diff options
| -rw-r--r-- | Documentation/filesystems/00-INDEX | 2 | ||||
| -rw-r--r-- | Documentation/filesystems/configfs/configfs.txt | 434 | ||||
| -rw-r--r-- | Documentation/filesystems/configfs/configfs_example.c | 474 | ||||
| -rw-r--r-- | MAINTAINERS | 5 | ||||
| -rw-r--r-- | fs/Kconfig | 14 | ||||
| -rw-r--r-- | fs/Makefile | 1 | ||||
| -rw-r--r-- | fs/configfs/Makefile | 7 | ||||
| -rw-r--r-- | fs/configfs/configfs_internal.h | 142 | ||||
| -rw-r--r-- | fs/configfs/dir.c | 1102 | ||||
| -rw-r--r-- | fs/configfs/file.c | 360 | ||||
| -rw-r--r-- | fs/configfs/inode.c | 162 | ||||
| -rw-r--r-- | fs/configfs/item.c | 227 | ||||
| -rw-r--r-- | fs/configfs/mount.c | 159 | ||||
| -rw-r--r-- | fs/configfs/symlink.c | 281 | ||||
| -rw-r--r-- | include/linux/configfs.h | 205 |
15 files changed, 3575 insertions, 0 deletions
diff --git a/Documentation/filesystems/00-INDEX b/Documentation/filesystems/00-INDEX index bcfbab8..628f8a7 100644 --- a/Documentation/filesystems/00-INDEX +++ b/Documentation/filesystems/00-INDEX @@ -12,6 +12,8 @@ cifs.txt - description of the CIFS filesystem coda.txt - description of the CODA filesystem. +configfs/ + - directory containing configfs documentation and example code. cramfs.txt - info on the cram filesystem for small storage (ROMs etc) devfs/ diff --git a/Documentation/filesystems/configfs/configfs.txt b/Documentation/filesystems/configfs/configfs.txt new file mode 100644 index 0000000..c4ff96b --- /dev/null +++ b/Documentation/filesystems/configfs/configfs.txt @@ -0,0 +1,434 @@ + +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. + + diff --git a/Documentation/filesystems/configfs/configfs_example.c b/Documentation/filesystems/configfs/configfs_example.c new file mode 100644 index 0000000..f3c6e49 --- /dev/null +++ b/Documentation/filesystems/configfs/configfs_example.c @@ -0,0 +1,474 @@ +/* + * 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"); diff --git a/MAINTAINERS b/MAINTAINERS index 6af6830..86ee06f 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -554,6 +554,11 @@ W: http://us1.samba.org/samba/Linux_CIFS_client.html T: git kernel.org:/pub/scm/linux/kernel/git/sfrench/cifs-2.6.git S: Supported +CONFIGFS +P: Joel Becker +M: Joel Becker <joel.becker@oracle.com> +S: Supported + CIRRUS LOGIC GENERIC FBDEV DRIVER P: Jeff Garzik M: jgarzik@pobox.com @@ -841,6 +841,20 @@ config RELAYFS_FS If unsure, say N. +config CONFIGFS_FS + tristate "Userspace-driven configuration filesystem (EXPERIMENTAL)" + depends on EXPERIMENTAL + help + configfs is a ram-based filesystem that provides the converse + of sysfs's functionality. Where sysfs is a filesystem-based + view of kernel objects, configfs is a filesystem-based manager + of kernel objects, or config_items. + + Both sysfs and configfs can and should exist together on the + same system. One is not a replacement for the other. + + If unsure, say N. + endmenu menu "Miscellaneous filesystems" diff --git a/fs/Makefile b/fs/Makefile index 4c26557..ff3d48a 100644 --- a/fs/Makefile +++ b/fs/Makefile @@ -101,3 +101,4 @@ obj-$(CONFIG_BEFS_FS) += befs/ obj-$(CONFIG_HOSTFS) += hostfs/ obj-$(CONFIG_HPPFS) += hppfs/ obj-$(CONFIG_DEBUG_FS) += debugfs/ +obj-$(CONFIG_CONFIGFS_FS) += configfs/ diff --git a/fs/configfs/Makefile b/fs/configfs/Makefile new file mode 100644 index 0000000..00ffb27 --- /dev/null +++ b/fs/configfs/Makefile @@ -0,0 +1,7 @@ +# +# Makefile for the configfs virtual filesystem +# + +obj-$(CONFIG_CONFIGFS_FS) += configfs.o + +configfs-objs := inode.o file.o dir.o symlink.o mount.o item.o diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h new file mode 100644 index 0000000..8899d9c --- /dev/null +++ b/fs/configfs/configfs_internal.h @@ -0,0 +1,142 @@ +/* -*- 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); +} + diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c new file mode 100644 index 0000000..e48b539 --- /dev/null +++ b/fs/configfs/dir.c @@ -0,0 +1,1102 @@ +/* -*- 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); diff --git a/fs/configfs/file.c b/fs/configfs/file.c new file mode 100644 index 0000000..af1ffc9 --- /dev/null +++ b/fs/configfs/file.c @@ -0,0 +1,360 @@ +/* -*- 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); +} + diff --git a/fs/configfs/inode.c b/fs/configfs/inode.c new file mode 100644 index 0000000..6b274c6 --- /dev/null +++ b/fs/configfs/inode.c @@ -0,0 +1,162 @@ +/* -*- 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); +} + + diff --git a/fs/configfs/item.c b/fs/configfs/item.c new file mode 100644 index 0000000..e07485a --- /dev/null +++ b/fs/configfs/item.c @@ -0,0 +1,227 @@ +/* -*- 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); + diff --git a/fs/configfs/mount.c b/fs/configfs/mount.c new file mode 100644 index 0000000..1a2f6f6 --- /dev/null +++ b/fs/configfs/mount.c @@ -0,0 +1,159 @@ +/* -*- 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); diff --git a/fs/configfs/symlink.c b/fs/configfs/symlink.c new file mode 100644 index 0000000..50f5840 --- /dev/null +++ b/fs/configfs/symlink.c @@ -0,0 +1,281 @@ +/* -*- 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, +}; + diff --git a/include/linux/configfs.h b/include/linux/configfs.h new file mode 100644 index 0000000..acffb8c --- /dev/null +++ b/include/linux/configfs.h @@ -0,0 +1,205 @@ +/* -*- 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_ */ |