sysfs, kernfs: introduce kernfs[_find_and]_get() and kernfs_put()

Introduce kernfs interface for finding, getting and putting
sysfs_dirents.

* sysfs_find_dirent() is renamed to kernfs_find_ns() and lockdep
  assertion for sysfs_mutex is added.

* sysfs_get_dirent_ns() is renamed to kernfs_find_and_get().

* Macro inline dancing around __sysfs_get/put() are removed and
  kernfs_get/put() are made proper functions implemented in
  fs/sysfs/dir.c.

While the conversions are mostly equivalent, there's one difference -
kernfs_get() doesn't return the input param as its return value.  This
change is intentional.  While passing through the input increases
writability in some areas, it is unnecessary and has been shown to
cause confusion regarding how the last ref is handled.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 23 insertions, 18 deletions

diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index e4eca285b390..7f0a79fa2ed8 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -881,19 +881,19 @@ void sysfs_notify(struct kobject *k, const char *dir, const char *attr)
 	struct sysfs_dirent *sd = k->sd, *tmp;
 
 	if (sd && dir)
-		sd = sysfs_get_dirent(sd, dir);
+		sd = kernfs_find_and_get(sd, dir);
 	else
-		sysfs_get(sd);
+		kernfs_get(sd);
 
 	if (sd && attr) {
-		tmp = sysfs_get_dirent(sd, attr);
-		sysfs_put(sd);
+		tmp = kernfs_find_and_get(sd, attr);
+		kernfs_put(sd);
 		sd = tmp;
 	}
 
 	if (sd) {
 		kernfs_notify(sd);
-		sysfs_put(sd);
+		kernfs_put(sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_notify);
@@ -1052,7 +1052,7 @@ struct sysfs_dirent *kernfs_create_file_ns_key(struct sysfs_dirent *parent,
 	sysfs_addrm_finish(&acxt);
 
 	if (rc) {
-		sysfs_put(sd);
+		kernfs_put(sd);
 		return ERR_PTR(rc);
 	}
 	return sd;
@@ -1106,16 +1106,18 @@ int sysfs_add_file_to_group(struct kobject *kobj,
 	struct sysfs_dirent *dir_sd;
 	int error;
 
-	if (group)
-		dir_sd = sysfs_get_dirent(kobj->sd, group);
-	else
-		dir_sd = sysfs_get(kobj->sd);
+	if (group) {
+		dir_sd = kernfs_find_and_get(kobj->sd, group);
+	} else {
+		dir_sd = kobj->sd;
+		kernfs_get(dir_sd);
+	}
 
 	if (!dir_sd)
 		return -ENOENT;
 
 	error = sysfs_add_file(dir_sd, attr, false);
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -1135,7 +1137,7 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 	struct iattr newattrs;
 	int rc;
 
-	sd = sysfs_get_dirent(kobj->sd, attr->name);
+	sd = kernfs_find_and_get(kobj->sd, attr->name);
 	if (!sd)
 		return -ENOENT;
 
@@ -1144,7 +1146,7 @@ int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
 
 	rc = kernfs_setattr(sd, &newattrs);
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return rc;
 }
 EXPORT_SYMBOL_GPL(sysfs_chmod_file);
@@ -1185,13 +1187,16 @@ void sysfs_remove_file_from_group(struct kobject *kobj,
 {
 	struct sysfs_dirent *dir_sd;
 
-	if (group)
-		dir_sd = sysfs_get_dirent(kobj->sd, group);
-	else
-		dir_sd = sysfs_get(kobj->sd);
+	if (group) {
+		dir_sd = kernfs_find_and_get(kobj->sd, group);
+	} else {
+		dir_sd = kobj->sd;
+		kernfs_get(dir_sd);
+	}
+
 	if (dir_sd) {
 		kernfs_remove_by_name(dir_sd, attr->name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_file_from_group);