Acquire inode ref before checking if inode is valid

42508b84 · Silas Boyd-Wickizer · 75c0ef4a · 42508b84
--- a/kernel/fs.cc
+++ b/kernel/fs.cc
@@ -189,6 +189,7 @@ ialloc(u32 dev, short type)
      // maybe this inode is free. look at it via the
      // inode cache to make sure.
      struct inode *ip = iget(dev, inum);
+      assert(ip->valid());
      ilock(ip, 1);
      if(ip->type == 0){
        ip->type = type;
@@ -263,17 +264,17 @@ iget(u32 dev, u32 inum)
    scoped_gc_epoch e;
    struct inode *ip = ins->lookup(make_pair(dev, inum));
    if (ip) {
+      if (ip->tryinc()) {
        if (!(ip->flags & I_VALID)) {
          acquire(&ip->lock);
          while((ip->flags & I_VALID) == 0)
            cv_sleep(&ip->cv, &ip->lock);
          release(&ip->lock);
        }
-      
-      if (ip->tryinc())
        return ip;
      }
    }
+  }
  
  // Allocate fresh inode cache slot.
  struct inode *ip = inode::alloc(dev, inum);