From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [PATCH 6/6] autofs4: don't take spinlock when not needed in autofs4_lookup_expiring Date: Thu, 10 Jul 2014 09:41:14 +1000 Message-ID: <20140709234114.4525.70534.stgit@notabene.brown> References: <20140709233541.4525.25151.stgit@notabene.brown> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20140709233541.4525.25151.stgit@notabene.brown> Sender: linux-kernel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Ian Kent Cc: autofs@vger.kernel.org, linux-kernel@vger.kernel.org If the expiring_list is empty, we can avoid a costly spinlock in the rcu-walk path through authfs4_d_manage. Signed-off-by: NeilBrown --- fs/autofs4/root.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/autofs4/root.c b/fs/autofs4/root.c index 1ad119407e2f..774c2dab331b 100644 --- a/fs/autofs4/root.c +++ b/fs/autofs4/root.c @@ -219,6 +219,8 @@ static struct dentry *autofs4_lookup_expiring(struct dentry *dentry, const unsigned char *str = name->name; struct list_head *p, *head; + if (list_empty(&sbi->expiring_list)) + return NULL; spin_lock(&sbi->lookup_lock); head = &sbi->expiring_list; list_for_each(p, head) {