fs/hugetlbfs/inode.c

   1 /*
   2  * hugetlbpage-backed filesystem.  Based on ramfs.
   3  *
   4  * Nadia Yvette Chambers, 2002
   5  *
   6  * Copyright (C) 2002 Linus Torvalds.
   7  * License: GPL
   8  */
   9
  10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  11
  12 #include <linux/thread_info.h>
  13 #include <asm/current.h>
  14 #include <linux/sched/signal.h>         /* remove ASAP */
  15 #include <linux/falloc.h>
  16 #include <linux/fs.h>
  17 #include <linux/mount.h>
  18 #include <linux/file.h>
  19 #include <linux/kernel.h>
  20 #include <linux/writeback.h>
  21 #include <linux/pagemap.h>
  22 #include <linux/highmem.h>
  23 #include <linux/init.h>
  24 #include <linux/string.h>
  25 #include <linux/capability.h>
  26 #include <linux/ctype.h>
  27 #include <linux/backing-dev.h>
  28 #include <linux/hugetlb.h>
  29 #include <linux/pagevec.h>
  30 #include <linux/fs_parser.h>
  31 #include <linux/mman.h>
  32 #include <linux/slab.h>
  33 #include <linux/dnotify.h>
  34 #include <linux/statfs.h>
  35 #include <linux/security.h>
  36 #include <linux/magic.h>
  37 #include <linux/migrate.h>
  38 #include <linux/uio.h>
  39
  40 #include <linux/uaccess.h>
  41
  42 static const struct super_operations hugetlbfs_ops;
  43 static const struct address_space_operations hugetlbfs_aops;
  44 const struct file_operations hugetlbfs_file_operations;
  45 static const struct inode_operations hugetlbfs_dir_inode_operations;
  46 static const struct inode_operations hugetlbfs_inode_operations;
  47
  48 enum hugetlbfs_size_type { NO_SIZE, SIZE_STD, SIZE_PERCENT };
  49
  50 struct hugetlbfs_fs_context {
  51         struct hstate           *hstate;
  52         unsigned long long      max_size_opt;
  53         unsigned long long      min_size_opt;
  54         long                    max_hpages;
  55         long                    nr_inodes;
  56         long                    min_hpages;
  57         enum hugetlbfs_size_type max_val_type;
  58         enum hugetlbfs_size_type min_val_type;
  59         kuid_t                  uid;
  60         kgid_t                  gid;
  61         umode_t                 mode;
  62 };
  63
  64 int sysctl_hugetlb_shm_group;
  65
  66 enum hugetlb_param {
  67         Opt_gid,
  68         Opt_min_size,
  69         Opt_mode,
  70         Opt_nr_inodes,
  71         Opt_pagesize,
  72         Opt_size,
  73         Opt_uid,
  74 };
  75
  76 static const struct fs_parameter_spec hugetlb_param_specs[] = {
  77         fsparam_u32   ("gid",           Opt_gid),
  78         fsparam_string("min_size",      Opt_min_size),
  79         fsparam_u32   ("mode",          Opt_mode),
  80         fsparam_string("nr_inodes",     Opt_nr_inodes),
  81         fsparam_string("pagesize",      Opt_pagesize),
  82         fsparam_string("size",          Opt_size),
  83         fsparam_u32   ("uid",           Opt_uid),
  84         {}
  85 };
  86
  87 static const struct fs_parameter_description hugetlb_fs_parameters = {
  88         .name           = "hugetlbfs",
  89         .specs          = hugetlb_param_specs,
  90 };
  91
  92 #ifdef CONFIG_NUMA
  93 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
  94                                         struct inode *inode, pgoff_t index)
  95 {
  96         vma->vm_policy = mpol_shared_policy_lookup(&HUGETLBFS_I(inode)->policy,
  97                                                         index);
  98 }
  99
 100 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
 101 {
 102         mpol_cond_put(vma->vm_policy);
 103 }
 104 #else
 105 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
 106                                         struct inode *inode, pgoff_t index)
 107 {
 108 }
 109
 110 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
 111 {
 112 }
 113 #endif
 114
 115 static void huge_pagevec_release(struct pagevec *pvec)
 116 {
 117         int i;
 118
 119         for (i = 0; i < pagevec_count(pvec); ++i)
 120                 put_page(pvec->pages[i]);
 121
 122         pagevec_reinit(pvec);
 123 }
 124
 125 /*
 126  * Mask used when checking the page offset value passed in via system
 127  * calls.  This value will be converted to a loff_t which is signed.
 128  * Therefore, we want to check the upper PAGE_SHIFT + 1 bits of the
 129  * value.  The extra bit (- 1 in the shift value) is to take the sign
 130  * bit into account.
 131  */
 132 #define PGOFF_LOFFT_MAX \
 133         (((1UL << (PAGE_SHIFT + 1)) - 1) <<  (BITS_PER_LONG - (PAGE_SHIFT + 1)))
 134
 135 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 136 {
 137         struct inode *inode = file_inode(file);
 138         loff_t len, vma_len;
 139         int ret;
 140         struct hstate *h = hstate_file(file);
 141
 142         /*
 143          * vma address alignment (but not the pgoff alignment) has
 144          * already been checked by prepare_hugepage_range.  If you add
 145          * any error returns here, do so after setting VM_HUGETLB, so
 146          * is_vm_hugetlb_page tests below unmap_region go the right
 147          * way when do_mmap_pgoff unwinds (may be important on powerpc
 148          * and ia64).
 149          */
 150         vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
 151         vma->vm_ops = &hugetlb_vm_ops;
 152
 153         /*
 154          * page based offset in vm_pgoff could be sufficiently large to
 155          * overflow a loff_t when converted to byte offset.  This can
 156          * only happen on architectures where sizeof(loff_t) ==
 157          * sizeof(unsigned long).  So, only check in those instances.
 158          */
 159         if (sizeof(unsigned long) == sizeof(loff_t)) {
 160                 if (vma->vm_pgoff & PGOFF_LOFFT_MAX)
 161                         return -EINVAL;
 162         }
 163
 164         /* must be huge page aligned */
 165         if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))
 166                 return -EINVAL;
 167
 168         vma_len = (loff_t)(vma->vm_end - vma->vm_start);
 169         len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 170         /* check for overflow */
 171         if (len < vma_len)
 172                 return -EINVAL;
 173
 174         inode_lock(inode);
 175         file_accessed(file);
 176
 177         ret = -ENOMEM;
 178         if (hugetlb_reserve_pages(inode,
 179                                 vma->vm_pgoff >> huge_page_order(h),
 180                                 len >> huge_page_shift(h), vma,
 181                                 vma->vm_flags))
 182                 goto out;
 183
 184         ret = 0;
 185         if (vma->vm_flags & VM_WRITE && inode->i_size < len)
 186                 i_size_write(inode, len);
 187 out:
 188         inode_unlock(inode);
 189
 190         return ret;
 191 }
 192
 193 /*
 194  * Called under down_write(mmap_sem).
