lab fs/bigfile: finish

3 files changed, 64 insertions, 9 deletions

diff --git a/kernel/file.h b/kernel/file.h
index 1eb5107..b993cc3 100644
--- a/kernel/file.h
+++ b/kernel/file.h
@@ -33,7 +33,7 @@ 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 6c4079e..57b36a1 100644
--- a/kernel/fs.c
+++ b/kernel/fs.c
@@ -396,7 +396,7 @@ bmap(struct inode *ip, uint bn)
   }
   bn -= NDIRECT;
 
-  if(bn < NINDIRECT){
+  if(bn < NSG_INDIRECT){
     // Load indirect block, allocating if necessary.
     if((addr = ip->addrs[NDIRECT]) == 0){
       addr = balloc(ip->dev);
@@ -416,6 +416,38 @@ bmap(struct inode *ip, uint bn)
     brelse(bp);
     return addr;
   }
+  bn -= NSG_INDIRECT;
+
+  if(bn < NDB_INDIRECT){
+    // Load indirect block in each level, allocating if necessary.
+    if((addr = ip->addrs[NDIRECT+1]) == 0){
+      addr = balloc(ip->dev);
+      if(addr == 0)
+        return 0;
+      ip->addrs[NDIRECT+1] = addr;
+    }
+    bp = bread(ip->dev, addr);
+    a = (uint*)bp->data;
+    if((addr = a[bn/NSG_INDIRECT]) == 0){
+      addr = balloc(ip->dev);
+      if(addr){
+        a[bn/NSG_INDIRECT] = addr;
+        log_write(bp);
+      }
+    }
+    brelse(bp);
+    bp = bread(ip->dev, addr);
+    a = (uint*)bp->data;
+    if((addr = a[bn%NSG_INDIRECT]) == 0){
+      addr = balloc(ip->dev);
+      if(addr){
+        a[bn%NSG_INDIRECT] = addr;
+        log_write(bp);
+      }
+    }
+    brelse(bp);
+    return addr;
+  }
   panic("bmap: out of range");
 }
 
@@ -424,9 +456,9 @@ 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, *l2bp;
+  uint *a, *l2a;
 
   for(i = 0; i < NDIRECT; i++){
     if(ip->addrs[i]){
@@ -438,7 +470,7 @@ itrunc(struct inode *ip)
   if(ip->addrs[NDIRECT]){
     bp = bread(ip->dev, ip->addrs[NDIRECT]);
     a = (uint*)bp->data;
-    for(j = 0; j < NINDIRECT; j++){
+    for(j = 0; j < NSG_INDIRECT; j++){
       if(a[j])
         bfree(ip->dev, a[j]);
     }
@@ -447,6 +479,27 @@ 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 < NSG_INDIRECT; j++){
+      if(a[j]){
+        l2bp = bread(ip->dev, a[j]);
+        l2a = (uint*)l2bp->data;
+        for(k = 0; k < NSG_INDIRECT; k++)
+        {
+          if(l2a[k]){
+            bfree(ip->dev, l2a[k]);
+          }
+        }
+        brelse(l2bp);        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..9ae5ece 100644
--- a/kernel/fs.h
+++ b/kernel/fs.h
@@ -24,8 +24,10 @@ struct superblock {
 
 #define FSMAGIC 0x10203040
 
-#define NDIRECT 12
-#define NINDIRECT (BSIZE / sizeof(uint))
+#define NDIRECT 11
+#define NSG_INDIRECT (BSIZE / sizeof(uint))
+#define NDB_INDIRECT (NSG_INDIRECT * NSG_INDIRECT)
+#define NINDIRECT (NSG_INDIRECT + NDB_INDIRECT)
 #define MAXFILE (NDIRECT + NINDIRECT)
 
 // On-disk inode structure
@@ -35,7 +37,7 @@ 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.