Merge http://oss.oracle.com/git/ocfs2

Documentation/filesystems/00-INDEX

@@ -12,10 +12,14 @@ cifs.txt
 	- description of the CIFS filesystem
 coda.txt
 	- description of the CODA filesystem.
+configfs/
+	- directory containing configfs documentation and example code.
 cramfs.txt
 	- info on the cram filesystem for small storage (ROMs etc)
 devfs/
 	- directory containing devfs documentation.
+dlmfs.txt
+	- info on the userspace interface to the OCFS2 DLM.
 ext2.txt
 	- info, mount options and specifications for the Ext2 filesystem.
 hpfs.txt
@@ -30,6 +34,8 @@ ntfs.txt
 	- info and mount options for the NTFS filesystem (Windows NT).
 proc.txt
 	- info on Linux's /proc filesystem.
+ocfs2.txt
+	- info and mount options for the OCFS2 clustered filesystem.
 romfs.txt
 	- Description of the ROMFS filesystem.
 smbfs.txt

Documentation/filesystems/configfs/configfs.txt

+
+configfs - Userspace-driven kernel object configuation.
+
+Joel Becker <joel.becker@oracle.com>
+
+Updated: 31 March 2005
+
+Copyright (c) 2005 Oracle Corporation,
+	Joel Becker <joel.becker@oracle.com>
+
+
+[What is configfs?]
+
+configfs is a ram-based filesystem that provides the converse of
+sysfs's functionality.  Where sysfs is a filesystem-based view of
+kernel objects, configfs is a filesystem-based manager of kernel
+objects, or config_items.
+
+With sysfs, an object is created in kernel (for example, when a device
+is discovered) and it is registered with sysfs.  Its attributes then
+appear in sysfs, allowing userspace to read the attributes via
+readdir(3)/read(2).  It may allow some attributes to be modified via
+write(2).  The important point is that the object is created and
+destroyed in kernel, the kernel controls the lifecycle of the sysfs
+representation, and sysfs is merely a window on all this.
+
+A configfs config_item is created via an explicit userspace operation:
+mkdir(2).  It is destroyed via rmdir(2).  The attributes appear at
+mkdir(2) time, and can be read or modified via read(2) and write(2).
+As with sysfs, readdir(3) queries the list of items and/or attributes.
+symlink(2) can be used to group items together.  Unlike sysfs, the
+lifetime of the representation is completely driven by userspace.  The
+kernel modules backing the items must respond to this.
+
+Both sysfs and configfs can and should exist together on the same
+system.  One is not a replacement for the other.
+
+[Using configfs]
+
+configfs can be compiled as a module or into the kernel.  You can access
+it by doing
+
+	mount -t configfs none /config
+
+The configfs tree will be empty unless client modules are also loaded.
+These are modules that register their item types with configfs as
+subsystems.  Once a client subsystem is loaded, it will appear as a
+subdirectory (or more than one) under /config.  Like sysfs, the
+configfs tree is always there, whether mounted on /config or not.
+
+An item is created via mkdir(2).  The item's attributes will also
+appear at this time.  readdir(3) can determine what the attributes are,
+read(2) can query their default values, and write(2) can store new
+values.  Like sysfs, attributes should be ASCII text files, preferably
+with only one value per file.  The same efficiency caveats from sysfs
+apply.  Don't mix more than one attribute in one attribute file.
+
+Like sysfs, configfs expects write(2) to store the entire buffer at
+once.  When writing to configfs attributes, userspace processes should
+first read the entire file, modify the portions they wish to change, and
+then write the entire buffer back.  Attribute files have a maximum size
+of one page (PAGE_SIZE, 4096 on i386).
+
+When an item needs to be destroyed, remove it with rmdir(2).  An
+item cannot be destroyed if any other item has a link to it (via
+symlink(2)).  Links can be removed via unlink(2).
+
+[Configuring FakeNBD: an Example]
+
+Imagine there's a Network Block Device (NBD) driver that allows you to
+access remote block devices.  Call it FakeNBD.  FakeNBD uses configfs
+for its configuration.  Obviously, there will be a nice program that
+sysadmins use to configure FakeNBD, but somehow that program has to tell
+the driver about it.  Here's where configfs comes in.
+
+When the FakeNBD driver is loaded, it registers itself with configfs.
+readdir(3) sees this just fine:
+
+	# ls /config
+	fakenbd
+
+A fakenbd connection can be created with mkdir(2).  The name is
+arbitrary, but likely the tool will make some use of the name.  Perhaps
+it is a uuid or a disk name:
+
+	# mkdir /config/fakenbd/disk1
+	# ls /config/fakenbd/disk1
+	target device rw
+
+The target attribute contains the IP address of the server FakeNBD will
+connect to.  The device attribute is the device on the server.
+Predictably, the rw attribute determines whether the connection is
+read-only or read-write.
+
+	# echo 10.0.0.1 > /config/fakenbd/disk1/target
+	# echo /dev/sda1 > /config/fakenbd/disk1/device
+	# echo 1 > /config/fakenbd/disk1/rw
+
+That's it.  That's all there is.  Now the device is configured, via the
+shell no less.
+
+[Coding With configfs]
+
+Every object in configfs is a config_item.  A config_item reflects an
+object in the subsystem.  It has attributes that match values on that
+object.  configfs handles the filesystem representation of that object
+and its attributes, allowing the subsystem to ignore all but the
+basic show/store interaction.
+
+Items are created and destroyed inside a config_group.  A group is a
+collection of items that share the same attributes and operations.
+Items are created by mkdir(2) and removed by rmdir(2), but configfs
+handles that.  The group has a set of operations to perform these tasks
+
+A subsystem is the top level of a client module.  During initialization,
+the client module registers the subsystem with configfs, the subsystem
+appears as a directory at the top of the configfs filesystem.  A
+subsystem is also a config_group, and can do everything a config_group
+can.
+
+[struct config_item]
+
+	struct config_item {
+		char                    *ci_name;
+		char                    ci_namebuf[UOBJ_NAME_LEN];
+		struct kref             ci_kref;
+		struct list_head        ci_entry;
+		struct config_item      *ci_parent;
+		struct config_group     *ci_group;
+		struct config_item_type *ci_type;
+		struct dentry           *ci_dentry;
+	};
+
+	void config_item_init(struct config_item *);
+	void config_item_init_type_name(struct config_item *,
+					const char *name,
+					struct config_item_type *type);
+	struct config_item *config_item_get(struct config_item *);
+	void config_item_put(struct config_item *);
+
+Generally, struct config_item is embedded in a container structure, a
+structure that actually represents what the subsystem is doing.  The
+config_item portion of that structure is how the object interacts with
+configfs.
+
+Whether statically defined in a source file or created by a parent
+config_group, a config_item must have one of the _init() functions
+called on it.  This initializes the reference count and sets up the
+appropriate fields.
+
+All users of a config_item should have a reference on it via
+config_item_get(), and drop the reference when they are done via
+config_item_put().
+
+By itself, a config_item cannot do much more than appear in configfs.
+Usually a subsystem wants the item to display and/or store attributes,
+among other things.  For that, it needs a type.
+
+[struct config_item_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,
+				 struct config_item *target);
+	};
+
+	struct config_item_type {
+		struct module                           *ct_owner;
+		struct configfs_item_operations         *ct_item_ops;
+		struct configfs_group_operations        *ct_group_ops;
+		struct configfs_attribute               **ct_attrs;
+	};
+
+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.
+
+[struct configfs_attribute]
+
+	struct configfs_attribute {
+		char                    *ca_name;
+		struct module           *ca_owner;
+		mode_t                  ca_mode;
+	};
+
+When a config_item wants an attribute to appear as a file in the item's
+configfs directory, it must define a configfs_attribute describing it.
+It then adds the attribute to the NULL-terminated array
+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).
+
+[struct config_group]
+
+A config_item cannot live in a vaccum.  The only way one can be created
+is via mkdir(2) on a config_group.  This will trigger creation of a
+child item.
+
+	struct config_group {
+		struct config_item		cg_item;
+		struct list_head		cg_children;
+		struct configfs_subsystem 	*cg_subsys;
+		struct config_group		**default_groups;
+	};
+
+	void config_group_init(struct config_group *group);
+	void config_group_init_type_name(struct config_group *group,
+					 const char *name,
+					 struct config_item_type *type);
+
+
+The config_group structure contains a config_item.  Properly configuring
+that item means that a group can behave as an item in its own right.
+However, it can do more: it can create child items or groups.  This is
+accomplished via the group operations specified on the group's
+config_item_type.
+
+	struct configfs_group_operations {
+		struct config_item *(*make_item)(struct config_group *group,
+						 const char *name);
+		struct config_group *(*make_group)(struct config_group *group,
+						   const char *name);
+		int (*commit_item)(struct config_item *item);
