3 #include "kerncompat.h"
4 #include "radix-tree.h"
7 #include "print-tree.h"
9 static int split_node(struct ctree_root *root, struct ctree_path *path,
11 static int split_leaf(struct ctree_root *root, struct ctree_path *path,
13 static int push_node_left(struct ctree_root *root, struct tree_buffer *dst,
14 struct tree_buffer *src);
15 static int balance_node_right(struct ctree_root *root,
16 struct tree_buffer *dst_buf,
17 struct tree_buffer *src_buf);
18 static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
21 inline void init_path(struct ctree_path *p)
23 memset(p, 0, sizeof(*p));
26 void release_path(struct ctree_root *root, struct ctree_path *p)
29 for (i = 0; i < MAX_LEVEL; i++) {
32 tree_block_release(root, p->nodes[i]);
34 memset(p, 0, sizeof(*p));
37 int btrfs_cow_block(struct ctree_root *root,
38 struct tree_buffer *buf,
39 struct tree_buffer *parent,
41 struct tree_buffer **cow_ret)
43 struct tree_buffer *cow;
45 if (!list_empty(&buf->dirty)) {
49 cow = alloc_free_block(root);
50 memcpy(&cow->node, &buf->node, sizeof(buf->node));
51 btrfs_set_header_blocknr(&cow->node.header, cow->blocknr);
53 btrfs_inc_ref(root, buf);
54 if (buf == root->node) {
57 if (buf != root->commit_root)
58 free_extent(root, buf->blocknr, 1);
59 tree_block_release(root, buf);
61 parent->node.blockptrs[parent_slot] = cow->blocknr;
62 BUG_ON(list_empty(&parent->dirty));
63 free_extent(root, buf->blocknr, 1);
65 tree_block_release(root, buf);
70 * The leaf data grows from end-to-front in the node.
71 * this returns the address of the start of the last item,
72 * which is the stop of the leaf data stack
74 static inline unsigned int leaf_data_end(struct leaf *leaf)
76 u32 nr = btrfs_header_nritems(&leaf->header);
78 return sizeof(leaf->data);
79 return leaf->items[nr-1].offset;
83 * The space between the end of the leaf items and
84 * the start of the leaf data. IOW, how much room
85 * the leaf has left for both items and data
87 int leaf_free_space(struct leaf *leaf)
89 int data_end = leaf_data_end(leaf);
90 int nritems = btrfs_header_nritems(&leaf->header);
91 char *items_end = (char *)(leaf->items + nritems + 1);
92 return (char *)(leaf->data + data_end) - (char *)items_end;
96 * compare two keys in a memcmp fashion
98 int comp_keys(struct btrfs_disk_key *disk, struct btrfs_key *k2)
102 btrfs_disk_key_to_cpu(&k1, disk);
104 if (k1.objectid > k2->objectid)
106 if (k1.objectid < k2->objectid)
108 if (k1.flags > k2->flags)
110 if (k1.flags < k2->flags)
112 if (k1.offset > k2->offset)
114 if (k1.offset < k2->offset)
119 int check_node(struct ctree_path *path, int level)
122 struct node *parent = NULL;
123 struct node *node = &path->nodes[level]->node;
125 u32 nritems = btrfs_header_nritems(&node->header);
127 if (path->nodes[level + 1])
128 parent = &path->nodes[level + 1]->node;
129 parent_slot = path->slots[level + 1];
130 BUG_ON(nritems == 0);
132 struct btrfs_disk_key *parent_key;
133 parent_key = &parent->keys[parent_slot];
134 BUG_ON(memcmp(parent_key, node->keys,
135 sizeof(struct btrfs_disk_key)));
136 BUG_ON(parent->blockptrs[parent_slot] !=
137 btrfs_header_blocknr(&node->header));
139 BUG_ON(nritems > NODEPTRS_PER_BLOCK);
140 for (i = 0; nritems > 1 && i < nritems - 2; i++) {
141 struct btrfs_key cpukey;
142 btrfs_disk_key_to_cpu(&cpukey, &node->keys[i + 1]);
143 BUG_ON(comp_keys(&node->keys[i], &cpukey) >= 0);
148 int check_leaf(struct ctree_path *path, int level)
151 struct leaf *leaf = &path->nodes[level]->leaf;
152 struct node *parent = NULL;
154 u32 nritems = btrfs_header_nritems(&leaf->header);
156 if (path->nodes[level + 1])
157 parent = &path->nodes[level + 1]->node;
158 parent_slot = path->slots[level + 1];
159 BUG_ON(leaf_free_space(leaf) < 0);
165 struct btrfs_disk_key *parent_key;
166 parent_key = &parent->keys[parent_slot];
167 BUG_ON(memcmp(parent_key, &leaf->items[0].key,
168 sizeof(struct btrfs_disk_key)));
169 BUG_ON(parent->blockptrs[parent_slot] !=
170 btrfs_header_blocknr(&leaf->header));
172 for (i = 0; nritems > 1 && i < nritems - 2; i++) {
