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driverfs: die die die

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Documentation/filesystems/driverfs.txt deleted 100644 → 0
View file @ 60211581
driverfs - The Device Driver Filesystem
Patrick Mochel <mochel@osdl.org>
2 August 2002
What it is:
~~~~~~~~~~~
driverfs is a ram-based filesystem. It was created by copying
ramfs/inode.c to driverfs/inode.c and doing a little search-and-replace.
driverfs is a means to export kernel data structures, their
attributes, and the linkages between them to userspace.
driverfs provides a unified interface for exporting attributes to
userspace. Currently, this interface is available only to device and
bus drivers.
Using driverfs
~~~~~~~~~~~~~~
driverfs is always compiled in. You can access it by doing something like:
mount -t driverfs driverfs /devices
Top Level Directory Layout
~~~~~~~~~~~~~~~~~~~~~~~~~~
The driverfs directory arrangement exposes the relationship of kernel
data structures.
The top level driverfs diretory looks like:
bus/
root/
root/ contains a filesystem representation of the device tree. It maps
directly to the internal kernel device tree, which is a hierarchy of
struct device.
bus/ contains flat directory layout of the various bus types in the
kernel. Each bus's directory contains two subdirectories:
devices/
drivers/
devices/ contains symlinks for each device discovered in the system
that point to the device's directory under root/.
drivers/ contains a directory for each device driver that is loaded
for devices on that particular bus (this assmumes that drivers do not
span multiple bus types).
More information can device-model specific features can be found in
Documentation/device-model/.
Directory Contents
~~~~~~~~~~~~~~~~~~
Each object that is represented in driverfs gets a directory, rather
than a file, to make it simple to export attributes of that object.
Attributes are exported via ASCII text files. The programming
interface is discussed below.
Instead of having monolithic files that are difficult to parse, all
files are intended to export one attribute. The name of the attribute
is the name of the file. The value of the attribute are the contents
of the file.
There should be few, if any, exceptions to this rule. You should not
violate it, for fear of public humilation.
The Two-Tier Model
~~~~~~~~~~~~~~~~~~
driverfs is a very simple, low-level interface. In order for kernel
objects to use it, there must be an intermediate layer in place for
each object type.
All calls in driverfs are intended to be as type-safe as possible.
In order to extend driverfs to support multiple data types, a layer of
abstraction was required. This intermediate layer converts between the
generic calls and data structures of the driverfs core to the
subsystem-specific objects and calls.
The Subsystem Interface
~~~~~~~~~~~~~~~~~~~~~~~
The subsystems bear the responsibility of implementing driverfs
extensions for the objects they control. Fortunately, it's intended to
be really easy to do so.
It's divided into three sections: directories, files, and operations.
Directories
~~~~~~~~~~~
struct driver_dir_entry {
char * name;
struct dentry * dentry;
mode_t mode;
struct driverfs_ops * ops;
};
int
driverfs_create_dir(struct driver_dir_entry *, struct driver_dir_entry *);
void
driverfs_remove_dir(struct driver_dir_entry * entry);
The directory structure should be statically allocated, and reside in
a subsystem-specific data structure:
struct device {
...
struct driver_dir_entry dir;
};
The subsystem is responsible for initializing the name, mode, and ops
fields of the directory entry. (More on struct driverfs_ops later)
Files
~~~~~
struct attribute {
char * name;
mode_t mode;
};
int
driverfs_create_file(struct attribute * attr, struct driver_dir_entry * parent);
void
driverfs_remove_file(struct driver_dir_entry *, const char * name);
The attribute structure is a simple, common token that the driverfs
core handles. It has little use on its own outside of the
core. Objects cannot use a plain struct attribute to export
attributes, since there are no callbacks for reading and writing data.
Therefore, the subsystem is required to define a data structure that
encapsulates the attribute structure, and provides type-safe callbacks
for reading and writing data.