+		void (*drop_item)(struct config_group *group,
+				  struct config_item *item);
+	};
+
+A group creates child items by providing the
+ct_group_ops->make_item() method.  If provided, this method is called from mkdir(2) in the group's directory.  The subsystem allocates a new
+config_item (or more likely, its container structure), initializes it,
+and returns it to configfs.  Configfs will then populate the filesystem
+tree to reflect the new item.
+
+If the subsystem wants the child to be a group itself, the subsystem
+provides ct_group_ops->make_group().  Everything else behaves the same,
+using the group _init() functions on the group.
+
+Finally, when userspace calls rmdir(2) on the item or group,
+ct_group_ops->drop_item() is called.  As a config_group is also a
+config_item, it is not necessary for a seperate drop_group() method.
+The subsystem must config_item_put() the reference that was initialized
+upon item allocation.  If a subsystem has no work to do, it may omit
+the ct_group_ops->drop_item() method, and configfs will call
+config_item_put() on the item on behalf of the subsystem.
+
+IMPORTANT: drop_item() is void, and as such cannot fail.  When rmdir(2)
+is called, configfs WILL remove the item from the filesystem tree
+(assuming that it has no children to keep it busy).  The subsystem is
+responsible for responding to this.  If the subsystem has references to
+the item in other threads, the memory is safe.  It may take some time
+for the item to actually disappear from the subsystem's usage.  But it
+is gone from configfs.
+
+A config_group cannot be removed while it still has child items.  This
+is implemented in the configfs rmdir(2) code.  ->drop_item() will not be
+called, as the item has not been dropped.  rmdir(2) will fail, as the
+directory is not empty.
+
+[struct configfs_subsystem]
+
+A subsystem must register itself, ususally at module_init time.  This
+tells configfs to make the subsystem appear in the file tree.
+
+	struct configfs_subsystem {
+		struct config_group	su_group;
+		struct semaphore	su_sem;
+	};
+
+	int configfs_register_subsystem(struct configfs_subsystem *subsys);
+	void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
+
+	A subsystem consists of a toplevel config_group and a semaphore.
+The group is where child config_items are created.  For a subsystem,
+this group is usually defined statically.  Before calling
+configfs_register_subsystem(), the subsystem must have initialized the
+group via the usual group _init() functions, and it must also have
+initialized the semaphore.
+	When the register call returns, the subsystem is live, and it
+will be visible via configfs.  At that point, mkdir(2) can be called and
+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.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 Semaphore]
+
+There is an extra bonus that configfs provides.  The config_groups and
+config_items are arranged in a hierarchy due to the fact that they
+appear in a filesystem.  A subsystem is NEVER to touch the filesystem
+parts, but the subsystem might be interested in this hierarchy.  For
+this reason, the hierarchy is mirrored via the config_group->cg_children
+and config_item->ci_parent structure members.
+
+A subsystem can navigate the cg_children list and the ci_parent pointer
+to see the tree created by the subsystem.  This can race with configfs'
+management of the hierarchy, so configfs uses the subsystem semaphore to
+protect modifications.  Whenever a subsystem wants to navigate the
+hierarchy, it must do so under the protection of the subsystem
+semaphore.
+
+A subsystem will be prevented from acquiring the semaphore while a newly
+allocated item has not been linked into this hierarchy.   Similarly, it
+will not be able to acquire the semaphore while a dropping item has not
+yet been unlinked.  This means that an item's ci_parent pointer will
+never be NULL while the item is in configfs, and that an item will only
+be in its parent's cg_children list for the same duration.  This allows
+a subsystem to trust ci_parent and cg_children while they hold the
+semaphore.
+
+[Item Aggregation Via symlink(2)]
+
+configfs provides a simple group via the group->item parent/child
+relationship.  Often, however, a larger environment requires aggregation
+outside of the parent/child connection.  This is implemented via
+symlink(2).
+
+A config_item may provide the ct_item_ops->allow_link() and
+ct_item_ops->drop_link() methods.  If the ->allow_link() method exists,
+symlink(2) may be called with the config_item as the source of the link.
+These links are only allowed between configfs config_items.  Any
+symlink(2) attempt outside the configfs filesystem will be denied.
+
+When symlink(2) is called, the source config_item's ->allow_link()
+method is called with itself and a target item.  If the source item
+allows linking to target item, it returns 0.  A source item may wish to
+reject a link if it only wants links to a certain type of object (say,
+in its own subsystem).
+
+When unlink(2) is called on the symbolic link, the source item is
+notified via the ->drop_link() method.  Like the ->drop_item() method,
+this is a void function and cannot return failure.  The subsystem is
+responsible for responding to the change.
+
+A config_item cannot be removed while it links to any other item, nor
+can it be removed while an item links to it.  Dangling symlinks are not
+allowed in configfs.
+
+[Automatically Created Subgroups]
+
+A new config_group may want to have two types of child config_items.
+While this could be codified by magic names in ->make_item(), it is much
+more explicit to have a method whereby userspace sees this divergence.
+
+Rather than have a group where some items behave differently than
+others, configfs provides a method whereby one or many subgroups are
+automatically created inside the parent at its creation.  Thus,
+mkdir("parent) results in "parent", "parent/subgroup1", up through
+"parent/subgroupN".  Items of type 1 can now be created in
+"parent/subgroup1", and items of type N can be created in
+"parent/subgroupN".
+
+These automatic subgroups, or default groups, do not preclude other
+children of the parent group.  If ct_group_ops->make_group() exists,
+other child groups can be created on the parent group directly.
+
+A configfs subsystem specifies default groups by filling in the
+NULL-terminated array default_groups on the config_group structure.
+Each group in that array is populated in the configfs tree at the same
+time as the parent group.  Similarly, they are removed at the same time
+as the parent.  No extra notification is provided.  When a ->drop_item()
+method call notifies the subsystem the parent group is going away, it
+also means every default group child associated with that parent group.
+
+As a consequence of this, default_groups cannot be removed directly via
+rmdir(2).  They also are not considered when rmdir(2) on the parent
+group is checking for children.
+
+[Committable Items]
+
+NOTE: Committable items are currently unimplemented.
+
+Some config_items cannot have a valid initial state.  That is, no
+default values can be specified for the item's attributes such that the
+item can do its work.  Userspace must configure one or more attributes,
+after which the subsystem can start whatever entity this item
+represents.
+
+Consider the FakeNBD device from above.  Without a target address *and*
+a target device, the subsystem has no idea what block device to import.
+The simple example assumes that the subsystem merely waits until all the
+appropriate attributes are configured, and then connects.  This will,
+indeed, work, but now every attribute store must check if the attributes
+are initialized.  Every attribute store must fire off the connection if
+that condition is met.
+
+Far better would be an explicit action notifying the subsystem that the
+config_item is ready to go.  More importantly, an explicit action allows
+the subsystem to provide feedback as to whether the attibutes are
+initialized in a way that makes sense.  configfs provides this as
+committable items.
+
+configfs still uses only normal filesystem operations.  An item is
+committed via rename(2).  The item is moved from a directory where it
+can be modified to a directory where it cannot.
+
+Any group that provides the ct_group_ops->commit_item() method has
+committable items.  When this group appears in configfs, mkdir(2) will
+not work directly in the group.  Instead, the group will have two
+subdirectories: "live" and "pending".  The "live" directory does not
+support mkdir(2) or rmdir(2) either.  It only allows rename(2).  The
+"pending" directory does allow mkdir(2) and rmdir(2).  An item is
+created in the "pending" directory.  Its attributes can be modified at
+will.  Userspace commits the item by renaming it into the "live"
+directory.  At this point, the subsystem recieves the ->commit_item()
+callback.  If all required attributes are filled to satisfaction, the
+method returns zero and the item is moved to the "live" directory.
+
+As rmdir(2) does not work in the "live" directory, an item must be
+shutdown, or "uncommitted".  Again, this is done via rename(2), this
+time from the "live" directory back to the "pending" one.  The subsystem
+is notified by the ct_group_ops->uncommit_object() method.
+
+

