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Btrfs: support for items bigger than 1/2 the blocksize
[deliverable/linux.git] / fs / btrfs / ctree.c
1 #include <linux/module.h>
2 #include "ctree.h"
3 #include "disk-io.h"
4 #include "transaction.h"
5
6 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
7 *root, struct btrfs_path *path, int level);
8 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
9 *root, struct btrfs_key *ins_key,
10 struct btrfs_path *path, int data_size);
11 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
12 *root, struct buffer_head *dst, struct buffer_head
13 *src);
14 static int balance_node_right(struct btrfs_trans_handle *trans, struct
15 btrfs_root *root, struct buffer_head *dst_buf,
16 struct buffer_head *src_buf);
17 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
18 struct btrfs_path *path, int level, int slot);
19
20 inline void btrfs_init_path(struct btrfs_path *p)
21 {
22 memset(p, 0, sizeof(*p));
23 }
24
25 struct btrfs_path *btrfs_alloc_path(void)
26 {
27 struct btrfs_path *path;
28 path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
29 if (path)
30 btrfs_init_path(path);
31 return path;
32 }
33
34 void btrfs_free_path(struct btrfs_path *p)
35 {
36 btrfs_release_path(NULL, p);
37 kmem_cache_free(btrfs_path_cachep, p);
38 }
39
40 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
41 {
42 int i;
43 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
44 if (!p->nodes[i])
45 break;
46 btrfs_block_release(root, p->nodes[i]);
47 }
48 memset(p, 0, sizeof(*p));
49 }
50
51 static int btrfs_cow_block(struct btrfs_trans_handle *trans, struct btrfs_root
52 *root, struct buffer_head *buf, struct buffer_head
53 *parent, int parent_slot, struct buffer_head
54 **cow_ret)
55 {
56 struct buffer_head *cow;
57 struct btrfs_node *cow_node;
58
59 if (btrfs_header_generation(btrfs_buffer_header(buf)) ==
60 trans->transid) {
61 *cow_ret = buf;
62 return 0;
63 }
64 cow = btrfs_alloc_free_block(trans, root);
65 cow_node = btrfs_buffer_node(cow);
66 if (buf->b_size != root->blocksize || cow->b_size != root->blocksize)
67 WARN_ON(1);
68 memcpy(cow_node, btrfs_buffer_node(buf), root->blocksize);
69 btrfs_set_header_blocknr(&cow_node->header, cow->b_blocknr);
70 btrfs_set_header_generation(&cow_node->header, trans->transid);
71 btrfs_inc_ref(trans, root, buf);
72 if (buf == root->node) {
73 root->node = cow;
74 get_bh(cow);
75 if (buf != root->commit_root) {
76 btrfs_free_extent(trans, root, buf->b_blocknr, 1, 1);
77 }
78 btrfs_block_release(root, buf);
79 } else {
80 btrfs_set_node_blockptr(btrfs_buffer_node(parent), parent_slot,
81 cow->b_blocknr);
82 btrfs_mark_buffer_dirty(parent);
83 btrfs_free_extent(trans, root, buf->b_blocknr, 1, 1);
84 }
85 btrfs_block_release(root, buf);
86 mark_buffer_dirty(cow);
87 *cow_ret = cow;
88 return 0;
89 }
90
91 /*
92 * The leaf data grows from end-to-front in the node.
93 * this returns the address of the start of the last item,
94 * which is the stop of the leaf data stack
95 */
96 static inline unsigned int leaf_data_end(struct btrfs_root *root,
97 struct btrfs_leaf *leaf)
98 {
99 u32 nr = btrfs_header_nritems(&leaf->header);
100 if (nr == 0)
101 return BTRFS_LEAF_DATA_SIZE(root);
102 return btrfs_item_offset(leaf->items + nr - 1);
103 }
104
105 /*
106 * compare two keys in a memcmp fashion
107 */
108 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
109 {
110 struct btrfs_key k1;
111
112 btrfs_disk_key_to_cpu(&k1, disk);
113
114 if (k1.objectid > k2->objectid)
115 return 1;
116 if (k1.objectid < k2->objectid)
117 return -1;
118 if (k1.offset > k2->offset)
119 return 1;
120 if (k1.offset < k2->offset)
121 return -1;
122 if (k1.flags > k2->flags)
123 return 1;
124 if (k1.flags < k2->flags)
125 return -1;
126 return 0;
127 }
128
129 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
130 int level)
131 {
132 int i;
133 struct btrfs_node *parent = NULL;
134 struct btrfs_node *node = btrfs_buffer_node(path->nodes[level]);
135 int parent_slot;
136 u32 nritems = btrfs_header_nritems(&node->header);
137
138 if (path->nodes[level + 1])
139 parent = btrfs_buffer_node(path->nodes[level + 1]);
140 parent_slot = path->slots[level + 1];
141 BUG_ON(nritems == 0);
142 if (parent) {
143 struct btrfs_disk_key *parent_key;
144 parent_key = &parent->ptrs[parent_slot].key;
145 BUG_ON(memcmp(parent_key, &node->ptrs[0].key,
146 sizeof(struct btrfs_disk_key)));
147 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
148 btrfs_header_blocknr(&node->header));
149 }
150 BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
151 for (i = 0; nritems > 1 && i < nritems - 2; i++) {
152 struct btrfs_key cpukey;
153 btrfs_disk_key_to_cpu(&cpukey, &node->ptrs[i + 1].key);
154 BUG_ON(comp_keys(&node->ptrs[i].key, &cpukey) >= 0);
155 }
156 return 0;
157 }
158
159 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
160 int level)
161 {
162 int i;
163 struct btrfs_leaf *leaf = btrfs_buffer_leaf(path->nodes[level]);
164 struct btrfs_node *parent = NULL;
165 int parent_slot;
166 u32 nritems = btrfs_header_nritems(&leaf->header);
167
168 if (path->nodes[level + 1])
169 parent = btrfs_buffer_node(path->nodes[level + 1]);
170 parent_slot = path->slots[level + 1];
171 BUG_ON(btrfs_leaf_free_space(root, leaf) < 0);
172
173 if (nritems == 0)
174 return 0;
175
176 if (parent) {
177 struct btrfs_disk_key *parent_key;
178 parent_key = &parent->ptrs[parent_slot].key;
179 BUG_ON(memcmp(parent_key, &leaf->items[0].key,
180 sizeof(struct btrfs_disk_key)));
181 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
182 btrfs_header_blocknr(&leaf->header));
183 }
184 for (i = 0; nritems > 1 && i < nritems - 2; i++) {
185 struct btrfs_key cpukey;
186 btrfs_disk_key_to_cpu(&cpukey, &leaf->items[i + 1].key);
187 BUG_ON(comp_keys(&leaf->items[i].key,
188 &cpukey) >= 0);
189 BUG_ON(btrfs_item_offset(leaf->items + i) !=
190 btrfs_item_end(leaf->items + i + 1));
191 if (i == 0) {
192 BUG_ON(btrfs_item_offset(leaf->items + i) +
193 btrfs_item_size(leaf->items + i) !=
194 BTRFS_LEAF_DATA_SIZE(root));
195 }
196 }
197 return 0;
198 }
199
200 static int check_block(struct btrfs_root *root, struct btrfs_path *path,
201 int level)
202 {
203 if (level == 0)
204 return check_leaf(root, path, level);
205 return check_node(root, path, level);
206 }
207
208 /*
209 * search for key in the array p. items p are item_size apart
210 * and there are 'max' items in p
211 * the slot in the array is returned via slot, and it points to
212 * the place where you would insert key if it is not found in
213 * the array.
