drivers/dax/device.c

   1 /*
   2  * Copyright(c) 2016 - 2017 Intel Corporation. All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of version 2 of the GNU General Public License as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  */
  13 #include <linux/pagemap.h>
  14 #include <linux/module.h>
  15 #include <linux/device.h>
  16 #include <linux/pfn_t.h>
  17 #include <linux/cdev.h>
  18 #include <linux/slab.h>
  19 #include <linux/dax.h>
  20 #include <linux/fs.h>
  21 #include <linux/mm.h>
  22 #include "dax-private.h"
  23 #include "dax.h"
  24
  25 static struct class *dax_class;
  26
  27 /*
  28  * Rely on the fact that drvdata is set before the attributes are
  29  * registered, and that the attributes are unregistered before drvdata
  30  * is cleared to assume that drvdata is always valid.
  31  */
  32 static ssize_t id_show(struct device *dev,
  33                 struct device_attribute *attr, char *buf)
  34 {
  35         struct dax_region *dax_region = dev_get_drvdata(dev);
  36
  37         return sprintf(buf, "%d\n", dax_region->id);
  38 }
  39 static DEVICE_ATTR_RO(id);
  40
  41 static ssize_t region_size_show(struct device *dev,
  42                 struct device_attribute *attr, char *buf)
  43 {
  44         struct dax_region *dax_region = dev_get_drvdata(dev);
  45
  46         return sprintf(buf, "%llu\n", (unsigned long long)
  47                         resource_size(&dax_region->res));
  48 }
  49 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
  50                 region_size_show, NULL);
  51
  52 static ssize_t align_show(struct device *dev,
  53                 struct device_attribute *attr, char *buf)
  54 {
  55         struct dax_region *dax_region = dev_get_drvdata(dev);
  56
  57         return sprintf(buf, "%u\n", dax_region->align);
  58 }
  59 static DEVICE_ATTR_RO(align);
  60
  61 static struct attribute *dax_region_attributes[] = {
  62         &dev_attr_region_size.attr,
  63         &dev_attr_align.attr,
  64         &dev_attr_id.attr,
  65         NULL,
  66 };
  67
  68 static const struct attribute_group dax_region_attribute_group = {
  69         .name = "dax_region",
  70         .attrs = dax_region_attributes,
  71 };
  72
  73 static const struct attribute_group *dax_region_attribute_groups[] = {
  74         &dax_region_attribute_group,
  75         NULL,
  76 };
  77
  78 static void dax_region_free(struct kref *kref)
  79 {
  80         struct dax_region *dax_region;
  81
  82         dax_region = container_of(kref, struct dax_region, kref);
  83         kfree(dax_region);
  84 }
  85
  86 void dax_region_put(struct dax_region *dax_region)
  87 {
  88         kref_put(&dax_region->kref, dax_region_free);
  89 }
  90 EXPORT_SYMBOL_GPL(dax_region_put);
  91
  92 static void dax_region_unregister(void *region)
  93 {
  94         struct dax_region *dax_region = region;
  95
  96         sysfs_remove_groups(&dax_region->dev->kobj,
  97                         dax_region_attribute_groups);
  98         dax_region_put(dax_region);
  99 }
 100
 101 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 102                 struct resource *res, unsigned int align, void *addr,
 103                 unsigned long pfn_flags)
 104 {
 105         struct dax_region *dax_region;
 106
 107         /*
 108          * The DAX core assumes that it can store its private data in
 109          * parent->driver_data. This WARN is a reminder / safeguard for
 110          * developers of device-dax drivers.
