free inode only when noone is holding a pointer to it. should fix open-unlink-

read problem, but untested

free inode only when noone is holding a pointer to it. should fix open-unlink-
22bac2cb · kaashoek · 14938f93 · 22bac2cb
--- a/fs.c
+++ b/fs.c
@@ -226,6 +226,38 @@ iunlock(struct inode *ip)
  release(&inode_table_lock);
 }

+uint
+bmap(struct inode *ip, uint bn)
+{
+  unsigned x;
+
+  if(bn >= NDIRECT)
+    panic("bmap 1");
+  x = ip->addrs[bn];
+  if(x == 0)
+    panic("bmap 2");
+  return x;
+}
+
+void 
+iunlink(struct inode *ip)
+{
+  int i;
+
+  // free inode, its blocks, and remove dir entry
+  for (i = 0; i < NDIRECT; i++) {
+    if (ip->addrs[i] != 0) {
+      bfree(ip->dev, ip->addrs[i]);
+      ip->addrs[i] = 0;
+    }
+  }
+  ip->size = 0;
+  ip->major = 0;
+  ip->minor = 0;
+  iupdate(ip);
+  ifree(ip);  // is this the right order?
+}
+
 // caller is releasing a reference to this inode.
 // you must have the inode lock.
 void
@@ -234,6 +266,9 @@ iput(struct inode *ip)
  if(ip->count < 1 || ip->busy != 1)
    panic("iput");

+  if ((ip->count <= 1) && (ip->nlink <= 0)) 
+    iunlink(ip);
+
  acquire(&inode_table_lock);

  ip->count -= 1;
@@ -256,21 +291,6 @@ idecref(struct inode *ip)
  release(&inode_table_lock);
 }

-uint
-bmap(struct inode *ip, uint bn)
-{
-  unsigned x;
-
-  if(bn >= NDIRECT)
-    panic("bmap 1");
-  x = ip->addrs[bn];
-  if(x == 0)
-    panic("bmap 2");
-  return x;
-}
-
-#define min(a, b) ((a) < (b) ? (a) : (b))
-
 void
 stati(struct inode *ip, struct stat *st)
 {
@@ -281,6 +301,8 @@ stati(struct inode *ip, struct stat *st)
  st->st_size = ip->size;
 }

+#define min(a, b) ((a) < (b) ? (a) : (b))
+
 int
 readi(struct inode *ip, char *dst, uint off, uint n)
 {
@@ -307,8 +329,6 @@ readi(struct inode *ip, char *dst, uint off, uint n)
  return target - n;
 }

-#define MIN(a, b) ((a < b) ? a : b)
-
 int
 writei(struct inode *ip, char *addr, uint off, uint n)
 {
@@ -330,7 +350,7 @@ writei(struct inode *ip, char *addr, uint off, uint n)
 	if (b <= 0) return r;
 	ip->addrs[lbn] = b;
      }
-      m = MIN(BSIZE - off % BSIZE, n-r);
+      m = min(BSIZE - off % BSIZE, n-r);
      bp = bread(ip->dev, bmap(ip, off / BSIZE));
      memmove (bp->data + off % BSIZE, addr, m);
      bwrite (ip->dev, bp, bmap(ip, off/BSIZE));
@@ -476,12 +496,13 @@ mknod(char *cp, short type, short major, short minor)
 int
 unlink(char *cp)
 {
-  int i;
-  struct inode *ip, *dp;
+  struct inode *ip;
+  struct inode *dp;
  struct dirent *ep = 0;
  int off;
  struct buf *bp = 0;
  uint pinum;
+
  
  if ((ip = namei(cp, &pinum)) == 0) {
    cprintf("file to be unlinked doesn't exist\n");
@@ -490,24 +511,10 @@ unlink(char *cp)

  ip->nlink--;
  if (ip->nlink > 0) {
-    iupdate(ip);
-    iput(ip); // is this the right order?
+    iput(ip);
    return 0;
  }

-  // free inode, its blocks, and remove dir entry
-  for (i = 0; i < NDIRECT; i++) {
-    if (ip->addrs[i] != 0) {
-      bfree(ip->dev, ip->addrs[i]);
-      ip->addrs[i] = 0;
-    }
-  }
-  ip->size = 0;
-  ip->major = 0;
-  ip->minor = 0;
-  iupdate(ip);
-  ifree(ip);  // is this the right order?
-
  dp = iget(rootdev, pinum);
  for(off = 0; off < dp->size; off += BSIZE) {
    bp = bread(dp->dev, bmap(dp, off / BSIZE));
@@ -526,8 +533,8 @@ unlink(char *cp)
  ep->inum = 0;
  bwrite (dp->dev, bp, bmap(dp, off/BSIZE));   // write directory block
  brelse(bp);
-  iput(ip);
  iupdate (dp);
  iput(dp);
+  iput(ip);
  return 0;
 }