configfs: remove old API

Remove the old show_attribute and store_attribute methods and update
the documentation.  Also replace the two C samples with a single new
one in the proper samples directory where people expect to find it.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

Documentation/filesystems/Makefile

-subdir-y := configfs
-
 # List of programs to build
 hostprogs-y := dnotify_test
 

Documentation/filesystems/configfs/Makefile

-ifneq ($(CONFIG_CONFIGFS_FS),)
-obj-m += configfs_example_explicit.o configfs_example_macros.o
-endif

Documentation/filesystems/configfs/configfs.txt

@@ -160,12 +160,6 @@ among other things.  For that, it needs a type.
 
 	struct configfs_item_operations {
 		void (*release)(struct config_item *);
-		ssize_t (*show_attribute)(struct config_item *,
-					  struct configfs_attribute *,
-					  char *);
-		ssize_t (*store_attribute)(struct config_item *,
-					   struct configfs_attribute *,
-					   const char *, size_t);
 		int (*allow_link)(struct config_item *src,
 				  struct config_item *target);
 		int (*drop_link)(struct config_item *src,
@@ -183,9 +177,7 @@ The most basic function of a config_item_type is to define what
 operations can be performed on a config_item.  All items that have been
 allocated dynamically will need to provide the ct_item_ops->release()
 method.  This method is called when the config_item's reference count
-reaches zero.  Items that wish to display an attribute need to provide
-the ct_item_ops->show_attribute() method.  Similarly, storing a new
-attribute value uses the store_attribute() method.
+reaches zero.
 
 [struct configfs_attribute]
 
@@ -193,6 +185,8 @@ attribute value uses the store_attribute() method.
 		char                    *ca_name;
 		struct module           *ca_owner;
 		umode_t                  ca_mode;
+		ssize_t (*show)(struct config_item *, char *);
+		ssize_t (*store)(struct config_item *, const char *, size_t);
 	};
 
 When a config_item wants an attribute to appear as a file in the item's
@@ -202,10 +196,10 @@ config_item_type->ct_attrs.  When the item appears in configfs, the
 attribute file will appear with the configfs_attribute->ca_name
 filename.  configfs_attribute->ca_mode specifies the file permissions.
 
-If an attribute is readable and the config_item provides a
-ct_item_ops->show_attribute() method, that method will be called
-whenever userspace asks for a read(2) on the attribute.  The converse
-will happen for write(2).
+If an attribute is readable and provides a ->show method, that method will
+be called whenever userspace asks for a read(2) on the attribute.  If an
+attribute is writable and provides a ->store  method, that method will be
+be called whenever userspace asks for a write(2) on the attribute.
 
 [struct config_group]
 
@@ -311,20 +305,10 @@ the subsystem must be ready for it.
 [An Example]
 
 The best example of these basic concepts is the simple_children
-subsystem/group and the simple_child item in configfs_example_explicit.c
-and configfs_example_macros.c.  It shows a trivial object displaying and
-storing an attribute, and a simple group creating and destroying these
-children.
-
-The only difference between configfs_example_explicit.c and
-configfs_example_macros.c is how the attributes of the childless item
-are defined.  The childless item has extended attributes, each with
-their own show()/store() operation.  This follows a convention commonly
-used in sysfs.  configfs_example_explicit.c creates these attributes
-by explicitly defining the structures involved.  Conversely
-configfs_example_macros.c uses some convenience macros from configfs.h
-to define the attributes.  These macros are similar to their sysfs
-counterparts.
+subsystem/group and the simple_child item in
+samples/configfs/configfs_sample.c. It shows a trivial object displaying
+and storing an attribute, and a simple group creating and destroying
+these children.
 