Documentation/filesystems/configfs/configfs_example.c

+/*
+ * vim: noexpandtab ts=8 sts=0 sw=8:
+ *
+ * configfs_example.c - This file is a demonstration module containing
+ *      a number of configfs subsystems.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include <linux/configfs.h>
+
+
+
+/*
+ * 01-childless
+ *
+ * This first example is a childless subsystem.  It cannot create
+ * any config_items.  It just has attributes.
+ *
+ * Note that we are enclosing the configfs_subsystem inside a container.
+ * This is not necessary if a subsystem has no attributes directly
+ * on the subsystem.  See the next example, 02-simple-children, for
+ * such a subsystem.
+ */
+
+struct childless {
+	struct configfs_subsystem subsys;
+	int showme;
+	int storeme;
+};
+
+struct childless_attribute {
+	struct configfs_attribute attr;
+	ssize_t (*show)(struct childless *, char *);
+	ssize_t (*store)(struct childless *, const char *, size_t);
+};
+
+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;
+}
+
+static ssize_t childless_showme_read(struct childless *childless,
+				     char *page)
+{
+	ssize_t pos;
+
+	pos = sprintf(page, "%d\n", childless->showme);
+	childless->showme++;
+
+	return pos;
+}
+
+static ssize_t childless_storeme_read(struct childless *childless,
+				      char *page)
+{
+	return sprintf(page, "%d\n", childless->storeme);
+}
+
+static ssize_t childless_storeme_write(struct childless *childless,
+				       const char *page,
+				       size_t count)
+{
+	unsigned long tmp;
+	char *p = (char *) page;
+
+	tmp = simple_strtoul(p, &p, 10);
+	if (!p || (*p && (*p != '\n')))
+		return -EINVAL;
+
+	if (tmp > INT_MAX)
+		return -ERANGE;
+
+	childless->storeme = tmp;
+
+	return count;
+}
+
+static ssize_t childless_description_read(struct childless *childless,
+					  char *page)
+{
+	return sprintf(page,
+"[01-childless]\n"
+"\n"
+"The childless subsystem is the simplest possible subsystem in\n"
+"configfs.  It does not support the creation of child config_items.\n"
+"It only has a few attributes.  In fact, it isn't much different\n"
+"than a directory in /proc.\n");
+}
+
+static struct childless_attribute childless_attr_showme = {
+	.attr	= { .ca_owner = THIS_MODULE, .ca_name = "showme", .ca_mode = S_IRUGO },
+	.show	= childless_showme_read,
+};
+static struct childless_attribute childless_attr_storeme = {
+	.attr	= { .ca_owner = THIS_MODULE, .ca_name = "storeme", .ca_mode = S_IRUGO | S_IWUSR },
+	.show	= childless_storeme_read,
+	.store	= childless_storeme_write,
+};
+static struct childless_attribute childless_attr_description = {
+	.attr = { .ca_owner = THIS_MODULE, .ca_name = "description", .ca_mode = S_IRUGO },
+	.show = childless_description_read,
+};
+
+static struct configfs_attribute *childless_attrs[] = {
+	&childless_attr_showme.attr,
+	&childless_attr_storeme.attr,
+	&childless_attr_description.attr,
+	NULL,
+};
+
+static ssize_t childless_attr_show(struct config_item *item,
+				   struct configfs_attribute *attr,
+				   char *page)
+{
+	struct childless *childless = to_childless(item);
+	struct childless_attribute *childless_attr =
+		container_of(attr, struct childless_attribute, attr);
+	ssize_t ret = 0;
+
+	if (childless_attr->show)
+		ret = childless_attr->show(childless, page);
+	return ret;
+}
+
+static ssize_t childless_attr_store(struct config_item *item,
+				    struct configfs_attribute *attr,
+				    const char *page, size_t count)
+{
+	struct childless *childless = to_childless(item);
+	struct childless_attribute *childless_attr =
+		container_of(attr, struct childless_attribute, attr);
+	ssize_t ret = -EINVAL;
+
+	if (childless_attr->store)
+		ret = childless_attr->store(childless, page, count);
+	return ret;
+}
+
+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,
+};
+
+static struct childless childless_subsys = {
+	.subsys = {
+		.su_group = {
+			.cg_item = {
+				.ci_namebuf = "01-childless",
+				.ci_type = &childless_type,
+			},
+		},
+	},
+};
+
+
+/* ----------------------------------------------------------------- */
+
+/*
+ * 02-simple-children
+ *
+ * This example merely has a simple one-attribute child.  Note that
+ * there is no extra attribute structure, as the child's attribute is
+ * known from the get-go.  Also, there is no container for the
+ * subsystem, as it has no attributes of its own.
+ */
+
+struct simple_child {
+	struct config_item item;
+	int storeme;
+};
+
+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)
+{
+	ssize_t count;
+	struct simple_child *simple_child = to_simple_child(item);
+
+	count = sprintf(page, "%d\n", simple_child->storeme);
+
+	return count;
+}
+
+static ssize_t simple_child_attr_store(struct config_item *item,
+				       struct configfs_attribute *attr,
+				       const char *page, size_t count)
+{
+	struct simple_child *simple_child = to_simple_child(item);
+	unsigned long tmp;
+	char *p = (char *) page;
+
+	tmp = simple_strtoul(p, &p, 10);
+	if (!p || (*p && (*p != '\n')))
+		return -EINVAL;
+
+	if (tmp > INT_MAX)
+		return -ERANGE;
+
+	simple_child->storeme = tmp;
+
+	return count;
+}
+
+static void simple_child_release(struct config_item *item)
+{
+	kfree(to_simple_child(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 = {
+	.ct_item_ops	= &simple_child_item_ops,
+	.ct_attrs	= simple_child_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+
+static struct config_item *simple_children_make_item(struct config_group *group, const char *name)
+{
+	struct simple_child *simple_child;
+
+	simple_child = kmalloc(sizeof(struct simple_child), GFP_KERNEL);
+	if (!simple_child)
+		return NULL;
+
+	memset(simple_child, 0, sizeof(struct simple_child));
+
+	config_item_init_type_name(&simple_child->item, name,
+				   &simple_child_type);
+
+	simple_child->storeme = 0;
+
+	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,
+			   		 char *page)
+{
+	return sprintf(page,
+"[02-simple-children]\n"
+"\n"
+"This subsystem allows the creation of child config_items.  These\n"
+"items have only one attribute that is readable and writeable.\n");
+}
+
+static struct configfs_item_operations simple_children_item_ops = {
+	.show_attribute	= simple_children_attr_show,
+};
+
+/*
+ * Note that, since no extra work is required on ->drop_item(),
+ * no ->drop_item() is provided.
+ */
+static struct configfs_group_operations simple_children_group_ops = {
+	.make_item	= simple_children_make_item,
+};
+
+static struct config_item_type simple_children_type = {
+	.ct_item_ops	= &simple_children_item_ops,
+	.ct_group_ops	= &simple_children_group_ops,
+	.ct_attrs	= simple_children_attrs,
+};
+
+static struct configfs_subsystem simple_children_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "02-simple-children",
+			.ci_type = &simple_children_type,
+		},
+	},
+};
+
+
+/* ----------------------------------------------------------------- */
+
+/*
+ * 03-group-children
+ *
+ * This example reuses the simple_children group from above.  However,
+ * the simple_children group is not the subsystem itself, it is a
+ * child of the subsystem.  Creation of a group in the subsystem creates
+ * a new simple_children group.  That group can then have simple_child
+ * children of its own.
+ */
+
+struct simple_children {
+	struct config_group group;
+};
+
+static struct config_group *group_children_make_group(struct config_group *group, const char *name)
+{
+	struct simple_children *simple_children;
+
+	simple_children = kmalloc(sizeof(struct simple_children),
+				  GFP_KERNEL);
+	if (!simple_children)
+		return NULL;
+
+	memset(simple_children, 0, sizeof(struct simple_children));
+
+	config_group_init_type_name(&simple_children->group, name,
+				    &simple_children_type);
+
+	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,
+			   		char *page)
+{
+	return sprintf(page,
+"[03-group-children]\n"
+"\n"
+"This subsystem allows the creation of child config_groups.  These\n"
+"groups are like the subsystem simple-children.\n");
+}
+
+static struct configfs_item_operations group_children_item_ops = {
+	.show_attribute	= group_children_attr_show,
+};
+
+/*
+ * Note that, since no extra work is required on ->drop_item(),
+ * no ->drop_item() is provided.
+ */
+static struct configfs_group_operations group_children_group_ops = {
+	.make_group	= group_children_make_group,
+};
+
+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,
+};
+
+static struct configfs_subsystem group_children_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "03-group-children",
+			.ci_type = &group_children_type,
+		},
+	},
+};
+
+/* ----------------------------------------------------------------- */
+
+/*
+ * We're now done with our subsystem definitions.
+ * For convenience in this module, here's a list of them all.  It
+ * allows the init function to easily register them.  Most modules
+ * will only have one subsystem, and will only call register_subsystem
+ * on it directly.
+ */
+static struct configfs_subsystem *example_subsys[] = {
+	&childless_subsys.subsys,
+	&simple_children_subsys,
+	&group_children_subsys,
+	NULL,
+};
+
+static int __init configfs_example_init(void)
+{
+	int ret;
+	int i;
+	struct configfs_subsystem *subsys;
+
+	for (i = 0; example_subsys[i]; i++) {
+		subsys = example_subsys[i];
+
+		config_group_init(&subsys->su_group);
+		init_MUTEX(&subsys->su_sem);
+		ret = configfs_register_subsystem(subsys);
+		if (ret) {
+			printk(KERN_ERR "Error %d while registering subsystem %s\n",
+			       ret,
+			       subsys->su_group.cg_item.ci_namebuf);
+			goto out_unregister;
+		}
+	}
+
+	return 0;
+
+out_unregister:
+	for (; i >= 0; i--) {
+		configfs_unregister_subsystem(example_subsys[i]);
+	}
+
+	return ret;
+}
+
+static void __exit configfs_example_exit(void)
+{
+	int i;
+
+	for (i = 0; example_subsys[i]; i++) {
+		configfs_unregister_subsystem(example_subsys[i]);
+	}
+}
+
+module_init(configfs_example_init);
+module_exit(configfs_example_exit);
+MODULE_LICENSE("GPL");

Documentation/filesystems/dlmfs.txt

+dlmfs
+==================
+A minimal DLM userspace interface implemented via a virtual file
+system.
+
+dlmfs is built with OCFS2 as it requires most of its infrastructure.
+
+Project web page:    http://oss.oracle.com/projects/ocfs2
+Tools web page:      http://oss.oracle.com/projects/ocfs2-tools
+OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/
+
+All code copyright 2005 Oracle except when otherwise noted.
+
+CREDITS
+=======
+
+Some code taken from ramfs which is Copyright (C) 2000 Linus Torvalds
+and Transmeta Corp.
+
+Mark Fasheh <mark.fasheh@oracle.com>
+
+Caveats
+=======
+- Right now it only works with the OCFS2 DLM, though support for other
+  DLM implementations should not be a major issue.
+
+Mount options
+=============
+None
+
+Usage
+=====
+
+If you're just interested in OCFS2, then please see ocfs2.txt. The
+rest of this document will be geared towards those who want to use
+dlmfs for easy to setup and easy to use clustered locking in
+userspace.
+
+Setup
+=====
+
+dlmfs requires that the OCFS2 cluster infrastructure be in
+place. Please download ocfs2-tools from the above url and configure a
+cluster.
+
+You'll want to start heartbeating on a volume which all the nodes in
+your lockspace can access. The easiest way to do this is via
+ocfs2_hb_ctl (distributed with ocfs2-tools). Right now it requires
+that an OCFS2 file system be in place so that it can automatically
+find it's heartbeat area, though it will eventually support heartbeat
+against raw disks.
+
+Please see the ocfs2_hb_ctl and mkfs.ocfs2 manual pages distributed
+with ocfs2-tools.
+
+Once you're heartbeating, DLM lock 'domains' can be easily created /
+destroyed and locks within them accessed.
+
+Locking
+=======
+
+Users may access dlmfs via standard file system calls, or they can use
+'libo2dlm' (distributed with ocfs2-tools) which abstracts the file
+system calls and presents a more traditional locking api.
+
+dlmfs handles lock caching automatically for the user, so a lock
+request for an already acquired lock will not generate another DLM
+call. Userspace programs are assumed to handle their own local
+locking.
+
+Two levels of locks are supported - Shared Read, and Exlcusive.
+Also supported is a Trylock operation.
+
+For information on the libo2dlm interface, please see o2dlm.h,
+distributed with ocfs2-tools.
+
+Lock value blocks can be read and written to a resource via read(2)
+and write(2) against the fd obtained via your open(2) call. The
+maximum currently supported LVB length is 64 bytes (though that is an
+OCFS2 DLM limitation). Through this mechanism, users of dlmfs can share
+small amounts of data amongst their nodes.
+
+mkdir(2) signals dlmfs to join a domain (which will have the same name
+as the resulting directory)
+
+rmdir(2) signals dlmfs to leave the domain
+
+Locks for a given domain are represented by regular inodes inside the
+domain directory.  Locking against them is done via the open(2) system
+call.
+
+The open(2) call will not return until your lock has been granted or
+an error has occurred, unless it has been instructed to do a trylock
+operation. If the lock succeeds, you'll get an fd.
+
+open(2) with O_CREAT to ensure the resource inode is created - dlmfs does
+not automatically create inodes for existing lock resources.
+
+Open Flag     Lock Request Type
+---------     -----------------
+O_RDONLY      Shared Read
+O_RDWR        Exclusive
+
+Open Flag     Resulting Locking Behavior
+---------     --------------------------
+O_NONBLOCK    Trylock operation
+
+You must provide exactly one of O_RDONLY or O_RDWR.
+
+If O_NONBLOCK is also provided and the trylock operation was valid but
+could not lock the resource then open(2) will return ETXTBUSY.
+
+close(2) drops the lock associated with your fd.
+
+Modes passed to mkdir(2) or open(2) are adhered to locally. Chown is
+supported locally as well. This means you can use them to restrict
+access to the resources via dlmfs on your local node only.
+
+The resource LVB may be read from the fd in either Shared Read or
+Exclusive modes via the read(2) system call. It can be written via
+write(2) only when open in Exclusive mode.
+
+Once written, an LVB will be visible to other nodes who obtain Read
+Only or higher level locks on the resource.
+
+See Also
+========
+http://opendlm.sourceforge.net/cvsmirror/opendlm/docs/dlmbook_final.pdf
+
+For more information on the VMS distributed locking API.

