linux-kernel - [PATCH 3.14 025/130] lift the "already marked killed" case into shrink_dentry

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Message-Id: <20160301234500.655332721@linuxfoundation.org>
Date:	Tue,  1 Mar 2016 15:44:36 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>
Subject: [PATCH 3.14 025/130] lift the "already marked killed" case into shrink_dentry_list()

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <viro@...iv.linux.org.uk>

commit 64fd72e0a44bdd62c5ca277cb24d0d02b2d8e9dc upstream.

It can happen only when dentry_kill() is called with unlock_on_failure
equal to 0 - other callers had dentry pinned until the moment they've
got ->d_lock and DCACHE_DENTRY_KILLED is set only after lockref_mark_dead().

IOW, only one of three call sites of dentry_kill() might end up reaching
that code.  Just move it there.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 fs/dcache.c |   15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -453,12 +453,6 @@ dentry_kill(struct dentry *dentry, int u
 	struct dentry *parent = NULL;
 	bool can_free = true;
 
-	if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
-		can_free = dentry->d_flags & DCACHE_MAY_FREE;
-		spin_unlock(&dentry->d_lock);
-		goto out;
-	}
-
 	inode = dentry->d_inode;
 	if (inode && !spin_trylock(&inode->i_lock)) {
 relock:
@@ -816,6 +810,15 @@ static void shrink_dentry_list(struct li
 			continue;
 		}
 
+
+		if (unlikely(dentry->d_flags & DCACHE_DENTRY_KILLED)) {
+			bool can_free = dentry->d_flags & DCACHE_MAY_FREE;
+			spin_unlock(&dentry->d_lock);
+			if (can_free)
+				dentry_free(dentry);
+			continue;
+		}
+
 		parent = dentry_kill(dentry, 0);
 		/*
 		 * If dentry_kill returns NULL, we have nothing more to do.