 111          */
 112         if (dev_get_drvdata(parent)) {
 113                 dev_WARN(parent, "dax core failed to setup private data\n");
 114                 return NULL;
 115         }
 116
 117         if (!IS_ALIGNED(res->start, align)
 118                         || !IS_ALIGNED(resource_size(res), align))
 119                 return NULL;
 120
 121         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 122         if (!dax_region)
 123                 return NULL;
 124
 125         dev_set_drvdata(parent, dax_region);
 126         memcpy(&dax_region->res, res, sizeof(*res));
 127         dax_region->pfn_flags = pfn_flags;
 128         kref_init(&dax_region->kref);
 129         dax_region->id = region_id;
 130         ida_init(&dax_region->ida);
 131         dax_region->align = align;
 132         dax_region->dev = parent;
 133         dax_region->base = addr;
 134         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 135                 kfree(dax_region);
 136                 return NULL;;
 137         }
 138
 139         kref_get(&dax_region->kref);
 140         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 141                 return NULL;
 142         return dax_region;
 143 }
 144 EXPORT_SYMBOL_GPL(alloc_dax_region);
 145
 146 static struct dev_dax *to_dev_dax(struct device *dev)
 147 {
 148         return container_of(dev, struct dev_dax, dev);
 149 }
 150
 151 static ssize_t size_show(struct device *dev,
 152                 struct device_attribute *attr, char *buf)
 153 {
 154         struct dev_dax *dev_dax = to_dev_dax(dev);
 155         unsigned long long size = 0;
 156         int i;
 157
 158         for (i = 0; i < dev_dax->num_resources; i++)
 159                 size += resource_size(&dev_dax->res[i]);
 160
 161         return sprintf(buf, "%llu\n", size);
 162 }
 163 static DEVICE_ATTR_RO(size);
 164
 165 static struct attribute *dev_dax_attributes[] = {
 166         &dev_attr_size.attr,
 167         NULL,
 168 };
 169
 170 static const struct attribute_group dev_dax_attribute_group = {
 171         .attrs = dev_dax_attributes,
 172 };
 173
 174 static const struct attribute_group *dax_attribute_groups[] = {
 175         &dev_dax_attribute_group,
 176         NULL,
 177 };
 178
 179 static int check_vma(struct dev_dax *dev_dax, struct vm_area_struct *vma,
 180                 const char *func)
 181 {
 182         struct dax_region *dax_region = dev_dax->region;
 183         struct device *dev = &dev_dax->dev;
 184         unsigned long mask;
 185
 186         if (!dax_alive(dev_dax->dax_dev))
 187                 return -ENXIO;
 188
 189         /* prevent private mappings from being established */
 190         if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
 191                 dev_info(dev, "%s: %s: fail, attempted private mapping\n",
 192                                 current->comm, func);
 193                 return -EINVAL;
 194         }
 195
 196         mask = dax_region->align - 1;
 197         if (vma->vm_start & mask || vma->vm_end & mask) {
 198                 dev_info(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 199                                 current->comm, func, vma->vm_start, vma->vm_end,
 200                                 mask);
 201                 return -EINVAL;
 202         }
 203
 204         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 205                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
 206                 dev_info(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
 207                                 current->comm, func);
 208                 return -EINVAL;
 209         }
 210
 211         if (!vma_is_dax(vma)) {
 212                 dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
 213                                 current->comm, func);
 214                 return -EINVAL;
 215         }
 216
 217         return 0;
 218 }
 219
 220 /* see "strong" declaration in tools/testing/nvdimm/dax-dev.c */
 221 __weak phys_addr_t dax_pgoff_to_phys(struct dev_dax *dev_dax, pgoff_t pgoff,
 222                 unsigned long size)
 223 {
 224         struct resource *res;
 225         /* gcc-4.6.3-nolibc for i386 complains that this is uninitialized */
 226         phys_addr_t uninitialized_var(phys);
