Configfs, a file system for userspace-driven kernel object configuration.
The OCFS2 stack makes extensive use of this for propagation of cluster
configuration information into kernel.
Signed-off-by: Joel Becker <joel.becker@oracle.com>
- 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/
--- /dev/null
+
+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.
+
+
--- /dev/null
+/*
+ * 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");
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
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"
obj-$(CONFIG_HOSTFS) += hostfs/
obj-$(CONFIG_HPPFS) += hppfs/
obj-$(CONFIG_DEBUG_FS) += debugfs/
+obj-$(CONFIG_CONFIGFS_FS) += configfs/
--- /dev/null
+#
+# 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
--- /dev/null
+/* -*- 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);
+}
+
--- /dev/null
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * dir.c - Operations for configfs directories.
+ *
+ * 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.
+ */
+
+#undef DEBUG
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+
+#include <linux/configfs.h>
+#include "configfs_internal.h"
+
+DECLARE_RWSEM(configfs_rename_sem);
+
+static void configfs_d_iput(struct dentry * dentry,
+ struct inode * inode)
+{
+ struct configfs_dirent * sd = dentry->d_fsdata;
+
+ if (sd) {
+ BUG_ON(sd->s_dentry != dentry);
+ sd->s_dentry = NULL;
+ configfs_put(sd);
+ }
+ iput(inode);
+}
+
+/*
+ * We _must_ delete our dentries on last dput, as the chain-to-parent
+ * behavior is required to clear the parents of default_groups.
+ */
+static int configfs_d_delete(struct dentry *dentry)
+{
+ return 1;
+}
+
+static struct dentry_operations configfs_dentry_ops = {
+ .d_iput = configfs_d_iput,
+ /* simple_delete_dentry() isn't exported */
+ .d_delete = configfs_d_delete,
+};
+
+/*
+ * Allocates a new configfs_dirent and links it to the parent configfs_dirent
+ */
+static struct configfs_dirent *configfs_new_dirent(struct configfs_dirent * parent_sd,
+ void * element)
+{
+ struct configfs_dirent * sd;
+
+ sd = kmalloc(sizeof(*sd), GFP_KERNEL);
+ if (!sd)
+ return NULL;
+
+ memset(sd, 0, sizeof(*sd));
+ atomic_set(&sd->s_count, 1);
+ INIT_LIST_HEAD(&sd->s_links);
+ INIT_LIST_HEAD(&sd->s_children);
+ list_add(&sd->s_sibling, &parent_sd->s_children);
+ sd->s_element = element;
+
+ return sd;
+}
+
+int configfs_make_dirent(struct configfs_dirent * parent_sd,
+ struct dentry * dentry, void * element,
+ umode_t mode, int type)
+{
+ struct configfs_dirent * sd;
+
+ sd = configfs_new_dirent(parent_sd, element);
+ if (!sd)
+ return -ENOMEM;
+
+ sd->s_mode = mode;
+ sd->s_type = type;
+ sd->s_dentry = dentry;
+ if (dentry) {
+ dentry->d_fsdata = configfs_get(sd);
+ dentry->d_op = &configfs_dentry_ops;
+ }
+
+ return 0;
+}
+
+static int init_dir(struct inode * 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++;
+ return 0;
+}
+
+static int init_file(struct inode * inode)
+{
+ inode->i_size = PAGE_SIZE;
+ inode->i_fop = &configfs_file_operations;
+ return 0;
+}
+
+static int init_symlink(struct inode * inode)
+{
+ inode->i_op = &configfs_symlink_inode_operations;
+ return 0;
+}
+
+static int create_dir(struct config_item * k, struct dentry * p,
+ struct dentry * d)
+{
+ int error;
+ umode_t mode = S_IFDIR| S_IRWXU | S_IRUGO | S_IXUGO;
+
+ error = configfs_create(d, mode, init_dir);
+ if (!error) {
+ error = configfs_make_dirent(p->d_fsdata, d, k, mode,
+ CONFIGFS_DIR);
+ if (!error) {
+ p->d_inode->i_nlink++;
+ (d)->d_op = &configfs_dentry_ops;
+ }
+ }
+ return error;
+}
+
+
+/**
+ * configfs_create_dir - create a directory for an config_item.
+ * @item: config_itemwe're creating directory for.
+ * @dentry: config_item's dentry.
