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 #include <linux/sched/mm.h>
  42
  43 static const struct super_operations hugetlbfs_ops;
  44 static const struct address_space_operations hugetlbfs_aops;
  45 const struct file_operations hugetlbfs_file_operations;
  46 static const struct inode_operations hugetlbfs_dir_inode_operations;
  47 static const struct inode_operations hugetlbfs_inode_operations;
  48
  49 enum hugetlbfs_size_type { NO_SIZE, SIZE_STD, SIZE_PERCENT };
  50
  51 struct hugetlbfs_fs_context {
  52         struct hstate           *hstate;
  53         unsigned long long      max_size_opt;
  54         unsigned long long      min_size_opt;
  55         long                    max_hpages;
  56         long                    nr_inodes;
  57         long                    min_hpages;
  58         enum hugetlbfs_size_type max_val_type;
  59         enum hugetlbfs_size_type min_val_type;
  60         kuid_t                  uid;
  61         kgid_t                  gid;
  62         umode_t                 mode;
  63 };
  64
  65 int sysctl_hugetlb_shm_group;
  66
  67 enum hugetlb_param {
  68         Opt_gid,
  69         Opt_min_size,
  70         Opt_mode,
  71         Opt_nr_inodes,
  72         Opt_pagesize,
  73         Opt_size,
  74         Opt_uid,
  75 };
  76
  77 static const struct fs_parameter_spec hugetlb_fs_parameters[] = {
  78         fsparam_u32   ("gid",           Opt_gid),
  79         fsparam_string("min_size",      Opt_min_size),
  80         fsparam_u32   ("mode",          Opt_mode),
  81         fsparam_string("nr_inodes",     Opt_nr_inodes),
  82         fsparam_string("pagesize",      Opt_pagesize),
  83         fsparam_string("size",          Opt_size),
  84         fsparam_u32   ("uid",           Opt_uid),
  85         {}
  86 };
  87
  88 #ifdef CONFIG_NUMA
  89 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
  90                                         struct inode *inode, pgoff_t index)
  91 {
  92         vma->vm_policy = mpol_shared_policy_lookup(&HUGETLBFS_I(inode)->policy,
  93                                                         index);
  94 }
  95
  96 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
  97 {
  98         mpol_cond_put(vma->vm_policy);
  99 }
 100 #else
 101 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
 102                                         struct inode *inode, pgoff_t index)
 103 {
 104 }
 105
 106 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
 107 {
 108 }
 109 #endif
 110
 111 static void huge_pagevec_release(struct pagevec *pvec)
 112 {
 113         int i;
 114
 115         for (i = 0; i < pagevec_count(pvec); ++i)
 116                 put_page(pvec->pages[i]);
 117
 118         pagevec_reinit(pvec);
 119 }
 120
 121 /*
 122  * Mask used when checking the page offset value passed in via system
 123  * calls.  This value will be converted to a loff_t which is signed.
 124  * Therefore, we want to check the upper PAGE_SHIFT + 1 bits of the
 125  * value.  The extra bit (- 1 in the shift value) is to take the sign
 126  * bit into account.
 127  */
 128 #define PGOFF_LOFFT_MAX \
 129         (((1UL << (PAGE_SHIFT + 1)) - 1) <<  (BITS_PER_LONG - (PAGE_SHIFT + 1)))
 130
 131 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
 132 {
 133         struct inode *inode = file_inode(file);
 134         loff_t len, vma_len;
 135         int ret;
 136         struct hstate *h = hstate_file(file);
 137
 138         /*
 139          * vma address alignment (but not the pgoff alignment) has
 140          * already been checked by prepare_hugepage_range.  If you add
 141          * any error returns here, do so after setting VM_HUGETLB, so
 142          * is_vm_hugetlb_page tests below unmap_region go the right
 143          * way when do_mmap unwinds (may be important on powerpc
 144          * and ia64).
 145          */
 146         vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
 147         vma->vm_ops = &hugetlb_vm_ops;
 148
 149         /*
 150          * page based offset in vm_pgoff could be sufficiently large to
 151          * overflow a loff_t when converted to byte offset.  This can
 152          * only happen on architectures where sizeof(loff_t) ==
 153          * sizeof(unsigned long).  So, only check in those instances.
