android_kernel_xiaomi_sm8350/fs/configfs/file.c
Arjan van de Ven 4b6f5d20b0 [PATCH] Make most file operations structs in fs/ const
This is a conversion to make the various file_operations structs in fs/
const.  Basically a regexp job, with a few manual fixups

The goal is both to increase correctness (harder to accidentally write to
shared datastructures) and reducing the false sharing of cachelines with
things that get dirty in .data (while .rodata is nicely read only and thus
cache clean)

Signed-off-by: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-28 09:16:06 -08:00

362 lines
9.6 KiB
C

/* -*- mode: c; c-basic-offset: 8; -*-
* vim: noexpandtab sw=8 ts=8 sts=0:
*
* file.c - operations for regular (text) files.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public
* License along with this program; if not, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*
* Based on sysfs:
* sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
*
* configfs Copyright (C) 2005 Oracle. All rights reserved.
*/
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <asm/uaccess.h>
#include <asm/semaphore.h>
#include <linux/configfs.h>
#include "configfs_internal.h"
struct configfs_buffer {
size_t count;
loff_t pos;
char * page;
struct configfs_item_operations * ops;
struct semaphore sem;
int needs_read_fill;
};
/**
* fill_read_buffer - allocate and fill buffer from item.
* @dentry: dentry pointer.
* @buffer: data buffer for file.
*
* Allocate @buffer->page, if it hasn't been already, then call the
* config_item's show() method to fill the buffer with this attribute's
* data.
* This is called only once, on the file's first read.
*/
static int fill_read_buffer(struct dentry * dentry, struct configfs_buffer * buffer)
{
struct configfs_attribute * attr = to_attr(dentry);
struct config_item * item = to_item(dentry->d_parent);
struct configfs_item_operations * ops = buffer->ops;
int ret = 0;
ssize_t count;
if (!buffer->page)
buffer->page = (char *) get_zeroed_page(GFP_KERNEL);
if (!buffer->page)
return -ENOMEM;
count = ops->show_attribute(item,attr,buffer->page);
buffer->needs_read_fill = 0;
BUG_ON(count > (ssize_t)PAGE_SIZE);
if (count >= 0)
buffer->count = count;
else
ret = count;
return ret;
}
/**
* flush_read_buffer - push buffer to userspace.
* @buffer: data buffer for file.
* @userbuf: user-passed buffer.
* @count: number of bytes requested.
* @ppos: file position.
*
* Copy the buffer we filled in fill_read_buffer() to userspace.
* This is done at the reader's leisure, copying and advancing
* the amount they specify each time.
* This may be called continuously until the buffer is empty.
*/
static int flush_read_buffer(struct configfs_buffer * buffer, char __user * buf,
size_t count, loff_t * ppos)
{
int error;
if (*ppos > buffer->count)
return 0;
if (count > (buffer->count - *ppos))
count = buffer->count - *ppos;
error = copy_to_user(buf,buffer->page + *ppos,count);
if (!error)
*ppos += count;
return error ? -EFAULT : count;
}
/**
* configfs_read_file - read an attribute.
* @file: file pointer.
* @buf: buffer to fill.
* @count: number of bytes to read.
* @ppos: starting offset in file.
*
* Userspace wants to read an attribute file. The attribute descriptor
* is in the file's ->d_fsdata. The target item is in the directory's
* ->d_fsdata.
*
* We call fill_read_buffer() to allocate and fill the buffer from the
* item's show() method exactly once (if the read is happening from
* the beginning of the file). That should fill the entire buffer with
* all the data the item has to offer for that attribute.
* We then call flush_read_buffer() to copy the buffer to userspace
* in the increments specified.
*/
static ssize_t
configfs_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos)
{
struct configfs_buffer * buffer = file->private_data;
ssize_t retval = 0;
down(&buffer->sem);
if (buffer->needs_read_fill) {
if ((retval = fill_read_buffer(file->f_dentry,buffer)))
goto out;
}
pr_debug("%s: count = %d, ppos = %lld, buf = %s\n",
__FUNCTION__,count,*ppos,buffer->page);
retval = flush_read_buffer(buffer,buf,count,ppos);
out:
up(&buffer->sem);
return retval;
}
/**
* fill_write_buffer - copy buffer from userspace.
* @buffer: data buffer for file.
* @buf: data from user.
* @count: number of bytes in @userbuf.
*
* Allocate @buffer->page if it hasn't been already, then
* copy the user-supplied buffer into it.
*/
static int
fill_write_buffer(struct configfs_buffer * buffer, const char __user * buf, size_t count)
{
int error;
if (!buffer->page)
buffer->page = (char *)get_zeroed_page(GFP_KERNEL);
if (!buffer->page)
return -ENOMEM;
if (count > PAGE_SIZE)
count = PAGE_SIZE;
error = copy_from_user(buffer->page,buf,count);
buffer->needs_read_fill = 1;