 227         int i;
 228
 229         for (i = 0; i < dev_dax->num_resources; i++) {
 230                 res = &dev_dax->res[i];
 231                 phys = pgoff * PAGE_SIZE + res->start;
 232                 if (phys >= res->start && phys <= res->end)
 233                         break;
 234                 pgoff -= PHYS_PFN(resource_size(res));
 235         }
 236
 237         if (i < dev_dax->num_resources) {
 238                 res = &dev_dax->res[i];
 239                 if (phys + size - 1 <= res->end)
 240                         return phys;
 241         }
 242
 243         return -1;
 244 }
 245
 246 static int __dev_dax_pte_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 247 {
 248         struct device *dev = &dev_dax->dev;
 249         struct dax_region *dax_region;
 250         int rc = VM_FAULT_SIGBUS;
 251         phys_addr_t phys;
 252         pfn_t pfn;
 253         unsigned int fault_size = PAGE_SIZE;
 254
 255         if (check_vma(dev_dax, vmf->vma, __func__))
 256                 return VM_FAULT_SIGBUS;
 257
 258         dax_region = dev_dax->region;
 259         if (dax_region->align > PAGE_SIZE) {
 260                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 261                         __func__, dax_region->align, fault_size);
 262                 return VM_FAULT_SIGBUS;
 263         }
 264
 265         if (fault_size != dax_region->align)
 266                 return VM_FAULT_SIGBUS;
 267
 268         phys = dax_pgoff_to_phys(dev_dax, vmf->pgoff, PAGE_SIZE);
 269         if (phys == -1) {
 270                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 271                                 vmf->pgoff);
 272                 return VM_FAULT_SIGBUS;
 273         }
 274
 275         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 276
 277         rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
 278
 279         if (rc == -ENOMEM)
 280                 return VM_FAULT_OOM;
 281         if (rc < 0 && rc != -EBUSY)
 282                 return VM_FAULT_SIGBUS;
 283
 284         return VM_FAULT_NOPAGE;
 285 }
 286
 287 static int __dev_dax_pmd_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 288 {
 289         unsigned long pmd_addr = vmf->address & PMD_MASK;
 290         struct device *dev = &dev_dax->dev;
 291         struct dax_region *dax_region;
 292         phys_addr_t phys;
 293         pgoff_t pgoff;
 294         pfn_t pfn;
 295         unsigned int fault_size = PMD_SIZE;
 296
 297         if (check_vma(dev_dax, vmf->vma, __func__))
 298                 return VM_FAULT_SIGBUS;
 299
 300         dax_region = dev_dax->region;
 301         if (dax_region->align > PMD_SIZE) {
 302                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 303                         __func__, dax_region->align, fault_size);
 304                 return VM_FAULT_SIGBUS;
 305         }
 306
 307         /* dax pmd mappings require pfn_t_devmap() */
 308         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 309                 dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
 310                 return VM_FAULT_SIGBUS;
 311         }
 312
 313         if (fault_size < dax_region->align)
 314                 return VM_FAULT_SIGBUS;
 315         else if (fault_size > dax_region->align)
 316                 return VM_FAULT_FALLBACK;
 317
 318         /* if we are outside of the VMA */
 319         if (pmd_addr < vmf->vma->vm_start ||
 320                         (pmd_addr + PMD_SIZE) > vmf->vma->vm_end)
 321                 return VM_FAULT_SIGBUS;
 322
 323         pgoff = linear_page_index(vmf->vma, pmd_addr);
 324         phys = dax_pgoff_to_phys(dev_dax, pgoff, PMD_SIZE);
 325         if (phys == -1) {
 326                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 327                                 pgoff);
 328                 return VM_FAULT_SIGBUS;
 329         }
 330
 331         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 332
 333         return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, pfn,
 334                         vmf->flags & FAULT_FLAG_WRITE);
 335 }
 336
 337 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 338 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 339 {
 340         unsigned long pud_addr = vmf->address & PUD_MASK;