 154          */
 155         if (sizeof(unsigned long) == sizeof(loff_t)) {
 156                 if (vma->vm_pgoff & PGOFF_LOFFT_MAX)
 157                         return -EINVAL;
 158         }
 159
 160         /* must be huge page aligned */
 161         if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))
 162                 return -EINVAL;
 163
 164         vma_len = (loff_t)(vma->vm_end - vma->vm_start);
 165         len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
 166         /* check for overflow */
 167         if (len < vma_len)
 168                 return -EINVAL;
 169
 170         inode_lock(inode);
 171         file_accessed(file);
 172
 173         ret = -ENOMEM;
 174         if (hugetlb_reserve_pages(inode,
 175                                 vma->vm_pgoff >> huge_page_order(h),
 176                                 len >> huge_page_shift(h), vma,
 177                                 vma->vm_flags))
 178                 goto out;
 179
 180         ret = 0;
 181         if (vma->vm_flags & VM_WRITE && inode->i_size < len)
 182                 i_size_write(inode, len);
 183 out:
 184         inode_unlock(inode);
 185
 186         return ret;
 187 }
 188
 189 /*
 190  * Called under mmap_write_lock(mm).
 191  */
 192
 193 #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 194 static unsigned long
 195 hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr,
 196                 unsigned long len, unsigned long pgoff, unsigned long flags)
 197 {
 198         struct hstate *h = hstate_file(file);
 199         struct vm_unmapped_area_info info;
 200
 201         info.flags = 0;
 202         info.length = len;
 203         info.low_limit = current->mm->mmap_base;
 204         info.high_limit = TASK_SIZE;
 205         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 206         info.align_offset = 0;
 207         return vm_unmapped_area(&info);
 208 }
 209
 210 static unsigned long
 211 hugetlb_get_unmapped_area_topdown(struct file *file, unsigned long addr,
 212                 unsigned long len, unsigned long pgoff, unsigned long flags)
 213 {
 214         struct hstate *h = hstate_file(file);
 215         struct vm_unmapped_area_info info;
 216
 217         info.flags = VM_UNMAPPED_AREA_TOPDOWN;
 218         info.length = len;
 219         info.low_limit = max(PAGE_SIZE, mmap_min_addr);
 220         info.high_limit = current->mm->mmap_base;
 221         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
 222         info.align_offset = 0;
 223         addr = vm_unmapped_area(&info);
 224
 225         /*
 226          * A failed mmap() very likely causes application failure,
 227          * so fall back to the bottom-up function here. This scenario
 228          * can happen with large stack limits and large mmap()
 229          * allocations.
 230          */
 231         if (unlikely(offset_in_page(addr))) {
 232                 VM_BUG_ON(addr != -ENOMEM);
 233                 info.flags = 0;
 234                 info.low_limit = current->mm->mmap_base;
 235                 info.high_limit = TASK_SIZE;
 236                 addr = vm_unmapped_area(&info);
 237         }
 238
 239         return addr;
 240 }
 241
 242 static unsigned long
 243 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 244                 unsigned long len, unsigned long pgoff, unsigned long flags)
 245 {
 246         struct mm_struct *mm = current->mm;
 247         struct vm_area_struct *vma;
 248         struct hstate *h = hstate_file(file);
 249
 250         if (len & ~huge_page_mask(h))
 251                 return -EINVAL;
 252         if (len > TASK_SIZE)
 253                 return -ENOMEM;
 254
 255         if (flags & MAP_FIXED) {
 256                 if (prepare_hugepage_range(file, addr, len))
 257                         return -EINVAL;
 258                 return addr;
 259         }
 260
 261         if (addr) {
 262                 addr = ALIGN(addr, huge_page_size(h));
 263                 vma = find_vma(mm, addr);
 264                 if (TASK_SIZE - len >= addr &&
 265                     (!vma || addr + len <= vm_start_gap(vma)))
 266                         return addr;
 267         }
 268
 269         /*
 270          * Use mm->get_unmapped_area value as a hint to use topdown routine.
 271          * If architectures have special needs, they should define their own
 272          * version of hugetlb_get_unmapped_area.
