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_inode(file)->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_inode(file)->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)
 183                 return;
 184
 185         if (!sysfs_get_active(attr_sd))
 186                 return;
 187
 188         if (bb->vm_ops->open)
 189                 bb->vm_ops->open(vma);
 190
 191         sysfs_put_active(attr_sd);
 192 }
 193
 194 static int bin_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 195 {
 196         struct file *file = vma->vm_file;
 197         struct bin_buffer *bb = file->private_data;
 198         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 199         int ret;
 200
 201         if (!bb->vm_ops)
 202                 return VM_FAULT_SIGBUS;
 203
 204         if (!sysfs_get_active(attr_sd))
 205                 return VM_FAULT_SIGBUS;
 206
 207         ret = VM_FAULT_SIGBUS;
 208         if (bb->vm_ops->fault)
 209                 ret = bb->vm_ops->fault(vma, vmf);
 210
 211         sysfs_put_active(attr_sd);
 212         return ret;
 213 }
 214
 215 static int bin_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
 216 {
 217         struct file *file = vma->vm_file;
 218         struct bin_buffer *bb = file->private_data;
 219         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 220         int ret;
 221
 222         if (!bb->vm_ops)
 223                 return VM_FAULT_SIGBUS;
 224
 225         if (!sysfs_get_active(attr_sd))
 226                 return VM_FAULT_SIGBUS;
 227
 228         ret = 0;
 229         if (bb->vm_ops->page_mkwrite)
 230                 ret = bb->vm_ops->page_mkwrite(vma, vmf);
 231         else
 232                 file_update_time(file);
 233
 234         sysfs_put_active(attr_sd);
 235         return ret;
 236 }
 237
 238 static int bin_access(struct vm_area_struct *vma, unsigned long addr,
 239                   void *buf, int len, int write)
 240 {
 241         struct file *file = vma->vm_file;
 242         struct bin_buffer *bb = file->private_data;
 243         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 244         int ret;
 245
 246         if (!bb->vm_ops)
 247                 return -EINVAL;
 248
 249         if (!sysfs_get_active(attr_sd))
 250                 return -EINVAL;
 251
 252         ret = -EINVAL;
 253         if (bb->vm_ops->access)
 254                 ret = bb->vm_ops->access(vma, addr, buf, len, write);
 255
 256         sysfs_put_active(attr_sd);
 257         return ret;
 258 }
 259
 260 #ifdef CONFIG_NUMA
 261 static int bin_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 262 {
 263         struct file *file = vma->vm_file;
 264         struct bin_buffer *bb = file->private_data;
 265         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 266         int ret;
 267
 268         if (!bb->vm_ops)
 269                 return 0;
 270
 271         if (!sysfs_get_active(attr_sd))
 272                 return -EINVAL;
 273
 274         ret = 0;
 275         if (bb->vm_ops->set_policy)
 276                 ret = bb->vm_ops->set_policy(vma, new);
 277
 278         sysfs_put_active(attr_sd);
 279         return ret;
 280 }
 281
 282 static struct mempolicy *bin_get_policy(struct vm_area_struct *vma,
 283                                         unsigned long addr)
 284 {
 285         struct file *file = vma->vm_file;
 286         struct bin_buffer *bb = file->private_data;
 287         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 288         struct mempolicy *pol;
 289
 290         if (!bb->vm_ops)
 291                 return vma->vm_policy;
 292
 293         if (!sysfs_get_active(attr_sd))
 294                 return vma->vm_policy;
 295
 296         pol = vma->vm_policy;
 297         if (bb->vm_ops->get_policy)
 298                 pol = bb->vm_ops->get_policy(vma, addr);
 299
 300         sysfs_put_active(attr_sd);
 301         return pol;
 302 }
 303
 304 static int bin_migrate(struct vm_area_struct *vma, const nodemask_t *from,
 305                         const nodemask_t *to, unsigned long flags)
 306 {
 307         struct file *file = vma->vm_file;
 308         struct bin_buffer *bb = file->private_data;
 309         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 310         int ret;
 311
 312         if (!bb->vm_ops)
 313                 return 0;
 314
 315         if (!sysfs_get_active(attr_sd))
 316                 return 0;
 317
 318         ret = 0;
 319         if (bb->vm_ops->migrate)
 320                 ret = bb->vm_ops->migrate(vma, from, to, flags);
 321
 322         sysfs_put_active(attr_sd);
 323         return ret;
 324 }
 325 #endif
 326
 327 static const struct vm_operations_struct bin_vm_ops = {
 328         .open           = bin_vma_open,
 329         .fault          = bin_fault,
 330         .page_mkwrite   = bin_page_mkwrite,
 331         .access         = bin_access,
 332 #ifdef CONFIG_NUMA
 333         .set_policy     = bin_set_policy,
 334         .get_policy     = bin_get_policy,
 335         .migrate        = bin_migrate,
 336 #endif
 337 };
 338
 339 static int mmap(struct file *file, struct vm_area_struct *vma)
 340 {
 341         struct bin_buffer *bb = file->private_data;
 342         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 343         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 344         struct kobject *kobj = attr_sd->s_parent->s_dir.kobj;
 345         int rc;
 346
 347         mutex_lock(&bb->mutex);
 348
 349         /* need attr_sd for attr, its parent for kobj */
 350         rc = -ENODEV;
 351         if (!sysfs_get_active(attr_sd))
 352                 goto out_unlock;
 353
 354         rc = -EINVAL;
 355         if (!attr->mmap)
 356                 goto out_put;
 357
 358         rc = attr->mmap(file, kobj, attr, vma);
 359         if (rc)
 360                 goto out_put;
 361
 362         /*
 363          * PowerPC's pci_mmap of legacy_mem uses shmem_zero_setup()
 364          * to satisfy versions of X which crash if the mmap fails: that
 365          * substitutes a new vm_file, and we don't then want bin_vm_ops.
