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/magic.h>
  17 #include <linux/mount.h>
  18 #include <linux/pfn_t.h>
  19 #include <linux/hash.h>
  20 #include <linux/cdev.h>
  21 #include <linux/slab.h>
  22 #include <linux/dax.h>
  23 #include <linux/fs.h>
  24 #include <linux/mm.h>
  25 #include "dax.h"
  26
  27 static dev_t dax_devt;
  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 + rcu 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 static ssize_t id_show(struct device *dev,
  80                 struct device_attribute *attr, char *buf)
  81 {
  82         struct dax_region *dax_region;
  83         ssize_t rc = -ENXIO;
  84
  85         device_lock(dev);
  86         dax_region = dev_get_drvdata(dev);
  87         if (dax_region)
  88                 rc = sprintf(buf, "%d\n", dax_region->id);
  89         device_unlock(dev);
  90
  91         return rc;
  92 }
  93 static DEVICE_ATTR_RO(id);
  94
  95 static ssize_t region_size_show(struct device *dev,
  96                 struct device_attribute *attr, char *buf)
  97 {
  98         struct dax_region *dax_region;
  99         ssize_t rc = -ENXIO;
 100
 101         device_lock(dev);
 102         dax_region = dev_get_drvdata(dev);
 103         if (dax_region)
 104                 rc = sprintf(buf, "%llu\n", (unsigned long long)
 105                                 resource_size(&dax_region->res));
 106         device_unlock(dev);
 107
 108         return rc;
 109 }
 110 static struct device_attribute dev_attr_region_size = __ATTR(size, 0444,
 111                 region_size_show, NULL);
 112
 113 static ssize_t align_show(struct device *dev,
 114                 struct device_attribute *attr, char *buf)
 115 {
 116         struct dax_region *dax_region;
 117         ssize_t rc = -ENXIO;
 118
 119         device_lock(dev);
 120         dax_region = dev_get_drvdata(dev);
 121         if (dax_region)
 122                 rc = sprintf(buf, "%u\n", dax_region->align);
 123         device_unlock(dev);
 124
 125         return rc;
 126 }
 127 static DEVICE_ATTR_RO(align);
 128
 129 static struct attribute *dax_region_attributes[] = {
 130         &dev_attr_region_size.attr,
 131         &dev_attr_align.attr,
 132         &dev_attr_id.attr,
 133         NULL,
 134 };
 135
 136 static const struct attribute_group dax_region_attribute_group = {
 137         .name = "dax_region",
 138         .attrs = dax_region_attributes,
 139 };
 140
 141 static const struct attribute_group *dax_region_attribute_groups[] = {
 142         &dax_region_attribute_group,
 143         NULL,
 144 };
 145
 146 static struct inode *dax_alloc_inode(struct super_block *sb)
 147 {
 148         return kmem_cache_alloc(dax_cache, GFP_KERNEL);
 149 }
 150
 151 static void dax_i_callback(struct rcu_head *head)
 152 {
 153         struct inode *inode = container_of(head, struct inode, i_rcu);
 154
 155         kmem_cache_free(dax_cache, inode);
 156 }
 157
 158 static void dax_destroy_inode(struct inode *inode)
 159 {
 160         call_rcu(&inode->i_rcu, dax_i_callback);
 161 }
 162
 163 static const struct super_operations dax_sops = {
 164         .statfs = simple_statfs,
 165         .alloc_inode = dax_alloc_inode,
 166         .destroy_inode = dax_destroy_inode,
 167         .drop_inode = generic_delete_inode,
 168 };
 169
 170 static struct dentry *dax_mount(struct file_system_type *fs_type,
 171                 int flags, const char *dev_name, void *data)
 172 {
 173         return mount_pseudo(fs_type, "dax:", &dax_sops, NULL, DAXFS_MAGIC);
