drivers/dax/dax.c

   1 /*
   2  * Copyright(c) 2016 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/mount.h>
  17 #include <linux/pfn_t.h>
  18 #include <linux/hash.h>
  19 #include <linux/cdev.h>
  20 #include <linux/slab.h>
  21 #include <linux/dax.h>
  22 #include <linux/fs.h>
  23 #include <linux/mm.h>
  24 #include "dax.h"
  25
  26 static dev_t dax_devt;
  27 DEFINE_STATIC_SRCU(dax_srcu);
  28 static struct class *dax_class;
  29 static DEFINE_IDA(dax_minor_ida);
  30 static int nr_dax = CONFIG_NR_DEV_DAX;
  31 module_param(nr_dax, int, S_IRUGO);
  32 static struct vfsmount *dax_mnt;
  33 static struct kmem_cache *dax_cache __read_mostly;
  34 static struct super_block *dax_superblock __read_mostly;
  35 MODULE_PARM_DESC(nr_dax, "max number of device-dax instances");
  36
  37 /**
  38  * struct dax_region - mapping infrastructure for dax devices
  39  * @id: kernel-wide unique region for a memory range
  40  * @base: linear address corresponding to @res
  41  * @kref: to pin while other agents have a need to do lookups
  42  * @dev: parent device backing this region
  43  * @align: allocation and mapping alignment for child dax devices
  44  * @res: physical address range of the region
  45  * @pfn_flags: identify whether the pfns are paged back or not
  46  */
  47 struct dax_region {
  48         int id;
  49         struct ida ida;
  50         void *base;
  51         struct kref kref;
  52         struct device *dev;
  53         unsigned int align;
  54         struct resource res;
  55         unsigned long pfn_flags;
  56 };
  57
  58 /**
  59  * struct dax_dev - subdivision of a dax region
  60  * @region - parent region
  61  * @dev - device backing the character device
  62  * @cdev - core chardev data
  63  * @alive - !alive + srcu grace period == no new mappings can be established
  64  * @id - child id in the region
  65  * @num_resources - number of physical address extents in this device
  66  * @res - array of physical address ranges
  67  */
  68 struct dax_dev {
  69         struct dax_region *region;
  70         struct inode *inode;
  71         struct device dev;
  72         struct cdev cdev;
  73         bool alive;
  74         int id;
  75         int num_resources;
  76         struct resource res[0];
  77 };
  78
  79 /*
  80  * Rely on the fact that drvdata is set before the attributes are
  81  * registered, and that the attributes are unregistered before drvdata
  82  * is cleared to assume that drvdata is always valid.
  83  */
  84 static ssize_t id_show(struct device *dev,
  85                 struct device_attribute *attr, char *buf)
  86 {
  87         struct dax_region *dax_region = dev_get_drvdata(dev);
  88
  89         return sprintf(buf, "%d\n", dax_region->id);
  90 }
  91 static DEVICE_ATTR_RO(id);
  92
  93 static ssize_t region_size_show(struct device *dev,
  94                 struct device_attribute *attr, char *buf)
  95 {
  96         struct dax_region *dax_region = dev_get_drvdata(dev);
  97
  98         return sprintf(buf, "%llu\n", (unsigned long long)
  99                         resource_size(&dax_region->res));
 100 }
 101 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
 102                 region_size_show, NULL);
 103
 104 static ssize_t align_show(struct device *dev,
 105                 struct device_attribute *attr, char *buf)
 106 {
 107         struct dax_region *dax_region = dev_get_drvdata(dev);
 108
 109         return sprintf(buf, "%u\n", dax_region->align);
 110 }
 111 static DEVICE_ATTR_RO(align);
 112
 113 static struct attribute *dax_region_attributes[] = {
 114         &dev_attr_region_size.attr,
 115         &dev_attr_align.attr,
 116         &dev_attr_id.attr,
 117         NULL,
 118 };
 119
 120 static const struct attribute_group dax_region_attribute_group = {
 121         .name = "dax_region",
 122         .attrs = dax_region_attributes,
 123 };
 124
 125 static const struct attribute_group *dax_region_attribute_groups[] = {
 126         &dax_region_attribute_group,
 127         NULL,
 128 };
 129
 130 static struct inode *dax_alloc_inode(struct super_block *sb)
 131 {
 132         return kmem_cache_alloc(dax_cache, GFP_KERNEL);
 133 }
 134
 135 static void dax_i_callback(struct rcu_head *head)
