diff --git a/fs.c b/fs.c
index a6c4732..fb82f91 100644
--- a/fs.c
+++ b/fs.c
@@ -143,7 +143,7 @@ iinit(void)
 }
 
 // Find the inode with number inum on device dev
-// and return the in-memory copy. h
+// and return the in-memory copy.
 static struct inode*
 iget(uint dev, uint inum)
 {
@@ -255,6 +255,7 @@ iput(struct inode *ip)
   release(&icache.lock);
 }
 
+// Common idiom: unlock, then put.
 void
 iunlockput(struct inode *ip)
 {
@@ -275,7 +276,7 @@ ialloc(uint dev, short type)
   readsb(dev, &sb);
   for(inum = 1; inum < sb.ninodes; inum++) {  // loop over inode blocks
     bp = bread(dev, IBLOCK(inum));
-    dip = &((struct dinode*)(bp->data))[inum % IPB];
+    dip = (struct dinode*)(bp->data) + inum%IPB;
     if(dip->type == 0) {  // a free inode
       memset(dip, 0, sizeof(*dip));
       dip->type = type;
@@ -296,7 +297,7 @@ iupdate(struct inode *ip)
   struct dinode *dip;
 
   bp = bread(ip->dev, IBLOCK(ip->inum));
-  dip = &((struct dinode*)(bp->data))[ip->inum % IPB];
+  dip = (struct dinode*)(bp->data) + ip->inum%IPB;
   dip->type = ip->type;
   dip->major = ip->major;
   dip->minor = ip->minor;
@@ -312,7 +313,7 @@ iupdate(struct inode *ip)
 //
 // The contents (data) associated with each inode is stored
 // in a sequence of blocks on the disk.  The first NDIRECT blocks
-// are stored in ip->addrs[].  The next NINDIRECT blocks are 
+// are listed in ip->addrs[].  The next NINDIRECT blocks are 
 // listed in the block ip->addrs[INDIRECT].
 
 // Return the disk block address of the nth block in inode ip.
@@ -414,7 +415,7 @@ readi(struct inode *ip, char *dst, uint off, uint n)
     return devsw[ip->major].read(ip->minor, dst, n);
   }
 
-  if(off + n < off)
+  if(off > ip->size || off + n < off)
     return -1;
   if(off + n > ip->size)
     n = ip->size - off;
@@ -486,8 +487,8 @@ dirlookup(struct inode *dp, char *name, uint *poff)
 
   for(off = 0; off < dp->size; off += BSIZE){
     bp = bread(dp->dev, bmap(dp, off / BSIZE, 0));
-    for(de = (struct dirent*) bp->data;
-        de < (struct dirent*) (bp->data + BSIZE);
+    for(de = (struct dirent*)bp->data;
+        de < (struct dirent*)(bp->data + BSIZE);
         de++){
       if(de->inum == 0)
         continue;
@@ -522,7 +523,7 @@ dirlink(struct inode *dp, char *name, uint ino)
   // Look for an empty dirent.
   for(off = 0; off < dp->size; off += sizeof(de)){
     if(readi(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
-      panic("dirwrite read");
+      panic("dirlink read");
     if(de.inum == 0)
       break;
   }
@@ -530,7 +531,7 @@ dirlink(struct inode *dp, char *name, uint ino)
   strncpy(de.name, name, DIRSIZ);
   de.inum = ino;
   if(writei(dp, (char*)&de, off, sizeof(de)) != sizeof(de))
-    panic("dirwrite");
+    panic("dirlink");
   
   return 0;
 }
@@ -546,7 +547,7 @@ dirlink(struct inode *dp, char *name, uint ino)
 //
 // Examples:
 //   skipelem("a/bb/c", name) = "bb/c", setting name = "a"
-//   skipelem("///a/bb", name) = "bb", setting name="a"
+//   skipelem("///a//bb", name) = "bb", setting name = "a"
 //   skipelem("", name) = skipelem("////", name) = 0
 //
 static char*
@@ -574,21 +575,6 @@ skipelem(char *path, char *name)
   return path;
 }
 
-static struct inode* _namei(char*, int, char*);
-
-struct inode*
-namei(char *path)
-{
-  char name[DIRSIZ];
-  return _namei(path, 0, name);
-}
-
-struct inode*
-nameiparent(char *path, char *name)
-{
-  return _namei(path, 1, name);
-}
-
 // Look up and return the inode for a path name.
 // If parent is set, return the inode for the parent
 // and write the final path element to name, which
@@ -597,7 +583,6 @@ static struct inode*
 _namei(char *path, int parent, char *name)
 {
   struct inode *ip, *next;
-  uint off;
 
   if(*path == '/')
     ip = iget(ROOTDEV, 1);
@@ -610,14 +595,12 @@ _namei(char *path, int parent, char *name)
       iunlockput(ip);
       return 0;
     }
-    
     if(parent && *path == '\0'){
       // Stop one level early.
       iunlock(ip);
       return ip;
     }
-
-    if((next = dirlookup(ip, name, &off)) == 0){
+    if((next = dirlookup(ip, name, 0)) == 0){
       iunlockput(ip);
       return 0;
     }
@@ -631,3 +614,14 @@ _namei(char *path, int parent, char *name)
   return ip;
 }
 
+struct inode*
+namei(char *path)
+{
+  char name[DIRSIZ];
+  return _namei(path, 0, name);
+}
+struct inode*
+nameiparent(char *path, char *name)
+{
+  return _namei(path, 1, name);
+}