 195  */
 196
 197 #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 198 static unsigned long
 199 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 200                 unsigned long len, unsigned long pgoff, unsigned long flags)
 201 {
 202         struct mm_struct *mm = current->mm;
 203         struct vm_area_struct *vma;
 204         struct hstate *h = hstate_file(file);
 205         struct vm_unmapped_area_info info;
 206
 207         if (len & ~huge_page_mask(h))
 208                 return -EINVAL;
 209         if (len > TASK_SIZE)
 210                 return -ENOMEM;
 211
 212         if (flags & MAP_FIXED) {
 213                 if (prepare_hugepage_range(file, addr, len))
 214                         return -EINVAL;
 215                 return addr;
 216         }
 217
 218         if (addr) {
 219                 addr = ALIGN(addr, huge_page_size(h));
 220                 vma = find_vma(mm, addr);
 221                 if (TASK_SIZE - len >= addr &&
 222                     (!vma || addr + len <= vm_start_gap(vma)))
 223                         return addr;
 224         }
 225
 226         info.flags = 0;
 227         info.length = len;
 228         info.low_limit = TASK_UNMAPPED_BASE;
 229         info.high_limit = TASK_SIZE;
 230         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 231         info.align_offset = 0;
 232         return vm_unmapped_area(&info);
 233 }
 234 #endif
 235
 236 static size_t
 237 hugetlbfs_read_actor(struct page *page, unsigned long offset,
 238                         struct iov_iter *to, unsigned long size)
 239 {
 240         size_t copied = 0;
 241         int i, chunksize;
 242
 243         /* Find which 4k chunk and offset with in that chunk */
 244         i = offset >> PAGE_SHIFT;
 245         offset = offset & ~PAGE_MASK;
 246
 247         while (size) {
 248                 size_t n;
 249                 chunksize = PAGE_SIZE;
 250                 if (offset)
 251                         chunksize -= offset;
 252                 if (chunksize > size)
 253                         chunksize = size;
 254                 n = copy_page_to_iter(&page[i], offset, chunksize, to);
 255                 copied += n;
 256                 if (n != chunksize)
 257                         return copied;
 258                 offset = 0;
 259                 size -= chunksize;
 260                 i++;
 261         }
 262         return copied;
 263 }
 264
 265 /*
 266  * Support for read() - Find the page attached to f_mapping and copy out the
 267  * data. Its *very* similar to do_generic_mapping_read(), we can't use that
 268  * since it has PAGE_SIZE assumptions.
 269  */
 270 static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 271 {
 272         struct file *file = iocb->ki_filp;
 273         struct hstate *h = hstate_file(file);
 274         struct address_space *mapping = file->f_mapping;
 275         struct inode *inode = mapping->host;
 276         unsigned long index = iocb->ki_pos >> huge_page_shift(h);
 277         unsigned long offset = iocb->ki_pos & ~huge_page_mask(h);
 278         unsigned long end_index;
 279         loff_t isize;
 280         ssize_t retval = 0;
 281
 282         while (iov_iter_count(to)) {
 283                 struct page *page;
 284                 size_t nr, copied;
 285
 286                 /* nr is the maximum number of bytes to copy from this page */
 287                 nr = huge_page_size(h);
 288                 isize = i_size_read(inode);
 289                 if (!isize)
 290                         break;
 291                 end_index = (isize - 1) >> huge_page_shift(h);
 292                 if (index > end_index)
 293                         break;
 294                 if (index == end_index) {
 295                         nr = ((isize - 1) & ~huge_page_mask(h)) + 1;
 296                         if (nr <= offset)
 297                                 break;
 298                 }
 299                 nr = nr - offset;
 300
 301                 /* Find the page */
 302                 page = find_lock_page(mapping, index);
 303                 if (unlikely(page == NULL)) {
 304                         /*
 305                          * We have a HOLE, zero out the user-buffer for the
 306                          * length of the hole or request.
 307                          */
 308                         copied = iov_iter_zero(nr, to);
 309                 } else {
 310                         unlock_page(page);
 311
 312                         /*
 313                          * We have the page, copy it to user space buffer.
 314                          */
 315                         copied = hugetlbfs_read_actor(page, offset, to, nr);
 316                         put_page(page);
 317                 }
 318                 offset += copied;
 319                 retval += copied;
 320                 if (copied != nr && iov_iter_count(to)) {
 321                         if (!retval)
 322                                 retval = -EFAULT;
 323                         break;
 324                 }
 325                 index += offset >> huge_page_shift(h);
 326                 offset &= ~huge_page_mask(h);
 327         }
 328         iocb->ki_pos = ((loff_t)index << huge_page_shift(h)) + offset;
 329         return retval;
 330 }
 331
 332 static int hugetlbfs_write_begin(struct file *file,
 333                         struct address_space *mapping,
 334                         loff_t pos, unsigned len, unsigned flags,
 335                         struct page **pagep, void **fsdata)
 336 {
 337         return -EINVAL;
 338 }
 339
 340 static int hugetlbfs_write_end(struct file *file, struct address_space *mapping,
 341                         loff_t pos, unsigned len, unsigned copied,
 342                         struct page *page, void *fsdata)
 343 {
 344         BUG();
 345         return -EINVAL;
 346 }
 347
 348 static void remove_huge_page(struct page *page)
 349 {
 350         ClearPageDirty(page);
 351         ClearPageUptodate(page);
 352         delete_from_page_cache(page);
 353 }
 354
 355 static void
 356 hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end)
 357 {
 358         struct vm_area_struct *vma;
 359
 360         /*
 361          * end == 0 indicates that the entire range after
 362          * start should be unmapped.
 363          */
 364         vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) {
 365                 unsigned long v_offset;
 366                 unsigned long v_end;
 367
 368                 /*
 369                  * Can the expression below overflow on 32-bit arches?
 370                  * No, because the interval tree returns us only those vmas
 371                  * which overlap the truncated area starting at pgoff,
 372                  * and no vma on a 32-bit arch can span beyond the 4GB.
 373                  */
 374                 if (vma->vm_pgoff < start)
 375                         v_offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
 376                 else
 377                         v_offset = 0;
 378
 379                 if (!end)
 380                         v_end = vma->vm_end;
 381                 else {
 382                         v_end = ((end - vma->vm_pgoff) << PAGE_SHIFT)
 383                                                         + vma->vm_start;
 384                         if (v_end > vma->vm_end)
 385                                 v_end = vma->vm_end;
 386                 }
 387
 388                 unmap_hugepage_range(vma, vma->vm_start + v_offset, v_end,
 389                                                                         NULL);
 390         }
 391 }
 392
 393 /*
 394  * remove_inode_hugepages handles two distinct cases: truncation and hole
 395  * punch.  There are subtle differences in operation for each case.