173 struct btrfs_key cpukey;
174 btrfs_disk_key_to_cpu(&cpukey, &leaf->items[i + 1].key);
175 BUG_ON(comp_keys(&leaf->items[i].key,
177 BUG_ON(leaf->items[i].offset != leaf->items[i + 1].offset +
178 leaf->items[i + 1].size);
180 BUG_ON(leaf->items[i].offset + leaf->items[i].size !=
187 int check_block(struct ctree_path *path, int level)
190 return check_leaf(path, level);
191 return check_node(path, level);
195 * search for key in the array p. items p are item_size apart
196 * and there are 'max' items in p
197 * the slot in the array is returned via slot, and it points to
198 * the place where you would insert key if it is not found in
201 * slot may point to max if the key is bigger than all of the keys
203 int generic_bin_search(char *p, int item_size, struct btrfs_key *key,
210 struct btrfs_disk_key *tmp;
213 mid = (low + high) / 2;
214 tmp = (struct btrfs_disk_key *)(p + mid * item_size);
215 ret = comp_keys(tmp, key);
231 * simple bin_search frontend that does the right thing for
234 int bin_search(struct node *c, struct btrfs_key *key, int *slot)
236 if (btrfs_is_leaf(c)) {
237 struct leaf *l = (struct leaf *)c;
238 return generic_bin_search((void *)l->items, sizeof(struct item),
239 key, btrfs_header_nritems(&c->header),
242 return generic_bin_search((void *)c->keys,
243 sizeof(struct btrfs_disk_key),
244 key, btrfs_header_nritems(&c->header),
250 struct tree_buffer *read_node_slot(struct ctree_root *root,
251 struct tree_buffer *parent_buf,
254 struct node *node = &parent_buf->node;
257 if (slot >= btrfs_header_nritems(&node->header))
259 return read_tree_block(root, node->blockptrs[slot]);
262 static int balance_level(struct ctree_root *root, struct ctree_path *path,
265 struct tree_buffer *right_buf;
266 struct tree_buffer *mid_buf;
267 struct tree_buffer *left_buf;
268 struct tree_buffer *parent_buf = NULL;
269 struct node *right = NULL;
271 struct node *left = NULL;
272 struct node *parent = NULL;
276 int orig_slot = path->slots[level];
282 mid_buf = path->nodes[level];
283 mid = &mid_buf->node;
284 orig_ptr = mid->blockptrs[orig_slot];
286 if (level < MAX_LEVEL - 1)
287 parent_buf = path->nodes[level + 1];
288 pslot = path->slots[level + 1];
291 struct tree_buffer *child;
292 u64 blocknr = mid_buf->blocknr;
294 if (btrfs_header_nritems(&mid->header) != 1)
297 /* promote the child to a root */
298 child = read_node_slot(root, mid_buf, 0);
301 path->nodes[level] = NULL;
302 /* once for the path */
303 tree_block_release(root, mid_buf);
304 /* once for the root ptr */
305 tree_block_release(root, mid_buf);
306 clean_tree_block(root, mid_buf);
307 return free_extent(root, blocknr, 1);
309 parent = &parent_buf->node;
311 if (btrfs_header_nritems(&mid->header) > NODEPTRS_PER_BLOCK / 4)
314 left_buf = read_node_slot(root, parent_buf, pslot - 1);
315 right_buf = read_node_slot(root, parent_buf, pslot + 1);
317 /* first, try to make some room in the middle buffer */
319 btrfs_cow_block(root, left_buf, parent_buf,
320 pslot - 1, &left_buf);
321 left = &left_buf->node;
322 orig_slot += btrfs_header_nritems(&left->header);
323 wret = push_node_left(root, left_buf, mid_buf);
329 * then try to empty the right most buffer into the middle
332 btrfs_cow_block(root, right_buf, parent_buf,
333 pslot + 1, &right_buf);
334 right = &right_buf->node;
335 wret = push_node_left(root, mid_buf, right_buf);
338 if (btrfs_header_nritems(&right->header) == 0) {
339 u64 blocknr = right_buf->blocknr;
340 tree_block_release(root, right_buf);
341 clean_tree_block(root, right_buf);
344 wret = del_ptr(root, path, level + 1, pslot + 1);
347 wret = free_extent(root, blocknr, 1);
351 memcpy(parent->keys + pslot + 1, right->keys,
352 sizeof(struct btrfs_disk_key));
353 BUG_ON(list_empty(&parent_buf->dirty));
356 if (btrfs_header_nritems(&mid->header) == 1) {
358 * we're not allowed to leave a node with one item in the
359 * tree during a delete. A deletion from lower in the tree
360 * could try to delete the only pointer in this node.
