/*
 * fs/sysfs/bin.c - sysfs binary file implementation
 *
 * Copyright (c) 2003 Patrick Mochel
 * Copyright (c) 2003 Matthew Wilcox
 * Copyright (c) 2004 Silicon Graphics, Inc.
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
 *
 * This file is released under the GPLv2.
 *
 * Please see Documentation/filesystems/sysfs.txt for more information.
 */

#undef DEBUG

#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/mm.h>

#include <asm/uaccess.h>

#include "sysfs.h"

/*
 * There's one bin_buffer for each open file.
 *
 * filp->private_data points to bin_buffer and
 * sysfs_dirent->s_bin_attr.buffers points to a the bin_buffer s
 * sysfs_dirent->s_bin_attr.buffers is protected by sysfs_bin_lock
 */
static DEFINE_MUTEX(sysfs_bin_lock);

struct bin_buffer {
        struct mutex                    mutex;
        void                            *buffer;
        int                             mmapped;
        const struct vm_operations_struct *vm_ops;
        struct file                     *file;
        struct hlist_node               list;
};

static int
fill_read(struct file *file, char *buffer, loff_t off, size_t count)
{
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
        int rc;

        /* need attr_sd for attr, its parent for kobj */
        if (!sysfs_get_active(attr_sd))
                return -ENODEV;

        rc = -EIO;
        if (attr->read)
                rc = attr->read(file, kobj, attr, buffer, off, count);

        sysfs_put_active(attr_sd);

        return rc;
}

static ssize_t
read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
{
        struct bin_buffer *bb = file->private_data;
        int size = file->f_path.dentry->d_inode->i_size;
        loff_t offs = *off;
        int count = min_t(size_t, bytes, PAGE_SIZE);
        char *temp;

        if (!bytes)
                return 0;

        if (size) {
                if (offs > size)
                        return 0;
                if (offs + count > size)
                        count = size - offs;
        }

        temp = kmalloc(count, GFP_KERNEL);
        if (!temp)
                return -ENOMEM;

        mutex_lock(&bb->mutex);

        count = fill_read(file, bb->buffer, offs, count);
        if (count < 0) {
                mutex_unlock(&bb->mutex);
                goto out_free;
        }

        memcpy(temp, bb->buffer, count);

        mutex_unlock(&bb->mutex);

        if (copy_to_user(userbuf, temp, count)) {
                count = -EFAULT;
                goto out_free;
        }

        pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);

        *off = offs + count;

 out_free:
        kfree(temp);
        return count;
}

static int
flush_write(struct file *file, char *buffer, loff_t offset, size_t count)
{
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
        int rc;

        /* need attr_sd for attr, its parent for kobj */
        if (!sysfs_get_active(attr_sd))
                return -ENODEV;

        rc = -EIO;
        if (attr->write)
                rc = attr->write(file, kobj, attr, buffer, offset, count);

        sysfs_put_active(attr_sd);

        return rc;
}

static ssize_t write(struct file *file, const char __user *userbuf,
                     size_t bytes, loff_t *off)
{
        struct bin_buffer *bb = file->private_data;
        int size = file->f_path.dentry->d_inode->i_size;
        loff_t offs = *off;
        int count = min_t(size_t, bytes, PAGE_SIZE);
        char *temp;

        if (!bytes)
                return 0;

        if (size) {
                if (offs > size)
                        return 0;
                if (offs + count > size)
                        count = size - offs;
        }

        temp = memdup_user(userbuf, count);
        if (IS_ERR(temp))
                return PTR_ERR(temp);

        mutex_lock(&bb->mutex);

        memcpy(bb->buffer, temp, count);

        count = flush_write(file, bb->buffer, offs, count);
        mutex_unlock(&bb->mutex);

        if (count > 0)
                *off = offs + count;

        kfree(temp);
        return count;
}

static void bin_vma_open(struct vm_area_struct *vma)
{
        struct file *file = vma->vm_file;
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;

        if (!bb->vm_ops)
                return;

        if (!sysfs_get_active(attr_sd))
                return;

        if (bb->vm_ops->open)
                bb->vm_ops->open(vma);

        sysfs_put_active(attr_sd);
}

static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct file *file = vma->vm_file;
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        int ret;

        if (!bb->vm_ops)
                return VM_FAULT_SIGBUS;

        if (!sysfs_get_active(attr_sd))
                return VM_FAULT_SIGBUS;

        ret = VM_FAULT_SIGBUS;
        if (bb->vm_ops->fault)
                ret = bb->vm_ops->fault(vma, vmf);

        sysfs_put_active(attr_sd);
        return ret;
}

static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
{
        struct file *file = vma->vm_file;
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        int ret;

        if (!bb->vm_ops)
                return VM_FAULT_SIGBUS;

        if (!sysfs_get_active(attr_sd))
                return VM_FAULT_SIGBUS;

        ret = 0;
        if (bb->vm_ops->page_mkwrite)
                ret = bb->vm_ops->page_mkwrite(vma, vmf);

        sysfs_put_active(attr_sd);
        return ret;
}

static int bin_access(struct vm_area_struct *vma, unsigned long addr,
                  void *buf, int len, int write)
{
        struct file *file = vma->vm_file;
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        int ret;

        if (!bb->vm_ops)
                return -EINVAL;

        if (!sysfs_get_active(attr_sd))
                return -EINVAL;

        ret = -EINVAL;
        if (bb->vm_ops->access)
                ret = bb->vm_ops->access(vma, addr, buf, len, write);

        sysfs_put_active(attr_sd);
        return ret;
}

#ifdef CONFIG_NUMA
static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
{
        struct file *file = vma->vm_file;
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        int ret;

        if (!bb->vm_ops)
                return 0;