 341         struct device *dev = &dev_dax->dev;
 342         struct dax_region *dax_region;
 343         phys_addr_t phys;
 344         pgoff_t pgoff;
 345         pfn_t pfn;
 346         unsigned int fault_size = PUD_SIZE;
 347
 348
 349         if (check_vma(dev_dax, vmf->vma, __func__))
 350                 return VM_FAULT_SIGBUS;
 351
 352         dax_region = dev_dax->region;
 353         if (dax_region->align > PUD_SIZE) {
 354                 dev_dbg(dev, "%s: alignment (%#x) > fault size (%#x)\n",
 355                         __func__, dax_region->align, fault_size);
 356                 return VM_FAULT_SIGBUS;
 357         }
 358
 359         /* dax pud mappings require pfn_t_devmap() */
 360         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 361                 dev_dbg(dev, "%s: region lacks devmap flags\n", __func__);
 362                 return VM_FAULT_SIGBUS;
 363         }
 364
 365         if (fault_size < dax_region->align)
 366                 return VM_FAULT_SIGBUS;
 367         else if (fault_size > dax_region->align)
 368                 return VM_FAULT_FALLBACK;
 369
 370         /* if we are outside of the VMA */
 371         if (pud_addr < vmf->vma->vm_start ||
 372                         (pud_addr + PUD_SIZE) > vmf->vma->vm_end)
 373                 return VM_FAULT_SIGBUS;
 374
 375         pgoff = linear_page_index(vmf->vma, pud_addr);
 376         phys = dax_pgoff_to_phys(dev_dax, pgoff, PUD_SIZE);
 377         if (phys == -1) {
 378                 dev_dbg(dev, "%s: pgoff_to_phys(%#lx) failed\n", __func__,
 379                                 pgoff);
 380                 return VM_FAULT_SIGBUS;
 381         }
 382
 383         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 384
 385         return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
 386                         vmf->flags & FAULT_FLAG_WRITE);
 387 }
 388 #else
 389 static int __dev_dax_pud_fault(struct dev_dax *dev_dax, struct vm_fault *vmf)
 390 {
 391         return VM_FAULT_FALLBACK;
 392 }
 393 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 394
 395 static int dev_dax_huge_fault(struct vm_fault *vmf,
 396                 enum page_entry_size pe_size)
 397 {
 398         int rc, id;
 399         struct file *filp = vmf->vma->vm_file;
 400         struct dev_dax *dev_dax = filp->private_data;
 401
 402         dev_dbg(&dev_dax->dev, "%s: %s: %s (%#lx - %#lx) size = %d\n", __func__,
 403                         current->comm, (vmf->flags & FAULT_FLAG_WRITE)
 404                         ? "write" : "read",
 405                         vmf->vma->vm_start, vmf->vma->vm_end, pe_size);
 406
 407         id = dax_read_lock();
 408         switch (pe_size) {
 409         case PE_SIZE_PTE:
 410                 rc = __dev_dax_pte_fault(dev_dax, vmf);
 411                 break;
 412         case PE_SIZE_PMD:
 413                 rc = __dev_dax_pmd_fault(dev_dax, vmf);
 414                 break;
 415         case PE_SIZE_PUD:
 416                 rc = __dev_dax_pud_fault(dev_dax, vmf);
 417                 break;
 418         default:
 419                 rc = VM_FAULT_SIGBUS;
 420         }
 421         dax_read_unlock(id);
 422
 423         return rc;
 424 }
 425
 426 static int dev_dax_fault(struct vm_fault *vmf)
 427 {
 428         return dev_dax_huge_fault(vmf, PE_SIZE_PTE);
 429 }
 430
 431 static int dev_dax_split(struct vm_area_struct *vma, unsigned long addr)
 432 {
 433         struct file *filp = vma->vm_file;
 434         struct dev_dax *dev_dax = filp->private_data;
 435         struct dax_region *dax_region = dev_dax->region;
 436
 437         if (!IS_ALIGNED(addr, dax_region->align))
 438                 return -EINVAL;
 439         return 0;
 440 }
 441
 442 static const struct vm_operations_struct dax_vm_ops = {
 443         .fault = dev_dax_fault,
 444         .huge_fault = dev_dax_huge_fault,
 445         .split = dev_dax_split,
 446 };
 447
 448 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 449 {
 450         struct dev_dax *dev_dax = filp->private_data;
 451         int rc, id;
 452
 453         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 454
 455         /*
 456          * We lock to check dax_dev liveness and will re-check at
 457          * fault time.