Documentation/filesystems/ocfs2.txt

+OCFS2 filesystem
+==================
+OCFS2 is a general purpose extent based shared disk cluster file
+system with many similarities to ext3. It supports 64 bit inode
+numbers, and has automatically extending metadata groups which may
+also make it attractive for non-clustered use.
+
+You'll want to install the ocfs2-tools package in order to at least
+get "mount.ocfs2" and "ocfs2_hb_ctl".
+
+Project web page:    http://oss.oracle.com/projects/ocfs2
+Tools web page:      http://oss.oracle.com/projects/ocfs2-tools
+OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/
+
+All code copyright 2005 Oracle except when otherwise noted.
+
+CREDITS:
+Lots of code taken from ext3 and other projects.
+
+Authors in alphabetical order:
+Joel Becker   <joel.becker@oracle.com>
+Zach Brown    <zach.brown@oracle.com>
+Mark Fasheh   <mark.fasheh@oracle.com>
+Kurt Hackel   <kurt.hackel@oracle.com>
+Sunil Mushran <sunil.mushran@oracle.com>
+Manish Singh  <manish.singh@oracle.com>
+
+Caveats
+=======
+Features which OCFS2 does not support yet:
+	- sparse files
+	- extended attributes
+	- shared writeable mmap
+	- loopback is supported, but data written will not
+	  be cluster coherent.
+	- quotas
+	- cluster aware flock
+	- Directory change notification (F_NOTIFY)
+	- Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease)
+	- POSIX ACLs
+	- readpages / writepages (not user visible)
+
+Mount options
+=============
+
+OCFS2 supports the following mount options:
+(*) == default
+
+barrier=1		This enables/disables barriers. barrier=0 disables it,
+			barrier=1 enables it.
+errors=remount-ro(*)	Remount the filesystem read-only on an error.
+errors=panic		Panic and halt the machine if an error occurs.
+intr		(*)	Allow signals to interrupt cluster operations.
+nointr			Do not allow signals to interrupt cluster
+			operations.

MAINTAINERS

@@ -554,6 +554,11 @@ W:	http://us1.samba.org/samba/Linux_CIFS_client.html
 T:	git kernel.org:/pub/scm/linux/kernel/git/sfrench/cifs-2.6.git
 S:	Supported	
 
+CONFIGFS
+P:	Joel Becker
+M:	Joel Becker <joel.becker@oracle.com>
+S:	Supported
+
 CIRRUS LOGIC GENERIC FBDEV DRIVER
 P:	Jeff Garzik
 M:	jgarzik@pobox.com
@@ -1898,6 +1903,15 @@ M:	ajoshi@shell.unixbox.com
 L:	linux-nvidia@lists.surfsouth.com
 S:	Maintained
 
+ORACLE CLUSTER FILESYSTEM 2 (OCFS2)
+P:	Mark Fasheh
+M:	mark.fasheh@oracle.com
+P:	Kurt Hackel
+M:	kurt.hackel@oracle.com
+L:	ocfs2-devel@oss.oracle.com
+W:	http://oss.oracle.com/projects/ocfs2/
+S:	Supported	
+
 OLYMPIC NETWORK DRIVER
 P:	Peter De Shrijver
 M:	p2@ace.ulyssis.student.kuleuven.ac.be

drivers/block/loop.c

@@ -213,7 +213,7 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
 	struct address_space_operations *aops = mapping->a_ops;
 	pgoff_t index;
 	unsigned offset, bv_offs;
-	int len, ret = 0;
+	int len, ret;
 
 	down(&mapping->host->i_sem);
 	index = pos >> PAGE_CACHE_SHIFT;
@@ -232,9 +232,15 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
 		page = grab_cache_page(mapping, index);
 		if (unlikely(!page))
 			goto fail;
-		if (unlikely(aops->prepare_write(file, page, offset,
-				offset + size)))
+		ret = aops->prepare_write(file, page, offset,
+					  offset + size);
+		if (unlikely(ret)) {
+			if (ret == AOP_TRUNCATED_PAGE) {
+				page_cache_release(page);
+				continue;
+			}
 			goto unlock;
+		}
 		transfer_result = lo_do_transfer(lo, WRITE, page, offset,
 				bvec->bv_page, bv_offs, size, IV);
 		if (unlikely(transfer_result)) {
@@ -251,9 +257,15 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
 			kunmap_atomic(kaddr, KM_USER0);
 		}
 		flush_dcache_page(page);
-		if (unlikely(aops->commit_write(file, page, offset,
-				offset + size)))
+		ret = aops->commit_write(file, page, offset,
+					 offset + size);
+		if (unlikely(ret)) {
+			if (ret == AOP_TRUNCATED_PAGE) {
+				page_cache_release(page);
+				continue;
+			}
 			goto unlock;
+		}
 		if (unlikely(transfer_result))
 			goto unlock;
 		bv_offs += size;
@@ -264,6 +276,7 @@ static int do_lo_send_aops(struct loop_device *lo, struct bio_vec *bvec,
 		unlock_page(page);
 		page_cache_release(page);
 	}
+	ret = 0;
 out:
 	up(&mapping->host->i_sem);
 	return ret;

drivers/block/rd.c

@@ -154,7 +154,7 @@ static int ramdisk_commit_write(struct file *file, struct page *page,
 
 /*
  * ->writepage to the the blockdev's mapping has to redirty the page so that the
- * VM doesn't go and steal it.  We return WRITEPAGE_ACTIVATE so that the VM
+ * VM doesn't go and steal it.  We return AOP_WRITEPAGE_ACTIVATE so that the VM
  * won't try to (pointlessly) write the page again for a while.
  *
  * Really, these pages should not be on the LRU at all.
@@ -165,7 +165,7 @@ static int ramdisk_writepage(struct page *page, struct writeback_control *wbc)
 		make_page_uptodate(page);
 	SetPageDirty(page);
 	if (wbc->for_reclaim)
-		return WRITEPAGE_ACTIVATE;
+		return AOP_WRITEPAGE_ACTIVATE;
 	unlock_page(page);
 	return 0;
 }

fs/Kconfig

@@ -70,6 +70,7 @@ config FS_XIP
 
 config EXT3_FS
 	tristate "Ext3 journalling file system support"
+	select JBD
 	help
 	  This is the journaling version of the Second extended file system
 	  (often called ext3), the de facto standard Linux file system
@@ -138,23 +139,20 @@ config EXT3_FS_SECURITY
 	  extended attributes for file security labels, say N.
 
 config JBD
-# CONFIG_JBD could be its own option (even modular), but until there are
-# other users than ext3, we will simply make it be the same as CONFIG_EXT3_FS
-# dep_tristate '  Journal Block Device support (JBD for ext3)' CONFIG_JBD $CONFIG_EXT3_FS
 	tristate
-	default EXT3_FS
 	help
 	  This is a generic journaling layer for block devices.  It is
-	  currently used by the ext3 file system, but it could also be used to
-	  add journal support to other file systems or block devices such as
-	  RAID or LVM.
+	  currently used by the ext3 and OCFS2 file systems, but it could
+	  also be used to add journal support to other file systems or block
+	  devices such as RAID or LVM.
 
-	  If you are using the ext3 file system, you need to say Y here. If
-	  you are not using ext3 then you will probably want to say N.
+	  If you are using the ext3 or OCFS2 file systems, you need to
+	  say Y here. If you are not using ext3 OCFS2 then you will probably
+	  want to say N.
 