An example looks like this:
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device * dev, char * buf, size_t count, loff_t off);
ssize_t (*store)(struct device * dev, const char * buf, size_t count, loff_t off);
};
Note that there is a struct attribute embedded in the structure. In
order to relieve pain in declaring attributes, the subsystem should
also define a macro, like:
#define DEVICE_ATTR(_name,_mode,_show,_store) \
struct device_attribute dev_attr_##_name = { \
.attr = {.name = __stringify(_name) , .mode = _mode }, \
.show = _show, \
.store = _store, \
};
This hides the initialization of the embedded struct, and in general,
the internals of each structure. It yields a structure by the name of
dev_attr_<name>.
In order for objects to create files, the subsystem should create
wrapper functions, like this:
int device_create_file(struct device *device, struct device_attribute * entry);
void device_remove_file(struct device * dev, struct device_attribute * attr);
..and forward the call on to the driverfs functions.
Note that there is no unique information in the attribute structures,
so the same structure can be used to describe files of several
different object instances.
Operations
~~~~~~~~~~
struct driverfs_ops {
int (*open)(struct driver_dir_entry *);
int (*close)(struct driver_dir_entry *);
ssize_t (*show)(struct driver_dir_entry *, struct attribute *,char *, size_t, loff_t);
ssize_t (*store)(struct driver_dir_entry *,struct attribute *,const char *, size_t, loff_t);
};
Subsystems are required to implement this set of callbacks. Their
purpose is to translate the generic data structures into the specific
objects, and operate on them. This can be done by defining macros like
this:
#define to_dev_attr(_attr) container_of(_attr,struct device_attribute,attr)
#define to_device(d) container_of(d, struct device, dir)
Since the directories are statically allocated in the object, you can
derive the pointer to the object that owns the file. Ditto for the
attribute structures.
Current Interfaces
~~~~~~~~~~~~~~~~~~
The following interface layers currently exist in driverfs:
- devices (include/linux/device.h)
----------------------------------
Structure:
struct device_attribute {
struct attribute attr;
ssize_t (*show)(struct device * dev, char * buf, size_t count, loff_t off);
ssize_t (*store)(struct device * dev, const char * buf, size_t count, loff_t off);
};
Declaring:
DEVICE_ATTR(_name,_str,_mode,_show,_store);
Creation/Removal:
int device_create_file(struct device *device, struct device_attribute * entry);
void device_remove_file(struct device * dev, struct device_attribute * attr);
- bus drivers (include/linux/device.h)
--------------------------------------
Structure:
struct bus_attribute {
struct attribute attr;
ssize_t (*show)(struct bus_type *, char * buf, size_t count, loff_t off);
ssize_t (*store)(struct bus_type *, const char * buf, size_t count, loff_t off);
};
Declaring:
BUS_ATTR(_name,_mode,_show,_store)
Creation/Removal:
int bus_create_file(struct bus_type *, struct bus_attribute *);
void bus_remove_file(struct bus_type *, struct bus_attribute *);
- device drivers (include/linux/device.h)
-----------------------------------------
Structure:
struct driver_attribute {
struct attribute attr;
ssize_t (*show)(struct device_driver *, char * buf, size_t count, loff_t off);
ssize_t (*store)(struct device_driver *, const char * buf, size_t count, loff_t off);
};
Declaring:
DRIVER_ATTR(_name,_mode,_show,_store)
Creation/Removal:
int driver_create_file(struct device_driver *, struct driver_attribute *);
void driver_remove_file(struct device_driver *, struct driver_attribute *);
Reading/Writing Data
~~~~~~~~~~~~~~~~~~~~
The callback functionality is similar to the way procfs works. When a
user performs a read(2) or write(2) on the file, it first calls a
driverfs function. This calls to the subsystem, which then calls to
the object's show() or store() function.
The buffer pointer, offset, and length should be passed to each
function. The downstream callback should fill the buffer and return
the number of bytes read/written.
What driverfs is not:
~~~~~~~~~~~~~~~~~~~~~
It is not a replacement for either devfs or procfs.
It does not handle device nodes, like devfs is intended to do. I think
this functionality is possible, but indeed think that integration of
the device nodes and control files should be done. Whether driverfs or
devfs, or something else, is the place to do it, I don't know.
It is not intended to be a replacement for all of the procfs
functionality. I think that many of the driver files should be moved
out of /proc (and maybe a few other things as well ;).