361 * So, pull some keys from the left.
362 * There has to be a left pointer at this point because
363 * otherwise we would have pulled some pointers from the
367 wret = balance_node_right(root, mid_buf, left_buf);
372 if (btrfs_header_nritems(&mid->header) == 0) {
373 /* we've managed to empty the middle node, drop it */
374 u64 blocknr = mid_buf->blocknr;
375 tree_block_release(root, mid_buf);
376 clean_tree_block(root, mid_buf);
379 wret = del_ptr(root, path, level + 1, pslot);
382 wret = free_extent(root, blocknr, 1);
386 /* update the parent key to reflect our changes */
387 memcpy(parent->keys + pslot, mid->keys,
388 sizeof(struct btrfs_disk_key));
389 BUG_ON(list_empty(&parent_buf->dirty));
392 /* update the path */
394 if (btrfs_header_nritems(&left->header) > orig_slot) {
395 left_buf->count++; // released below
396 path->nodes[level] = left_buf;
397 path->slots[level + 1] -= 1;
398 path->slots[level] = orig_slot;
400 tree_block_release(root, mid_buf);
402 orig_slot -= btrfs_header_nritems(&left->header);
403 path->slots[level] = orig_slot;
406 /* double check we haven't messed things up */
407 check_block(path, level);
408 if (orig_ptr != path->nodes[level]->node.blockptrs[path->slots[level]])
412 tree_block_release(root, right_buf);
414 tree_block_release(root, left_buf);
419 * look for key in the tree. path is filled in with nodes along the way
420 * if key is found, we return zero and you can find the item in the leaf
421 * level of the path (level 0)
423 * If the key isn't found, the path points to the slot where it should
424 * be inserted, and 1 is returned. If there are other errors during the
425 * search a negative error number is returned.
427 * if ins_len > 0, nodes and leaves will be split as we walk down the
428 * tree. if ins_len < 0, nodes will be merged as we walk down the tree (if
431 int search_slot(struct ctree_root *root, struct btrfs_key *key,
432 struct ctree_path *p, int ins_len, int cow)
434 struct tree_buffer *b;
435 struct tree_buffer *cow_buf;
445 level = btrfs_header_level(&b->node.header);
448 wret = btrfs_cow_block(root, b, p->nodes[level + 1],
449 p->slots[level + 1], &cow_buf);
452 BUG_ON(!cow && ins_len);
455 ret = check_block(p, level);
458 ret = bin_search(c, key, &slot);
459 if (!btrfs_is_leaf(c)) {
462 p->slots[level] = slot;
463 if (ins_len > 0 && btrfs_header_nritems(&c->header) ==
464 NODEPTRS_PER_BLOCK) {
465 int sret = split_node(root, p, level);
471 slot = p->slots[level];
472 } else if (ins_len < 0) {
473 int sret = balance_level(root, p, level);
480 slot = p->slots[level];
481 BUG_ON(btrfs_header_nritems(&c->header) == 1);
483 b = read_tree_block(root, c->blockptrs[slot]);
485 struct leaf *l = (struct leaf *)c;
486 p->slots[level] = slot;
487 if (ins_len > 0 && leaf_free_space(l) <
488 sizeof(struct item) + ins_len) {
489 int sret = split_leaf(root, p, ins_len);
494 BUG_ON(root->node->count == 1);
498 BUG_ON(root->node->count == 1);
503 * adjust the pointers going up the tree, starting at level
504 * making sure the right key of each node is points to 'key'.
505 * This is used after shifting pointers to the left, so it stops
506 * fixing up pointers when a given leaf/node is not in slot 0 of the
509 * If this fails to write a tree block, it returns -1, but continues
510 * fixing up the blocks in ram so the tree is consistent.
512 static int fixup_low_keys(struct ctree_root *root,
513 struct ctree_path *path, struct btrfs_disk_key *key,
518 for (i = level; i < MAX_LEVEL; i++) {
520 int tslot = path->slots[i];
523 t = &path->nodes[i]->node;
524 memcpy(t->keys + tslot, key, sizeof(*key));
525 BUG_ON(list_empty(&path->nodes[i]->dirty));
533 * try to push data from one node into the next node left in the
536 * returns 0 if some ptrs were pushed left, < 0 if there was some horrible
537 * error, and > 0 if there was no room in the left hand block.
