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Btrfs: Retry metadata reads in the face of checksum failures
[deliverable/linux.git] / fs / btrfs / ctree.c
1 /*
2 * Copyright (C) 2007 Oracle. All rights reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public
6 * License v2 as published by the Free Software Foundation.
7 *
8 * This program is distributed in the hope that it will be useful,
9 * but WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
12 *
13 * You should have received a copy of the GNU General Public
14 * License along with this program; if not, write to the
15 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
16 * Boston, MA 021110-1307, USA.
17 */
18
19 #include <linux/sched.h>
20 #include "ctree.h"
21 #include "disk-io.h"
22 #include "transaction.h"
23 #include "print-tree.h"
24
25 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
26 *root, struct btrfs_path *path, int level);
27 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
28 *root, struct btrfs_key *ins_key,
29 struct btrfs_path *path, int data_size, int extend);
30 static int push_node_left(struct btrfs_trans_handle *trans,
31 struct btrfs_root *root, struct extent_buffer *dst,
32 struct extent_buffer *src);
33 static int balance_node_right(struct btrfs_trans_handle *trans,
34 struct btrfs_root *root,
35 struct extent_buffer *dst_buf,
36 struct extent_buffer *src_buf);
37 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
38 struct btrfs_path *path, int level, int slot);
39
40 inline void btrfs_init_path(struct btrfs_path *p)
41 {
42 memset(p, 0, sizeof(*p));
43 }
44
45 struct btrfs_path *btrfs_alloc_path(void)
46 {
47 struct btrfs_path *path;
48 path = kmem_cache_alloc(btrfs_path_cachep, GFP_NOFS);
49 if (path) {
50 btrfs_init_path(path);
51 path->reada = 1;
52 }
53 return path;
54 }
55
56 void btrfs_free_path(struct btrfs_path *p)
57 {
58 btrfs_release_path(NULL, p);
59 kmem_cache_free(btrfs_path_cachep, p);
60 }
61
62 void btrfs_release_path(struct btrfs_root *root, struct btrfs_path *p)
63 {
64 int i;
65 for (i = 0; i < BTRFS_MAX_LEVEL; i++) {
66 if (!p->nodes[i])
67 break;
68 free_extent_buffer(p->nodes[i]);
69 }
70 memset(p, 0, sizeof(*p));
71 }
72
73 static void add_root_to_dirty_list(struct btrfs_root *root)
74 {
75 if (root->track_dirty && list_empty(&root->dirty_list)) {
76 list_add(&root->dirty_list,
77 &root->fs_info->dirty_cowonly_roots);
78 }
79 }
80
81 int btrfs_copy_root(struct btrfs_trans_handle *trans,
82 struct btrfs_root *root,
83 struct extent_buffer *buf,
84 struct extent_buffer **cow_ret, u64 new_root_objectid)
85 {
86 struct extent_buffer *cow;
87 u32 nritems;
88 int ret = 0;
89 int level;
90 struct btrfs_key first_key;
91 struct btrfs_root *new_root;
92
93 new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
94 if (!new_root)
95 return -ENOMEM;
96
97 memcpy(new_root, root, sizeof(*new_root));
98 new_root->root_key.objectid = new_root_objectid;
99
100 WARN_ON(root->ref_cows && trans->transid !=
101 root->fs_info->running_transaction->transid);
102 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
103
104 level = btrfs_header_level(buf);
105 nritems = btrfs_header_nritems(buf);
106 if (nritems) {
107 if (level == 0)
108 btrfs_item_key_to_cpu(buf, &first_key, 0);
109 else
110 btrfs_node_key_to_cpu(buf, &first_key, 0);
111 } else {
112 first_key.objectid = 0;
113 }
114 cow = __btrfs_alloc_free_block(trans, new_root, buf->len,
115 new_root_objectid,
116 trans->transid, first_key.objectid,
117 level, buf->start, 0);
118 if (IS_ERR(cow)) {
119 kfree(new_root);
120 return PTR_ERR(cow);
121 }
122
123 copy_extent_buffer(cow, buf, 0, 0, cow->len);
124 btrfs_set_header_bytenr(cow, cow->start);
125 btrfs_set_header_generation(cow, trans->transid);
126 btrfs_set_header_owner(cow, new_root_objectid);
127 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
128
129 WARN_ON(btrfs_header_generation(buf) > trans->transid);
130 ret = btrfs_inc_ref(trans, new_root, buf);
131 kfree(new_root);
132
133 if (ret)
134 return ret;
135
136 btrfs_mark_buffer_dirty(cow);
137 *cow_ret = cow;
138 return 0;
139 }
140
141 int __btrfs_cow_block(struct btrfs_trans_handle *trans,
142 struct btrfs_root *root,
143 struct extent_buffer *buf,
144 struct extent_buffer *parent, int parent_slot,
145 struct extent_buffer **cow_ret,
146 u64 search_start, u64 empty_size)
147 {
148 u64 root_gen;
149 struct extent_buffer *cow;
150 u32 nritems;
151 int ret = 0;
152 int different_trans = 0;
153 int level;
154 struct btrfs_key first_key;
155
156 if (root->ref_cows) {
157 root_gen = trans->transid;
158 } else {
159 root_gen = 0;
160 }
161 WARN_ON(root->ref_cows && trans->transid !=
162 root->fs_info->running_transaction->transid);
163 WARN_ON(root->ref_cows && trans->transid != root->last_trans);
164
165 level = btrfs_header_level(buf);
166 nritems = btrfs_header_nritems(buf);
167 if (nritems) {
168 if (level == 0)
169 btrfs_item_key_to_cpu(buf, &first_key, 0);
170 else
171 btrfs_node_key_to_cpu(buf, &first_key, 0);
172 } else {
173 first_key.objectid = 0;
174 }
175 cow = __btrfs_alloc_free_block(trans, root, buf->len,
176 root->root_key.objectid,
177 root_gen, first_key.objectid, level,
178 search_start, empty_size);
179 if (IS_ERR(cow))
180 return PTR_ERR(cow);
181
182 copy_extent_buffer(cow, buf, 0, 0, cow->len);
183 btrfs_set_header_bytenr(cow, cow->start);
184 btrfs_set_header_generation(cow, trans->transid);
185 btrfs_set_header_owner(cow, root->root_key.objectid);
186 btrfs_clear_header_flag(cow, BTRFS_HEADER_FLAG_WRITTEN);
187
188 WARN_ON(btrfs_header_generation(buf) > trans->transid);
189 if (btrfs_header_generation(buf) != trans->transid) {
190 different_trans = 1;
191 ret = btrfs_inc_ref(trans, root, buf);
192 if (ret)
193 return ret;
194 } else {
195 clean_tree_block(trans, root, buf);
196 }
197
198 if (buf == root->node) {
199 root_gen = btrfs_header_generation(buf);
200 root->node = cow;
201 extent_buffer_get(cow);
202 if (buf != root->commit_root) {
203 btrfs_free_extent(trans, root, buf->start,
204 buf->len, root->root_key.objectid,
205 root_gen, 0, 0, 1);
206 }
207 free_extent_buffer(buf);
208 add_root_to_dirty_list(root);
209 } else {
210 root_gen = btrfs_header_generation(parent);
211 btrfs_set_node_blockptr(parent, parent_slot,
212 cow->start);
213 WARN_ON(trans->transid == 0);
214 btrfs_set_node_ptr_generation(parent, parent_slot,
215 trans->transid);
216 btrfs_mark_buffer_dirty(parent);
217 WARN_ON(btrfs_header_generation(parent) != trans->transid);
218 btrfs_free_extent(trans, root, buf->start, buf->len,
219 btrfs_header_owner(parent), root_gen,
220 0, 0, 1);
221 }
222 free_extent_buffer(buf);
223 btrfs_mark_buffer_dirty(cow);
224 *cow_ret = cow;
225 return 0;
226 }
227
228 int btrfs_cow_block(struct btrfs_trans_handle *trans,
229 struct btrfs_root *root, struct extent_buffer *buf,
230 struct extent_buffer *parent, int parent_slot,
231 struct extent_buffer **cow_ret)
232 {
233 u64 search_start;
234 u64 header_trans;
235 int ret;
236
237 if (trans->transaction != root->fs_info->running_transaction) {
238 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
239 root->fs_info->running_transaction->transid);
240 WARN_ON(1);
241 }
242 if (trans->transid != root->fs_info->generation) {
243 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
244 root->fs_info->generation);
245 WARN_ON(1);
246 }
247
248 header_trans = btrfs_header_generation(buf);
249 spin_lock(&root->fs_info->hash_lock);
250 if (header_trans == trans->transid &&
251 !btrfs_header_flag(buf, BTRFS_HEADER_FLAG_WRITTEN)) {
252 *cow_ret = buf;
253 spin_unlock(&root->fs_info->hash_lock);
254 return 0;
255 }
256 spin_unlock(&root->fs_info->hash_lock);
257 search_start = buf->start & ~((u64)(1024 * 1024 * 1024) - 1);
258 ret = __btrfs_cow_block(trans, root, buf, parent,
259 parent_slot, cow_ret, search_start, 0);
260 return ret;
261 }
262
263 static int close_blocks(u64 blocknr, u64 other, u32 blocksize)
264 {
265 if (blocknr < other && other - (blocknr + blocksize) < 32768)
266 return 1;
267 if (blocknr > other && blocknr - (other + blocksize) < 32768)
268 return 1;
269 return 0;
270 }
271
272 /*
273 * compare two keys in a memcmp fashion
274 */
275 static int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
276 {
277 struct btrfs_key k1;
278
279 btrfs_disk_key_to_cpu(&k1, disk);
280
281 if (k1.objectid > k2->objectid)
282 return 1;
283 if (k1.objectid < k2->objectid)
284 return -1;
285 if (k1.type > k2->type)
286 return 1;
287 if (k1.type < k2->type)
288 return -1;
289 if (k1.offset > k2->offset)
290 return 1;
291 if (k1.offset < k2->offset)
292 return -1;
293 return 0;
294 }
295
296
297 int btrfs_realloc_node(struct btrfs_trans_handle *trans,
298 struct btrfs_root *root, struct extent_buffer *parent,
299 int start_slot, int cache_only, u64 *last_ret,
300 struct btrfs_key *progress)
301 {
302 struct extent_buffer *cur;
303 struct extent_buffer *tmp;
304 u64 blocknr;
305 u64 search_start = *last_ret;
306 u64 last_block = 0;
307 u64 other;
308 u32 parent_nritems;
309 int end_slot;
310 int i;
311 int err = 0;
312 int parent_level;
313 int uptodate;
314 u32 blocksize;
315 int progress_passed = 0;
316 struct btrfs_disk_key disk_key;
317
318 parent_level = btrfs_header_level(parent);
319 if (cache_only && parent_level != 1)
320 return 0;
321
322 if (trans->transaction != root->fs_info->running_transaction) {
323 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
324 root->fs_info->running_transaction->transid);
325 WARN_ON(1);
326 }
327 if (trans->transid != root->fs_info->generation) {
328 printk(KERN_CRIT "trans %Lu running %Lu\n", trans->transid,
329 root->fs_info->generation);
330 WARN_ON(1);
331 }
332
333 parent_nritems = btrfs_header_nritems(parent);
334 blocksize = btrfs_level_size(root, parent_level - 1);
335 end_slot = parent_nritems;
336
337 if (parent_nritems == 1)
338 return 0;
339
340 for (i = start_slot; i < end_slot; i++) {
341 int close = 1;
342
343 if (!parent->map_token) {
344 map_extent_buffer(parent,
345 btrfs_node_key_ptr_offset(i),
346 sizeof(struct btrfs_key_ptr),
347 &parent->map_token, &parent->kaddr,
348 &parent->map_start, &parent->map_len,
349 KM_USER1);
350 }
351 btrfs_node_key(parent, &disk_key, i);
352 if (!progress_passed && comp_keys(&disk_key, progress) < 0)
353 continue;
354
355 progress_passed = 1;
356 blocknr = btrfs_node_blockptr(parent, i);
357 if (last_block == 0)
358 last_block = blocknr;
359
360 if (i > 0) {
361 other = btrfs_node_blockptr(parent, i - 1);
362 close = close_blocks(blocknr, other, blocksize);
363 }
364 if (close && i < end_slot - 2) {
365 other = btrfs_node_blockptr(parent, i + 1);
366 close = close_blocks(blocknr, other, blocksize);
367 }
368 if (close) {
369 last_block = blocknr;
370 continue;
371 }
372 if (parent->map_token) {
373 unmap_extent_buffer(parent, parent->map_token,
374 KM_USER1);
375 parent->map_token = NULL;
376 }
377
378 cur = btrfs_find_tree_block(root, blocknr, blocksize);
379 if (cur)
380 uptodate = btrfs_buffer_uptodate(cur);
381 else
382 uptodate = 0;
383 if (!cur || !uptodate) {
384 if (cache_only) {
385 free_extent_buffer(cur);
386 continue;
387 }
388 if (!cur) {
389 cur = read_tree_block(root, blocknr,
390 blocksize);
391 } else if (!uptodate) {
392 btrfs_read_buffer(cur);
393 }
394 }
395 if (search_start == 0)
396 search_start = last_block;
397
398 btrfs_verify_block_csum(root, cur);
399 err = __btrfs_cow_block(trans, root, cur, parent, i,
400 &tmp, search_start,
401 min(16 * blocksize,
402 (end_slot - i) * blocksize));
403 if (err) {
404 free_extent_buffer(cur);
405 break;
406 }
407 search_start = tmp->start;
408 last_block = tmp->start;
409 *last_ret = search_start;
410 if (parent_level == 1)
411 btrfs_clear_buffer_defrag(tmp);
412 free_extent_buffer(tmp);
413 }
414 if (parent->map_token) {
415 unmap_extent_buffer(parent, parent->map_token,
416 KM_USER1);
417 parent->map_token = NULL;
418 }
419 return err;
420 }
421
422 /*
423 * The leaf data grows from end-to-front in the node.