 	  To compile this device as a module, choose M here: the module will be
-	  called jbd.  If you are compiling ext3 into the kernel, you cannot
-	  compile this code as a module.
+	  called jbd.  If you are compiling ext3 or OCFS2 into the kernel,
+	  you cannot compile this code as a module.
 
 config JBD_DEBUG
 	bool "JBD (ext3) debugging support"
@@ -326,6 +324,38 @@ config FS_POSIX_ACL
 
 source "fs/xfs/Kconfig"
 
+config OCFS2_FS
+	tristate "OCFS2 file system support (EXPERIMENTAL)"
+	depends on NET && EXPERIMENTAL
+	select CONFIGFS_FS
+	select JBD
+	select CRC32
+	select INET
+	help
+	  OCFS2 is a general purpose extent based shared disk cluster file
+	  system with many similarities to ext3. It supports 64 bit inode
+	  numbers, and has automatically extending metadata groups which may
+	  also make it attractive for non-clustered use.
+
+	  You'll want to install the ocfs2-tools package in order to at least
+	  get "mount.ocfs2".
+
+	  Project web page:    http://oss.oracle.com/projects/ocfs2
+	  Tools web page:      http://oss.oracle.com/projects/ocfs2-tools
+	  OCFS2 mailing lists: http://oss.oracle.com/projects/ocfs2/mailman/
+
+	  Note: Features which OCFS2 does not support yet:
+	          - extended attributes
+		  - shared writeable mmap
+	          - loopback is supported, but data written will not
+	            be cluster coherent.
+	          - quotas
+	          - cluster aware flock
+	          - Directory change notification (F_NOTIFY)
+	          - Distributed Caching (F_SETLEASE/F_GETLEASE/break_lease)
+	          - POSIX ACLs
+	          - readpages / writepages (not user visible)
+
 config MINIX_FS
 	tristate "Minix fs support"
 	help
@@ -841,6 +871,20 @@ config RELAYFS_FS
 
 	  If unsure, say N.
 
+config CONFIGFS_FS
+	tristate "Userspace-driven configuration filesystem (EXPERIMENTAL)"
+	depends on EXPERIMENTAL
+	help
+	  configfs is a ram-based filesystem that provides the converse
+	  of sysfs's functionality. Where sysfs is a filesystem-based
+	  view of kernel objects, configfs is a filesystem-based manager
+	  of kernel objects, or config_items.
+
+	  Both sysfs and configfs can and should exist together on the
+	  same system. One is not a replacement for the other.
+
+	  If unsure, say N.
+
 endmenu
 
 menu "Miscellaneous filesystems"

fs/Makefile

@@ -101,3 +101,5 @@ obj-$(CONFIG_BEFS_FS)		+= befs/
 obj-$(CONFIG_HOSTFS)		+= hostfs/
 obj-$(CONFIG_HPPFS)		+= hppfs/
 obj-$(CONFIG_DEBUG_FS)		+= debugfs/
+obj-$(CONFIG_CONFIGFS_FS)	+= configfs/
+obj-$(CONFIG_OCFS2_FS)		+= ocfs2/

fs/configfs/Makefile

+#
+# Makefile for the configfs virtual filesystem
+#
+
+obj-$(CONFIG_CONFIGFS_FS)	+= configfs.o
+
+configfs-objs	:= inode.o file.o dir.o symlink.o mount.o item.o

fs/configfs/configfs_internal.h

+/* -*- mode: c; c-basic-offset:8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * configfs_internal.h - Internal stuff for configfs
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/slab.h>
+#include <linux/list.h>
+
+struct configfs_dirent {
+	atomic_t		s_count;
+	struct list_head	s_sibling;
+	struct list_head	s_children;
+	struct list_head	s_links;
+	void 			* s_element;
+	int			s_type;
+	umode_t			s_mode;
+	struct dentry		* s_dentry;
+};
+
+#define CONFIGFS_ROOT		0x0001
+#define CONFIGFS_DIR		0x0002
+#define CONFIGFS_ITEM_ATTR 	0x0004
+#define CONFIGFS_ITEM_LINK 	0x0020
+#define CONFIGFS_USET_DIR	0x0040
+#define CONFIGFS_USET_DEFAULT	0x0080
+#define CONFIGFS_USET_DROPPING	0x0100
+#define CONFIGFS_NOT_PINNED	(CONFIGFS_ITEM_ATTR)
+
+extern struct vfsmount * configfs_mount;
+
+extern int configfs_is_root(struct config_item *item);
+
+extern struct inode * configfs_new_inode(mode_t mode);
+extern int configfs_create(struct dentry *, int mode, int (*init)(struct inode *));
+
+extern int configfs_create_file(struct config_item *, const struct configfs_attribute *);
+extern int configfs_make_dirent(struct configfs_dirent *,
+				struct dentry *, void *, umode_t, int);
+
+extern int configfs_add_file(struct dentry *, const struct configfs_attribute *, int);
+extern void configfs_hash_and_remove(struct dentry * dir, const char * name);
+
+extern const unsigned char * configfs_get_name(struct configfs_dirent *sd);
+extern void configfs_drop_dentry(struct configfs_dirent *sd, struct dentry *parent);
+
+extern int configfs_pin_fs(void);
+extern void configfs_release_fs(void);
+
+extern struct rw_semaphore configfs_rename_sem;
+extern struct super_block * configfs_sb;
+extern struct file_operations configfs_dir_operations;
+extern struct file_operations configfs_file_operations;
+extern struct file_operations bin_fops;
+extern struct inode_operations configfs_dir_inode_operations;
+extern struct inode_operations configfs_symlink_inode_operations;
+
+extern int configfs_symlink(struct inode *dir, struct dentry *dentry,
+			    const char *symname);
+extern int configfs_unlink(struct inode *dir, struct dentry *dentry);
+
+struct configfs_symlink {
+	struct list_head sl_list;
+	struct config_item *sl_target;
+};
+
+extern int configfs_create_link(struct configfs_symlink *sl,
+				struct dentry *parent,
+				struct dentry *dentry);
+
+static inline struct config_item * to_item(struct dentry * dentry)
+{
+	struct configfs_dirent * sd = dentry->d_fsdata;
+	return ((struct config_item *) sd->s_element);
+}
+
+static inline struct configfs_attribute * to_attr(struct dentry * dentry)
+{
+	struct configfs_dirent * sd = dentry->d_fsdata;
+	return ((struct configfs_attribute *) sd->s_element);
+}
+
+static inline struct config_item *configfs_get_config_item(struct dentry *dentry)
+{
+	struct config_item * item = NULL;
+
+	spin_lock(&dcache_lock);
+	if (!d_unhashed(dentry)) {
+		struct configfs_dirent * sd = dentry->d_fsdata;
+		if (sd->s_type & CONFIGFS_ITEM_LINK) {
+			struct configfs_symlink * sl = sd->s_element;
+			item = config_item_get(sl->sl_target);
+		} else
+			item = config_item_get(sd->s_element);
+	}
+	spin_unlock(&dcache_lock);
+
+	return item;
+}
+
+static inline void release_configfs_dirent(struct configfs_dirent * sd)
+{
+	if (!(sd->s_type & CONFIGFS_ROOT))
+		kfree(sd);
+}
+
+static inline struct configfs_dirent * configfs_get(struct configfs_dirent * sd)
+{
+	if (sd) {
+		WARN_ON(!atomic_read(&sd->s_count));
+		atomic_inc(&sd->s_count);
+	}
+	return sd;
+}
+
+static inline void configfs_put(struct configfs_dirent * sd)
+{
+	WARN_ON(!atomic_read(&sd->s_count));
+	if (atomic_dec_and_test(&sd->s_count))
+		release_configfs_dirent(sd);
+}
+