Limitations:
~~~~~~~~~~~~
The driverfs functions assume that at most a page is being either read
or written each time.
There is a race condition that is really, really hard to fix; if not
impossible. There exists a race between a driverfs file being opened
and the object that owns the file going away. During the driverfs
open() callback, the reference count for the owning object needs to be
incremented.
For drivers, we can put a struct module * owner in struct driver_dir_entry
and do try_inc_mod_count() when we open a file. However, this won't
work for devices, that aren't tied to a module. And, it is still not
guaranteed to solve the race.
I'm looking into fixing this, but it may not be doable without making
a separate filesystem instance for each object. It's fun stuff. Please
mail me with creative ideas that you know will work.
Possible bugs:
~~~~~~~~~~~~~~
It may not deal with offsets and/or seeks very well, especially if
they cross a page boundary.
fs/Makefile
View file @ 808897cf
...@@ -37,7 +37,7 @@ obj-$(CONFIG_QUOTACTL) += quota.o ...@@ -37,7 +37,7 @@ obj-$(CONFIG_QUOTACTL) += quota.o
obj-$(CONFIG_PROC_FS) += proc/ obj-$(CONFIG_PROC_FS) += proc/
obj-y += partitions/ obj-y += partitions/
obj-y += driverfs/ sysfs/ obj-y += sysfs/
obj-y += devpts/ obj-y += devpts/
obj-$(CONFIG_PROFILING) += dcookies.o obj-$(CONFIG_PROFILING) += dcookies.o
......
fs/driverfs/Makefile deleted 100644 → 0
View file @ 60211581
#
# Makefile for the driverfs virtual filesystem.
#
export-objs := inode.o
obj-y := inode.o
include $(TOPDIR)/Rules.make
fs/driverfs/inode.c deleted 100644 → 0
View file @ 60211581
/*
* driverfs.c - The device driver file system
*
* Copyright (c) 2001 Patrick Mochel <mochel@osdl.org>
*
* 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 02111-1307 USA
*
* This is a simple, ram-based filesystem, which allows kernel
* callbacks for read/write of files.
*
* Please see Documentation/filesystems/driverfs.txt for more information.
*/
#include <linux/list.h>
#include <linux/init.h>
#include <linux/pagemap.h>
#include <linux/stat.h>
#include <linux/fs.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/backing-dev.h>
#include <linux/driverfs_fs.h>
#include <asm/uaccess.h>
#undef DEBUG
#ifdef DEBUG
# define DBG(x...) printk(x)
#else
# define DBG(x...)
#endif
/* Random magic number */
#define DRIVERFS_MAGIC 0x42454552
static struct super_operations driverfs_ops;
static struct file_operations driverfs_file_operations;
static struct inode_operations driverfs_dir_inode_operations;
static struct address_space_operations driverfs_aops;
static struct vfsmount *driverfs_mount;
static spinlock_t mount_lock = SPIN_LOCK_UNLOCKED;
static int mount_count = 0;
static struct backing_dev_info driverfs_backing_dev_info = {
.ra_pages = 0, /* No readahead */
.memory_backed = 1, /* Does not contribute to dirty memory */
};
static int driverfs_readpage(struct file *file, struct page * page)
{
if (!PageUptodate(page)) {
void *kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr, 0, PAGE_CACHE_SIZE);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
SetPageUptodate(page);
}
unlock_page(page);
return 0;
}
static int driverfs_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
{
if (!PageUptodate(page)) {
void *kaddr = kmap_atomic(page, KM_USER0);
memset(kaddr, 0, PAGE_CACHE_SIZE);
flush_dcache_page(page);
kunmap_atomic(kaddr, KM_USER0);
SetPageUptodate(page);
}
return 0;
}
static int driverfs_commit_write(struct file *file, struct page *page, unsigned offset, unsigned to)
{
struct inode *inode = page->mapping->host;
loff_t pos = ((loff_t)page->index << PAGE_CACHE_SHIFT) + to;
set_page_dirty(page);
if (pos > inode->i_size)
inode->i_size = pos;
return 0;
}
struct inode *driverfs_get_inode(struct super_block *sb, int mode, int dev)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_mode = mode;
inode->i_uid = current->fsuid;
inode->i_gid = current->fsgid;
inode->i_blksize = PAGE_CACHE_SIZE;
inode->i_blocks = 0;