214 *
215 * slot may point to max if the key is bigger than all of the keys
216 */
217 static int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
218 int max, int *slot)
219 {
220 int low = 0;
221 int high = max;
222 int mid;
223 int ret;
224 struct btrfs_disk_key *tmp;
225
226 while(low < high) {
227 mid = (low + high) / 2;
228 tmp = (struct btrfs_disk_key *)(p + mid * item_size);
229 ret = comp_keys(tmp, key);
230
231 if (ret < 0)
232 low = mid + 1;
233 else if (ret > 0)
234 high = mid;
235 else {
236 *slot = mid;
237 return 0;
238 }
239 }
240 *slot = low;
241 return 1;
242 }
243
244 /*
245 * simple bin_search frontend that does the right thing for
246 * leaves vs nodes
247 */
248 static int bin_search(struct btrfs_node *c, struct btrfs_key *key, int *slot)
249 {
250 if (btrfs_is_leaf(c)) {
251 struct btrfs_leaf *l = (struct btrfs_leaf *)c;
252 return generic_bin_search((void *)l->items,
253 sizeof(struct btrfs_item),
254 key, btrfs_header_nritems(&c->header),
255 slot);
256 } else {
257 return generic_bin_search((void *)c->ptrs,
258 sizeof(struct btrfs_key_ptr),
259 key, btrfs_header_nritems(&c->header),
260 slot);
261 }
262 return -1;
263 }
264
265 static struct buffer_head *read_node_slot(struct btrfs_root *root,
266 struct buffer_head *parent_buf,
267 int slot)
268 {
269 struct btrfs_node *node = btrfs_buffer_node(parent_buf);
270 if (slot < 0)
271 return NULL;
272 if (slot >= btrfs_header_nritems(&node->header))
273 return NULL;
274 return read_tree_block(root, btrfs_node_blockptr(node, slot));
275 }
276
277 static int balance_level(struct btrfs_trans_handle *trans, struct btrfs_root
278 *root, struct btrfs_path *path, int level)
279 {
280 struct buffer_head *right_buf;
281 struct buffer_head *mid_buf;
282 struct buffer_head *left_buf;
283 struct buffer_head *parent_buf = NULL;
284 struct btrfs_node *right = NULL;
285 struct btrfs_node *mid;
286 struct btrfs_node *left = NULL;
287 struct btrfs_node *parent = NULL;
288 int ret = 0;
289 int wret;
290 int pslot;
291 int orig_slot = path->slots[level];
292 u64 orig_ptr;
293
294 if (level == 0)
295 return 0;
296
297 mid_buf = path->nodes[level];
298 mid = btrfs_buffer_node(mid_buf);
299 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
300
301 if (level < BTRFS_MAX_LEVEL - 1)
302 parent_buf = path->nodes[level + 1];
303 pslot = path->slots[level + 1];
304
305 /*
306 * deal with the case where there is only one pointer in the root
307 * by promoting the node below to a root
308 */
309 if (!parent_buf) {
310 struct buffer_head *child;
311 u64 blocknr = mid_buf->b_blocknr;
312
313 if (btrfs_header_nritems(&mid->header) != 1)
314 return 0;
315
316 /* promote the child to a root */
317 child = read_node_slot(root, mid_buf, 0);
318 BUG_ON(!child);
319 root->node = child;
320 path->nodes[level] = NULL;
321 clean_tree_block(trans, root, mid_buf);
322 wait_on_buffer(mid_buf);
323 /* once for the path */
324 btrfs_block_release(root, mid_buf);
325 /* once for the root ptr */
326 btrfs_block_release(root, mid_buf);
327 return btrfs_free_extent(trans, root, blocknr, 1, 1);
328 }
329 parent = btrfs_buffer_node(parent_buf);
330
331 if (btrfs_header_nritems(&mid->header) >
332 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
333 return 0;
334
335 left_buf = read_node_slot(root, parent_buf, pslot - 1);
336 right_buf = read_node_slot(root, parent_buf, pslot + 1);
337
338 /* first, try to make some room in the middle buffer */
339 if (left_buf) {
340 btrfs_cow_block(trans, root, left_buf, parent_buf, pslot - 1,
341 &left_buf);
342 left = btrfs_buffer_node(left_buf);
343 orig_slot += btrfs_header_nritems(&left->header);
344 wret = push_node_left(trans, root, left_buf, mid_buf);
345 if (wret < 0)
346 ret = wret;
347 }
348
349 /*
350 * then try to empty the right most buffer into the middle
351 */
352 if (right_buf) {
353 btrfs_cow_block(trans, root, right_buf, parent_buf, pslot + 1,
354 &right_buf);
355 right = btrfs_buffer_node(right_buf);
356 wret = push_node_left(trans, root, mid_buf, right_buf);
357 if (wret < 0)
358 ret = wret;
359 if (btrfs_header_nritems(&right->header) == 0) {
360 u64 blocknr = right_buf->b_blocknr;
361 clean_tree_block(trans, root, right_buf);
362 wait_on_buffer(right_buf);
363 btrfs_block_release(root, right_buf);
364 right_buf = NULL;
365 right = NULL;
366 wret = del_ptr(trans, root, path, level + 1, pslot +
367 1);
368 if (wret)
369 ret = wret;
370 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
371 if (wret)
372 ret = wret;
373 } else {
374 btrfs_memcpy(root, parent,
375 &parent->ptrs[pslot + 1].key,
376 &right->ptrs[0].key,
377 sizeof(struct btrfs_disk_key));
378 btrfs_mark_buffer_dirty(parent_buf);
379 }
380 }
381 if (btrfs_header_nritems(&mid->header) == 1) {
382 /*
383 * we're not allowed to leave a node with one item in the
384 * tree during a delete. A deletion from lower in the tree
385 * could try to delete the only pointer in this node.
386 * So, pull some keys from the left.