fs/configfs/file.c

+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * file.c - operations for regular (text) files.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/dnotify.h>
+#include <linux/slab.h>
+#include <asm/uaccess.h>
+#include <asm/semaphore.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+
+struct configfs_buffer {
+	size_t			count;
+	loff_t			pos;
+	char			* page;
+	struct configfs_item_operations	* ops;
+	struct semaphore	sem;
+	int			needs_read_fill;
+};
+
+
+/**
+ *	fill_read_buffer - allocate and fill buffer from item.
+ *	@dentry:	dentry pointer.
+ *	@buffer:	data buffer for file.
+ *
+ *	Allocate @buffer->page, if it hasn't been already, then call the
+ *	config_item's show() method to fill the buffer with this attribute's
+ *	data.
+ *	This is called only once, on the file's first read.
+ */
+static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
+{
+	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;
+
+	if (!buffer->page)
+		buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	count = ops->show_attribute(item,attr,buffer->page);
+	buffer->needs_read_fill = 0;
+	BUG_ON(count > (ssize_t)PAGE_SIZE);
+	if (count >= 0)
+		buffer->count = count;
+	else
+		ret = count;
+	return ret;
+}
+
+
+/**
+ *	flush_read_buffer - push buffer to userspace.
+ *	@buffer:	data buffer for file.
+ *	@userbuf:	user-passed buffer.
+ *	@count:		number of bytes requested.
+ *	@ppos:		file position.
+ *
+ *	Copy the buffer we filled in fill_read_buffer() to userspace.
+ *	This is done at the reader's leisure, copying and advancing
+ *	the amount they specify each time.
+ *	This may be called continuously until the buffer is empty.
+ */
+static int flush_read_buffer(struct configfs_buffer * buffer, char __user * buf,
+			     size_t count, loff_t * ppos)
+{
+	int error;
+
+	if (*ppos > buffer->count)
+		return 0;
+
+	if (count > (buffer->count - *ppos))
+		count = buffer->count - *ppos;
+
+	error = copy_to_user(buf,buffer->page + *ppos,count);
+	if (!error)
+		*ppos += count;
+	return error ? -EFAULT : count;
+}
+
+/**
+ *	configfs_read_file - read an attribute.
+ *	@file:	file pointer.
+ *	@buf:	buffer to fill.
+ *	@count:	number of bytes to read.
+ *	@ppos:	starting offset in file.
+ *
+ *	Userspace wants to read an attribute file. The attribute descriptor
+ *	is in the file's ->d_fsdata. The target item is in the directory's
+ *	->d_fsdata.
+ *
+ *	We call fill_read_buffer() to allocate and fill the buffer from the
+ *	item's show() method exactly once (if the read is happening from
+ *	the beginning of the file). That should fill the entire buffer with
+ *	all the data the item has to offer for that attribute.
+ *	We then call flush_read_buffer() to copy the buffer to userspace
+ *	in the increments specified.
+ */
+
+static ssize_t
+configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct configfs_buffer * buffer = file->private_data;
+	ssize_t retval = 0;
+
+	down(&buffer->sem);
+	if (buffer->needs_read_fill) {
+		if ((retval = fill_read_buffer(file->f_dentry,buffer)))
+			goto out;
+	}
+	pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
+		 __FUNCTION__,count,*ppos,buffer->page);
+	retval = flush_read_buffer(buffer,buf,count,ppos);
+out:
+	up(&buffer->sem);
+	return retval;
+}
+
+
+/**
+ *	fill_write_buffer - copy buffer from userspace.
+ *	@buffer:	data buffer for file.
+ *	@userbuf:	data from user.
+ *	@count:		number of bytes in @userbuf.
+ *
+ *	Allocate @buffer->page if it hasn't been already, then
+ *	copy the user-supplied buffer into it.
+ */
+
+static int
+fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
+{
+	int error;
+
+	if (!buffer->page)
+		buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
+	if (!buffer->page)
+		return -ENOMEM;
+
+	if (count > PAGE_SIZE)
+		count = PAGE_SIZE;
+	error = copy_from_user(buffer->page,buf,count);
+	buffer->needs_read_fill = 1;
+	return error ? -EFAULT : count;
+}
+
+
+/**
+ *	flush_write_buffer - push buffer to config_item.
+ *	@file:		file pointer.
+ *	@buffer:	data buffer for file.
+ *
+ *	Get the correct pointers for the config_item and the attribute we're
+ *	dealing with, then call the store() method for the attribute,
+ *	passing the buffer that we acquired in fill_write_buffer().
+ */
+
+static int
+flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
+{
+	struct configfs_attribute * attr = to_attr(dentry);
+	struct config_item * item = to_item(dentry->d_parent);
+	struct configfs_item_operations * ops = buffer->ops;
+
+	return ops->store_attribute(item,attr,buffer->page,count);
+}
+
+
+/**
+ *	configfs_write_file - write an attribute.
+ *	@file:	file pointer
+ *	@buf:	data to write
+ *	@count:	number of bytes
+ *	@ppos:	starting offset
+ *
+ *	Similar to configfs_read_file(), though working in the opposite direction.
+ *	We allocate and fill the data from the user in fill_write_buffer(),
+ *	then push it to the config_item in flush_write_buffer().
+ *	There is no easy way for us to know if userspace is only doing a partial
+ *	write, so we don't support them. We expect the entire buffer to come
+ *	on the first write.
+ *	Hint: if you're writing a value, first read the file, modify only the
+ *	the value you're changing, then write entire buffer back.
+ */
+
+static ssize_t
+configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct configfs_buffer * buffer = file->private_data;
+
+	down(&buffer->sem);
+	count = fill_write_buffer(buffer,buf,count);
+	if (count > 0)
+		count = flush_write_buffer(file->f_dentry,buffer,count);
+	if (count > 0)
+		*ppos += count;
+	up(&buffer->sem);
+	return count;
+}
+
+static int check_perm(struct inode * inode, struct file * file)
+{
+	struct config_item *item = configfs_get_config_item(file->f_dentry->d_parent);
+	struct configfs_attribute * attr = to_attr(file->f_dentry);
+	struct configfs_buffer * buffer;
+	struct configfs_item_operations * ops = NULL;
+	int error = 0;
+
+	if (!item || !attr)
+		goto Einval;
+
+	/* Grab the module reference for this attribute if we have one */
+	if (!try_module_get(attr->ca_owner)) {
+		error = -ENODEV;
+		goto Done;
+	}
+
+	if (item->ci_type)
+		ops = item->ci_type->ct_item_ops;
+	else
+		goto Eaccess;
+
+	/* File needs write support.
+	 * The inode's perms must say it's ok,
+	 * and we must have a store method.
+	 */
+	if (file->f_mode & FMODE_WRITE) {
+
+		if (!(inode->i_mode & S_IWUGO) || !ops->store_attribute)
+			goto Eaccess;
+
+	}
+
+	/* File needs read support.
+	 * The inode's perms must say it's ok, and we there
+	 * must be a show method for it.
+	 */
+	if (file->f_mode & FMODE_READ) {
+		if (!(inode->i_mode & S_IRUGO) || !ops->show_attribute)
+			goto Eaccess;
+	}
+
+	/* No error? Great, allocate a buffer for the file, and store it
+	 * it in file->private_data for easy access.
+	 */
+	buffer = kmalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
+	if (buffer) {
+		memset(buffer,0,sizeof(struct configfs_buffer));
+		init_MUTEX(&buffer->sem);
+		buffer->needs_read_fill = 1;
+		buffer->ops = ops;
+		file->private_data = buffer;
+	} else
+		error = -ENOMEM;
+	goto Done;
+
+ Einval:
+	error = -EINVAL;
+	goto Done;
+ Eaccess:
+	error = -EACCES;
+	module_put(attr->ca_owner);
+ Done:
+	if (error && item)
+		config_item_put(item);
+	return error;
+}
+
+static int configfs_open_file(struct inode * inode, struct file * filp)
+{
+	return check_perm(inode,filp);
+}
+
+static int configfs_release(struct inode * inode, struct file * filp)
+{
+	struct config_item * item = to_item(filp->f_dentry->d_parent);
+	struct configfs_attribute * attr = to_attr(filp->f_dentry);
+	struct module * owner = attr->ca_owner;
+	struct configfs_buffer * buffer = filp->private_data;
+
+	if (item)
+		config_item_put(item);
+	/* After this point, attr should not be accessed. */
+	module_put(owner);
+
+	if (buffer) {
+		if (buffer->page)
+			free_page((unsigned long)buffer->page);
+		kfree(buffer);
+	}
+	return 0;
+}
+
+struct file_operations configfs_file_operations = {
+	.read		= configfs_read_file,
+	.write		= configfs_write_file,
+	.llseek		= generic_file_llseek,
+	.open		= configfs_open_file,
+	.release	= configfs_release,
+};
+
+
+int configfs_add_file(struct dentry * dir, const struct configfs_attribute * attr, int type)
+{
+	struct configfs_dirent * parent_sd = dir->d_fsdata;
+	umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
+	int error = 0;
+
+	down(&dir->d_inode->i_sem);
+	error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
+	up(&dir->d_inode->i_sem);
+
+	return error;
+}
+
+
+/**
+ *	configfs_create_file - create an attribute file for an item.
+ *	@item:	item we're creating for.
+ *	@attr:	atrribute descriptor.
+ */
+
+int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
+{
+	BUG_ON(!item || !item->ci_dentry || !attr);
+
+	return configfs_add_file(item->ci_dentry, attr,
+				 CONFIGFS_ITEM_ATTR);
+}
+

fs/configfs/inode.c

+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * inode.c - basic inode and dentry operations.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ *
+ * Please see Documentation/filesystems/configfs.txt for more information.
+ */
+
+#undef DEBUG
+
+#include <linux/pagemap.h>
+#include <linux/namei.h>
+#include <linux/backing-dev.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+extern struct super_block * configfs_sb;
+
+static struct address_space_operations configfs_aops = {
+	.readpage	= simple_readpage,
+	.prepare_write	= simple_prepare_write,
+	.commit_write	= simple_commit_write
+};
+
+static struct backing_dev_info configfs_backing_dev_info = {
+	.ra_pages	= 0,	/* No readahead */
+	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
+};
+
+struct inode * configfs_new_inode(mode_t mode)
+{
+	struct inode * inode = new_inode(configfs_sb);
+	if (inode) {
+		inode->i_mode = mode;
+		inode->i_uid = 0;
+		inode->i_gid = 0;
+		inode->i_blksize = PAGE_CACHE_SIZE;
+		inode->i_blocks = 0;
+		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
+		inode->i_mapping->a_ops = &configfs_aops;
+		inode->i_mapping->backing_dev_info = &configfs_backing_dev_info;
+	}
+	return inode;
+}
+
+int configfs_create(struct dentry * dentry, int mode, int (*init)(struct inode *))
+{
+	int error = 0;
+	struct inode * inode = NULL;
+	if (dentry) {
+		if (!dentry->d_inode) {
+			if ((inode = configfs_new_inode(mode))) {
+				if (dentry->d_parent && dentry->d_parent->d_inode) {
+					struct inode *p_inode = dentry->d_parent->d_inode;
+					p_inode->i_mtime = p_inode->i_ctime = CURRENT_TIME;
+				}
+				goto Proceed;
+			}
+			else
+				error = -ENOMEM;
+		} else
+			error = -EEXIST;
+	} else
+		error = -ENOENT;
+	goto Done;
+
+ Proceed:
+	if (init)
+		error = init(inode);
+	if (!error) {
+		d_instantiate(dentry, inode);
+		if (S_ISDIR(mode) || S_ISLNK(mode))
+			dget(dentry);  /* pin link and directory dentries in core */
+	} else
+		iput(inode);
+ Done:
+	return error;
+}
+
+/*
+ * Get the name for corresponding element represented by the given configfs_dirent
+ */
+const unsigned char * configfs_get_name(struct configfs_dirent *sd)
+{
+	struct attribute * attr;
+
+	if (!sd || !sd->s_element)
+		BUG();
+
+	/* These always have a dentry, so use that */
+	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
+		return sd->s_dentry->d_name.name;
+
+	if (sd->s_type & CONFIGFS_ITEM_ATTR) {
+		attr = sd->s_element;
+		return attr->name;
+	}
+	return NULL;
+}
+
+
+/*
+ * Unhashes the dentry corresponding to given configfs_dirent
+ * Called with parent inode's i_sem held.
+ */
+void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
+{
+	struct dentry * dentry = sd->s_dentry;
+
+	if (dentry) {
+		spin_lock(&dcache_lock);
+		if (!(d_unhashed(dentry) && dentry->d_inode)) {
+			dget_locked(dentry);
+			__d_drop(dentry);
+			spin_unlock(&dcache_lock);
+			simple_unlink(parent->d_inode, dentry);
+		} else
+			spin_unlock(&dcache_lock);
+	}
+}
+
+void configfs_hash_and_remove(struct dentry * dir, const char * name)
+{
+	struct configfs_dirent * sd;
+	struct configfs_dirent * parent_sd = dir->d_fsdata;
+
+	down(&dir->d_inode->i_sem);
+	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+		if (!sd->s_element)
+			continue;
+		if (!strcmp(configfs_get_name(sd), name)) {
+			list_del_init(&sd->s_sibling);
+			configfs_drop_dentry(sd, dir);
+			configfs_put(sd);
+			break;
+		}
+	}
+	up(&dir->d_inode->i_sem);
+}
+
+

