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/*
* Hypervisor filesystem for Linux on s390.
*
* Copyright IBM Corp. 2006, 2008
* Author(s): Michael Holzheu <holzheu@de.ibm.com>
*/
#define KMSG_COMPONENT "hypfs"
#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/vfs.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/time.h>
#include <linux/parser.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/uio.h>
#include <asm/ebcdic.h>
#include "hypfs.h"
#define HYPFS_MAGIC 0x687970 /* ASCII 'hyp' */
#define TMP_SIZE 64 /* size of temporary buffers */
static struct dentry *hypfs_create_update_file(struct dentry *dir);
struct hypfs_sb_info {
kuid_t uid; /* uid used for files and dirs */
kgid_t gid; /* gid used for files and dirs */
struct dentry *update_file; /* file to trigger update */
time_t last_update; /* last update time in secs since 1970 */
struct mutex lock; /* lock to protect update process */
};
static const struct file_operations hypfs_file_ops;
static struct file_system_type hypfs_type;
static const struct super_operations hypfs_s_ops;
/* start of list of all dentries, which have to be deleted on update */
static struct dentry *hypfs_last_dentry;
static void hypfs_update_update(struct super_block *sb)
{
struct hypfs_sb_info *sb_info = sb->s_fs_info;
struct inode *inode = d_inode(sb_info->update_file);
sb_info->last_update = get_seconds();
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
}
/* directory tree removal functions */
static void hypfs_add_dentry(struct dentry *dentry)
{
dentry->d_fsdata = hypfs_last_dentry;
hypfs_last_dentry = dentry;
}
static void hypfs_remove(struct dentry *dentry)
{
struct dentry *parent;
parent = dentry->d_parent;
inode_lock(d_inode(parent));
if (simple_positive(dentry)) {
if (d_is_dir(dentry))
simple_rmdir(d_inode(parent), dentry);
else
simple_unlink(d_inode(parent), dentry);
}
d_delete(dentry);
dput(dentry);
inode_unlock(d_inode(parent));
}
static void hypfs_delete_tree(struct dentry *root)
{
while (hypfs_last_dentry) {
struct dentry *next_dentry;
next_dentry = hypfs_last_dentry->d_fsdata;
hypfs_remove(hypfs_last_dentry);
hypfs_last_dentry = next_dentry;
}
}
static struct inode *hypfs_make_inode(struct super_block *sb, umode_t mode)
{
struct inode *ret = new_inode(sb);
if (ret) {
struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
ret->i_ino = get_next_ino();
ret->i_mode = mode;
ret->i_uid = hypfs_info->uid;
ret->i_gid = hypfs_info->gid;
ret->i_atime = ret->i_mtime = ret->i_ctime = CURRENT_TIME;
if (S_ISDIR(mode))
set_nlink(ret, 2);
}
return ret;
}
static void hypfs_evict_inode(struct inode *inode)
{
clear_inode(inode);
kfree(inode->i_private);
}
static int hypfs_open(struct inode *inode, struct file *filp)
{
char *data = file_inode(filp)->i_private;
struct hypfs_sb_info *fs_info;
if (filp->f_mode & FMODE_WRITE) {
if (!(inode->i_mode & S_IWUGO))
return -EACCES;
}
if (filp->f_mode & FMODE_READ) {
if (!(inode->i_mode & S_IRUGO))
return -EACCES;
}
fs_info = inode->i_sb->s_fs_info;
if(data) {
mutex_lock(&fs_info->lock);
filp->private_data = kstrdup(data, GFP_KERNEL);
if (!filp->private_data) {
mutex_unlock(&fs_info->lock);
return -ENOMEM;
}
mutex_unlock(&fs_info->lock);
}
return nonseekable_open(inode, filp);
}
static ssize_t hypfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
char *data = file->private_data;
size_t available = strlen(data);
loff_t pos = iocb->ki_pos;
size_t count;
if (pos < 0)
return -EINVAL;
if (pos >= available || !iov_iter_count(to))
return 0;
count = copy_to_iter(data + pos, available - pos, to);
if (!count)
return -EFAULT;
iocb->ki_pos = pos + count;
file_accessed(file);
return count;
}
static ssize_t hypfs_write_iter(struct kiocb *iocb, struct iov_iter *from)
{
int rc;
struct super_block *sb = file_inode(iocb->ki_filp)->i_sb;
struct hypfs_sb_info *fs_info = sb->s_fs_info;
size_t count = iov_iter_count(from);
/*
* Currently we only allow one update per second for two reasons:
* 1. diag 204 is VERY expensive
* 2. If several processes do updates in parallel and then read the
* hypfs data, the likelihood of collisions is reduced, if we restrict
* the minimum update interval. A collision occurs, if during the
* data gathering of one process another process triggers an update
* If the first process wants to ensure consistent data, it has
* to restart data collection in this case.
*/
mutex_lock(&fs_info->lock);
if (fs_info->last_update == get_seconds()) {
rc = -EBUSY;
goto out;
}
hypfs_delete_tree(sb->s_root);
if (MACHINE_IS_VM)
rc = hypfs_vm_create_files(sb->s_root);
else
rc = hypfs_diag_create_files(sb->s_root);
if (rc) {
pr_err("Updating the hypfs tree failed\n");
hypfs_delete_tree(sb->s_root);
goto out;
}
hypfs_update_update(sb);
rc = count;
iov_iter_advance(from, count);
out:
mutex_unlock(&fs_info->lock);
return rc;
}
static int hypfs_release(struct inode *inode, struct file *filp)
{
kfree(filp->private_data);
return 0;
}
enum { opt_uid, opt_gid, opt_err };
static const match_table_t hypfs_tokens = {
{opt_uid, "uid=%u"},
{opt_gid, "gid=%u"},
{opt_err, NULL}
};
static int hypfs_parse_options(char *options, struct super_block *sb)
{
char *str;
substring_t args[MAX_OPT_ARGS];
kuid_t uid;
kgid_t gid;
if (!options)
return 0;
while ((str = strsep(&options, ",")) != NULL) {
int token, option;
struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
if (!*str)
continue;
token = match_token(str, hypfs_tokens, args);
switch (token) {
case opt_uid:
if (match_int(&args[0], &option))
return -EINVAL;
uid =
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