linux-kernel - [PATCH 2/6] staging: lustre: llite: use d_splice

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Date:   Wed, 02 Aug 2017 13:06:18 +1000
From:   NeilBrown <neilb@...e.com>
To:     Oleg Drokin <oleg.drokin@...el.com>,
        Greg Kroah-Hartman <greg@...ah.com>,
        Andreas Dilger <andreas.dilger@...el.com>
Cc:     Lustre Development List <lustre-devel@...ts.lustre.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 2/6] staging: lustre: llite: use d_splice_alias for
 directories.

In the Linux dcache a directory only ever has one dentry,
so d_splice_alias() can be used by ll_splice_alias() for directories.
It will find the one dentry whether it is DCACHE_DISCONNECTED or
IS_ROOT() or d_lustre_invalid().
Separating out the directories from non-directories will allow us
to simplify the non-directory code.

Signed-off-by: NeilBrown <neilb@...e.com>
---
 drivers/staging/lustre/lustre/llite/namei.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/staging/lustre/lustre/llite/namei.c b/drivers/staging/lustre/lustre/llite/namei.c
index a208a8b02c2c..5ac340a8ad6f 100644
--- a/drivers/staging/lustre/lustre/llite/namei.c
+++ b/drivers/staging/lustre/lustre/llite/namei.c
@@ -432,7 +432,7 @@ static struct dentry *ll_find_alias(struct inode *inode, struct dentry *dentry)
  */
 struct dentry *ll_splice_alias(struct inode *inode, struct dentry *de)
 {
-	if (inode) {
+	if (inode && !S_ISDIR(inode->i_mode)) {
 		struct dentry *new = ll_find_alias(inode, de);
 
 		if (new) {
@@ -443,8 +443,13 @@ struct dentry *ll_splice_alias(struct inode *inode, struct dentry *de)
 			      new, d_inode(new), d_count(new), new->d_flags);
 			return new;
 		}
+		d_add(de, inode);
+	} else {
+		struct dentry *new = d_splice_alias(inode, de);
+
+		if (new)
+			de = new;
 	}
-	d_add(de, inode);
 	CDEBUG(D_DENTRY, "Add dentry %p inode %p refc %d flags %#x\n",
 	       de, d_inode(de), d_count(de), de->d_flags);
 	return de;