387 * There has to be a left pointer at this point because
388 * otherwise we would have pulled some pointers from the
389 * right
390 */
391 BUG_ON(!left_buf);
392 wret = balance_node_right(trans, root, mid_buf, left_buf);
393 if (wret < 0)
394 ret = wret;
395 BUG_ON(wret == 1);
396 }
397 if (btrfs_header_nritems(&mid->header) == 0) {
398 /* we've managed to empty the middle node, drop it */
399 u64 blocknr = mid_buf->b_blocknr;
400 clean_tree_block(trans, root, mid_buf);
401 wait_on_buffer(mid_buf);
402 btrfs_block_release(root, mid_buf);
403 mid_buf = NULL;
404 mid = NULL;
405 wret = del_ptr(trans, root, path, level + 1, pslot);
406 if (wret)
407 ret = wret;
408 wret = btrfs_free_extent(trans, root, blocknr, 1, 1);
409 if (wret)
410 ret = wret;
411 } else {
412 /* update the parent key to reflect our changes */
413 btrfs_memcpy(root, parent,
414 &parent->ptrs[pslot].key, &mid->ptrs[0].key,
415 sizeof(struct btrfs_disk_key));
416 btrfs_mark_buffer_dirty(parent_buf);
417 }
418
419 /* update the path */
420 if (left_buf) {
421 if (btrfs_header_nritems(&left->header) > orig_slot) {
422 get_bh(left_buf);
423 path->nodes[level] = left_buf;
424 path->slots[level + 1] -= 1;
425 path->slots[level] = orig_slot;
426 if (mid_buf)
427 btrfs_block_release(root, mid_buf);
428 } else {
429 orig_slot -= btrfs_header_nritems(&left->header);
430 path->slots[level] = orig_slot;
431 }
432 }
433 /* double check we haven't messed things up */
434 check_block(root, path, level);
435 if (orig_ptr !=
436 btrfs_node_blockptr(btrfs_buffer_node(path->nodes[level]),
437 path->slots[level]))
438 BUG();
439
440 if (right_buf)
441 btrfs_block_release(root, right_buf);
442 if (left_buf)
443 btrfs_block_release(root, left_buf);
444 return ret;
445 }
446
447 /*
448 * look for key in the tree. path is filled in with nodes along the way
449 * if key is found, we return zero and you can find the item in the leaf
450 * level of the path (level 0)
451 *
452 * If the key isn't found, the path points to the slot where it should
453 * be inserted, and 1 is returned. If there are other errors during the
454 * search a negative error number is returned.
455 *
456 * if ins_len > 0, nodes and leaves will be split as we walk down the
457 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
458 * possible)
459 */
460 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
461 *root, struct btrfs_key *key, struct btrfs_path *p, int
462 ins_len, int cow)
463 {
464 struct buffer_head *b;
465 struct buffer_head *cow_buf;
466 struct btrfs_node *c;
467 int slot;
468 int ret;
469 int level;
470
471 WARN_ON(p->nodes[0] != NULL);
472 WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
473 again:
474 b = root->node;
475 get_bh(b);
476 while (b) {
477 c = btrfs_buffer_node(b);
478 level = btrfs_header_level(&c->header);
479 if (cow) {
480 int wret;
481 wret = btrfs_cow_block(trans, root, b,
482 p->nodes[level + 1],
483 p->slots[level + 1],
484 &cow_buf);
485 b = cow_buf;
486 c = btrfs_buffer_node(b);
487 }
488 BUG_ON(!cow && ins_len);
489 if (level != btrfs_header_level(&c->header))
490 WARN_ON(1);
491 level = btrfs_header_level(&c->header);
492 p->nodes[level] = b;
493 ret = check_block(root, p, level);
494 if (ret)
495 return -1;
496 ret = bin_search(c, key, &slot);
497 if (!btrfs_is_leaf(c)) {
498 if (ret && slot > 0)
499 slot -= 1;
500 p->slots[level] = slot;
501 if (ins_len > 0 && btrfs_header_nritems(&c->header) >=
502 BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
503 int sret = split_node(trans, root, p, level);
504 BUG_ON(sret > 0);
505 if (sret)
506 return sret;
507 b = p->nodes[level];
508 c = btrfs_buffer_node(b);
509 slot = p->slots[level];
510 } else if (ins_len < 0) {
511 int sret = balance_level(trans, root, p,
512 level);
513 if (sret)
514 return sret;
515 b = p->nodes[level];
516 if (!b)
517 goto again;
518 c = btrfs_buffer_node(b);
519 slot = p->slots[level];
520 BUG_ON(btrfs_header_nritems(&c->header) == 1);
521 }
522 b = read_tree_block(root, btrfs_node_blockptr(c, slot));
523 } else {
524 struct btrfs_leaf *l = (struct btrfs_leaf *)c;
525 p->slots[level] = slot;
526 if (ins_len > 0 && btrfs_leaf_free_space(root, l) <
527 sizeof(struct btrfs_item) + ins_len) {
528 int sret = split_leaf(trans, root, key,
529 p, ins_len);
530 BUG_ON(sret > 0);
531 if (sret)
532 return sret;
533 }
534 return ret;
535 }
536 }
537 return 1;
538 }
539
540 /*
541 * adjust the pointers going up the tree, starting at level
542 * making sure the right key of each node is points to 'key'.
543 * This is used after shifting pointers to the left, so it stops
544 * fixing up pointers when a given leaf/node is not in slot 0 of the
545 * higher levels
546 *
547 * If this fails to write a tree block, it returns -1, but continues
548 * fixing up the blocks in ram so the tree is consistent.
549 */
550 static int fixup_low_keys(struct btrfs_trans_handle *trans, struct btrfs_root
551 *root, struct btrfs_path *path, struct btrfs_disk_key
552 *key, int level)
553 {
554 int i;
555 int ret = 0;
556 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
557 struct btrfs_node *t;
558 int tslot = path->slots[i];
559 if (!path->nodes[i])
560 break;
561 t = btrfs_buffer_node(path->nodes[i]);
562 btrfs_memcpy(root, t, &t->ptrs[tslot].key, key, sizeof(*key));
563 btrfs_mark_buffer_dirty(path->nodes[i]);
564 if (tslot != 0)
565 break;
566 }
567 return ret;
568 }
569
570 /*
571 * try to push data from one node into the next node left in the
572 * tree.
573 *
574 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
575 * error, and > 0 if there was no room in the left hand block.
576 */
577 static int push_node_left(struct btrfs_trans_handle *trans, struct btrfs_root
578 *root, struct buffer_head *dst_buf, struct
579 buffer_head *src_buf)
580 {
581 struct btrfs_node *src = btrfs_buffer_node(src_buf);
582 struct btrfs_node *dst = btrfs_buffer_node(dst_buf);
583 int push_items = 0;
584 int src_nritems;
585 int dst_nritems;
586 int ret = 0;
587
588 src_nritems = btrfs_header_nritems(&src->header);
589 dst_nritems = btrfs_header_nritems(&dst->header);
590 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
591 if (push_items <= 0) {
592 return 1;
593 }
594
595 if (src_nritems < push_items)
596 push_items = src_nritems;
597
598 btrfs_memcpy(root, dst, dst->ptrs + dst_nritems, src->ptrs,
599 push_items * sizeof(struct btrfs_key_ptr));
600 if (push_items < src_nritems) {
601 btrfs_memmove(root, src, src->ptrs, src->ptrs + push_items,
602 (src_nritems - push_items) *
603 sizeof(struct btrfs_key_ptr));
604 }
605 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
606 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
607 btrfs_mark_buffer_dirty(src_buf);
608 btrfs_mark_buffer_dirty(dst_buf);
609 return ret;
610 }
611
612 /*
613 * try to push data from one node into the next node right in the
614 * tree.
615 *
616 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
617 * error, and > 0 if there was no room in the right hand block.