424 * this returns the address of the start of the last item,
425 * which is the stop of the leaf data stack
426 */
427 static inline unsigned int leaf_data_end(struct btrfs_root *root,
428 struct extent_buffer *leaf)
429 {
430 u32 nr = btrfs_header_nritems(leaf);
431 if (nr == 0)
432 return BTRFS_LEAF_DATA_SIZE(root);
433 return btrfs_item_offset_nr(leaf, nr - 1);
434 }
435
436 static int check_node(struct btrfs_root *root, struct btrfs_path *path,
437 int level)
438 {
439 struct extent_buffer *parent = NULL;
440 struct extent_buffer *node = path->nodes[level];
441 struct btrfs_disk_key parent_key;
442 struct btrfs_disk_key node_key;
443 int parent_slot;
444 int slot;
445 struct btrfs_key cpukey;
446 u32 nritems = btrfs_header_nritems(node);
447
448 if (path->nodes[level + 1])
449 parent = path->nodes[level + 1];
450
451 slot = path->slots[level];
452 BUG_ON(nritems == 0);
453 if (parent) {
454 parent_slot = path->slots[level + 1];
455 btrfs_node_key(parent, &parent_key, parent_slot);
456 btrfs_node_key(node, &node_key, 0);
457 BUG_ON(memcmp(&parent_key, &node_key,
458 sizeof(struct btrfs_disk_key)));
459 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
460 btrfs_header_bytenr(node));
461 }
462 BUG_ON(nritems > BTRFS_NODEPTRS_PER_BLOCK(root));
463 if (slot != 0) {
464 btrfs_node_key_to_cpu(node, &cpukey, slot - 1);
465 btrfs_node_key(node, &node_key, slot);
466 BUG_ON(comp_keys(&node_key, &cpukey) <= 0);
467 }
468 if (slot < nritems - 1) {
469 btrfs_node_key_to_cpu(node, &cpukey, slot + 1);
470 btrfs_node_key(node, &node_key, slot);
471 BUG_ON(comp_keys(&node_key, &cpukey) >= 0);
472 }
473 return 0;
474 }
475
476 static int check_leaf(struct btrfs_root *root, struct btrfs_path *path,
477 int level)
478 {
479 struct extent_buffer *leaf = path->nodes[level];
480 struct extent_buffer *parent = NULL;
481 int parent_slot;
482 struct btrfs_key cpukey;
483 struct btrfs_disk_key parent_key;
484 struct btrfs_disk_key leaf_key;
485 int slot = path->slots[0];
486
487 u32 nritems = btrfs_header_nritems(leaf);
488
489 if (path->nodes[level + 1])
490 parent = path->nodes[level + 1];
491
492 if (nritems == 0)
493 return 0;
494
495 if (parent) {
496 parent_slot = path->slots[level + 1];
497 btrfs_node_key(parent, &parent_key, parent_slot);
498 btrfs_item_key(leaf, &leaf_key, 0);
499
500 BUG_ON(memcmp(&parent_key, &leaf_key,
501 sizeof(struct btrfs_disk_key)));
502 BUG_ON(btrfs_node_blockptr(parent, parent_slot) !=
503 btrfs_header_bytenr(leaf));
504 }
505 #if 0
506 for (i = 0; nritems > 1 && i < nritems - 2; i++) {
507 btrfs_item_key_to_cpu(leaf, &cpukey, i + 1);
508 btrfs_item_key(leaf, &leaf_key, i);
509 if (comp_keys(&leaf_key, &cpukey) >= 0) {
510 btrfs_print_leaf(root, leaf);
511 printk("slot %d offset bad key\n", i);
512 BUG_ON(1);
513 }
514 if (btrfs_item_offset_nr(leaf, i) !=
515 btrfs_item_end_nr(leaf, i + 1)) {
516 btrfs_print_leaf(root, leaf);
517 printk("slot %d offset bad\n", i);
518 BUG_ON(1);
519 }
520 if (i == 0) {
521 if (btrfs_item_offset_nr(leaf, i) +
522 btrfs_item_size_nr(leaf, i) !=
523 BTRFS_LEAF_DATA_SIZE(root)) {
524 btrfs_print_leaf(root, leaf);
525 printk("slot %d first offset bad\n", i);
526 BUG_ON(1);
527 }
528 }
529 }
530 if (nritems > 0) {
531 if (btrfs_item_size_nr(leaf, nritems - 1) > 4096) {
532 btrfs_print_leaf(root, leaf);
533 printk("slot %d bad size \n", nritems - 1);
534 BUG_ON(1);
535 }
536 }
537 #endif
538 if (slot != 0 && slot < nritems - 1) {
539 btrfs_item_key(leaf, &leaf_key, slot);
540 btrfs_item_key_to_cpu(leaf, &cpukey, slot - 1);
541 if (comp_keys(&leaf_key, &cpukey) <= 0) {
542 btrfs_print_leaf(root, leaf);
543 printk("slot %d offset bad key\n", slot);
544 BUG_ON(1);
545 }
546 if (btrfs_item_offset_nr(leaf, slot - 1) !=
547 btrfs_item_end_nr(leaf, slot)) {
548 btrfs_print_leaf(root, leaf);
549 printk("slot %d offset bad\n", slot);
550 BUG_ON(1);
551 }
552 }
553 if (slot < nritems - 1) {
554 btrfs_item_key(leaf, &leaf_key, slot);
555 btrfs_item_key_to_cpu(leaf, &cpukey, slot + 1);
556 BUG_ON(comp_keys(&leaf_key, &cpukey) >= 0);
557 if (btrfs_item_offset_nr(leaf, slot) !=
558 btrfs_item_end_nr(leaf, slot + 1)) {
559 btrfs_print_leaf(root, leaf);
560 printk("slot %d offset bad\n", slot);
561 BUG_ON(1);
562 }
563 }
564 BUG_ON(btrfs_item_offset_nr(leaf, 0) +
565 btrfs_item_size_nr(leaf, 0) != BTRFS_LEAF_DATA_SIZE(root));
566 return 0;
567 }
568
569 static int noinline check_block(struct btrfs_root *root,
570 struct btrfs_path *path, int level)
571 {
572 u64 found_start;
573 if (btrfs_header_level(path->nodes[level]) != level)
574 printk("warning: bad level %Lu wanted %d found %d\n",
575 path->nodes[level]->start, level,
576 btrfs_header_level(path->nodes[level]));
577 found_start = btrfs_header_bytenr(path->nodes[level]);
578 if (found_start != path->nodes[level]->start) {
579 printk("warning: bad bytentr %Lu found %Lu\n",
580 path->nodes[level]->start, found_start);
581 }
582 #if 0
583 struct extent_buffer *buf = path->nodes[level];
584
585 if (memcmp_extent_buffer(buf, root->fs_info->fsid,
586 (unsigned long)btrfs_header_fsid(buf),
587 BTRFS_FSID_SIZE)) {
588 printk("warning bad block %Lu\n", buf->start);
589 return 1;
590 }
591 #endif
592 if (level == 0)
593 return check_leaf(root, path, level);
594 return check_node(root, path, level);
595 }
596
597 /*
598 * search for key in the extent_buffer. The items start at offset p,
599 * and they are item_size apart. There are 'max' items in p.
600 *
601 * the slot in the array is returned via slot, and it points to
602 * the place where you would insert key if it is not found in
603 * the array.
604 *
605 * slot may point to max if the key is bigger than all of the keys
606 */
607 static int generic_bin_search(struct extent_buffer *eb, unsigned long p,
608 int item_size, struct btrfs_key *key,
609 int max, int *slot)
610 {
611 int low = 0;
612 int high = max;
613 int mid;
614 int ret;
615 struct btrfs_disk_key *tmp = NULL;
616 struct btrfs_disk_key unaligned;
617 unsigned long offset;
618 char *map_token = NULL;
619 char *kaddr = NULL;
620 unsigned long map_start = 0;
621 unsigned long map_len = 0;
622 int err;
623
624 while(low < high) {
625 mid = (low + high) / 2;
626 offset = p + mid * item_size;
627
628 if (!map_token || offset < map_start ||
629 (offset + sizeof(struct btrfs_disk_key)) >
630 map_start + map_len) {
631 if (map_token) {
632 unmap_extent_buffer(eb, map_token, KM_USER0);
633 map_token = NULL;
634 }
635 err = map_extent_buffer(eb, offset,
636 sizeof(struct btrfs_disk_key),
637 &map_token, &kaddr,
638 &map_start, &map_len, KM_USER0);
639
640 if (!err) {
641 tmp = (struct btrfs_disk_key *)(kaddr + offset -
642 map_start);
643 } else {
644 read_extent_buffer(eb, &unaligned,
645 offset, sizeof(unaligned));
646 tmp = &unaligned;
647 }
648
649 } else {
650 tmp = (struct btrfs_disk_key *)(kaddr + offset -
651 map_start);
652 }
653 ret = comp_keys(tmp, key);
654
655 if (ret < 0)
656 low = mid + 1;
657 else if (ret > 0)
658 high = mid;
659 else {
660 *slot = mid;
661 if (map_token)
662 unmap_extent_buffer(eb, map_token, KM_USER0);
663 return 0;
664 }
665 }
666 *slot = low;
667 if (map_token)
668 unmap_extent_buffer(eb, map_token, KM_USER0);
669 return 1;
670 }
671
672 /*
673 * simple bin_search frontend that does the right thing for
674 * leaves vs nodes
675 */
676 static int bin_search(struct extent_buffer *eb, struct btrfs_key *key,
677 int level, int *slot)
678 {
679 if (level == 0) {
680 return generic_bin_search(eb,
681 offsetof(struct btrfs_leaf, items),
682 sizeof(struct btrfs_item),
683 key, btrfs_header_nritems(eb),
684 slot);
685 } else {
686 return generic_bin_search(eb,
687 offsetof(struct btrfs_node, ptrs),
688 sizeof(struct btrfs_key_ptr),
689 key, btrfs_header_nritems(eb),
690 slot);
691 }
692 return -1;
693 }
694
695 static struct extent_buffer *read_node_slot(struct btrfs_root *root,
696 struct extent_buffer *parent, int slot)
697 {
698 if (slot < 0)
699 return NULL;
700 if (slot >= btrfs_header_nritems(parent))
701 return NULL;
702 return read_tree_block(root, btrfs_node_blockptr(parent, slot),
703 btrfs_level_size(root, btrfs_header_level(parent) - 1));
704 }
705
706 static int balance_level(struct btrfs_trans_handle *trans,
707 struct btrfs_root *root,
708 struct btrfs_path *path, int level)
709 {
710 struct extent_buffer *right = NULL;
711 struct extent_buffer *mid;
712 struct extent_buffer *left = NULL;
713 struct extent_buffer *parent = NULL;
714 int ret = 0;
715 int wret;
716 int pslot;
717 int orig_slot = path->slots[level];
718 int err_on_enospc = 0;
719 u64 orig_ptr;
720
721 if (level == 0)
722 return 0;
723
724 mid = path->nodes[level];
725 WARN_ON(btrfs_header_generation(mid) != trans->transid);
726
727 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
728
729 if (level < BTRFS_MAX_LEVEL - 1)
730 parent = path->nodes[level + 1];
731 pslot = path->slots[level + 1];
732
733 /*
734 * deal with the case where there is only one pointer in the root
735 * by promoting the node below to a root
736 */
737 if (!parent) {
738 struct extent_buffer *child;
739
740 if (btrfs_header_nritems(mid) != 1)
741 return 0;
742
743 /* promote the child to a root */
744 child = read_node_slot(root, mid, 0);
745 BUG_ON(!child);
746 ret = btrfs_cow_block(trans, root, child, mid, 0, &child);
747 BUG_ON(ret);
748
749 root->node = child;
750 add_root_to_dirty_list(root);
751 path->nodes[level] = NULL;
752 clean_tree_block(trans, root, mid);
753 wait_on_tree_block_writeback(root, mid);
754 /* once for the path */
755 free_extent_buffer(mid);
756 ret = btrfs_free_extent(trans, root, mid->start, mid->len,
757 root->root_key.objectid,
758 btrfs_header_generation(mid), 0, 0, 1);
759 /* once for the root ptr */
760 free_extent_buffer(mid);
761 return ret;
762 }
763 if (btrfs_header_nritems(mid) >
764 BTRFS_NODEPTRS_PER_BLOCK(root) / 4)
765 return 0;
766
767 if (btrfs_header_nritems(mid) < 2)
768 err_on_enospc = 1;
769
770 left = read_node_slot(root, parent, pslot - 1);
771 if (left) {
772 wret = btrfs_cow_block(trans, root, left,
773 parent, pslot - 1, &left);
774 if (wret) {
775 ret = wret;
776 goto enospc;
777 }
778 }
779 right = read_node_slot(root, parent, pslot + 1);
780 if (right) {
781 wret = btrfs_cow_block(trans, root, right,
782 parent, pslot + 1, &right);
783 if (wret) {
784 ret = wret;
785 goto enospc;
786 }
787 }
788
789 /* first, try to make some room in the middle buffer */
790 if (left) {
791 orig_slot += btrfs_header_nritems(left);
792 wret = push_node_left(trans, root, left, mid);
793 if (wret < 0)
794 ret = wret;
795 if (btrfs_header_nritems(mid) < 2)
796 err_on_enospc = 1;
797 }
798
799 /*
800 * then try to empty the right most buffer into the middle
801 */
802 if (right) {
803 wret = push_node_left(trans, root, mid, right);
804 if (wret < 0 && wret != -ENOSPC)
805 ret = wret;
806 if (btrfs_header_nritems(right) == 0) {
807 u64 bytenr = right->start;
808 u64 generation = btrfs_header_generation(parent);
809 u32 blocksize = right->len;
810
811 clean_tree_block(trans, root, right);
812 wait_on_tree_block_writeback(root, right);
813 free_extent_buffer(right);
814 right = NULL;
815 wret = del_ptr(trans, root, path, level + 1, pslot +
816 1);
817 if (wret)
818 ret = wret;
819 wret = btrfs_free_extent(trans, root, bytenr,
820 blocksize,
821 btrfs_header_owner(parent),
822 generation, 0, 0, 1);
823 if (wret)
824 ret = wret;
825 } else {
826 struct btrfs_disk_key right_key;
827 btrfs_node_key(right, &right_key, 0);
828 btrfs_set_node_key(parent, &right_key, pslot + 1);
829 btrfs_mark_buffer_dirty(parent);
830 }
831 }
832 if (btrfs_header_nritems(mid) == 1) {
833 /*
834 * we're not allowed to leave a node with one item in the
835 * tree during a delete. A deletion from lower in the tree
836 * could try to delete the only pointer in this node.