 136 {
 137         struct inode *inode = container_of(head, struct inode, i_rcu);
 138
 139         kmem_cache_free(dax_cache, inode);
 140 }
 141
 142 static void dax_destroy_inode(struct inode *inode)
 143 {
 144         call_rcu(&inode->i_rcu, dax_i_callback);
 145 }
 146
 147 static const struct super_operations dax_sops = {
 148         .statfs = simple_statfs,
 149         .alloc_inode = dax_alloc_inode,
 150         .destroy_inode = dax_destroy_inode,
 151         .drop_inode = generic_delete_inode,
 152 };
 153
 154 static struct dentry *dax_mount(struct file_system_type *fs_type,
 155                 int flags, const char *dev_name, void *data)
 156 {
 157         return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC);
 158 }
 159
 160 static struct file_system_type dax_type = {
 161         .name = "dax",
 162         .mount = dax_mount,
 163         .kill_sb = kill_anon_super,
 164 };
 165
 166 static int dax_test(struct inode *inode, void *data)
 167 {
 168         return inode->i_cdev == data;
 169 }
 170
 171 static int dax_set(struct inode *inode, void *data)
 172 {
 173         inode->i_cdev = data;
 174         return 0;
 175 }
 176
 177 static struct inode *dax_inode_get(struct cdev *cdev, dev_t devt)
 178 {
 179         struct inode *inode;
 180
 181         inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
 182                         dax_test, dax_set, cdev);
 183
 184         if (!inode)
 185                 return NULL;
 186
 187         if (inode->i_state & I_NEW) {
 188                 inode->i_mode = S_IFCHR;
 189                 inode->i_flags = S_DAX;
 190                 inode->i_rdev = devt;
 191                 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
 192                 unlock_new_inode(inode);
 193         }
 194         return inode;
 195 }
 196
 197 static void init_once(void *inode)
 198 {
 199         inode_init_once(inode);
 200 }
 201
 202 static int dax_inode_init(void)
 203 {
 204         int rc;
 205
 206         dax_cache = kmem_cache_create("dax_cache", sizeof(struct inode), 0,
 207                         (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
 208                          SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 209                         init_once);
 210         if (!dax_cache)
 211                 return -ENOMEM;
 212
 213         rc = register_filesystem(&dax_type);
 214         if (rc)
 215                 goto err_register_fs;
 216
 217         dax_mnt = kern_mount(&dax_type);
 218         if (IS_ERR(dax_mnt)) {
 219                 rc = PTR_ERR(dax_mnt);
 220                 goto err_mount;
 221         }
 222         dax_superblock = dax_mnt->mnt_sb;
 223
 224         return 0;
 225
 226  err_mount:
 227         unregister_filesystem(&dax_type);
 228  err_register_fs:
 229         kmem_cache_destroy(dax_cache);
 230
 231         return rc;
 232 }
 233
 234 static void dax_inode_exit(void)
 235 {
 236         kern_unmount(dax_mnt);
 237         unregister_filesystem(&dax_type);
 238         kmem_cache_destroy(dax_cache);
 239 }
 240
 241 static void dax_region_free(struct kref *kref)
 242 {
 243         struct dax_region *dax_region;
 244
 245         dax_region = container_of(kref, struct dax_region, kref);
 246         kfree(dax_region);
 247 }
 248
 249 void dax_region_put(struct dax_region *dax_region)
 250 {
 251         kref_put(&dax_region->kref, dax_region_free);
 252 }
 253 EXPORT_SYMBOL_GPL(dax_region_put);
 254
 255 static void dax_region_unregister(void *region)
 256 {
 257         struct dax_region *dax_region = region;
 258
 259         sysfs_remove_groups(&dax_region->dev->kobj,
 260                         dax_region_attribute_groups);
 261         dax_region_put(dax_region);
 262 }
 263
 264 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 265                 struct resource *res, unsigned int align, void *addr,
 266                 unsigned long pfn_flags)
 267 {
 268         struct dax_region *dax_region;
 269
 270         /*
 271          * The DAX core assumes that it can store its private data in
 272          * parent->driver_data. This WARN is a reminder / safeguard for
 273          * developers of device-dax drivers.