return error ? -EFAULT : count;
}
/**
* flush_write_buffer - push buffer to config_item.
* @dentry: dentry to the attribute
* @buffer: data buffer for file.
* @count: number of bytes
*
* Get the correct pointers for the config_item and the attribute we're
* dealing with, then call the store() method for the attribute,
* passing the buffer that we acquired in fill_write_buffer().
*/
static int
flush_write_buffer(struct dentry * dentry, struct configfs_buffer * buffer, size_t count)
{
struct configfs_attribute * attr = to_attr(dentry);
struct config_item * item = to_item(dentry->d_parent);
struct configfs_item_operations * ops = buffer->ops;
return ops->store_attribute(item,attr,buffer->page,count);
}
/**
* configfs_write_file - write an attribute.
* @file: file pointer
* @buf: data to write
* @count: number of bytes
* @ppos: starting offset
*
* Similar to configfs_read_file(), though working in the opposite direction.
* We allocate and fill the data from the user in fill_write_buffer(),
* then push it to the config_item in flush_write_buffer().
* There is no easy way for us to know if userspace is only doing a partial
* write, so we don't support them. We expect the entire buffer to come
* on the first write.
* Hint: if you're writing a value, first read the file, modify only the
* the value you're changing, then write entire buffer back.
*/
static ssize_t
configfs_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
struct configfs_buffer * buffer = file->private_data;
ssize_t len;
down(&buffer->sem);
len = fill_write_buffer(buffer, buf, count);
if (len > 0)
len = flush_write_buffer(file->f_dentry, buffer, count);
if (len > 0)
*ppos += len;
up(&buffer->sem);
return len;
}
static int check_perm(struct inode * inode, struct file * file)
{
struct config_item *item = configfs_get_config_item(file->f_dentry->d_parent);
struct configfs_attribute * attr = to_attr(file->f_dentry);
struct configfs_buffer * buffer;
struct configfs_item_operations * ops = NULL;
int error = 0;
if (!item || !attr)
goto Einval;
/* Grab the module reference for this attribute if we have one */
if (!try_module_get(attr->ca_owner)) {
error = -ENODEV;
goto Done;
}
if (item->ci_type)
ops = item->ci_type->ct_item_ops;
else
goto Eaccess;
/* File needs write support.
* The inode's perms must say it's ok,
* and we must have a store method.
*/
if (file->f_mode & FMODE_WRITE) {
if (!(inode->i_mode & S_IWUGO) || !ops->store_attribute)
goto Eaccess;
}
/* File needs read support.
* The inode's perms must say it's ok, and we there
* must be a show method for it.
*/
if (file->f_mode & FMODE_READ) {
if (!(inode->i_mode & S_IRUGO) || !ops->show_attribute)
goto Eaccess;
}
/* No error? Great, allocate a buffer for the file, and store it
* it in file->private_data for easy access.
*/
buffer = kmalloc(sizeof(struct configfs_buffer),GFP_KERNEL);
if (buffer) {
memset(buffer,0,sizeof(struct configfs_buffer));
init_MUTEX(&buffer->sem);
buffer->needs_read_fill = 1;
buffer->ops = ops;
file->private_data = buffer;
} else
error = -ENOMEM;
goto Done;
Einval:
error = -EINVAL;
goto Done;
Eaccess:
error = -EACCES;
module_put(attr->ca_owner);
Done:
if (error && item)
config_item_put(item);
return error;
}
static int configfs_open_file(struct inode * inode, struct file * filp)
{
return check_perm(inode,filp);
}
static int configfs_release(struct inode * inode, struct file * filp)
{
struct config_item * item = to_item(filp->f_dentry->d_parent);
struct configfs_attribute * attr = to_attr(filp->f_dentry);
struct module * owner = attr->ca_owner;
struct configfs_buffer * buffer = filp->private_data;
if (item)
config_item_put(item);
/* After this point, attr should not be accessed. */
module_put(owner);
if (buffer) {
if (buffer->page)
free_page((unsigned long)buffer->page);
kfree(buffer);
}
return 0;
}
const struct file_operations configfs_file_operations = {
.read = configfs_read_file,
.write = configfs_write_file,
.llseek = generic_file_llseek,
.open = configfs_open_file,
.release = configfs_release,
};
int configfs_add_file(struct dentry * dir, const struct configfs_attribute * attr, int type)
{
struct configfs_dirent * parent_sd = dir->d_fsdata;
umode_t mode = (attr->ca_mode & S_IALLUGO) | S_IFREG;
int error = 0;
mutex_lock(&dir->d_inode->i_mutex);
error = configfs_make_dirent(parent_sd, NULL, (void *) attr, mode, type);
mutex_unlock(&dir->d_inode->i_mutex);
return error;
}
/**
* configfs_create_file - create an attribute file for an item.
* @item: item we're creating for.
* @attr: atrribute descriptor.
*/
int configfs_create_file(struct config_item * item, const struct configfs_attribute * attr)
{
BUG_ON(!item || !item->ci_dentry || !attr);
return configfs_add_file(item->ci_dentry, attr,
CONFIGFS_ITEM_ATTR);
}