837 * So, pull some keys from the left.
838 * There has to be a left pointer at this point because
839 * otherwise we would have pulled some pointers from the
840 * right
841 */
842 BUG_ON(!left);
843 wret = balance_node_right(trans, root, mid, left);
844 if (wret < 0) {
845 ret = wret;
846 goto enospc;
847 }
848 BUG_ON(wret == 1);
849 }
850 if (btrfs_header_nritems(mid) == 0) {
851 /* we've managed to empty the middle node, drop it */
852 u64 root_gen = btrfs_header_generation(parent);
853 u64 bytenr = mid->start;
854 u32 blocksize = mid->len;
855 clean_tree_block(trans, root, mid);
856 wait_on_tree_block_writeback(root, mid);
857 free_extent_buffer(mid);
858 mid = NULL;
859 wret = del_ptr(trans, root, path, level + 1, pslot);
860 if (wret)
861 ret = wret;
862 wret = btrfs_free_extent(trans, root, bytenr, blocksize,
863 btrfs_header_owner(parent),
864 root_gen, 0, 0, 1);
865 if (wret)
866 ret = wret;
867 } else {
868 /* update the parent key to reflect our changes */
869 struct btrfs_disk_key mid_key;
870 btrfs_node_key(mid, &mid_key, 0);
871 btrfs_set_node_key(parent, &mid_key, pslot);
872 btrfs_mark_buffer_dirty(parent);
873 }
874
875 /* update the path */
876 if (left) {
877 if (btrfs_header_nritems(left) > orig_slot) {
878 extent_buffer_get(left);
879 path->nodes[level] = left;
880 path->slots[level + 1] -= 1;
881 path->slots[level] = orig_slot;
882 if (mid)
883 free_extent_buffer(mid);
884 } else {
885 orig_slot -= btrfs_header_nritems(left);
886 path->slots[level] = orig_slot;
887 }
888 }
889 /* double check we haven't messed things up */
890 check_block(root, path, level);
891 if (orig_ptr !=
892 btrfs_node_blockptr(path->nodes[level], path->slots[level]))
893 BUG();
894 enospc:
895 if (right)
896 free_extent_buffer(right);
897 if (left)
898 free_extent_buffer(left);
899 return ret;
900 }
901
902 /* returns zero if the push worked, non-zero otherwise */
903 static int noinline push_nodes_for_insert(struct btrfs_trans_handle *trans,
904 struct btrfs_root *root,
905 struct btrfs_path *path, int level)
906 {
907 struct extent_buffer *right = NULL;
908 struct extent_buffer *mid;
909 struct extent_buffer *left = NULL;
910 struct extent_buffer *parent = NULL;
911 int ret = 0;
912 int wret;
913 int pslot;
914 int orig_slot = path->slots[level];
915 u64 orig_ptr;
916
917 if (level == 0)
918 return 1;
919
920 mid = path->nodes[level];
921 WARN_ON(btrfs_header_generation(mid) != trans->transid);
922 orig_ptr = btrfs_node_blockptr(mid, orig_slot);
923
924 if (level < BTRFS_MAX_LEVEL - 1)
925 parent = path->nodes[level + 1];
926 pslot = path->slots[level + 1];
927
928 if (!parent)
929 return 1;
930
931 left = read_node_slot(root, parent, pslot - 1);
932
933 /* first, try to make some room in the middle buffer */
934 if (left) {
935 u32 left_nr;
936 left_nr = btrfs_header_nritems(left);
937 if (left_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
938 wret = 1;
939 } else {
940 ret = btrfs_cow_block(trans, root, left, parent,
941 pslot - 1, &left);
942 if (ret)
943 wret = 1;
944 else {
945 wret = push_node_left(trans, root,
946 left, mid);
947 }
948 }
949 if (wret < 0)
950 ret = wret;
951 if (wret == 0) {
952 struct btrfs_disk_key disk_key;
953 orig_slot += left_nr;
954 btrfs_node_key(mid, &disk_key, 0);
955 btrfs_set_node_key(parent, &disk_key, pslot);
956 btrfs_mark_buffer_dirty(parent);
957 if (btrfs_header_nritems(left) > orig_slot) {
958 path->nodes[level] = left;
959 path->slots[level + 1] -= 1;
960 path->slots[level] = orig_slot;
961 free_extent_buffer(mid);
962 } else {
963 orig_slot -=
964 btrfs_header_nritems(left);
965 path->slots[level] = orig_slot;
966 free_extent_buffer(left);
967 }
968 return 0;
969 }
970 free_extent_buffer(left);
971 }
972 right= read_node_slot(root, parent, pslot + 1);
973
974 /*
975 * then try to empty the right most buffer into the middle
976 */
977 if (right) {
978 u32 right_nr;
979 right_nr = btrfs_header_nritems(right);
980 if (right_nr >= BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
981 wret = 1;
982 } else {
983 ret = btrfs_cow_block(trans, root, right,
984 parent, pslot + 1,
985 &right);
986 if (ret)
987 wret = 1;
988 else {
989 wret = balance_node_right(trans, root,
990 right, mid);
991 }
992 }
993 if (wret < 0)
994 ret = wret;
995 if (wret == 0) {
996 struct btrfs_disk_key disk_key;
997
998 btrfs_node_key(right, &disk_key, 0);
999 btrfs_set_node_key(parent, &disk_key, pslot + 1);
1000 btrfs_mark_buffer_dirty(parent);
1001
1002 if (btrfs_header_nritems(mid) <= orig_slot) {
1003 path->nodes[level] = right;
1004 path->slots[level + 1] += 1;
1005 path->slots[level] = orig_slot -
1006 btrfs_header_nritems(mid);
1007 free_extent_buffer(mid);
1008 } else {
1009 free_extent_buffer(right);
1010 }
1011 return 0;
1012 }
1013 free_extent_buffer(right);
1014 }
1015 return 1;
1016 }
1017
1018 /*
1019 * readahead one full node of leaves
1020 */
1021 static void reada_for_search(struct btrfs_root *root, struct btrfs_path *path,
1022 int level, int slot, u64 objectid)
1023 {
1024 struct extent_buffer *node;
1025 struct btrfs_disk_key disk_key;
1026 u32 nritems;
1027 u64 search;
1028 u64 lowest_read;
1029 u64 highest_read;
1030 u64 nread = 0;
1031 int direction = path->reada;
1032 struct extent_buffer *eb;
1033 u32 nr;
1034 u32 blocksize;
1035 u32 nscan = 0;
1036
1037 if (level != 1)
1038 return;
1039
1040 if (!path->nodes[level])
1041 return;
1042
1043 node = path->nodes[level];
1044 search = btrfs_node_blockptr(node, slot);
1045 blocksize = btrfs_level_size(root, level - 1);
1046 eb = btrfs_find_tree_block(root, search, blocksize);
1047 if (eb) {
1048 free_extent_buffer(eb);
1049 return;
1050 }
1051
1052 highest_read = search;
1053 lowest_read = search;
1054
1055 nritems = btrfs_header_nritems(node);
1056 nr = slot;
1057 while(1) {
1058 if (direction < 0) {
1059 if (nr == 0)
1060 break;
1061 nr--;
1062 } else if (direction > 0) {
1063 nr++;
1064 if (nr >= nritems)
1065 break;
1066 }
1067 if (path->reada < 0 && objectid) {
1068 btrfs_node_key(node, &disk_key, nr);
1069 if (btrfs_disk_key_objectid(&disk_key) != objectid)
1070 break;
1071 }
1072 search = btrfs_node_blockptr(node, nr);
1073 if ((search >= lowest_read && search <= highest_read) ||
1074 (search < lowest_read && lowest_read - search <= 32768) ||
1075 (search > highest_read && search - highest_read <= 32768)) {
1076 readahead_tree_block(root, search, blocksize);
1077 nread += blocksize;
1078 }
1079 nscan++;
1080 if (path->reada < 2 && (nread > (256 * 1024) || nscan > 32))
1081 break;
1082 if(nread > (1024 * 1024) || nscan > 128)
1083 break;
1084
1085 if (search < lowest_read)
1086 lowest_read = search;
1087 if (search > highest_read)
1088 highest_read = search;
1089 }
1090 }
1091 /*
1092 * look for key in the tree. path is filled in with nodes along the way
1093 * if key is found, we return zero and you can find the item in the leaf
1094 * level of the path (level 0)
1095 *
1096 * If the key isn't found, the path points to the slot where it should
1097 * be inserted, and 1 is returned. If there are other errors during the
1098 * search a negative error number is returned.