 273          */
 274         if (mm->get_unmapped_area == arch_get_unmapped_area_topdown)
 275                 return hugetlb_get_unmapped_area_topdown(file, addr, len,
 276                                 pgoff, flags);
 277         return hugetlb_get_unmapped_area_bottomup(file, addr, len,
 278                         pgoff, flags);
 279 }
 280 #endif
 281
 282 static size_t
 283 hugetlbfs_read_actor(struct page *page, unsigned long offset,
 284                         struct iov_iter *to, unsigned long size)
 285 {
 286         size_t copied = 0;
 287         int i, chunksize;
 288
 289         /* Find which 4k chunk and offset with in that chunk */
 290         i = offset >> PAGE_SHIFT;
 291         offset = offset & ~PAGE_MASK;
 292
 293         while (size) {
 294                 size_t n;
 295                 chunksize = PAGE_SIZE;
 296                 if (offset)
 297                         chunksize -= offset;
 298                 if (chunksize > size)
 299                         chunksize = size;
 300                 n = copy_page_to_iter(&page[i], offset, chunksize, to);
 301                 copied += n;
 302                 if (n != chunksize)
 303                         return copied;
 304                 offset = 0;
 305                 size -= chunksize;
 306                 i++;
 307         }
 308         return copied;
 309 }
 310
 311 /*
 312  * Support for read() - Find the page attached to f_mapping and copy out the
 313  * data. Its *very* similar to do_generic_mapping_read(), we can't use that
 314  * since it has PAGE_SIZE assumptions.
 315  */
 316 static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
 317 {
 318         struct file *file = iocb->ki_filp;
 319         struct hstate *h = hstate_file(file);
 320         struct address_space *mapping = file->f_mapping;
 321         struct inode *inode = mapping->host;
 322         unsigned long index = iocb->ki_pos >> huge_page_shift(h);
 323         unsigned long offset = iocb->ki_pos & ~huge_page_mask(h);
 324         unsigned long end_index;
 325         loff_t isize;
 326         ssize_t retval = 0;
 327
 328         while (iov_iter_count(to)) {
 329                 struct page *page;
 330                 size_t nr, copied;
 331
 332                 /* nr is the maximum number of bytes to copy from this page */
 333                 nr = huge_page_size(h);
 334                 isize = i_size_read(inode);
 335                 if (!isize)
 336                         break;
 337                 end_index = (isize - 1) >> huge_page_shift(h);
 338                 if (index > end_index)
 339                         break;
 340                 if (index == end_index) {
 341                         nr = ((isize - 1) & ~huge_page_mask(h)) + 1;
 342                         if (nr <= offset)
 343                                 break;
 344                 }
 345                 nr = nr - offset;
 346
 347                 /* Find the page */
 348                 page = find_lock_page(mapping, index);
 349                 if (unlikely(page == NULL)) {
 350                         /*
 351                          * We have a HOLE, zero out the user-buffer for the
 352                          * length of the hole or request.
 353                          */
 354                         copied = iov_iter_zero(nr, to);
 355                 } else {
 356                         unlock_page(page);
 357
 358                         /*
 359                          * We have the page, copy it to user space buffer.
 360                          */
 361                         copied = hugetlbfs_read_actor(page, offset, to, nr);
 362                         put_page(page);
 363                 }
 364                 offset += copied;
 365                 retval += copied;
 366                 if (copied != nr && iov_iter_count(to)) {
 367                         if (!retval)
 368                                 retval = -EFAULT;
 369                         break;
 370                 }
 371                 index += offset >> huge_page_shift(h);
 372                 offset &= ~huge_page_mask(h);
 373         }
 374         iocb->ki_pos = ((loff_t)index << huge_page_shift(h)) + offset;
 375         return retval;
 376 }
 377
 378 static int hugetlbfs_write_begin(struct file *file,
 379                         struct address_space *mapping,
 380                         loff_t pos, unsigned len, unsigned flags,
 381                         struct page **pagep, void **fsdata)
 382 {
 383         return -EINVAL;
 384 }
 385
 386 static int hugetlbfs_write_end(struct file *file, struct address_space *mapping,
 387                         loff_t pos, unsigned len, unsigned copied,
 388                         struct page *page, void *fsdata)
 389 {
 390         BUG();
 391         return -EINVAL;
 392 }
 393
 394 static void remove_huge_page(struct page *page)
 395 {
 396         ClearPageDirty(page);
 397         ClearPageUptodate(page);
 398         delete_from_page_cache(page);
 399 }
 400
 401 static void
 402 hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end)
 403 {
 404         struct vm_area_struct *vma;
 405
 406         /*
 407          * end == 0 indicates that the entire range after
 408          * start should be unmapped.
 409          */
 410         vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) {
 411                 unsigned long v_offset;
 412                 unsigned long v_end;
 413
 414                 /*
 415                  * Can the expression below overflow on 32-bit arches?
 416                  * No, because the interval tree returns us only those vmas
 417                  * which overlap the truncated area starting at pgoff,
 418                  * and no vma on a 32-bit arch can span beyond the 4GB.
