linux/drivers/oprofile/oprofilefs.c
Deepa Dinamani 078cd8279e fs: Replace CURRENT_TIME with current_time() for inode timestamps
CURRENT_TIME macro is not appropriate for filesystems as it
doesn't use the right granularity for filesystem timestamps.
Use current_time() instead.

CURRENT_TIME is also not y2038 safe.

This is also in preparation for the patch that transitions
vfs timestamps to use 64 bit time and hence make them
y2038 safe. As part of the effort current_time() will be
extended to do range checks. Hence, it is necessary for all
file system timestamps to use current_time(). Also,
current_time() will be transitioned along with vfs to be
y2038 safe.

Note that whenever a single call to current_time() is used
to change timestamps in different inodes, it is because they
share the same time granularity.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Felipe Balbi <balbi@kernel.org>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: David Sterba <dsterba@suse.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2016-09-27 21:06:21 -04:00

290 lines
6.4 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/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(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;
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, void *data, int silent)
{
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 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);
}