539 static int push_node_left(struct ctree_root *root, struct tree_buffer *dst_buf,
540 struct tree_buffer *src_buf)
542 struct node *src = &src_buf->node;
543 struct node *dst = &dst_buf->node;
549 src_nritems = btrfs_header_nritems(&src->header);
550 dst_nritems = btrfs_header_nritems(&dst->header);
551 push_items = NODEPTRS_PER_BLOCK - dst_nritems;
552 if (push_items <= 0) {
556 if (src_nritems < push_items)
557 push_items = src_nritems;
559 memcpy(dst->keys + dst_nritems, src->keys,
560 push_items * sizeof(struct btrfs_disk_key));
561 memcpy(dst->blockptrs + dst_nritems, src->blockptrs,
562 push_items * sizeof(u64));
563 if (push_items < src_nritems) {
564 memmove(src->keys, src->keys + push_items,
565 (src_nritems - push_items) *
566 sizeof(struct btrfs_disk_key));
567 memmove(src->blockptrs, src->blockptrs + push_items,
568 (src_nritems - push_items) * sizeof(u64));
570 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
571 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
572 BUG_ON(list_empty(&src_buf->dirty));
573 BUG_ON(list_empty(&dst_buf->dirty));
578 * try to push data from one node into the next node right in the
581 * returns 0 if some ptrs were pushed, < 0 if there was some horrible
582 * error, and > 0 if there was no room in the right hand block.
584 * this will only push up to 1/2 the contents of the left node over
586 static int balance_node_right(struct ctree_root *root,
587 struct tree_buffer *dst_buf,
588 struct tree_buffer *src_buf)
590 struct node *src = &src_buf->node;
591 struct node *dst = &dst_buf->node;
598 src_nritems = btrfs_header_nritems(&src->header);
599 dst_nritems = btrfs_header_nritems(&dst->header);
600 push_items = NODEPTRS_PER_BLOCK - dst_nritems;
601 if (push_items <= 0) {
605 max_push = src_nritems / 2 + 1;
606 /* don't try to empty the node */
607 if (max_push > src_nritems)
609 if (max_push < push_items)
610 push_items = max_push;
612 memmove(dst->keys + push_items, dst->keys,
613 dst_nritems * sizeof(struct btrfs_disk_key));
614 memmove(dst->blockptrs + push_items, dst->blockptrs,
615 dst_nritems * sizeof(u64));
616 memcpy(dst->keys, src->keys + src_nritems - push_items,
617 push_items * sizeof(struct btrfs_disk_key));
618 memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items,
619 push_items * sizeof(u64));
621 btrfs_set_header_nritems(&src->header, src_nritems - push_items);
622 btrfs_set_header_nritems(&dst->header, dst_nritems + push_items);
624 BUG_ON(list_empty(&src_buf->dirty));
625 BUG_ON(list_empty(&dst_buf->dirty));
630 * helper function to insert a new root level in the tree.
631 * A new node is allocated, and a single item is inserted to
632 * point to the existing root
634 * returns zero on success or < 0 on failure.
636 static int insert_new_root(struct ctree_root *root,
637 struct ctree_path *path, int level)
639 struct tree_buffer *t;
642 struct btrfs_disk_key *lower_key;
644 BUG_ON(path->nodes[level]);
645 BUG_ON(path->nodes[level-1] != root->node);
647 t = alloc_free_block(root);
649 memset(c, 0, sizeof(c));
650 btrfs_set_header_nritems(&c->header, 1);
651 btrfs_set_header_level(&c->header, level);
652 btrfs_set_header_blocknr(&c->header, t->blocknr);
653 btrfs_set_header_parentid(&c->header,
654 btrfs_header_parentid(&root->node->node.header));
655 lower = &path->nodes[level-1]->node;
656 if (btrfs_is_leaf(lower))
657 lower_key = &((struct leaf *)lower)->items[0].key;
659 lower_key = lower->keys;
660 memcpy(c->keys, lower_key, sizeof(struct btrfs_disk_key));
661 c->blockptrs[0] = path->nodes[level-1]->blocknr;
662 /* the super has an extra ref to root->node */
663 tree_block_release(root, root->node);
666 path->nodes[level] = t;
667 path->slots[level] = 0;
672 * worker function to insert a single pointer in a node.
673 * the node should have enough room for the pointer already
675 * slot and level indicate where you want the key to go, and
676 * blocknr is the block the key points to.
678 * returns zero on success and < 0 on any error
680 static int insert_ptr(struct ctree_root *root,
681 struct ctree_path *path, struct btrfs_disk_key *key,
682 u64 blocknr, int slot, int level)
687 BUG_ON(!path->nodes[level]);
688 lower = &path->nodes[level]->node;
689 nritems = btrfs_header_nritems(&lower->header);
692 if (nritems == NODEPTRS_PER_BLOCK)
694 if (slot != nritems) {
695 memmove(lower->keys + slot + 1, lower->keys + slot,
696 (nritems - slot) * sizeof(struct btrfs_disk_key));
697 memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot,
698 (nritems - slot) * sizeof(u64));
700 memcpy(lower->keys + slot, key, sizeof(struct btrfs_disk_key));
701 lower->blockptrs[slot] = blocknr;
702 btrfs_set_header_nritems(&lower->header, nritems + 1);
703 if (lower->keys[1].objectid == 0)
705 BUG_ON(list_empty(&path->nodes[level]->dirty));
710 * split the node at the specified level in path in two.