+ */
+
+static int configfs_create_dir(struct config_item * item, struct dentry *dentry)
+{
+ struct dentry * parent;
+ int error = 0;
+
+ BUG_ON(!item);
+
+ if (item->ci_parent)
+ parent = item->ci_parent->ci_dentry;
+ else if (configfs_mount && configfs_mount->mnt_sb)
+ parent = configfs_mount->mnt_sb->s_root;
+ else
+ return -EFAULT;
+
+ error = create_dir(item,parent,dentry);
+ if (!error)
+ item->ci_dentry = dentry;
+ return error;
+}
+
+int configfs_create_link(struct configfs_symlink *sl,
+ struct dentry *parent,
+ struct dentry *dentry)
+{
+ int err = 0;
+ umode_t mode = S_IFLNK | S_IRWXUGO;
+
+ err = configfs_create(dentry, mode, init_symlink);
+ if (!err) {
+ err = configfs_make_dirent(parent->d_fsdata, dentry, sl,
+ mode, CONFIGFS_ITEM_LINK);
+ if (!err)
+ dentry->d_op = &configfs_dentry_ops;
+ }
+ return err;
+}
+
+static void remove_dir(struct dentry * d)
+{
+ struct dentry * parent = dget(d->d_parent);
+ struct configfs_dirent * sd;
+
+ sd = d->d_fsdata;
+ list_del_init(&sd->s_sibling);
+ configfs_put(sd);
+ if (d->d_inode)
+ simple_rmdir(parent->d_inode,d);
+
+ pr_debug(" o %s removing done (%d)\n",d->d_name.name,
+ atomic_read(&d->d_count));
+
+ dput(parent);
+}
+
+/**
+ * configfs_remove_dir - remove an config_item's directory.
+ * @item: config_item we're removing.
+ *
+ * The only thing special about this is that we remove any files in
+ * the directory before we remove the directory, and we've inlined
+ * what used to be configfs_rmdir() below, instead of calling separately.
+ */
+
+static void configfs_remove_dir(struct config_item * item)
+{
+ struct dentry * dentry = dget(item->ci_dentry);
+
+ if (!dentry)
+ return;
+
+ remove_dir(dentry);
+ /**
+ * Drop reference from dget() on entrance.
+ */
+ dput(dentry);
+}
+
+
+/* attaches attribute's configfs_dirent to the dentry corresponding to the
+ * attribute file
+ */
+static int configfs_attach_attr(struct configfs_dirent * sd, struct dentry * dentry)
+{
+ struct configfs_attribute * attr = sd->s_element;
+ int error;
+
+ error = configfs_create(dentry, (attr->ca_mode & S_IALLUGO) | S_IFREG, init_file);
+ if (error)
+ return error;
+
+ dentry->d_op = &configfs_dentry_ops;
+ dentry->d_fsdata = configfs_get(sd);
+ sd->s_dentry = dentry;
+ d_rehash(dentry);
+
+ return 0;
+}
+
+static struct dentry * configfs_lookup(struct inode *dir,
+ struct dentry *dentry,
+ struct nameidata *nd)
+{
+ struct configfs_dirent * parent_sd = dentry->d_parent->d_fsdata;
+ struct configfs_dirent * sd;
+ int found = 0;
+ int err = 0;
+
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_type & CONFIGFS_NOT_PINNED) {
+ const unsigned char * name = configfs_get_name(sd);
+
+ if (strcmp(name, dentry->d_name.name))
+ continue;
+
+ found = 1;
+ err = configfs_attach_attr(sd, dentry);
+ break;
+ }
+ }
+
+ if (!found) {
+ /*
+ * If it doesn't exist and it isn't a NOT_PINNED item,
+ * it must be negative.
+ */
+ return simple_lookup(dir, dentry, nd);
+ }
+
+ return ERR_PTR(err);
+}
+
+/*
+ * Only subdirectories count here. Files (CONFIGFS_NOT_PINNED) are
+ * attributes and are removed by rmdir(). We recurse, taking i_sem
+ * on all children that are candidates for default detach. If the
+ * result is clean, then configfs_detach_group() will handle dropping
+ * i_sem. If there is an error, the caller will clean up the i_sem
+ * holders via configfs_detach_rollback().
+ */
+static int configfs_detach_prep(struct dentry *dentry)
+{
+ struct configfs_dirent *parent_sd = dentry->d_fsdata;
+ struct configfs_dirent *sd;
+ int ret;
+
+ ret = -EBUSY;
+ if (!list_empty(&parent_sd->s_links))
+ goto out;
+
+ ret = 0;
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_type & CONFIGFS_NOT_PINNED)
+ continue;
+ if (sd->s_type & CONFIGFS_USET_DEFAULT) {
+ down(&sd->s_dentry->d_inode->i_sem);
+ /* Mark that we've taken i_sem */
+ sd->s_type |= CONFIGFS_USET_DROPPING;
+
+ ret = configfs_detach_prep(sd->s_dentry);
+ if (!ret)
+ continue;
+ } else
+ ret = -ENOTEMPTY;
+
+ break;
+ }
+
+out:
+ return ret;
+}
+
+/*
+ * Walk the tree, dropping i_sem wherever CONFIGFS_USET_DROPPING is
+ * set.
