linux/fs/fuse/control.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

355 lines
7.9 KiB
C

/*
FUSE: Filesystem in Userspace
Copyright (C) 2001-2008 Miklos Szeredi <miklos@szeredi.hu>
This program can be distributed under the terms of the GNU GPL.
See the file COPYING.
*/
#include "fuse_i.h"
#include <linux/init.h>
#include <linux/module.h>
#define FUSE_CTL_SUPER_MAGIC 0x65735543
/*
* This is non-NULL when the single instance of the control filesystem
* exists. Protected by fuse_mutex
*/
static struct super_block *fuse_control_sb;
static struct fuse_conn *fuse_ctl_file_conn_get(struct file *file)
{
struct fuse_conn *fc;
mutex_lock(&fuse_mutex);
fc = file_inode(file)->i_private;
if (fc)
fc = fuse_conn_get(fc);
mutex_unlock(&fuse_mutex);
return fc;
}
static ssize_t fuse_conn_abort_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
if (fc) {
fuse_abort_conn(fc);
fuse_conn_put(fc);
}
return count;
}
static ssize_t fuse_conn_waiting_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos)
{
char tmp[32];
size_t size;
if (!*ppos) {
long value;
struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
if (!fc)
return 0;
value = atomic_read(&fc->num_waiting);
file->private_data = (void *)value;
fuse_conn_put(fc);
}
size = sprintf(tmp, "%ld\n", (long)file->private_data);
return simple_read_from_buffer(buf, len, ppos, tmp, size);
}
static ssize_t fuse_conn_limit_read(struct file *file, char __user *buf,
size_t len, loff_t *ppos, unsigned val)
{
char tmp[32];
size_t size = sprintf(tmp, "%u\n", val);
return simple_read_from_buffer(buf, len, ppos, tmp, size);
}
static ssize_t fuse_conn_limit_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos, unsigned *val,
unsigned global_limit)
{
unsigned long t;
unsigned limit = (1 << 16) - 1;
int err;
if (*ppos)
return -EINVAL;
err = kstrtoul_from_user(buf, count, 0, &t);
if (err)
return err;
if (!capable(CAP_SYS_ADMIN))
limit = min(limit, global_limit);
if (t > limit)
return -EINVAL;
*val = t;
return count;
}
static ssize_t fuse_conn_max_background_read(struct file *file,
char __user *buf, size_t len,
loff_t *ppos)
{
struct fuse_conn *fc;
unsigned val;
fc = fuse_ctl_file_conn_get(file);
if (!fc)
return 0;
val = fc->max_background;
fuse_conn_put(fc);
return fuse_conn_limit_read(file, buf, len, ppos, val);
}
static ssize_t fuse_conn_max_background_write(struct file *file,
const char __user *buf,
size_t count, loff_t *ppos)
{
unsigned uninitialized_var(val);
ssize_t ret;
ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
max_user_bgreq);
if (ret > 0) {
struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
if (fc) {
fc->max_background = val;
fuse_conn_put(fc);
}
}
return ret;
}
static ssize_t fuse_conn_congestion_threshold_read(struct file *file,
char __user *buf, size_t len,
loff_t *ppos)
{
struct fuse_conn *fc;
unsigned val;
fc = fuse_ctl_file_conn_get(file);
if (!fc)
return 0;
val = fc->congestion_threshold;
fuse_conn_put(fc);
return fuse_conn_limit_read(file, buf, len, ppos, val);
}
static ssize_t fuse_conn_congestion_threshold_write(struct file *file,
const char __user *buf,
size_t count, loff_t *ppos)
{
unsigned uninitialized_var(val);
ssize_t ret;
ret = fuse_conn_limit_write(file, buf, count, ppos, &val,
max_user_congthresh);
if (ret > 0) {
struct fuse_conn *fc = fuse_ctl_file_conn_get(file);
if (fc) {
fc->congestion_threshold = val;
fuse_conn_put(fc);
}
}
return ret;
}
static const struct file_operations fuse_ctl_abort_ops = {
.open = nonseekable_open,
.write = fuse_conn_abort_write,
.llseek = no_llseek,
};
static const struct file_operations fuse_ctl_waiting_ops = {
.open = nonseekable_open,
.read = fuse_conn_waiting_read,
.llseek = no_llseek,
};
static const struct file_operations fuse_conn_max_background_ops = {
