diff options
author | Chris Mason <chris.mason@oracle.com> | 2007-01-26 23:51:26 +0300 |
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committer | David Woodhouse <dwmw2@hera.kernel.org> | 2007-01-26 23:51:26 +0300 |
commit | be0e5c097fc206b863ce9fe6b3cfd6974b0110f4 (patch) | |
tree | ec3ffe77df985bfd453ebad6349a56e8016cab18 /fs | |
download | linux-be0e5c097fc206b863ce9fe6b3cfd6974b0110f4.tar.xz |
Btrfs: Initial checkin, basic working tree code
Signed-off-by: Chris Mason <chris.mason@oracle.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/btrfs/ctree.c | 810 |
1 files changed, 810 insertions, 0 deletions
diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c new file mode 100644 index 000000000000..893fd56960a0 --- /dev/null +++ b/fs/btrfs/ctree.c @@ -0,0 +1,810 @@ +#include <stdio.h> +#include <stdlib.h> +#include "kerncompat.h" + +#define BLOCKSIZE 4096 + +struct key { + u64 objectid; + u32 flags; + u64 offset; +} __attribute__ ((__packed__)); + +struct header { + u64 fsid[2]; /* FS specific uuid */ + u64 blocknum; + u64 parentid; + u32 csum; + u32 ham; + u16 nritems; + u16 flags; +} __attribute__ ((__packed__)); + +#define NODEPTRS_PER_BLOCK ((BLOCKSIZE - sizeof(struct header)) / \ + (sizeof(struct key) + sizeof(u64))) + +#define LEVEL_BITS 3 +#define MAX_LEVEL (1 << LEVEL_BITS) +#define node_level(f) ((f) & (MAX_LEVEL-1)) +#define is_leaf(f) (node_level(f) == 0) + +struct ctree_root { + struct node *node; +}; + +struct item { + struct key key; + u16 offset; + u16 size; +} __attribute__ ((__packed__)); + +#define LEAF_DATA_SIZE (BLOCKSIZE - sizeof(struct header)) +struct leaf { + struct header header; + union { + struct item items[LEAF_DATA_SIZE/sizeof(struct item)]; + u8 data[BLOCKSIZE-sizeof(struct header)]; + }; +} __attribute__ ((__packed__)); + +struct node { + struct header header; + struct key keys[NODEPTRS_PER_BLOCK]; + u64 blockptrs[NODEPTRS_PER_BLOCK]; +} __attribute__ ((__packed__)); + +struct ctree_path { + struct node *nodes[MAX_LEVEL]; + int slots[MAX_LEVEL]; +}; + +static inline void init_path(struct ctree_path *p) +{ + memset(p, 0, sizeof(*p)); +} + +static inline unsigned int leaf_data_end(struct leaf *leaf) +{ + unsigned int nr = leaf->header.nritems; + if (nr == 0) + return ARRAY_SIZE(leaf->data); + return leaf->items[nr-1].offset; +} + +static inline int leaf_free_space(struct leaf *leaf) +{ + int data_end = leaf_data_end(leaf); + int nritems = leaf->header.nritems; + char *items_end = (char *)(leaf->items + nritems + 1); + return (char *)(leaf->data + data_end) - (char *)items_end; +} + +int comp_keys(struct key *k1, struct key *k2) +{ + if (k1->objectid > k2->objectid) + return 1; + if (k1->objectid < k2->objectid) + return -1; + if (k1->flags > k2->flags) + return 1; + if (k1->flags < k2->flags) + return -1; + if (k1->offset > k2->offset) + return 1; + if (k1->offset < k2->offset) + return -1; + return 0; +} +int generic_bin_search(char *p, int item_size, struct key *key, + int max, int *slot) +{ + int low = 0; + int high = max; + int mid; + int ret; + struct key *tmp; + + while(low < high) { + mid = (low + high) / 2; + tmp = (struct key *)(p + mid * item_size); + ret = comp_keys(tmp, key); + + if (ret < 0) + low = mid + 1; + else if (ret > 0) + high = mid; + else { + *slot = mid; + return 0; + } + } + *slot = low; + return 1; +} + +int bin_search(struct node *c, struct key *key, int *slot) +{ + if (is_leaf(c->header.flags)) { + struct leaf *l = (struct leaf *)c; + return generic_bin_search((void *)l->items, sizeof(struct item), + key, c->header.nritems, slot); + } else { + return generic_bin_search((void *)c->keys, sizeof(struct key), + key, c->header.nritems, slot); + } + return -1; +} + +void *read_block(u64 blocknum) +{ + return (void *)blocknum; +} + +int search_slot(struct ctree_root *root, struct key *key, struct ctree_path *p) +{ + struct node *c = root->node; + int slot; + int ret; + int level; + while (c) { + level = node_level(c->header.flags); + p->nodes[level] = c; + ret = bin_search(c, key, &slot); + if (!is_leaf(c->header.flags)) { + if (ret && slot > 0) + slot -= 1; + p->slots[level] = slot; + c = read_block(c->blockptrs[slot]); + continue; + } else { + p->slots[level] = slot; + return ret; + } + } + return -1; +} + +static void fixup_low_keys(struct ctree_path *path, struct key *key, + int level) +{ + int i; + /* adjust the pointers going up the tree */ + for (i = level; i < MAX_LEVEL; i++) { + struct node *t = path->nodes[i]; + int tslot = path->slots[i]; + if (!t) + break; + memcpy(t->keys + tslot, key, sizeof(*key)); + if (tslot != 0) + break; + } +} + +int __insert_ptr(struct ctree_root *root, + struct ctree_path *path, struct key *key, + u64 blocknr, int slot, int level) +{ + struct node *c; + struct node *lower; + struct key *lower_key; + int nritems; + /* need a new root */ + if (!path->nodes[level]) { + c = malloc(sizeof(struct node)); + memset(c, 0, sizeof(c)); + c->header.nritems = 2; + c->header.flags = node_level(level); + lower = path->nodes[level-1]; + if (is_leaf(lower->header.flags)) + lower_key = &((struct leaf *)lower)->items[0].key; + else + lower_key = lower->keys; + memcpy(c->keys, lower_key, sizeof(struct key)); + memcpy(c->keys + 1, key, sizeof(struct key)); + c->blockptrs[0] = (u64)lower; + c->blockptrs[1] = blocknr; + root->node = c; + path->nodes[level] = c; + path->slots[level] = 0; + if (c->keys[1].objectid == 0) + BUG(); + return 0; + } + lower = path->nodes[level]; + nritems = lower->header.nritems; + if (slot > nritems) + BUG(); + if (nritems == NODEPTRS_PER_BLOCK) + BUG(); + if (slot != nritems) { + memmove(lower->keys + slot + 1, lower->keys + slot, + (nritems - slot) * sizeof(struct key)); + memmove(lower->blockptrs + slot + 1, lower->blockptrs + slot, + (nritems - slot) * sizeof(u64)); + } + memcpy(lower->keys + slot, key, sizeof(struct key)); + lower->blockptrs[slot] = blocknr; + lower->header.nritems++; + if (lower->keys[1].objectid == 0) + BUG(); + return 0; +} + +int push_node_left(struct ctree_root *root, struct ctree_path *path, int level) +{ + int slot; + struct node *left; + struct node *right; + int push_items = 0; + int left_nritems; + int right_nritems; + + if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0) + return 1; + slot = path->slots[level + 1]; + if (slot == 0) + return 1; + + left = read_block(path->nodes[level + 1]->blockptrs[slot - 1]); + right = path->nodes[level]; + left_nritems = left->header.nritems; + right_nritems = right->header.nritems; + push_items = NODEPTRS_PER_BLOCK - (left_nritems + 1); + if (push_items <= 0) + return 1; + + if (right_nritems < push_items) + push_items = right_nritems; + memcpy(left->keys + left_nritems, right->keys, + push_items * sizeof(struct key)); + memcpy(left->blockptrs + left_nritems, right->blockptrs, + push_items * sizeof(u64)); + memmove(right->keys, right->keys + push_items, + (right_nritems - push_items) * sizeof(struct key)); + memmove(right->blockptrs, right->blockptrs + push_items, + (right_nritems - push_items) * sizeof(u64)); + right->header.nritems -= push_items; + left->header.nritems += push_items; + + /* adjust