 174 }
 175
 176 static struct file_system_type dax_type = {
 177         .name = "dax",
 178         .mount = dax_mount,
 179         .kill_sb = kill_anon_super,
 180 };
 181
 182 static int dax_test(struct inode *inode, void *data)
 183 {
 184         return inode->i_cdev == data;
 185 }
 186
 187 static int dax_set(struct inode *inode, void *data)
 188 {
 189         inode->i_cdev = data;
 190         return 0;
 191 }
 192
 193 static struct inode *dax_inode_get(struct cdev *cdev, dev_t devt)
 194 {
 195         struct inode *inode;
 196
 197         inode = iget5_locked(dax_superblock, hash_32(devt + DAXFS_MAGIC, 31),
 198                         dax_test, dax_set, cdev);
 199
 200         if (!inode)
 201                 return NULL;
 202
 203         if (inode->i_state & I_NEW) {
 204                 inode->i_mode = S_IFCHR;
 205                 inode->i_flags = S_DAX;
 206                 inode->i_rdev = devt;
 207                 mapping_set_gfp_mask(&inode->i_data, GFP_USER);
 208                 unlock_new_inode(inode);
 209         }
 210         return inode;
 211 }
 212
 213 static void init_once(void *inode)
 214 {
 215         inode_init_once(inode);
 216 }
 217
 218 static int dax_inode_init(void)
 219 {
 220         int rc;
 221
 222         dax_cache = kmem_cache_create("dax_cache", sizeof(struct inode), 0,
 223                         (SLAB_HWCACHE_ALIGN|SLAB_RECLAIM_ACCOUNT|
 224                          SLAB_MEM_SPREAD|SLAB_ACCOUNT),
 225                         init_once);
 226         if (!dax_cache)
 227                 return -ENOMEM;
 228
 229         rc = register_filesystem(&dax_type);
 230         if (rc)
 231                 goto err_register_fs;
 232
 233         dax_mnt = kern_mount(&dax_type);
 234         if (IS_ERR(dax_mnt)) {
 235                 rc = PTR_ERR(dax_mnt);
 236                 goto err_mount;
 237         }
 238         dax_superblock = dax_mnt->mnt_sb;
 239
 240         return 0;
 241
 242  err_mount:
 243         unregister_filesystem(&dax_type);
 244  err_register_fs:
 245         kmem_cache_destroy(dax_cache);
 246
 247         return rc;
 248 }
 249
 250 static void dax_inode_exit(void)
 251 {
 252         kern_unmount(dax_mnt);
 253         unregister_filesystem(&dax_type);
 254         kmem_cache_destroy(dax_cache);
 255 }
 256
 257 static void dax_region_free(struct kref *kref)
 258 {
 259         struct dax_region *dax_region;
 260
 261         dax_region = container_of(kref, struct dax_region, kref);
 262         kfree(dax_region);
 263 }
 264
 265 void dax_region_put(struct dax_region *dax_region)
 266 {
 267         kref_put(&dax_region->kref, dax_region_free);
 268 }
 269 EXPORT_SYMBOL_GPL(dax_region_put);
 270
 271 static void dax_region_unregister(void *region)
 272 {
 273         struct dax_region *dax_region = region;
 274
 275         sysfs_remove_groups(&dax_region->dev->kobj,
 276                         dax_region_attribute_groups);
 277         dax_region_put(dax_region);
 278 }
 279
 280 struct dax_region *alloc_dax_region(struct device *parent, int region_id,
 281                 struct resource *res, unsigned int align, void *addr,
 282                 unsigned long pfn_flags)
 283 {
 284         struct dax_region *dax_region;
 285
 286         /*
 287          * The DAX core assumes that it can store its private data in
 288          * parent->driver_data. This WARN is a reminder / safeguard for
 289          * developers of device-dax drivers.
