linux-kernel - [PATCH] VFS: Remove unnecessary micro-optimization in cached

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Message-Id: <1245271510-31542-5-git-send-email-jblunck@suse.de>
Date:	Wed, 17 Jun 2009 22:45:08 +0200
From:	Jan Blunck <jblunck@...e.de>
To:	viro@...IV.linux.org.uk
Cc:	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	vaurora@...hat.com, hch@....de, miklos@...redi.hu
Subject: [PATCH] VFS: Remove unnecessary micro-optimization in cached_lookup()

d_lookup() takes rename_lock which is a seq_lock.  This is so cheap
it's not worth calling lockless __d_lookup() first from
cache_lookup().  Rename cached_lookup() to cache_lookup() while we're
there.

Signed-off-by: Jan Blunck <jblunck@...e.de>
Signed-off-by: Valerie Aurora (Henson) <vaurora@...hat.com>
---
 fs/namei.c |   13 ++++---------
 1 files changed, 4 insertions(+), 9 deletions(-)

diff --git a/fs/namei.c b/fs/namei.c
index c0cd4cb..9b12363 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -404,15 +404,10 @@ do_revalidate(struct dentry *dentry, struct nameidata *nd)
  * Internal lookup() using the new generic dcache.
  * SMP-safe
  */
-static struct dentry * cached_lookup(struct dentry * parent, struct qstr * name, struct nameidata *nd)
+static struct dentry *cache_lookup(struct dentry *parent, struct qstr *name,
+				   struct nameidata *nd)
 {
-	struct dentry * dentry = __d_lookup(parent, name);
-
-	/* lockess __d_lookup may fail due to concurrent d_move() 
-	 * in some unrelated directory, so try with d_lookup
-	 */
-	if (!dentry)
-		dentry = d_lookup(parent, name);
+	struct dentry *dentry = d_lookup(parent, name);
 
 	if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
 		dentry = do_revalidate(dentry, nd);
@@ -1172,7 +1167,7 @@ static struct dentry *__lookup_hash(struct qstr *name,
 			goto out;
 	}
 
-	dentry = cached_lookup(base, name, nd);
+	dentry = cache_lookup(base, name, nd);
 	if (!dentry) {
 		struct dentry *new;
 
-- 
1.6.0.2

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