618 *
619 * this will only push up to 1/2 the contents of the left node over
620 */
621 static int balance_node_right(struct btrfs_trans_handle *trans, struct
622 btrfs_root *root, struct buffer_head *dst_buf,
623 struct buffer_head *src_buf)
624 {
625 struct btrfs_node *src = btrfs_buffer_node(src_buf);
626 struct btrfs_node *dst = btrfs_buffer_node(dst_buf);
627 int push_items = 0;
628 int max_push;
629 int src_nritems;
630 int dst_nritems;
631 int ret = 0;
632
633 src_nritems = btrfs_header_nritems(&src->header);
634 dst_nritems = btrfs_header_nritems(&dst->header);
635 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
636 if (push_items <= 0) {
637 return 1;
638 }
639
640 max_push = src_nritems / 2 + 1;
641 /* don't try to empty the node */
642 if (max_push > src_nritems)
643 return 1;
644 if (max_push < push_items)
645 push_items = max_push;
646
647 btrfs_memmove(root, dst, dst->ptrs + push_items, dst->ptrs,
648 dst_nritems * sizeof(struct btrfs_key_ptr));
649
650 btrfs_memcpy(root, dst, dst->ptrs,
651 src->ptrs + src_nritems - push_items,
652 push_items * sizeof(struct btrfs_key_ptr));
653
654 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
655 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
656
657 btrfs_mark_buffer_dirty(src_buf);
658 btrfs_mark_buffer_dirty(dst_buf);
659 return ret;
660 }
661
662 /*
663 * helper function to insert a new root level in the tree.
664 * A new node is allocated, and a single item is inserted to
665 * point to the existing root
666 *
667 * returns zero on success or < 0 on failure.
668 */
669 static int insert_new_root(struct btrfs_trans_handle *trans, struct btrfs_root
670 *root, struct btrfs_path *path, int level)
671 {
672 struct buffer_head *t;
673 struct btrfs_node *lower;
674 struct btrfs_node *c;
675 struct btrfs_disk_key *lower_key;
676
677 BUG_ON(path->nodes[level]);
678 BUG_ON(path->nodes[level-1] != root->node);
679
680 t = btrfs_alloc_free_block(trans, root);
681 c = btrfs_buffer_node(t);
682 memset(c, 0, root->blocksize);
683 btrfs_set_header_nritems(&c->header, 1);
684 btrfs_set_header_level(&c->header, level);
685 btrfs_set_header_blocknr(&c->header, t->b_blocknr);
686 btrfs_set_header_generation(&c->header, trans->transid);
687 btrfs_set_header_parentid(&c->header,
688 btrfs_header_parentid(btrfs_buffer_header(root->node)));
689 lower = btrfs_buffer_node(path->nodes[level-1]);
690 if (btrfs_is_leaf(lower))
691 lower_key = &((struct btrfs_leaf *)lower)->items[0].key;
692 else
693 lower_key = &lower->ptrs[0].key;
694 btrfs_memcpy(root, c, &c->ptrs[0].key, lower_key,
695 sizeof(struct btrfs_disk_key));
696 btrfs_set_node_blockptr(c, 0, path->nodes[level - 1]->b_blocknr);
697
698 btrfs_mark_buffer_dirty(t);
699
700 /* the super has an extra ref to root->node */
701 btrfs_block_release(root, root->node);
702 root->node = t;
703 get_bh(t);
704 path->nodes[level] = t;
705 path->slots[level] = 0;
706 return 0;
707 }
708
709 /*
710 * worker function to insert a single pointer in a node.
711 * the node should have enough room for the pointer already
712 *
713 * slot and level indicate where you want the key to go, and
714 * blocknr is the block the key points to.
715 *
716 * returns zero on success and < 0 on any error
717 */
718 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
719 *root, struct btrfs_path *path, struct btrfs_disk_key
720 *key, u64 blocknr, int slot, int level)
721 {
722 struct btrfs_node *lower;
723 int nritems;
724
725 BUG_ON(!path->nodes[level]);
726 lower = btrfs_buffer_node(path->nodes[level]);
727 nritems = btrfs_header_nritems(&lower->header);
728 if (slot > nritems)
729 BUG();
730 if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
731 BUG();
732 if (slot != nritems) {
733 btrfs_memmove(root, lower, lower->ptrs + slot + 1,
734 lower->ptrs + slot,
735 (nritems - slot) * sizeof(struct btrfs_key_ptr));
736 }
737 btrfs_memcpy(root, lower, &lower->ptrs[slot].key,
738 key, sizeof(struct btrfs_disk_key));
739 btrfs_set_node_blockptr(lower, slot, blocknr);
740 btrfs_set_header_nritems(&lower->header, nritems + 1);
741 btrfs_mark_buffer_dirty(path->nodes[level]);
742 return 0;
743 }
744
745 /*
746 * split the node at the specified level in path in two.
747 * The path is corrected to point to the appropriate node after the split
748 *
749 * Before splitting this tries to make some room in the node by pushing
750 * left and right, if either one works, it returns right away.
751 *
752 * returns 0 on success and < 0 on failure
753 */
754 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
755 *root, struct btrfs_path *path, int level)
756 {
757 struct buffer_head *t;
758 struct btrfs_node *c;
759 struct buffer_head *split_buffer;
760 struct btrfs_node *split;
761 int mid;
762 int ret;
763 int wret;
764 u32 c_nritems;
765
766 t = path->nodes[level];
767 c = btrfs_buffer_node(t);
768 if (t == root->node) {
769 /* trying to split the root, lets make a new one */
770 ret = insert_new_root(trans, root, path, level + 1);
771 if (ret)
772 return ret;
773 }
774 c_nritems = btrfs_header_nritems(&c->header);
775 split_buffer = btrfs_alloc_free_block(trans, root);
776 split = btrfs_buffer_node(split_buffer);
777 btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
778 btrfs_set_header_level(&split->header, btrfs_header_level(&c->header));
779 btrfs_set_header_blocknr(&split->header, split_buffer->b_blocknr);
780 btrfs_set_header_generation(&split->header, trans->transid);
781 btrfs_set_header_parentid(&split->header,
782 btrfs_header_parentid(btrfs_buffer_header(root->node)));
783 mid = (c_nritems + 1) / 2;
784 btrfs_memcpy(root, split, split->ptrs, c->ptrs + mid,
785 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
786 btrfs_set_header_nritems(&split->header, c_nritems - mid);
787 btrfs_set_header_nritems(&c->header, mid);
788 ret = 0;
789
790 btrfs_mark_buffer_dirty(t);
791 btrfs_mark_buffer_dirty(split_buffer);
792 wret = insert_ptr(trans, root, path, &split->ptrs[0].key,
793 split_buffer->b_blocknr, path->slots[level + 1] + 1,
794 level + 1);
795 if (wret)
796 ret = wret;
797
798 if (path->slots[level] >= mid) {
799 path->slots[level] -= mid;
800 btrfs_block_release(root, t);
801 path->nodes[level] = split_buffer;
802 path->slots[level + 1] += 1;
803 } else {
804 btrfs_block_release(root, split_buffer);
805 }
806 return ret;
807 }
808
809 /*
810 * how many bytes are required to store the items in a leaf. start
811 * and nr indicate which items in the leaf to check. This totals up the
812 * space used both by the item structs and the item data
813 */
814 static int leaf_space_used(struct btrfs_leaf *l, int start, int nr)
815 {
816 int data_len;
817 int nritems = btrfs_header_nritems(&l->header);
818 int end = min(nritems, start + nr) - 1;
819
820 if (!nr)
821 return 0;
822 data_len = btrfs_item_end(l->items + start);
823 data_len = data_len - btrfs_item_offset(l->items + end);
824 data_len += sizeof(struct btrfs_item) * nr;
825 WARN_ON(data_len < 0);
826 return data_len;
827 }
828
829 /*
830 * The space between the end of the leaf items and
831 * the start of the leaf data. IOW, how much room
832 * the leaf has left for both items and data
833 */
834 int btrfs_leaf_free_space(struct btrfs_root *root, struct btrfs_leaf *leaf)
835 {
836 int nritems = btrfs_header_nritems(&leaf->header);
837 return BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
838 }
839
840 /*
841 * push some data in the path leaf to the right, trying to free up at
842 * least data_size bytes. returns zero if the push worked, nonzero otherwise
843 *
844 * returns 1 if the push failed because the other node didn't have enough
845 * room, 0 if everything worked out and < 0 if there were major errors.
