protect ip->valid and ip->nlink with sleep lock in iput()

1 files changed, 10 insertions, 8 deletions

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--;