 396  *
 397  * truncation is indicated by end of range being LLONG_MAX
 398  *      In this case, we first scan the range and release found pages.
 399  *      After releasing pages, hugetlb_unreserve_pages cleans up region/reserv
 400  *      maps and global counts.  Page faults can not race with truncation
 401  *      in this routine.  hugetlb_no_page() prevents page faults in the
 402  *      truncated range.  It checks i_size before allocation, and again after
 403  *      with the page table lock for the page held.  The same lock must be
 404  *      acquired to unmap a page.
 405  * hole punch is indicated if end is not LLONG_MAX
 406  *      In the hole punch case we scan the range and release found pages.
 407  *      Only when releasing a page is the associated region/reserv map
 408  *      deleted.  The region/reserv map for ranges without associated
 409  *      pages are not modified.  Page faults can race with hole punch.
 410  *      This is indicated if we find a mapped page.
 411  * Note: If the passed end of range value is beyond the end of file, but
 412  * not LLONG_MAX this routine still performs a hole punch operation.
 413  */
 414 static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
 415                                    loff_t lend)
 416 {
 417         struct hstate *h = hstate_inode(inode);
 418         struct address_space *mapping = &inode->i_data;
 419         const pgoff_t start = lstart >> huge_page_shift(h);
 420         const pgoff_t end = lend >> huge_page_shift(h);
 421         struct vm_area_struct pseudo_vma;
 422         struct pagevec pvec;
 423         pgoff_t next, index;
 424         int i, freed = 0;
 425         bool truncate_op = (lend == LLONG_MAX);
 426
 427         vma_init(&pseudo_vma, current->mm);
 428         pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
 429         pagevec_init(&pvec);
 430         next = start;
 431         while (next < end) {
 432                 /*
 433                  * When no more pages are found, we are done.
 434                  */
 435                 if (!pagevec_lookup_range(&pvec, mapping, &next, end - 1))
 436                         break;
 437
 438                 for (i = 0; i < pagevec_count(&pvec); ++i) {
 439                         struct page *page = pvec.pages[i];
 440                         u32 hash;
 441
 442                         index = page->index;
 443                         hash = hugetlb_fault_mutex_hash(mapping, index);
 444                         mutex_lock(&hugetlb_fault_mutex_table[hash]);
 445
 446                         /*
 447                          * If page is mapped, it was faulted in after being
 448                          * unmapped in caller.  Unmap (again) now after taking
 449                          * the fault mutex.  The mutex will prevent faults
 450                          * until we finish removing the page.
 451                          *
 452                          * This race can only happen in the hole punch case.
 453                          * Getting here in a truncate operation is a bug.
 454                          */
 455                         if (unlikely(page_mapped(page))) {
 456                                 BUG_ON(truncate_op);
 457
 458                                 i_mmap_lock_write(mapping);
 459                                 hugetlb_vmdelete_list(&mapping->i_mmap,
 460                                         index * pages_per_huge_page(h),
 461                                         (index + 1) * pages_per_huge_page(h));
 462                                 i_mmap_unlock_write(mapping);
 463                         }
 464
 465                         lock_page(page);
 466                         /*
 467                          * We must free the huge page and remove from page
 468                          * cache (remove_huge_page) BEFORE removing the
 469                          * region/reserve map (hugetlb_unreserve_pages).  In
 470                          * rare out of memory conditions, removal of the
 471                          * region/reserve map could fail. Correspondingly,
 472                          * the subpool and global reserve usage count can need
 473                          * to be adjusted.
 474                          */
 475                         VM_BUG_ON(PagePrivate(page));
 476                         remove_huge_page(page);
 477                         freed++;
 478                         if (!truncate_op) {
 479                                 if (unlikely(hugetlb_unreserve_pages(inode,
 480                                                         index, index + 1, 1)))
 481                                         hugetlb_fix_reserve_counts(inode);
 482                         }
 483
 484                         unlock_page(page);
 485                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 486                 }
 487                 huge_pagevec_release(&pvec);
 488                 cond_resched();
 489         }
 490
 491         if (truncate_op)
 492                 (void)hugetlb_unreserve_pages(inode, start, LONG_MAX, freed);
 493 }
 494
 495 static void hugetlbfs_evict_inode(struct inode *inode)
 496 {
 497         struct resv_map *resv_map;
 498
 499         remove_inode_hugepages(inode, 0, LLONG_MAX);
 500
 501         /*
 502          * Get the resv_map from the address space embedded in the inode.
 503          * This is the address space which points to any resv_map allocated
 504          * at inode creation time.  If this is a device special inode,
 505          * i_mapping may not point to the original address space.
 506          */
 507         resv_map = (struct resv_map *)(&inode->i_data)->private_data;
 508         /* Only regular and link inodes have associated reserve maps */
 509         if (resv_map)
 510                 resv_map_release(&resv_map->refs);
 511         clear_inode(inode);
 512 }
 513
 514 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 515 {
 516         pgoff_t pgoff;
 517         struct address_space *mapping = inode->i_mapping;
 518         struct hstate *h = hstate_inode(inode);
 519
 520         BUG_ON(offset & ~huge_page_mask(h));
 521         pgoff = offset >> PAGE_SHIFT;
 522
 523         i_size_write(inode, offset);
 524         i_mmap_lock_write(mapping);
 525         if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
 526                 hugetlb_vmdelete_list(&mapping->i_mmap, pgoff, 0);
 527         i_mmap_unlock_write(mapping);
 528         remove_inode_hugepages(inode, offset, LLONG_MAX);
 529         return 0;
 530 }
 531
 532 static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 533 {
 534         struct hstate *h = hstate_inode(inode);
 535         loff_t hpage_size = huge_page_size(h);
 536         loff_t hole_start, hole_end;
 537
 538         /*
 539          * For hole punch round up the beginning offset of the hole and
 540          * round down the end.