 [Hierarchy Navigation and the Subsystem Mutex]
 

fs/configfs/file.c

@@ -65,7 +65,6 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf
 {
 	struct configfs_attribute * attr = to_attr(dentry);
 	struct config_item * item = to_item(dentry->d_parent);
-	struct configfs_item_operations * ops = buffer->ops;
 	int ret = 0;
 	ssize_t count;
 
@@ -74,9 +73,6 @@ static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buf
 	if (!buffer->page)
 		return -ENOMEM;
 
-	if (ops->show_attribute)
-		count = ops->show_attribute(item, attr, buffer->page);
-	else
 	count = attr->show(item, buffer->page);
 
 	buffer->needs_read_fill = 0;
@@ -175,10 +171,7 @@ flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size
 {
 	struct configfs_attribute * attr = to_attr(dentry);
 	struct config_item * item = to_item(dentry->d_parent);
-	struct configfs_item_operations * ops = buffer->ops;
 
-	if (ops->store_attribute)
-		return ops->store_attribute(item, attr, buffer->page, count);
 	return attr->store(item, buffer->page, count);
 }
 
@@ -243,8 +236,7 @@ static int check_perm(struct inode * inode, struct file * file)
 	 * and we must have a store method.
 	 */
 	if (file->f_mode & FMODE_WRITE) {
-		if (!(inode->i_mode & S_IWUGO) ||
-		    (!ops->store_attribute && !attr->store))
+		if (!(inode->i_mode & S_IWUGO) || !attr->store)
 			goto Eaccess;
 
 	}
@@ -254,8 +246,7 @@ static int check_perm(struct inode * inode, struct file * file)
 	 * must be a show method for it.
 	 */
 	if (file->f_mode & FMODE_READ) {
-		if (!(inode->i_mode & S_IRUGO) ||
-		    (!ops->show_attribute && !attr->show))
+		if (!(inode->i_mode & S_IRUGO) || !attr->show)
 			goto Eaccess;
 	}
 

include/linux/configfs.h

@@ -154,86 +154,6 @@ static struct configfs_attribute _pfx##attr_##_name = {	\
 	.store		= _pfx##_name##_store,		\
 }
 
-/*
- * Users often need to create attribute structures for their configurable
- * attributes, containing a configfs_attribute member and function pointers
- * for the show() and store() operations on that attribute. If they don't
- * need anything else on the extended attribute structure, they can use
- * this macro to define it  The argument _item is the name of the
- * config_item structure.
- */
-#define CONFIGFS_ATTR_STRUCT(_item)					\
-struct _item##_attribute {						\
-	struct configfs_attribute attr;					\
-	ssize_t (*show)(struct _item *, char *);			\
-	ssize_t (*store)(struct _item *, const char *, size_t);		\
-}
-
-/*
- * With the extended attribute structure, users can use this macro
- * (similar to sysfs' __ATTR) to make defining attributes easier.
- * An example:
- * #define MYITEM_ATTR(_name, _mode, _show, _store)	\
- * struct myitem_attribute childless_attr_##_name =	\
- *         __CONFIGFS_ATTR(_name, _mode, _show, _store)
- */
-#define __CONFIGFS_ATTR(_name, _mode, _show, _store)			\
-{									\
-	.attr	= {							\
-			.ca_name = __stringify(_name),			\
-			.ca_mode = _mode,				\
-			.ca_owner = THIS_MODULE,			\
-	},								\
-	.show	= _show,						\
-	.store	= _store,						\
-}
-/* Here is a readonly version, only requiring a show() operation */
-#define __CONFIGFS_ATTR_RO(_name, _show)				\
-{									\
-	.attr	= {							\
-			.ca_name = __stringify(_name),			\
-			.ca_mode = 0444,				\
-			.ca_owner = THIS_MODULE,			\
-	},								\
-	.show	= _show,						\
-}
-
-/*
- * With these extended attributes, the simple show_attribute() and
- * store_attribute() operations need to call the show() and store() of the
- * attributes.  This is a common pattern, so we provide a macro to define
- * them.  The argument _item is the name of the config_item structure.
- * This macro expects the attributes to be named "struct <name>_attribute"
- * and the function to_<name>() to exist;
- */
-#define CONFIGFS_ATTR_OPS(_item)					\
-static ssize_t _item##_attr_show(struct config_item *item,		\
-				 struct configfs_attribute *attr,	\
-				 char *page)				\
-{									\
-	struct _item *_item = to_##_item(item);				\
-	struct _item##_attribute *_item##_attr =			\
-		container_of(attr, struct _item##_attribute, attr);	\
-	ssize_t ret = 0;						\
-									\
-	if (_item##_attr->show)						\
-		ret = _item##_attr->show(_item, page);			\
-	return ret;							\
-}									\
-static ssize_t _item##_attr_store(struct config_item *item,		\
-				  struct configfs_attribute *attr,	\
-				  const char *page, size_t count)	\
-{									\
-	struct _item *_item = to_##_item(item);				\
-	struct _item##_attribute *_item##_attr =			\
-		container_of(attr, struct _item##_attribute, attr);	\
-	ssize_t ret = -EINVAL;						\
-									\
-	if (_item##_attr->store)					\
-		ret = _item##_attr->store(_item, page, count);		\
-	return ret;							\
-}
-
 /*
  * If allow_link() exists, the item can symlink(2) out to other
  * items.  If the item is a group, it may support mkdir(2).
@@ -250,8 +170,6 @@ static ssize_t _item##_attr_store(struct config_item *item,		\
  */
 struct configfs_item_operations {
 	void (*release)(struct config_item *);
-	ssize_t	(*show_attribute)(struct config_item *, struct configfs_attribute *,char *);
-	ssize_t	(*store_attribute)(struct config_item *,struct configfs_attribute *,const char *, size_t);
 	int (*allow_link)(struct config_item *src, struct config_item *target);
 	int (*drop_link)(struct config_item *src, struct config_item *target);
 };