1099 *
1100 * if ins_len > 0, nodes and leaves will be split as we walk down the
1101 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
1102 * possible)
1103 */
1104 int btrfs_search_slot(struct btrfs_trans_handle *trans, struct btrfs_root
1105 *root, struct btrfs_key *key, struct btrfs_path *p, int
1106 ins_len, int cow)
1107 {
1108 struct extent_buffer *b;
1109 u64 bytenr;
1110 u64 ptr_gen;
1111 int slot;
1112 int ret;
1113 int level;
1114 int should_reada = p->reada;
1115 u8 lowest_level = 0;
1116
1117 lowest_level = p->lowest_level;
1118 WARN_ON(lowest_level && ins_len);
1119 WARN_ON(p->nodes[0] != NULL);
1120 WARN_ON(!mutex_is_locked(&root->fs_info->fs_mutex));
1121 again:
1122 b = root->node;
1123 extent_buffer_get(b);
1124 while (b) {
1125 level = btrfs_header_level(b);
1126 if (cow) {
1127 int wret;
1128 wret = btrfs_cow_block(trans, root, b,
1129 p->nodes[level + 1],
1130 p->slots[level + 1],
1131 &b);
1132 if (wret) {
1133 free_extent_buffer(b);
1134 return wret;
1135 }
1136 }
1137 BUG_ON(!cow && ins_len);
1138 if (level != btrfs_header_level(b))
1139 WARN_ON(1);
1140 level = btrfs_header_level(b);
1141 p->nodes[level] = b;
1142 ret = check_block(root, p, level);
1143 if (ret)
1144 return -1;
1145 ret = bin_search(b, key, level, &slot);
1146 if (level != 0) {
1147 if (ret && slot > 0)
1148 slot -= 1;
1149 p->slots[level] = slot;
1150 if (ins_len > 0 && btrfs_header_nritems(b) >=
1151 BTRFS_NODEPTRS_PER_BLOCK(root) - 1) {
1152 int sret = split_node(trans, root, p, level);
1153 BUG_ON(sret > 0);
1154 if (sret)
1155 return sret;
1156 b = p->nodes[level];
1157 slot = p->slots[level];
1158 } else if (ins_len < 0) {
1159 int sret = balance_level(trans, root, p,
1160 level);
1161 if (sret)
1162 return sret;
1163 b = p->nodes[level];
1164 if (!b) {
1165 btrfs_release_path(NULL, p);
1166 goto again;
1167 }
1168 slot = p->slots[level];
1169 BUG_ON(btrfs_header_nritems(b) == 1);
1170 }
1171 /* this is only true while dropping a snapshot */
1172 if (level == lowest_level)
1173 break;
1174 bytenr = btrfs_node_blockptr(b, slot);
1175 ptr_gen = btrfs_node_ptr_generation(b, slot);
1176 if (should_reada)
1177 reada_for_search(root, p, level, slot,
1178 key->objectid);
1179 b = read_tree_block(root, bytenr,
1180 btrfs_level_size(root, level - 1));
1181 if (ptr_gen != btrfs_header_generation(b)) {
1182 printk("block %llu bad gen wanted %llu "
1183 "found %llu\n",
1184 (unsigned long long)b->start,
1185 (unsigned long long)ptr_gen,
1186 (unsigned long long)btrfs_header_generation(b));
1187 }
1188 } else {
1189 p->slots[level] = slot;
1190 if (ins_len > 0 && btrfs_leaf_free_space(root, b) <
1191 sizeof(struct btrfs_item) + ins_len) {
1192 int sret = split_leaf(trans, root, key,
1193 p, ins_len, ret == 0);
1194 BUG_ON(sret > 0);
1195 if (sret)
1196 return sret;
1197 }
1198 return ret;
1199 }
1200 }
1201 return 1;
1202 }
1203
1204 /*
1205 * adjust the pointers going up the tree, starting at level
1206 * making sure the right key of each node is points to 'key'.
1207 * This is used after shifting pointers to the left, so it stops
1208 * fixing up pointers when a given leaf/node is not in slot 0 of the
1209 * higher levels
1210 *
1211 * If this fails to write a tree block, it returns -1, but continues
1212 * fixing up the blocks in ram so the tree is consistent.
1213 */
1214 static int fixup_low_keys(struct btrfs_trans_handle *trans,
1215 struct btrfs_root *root, struct btrfs_path *path,
1216 struct btrfs_disk_key *key, int level)
1217 {
1218 int i;
1219 int ret = 0;
1220 struct extent_buffer *t;
1221
1222 for (i = level; i < BTRFS_MAX_LEVEL; i++) {
1223 int tslot = path->slots[i];
1224 if (!path->nodes[i])
1225 break;
1226 t = path->nodes[i];
1227 btrfs_set_node_key(t, key, tslot);
1228 btrfs_mark_buffer_dirty(path->nodes[i]);
1229 if (tslot != 0)
1230 break;
1231 }
1232 return ret;
1233 }
1234
1235 /*
1236 * try to push data from one node into the next node left in the
1237 * tree.
1238 *
1239 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
1240 * error, and > 0 if there was no room in the left hand block.
1241 */
1242 static int push_node_left(struct btrfs_trans_handle *trans,
1243 struct btrfs_root *root, struct extent_buffer *dst,
1244 struct extent_buffer *src)
1245 {
1246 int push_items = 0;
1247 int src_nritems;
1248 int dst_nritems;
1249 int ret = 0;
1250
1251 src_nritems = btrfs_header_nritems(src);
1252 dst_nritems = btrfs_header_nritems(dst);
1253 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1254 WARN_ON(btrfs_header_generation(src) != trans->transid);
1255 WARN_ON(btrfs_header_generation(dst) != trans->transid);
1256
1257 if (push_items <= 0) {
1258 return 1;
1259 }
1260
1261 if (src_nritems < push_items)
1262 push_items = src_nritems;
1263
1264 copy_extent_buffer(dst, src,
1265 btrfs_node_key_ptr_offset(dst_nritems),
1266 btrfs_node_key_ptr_offset(0),
1267 push_items * sizeof(struct btrfs_key_ptr));
1268
1269 if (push_items < src_nritems) {
1270 memmove_extent_buffer(src, btrfs_node_key_ptr_offset(0),
1271 btrfs_node_key_ptr_offset(push_items),
1272 (src_nritems - push_items) *
1273 sizeof(struct btrfs_key_ptr));
1274 }
1275 btrfs_set_header_nritems(src, src_nritems - push_items);
1276 btrfs_set_header_nritems(dst, dst_nritems + push_items);
1277 btrfs_mark_buffer_dirty(src);
1278 btrfs_mark_buffer_dirty(dst);
1279 return ret;
1280 }
1281
1282 /*
1283 * try to push data from one node into the next node right in the
1284 * tree.
1285 *
1286 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
1287 * error, and > 0 if there was no room in the right hand block.
1288 *
1289 * this will only push up to 1/2 the contents of the left node over
1290 */
1291 static int balance_node_right(struct btrfs_trans_handle *trans,
1292 struct btrfs_root *root,
1293 struct extent_buffer *dst,
1294 struct extent_buffer *src)
1295 {
1296 int push_items = 0;
1297 int max_push;
1298 int src_nritems;
1299 int dst_nritems;
1300 int ret = 0;
1301
1302 WARN_ON(btrfs_header_generation(src) != trans->transid);
1303 WARN_ON(btrfs_header_generation(dst) != trans->transid);
1304
1305 src_nritems = btrfs_header_nritems(src);
1306 dst_nritems = btrfs_header_nritems(dst);
1307 push_items = BTRFS_NODEPTRS_PER_BLOCK(root) - dst_nritems;
1308 if (push_items <= 0)
1309 return 1;
1310
1311 max_push = src_nritems / 2 + 1;
1312 /* don't try to empty the node */
1313 if (max_push >= src_nritems)
1314 return 1;
1315
1316 if (max_push < push_items)
1317 push_items = max_push;
1318
1319 memmove_extent_buffer(dst, btrfs_node_key_ptr_offset(push_items),
1320 btrfs_node_key_ptr_offset(0),
1321 (dst_nritems) *
1322 sizeof(struct btrfs_key_ptr));
1323
1324 copy_extent_buffer(dst, src,
1325 btrfs_node_key_ptr_offset(0),
1326 btrfs_node_key_ptr_offset(src_nritems - push_items),
1327 push_items * sizeof(struct btrfs_key_ptr));
1328
1329 btrfs_set_header_nritems(src, src_nritems - push_items);
1330 btrfs_set_header_nritems(dst, dst_nritems + push_items);
1331
1332 btrfs_mark_buffer_dirty(src);
1333 btrfs_mark_buffer_dirty(dst);
1334 return ret;
1335 }
1336
1337 /*
1338 * helper function to insert a new root level in the tree.
1339 * A new node is allocated, and a single item is inserted to
1340 * point to the existing root
1341 *
1342 * returns zero on success or < 0 on failure.
1343 */
1344 static int noinline insert_new_root(struct btrfs_trans_handle *trans,
1345 struct btrfs_root *root,
1346 struct btrfs_path *path, int level)
1347 {
1348 u64 root_gen;
1349 u64 lower_gen;
1350 struct extent_buffer *lower;
1351 struct extent_buffer *c;
1352 struct btrfs_disk_key lower_key;
1353
1354 BUG_ON(path->nodes[level]);
1355 BUG_ON(path->nodes[level-1] != root->node);
1356
1357 if (root->ref_cows)
1358 root_gen = trans->transid;
1359 else
1360 root_gen = 0;
1361
1362 lower = path->nodes[level-1];
1363 if (level == 1)
1364 btrfs_item_key(lower, &lower_key, 0);
1365 else
1366 btrfs_node_key(lower, &lower_key, 0);
1367
1368 c = __btrfs_alloc_free_block(trans, root, root->nodesize,
1369 root->root_key.objectid,
1370 root_gen, lower_key.objectid, level,
1371 root->node->start, 0);
1372 if (IS_ERR(c))
1373 return PTR_ERR(c);
1374 memset_extent_buffer(c, 0, 0, root->nodesize);
1375 btrfs_set_header_nritems(c, 1);
1376 btrfs_set_header_level(c, level);
1377 btrfs_set_header_bytenr(c, c->start);
1378 btrfs_set_header_generation(c, trans->transid);
1379 btrfs_set_header_owner(c, root->root_key.objectid);
1380
1381 write_extent_buffer(c, root->fs_info->fsid,
1382 (unsigned long)btrfs_header_fsid(c),
1383 BTRFS_FSID_SIZE);
1384 btrfs_set_node_key(c, &lower_key, 0);
1385 btrfs_set_node_blockptr(c, 0, lower->start);
1386 lower_gen = btrfs_header_generation(lower);
1387 WARN_ON(lower_gen == 0);
1388
1389 btrfs_set_node_ptr_generation(c, 0, lower_gen);
1390
1391 btrfs_mark_buffer_dirty(c);
1392
1393 /* the super has an extra ref to root->node */
1394 free_extent_buffer(root->node);
1395 root->node = c;
1396 add_root_to_dirty_list(root);
1397 extent_buffer_get(c);
1398 path->nodes[level] = c;
1399 path->slots[level] = 0;
1400
1401 if (root->ref_cows && lower_gen != trans->transid) {
1402 struct btrfs_path *back_path = btrfs_alloc_path();
1403 int ret;
1404 ret = btrfs_insert_extent_backref(trans,
1405 root->fs_info->extent_root,
1406 path, lower->start,
1407 root->root_key.objectid,
1408 trans->transid, 0, 0);
1409 BUG_ON(ret);
1410 btrfs_free_path(back_path);
1411 }
1412 return 0;
1413 }
1414
1415 /*
1416 * worker function to insert a single pointer in a node.
1417 * the node should have enough room for the pointer already
1418 *
1419 * slot and level indicate where you want the key to go, and
1420 * blocknr is the block the key points to.
1421 *
1422 * returns zero on success and < 0 on any error
1423 */
1424 static int insert_ptr(struct btrfs_trans_handle *trans, struct btrfs_root
1425 *root, struct btrfs_path *path, struct btrfs_disk_key
1426 *key, u64 bytenr, int slot, int level)
1427 {
1428 struct extent_buffer *lower;
1429 int nritems;
1430
1431 BUG_ON(!path->nodes[level]);
1432 lower = path->nodes[level];
1433 nritems = btrfs_header_nritems(lower);
1434 if (slot > nritems)
1435 BUG();
1436 if (nritems == BTRFS_NODEPTRS_PER_BLOCK(root))
1437 BUG();
1438 if (slot != nritems) {
1439 memmove_extent_buffer(lower,
1440 btrfs_node_key_ptr_offset(slot + 1),
1441 btrfs_node_key_ptr_offset(slot),
1442 (nritems - slot) * sizeof(struct btrfs_key_ptr));
1443 }
1444 btrfs_set_node_key(lower, key, slot);
1445 btrfs_set_node_blockptr(lower, slot, bytenr);
1446 WARN_ON(trans->transid == 0);
1447 btrfs_set_node_ptr_generation(lower, slot, trans->transid);
1448 btrfs_set_header_nritems(lower, nritems + 1);
1449 btrfs_mark_buffer_dirty(lower);
1450 return 0;
1451 }
1452
1453 /*
1454 * split the node at the specified level in path in two.
