bin.c

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/*
 * 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 <[email protected]>
 *
 * 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);
    else
        file_update_time(file);

    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);
}

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);
}


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);