fs/configfs/item.c

+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * item.c - library routines for handling generic config items
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on kobject:
+ * 	kobject is Copyright (c) 2002-2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ *
+ * Please see the file Documentation/filesystems/configfs.txt for
+ * critical information about using the config_item interface.
+ */
+
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/stat.h>
+#include <linux/slab.h>
+
+#include <linux/configfs.h>
+
+
+static inline struct config_item * to_item(struct list_head * entry)
+{
+	return container_of(entry,struct config_item,ci_entry);
+}
+
+/* Evil kernel */
+static void config_item_release(struct kref *kref);
+
+/**
+ *	config_item_init - initialize item.
+ *	@item:	item in question.
+ */
+void config_item_init(struct config_item * item)
+{
+	kref_init(&item->ci_kref);
+	INIT_LIST_HEAD(&item->ci_entry);
+}
+
+/**
+ *	config_item_set_name - Set the name of an item
+ *	@item:	item.
+ *	@name:	name.
+ *
+ *	If strlen(name) >= CONFIGFS_ITEM_NAME_LEN, then use a
+ *	dynamically allocated string that @item->ci_name points to.
+ *	Otherwise, use the static @item->ci_namebuf array.
+ */
+
+int config_item_set_name(struct config_item * item, const char * fmt, ...)
+{
+	int error = 0;
+	int limit = CONFIGFS_ITEM_NAME_LEN;
+	int need;
+	va_list args;
+	char * name;
+
+	/*
+	 * First, try the static array
+	 */
+	va_start(args,fmt);
+	need = vsnprintf(item->ci_namebuf,limit,fmt,args);
+	va_end(args);
+	if (need < limit)
+		name = item->ci_namebuf;
+	else {
+		/*
+		 * Need more space? Allocate it and try again
+		 */
+		limit = need + 1;
+		name = kmalloc(limit,GFP_KERNEL);
+		if (!name) {
+			error = -ENOMEM;
+			goto Done;
+		}
+		va_start(args,fmt);
+		need = vsnprintf(name,limit,fmt,args);
+		va_end(args);
+
+		/* Still? Give up. */
+		if (need >= limit) {
+			kfree(name);
+			error = -EFAULT;
+			goto Done;
+		}
+	}
+
+	/* Free the old name, if necessary. */
+	if (item->ci_name && item->ci_name != item->ci_namebuf)
+		kfree(item->ci_name);
+
+	/* Now, set the new name */
+	item->ci_name = name;
+ Done:
+	return error;
+}
+
+EXPORT_SYMBOL(config_item_set_name);
+
+void config_item_init_type_name(struct config_item *item,
+				const char *name,
+				struct config_item_type *type)
+{
+	config_item_set_name(item, name);
+	item->ci_type = type;
+	config_item_init(item);
+}
+EXPORT_SYMBOL(config_item_init_type_name);
+
+void config_group_init_type_name(struct config_group *group, const char *name,
+			 struct config_item_type *type)
+{
+	config_item_set_name(&group->cg_item, name);
+	group->cg_item.ci_type = type;
+	config_group_init(group);
+}
+EXPORT_SYMBOL(config_group_init_type_name);
+
+struct config_item * config_item_get(struct config_item * item)
+{
+	if (item)
+		kref_get(&item->ci_kref);
+	return item;
+}
+
+/**
+ *	config_item_cleanup - free config_item resources.
+ *	@item:	item.
+ */
+
+void config_item_cleanup(struct config_item * item)
+{
+	struct config_item_type * t = item->ci_type;
+	struct config_group * s = item->ci_group;
+	struct config_item * parent = item->ci_parent;
+
+	pr_debug("config_item %s: cleaning up\n",config_item_name(item));
+	if (item->ci_name != item->ci_namebuf)
+		kfree(item->ci_name);
+	item->ci_name = NULL;
+	if (t && t->ct_item_ops && t->ct_item_ops->release)
+		t->ct_item_ops->release(item);
+	if (s)
+		config_group_put(s);
+	if (parent)
+		config_item_put(parent);
+}
+
+static void config_item_release(struct kref *kref)
+{
+	config_item_cleanup(container_of(kref, struct config_item, ci_kref));
+}
+
+/**
+ *	config_item_put - decrement refcount for item.
+ *	@item:	item.
+ *
+ *	Decrement the refcount, and if 0, call config_item_cleanup().
+ */
+void config_item_put(struct config_item * item)
+{
+	if (item)
+		kref_put(&item->ci_kref, config_item_release);
+}
+
+
+/**
+ *	config_group_init - initialize a group for use
+ *	@k:	group
+ */
+
+void config_group_init(struct config_group *group)
+{
+	config_item_init(&group->cg_item);
+	INIT_LIST_HEAD(&group->cg_children);
+}
+
+
+/**
+ *	config_group_find_obj - search for item in group.
+ *	@group:	group we're looking in.
+ *	@name:	item's name.
+ *
+ *	Lock group via @group->cg_subsys, and iterate over @group->cg_list,
+ *	looking for a matching config_item. If matching item is found
+ *	take a reference and return the item.
+ */
+
+struct config_item * config_group_find_obj(struct config_group * group, const char * name)
+{
+	struct list_head * entry;
+	struct config_item * ret = NULL;
+
+        /* XXX LOCKING! */
+	list_for_each(entry,&group->cg_children) {
+		struct config_item * item = to_item(entry);
+		if (config_item_name(item) &&
+                    !strcmp(config_item_name(item), name)) {
+			ret = config_item_get(item);
+			break;
+		}
+	}
+	return ret;
+}
+
+
+EXPORT_SYMBOL(config_item_init);
+EXPORT_SYMBOL(config_group_init);
+EXPORT_SYMBOL(config_item_get);
+EXPORT_SYMBOL(config_item_put);
+

fs/configfs/mount.c

+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * mount.c - operations for initializing and mounting configfs.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/mount.h>
+#include <linux/pagemap.h>
+#include <linux/init.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+/* Random magic number */
+#define CONFIGFS_MAGIC 0x62656570
+
+struct vfsmount * configfs_mount = NULL;
+struct super_block * configfs_sb = NULL;
+static int configfs_mnt_count = 0;
+
+static struct super_operations configfs_ops = {
+	.statfs		= simple_statfs,
+	.drop_inode	= generic_delete_inode,
+};
+
+static struct config_group configfs_root_group = {
+	.cg_item = {
+		.ci_namebuf	= "root",
+		.ci_name	= configfs_root_group.cg_item.ci_namebuf,
+	},
+};
+
+int configfs_is_root(struct config_item *item)
+{
+	return item == &configfs_root_group.cg_item;
+}
+
+static struct configfs_dirent configfs_root = {
+	.s_sibling	= LIST_HEAD_INIT(configfs_root.s_sibling),
+	.s_children	= LIST_HEAD_INIT(configfs_root.s_children),
+	.s_element	= &configfs_root_group.cg_item,
+	.s_type		= CONFIGFS_ROOT,
+};
+
+static int configfs_fill_super(struct super_block *sb, void *data, int silent)
+{
+	struct inode *inode;
+	struct dentry *root;
+
+	sb->s_blocksize = PAGE_CACHE_SIZE;
+	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
+	sb->s_magic = CONFIGFS_MAGIC;
+	sb->s_op = &configfs_ops;
+	configfs_sb = sb;
+
+	inode = configfs_new_inode(S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO);
+	if (inode) {
+		inode->i_op = &configfs_dir_inode_operations;
+		inode->i_fop = &configfs_dir_operations;
+		/* directory inodes start off with i_nlink == 2 (for "." entry) */
+		inode->i_nlink++;
+	} else {
+		pr_debug("configfs: could not get root inode\n");
+		return -ENOMEM;
+	}
+
+	root = d_alloc_root(inode);
+	if (!root) {
+		pr_debug("%s: could not get root dentry!\n",__FUNCTION__);
+		iput(inode);
+		return -ENOMEM;
+	}
+	config_group_init(&configfs_root_group);
+	configfs_root_group.cg_item.ci_dentry = root;
+	root->d_fsdata = &configfs_root;
+	sb->s_root = root;
+	return 0;
+}
+
+static struct super_block *configfs_get_sb(struct file_system_type *fs_type,
+	int flags, const char *dev_name, void *data)
+{
+	return get_sb_single(fs_type, flags, data, configfs_fill_super);
+}
+
+static struct file_system_type configfs_fs_type = {
+	.owner		= THIS_MODULE,
+	.name		= "configfs",
+	.get_sb		= configfs_get_sb,
+	.kill_sb	= kill_litter_super,
+};
+
+int configfs_pin_fs(void)
+{
+	return simple_pin_fs("configfs", &configfs_mount,
+			     &configfs_mnt_count);
+}
+
+void configfs_release_fs(void)
+{
+	simple_release_fs(&configfs_mount, &configfs_mnt_count);
+}
+
+
+static decl_subsys(config, NULL, NULL);
+
+static int __init configfs_init(void)
+{
+	int err;
+
+	kset_set_kset_s(&config_subsys, kernel_subsys);
+	err = subsystem_register(&config_subsys);
+	if (err)
+		return err;
+
+	err = register_filesystem(&configfs_fs_type);
+	if (err) {
+		printk(KERN_ERR "configfs: Unable to register filesystem!\n");
+		subsystem_unregister(&config_subsys);
+	}
+
+	return err;
+}
+
+static void __exit configfs_exit(void)
+{
+	unregister_filesystem(&configfs_fs_type);
+	subsystem_unregister(&config_subsys);
+}
+
+MODULE_AUTHOR("Oracle");
+MODULE_LICENSE("GPL");
+MODULE_VERSION("0.0.1");
+MODULE_DESCRIPTION("Simple RAM filesystem for user driven kernel subsystem configuration.");
+
+module_init(configfs_init);
+module_exit(configfs_exit);