 541          */
 542         hole_start = round_up(offset, hpage_size);
 543         hole_end = round_down(offset + len, hpage_size);
 544
 545         if (hole_end > hole_start) {
 546                 struct address_space *mapping = inode->i_mapping;
 547                 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 548
 549                 inode_lock(inode);
 550
 551                 /* protected by i_mutex */
 552                 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
 553                         inode_unlock(inode);
 554                         return -EPERM;
 555                 }
 556
 557                 i_mmap_lock_write(mapping);
 558                 if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
 559                         hugetlb_vmdelete_list(&mapping->i_mmap,
 560                                                 hole_start >> PAGE_SHIFT,
 561                                                 hole_end  >> PAGE_SHIFT);
 562                 i_mmap_unlock_write(mapping);
 563                 remove_inode_hugepages(inode, hole_start, hole_end);
 564                 inode_unlock(inode);
 565         }
 566
 567         return 0;
 568 }
 569
 570 static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
 571                                 loff_t len)
 572 {
 573         struct inode *inode = file_inode(file);
 574         struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 575         struct address_space *mapping = inode->i_mapping;
 576         struct hstate *h = hstate_inode(inode);
 577         struct vm_area_struct pseudo_vma;
 578         struct mm_struct *mm = current->mm;
 579         loff_t hpage_size = huge_page_size(h);
 580         unsigned long hpage_shift = huge_page_shift(h);
 581         pgoff_t start, index, end;
 582         int error;
 583         u32 hash;
 584
 585         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
 586                 return -EOPNOTSUPP;
 587
 588         if (mode & FALLOC_FL_PUNCH_HOLE)
 589                 return hugetlbfs_punch_hole(inode, offset, len);
 590
 591         /*
 592          * Default preallocate case.
 593          * For this range, start is rounded down and end is rounded up
 594          * as well as being converted to page offsets.
 595          */
 596         start = offset >> hpage_shift;
 597         end = (offset + len + hpage_size - 1) >> hpage_shift;
 598
 599         inode_lock(inode);
 600
 601         /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
 602         error = inode_newsize_ok(inode, offset + len);
 603         if (error)
 604                 goto out;
 605
 606         if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
 607                 error = -EPERM;
 608                 goto out;
 609         }
 610
 611         /*
 612          * Initialize a pseudo vma as this is required by the huge page
 613          * allocation routines.  If NUMA is configured, use page index
 614          * as input to create an allocation policy.
 615          */
 616         vma_init(&pseudo_vma, mm);
 617         pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
 618         pseudo_vma.vm_file = file;
 619
 620         for (index = start; index < end; index++) {
 621                 /*
 622                  * This is supposed to be the vaddr where the page is being
 623                  * faulted in, but we have no vaddr here.
 624                  */
 625                 struct page *page;
 626                 unsigned long addr;
 627                 int avoid_reserve = 0;
 628
 629                 cond_resched();
 630
 631                 /*
 632                  * fallocate(2) manpage permits EINTR; we may have been
 633                  * interrupted because we are using up too much memory.
 634                  */
 635                 if (signal_pending(current)) {
 636                         error = -EINTR;
 637                         break;
 638                 }
 639
 640                 /* Set numa allocation policy based on index */
 641                 hugetlb_set_vma_policy(&pseudo_vma, inode, index);
 642
 643                 /* addr is the offset within the file (zero based) */
 644                 addr = index * hpage_size;
 645
 646                 /* mutex taken here, fault path and hole punch */
 647                 hash = hugetlb_fault_mutex_hash(mapping, index);
 648                 mutex_lock(&hugetlb_fault_mutex_table[hash]);
 649
 650                 /* See if already present in mapping to avoid alloc/free */
 651                 page = find_get_page(mapping, index);
 652                 if (page) {
 653                         put_page(page);
 654                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 655                         hugetlb_drop_vma_policy(&pseudo_vma);
 656                         continue;
 657                 }
 658
 659                 /* Allocate page and add to page cache */
 660                 page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
 661                 hugetlb_drop_vma_policy(&pseudo_vma);
 662                 if (IS_ERR(page)) {
 663                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 664                         error = PTR_ERR(page);
 665                         goto out;
 666                 }
 667                 clear_huge_page(page, addr, pages_per_huge_page(h));
 668                 __SetPageUptodate(page);
 669                 error = huge_add_to_page_cache(page, mapping, index);
 670                 if (unlikely(error)) {
 671                         put_page(page);
 672                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 673                         goto out;
 674                 }
 675
 676                 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 677
 678                 /*
 679                  * unlock_page because locked by add_to_page_cache()
 680                  * page_put due to reference from alloc_huge_page()
 681                  */
 682                 unlock_page(page);
 683                 put_page(page);
 684         }
 685
 686         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
 687                 i_size_write(inode, offset + len);
 688         inode->i_ctime = current_time(inode);
 689 out:
 690         inode_unlock(inode);
 691         return error;
 692 }
 693
 694 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
 695 {
 696         struct inode *inode = d_inode(dentry);
 697         struct hstate *h = hstate_inode(inode);
 698         int error;
 699         unsigned int ia_valid = attr->ia_valid;
 700         struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 701
 702         BUG_ON(!inode);
 703
 704         error = setattr_prepare(dentry, attr);
 705         if (error)
 706                 return error;
 707
 708         if (ia_valid & ATTR_SIZE) {
 709                 loff_t oldsize = inode->i_size;
 710                 loff_t newsize = attr->ia_size;
 711
 712                 if (newsize & ~huge_page_mask(h))
 713                         return -EINVAL;
 714                 /* protected by i_mutex */
 715                 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
 716                     (newsize > oldsize && (info->seals & F_SEAL_GROW)))
 717                         return -EPERM;
 718                 error = hugetlb_vmtruncate(inode, newsize);
 719                 if (error)
 720                         return error;
 721         }
 722
 723         setattr_copy(inode, attr);
 724         mark_inode_dirty(inode);
 725         return 0;
 726 }
 727
 728 static struct inode *hugetlbfs_get_root(struct super_block *sb,
 729                                         struct hugetlbfs_fs_context *ctx)
 730 {
 731         struct inode *inode;
 732
 733         inode = new_inode(sb);
 734         if (inode) {
 735                 inode->i_ino = get_next_ino();
 736                 inode->i_mode = S_IFDIR | ctx->mode;
 737                 inode->i_uid = ctx->uid;
 738                 inode->i_gid = ctx->gid;
 739                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 740                 inode->i_op = &hugetlbfs_dir_inode_operations;
 741                 inode->i_fop = &simple_dir_operations;
 742                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
 743                 inc_nlink(inode);
 744                 lockdep_annotate_inode_mutex_key(inode);
 745         }
 746         return inode;
 747 }
 748
 749 /*
 750  * Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
 751  * be taken from reclaim -- unlike regular filesystems. This needs an
 752  * annotation because huge_pmd_share() does an allocation under hugetlb's
 753  * i_mmap_rwsem.
 754  */
 755 static struct lock_class_key hugetlbfs_i_mmap_rwsem_key;
 756
 757 static struct inode *hugetlbfs_get_inode(struct super_block *sb,
 758                                         struct inode *dir,
 759                                         umode_t mode, dev_t dev)
 760 {
 761         struct inode *inode;
 762         struct resv_map *resv_map = NULL;
 763
 764         /*
 765          * Reserve maps are only needed for inodes that can have associated
 766          * page allocations.