inode->i_rdev = NODEV;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
inode->i_mapping->a_ops = &driverfs_aops;
inode->i_mapping->backing_dev_info = &driverfs_backing_dev_info;
switch (mode & S_IFMT) {
default:
init_special_inode(inode, mode, dev);
break;
case S_IFREG:
inode->i_fop = &driverfs_file_operations;
break;
case S_IFDIR:
inode->i_op = &driverfs_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
/* directory inodes start off with i_nlink == 2 (for "." entry) */
inode->i_nlink++;
break;
case S_IFLNK:
inode->i_op = &page_symlink_inode_operations;
break;
}
}
return inode;
}
static int driverfs_mknod(struct inode *dir, struct dentry *dentry, int mode, int dev)
{
struct inode *inode;
int error = -ENOSPC;
if (dentry->d_inode)
return -EEXIST;
/* only allow create if ->d_fsdata is not NULL (so we can assume it
* comes from the driverfs API below. */
inode = driverfs_get_inode(dir->i_sb, mode, dev);
if (inode) {
d_instantiate(dentry, inode);
error = 0;
}
return error;
}
static int driverfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
int res;
mode = (mode & (S_IRWXUGO|S_ISVTX)) | S_IFDIR;
res = driverfs_mknod(dir, dentry, mode, 0);
if (!res)
dir->i_nlink++;
return res;
}
static int driverfs_create(struct inode *dir, struct dentry *dentry, int mode)
{
int res;
mode = (mode & S_IALLUGO) | S_IFREG;
res = driverfs_mknod(dir, dentry, mode, 0);
return res;
}
static int driverfs_symlink(struct inode * dir, struct dentry *dentry, const char * symname)
{
struct inode *inode;
int error = -ENOSPC;
if (dentry->d_inode)
return -EEXIST;
inode = driverfs_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
if (inode) {
int l = strlen(symname)+1;
error = page_symlink(inode, symname, l);
if (!error) {
d_instantiate(dentry, inode);
dget(dentry);
} else
iput(inode);
}
return error;
}
static inline int driverfs_positive(struct dentry *dentry)
{
return (dentry->d_inode && !d_unhashed(dentry));
}
static int driverfs_empty(struct dentry *dentry)
{
struct list_head *list;
spin_lock(&dcache_lock);
list_for_each(list, &dentry->d_subdirs) {
struct dentry *de = list_entry(list, struct dentry, d_child);
if (driverfs_positive(de)) {
spin_unlock(&dcache_lock);
return 0;
}
}
spin_unlock(&dcache_lock);
return 1;
}
static int driverfs_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
down(&inode->i_sem);
dentry->d_inode->i_nlink--;
up(&inode->i_sem);
d_invalidate(dentry);
dput(dentry);
return 0;
}
/**
* driverfs_read_file - "read" data from a file.
* @file: file pointer
* @buf: buffer to fill
* @count: number of bytes to read
* @ppos: starting offset in file
*
* Userspace wants data from a file. It is up to the creator of the file to
* provide that data.
* There is a struct device_attribute embedded in file->private_data. We
* obtain that and check if the read callback is implemented. If so, we call
* it, passing the data field of the file entry.
* Said callback is responsible for filling the buffer and returning the number
* of bytes it put in it. We update @ppos correctly.
*/
static ssize_t
driverfs_read_file(struct file *file, char *buf, size_t count, loff_t *ppos)
{
struct attribute * attr = file->f_dentry->d_fsdata;
struct driver_dir_entry * dir;
unsigned char *page;
ssize_t retval = 0;
dir = file->f_dentry->d_parent->d_fsdata;
if (!dir->ops->show)
return 0;
if (count > PAGE_SIZE)
count = PAGE_SIZE;
page = (unsigned char*)__get_free_page(GFP_KERNEL);
if (!page)
return -ENOMEM;
while (count > 0) {
ssize_t len;
len = dir->ops->show(dir,attr,page,count,*ppos);
if (len <= 0) {
if (len < 0)
retval = len;
break;
} else if (len > count)
len = count;
if (copy_to_user(buf,page,len)) {
retval = -EFAULT;
break;
}
*ppos += len;
count -= len;
buf += len;
retval += len;
}
free_page((unsigned long)page);
return retval;
}
/**
* driverfs_write_file - "write" to a file
* @file: file pointer
* @buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Similarly to driverfs_read_file, we act essentially as a bit pipe.
