From f3979b7212f1bb9d72947f54abead5be973c6aed Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Thu, 16 Jul 2020 11:38:08 -0400
Subject: make "echo hello > x" truncate file x.

---
 kernel/fs.c | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

(limited to 'kernel/fs.c')

diff --git a/kernel/fs.c b/kernel/fs.c
index 53586d5..e33ec30 100644
--- a/kernel/fs.c
+++ b/kernel/fs.c
@@ -22,7 +22,6 @@
 #include "file.h"
 
 #define min(a, b) ((a) < (b) ? (a) : (b))
-static void itrunc(struct inode*);
 // there should be one superblock per disk device, but we run with
 // only one device
 struct superblock sb; 
@@ -406,11 +405,8 @@ bmap(struct inode *ip, uint bn)
 }
 
 // Truncate inode (discard contents).
-// Only called when the inode has no links
-// to it (no directory entries referring to it)
-// and has no in-memory reference to it (is
-// not an open file or current directory).
-static void
+// Caller must hold ip->lock.
+void
 itrunc(struct inode *ip)
 {
   int i, j;
@@ -463,7 +459,7 @@ readi(struct inode *ip, int user_dst, uint64 dst, uint off, uint n)
   struct buf *bp;
 
   if(off > ip->size || off + n < off)
-    return -1;
+    return 0;
   if(off + n > ip->size)
     n = ip->size - off;
 
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