 274          */
 275         if (dev_get_drvdata(parent)) {
 276                 dev_WARN(parent, "dax core failed to setup private data\n");
 277                 return NULL;
 278         }
 279
 280         if (!IS_ALIGNED(res->start, align)
 281                         || !IS_ALIGNED(resource_size(res), align))
 282                 return NULL;
 283
 284         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 285         if (!dax_region)
 286                 return NULL;
 287
 288         dev_set_drvdata(parent, dax_region);
 289         memcpy(&dax_region->res, res, sizeof(*res));
 290         dax_region->pfn_flags = pfn_flags;
 291         kref_init(&dax_region->kref);
 292         dax_region->id = region_id;
 293         ida_init(&dax_region->ida);
 294         dax_region->align = align;
 295         dax_region->dev = parent;
 296         dax_region->base = addr;
 297         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 298                 kfree(dax_region);
 299                 return NULL;;
 300         }
 301
 302         kref_get(&dax_region->kref);
 303         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 304                 return NULL;
 305         return dax_region;
 306 }
 307 EXPORT_SYMBOL_GPL(alloc_dax_region);
 308
 309 static struct dax_dev *to_dax_dev(struct device *dev)
 310 {
 311         return container_of(dev, struct dax_dev, dev);
 312 }
 313
 314 static ssize_t size_show(struct device *dev,
 315                 struct device_attribute *attr, char *buf)
 316 {
 317         struct dax_dev *dax_dev = to_dax_dev(dev);
 318         unsigned long long size = 0;
 319         int i;
 320
 321         for (i = 0; i < dax_dev->num_resources; i++)
 322                 size += resource_size(&dax_dev->res[i]);
 323
 324         return sprintf(buf, "%llu\n", size);
 325 }
 326 static DEVICE_ATTR_RO(size);
 327
 328 static struct attribute *dax_device_attributes[] = {
 329         &dev_attr_size.attr,
 330         NULL,
 331 };
 332
 333 static const struct attribute_group dax_device_attribute_group = {
 334         .attrs = dax_device_attributes,
 335 };
 336
 337 static const struct attribute_group *dax_attribute_groups[] = {
 338         &dax_device_attribute_group,
 339         NULL,
 340 };
 341
 342 static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
 343                 const char *func)
 344 {
 345         struct dax_region *dax_region = dax_dev->region;
 346         struct device *dev = &dax_dev->dev;
 347         unsigned long mask;
 348
 349         if (!dax_dev->alive)
 350                 return -ENXIO;
 351
 352         /* prevent private mappings from being established */
 353         if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
 354                 dev_info(dev, "%s: %s: fail, attempted private mapping\n",
 355                                 current->comm, func);
 356                 return -EINVAL;
 357         }
 358
 359         mask = dax_region->align - 1;
 360         if (vma->vm_start & mask || vma->vm_end & mask) {
 361                 dev_info(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 362                                 current->comm, func, vma->vm_start, vma->vm_end,
 363                                 mask);
 364                 return -EINVAL;
 365         }
 366
 367         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 368                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
 369                 dev_info(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
 370                                 current->comm, func);
 371                 return -EINVAL;
 372         }
 373
 374         if (!vma_is_dax(vma)) {
 375                 dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
 376                                 current->comm, func);
 377                 return -EINVAL;
 378         }
 379
 380         return 0;
 381 }
 382
 383 static phys_addr_t pgoff_to_phys(struct dax_dev *dax_dev, pgoff_t pgoff,
 384                 unsigned long size)
 385 {
 386         struct resource *res;
 387         phys_addr_t phys;
 388         int i;
 389
 390         for (i = 0; i < dax_dev->num_resources; i++) {
 391                 res = &dax_dev->res[i];
 392                 phys = pgoff * PAGE_SIZE + res->start;
 393                 if (phys >= res->start && phys <= res->end)
 394                         break;
 395                 pgoff -= PHYS_PFN(resource_size(res));
 396         }
