commit 65d8eb5a8f5480756105173de147ef5d60163e2f
author Al Viro <viro@zeniv.linux.org.uk> Fri Feb 23 22:07:35 2018 -0500
committer Al Viro <viro@zeniv.linux.org.uk> Thu Mar 29 15:07:42 2018 -0400
tree b06ff6ae3eb019432b827bf8620a38630a0f011f
parent 3b3f09f48ba78c0634e929849860a6447d057eed

now lock_parent() can't run into killed dentry

all remaining callers hold either a reference or ->i_lock

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

fs/dcache.c

diff --git a/fs/dcache.c b/fs/dcache.c
index af85014..916fd57 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -593,8 +593,6 @@ static inline struct dentry *lock_parent(struct dentry *dentry)
 	struct dentry *parent = dentry->d_parent;
 	if (IS_ROOT(dentry))
 		return NULL;
-	if (unlikely(dentry->d_lockref.count < 0))
-		return NULL;
 	if (likely(spin_trylock(&parent->d_lock)))
 		return parent;
 	rcu_read_lock();
@@ -614,16 +612,11 @@ static inline struct dentry *lock_parent(struct dentry *dentry)
 		spin_unlock(&parent->d_lock);
 		goto again;
 	}
-	if (parent != dentry) {
-		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
-		if (unlikely(dentry->d_lockref.count < 0)) {
-			spin_unlock(&parent->d_lock);
-			parent = NULL;
-		}
-	} else {
-		parent = NULL;
-	}
 	rcu_read_unlock();
+	if (parent != dentry)
+		spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
+	else
+		parent = NULL;
 	return parent;
 }