 290          */
 291         if (dev_get_drvdata(parent)) {
 292                 dev_WARN(parent, "dax core failed to setup private data\n");
 293                 return NULL;
 294         }
 295
 296         if (!IS_ALIGNED(res->start, align)
 297                         || !IS_ALIGNED(resource_size(res), align))
 298                 return NULL;
 299
 300         dax_region = kzalloc(sizeof(*dax_region), GFP_KERNEL);
 301         if (!dax_region)
 302                 return NULL;
 303
 304         dev_set_drvdata(parent, dax_region);
 305         memcpy(&dax_region->res, res, sizeof(*res));
 306         dax_region->pfn_flags = pfn_flags;
 307         kref_init(&dax_region->kref);
 308         dax_region->id = region_id;
 309         ida_init(&dax_region->ida);
 310         dax_region->align = align;
 311         dax_region->dev = parent;
 312         dax_region->base = addr;
 313         if (sysfs_create_groups(&parent->kobj, dax_region_attribute_groups)) {
 314                 kfree(dax_region);
 315                 return NULL;;
 316         }
 317
 318         kref_get(&dax_region->kref);
 319         if (devm_add_action_or_reset(parent, dax_region_unregister, dax_region))
 320                 return NULL;
 321         return dax_region;
 322 }
 323 EXPORT_SYMBOL_GPL(alloc_dax_region);
 324
 325 static struct dax_dev *to_dax_dev(struct device *dev)
 326 {
 327         return container_of(dev, struct dax_dev, dev);
 328 }
 329
 330 static ssize_t size_show(struct device *dev,
 331                 struct device_attribute *attr, char *buf)
 332 {
 333         struct dax_dev *dax_dev = to_dax_dev(dev);
 334         unsigned long long size = 0;
 335         int i;
 336
 337         for (i = 0; i < dax_dev->num_resources; i++)
 338                 size += resource_size(&dax_dev->res[i]);
 339
 340         return sprintf(buf, "%llu\n", size);
 341 }
 342 static DEVICE_ATTR_RO(size);
 343
 344 static struct attribute *dax_device_attributes[] = {
 345         &dev_attr_size.attr,
 346         NULL,
 347 };
 348
 349 static const struct attribute_group dax_device_attribute_group = {
 350         .attrs = dax_device_attributes,
 351 };
 352
 353 static const struct attribute_group *dax_attribute_groups[] = {
 354         &dax_device_attribute_group,
 355         NULL,
 356 };
 357
 358 static int check_vma(struct dax_dev *dax_dev, struct vm_area_struct *vma,
 359                 const char *func)
 360 {
 361         struct dax_region *dax_region = dax_dev->region;
 362         struct device *dev = &dax_dev->dev;
 363         unsigned long mask;
 364
 365         if (!dax_dev->alive)
 366                 return -ENXIO;
 367
 368         /* prevent private mappings from being established */
 369         if ((vma->vm_flags & VM_MAYSHARE) != VM_MAYSHARE) {
 370                 dev_info(dev, "%s: %s: fail, attempted private mapping\n",
 371                                 current->comm, func);
 372                 return -EINVAL;
 373         }
 374
 375         mask = dax_region->align - 1;
 376         if (vma->vm_start & mask || vma->vm_end & mask) {
 377                 dev_info(dev, "%s: %s: fail, unaligned vma (%#lx - %#lx, %#lx)\n",
 378                                 current->comm, func, vma->vm_start, vma->vm_end,
 379                                 mask);
 380                 return -EINVAL;
 381         }
 382
 383         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) == PFN_DEV
 384                         && (vma->vm_flags & VM_DONTCOPY) == 0) {
 385                 dev_info(dev, "%s: %s: fail, dax range requires MADV_DONTFORK\n",
 386                                 current->comm, func);
 387                 return -EINVAL;
 388         }
 389
 390         if (!vma_is_dax(vma)) {
 391                 dev_info(dev, "%s: %s: fail, vma is not DAX capable\n",