+ */
+static void configfs_detach_rollback(struct dentry *dentry)
+{
+ struct configfs_dirent *parent_sd = dentry->d_fsdata;
+ struct configfs_dirent *sd;
+
+ list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
+ if (sd->s_type & CONFIGFS_USET_DEFAULT) {
+ configfs_detach_rollback(sd->s_dentry);
+
+ if (sd->s_type & CONFIGFS_USET_DROPPING) {
+ sd->s_type &= ~CONFIGFS_USET_DROPPING;
+ up(&sd->s_dentry->d_inode->i_sem);
+ }
+ }
+ }
+}
+
+static void detach_attrs(struct config_item * item)
+{
+ struct dentry * dentry = dget(item->ci_dentry);
+ struct configfs_dirent * parent_sd;
+ struct configfs_dirent * sd, * tmp;
+
+ if (!dentry)
+ return;
+
+ pr_debug("configfs %s: dropping attrs for dir\n",
+ dentry->d_name.name);
+
+ parent_sd = dentry->d_fsdata;
+ list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
+ if (!sd->s_element || !(sd->s_type & CONFIGFS_NOT_PINNED))
+ continue;
+ list_del_init(&sd->s_sibling);
+ configfs_drop_dentry(sd, dentry);
+ configfs_put(sd);
+ }
+
+ /**
+ * Drop reference from dget() on entrance.
+ */
+ dput(dentry);
+}
+
+static int populate_attrs(struct config_item *item)
+{
+ struct config_item_type *t = item->ci_type;
+ struct configfs_attribute *attr;
+ int error = 0;
+ int i;
+
+ if (!t)
+ return -EINVAL;
+ if (t->ct_attrs) {
+ for (i = 0; (attr = t->ct_attrs[i]) != NULL; i++) {
+ if ((error = configfs_create_file(item, attr)))
+ break;
+ }
+ }
+
+ if (error)
+ detach_attrs(item);
+
+ return error;
+}
+
+static int configfs_attach_group(struct config_item *parent_item,
+ struct config_item *item,
+ struct dentry *dentry);
+static void configfs_detach_group(struct config_item *item);
+
+static void detach_groups(struct config_group *group)
+{
+ struct dentry * dentry = dget(group->cg_item.ci_dentry);
+ struct dentry *child;
+ struct configfs_dirent *parent_sd;
+ struct configfs_dirent *sd, *tmp;
+
+ if (!dentry)
+ return;
+
+ parent_sd = dentry->d_fsdata;
+ list_for_each_entry_safe(sd, tmp, &parent_sd->s_children, s_sibling) {
+ if (!sd->s_element ||
+ !(sd->s_type & CONFIGFS_USET_DEFAULT))
+ continue;
+
+ child = sd->s_dentry;
+
+ configfs_detach_group(sd->s_element);
+ child->d_inode->i_flags |= S_DEAD;
+
+ /*
+ * From rmdir/unregister, a configfs_detach_prep() pass
+ * has taken our i_sem for us. Drop it.
+ * From mkdir/register cleanup, there is no sem held.
+ */
+ if (sd->s_type & CONFIGFS_USET_DROPPING)
+ up(&child->d_inode->i_sem);
+
+ d_delete(child);
+ dput(child);
+ }
+
+ /**
+ * Drop reference from dget() on entrance.
+ */
+ dput(dentry);
+}
+
+/*
+ * This fakes mkdir(2) on a default_groups[] entry. It
+ * creates a dentry, attachs it, and then does fixup
+ * on the sd->s_type.
+ *
+ * We could, perhaps, tweak our parent's ->mkdir for a minute and
+ * try using vfs_mkdir. Just a thought.
+ */
+static int create_default_group(struct config_group *parent_group,
+ struct config_group *group)
+{
+ int ret;
+ struct qstr name;
+ struct configfs_dirent *sd;
+ /* We trust the caller holds a reference to parent */
+ struct dentry *child, *parent = parent_group->cg_item.ci_dentry;
+
+ if (!group->cg_item.ci_name)
+ group->cg_item.ci_name = group->cg_item.ci_namebuf;
+ name.name = group->cg_item.ci_name;
+ name.len = strlen(name.name);
+ name.hash = full_name_hash(name.name, name.len);
+
+ ret = -ENOMEM;
+ child = d_alloc(parent, &name);
+ if (child) {
+ d_add(child, NULL);
+
+ ret = configfs_attach_group(&parent_group->cg_item,
+ &group->cg_item, child);
+ if (!ret) {
+ sd = child->d_fsdata;
+ sd->s_type |= CONFIGFS_USET_DEFAULT;
+ } else {
+ d_delete(child);
+ dput(child);
+ }
+ }
+
+ return ret;
+}
+
+static int populate_groups(struct config_group *group)
+{
+ struct config_group *new_group;
+ struct dentry *dentry = group->cg_item.ci_dentry;
+ int ret = 0;
+ int i;
+
+ if (group && group->default_groups) {
+ /* FYI, we're faking mkdir here
+ * I'm not sure we need this semaphore, as we're called
+ * from our parent's mkdir. That holds our parent's
+ * i_sem, so afaik lookup cannot continue through our
+ * parent to find us, let alone mess with our tree.
