fs/sysfs/bin.c

   1 /*
   2  * bin.c - binary file operations for sysfs.
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Matthew Wilcox
   6  * Copyright (c) 2004 Silicon Graphics, Inc.
   7  */
   8
   9 #undef DEBUG
  10
  11 #include <linux/errno.h>
  12 #include <linux/fs.h>
  13 #include <linux/kernel.h>
  14 #include <linux/kobject.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17
  18 #include <asm/uaccess.h>
  19 #include <asm/semaphore.h>
  20
  21 #include "sysfs.h"
  22
  23 struct bin_buffer {
  24         struct mutex    mutex;
  25         void            *buffer;
  26 };
  27
  28 static int
  29 fill_read(struct dentry *dentry, char *buffer, loff_t off, size_t count)
  30 {
  31         struct sysfs_dirent *attr_sd = dentry->d_fsdata;
  32         struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
  33         struct kobject * kobj = to_kobj(dentry->d_parent);
  34
  35         if (!attr->read)
  36                 return -EIO;
  37
  38         return attr->read(kobj, buffer, off, count);
  39 }
  40
  41 static ssize_t
  42 read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
  43 {
  44         struct bin_buffer *bb = file->private_data;
  45         struct dentry *dentry = file->f_path.dentry;
  46         int size = dentry->d_inode->i_size;
  47         loff_t offs = *off;
  48         int count = min_t(size_t, bytes, PAGE_SIZE);
  49
  50         if (size) {
  51                 if (offs > size)
  52                         return 0;
  53                 if (offs + count > size)
  54                         count = size - offs;
  55         }
  56
  57         mutex_lock(&bb->mutex);
  58
  59         count = fill_read(dentry, bb->buffer, offs, count);
  60         if (count < 0)
  61                 goto out_unlock;
  62
  63         if (copy_to_user(userbuf, bb->buffer, count)) {
  64                 count = -EFAULT;
  65                 goto out_unlock;
  66         }
  67
  68         pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
  69
  70         *off = offs + count;
  71
  72  out_unlock:
  73         mutex_unlock(&bb->mutex);
  74         return count;
  75 }
  76
  77 static int
  78 flush_write(struct dentry *dentry, char *buffer, loff_t offset, size_t count)
  79 {
  80         struct sysfs_dirent *attr_sd = dentry->d_fsdata;
  81         struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
  82         struct kobject *kobj = to_kobj(dentry->d_parent);
  83
  84         if (!attr->write)
  85                 return -EIO;
  86
  87         return attr->write(kobj, buffer, offset, count);
  88 }
  89
  90 static ssize_t write(struct file *file, const char __user *userbuf,
  91                      size_t bytes, loff_t *off)
  92 {
  93         struct bin_buffer *bb = file->private_data;
  94         struct dentry *dentry = file->f_path.dentry;
  95         int size = dentry->d_inode->i_size;
  96         loff_t offs = *off;
  97         int count = min_t(size_t, bytes, PAGE_SIZE);
  98
  99         if (size) {
 100                 if (offs > size)
 101                         return 0;
 102                 if (offs + count > size)
 103                         count = size - offs;
 104         }
 105
 106         mutex_lock(&bb->mutex);
 107
 108         if (copy_from_user(bb->buffer, userbuf, count)) {
 109                 count = -EFAULT;
 110                 goto out_unlock;
 111         }
 112
 113         count = flush_write(dentry, bb->buffer, offs, count);
 114         if (count > 0)
 115                 *off = offs + count;
 116
 117  out_unlock:
 118         mutex_unlock(&bb->mutex);
 119         return count;
 120 }
 121
 122 static int mmap(struct file *file, struct vm_area_struct *vma)
 123 {
 124         struct bin_buffer *bb = file->private_data;
 125         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 126         struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
 127         struct kobject *kobj = to_kobj(file->f_path.dentry->d_parent);
 128         int rc;
 129
 130         if (!attr->mmap)
 131                 return -EINVAL;
 132
 133         mutex_lock(&bb->mutex);
 134         rc = attr->mmap(kobj, attr, vma);
 135         mutex_unlock(&bb->mutex);
 136
 137         return rc;
 138 }
 139
 140 static int open(struct inode * inode, struct file * file)
 141 {
 142         struct kobject *kobj = sysfs_get_kobject(file->f_path.dentry->d_parent);
 143         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 144         struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
 145         struct bin_buffer *bb = NULL;
 146         int error = -EINVAL;
 147
 148         if (!kobj || !attr)
 149                 goto Done;
 150
 151         /* Grab the module reference for this attribute if we have one */
 152         error = -ENODEV;
 153         if (!try_module_get(attr->attr.owner))
 154                 goto Done;
 155
 156         error = -EACCES;
 157         if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 158                 goto Error;
 159         if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
 160                 goto Error;
 161
 162         error = -ENOMEM;
 163         bb = kzalloc(sizeof(*bb), GFP_KERNEL);
 164         if (!bb)
 165                 goto Error;
 166
 167         bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 168         if (!bb->buffer)
 169                 goto Error;
 170
 171         mutex_init(&bb->mutex);
 172         file->private_data = bb;
 173
 174         error = 0;
 175         goto Done;
 176
 177  Error:
 178         kfree(bb);
 179         module_put(attr->attr.owner);
 180  Done:
 181         if (error)
 182                 kobject_put(kobj);
 183         return error;
 184 }
 185
 186 static int release(struct inode * inode, struct file * file)
 187 {
 188         struct kobject * kobj = to_kobj(file->f_path.dentry->d_parent);
 189         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 190         struct bin_attribute *attr = attr_sd->s_elem.bin_attr.bin_attr;
 191         struct bin_buffer *bb = file->private_data;
 192
 193         kobject_put(kobj);
 194         module_put(attr->attr.owner);
 195         kfree(bb->buffer);
 196         kfree(bb);
 197         return 0;
 198 }
 199
 200 const struct file_operations bin_fops = {
 201         .read           = read,
 202         .write          = write,
 203         .mmap           = mmap,
 204         .llseek         = generic_file_llseek,
 205         .open           = open,
 206         .release        = release,
 207 };
 208
 209 /**
 210  *      sysfs_create_bin_file - create binary file for object.
 211  *      @kobj:  object.
 212  *      @attr:  attribute descriptor.
 213  */
 214
 215 int sysfs_create_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 216 {
 217         BUG_ON(!kobj || !kobj->dentry || !attr);
 218
 219         return sysfs_add_file(kobj->dentry, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
 220 }
 221
 222
 223 /**
 224  *      sysfs_remove_bin_file - remove binary file for object.
 225  *      @kobj:  object.
 226  *      @attr:  attribute descriptor.
 227  */
 228
 229 void sysfs_remove_bin_file(struct kobject * kobj, struct bin_attribute * attr)
 230 {
 231         if (sysfs_hash_and_remove(kobj->dentry, attr->attr.name) < 0) {
 232                 printk(KERN_ERR "%s: "
 233                         "bad dentry or inode or no such file: \"%s\"\n",
 234                         __FUNCTION__, attr->attr.name);
 235                 dump_stack();
 236         }
 237 }
 238
 239 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 240 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);