 419                  */
 420                 if (vma->vm_pgoff < start)
 421                         v_offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
 422                 else
 423                         v_offset = 0;
 424
 425                 if (!end)
 426                         v_end = vma->vm_end;
 427                 else {
 428                         v_end = ((end - vma->vm_pgoff) << PAGE_SHIFT)
 429                                                         + vma->vm_start;
 430                         if (v_end > vma->vm_end)
 431                                 v_end = vma->vm_end;
 432                 }
 433
 434                 unmap_hugepage_range(vma, vma->vm_start + v_offset, v_end,
 435                                                                         NULL);
 436         }
 437 }
 438
 439 /*
 440  * remove_inode_hugepages handles two distinct cases: truncation and hole
 441  * punch.  There are subtle differences in operation for each case.
 442  *
 443  * truncation is indicated by end of range being LLONG_MAX
 444  *      In this case, we first scan the range and release found pages.
 445  *      After releasing pages, hugetlb_unreserve_pages cleans up region/reserv
 446  *      maps and global counts.  Page faults can not race with truncation
 447  *      in this routine.  hugetlb_no_page() holds i_mmap_rwsem and prevents
 448  *      page faults in the truncated range by checking i_size.  i_size is
 449  *      modified while holding i_mmap_rwsem.
 450  * hole punch is indicated if end is not LLONG_MAX
 451  *      In the hole punch case we scan the range and release found pages.
 452  *      Only when releasing a page is the associated region/reserv map
 453  *      deleted.  The region/reserv map for ranges without associated
 454  *      pages are not modified.  Page faults can race with hole punch.
 455  *      This is indicated if we find a mapped page.
 456  * Note: If the passed end of range value is beyond the end of file, but
 457  * not LLONG_MAX this routine still performs a hole punch operation.
 458  */
 459 static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
 460                                    loff_t lend)
 461 {
 462         struct hstate *h = hstate_inode(inode);
 463         struct address_space *mapping = &inode->i_data;
 464         const pgoff_t start = lstart >> huge_page_shift(h);
 465         const pgoff_t end = lend >> huge_page_shift(h);
 466         struct vm_area_struct pseudo_vma;
 467         struct pagevec pvec;
 468         pgoff_t next, index;
 469         int i, freed = 0;
 470         bool truncate_op = (lend == LLONG_MAX);
 471
 472         vma_init(&pseudo_vma, current->mm);
 473         pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
 474         pagevec_init(&pvec);
 475         next = start;
 476         while (next < end) {
 477                 /*
 478                  * When no more pages are found, we are done.
 479                  */
 480                 if (!pagevec_lookup_range(&pvec, mapping, &next, end - 1))
 481                         break;
 482
 483                 for (i = 0; i < pagevec_count(&pvec); ++i) {
 484                         struct page *page = pvec.pages[i];
 485                         u32 hash;
 486
 487                         index = page->index;
 488                         hash = hugetlb_fault_mutex_hash(mapping, index);
 489                         if (!truncate_op) {
 490                                 /*
 491                                  * Only need to hold the fault mutex in the
 492                                  * hole punch case.  This prevents races with
 493                                  * page faults.  Races are not possible in the
 494                                  * case of truncation.
 495                                  */
 496                                 mutex_lock(&hugetlb_fault_mutex_table[hash]);
 497                         }
 498
 499                         /*
 500                          * If page is mapped, it was faulted in after being
 501                          * unmapped in caller.  Unmap (again) now after taking
 502                          * the fault mutex.  The mutex will prevent faults
 503                          * until we finish removing the page.
 504                          *
 505                          * This race can only happen in the hole punch case.
 506                          * Getting here in a truncate operation is a bug.
 507                          */
 508                         if (unlikely(page_mapped(page))) {
 509                                 BUG_ON(truncate_op);
 510
 511                                 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 512                                 i_mmap_lock_write(mapping);
 513                                 mutex_lock(&hugetlb_fault_mutex_table[hash]);
 514                                 hugetlb_vmdelete_list(&mapping->i_mmap,
 515                                         index * pages_per_huge_page(h),
 516                                         (index + 1) * pages_per_huge_page(h));
 517                                 i_mmap_unlock_write(mapping);
 518                         }
 519
 520                         lock_page(page);
 521                         /*
 522                          * We must free the huge page and remove from page
 523                          * cache (remove_huge_page) BEFORE removing the
 524                          * region/reserve map (hugetlb_unreserve_pages).  In
 525                          * rare out of memory conditions, removal of the
 526                          * region/reserve map could fail. Correspondingly,
 527                          * the subpool and global reserve usage count can need
 528                          * to be adjusted.
