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