 397
 398         if (i < dax_dev->num_resources) {
 399                 res = &dax_dev->res[i];
 400                 if (phys + size - 1 <= res->end)
 401                         return phys;
 402         }
 403
 404         return -1;
 405 }
 406
 407 static int __dax_dev_fault(struct dax_dev *dax_dev, struct vm_area_struct *vma,
 408                 struct vm_fault *vmf)
 409 {
 410         struct device *dev = &dax_dev->dev;
 411         struct dax_region *dax_region;
 412         int rc = VM_FAULT_SIGBUS;
 413         phys_addr_t phys;
 414         pfn_t pfn;
 415         unsigned int fault_size = PAGE_SIZE;
 416
 417         if (check_vma(dax_dev, vma, __func__))
 418                 return VM_FAULT_SIGBUS;
 419
 420         dax_region = dax_dev->region;
 421         if (dax_region->align > PAGE_SIZE) {
 422                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 423                 return VM_FAULT_SIGBUS;
 424         }
 425
 426         if (fault_size != dax_region->align)
 427                 return VM_FAULT_SIGBUS;
 428
 429         phys = pgoff_to_phys(dax_dev, vmf->pgoff, PAGE_SIZE);
 430         if (phys == -1) {
 431                 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
 432                                 vmf->pgoff);
 433                 return VM_FAULT_SIGBUS;
 434         }
 435
 436         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 437
 438         rc = vm_insert_mixed(vma, vmf->address, pfn);
 439
 440         if (rc == -ENOMEM)
 441                 return VM_FAULT_OOM;
 442         if (rc < 0 && rc != -EBUSY)
 443                 return VM_FAULT_SIGBUS;
 444
 445         return VM_FAULT_NOPAGE;
 446 }
 447
 448 static int dax_dev_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 449 {
 450         int rc;
 451         struct file *filp = vma->vm_file;
 452         struct dax_dev *dax_dev = filp->private_data;
 453
 454         dev_dbg(&dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
 455                         current->comm, (vmf->flags & FAULT_FLAG_WRITE)
 456                         ? "write" : "read", vma->vm_start, vma->vm_end);
 457         rcu_read_lock();
 458         rc = __dax_dev_fault(dax_dev, vma, vmf);
 459         rcu_read_unlock();
 460
 461         return rc;
 462 }
 463
 464 static int __dax_dev_pmd_fault(struct dax_dev *dax_dev,
 465                 struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd,
 466                 unsigned int flags)
 467 {
 468         unsigned long pmd_addr = addr & PMD_MASK;
 469         struct device *dev = &dax_dev->dev;
 470         struct dax_region *dax_region;
 471         phys_addr_t phys;
 472         pgoff_t pgoff;
 473         pfn_t pfn;
 474         unsigned int fault_size = PMD_SIZE;
 475
 476         if (check_vma(dax_dev, vma, __func__))
 477                 return VM_FAULT_SIGBUS;
 478
 479         dax_region = dax_dev->region;
 480         if (dax_region->align > PMD_SIZE) {
 481                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 482                 return VM_FAULT_SIGBUS;
 483         }
 484
 485         /* dax pmd mappings require pfn_t_devmap() */
 486         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 487                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 488                 return VM_FAULT_SIGBUS;
 489         }
 490
 491         if (fault_size < dax_region->align)
 492                 return VM_FAULT_SIGBUS;
 493         else if (fault_size > dax_region->align)
 494                 return VM_FAULT_FALLBACK;
 495
 496         /* if we are outside of the VMA */
 497         if (pmd_addr < vma->vm_start ||
 498                         (pmd_addr + PMD_SIZE) > vma->vm_end)
 499                 return VM_FAULT_SIGBUS;
 500
 501         pgoff = linear_page_index(vma, pmd_addr);
 502         phys = pgoff_to_phys(dax_dev, pgoff, PMD_SIZE);
 503         if (phys == -1) {
 504                 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
 505                                 pgoff);
 506                 return VM_FAULT_SIGBUS;
 507         }
 508
 509         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 510
 511         return vmf_insert_pfn_pmd(vma, addr, pmd, pfn,
 512                         flags & FAULT_FLAG_WRITE);
 513 }
 514
 515 static int dax_dev_pmd_fault(struct vm_area_struct *vma, unsigned long addr,
 516                 pmd_t *pmd, unsigned int flags)
 517 {
 518         int rc, id;