 529                          */
 530                         VM_BUG_ON(PagePrivate(page));
 531                         remove_huge_page(page);
 532                         freed++;
 533                         if (!truncate_op) {
 534                                 if (unlikely(hugetlb_unreserve_pages(inode,
 535                                                         index, index + 1, 1)))
 536                                         hugetlb_fix_reserve_counts(inode);
 537                         }
 538
 539                         unlock_page(page);
 540                         if (!truncate_op)
 541                                 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 542                 }
 543                 huge_pagevec_release(&pvec);
 544                 cond_resched();
 545         }
 546
 547         if (truncate_op)
 548                 (void)hugetlb_unreserve_pages(inode, start, LONG_MAX, freed);
 549 }
 550
 551 static void hugetlbfs_evict_inode(struct inode *inode)
 552 {
 553         struct resv_map *resv_map;
 554
 555         remove_inode_hugepages(inode, 0, LLONG_MAX);
 556
 557         /*
 558          * Get the resv_map from the address space embedded in the inode.
 559          * This is the address space which points to any resv_map allocated
 560          * at inode creation time.  If this is a device special inode,
 561          * i_mapping may not point to the original address space.
 562          */
 563         resv_map = (struct resv_map *)(&inode->i_data)->private_data;
 564         /* Only regular and link inodes have associated reserve maps */
 565         if (resv_map)
 566                 resv_map_release(&resv_map->refs);
 567         clear_inode(inode);
 568 }
 569
 570 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 571 {
 572         pgoff_t pgoff;
 573         struct address_space *mapping = inode->i_mapping;
 574         struct hstate *h = hstate_inode(inode);
 575
 576         BUG_ON(offset & ~huge_page_mask(h));
 577         pgoff = offset >> PAGE_SHIFT;
 578
 579         i_mmap_lock_write(mapping);
 580         i_size_write(inode, offset);
 581         if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
 582                 hugetlb_vmdelete_list(&mapping->i_mmap, pgoff, 0);
 583         i_mmap_unlock_write(mapping);
 584         remove_inode_hugepages(inode, offset, LLONG_MAX);
 585         return 0;
 586 }
 587
 588 static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
 589 {
 590         struct hstate *h = hstate_inode(inode);
 591         loff_t hpage_size = huge_page_size(h);
 592         loff_t hole_start, hole_end;
 593
 594         /*
 595          * For hole punch round up the beginning offset of the hole and
 596          * round down the end.
 597          */
 598         hole_start = round_up(offset, hpage_size);
 599         hole_end = round_down(offset + len, hpage_size);
 600
 601         if (hole_end > hole_start) {
 602                 struct address_space *mapping = inode->i_mapping;
 603                 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 604
 605                 inode_lock(inode);
 606
 607                 /* protected by i_mutex */
 608                 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
 609                         inode_unlock(inode);
 610                         return -EPERM;
 611                 }
 612
 613                 i_mmap_lock_write(mapping);
 614                 if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
 615                         hugetlb_vmdelete_list(&mapping->i_mmap,
 616                                                 hole_start >> PAGE_SHIFT,
 617                                                 hole_end  >> PAGE_SHIFT);
 618                 i_mmap_unlock_write(mapping);
 619                 remove_inode_hugepages(inode, hole_start, hole_end);
 620                 inode_unlock(inode);
 621         }
 622
 623         return 0;
 624 }
 625
 626 static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
 627                                 loff_t len)
 628 {
 629         struct inode *inode = file_inode(file);
 630         struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 631         struct address_space *mapping = inode->i_mapping;
 632         struct hstate *h = hstate_inode(inode);
 633         struct vm_area_struct pseudo_vma;
 634         struct mm_struct *mm = current->mm;
 635         loff_t hpage_size = huge_page_size(h);
 636         unsigned long hpage_shift = huge_page_shift(h);
 637         pgoff_t start, index, end;
 638         int error;
 639         u32 hash;
 640
 641         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
 642                 return -EOPNOTSUPP;
 643
 644         if (mode & FALLOC_FL_PUNCH_HOLE)
 645                 return hugetlbfs_punch_hole(inode, offset, len);
 646
 647         /*
 648          * Default preallocate case.
 649          * For this range, start is rounded down and end is rounded up
 650          * as well as being converted to page offsets.
