Merge tag 'locks-v3.16-2' of git://git.samba.org/jlayton/linux

torvalds · torvalds · commit 2dfded821097 · 2014-06-21T16:40:30.000-10:00
Pull file locking fixes from Jeff Layton:
 "File locking related bugfixes

  Nothing too earth-shattering here.  A fix for a potential regression
  due to a patch in pile #1, and the addition of a memory barrier to
  prevent a race condition between break_deleg and generic_add_lease"

* tag 'locks-v3.16-2' of git://git.samba.org/jlayton/linux:
  locks: set fl_owner for leases back to current-&gt;files
  locks: add missing memory barrier in break_deleg
diff --git a/fs/locks.c b/fs/locks.c
@@ -431,7 +431,7 @@ static int lease_init(struct file *filp, long type, struct file_lock *fl)
 	if (assign_type(fl, type) != 0)
 		return -EINVAL;
 
-	fl->fl_owner = (fl_owner_t)filp;
+	fl->fl_owner = (fl_owner_t)current->files;
 	fl->fl_pid = current->tgid;
 
 	fl->fl_file = filp;
diff --git a/include/linux/fs.h b/include/linux/fs.h
@@ -1921,6 +1921,12 @@ static inline int break_lease(struct inode *inode, unsigned int mode)
 
 static inline int break_deleg(struct inode *inode, unsigned int mode)
 {
+	/*
+	 * Since this check is lockless, we must ensure that any refcounts
+	 * taken are done before checking inode->i_flock. Otherwise, we could
+	 * end up racing with tasks trying to set a new lease on this file.
+	 */
+	smp_mb();
 	if (inode->i_flock)
 		return __break_lease(inode, mode, FL_DELEG);
 	return 0;