1455 * The path is corrected to point to the appropriate node after the split
1456 *
1457 * Before splitting this tries to make some room in the node by pushing
1458 * left and right, if either one works, it returns right away.
1459 *
1460 * returns 0 on success and < 0 on failure
1461 */
1462 static int split_node(struct btrfs_trans_handle *trans, struct btrfs_root
1463 *root, struct btrfs_path *path, int level)
1464 {
1465 u64 root_gen;
1466 struct extent_buffer *c;
1467 struct extent_buffer *split;
1468 struct btrfs_disk_key disk_key;
1469 int mid;
1470 int ret;
1471 int wret;
1472 u32 c_nritems;
1473
1474 c = path->nodes[level];
1475 WARN_ON(btrfs_header_generation(c) != trans->transid);
1476 if (c == root->node) {
1477 /* trying to split the root, lets make a new one */
1478 ret = insert_new_root(trans, root, path, level + 1);
1479 if (ret)
1480 return ret;
1481 } else {
1482 ret = push_nodes_for_insert(trans, root, path, level);
1483 c = path->nodes[level];
1484 if (!ret && btrfs_header_nritems(c) <
1485 BTRFS_NODEPTRS_PER_BLOCK(root) - 1)
1486 return 0;
1487 if (ret < 0)
1488 return ret;
1489 }
1490
1491 c_nritems = btrfs_header_nritems(c);
1492 if (root->ref_cows)
1493 root_gen = trans->transid;
1494 else
1495 root_gen = 0;
1496
1497 btrfs_node_key(c, &disk_key, 0);
1498 split = __btrfs_alloc_free_block(trans, root, root->nodesize,
1499 root->root_key.objectid,
1500 root_gen,
1501 btrfs_disk_key_objectid(&disk_key),
1502 level, c->start, 0);
1503 if (IS_ERR(split))
1504 return PTR_ERR(split);
1505
1506 btrfs_set_header_flags(split, btrfs_header_flags(c));
1507 btrfs_set_header_level(split, btrfs_header_level(c));
1508 btrfs_set_header_bytenr(split, split->start);
1509 btrfs_set_header_generation(split, trans->transid);
1510 btrfs_set_header_owner(split, root->root_key.objectid);
1511 btrfs_set_header_flags(split, 0);
1512 write_extent_buffer(split, root->fs_info->fsid,
1513 (unsigned long)btrfs_header_fsid(split),
1514 BTRFS_FSID_SIZE);
1515
1516 mid = (c_nritems + 1) / 2;
1517
1518 copy_extent_buffer(split, c,
1519 btrfs_node_key_ptr_offset(0),
1520 btrfs_node_key_ptr_offset(mid),
1521 (c_nritems - mid) * sizeof(struct btrfs_key_ptr));
1522 btrfs_set_header_nritems(split, c_nritems - mid);
1523 btrfs_set_header_nritems(c, mid);
1524 ret = 0;
1525
1526 btrfs_mark_buffer_dirty(c);
1527 btrfs_mark_buffer_dirty(split);
1528
1529 btrfs_node_key(split, &disk_key, 0);
1530 wret = insert_ptr(trans, root, path, &disk_key, split->start,
1531 path->slots[level + 1] + 1,
1532 level + 1);
1533 if (wret)
1534 ret = wret;
1535
1536 if (path->slots[level] >= mid) {
1537 path->slots[level] -= mid;
1538 free_extent_buffer(c);
1539 path->nodes[level] = split;
1540 path->slots[level + 1] += 1;
1541 } else {
1542 free_extent_buffer(split);
1543 }
1544 return ret;
1545 }
1546
1547 /*
1548 * how many bytes are required to store the items in a leaf. start
1549 * and nr indicate which items in the leaf to check. This totals up the
1550 * space used both by the item structs and the item data
1551 */
1552 static int leaf_space_used(struct extent_buffer *l, int start, int nr)
1553 {
1554 int data_len;
1555 int nritems = btrfs_header_nritems(l);
1556 int end = min(nritems, start + nr) - 1;
1557
1558 if (!nr)
1559 return 0;
1560 data_len = btrfs_item_end_nr(l, start);
1561 data_len = data_len - btrfs_item_offset_nr(l, end);
1562 data_len += sizeof(struct btrfs_item) * nr;
1563 WARN_ON(data_len < 0);
1564 return data_len;
1565 }
1566
1567 /*
1568 * The space between the end of the leaf items and
1569 * the start of the leaf data. IOW, how much room
1570 * the leaf has left for both items and data
1571 */
1572 int btrfs_leaf_free_space(struct btrfs_root *root, struct extent_buffer *leaf)
1573 {
1574 int nritems = btrfs_header_nritems(leaf);
1575 int ret;
1576 ret = BTRFS_LEAF_DATA_SIZE(root) - leaf_space_used(leaf, 0, nritems);
1577 if (ret < 0) {
1578 printk("leaf free space ret %d, leaf data size %lu, used %d nritems %d\n",
1579 ret, (unsigned long) BTRFS_LEAF_DATA_SIZE(root),
1580 leaf_space_used(leaf, 0, nritems), nritems);
1581 }
1582 return ret;
1583 }
1584
1585 /*
1586 * push some data in the path leaf to the right, trying to free up at
1587 * least data_size bytes. returns zero if the push worked, nonzero otherwise
1588 *
1589 * returns 1 if the push failed because the other node didn't have enough
1590 * room, 0 if everything worked out and < 0 if there were major errors.
1591 */
1592 static int push_leaf_right(struct btrfs_trans_handle *trans, struct btrfs_root
1593 *root, struct btrfs_path *path, int data_size,
1594 int empty)
1595 {
1596 struct extent_buffer *left = path->nodes[0];
1597 struct extent_buffer *right;
1598 struct extent_buffer *upper;
1599 struct btrfs_disk_key disk_key;
1600 int slot;
1601 u32 i;
1602 int free_space;
1603 int push_space = 0;
1604 int push_items = 0;
1605 struct btrfs_item *item;
1606 u32 left_nritems;
1607 u32 nr;
1608 u32 right_nritems;
1609 u32 data_end;
1610 u32 this_item_size;
1611 int ret;
1612
1613 slot = path->slots[1];
1614 if (!path->nodes[1]) {
1615 return 1;
1616 }
1617 upper = path->nodes[1];
1618 if (slot >= btrfs_header_nritems(upper) - 1)
1619 return 1;
1620
1621 right = read_tree_block(root, btrfs_node_blockptr(upper, slot + 1),
1622 root->leafsize);
1623 free_space = btrfs_leaf_free_space(root, right);
1624 if (free_space < data_size + sizeof(struct btrfs_item)) {
1625 free_extent_buffer(right);
1626 return 1;
1627 }
1628
1629 /* cow and double check */
1630 ret = btrfs_cow_block(trans, root, right, upper,
1631 slot + 1, &right);
1632 if (ret) {
1633 free_extent_buffer(right);
1634 return 1;
1635 }
1636 free_space = btrfs_leaf_free_space(root, right);
1637 if (free_space < data_size + sizeof(struct btrfs_item)) {
1638 free_extent_buffer(right);
1639 return 1;
1640 }
1641
1642 left_nritems = btrfs_header_nritems(left);
1643 if (left_nritems == 0) {
1644 free_extent_buffer(right);
1645 return 1;
1646 }
1647
1648 if (empty)
1649 nr = 0;
1650 else
1651 nr = 1;
1652
1653 i = left_nritems - 1;
1654 while (i >= nr) {
1655 item = btrfs_item_nr(left, i);
1656
1657 if (path->slots[0] == i)
1658 push_space += data_size + sizeof(*item);
1659
1660 if (!left->map_token) {
1661 map_extent_buffer(left, (unsigned long)item,
1662 sizeof(struct btrfs_item),
1663 &left->map_token, &left->kaddr,
1664 &left->map_start, &left->map_len,
1665 KM_USER1);
1666 }
1667
1668 this_item_size = btrfs_item_size(left, item);
1669 if (this_item_size + sizeof(*item) + push_space > free_space)
1670 break;
1671 push_items++;
1672 push_space += this_item_size + sizeof(*item);
1673 if (i == 0)
1674 break;
1675 i--;
1676 }
1677 if (left->map_token) {
1678 unmap_extent_buffer(left, left->map_token, KM_USER1);
1679 left->map_token = NULL;
1680 }
1681
1682 if (push_items == 0) {
1683 free_extent_buffer(right);
1684 return 1;
1685 }
1686
1687 if (!empty && push_items == left_nritems)
1688 WARN_ON(1);
1689
1690 /* push left to right */
1691 right_nritems = btrfs_header_nritems(right);
1692
1693 push_space = btrfs_item_end_nr(left, left_nritems - push_items);
1694 push_space -= leaf_data_end(root, left);
1695
1696 /* make room in the right data area */
1697 data_end = leaf_data_end(root, right);
1698 memmove_extent_buffer(right,
1699 btrfs_leaf_data(right) + data_end - push_space,
1700 btrfs_leaf_data(right) + data_end,
1701 BTRFS_LEAF_DATA_SIZE(root) - data_end);
1702
1703 /* copy from the left data area */
1704 copy_extent_buffer(right, left, btrfs_leaf_data(right) +
1705 BTRFS_LEAF_DATA_SIZE(root) - push_space,
1706 btrfs_leaf_data(left) + leaf_data_end(root, left),
1707 push_space);
1708
1709 memmove_extent_buffer(right, btrfs_item_nr_offset(push_items),
1710 btrfs_item_nr_offset(0),
1711 right_nritems * sizeof(struct btrfs_item));
1712
1713 /* copy the items from left to right */
1714 copy_extent_buffer(right, left, btrfs_item_nr_offset(0),
1715 btrfs_item_nr_offset(left_nritems - push_items),
1716 push_items * sizeof(struct btrfs_item));
1717
1718 /* update the item pointers */
1719 right_nritems += push_items;
1720 btrfs_set_header_nritems(right, right_nritems);
1721 push_space = BTRFS_LEAF_DATA_SIZE(root);
1722 for (i = 0; i < right_nritems; i++) {
1723 item = btrfs_item_nr(right, i);
1724 if (!right->map_token) {
1725 map_extent_buffer(right, (unsigned long)item,
1726 sizeof(struct btrfs_item),
1727 &right->map_token, &right->kaddr,
1728 &right->map_start, &right->map_len,
1729 KM_USER1);
1730 }
1731 push_space -= btrfs_item_size(right, item);
1732 btrfs_set_item_offset(right, item, push_space);
1733 }
1734
1735 if (right->map_token) {
1736 unmap_extent_buffer(right, right->map_token, KM_USER1);
1737 right->map_token = NULL;
1738 }
1739 left_nritems -= push_items;
1740 btrfs_set_header_nritems(left, left_nritems);
1741
1742 if (left_nritems)
1743 btrfs_mark_buffer_dirty(left);
1744 btrfs_mark_buffer_dirty(right);
1745
1746 btrfs_item_key(right, &disk_key, 0);
1747 btrfs_set_node_key(upper, &disk_key, slot + 1);
1748 btrfs_mark_buffer_dirty(upper);
1749
1750 /* then fixup the leaf pointer in the path */
1751 if (path->slots[0] >= left_nritems) {
1752 path->slots[0] -= left_nritems;
1753 free_extent_buffer(path->nodes[0]);
1754 path->nodes[0] = right;
1755 path->slots[1] += 1;
1756 } else {
1757 free_extent_buffer(right);
1758 }
1759 return 0;
1760 }
1761 /*
1762 * push some data in the path leaf to the left, trying to free up at
1763 * least data_size bytes. returns zero if the push worked, nonzero otherwise
1764 */
1765 static int push_leaf_left(struct btrfs_trans_handle *trans, struct btrfs_root
1766 *root, struct btrfs_path *path, int data_size,
1767 int empty)
1768 {
1769 struct btrfs_disk_key disk_key;
1770 struct extent_buffer *right = path->nodes[0];
1771 struct extent_buffer *left;
1772 int slot;
1773 int i;
1774 int free_space;
1775 int push_space = 0;
1776 int push_items = 0;
1777 struct btrfs_item *item;
1778 u32 old_left_nritems;
1779 u32 right_nritems;
1780 u32 nr;
1781 int ret = 0;
1782 int wret;
1783 u32 this_item_size;
1784 u32 old_left_item_size;
