avoid some more unnecessary sharing

6ac05a42 · Nickolai Zeldovich · 102ee83e · 6ac05a42 · 6ac05a42
--- a/kernel/bio.cc
+++ b/kernel/bio.cc
@@ -127,12 +127,4 @@ void
 initbio(void)
 {
  bufns = new xns<pair<u32, u64>, buf*, bio_hash>(false);
-
-  for (u64 i = 0; i < NBUF; i++) {
-    struct buf *b = new buf(0xdeadbeef, -i);
-    /* dummy to pre-allocate NBUF spaces for evict */
-    b->flags = 0;
-    if (bufns->insert(mkpair(b->dev, b->sector), b) < 0)
-      panic("binit ns_insert");
-  }
 }
--- a/kernel/fs.cc
+++ b/kernel/fs.cc
@@ -443,13 +443,23 @@ bmap(struct inode *ip, u32 bn)
    // Load indirect block, allocating if necessary.
    if((addr = ip->addrs[NDIRECT]) == 0)
      ip->addrs[NDIRECT] = addr = balloc(ip->dev);
-    bp = bread(ip->dev, addr, 1);
+
+    int writerflag = 0;
+    bp = bread(ip->dev, addr, writerflag);
    a = (u32*)bp->data;
    if((addr = a[bn]) == 0){
-      a[bn] = addr = balloc(ip->dev);
-      bwrite(bp);
+      brelse(bp, writerflag);
+
+      writerflag = 1;
+      bp = bread(ip->dev, addr, writerflag);
+      a = (u32*)bp->data;
+      addr = a[bn];
+      if (addr == 0) {
+        a[bn] = addr = balloc(ip->dev);
+        bwrite(bp);
+      }
    }
-    brelse(bp, 1);
+    brelse(bp, writerflag);
    return addr;
  }