fs/sysfs/bin.c

   1 /*
   2  * fs/sysfs/bin.c - sysfs binary file implementation
   3  *
   4  * Copyright (c) 2003 Patrick Mochel
   5  * Copyright (c) 2003 Matthew Wilcox
   6  * Copyright (c) 2004 Silicon Graphics, Inc.
   7  * Copyright (c) 2007 SUSE Linux Products GmbH
   8  * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
   9  *
  10  * This file is released under the GPLv2.
  11  *
  12  * Please see Documentation/filesystems/sysfs.txt for more information.
  13  */
  14
  15 #undef DEBUG
  16
  17 #include <linux/errno.h>
  18 #include <linux/fs.h>
  19 #include <linux/kernel.h>
  20 #include <linux/kobject.h>
  21 #include <linux/module.h>
  22 #include <linux/slab.h>
  23 #include <linux/mutex.h>
  24 #include <linux/mm.h>
  25
  26 #include <asm/uaccess.h>
  27
  28 #include "sysfs.h"
  29
  30 /*
  31  * There's one bin_buffer for each open file.
  32  *
  33  * filp->private_data points to bin_buffer and
  34  * sysfs_dirent->s_bin_attr.buffers points to a the bin_buffer s
  35  * sysfs_dirent->s_bin_attr.buffers is protected by sysfs_bin_lock
  36  */
  37 static DEFINE_MUTEX(sysfs_bin_lock);
  38
  39 struct bin_buffer {
  40         struct mutex                    mutex;
  41         void                            *buffer;
  42         int                             mmapped;
  43         const struct vm_operations_struct *vm_ops;
  44         struct file                     *file;
  45         struct hlist_node               list;
  46 };
  47
  48 static int
  49 fill_read(struct file *file, char *buffer, loff_t off, size_t count)
  50 {
  51         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
  52         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
  53         struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
  54         int rc;
  55
  56         /* need attr_sd for attr, its parent for kobj */
  57         if (!sysfs_get_active(attr_sd))
  58                 return -ENODEV;
  59
  60         rc = -EIO;
  61         if (attr->read)
  62                 rc = attr->read(file, kobj, attr, buffer, off, count);
  63
  64         sysfs_put_active(attr_sd);
  65
  66         return rc;
  67 }
  68
  69 static ssize_t
  70 read(struct file *file, char __user *userbuf, size_t bytes, loff_t *off)
  71 {
  72         struct bin_buffer *bb = file->private_data;
  73         int size = file->f_path.dentry->d_inode->i_size;
  74         loff_t offs = *off;
  75         int count = min_t(size_t, bytes, PAGE_SIZE);
  76         char *temp;
  77
  78         if (!bytes)
  79                 return 0;
  80
  81         if (size) {
  82                 if (offs > size)
  83                         return 0;
  84                 if (offs + count > size)
  85                         count = size - offs;
  86         }
  87
  88         temp = kmalloc(count, GFP_KERNEL);
  89         if (!temp)
  90                 return -ENOMEM;
  91
  92         mutex_lock(&bb->mutex);
  93
  94         count = fill_read(file, bb->buffer, offs, count);
  95         if (count < 0) {
  96                 mutex_unlock(&bb->mutex);
  97                 goto out_free;
  98         }
  99
 100         memcpy(temp, bb->buffer, count);
 101
 102         mutex_unlock(&bb->mutex);
 103
 104         if (copy_to_user(userbuf, temp, count)) {
 105                 count = -EFAULT;
 106                 goto out_free;
 107         }
 108
 109         pr_debug("offs = %lld, *off = %lld, count = %d\n", offs, *off, count);
 110
 111         *off = offs + count;
 112
 113  out_free:
 114         kfree(temp);
 115         return count;
 116 }
 117
 118 static int
 119 flush_write(struct file *file, char *buffer, loff_t offset, size_t count)
 120 {
 121         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 122         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 123         struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
 124         int rc;
 125
 126         /* need attr_sd for attr, its parent for kobj */
 127         if (!sysfs_get_active(attr_sd))
 128                 return -ENODEV;
 129
 130         rc = -EIO;
 131         if (attr->write)
 132                 rc = attr->write(file, kobj, attr, buffer, offset, count);
 133
 134         sysfs_put_active(attr_sd);
 135
 136         return rc;
 137 }
 138
 139 static ssize_t write(struct file *file, const char __user *userbuf,
 140                      size_t bytes, loff_t *off)
 141 {
 142         struct bin_buffer *bb = file->private_data;
 143         int size = file->f_path.dentry->d_inode->i_size;
 144         loff_t offs = *off;
 145         int count = min_t(size_t, bytes, PAGE_SIZE);
 146         char *temp;
 147
 148         if (!bytes)
 149                 return 0;
 150
 151         if (size) {
 152                 if (offs > size)
 153                         return 0;
 154                 if (offs + count > size)
 155                         count = size - offs;
 156         }
 157
 158         temp = memdup_user(userbuf, count);
 159         if (IS_ERR(temp))
 160                 return PTR_ERR(temp);
 161
 162         mutex_lock(&bb->mutex);
 163
 164         memcpy(bb->buffer, temp, count);
 165
 166         count = flush_write(file, bb->buffer, offs, count);
 167         mutex_unlock(&bb->mutex);
 168
 169         if (count > 0)
 170                 *off = offs + count;
 171
 172         kfree(temp);
 173         return count;
 174 }
 175
 176 static void bin_vma_open(struct vm_area_struct *vma)
 177 {
 178         struct file *file = vma->vm_file;
 179         struct bin_buffer *bb = file->private_data;