samples/Kconfig

@@ -70,4 +70,10 @@ config SAMPLE_LIVEPATCH
 	  Builds a sample live patch that replaces the procfs handler
 	  for /proc/cmdline to print "this has been live patched".
 
+config SAMPLE_CONFIGFS
+	tristate "Build configfs patching sample -- loadable modules only"
+	depends on CONFIGFS_FS && m
+	help
+	  Builds a sample configfs interface.
+
 endif # SAMPLES

samples/Makefile

 # Makefile for Linux samples code
 
 obj-$(CONFIG_SAMPLES)	+= kobject/ kprobes/ trace_events/ livepatch/ \
-			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/
+			   hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \
+			   configfs/

samples/configfs/Makefile

+
+obj-$(CONFIG_SAMPLE_CONFIGFS) += configfs_sample.o

Documentation/filesystems/configfs/configfs_example_macros.c → samples/configfs/configfs_sample.c

@@ -54,18 +54,13 @@ struct childless {
 
 static inline struct childless *to_childless(struct config_item *item)
 {
-	return item ? container_of(to_configfs_subsystem(to_config_group(item)), struct childless, subsys) : NULL;
+	return item ? container_of(to_configfs_subsystem(to_config_group(item)),
+			struct childless, subsys) : NULL;
 }
 
-CONFIGFS_ATTR_STRUCT(childless);
-#define CHILDLESS_ATTR(_name, _mode, _show, _store)	\
-struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR(_name, _mode, _show, _store)
-#define CHILDLESS_ATTR_RO(_name, _show)	\
-struct childless_attribute childless_attr_##_name = __CONFIGFS_ATTR_RO(_name, _show);
-
-static ssize_t childless_showme_read(struct childless *childless,
-				     char *page)
+static ssize_t childless_showme_show(struct config_item *item, char *page)
 {
+	struct childless *childless = to_childless(item);
 	ssize_t pos;
 
 	pos = sprintf(page, "%d\n", childless->showme);
@@ -74,16 +69,15 @@ static ssize_t childless_showme_read(struct childless *childless,
 	return pos;
 }
 
-static ssize_t childless_storeme_read(struct childless *childless,
-				      char *page)
+static ssize_t childless_storeme_show(struct config_item *item, char *page)
 {
-	return sprintf(page, "%d\n", childless->storeme);
+	return sprintf(page, "%d\n", to_childless(item)->storeme);
 }
 