846 */
847 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
848 *root, struct btrfs_path *path, int data_size)
849 {
850 struct buffer_head *left_buf = path->nodes[0];
851 struct btrfs_leaf *left = btrfs_buffer_leaf(left_buf);
852 struct btrfs_leaf *right;
853 struct buffer_head *right_buf;
854 struct buffer_head *upper;
855 struct btrfs_node *upper_node;
856 int slot;
857 int i;
858 int free_space;
859 int push_space = 0;
860 int push_items = 0;
861 struct btrfs_item *item;
862 u32 left_nritems;
863 u32 right_nritems;
864
865 slot = path->slots[1];
866 if (!path->nodes[1]) {
867 return 1;
868 }
869 upper = path->nodes[1];
870 upper_node = btrfs_buffer_node(upper);
871 if (slot >= btrfs_header_nritems(&upper_node->header) - 1) {
872 return 1;
873 }
874 right_buf = read_tree_block(root,
875 btrfs_node_blockptr(btrfs_buffer_node(upper), slot + 1));
876 right = btrfs_buffer_leaf(right_buf);
877 free_space = btrfs_leaf_free_space(root, right);
878 if (free_space < data_size + sizeof(struct btrfs_item)) {
879 btrfs_block_release(root, right_buf);
880 return 1;
881 }
882 /* cow and double check */
883 btrfs_cow_block(trans, root, right_buf, upper, slot + 1, &right_buf);
884 right = btrfs_buffer_leaf(right_buf);
885 free_space = btrfs_leaf_free_space(root, right);
886 if (free_space < data_size + sizeof(struct btrfs_item)) {
887 btrfs_block_release(root, right_buf);
888 return 1;
889 }
890
891 left_nritems = btrfs_header_nritems(&left->header);
892 for (i = left_nritems - 1; i >= 0; i--) {
893 item = left->items + i;
894 if (path->slots[0] == i)
895 push_space += data_size + sizeof(*item);
896 if (btrfs_item_size(item) + sizeof(*item) + push_space >
897 free_space)
898 break;
899 push_items++;
900 push_space += btrfs_item_size(item) + sizeof(*item);
901 }
902 if (push_items == 0) {
903 btrfs_block_release(root, right_buf);
904 return 1;
905 }
906 right_nritems = btrfs_header_nritems(&right->header);
907 /* push left to right */
908 push_space = btrfs_item_end(left->items + left_nritems - push_items);
909 push_space -= leaf_data_end(root, left);
910 /* make room in the right data area */
911 btrfs_memmove(root, right, btrfs_leaf_data(right) +
912 leaf_data_end(root, right) - push_space,
913 btrfs_leaf_data(right) +
914 leaf_data_end(root, right), BTRFS_LEAF_DATA_SIZE(root) -
915 leaf_data_end(root, right));
916 /* copy from the left data area */
917 btrfs_memcpy(root, right, btrfs_leaf_data(right) +
918 BTRFS_LEAF_DATA_SIZE(root) - push_space,
919 btrfs_leaf_data(left) + leaf_data_end(root, left),
920 push_space);
921 btrfs_memmove(root, right, right->items + push_items, right->items,
922 right_nritems * sizeof(struct btrfs_item));
923 /* copy the items from left to right */
924 btrfs_memcpy(root, right, right->items, left->items +
925 left_nritems - push_items,
926 push_items * sizeof(struct btrfs_item));
927
928 /* update the item pointers */
929 right_nritems += push_items;
930 btrfs_set_header_nritems(&right->header, right_nritems);
931 push_space = BTRFS_LEAF_DATA_SIZE(root);
932 for (i = 0; i < right_nritems; i++) {
933 btrfs_set_item_offset(right->items + i, push_space -
934 btrfs_item_size(right->items + i));
935 push_space = btrfs_item_offset(right->items + i);
936 }
937 left_nritems -= push_items;
938 btrfs_set_header_nritems(&left->header, left_nritems);
939
940 btrfs_mark_buffer_dirty(left_buf);
941 btrfs_mark_buffer_dirty(right_buf);
942 btrfs_memcpy(root, upper_node, &upper_node->ptrs[slot + 1].key,
943 &right->items[0].key, sizeof(struct btrfs_disk_key));
944 btrfs_mark_buffer_dirty(upper);
945
946 /* then fixup the leaf pointer in the path */
947 if (path->slots[0] >= left_nritems) {
948 path->slots[0] -= left_nritems;
949 btrfs_block_release(root, path->nodes[0]);
950 path->nodes[0] = right_buf;
951 path->slots[1] += 1;
952 } else {
953 btrfs_block_release(root, right_buf);
954 }
955 return 0;
956 }
957 /*
958 * push some data in the path leaf to the left, trying to free up at
959 * least data_size bytes. returns zero if the push worked, nonzero otherwise
960 */
961 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
962 *root, struct btrfs_path *path, int data_size)
963 {
964 struct buffer_head *right_buf = path->nodes[0];
965 struct btrfs_leaf *right = btrfs_buffer_leaf(right_buf);
966 struct buffer_head *t;
967 struct btrfs_leaf *left;
968 int slot;
969 int i;
970 int free_space;
971 int push_space = 0;
972 int push_items = 0;
973 struct btrfs_item *item;
974 u32 old_left_nritems;
975 int ret = 0;
976 int wret;
977
978 slot = path->slots[1];
979 if (slot == 0) {
980 return 1;
981 }
982 if (!path->nodes[1]) {
983 return 1;
984 }
985 t = read_tree_block(root,
986 btrfs_node_blockptr(btrfs_buffer_node(path->nodes[1]), slot - 1));
987 left = btrfs_buffer_leaf(t);
988 free_space = btrfs_leaf_free_space(root, left);
989 if (free_space < data_size + sizeof(struct btrfs_item)) {
990 btrfs_block_release(root, t);
991 return 1;
992 }
993
994 /* cow and double check */
995 btrfs_cow_block(trans, root, t, path->nodes[1], slot - 1, &t);
996 left = btrfs_buffer_leaf(t);
997 free_space = btrfs_leaf_free_space(root, left);
998 if (free_space < data_size + sizeof(struct btrfs_item)) {
999 btrfs_block_release(root, t);
1000 return 1;
1001 }
1002
1003 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1004 item = right->items + i;
1005 if (path->slots[0] == i)
1006 push_space += data_size + sizeof(*item);
1007 if (btrfs_item_size(item) + sizeof(*item) + push_space >
1008 free_space)
1009 break;
1010 push_items++;
1011 push_space += btrfs_item_size(item) + sizeof(*item);
1012 }
1013 if (push_items == 0) {
1014 btrfs_block_release(root, t);
1015 return 1;