 180         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 181
 182         if (!bb->vm_ops || !bb->vm_ops->open)
 183                 return;
 184
 185         if (!sysfs_get_active(attr_sd))
 186                 return;
 187
 188         bb->vm_ops->open(vma);
 189
 190         sysfs_put_active(attr_sd);
 191 }
 192
 193 static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 194 {
 195         struct file *file = vma->vm_file;
 196         struct bin_buffer *bb = file->private_data;
 197         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 198         int ret;
 199
 200         if (!bb->vm_ops || !bb->vm_ops->fault)
 201                 return VM_FAULT_SIGBUS;
 202
 203         if (!sysfs_get_active(attr_sd))
 204                 return VM_FAULT_SIGBUS;
 205
 206         ret = bb->vm_ops->fault(vma, vmf);
 207
 208         sysfs_put_active(attr_sd);
 209         return ret;
 210 }
 211
 212 static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 213 {
 214         struct file *file = vma->vm_file;
 215         struct bin_buffer *bb = file->private_data;
 216         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 217         int ret;
 218
 219         if (!bb->vm_ops)
 220                 return VM_FAULT_SIGBUS;
 221
 222         if (!bb->vm_ops->page_mkwrite)
 223                 return 0;
 224
 225         if (!sysfs_get_active(attr_sd))
 226                 return VM_FAULT_SIGBUS;
 227
 228         ret = bb->vm_ops->page_mkwrite(vma, vmf);
 229
 230         sysfs_put_active(attr_sd);
 231         return ret;
 232 }
 233
 234 static int bin_access(struct vm_area_struct *vma, unsigned long addr,
 235                   void *buf, int len, int write)
 236 {
 237         struct file *file = vma->vm_file;
 238         struct bin_buffer *bb = file->private_data;
 239         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 240         int ret;
 241
 242         if (!bb->vm_ops || !bb->vm_ops->access)
 243                 return -EINVAL;
 244
 245         if (!sysfs_get_active(attr_sd))
 246                 return -EINVAL;
 247
 248         ret = bb->vm_ops->access(vma, addr, buf, len, write);
 249
 250         sysfs_put_active(attr_sd);
 251         return ret;
 252 }
 253
 254 #ifdef CONFIG_NUMA
 255 static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 256 {
 257         struct file *file = vma->vm_file;
 258         struct bin_buffer *bb = file->private_data;
 259         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 260         int ret;
 261
 262         if (!bb->vm_ops || !bb->vm_ops->set_policy)
 263                 return 0;
 264
 265         if (!sysfs_get_active(attr_sd))
 266                 return -EINVAL;
 267
 268         ret = bb->vm_ops->set_policy(vma, new);
 269
 270         sysfs_put_active(attr_sd);
 271         return ret;
 272 }
 273
 274 static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
 275                                         unsigned long addr)
 276 {
 277         struct file *file = vma->vm_file;
 278         struct bin_buffer *bb = file->private_data;
 279         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 280         struct mempolicy *pol;
 281
 282         if (!bb->vm_ops || !bb->vm_ops->get_policy)
 283                 return vma->vm_policy;
 284
 285         if (!sysfs_get_active(attr_sd))
 286                 return vma->vm_policy;
 287
 288         pol = bb->vm_ops->get_policy(vma, addr);
 289
 290         sysfs_put_active(attr_sd);
 291         return pol;
 292 }
 293
 294 static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
 295                         const nodemask_t *to, unsigned long flags)
 296 {
 297         struct file *file = vma->vm_file;
 298         struct bin_buffer *bb = file->private_data;
 299         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 300         int ret;
 301
 302         if (!bb->vm_ops || !bb->vm_ops->migrate)
 303                 return 0;
 304
 305         if (!sysfs_get_active(attr_sd))
 306                 return 0;
 307
 308         ret = bb->vm_ops->migrate(vma, from, to, flags);
 309
 310         sysfs_put_active(attr_sd);
 311         return ret;
 312 }
 313 #endif
 314
 315 static const struct vm_operations_struct bin_vm_ops = {
 316         .open           = bin_vma_open,
 317         .fault          = bin_fault,
 318         .page_mkwrite   = bin_page_mkwrite,
 319         .access         = bin_access,
 320 #ifdef CONFIG_NUMA
 321         .set_policy     = bin_set_policy,
 322         .get_policy     = bin_get_policy,
 323         .migrate        = bin_migrate,
 324 #endif
 325 };
 326
 327 static int mmap(struct file *file, struct vm_area_struct *vma)
 328 {
 329         struct bin_buffer *bb = file->private_data;
 330         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 331         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 332         struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
 333         int rc;
 334
 335         mutex_lock(&bb->mutex);
 336
 337         /* need attr_sd for attr, its parent for kobj */
 338         rc = -ENODEV;
 339         if (!sysfs_get_active(attr_sd))
 340                 goto out_unlock;
 341
 342         rc = -EINVAL;
 343         if (!attr->mmap)
 344                 goto out_put;
 345
 346         rc = attr->mmap(file, kobj, attr, vma);
 347         if (rc)
 348                 goto out_put;
 349
 350         /*
 351          * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
 352          * to satisfy versions of X which crash if the mmap fails: that
 353          * substitutes a new vm_file, and we don't then want bin_vm_ops.