 519         struct file *filp = vma->vm_file;
 520         struct dax_dev *dax_dev = filp->private_data;
 521
 522         dev_dbg(&dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
 523                         current->comm, (flags & FAULT_FLAG_WRITE)
 524                         ? "write" : "read", vma->vm_start, vma->vm_end);
 525
 526         id = srcu_read_lock(&dax_srcu);
 527         rc = __dax_dev_pmd_fault(dax_dev, vma, addr, pmd, flags);
 528         srcu_read_unlock(&dax_srcu, id);
 529
 530         return rc;
 531 }
 532
 533 static const struct vm_operations_struct dax_dev_vm_ops = {
 534         .fault = dax_dev_fault,
 535         .pmd_fault = dax_dev_pmd_fault,
 536 };
 537
 538 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 539 {
 540         struct dax_dev *dax_dev = filp->private_data;
 541         int rc;
 542
 543         dev_dbg(&dax_dev->dev, "%s\n", __func__);
 544
 545         rc = check_vma(dax_dev, vma, __func__);
 546         if (rc)
 547                 return rc;
 548
 549         vma->vm_ops = &dax_dev_vm_ops;
 550         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 551         return 0;
 552 }
 553
 554 /* return an unmapped area aligned to the dax region specified alignment */
 555 static unsigned long dax_get_unmapped_area(struct file *filp,
 556                 unsigned long addr, unsigned long len, unsigned long pgoff,
 557                 unsigned long flags)
 558 {
 559         unsigned long off, off_end, off_align, len_align, addr_align, align;
 560         struct dax_dev *dax_dev = filp ? filp->private_data : NULL;
 561         struct dax_region *dax_region;
 562
 563         if (!dax_dev || addr)
 564                 goto out;
 565
 566         dax_region = dax_dev->region;
 567         align = dax_region->align;
 568         off = pgoff << PAGE_SHIFT;
 569         off_end = off + len;
 570         off_align = round_up(off, align);
 571
 572         if ((off_end <= off_align) || ((off_end - off_align) < align))
 573                 goto out;
 574
 575         len_align = len + align;
 576         if ((off + len_align) < off)
 577                 goto out;
 578
 579         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 580                         pgoff, flags);
 581         if (!IS_ERR_VALUE(addr_align)) {
 582                 addr_align += (off - addr_align) & (align - 1);
 583                 return addr_align;
 584         }
 585  out:
 586         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 587 }
 588
 589 static int dax_open(struct inode *inode, struct file *filp)
 590 {
 591         struct dax_dev *dax_dev;
 592
 593         dax_dev = container_of(inode->i_cdev, struct dax_dev, cdev);
 594         dev_dbg(&dax_dev->dev, "%s\n", __func__);
 595         inode->i_mapping = dax_dev->inode->i_mapping;
 596         inode->i_mapping->host = dax_dev->inode;
 597         filp->f_mapping = inode->i_mapping;
 598         filp->private_data = dax_dev;
 599         inode->i_flags = S_DAX;
 600
 601         return 0;
 602 }
 603
 604 static int dax_release(struct inode *inode, struct file *filp)
 605 {
 606         struct dax_dev *dax_dev = filp->private_data;
 607
 608         dev_dbg(&dax_dev->dev, "%s\n", __func__);
 609         return 0;
 610 }
 611
 612 static const struct file_operations dax_fops = {
 613         .llseek = noop_llseek,
 614         .owner = THIS_MODULE,
 615         .open = dax_open,
 616         .release = dax_release,
 617         .get_unmapped_area = dax_get_unmapped_area,
 618         .mmap = dax_mmap,
 619 };
 620
 621 static void dax_dev_release(struct device *dev)
 622 {
 623         struct dax_dev *dax_dev = to_dax_dev(dev);
 624         struct dax_region *dax_region = dax_dev->region;
 625
 626         ida_simple_remove(&dax_region->ida, dax_dev->id);
 627         ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));
 628         dax_region_put(dax_region);
 629         iput(dax_dev->inode);
 630         kfree(dax_dev);
 631 }
 632
 633 static void kill_dax_dev(struct dax_dev *dax_dev)
 634 {
 635         struct cdev *cdev = &dax_dev->cdev;
 636
 637         /*
 638          * Note, rcu is not protecting the liveness of dax_dev, rcu is
 639          * ensuring that any fault handlers that might have seen
 640          * dax_dev->alive == true, have completed.  Any fault handlers
 641          * that start after synchronize_srcu() has started will abort
 642          * upon seeing dax_dev->alive == false.