 651          */
 652         start = offset >> hpage_shift;
 653         end = (offset + len + hpage_size - 1) >> hpage_shift;
 654
 655         inode_lock(inode);
 656
 657         /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
 658         error = inode_newsize_ok(inode, offset + len);
 659         if (error)
 660                 goto out;
 661
 662         if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
 663                 error = -EPERM;
 664                 goto out;
 665         }
 666
 667         /*
 668          * Initialize a pseudo vma as this is required by the huge page
 669          * allocation routines.  If NUMA is configured, use page index
 670          * as input to create an allocation policy.
 671          */
 672         vma_init(&pseudo_vma, mm);
 673         pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
 674         pseudo_vma.vm_file = file;
 675
 676         for (index = start; index < end; index++) {
 677                 /*
 678                  * This is supposed to be the vaddr where the page is being
 679                  * faulted in, but we have no vaddr here.
 680                  */
 681                 struct page *page;
 682                 unsigned long addr;
 683                 int avoid_reserve = 0;
 684
 685                 cond_resched();
 686
 687                 /*
 688                  * fallocate(2) manpage permits EINTR; we may have been
 689                  * interrupted because we are using up too much memory.
 690                  */
 691                 if (signal_pending(current)) {
 692                         error = -EINTR;
 693                         break;
 694                 }
 695
 696                 /* Set numa allocation policy based on index */
 697                 hugetlb_set_vma_policy(&pseudo_vma, inode, index);
 698
 699                 /* addr is the offset within the file (zero based) */
 700                 addr = index * hpage_size;
 701
 702                 /*
 703                  * fault mutex taken here, protects against fault path
 704                  * and hole punch.  inode_lock previously taken protects
 705                  * against truncation.
 706                  */
 707                 hash = hugetlb_fault_mutex_hash(mapping, index);
 708                 mutex_lock(&hugetlb_fault_mutex_table[hash]);
 709
 710                 /* See if already present in mapping to avoid alloc/free */
 711                 page = find_get_page(mapping, index);
 712                 if (page) {
 713                         put_page(page);
 714                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 715                         hugetlb_drop_vma_policy(&pseudo_vma);
 716                         continue;
 717                 }
 718
 719                 /* Allocate page and add to page cache */
 720                 page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
 721                 hugetlb_drop_vma_policy(&pseudo_vma);
 722                 if (IS_ERR(page)) {
 723                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 724                         error = PTR_ERR(page);
 725                         goto out;
 726                 }
 727                 clear_huge_page(page, addr, pages_per_huge_page(h));
 728                 __SetPageUptodate(page);
 729                 error = huge_add_to_page_cache(page, mapping, index);
 730                 if (unlikely(error)) {
 731                         put_page(page);
 732                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 733                         goto out;
 734                 }
 735
 736                 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
 737
 738                 /*
 739                  * unlock_page because locked by add_to_page_cache()
 740                  * page_put due to reference from alloc_huge_page()
 741                  */
 742                 unlock_page(page);
 743                 put_page(page);
 744         }
 745
 746         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
 747                 i_size_write(inode, offset + len);
 748         inode->i_ctime = current_time(inode);
 749 out:
 750         inode_unlock(inode);
 751         return error;
 752 }
 753
 754 static int hugetlbfs_setattr(struct user_namespace *mnt_userns,
 755                              struct dentry *dentry, struct iattr *attr)
 756 {
 757         struct inode *inode = d_inode(dentry);
 758         struct hstate *h = hstate_inode(inode);
 759         int error;
 760         unsigned int ia_valid = attr->ia_valid;
 761         struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 762
 763         BUG_ON(!inode);
 764
 765         error = setattr_prepare(&init_user_ns, dentry, attr);
 766         if (error)
 767                 return error;
 768
 769         if (ia_valid & ATTR_SIZE) {
 770                 loff_t oldsize = inode->i_size;
 771                 loff_t newsize = attr->ia_size;
 772
 773                 if (newsize & ~huge_page_mask(h))
 774                         return -EINVAL;
 775                 /* protected by i_mutex */
 776                 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
 777                     (newsize > oldsize && (info->seals & F_SEAL_GROW)))
 778                         return -EPERM;
 779                 error = hugetlb_vmtruncate(inode, newsize);
 780                 if (error)
 781                         return error;
 782         }
 783
 784         setattr_copy(&init_user_ns, inode, attr);
 785         mark_inode_dirty(inode);
 786         return 0;
 787 }
 788
 789 static struct inode *hugetlbfs_get_root(struct super_block *sb,
 790                                         struct hugetlbfs_fs_context *ctx)
 791 {
 792         struct inode *inode;
 793
 794         inode = new_inode(sb);
 795         if (inode) {
 796                 inode->i_ino = get_next_ino();
 797                 inode->i_mode = S_IFDIR | ctx->mode;
 798                 inode->i_uid = ctx->uid;
 799                 inode->i_gid = ctx->gid;
 800                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 801                 inode->i_op = &hugetlbfs_dir_inode_operations;
 802                 inode->i_fop = &simple_dir_operations;
 803                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
 804                 inc_nlink(inode);
 805                 lockdep_annotate_inode_mutex_key(inode);
 806         }
 807         return inode;
 808 }
 809
 810 /*
 811  * Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
 812  * be taken from reclaim -- unlike regular filesystems. This needs an
 813  * annotation because huge_pmd_share() does an allocation under hugetlb's
 814  * i_mmap_rwsem.
