lfs.c

早期freebsd实现

	/* 
	 * Initialize dynamic accounting.  The blocks available for
	 * writing are the bfree blocks minus 1 segment summary for
	 * each segment since you can't write any new data without
	 * creating a segment summary - 2 segments that the cleaner
	 * needs.
	 */
	lfsp->lfs_avail = lfsp->lfs_bfree - lfsp->lfs_nseg - 
		fsbtodb(lfsp, 2 * lfsp->lfs_ssize);
	lfsp->lfs_uinodes = 0;
	/*
	 * Ready to start writing segments.  The first segment is different
	 * because it contains the segment usage table and the ifile inode
	 * as well as a superblock.  For the rest of the segments, set the 
	 * time stamp to be 0 so that the first segment is the most recent.
	 * For each segment that is supposed to contain a copy of the super
	 * block, initialize its first few blocks and its segment summary 
	 * to indicate this.
	 */
	lfsp->lfs_nfiles = LFS_FIRST_INUM - 1;
	lfsp->lfs_cksum = 
	    cksum(lfsp, sizeof(struct lfs) - sizeof(lfsp->lfs_cksum));

	/* Now create a block of disk inodes */
	if (!(dpagep = malloc(lfsp->lfs_bsize)))
		fatal("%s", strerror(errno));
	dip = (struct dinode *)dpagep;
	bzero(dip, lfsp->lfs_bsize);

	/* Create a block of IFILE structures. */
	if (!(ipagep = malloc(lfsp->lfs_bsize)))
		fatal("%s", strerror(errno));
	ifile = (IFILE *)ipagep;

	/* 
	 * Initialize IFILE.  It is the next block following the
	 * block of inodes (whose address has been calculated in
	 * lfsp->lfs_idaddr;
	 */
	sb_addr = lfsp->lfs_idaddr + lfsp->lfs_bsize / lp->d_secsize;
	sb_addr = make_dinode(LFS_IFILE_INUM, dip, 
	    lfsp->lfs_cleansz + lfsp->lfs_segtabsz+1, sb_addr, lfsp);
	dip->di_mode = IFREG|IREAD|IWRITE;
	ip = &ifile[LFS_IFILE_INUM];
	ip->if_version = 1;
	ip->if_daddr = lfsp->lfs_idaddr;

	/* Initialize the ROOT Directory */
	sb_addr = make_dinode(ROOTINO, ++dip, 1, sb_addr, lfsp);
	dip->di_mode = IFDIR|IREAD|IWRITE|IEXEC;
	dip->di_size = DIRBLKSIZ;
	dip->di_nlink = 3;
	ip = &ifile[ROOTINO];
	ip->if_version = 1;
	ip->if_daddr = lfsp->lfs_idaddr;

	/* Initialize the lost+found Directory */
	sb_addr = make_dinode(LOSTFOUNDINO, ++dip, 1, sb_addr, lfsp);
	dip->di_mode = IFDIR|IREAD|IWRITE|IEXEC;
	dip->di_size = DIRBLKSIZ;
	dip->di_nlink = 2;
	ip = &ifile[LOSTFOUNDINO];
	ip->if_version = 1;
	ip->if_daddr = lfsp->lfs_idaddr;

	/* Make all the other dinodes invalid */
	for (i = INOPB(lfsp)-3, dip++; i; i--, dip++)
		dip->di_inumber = LFS_UNUSED_INUM;
	

	/* Link remaining IFILE entries in free list */
	for (ip = &ifile[LFS_FIRST_INUM], i = LFS_FIRST_INUM; 
	    i < lfsp->lfs_ifpb; ++ip) {
		ip->if_version = 1;
		ip->if_daddr = LFS_UNUSED_DADDR;
		ip->if_nextfree = ++i;
	}
	ifile[lfsp->lfs_ifpb - 1].if_nextfree = LFS_UNUSED_INUM;

	/* Now, write the segment */

	/* Compute a checksum across all the data you're writing */
	dp = datasump = malloc (blocks_used * sizeof(u_long));
	*dp++ = ((u_long *)dpagep)[0];		/* inode block */
	for (i = 0; i < lfsp->lfs_cleansz; i++)
		*dp++ = ((u_long *)cleaninfo)[(i << lfsp->lfs_bshift) / 
		    sizeof(u_long)];		/* Cleaner info */
	for (i = 0; i < lfsp->lfs_segtabsz; i++)
		*dp++ = ((u_long *)segtable)[(i << lfsp->lfs_bshift) / 
		    sizeof(u_long)];		/* Segusage table */
	*dp++ = ((u_long *)ifile)[0];		/* Ifile */

	/* Still need the root and l+f bytes; get them later */

	/* Write out the inode block */
	off = LFS_LABELPAD + LFS_SBPAD + LFS_SUMMARY_SIZE;
	put(fd, off, dpagep, lfsp->lfs_bsize);
	free(dpagep);
	off += lfsp->lfs_bsize;