1016 }
1017 /* push data from right to left */
1018 btrfs_memcpy(root, left, left->items +
1019 btrfs_header_nritems(&left->header),
1020 right->items, push_items * sizeof(struct btrfs_item));
1021 push_space = BTRFS_LEAF_DATA_SIZE(root) -
1022 btrfs_item_offset(right->items + push_items -1);
1023 btrfs_memcpy(root, left, btrfs_leaf_data(left) +
1024 leaf_data_end(root, left) - push_space,
1025 btrfs_leaf_data(right) +
1026 btrfs_item_offset(right->items + push_items - 1),
1027 push_space);
1028 old_left_nritems = btrfs_header_nritems(&left->header);
1029 BUG_ON(old_left_nritems < 0);
1030
1031 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1032 u32 ioff = btrfs_item_offset(left->items + i);
1033 btrfs_set_item_offset(left->items + i, ioff -
1034 (BTRFS_LEAF_DATA_SIZE(root) -
1035 btrfs_item_offset(left->items +
1036 old_left_nritems - 1)));
1037 }
1038 btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
1039
1040 /* fixup right node */
1041 push_space = btrfs_item_offset(right->items + push_items - 1) -
1042 leaf_data_end(root, right);
1043 btrfs_memmove(root, right, btrfs_leaf_data(right) +
1044 BTRFS_LEAF_DATA_SIZE(root) - push_space,
1045 btrfs_leaf_data(right) +
1046 leaf_data_end(root, right), push_space);
1047 btrfs_memmove(root, right, right->items, right->items + push_items,
1048 (btrfs_header_nritems(&right->header) - push_items) *
1049 sizeof(struct btrfs_item));
1050 btrfs_set_header_nritems(&right->header,
1051 btrfs_header_nritems(&right->header) -
1052 push_items);
1053 push_space = BTRFS_LEAF_DATA_SIZE(root);
1054
1055 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1056 btrfs_set_item_offset(right->items + i, push_space -
1057 btrfs_item_size(right->items + i));
1058 push_space = btrfs_item_offset(right->items + i);
1059 }
1060
1061 btrfs_mark_buffer_dirty(t);
1062 btrfs_mark_buffer_dirty(right_buf);
1063
1064 wret = fixup_low_keys(trans, root, path, &right->items[0].key, 1);
1065 if (wret)
1066 ret = wret;
1067
1068 /* then fixup the leaf pointer in the path */
1069 if (path->slots[0] < push_items) {
1070 path->slots[0] += old_left_nritems;
1071 btrfs_block_release(root, path->nodes[0]);
1072 path->nodes[0] = t;
1073 path->slots[1] -= 1;
1074 } else {
1075 btrfs_block_release(root, t);
1076 path->slots[0] -= push_items;
1077 }
1078 BUG_ON(path->slots[0] < 0);
1079 return ret;
1080 }
1081
1082 /*
1083 * split the path's leaf in two, making sure there is at least data_size
1084 * available for the resulting leaf level of the path.
1085 *
1086 * returns 0 if all went well and < 0 on failure.
1087 */
1088 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1089 *root, struct btrfs_key *ins_key,
1090 struct btrfs_path *path, int data_size)
1091 {
1092 struct buffer_head *l_buf;
1093 struct btrfs_leaf *l;
1094 u32 nritems;
1095 int mid;
1096 int slot;
1097 struct btrfs_leaf *right;
1098 struct buffer_head *right_buffer;
1099 int space_needed = data_size + sizeof(struct btrfs_item);
1100 int data_copy_size;
1101 int rt_data_off;
1102 int i;
1103 int ret = 0;
1104 int wret;
1105 int double_split = 0;
1106 struct btrfs_disk_key disk_key;
1107
1108 /* first try to make some room by pushing left and right */
1109 wret = push_leaf_left(trans, root, path, data_size);
1110 if (wret < 0)
1111 return wret;
1112 if (wret) {
1113 wret = push_leaf_right(trans, root, path, data_size);
1114 if (wret < 0)
1115 return wret;
1116 }
1117 l_buf = path->nodes[0];
1118 l = btrfs_buffer_leaf(l_buf);
1119
1120 /* did the pushes work? */
1121 if (btrfs_leaf_free_space(root, l) >=
1122 sizeof(struct btrfs_item) + data_size)
1123 return 0;
1124
1125 if (!path->nodes[1]) {
1126 ret = insert_new_root(trans, root, path, 1);
1127 if (ret)
1128 return ret;
1129 }
1130 slot = path->slots[0];
1131 nritems = btrfs_header_nritems(&l->header);
1132 mid = (nritems + 1)/ 2;
1133 right_buffer = btrfs_alloc_free_block(trans, root);
1134 BUG_ON(!right_buffer);
1135 right = btrfs_buffer_leaf(right_buffer);
1136 memset(&right->header, 0, sizeof(right->header));
1137 btrfs_set_header_blocknr(&right->header, right_buffer->b_blocknr);
1138 btrfs_set_header_generation(&right->header, trans->transid);
1139 btrfs_set_header_level(&right->header, 0);
1140 btrfs_set_header_parentid(&right->header,
1141 btrfs_header_parentid(btrfs_buffer_header(root->node)));
1142 if (mid <= slot) {
1143 if (nritems == 1 ||
1144 leaf_space_used(l, mid, nritems - mid) + space_needed >
1145 BTRFS_LEAF_DATA_SIZE(root)) {
1146 if (slot >= nritems) {
1147 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1148 btrfs_set_header_nritems(&right->header, 0);
1149 wret = insert_ptr(trans, root, path,
1150 &disk_key,
1151 right_buffer->b_blocknr,
1152 path->slots[1] + 1, 1);
1153 if (wret)
1154 ret = wret;
1155 btrfs_block_release(root, path->nodes[0]);
1156 path->nodes[0] = right_buffer;
1157 path->slots[0] = 0;
1158 path->slots[1] += 1;
1159 return ret;
1160 }
1161 mid = slot;
1162 double_split = 1;
1163 }
1164 } else {
1165 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1166 BTRFS_LEAF_DATA_SIZE(root)) {
1167 if (slot == 0) {
1168 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1169 btrfs_set_header_nritems(&right->header, 0);
1170 wret = insert_ptr(trans, root, path,
1171 &disk_key,
1172 right_buffer->b_blocknr,
1173 path->slots[1] - 1, 1);
1174 if (wret)
1175 ret = wret;
1176 btrfs_block_release(root, path->nodes[0]);
1177 path->nodes[0] = right_buffer;
1178 path->slots[0] = 0;
1179 path->slots[1] -= 1;
1180 return ret;
1181 }
1182 mid = slot;
1183 double_split = 1;
1184 }
1185 }
1186 btrfs_set_header_nritems(&right->header, nritems - mid);
1187 data_copy_size = btrfs_item_end(l->items + mid) -
