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linux/fs/debugfs/file.c
Theodore Ts'o 8e18e2941c [PATCH] inode_diet: Replace inode.u.generic_ip with inode.i_private 
The following patches reduce the size of the VFS inode structure by 28 bytes
on a UP x86.  (It would be more on an x86_64 system).  This is a 10% reduction
in the inode size on a UP kernel that is configured in a production mode
(i.e., with no spinlock or other debugging functions enabled; if you want to
save memory taken up by in-core inodes, the first thing you should do is
disable the debugging options; they are responsible for a huge amount of bloat
in the VFS inode structure).

This patch:

The filesystem or device-specific pointer in the inode is inside a union,
which is pretty pointless given that all 30+ users of this field have been
using the void pointer.  Get rid of the union and rename it to i_private, with
a comment to explain who is allowed to use the void pointer.  This is just a
cleanup, but it allows us to reuse the union 'u' for something something where
the union will actually be used.

[judith@osdl.org: powerpc build fix]
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Judith Lebzelter <judith@osdl.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-27 08:26:17 -07:00

293 lines
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/*
* file.c - part of debugfs, a tiny little debug file system
*
* Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
* Copyright (C) 2004 IBM Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License version
* 2 as published by the Free Software Foundation.
*
* debugfs is for people to use instead of /proc or /sys.
* See Documentation/DocBook/kernel-api for more details.
*
*/
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/debugfs.h>
static ssize_t default_read_file(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
return 0;
}
static ssize_t default_write_file(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
return count;
}
static int default_open(struct inode *inode, struct file *file)
{
if (inode->i_private)
file->private_data = inode->i_private;
return 0;
}
const struct file_operations debugfs_file_operations = {
.read = default_read_file,
.write = default_write_file,
.open = default_open,
};
static void debugfs_u8_set(void *data, u64 val)
{
*(u8 *)data = val;
}
static u64 debugfs_u8_get(void *data)
{
return *(u8 *)data;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
/**
* debugfs_create_u8 - create a debugfs file that is used to read and write an unsigned 8-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_u8(const char *name, mode_t mode,
struct dentry *parent, u8 *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_u8);
}
EXPORT_SYMBOL_GPL(debugfs_create_u8);
static void debugfs_u16_set(void *data, u64 val)
{
*(u16 *)data = val;
}
static u64 debugfs_u16_get(void *data)
{
return *(u16 *)data;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
/**
* debugfs_create_u16 - create a debugfs file that is used to read and write an unsigned 16-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_u16(const char *name, mode_t mode,
struct dentry *parent, u16 *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_u16);
}
EXPORT_SYMBOL_GPL(debugfs_create_u16);
static void debugfs_u32_set(void *data, u64 val)
{
*(u32 *)data = val;
}
static u64 debugfs_u32_get(void *data)
{
return *(u32 *)data;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
/**
* debugfs_create_u32 - create a debugfs file that is used to read and write an unsigned 32-bit value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_u32(const char *name, mode_t mode,
struct dentry *parent, u32 *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_u32);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32);
static ssize_t read_file_bool(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
char buf[3];
u32 *val = file->private_data;
if (*val)
buf[0] = 'Y';
else
buf[0] = 'N';
buf[1] = '\n';
buf[2] = 0x00;
return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}
static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
size_t count, loff_t *ppos)
{
char buf[32];
int buf_size;
u32 *val = file->private_data;
buf_size = min(count, (sizeof(buf)-1));
if (copy_from_user(buf, user_buf, buf_size))
return -EFAULT;
switch (buf[0]) {
case 'y':
case 'Y':
case '1':
*val = 1;
break;
case 'n':
case 'N':
case '0':
*val = 0;
break;
}
return count;
}
static const struct file_operations fops_bool = {
.read = read_file_bool,
.write = write_file_bool,
.open = default_open,
};
/**
* debugfs_create_bool - create a debugfs file that is used to read and write a boolean value
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @value: a pointer to the variable that the file should read to and write
* from.
*
* This function creates a file in debugfs with the given name that
* contains the value of the variable @value. If the @mode variable is so
* set, it can be read from, and written to.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_bool(const char *name, mode_t mode,
struct dentry *parent, u32 *value)
{
return debugfs_create_file(name, mode, parent, value, &fops_bool);
}
EXPORT_SYMBOL_GPL(debugfs_create_bool);
static ssize_t read_file_blob(struct file *file, char __user *user_buf,
size_t count, loff_t *ppos)
{
struct debugfs_blob_wrapper *blob = file->private_data;
return simple_read_from_buffer(user_buf, count, ppos, blob->data,
blob->size);
}
static struct file_operations fops_blob = {
.read = read_file_blob,
.open = default_open,
};
/**
* debugfs_create_blob - create a debugfs file that is used to read and write a binary blob
* @name: a pointer to a string containing the name of the file to create.
* @mode: the permission that the file should have
* @parent: a pointer to the parent dentry for this file. This should be a
* directory dentry if set. If this parameter is %NULL, then the
* file will be created in the root of the debugfs filesystem.
* @blob: a pointer to a struct debugfs_blob_wrapper which contains a pointer
* to the blob data and the size of the data.
*
* This function creates a file in debugfs with the given name that exports
* @blob->data as a binary blob. If the @mode variable is so set it can be
* read from. Writing is not supported.
*
* This function will return a pointer to a dentry if it succeeds. This
* pointer must be passed to the debugfs_remove() function when the file is
* to be removed (no automatic cleanup happens if your module is unloaded,
* you are responsible here.) If an error occurs, %NULL will be returned.
*
* If debugfs is not enabled in the kernel, the value -%ENODEV will be
* returned. It is not wise to check for this value, but rather, check for
* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
* code.
*/
struct dentry *debugfs_create_blob(const char *name, mode_t mode,
struct dentry *parent,
struct debugfs_blob_wrapper *blob)
{
return debugfs_create_file(name, mode, parent, blob, &fops_blob);
}
EXPORT_SYMBOL_GPL(debugfs_create_blob);
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