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, 16 insertions, 14 deletions

diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index 9f65cd9..7177532 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -108,13 +108,13 @@ static int internal_create_group(struct kobject *kobj, int update,
 		}
 	} else
 		sd = kobj->sd;
-	sysfs_get(sd);
+	kernfs_get(sd);
 	error = create_files(sd, kobj, grp, update);
 	if (error) {
 		if (grp->name)
 			kernfs_remove(sd);
 	}
-	sysfs_put(sd);
+	kernfs_put(sd);
 	return error;
 }
 
@@ -208,21 +208,23 @@ void sysfs_remove_group(struct kobject *kobj,
 	struct sysfs_dirent *sd;
 
 	if (grp->name) {
-		sd = sysfs_get_dirent(dir_sd, grp->name);
+		sd = kernfs_find_and_get(dir_sd, grp->name);
 		if (!sd) {
 			WARN(!sd, KERN_WARNING
 			     "sysfs group %p not found for kobject '%s'\n",
 			     grp, kobject_name(kobj));
 			return;
 		}
-	} else
-		sd = sysfs_get(dir_sd);
+	} else {
+		sd = dir_sd;
+		kernfs_get(sd);
+	}
 
 	remove_files(sd, kobj, grp);
 	if (grp->name)
 		kernfs_remove(sd);
 
-	sysfs_put(sd);
+	kernfs_put(sd);
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_group);
 
@@ -263,7 +265,7 @@ int sysfs_merge_group(struct kobject *kobj,
 	struct attribute *const *attr;
 	int i;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, grp->name);
+	dir_sd = kernfs_find_and_get(kobj->sd, grp->name);
 	if (!dir_sd)
 		return -ENOENT;
 
@@ -273,7 +275,7 @@ int sysfs_merge_group(struct kobject *kobj,
 		while (--i >= 0)
 			kernfs_remove_by_name(dir_sd, (*--attr)->name);
 	}
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -290,11 +292,11 @@ void sysfs_unmerge_group(struct kobject *kobj,
 	struct sysfs_dirent *dir_sd;
 	struct attribute *const *attr;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, grp->name);
+	dir_sd = kernfs_find_and_get(kobj->sd, grp->name);
 	if (dir_sd) {
 		for (attr = grp->attrs; *attr; ++attr)
 			kernfs_remove_by_name(dir_sd, (*attr)->name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
@@ -312,12 +314,12 @@ int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
 	struct sysfs_dirent *dir_sd;
 	int error = 0;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, group_name);
+	dir_sd = kernfs_find_and_get(kobj->sd, group_name);
 	if (!dir_sd)
 		return -ENOENT;
 
 	error = sysfs_create_link_sd(dir_sd, target, link_name);
-	sysfs_put(dir_sd);
+	kernfs_put(dir_sd);
 
 	return error;
 }
@@ -334,10 +336,10 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 {
 	struct sysfs_dirent *dir_sd;
 
-	dir_sd = sysfs_get_dirent(kobj->sd, group_name);
+	dir_sd = kernfs_find_and_get(kobj->sd, group_name);
 	if (dir_sd) {
 		kernfs_remove_by_name(dir_sd, link_name);
-		sysfs_put(dir_sd);
+		kernfs_put(dir_sd);
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);