various cleanups

7d4aef6c · rsc · b6095304 · 7d4aef6c
--- a/fs.c
+++ b/fs.c
@@ -41,13 +41,9 @@ iinit(void)
 static uint
 balloc(uint dev)
 {
-  int b;
+  int b, bi, m, ninodes, size;
  struct buf *bp;
  struct superblock *sb;
-  int bi = 0;
-  int size;
-  int ninodes;
-  uchar m;

  bp = bread(dev, 1);
  sb = (struct superblock*) bp->data;
@@ -62,16 +58,13 @@ balloc(uint dev)
    bi = b % BPB;
    m = 0x1 << (bi % 8);
    if((bp->data[bi/8] & m) == 0) {  // is block free?
-      break;
-    }
-  }
-  if(b >= size)
-    panic("balloc: out of blocks");
-
      bp->data[bi/8] |= 0x1 << (bi % 8);
      bwrite(bp, BBLOCK(b, ninodes));  // mark it allocated on disk
      brelse(bp);
      return b;
+    }
+  }
+  panic("balloc: out of blocks");
 }

 // Free a disk block.
@@ -80,9 +73,7 @@ bfree(int dev, uint b)
 {
  struct buf *bp;
  struct superblock *sb;
-  int bi;
-  int ninodes;
-  uchar m;
+  int bi, m, ninodes;

  bp = bread(dev, 1);
  sb = (struct superblock*) bp->data;
@@ -96,8 +87,8 @@ bfree(int dev, uint b)

  bp = bread(dev, BBLOCK(b, ninodes));
  bi = b % BPB;
-  m = ~(0x1 << (bi %8));
-  bp->data[bi/8] &= m;
+  m = 0x1 << (bi % 8);
+  bp->data[bi/8] &= ~m;
  bwrite(bp, BBLOCK(b, ninodes));  // mark it free on disk
  brelse(bp);
 }
@@ -176,7 +167,7 @@ iupdate(struct inode *ip)
  dip->nlink = ip->nlink;
  dip->size = ip->size;
  memmove(dip->addrs, ip->addrs, sizeof(ip->addrs));
-  bwrite(bp, IBLOCK(ip->inum));   // mark it allocated on the disk
+  bwrite(bp, IBLOCK(ip->inum));
  brelse(bp);
 }

@@ -186,7 +177,7 @@ struct inode*
 ialloc(uint dev, short type)
 {
  struct inode *ip;
-  struct dinode *dip = 0;
+  struct dinode *dip;
  struct superblock *sb;
  int ninodes;
  int inum;
@@ -290,12 +281,13 @@ itrunc(struct inode *ip)
 {
  int i, j;
  struct buf *inbp;
+  uint *a;

  for(i = 0; i < NADDRS; i++) {
    if(ip->addrs[i] != 0) {
      if(i == INDIRECT) {
        inbp = bread(ip->dev, ip->addrs[INDIRECT]);
-        uint *a = (uint*) inbp->data;
+        a = (uint*)inbp->data;
        for(j = 0; j < NINDIRECT; j++) {
          if(a[j] != 0) {
            bfree(ip->dev, a[j]);
@@ -372,7 +364,7 @@ stati(struct inode *ip, struct stat *st)
 int
 readi(struct inode *ip, char *dst, uint off, uint n)
 {
-  uint target = n, n1;
+  uint target, n1;
  struct buf *bp;

  if(ip->type == T_DEV) {
@@ -381,6 +373,7 @@ readi(struct inode *ip, char *dst, uint off, uint n)
    return devsw[ip->major].read(ip->minor, dst, n);
  }

+  target = n;
  while(n > 0 && off < ip->size){
    bp = bread(ip->dev, bmap(ip, off / BSIZE));
    n1 = min(n, ip->size - off);
@@ -435,16 +428,16 @@ newblock(struct inode *ip, uint lbn)
 int
 writei(struct inode *ip, char *addr, uint off, uint n)
 {
+  struct buf *bp;
+  int r, m, lbn;
+
  if(ip->type == T_DEV) {
    if(ip->major < 0 || ip->major >= NDEV || !devsw[ip->major].write)
      return -1;
    return devsw[ip->major].write(ip->minor, addr, n);
-  } else if(ip->type == T_FILE || ip->type == T_DIR) {
-    struct buf *bp;
-    int r = 0;
-    int m;
-    int lbn;
-    while(r < n) {
+  }
+
+  for(r=0; r<n; ) {
    lbn = off / BSIZE;
    if(lbn >= MAXFILE)
      return r;
@@ -460,20 +453,14 @@ writei(struct inode *ip, char *addr, uint off, uint n)
    r += m;
    off += m;
  }
-    if(r > 0) {
-      if(off > ip->size) {
+  if(r > 0 && off > ip->size) {
    if(ip->type == T_DIR)
      ip->size = ((off / BSIZE) + 1) * BSIZE;
    else
      ip->size = off;
-      }
    iupdate(ip);
  }
  return r;
-  } else {
-    panic("writei: unknown type");
-    return 0;
-  }
 }

 // Skip over the next path element in path,