1.1 --- a/src/fs.c	Sun Dec 11 10:17:58 2011 +0200
     1.2 +++ b/src/fs.c	Sun Dec 11 11:12:30 2011 +0200
     1.3 @@ -4,47 +4,52 @@
     1.4   */
     1.5  #include <stdio.h>
     1.6  #include <stdlib.h>
     1.7 +#include <string.h>
     1.8  #include <errno.h>
     1.9 +#include <assert.h>
    1.10  #include "fs.h"
    1.11  #include "bdev.h"
    1.12  
    1.13  
    1.14  int openfs(struct filesys *fs, dev_t dev);
    1.15 -static int read_superblock(struct block_device *bdev, struct superblock *sb);
    1.16 -
    1.17 +static int read_superblock(struct filesys *fs);
    1.18 +static int write_superblock(struct filesys *fs);
    1.19 +static int get_inode(struct filesys *fs, int ino, struct inode *inode);
    1.20 +static int put_inode(struct filesys *fs, struct inode *inode);
    1.21  
    1.22  int openfs(struct filesys *fs, dev_t dev)
    1.23  {
    1.24  	int res;
    1.25  	struct block_device *bdev;
    1.26 -	struct superblock *sb = 0;
    1.27 +
    1.28 +	assert(BLKSZ % sizeof(struct inode) == 0);
    1.29  
    1.30  	if(!(bdev = blk_open(dev))) {
    1.31  		return -ENOENT;
    1.32  	}
    1.33 +	fs->bdev = bdev;
    1.34  
    1.35  	/* read the superblock */
    1.36 -	if(!(sb = malloc(BLKSZ))) {
    1.37 +	if(!(fs->sb = malloc(BLKSZ))) {
    1.38  		res = -ENOMEM;
    1.39  		goto done;
    1.40  	}
    1.41 -	if((res = read_superblock(bdev, sb)) != 0) {
    1.42 +	if((res = read_superblock(fs)) != 0) {
    1.43  		goto done;
    1.44  	}
    1.45  
    1.46  
    1.47 -
    1.48 -
    1.49  done:
    1.50  	blk_close(bdev);
    1.51 -	free(sb);
    1.52  	return res;
    1.53  }
    1.54  
    1.55 -static int read_superblock(struct block_device *bdev, struct superblock *sb)
    1.56 +static int read_superblock(struct filesys *fs)
    1.57  {
    1.58 +	struct superblock *sb = fs->sb;
    1.59 +
    1.60  	/* read superblock and verify */
    1.61 -	if(blk_read(bdev, 1, 1, sb) == -1) {
    1.62 +	if(blk_read(fs->bdev, 1, 1, sb) == -1) {
    1.63  		printf("failed to read superblock\n");
    1.64  		return -EIO;
    1.65  	}
    1.66 @@ -65,7 +70,7 @@
    1.67  	if(!(sb->ibm = malloc(sb->ibm_count * sb->blksize))) {
    1.68  		return -ENOMEM;
    1.69  	}
    1.70 -	if(blk_read(bdev, sb->ibm_start, sb->ibm_count, sb->ibm) == -1) {
    1.71 +	if(blk_read(fs->bdev, sb->ibm_start, sb->ibm_count, sb->ibm) == -1) {
    1.72  		printf("failed to read inode bitmap\n");
    1.73  		free(sb->ibm);
    1.74  		return -EIO;
    1.75 @@ -74,12 +79,80 @@
    1.76  		free(sb->ibm);
    1.77  		return -ENOMEM;
    1.78  	}
    1.79 -	if(blk_read(bdev, sb->bm_start, sb->bm_count, sb->bm) == -1) {
    1.80 +	if(blk_read(fs->bdev, sb->bm_start, sb->bm_count, sb->bm) == -1) {
    1.81  		printf("failed to read block bitmap\n");
    1.82  		free(sb->ibm);
    1.83  		free(sb->bm);
    1.84  		return -EIO;
    1.85  	}
    1.86  
    1.87 +	/* read the root inode */
    1.88 +	if(!(sb->root = malloc(sizeof *sb->root))) {
    1.89 +		free(sb->ibm);
    1.90 +		free(sb->bm);
    1.91 +		return -ENOMEM;
    1.92 +	}
    1.93 +	if(get_inode(fs, sb->root_ino, sb->root) == -1) {
    1.94 +		printf("failed to read root inode\n");
    1.95 +		return -1;
    1.96 +	}
    1.97 +
    1.98  	return 0;
    1.99  }
   1.100 +
   1.101 +static int write_superblock(struct filesys *fs)
   1.102 +{
   1.103 +	struct superblock *sb = fs->sb;
   1.104 +
   1.105 +	/* write back any changes in the root inode */
   1.106 +	if(put_inode(fs, sb->root) == -1) {
   1.107 +		return -1;
   1.108 +	}
   1.109 +	/* write back the block bitmap */
   1.110 +	if(blk_write(fs->bdev, sb->bm_start, sb->bm_count, sb->bm) == -1) {
   1.111 +		return -1;
   1.112 +	}
   1.113 +	/* write back the inode bitmap */
   1.114 +	if(blk_write(fs->bdev, sb->ibm_start, sb->ibm_count, sb->ibm) == -1) {
   1.115 +		return -1;
   1.116 +	}
   1.117 +	return 0;
   1.118 +}
   1.119 +
   1.120 +/* number of inodes in a block */
   1.121 +#define BLK_INODES		(BLKSZ / sizeof(struct inode))
   1.122 +
   1.123 +/* copy the requested inode from the disk, into the buffer passed in the last arg */
   1.124 +static int get_inode(struct filesys *fs, int ino, struct inode *inode)
   1.125 +{
   1.126 +	struct inode *buf = malloc(BLKSZ);
   1.127 +	assert(buf);
   1.128 +
   1.129 +	if(blk_read(fs->bdev, fs->sb->itbl_start + ino / BLK_INODES, 1, buf) == -1) {
   1.130 +		free(buf);
   1.131 +		return -1;
   1.132 +	}
   1.133 +	memcpy(inode, buf + ino % BLK_INODES, sizeof *inode);
   1.134 +	free(buf);
   1.135 +	return 0;
   1.136 +}
   1.137 +
   1.138 +/* write the inode to the disk */
   1.139 +static int put_inode(struct filesys *fs, struct inode *inode)
   1.140 +{
   1.141 +	struct inode *buf = malloc(BLKSZ);
   1.142 +	assert(buf);
   1.143 +
   1.144 +	if(blk_read(fs->bdev, fs->sb->itbl_start + inode->ino / BLK_INODES, 1, buf) == -1) {
   1.145 +		free(buf);
   1.146 +		return -1;
   1.147 +	}
   1.148 +	memcpy(buf + inode->ino % BLK_INODES, inode, sizeof *inode);
   1.149 +
   1.150 +	if(blk_write(fs->bdev, fs->sb->itbl_start + inode->ino / BLK_INODES, 1, buf) == -1) {
   1.151 +		free(buf);
   1.152 +		return -1;
   1.153 +	}
   1.154 +	free(buf);
   1.155 +	return 0;
   1.156 +}