        if (!sysfs_get_active(attr_sd))
                return -EINVAL;

        ret = 0;
        if (bb->vm_ops->set_policy)
                ret = bb->vm_ops->set_policy(vma, new);

        sysfs_put_active(attr_sd);
        return ret;
}

static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
                                        unsigned long addr)
{
        struct file *file = vma->vm_file;
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct mempolicy *pol;

        if (!bb->vm_ops)
                return vma->vm_policy;

        if (!sysfs_get_active(attr_sd))
                return vma->vm_policy;

        pol = vma->vm_policy;
        if (bb->vm_ops->get_policy)
                pol = bb->vm_ops->get_policy(vma, addr);

        sysfs_put_active(attr_sd);
        return pol;
}

static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
                        const nodemask_t *to, unsigned long flags)
{
        struct file *file = vma->vm_file;
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        int ret;

        if (!bb->vm_ops)
                return 0;

        if (!sysfs_get_active(attr_sd))
                return 0;

        ret = 0;
        if (bb->vm_ops->migrate)
                ret = bb->vm_ops->migrate(vma, from, to, flags);

        sysfs_put_active(attr_sd);
        return ret;
}
#endif

static const struct vm_operations_struct bin_vm_ops = {
        .open           = bin_vma_open,
        .fault          = bin_fault,
        .page_mkwrite   = bin_page_mkwrite,
        .access         = bin_access,
#ifdef CONFIG_NUMA
        .set_policy     = bin_set_policy,
        .get_policy     = bin_get_policy,
        .migrate        = bin_migrate,
#endif
};

static int mmap(struct file *file, struct vm_area_struct *vma)
{
        struct bin_buffer *bb = file->private_data;
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
        int rc;

        mutex_lock(&bb->mutex);

        /* need attr_sd for attr, its parent for kobj */
        rc = -ENODEV;
        if (!sysfs_get_active(attr_sd))
                goto out_unlock;

        rc = -EINVAL;
        if (!attr->mmap)
                goto out_put;

        rc = attr->mmap(file, kobj, attr, vma);
        if (rc)
                goto out_put;

        /*
         * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
         * to satisfy versions of X which crash if the mmap fails: that
         * substitutes a new vm_file, and we don't then want bin_vm_ops.
         */
        if (vma->vm_file != file)
                goto out_put;

        rc = -EINVAL;
        if (bb->mmapped && bb->vm_ops != vma->vm_ops)
                goto out_put;

        /*
         * It is not possible to successfully wrap close.
         * So error if someone is trying to use close.
         */
        rc = -EINVAL;
        if (vma->vm_ops && vma->vm_ops->close)
                goto out_put;

        rc = 0;
        bb->mmapped = 1;
        bb->vm_ops = vma->vm_ops;
        vma->vm_ops = &bin_vm_ops;
out_put:
        sysfs_put_active(attr_sd);
out_unlock:
        mutex_unlock(&bb->mutex);

        return rc;
}

static int open(struct inode * inode, struct file * file)
{
        struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
        struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
        struct bin_buffer *bb = NULL;
        int error;

        /* binary file operations requires both @sd and its parent */
        if (!sysfs_get_active(attr_sd))
                return -ENODEV;

        error = -EACCES;
        if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
                goto err_out;
        if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
                goto err_out;

        error = -ENOMEM;
        bb = kzalloc(sizeof(*bb), GFP_KERNEL);
        if (!bb)
                goto err_out;

        bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!bb->buffer)
                goto err_out;

        mutex_init(&bb->mutex);
        bb->file = file;
        file->private_data = bb;

        mutex_lock(&sysfs_bin_lock);
        hlist_add_head(&bb->list, &attr_sd->s_bin_attr.buffers);
        mutex_unlock(&sysfs_bin_lock);

        /* open succeeded, put active references */
        sysfs_put_active(attr_sd);
        return 0;

 err_out:
        sysfs_put_active(attr_sd);
        kfree(bb);
        return error;
}

static int release(struct inode * inode, struct file * file)
{
        struct bin_buffer *bb = file->private_data;

        mutex_lock(&sysfs_bin_lock);
        hlist_del(&bb->list);
        mutex_unlock(&sysfs_bin_lock);

        kfree(bb->buffer);
        kfree(bb);
        return 0;
}

const struct file_operations bin_fops = {
        .read           = read,
        .write          = write,
        .mmap           = mmap,
        .llseek         = generic_file_llseek,
        .open           = open,
        .release        = release,
};


void unmap_bin_file(struct sysfs_dirent *attr_sd)
{
        struct bin_buffer *bb;
        struct hlist_node *tmp;

        if (sysfs_type(attr_sd) != SYSFS_KOBJ_BIN_ATTR)
                return;

        mutex_lock(&sysfs_bin_lock);

        hlist_for_each_entry(bb, tmp, &attr_sd->s_bin_attr.buffers, list) {
                struct inode *inode = bb->file->f_path.dentry->d_inode;

                unmap_mapping_range(inode->i_mapping, 0, 0, 1);
        }

        mutex_unlock(&sysfs_bin_lock);
}

/**
 *      sysfs_create_bin_file - create binary file for object.
 *      @kobj:  object.
 *      @attr:  attribute descriptor.
 */

int sysfs_create_bin_file(struct kobject *kobj,
                          const struct bin_attribute *attr)
{
        BUG_ON(!kobj || !kobj->sd || !attr);

        return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
}


/**
 *      sysfs_remove_bin_file - remove binary file for object.
 *      @kobj:  object.
 *      @attr:  attribute descriptor.
 */

void sysfs_remove_bin_file(struct kobject *kobj,
                           const struct bin_attribute *attr)
{
        sysfs_hash_and_remove(kobj->sd, NULL, attr->attr.name);
}

EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);