	/* Write out the ifile */

	put(fd, off, cleaninfo, lfsp->lfs_cleansz << lfsp->lfs_bshift);
	off += (lfsp->lfs_cleansz << lfsp->lfs_bshift);
	(void)free(cleaninfo);

	put(fd, off, segtable, lfsp->lfs_segtabsz << lfsp->lfs_bshift);
	off += (lfsp->lfs_segtabsz << lfsp->lfs_bshift);
	(void)free(segtable);

	put(fd, off, ifile, lfsp->lfs_bsize);
	off += lfsp->lfs_bsize;

	/*
	 * use ipagep for space for writing out other stuff.  It used to 
	 * contain the ifile, but we're done with it.
	 */

	/* Write out the root and lost and found directories */
	bzero(ipagep, lfsp->lfs_bsize);
	make_dir(ipagep, lfs_root_dir, 
	    sizeof(lfs_root_dir) / sizeof(struct direct));
	*dp++ = ((u_long *)ipagep)[0];
	put(fd, off, ipagep, lfsp->lfs_bsize);
	off += lfsp->lfs_bsize;

	bzero(ipagep, lfsp->lfs_bsize);
	make_dir(ipagep, lfs_lf_dir, 
		sizeof(lfs_lf_dir) / sizeof(struct direct));
	*dp++ = ((u_long *)ipagep)[0];
	put(fd, off, ipagep, lfsp->lfs_bsize);

	/* Write Supberblock */
	lfsp->lfs_offset = (off + lfsp->lfs_bsize) / lp->d_secsize;
	put(fd, LFS_LABELPAD, lfsp, sizeof(struct lfs));

	/* 
	 * Finally, calculate all the fields for the summary structure
	 * and write it.
	 */

	summary.ss_next = lfsp->lfs_nextseg;
	summary.ss_create = lfsp->lfs_tstamp;
	summary.ss_nfinfo = 3;
	summary.ss_ninos = 3;
	summary.ss_datasum = cksum(datasump, sizeof(u_long) * blocks_used);

	/*
	 * Make sure that we don't overflow a summary block. We have to
	 * record: FINFO structures for ifile, root, and l+f.  The number
	 * of blocks recorded for the ifile is determined by the size of
	 * the cleaner info and the segments usage table.  There is room
	 * for one block included in sizeof(FINFO) so we don't need to add
	 * any extra space for the ROOT and L+F, and one block of the ifile
	 * is already counted.  Finally, we leave room for 1 inode block
	 * address.
	 */
	sum_size = 3*sizeof(FINFO) + sizeof(SEGSUM) + sizeof(daddr_t) +
	    (lfsp->lfs_cleansz + lfsp->lfs_segtabsz) * sizeof(u_long);
#define	SUMERR \
"Multiple summary blocks in segment 1 not yet implemented\nsummary is %d bytes."
	if (sum_size > LFS_SUMMARY_SIZE)
		fatal(SUMERR, sum_size);

		block_array_size = lfsp->lfs_cleansz + lfsp->lfs_segtabsz + 1;

	if (!(block_array = malloc(block_array_size *sizeof(int))))
		fatal("%s: %s", special, strerror(errno));

	/* fill in the array */
	for (i = 0; i < block_array_size; i++)
		block_array[i] = i;

	/* copy into segment */
	sump = ipagep;
	bcopy(&summary, sump, sizeof(SEGSUM));
	sump += sizeof(SEGSUM);

	/* Now, add the ifile */
	file_info.fi_nblocks = block_array_size;
	file_info.fi_version = 1;
	file_info.fi_ino = LFS_IFILE_INUM;

	bcopy(&file_info, sump, sizeof(FINFO) - sizeof(u_long));
	sump += sizeof(FINFO) - sizeof(u_long);
	bcopy(block_array, sump, sizeof(u_long) * file_info.fi_nblocks);
	sump += sizeof(u_long) * file_info.fi_nblocks;

	/* Now, add the root directory */
	file_info.fi_nblocks = 1;
	file_info.fi_version = 1;
	file_info.fi_ino = ROOTINO;
	file_info.fi_blocks[0] = 0;
	bcopy(&file_info, sump, sizeof(FINFO));
	sump += sizeof(FINFO);

	/* Now, add the lost and found */
	file_info.fi_ino = LOSTFOUNDINO;
	bcopy(&file_info, sump, sizeof(FINFO));

	((daddr_t *)ipagep)[LFS_SUMMARY_SIZE / sizeof(daddr_t) - 1] = 
	    lfsp->lfs_idaddr;
	((SEGSUM *)ipagep)->ss_sumsum = cksum(ipagep+sizeof(summary.ss_sumsum), 
	    LFS_SUMMARY_SIZE - sizeof(summary.ss_sumsum));
	put(fd, LFS_LABELPAD + LFS_SBPAD, ipagep, LFS_SUMMARY_SIZE);

	sp = (SEGSUM *)ipagep;
	sp->ss_create = 0;
	sp->ss_nfinfo = 0;
	sp->ss_ninos = 0;
	sp->ss_datasum = 0;