+ * That said, taking our i_sem is closer to mkdir
+ * emulation, and shouldn't hurt. */
+ down(&dentry->d_inode->i_sem);
+
+ for (i = 0; group->default_groups[i]; i++) {
+ new_group = group->default_groups[i];
+
+ ret = create_default_group(group, new_group);
+ if (ret)
+ break;
+ }
+
+ up(&dentry->d_inode->i_sem);
+ }
+
+ if (ret)
+ detach_groups(group);
+
+ return ret;
+}
+
+/*
+ * All of link_obj/unlink_obj/link_group/unlink_group require that
+ * subsys->su_sem is held.
+ */
+
+static void unlink_obj(struct config_item *item)
+{
+ struct config_group *group;
+
+ group = item->ci_group;
+ if (group) {
+ list_del_init(&item->ci_entry);
+
+ item->ci_group = NULL;
+ item->ci_parent = NULL;
+ config_item_put(item);
+
+ config_group_put(group);
+ }
+}
+
+static void link_obj(struct config_item *parent_item, struct config_item *item)
+{
+ /* Parent seems redundant with group, but it makes certain
+ * traversals much nicer. */
+ item->ci_parent = parent_item;
+ item->ci_group = config_group_get(to_config_group(parent_item));
+ list_add_tail(&item->ci_entry, &item->ci_group->cg_children);
+
+ config_item_get(item);
+}
+
+static void unlink_group(struct config_group *group)
+{
+ int i;
+ struct config_group *new_group;
+
+ if (group->default_groups) {
+ for (i = 0; group->default_groups[i]; i++) {
+ new_group = group->default_groups[i];
+ unlink_group(new_group);
+ }
+ }
+
+ group->cg_subsys = NULL;
+ unlink_obj(&group->cg_item);
+}
+
+static void link_group(struct config_group *parent_group, struct config_group *group)
+{
+ int i;
+ struct config_group *new_group;
+ struct configfs_subsystem *subsys = NULL; /* gcc is a turd */
+
+ link_obj(&parent_group->cg_item, &group->cg_item);
+
+ if (parent_group->cg_subsys)
+ subsys = parent_group->cg_subsys;
+ else if (configfs_is_root(&parent_group->cg_item))
+ subsys = to_configfs_subsystem(group);
+ else
+ BUG();
+ group->cg_subsys = subsys;
+
+ if (group->default_groups) {
+ for (i = 0; group->default_groups[i]; i++) {
+ new_group = group->default_groups[i];
+ link_group(group, new_group);
+ }
+ }
+}
+
+/*
+ * The goal is that configfs_attach_item() (and
+ * configfs_attach_group()) can be called from either the VFS or this
+ * module. That is, they assume that the items have been created,
+ * the dentry allocated, and the dcache is all ready to go.
+ *
+ * If they fail, they must clean up after themselves as if they
+ * had never been called. The caller (VFS or local function) will
+ * handle cleaning up the dcache bits.
+ *
+ * configfs_detach_group() and configfs_detach_item() behave similarly on
+ * the way out. They assume that the proper semaphores are held, they
+ * clean up the configfs items, and they expect their callers will
+ * handle the dcache bits.
+ */
+static int configfs_attach_item(struct config_item *parent_item,
+ struct config_item *item,
+ struct dentry *dentry)
+{
+ int ret;
+
+ ret = configfs_create_dir(item, dentry);
+ if (!ret) {
+ ret = populate_attrs(item);
+ if (ret) {
+ configfs_remove_dir(item);
+ d_delete(dentry);
+ }
+ }
+
+ return ret;
+}
+
+static void configfs_detach_item(struct config_item *item)
+{
+ detach_attrs(item);
+ configfs_remove_dir(item);
+}
+
+static int configfs_attach_group(struct config_item *parent_item,
+ struct config_item *item,
+ struct dentry *dentry)
+{
+ int ret;
+ struct configfs_dirent *sd;
+
+ ret = configfs_attach_item(parent_item, item, dentry);
+ if (!ret) {
+ sd = dentry->d_fsdata;
+ sd->s_type |= CONFIGFS_USET_DIR;
+
+ ret = populate_groups(to_config_group(item));
+ if (ret) {
+ configfs_detach_item(item);
+ d_delete(dentry);
+ }
+ }
+
+ return ret;
+}
+
+static void configfs_detach_group(struct config_item *item)
+{
+ detach_groups(to_config_group(item));
+ configfs_detach_item(item);
+}
+
+/*
+ * Drop the initial reference from make_item()/make_group()
+ * This function assumes that reference is held on item
+ * and that item holds a valid reference to the parent. Also, it
+ * assumes the caller has validated ci_type.
