[Devel] [PATCH RHEL7 COMMIT] ms/dcache: add missing lockdep annotation

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-327.18.2.vz7.14.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-327.18.2.vz7.14.8
------>
commit 952e07e6fd8d272b120e05893b62cd934edb2c49
Author: Linus Torvalds <torvalds at linux-foundation.org>
Date:   Fri May 27 12:53:14 2016 +0400

    ms/dcache: add missing lockdep annotation
    
    lock_parent() very much on purpose does nested locking of dentries, and
    is careful to maintain the right order (lock parent first).  But because
    it didn't annotate the nested locking order, lockdep thought it might be
    a deadlock on d_lock, and complained.
    
    Add the proper annotation for the inner locking of the child dentry to
    make lockdep happy.
    
    Introduced by commit 046b961b45f9 ("shrink_dentry_list(): take parent's
    ->d_lock earlier").
    
    Reported-and-tested-by: Josh Boyer <jwboyer at fedoraproject.org>
    Cc: Al Viro <viro at zeniv.linux.org.uk>
    Signed-off-by: Linus Torvalds <torvalds at linux-foundation.org>
    (cherry picked from commit 9f12600fe425bc28f0ccba034a77783c09c15af4)
    Signed-off-by: Vladimir Davydov <vdavydov at virtuozzo.com>
---
 fs/dcache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/dcache.c b/fs/dcache.c
index ab68597..09ed486 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -582,7 +582,7 @@ again:
 	}
 	rcu_read_unlock();
 	if (parent != dentry)
-		spin_lock(&dentry->d_lock);
+		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
 	else
 		parent = NULL;
 	return parent;