* We check for a "write" callback in file->private_data, and pass
* @buffer, @count, @ppos, and the file entry's data to the callback.
* The number of bytes written is returned, and we handle updating
* @ppos properly.
*/
static ssize_t
driverfs_write_file(struct file *file, const char *buf, size_t count, loff_t *ppos)
{
struct attribute * attr = file->f_dentry->d_fsdata;
struct driver_dir_entry * dir;
ssize_t retval = 0;
char * page;
dir = file->f_dentry->d_parent->d_fsdata;
page = (char *)__get_free_page(GFP_KERNEL);
if (!page)
return -ENOMEM;
if (count >= PAGE_SIZE)
count = PAGE_SIZE - 1;
if (copy_from_user(page,buf,count))
goto done;
*(page + count) = '\0';
while (count > 0) {
ssize_t len;
len = dir->ops->store(dir,attr,page + retval,count,*ppos);
if (len <= 0) {
if (len < 0)
retval = len;
break;
}
retval += len;
count -= len;
*ppos += len;
buf += len;
}
done:
free_page((unsigned long)page);
return retval;
}
static loff_t
driverfs_file_lseek(struct file *file, loff_t offset, int orig)
{
loff_t retval = -EINVAL;
down(&file->f_dentry->d_inode->i_sem);
switch(orig) {
case 0:
if (offset > 0) {
file->f_pos = offset;
retval = file->f_pos;
}
break;
case 1:
if ((offset + file->f_pos) > 0) {
file->f_pos += offset;
retval = file->f_pos;
}
break;
default:
break;
}
up(&file->f_dentry->d_inode->i_sem);
return retval;
}
static int driverfs_open_file(struct inode * inode, struct file * filp)
{
struct driver_dir_entry * dir;
int error = 0;
dir = (struct driver_dir_entry *)filp->f_dentry->d_parent->d_fsdata;
if (dir) {
struct attribute * attr = filp->f_dentry->d_fsdata;
if (attr && dir->ops) {
if (dir->ops->open)
error = dir->ops->open(dir);
goto Done;
}
}
error = -EINVAL;
Done:
return error;
}
static int driverfs_release(struct inode * inode, struct file * filp)
{
struct driver_dir_entry * dir;
dir = (struct driver_dir_entry *)filp->f_dentry->d_parent->d_fsdata;
if (dir->ops->close)
dir->ops->close(dir);
return 0;
}
static struct file_operations driverfs_file_operations = {
.read = driverfs_read_file,
.write = driverfs_write_file,
.llseek = driverfs_file_lseek,
.open = driverfs_open_file,
.release = driverfs_release,
};
static struct inode_operations driverfs_dir_inode_operations = {
.lookup = simple_lookup,
};
static struct address_space_operations driverfs_aops = {
.readpage = driverfs_readpage,
.writepage = fail_writepage,
.prepare_write = driverfs_prepare_write,
.commit_write = driverfs_commit_write
};
static struct super_operations driverfs_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
};
static int driverfs_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 = DRIVERFS_MAGIC;
sb->s_op = &driverfs_ops;
inode = driverfs_get_inode(sb, S_IFDIR | 0755, 0);
if (!inode) {
DBG("%s: could not get inode!\n",__FUNCTION__);
return -ENOMEM;
}
root = d_alloc_root(inode);
if (!root) {
DBG("%s: could not get root dentry!\n",__FUNCTION__);
iput(inode);
return -ENOMEM;
}
sb->s_root = root;
return 0;
}
static struct super_block *driverfs_get_sb(struct file_system_type *fs_type,
int flags, char *dev_name, void *data)
{
return get_sb_single(fs_type, flags, data, driverfs_fill_super);
}
static struct file_system_type driverfs_fs_type = {
.owner = THIS_MODULE,
.name = "driverfs",
.get_sb = driverfs_get_sb,
.kill_sb = kill_litter_super,
};
static int get_mount(void)
{
struct vfsmount * mnt;
spin_lock(&mount_lock);
if (driverfs_mount) {
mntget(driverfs_mount);