1785
1786 slot = path->slots[1];
1787 if (slot == 0)
1788 return 1;
1789 if (!path->nodes[1])
1790 return 1;
1791
1792 right_nritems = btrfs_header_nritems(right);
1793 if (right_nritems == 0) {
1794 return 1;
1795 }
1796
1797 left = read_tree_block(root, btrfs_node_blockptr(path->nodes[1],
1798 slot - 1), root->leafsize);
1799 free_space = btrfs_leaf_free_space(root, left);
1800 if (free_space < data_size + sizeof(struct btrfs_item)) {
1801 free_extent_buffer(left);
1802 return 1;
1803 }
1804
1805 /* cow and double check */
1806 ret = btrfs_cow_block(trans, root, left,
1807 path->nodes[1], slot - 1, &left);
1808 if (ret) {
1809 /* we hit -ENOSPC, but it isn't fatal here */
1810 free_extent_buffer(left);
1811 return 1;
1812 }
1813
1814 free_space = btrfs_leaf_free_space(root, left);
1815 if (free_space < data_size + sizeof(struct btrfs_item)) {
1816 free_extent_buffer(left);
1817 return 1;
1818 }
1819
1820 if (empty)
1821 nr = right_nritems;
1822 else
1823 nr = right_nritems - 1;
1824
1825 for (i = 0; i < nr; i++) {
1826 item = btrfs_item_nr(right, i);
1827 if (!right->map_token) {
1828 map_extent_buffer(right, (unsigned long)item,
1829 sizeof(struct btrfs_item),
1830 &right->map_token, &right->kaddr,
1831 &right->map_start, &right->map_len,
1832 KM_USER1);
1833 }
1834
1835 if (path->slots[0] == i)
1836 push_space += data_size + sizeof(*item);
1837
1838 this_item_size = btrfs_item_size(right, item);
1839 if (this_item_size + sizeof(*item) + push_space > free_space)
1840 break;
1841
1842 push_items++;
1843 push_space += this_item_size + sizeof(*item);
1844 }
1845
1846 if (right->map_token) {
1847 unmap_extent_buffer(right, right->map_token, KM_USER1);
1848 right->map_token = NULL;
1849 }
1850
1851 if (push_items == 0) {
1852 free_extent_buffer(left);
1853 return 1;
1854 }
1855 if (!empty && push_items == btrfs_header_nritems(right))
1856 WARN_ON(1);
1857
1858 /* push data from right to left */
1859 copy_extent_buffer(left, right,
1860 btrfs_item_nr_offset(btrfs_header_nritems(left)),
1861 btrfs_item_nr_offset(0),
1862 push_items * sizeof(struct btrfs_item));
1863
1864 push_space = BTRFS_LEAF_DATA_SIZE(root) -
1865 btrfs_item_offset_nr(right, push_items -1);
1866
1867 copy_extent_buffer(left, right, btrfs_leaf_data(left) +
1868 leaf_data_end(root, left) - push_space,
1869 btrfs_leaf_data(right) +
1870 btrfs_item_offset_nr(right, push_items - 1),
1871 push_space);
1872 old_left_nritems = btrfs_header_nritems(left);
1873 BUG_ON(old_left_nritems < 0);
1874
1875 old_left_item_size = btrfs_item_offset_nr(left, old_left_nritems - 1);
1876 for (i = old_left_nritems; i < old_left_nritems + push_items; i++) {
1877 u32 ioff;
1878
1879 item = btrfs_item_nr(left, i);
1880 if (!left->map_token) {
1881 map_extent_buffer(left, (unsigned long)item,
1882 sizeof(struct btrfs_item),
1883 &left->map_token, &left->kaddr,
1884 &left->map_start, &left->map_len,
1885 KM_USER1);
1886 }
1887
1888 ioff = btrfs_item_offset(left, item);
1889 btrfs_set_item_offset(left, item,
1890 ioff - (BTRFS_LEAF_DATA_SIZE(root) - old_left_item_size));
1891 }
1892 btrfs_set_header_nritems(left, old_left_nritems + push_items);
1893 if (left->map_token) {
1894 unmap_extent_buffer(left, left->map_token, KM_USER1);
1895 left->map_token = NULL;
1896 }
1897
1898 /* fixup right node */
1899 if (push_items > right_nritems) {
1900 printk("push items %d nr %u\n", push_items, right_nritems);
1901 WARN_ON(1);
1902 }
1903
1904 if (push_items < right_nritems) {
1905 push_space = btrfs_item_offset_nr(right, push_items - 1) -
1906 leaf_data_end(root, right);
1907 memmove_extent_buffer(right, btrfs_leaf_data(right) +
1908 BTRFS_LEAF_DATA_SIZE(root) - push_space,
1909 btrfs_leaf_data(right) +
1910 leaf_data_end(root, right), push_space);
1911
1912 memmove_extent_buffer(right, btrfs_item_nr_offset(0),
1913 btrfs_item_nr_offset(push_items),
1914 (btrfs_header_nritems(right) - push_items) *
1915 sizeof(struct btrfs_item));
1916 }
1917 right_nritems -= push_items;
1918 btrfs_set_header_nritems(right, right_nritems);
1919 push_space = BTRFS_LEAF_DATA_SIZE(root);
1920 for (i = 0; i < right_nritems; i++) {
1921 item = btrfs_item_nr(right, i);
1922
1923 if (!right->map_token) {
1924 map_extent_buffer(right, (unsigned long)item,
1925 sizeof(struct btrfs_item),
1926 &right->map_token, &right->kaddr,
1927 &right->map_start, &right->map_len,
1928 KM_USER1);
1929 }
1930
1931 push_space = push_space - btrfs_item_size(right, item);
1932 btrfs_set_item_offset(right, item, push_space);
1933 }
1934 if (right->map_token) {
1935 unmap_extent_buffer(right, right->map_token, KM_USER1);
1936 right->map_token = NULL;
1937 }
1938
1939 btrfs_mark_buffer_dirty(left);
1940 if (right_nritems)
1941 btrfs_mark_buffer_dirty(right);
1942
1943 btrfs_item_key(right, &disk_key, 0);
1944 wret = fixup_low_keys(trans, root, path, &disk_key, 1);
1945 if (wret)
1946 ret = wret;
1947
1948 /* then fixup the leaf pointer in the path */
1949 if (path->slots[0] < push_items) {
1950 path->slots[0] += old_left_nritems;
1951 free_extent_buffer(path->nodes[0]);
1952 path->nodes[0] = left;
1953 path->slots[1] -= 1;
1954 } else {
1955 free_extent_buffer(left);
1956 path->slots[0] -= push_items;
1957 }
1958 BUG_ON(path->slots[0] < 0);
1959 return ret;
1960 }
1961
1962 /*
1963 * split the path's leaf in two, making sure there is at least data_size
1964 * available for the resulting leaf level of the path.
1965 *
1966 * returns 0 if all went well and < 0 on failure.
1967 */
1968 static int split_leaf(struct btrfs_trans_handle *trans, struct btrfs_root
1969 *root, struct btrfs_key *ins_key,
1970 struct btrfs_path *path, int data_size, int extend)
1971 {
1972 u64 root_gen;
1973 struct extent_buffer *l;
1974 u32 nritems;
1975 int mid;
1976 int slot;
1977 struct extent_buffer *right;
1978 int space_needed = data_size + sizeof(struct btrfs_item);
1979 int data_copy_size;
1980 int rt_data_off;
1981 int i;
1982 int ret = 0;
1983 int wret;
1984 int double_split;
1985 int num_doubles = 0;
1986 struct btrfs_disk_key disk_key;
1987
1988 if (extend)
1989 space_needed = data_size;
1990
1991 if (root->ref_cows)
1992 root_gen = trans->transid;
1993 else
1994 root_gen = 0;
1995
1996 /* first try to make some room by pushing left and right */
1997 if (ins_key->type != BTRFS_DIR_ITEM_KEY) {
1998 wret = push_leaf_right(trans, root, path, data_size, 0);
1999 if (wret < 0) {
2000 return wret;
2001 }
2002 if (wret) {
2003 wret = push_leaf_left(trans, root, path, data_size, 0);
2004 if (wret < 0)
2005 return wret;
2006 }
2007 l = path->nodes[0];
2008
2009 /* did the pushes work? */
2010 if (btrfs_leaf_free_space(root, l) >= space_needed)
2011 return 0;
2012 }
2013
2014 if (!path->nodes[1]) {
2015 ret = insert_new_root(trans, root, path, 1);
2016 if (ret)
2017 return ret;
2018 }
2019 again:
2020 double_split = 0;
2021 l = path->nodes[0];
2022 slot = path->slots[0];
2023 nritems = btrfs_header_nritems(l);
2024 mid = (nritems + 1)/ 2;
2025
2026 btrfs_item_key(l, &disk_key, 0);
2027
2028 right = __btrfs_alloc_free_block(trans, root, root->leafsize,
2029 root->root_key.objectid,
2030 root_gen, disk_key.objectid, 0,
2031 l->start, 0);
2032 if (IS_ERR(right)) {
2033 BUG_ON(1);
2034 return PTR_ERR(right);
2035 }
2036
2037 memset_extent_buffer(right, 0, 0, sizeof(struct btrfs_header));
2038 btrfs_set_header_bytenr(right, right->start);
2039 btrfs_set_header_generation(right, trans->transid);
2040 btrfs_set_header_owner(right, root->root_key.objectid);
2041 btrfs_set_header_level(right, 0);
2042 write_extent_buffer(right, root->fs_info->fsid,
2043 (unsigned long)btrfs_header_fsid(right),
2044 BTRFS_FSID_SIZE);
2045 if (mid <= slot) {
2046 if (nritems == 1 ||
2047 leaf_space_used(l, mid, nritems - mid) + space_needed >
2048 BTRFS_LEAF_DATA_SIZE(root)) {
2049 if (slot >= nritems) {
2050 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2051 btrfs_set_header_nritems(right, 0);
2052 wret = insert_ptr(trans, root, path,
2053 &disk_key, right->start,
2054 path->slots[1] + 1, 1);
2055 if (wret)
2056 ret = wret;
2057 free_extent_buffer(path->nodes[0]);
2058 path->nodes[0] = right;
2059 path->slots[0] = 0;
2060 path->slots[1] += 1;
2061 btrfs_mark_buffer_dirty(right);
2062 return ret;
2063 }
2064 mid = slot;
2065 if (mid != nritems &&
2066 leaf_space_used(l, mid, nritems - mid) +
2067 space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
2068 double_split = 1;
2069 }
2070 }
2071 } else {
2072 if (leaf_space_used(l, 0, mid + 1) + space_needed >
2073 BTRFS_LEAF_DATA_SIZE(root)) {
2074 if (!extend && slot == 0) {
2075 btrfs_cpu_key_to_disk(&disk_key, ins_key);
2076 btrfs_set_header_nritems(right, 0);
2077 wret = insert_ptr(trans, root, path,
2078 &disk_key,
2079 right->start,
2080 path->slots[1], 1);
2081 if (wret)
2082 ret = wret;
2083 free_extent_buffer(path->nodes[0]);
2084 path->nodes[0] = right;
2085 path->slots[0] = 0;
2086 if (path->slots[1] == 0) {
2087 wret = fixup_low_keys(trans, root,
2088 path, &disk_key, 1);
2089 if (wret)
2090 ret = wret;
2091 }
2092 btrfs_mark_buffer_dirty(right);
2093 return ret;
2094 } else if (extend && slot == 0) {
2095 mid = 1;
2096 } else {
2097 mid = slot;
2098 if (mid != nritems &&
2099 leaf_space_used(l, mid, nritems - mid) +
2100 space_needed > BTRFS_LEAF_DATA_SIZE(root)) {
2101 double_split = 1;
2102 }
2103 }
2104 }
2105 }
2106 nritems = nritems - mid;
2107 btrfs_set_header_nritems(right, nritems);
2108 data_copy_size = btrfs_item_end_nr(l, mid) - leaf_data_end(root, l);
2109
2110 copy_extent_buffer(right, l, btrfs_item_nr_offset(0),
2111 btrfs_item_nr_offset(mid),
2112 nritems * sizeof(struct btrfs_item));
2113
2114 copy_extent_buffer(right, l,
2115 btrfs_leaf_data(right) + BTRFS_LEAF_DATA_SIZE(root) -
2116 data_copy_size, btrfs_leaf_data(l) +
2117 leaf_data_end(root, l), data_copy_size);
2118
2119 rt_data_off = BTRFS_LEAF_DATA_SIZE(root) -
2120 btrfs_item_end_nr(l, mid);
2121
2122 for (i = 0; i < nritems; i++) {
2123 struct btrfs_item *item = btrfs_item_nr(right, i);
2124 u32 ioff;
2125
2126 if (!right->map_token) {
2127 map_extent_buffer(right, (unsigned long)item,
