From 70d912b332328cb30cd86fdf63074cf10ba5ed35 Mon Sep 17 00:00:00 2001
From: Robert Morris <rtm@csail.mit.edu>
Date: Tue, 8 Aug 2017 13:48:48 -0400
Subject: protect ip->valid and ip->nlink with sleep lock in iput()

---
 fs.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

(limited to 'fs.c')

diff --git a/fs.c b/fs.c
index b67db5d..c73c530 100644
--- a/fs.c
+++ b/fs.c
@@ -320,15 +320,17 @@ void
 iput(struct inode *ip)
 {
   acquire(&icache.lock);
-  if(ip->ref == 1 && ip->valid && ip->nlink == 0){
-    // inode has no links and no other references: truncate and free.
+  if(ip->ref == 1){
     acquiresleep(&ip->lock);
-    release(&icache.lock);
-    itrunc(ip);
-    ip->type = 0;
-    iupdate(ip);
-    acquire(&icache.lock);
-    ip->valid = 0;
+    if(ip->valid && ip->nlink == 0){
+      // inode has no links and no other references: truncate and free.
+      release(&icache.lock);
+      itrunc(ip);
+      ip->type = 0;
+      iupdate(ip);
+      ip->valid = 0;
+      acquire(&icache.lock);
+    }
     releasesleep(&ip->lock);
   }
   ip->ref--;
-- 
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