711 * The path is corrected to point to the appropriate node after the split
713 * Before splitting this tries to make some room in the node by pushing
714 * left and right, if either one works, it returns right away.
716 * returns 0 on success and < 0 on failure
718 static int split_node(struct ctree_root *root, struct ctree_path *path,
721 struct tree_buffer *t;
723 struct tree_buffer *split_buffer;
730 t = path->nodes[level];
732 if (t == root->node) {
733 /* trying to split the root, lets make a new one */
734 ret = insert_new_root(root, path, level + 1);
738 c_nritems = btrfs_header_nritems(&c->header);
739 split_buffer = alloc_free_block(root);
740 split = &split_buffer->node;
741 btrfs_set_header_flags(&split->header, btrfs_header_flags(&c->header));
742 btrfs_set_header_blocknr(&split->header, split_buffer->blocknr);
743 btrfs_set_header_parentid(&split->header,
744 btrfs_header_parentid(&root->node->node.header));
745 mid = (c_nritems + 1) / 2;
746 memcpy(split->keys, c->keys + mid,
747 (c_nritems - mid) * sizeof(struct btrfs_disk_key));
748 memcpy(split->blockptrs, c->blockptrs + mid,
749 (c_nritems - mid) * sizeof(u64));
750 btrfs_set_header_nritems(&split->header, c_nritems - mid);
751 btrfs_set_header_nritems(&c->header, mid);
754 BUG_ON(list_empty(&t->dirty));
755 wret = insert_ptr(root, path, split->keys, split_buffer->blocknr,
756 path->slots[level + 1] + 1, level + 1);
760 if (path->slots[level] >= mid) {
761 path->slots[level] -= mid;
762 tree_block_release(root, t);
763 path->nodes[level] = split_buffer;
764 path->slots[level + 1] += 1;
766 tree_block_release(root, split_buffer);
772 * how many bytes are required to store the items in a leaf. start
773 * and nr indicate which items in the leaf to check. This totals up the
774 * space used both by the item structs and the item data
776 static int leaf_space_used(struct leaf *l, int start, int nr)
779 int end = start + nr - 1;
783 data_len = l->items[start].offset + l->items[start].size;
784 data_len = data_len - l->items[end].offset;
785 data_len += sizeof(struct item) * nr;
790 * push some data in the path leaf to the right, trying to free up at
791 * least data_size bytes. returns zero if the push worked, nonzero otherwise
793 * returns 1 if the push failed because the other node didn't have enough
794 * room, 0 if everything worked out and < 0 if there were major errors.
796 static int push_leaf_right(struct ctree_root *root, struct ctree_path *path,
799 struct tree_buffer *left_buf = path->nodes[0];
800 struct leaf *left = &left_buf->leaf;
802 struct tree_buffer *right_buf;
803 struct tree_buffer *upper;
813 slot = path->slots[1];
814 if (!path->nodes[1]) {
817 upper = path->nodes[1];
818 if (slot >= btrfs_header_nritems(&upper->node.header) - 1) {
821 right_buf = read_tree_block(root, upper->node.blockptrs[slot + 1]);
822 right = &right_buf->leaf;
823 free_space = leaf_free_space(right);
824 if (free_space < data_size + sizeof(struct item)) {
825 tree_block_release(root, right_buf);
828 /* cow and double check */
829 btrfs_cow_block(root, right_buf, upper, slot + 1, &right_buf);
830 right = &right_buf->leaf;
831 free_space = leaf_free_space(right);
832 if (free_space < data_size + sizeof(struct item)) {
833 tree_block_release(root, right_buf);
837 left_nritems = btrfs_header_nritems(&left->header);
838 for (i = left_nritems - 1; i >= 0; i--) {
839 item = left->items + i;
840 if (path->slots[0] == i)
841 push_space += data_size + sizeof(*item);
842 if (item->size + sizeof(*item) + push_space > free_space)
845 push_space += item->size + sizeof(*item);
847 if (push_items == 0) {
848 tree_block_release(root, right_buf);
851 right_nritems = btrfs_header_nritems(&right->header);
852 /* push left to right */
853 push_space = left->items[left_nritems - push_items].offset +
854 left->items[left_nritems - push_items].size;
855 push_space -= leaf_data_end(left);
856 /* make room in the right data area */
857 memmove(right->data + leaf_data_end(right) - push_space,
858 right->data + leaf_data_end(right),
859 LEAF_DATA_SIZE - leaf_data_end(right));
860 /* copy from the left data area */
861 memcpy(right->data + LEAF_DATA_SIZE - push_space,
862 left->data + leaf_data_end(left),