-static ssize_t childless_storeme_write(struct childless *childless,
-				       const char *page,
-				       size_t count)
+static ssize_t childless_storeme_store(struct config_item *item,
+		const char *page, size_t count)
 {
+	struct childless *childless = to_childless(item);
 	unsigned long tmp;
 	char *p = (char *) page;
 
@@ -99,8 +93,7 @@ static ssize_t childless_storeme_write(struct childless *childless,
 	return count;
 }
 
-static ssize_t childless_description_read(struct childless *childless,
-					  char *page)
+static ssize_t childless_description_show(struct config_item *item, char *page)
 {
 	return sprintf(page,
 "[01-childless]\n"
@@ -111,26 +104,18 @@ static ssize_t childless_description_read(struct childless *childless,
 "than a directory in /proc.\n");
 }
 
-CHILDLESS_ATTR_RO(showme, childless_showme_read);
-CHILDLESS_ATTR(storeme, S_IRUGO | S_IWUSR, childless_storeme_read,
-	       childless_storeme_write);
-CHILDLESS_ATTR_RO(description, childless_description_read);
+CONFIGFS_ATTR_RO(childless_, showme);
+CONFIGFS_ATTR(childless_, storeme);
+CONFIGFS_ATTR_RO(childless_, description);
 
 static struct configfs_attribute *childless_attrs[] = {
-	&childless_attr_showme.attr,
-	&childless_attr_storeme.attr,
-	&childless_attr_description.attr,
+	&childless_attr_showme,
+	&childless_attr_storeme,
+	&childless_attr_description,
 	NULL,
 };
 
-CONFIGFS_ATTR_OPS(childless);
-static struct configfs_item_operations childless_item_ops = {
-	.show_attribute		= childless_attr_show,
-	.store_attribute	= childless_attr_store,
-};
-
 static struct config_item_type childless_type = {
-	.ct_item_ops	= &childless_item_ops,
 	.ct_attrs	= childless_attrs,
 	.ct_owner	= THIS_MODULE,
 };
@@ -168,31 +153,12 @@ static inline struct simple_child *to_simple_child(struct config_item *item)
 	return item ? container_of(item, struct simple_child, item) : NULL;
 }
 
-static struct configfs_attribute simple_child_attr_storeme = {
-	.ca_owner = THIS_MODULE,
-	.ca_name = "storeme",
-	.ca_mode = S_IRUGO | S_IWUSR,
-};
-
-static struct configfs_attribute *simple_child_attrs[] = {
-	&simple_child_attr_storeme,
-	NULL,
-};
-
-static ssize_t simple_child_attr_show(struct config_item *item,
-				      struct configfs_attribute *attr,
-				      char *page)
+static ssize_t simple_child_storeme_show(struct config_item *item, char *page)
 {
-	ssize_t count;
-	struct simple_child *simple_child = to_simple_child(item);
-
-	count = sprintf(page, "%d\n", simple_child->storeme);
-
-	return count;
+	return sprintf(page, "%d\n", to_simple_child(item)->storeme);
 }
 
-static ssize_t simple_child_attr_store(struct config_item *item,
-				       struct configfs_attribute *attr,
+static ssize_t simple_child_storeme_store(struct config_item *item,
 		const char *page, size_t count)
 {
 	struct simple_child *simple_child = to_simple_child(item);
@@ -211,6 +177,13 @@ static ssize_t simple_child_attr_store(struct config_item *item,
 	return count;
 }
 
