Increment the max file size

cw00h · Jan 20, 2023 · 9f1aa19 · 9f1aa19
1 parent 46bcbaf
commit 9f1aa19
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Showing 3 changed files with 53 additions and 8 deletions.
diff --git 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
@@ -377,8 +377,8 @@ iunlockput(struct inode *ip)
 static uint
 bmap(struct inode *ip, uint bn)
 {
-  uint addr, *a;
-  struct buf *bp;
+  uint addr, *a, idx;
+  struct buf *bp, *bp2;
 
   if(bn < NDIRECT){
     if((addr = ip->addrs[bn]) == 0)
@@ -400,6 +400,29 @@ bmap(struct inode *ip, uint bn)
     brelse(bp);
     return addr;
   }
+  bn -= NINDIRECT;
+
+  if(bn < NDBLINDIRECT) {
+    idx = bn / NINDIRECT; // Index in the doubly-indirect block
+    if((addr = ip->addrs[NDIRECT + 1]) == 0) { // The doubly-indirect block is not allocated
+      ip->addrs[NDIRECT + 1] = addr = balloc(ip->dev);
+    }
+    bp = bread(ip->dev, addr);
+    a = (uint*)bp->data;
+    if((addr = a[idx]) == 0) { // The singly-indirect block pointed by the doubly-indirect block is not allocated
+      a[idx] = addr = balloc(ip->dev);
+      log_write(bp);
+    }
+    bp2 = bread(ip->dev, addr);
+    a = (uint*)bp2->data;
+    if((addr = a[bn % NINDIRECT]) == 0) { // The data block is not allocated
+      a[bn % NINDIRECT] = addr = balloc(ip->dev);
+      log_write(bp2);
+    } 
+    brelse(bp);
+    brelse(bp2);
+    return addr;
+  }
 
   panic("bmap: out of range");
 }
@@ -410,8 +433,8 @@ void
 itrunc(struct inode *ip)
 {
   int i, j;
-  struct buf *bp;
-  uint *a;
+  struct buf *bp, *bp2;
+  uint *a, *b;
 
   for(i = 0; i < NDIRECT; i++){
     if(ip->addrs[i]){
@@ -432,6 +455,27 @@ 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(i = 0;  i < NINDIRECT; i++) {
+      if(a[i]) {
+        bp2 = bread(ip->dev, a[i]);
+        b = (uint*)bp2->data;
+        for(j = 0; j < NINDIRECT; j++) {
+          if(b[j]) {
+            bfree(ip->dev, b[j]);
+          }
+        }
+        brelse(bp2);
+        bfree(ip->dev, a[i]);
+      }
+    }
+    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
@@ -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 NDBLINDIRECT (((BSIZE * BSIZE) / sizeof(uint)) / sizeof(uint))
+#define MAXFILE (NDIRECT + NINDIRECT + NDBLINDIRECT)
 
 // 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.