.open = nonseekable_open,
.read = fuse_conn_max_background_read,
.write = fuse_conn_max_background_write,
.llseek = no_llseek,
};
static const struct file_operations fuse_conn_congestion_threshold_ops = {
.open = nonseekable_open,
.read = fuse_conn_congestion_threshold_read,
.write = fuse_conn_congestion_threshold_write,
.llseek = no_llseek,
};
static struct dentry *fuse_ctl_add_dentry(struct dentry *parent,
struct fuse_conn *fc,
const char *name,
int mode, int nlink,
const struct inode_operations *iop,
const struct file_operations *fop)
{
struct dentry *dentry;
struct inode *inode;
BUG_ON(fc->ctl_ndents >= FUSE_CTL_NUM_DENTRIES);
dentry = d_alloc_name(parent, name);
if (!dentry)
return NULL;
fc->ctl_dentry[fc->ctl_ndents++] = dentry;
inode = new_inode(fuse_control_sb);
if (!inode)
return NULL;
inode->i_ino = get_next_ino();
inode->i_mode = mode;
inode->i_uid = fc->user_id;
inode->i_gid = fc->group_id;
inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
/* setting ->i_op to NULL is not allowed */
if (iop)
inode->i_op = iop;
inode->i_fop = fop;
set_nlink(inode, nlink);
inode->i_private = fc;
d_add(dentry, inode);
return dentry;
}
/*
* Add a connection to the control filesystem (if it exists). Caller
* must hold fuse_mutex
*/
int fuse_ctl_add_conn(struct fuse_conn *fc)
{
struct dentry *parent;
char name[32];
if (!fuse_control_sb)
return 0;
parent = fuse_control_sb->s_root;
inc_nlink(d_inode(parent));
sprintf(name, "%u", fc->dev);
parent = fuse_ctl_add_dentry(parent, fc, name, S_IFDIR | 0500, 2,
&simple_dir_inode_operations,
&simple_dir_operations);
if (!parent)
goto err;
if (!fuse_ctl_add_dentry(parent, fc, "waiting", S_IFREG | 0400, 1,
NULL, &fuse_ctl_waiting_ops) ||
!fuse_ctl_add_dentry(parent, fc, "abort", S_IFREG | 0200, 1,
NULL, &fuse_ctl_abort_ops) ||
!fuse_ctl_add_dentry(parent, fc, "max_background", S_IFREG | 0600,
1, NULL, &fuse_conn_max_background_ops) ||
!fuse_ctl_add_dentry(parent, fc, "congestion_threshold",
S_IFREG | 0600, 1, NULL,
&fuse_conn_congestion_threshold_ops))
goto err;
return 0;
err:
fuse_ctl_remove_conn(fc);
return -ENOMEM;
}
/*
* Remove a connection from the control filesystem (if it exists).
* Caller must hold fuse_mutex
*/
void fuse_ctl_remove_conn(struct fuse_conn *fc)
{
int i;
if (!fuse_control_sb)
return;
for (i = fc->ctl_ndents - 1; i >= 0; i--) {
struct dentry *dentry = fc->ctl_dentry[i];
d_inode(dentry)->i_private = NULL;
d_drop(dentry);
dput(dentry);
}
drop_nlink(d_inode(fuse_control_sb->s_root));
}
static int fuse_ctl_fill_super(struct super_block *sb, void *data, int silent)
{
struct tree_descr empty_descr = {""};
struct fuse_conn *fc;
int err;
err = simple_fill_super(sb, FUSE_CTL_SUPER_MAGIC, &empty_descr);
if (err)
return err;
mutex_lock(&fuse_mutex);
BUG_ON(fuse_control_sb);
fuse_control_sb = sb;
list_for_each_entry(fc, &fuse_conn_list, entry) {
err = fuse_ctl_add_conn(fc);
if (err) {
fuse_control_sb = NULL;
mutex_unlock(&fuse_mutex);
return err;
}
}
mutex_unlock(&fuse_mutex);
return 0;
}
static struct dentry *fuse_ctl_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *raw_data)
{
return mount_single(fs_type, flags, raw_data, fuse_ctl_fill_super);
}
static void fuse_ctl_kill_sb(struct super_block *sb)
{
struct fuse_conn *fc;
mutex_lock(&fuse_mutex);
fuse_control_sb = NULL;
list_for_each_entry(fc, &fuse_conn_list, entry)
fc->ctl_ndents = 0;
mutex_unlock(&fuse_mutex);
kill_litter_super(sb);
}
static struct file_system_type fuse_ctl_fs_type = {
.owner = THIS_MODULE,
.name = "fusectl",
.mount = fuse_ctl_mount,
.kill_sb = fuse_ctl_kill_sb,
};
MODULE_ALIAS_FS("fusectl");
int __init fuse_ctl_init(void)
{
return register_filesystem(&fuse_ctl_fs_type);
}
void __exit fuse_ctl_cleanup(void)
{
unregister_filesystem(&fuse_ctl_fs_type);
}