linux/arch/s390/hypfs/inode.c
Michael Holzheu 2fcb3686e1 [S390] hypfs: Move buffer allocation from open to read
Currently the buffer for diagnose data is allocated in the open function
of the debugfs file and is released in the close function. This has the
drawback that a user (root) can pin that memory by not closing the file.
This patch moves the buffer allocation to the read function. The buffer is
automatically released after the buffer is copied to userspace.

Signed-off-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2011-01-05 12:47:27 +01:00

520 lines
12 KiB
C

/*
* arch/s390/hypfs/inode.c
* 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 <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 super_block *sb,
struct dentry *dir);
struct hypfs_sb_info {
uid_t uid; /* uid used for files and dirs */
gid_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 = sb_info->update_file->d_inode;
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 inline int hypfs_positive(struct dentry *dentry)
{
return dentry->d_inode && !d_unhashed(dentry);
}
static void hypfs_remove(struct dentry *dentry)
{
struct dentry *parent;
parent = dentry->d_parent;
if (!parent || !parent->d_inode)
return;
mutex_lock(&parent->d_inode->i_mutex);
if (hypfs_positive(dentry)) {
if (S_ISDIR(dentry->d_inode->i_mode))
simple_rmdir(parent->d_inode, dentry);
else
simple_unlink(parent->d_inode, dentry);
}
d_delete(dentry);
dput(dentry);
mutex_unlock(&parent->d_inode->i_mutex);
}
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, int mode)
{
struct inode *ret = new_inode(sb);
if (ret) {
struct hypfs_sb_info *hypfs_info = sb->s_fs_info;
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 (mode & S_IFDIR)
ret->i_nlink = 2;
else
ret->i_nlink = 1;
}
return ret;
}
static void hypfs_evict_inode(struct inode *inode)
{
end_writeback(inode);
kfree(inode->i_private);
}
static int hypfs_open(struct inode *inode, struct file *filp)
{
char *data = filp->f_path.dentry->d_inode->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_aio_read(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t offset)
{
char *data;
ssize_t ret;
struct file *filp = iocb->ki_filp;
/* XXX: temporary */
char __user *buf = iov[0].iov_base;
size_t count = iov[0].iov_len;
if (nr_segs != 1)
return -EINVAL;
data = filp->private_data;
ret = simple_read_from_buffer(buf, count, &offset, data, strlen(data));
if (ret <= 0)
return ret;
iocb->ki_pos += ret;
file_accessed(filp);
return ret;
}
static ssize_t hypfs_aio_write(struct kiocb *iocb, const struct iovec *iov,
unsigned long nr_segs, loff_t offset)
{
int rc;
struct super_block *sb;
struct hypfs_sb_info *fs_info;
size_t count = iov_length(iov, nr_segs);
sb = iocb->ki_filp->f_path.dentry->d_inode->i_sb;
fs_info = sb->s_fs_info;
/*
* 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, sb->s_root);
else
rc = hypfs_diag_create_files(sb, 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;
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];
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;
hypfs_info->uid = option;
break;
case opt_gid:
if (match_int(&args[0], &option))
return -EINVAL;
hypfs_info->gid = option;
break;
case opt_err:
default:
pr_err("%s is not a valid mount option\n", str);
return -EINVAL;
}
}
return 0;
}
static int hypfs_show_options(struct seq_file *s, struct vfsmount *mnt)
{
struct hypfs_sb_info *hypfs_info = mnt->mnt_sb->s_fs_info;
seq_printf(s, ",uid=%u", hypfs_info->uid);
seq_printf(s, ",gid=%u", hypfs_info->gid);
return 0;
}
static int hypfs_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *root_inode;
struct dentry *root_dentry;
int rc = 0;
struct hypfs_sb_info *sbi;
sbi = kzalloc(sizeof(struct hypfs_sb_info), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
mutex_init(&sbi->lock);
sbi->uid = current_uid();
sbi->gid = current_gid();
sb->s_fs_info = sbi;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = HYPFS_MAGIC;
sb->s_op = &hypfs_s_ops;
if (hypfs_parse_options(data, sb))
return -EINVAL;
root_inode = hypfs_make_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 = root_dentry = d_alloc_root(root_inode);
if (!root_dentry) {
iput(root_inode);
return -ENOMEM;
}
if (MACHINE_IS_VM)
rc = hypfs_vm_create_files(sb, root_dentry);
else
rc = hypfs_diag_create_files(sb, root_dentry);
if (rc)
return rc;
sbi->update_file = hypfs_create_update_file(sb, root_dentry);
if (IS_ERR(sbi->update_file))
return PTR_ERR(sbi->update_file);
hypfs_update_update(sb);
