linux/drivers/oprofile/oprofilefs.c
David Howells c6a2c720d2 vfs: Convert oprofilefs to use the new mount API
Convert the oprofilefs filesystem to the new internal mount API as the old
one will be obsoleted and removed.  This allows greater flexibility in
communication of mount parameters between userspace, the VFS and the
filesystem.

See Documentation/filesystems/mount_api.txt for more information.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Robert Richter <rric@kernel.org>
cc: oprofile-list@lists.sf.net
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2019-07-04 22:01:59 -04:00

301 lines
6.6 KiB
C

/**
* @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/fs_context.h>
#include <linux/pagemap.h>
#include <linux/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(inode);
}
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 dentry *root, char const *name,
const struct file_operations *fops, int perm, void *priv)
{
struct dentry *dentry;
struct inode *inode;
if (!root)
return -ENOMEM;
inode_lock(d_inode(root));
dentry = d_alloc_name(root, name);
if (!dentry) {
inode_unlock(d_inode(root));
return -ENOMEM;
}
inode = oprofilefs_get_inode(root->d_sb, S_IFREG | perm);
if (!inode) {
dput(dentry);
inode_unlock(d_inode(root));
return -ENOMEM;
}
inode->i_fop = fops;
inode->i_private = priv;
d_add(dentry, inode);
inode_unlock(d_inode(root));
return 0;
}
int oprofilefs_create_ulong(struct dentry *root,
char const *name, unsigned long *val)
{
return __oprofilefs_create_file(root, name,
&ulong_fops, 0644, val);
}
int oprofilefs_create_ro_ulong(struct dentry *root,
char const *name, unsigned long *val)
{
return __oprofilefs_create_file(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 dentry *root,
char const *name, atomic_t *val)
{
return __oprofilefs_create_file(root, name,
&atomic_ro_fops, 0444, val);
}
int oprofilefs_create_file(struct dentry *root,
char const *name, const struct file_operations *fops)
{
return __oprofilefs_create_file(root, name, fops, 0644, NULL);
}
int oprofilefs_create_file_perm(struct dentry *root,
char const *name, const struct file_operations *fops, int perm)
{
return __oprofilefs_create_file(root, name, fops, perm, NULL);
}
struct dentry *oprofilefs_mkdir(struct dentry *parent, char const *name)
{
struct dentry *dentry;
struct inode *inode;
inode_lock(d_inode(parent));
dentry = d_alloc_name(parent, name);
if (!dentry) {
inode_unlock(d_inode(parent));
return NULL;
}
inode = oprofilefs_get_inode(parent->d_sb, S_IFDIR | 0755);
if (!inode) {
dput(dentry);
inode_unlock(d_inode(parent));
return NULL;
}
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
d_add(dentry, inode);
inode_unlock(d_inode(parent));
return dentry;
}
static int oprofilefs_fill_super(struct super_block *sb, struct fs_context *fc)
{
struct inode *root_inode;
sb->s_blocksize = PAGE_SIZE;
sb->s_blocksize_bits = PAGE_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->s_root);
// FIXME: verify kill_litter_super removes our dentries
return 0;
}
static int oprofilefs_get_tree(struct fs_context *fc)
{
return get_tree_single(fc, oprofilefs_fill_super);
}
static const struct fs_context_operations oprofilefs_context_ops = {
.get_tree = oprofilefs_get_tree,
};
static int oprofilefs_init_fs_context(struct fs_context *fc)
{
fc->ops = &oprofilefs_context_ops;
return 0;
}
static struct file_system_type oprofilefs_type = {
.owner = THIS_MODULE,
.name = "oprofilefs",
.init_fs_context = oprofilefs_init_fs_context,
.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);
}