 392                                 current->comm, func);
 393                 return -EINVAL;
 394         }
 395
 396         return 0;
 397 }
 398
 399 static phys_addr_t pgoff_to_phys(struct dax_dev *dax_dev, pgoff_t pgoff,
 400                 unsigned long size)
 401 {
 402         struct resource *res;
 403         phys_addr_t phys;
 404         int i;
 405
 406         for (i = 0; i < dax_dev->num_resources; i++) {
 407                 res = &dax_dev->res[i];
 408                 phys = pgoff * PAGE_SIZE + res->start;
 409                 if (phys >= res->start && phys <= res->end)
 410                         break;
 411                 pgoff -= PHYS_PFN(resource_size(res));
 412         }
 413
 414         if (i < dax_dev->num_resources) {
 415                 res = &dax_dev->res[i];
 416                 if (phys + size - 1 <= res->end)
 417                         return phys;
 418         }
 419
 420         return -1;
 421 }
 422
 423 static int __dax_dev_pte_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
 424 {
 425         struct device *dev = &dax_dev->dev;
 426         struct dax_region *dax_region;
 427         int rc = VM_FAULT_SIGBUS;
 428         phys_addr_t phys;
 429         pfn_t pfn;
 430
 431         if (check_vma(dax_dev, vmf->vma, __func__))
 432                 return VM_FAULT_SIGBUS;
 433
 434         dax_region = dax_dev->region;
 435         if (dax_region->align > PAGE_SIZE) {
 436                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 437                 return VM_FAULT_SIGBUS;
 438         }
 439
 440         phys = pgoff_to_phys(dax_dev, vmf->pgoff, PAGE_SIZE);
 441         if (phys == -1) {
 442                 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
 443                                 vmf->pgoff);
 444                 return VM_FAULT_SIGBUS;
 445         }
 446
 447         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 448
 449         rc = vm_insert_mixed(vmf->vma, vmf->address, pfn);
 450
 451         if (rc == -ENOMEM)
 452                 return VM_FAULT_OOM;
 453         if (rc < 0 && rc != -EBUSY)
 454                 return VM_FAULT_SIGBUS;
 455
 456         return VM_FAULT_NOPAGE;
 457 }
 458
 459 static int __dax_dev_pmd_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
 460 {
 461         unsigned long pmd_addr = vmf->address & PMD_MASK;
 462         struct device *dev = &dax_dev->dev;
 463         struct dax_region *dax_region;
 464         phys_addr_t phys;
 465         pgoff_t pgoff;
 466         pfn_t pfn;
 467
 468         if (check_vma(dax_dev, vmf->vma, __func__))
 469                 return VM_FAULT_SIGBUS;
 470
 471         dax_region = dax_dev->region;
 472         if (dax_region->align > PMD_SIZE) {
 473                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 474                 return VM_FAULT_SIGBUS;
 475         }
 476
 477         /* dax pmd mappings require pfn_t_devmap() */
 478         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 479                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 480                 return VM_FAULT_SIGBUS;
 481         }
 482
 483         pgoff = linear_page_index(vmf->vma, pmd_addr);
 484         phys = pgoff_to_phys(dax_dev, pgoff, PMD_SIZE);
 485         if (phys == -1) {
 486                 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
 487                                 pgoff);
 488                 return VM_FAULT_SIGBUS;
 489         }
 490
 491         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 492
 493         return vmf_insert_pfn_pmd(vmf->vma, vmf->address, vmf->pmd, pfn,
 494                         vmf->flags & FAULT_FLAG_WRITE);
 495 }
 496
 497 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
 498 static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
 499 {
 500         unsigned long pud_addr = vmf->address & PUD_MASK;