 815  */
 816 static struct lock_class_key hugetlbfs_i_mmap_rwsem_key;
 817
 818 static struct inode *hugetlbfs_get_inode(struct super_block *sb,
 819                                         struct inode *dir,
 820                                         umode_t mode, dev_t dev)
 821 {
 822         struct inode *inode;
 823         struct resv_map *resv_map = NULL;
 824
 825         /*
 826          * Reserve maps are only needed for inodes that can have associated
 827          * page allocations.
 828          */
 829         if (S_ISREG(mode) || S_ISLNK(mode)) {
 830                 resv_map = resv_map_alloc();
 831                 if (!resv_map)
 832                         return NULL;
 833         }
 834
 835         inode = new_inode(sb);
 836         if (inode) {
 837                 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
 838
 839                 inode->i_ino = get_next_ino();
 840                 inode_init_owner(&init_user_ns, inode, dir, mode);
 841                 lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
 842                                 &hugetlbfs_i_mmap_rwsem_key);
 843                 inode->i_mapping->a_ops = &hugetlbfs_aops;
 844                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
 845                 inode->i_mapping->private_data = resv_map;
 846                 info->seals = F_SEAL_SEAL;
 847                 switch (mode & S_IFMT) {
 848                 default:
 849                         init_special_inode(inode, mode, dev);
 850                         break;
 851                 case S_IFREG:
 852                         inode->i_op = &hugetlbfs_inode_operations;
 853                         inode->i_fop = &hugetlbfs_file_operations;
 854                         break;
 855                 case S_IFDIR:
 856                         inode->i_op = &hugetlbfs_dir_inode_operations;
 857                         inode->i_fop = &simple_dir_operations;
 858
 859                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 860                         inc_nlink(inode);
 861                         break;
 862                 case S_IFLNK:
 863                         inode->i_op = &page_symlink_inode_operations;
 864                         inode_nohighmem(inode);
 865                         break;
 866                 }
 867                 lockdep_annotate_inode_mutex_key(inode);
 868         } else {
 869                 if (resv_map)
 870                         kref_put(&resv_map->refs, resv_map_release);
 871         }
 872
 873         return inode;
 874 }
 875
 876 /*
 877  * File creation. Allocate an inode, and we're done..
 878  */
 879 static int do_hugetlbfs_mknod(struct inode *dir,
 880                         struct dentry *dentry,
 881                         umode_t mode,
 882                         dev_t dev,
 883                         bool tmpfile)
 884 {
 885         struct inode *inode;
 886         int error = -ENOSPC;
 887
 888         inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
 889         if (inode) {
 890                 dir->i_ctime = dir->i_mtime = current_time(dir);
 891                 if (tmpfile) {
 892                         d_tmpfile(dentry, inode);
 893                 } else {
 894                         d_instantiate(dentry, inode);
 895                         dget(dentry);/* Extra count - pin the dentry in core */
 896                 }
 897                 error = 0;
 898         }
 899         return error;
 900 }
 901
 902 static int hugetlbfs_mknod(struct user_namespace *mnt_userns, struct inode *dir,
 903                            struct dentry *dentry, umode_t mode, dev_t dev)
 904 {
 905         return do_hugetlbfs_mknod(dir, dentry, mode, dev, false);
 906 }
 907
 908 static int hugetlbfs_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
 909                            struct dentry *dentry, umode_t mode)
 910 {
 911         int retval = hugetlbfs_mknod(&init_user_ns, dir, dentry,
 912                                      mode | S_IFDIR, 0);
 913         if (!retval)
 914                 inc_nlink(dir);
 915         return retval;
 916 }
 917
 918 static int hugetlbfs_create(struct user_namespace *mnt_userns,
 919                             struct inode *dir, struct dentry *dentry,
 920                             umode_t mode, bool excl)
 921 {
 922         return hugetlbfs_mknod(&init_user_ns, dir, dentry, mode | S_IFREG, 0);
 923 }
 924
 925 static int hugetlbfs_tmpfile(struct user_namespace *mnt_userns,
 926                              struct inode *dir, struct dentry *dentry,
