Pick up where i left off in april:

- move log into metadata part of disk, so that marking
that the log's blocks are in use falls out for free
- superblock describes the whole disk (sizes and offets)
- sizes and offsets are computed in one place (mkfs) and
the rest of the code refers to the superblock for these values,
instead of recomputing them.

1 files changed, 12 insertions, 14 deletions

diff --git a/fs.c b/fs.c
index 286252d..025b326 100644
--- a/fs.c
+++ b/fs.c
@@ -22,6 +22,7 @@
 
 #define min(a, b) ((a) < (b) ? (a) : (b))
 static void itrunc(struct inode*);
+struct superblock sb;   // there should be one per dev, but we run with one dev
 
 // Read the super block.
 void
@@ -54,12 +55,10 @@ balloc(uint dev)
 {
   int b, bi, m;
   struct buf *bp;
-  struct superblock sb;
 
   bp = 0;
-  readsb(dev, &sb);
   for(b = 0; b < sb.size; b += BPB){
-    bp = bread(dev, BBLOCK(b, sb.ninodes));
+    bp = bread(dev, BBLOCK(b, sb));
     for(bi = 0; bi < BPB && b + bi < sb.size; bi++){
       m = 1 << (bi % 8);
       if((bp->data[bi/8] & m) == 0){  // Is block free?
@@ -80,11 +79,10 @@ static void
 bfree(int dev, uint b)
 {
   struct buf *bp;
-  struct superblock sb;
   int bi, m;
 
   readsb(dev, &sb);
-  bp = bread(dev, BBLOCK(b, sb.ninodes));
+  bp = bread(dev, BBLOCK(b, sb));
   bi = b % BPB;
   m = 1 << (bi % 8);
   if((bp->data[bi/8] & m) == 0)
@@ -101,8 +99,8 @@ bfree(int dev, uint b)
 // its size, the number of links referring to it, and the
 // list of blocks holding the file's content.
 //
-// The inodes are laid out sequentially on disk immediately after
-// the superblock. Each inode has a number, indicating its
+// The inodes are laid out sequentially on disk at
+// sb.startinode. Each inode has a number, indicating its
 // position on the disk.
 //
 // The kernel keeps a cache of in-use inodes in memory
@@ -162,9 +160,12 @@ struct {
 } icache;
 
 void
-iinit(void)
+iinit(int dev)
 {
   initlock(&icache.lock, "icache");
+  readsb(dev, &sb);
+  cprintf("sb: size %d nblocks %d ninodes %d nlog %d logstart %d inodestart %d bmap start %d\n", sb.size,
+          sb.nblocks, sb.ninodes, sb.nlog, sb.logstart, sb.inodestart, sb.bmapstart);
 }
 
 static struct inode* iget(uint dev, uint inum);
@@ -178,12 +179,9 @@ ialloc(uint dev, short type)
   int inum;
   struct buf *bp;
   struct dinode *dip;
-  struct superblock sb;
-
-  readsb(dev, &sb);
 
   for(inum = 1; inum < sb.ninodes; inum++){
-    bp = bread(dev, IBLOCK(inum));
+    bp = bread(dev, IBLOCK(inum, sb));
     dip = (struct dinode*)bp->data + inum%IPB;
     if(dip->type == 0){  // a free inode
       memset(dip, 0, sizeof(*dip));
@@ -204,7 +202,7 @@ iupdate(struct inode *ip)
   struct buf *bp;
   struct dinode *dip;
 
-  bp = bread(ip->dev, IBLOCK(ip->inum));
+  bp = bread(ip->dev, IBLOCK(ip->inum, sb));
   dip = (struct dinode*)bp->data + ip->inum%IPB;
   dip->type = ip->type;
   dip->major = ip->major;
@@ -281,7 +279,7 @@ ilock(struct inode *ip)
   release(&icache.lock);
 
   if(!(ip->flags & I_VALID)){
-    bp = bread(ip->dev, IBLOCK(ip->inum));
+    bp = bread(ip->dev, IBLOCK(ip->inum, sb));
     dip = (struct dinode*)bp->data + ip->inum%IPB;
     ip->type = dip->type;
     ip->major = dip->major;