 767          */
 768         if (S_ISREG(mode) || S_ISLNK(mode)) {
 769                 resv_map = resv_map_alloc();
 770                 if (!resv_map)
 771                         return NULL;
 772         }
 773
 774         inode = new_inode(sb);
 775         if (inode) {
 776                 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 777
 778                 inode->i_ino = get_next_ino();
 779                 inode_init_owner(inode, dir, mode);
 780                 lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
 781                                 &hugetlbfs_i_mmap_rwsem_key);
 782                 inode->i_mapping->a_ops = &hugetlbfs_aops;
 783                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 784                 inode->i_mapping->private_data = resv_map;
 785                 info->seals = F_SEAL_SEAL;
 786                 switch (mode & S_IFMT) {
 787                 default:
 788                         init_special_inode(inode, mode, dev);
 789                         break;
 790                 case S_IFREG:
 791                         inode->i_op = &hugetlbfs_inode_operations;
 792                         inode->i_fop = &hugetlbfs_file_operations;
 793                         break;
 794                 case S_IFDIR:
 795                         inode->i_op = &hugetlbfs_dir_inode_operations;
 796                         inode->i_fop = &simple_dir_operations;
 797
 798                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 799                         inc_nlink(inode);
 800                         break;
 801                 case S_IFLNK:
 802                         inode->i_op = &page_symlink_inode_operations;
 803                         inode_nohighmem(inode);
 804                         break;
 805                 }
 806                 lockdep_annotate_inode_mutex_key(inode);
 807         } else {
 808                 if (resv_map)
 809                         kref_put(&resv_map->refs, resv_map_release);
 810         }
 811
 812         return inode;
 813 }
 814
 815 /*
 816  * File creation. Allocate an inode, and we're done..
 817  */
 818 static int do_hugetlbfs_mknod(struct inode *dir,
 819                         struct dentry *dentry,
 820                         umode_t mode,
 821                         dev_t dev,
 822                         bool tmpfile)
 823 {
 824         struct inode *inode;
 825         int error = -ENOSPC;
 826
 827         inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
 828         if (inode) {
 829                 dir->i_ctime = dir->i_mtime = current_time(dir);
 830                 if (tmpfile) {
 831                         d_tmpfile(dentry, inode);
 832                 } else {
 833                         d_instantiate(dentry, inode);
 834                         dget(dentry);/* Extra count - pin the dentry in core */
 835                 }
 836                 error = 0;
 837         }
 838         return error;
 839 }
 840
 841 static int hugetlbfs_mknod(struct inode *dir,
 842                         struct dentry *dentry, umode_t mode, dev_t dev)
 843 {
 844         return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
 845 }
 846
 847 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 848 {
 849         int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
 850         if (!retval)
 851                 inc_nlink(dir);
 852         return retval;
 853 }
 854
 855 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
 856 {
 857         return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
 858 }
 859
 860 static int hugetlbfs_tmpfile(struct inode *dir,
 861                         struct dentry *dentry, umode_t mode)
 862 {
 863         return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
 864 }
 865
 866 static int hugetlbfs_symlink(struct inode *dir,
 867                         struct dentry *dentry, const char *symname)
 868 {
 869         struct inode *inode;
 870         int error = -ENOSPC;
 871
 872         inode = hugetlbfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
 873         if (inode) {
 874                 int l = strlen(symname)+1;
 875                 error = page_symlink(inode, symname, l);
 876                 if (!error) {
 877                         d_instantiate(dentry, inode);
 878                         dget(dentry);
 879                 } else
 880                         iput(inode);
 881         }
 882         dir->i_ctime = dir->i_mtime = current_time(dir);
 883
 884         return error;
 885 }
 886
 887 /*
 888  * mark the head page dirty
 889  */
 890 static int hugetlbfs_set_page_dirty(struct page *page)
 891 {
 892         struct page *head = compound_head(page);
 893
 894         SetPageDirty(head);
 895         return 0;
 896 }
 897
 898 static int hugetlbfs_migrate_page(struct address_space *mapping,
 899                                 struct page *newpage, struct page *page,
 900                                 enum migrate_mode mode)
 901 {
 902         int rc;
 903
 904         rc = migrate_huge_page_move_mapping(mapping, newpage, page);
 905         if (rc != MIGRATEPAGE_SUCCESS)
 906                 return rc;
 907
 908         /*
 909          * page_private is subpool pointer in hugetlb pages.  Transfer to
 910          * new page.  PagePrivate is not associated with page_private for
 911          * hugetlb pages and can not be set here as only page_huge_active
 912          * pages can be migrated.
 913          */
 914         if (page_private(page)) {
 915                 set_page_private(newpage, page_private(page));
 916                 set_page_private(page, 0);
 917         }
 918
 919         if (mode != MIGRATE_SYNC_NO_COPY)
 920                 migrate_page_copy(newpage, page);
 921         else
 922                 migrate_page_states(newpage, page);
 923
 924         return MIGRATEPAGE_SUCCESS;
 925 }
 926
 927 static int hugetlbfs_error_remove_page(struct address_space *mapping,
 928                                 struct page *page)
 929 {
 930         struct inode *inode = mapping->host;
 931         pgoff_t index = page->index;
 932
 933         remove_huge_page(page);
 934         if (unlikely(hugetlb_unreserve_pages(inode, index, index + 1, 1)))
 935                 hugetlb_fix_reserve_counts(inode);
 936
 937         return 0;
 938 }
 939
 940 /*
 941  * Display the mount options in /proc/mounts.
