original development tree for Linux kernel GTP module; now long in mainline.
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/**
* @file oprofilefs.c
*
* @remark Copyright 2002 OProfile authors
* @remark Read the file COPYING
*
* @author John Levon
*
* A simple filesystem for configuration and
* access of oprofile.
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/oprofile.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <asm/uaccess.h>
#include "oprof.h"
#define OPROFILEFS_MAGIC 0x6f70726f
DEFINE_RAW_SPINLOCK(oprofilefs_lock);
static struct inode *oprofilefs_get_inode(struct super_block *sb, int mode)
{
struct inode *inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode->i_mode = mode;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
}
return inode;
}
static const struct super_operations s_ops = {
.statfs = simple_statfs,
.drop_inode = generic_delete_inode,
};
ssize_t oprofilefs_str_to_user(char const *str, char __user *buf, size_t count, loff_t *offset)
{
return simple_read_from_buffer(buf, count, offset, str, strlen(str));
}
#define TMPBUFSIZE 50
ssize_t oprofilefs_ulong_to_user(unsigned long val, char __user *buf, size_t count, loff_t *offset)
{
char tmpbuf[TMPBUFSIZE];
size_t maxlen = snprintf(tmpbuf, TMPBUFSIZE, "%lu\n", val);
if (maxlen > TMPBUFSIZE)
maxlen = TMPBUFSIZE;
return simple_read_from_buffer(buf, count, offset, tmpbuf, maxlen);
}
/*
* Note: If oprofilefs_ulong_from_user() returns 0, then *val remains
* unchanged and might be uninitialized. This follows write syscall
* implementation when count is zero: "If count is zero ... [and if]
* no errors are detected, 0 will be returned without causing any
* other effect." (man 2 write)
*/
int oprofilefs_ulong_from_user(unsigned long *val, char const __user *buf, size_t count)
{
char tmpbuf[TMPBUFSIZE];
unsigned long flags;
if (!count)
return 0;
if (count > TMPBUFSIZE - 1)
return -EINVAL;
memset(tmpbuf, 0x0, TMPBUFSIZE);
if (copy_from_user(tmpbuf, buf, count))
return -EFAULT;
raw_spin_lock_irqsave(&oprofilefs_lock, flags);
*val = simple_strtoul(tmpbuf, NULL, 0);
raw_spin_unlock_irqrestore(&oprofilefs_lock, flags);
return count;
}
static ssize_t ulong_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
unsigned long *val = file->private_data;
return oprofilefs_ulong_to_user(*val, buf, count, offset);
}
static ssize_t ulong_write_file(struct file *file, char const __user *buf, size_t count, loff_t *offset)
{
unsigned long value;
int retval;
if (*offset)
return -EINVAL;
retval = oprofilefs_ulong_from_user(&value, buf, count);
if (retval <= 0)
return retval;
retval = oprofile_set_ulong(file->private_data, value);
if (retval)
return retval;
return count;
}
static const struct file_operations ulong_fops = {
.read = ulong_read_file,
.write = ulong_write_file,
.open = simple_open,
.llseek = default_llseek,
};
static const struct file_operations ulong_ro_fops = {
.read = ulong_read_file,
.open = simple_open,
.llseek = default_llseek,
};
static int __oprofilefs_create_file(struct super_block *sb,
struct dentry *root, char const *name, const struct file_operations *fops,
int perm, void *priv)
{
struct dentry *dentry;
struct inode *inode;
mutex_lock(&root->d_inode->i_mutex);
dentry = d_alloc_name(root, name);
if (!dentry) {
mutex_unlock(&root->d_inode->i_mutex);
return -ENOMEM;
}
inode = oprofilefs_get_inode(sb, S_IFREG | perm);
if (!inode) {
dput(dentry);
mutex_unlock(&root->d_inode->i_mutex);
return -ENOMEM;
}
inode->i_fop = fops;
inode->i_private = priv;
d_add(dentry, inode);
mutex_unlock(&root->d_inode->i_mutex);
return 0;
}
int oprofilefs_create_ulong(struct super_block *sb, struct dentry *root,
char const *name, unsigned long *val)
{
return __oprofilefs_create_file(sb, root, name,
&ulong_fops, 0644, val);
}
int oprofilefs_create_ro_ulong(struct super_block *sb, struct dentry *root,
char const *name, unsigned long *val)
{
return __oprofilefs_create_file(sb, root, name,
&ulong_ro_fops, 0444, val);
}
static ssize_t atomic_read_file(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
atomic_t *val = file->private_data;
return oprofilefs_ulong_to_user(atomic_read(val), buf, count, offset);
}
static const struct file_operations atomic_ro_fops = {
.read = atomic_read_file,
.open = simple_open,
.llseek = default_llseek,
};
int oprofilefs_create_ro_atomic(struct super_block *sb, struct dentry *root,
char const *name, atomic_t *val)
{
return __oprofilefs_create_file(sb, root, name,
&atomic_ro_fops, 0444, val);
}
int oprofilefs_create_file(struct super_block *sb, struct dentry *root,
char const *name, const struct file_operations *fops)
{
return __oprofilefs_create_file(sb, root, name, fops, 0644, NULL);
}
int oprofilefs_create_file_perm(struct super_block *sb, struct dentry *root,
char const *name, const struct file_operations *fops, int perm)
{
return __oprofilefs_create_file(sb, root, name, fops, perm, NULL);
}
struct dentry *oprofilefs_mkdir(struct super_block *sb,
struct dentry *root, char const *name)
{
struct dentry *dentry;
struct inode *inode;
mutex_lock(&root->d_inode->i_mutex);
dentry = d_alloc_name(root, name);
if (!dentry) {
mutex_unlock(&root->d_inode->i_mutex);
return NULL;
}
inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
if (!inode) {
dput(dentry);
mutex_unlock(&root->d_inode->i_mutex);
return NULL;
}
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
d_add(dentry, inode);
mutex_unlock(&root->d_inode->i_mutex);
return dentry;
}
static int oprofilefs_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *root_inode;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = OPROFILEFS_MAGIC;
sb->s_op = &s_ops;
sb->s_time_gran = 1;
root_inode = oprofilefs_get_inode(sb, S_IFDIR | 0755);
if (!root_inode)
return -ENOMEM;
root_inode->i_op = &simple_dir_inode_operations;
root_inode->i_fop = &simple_dir_operations;
sb->s_root = d_make_root(root_inode);
if (!sb->s_root)
return -ENOMEM;
oprofile_create_files(sb, sb->s_root);
// FIXME: verify kill_litter_super removes our dentries
return 0;
}
static struct dentry *oprofilefs_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return mount_single(fs_type, flags, data, oprofilefs_fill_super);
}
static struct file_system_type oprofilefs_type = {
.owner = THIS_MODULE,
.name = "oprofilefs",
.mount = oprofilefs_mount,
.kill_sb = kill_litter_super,
};
MODULE_ALIAS_FS("oprofilefs");
int __init oprofilefs_register(void)
{
return register_filesystem(&oprofilefs_type);
}
void __exit oprofilefs_unregister(void)
{
unregister_filesystem(&oprofilefs_type);
}