diff --git a/kernel/file.h b/kernel/file.h
index b076d1d..5c4eb3a 100644
--- a/kernel/file.h
+++ b/kernel/file.h
@@ -26,7 +26,7 @@ struct inode {
   short minor;
   short nlink;
   uint size;
-  uint addrs[NDIRECT+1];
+  uint addrs[NDIRECT+2];
 };
 
 // map major device number to device functions.
diff --git a/kernel/fs.c b/kernel/fs.c
index c6bab15..8c970e6 100644
--- a/kernel/fs.c
+++ b/kernel/fs.c
@@ -416,7 +416,43 @@ bmap(struct inode *ip, uint bn)
     brelse(bp);
     return addr;
   }
-
+  bn -= NINDIRECT;
+  if (bn < NINDIRECT2) {
+    // Load doubly indirect block L1
+    if ((addr = ip->addrs[NDIRECT+1]) == 0){
+      addr = balloc(ip->dev);
+      if(addr == 0)
+        return 0;
+      ip->addrs[NDIRECT+1] = addr;
+    }
+    // load doubly indirect block L2
+    // we have NINDIRECT blocks for per L1 entry
+    bp = bread(ip->dev, addr);
+    a = (uint*)bp->data;
+    if ((addr = a[bn / NINDIRECT]) == 0) {
+      addr = balloc(ip->dev);
+      if (addr == 0) {
+        brelse(bp);
+        return 0;
+      }
+      a[bn / NINDIRECT] = addr;
+      log_write(bp);
+    }
+    brelse(bp);
+    // Load finally the target block
+    bp = bread(ip->dev, addr);
+    a = (uint*)bp->data;
+    if ((addr = a[bn % NINDIRECT]) == 0) {
+      addr = balloc(ip->dev);
+      if (addr) {
+        a[bn % NINDIRECT] = addr;
+        log_write(bp);
+      }
+    }
+    brelse(bp);
+    return addr;
+  }
+  printf("bn=%d\n", bn);
   panic("bmap: out of range");
 }
 
@@ -425,9 +461,9 @@ bmap(struct inode *ip, uint bn)
 void
 itrunc(struct inode *ip)
 {
-  int i, j;
-  struct buf *bp;
-  uint *a;
+  int i, j, k;
+  struct buf *bp, *bp1;
+  uint *a, *a1;
 
   for(i = 0; i < NDIRECT; i++){
     if(ip->addrs[i]){
@@ -448,6 +484,26 @@ itrunc(struct inode *ip)
     ip->addrs[NDIRECT] = 0;
   }
 
+  if (ip->addrs[NDIRECT+1]) {
+    bp = bread(ip->dev, ip->addrs[NDIRECT+1]);
+    a = (uint*)bp->data;
+    for(j = 0; j < NINDIRECT; j++){
+      if(a[j]) {
+        bp1 = bread(ip->dev, a[j]);
+        a1 = (uint*)bp1->data;
+        for (k = 0; k < NINDIRECT; ++ k) {
+          if (a1[k]) {
+            bfree(ip->dev, a1[k]);
+          }
+        }
+        brelse(bp1);
+        bfree(ip->dev, a[j]);
+      }
+    }
+    brelse(bp);
+    bfree(ip->dev, ip->addrs[NDIRECT+1]);
+    ip->addrs[NDIRECT+1] = 0;
+  }
   ip->size = 0;
   iupdate(ip);
 }
diff --git a/kernel/fs.h b/kernel/fs.h
index 139dcc9..cd5de8a 100644
--- a/kernel/fs.h
+++ b/kernel/fs.h
@@ -24,9 +24,10 @@ struct superblock {
 
 #define FSMAGIC 0x10203040
 
-#define NDIRECT 12
+#define NDIRECT 11
 #define NINDIRECT (BSIZE / sizeof(uint))
-#define MAXFILE (NDIRECT + NINDIRECT)
+#define NINDIRECT2 (NINDIRECT * NINDIRECT)
+#define MAXFILE (NDIRECT + NINDIRECT + NINDIRECT2)
 
 // On-disk inode structure
 struct dinode {
@@ -35,7 +36,7 @@ struct dinode {
   short minor;          // Minor device number (T_DEVICE only)
   short nlink;          // Number of links to inode in file system
   uint size;            // Size of file (bytes)
-  uint addrs[NDIRECT+1];   // Data block addresses
+  uint addrs[NDIRECT+2];   // Data block addresses
 };
 
 // Inodes per block.
diff --git a/user/bigfile.c b/user/bigfile.c
index 0755700..a484040 100644
--- a/user/bigfile.c
+++ b/user/bigfile.c
@@ -32,9 +32,11 @@ main()
     printf("bigfile: file is too small\n");
     exit(-1);
   }
-  
+  printf("bef close fd\n");
   close(fd);
+  printf("aft close fd\n");
   fd = open("big.file", O_RDONLY);
+  printf("aft open\n");
   if(fd < 0){
     printf("bigfile: cannot re-open big.file for reading\n");
     exit(-1);