	/* Now write the summary block for the next partial so it's invalid */
	lfsp->lfs_tstamp = 0;
	off += lfsp->lfs_bsize;
	sp->ss_sumsum =
	    cksum(&sp->ss_datasum, LFS_SUMMARY_SIZE - sizeof(sp->ss_sumsum));
	put(fd, off, sp, LFS_SUMMARY_SIZE);

	/* Now, write rest of segments containing superblocks */
	lfsp->lfs_cksum = 
	    cksum(lfsp, sizeof(struct lfs) - sizeof(lfsp->lfs_cksum));
	for (seg_addr = last_addr = lfsp->lfs_sboffs[0], j = 1, i = 1; 
	    i < lfsp->lfs_nseg; i++) {

		seg_addr += lfsp->lfs_ssize << lfsp->lfs_fsbtodb;
		sp->ss_next = last_addr;
		last_addr = seg_addr;
		seg_seek = seg_addr * lp->d_secsize;

		if (seg_addr == lfsp->lfs_sboffs[j]) {
			if (j < (LFS_MAXNUMSB - 2))
				j++;
			put(fd, seg_seek, lfsp, sizeof(struct lfs));
			seg_seek += LFS_SBPAD;
		} 

		/* Summary */
		sp->ss_sumsum = cksum(&sp->ss_datasum, 
		    LFS_SUMMARY_SIZE - sizeof(sp->ss_sumsum));
		put(fd, seg_seek, sp, LFS_SUMMARY_SIZE);
	}
	free(ipagep);
	close(fd);
	return (0);
}

static void
put(fd, off, p, len)
	int fd;
	off_t off;
	void *p;
	size_t len;
{
	int wbytes;

	if (lseek(fd, off, SEEK_SET) < 0)
		fatal("%s: %s", special, strerror(errno));
	if ((wbytes = write(fd, p, len)) < 0)
		fatal("%s: %s", special, strerror(errno));
	if (wbytes != len)
		fatal("%s: short write (%d, not %d)", special, wbytes, len);
}

/*
 * Create the root directory for this file system and the lost+found
 * directory.
 */

	u_long	d_ino;			/* inode number of entry */
	u_short	d_reclen;		/* length of this record */
	u_short	d_namlen;		/* length of string in d_name */
	char	d_name[MAXNAMLEN + 1];	/* name with length <= MAXNAMLEN */
void
lfsinit()
{}

static daddr_t
make_dinode(ino, dip, nblocks, saddr, lfsp)
	ino_t ino;				/* inode we're creating */
	struct dinode *dip;			/* disk inode */
	int nblocks;				/* number of blocks in file */
	daddr_t saddr;				/* starting block address */
	struct lfs *lfsp;			/* superblock */
{
	int db_per_fb, i;

	dip->di_nlink = 1;
	dip->di_blocks = nblocks << lfsp->lfs_fsbtodb;

	dip->di_size = (nblocks << lfsp->lfs_bshift);
	dip->di_atime.ts_sec = dip->di_mtime.ts_sec =
	    dip->di_ctime.ts_sec = lfsp->lfs_tstamp;
	dip->di_atime.ts_nsec = dip->di_mtime.ts_nsec =
	    dip->di_ctime.ts_nsec = 0;
	dip->di_inumber = ino;

#define	SEGERR \
"File requires more than the number of direct blocks; increase block or segment size."
	if (NDADDR < nblocks)
		fatal("%s", SEGERR);

	/* Assign the block addresses for the ifile */
	db_per_fb = 1 << lfsp->lfs_fsbtodb;
	for (i = 0; i < nblocks; i++, saddr += db_per_fb)
		dip->di_db[i] = saddr;

	return (saddr);
}


/*
 * Construct a set of directory entries in "bufp".  We assume that all the
 * entries in protodir fir in the first DIRBLKSIZ.  
 */
static void
make_dir(bufp, protodir, entries)
	void *bufp;
	register struct direct *protodir;
	int entries;
{
	char *cp;
	int i, spcleft;

	spcleft = DIRBLKSIZ;
	for (cp = bufp, i = 0; i < entries - 1; i++) {
		protodir[i].d_reclen = DIRSIZ(NEWDIRFMT, &protodir[i]);
		bcopy(&protodir[i], cp, protodir[i].d_reclen);
		cp += protodir[i].d_reclen;
		if ((spcleft -= protodir[i].d_reclen) < 0)
			fatal("%s: %s", special, "directory too big");
	}
	protodir[i].d_reclen = spcleft;
	bcopy(&protodir[i], cp, DIRSIZ(NEWDIRFMT, &protodir[i]));
}