 942  */
 943 static int hugetlbfs_show_options(struct seq_file *m, struct dentry *root)
 944 {
 945         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(root->d_sb);
 946         struct hugepage_subpool *spool = sbinfo->spool;
 947         unsigned long hpage_size = huge_page_size(sbinfo->hstate);
 948         unsigned hpage_shift = huge_page_shift(sbinfo->hstate);
 949         char mod;
 950
 951         if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
 952                 seq_printf(m, ",uid=%u",
 953                            from_kuid_munged(&init_user_ns, sbinfo->uid));
 954         if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
 955                 seq_printf(m, ",gid=%u",
 956                            from_kgid_munged(&init_user_ns, sbinfo->gid));
 957         if (sbinfo->mode != 0755)
 958                 seq_printf(m, ",mode=%o", sbinfo->mode);
 959         if (sbinfo->max_inodes != -1)
 960                 seq_printf(m, ",nr_inodes=%lu", sbinfo->max_inodes);
 961
 962         hpage_size /= 1024;
 963         mod = 'K';
 964         if (hpage_size >= 1024) {
 965                 hpage_size /= 1024;
 966                 mod = 'M';
 967         }
 968         seq_printf(m, ",pagesize=%lu%c", hpage_size, mod);
 969         if (spool) {
 970                 if (spool->max_hpages != -1)
 971                         seq_printf(m, ",size=%llu",
 972                                    (unsigned long long)spool->max_hpages << hpage_shift);
 973                 if (spool->min_hpages != -1)
 974                         seq_printf(m, ",min_size=%llu",
 975                                    (unsigned long long)spool->min_hpages << hpage_shift);
 976         }
 977         return 0;
 978 }
 979
 980 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 981 {
 982         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
 983         struct hstate *h = hstate_inode(d_inode(dentry));
 984
 985         buf->f_type = HUGETLBFS_MAGIC;
 986         buf->f_bsize = huge_page_size(h);
 987         if (sbinfo) {
 988                 spin_lock(&sbinfo->stat_lock);
 989                 /* If no limits set, just report 0 for max/free/used
 990                  * blocks, like simple_statfs() */
 991                 if (sbinfo->spool) {
 992                         long free_pages;
 993
 994                         spin_lock(&sbinfo->spool->lock);
 995                         buf->f_blocks = sbinfo->spool->max_hpages;
 996                         free_pages = sbinfo->spool->max_hpages
 997                                 - sbinfo->spool->used_hpages;
 998                         buf->f_bavail = buf->f_bfree = free_pages;
 999                         spin_unlock(&sbinfo->spool->lock);
1000                         buf->f_files = sbinfo->max_inodes;
1001                         buf->f_ffree = sbinfo->free_inodes;
1002                 }
1003                 spin_unlock(&sbinfo->stat_lock);
1004         }
1005         buf->f_namelen = NAME_MAX;
1006         return 0;
1007 }
1008
1009 static void hugetlbfs_put_super(struct super_block *sb)
1010 {
1011         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
1012
1013         if (sbi) {
1014                 sb->s_fs_info = NULL;
1015
1016                 if (sbi->spool)
1017                         hugepage_put_subpool(sbi->spool);
1018
1019                 kfree(sbi);
1020         }
1021 }
1022
1023 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1024 {
1025         if (sbinfo->free_inodes >= 0) {
1026                 spin_lock(&sbinfo->stat_lock);
1027                 if (unlikely(!sbinfo->free_inodes)) {
1028                         spin_unlock(&sbinfo->stat_lock);
1029                         return 0;
1030                 }
1031                 sbinfo->free_inodes--;
1032                 spin_unlock(&sbinfo->stat_lock);
1033         }
1034
1035         return 1;
1036 }
1037
1038 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1039 {
1040         if (sbinfo->free_inodes >= 0) {
1041                 spin_lock(&sbinfo->stat_lock);
1042                 sbinfo->free_inodes++;
1043                 spin_unlock(&sbinfo->stat_lock);
1044         }
1045 }
1046
1047
1048 static struct kmem_cache *hugetlbfs_inode_cachep;
1049
1050 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
1051 {
1052         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
1053         struct hugetlbfs_inode_info *p;
1054
1055         if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
1056                 return NULL;
1057         p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);
1058         if (unlikely(!p)) {
1059                 hugetlbfs_inc_free_inodes(sbinfo);
1060                 return NULL;
1061         }
1062
1063         /*
1064          * Any time after allocation, hugetlbfs_destroy_inode can be called
1065          * for the inode.  mpol_free_shared_policy is unconditionally called
1066          * as part of hugetlbfs_destroy_inode.  So, initialize policy here
1067          * in case of a quick call to destroy.
1068          *
1069          * Note that the policy is initialized even if we are creating a
1070          * private inode.  This simplifies hugetlbfs_destroy_inode.
1071          */
1072         mpol_shared_policy_init(&p->policy, NULL);
1073
1074         return &p->vfs_inode;
1075 }
1076
1077 static void hugetlbfs_free_inode(struct inode *inode)
1078 {
1079         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
1080 }
1081
1082 static void hugetlbfs_destroy_inode(struct inode *inode)
1083 {
1084         hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
1085         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
1086 }
1087
1088 static const struct address_space_operations hugetlbfs_aops = {
1089         .write_begin    = hugetlbfs_write_begin,
1090         .write_end      = hugetlbfs_write_end,
1091         .set_page_dirty = hugetlbfs_set_page_dirty,
1092         .migratepage    = hugetlbfs_migrate_page,
1093         .error_remove_page      = hugetlbfs_error_remove_page,
1094 };
1095
1096
1097 static void init_once(void *foo)
1098 {
1099         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
1100
1101         inode_init_once(&ei->vfs_inode);
1102 }
1103
1104 const struct file_operations hugetlbfs_file_operations = {
1105         .read_iter              = hugetlbfs_read_iter,
1106         .mmap                   = hugetlbfs_file_mmap,
1107         .fsync                  = noop_fsync,
1108         .get_unmapped_area      = hugetlb_get_unmapped_area,
1109         .llseek                 = default_llseek,
1110         .fallocate              = hugetlbfs_fallocate,
1111 };
1112
1113 static const struct inode_operations hugetlbfs_dir_inode_operations = {
1114         .create         = hugetlbfs_create,
1115         .lookup         = simple_lookup,
1116         .link           = simple_link,
1117         .unlink         = simple_unlink,
1118         .symlink        = hugetlbfs_symlink,
1119         .mkdir          = hugetlbfs_mkdir,
1120         .rmdir          = simple_rmdir,
1121         .mknod          = hugetlbfs_mknod,
1122         .rename         = simple_rename,
1123         .setattr        = hugetlbfs_setattr,
1124         .tmpfile        = hugetlbfs_tmpfile,
1125 };
1126
1127 static const struct inode_operations hugetlbfs_inode_operations = {
1128         .setattr        = hugetlbfs_setattr,
1129 };
1130
1131 static const struct super_operations hugetlbfs_ops = {
1132         .alloc_inode    = hugetlbfs_alloc_inode,
1133         .free_inode     = hugetlbfs_free_inode,
1134         .destroy_inode  = hugetlbfs_destroy_inode,
1135         .evict_inode    = hugetlbfs_evict_inode,
1136         .statfs         = hugetlbfs_statfs,
1137         .put_super      = hugetlbfs_put_super,
1138         .show_options   = hugetlbfs_show_options,
1139 };
1140
1141 /*
1142  * Convert size option passed from command line to number of huge pages
1143  * in the pool specified by hstate.  Size option could be in bytes
1144  * (val_type == SIZE_STD) or percentage of the pool (val_type == SIZE_PERCENT).