 501         struct device *dev = &dax_dev->dev;
 502         struct dax_region *dax_region;
 503         phys_addr_t phys;
 504         pgoff_t pgoff;
 505         pfn_t pfn;
 506
 507         if (check_vma(dax_dev, vmf->vma, __func__))
 508                 return VM_FAULT_SIGBUS;
 509
 510         dax_region = dax_dev->region;
 511         if (dax_region->align > PUD_SIZE) {
 512                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 513                 return VM_FAULT_SIGBUS;
 514         }
 515
 516         /* dax pud mappings require pfn_t_devmap() */
 517         if ((dax_region->pfn_flags & (PFN_DEV|PFN_MAP)) != (PFN_DEV|PFN_MAP)) {
 518                 dev_dbg(dev, "%s: alignment > fault size\n", __func__);
 519                 return VM_FAULT_SIGBUS;
 520         }
 521
 522         pgoff = linear_page_index(vmf->vma, pud_addr);
 523         phys = pgoff_to_phys(dax_dev, pgoff, PUD_SIZE);
 524         if (phys == -1) {
 525                 dev_dbg(dev, "%s: phys_to_pgoff(%#lx) failed\n", __func__,
 526                                 pgoff);
 527                 return VM_FAULT_SIGBUS;
 528         }
 529
 530         pfn = phys_to_pfn_t(phys, dax_region->pfn_flags);
 531
 532         return vmf_insert_pfn_pud(vmf->vma, vmf->address, vmf->pud, pfn,
 533                         vmf->flags & FAULT_FLAG_WRITE);
 534 }
 535 #else
 536 static int __dax_dev_pud_fault(struct dax_dev *dax_dev, struct vm_fault *vmf)
 537 {
 538         return VM_FAULT_FALLBACK;
 539 }
 540 #endif /* !CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
 541
 542 static int dax_dev_huge_fault(struct vm_fault *vmf,
 543                 enum page_entry_size pe_size)
 544 {
 545         int rc;
 546         struct file *filp = vmf->vma->vm_file;
 547         struct dax_dev *dax_dev = filp->private_data;
 548
 549         dev_dbg(&dax_dev->dev, "%s: %s: %s (%#lx - %#lx)\n", __func__,
 550                         current->comm, (vmf->flags & FAULT_FLAG_WRITE)
 551                         ? "write" : "read",
 552                         vmf->vma->vm_start, vmf->vma->vm_end);
 553
 554         rcu_read_lock();
 555         switch (pe_size) {
 556         case PE_SIZE_PTE:
 557                 rc = __dax_dev_pte_fault(dax_dev, vmf);
 558                 break;
 559         case PE_SIZE_PMD:
 560                 rc = __dax_dev_pmd_fault(dax_dev, vmf);
 561                 break;
 562         case PE_SIZE_PUD:
 563                 rc = __dax_dev_pud_fault(dax_dev, vmf);
 564                 break;
 565         default:
 566                 return VM_FAULT_FALLBACK;
 567         }
 568         rcu_read_unlock();
 569
 570         return rc;
 571 }
 572
 573 static int dax_dev_fault(struct vm_fault *vmf)
 574 {
 575         return dax_dev_huge_fault(vmf, PE_SIZE_PTE);
 576 }
 577
 578 static const struct vm_operations_struct dax_dev_vm_ops = {
 579         .fault = dax_dev_fault,
 580         .huge_fault = dax_dev_huge_fault,
 581 };
 582
 583 static int dax_mmap(struct file *filp, struct vm_area_struct *vma)
 584 {
 585         struct dax_dev *dax_dev = filp->private_data;
 586         int rc;
 587
 588         dev_dbg(&dax_dev->dev, "%s\n", __func__);
 589
 590         rc = check_vma(dax_dev, vma, __func__);
 591         if (rc)
 592                 return rc;
 593
 594         vma->vm_ops = &dax_dev_vm_ops;
 595         vma->vm_flags |= VM_MIXEDMAP | VM_HUGEPAGE;
 596         return 0;
 597 }
 598
 599 /* return an unmapped area aligned to the dax region specified alignment */
 600 static unsigned long dax_get_unmapped_area(struct file *filp,
 601                 unsigned long addr, unsigned long len, unsigned long pgoff,
 602                 unsigned long flags)
 603 {
 604         unsigned long off, off_end, off_align, len_align, addr_align, align;
 605         struct dax_dev *dax_dev = filp ? filp->private_data : NULL;