1188 leaf_data_end(root, l);
1189 btrfs_memcpy(root, right, right->items, l->items + mid,
1190 (nritems - mid) * sizeof(struct btrfs_item));
1191 btrfs_memcpy(root, right,
1192 btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
1193 data_copy_size, btrfs_leaf_data(l) +
1194 leaf_data_end(root, l), data_copy_size);
1195 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
1196 btrfs_item_end(l->items + mid);
1197
1198 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
1199 u32 ioff = btrfs_item_offset(right->items + i);
1200 btrfs_set_item_offset(right->items + i, ioff + rt_data_off);
1201 }
1202
1203 btrfs_set_header_nritems(&l->header, mid);
1204 ret = 0;
1205 wret = insert_ptr(trans, root, path, &right->items[0].key,
1206 right_buffer->b_blocknr, path->slots[1] + 1, 1);
1207 if (wret)
1208 ret = wret;
1209 btrfs_mark_buffer_dirty(right_buffer);
1210 btrfs_mark_buffer_dirty(l_buf);
1211 BUG_ON(path->slots[0] != slot);
1212 if (mid <= slot) {
1213 btrfs_block_release(root, path->nodes[0]);
1214 path->nodes[0] = right_buffer;
1215 path->slots[0] -= mid;
1216 path->slots[1] += 1;
1217 } else
1218 btrfs_block_release(root, right_buffer);
1219 BUG_ON(path->slots[0] < 0);
1220
1221 if (!double_split)
1222 return ret;
1223 right_buffer = btrfs_alloc_free_block(trans, root);
1224 BUG_ON(!right_buffer);
1225 right = btrfs_buffer_leaf(right_buffer);
1226 memset(&right->header, 0, sizeof(right->header));
1227 btrfs_set_header_blocknr(&right->header, right_buffer->b_blocknr);
1228 btrfs_set_header_generation(&right->header, trans->transid);
1229 btrfs_set_header_level(&right->header, 0);
1230 btrfs_set_header_parentid(&right->header,
1231 btrfs_header_parentid(btrfs_buffer_header(root->node)));
1232 btrfs_cpu_key_to_disk(&disk_key, ins_key);
1233 btrfs_set_header_nritems(&right->header, 0);
1234 wret = insert_ptr(trans, root, path,
1235 &disk_key,
1236 right_buffer->b_blocknr,
1237 path->slots[1], 1);
1238 if (wret)
1239 ret = wret;
1240 btrfs_block_release(root, path->nodes[0]);
1241 path->nodes[0] = right_buffer;
1242 path->slots[0] = 0;
1243 check_node(root, path, 1);
1244 check_leaf(root, path, 0);
1245 return ret;
1246 }
1247
1248 /*
1249 * Given a key and some data, insert an item into the tree.
1250 * This does all the path init required, making room in the tree if needed.
1251 */
1252 int btrfs_insert_empty_item(struct btrfs_trans_handle *trans, struct btrfs_root
1253 *root, struct btrfs_path *path, struct btrfs_key
1254 *cpu_key, u32 data_size)
1255 {
1256 int ret = 0;
1257 int slot;
1258 int slot_orig;
1259 struct btrfs_leaf *leaf;
1260 struct buffer_head *leaf_buf;
1261 u32 nritems;
1262 unsigned int data_end;
1263 struct btrfs_disk_key disk_key;
1264
1265 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1266
1267 /* create a root if there isn't one */
1268 if (!root->node)
1269 BUG();
1270 ret = btrfs_search_slot(trans, root, cpu_key, path, data_size, 1);
1271 if (ret == 0) {
1272 return -EEXIST;
1273 }
1274 if (ret < 0)
1275 goto out;
1276
1277 slot_orig = path->slots[0];
1278 leaf_buf = path->nodes[0];
1279 leaf = btrfs_buffer_leaf(leaf_buf);
1280
1281 nritems = btrfs_header_nritems(&leaf->header);
1282 data_end = leaf_data_end(root, leaf);
1283
1284 if (btrfs_leaf_free_space(root, leaf) <
1285 sizeof(struct btrfs_item) + data_size) {
1286 BUG();
1287 }
1288 slot = path->slots[0];
1289 BUG_ON(slot < 0);
1290 if (slot != nritems) {
1291 int i;
1292 unsigned int old_data = btrfs_item_end(leaf->items + slot);
1293
1294 /*
1295 * item0..itemN ... dataN.offset..dataN.size .. data0.size
1296 */
1297 /* first correct the data pointers */
1298 for (i = slot; i < nritems; i++) {
1299 u32 ioff = btrfs_item_offset(leaf->items + i);
1300 btrfs_set_item_offset(leaf->items + i,
1301 ioff - data_size);
1302 }
1303
1304 /* shift the items */
1305 btrfs_memmove(root, leaf, leaf->items + slot + 1,
1306 leaf->items + slot,
1307 (nritems - slot) * sizeof(struct btrfs_item));
1308
1309 /* shift the data */
1310 btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
1311 data_end - data_size, btrfs_leaf_data(leaf) +
1312 data_end, old_data - data_end);
1313 data_end = old_data;
1314 }
1315 /* setup the item for the new data */
1316 btrfs_memcpy(root, leaf, &leaf->items[slot].key, &disk_key,
1317 sizeof(struct btrfs_disk_key));
1318 btrfs_set_item_offset(leaf->items + slot, data_end - data_size);
1319 btrfs_set_item_size(leaf->items + slot, data_size);
1320 btrfs_set_header_nritems(&leaf->header, nritems + 1);
1321 btrfs_mark_buffer_dirty(leaf_buf);
1322
1323 ret = 0;
1324 if (slot == 0)
1325 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
1326
1327 if (btrfs_leaf_free_space(root, leaf) < 0)
1328 BUG();
1329 check_leaf(root, path, 0);
1330 out:
1331 return ret;
1332 }
1333
1334 /*
1335 * Given a key and some data, insert an item into the tree.
1336 * This does all the path init required, making room in the tree if needed.
1337 */
1338 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
1339 *root, struct btrfs_key *cpu_key, void *data, u32
1340 data_size)
1341 {
1342 int ret = 0;
1343 struct btrfs_path *path;
1344 u8 *ptr;
1345
1346 path = btrfs_alloc_path();
1347 BUG_ON(!path);
1348 btrfs_init_path(path);
1349 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
1350 if (!ret) {
1351 ptr = btrfs_item_ptr(btrfs_buffer_leaf(path->nodes[0]),
1352 path->slots[0], u8);
1353 btrfs_memcpy(root, path->nodes[0]->b_data,
1354 ptr, data, data_size);
1355 btrfs_mark_buffer_dirty(path->nodes[0]);
1356 }
1357 btrfs_release_path(root, path);
1358 btrfs_free_path(path);
1359 return ret;
1360 }
1361
1362 /*
1363 * delete the pointer from a given node.