1145  */
1146 static long
1147 hugetlbfs_size_to_hpages(struct hstate *h, unsigned long long size_opt,
1148                          enum hugetlbfs_size_type val_type)
1149 {
1150         if (val_type == NO_SIZE)
1151                 return -1;
1152
1153         if (val_type == SIZE_PERCENT) {
1154                 size_opt <<= huge_page_shift(h);
1155                 size_opt *= h->max_huge_pages;
1156                 do_div(size_opt, 100);
1157         }
1158
1159         size_opt >>= huge_page_shift(h);
1160         return size_opt;
1161 }
1162
1163 /*
1164  * Parse one mount parameter.
1165  */
1166 static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
1167 {
1168         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1169         struct fs_parse_result result;
1170         char *rest;
1171         unsigned long ps;
1172         int opt;
1173
1174         opt = fs_parse(fc, &hugetlb_fs_parameters, param, &result);
1175         if (opt < 0)
1176                 return opt;
1177
1178         switch (opt) {
1179         case Opt_uid:
1180                 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
1181                 if (!uid_valid(ctx->uid))
1182                         goto bad_val;
1183                 return 0;
1184
1185         case Opt_gid:
1186                 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
1187                 if (!gid_valid(ctx->gid))
1188                         goto bad_val;
1189                 return 0;
1190
1191         case Opt_mode:
1192                 ctx->mode = result.uint_32 & 01777U;
1193                 return 0;
1194
1195         case Opt_size:
1196                 /* memparse() will accept a K/M/G without a digit */
1197                 if (!isdigit(param->string[0]))
1198                         goto bad_val;
1199                 ctx->max_size_opt = memparse(param->string, &rest);
1200                 ctx->max_val_type = SIZE_STD;
1201                 if (*rest == '%')
1202                         ctx->max_val_type = SIZE_PERCENT;
1203                 return 0;
1204
1205         case Opt_nr_inodes:
1206                 /* memparse() will accept a K/M/G without a digit */
1207                 if (!isdigit(param->string[0]))
1208                         goto bad_val;
1209                 ctx->nr_inodes = memparse(param->string, &rest);
1210                 return 0;
1211
1212         case Opt_pagesize:
1213                 ps = memparse(param->string, &rest);
1214                 ctx->hstate = size_to_hstate(ps);
1215                 if (!ctx->hstate) {
1216                         pr_err("Unsupported page size %lu MB\n", ps >> 20);
1217                         return -EINVAL;
1218                 }
1219                 return 0;
1220
1221         case Opt_min_size:
1222                 /* memparse() will accept a K/M/G without a digit */
1223                 if (!isdigit(param->string[0]))
1224                         goto bad_val;
1225                 ctx->min_size_opt = memparse(param->string, &rest);
1226                 ctx->min_val_type = SIZE_STD;
1227                 if (*rest == '%')
1228                         ctx->min_val_type = SIZE_PERCENT;
1229                 return 0;
1230
1231         default:
1232                 return -EINVAL;
1233         }
1234
1235 bad_val:
1236         return invalf(fc, "hugetlbfs: Bad value '%s' for mount option '%s'\n",
1237                       param->string, param->key);
1238 }
1239
1240 /*
1241  * Validate the parsed options.
1242  */
1243 static int hugetlbfs_validate(struct fs_context *fc)
1244 {
1245         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1246
1247         /*
1248          * Use huge page pool size (in hstate) to convert the size
1249          * options to number of huge pages.  If NO_SIZE, -1 is returned.
1250          */
1251         ctx->max_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
1252                                                    ctx->max_size_opt,
1253                                                    ctx->max_val_type);
1254         ctx->min_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
1255                                                    ctx->min_size_opt,
1256                                                    ctx->min_val_type);
1257
1258         /*
1259          * If max_size was specified, then min_size must be smaller
1260          */
1261         if (ctx->max_val_type > NO_SIZE &&
1262             ctx->min_hpages > ctx->max_hpages) {
1263                 pr_err("Minimum size can not be greater than maximum size\n");
1264                 return -EINVAL;
1265         }
1266
1267         return 0;
1268 }
1269
1270 static int
1271 hugetlbfs_fill_super(struct super_block *sb, struct fs_context *fc)
1272 {
1273         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1274         struct hugetlbfs_sb_info *sbinfo;
1275
1276         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
1277         if (!sbinfo)
1278                 return -ENOMEM;
1279         sb->s_fs_info = sbinfo;
1280         spin_lock_init(&sbinfo->stat_lock);
1281         sbinfo->hstate          = ctx->hstate;
1282         sbinfo->max_inodes      = ctx->nr_inodes;
1283         sbinfo->free_inodes     = ctx->nr_inodes;
1284         sbinfo->spool           = NULL;
1285         sbinfo->uid             = ctx->uid;
1286         sbinfo->gid             = ctx->gid;
1287         sbinfo->mode            = ctx->mode;
1288
1289         /*
1290          * Allocate and initialize subpool if maximum or minimum size is
1291          * specified.  Any needed reservations (for minimim size) are taken
1292          * taken when the subpool is created.
