[PATCH] fuse: locking fix for nlookup

An inode could be returned by independent parallel lookups, in this case an
update of the lookup counter could be lost resulting in a memory leak in
userspace.
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

fs/fuse/dir.c

@@ -163,7 +163,9 @@ static int fuse_dentry_revalidate(struct dentry *entry, struct nameidata *nd)
 				fuse_send_forget(fc, req, outarg.nodeid, 1);
 				return 0;
 			}
+			spin_lock(&fc->lock);
 			fi->nlookup ++;
+			spin_unlock(&fc->lock);
 		}
 		fuse_put_request(fc, req);
 		if (err || (outarg.attr.mode ^ inode->i_mode) & S_IFMT)

fs/fuse/inode.c

@@ -195,7 +195,9 @@ struct inode *fuse_iget(struct super_block *sb, unsigned long nodeid,
 	}
 
 	fi = get_fuse_inode(inode);
+	spin_lock(&fc->lock);
 	fi->nlookup ++;
+	spin_unlock(&fc->lock);
 	fuse_change_attributes(inode, attr);
 	return inode;
 }