From ca1bab38195d66bdf42320a99cc7359434a271d3 Mon Sep 17 00:00:00 2001
From: "Eric W. Biederman" <ebiederm@xmission.com>
Date: Fri, 20 Nov 2009 16:08:57 -0800
Subject: [PATCH] sysfs: Factor out sysfs_rename from sysfs_rename_dir and
 sysfs_move_dir

These two functions do 90% of the same work and it doesn't significantly
obfuscate the function to allow both the parent dir and the name to change
at the same time.  So merge them together to simplify maintenance, and
increase testing.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
 fs/sysfs/dir.c   | 62 ++++++++++++++++++++++--------------------------
 fs/sysfs/sysfs.h |  3 +++
 2 files changed, 32 insertions(+), 33 deletions(-)

diff --git a/fs/sysfs/dir.c b/fs/sysfs/dir.c
index 97954c69ff0..f05f2303a8b 100644
--- a/fs/sysfs/dir.c
+++ b/fs/sysfs/dir.c
@@ -760,30 +760,42 @@ void sysfs_remove_dir(struct kobject * kobj)
 	__sysfs_remove_dir(sd);
 }
 
-int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
+int sysfs_rename(struct sysfs_dirent *sd,
+	struct sysfs_dirent *new_parent_sd, const char *new_name)
 {
-	struct sysfs_dirent *sd = kobj->sd;
 	const char *dup_name = NULL;
 	int error;
 
 	mutex_lock(&sysfs_mutex);
 
 	error = 0;
-	if (strcmp(sd->s_name, new_name) == 0)
+	if ((sd->s_parent == new_parent_sd) &&
+	    (strcmp(sd->s_name, new_name) == 0))
 		goto out;	/* nothing to rename */
 
 	error = -EEXIST;
-	if (sysfs_find_dirent(sd->s_parent, new_name))
+	if (sysfs_find_dirent(new_parent_sd, new_name))
 		goto out;
 
 	/* rename sysfs_dirent */
-	error = -ENOMEM;
-	new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
-	if (!new_name)
-		goto out;
+	if (strcmp(sd->s_name, new_name) != 0) {
+		error = -ENOMEM;
+		new_name = dup_name = kstrdup(new_name, GFP_KERNEL);
+		if (!new_name)
+			goto out;
 
-	dup_name = sd->s_name;
-	sd->s_name = new_name;
+		dup_name = sd->s_name;
+		sd->s_name = new_name;
+	}
+
+	/* Remove from old parent's list and insert into new parent's list. */
+	if (sd->s_parent != new_parent_sd) {
+		sysfs_unlink_sibling(sd);
+		sysfs_get(new_parent_sd);
+		sysfs_put(sd->s_parent);
+		sd->s_parent = new_parent_sd;
+		sysfs_link_sibling(sd);
+	}
 
 	error = 0;
  out:
@@ -792,37 +804,21 @@ int sysfs_rename_dir(struct kobject * kobj, const char *new_name)
 	return error;
 }
 
+int sysfs_rename_dir(struct kobject *kobj, const char *new_name)
+{
+	return sysfs_rename(kobj->sd, kobj->sd->s_parent, new_name);
+}
+
 int sysfs_move_dir(struct kobject *kobj, struct kobject *new_parent_kobj)
 {
 	struct sysfs_dirent *sd = kobj->sd;
 	struct sysfs_dirent *new_parent_sd;
-	int error;
 
 	BUG_ON(!sd->s_parent);
-
-	mutex_lock(&sysfs_mutex);
-	new_parent_sd = (new_parent_kobj && new_parent_kobj->sd) ?
+	new_parent_sd = new_parent_kobj && new_parent_kobj->sd ?
 		new_parent_kobj->sd : &sysfs_root;
 
-	error = 0;
-	if (sd->s_parent == new_parent_sd)
-		goto out;	/* nothing to move */
-
-	error = -EEXIST;
-	if (sysfs_find_dirent(new_parent_sd, sd->s_name))
-		goto out;
-
-	/* Remove from old parent's list and insert into new parent's list. */
-	sysfs_unlink_sibling(sd);
-	sysfs_get(new_parent_sd);
-	sysfs_put(sd->s_parent);
-	sd->s_parent = new_parent_sd;
-	sysfs_link_sibling(sd);
-
-	error = 0;
-out:
-	mutex_unlock(&sysfs_mutex);
-	return error;
+	return sysfs_rename(sd, new_parent_sd, sd->s_name);
 }
 
 /* Relationship between s_mode and the DT_xxx types */
diff --git a/fs/sysfs/sysfs.h b/fs/sysfs/sysfs.h
index 98a15bf1efe..ca52e7b9d8f 100644
--- a/fs/sysfs/sysfs.h
+++ b/fs/sysfs/sysfs.h
@@ -130,6 +130,9 @@ int sysfs_create_subdir(struct kobject *kobj, const char *name,
 			struct sysfs_dirent **p_sd);
 void sysfs_remove_subdir(struct sysfs_dirent *sd);
 
+int sysfs_rename(struct sysfs_dirent *sd,
+	struct sysfs_dirent *new_parent_sd, const char *new_name);
+
 static inline struct sysfs_dirent *__sysfs_get(struct sysfs_dirent *sd)
 {
 	if (sd) {