 354          */
 355         if (vma->vm_file != file)
 356                 goto out_put;
 357
 358         rc = -EINVAL;
 359         if (bb->mmapped && bb->vm_ops != vma->vm_ops)
 360                 goto out_put;
 361
 362         /*
 363          * It is not possible to successfully wrap close.
 364          * So error if someone is trying to use close.
 365          */
 366         rc = -EINVAL;
 367         if (vma->vm_ops && vma->vm_ops->close)
 368                 goto out_put;
 369
 370         rc = 0;
 371         bb->mmapped = 1;
 372         bb->vm_ops = vma->vm_ops;
 373         vma->vm_ops = &bin_vm_ops;
 374 out_put:
 375         sysfs_put_active(attr_sd);
 376 out_unlock:
 377         mutex_unlock(&bb->mutex);
 378
 379         return rc;
 380 }
 381
 382 static int open(struct inode * inode, struct file * file)
 383 {
 384         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 385         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 386         struct bin_buffer *bb = NULL;
 387         int error;
 388
 389         /* binary file operations requires both @sd and its parent */
 390         if (!sysfs_get_active(attr_sd))
 391                 return -ENODEV;
 392
 393         error = -EACCES;
 394         if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 395                 goto err_out;
 396         if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
 397                 goto err_out;
 398
 399         error = -ENOMEM;
 400         bb = kzalloc(sizeof(*bb), GFP_KERNEL);
 401         if (!bb)
 402                 goto err_out;
 403
 404         bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 405         if (!bb->buffer)
 406                 goto err_out;
 407
 408         mutex_init(&bb->mutex);
 409         bb->file = file;
 410         file->private_data = bb;
 411
 412         mutex_lock(&sysfs_bin_lock);
 413         hlist_add_head(&bb->list, &attr_sd->s_bin_attr.buffers);
 414         mutex_unlock(&sysfs_bin_lock);
 415
 416         /* open succeeded, put active references */
 417         sysfs_put_active(attr_sd);
 418         return 0;
 419
 420  err_out:
 421         sysfs_put_active(attr_sd);
 422         kfree(bb);
 423         return error;
 424 }
 425
 426 static int release(struct inode * inode, struct file * file)
 427 {
 428         struct bin_buffer *bb = file->private_data;
 429
 430         mutex_lock(&sysfs_bin_lock);
 431         hlist_del(&bb->list);
 432         mutex_unlock(&sysfs_bin_lock);
 433
 434         kfree(bb->buffer);
 435         kfree(bb);
 436         return 0;
 437 }
 438
 439 const struct file_operations bin_fops = {
 440         .read           = read,
 441         .write          = write,
 442         .mmap           = mmap,
 443         .llseek         = generic_file_llseek,
 444         .open           = open,
 445         .release        = release,
 446 };
 447
 448
 449 void unmap_bin_file(struct sysfs_dirent *attr_sd)
 450 {
 451         struct bin_buffer *bb;
 452         struct hlist_node *tmp;
 453
 454         if (sysfs_type(attr_sd) != SYSFS_KOBJ_BIN_ATTR)
 455                 return;
 456
 457         mutex_lock(&sysfs_bin_lock);
 458
 459         hlist_for_each_entry(bb, tmp, &attr_sd->s_bin_attr.buffers, list) {
 460                 struct inode *inode = bb->file->f_path.dentry->d_inode;
 461
 462                 unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 463         }
 464
 465         mutex_unlock(&sysfs_bin_lock);
 466 }
 467
 468 /**
 469  *      sysfs_create_bin_file - create binary file for object.
 470  *      @kobj:  object.
 471  *      @attr:  attribute descriptor.
 472  */
 473
 474 int sysfs_create_bin_file(struct kobject *kobj,
 475                           const struct bin_attribute *attr)
 476 {
 477         BUG_ON(!kobj || !kobj->sd || !attr);
 478
 479         return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
 480 }
 481
 482
 483 /**
 484  *      sysfs_remove_bin_file - remove binary file for object.
 485  *      @kobj:  object.
 486  *      @attr:  attribute descriptor.
 487  */
 488
 489 void sysfs_remove_bin_file(struct kobject *kobj,
 490                            const struct bin_attribute *attr)
 491 {
 492         sysfs_hash_and_remove(kobj->sd, NULL, attr->attr.name);
 493 }
 494
 495 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 496 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);