+ */
+static void client_drop_item(struct config_item *parent_item,
+ struct config_item *item)
+{
+ struct config_item_type *type;
+
+ type = parent_item->ci_type;
+ BUG_ON(!type);
+
+ if (type->ct_group_ops && type->ct_group_ops->drop_item)
+ type->ct_group_ops->drop_item(to_config_group(parent_item),
+ item);
+ else
+ config_item_put(item);
+}
+
+
+static int configfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
+{
+ int ret;
+ struct config_group *group;
+ struct config_item *item;
+ struct config_item *parent_item;
+ struct configfs_subsystem *subsys;
+ struct configfs_dirent *sd;
+ struct config_item_type *type;
+ struct module *owner;
+ char *name;
+
+ if (dentry->d_parent == configfs_sb->s_root)
+ return -EPERM;
+
+ sd = dentry->d_parent->d_fsdata;
+ if (!(sd->s_type & CONFIGFS_USET_DIR))
+ return -EPERM;
+
+ parent_item = configfs_get_config_item(dentry->d_parent);
+ type = parent_item->ci_type;
+ subsys = to_config_group(parent_item)->cg_subsys;
+ BUG_ON(!subsys);
+
+ if (!type || !type->ct_group_ops ||
+ (!type->ct_group_ops->make_group &&
+ !type->ct_group_ops->make_item)) {
+ config_item_put(parent_item);
+ return -EPERM; /* What lack-of-mkdir returns */
+ }
+
+ name = kmalloc(dentry->d_name.len + 1, GFP_KERNEL);
+ if (!name) {
+ config_item_put(parent_item);
+ return -ENOMEM;
+ }
+ snprintf(name, dentry->d_name.len + 1, "%s", dentry->d_name.name);
+
+ down(&subsys->su_sem);
+ group = NULL;
+ item = NULL;
+ if (type->ct_group_ops->make_group) {
+ group = type->ct_group_ops->make_group(to_config_group(parent_item), name);
+ if (group) {
+ link_group(to_config_group(parent_item), group);
+ item = &group->cg_item;
+ }
+ } else {
+ item = type->ct_group_ops->make_item(to_config_group(parent_item), name);
+ if (item)
+ link_obj(parent_item, item);
+ }
+ up(&subsys->su_sem);
+
+ kfree(name);
+ if (!item) {
+ config_item_put(parent_item);
+ return -ENOMEM;
+ }
+
+ ret = -EINVAL;
+ type = item->ci_type;
+ if (type) {
+ owner = type->ct_owner;
+ if (try_module_get(owner)) {
+ if (group) {
+ ret = configfs_attach_group(parent_item,
+ item,
+ dentry);
+ } else {
+ ret = configfs_attach_item(parent_item,
+ item,
+ dentry);
+ }
+
+ if (ret) {
+ down(&subsys->su_sem);
+ if (group)
+ unlink_group(group);
+ else
+ unlink_obj(item);
+ client_drop_item(parent_item, item);
+ up(&subsys->su_sem);
+
+ config_item_put(parent_item);
+ module_put(owner);
+ }
+ }
+ }
+
+ return ret;
+}
+
+static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
+{
+ struct config_item *parent_item;
+ struct config_item *item;
+ struct configfs_subsystem *subsys;
+ struct configfs_dirent *sd;
+ struct module *owner = NULL;
+ int ret;
+
+ if (dentry->d_parent == configfs_sb->s_root)
+ return -EPERM;
+
+ sd = dentry->d_fsdata;
+ if (sd->s_type & CONFIGFS_USET_DEFAULT)
+ return -EPERM;
+
+ parent_item = configfs_get_config_item(dentry->d_parent);
+ subsys = to_config_group(parent_item)->cg_subsys;
+ BUG_ON(!subsys);
+
+ if (!parent_item->ci_type) {
+ config_item_put(parent_item);
+ return -EINVAL;
+ }
+
+ ret = configfs_detach_prep(dentry);
+ if (ret) {
+ configfs_detach_rollback(dentry);
+ config_item_put(parent_item);
+ return ret;
+ }
+
+ item = configfs_get_config_item(dentry);
+
+ /* Drop reference from above, item already holds one. */
+ config_item_put(parent_item);
+
+ if (item->ci_type)
+ owner = item->ci_type->ct_owner;
+
+ if (sd->s_type & CONFIGFS_USET_DIR) {
+ configfs_detach_group(item);
+
+ down(&subsys->su_sem);
+ unlink_group(to_config_group(item));
+ } else {
+ configfs_detach_item(item);
+