864 memmove(right->items + push_items, right->items,
865 right_nritems * sizeof(struct item));
866 /* copy the items from left to right */
867 memcpy(right->items, left->items + left_nritems - push_items,
868 push_items * sizeof(struct item));
870 /* update the item pointers */
871 right_nritems += push_items;
872 btrfs_set_header_nritems(&right->header, right_nritems);
873 push_space = LEAF_DATA_SIZE;
874 for (i = 0; i < right_nritems; i++) {
875 right->items[i].offset = push_space - right->items[i].size;
876 push_space = right->items[i].offset;
878 left_nritems -= push_items;
879 btrfs_set_header_nritems(&left->header, left_nritems);
881 BUG_ON(list_empty(&left_buf->dirty));
882 BUG_ON(list_empty(&right_buf->dirty));
883 memcpy(upper->node.keys + slot + 1,
884 &right->items[0].key, sizeof(struct btrfs_disk_key));
885 BUG_ON(list_empty(&upper->dirty));
887 /* then fixup the leaf pointer in the path */
888 if (path->slots[0] >= left_nritems) {
889 path->slots[0] -= left_nritems;
890 tree_block_release(root, path->nodes[0]);
891 path->nodes[0] = right_buf;
894 tree_block_release(root, right_buf);
899 * push some data in the path leaf to the left, trying to free up at
900 * least data_size bytes. returns zero if the push worked, nonzero otherwise
902 static int push_leaf_left(struct ctree_root *root, struct ctree_path *path,
905 struct tree_buffer *right_buf = path->nodes[0];
906 struct leaf *right = &right_buf->leaf;
907 struct tree_buffer *t;
915 u32 old_left_nritems;
919 slot = path->slots[1];
923 if (!path->nodes[1]) {
926 t = read_tree_block(root, path->nodes[1]->node.blockptrs[slot - 1]);
928 free_space = leaf_free_space(left);
929 if (free_space < data_size + sizeof(struct item)) {
930 tree_block_release(root, t);
934 /* cow and double check */
935 btrfs_cow_block(root, t, path->nodes[1], slot - 1, &t);
937 free_space = leaf_free_space(left);
938 if (free_space < data_size + sizeof(struct item)) {
939 tree_block_release(root, t);
943 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
944 item = right->items + i;
945 if (path->slots[0] == i)
946 push_space += data_size + sizeof(*item);
947 if (item->size + sizeof(*item) + push_space > free_space)
950 push_space += item->size + sizeof(*item);
952 if (push_items == 0) {
953 tree_block_release(root, t);
956 /* push data from right to left */
957 memcpy(left->items + btrfs_header_nritems(&left->header),
958 right->items, push_items * sizeof(struct item));
959 push_space = LEAF_DATA_SIZE - right->items[push_items -1].offset;
960 memcpy(left->data + leaf_data_end(left) - push_space,
961 right->data + right->items[push_items - 1].offset,
963 old_left_nritems = btrfs_header_nritems(&left->header);
964 BUG_ON(old_left_nritems < 0);
966 for(i = old_left_nritems; i < old_left_nritems + push_items; i++) {
967 left->items[i].offset -= LEAF_DATA_SIZE -
968 left->items[old_left_nritems -1].offset;
970 btrfs_set_header_nritems(&left->header, old_left_nritems + push_items);
972 /* fixup right node */
973 push_space = right->items[push_items-1].offset - leaf_data_end(right);
974 memmove(right->data + LEAF_DATA_SIZE - push_space, right->data +
975 leaf_data_end(right), push_space);
976 memmove(right->items, right->items + push_items,
977 (btrfs_header_nritems(&right->header) - push_items) *
978 sizeof(struct item));
979 btrfs_set_header_nritems(&right->header,
980 btrfs_header_nritems(&right->header) -
982 push_space = LEAF_DATA_SIZE;
984 for (i = 0; i < btrfs_header_nritems(&right->header); i++) {
985 right->items[i].offset = push_space - right->items[i].size;
986 push_space = right->items[i].offset;
989 BUG_ON(list_empty(&t->dirty));
990 BUG_ON(list_empty(&right_buf->dirty));
992 wret = fixup_low_keys(root, path, &right->items[0].key, 1);
996 /* then fixup the leaf pointer in the path */
997 if (path->slots[0] < push_items) {
998 path->slots[0] += old_left_nritems;
999 tree_block_release(root, path->nodes[0]);
1001 path->slots[1] -= 1;
1003 tree_block_release(root, t);
1004 path->slots[0] -= push_items;
1006 BUG_ON(path->slots[0] < 0);
1011 * split the path's leaf in two, making sure there is at least data_size
1012 * available for the resulting leaf level of the path.
1014 * returns 0 if all went well and < 0 on failure.
