mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-08-26 02:39:48 +00:00
175 lines
3.7 KiB
C
175 lines
3.7 KiB
C
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#define _XOPEN_SOURCE 500
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include "kerncompat.h"
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#include "radix-tree.h"
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#include "ctree.h"
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#include "disk-io.h"
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static int allocated_blocks = 0;
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struct ctree_header {
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u64 root_block;
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} __attribute__ ((__packed__));
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static int get_free_block(struct ctree_root *root, u64 *block)
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{
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struct stat st;
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int ret;
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st.st_size = 0;
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ret = fstat(root->fp, &st);
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if (st.st_size > sizeof(struct ctree_header)) {
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*block = (st.st_size -
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sizeof(struct ctree_header)) / CTREE_BLOCKSIZE;
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} else {
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*block = 0;
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}
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ret = ftruncate(root->fp, sizeof(struct ctree_header) + (*block + 1) *
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CTREE_BLOCKSIZE);
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return ret;
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}
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struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
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{
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struct tree_buffer *buf;
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int ret;
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buf = malloc(sizeof(struct tree_buffer));
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if (!buf)
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return buf;
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allocated_blocks++;
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buf->blocknr = blocknr;
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buf->count = 1;
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radix_tree_preload(GFP_KERNEL);
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ret = radix_tree_insert(&root->cache_radix, blocknr, buf);
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radix_tree_preload_end();
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if (ret) {
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free(buf);
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return NULL;
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}
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return buf;
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}
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struct tree_buffer *alloc_free_block(struct ctree_root *root)
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{
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u64 free_block;
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int ret;
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struct tree_buffer * buf;
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ret = get_free_block(root, &free_block);
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if (ret) {
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BUG();
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return NULL;
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}
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buf = alloc_tree_block(root, free_block);
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if (!buf)
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BUG();
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return buf;
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}
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struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
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{
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loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
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struct tree_buffer *buf;
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int ret;
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buf = radix_tree_lookup(&root->cache_radix, blocknr);
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if (buf) {
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buf->count++;
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if (buf->blocknr != blocknr)
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BUG();
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if (buf->blocknr != buf->node.header.blocknr)
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BUG();
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return buf;
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}
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buf = alloc_tree_block(root, blocknr);
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if (!buf)
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return NULL;
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ret = pread(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
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if (ret != CTREE_BLOCKSIZE) {
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free(buf);
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return NULL;
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}
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if (buf->blocknr != buf->node.header.blocknr)
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BUG();
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return buf;
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}
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int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
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{
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u64 blocknr = buf->blocknr;
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loff_t offset = blocknr * CTREE_BLOCKSIZE + sizeof(struct ctree_header);
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int ret;
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if (buf->blocknr != buf->node.header.blocknr)
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BUG();
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ret = pwrite(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
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if (ret != CTREE_BLOCKSIZE)
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return ret;
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if (buf == root->node)
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return update_root_block(root);
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return 0;
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}
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struct ctree_root *open_ctree(char *filename)
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{
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struct ctree_root *root = malloc(sizeof(struct ctree_root));
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int fp;
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u64 root_block;
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int ret;
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fp = open(filename, O_CREAT | O_RDWR);
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if (fp < 0) {
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free(root);
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return NULL;
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}
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root->fp = fp;
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INIT_RADIX_TREE(&root->cache_radix, GFP_KERNEL);
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ret = pread(fp, &root_block, sizeof(u64), 0);
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if (ret == sizeof(u64)) {
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printf("reading root node at block %lu\n", root_block);
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root->node = read_tree_block(root, root_block);
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} else
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root->node = NULL;
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return root;
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}
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int close_ctree(struct ctree_root *root)
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{
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close(root->fp);
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if (root->node)
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tree_block_release(root, root->node);
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free(root);
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printf("on close %d blocks are allocated\n", allocated_blocks);
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return 0;
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}
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int update_root_block(struct ctree_root *root)
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{
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int ret;
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u64 root_block = root->node->blocknr;
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ret = pwrite(root->fp, &root_block, sizeof(u64), 0);
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if (ret != sizeof(u64))
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return ret;
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return 0;
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}
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void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
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{
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buf->count--;
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if (buf->count == 0) {
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if (!radix_tree_lookup(&root->cache_radix, buf->blocknr))
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BUG();
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radix_tree_delete(&root->cache_radix, buf->blocknr);
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memset(buf, 0, sizeof(*buf));
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free(buf);
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BUG_ON(allocated_blocks == 0);
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allocated_blocks--;
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}
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}
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