+ down(&subsys->su_sem);
+ unlink_obj(item);
+ }
+
+ client_drop_item(parent_item, item);
+ up(&subsys->su_sem);
+
+ /* Drop our reference from above */
+ config_item_put(item);
+
+ module_put(owner);
+
+ return 0;
+}
+
+struct inode_operations configfs_dir_inode_operations = {
+ .mkdir = configfs_mkdir,
+ .rmdir = configfs_rmdir,
+ .symlink = configfs_symlink,
+ .unlink = configfs_unlink,
+ .lookup = configfs_lookup,
+};
+
+#if 0
+int configfs_rename_dir(struct config_item * item, const char *new_name)
+{
+ int error = 0;
+ struct dentry * new_dentry, * parent;
+
+ if (!strcmp(config_item_name(item), new_name))
+ return -EINVAL;
+
+ if (!item->parent)
+ return -EINVAL;
+
+ down_write(&configfs_rename_sem);
+ parent = item->parent->dentry;
+
+ down(&parent->d_inode->i_sem);
+
+ new_dentry = lookup_one_len(new_name, parent, strlen(new_name));
+ if (!IS_ERR(new_dentry)) {
+ if (!new_dentry->d_inode) {
+ error = config_item_set_name(item, "%s", new_name);
+ if (!error) {
+ d_add(new_dentry, NULL);
+ d_move(item->dentry, new_dentry);
+ }
+ else
+ d_delete(new_dentry);
+ } else
+ error = -EEXIST;
+ dput(new_dentry);
+ }
+ up(&parent->d_inode->i_sem);
+ up_write(&configfs_rename_sem);
+
+ return error;
+}
+#endif
+
+static int configfs_dir_open(struct inode *inode, struct file *file)
+{
+ struct dentry * dentry = file->f_dentry;
+ struct configfs_dirent * parent_sd = dentry->d_fsdata;
+
+ down(&dentry->d_inode->i_sem);
+ file->private_data = configfs_new_dirent(parent_sd, NULL);
+ up(&dentry->d_inode->i_sem);
+
+ return file->private_data ? 0 : -ENOMEM;
+
+}
+
+static int configfs_dir_close(struct inode *inode, struct file *file)
+{
+ struct dentry * dentry = file->f_dentry;
+ struct configfs_dirent * cursor = file->private_data;
+
+ down(&dentry->d_inode->i_sem);
+ list_del_init(&cursor->s_sibling);
+ up(&dentry->d_inode->i_sem);
+
+ release_configfs_dirent(cursor);
+
+ return 0;
+}
+
+/* Relationship between s_mode and the DT_xxx types */
+static inline unsigned char dt_type(struct configfs_dirent *sd)
+{
+ return (sd->s_mode >> 12) & 15;
+}
+
+static int configfs_readdir(struct file * filp, void * dirent, filldir_t filldir)
+{
+ struct dentry *dentry = filp->f_dentry;
+ struct configfs_dirent * parent_sd = dentry->d_fsdata;
+ struct configfs_dirent *cursor = filp->private_data;
+ struct list_head *p, *q = &cursor->s_sibling;
+ ino_t ino;
+ int i = filp->f_pos;
+
+ switch (i) {
+ case 0:
+ ino = dentry->d_inode->i_ino;
+ if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ case 1:
+ ino = parent_ino(dentry);
+ if (filldir(dirent, "..", 2, i, ino, DT_DIR) < 0)
+ break;
+ filp->f_pos++;
+ i++;
+ /* fallthrough */
+ default:
+ if (filp->f_pos == 2) {
+ list_del(q);
+ list_add(q, &parent_sd->s_children);
+ }
+ for (p=q->next; p!= &parent_sd->s_children; p=p->next) {
+ struct configfs_dirent *next;
+ const char * name;
+ int len;
+
+ next = list_entry(p, struct configfs_dirent,
+ s_sibling);
+ if (!next->s_element)
+ continue;
+
+ name = configfs_get_name(next);
+ len = strlen(name);
+ if (next->s_dentry)
+ ino = next->s_dentry->d_inode->i_ino;
+ else
+ ino = iunique(configfs_sb, 2);
+
+ if (filldir(dirent, name, len, filp->f_pos, ino,
+ dt_type(next)) < 0)
+ return 0;
+
+ list_del(q);
+ list_add(q, p);
+ p = q;
+ filp->f_pos++;
+ }
+ }
+ return 0;
+}
+
+static loff_t configfs_dir_lseek(struct file * file, loff_t offset, int origin)
+{
+ struct dentry * dentry = file->f_dentry;
+
+ down(&dentry->d_inode->i_sem);
+ switch (origin) {
+ case 1:
+ offset += file->f_pos;
+ case 0:
+ if (offset >= 0)
+ break;
+ default:
+ up(&file->f_dentry->d_inode->i_sem);
+ return -EINVAL;
+ }
+ if (offset != file->f_pos) {
+ file->f_pos = offset;
+ if (file->f_pos >= 2) {
+ struct configfs_dirent *sd = dentry->d_fsdata;
+ struct configfs_dirent *cursor = file->private_data;
+ struct list_head *p;
+ loff_t n = file->f_pos - 2;
+
+ list_del(&cursor->s_sibling);
+ p = sd->s_children.next;
+ while (n && p != &sd->s_children) {
+ struct configfs_dirent *next;
+ next = list_entry(p, struct configfs_dirent,
+ s_sibling);
+ if (next->s_element)
+ n--;
+ p = p->next;
+ }
+ list_add_tail(&cursor->s_sibling, p);
+ }
+ }
+ up(&dentry->d_inode->i_sem);
+ return offset;
+}
+
+struct file_operations configfs_dir_operations = {
+ .open = configfs_dir_open,
+ .release = configfs_dir_close,
+ .llseek = configfs_dir_lseek,
+ .read = generic_read_dir,
+ .readdir = configfs_readdir,
+};
+
+int configfs_register_subsystem(struct configfs_subsystem *subsys)
+{
+ int err;
+ struct config_group *group = &subsys->su_group;
+ struct qstr name;
+ struct dentry *dentry;
+ struct configfs_dirent *sd;
+
+ err = configfs_pin_fs();
+ if (err)
+ return err;
+
+ if (!group->cg_item.ci_name)
+ group->cg_item.ci_name = group->cg_item.ci_namebuf;
+
+ sd = configfs_sb->s_root->d_fsdata;
+ link_group(to_config_group(sd->s_element), group);
+
+ down(&configfs_sb->s_root->d_inode->i_sem);
+
+ name.name = group->cg_item.ci_name;
+ name.len = strlen(name.name);
+ name.hash = full_name_hash(name.name, name.len);
+
+ err = -ENOMEM;
+ dentry = d_alloc(configfs_sb->s_root, &name);
+ if (!dentry)
+ goto out_release;
+
+ d_add(dentry, NULL);
+
+ err = configfs_attach_group(sd->s_element, &group->cg_item,
+ dentry);
+ if (!err)
+ dentry = NULL;
+ else
+ d_delete(dentry);
+
+ up(&configfs_sb->s_root->d_inode->i_sem);
+
+ if (dentry) {
+ dput(dentry);
+out_release:
+ unlink_group(group);
+ configfs_release_fs();
+ }
+
+ return err;
+}
+
+void configfs_unregister_subsystem(struct configfs_subsystem *subsys)
+{
+ struct config_group *group = &subsys->su_group;
+ struct dentry *dentry = group->cg_item.ci_dentry;
+
+ if (dentry->d_parent != configfs_sb->s_root) {
+ printk(KERN_ERR "configfs: Tried to unregister non-subsystem!\n");
+ return;
+ }
+
+ down(&configfs_sb->s_root->d_inode->i_sem);
+ down(&dentry->d_inode->i_sem);
+ if (configfs_detach_prep(dentry)) {
+ printk(KERN_ERR "configfs: Tried to unregister non-empty subsystem!\n");
+ }
+ configfs_detach_group(&group->cg_item);
+ dentry->d_inode->i_flags |= S_DEAD;
+ up(&dentry->d_inode->i_sem);
+
+ d_delete(dentry);
+
+ up(&configfs_sb->s_root->d_inode->i_sem);
+
+ dput(dentry);
+
+ unlink_group(group);
+ configfs_release_fs();
+}
+
+EXPORT_SYMBOL(configfs_register_subsystem);
+EXPORT_SYMBOL(configfs_unregister_subsystem);
--- /dev/null
+/* -*- 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);
+}
+
--- /dev/null
+/* -*- 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);
+}
+
+
--- /dev/null
+/* -*- 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);
+
--- /dev/null
+/* -*- 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);
--- /dev/null
+/* -*- 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,
+};
+
--- /dev/null
+/* -*- mode: c; c-basic-offset: 8; -*-
+ * vim: noexpandtab sw=8 ts=8 sts=0:
+ *
+ * configfs.h - definitions for the device driver filesystem
+ *
+ * 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
+ *
+ * Based on kobject.h:
+ * Copyright (c) 2002-2003 Patrick Mochel
+ * Copyright (c) 2002-2003 Open Source Development Labs
+ *
+ * configfs Copyright (C) 2005 Oracle. All rights reserved.