 606         struct dax_region *dax_region;
 607
 608         if (!dax_dev || addr)
 609                 goto out;
 610
 611         dax_region = dax_dev->region;
 612         align = dax_region->align;
 613         off = pgoff << PAGE_SHIFT;
 614         off_end = off + len;
 615         off_align = round_up(off, align);
 616
 617         if ((off_end <= off_align) || ((off_end - off_align) < align))
 618                 goto out;
 619
 620         len_align = len + align;
 621         if ((off + len_align) < off)
 622                 goto out;
 623
 624         addr_align = current->mm->get_unmapped_area(filp, addr, len_align,
 625                         pgoff, flags);
 626         if (!IS_ERR_VALUE(addr_align)) {
 627                 addr_align += (off - addr_align) & (align - 1);
 628                 return addr_align;
 629         }
 630  out:
 631         return current->mm->get_unmapped_area(filp, addr, len, pgoff, flags);
 632 }
 633
 634 static int dax_open(struct inode *inode, struct file *filp)
 635 {
 636         struct dax_dev *dax_dev;
 637
 638         dax_dev = container_of(inode->i_cdev, struct dax_dev, cdev);
 639         dev_dbg(&dax_dev->dev, "%s\n", __func__);
 640         inode->i_mapping = dax_dev->inode->i_mapping;
 641         inode->i_mapping->host = dax_dev->inode;
 642         filp->f_mapping = inode->i_mapping;
 643         filp->private_data = dax_dev;
 644         inode->i_flags = S_DAX;
 645
 646         return 0;
 647 }
 648
 649 static int dax_release(struct inode *inode, struct file *filp)
 650 {
 651         struct dax_dev *dax_dev = filp->private_data;
 652
 653         dev_dbg(&dax_dev->dev, "%s\n", __func__);
 654         return 0;
 655 }
 656
 657 static const struct file_operations dax_fops = {
 658         .llseek = noop_llseek,
 659         .owner = THIS_MODULE,
 660         .open = dax_open,
 661         .release = dax_release,
 662         .get_unmapped_area = dax_get_unmapped_area,
 663         .mmap = dax_mmap,
 664 };
 665
 666 static void dax_dev_release(struct device *dev)
 667 {
 668         struct dax_dev *dax_dev = to_dax_dev(dev);
 669         struct dax_region *dax_region = dax_dev->region;
 670
 671         ida_simple_remove(&dax_region->ida, dax_dev->id);
 672         ida_simple_remove(&dax_minor_ida, MINOR(dev->devt));
 673         dax_region_put(dax_region);
 674         iput(dax_dev->inode);
 675         kfree(dax_dev);
 676 }
 677
 678 static void unregister_dax_dev(void *dev)
 679 {
 680         struct dax_dev *dax_dev = to_dax_dev(dev);
 681         struct cdev *cdev = &dax_dev->cdev;
 682
 683         dev_dbg(dev, "%s\n", __func__);
 684
 685         /*
 686          * Note, rcu is not protecting the liveness of dax_dev, rcu is
 687          * ensuring that any fault handlers that might have seen
 688          * dax_dev->alive == true, have completed.  Any fault handlers
 689          * that start after synchronize_rcu() has started will abort
 690          * upon seeing dax_dev->alive == false.
 691          */
 692         dax_dev->alive = false;
 693         synchronize_rcu();
 694         unmap_mapping_range(dax_dev->inode->i_mapping, 0, 0, 1);
 695         cdev_del(cdev);
 696         device_unregister(dev);
 697 }
 698
 699 struct dax_dev *devm_create_dax_dev(struct dax_region *dax_region,
 700                 struct resource *res, int count)
 701 {
 702         struct device *parent = dax_region->dev;
 703         struct dax_dev *dax_dev;
 704         int rc = 0, minor, i;
 705         struct device *dev;
 706         struct cdev *cdev;
 707         dev_t dev_t;
 708
 709         dax_dev = kzalloc(sizeof(*dax_dev) + sizeof(*res) * count, GFP_KERNEL);
 710         if (!dax_dev)
 711                 return ERR_PTR(-ENOMEM);
 712
 713         for (i = 0; i < count; i++) {