pr_info("Hypervisor filesystem mounted\n");
return 0;
}
static struct dentry *hypfs_mount(struct file_system_type *fst, int flags,
const char *devname, void *data)
{
return mount_single(fst, flags, data, hypfs_fill_super);
}
static void hypfs_kill_super(struct super_block *sb)
{
struct hypfs_sb_info *sb_info = sb->s_fs_info;
if (sb->s_root)
hypfs_delete_tree(sb->s_root);
if (sb_info->update_file)
hypfs_remove(sb_info->update_file);
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
kill_litter_super(sb);
}
static struct dentry *hypfs_create_file(struct super_block *sb,
struct dentry *parent, const char *name,
char *data, mode_t mode)
{
struct dentry *dentry;
struct inode *inode;
mutex_lock(&parent->d_inode->i_mutex);
dentry = lookup_one_len(name, parent, strlen(name));
if (IS_ERR(dentry)) {
dentry = ERR_PTR(-ENOMEM);
goto fail;
}
inode = hypfs_make_inode(sb, mode);
if (!inode) {
dput(dentry);
dentry = ERR_PTR(-ENOMEM);
goto fail;
}
if (mode & S_IFREG) {
inode->i_fop = &hypfs_file_ops;
if (data)
inode->i_size = strlen(data);
else
inode->i_size = 0;
} else if (mode & S_IFDIR) {
inode->i_op = &simple_dir_inode_operations;
inode->i_fop = &simple_dir_operations;
parent->d_inode->i_nlink++;
} else
BUG();
inode->i_private = data;
d_instantiate(dentry, inode);
dget(dentry);
fail:
mutex_unlock(&parent->d_inode->i_mutex);
return dentry;
}
struct dentry *hypfs_mkdir(struct super_block *sb, struct dentry *parent,
const char *name)
{
struct dentry *dentry;
dentry = hypfs_create_file(sb, parent, name, NULL, S_IFDIR | DIR_MODE);
if (IS_ERR(dentry))
return dentry;
hypfs_add_dentry(dentry);
return dentry;
}
static struct dentry *hypfs_create_update_file(struct super_block *sb,
struct dentry *dir)
{
struct dentry *dentry;
dentry = hypfs_create_file(sb, dir, "update", NULL,
S_IFREG | UPDATE_FILE_MODE);
/*
* We do not put the update file on the 'delete' list with
* hypfs_add_dentry(), since it should not be removed when the tree
* is updated.
*/
return dentry;
}
struct dentry *hypfs_create_u64(struct super_block *sb, struct dentry *dir,
const char *name, __u64 value)
{
char *buffer;
char tmp[TMP_SIZE];
struct dentry *dentry;
snprintf(tmp, TMP_SIZE, "%llu\n", (unsigned long long int)value);
buffer = kstrdup(tmp, GFP_KERNEL);
if (!buffer)
return ERR_PTR(-ENOMEM);
dentry =
hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
if (IS_ERR(dentry)) {
kfree(buffer);
return ERR_PTR(-ENOMEM);
}
hypfs_add_dentry(dentry);
return dentry;
}
struct dentry *hypfs_create_str(struct super_block *sb, struct dentry *dir,
const char *name, char *string)
{
char *buffer;
struct dentry *dentry;
buffer = kmalloc(strlen(string) + 2, GFP_KERNEL);
if (!buffer)
return ERR_PTR(-ENOMEM);
sprintf(buffer, "%s\n", string);
dentry =
hypfs_create_file(sb, dir, name, buffer, S_IFREG | REG_FILE_MODE);
if (IS_ERR(dentry)) {
kfree(buffer);
return ERR_PTR(-ENOMEM);
}
hypfs_add_dentry(dentry);
return dentry;
}
static const struct file_operations hypfs_file_ops = {
.open = hypfs_open,
.release = hypfs_release,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = hypfs_aio_read,
.aio_write = hypfs_aio_write,
.llseek = no_llseek,
};
static struct file_system_type hypfs_type = {
.owner = THIS_MODULE,
.name = "s390_hypfs",
.mount = hypfs_mount,
.kill_sb = hypfs_kill_super
};
static const struct super_operations hypfs_s_ops = {
.statfs = simple_statfs,
.evict_inode = hypfs_evict_inode,
.show_options = hypfs_show_options,
};
static struct kobject *s390_kobj;
static int __init hypfs_init(void)
{
int rc;
rc = hypfs_dbfs_init();
if (rc)
return rc;
if (hypfs_diag_init()) {
rc = -ENODATA;
goto fail_dbfs_exit;
}
if (hypfs_vm_init()) {
rc = -ENODATA;
goto fail_hypfs_diag_exit;
}
s390_kobj = kobject_create_and_add("s390", hypervisor_kobj);
if (!s390_kobj) {
rc = -ENOMEM;
goto fail_hypfs_vm_exit;
}
rc = register_filesystem(&hypfs_type);
if (rc)
goto fail_filesystem;
return 0;
fail_filesystem:
kobject_put(s390_kobj);
fail_hypfs_vm_exit:
hypfs_vm_exit();
fail_hypfs_diag_exit:
hypfs_diag_exit();
fail_dbfs_exit:
hypfs_dbfs_exit();
pr_err("Initialization of hypfs failed with rc=%i\n", rc);
return rc;
}
static void __exit hypfs_exit(void)
{
hypfs_diag_exit();
hypfs_vm_exit();
hypfs_dbfs_exit();
unregister_filesystem(&hypfs_type);
kobject_put(s390_kobj);
}
module_init(hypfs_init)
module_exit(hypfs_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michael Holzheu <holzheu@de.ibm.com>");
MODULE_DESCRIPTION("s390 Hypervisor Filesystem");