fix iget() bug that allocated in-use inode[] entries

1 files changed, 13 insertions, 37 deletions

diff --git a/fs.c b/fs.c
index 37b964d..fbb4a8c 100644
--- a/fs.c
+++ b/fs.c
@@ -54,7 +54,6 @@ balloc(uint dev)
   if (b >= size)
     panic("balloc: out of blocks\n");
 
-  cprintf ("balloc: allocate block %d\n", b);
   bp->data[bi/8] |= 0x1 << (bi % 8);
   bwrite (bp, BBLOCK(b, ninodes));  // mark it allocated on disk
   brelse(bp);
@@ -70,7 +69,6 @@ bfree(int dev, uint b)
   int ninodes;
   uchar m;
 
-  cprintf ("bfree: free block %d\n", b);
   bp = bread(dev, 1);
   sb = (struct superblock *) bp->data;
   ninodes = sb->ninodes;
@@ -93,13 +91,14 @@ bfree(int dev, uint b)
 struct inode *
 iget(uint dev, uint inum)
 {
-  struct inode *ip, *nip = 0;
+  struct inode *ip, *nip;
   struct dinode *dip;
   struct buf *bp;
 
   acquire(&inode_table_lock);
 
  loop:
+  nip = 0;
   for(ip = &inode[0]; ip < &inode[NINODE]; ip++){
     if(ip->count > 0 && ip->dev == dev && ip->inum == inum){
       if(ip->busy){
@@ -180,11 +179,9 @@ ialloc(uint dev, short type)
     brelse(bp);
   }
  
-  if (inum >= ninodes) {
+  if (inum >= ninodes) 
     panic ("ialloc: no inodes left\n");
-  }
 
-  cprintf ("ialloc: %d\n", inum);
   dip->type = type;
   bwrite (bp, IBLOCK(inum));   // mark it allocated on the disk
   brelse(bp);
@@ -195,7 +192,6 @@ ialloc(uint dev, short type)
 static void
 ifree(struct inode *ip)
 {
-  cprintf("ifree: %d\n", ip->inum);
   ip->type = 0;
   iupdate(ip);
 }
@@ -220,7 +216,7 @@ ilock(struct inode *ip)
 void
 iunlock(struct inode *ip)
 {
-  if(ip->busy != 1)
+  if(ip->busy != 1 || ip->count < 1)
     panic("iunlock");
 
   acquire(&inode_table_lock);
@@ -271,7 +267,7 @@ iput(struct inode *ip)
   if(ip->count < 1 || ip->busy != 1)
     panic("iput");
 
-  if ((ip->count <= 1) && (ip->nlink <= 0)) 
+  if ((ip->count == 1) && (ip->nlink == 0)) 
     iunlink(ip);
 
   acquire(&inode_table_lock);
@@ -498,8 +494,6 @@ mknod(char *cp, short type, short major, short minor)
 {
   struct inode *ip, *dp;
 
-  cprintf("mknod: %s %d %d %d\n", cp, type, major, minor);
-
   if ((dp = namei(cp, NAMEI_CREATE, 0)) == 0)
     return 0;
 
@@ -525,24 +519,17 @@ unlink(char *cp)
 {
   struct inode *ip, *dp;
   struct dirent de;
-  uint off, inum, cc;
+  uint off, inum, dev;
   
-  cprintf("unlink(%s)\n", cp);
-
-  if ((dp = namei(cp, NAMEI_DELETE, &off)) == 0) {
-    cprintf("unlink(%s) it doesn't exist\n", cp);
+  if ((dp = namei(cp, NAMEI_DELETE, &off)) == 0)
     return -1;
-  }
 
-  if((cc = readi(dp, (char*)&de, off, sizeof(de))) != sizeof(de) ||
-     de.inum == 0){
-    cprintf("off %d dp->size %d cc %d de.inum %d",
-            off, dp->size, cc, de.inum);
+  dev = dp->dev;
+
+  if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de) || de.inum == 0)
     panic("unlink no entry");
-  }
+
   inum = de.inum;
-  cprintf("dinum %d off %d de %s/%d\n", 
-          dp->inum, off, de.name, de.inum);
 
   memset(&de, 0, sizeof(de));
   if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
@@ -551,9 +538,7 @@ unlink(char *cp)
   iupdate(dp);
   iput(dp);
 
-  ip = iget(dp->dev, inum);
-  if(ip == 0)
-    panic("unlink no inode");
+  ip = iget(dev, inum);
 
   ip->nlink--;
 
@@ -568,14 +553,9 @@ link(char *name1, char *name2)
 {
   struct inode *ip, *dp;
 
-  cprintf("link(%s, %s)\n", name1, name2);
-
-  if ((ip = namei(name1, NAMEI_LOOKUP, 0)) == 0){
-    cprintf("  failed %s does not exist\n", name1);
+  if ((ip = namei(name1, NAMEI_LOOKUP, 0)) == 0)
     return -1;
-  }
   if(ip->type == T_DIR){
-    cprintf("  failed %s is a dir\n", name1);
     iput(ip);
     return -1;
   }
@@ -583,12 +563,10 @@ link(char *name1, char *name2)
   iunlock(ip);
 
   if ((dp = namei(name2, NAMEI_CREATE, 0)) == 0) {
-    cprintf("  failed %s exists\n", name2);
     idecref(ip);
     return -1;
   }
   if(dp->dev != ip->dev){
-    cprintf("  cross-device link\n");
     idecref(ip);
     iput(dp);
     return -1;
@@ -602,7 +580,5 @@ link(char *name1, char *name2)
   iput(dp);
   iput(ip);
 
-  cprintf("  succeeded\n");
-
   return 0;
 }