1016 static int split_leaf(struct ctree_root *root, struct ctree_path *path,
1019 struct tree_buffer *l_buf;
1025 struct tree_buffer *right_buffer;
1026 int space_needed = data_size + sizeof(struct item);
1033 l_buf = path->nodes[0];
1036 /* did the pushes work? */
1037 if (leaf_free_space(l) >= sizeof(struct item) + data_size)
1040 if (!path->nodes[1]) {
1041 ret = insert_new_root(root, path, 1);
1045 slot = path->slots[0];
1046 nritems = btrfs_header_nritems(&l->header);
1047 mid = (nritems + 1)/ 2;
1048 right_buffer = alloc_free_block(root);
1049 BUG_ON(!right_buffer);
1050 BUG_ON(mid == nritems);
1051 right = &right_buffer->leaf;
1052 memset(right, 0, sizeof(*right));
1054 /* FIXME, just alloc a new leaf here */
1055 if (leaf_space_used(l, mid, nritems - mid) + space_needed >
1059 /* FIXME, just alloc a new leaf here */
1060 if (leaf_space_used(l, 0, mid + 1) + space_needed >
1064 btrfs_set_header_nritems(&right->header, nritems - mid);
1065 btrfs_set_header_blocknr(&right->header, right_buffer->blocknr);
1066 btrfs_set_header_level(&right->header, 0);
1067 btrfs_set_header_parentid(&right->header,
1068 btrfs_header_parentid(&root->node->node.header));
1069 data_copy_size = l->items[mid].offset + l->items[mid].size -
1071 memcpy(right->items, l->items + mid,
1072 (nritems - mid) * sizeof(struct item));
1073 memcpy(right->data + LEAF_DATA_SIZE - data_copy_size,
1074 l->data + leaf_data_end(l), data_copy_size);
1075 rt_data_off = LEAF_DATA_SIZE -
1076 (l->items[mid].offset + l->items[mid].size);
1078 for (i = 0; i < btrfs_header_nritems(&right->header); i++)
1079 right->items[i].offset += rt_data_off;
1081 btrfs_set_header_nritems(&l->header, mid);
1083 wret = insert_ptr(root, path, &right->items[0].key,
1084 right_buffer->blocknr, path->slots[1] + 1, 1);
1087 BUG_ON(list_empty(&right_buffer->dirty));
1088 BUG_ON(list_empty(&l_buf->dirty));
1089 BUG_ON(path->slots[0] != slot);
1091 tree_block_release(root, path->nodes[0]);
1092 path->nodes[0] = right_buffer;
1093 path->slots[0] -= mid;
1094 path->slots[1] += 1;
1096 tree_block_release(root, right_buffer);
1097 BUG_ON(path->slots[0] < 0);
1102 * Given a key and some data, insert an item into the tree.
1103 * This does all the path init required, making room in the tree if needed.
1105 int insert_item(struct ctree_root *root, struct btrfs_key *cpu_key,
1106 void *data, int data_size)
1112 struct tree_buffer *leaf_buf;
1114 unsigned int data_end;
1115 struct ctree_path path;
1116 struct btrfs_disk_key disk_key;
1118 btrfs_cpu_key_to_disk(&disk_key, cpu_key);
1120 /* create a root if there isn't one */
1124 ret = search_slot(root, cpu_key, &path, data_size, 1);
1126 release_path(root, &path);
1132 slot_orig = path.slots[0];
1133 leaf_buf = path.nodes[0];
1134 leaf = &leaf_buf->leaf;
1136 nritems = btrfs_header_nritems(&leaf->header);
1137 data_end = leaf_data_end(leaf);
1139 if (leaf_free_space(leaf) < sizeof(struct item) + data_size)
1142 slot = path.slots[0];
1144 if (slot != nritems) {
1146 unsigned int old_data = leaf->items[slot].offset +
1147 leaf->items[slot].size;
1150 * item0..itemN ... dataN.offset..dataN.size .. data0.size
1152 /* first correct the data pointers */
1153 for (i = slot; i < nritems; i++)
1154 leaf->items[i].offset -= data_size;
1156 /* shift the items */
1157 memmove(leaf->items + slot + 1, leaf->items + slot,
1158 (nritems - slot) * sizeof(struct item));
1160 /* shift the data */
1161 memmove(leaf->data + data_end - data_size, leaf->data +
1162 data_end, old_data - data_end);
1163 data_end = old_data;
1165 /* copy the new data in */
1166 memcpy(&leaf->items[slot].key, &disk_key,
1167 sizeof(struct btrfs_disk_key));
1168 leaf->items[slot].offset = data_end - data_size;
1169 leaf->items[slot].size = data_size;
1170 memcpy(leaf->data + data_end - data_size, data, data_size);
1171 btrfs_set_header_nritems(&leaf->header, nritems + 1);
1175 ret = fixup_low_keys(root, &path, &disk_key, 1);
1177 BUG_ON(list_empty(&leaf_buf->dirty));
1178 if (leaf_free_space(leaf) < 0)
1180 check_leaf(&path, 0);
1182 release_path(root, &path);
1187 * delete the pointer from a given node.