 643          */
 644         dax_dev->alive = false;
 645         synchronize_srcu(&dax_srcu);
 646         unmap_mapping_range(dax_dev->inode->i_mapping, 0, 0, 1);
 647         cdev_del(cdev);
 648 }
 649
 650 static void unregister_dax_dev(void *dev)
 651 {
 652         struct dax_dev *dax_dev = to_dax_dev(dev);
 653
 654         dev_dbg(dev, "%s\n", __func__);
 655
 656         kill_dax_dev(dax_dev);
 657         device_unregister(dev);
 658 }
 659
 660 struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
 661                 struct resource *res, int count)
 662 {
 663         struct device *parent = dax_region->dev;
 664         struct dax_dev *dax_dev;
 665         int rc = 0, minor, i;
 666         struct device *dev;
 667         struct cdev *cdev;
 668         dev_t dev_t;
 669
 670         dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL);
 671         if (!dax_dev)
 672                 return ERR_PTR(-ENOMEM);
 673
 674         for (i = 0; i < count; i++) {
 675                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 676                                 || !IS_ALIGNED(resource_size(&res[i]),
 677                                         dax_region->align)) {
 678                         rc = -EINVAL;
 679                         break;
 680                 }
 681                 dax_dev->res[i].start = res[i].start;
 682                 dax_dev->res[i].end = res[i].end;
 683         }
 684
 685         if (i < count)
 686                 goto err_id;
 687
 688         dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 689         if (dax_dev->id < 0) {
 690                 rc = dax_dev->id;
 691                 goto err_id;
 692         }
 693
 694         minor = ida_simple_get(&dax_minor_ida, 0, 0, GFP_KERNEL);
 695         if (minor < 0) {
 696                 rc = minor;
 697                 goto err_minor;
 698         }
 699
 700         dev_t = MKDEV(MAJOR(dax_devt), minor);
 701         dev = &dax_dev->dev;
 702         dax_dev->inode = dax_inode_get(&dax_dev->cdev, dev_t);
 703         if (!dax_dev->inode) {
 704                 rc = -ENOMEM;
 705                 goto err_inode;
 706         }
 707
 708         /* device_initialize() so cdev can reference kobj parent */
 709         device_initialize(dev);
 710
 711         cdev = &dax_dev->cdev;
 712         cdev_init(cdev, &dax_fops);
 713         cdev->owner = parent->driver->owner;
 714         cdev->kobj.parent = &dev->kobj;
 715         rc = cdev_add(&dax_dev->cdev, dev_t, 1);
 716         if (rc)
 717                 goto err_cdev;
 718
 719         /* from here on we're committed to teardown via dax_dev_release() */
 720         dax_dev->num_resources = count;
 721         dax_dev->alive = true;
 722         dax_dev->region = dax_region;
 723         kref_get(&dax_region->kref);
 724
 725         dev->devt = dev_t;
 726         dev->class = dax_class;
 727         dev->parent = parent;
 728         dev->groups = dax_attribute_groups;
 729         dev->release = dax_dev_release;
 730         dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id);
 731         rc = device_add(dev);
 732         if (rc) {
 733                 kill_dax_dev(dax_dev);
 734                 put_device(dev);
 735                 return ERR_PTR(rc);
 736         }
 737
 738         rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);
 739         if (rc)
 740                 return ERR_PTR(rc);
 741
 742         return dax_dev;
 743
 744  err_cdev:
 745         iput(dax_dev->inode);
 746  err_inode:
 747         ida_simple_remove(&dax_minor_ida, minor);
 748  err_minor:
 749         ida_simple_remove(&dax_region->ida, dax_dev->id);
 750  err_id:
 751         kfree(dax_dev);
 752
 753         return ERR_PTR(rc);
 754 }
 755 EXPORT_SYMBOL_GPL(devm_create_dax_dev);
 756
 757 static int __init dax_init(void)
 758 {
 759         int rc;
 760
 761         rc = dax_inode_init();
 762         if (rc)
 763                 return rc;
 764
 765         nr_dax = max(nr_dax, 256);
 766         rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");
 767         if (rc)
 768                 goto err_chrdev;
 769
 770         dax_class = class_create(THIS_MODULE, "dax");
 771         if (IS_ERR(dax_class)) {
 772                 rc = PTR_ERR(dax_class);
 773                 goto err_class;
 774         }
 775
 776         return 0;
 777
 778  err_class:
 779         unregister_chrdev_region(dax_devt, nr_dax);
 780  err_chrdev:
 781         dax_inode_exit();
 782         return rc;
 783 }
 784
 785 static void __exit dax_exit(void)
 786 {
 787         class_destroy(dax_class);
 788         unregister_chrdev_region(dax_devt, nr_dax);
 789         ida_destroy(&dax_minor_ida);
 790         dax_inode_exit();
 791 }
 792
 793 MODULE_AUTHOR("Intel Corporation");
 794 MODULE_LICENSE("GPL v2");
 795 subsys_initcall(dax_init);
 796 module_exit(dax_exit);