 366          */
 367         if (vma->vm_file != file)
 368                 goto out_put;
 369
 370         rc = -EINVAL;
 371         if (bb->mmapped && bb->vm_ops != vma->vm_ops)
 372                 goto out_put;
 373
 374         /*
 375          * It is not possible to successfully wrap close.
 376          * So error if someone is trying to use close.
 377          */
 378         rc = -EINVAL;
 379         if (vma->vm_ops && vma->vm_ops->close)
 380                 goto out_put;
 381
 382         rc = 0;
 383         bb->mmapped = 1;
 384         bb->vm_ops = vma->vm_ops;
 385         vma->vm_ops = &bin_vm_ops;
 386 out_put:
 387         sysfs_put_active(attr_sd);
 388 out_unlock:
 389         mutex_unlock(&bb->mutex);
 390
 391         return rc;
 392 }
 393
 394 static int open(struct inode * inode, struct file * file)
 395 {
 396         struct sysfs_dirent *attr_sd = file->f_path.dentry->d_fsdata;
 397         struct bin_attribute *attr = attr_sd->s_bin_attr.bin_attr;
 398         struct bin_buffer *bb = NULL;
 399         int error;
 400
 401         /* binary file operations requires both @sd and its parent */
 402         if (!sysfs_get_active(attr_sd))
 403                 return -ENODEV;
 404
 405         error = -EACCES;
 406         if ((file->f_mode & FMODE_WRITE) && !(attr->write || attr->mmap))
 407                 goto err_out;
 408         if ((file->f_mode & FMODE_READ) && !(attr->read || attr->mmap))
 409                 goto err_out;
 410
 411         error = -ENOMEM;
 412         bb = kzalloc(sizeof(*bb), GFP_KERNEL);
 413         if (!bb)
 414                 goto err_out;
 415
 416         bb->buffer = kmalloc(PAGE_SIZE, GFP_KERNEL);
 417         if (!bb->buffer)
 418                 goto err_out;
 419
 420         mutex_init(&bb->mutex);
 421         bb->file = file;
 422         file->private_data = bb;
 423
 424         mutex_lock(&sysfs_bin_lock);
 425         hlist_add_head(&bb->list, &attr_sd->s_bin_attr.buffers);
 426         mutex_unlock(&sysfs_bin_lock);
 427
 428         /* open succeeded, put active references */
 429         sysfs_put_active(attr_sd);
 430         return 0;
 431
 432  err_out:
 433         sysfs_put_active(attr_sd);
 434         kfree(bb);
 435         return error;
 436 }
 437
 438 static int release(struct inode * inode, struct file * file)
 439 {
 440         struct bin_buffer *bb = file->private_data;
 441
 442         mutex_lock(&sysfs_bin_lock);
 443         hlist_del(&bb->list);
 444         mutex_unlock(&sysfs_bin_lock);
 445
 446         kfree(bb->buffer);
 447         kfree(bb);
 448         return 0;
 449 }
 450
 451 const struct file_operations bin_fops = {
 452         .read           = read,
 453         .write          = write,
 454         .mmap           = mmap,
 455         .llseek         = generic_file_llseek,
 456         .open           = open,
 457         .release        = release,
 458 };
 459
 460
 461 void unmap_bin_file(struct sysfs_dirent *attr_sd)
 462 {
 463         struct bin_buffer *bb;
 464
 465         if (sysfs_type(attr_sd) != SYSFS_KOBJ_BIN_ATTR)
 466                 return;
 467
 468         mutex_lock(&sysfs_bin_lock);
 469
 470         hlist_for_each_entry(bb, &attr_sd->s_bin_attr.buffers, list) {
 471                 struct inode *inode = file_inode(bb->file);
 472
 473                 unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 474         }
 475
 476         mutex_unlock(&sysfs_bin_lock);
 477 }
 478
 479 /**
 480  *      sysfs_create_bin_file - create binary file for object.
 481  *      @kobj:  object.
 482  *      @attr:  attribute descriptor.
 483  */
 484
 485 int sysfs_create_bin_file(struct kobject *kobj,
 486                           const struct bin_attribute *attr)
 487 {
 488         BUG_ON(!kobj || !kobj->sd || !attr);
 489
 490         return sysfs_add_file(kobj->sd, &attr->attr, SYSFS_KOBJ_BIN_ATTR);
 491 }
 492
 493
 494 /**
 495  *      sysfs_remove_bin_file - remove binary file for object.
 496  *      @kobj:  object.
 497  *      @attr:  attribute descriptor.
 498  */
 499
 500 void sysfs_remove_bin_file(struct kobject *kobj,
 501                            const struct bin_attribute *attr)
 502 {
 503         sysfs_hash_and_remove(kobj->sd, NULL, attr->attr.name);
 504 }
 505
 506 EXPORT_SYMBOL_GPL(sysfs_create_bin_file);
 507 EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);