 714                 if (!IS_ALIGNED(res[i].start, dax_region->align)
 715                                 || !IS_ALIGNED(resource_size(&res[i]),
 716                                         dax_region->align)) {
 717                         rc = -EINVAL;
 718                         break;
 719                 }
 720                 dax_dev->res[i].start = res[i].start;
 721                 dax_dev->res[i].end = res[i].end;
 722         }
 723
 724         if (i < count)
 725                 goto err_id;
 726
 727         dax_dev->id = ida_simple_get(&dax_region->ida, 0, 0, GFP_KERNEL);
 728         if (dax_dev->id < 0) {
 729                 rc = dax_dev->id;
 730                 goto err_id;
 731         }
 732
 733         minor = ida_simple_get(&dax_minor_ida, 0, 0, GFP_KERNEL);
 734         if (minor < 0) {
 735                 rc = minor;
 736                 goto err_minor;
 737         }
 738
 739         dev_t = MKDEV(MAJOR(dax_devt), minor);
 740         dev = &dax_dev->dev;
 741         dax_dev->inode = dax_inode_get(&dax_dev->cdev, dev_t);
 742         if (!dax_dev->inode) {
 743                 rc = -ENOMEM;
 744                 goto err_inode;
 745         }
 746
 747         /* device_initialize() so cdev can reference kobj parent */
 748         device_initialize(dev);
 749
 750         cdev = &dax_dev->cdev;
 751         cdev_init(cdev, &dax_fops);
 752         cdev->owner = parent->driver->owner;
 753         cdev->kobj.parent = &dev->kobj;
 754         rc = cdev_add(&dax_dev->cdev, dev_t, 1);
 755         if (rc)
 756                 goto err_cdev;
 757
 758         /* from here on we're committed to teardown via dax_dev_release() */
 759         dax_dev->num_resources = count;
 760         dax_dev->alive = true;
 761         dax_dev->region = dax_region;
 762         kref_get(&dax_region->kref);
 763
 764         dev->devt = dev_t;
 765         dev->class = dax_class;
 766         dev->parent = parent;
 767         dev->groups = dax_attribute_groups;
 768         dev->release = dax_dev_release;
 769         dev_set_name(dev, "dax%d.%d", dax_region->id, dax_dev->id);
 770         rc = device_add(dev);
 771         if (rc) {
 772                 put_device(dev);
 773                 return ERR_PTR(rc);
 774         }
 775
 776         rc = devm_add_action_or_reset(dax_region->dev, unregister_dax_dev, dev);
 777         if (rc)
 778                 return ERR_PTR(rc);
 779
 780         return dax_dev;
 781
 782  err_cdev:
 783         iput(dax_dev->inode);
 784  err_inode:
 785         ida_simple_remove(&dax_minor_ida, minor);
 786  err_minor:
 787         ida_simple_remove(&dax_region->ida, dax_dev->id);
 788  err_id:
 789         kfree(dax_dev);
 790
 791         return ERR_PTR(rc);
 792 }
 793 EXPORT_SYMBOL_GPL(devm_create_dax_dev);
 794
 795 static int __init dax_init(void)
 796 {
 797         int rc;
 798
 799         rc = dax_inode_init();
 800         if (rc)
 801                 return rc;
 802
 803         nr_dax = max(nr_dax, 256);
 804         rc = alloc_chrdev_region(&dax_devt, 0, nr_dax, "dax");
 805         if (rc)
 806                 goto err_chrdev;
 807
 808         dax_class = class_create(THIS_MODULE, "dax");
 809         if (IS_ERR(dax_class)) {
 810                 rc = PTR_ERR(dax_class);
 811                 goto err_class;
 812         }
 813
 814         return 0;
 815
 816  err_class:
 817         unregister_chrdev_region(dax_devt, nr_dax);
 818  err_chrdev:
 819         dax_inode_exit();
 820         return rc;
 821 }
 822
 823 static void __exit dax_exit(void)
 824 {
 825         class_destroy(dax_class);
 826         unregister_chrdev_region(dax_devt, nr_dax);
 827         ida_destroy(&dax_minor_ida);
 828         dax_inode_exit();
 829 }
 830
 831 MODULE_AUTHOR("Intel Corporation");
 832 MODULE_LICENSE("GPL v2");
 833 subsys_initcall(dax_init);
 834 module_exit(dax_exit);