diff --git a/tools/mkfs.c b/tools/mkfs.c
index 78eb260..eee942c 100644
--- a/tools/mkfs.c
+++ b/tools/mkfs.c
@@ -8,8 +8,8 @@
  *	 ensure that swap is not used on RF disk images.
  *	 deal with errors instead of exiting :-)
  *
- * $Revision: 1.18 $
- * $Date: 2008/05/04 09:07:54 $
+ * $Revision: 1.17 $
+ * $Date: 2008/05/04 14:20:12 $
  */
 
 int debug=1;
@@ -55,7 +55,7 @@ struct v1inode {		/* Format of 1st edition i-node */
 
 /*
  * We build directories with certain limitations: first, they are all
- * directories under /; second, most of them occupy 4 contiguous disk blocks,
+ * directories under /; second, they all occupy 4 contiguous disk blocks,
  * giving us up to 64 directory entries.
  */
 #define DIRBLOCKS	4
@@ -68,8 +68,10 @@ struct v1dirent {		/* Format of 1st edition dir entry */
 
 struct directory {		/* Internal structure for each dir */
   uint16_t block;		/* Starting block */
+  uint16_t inum;		/* I-node number used by this dir */
   int numentries;		/* Number of entries in entry[] */
-  struct v1dirent *entry;	/* calloc'd later to be an array */
+  int nextfree;			/* Next free entry */
+  struct v1dirent *entry;
 };
 
 unsigned char buf[BLKSIZE];	/* A block buffer */
@@ -107,7 +109,7 @@ void write_superblock(void)
   if (debug)
     printf("Writing %d inodes, each size %d, total %d\n",
 	icount, sizeof(struct v1inode), icount * sizeof(struct v1inode));
-  fwrite(inodelist, sizeof(struct v1inode), icount, diskfh);
+  fwrite(&inodelist[1], sizeof(struct v1inode), icount-1, diskfh);
   if (debug) {
     long posn= ftell(diskfh);
     long block= posn/BLKSIZE;
@@ -178,8 +180,6 @@ int alloc_blocks(int n)
 /* Add a filename and i-number to the given directory */
 void add_direntry(struct directory *d, uint16_t inum, char *name)
 {
-  int i;
-
   if (d == NULL) {
     printf("I need a struct directory * please\n"); exit(1);
   }
@@ -194,23 +194,18 @@ void add_direntry(struct directory *d, uint16_t inum, char *name)
   }
 
   /* Find an entry in the directory which is empty */
-  for (i = 0; i < d->numentries; i++) {
-    if (d->entry[i].inode == 0) {
-      d->entry[i].inode = inum;
-      strncpy(d->entry[i].name, name, 8);
-      return;
-    }
+  if (d->nextfree >= d->numentries) {
+    printf("Unable to add directory entry\n"); exit(1);
   }
-
-  printf("Unable to add directory entry\n"); exit(1);
+  d->entry[d->nextfree].inode = inum;
+  strncpy(d->entry[d->nextfree].name, name, 8);
+  d->nextfree++;
 }
 
 /*
  * Create a directory with the given name. Allocate an i-node for it, and a
  * set of blocks. Attach it to /. Return the struct allocated. If name is
- * "/", we are making the root directory itself. numblocks is the number of
- * disk blocks the dir will occupy, normally this is DIRBLOCKS, but / and
- * /dev only need 1 block each.
+ * "/", we are making the root directory itself.
  */
 struct directory *create_dir(char *name, int numblocks)
 {
@@ -228,26 +223,23 @@ struct directory *create_dir(char *name, int numblocks)
 
   d = (struct directory *)calloc(1, sizeof(struct directory));
   d->numentries= numblocks * DIRENTPERBLOCK;
+  d->nextfree= 0;
   d->entry= (struct v1dirent *)calloc(d->numentries, sizeof(struct v1dirent));
 
   /* Allocate an i-node and some blocks for the directory */
-  /* / always gets ROOTDIR_INUM; other dirs get allocated an inode number */
   if (strcmp(name, "/")) inum = alloc_inode();
   else inum = ROOTDIR_INUM;
   d->block = alloc_blocks(numblocks);
-  if (debug) printf("In create_dir, got back block %d, %d config blks\n",
-			d->block, numblocks);
+  d->inum= inum;
+  if (debug) printf("In create_dir, got back inum %d blk %d, %d config blks\n",
+			inum, d->block, numblocks);
 
-  /* Mark the i-node as a directory. Set the number of links to default 2 */
-  /* (. and the root entry), set the directory size, and write the number */
-  /* of blocks occupied into the directory's i-node. */
-  inodelist[inum].flags |= I_DIR | I_UREAD | I_UWRITE | I_OREAD | I_OWRITE;
-  inodelist[inum].nlinks= 2;
-  inodelist[inum].size= numblocks * BLKSIZE;
+  /* Mark the i-node as a directory */
+  inodelist[inum].flags |= I_DIR | I_UREAD | I_UWRITE | I_OREAD;
+  inodelist[inum].nlinks= 2;	/* Size is determined at write-time */
   for (i=0, blk=d->block; i < numblocks; i++, blk++)
     inodelist[inum].block[i]= blk;
 
-
   /* If the directory is not /, attach it to rootdir */
   if (strcmp(name, "/")) {
     add_direntry(rootdir, inum, name);
@@ -272,10 +264,13 @@ void write_dir(struct directory *d, char *name)
   }
 
   if (debug)
-    printf("Writing dir %s of %d blocks from block %d (offset 0x%x) on\n",
-			name, d->numentries / DIRENTPERBLOCK, d->block,
+    printf("Writing dir %s, size %d, %d blks from block %d (offset 0x%x) on\n",
+			name, d->numentries * sizeof(struct v1dirent),
+			d->numentries / DIRENTPERBLOCK, d->block,
 			d->block * BLKSIZE);
 
+  /* Directory size is the # of bytes of the in-use directory entries */
+  inodelist[d->inum].size= d->nextfree * sizeof(struct v1dirent);
   fseek(diskfh, d->block * BLKSIZE, SEEK_SET);
   fwrite(d->entry, d->numentries * sizeof(struct v1dirent), 1, diskfh);
 }
@@ -364,7 +359,7 @@ void add_files(char *basedir, char *dir)
     printf("Cannot opendir %s\n", fullname); exit(1);
   }
 
-  /* Create the image directory with a default number of blocks */
+  /* Create the image directory */
   d = create_dir(dir, DIRBLOCKS);
 
   /* Walk the directory */
@@ -586,12 +581,12 @@ int main(int argc, char *argv[])
   /* Walk the top directory argument, dealing with the subdirs */
   process_topdir(argv[1]);
 
-  /* Write out the superblock and i-nodes */
-  write_superblock();
-
   /* Write out the root directory */
   write_dir(rootdir, "/");
 
+  /* Write out the superblock and i-nodes */
+  write_superblock();
+
   fclose(diskfh);
   exit(0);
 }