the pointers going up the tree */ + fixup_low_keys(path, right->keys, level + 1); + + /* then fixup the leaf pointer in the path */ + if (path->slots[level] < push_items) { + path->slots[level] += left_nritems; + path->nodes[level] = (struct node*)left; + path->slots[level + 1] -= 1; + } else { + path->slots[level] -= push_items; + } + return 0; +} + +int push_node_right(struct ctree_root *root, struct ctree_path *path, int level) +{ + int slot; + struct node *dst; + struct node *src; + int push_items = 0; + int dst_nritems; + int src_nritems; + + if (level == MAX_LEVEL - 1 || path->nodes[level + 1] == 0) + return 1; + slot = path->slots[level + 1]; + if (slot == NODEPTRS_PER_BLOCK - 1) + return 1; + + if (slot >= path->nodes[level + 1]->header.nritems -1) + return 1; + + dst = read_block(path->nodes[level + 1]->blockptrs[slot + 1]); + src = path->nodes[level]; + dst_nritems = dst->header.nritems; + src_nritems = src->header.nritems; + push_items = NODEPTRS_PER_BLOCK - (dst_nritems + 1); + if (push_items <= 0) + return 1; + + if (src_nritems < push_items) + push_items = src_nritems; + memmove(dst->keys + push_items, dst->keys, + dst_nritems * sizeof(struct key)); + memcpy(dst->keys, src->keys + src_nritems - push_items, + push_items * sizeof(struct key)); + + memmove(dst->blockptrs + push_items, dst->blockptrs, + dst_nritems * sizeof(u64)); + memcpy(dst->blockptrs, src->blockptrs + src_nritems - push_items, + push_items * sizeof(u64)); + + src->header.nritems -= push_items; + dst->header.nritems += push_items; + + /* adjust the pointers going up the tree */ + memcpy(path->nodes[level + 1]->keys + path->slots[level + 1] + 1, + dst->keys, sizeof(struct key)); + /* then fixup the leaf pointer in the path */ + if (path->slots[level] >= src->header.nritems) { + path->slots[level] -= src->header.nritems; + path->nodes[level] = (struct node*)dst; + path->slots[level + 1] += 1; + } + return 0; +} + +int insert_ptr(struct ctree_root *root, + struct ctree_path *path, struct key *key, + u64 blocknr, int level) +{ + struct node *c = path->nodes[level]; + struct node *b; + struct node *bal[MAX_LEVEL]; + int bal_level = level; + int mid; + int bal_start = -1; + + memset(bal, 0, ARRAY_SIZE(bal)); + while(c && c->header.nritems == NODEPTRS_PER_BLOCK) { + if (push_node_left(root, path, + node_level(c->header.flags)) == 0) + break; + if (push_node_right(root, path, + node_level(c->header.flags)) == 0) + break; + bal_start = bal_level; + if (bal_level == MAX_LEVEL - 1) + BUG(); + b = malloc(sizeof(struct node)); + b->header.flags = c->header.flags; + mid = (c->header.nritems + 1) / 2; + memcpy(b->keys, c->keys + mid, + (c->header.nritems - mid) * sizeof(struct key)); + memcpy(b->blockptrs, c->blockptrs + mid, + (c->header.nritems - mid) * sizeof(u64)); + b->header.nritems = c->header.nritems - mid; + c->header.nritems = mid; + bal[bal_level] = b; + if (bal_level == MAX_LEVEL - 1) + break; + bal_level += 1; + c = path->nodes[bal_level]; + } + while(bal_start > 0) { + b = bal[bal_start]; + c = path->nodes[bal_start]; + __insert_ptr(root, path, b->keys, (u64)b, + path->slots[bal_start + 1] + 1, bal_start + 1); + if (path->slots[bal_start] >= c->header.nritems) { + path->slots[bal_start] -= c->header.nritems; + path->nodes[bal_start] = b; + path->slots[bal_start + 1] += 1; + } + bal_start--; + if (!bal[bal_start]) + break; + } + return __insert_ptr(root, path, key, blocknr, path->slots[level] + 1, + level); +} + +int leaf_space_used(struct leaf *l, int start, int nr) +{ + int data_len; + int end = start + nr - 1; + + if (!nr) + return 0; + data_len = l->items[start].offset + l->items[start].size; + data_len = data_len - l->items[end].offset; + data_len += sizeof(struct item) * nr; + return data_len; +} + +int push_leaf_left(struct ctree_root *root, struct ctree_path *path, + int data_size) +{ + struct leaf *right = (struct leaf *)path->nodes[0]; + struct leaf *left; + int slot; + int i; + int free_space; + int push_space = 0; + int push_items = 0; + struct item *item; + int old_left_nritems; + + slot = path->slots[1]; + if (slot == 0) { + return 1; + } + if (!path->nodes[1]) { + return 1; + } + left = read_block(path->nodes[1]->blockptrs[slot - 1]); + free_space = leaf_free_space(left); + if (free_space < data_size + sizeof(struct item)) { + return 1; + } + for (i = 0; i < right->header.nritems; i++) { + item = right->items + i; + if (path->slots[0] == i) + push_space += data_size + sizeof(*item); + if (item->size + sizeof(*item) + push_space > free_space) + break; + push_items++; + push_space += item->size + sizeof(*item); + } + if (push_items == 0) { + return 1; + } + /* push data from right to left */ + memcpy(left->items + left->header.nritems, + right->items, push_items * sizeof(struct item)); + push_space = LEAF_DATA_SIZE - right->items[push_items -1].offset; + memcpy(left->data + leaf_data_end(left) - push_space, + right->data + right->items[push_items - 1].offset, + push_space); + old_left_nritems = left->header.nritems; + for(i = old_left_nritems; i < old_left_nritems + push_items; i++) { + left->items[i].offset -= LEAF_DATA_SIZE - + left->items[old_left_nritems -1].offset; + } + left->header.nritems += push_items; + + /* fixup right node */ + push_space = right->items[push_items-1].offset - leaf_data_end(right); + memmove(right->data + LEAF_DATA_SIZE - push_space, right->data + + leaf_data_end(right), push_space); + memmove(right->items, right->items + push_items, + (right->header.nritems - push_items) * sizeof(struct item)); + right->header.nritems -= push_items; + push_space = LEAF_DATA_SIZE; + for (i = 0; i < right->header.nritems; i++) { + right->items[i].offset = push_space - right->items[i].size; + push_space = right->items[i].offset; + } + fixup_low_keys(path, &right->items[0].key, 1); + + /* then fixup the leaf pointer in the path */ + if (path->slots[0] < push_items) { + path->slots[0] += old_left_nritems; + path->nodes[0] = (struct node*)left; + path->slots[1] -= 1; + } else { + path->slots[0] -= push_items; + } + return 0; +} + +int split_leaf(struct ctree_root *root, struct ctree_path *path, int data_size) +{ + struct leaf *l = (struct leaf *)path->nodes[0]; + int nritems = l->header.nritems; + int mid = (nritems + 1)/ 2; + int slot = path->slots[0]; + struct leaf *right; + int space_needed = data_size + sizeof(struct item); + int data_copy_size; + int rt_data_off; + int i; + int ret; + + if (push_leaf_left(root, path, data_size) == 0) { + return 0; + } + right = malloc(sizeof(struct leaf)); + memset(right, 0, sizeof(*right)); + if (mid <= slot) { + if (leaf_space_used(l, mid, nritems - mid) + space_needed > + LEAF_DATA_SIZE) + BUG(); + } else { + if (leaf_space_used(l, 0, mid + 1) + space_needed > + LEAF_DATA_SIZE) + BUG(); + } + right->header.nritems = nritems - mid; + data_copy_size = l->items[mid].offset + l->items[mid].size - + leaf_data_end(l); + memcpy(right->items, l->items + mid, + (nritems - mid) * sizeof(struct item)); + memcpy(right->data + LEAF_DATA_SIZE - data_copy_size, + l->data + leaf_data_end(l), data_copy_size); + rt_data_off = LEAF_DATA_SIZE - + (l->items[mid].offset + l->items[mid].size); + for (i = 0; i < right->header.nritems; i++) { + right->items[i].offset += rt_data_off; + } + l->header.nritems = mid; + ret = insert_ptr(root, path, &right->items[0].key, + (u64)right, 1); + if (mid <= slot) { + path->nodes[0] = (struct node *)right; + path->slots[0] -= mid; + path->slots[1] += 1; + } + return ret; +} + +int insert_item(struct ctree_root *root, struct key *key, + void *data, int data_size) +{ + int ret; + int slot; + struct leaf *leaf; + unsigned int nritems; + unsigned int data_end; + struct ctree_path path; + + init_path(&path); + ret = search_slot(root, key, &path); + if (ret == 0) + return -EEXIST; + + leaf = (struct leaf *)path.nodes[0]; + if (leaf_free_space(leaf) < sizeof(struct item) + data_size) + split_leaf(root, &path, data_size); + leaf = (struct leaf *)path.nodes[0]; + nritems = leaf->header.nritems; + data_end = leaf_data_end(leaf); + if (leaf_free_space(leaf) < sizeof(struct item) + data_size) + BUG(); + + slot = path.slots[0]; + if (slot == 0) + fixup_low_keys(&path, key, 1); + if (slot != nritems) { + int i; + unsigned int old_data = leaf->items[slot].offset + + leaf->items[slot].size; + + /* + * item0..itemN ... dataN.offset..dataN.size .. data0.size + */ + /* first correct the data pointers */ + for (i = slot; i < nritems; i++) + leaf->items[i].offset -= data_size; + + /* shift the items */ + memmove(leaf->items + slot + 1, leaf->items + slot, + (nritems - slot) * sizeof(struct item)); + + /* shift the data */ + memmove(leaf->data + data_end - data_size, leaf->data + + data_end, old_data - data_end); + data_end = old_data; + } + memcpy(&leaf->items[slot].key, key, sizeof(struct key)); + leaf->items[slot].offset = data_end - data_size; + leaf->items[slot].size = data_size; + memcpy(leaf->data + data_end - data_size, data, data_size); + leaf->header.nritems += 1; + if (leaf_free_space(leaf) < 0) + BUG(); + return 0; +} + +int del_ptr(struct ctree_root *root, struct ctree_path *path, int level) +{ + int slot; + struct node *node; + int nritems; + + while(1) { + node = path->nodes[level]; + if (!node) + break; + slot = path->slots[level]; + nritems = node->header.nritems; + + if (slot != nritems -1) { + memmove(node->keys + slot, node->keys + slot + 1, + sizeof(struct key) * (nritems - slot - 1)); + memmove(node->blockptrs + slot, + node->blockptrs + slot + 1, + sizeof(u64) * (nritems - slot - 1)); + } + node->header.nritems--; + if (node->header.nritems != 0) { + int tslot; + if (slot == 0) + fixup_low_keys(path, node->keys, level + 1); + tslot = path->slots[level+1]; + push_node_left(root, path, level); + if (node->header.nritems) { + push_node_right(root, path, level); + } + path->slots[level+1] = tslot; + if (node->header.nritems) + break; + } + if (node == root->node) { + printf("root is now null!\n"); + root->node = NULL; + break; + } + level++; + if (!path->nodes[level]) + BUG(); + free(node); + } + return 0; +} + +int del_item(struct ctree_root *root, struct key *key) +{ + int ret; + int slot; + struct leaf *leaf; + struct ctree_path path; + int doff; + int dsize; + + init_path(&path); + ret = search_slot(root, key, &path); + if (ret != 0) + return -1; + + leaf = (struct leaf *)path.nodes[0]; + slot = path.slots[0]; + doff = leaf->items[slot].offset; + dsize = leaf->items[slot].size; + + if (slot != leaf->header.nritems - 1) { + int i; + int data_end = leaf_data_end(leaf); + memmove(leaf->data + data_end + dsize, + leaf->data + data_end, + doff - data_end); + for (i = slot + 1; i < leaf->header.nritems; i++) + leaf->items[i].offset += dsize; + memmove(leaf->items + slot, leaf->items + slot + 1, + sizeof(struct item) * + (leaf->header.nritems - slot - 1)); + } + leaf->header.nritems -= 1; + if (leaf->header.nritems == 0) { + free(leaf); + del_ptr(root, &path, 1); + } else { + if (slot == 0) + fixup_low_keys(&path, &leaf->items[0].key, 1); + if (leaf_space_used(leaf, 0, leaf->header.nritems) < + LEAF_DATA_SIZE / 4) { + /* push_leaf_left fixes the path. + * make sure the path still points to our leaf + * for possible call to del_ptr below + */ + slot = path.slots[1]; + push_leaf_left(root, &path, 1); + path.slots[1] = slot; + if (leaf->header.nritems == 0) { + free(leaf); + del_ptr(root, &path, 1); + } + } + } + return 0; +} + +void print_leaf(struct leaf *l) +{ + int i; + int nr = l->header.nritems; + struct item *item; + printf("leaf %p total ptrs %d free space %d\n", l, nr, + leaf_free_space(l)); + fflush(stdout); + for (i = 0 ; i < nr ; i++) { + item = l->items + i; + printf("\titem %d key (%lu %u %lu) itemoff %d itemsize %d\n", + i, + item->key.objectid, item->key.flags, item->key.offset, + item->offset, item->size); + fflush(stdout); + printf("\t\titem data %.*s\n", item->size, l->data+item->offset); + fflush(stdout); + } +} +void print_tree(struct node *c) +{ + int i; + int nr; + + if (!c) + return; + nr = c->header.nritems; + if (is_leaf(c->header.flags)) { + print_leaf((struct leaf *)c); + return; + } + printf("node %p level %d total ptrs %d free spc %lu\n", c, + node_level(c->header.flags), c->header.nritems, + NODEPTRS_PER_BLOCK - c->header.nritems); + fflush(stdout); + for (i = 0; i < nr; i++) { + printf("\tkey %d (%lu %u %lu) block %lx\n", + i, + c->keys[i].objectid, c->keys[i].flags, c->keys[i].offset, + c->blockptrs[i]); + fflush(stdout); + } + for (i = 0; i < nr; i++) { + struct node *next = read_block(c->blockptrs[i]); + if (is_leaf(next->header.flags) && + node_level(c->header.flags) != 1) + BUG(); + if (node_level(next->header.flags) != + node_level(c->header.flags) - 1) + BUG(); + print_tree(next); + } + +} + +/* for testing only */ +int next_key(int i, int max_key) { + return rand() % max_key; + // return i; +} + +int main() { + struct leaf *first_node = malloc(sizeof(struct leaf)); + struct ctree_root root; + struct key ins; + char *buf; + int i; + int num; + int ret; + int run_size = 10000000; + int max_key = 100000000; + int tree_size = 0; + struct ctree_path path; + + + srand(55); + root.node = (struct node *)first_node; + memset(first_node, 0, sizeof(*first_node)); + for (i = 0; i < run_size; i++) { + buf = malloc(64); + num = next_key(i, max_key); + // num = i; + sprintf(buf, "string-%d", num); + // printf("insert %d\n", num); + ins.objectid = num; + ins.offset = 0; + ins.flags = 0; + ret = insert_item(&root, &ins, buf, strlen(buf)); + if (!ret) + tree_size++; + } + srand(55); + for (i = 0; i < run_size; i++) { + num = next_key(i, max_key); + ins.objectid = num; + ins.offset = 0; + ins.flags = 0; + init_path(&path); + ret = search_slot(&root, &ins, &path); + if (ret) { + print_tree(root.node); + printf("unable to find %d\n", num); + exit(1); + } + } + printf("node %p level %d total ptrs %d free spc %lu\n", root.node, + node_level(root.node->header.flags), root.node->header.nritems, + NODEPTRS_PER_BLOCK - root.node->header.nritems); + // print_tree(root.node); + printf("all searches good\n"); + i = 0; + srand(55); + for (i = 0; i < run_size; i++) { + num = next_key(i, max_key); + ins.objectid = num; + del_item(&root, &ins); + } + print_tree(root.node); + return 0; +} |