 458          */
 459         id = dax_read_lock();
 460         rc = check_vma(dev_dax, vma, __func__);
 461         dax_read_unlock(id);
 462         if (rc)
 463                 return rc;
 464
 465         vma->vm_ops = &dax_vm_ops;
 466         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 467         return 0;
 468 }
 469
 470 /* return an unmapped area aligned to the dax region specified alignment */
 471 static unsigned long dax_get_unmapped_area(struct file *filp,
 472                 unsigned long addr, unsigned long len, unsigned long pgoff,
 473                 unsigned long flags)
 474 {
 475         unsigned long off, off_end, off_align, len_align, addr_align, align;
 476         struct dev_dax *dev_dax = filp ? filp->private_data : NULL;
 477         struct dax_region *dax_region;
 478
 479         if (!dev_dax || addr)
 480                 goto out;
 481
 482         dax_region = dev_dax->region;
 483         align = dax_region->align;
 484         off = pgoff << PAGE_SHIFT;
 485         off_end = off + len;
 486         off_align = round_up(off, align);
 487
 488         if ((off_end <= off_align) || ((off_end - off_align) < align))
 489                 goto out;
 490
 491         len_align = len + align;
 492         if ((off + len_align) < off)
 493                 goto out;
 494
 495         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 496                         pgoff, flags);
 497         if (!IS_ERR_VALUE(addr_align)) {
 498                 addr_align += (off - addr_align) & (align - 1);
 499                 return addr_align;
 500         }
 501  out:
 502         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 503 }
 504
 505 static int dax_open(struct inode *inode, struct file *filp)
 506 {
 507         struct dax_device *dax_dev = inode_dax(inode);
 508         struct inode *__dax_inode = dax_inode(dax_dev);
 509         struct dev_dax *dev_dax = dax_get_private(dax_dev);
 510
 511         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 512         inode->i_mapping = __dax_inode->i_mapping;
 513         inode->i_mapping->host = __dax_inode;
 514         filp->f_mapping = inode->i_mapping;
 515         filp->f_wb_err = filemap_sample_wb_err(filp->f_mapping);
 516         filp->private_data = dev_dax;
 517         inode->i_flags = S_DAX;
 518
 519         return 0;
 520 }
 521
 522 static int dax_release(struct inode *inode, struct file *filp)
 523 {
 524         struct dev_dax *dev_dax = filp->private_data;
 525
 526         dev_dbg(&dev_dax->dev, "%s\n", __func__);
 527         return 0;
 528 }
 529
 530 static const struct file_operations dax_fops = {
 531         .llseek = noop_llseek,
 532         .owner = THIS_MODULE,
 533         .open = dax_open,
 534         .release = dax_release,
 535         .get_unmapped_area = dax_get_unmapped_area,
 536         .mmap = dax_mmap,
 537 };
 538
 539 static void dev_dax_release(struct device *dev)
 540 {
 541         struct dev_dax *dev_dax = to_dev_dax(dev);
 542         struct dax_region *dax_region = dev_dax->region;
 543         struct dax_device *dax_dev = dev_dax->dax_dev;
 544
 545         if (dev_dax->id >= 0)
 546                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 547         dax_region_put(dax_region);
 548         put_dax(dax_dev);
 549         kfree(dev_dax);
 550 }
 551
 552 static void kill_dev_dax(struct dev_dax *dev_dax)
 553 {
 554         struct dax_device *dax_dev = dev_dax->dax_dev;
 555         struct inode *inode = dax_inode(dax_dev);
 556
 557         kill_dax(dax_dev);
 558         unmap_mapping_range(inode->i_mapping, 0, 0, 1);
 559 }
 560
 561 static void unregister_dev_dax(void *dev)
 562 {
 563         struct dev_dax *dev_dax = to_dev_dax(dev);
 564         struct dax_device *dax_dev = dev_dax->dax_dev;
 565         struct inode *inode = dax_inode(dax_dev);
 566         struct cdev *cdev = inode->i_cdev;
 567
 568         dev_dbg(dev, "%s\n", __func__);