2128 sizeof(struct btrfs_item),
2129 &right->map_token, &right->kaddr,
2130 &right->map_start, &right->map_len,
2131 KM_USER1);
2132 }
2133
2134 ioff = btrfs_item_offset(right, item);
2135 btrfs_set_item_offset(right, item, ioff + rt_data_off);
2136 }
2137
2138 if (right->map_token) {
2139 unmap_extent_buffer(right, right->map_token, KM_USER1);
2140 right->map_token = NULL;
2141 }
2142
2143 btrfs_set_header_nritems(l, mid);
2144 ret = 0;
2145 btrfs_item_key(right, &disk_key, 0);
2146 wret = insert_ptr(trans, root, path, &disk_key, right->start,
2147 path->slots[1] + 1, 1);
2148 if (wret)
2149 ret = wret;
2150
2151 btrfs_mark_buffer_dirty(right);
2152 btrfs_mark_buffer_dirty(l);
2153 BUG_ON(path->slots[0] != slot);
2154
2155 if (mid <= slot) {
2156 free_extent_buffer(path->nodes[0]);
2157 path->nodes[0] = right;
2158 path->slots[0] -= mid;
2159 path->slots[1] += 1;
2160 } else
2161 free_extent_buffer(right);
2162
2163 BUG_ON(path->slots[0] < 0);
2164
2165 if (double_split) {
2166 BUG_ON(num_doubles != 0);
2167 num_doubles++;
2168 goto again;
2169 }
2170 return ret;
2171 }
2172
2173 int btrfs_truncate_item(struct btrfs_trans_handle *trans,
2174 struct btrfs_root *root,
2175 struct btrfs_path *path,
2176 u32 new_size, int from_end)
2177 {
2178 int ret = 0;
2179 int slot;
2180 int slot_orig;
2181 struct extent_buffer *leaf;
2182 struct btrfs_item *item;
2183 u32 nritems;
2184 unsigned int data_end;
2185 unsigned int old_data_start;
2186 unsigned int old_size;
2187 unsigned int size_diff;
2188 int i;
2189
2190 slot_orig = path->slots[0];
2191 leaf = path->nodes[0];
2192 slot = path->slots[0];
2193
2194 old_size = btrfs_item_size_nr(leaf, slot);
2195 if (old_size == new_size)
2196 return 0;
2197
2198 nritems = btrfs_header_nritems(leaf);
2199 data_end = leaf_data_end(root, leaf);
2200
2201 old_data_start = btrfs_item_offset_nr(leaf, slot);
2202
2203 size_diff = old_size - new_size;
2204
2205 BUG_ON(slot < 0);
2206 BUG_ON(slot >= nritems);
2207
2208 /*
2209 * item0..itemN ... dataN.offset..dataN.size .. data0.size
2210 */
2211 /* first correct the data pointers */
2212 for (i = slot; i < nritems; i++) {
2213 u32 ioff;
2214 item = btrfs_item_nr(leaf, i);
2215
2216 if (!leaf->map_token) {
2217 map_extent_buffer(leaf, (unsigned long)item,
2218 sizeof(struct btrfs_item),
2219 &leaf->map_token, &leaf->kaddr,
2220 &leaf->map_start, &leaf->map_len,
2221 KM_USER1);
2222 }
2223
2224 ioff = btrfs_item_offset(leaf, item);
2225 btrfs_set_item_offset(leaf, item, ioff + size_diff);
2226 }
2227
2228 if (leaf->map_token) {
2229 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2230 leaf->map_token = NULL;
2231 }
2232
2233 /* shift the data */
2234 if (from_end) {
2235 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2236 data_end + size_diff, btrfs_leaf_data(leaf) +
2237 data_end, old_data_start + new_size - data_end);
2238 } else {
2239 struct btrfs_disk_key disk_key;
2240 u64 offset;
2241
2242 btrfs_item_key(leaf, &disk_key, slot);
2243
2244 if (btrfs_disk_key_type(&disk_key) == BTRFS_EXTENT_DATA_KEY) {
2245 unsigned long ptr;
2246 struct btrfs_file_extent_item *fi;
2247
2248 fi = btrfs_item_ptr(leaf, slot,
2249 struct btrfs_file_extent_item);
2250 fi = (struct btrfs_file_extent_item *)(
2251 (unsigned long)fi - size_diff);
2252
2253 if (btrfs_file_extent_type(leaf, fi) ==
2254 BTRFS_FILE_EXTENT_INLINE) {
2255 ptr = btrfs_item_ptr_offset(leaf, slot);
2256 memmove_extent_buffer(leaf, ptr,
2257 (unsigned long)fi,
2258 offsetof(struct btrfs_file_extent_item,
2259 disk_bytenr));
2260 }
2261 }
2262
2263 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2264 data_end + size_diff, btrfs_leaf_data(leaf) +
2265 data_end, old_data_start - data_end);
2266
2267 offset = btrfs_disk_key_offset(&disk_key);
2268 btrfs_set_disk_key_offset(&disk_key, offset + size_diff);
2269 btrfs_set_item_key(leaf, &disk_key, slot);
2270 if (slot == 0)
2271 fixup_low_keys(trans, root, path, &disk_key, 1);
2272 }
2273
2274 item = btrfs_item_nr(leaf, slot);
2275 btrfs_set_item_size(leaf, item, new_size);
2276 btrfs_mark_buffer_dirty(leaf);
2277
2278 ret = 0;
2279 if (btrfs_leaf_free_space(root, leaf) < 0) {
2280 btrfs_print_leaf(root, leaf);
2281 BUG();
2282 }
2283 return ret;
2284 }
2285
2286 int btrfs_extend_item(struct btrfs_trans_handle *trans,
2287 struct btrfs_root *root, struct btrfs_path *path,
2288 u32 data_size)
2289 {
2290 int ret = 0;
2291 int slot;
2292 int slot_orig;
2293 struct extent_buffer *leaf;
2294 struct btrfs_item *item;
2295 u32 nritems;
2296 unsigned int data_end;
2297 unsigned int old_data;
2298 unsigned int old_size;
2299 int i;
2300
2301 slot_orig = path->slots[0];
2302 leaf = path->nodes[0];
2303
2304 nritems = btrfs_header_nritems(leaf);
2305 data_end = leaf_data_end(root, leaf);
2306
2307 if (btrfs_leaf_free_space(root, leaf) < data_size) {
2308 btrfs_print_leaf(root, leaf);
2309 BUG();
2310 }
2311 slot = path->slots[0];
2312 old_data = btrfs_item_end_nr(leaf, slot);
2313
2314 BUG_ON(slot < 0);
2315 if (slot >= nritems) {
2316 btrfs_print_leaf(root, leaf);
2317 printk("slot %d too large, nritems %d\n", slot, nritems);
2318 BUG_ON(1);
2319 }
2320
2321 /*
2322 * item0..itemN ... dataN.offset..dataN.size .. data0.size
2323 */
2324 /* first correct the data pointers */
2325 for (i = slot; i < nritems; i++) {
2326 u32 ioff;
2327 item = btrfs_item_nr(leaf, i);
2328
2329 if (!leaf->map_token) {
2330 map_extent_buffer(leaf, (unsigned long)item,
2331 sizeof(struct btrfs_item),
2332 &leaf->map_token, &leaf->kaddr,
2333 &leaf->map_start, &leaf->map_len,
2334 KM_USER1);
2335 }
2336 ioff = btrfs_item_offset(leaf, item);
2337 btrfs_set_item_offset(leaf, item, ioff - data_size);
2338 }
2339
2340 if (leaf->map_token) {
2341 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2342 leaf->map_token = NULL;
2343 }
2344
2345 /* shift the data */
2346 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2347 data_end - data_size, btrfs_leaf_data(leaf) +
2348 data_end, old_data - data_end);
2349
2350 data_end = old_data;
2351 old_size = btrfs_item_size_nr(leaf, slot);
2352 item = btrfs_item_nr(leaf, slot);
2353 btrfs_set_item_size(leaf, item, old_size + data_size);
2354 btrfs_mark_buffer_dirty(leaf);
2355
2356 ret = 0;
2357 if (btrfs_leaf_free_space(root, leaf) < 0) {
2358 btrfs_print_leaf(root, leaf);
2359 BUG();
2360 }
2361 return ret;
2362 }
2363
2364 /*
2365 * Given a key and some data, insert an item into the tree.
2366 * This does all the path init required, making room in the tree if needed.
2367 */
2368 int btrfs_insert_empty_items(struct btrfs_trans_handle *trans,
2369 struct btrfs_root *root,
2370 struct btrfs_path *path,
2371 struct btrfs_key *cpu_key, u32 *data_size,
2372 int nr)
2373 {
2374 struct extent_buffer *leaf;
2375 struct btrfs_item *item;
2376 int ret = 0;
2377 int slot;
2378 int slot_orig;
2379 int i;
2380 u32 nritems;
2381 u32 total_size = 0;
2382 u32 total_data = 0;
2383 unsigned int data_end;
2384 struct btrfs_disk_key disk_key;
2385
2386 for (i = 0; i < nr; i++) {
2387 total_data += data_size[i];
2388 }
2389
2390 /* create a root if there isn't one */
2391 if (!root->node)
2392 BUG();
2393
2394 total_size = total_data + (nr - 1) * sizeof(struct btrfs_item);
2395 ret = btrfs_search_slot(trans, root, cpu_key, path, total_size, 1);
2396 if (ret == 0) {
2397 return -EEXIST;
2398 }
2399 if (ret < 0)
2400 goto out;
2401
2402 slot_orig = path->slots[0];
2403 leaf = path->nodes[0];
2404
2405 nritems = btrfs_header_nritems(leaf);
2406 data_end = leaf_data_end(root, leaf);
2407
2408 if (btrfs_leaf_free_space(root, leaf) <
2409 sizeof(struct btrfs_item) + total_size) {
2410 btrfs_print_leaf(root, leaf);
2411 printk("not enough freespace need %u have %d\n",
2412 total_size, btrfs_leaf_free_space(root, leaf));
2413 BUG();
2414 }
2415
2416 slot = path->slots[0];
2417 BUG_ON(slot < 0);
2418
2419 if (slot != nritems) {
2420 int i;
2421 unsigned int old_data = btrfs_item_end_nr(leaf, slot);
2422
2423 if (old_data < data_end) {
2424 btrfs_print_leaf(root, leaf);
2425 printk("slot %d old_data %d data_end %d\n",
2426 slot, old_data, data_end);
2427 BUG_ON(1);
2428 }
2429 /*
2430 * item0..itemN ... dataN.offset..dataN.size .. data0.size
2431 */
2432 /* first correct the data pointers */
2433 WARN_ON(leaf->map_token);
2434 for (i = slot; i < nritems; i++) {
2435 u32 ioff;
2436
2437 item = btrfs_item_nr(leaf, i);
2438 if (!leaf->map_token) {
2439 map_extent_buffer(leaf, (unsigned long)item,
2440 sizeof(struct btrfs_item),
2441 &leaf->map_token, &leaf->kaddr,
2442 &leaf->map_start, &leaf->map_len,
2443 KM_USER1);
2444 }
2445
2446 ioff = btrfs_item_offset(leaf, item);
2447 btrfs_set_item_offset(leaf, item, ioff - total_data);
2448 }
2449 if (leaf->map_token) {
2450 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2451 leaf->map_token = NULL;
2452 }
2453
2454 /* shift the items */
2455 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot + nr),
2456 btrfs_item_nr_offset(slot),
2457 (nritems - slot) * sizeof(struct btrfs_item));
2458
2459 /* shift the data */
2460 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2461 data_end - total_data, btrfs_leaf_data(leaf) +
2462 data_end, old_data - data_end);
2463 data_end = old_data;
2464 }
2465
2466 /* setup the item for the new data */
2467 for (i = 0; i < nr; i++) {
2468 btrfs_cpu_key_to_disk(&disk_key, cpu_key + i);
2469 btrfs_set_item_key(leaf, &disk_key, slot + i);
2470 item = btrfs_item_nr(leaf, slot + i);
2471 btrfs_set_item_offset(leaf, item, data_end - data_size[i]);
2472 data_end -= data_size[i];
2473 btrfs_set_item_size(leaf, item, data_size[i]);
2474 }
2475 btrfs_set_header_nritems(leaf, nritems + nr);
2476 btrfs_mark_buffer_dirty(leaf);
2477
2478 ret = 0;
2479 if (slot == 0) {
2480 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
2481 ret = fixup_low_keys(trans, root, path, &disk_key, 1);
2482 }
2483
2484 if (btrfs_leaf_free_space(root, leaf) < 0) {
2485 btrfs_print_leaf(root, leaf);
2486 BUG();
2487 }
2488
2489 out:
2490 return ret;
2491 }
2492
2493 /*
2494 * Given a key and some data, insert an item into the tree.