+ *
+ * Please read Documentation/filesystems/configfs.txt before using the
+ * configfs interface, ESPECIALLY the parts about reference counts and
+ * item destructors.
+ */
+
+#ifndef _CONFIGFS_H_
+#define _CONFIGFS_H_
+
+#ifdef __KERNEL__
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/kref.h>
+
+#include <asm/atomic.h>
+#include <asm/semaphore.h>
+
+#define CONFIGFS_ITEM_NAME_LEN 20
+
+struct module;
+
+struct configfs_item_operations;
+struct configfs_group_operations;
+struct configfs_attribute;
+struct configfs_subsystem;
+
+struct config_item {
+ char *ci_name;
+ char ci_namebuf[CONFIGFS_ITEM_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;
+};
+
+extern int config_item_set_name(struct config_item *, const char *, ...);
+
+static inline char *config_item_name(struct config_item * item)
+{
+ return item->ci_name;
+}
+
+extern void config_item_init(struct config_item *);
+extern void config_item_init_type_name(struct config_item *item,
+ const char *name,
+ struct config_item_type *type);
+extern void config_item_cleanup(struct config_item *);
+
+extern struct config_item * config_item_get(struct config_item *);
+extern void config_item_put(struct config_item *);
+
+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;
+};
+
+
+/**
+ * group - a group of config_items of a specific type, belonging
+ * to a specific subsystem.
+ */
+
+struct config_group {
+ struct config_item cg_item;
+ struct list_head cg_children;
+ struct configfs_subsystem *cg_subsys;
+ struct config_group **default_groups;
+};
+
+
+extern void config_group_init(struct config_group *group);
+extern void config_group_init_type_name(struct config_group *group,
+ const char *name,
+ struct config_item_type *type);
+
+
+static inline struct config_group *to_config_group(struct config_item *item)
+{
+ return item ? container_of(item,struct config_group,cg_item) : NULL;
+}
+
+static inline struct config_group *config_group_get(struct config_group *group)
+{
+ return group ? to_config_group(config_item_get(&group->cg_item)) : NULL;
+}
+
+static inline void config_group_put(struct config_group *group)
+{
+ config_item_put(&group->cg_item);
+}
+
+extern struct config_item *config_group_find_obj(struct config_group *, const char *);
+
+
+struct configfs_attribute {
+ char *ca_name;
+ struct module *ca_owner;
+ mode_t ca_mode;
+};
+
+
+/*
+ * If allow_link() exists, the item can symlink(2) out to other
+ * items. If the item is a group, it may support mkdir(2).
+ * Groups supply one of make_group() and make_item(). If the
+ * group supports make_group(), one can create group children. If it
+ * supports make_item(), one can create config_item children. If it has
+ * default_groups on group->default_groups, it has automatically created
+ * group children. default_groups may coexist alongsize make_group() or
+ * make_item(), but if the group wishes to have only default_groups
+ * children (disallowing mkdir(2)), it need not provide either function.
+ * If the group has commit(), it supports pending and commited (active)
+ * items.
+ */
+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 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);
+};
+
+
+
+/**
+ * Use these macros to make defining attributes easier. See include/linux/device.h
+ * for examples..
+ */
+
+#if 0
+#define __ATTR(_name,_mode,_show,_store) { \
+ .attr = {.ca_name = __stringify(_name), .ca_mode = _mode, .ca_owner = THIS_MODULE }, \
+ .show = _show, \
+ .store = _store, \
+}
+
+#define __ATTR_RO(_name) { \
+ .attr = { .ca_name = __stringify(_name), .ca_mode = 0444, .ca_owner = THIS_MODULE }, \
+ .show = _name##_show, \
+}
+
+#define __ATTR_NULL { .attr = { .name = NULL } }
+
+#define attr_name(_attr) (_attr).attr.name
+#endif
+
+
+struct configfs_subsystem {
+ struct config_group su_group;
+ struct semaphore su_sem;
+};
+
+static inline struct configfs_subsystem *to_configfs_subsystem(struct config_group *group)
+{
+ return group ?
+ container_of(group, struct configfs_subsystem, su_group) :
+ NULL;
+}
+
+int configfs_register_subsystem(struct configfs_subsystem *subsys);
+void configfs_unregister_subsystem(struct configfs_subsystem *subsys);
+
+#endif /* __KERNEL__ */
+
+#endif /* _CONFIGFS_H_ */
projects / kernel / kernel-generic.git / commitdiff