+CONFIGFS_ATTR(simple_child_, storeme);
+
+static struct configfs_attribute *simple_child_attrs[] = {
+	&simple_child_attr_storeme,
+	NULL,
+};
+
 static void simple_child_release(struct config_item *item)
 {
 	kfree(to_simple_child(item));
@@ -218,8 +191,6 @@ static void simple_child_release(struct config_item *item)
 
 static struct configfs_item_operations simple_child_item_ops = {
 	.release		= simple_child_release,
-	.show_attribute		= simple_child_attr_show,
-	.store_attribute	= simple_child_attr_store,
 };
 
 static struct config_item_type simple_child_type = {
@@ -235,10 +206,12 @@ struct simple_children {
 
 static inline struct simple_children *to_simple_children(struct config_item *item)
 {
-	return item ? container_of(to_config_group(item), struct simple_children, group) : NULL;
+	return item ? container_of(to_config_group(item),
+			struct simple_children, group) : NULL;
 }
 
-static struct config_item *simple_children_make_item(struct config_group *group, const char *name)
+static struct config_item *simple_children_make_item(struct config_group *group,
+		const char *name)
 {
 	struct simple_child *simple_child;
 
@@ -254,19 +227,7 @@ static struct config_item *simple_children_make_item(struct config_group *group,
 	return &simple_child->item;
 }
 
-static struct configfs_attribute simple_children_attr_description = {
-	.ca_owner = THIS_MODULE,
-	.ca_name = "description",
-	.ca_mode = S_IRUGO,
-};
-
-static struct configfs_attribute *simple_children_attrs[] = {
-	&simple_children_attr_description,
-	NULL,
-};
-
-static ssize_t simple_children_attr_show(struct config_item *item,
-					 struct configfs_attribute *attr,
+static ssize_t simple_children_description_show(struct config_item *item,
 		char *page)
 {
 	return sprintf(page,
@@ -276,6 +237,13 @@ static ssize_t simple_children_attr_show(struct config_item *item,
 "items have only one attribute that is readable and writeable.\n");
 }
 
+CONFIGFS_ATTR_RO(simple_children_, description);
+
+static struct configfs_attribute *simple_children_attrs[] = {
+	&simple_children_attr_description,
+	NULL,
+};
+
 static void simple_children_release(struct config_item *item)
 {
 	kfree(to_simple_children(item));
@@ -283,7 +251,6 @@ static void simple_children_release(struct config_item *item)
 
 static struct configfs_item_operations simple_children_item_ops = {
 	.release	= simple_children_release,
-	.show_attribute	= simple_children_attr_show,
 };
 
 /*
@@ -323,7 +290,8 @@ static struct configfs_subsystem simple_children_subsys = {
  * children of its own.
  */
 
-static struct config_group *group_children_make_group(struct config_group *group, const char *name)
+static struct config_group *group_children_make_group(
+		struct config_group *group, const char *name)
 {
 	struct simple_children *simple_children;
 
@@ -338,19 +306,7 @@ static struct config_group *group_children_make_group(struct config_group *group
 	return &simple_children->group;
 }
 
-static struct configfs_attribute group_children_attr_description = {
-	.ca_owner = THIS_MODULE,
-	.ca_name = "description",
-	.ca_mode = S_IRUGO,
-};
-
-static struct configfs_attribute *group_children_attrs[] = {
-	&group_children_attr_description,
-	NULL,
-};
-
-static ssize_t group_children_attr_show(struct config_item *item,
-					struct configfs_attribute *attr,
+static ssize_t group_children_description_show(struct config_item *item,
 		char *page)
 {
 	return sprintf(page,
@@ -360,8 +316,11 @@ static ssize_t group_children_attr_show(struct config_item *item,
 "groups are like the subsystem simple-children.\n");
 }
 
-static struct configfs_item_operations group_children_item_ops = {
-	.show_attribute	= group_children_attr_show,
+CONFIGFS_ATTR_RO(group_children_, description);
+
+static struct configfs_attribute *group_children_attrs[] = {
+	&group_children_attr_description,
+	NULL,
 };
 
 /*
@@ -373,7 +332,6 @@ static struct configfs_group_operations group_children_group_ops = {
 };
 
 static struct config_item_type group_children_type = {
-	.ct_item_ops	= &group_children_item_ops,
 	.ct_group_ops	= &group_children_group_ops,
 	.ct_attrs	= group_children_attrs,
 	.ct_owner	= THIS_MODULE,