2495 * This does all the path init required, making room in the tree if needed.
2496 */
2497 int btrfs_insert_item(struct btrfs_trans_handle *trans, struct btrfs_root
2498 *root, struct btrfs_key *cpu_key, void *data, u32
2499 data_size)
2500 {
2501 int ret = 0;
2502 struct btrfs_path *path;
2503 struct extent_buffer *leaf;
2504 unsigned long ptr;
2505
2506 path = btrfs_alloc_path();
2507 BUG_ON(!path);
2508 ret = btrfs_insert_empty_item(trans, root, path, cpu_key, data_size);
2509 if (!ret) {
2510 leaf = path->nodes[0];
2511 ptr = btrfs_item_ptr_offset(leaf, path->slots[0]);
2512 write_extent_buffer(leaf, data, ptr, data_size);
2513 btrfs_mark_buffer_dirty(leaf);
2514 }
2515 btrfs_free_path(path);
2516 return ret;
2517 }
2518
2519 /*
2520 * delete the pointer from a given node.
2521 *
2522 * If the delete empties a node, the node is removed from the tree,
2523 * continuing all the way the root if required. The root is converted into
2524 * a leaf if all the nodes are emptied.
2525 */
2526 static int del_ptr(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2527 struct btrfs_path *path, int level, int slot)
2528 {
2529 struct extent_buffer *parent = path->nodes[level];
2530 u32 nritems;
2531 int ret = 0;
2532 int wret;
2533
2534 nritems = btrfs_header_nritems(parent);
2535 if (slot != nritems -1) {
2536 memmove_extent_buffer(parent,
2537 btrfs_node_key_ptr_offset(slot),
2538 btrfs_node_key_ptr_offset(slot + 1),
2539 sizeof(struct btrfs_key_ptr) *
2540 (nritems - slot - 1));
2541 }
2542 nritems--;
2543 btrfs_set_header_nritems(parent, nritems);
2544 if (nritems == 0 && parent == root->node) {
2545 BUG_ON(btrfs_header_level(root->node) != 1);
2546 /* just turn the root into a leaf and break */
2547 btrfs_set_header_level(root->node, 0);
2548 } else if (slot == 0) {
2549 struct btrfs_disk_key disk_key;
2550
2551 btrfs_node_key(parent, &disk_key, 0);
2552 wret = fixup_low_keys(trans, root, path, &disk_key, level + 1);
2553 if (wret)
2554 ret = wret;
2555 }
2556 btrfs_mark_buffer_dirty(parent);
2557 return ret;
2558 }
2559
2560 /*
2561 * delete the item at the leaf level in path. If that empties
2562 * the leaf, remove it from the tree
2563 */
2564 int btrfs_del_items(struct btrfs_trans_handle *trans, struct btrfs_root *root,
2565 struct btrfs_path *path, int slot, int nr)
2566 {
2567 struct extent_buffer *leaf;
2568 struct btrfs_item *item;
2569 int last_off;
2570 int dsize = 0;
2571 int ret = 0;
2572 int wret;
2573 int i;
2574 u32 nritems;
2575
2576 leaf = path->nodes[0];
2577 last_off = btrfs_item_offset_nr(leaf, slot + nr - 1);
2578
2579 for (i = 0; i < nr; i++)
2580 dsize += btrfs_item_size_nr(leaf, slot + i);
2581
2582 nritems = btrfs_header_nritems(leaf);
2583
2584 if (slot + nr != nritems) {
2585 int i;
2586 int data_end = leaf_data_end(root, leaf);
2587
2588 memmove_extent_buffer(leaf, btrfs_leaf_data(leaf) +
2589 data_end + dsize,
2590 btrfs_leaf_data(leaf) + data_end,
2591 last_off - data_end);
2592
2593 for (i = slot + nr; i < nritems; i++) {
2594 u32 ioff;
2595
2596 item = btrfs_item_nr(leaf, i);
2597 if (!leaf->map_token) {
2598 map_extent_buffer(leaf, (unsigned long)item,
2599 sizeof(struct btrfs_item),
2600 &leaf->map_token, &leaf->kaddr,
2601 &leaf->map_start, &leaf->map_len,
2602 KM_USER1);
2603 }
2604 ioff = btrfs_item_offset(leaf, item);
2605 btrfs_set_item_offset(leaf, item, ioff + dsize);
2606 }
2607
2608 if (leaf->map_token) {
2609 unmap_extent_buffer(leaf, leaf->map_token, KM_USER1);
2610 leaf->map_token = NULL;
2611 }
2612
2613 memmove_extent_buffer(leaf, btrfs_item_nr_offset(slot),
2614 btrfs_item_nr_offset(slot + nr),
2615 sizeof(struct btrfs_item) *
2616 (nritems - slot - nr));
2617 }
2618 btrfs_set_header_nritems(leaf, nritems - nr);
2619 nritems -= nr;
2620
2621 /* delete the leaf if we've emptied it */
2622 if (nritems == 0) {
2623 if (leaf == root->node) {
2624 btrfs_set_header_level(leaf, 0);
2625 } else {
2626 u64 root_gen = btrfs_header_generation(path->nodes[1]);
2627 clean_tree_block(trans, root, leaf);
2628 wait_on_tree_block_writeback(root, leaf);
2629 wret = del_ptr(trans, root, path, 1, path->slots[1]);
2630 if (wret)
2631 ret = wret;
2632 wret = btrfs_free_extent(trans, root,
2633 leaf->start, leaf->len,
2634 btrfs_header_owner(path->nodes[1]),
2635 root_gen, 0, 0, 1);
2636 if (wret)
2637 ret = wret;
2638 }
2639 } else {
2640 int used = leaf_space_used(leaf, 0, nritems);
2641 if (slot == 0) {
2642 struct btrfs_disk_key disk_key;
2643
2644 btrfs_item_key(leaf, &disk_key, 0);
2645 wret = fixup_low_keys(trans, root, path,
2646 &disk_key, 1);
2647 if (wret)
2648 ret = wret;
2649 }
2650
2651 /* delete the leaf if it is mostly empty */
2652 if (used < BTRFS_LEAF_DATA_SIZE(root) / 4) {
2653 /* push_leaf_left fixes the path.
2654 * make sure the path still points to our leaf
2655 * for possible call to del_ptr below
2656 */
2657 slot = path->slots[1];
2658 extent_buffer_get(leaf);
2659
2660 wret = push_leaf_left(trans, root, path, 1, 1);
2661 if (wret < 0 && wret != -ENOSPC)
2662 ret = wret;
2663
2664 if (path->nodes[0] == leaf &&
2665 btrfs_header_nritems(leaf)) {
2666 wret = push_leaf_right(trans, root, path, 1, 1);
2667 if (wret < 0 && wret != -ENOSPC)
2668 ret = wret;
2669 }
2670
2671 if (btrfs_header_nritems(leaf) == 0) {
2672 u64 root_gen;
2673 u64 bytenr = leaf->start;
2674 u32 blocksize = leaf->len;
2675
2676 root_gen = btrfs_header_generation(
2677 path->nodes[1]);
2678
2679 clean_tree_block(trans, root, leaf);
2680 wait_on_tree_block_writeback(root, leaf);
2681
2682 wret = del_ptr(trans, root, path, 1, slot);
2683 if (wret)
2684 ret = wret;
2685
2686 free_extent_buffer(leaf);
2687 wret = btrfs_free_extent(trans, root, bytenr,
2688 blocksize,
2689 btrfs_header_owner(path->nodes[1]),
2690 root_gen, 0, 0, 1);
2691 if (wret)
2692 ret = wret;
2693 } else {
2694 btrfs_mark_buffer_dirty(leaf);
2695 free_extent_buffer(leaf);
2696 }
2697 } else {
2698 btrfs_mark_buffer_dirty(leaf);
2699 }
2700 }
2701 return ret;
2702 }
2703
2704 /*
2705 * walk up the tree as far as required to find the previous leaf.
2706 * returns 0 if it found something or 1 if there are no lesser leaves.
2707 * returns < 0 on io errors.
2708 */
2709 int btrfs_prev_leaf(struct btrfs_root *root, struct btrfs_path *path)
2710 {
2711 u64 bytenr;
2712 int slot;
2713 int level = 1;
2714 struct extent_buffer *c;
2715 struct extent_buffer *next = NULL;
2716
2717 while(level < BTRFS_MAX_LEVEL) {
2718 if (!path->nodes[level])
2719 return 1;
2720
2721 slot = path->slots[level];
2722 c = path->nodes[level];
2723 if (slot == 0) {
2724 level++;
2725 if (level == BTRFS_MAX_LEVEL)
2726 return 1;
2727 continue;
2728 }
2729 slot--;
2730
2731 bytenr = btrfs_node_blockptr(c, slot);
2732 if (next)
2733 free_extent_buffer(next);
2734
2735 next = read_tree_block(root, bytenr,
2736 btrfs_level_size(root, level - 1));
2737 break;
2738 }
2739 path->slots[level] = slot;
2740 while(1) {
2741 level--;
2742 c = path->nodes[level];
2743 free_extent_buffer(c);
2744 slot = btrfs_header_nritems(next);
2745 if (slot != 0)
2746 slot--;
2747 path->nodes[level] = next;
2748 path->slots[level] = slot;
2749 if (!level)
2750 break;
2751 next = read_tree_block(root, btrfs_node_blockptr(next, slot),
2752 btrfs_level_size(root, level - 1));
2753 }
2754 return 0;
2755 }
2756
2757 /*
2758 * walk up the tree as far as required to find the next leaf.
2759 * returns 0 if it found something or 1 if there are no greater leaves.
2760 * returns < 0 on io errors.
2761 */
2762 int btrfs_next_leaf(struct btrfs_root *root, struct btrfs_path *path)
2763 {
2764 int slot;
2765 int level = 1;
2766 u64 bytenr;
2767 struct extent_buffer *c;
2768 struct extent_buffer *next = NULL;
2769
2770 while(level < BTRFS_MAX_LEVEL) {
2771 if (!path->nodes[level])
2772 return 1;
2773
2774 slot = path->slots[level] + 1;
2775 c = path->nodes[level];
2776 if (slot >= btrfs_header_nritems(c)) {
2777 level++;
2778 if (level == BTRFS_MAX_LEVEL)
2779 return 1;
2780 continue;
2781 }
2782
2783 bytenr = btrfs_node_blockptr(c, slot);
2784 if (next)
2785 free_extent_buffer(next);
2786
2787 if (path->reada)
2788 reada_for_search(root, path, level, slot, 0);
2789
2790 next = read_tree_block(root, bytenr,
2791 btrfs_level_size(root, level -1));
2792 break;
2793 }
2794 path->slots[level] = slot;
2795 while(1) {
2796 level--;
2797 c = path->nodes[level];
2798 free_extent_buffer(c);
2799 path->nodes[level] = next;
2800 path->slots[level] = 0;
2801 if (!level)
2802 break;
2803 if (path->reada)
2804 reada_for_search(root, path, level, 0, 0);
2805 next = read_tree_block(root, btrfs_node_blockptr(next, 0),
2806 btrfs_level_size(root, level - 1));
2807 }
2808 return 0;
2809 }
2810
2811 int btrfs_previous_item(struct btrfs_root *root,
2812 struct btrfs_path *path, u64 min_objectid,
2813 int type)
2814 {
2815 struct btrfs_key found_key;
2816 struct extent_buffer *leaf;
2817 int ret;
2818
2819 while(1) {
2820 if (path->slots[0] == 0) {
2821 ret = btrfs_prev_leaf(root, path);
2822 if (ret != 0)
2823 return ret;
2824 } else {
2825 path->slots[0]--;
2826 }
2827 leaf = path->nodes[0];
2828 btrfs_item_key_to_cpu(leaf, &found_key, path->slots[0]);
2829 if (found_key.type == type)
2830 return 0;
2831 }
2832 return 1;
2833 }
2834
Linux kernel - Deliverables
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