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linux/arch/s390/hypfs/inode.c
Arnd Bergmann 6038f373a3 llseek: automatically add .llseek fop
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time.  Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
//   but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
 ...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
 .llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
 .read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
 .write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
 .open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
...  .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
...  .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
...  .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+	.llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
 .write = write_f,
 .read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
2010-10-15 15:53:27 +02:00

524 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;
struct dentry *hypfs_dbfs_dir;
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 int hypfs_get_super(struct file_system_type *fst, int flags,
const char *devname, void *data, struct vfsmount *mnt)
{
return get_sb_single(fst, flags, data, hypfs_fill_super, mnt);
}
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",
.get_sb = hypfs_get_super,
.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;
hypfs_dbfs_dir = debugfs_create_dir("s390_hypfs", NULL);
if (IS_ERR(hypfs_dbfs_dir))
return PTR_ERR(hypfs_dbfs_dir);
if (hypfs_diag_init()) {
rc = -ENODATA;
goto fail_debugfs_remove;
}
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_debugfs_remove:
debugfs_remove(hypfs_dbfs_dir);
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();
debugfs_remove(hypfs_dbfs_dir);
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");