fs/configfs/symlink.c

+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * symlink.c - operations for configfs symlinks.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 021110-1307, USA.
+ *
+ * Based on sysfs:
+ * 	sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
+ *
+ * configfs Copyright (C) 2005 Oracle.  All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/namei.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+static int item_depth(struct config_item * item)
+{
+	struct config_item * p = item;
+	int depth = 0;
+	do { depth++; } while ((p = p->ci_parent) && !configfs_is_root(p));
+	return depth;
+}
+
+static int item_path_length(struct config_item * item)
+{
+	struct config_item * p = item;
+	int length = 1;
+	do {
+		length += strlen(config_item_name(p)) + 1;
+		p = p->ci_parent;
+	} while (p && !configfs_is_root(p));
+	return length;
+}
+
+static void fill_item_path(struct config_item * item, char * buffer, int length)
+{
+	struct config_item * p;
+
+	--length;
+	for (p = item; p && !configfs_is_root(p); p = p->ci_parent) {
+		int cur = strlen(config_item_name(p));
+
+		/* back up enough to print this bus id with '/' */
+		length -= cur;
+		strncpy(buffer + length,config_item_name(p),cur);
+		*(buffer + --length) = '/';
+	}
+}
+
+static int create_link(struct config_item *parent_item,
+ 		       struct config_item *item,
+		       struct dentry *dentry)
+{
+	struct configfs_dirent *target_sd = item->ci_dentry->d_fsdata;
+	struct configfs_symlink *sl;
+	int ret;
+
+	ret = -ENOMEM;
+	sl = kmalloc(sizeof(struct configfs_symlink), GFP_KERNEL);
+	if (sl) {
+		sl->sl_target = config_item_get(item);
+		/* FIXME: needs a lock, I'd bet */
+		list_add(&sl->sl_list, &target_sd->s_links);
+		ret = configfs_create_link(sl, parent_item->ci_dentry,
+					   dentry);
+		if (ret) {
+			list_del_init(&sl->sl_list);
+			config_item_put(item);
+			kfree(sl);
+		}
+	}
+
+	return ret;
+}
+
+
+static int get_target(const char *symname, struct nameidata *nd,
+		      struct config_item **target)
+{
+	int ret;
+
+	ret = path_lookup(symname, LOOKUP_FOLLOW|LOOKUP_DIRECTORY, nd);
+	if (!ret) {
+		if (nd->dentry->d_sb == configfs_sb) {
+			*target = configfs_get_config_item(nd->dentry);
+			if (!*target) {
+				ret = -ENOENT;
+				path_release(nd);
+			}
+		} else
+			ret = -EPERM;
+	}
+
+	return ret;
+}
+
+
+int configfs_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
+{
+	int ret;
+	struct nameidata nd;
+	struct config_item *parent_item;
+	struct config_item *target_item;
+	struct config_item_type *type;
+
+	ret = -EPERM;  /* What lack-of-symlink returns */
+	if (dentry->d_parent == configfs_sb->s_root)
+		goto out;
+
+	parent_item = configfs_get_config_item(dentry->d_parent);
+	type = parent_item->ci_type;
+
+	if (!type || !type->ct_item_ops ||
+	    !type->ct_item_ops->allow_link)
+		goto out_put;
+
+	ret = get_target(symname, &nd, &target_item);
+	if (ret)
+		goto out_put;
+
+	ret = type->ct_item_ops->allow_link(parent_item, target_item);
+	if (!ret)
+		ret = create_link(parent_item, target_item, dentry);
+
+	config_item_put(target_item);
+	path_release(&nd);
+
+out_put:
+	config_item_put(parent_item);
+
+out:
+	return ret;
+}
+
+int configfs_unlink(struct inode *dir, struct dentry *dentry)
+{
+	struct configfs_dirent *sd = dentry->d_fsdata;
+	struct configfs_symlink *sl;
+	struct config_item *parent_item;
+	struct config_item_type *type;
+	int ret;
+
+	ret = -EPERM;  /* What lack-of-symlink returns */
+	if (!(sd->s_type & CONFIGFS_ITEM_LINK))
+		goto out;
+
+	if (dentry->d_parent == configfs_sb->s_root)
+		BUG();
+
+	sl = sd->s_element;
+
+	parent_item = configfs_get_config_item(dentry->d_parent);
+	type = parent_item->ci_type;
+
+	list_del_init(&sd->s_sibling);
+	configfs_drop_dentry(sd, dentry->d_parent);
+	dput(dentry);
+	configfs_put(sd);
+
+	/*
+	 * drop_link() must be called before
+	 * list_del_init(&sl->sl_list), so that the order of
+	 * drop_link(this, target) and drop_item(target) is preserved.
+	 */
+	if (type && type->ct_item_ops &&
+	    type->ct_item_ops->drop_link)
+		type->ct_item_ops->drop_link(parent_item,
+					       sl->sl_target);
+
+	/* FIXME: Needs lock */
+	list_del_init(&sl->sl_list);
+
+	/* Put reference from create_link() */
+	config_item_put(sl->sl_target);
+	kfree(sl);
+
+	config_item_put(parent_item);
+
+	ret = 0;
+
+out:
+	return ret;
+}
+
+static int configfs_get_target_path(struct config_item * item, struct config_item * target,
+				   char *path)
+{
+	char * s;
+	int depth, size;
+
+	depth = item_depth(item);
+	size = item_path_length(target) + depth * 3 - 1;
+	if (size > PATH_MAX)
+		return -ENAMETOOLONG;
+
+	pr_debug("%s: depth = %d, size = %d\n", __FUNCTION__, depth, size);
+
+	for (s = path; depth--; s += 3)
+		strcpy(s,"../");
+
+	fill_item_path(target, path, size);
+	pr_debug("%s: path = '%s'\n", __FUNCTION__, path);
+
+	return 0;
+}
+
+static int configfs_getlink(struct dentry *dentry, char * path)
+{
+	struct config_item *item, *target_item;
+	int error = 0;
+
+	item = configfs_get_config_item(dentry->d_parent);
+	if (!item)
+		return -EINVAL;
+
+	target_item = configfs_get_config_item(dentry);
+	if (!target_item) {
+		config_item_put(item);
+		return -EINVAL;
+	}
+
+	down_read(&configfs_rename_sem);
+	error = configfs_get_target_path(item, target_item, path);
+	up_read(&configfs_rename_sem);
+
+	config_item_put(item);
+	config_item_put(target_item);
+	return error;
+
+}
+
+static void *configfs_follow_link(struct dentry *dentry, struct nameidata *nd)
+{
+	int error = -ENOMEM;
+	unsigned long page = get_zeroed_page(GFP_KERNEL);
+
+	if (page) {
+		error = configfs_getlink(dentry, (char *)page);
+		if (!error) {
+			nd_set_link(nd, (char *)page);
+			return (void *)page;
+		}
+	}
+
+	nd_set_link(nd, ERR_PTR(error));
+	return NULL;
+}
+
+static void configfs_put_link(struct dentry *dentry, struct nameidata *nd,
+			      void *cookie)
+{
+	if (cookie) {
+		unsigned long page = (unsigned long)cookie;
+		free_page(page);
+	}
+}
+
+struct inode_operations configfs_symlink_inode_operations = {
+	.follow_link = configfs_follow_link,
+	.readlink = generic_readlink,
+	.put_link = configfs_put_link,
+};
+

fs/mpage.c

@@ -721,7 +721,7 @@ retry:
 						&last_block_in_bio, &ret, wbc,
 						page->mapping->a_ops->writepage);
 			}
-			if (unlikely(ret == WRITEPAGE_ACTIVATE))
+			if (unlikely(ret == AOP_WRITEPAGE_ACTIVATE))
 				unlock_page(page);
 			if (ret || (--(wbc->nr_to_write) <= 0))
 				done = 1;

fs/ocfs2/Makefile

+EXTRA_CFLAGS += -Ifs/ocfs2
+
+EXTRA_CFLAGS += -DCATCH_BH_JBD_RACES
+
+obj-$(CONFIG_OCFS2_FS) += ocfs2.o
+
+ocfs2-objs := \
+	alloc.o 		\
+	aops.o 			\
+	buffer_head_io.o	\
+	dcache.o 		\
+	dir.o 			\
+	dlmglue.o 		\
+	export.o 		\
+	extent_map.o 		\
+	file.o 			\
+	heartbeat.o 		\
+	inode.o 		\
+	journal.o 		\
+	localalloc.o 		\
+	mmap.o 			\
+	namei.o 		\
+	slot_map.o 		\
+	suballoc.o 		\
+	super.o 		\
+	symlink.o 		\
+	sysfile.o 		\
+	uptodate.o		\
+	ver.o 			\
+	vote.o
+
+obj-$(CONFIG_OCFS2_FS) += cluster/
+obj-$(CONFIG_OCFS2_FS) += dlm/