++mount_count;
spin_unlock(&mount_lock);
goto go_ahead;
}
spin_unlock(&mount_lock);
mnt = kern_mount(&driverfs_fs_type);
if (IS_ERR(mnt)) {
printk(KERN_ERR "driverfs: could not mount!\n");
return -ENODEV;
}
spin_lock(&mount_lock);
if (!driverfs_mount) {
driverfs_mount = mnt;
++mount_count;
spin_unlock(&mount_lock);
goto go_ahead;
}
mntget(driverfs_mount);
++mount_count;
spin_unlock(&mount_lock);
go_ahead:
DBG("driverfs: mount_count = %d\n",mount_count);
return 0;
}
static void put_mount(void)
{
struct vfsmount * mnt;
spin_lock(&mount_lock);
mnt = driverfs_mount;
--mount_count;
if (!mount_count)
driverfs_mount = NULL;
spin_unlock(&mount_lock);
mntput(mnt);
DBG("driverfs: mount_count = %d\n",mount_count);
}
static int __init driverfs_init(void)
{
return register_filesystem(&driverfs_fs_type);
}
core_initcall(driverfs_init);
static struct dentry * get_dentry(struct dentry * parent, const char * name)
{
struct qstr qstr;
qstr.name = name;
qstr.len = strlen(name);
qstr.hash = full_name_hash(name,qstr.len);
return lookup_hash(&qstr,parent);
}
/**
* driverfs_create_dir - create a directory in the filesystem
* @entry: directory entry
* @parent: parent directory entry
*/
int
driverfs_create_dir(struct driver_dir_entry * entry,
struct driver_dir_entry * parent)
{
struct dentry * dentry = NULL;
struct dentry * parent_dentry;
int error = 0;
if (!entry)
return -EINVAL;
get_mount();
parent_dentry = parent ? parent->dentry : NULL;
if (!parent_dentry)
if (driverfs_mount && driverfs_mount->mnt_sb)
parent_dentry = driverfs_mount->mnt_sb->s_root;
if (!parent_dentry) {
put_mount();
return -EFAULT;
}
down(&parent_dentry->d_inode->i_sem);
dentry = get_dentry(parent_dentry,entry->name);
if (!IS_ERR(dentry)) {
dentry->d_fsdata = (void *) entry;
entry->dentry = dentry;
error = driverfs_mkdir(parent_dentry->d_inode,dentry,entry->mode);
} else
error = PTR_ERR(dentry);
up(&parent_dentry->d_inode->i_sem);
if (error)
put_mount();
return error;
}
/**
* driverfs_create_file - create a file
* @entry: structure describing the file
* @parent: directory to create it in
*/
int
driverfs_create_file(struct attribute * entry,
struct driver_dir_entry * parent)
{
struct dentry * dentry;
int error = 0;
if (!entry || !parent)
return -EINVAL;
if (!parent->dentry) {
put_mount();
return -EINVAL;
}
down(&parent->dentry->d_inode->i_sem);
dentry = get_dentry(parent->dentry,entry->name);
if (!IS_ERR(dentry)) {
dentry->d_fsdata = (void *)entry;
error = driverfs_create(parent->dentry->d_inode,dentry,entry->mode);
} else
error = PTR_ERR(dentry);
up(&parent->dentry->d_inode->i_sem);
return error;
}
/**
* driverfs_create_symlink - make a symlink
* @parent: directory we're creating in
* @entry: entry describing link
* @target: place we're symlinking to
*
*/
int driverfs_create_symlink(struct driver_dir_entry * parent,
char * name, char * target)
{
struct dentry * dentry;
int error = 0;
if (!parent)
return -EINVAL;
if (!parent->dentry) {
put_mount();
return -EINVAL;
}
down(&parent->dentry->d_inode->i_sem);
dentry = get_dentry(parent->dentry,name);
if (!IS_ERR(dentry))
error = driverfs_symlink(parent->dentry->d_inode,dentry,target);
else
error = PTR_ERR(dentry);
up(&parent->dentry->d_inode->i_sem);
return error;
}
/**
* driverfs_remove_file - exported file removal
* @dir: directory the file supposedly resides in
* @name: name of the file
*
* Try and find the file in the dir's list.