1189 * If the delete empties a node, the node is removed from the tree,
1190 * continuing all the way the root if required. The root is converted into
1191 * a leaf if all the nodes are emptied.
1193 static int del_ptr(struct ctree_root *root, struct ctree_path *path, int level,
1197 struct tree_buffer *parent = path->nodes[level];
1202 node = &parent->node;
1203 nritems = btrfs_header_nritems(&node->header);
1204 if (slot != nritems -1) {
1205 memmove(node->keys + slot, node->keys + slot + 1,
1206 sizeof(struct btrfs_disk_key) * (nritems - slot - 1));
1207 memmove(node->blockptrs + slot,
1208 node->blockptrs + slot + 1,
1209 sizeof(u64) * (nritems - slot - 1));
1212 btrfs_set_header_nritems(&node->header, nritems);
1213 if (nritems == 0 && parent == root->node) {
1214 BUG_ON(btrfs_header_level(&root->node->node.header) != 1);
1215 /* just turn the root into a leaf and break */
1216 btrfs_set_header_level(&root->node->node.header, 0);
1217 } else if (slot == 0) {
1218 wret = fixup_low_keys(root, path, node->keys, level + 1);
1222 BUG_ON(list_empty(&parent->dirty));
1227 * delete the item at the leaf level in path. If that empties
1228 * the leaf, remove it from the tree
1230 int del_item(struct ctree_root *root, struct ctree_path *path)
1234 struct tree_buffer *leaf_buf;
1241 leaf_buf = path->nodes[0];
1242 leaf = &leaf_buf->leaf;
1243 slot = path->slots[0];
1244 doff = leaf->items[slot].offset;
1245 dsize = leaf->items[slot].size;
1246 nritems = btrfs_header_nritems(&leaf->header);
1248 if (slot != nritems - 1) {
1250 int data_end = leaf_data_end(leaf);
1251 memmove(leaf->data + data_end + dsize,
1252 leaf->data + data_end,
1254 for (i = slot + 1; i < nritems; i++)
1255 leaf->items[i].offset += dsize;
1256 memmove(leaf->items + slot, leaf->items + slot + 1,
1257 sizeof(struct item) *
1258 (nritems - slot - 1));
1260 btrfs_set_header_nritems(&leaf->header, nritems - 1);
1262 /* delete the leaf if we've emptied it */
1264 if (leaf_buf == root->node) {
1265 btrfs_set_header_level(&leaf->header, 0);
1266 BUG_ON(list_empty(&leaf_buf->dirty));
1268 clean_tree_block(root, leaf_buf);
1269 wret = del_ptr(root, path, 1, path->slots[1]);
1272 wret = free_extent(root, leaf_buf->blocknr, 1);
1277 int used = leaf_space_used(leaf, 0, nritems);
1279 wret = fixup_low_keys(root, path,
1280 &leaf->items[0].key, 1);
1284 BUG_ON(list_empty(&leaf_buf->dirty));
1286 /* delete the leaf if it is mostly empty */
1287 if (used < LEAF_DATA_SIZE / 3) {
1288 /* push_leaf_left fixes the path.
1289 * make sure the path still points to our leaf
1290 * for possible call to del_ptr below
1292 slot = path->slots[1];
1294 wret = push_leaf_left(root, path, 1);
1297 if (path->nodes[0] == leaf_buf &&
1298 btrfs_header_nritems(&leaf->header)) {
1299 wret = push_leaf_right(root, path, 1);
1303 if (btrfs_header_nritems(&leaf->header) == 0) {
1304 u64 blocknr = leaf_buf->blocknr;
1305 clean_tree_block(root, leaf_buf);
1306 wret = del_ptr(root, path, 1, slot);
1309 tree_block_release(root, leaf_buf);
1310 wret = free_extent(root, blocknr, 1);
1314 tree_block_release(root, leaf_buf);
1322 * walk up the tree as far as required to find the next leaf.
1323 * returns 0 if it found something or 1 if there are no greater leaves.
1324 * returns < 0 on io errors.
1326 int next_leaf(struct ctree_root *root, struct ctree_path *path)
1331 struct tree_buffer *c;
1332 struct tree_buffer *next = NULL;
1334 while(level < MAX_LEVEL) {
1335 if (!path->nodes[level])
1337 slot = path->slots[level] + 1;
1338 c = path->nodes[level];
1339 if (slot >= btrfs_header_nritems(&c->node.header)) {
1343 blocknr = c->node.blockptrs[slot];
1345 tree_block_release(root, next);
1346 next = read_tree_block(root, blocknr);
1349 path->slots[level] = slot;
1352 c = path->nodes[level];
1353 tree_block_release(root, c);
1354 path->nodes[level] = next;
1355 path->slots[level] = 0;
1358 next = read_tree_block(root, next->node.blockptrs[0]);