1293          */
1294         if (ctx->max_hpages != -1 || ctx->min_hpages != -1) {
1295                 sbinfo->spool = hugepage_new_subpool(ctx->hstate,
1296                                                      ctx->max_hpages,
1297                                                      ctx->min_hpages);
1298                 if (!sbinfo->spool)
1299                         goto out_free;
1300         }
1301         sb->s_maxbytes = MAX_LFS_FILESIZE;
1302         sb->s_blocksize = huge_page_size(ctx->hstate);
1303         sb->s_blocksize_bits = huge_page_shift(ctx->hstate);
1304         sb->s_magic = HUGETLBFS_MAGIC;
1305         sb->s_op = &hugetlbfs_ops;
1306         sb->s_time_gran = 1;
1307         sb->s_root = d_make_root(hugetlbfs_get_root(sb, ctx));
1308         if (!sb->s_root)
1309                 goto out_free;
1310         return 0;
1311 out_free:
1312         kfree(sbinfo->spool);
1313         kfree(sbinfo);
1314         return -ENOMEM;
1315 }
1316
1317 static int hugetlbfs_get_tree(struct fs_context *fc)
1318 {
1319         int err = hugetlbfs_validate(fc);
1320         if (err)
1321                 return err;
1322         return get_tree_nodev(fc, hugetlbfs_fill_super);
1323 }
1324
1325 static void hugetlbfs_fs_context_free(struct fs_context *fc)
1326 {
1327         kfree(fc->fs_private);
1328 }
1329
1330 static const struct fs_context_operations hugetlbfs_fs_context_ops = {
1331         .free           = hugetlbfs_fs_context_free,
1332         .parse_param    = hugetlbfs_parse_param,
1333         .get_tree       = hugetlbfs_get_tree,
1334 };
1335
1336 static int hugetlbfs_init_fs_context(struct fs_context *fc)
1337 {
1338         struct hugetlbfs_fs_context *ctx;
1339
1340         ctx = kzalloc(sizeof(struct hugetlbfs_fs_context), GFP_KERNEL);
1341         if (!ctx)
1342                 return -ENOMEM;
1343
1344         ctx->max_hpages = -1; /* No limit on size by default */
1345         ctx->nr_inodes  = -1; /* No limit on number of inodes by default */
1346         ctx->uid        = current_fsuid();
1347         ctx->gid        = current_fsgid();
1348         ctx->mode       = 0755;
1349         ctx->hstate     = &default_hstate;
1350         ctx->min_hpages = -1; /* No default minimum size */
1351         ctx->max_val_type = NO_SIZE;
1352         ctx->min_val_type = NO_SIZE;
1353         fc->fs_private = ctx;
1354         fc->ops = &hugetlbfs_fs_context_ops;
1355         return 0;
1356 }
1357
1358 static struct file_system_type hugetlbfs_fs_type = {
1359         .name                   = "hugetlbfs",
1360         .init_fs_context        = hugetlbfs_init_fs_context,
1361         .parameters             = &hugetlb_fs_parameters,
1362         .kill_sb                = kill_litter_super,
1363 };
1364
1365 static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE];
1366
1367 static int can_do_hugetlb_shm(void)
1368 {
1369         kgid_t shm_group;
1370         shm_group = make_kgid(&init_user_ns, sysctl_hugetlb_shm_group);
1371         return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
1372 }
1373
1374 static int get_hstate_idx(int page_size_log)
1375 {
1376         struct hstate *h = hstate_sizelog(page_size_log);
1377
1378         if (!h)
1379                 return -1;
1380         return h - hstates;
1381 }
1382
1383 /*
1384  * Note that size should be aligned to proper hugepage size in caller side,
1385  * otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
1386  */
1387 struct file *hugetlb_file_setup(const char *name, size_t size,
1388                                 vm_flags_t acctflag, struct user_struct **user,
1389                                 int creat_flags, int page_size_log)
1390 {
1391         struct inode *inode;
1392         struct vfsmount *mnt;
1393         int hstate_idx;
1394         struct file *file;
1395
1396         hstate_idx = get_hstate_idx(page_size_log);
1397         if (hstate_idx < 0)
1398                 return ERR_PTR(-ENODEV);
1399
1400         *user = NULL;
1401         mnt = hugetlbfs_vfsmount[hstate_idx];
1402         if (!mnt)
1403                 return ERR_PTR(-ENOENT);
1404
1405         if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
1406                 *user = current_user();
1407                 if (user_shm_lock(size, *user)) {
1408                         task_lock(current);
1409                         pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is deprecated\n",
1410                                 current->comm, current->pid);
1411                         task_unlock(current);
1412                 } else {
1413                         *user = NULL;
1414                         return ERR_PTR(-EPERM);
1415                 }
1416         }
1417
1418         file = ERR_PTR(-ENOSPC);
1419         inode = hugetlbfs_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0);
1420         if (!inode)
1421                 goto out;
1422         if (creat_flags == HUGETLB_SHMFS_INODE)
1423                 inode->i_flags |= S_PRIVATE;
1424
1425         inode->i_size = size;
1426         clear_nlink(inode);
1427
1428         if (hugetlb_reserve_pages(inode, 0,
1429                         size >> huge_page_shift(hstate_inode(inode)), NULL,
1430                         acctflag))
1431                 file = ERR_PTR(-ENOMEM);
1432         else
1433                 file = alloc_file_pseudo(inode, mnt, name, O_RDWR,
1434                                         &hugetlbfs_file_operations);
1435         if (!IS_ERR(file))
1436                 return file;
1437
1438         iput(inode);
1439 out:
1440         if (*user) {
1441                 user_shm_unlock(size, *user);
1442                 *user = NULL;
1443         }
1444         return file;
1445 }
1446
1447 static struct vfsmount *__init mount_one_hugetlbfs(struct hstate *h)
1448 {
1449         struct fs_context *fc;
1450         struct vfsmount *mnt;
1451
1452         fc = fs_context_for_mount(&hugetlbfs_fs_type, SB_KERNMOUNT);
1453         if (IS_ERR(fc)) {
1454                 mnt = ERR_CAST(fc);
1455         } else {
1456                 struct hugetlbfs_fs_context *ctx = fc->fs_private;
1457                 ctx->hstate = h;
1458                 mnt = fc_mount(fc);
1459                 put_fs_context(fc);
1460         }
1461         if (IS_ERR(mnt))
1462                 pr_err("Cannot mount internal hugetlbfs for page size %uK",
1463                        1U << (h->order + PAGE_SHIFT - 10));
1464         return mnt;
1465 }
1466
1467 static int __init init_hugetlbfs_fs(void)
1468 {
1469         struct vfsmount *mnt;
1470         struct hstate *h;
1471         int error;
1472         int i;
1473
1474         if (!hugepages_supported()) {
1475                 pr_info("disabling because there are no supported hugepage sizes\n");
1476                 return -ENOTSUPP;
1477         }
1478
1479         error = -ENOMEM;
1480         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
1481                                         sizeof(struct hugetlbfs_inode_info),
1482                                         0, SLAB_ACCOUNT, init_once);
1483         if (hugetlbfs_inode_cachep == NULL)
1484                 goto out;
1485
1486         error = register_filesystem(&hugetlbfs_fs_type);
1487         if (error)
1488                 goto out_free;
1489
1490         /* default hstate mount is required */
1491         mnt = mount_one_hugetlbfs(&hstates[default_hstate_idx]);
1492         if (IS_ERR(mnt)) {
1493                 error = PTR_ERR(mnt);
1494                 goto out_unreg;
1495         }
1496         hugetlbfs_vfsmount[default_hstate_idx] = mnt;
1497
1498         /* other hstates are optional */
1499         i = 0;
1500         for_each_hstate(h) {
1501                 if (i == default_hstate_idx) {
1502                         i++;
1503                         continue;
1504                 }
1505
1506                 mnt = mount_one_hugetlbfs(h);
1507                 if (IS_ERR(mnt))
1508                         hugetlbfs_vfsmount[i] = NULL;
1509                 else
1510                         hugetlbfs_vfsmount[i] = mnt;
1511                 i++;
1512         }
1513
1514         return 0;
1515
1516  out_unreg:
1517         (void)unregister_filesystem(&hugetlbfs_fs_type);
1518  out_free:
1519         kmem_cache_destroy(hugetlbfs_inode_cachep);
1520  out:
1521         return error;
1522 }
1523 fs_initcall(init_hugetlbfs_fs)