 569
 570         kill_dev_dax(dev_dax);
 571         cdev_device_del(cdev, dev);
 572         put_device(dev);
 573 }
 574
 575 struct dev_dax *devm_create_dev_dax(struct dax_region *dax_region,
 576                 int id, struct resource *res, int count)
 577 {
 578         struct device *parent = dax_region->dev;
 579         struct dax_device *dax_dev;
 580         struct dev_dax *dev_dax;
 581         struct inode *inode;
 582         struct device *dev;
 583         struct cdev *cdev;
 584         int rc, i;
 585
 586         if (!count)
 587                 return ERR_PTR(-EINVAL);
 588
 589         dev_dax = kzalloc(sizeof(*dev_dax) + sizeof(*res) * count, GFP_KERNEL);
 590         if (!dev_dax)
 591                 return ERR_PTR(-ENOMEM);
 592
 593         for (i = 0; i < count; i++) {
 594                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 595                                 || !IS_ALIGNED(resource_size(&res[i]),
 596                                         dax_region->align)) {
 597                         rc = -EINVAL;
 598                         break;
 599                 }
 600                 dev_dax->res[i].start = res[i].start;
 601                 dev_dax->res[i].end = res[i].end;
 602         }
 603
 604         if (i < count)
 605                 goto err_id;
 606
 607         if (id < 0) {
 608                 id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 609                 dev_dax->id = id;
 610                 if (id < 0) {
 611                         rc = id;
 612                         goto err_id;
 613                 }
 614         } else {
 615                 /* region provider owns @id lifetime */
 616                 dev_dax->id = -1;
 617         }
 618
 619         /*
 620          * No 'host' or dax_operations since there is no access to this
 621          * device outside of mmap of the resulting character device.
 622          */
 623         dax_dev = alloc_dax(dev_dax, NULL, NULL);
 624         if (!dax_dev) {
 625                 rc = -ENOMEM;
 626                 goto err_dax;
 627         }
 628
 629         /* from here on we're committed to teardown via dax_dev_release() */
 630         dev = &dev_dax->dev;
 631         device_initialize(dev);
 632
 633         inode = dax_inode(dax_dev);
 634         cdev = inode->i_cdev;
 635         cdev_init(cdev, &dax_fops);
 636         cdev->owner = parent->driver->owner;
 637
 638         dev_dax->num_resources = count;
 639         dev_dax->dax_dev = dax_dev;
 640         dev_dax->region = dax_region;
 641         kref_get(&dax_region->kref);
 642
 643         dev->devt = inode->i_rdev;
 644         dev->class = dax_class;
 645         dev->parent = parent;
 646         dev->groups = dax_attribute_groups;
 647         dev->release = dev_dax_release;
 648         dev_set_name(dev, "dax%d.%d", dax_region->id, id);
 649
 650         rc = cdev_device_add(cdev, dev);
 651         if (rc) {
 652                 kill_dev_dax(dev_dax);
 653                 put_device(dev);
 654                 return ERR_PTR(rc);
 655         }
 656
 657         rc = devm_add_action_or_reset(dax_region->dev, unregister_dev_dax, dev);
 658         if (rc)
 659                 return ERR_PTR(rc);
 660
 661         return dev_dax;
 662
 663  err_dax:
 664         if (dev_dax->id >= 0)
 665                 ida_simple_remove(&dax_region->ida, dev_dax->id);
 666  err_id:
 667         kfree(dev_dax);
 668
 669         return ERR_PTR(rc);
 670 }
 671 EXPORT_SYMBOL_GPL(devm_create_dev_dax);
 672
 673 static int __init dax_init(void)
 674 {
 675         dax_class = class_create(THIS_MODULE, "dax");
 676         return PTR_ERR_OR_ZERO(dax_class);
 677 }
 678
 679 static void __exit dax_exit(void)
 680 {
 681         class_destroy(dax_class);
 682 }
 683
 684 MODULE_AUTHOR("Intel Corporation");
 685 MODULE_LICENSE("GPL v2");
 686 subsys_initcall(dax_init);
 687 module_exit(dax_exit);