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From:   Xiubo Li <xiubli@redhat.com>
To:     jlayton@kernel.org, idryomov@gmail.com, viro@zeniv.linux.org.uk
Cc:     willy@infradead.org, vshankar@redhat.com,
        ceph-devel@vger.kernel.org, arnd@arndb.de, mcgrof@kernel.org,
        akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, Xiubo Li <xiubli@redhat.com>
Subject: [PATCH v4 1/2] fs/dcache: add d_compare() helper support
Date:   Wed, 18 May 2022 22:45:44 +0800
Message-Id: <20220518144545.246604-2-xiubli@redhat.com>
In-Reply-To: <20220518144545.246604-1-xiubli@redhat.com>
References: <20220518144545.246604-1-xiubli@redhat.com>
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Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Xiubo Li <xiubli@redhat.com>
---
 fs/dcache.c            | 15 +++++++++++++++
 include/linux/dcache.h |  2 ++
 2 files changed, 17 insertions(+)

diff --git a/fs/dcache.c b/fs/dcache.c
index 93f4f5ee07bf..95a72f92a94b 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -2262,6 +2262,21 @@ static inline bool d_same_name(const struct dentry *dentry,
 				       name) == 0;
 }
 
+/**
+ * d_compare - compare dentry name with case-exact name
+ * @parent: parent dentry
+ * @dentry: the negative dentry that was passed to the parent's lookup func
+ * @name:   the case-exact name to be associated with the returned dentry
+ *
+ * Return: 0 if names are same, or 1
+ */
+bool d_compare(const struct dentry *parent, const struct dentry *dentry,
+	       const struct qstr *name)
+{
+	return !d_same_name(dentry, parent, name);
+}
+EXPORT_SYMBOL(d_compare);
+
 /**
  * __d_lookup_rcu - search for a dentry (racy, store-free)
  * @parent: parent dentry
diff --git a/include/linux/dcache.h b/include/linux/dcache.h
index f5bba51480b2..444b2230e5c3 100644
--- a/include/linux/dcache.h
+++ b/include/linux/dcache.h
@@ -233,6 +233,8 @@ extern struct dentry * d_alloc_parallel(struct dentry *, const struct qstr *,
 					wait_queue_head_t *);
 extern struct dentry * d_splice_alias(struct inode *, struct dentry *);
 extern struct dentry * d_add_ci(struct dentry *, struct inode *, struct qstr *);
+extern bool d_compare(const struct dentry *parent, const struct dentry *dentry,
+		      const struct qstr *name);
 extern struct dentry * d_exact_alias(struct dentry *, struct inode *);
 extern struct dentry *d_find_any_alias(struct inode *inode);
 extern struct dentry * d_obtain_alias(struct inode *);
-- 
2.36.0.rc1