btrfs-progs/disk-io.c

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#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include "kerncompat.h"
#include "radix-tree.h"
#include "ctree.h"
#include "disk-io.h"
static int allocated_blocks = 0;
static int get_free_block(struct ctree_root *root, u64 *block)
{
struct stat st;
int ret;
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if (root->alloc_extent->num_used >= root->alloc_extent->num_blocks)
return -1;
*block = root->alloc_extent->blocknr + root->alloc_extent->num_used;
root->alloc_extent->num_used += 1;
if (root->alloc_extent->num_used >= root->alloc_extent->num_blocks) {
struct alloc_extent *ae = root->alloc_extent;
root->alloc_extent = root->reserve_extent;
root->reserve_extent = ae;
ae->num_blocks = 0;
}
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st.st_size = 0;
ret = fstat(root->fp, &st);
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if (st.st_size < (*block + 1) * CTREE_BLOCKSIZE)
ret = ftruncate(root->fp,
(*block + 1) * CTREE_BLOCKSIZE);
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return ret;
}
struct tree_buffer *alloc_tree_block(struct ctree_root *root, u64 blocknr)
{
struct tree_buffer *buf;
int ret;
buf = malloc(sizeof(struct tree_buffer));
if (!buf)
return buf;
allocated_blocks++;
buf->blocknr = blocknr;
buf->count = 1;
radix_tree_preload(GFP_KERNEL);
ret = radix_tree_insert(&root->cache_radix, blocknr, buf);
radix_tree_preload_end();
if (ret) {
free(buf);
return NULL;
}
return buf;
}
struct tree_buffer *alloc_free_block(struct ctree_root *root)
{
u64 free_block;
int ret;
struct tree_buffer * buf;
ret = get_free_block(root, &free_block);
if (ret) {
BUG();
return NULL;
}
buf = alloc_tree_block(root, free_block);
if (!buf)
BUG();
return buf;
}
struct tree_buffer *read_tree_block(struct ctree_root *root, u64 blocknr)
{
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loff_t offset = blocknr * CTREE_BLOCKSIZE;
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struct tree_buffer *buf;
int ret;
buf = radix_tree_lookup(&root->cache_radix, blocknr);
if (buf) {
buf->count++;
if (buf->blocknr != blocknr)
BUG();
if (buf->blocknr != buf->node.header.blocknr)
BUG();
return buf;
}
buf = alloc_tree_block(root, blocknr);
if (!buf)
return NULL;
ret = pread(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
if (ret != CTREE_BLOCKSIZE) {
free(buf);
return NULL;
}
if (buf->blocknr != buf->node.header.blocknr)
BUG();
return buf;
}
int write_tree_block(struct ctree_root *root, struct tree_buffer *buf)
{
u64 blocknr = buf->blocknr;
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loff_t offset = blocknr * CTREE_BLOCKSIZE;
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int ret;
if (buf->blocknr != buf->node.header.blocknr)
BUG();
ret = pwrite(root->fp, &buf->node, CTREE_BLOCKSIZE, offset);
if (ret != CTREE_BLOCKSIZE)
return ret;
if (buf == root->node)
return update_root_block(root);
return 0;
}
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struct ctree_super_block {
struct ctree_root_info root_info;
struct ctree_root_info extent_info;
} __attribute__ ((__packed__));
static int __setup_root(struct ctree_root *root, struct ctree_root *extent_root,
struct ctree_root_info *info, int fp)
{
root->fp = fp;
root->node = read_tree_block(root, info->tree_root);
root->extent_root = extent_root;
memcpy(&root->ai1, &info->alloc_extent, sizeof(info->alloc_extent));
memcpy(&root->ai2, &info->reserve_extent, sizeof(info->reserve_extent));
root->alloc_extent = &root->ai1;
root->reserve_extent = &root->ai2;
INIT_RADIX_TREE(&root->cache_radix, GFP_KERNEL);
printf("setup done reading root %p, used %lu\n", root, root->alloc_extent->num_used);
return 0;
}
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struct ctree_root *open_ctree(char *filename)
{
struct ctree_root *root = malloc(sizeof(struct ctree_root));
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struct ctree_root *extent_root = malloc(sizeof(struct ctree_root));
struct ctree_super_block super;
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int fp;
int ret;
fp = open(filename, O_CREAT | O_RDWR);
if (fp < 0) {
free(root);
return NULL;
}
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ret = pread(fp, &super, sizeof(struct ctree_super_block),
CTREE_SUPER_INFO_OFFSET(CTREE_BLOCKSIZE));
if (ret == 0) {
ret = mkfs(fp);
if (ret)
return NULL;
ret = pread(fp, &super, sizeof(struct ctree_super_block),
CTREE_SUPER_INFO_OFFSET(CTREE_BLOCKSIZE));
if (ret != sizeof(struct ctree_super_block))
return NULL;
}
BUG_ON(ret < 0);
__setup_root(root, extent_root, &super.root_info, fp);
__setup_root(extent_root, extent_root, &super.extent_info, fp);
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return root;
}
int close_ctree(struct ctree_root *root)
{
close(root->fp);
if (root->node)
tree_block_release(root, root->node);
free(root);
printf("on close %d blocks are allocated\n", allocated_blocks);
return 0;
}
int update_root_block(struct ctree_root *root)
{
int ret;
u64 root_block = root->node->blocknr;
ret = pwrite(root->fp, &root_block, sizeof(u64), 0);
if (ret != sizeof(u64))
return ret;
return 0;
}
void tree_block_release(struct ctree_root *root, struct tree_buffer *buf)
{
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return;
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buf->count--;
if (buf->count == 0) {
if (!radix_tree_lookup(&root->cache_radix, buf->blocknr))
BUG();
radix_tree_delete(&root->cache_radix, buf->blocknr);
memset(buf, 0, sizeof(*buf));
free(buf);
BUG_ON(allocated_blocks == 0);
allocated_blocks--;
}
}