr, 1, 1);
1329 if (wret)
1330 ret = wret;
1331 }
1332 } else {
1333 int used = leaf_space_used(leaf, 0, nritems);
1334 if (slot == 0) {
1335 wret = fixup_low_keys(trans, root, path,
1336 &leaf->items[0].key, 1);
1337 if (wret)
1338 ret = wret;
1339 }
1340 BUG_ON(list_empty(&leaf_buf->dirty));
1341
1342 /* delete the leaf if it is mostly empty */
1343 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
1344 /* push_leaf_left fixes the path.
1345 * make sure the path still points to our leaf
1346 * for possible call to del_ptr below
1347 */
1348 slot = path->slots[1];
1349 leaf_buf->count++;
1350 wret = push_leaf_left(trans, root, path, 1);
1351 if (wret < 0)
1352 ret = wret;
1353 if (path->nodes[0] == leaf_buf &&
1354 btrfs_header_nritems(&leaf->header)) {
1355 wret = push_leaf_right(trans, root, path, 1);
1356 if (wret < 0)
1357 ret = wret;
1358 }
1359 if (btrfs_header_nritems(&leaf->header) == 0) {
1360 u64 blocknr = leaf_buf->blocknr;
1361 clean_tree_block(trans, root, leaf_buf);
1362 wret = del_ptr(trans, root, path, 1, slot);
1363 if (wret)
1364 ret = wret;
1365 btrfs_block_release(root, leaf_buf);
1366 wret = btrfs_free_extent(trans, root, blocknr,
1367 1, 1);
1368 if (wret)
1369 ret = wret;
1370 } else {
1371 btrfs_block_release(root, leaf_buf);
1372 }
1373 }
1374 }
1375 return ret;
1376 }
1377
1378 /*
1379 * walk up the tree as far as required to find the next leaf.
1380 * returns 0 if it found something or 1 if there are no greater leaves.
1381 * returns < 0 on io errors.
1382 */
1383 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
1384 {
1385 int slot;
1386 int level = 1;
1387 u64 blocknr;
1388 struct btrfs_buffer *c;
1389 struct btrfs_buffer *next = NULL;
1390
1391 while(level < BTRFS_MAX_LEVEL) {
1392 if (!path->nodes[level])
1393 return 1;
1394 slot = path->slots[level] + 1;
1395 c = path->nodes[level];
1396 if (slot >= btrfs_header_nritems(&c->node.header)) {
1397 level++;
1398 continue;
1399 }
1400 blocknr = btrfs_node_blockptr(&c->node, slot);
1401 if (next)
1402 btrfs_block_release(root, next);
1403 next = read_tree_block(root, blocknr);
1404 break;
1405 }
1406 path->slots[level] = slot;
1407 while(1) {
1408 level--;
1409 c = path->nodes[level];
1410 btrfs_block_release(root, c);
1411 path->nodes[level] = next;
1412 path->slots[level] = 0;
1413 if (!level)
1414 break;
1415 next = read_tree_block(root,
1416 btrfs_node_blockptr(&next->node, 0));
1417 }
1418 return 0;
1419 }
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