linux-kernel - [PATCH 4/5] staging: lluste: llite: simplify ll_find

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Message-ID: <151847104803.26699.4826721577063033284.stgit@noble>
Date:   Tue, 13 Feb 2018 08:30:48 +1100
From:   NeilBrown <neilb@...e.com>
To:     Oleg Drokin <oleg.drokin@...el.com>,
        Andreas Dilger <andreas.dilger@...el.com>,
        James Simmons <jsimmons@...radead.org>,
        Al Viro <viro@...IV.linux.org.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        lustre <lustre-devel@...ts.lustre.org>
Subject: [PATCH 4/5] staging: lluste: llite: simplify ll_find_alias()

Now that ll_find_alias is only searching for one type
of dentry, we can return as soon as we find it.
This allows substantial simplification, and brings the
bonus that we don't need to take the d_lock again just
to increment the ref-count.  We can increment it immediately
that the dentry is found.

Signed-off-by: NeilBrown <neilb@...e.com>
---
 drivers/staging/lustre/lustre/llite/namei.c |   23 ++++++++---------------
 1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/namei.c b/drivers/staging/lustre/lustre/llite/namei.c
index 2322328155d6..baf94f4bcee9 100644
--- a/drivers/staging/lustre/lustre/llite/namei.c
+++ b/drivers/staging/lustre/lustre/llite/namei.c
@@ -384,13 +384,11 @@ void ll_i2gids(__u32 *suppgids, struct inode *i1, struct inode *i2)
  */
 static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry)
 {
-	struct dentry *alias, *invalid_alias;
+	struct dentry *alias;
 
 	if (hlist_empty(&inode->i_dentry))
 		return NULL;
 
-	invalid_alias = NULL;
-
 	spin_lock(&inode->i_lock);
 	hlist_for_each_entry(alias, &inode->i_dentry, d_u.d_alias) {
 		LASSERT(alias != dentry);
@@ -400,22 +398,17 @@ static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry)
 		    alias->d_name.hash == dentry->d_name.hash       &&
 		    alias->d_name.len == dentry->d_name.len	 &&
 		    memcmp(alias->d_name.name, dentry->d_name.name,
-			   dentry->d_name.len) == 0)
-			invalid_alias = alias;
-		spin_unlock(&alias->d_lock);
-
-		if (invalid_alias)
-			break;
-	}
-	alias = invalid_alias ?: NULL;
-	if (alias) {
-		spin_lock(&alias->d_lock);
-		dget_dlock(alias);
+			   dentry->d_name.len) == 0) {
+			dget_dlock(alias);
+			spin_unlock(&alias->d_lock);
+			spin_unlock(&inode->i_lock);
+			return alias;
+		}
 		spin_unlock(&alias->d_lock);
 	}
 	spin_unlock(&inode->i_lock);
 
-	return alias;
+	return NULL;
 }
 
 /*