* If it's there, call __remove_file() (above) for the dentry.
*/
void driverfs_remove_file(struct driver_dir_entry * dir, const char * name)
{
struct dentry * dentry;
if (!dir->dentry)
return;
down(&dir->dentry->d_inode->i_sem);
dentry = get_dentry(dir->dentry,name);
if (!IS_ERR(dentry)) {
/* make sure dentry is really there */
if (dentry->d_inode &&
(dentry->d_parent->d_inode == dir->dentry->d_inode)) {
driverfs_unlink(dir->dentry->d_inode,dentry);
}
}
up(&dir->dentry->d_inode->i_sem);
}
/**
* driverfs_remove_dir - exportable directory removal
* @dir: directory to remove
*
* To make sure we don't orphan anyone, first remove
* all the children in the list, then do clean up the directory.
*/
void driverfs_remove_dir(struct driver_dir_entry * dir)
{
struct list_head * node, * next;
struct dentry * dentry = dir->dentry;
struct dentry * parent;
if (!dentry)
goto done;
parent = dget(dentry->d_parent);
down(&parent->d_inode->i_sem);
down(&dentry->d_inode->i_sem);
list_for_each_safe(node,next,&dentry->d_subdirs) {
struct dentry * d = list_entry(node,struct dentry,d_child);
/* make sure dentry is still there */
if (d->d_inode)
driverfs_unlink(dentry->d_inode,d);
}
d_invalidate(dentry);
if (driverfs_empty(dentry)) {
dentry->d_inode->i_nlink -= 2;
dentry->d_inode->i_flags |= S_DEAD;
parent->d_inode->i_nlink--;
}
up(&dentry->d_inode->i_sem);
dput(dentry);
up(&parent->d_inode->i_sem);
dput(parent);
done:
put_mount();
}
EXPORT_SYMBOL(driverfs_create_file);
EXPORT_SYMBOL(driverfs_create_symlink);
EXPORT_SYMBOL(driverfs_create_dir);
EXPORT_SYMBOL(driverfs_remove_file);
EXPORT_SYMBOL(driverfs_remove_dir);
MODULE_LICENSE("GPL");
include/linux/driverfs_fs.h deleted 100644 → 0
View file @ 60211581
/*
* driverfs_fs.h - definitions for the device driver filesystem
*
* Copyright (c) 2001 Patrick Mochel <mochel@osdl.org>
*
* 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 02111-1307 USA
*
* This is a simple, ram-based filesystem, which allows kernel
* callbacks for read/write of files.
*
* Please see Documentation/filesystems/driverfs.txt for more information.
*/
#ifndef _DRIVER_FS_H_
#define _DRIVER_FS_H_
#include <linux/sysfs.h>
struct driver_dir_entry;
struct attribute;
struct driverfs_ops {
int (*open)(struct driver_dir_entry *);
int (*close)(struct driver_dir_entry *);
ssize_t (*show)(struct driver_dir_entry *, struct attribute *,char *, size_t, loff_t);
ssize_t (*store)(struct driver_dir_entry *,struct attribute *,const char *, size_t, loff_t);
};
struct driver_dir_entry {
char * name;
struct dentry * dentry;
mode_t mode;
struct driverfs_ops * ops;
};
extern int
driverfs_create_dir(struct driver_dir_entry *, struct driver_dir_entry *);
extern void
driverfs_remove_dir(struct driver_dir_entry * entry);
extern int
driverfs_create_file(struct attribute * attr,
struct driver_dir_entry * parent);
extern int
driverfs_create_symlink(struct driver_dir_entry * parent,
char * name, char * target);
extern void
driverfs_remove_file(struct driver_dir_entry *, const char * name);
#endif /* _DDFS_H_ */
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