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

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->files
  locks: add missing memory barrier in break_deleg

2 files changed, 7 insertions, 1 deletions

diff --git a/fs/locks.c b/fs/locks.c
index da57c9b7e844..717fbc404e6b 100644
--- 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
index 338e6f758c6d..e11d60cc867b 100644
--- 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;