1364 *
1365 * If the delete empties a node, the node is removed from the tree,
1366 * continuing all the way the root if required. The root is converted into
1367 * a leaf if all the nodes are emptied.
1368 */
1369 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1370 struct btrfs_path *path, int level, int slot)
1371 {
1372 struct btrfs_node *node;
1373 struct buffer_head *parent = path->nodes[level];
1374 u32 nritems;
1375 int ret = 0;
1376 int wret;
1377
1378 node = btrfs_buffer_node(parent);
1379 nritems = btrfs_header_nritems(&node->header);
1380 if (slot != nritems -1) {
1381 btrfs_memmove(root, node, node->ptrs + slot,
1382 node->ptrs + slot + 1,
1383 sizeof(struct btrfs_key_ptr) *
1384 (nritems - slot - 1));
1385 }
1386 nritems--;
1387 btrfs_set_header_nritems(&node->header, nritems);
1388 if (nritems == 0 && parent == root->node) {
1389 struct btrfs_header *header = btrfs_buffer_header(root->node);
1390 BUG_ON(btrfs_header_level(header) != 1);
1391 /* just turn the root into a leaf and break */
1392 btrfs_set_header_level(header, 0);
1393 } else if (slot == 0) {
1394 wret = fixup_low_keys(trans, root, path, &node->ptrs[0].key,
1395 level + 1);
1396 if (wret)
1397 ret = wret;
1398 }
1399 btrfs_mark_buffer_dirty(parent);
1400 return ret;
1401 }
1402
1403 /*
1404 * delete the item at the leaf level in path. If that empties
1405 * the leaf, remove it from the tree
1406 */
1407 int btrfs_del_item(struct btrfs_trans_handle *trans, struct btrfs_root *root,
1408 struct btrfs_path *path)
1409 {
1410 int slot;
1411 struct btrfs_leaf *leaf;
1412 struct buffer_head *leaf_buf;
1413 int doff;
1414 int dsize;
1415 int ret = 0;
1416 int wret;
1417 u32 nritems;
1418
1419 leaf_buf = path->nodes[0];
1420 leaf = btrfs_buffer_leaf(leaf_buf);
1421 slot = path->slots[0];
1422 doff = btrfs_item_offset(leaf->items + slot);
1423 dsize = btrfs_item_size(leaf->items + slot);
1424 nritems = btrfs_header_nritems(&leaf->header);
1425
1426 if (slot != nritems - 1) {
1427 int i;
1428 int data_end = leaf_data_end(root, leaf);
1429 btrfs_memmove(root, leaf, btrfs_leaf_data(leaf) +
1430 data_end + dsize,
1431 btrfs_leaf_data(leaf) + data_end,
1432 doff - data_end);
1433 for (i = slot + 1; i < nritems; i++) {
1434 u32 ioff = btrfs_item_offset(leaf->items + i);
1435 btrfs_set_item_offset(leaf->items + i, ioff + dsize);
1436 }
1437 btrfs_memmove(root, leaf, leaf->items + slot,
1438 leaf->items + slot + 1,
1439 sizeof(struct btrfs_item) *
1440 (nritems - slot - 1));
1441 }
1442 btrfs_set_header_nritems(&leaf->header, nritems - 1);
1443 nritems--;
1444 /* delete the leaf if we've emptied it */
1445 if (nritems == 0) {
1446 if (leaf_buf == root->node) {
1447 btrfs_set_header_level(&leaf->header, 0);
1448 } else {
1449 clean_tree_block(trans, root, leaf_buf);
1450 wait_on_buffer(leaf_buf);
1451 wret = del_ptr(trans, root, path, 1, path->slots[1]);
1452 if (wret)
1453 ret = wret;
1454 wret = btrfs_free_extent(trans, root,
1455 leaf_buf->b_blocknr, 1, 1);
1456 if (wret)
1457 ret = wret;
1458 }
1459 } else {
1460 int used = leaf_space_used(leaf, 0, nritems);
1461 if (slot == 0) {
1462 wret = fixup_low_keys(trans, root, path,
1463 &leaf->items[0].key, 1);
1464 if (wret)
1465 ret = wret;
1466 }
1467
1468 /* delete the leaf if it is mostly empty */
1469 if (used < BTRFS_LEAF_DATA_SIZE(root) / 3) {
1470 /* push_leaf_left fixes the path.
1471 * make sure the path still points to our leaf
1472 * for possible call to del_ptr below
1473 */
1474 slot = path->slots[1];
1475 get_bh(leaf_buf);
1476 wret = push_leaf_left(trans, root, path, 1);
1477 if (wret < 0)
1478 ret = wret;
1479 if (path->nodes[0] == leaf_buf &&
1480 btrfs_header_nritems(&leaf->header)) {
1481 wret = push_leaf_right(trans, root, path, 1);
1482 if (wret < 0)
1483 ret = wret;
1484 }
1485 if (btrfs_header_nritems(&leaf->header) == 0) {
1486 u64 blocknr = leaf_buf->b_blocknr;
1487 clean_tree_block(trans, root, leaf_buf);
1488 wait_on_buffer(leaf_buf);
1489 wret = del_ptr(trans, root, path, 1, slot);
1490 if (wret)
1491 ret = wret;
1492 btrfs_block_release(root, leaf_buf);
1493 wret = btrfs_free_extent(trans, root, blocknr,
1494 1, 1);
1495 if (wret)
1496 ret = wret;
1497 } else {
1498 btrfs_mark_buffer_dirty(leaf_buf);
1499 btrfs_block_release(root, leaf_buf);
1500 }
1501 } else {
1502 btrfs_mark_buffer_dirty(leaf_buf);
1503 }
1504 }
1505 return ret;
1506 }
1507
1508 /*
1509 * walk up the tree as far as required to find the next leaf.
1510 * returns 0 if it found something or 1 if there are no greater leaves.
1511 * returns < 0 on io errors.
1512 */
1513 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
1514 {
1515 int slot;
1516 int level = 1;
1517 u64 blocknr;
1518 struct buffer_head *c;
1519 struct btrfs_node *c_node;
1520 struct buffer_head *next = NULL;
1521
1522 while(level < BTRFS_MAX_LEVEL) {
1523 if (!path->nodes[level])
1524 return 1;
1525 slot = path->slots[level] + 1;
1526 c = path->nodes[level];
1527 c_node = btrfs_buffer_node(c);
1528 if (slot >= btrfs_header_nritems(&c_node->header)) {
1529 level++;
1530 continue;
1531 }
1532 blocknr = btrfs_node_blockptr(c_node, slot);
1533 if (next)
1534 btrfs_block_release(root, next);
1535 next = read_tree_block(root, blocknr);
1536 break;
1537 }
1538 path->slots[level] = slot;
1539 while(1) {
1540 level--;
1541 c = path->nodes[level];
1542 btrfs_block_release(root, c);
1543 path->nodes[level] = next;
1544 path->slots[level] = 0;
1545 if (!level)
1546 break;
1547 next = read_tree_block(root,
1548 btrfs_node_blockptr(btrfs_buffer_node(next), 0));
1549 }
1550 return 0;
1551 }
Linux kernel - Deliverables
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