 927                              umode_t mode)
 928 {
 929         return do_hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0, true);
 930 }
 931
 932 static int hugetlbfs_symlink(struct user_namespace *mnt_userns,
 933                              struct inode *dir, struct dentry *dentry,
 934                              const char *symname)
 935 {
 936         struct inode *inode;
 937         int error = -ENOSPC;
 938
 939         inode = hugetlbfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
 940         if (inode) {
 941                 int l = strlen(symname)+1;
 942                 error = page_symlink(inode, symname, l);
 943                 if (!error) {
 944                         d_instantiate(dentry, inode);
 945                         dget(dentry);
 946                 } else
 947                         iput(inode);
 948         }
 949         dir->i_ctime = dir->i_mtime = current_time(dir);
 950
 951         return error;
 952 }
 953
 954 /*
 955  * mark the head page dirty
 956  */
 957 static int hugetlbfs_set_page_dirty(struct page *page)
 958 {
 959         struct page *head = compound_head(page);
 960
 961         SetPageDirty(head);
 962         return 0;
 963 }
 964
 965 static int hugetlbfs_migrate_page(struct address_space *mapping,
 966                                 struct page *newpage, struct page *page,
 967                                 enum migrate_mode mode)
 968 {
 969         int rc;
 970
 971         rc = migrate_huge_page_move_mapping(mapping, newpage, page);
 972         if (rc != MIGRATEPAGE_SUCCESS)
 973                 return rc;
 974
 975         /*
 976          * page_private is subpool pointer in hugetlb pages.  Transfer to
 977          * new page.  PagePrivate is not associated with page_private for
 978          * hugetlb pages and can not be set here as only page_huge_active
 979          * pages can be migrated.
 980          */
 981         if (page_private(page)) {
 982                 set_page_private(newpage, page_private(page));
 983                 set_page_private(page, 0);
 984         }
 985
 986         if (mode != MIGRATE_SYNC_NO_COPY)
 987                 migrate_page_copy(newpage, page);
 988         else
 989                 migrate_page_states(newpage, page);
 990
 991         return MIGRATEPAGE_SUCCESS;
 992 }
 993
 994 static int hugetlbfs_error_remove_page(struct address_space *mapping,
 995                                 struct page *page)
 996 {
 997         struct inode *inode = mapping->host;
 998         pgoff_t index = page->index;
 999
1000         remove_huge_page(page);
1001         if (unlikely(hugetlb_unreserve_pages(inode, index, index + 1, 1)))
1002                 hugetlb_fix_reserve_counts(inode);
1003
1004         return 0;
1005 }
1006
1007 /*
1008  * Display the mount options in /proc/mounts.
1009  */
1010 static int hugetlbfs_show_options(struct seq_file *m, struct dentry *root)
1011 {
1012         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(root->d_sb);
1013         struct hugepage_subpool *spool = sbinfo->spool;
1014         unsigned long hpage_size = huge_page_size(sbinfo->hstate);
1015         unsigned hpage_shift = huge_page_shift(sbinfo->hstate);
1016         char mod;
1017
1018         if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
1019                 seq_printf(m, ",uid=%u",
1020                            from_kuid_munged(&init_user_ns, sbinfo->uid));
1021         if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
1022                 seq_printf(m, ",gid=%u",
1023                            from_kgid_munged(&init_user_ns, sbinfo->gid));
1024         if (sbinfo->mode != 0755)
1025                 seq_printf(m, ",mode=%o", sbinfo->mode);
1026         if (sbinfo->max_inodes != -1)
1027                 seq_printf(m, ",nr_inodes=%lu", sbinfo->max_inodes);
1028
1029         hpage_size /= 1024;
1030         mod = 'K';
1031         if (hpage_size >= 1024) {
1032                 hpage_size /= 1024;
1033                 mod = 'M';
1034         }
1035         seq_printf(m, ",pagesize=%lu%c", hpage_size, mod);
1036         if (spool) {
1037                 if (spool->max_hpages != -1)
1038                         seq_printf(m, ",size=%llu",
1039                                    (unsigned long long)spool->max_hpages << hpage_shift);
1040                 if (spool->min_hpages != -1)
1041                         seq_printf(m, ",min_size=%llu",
1042                                    (unsigned long long)spool->min_hpages << hpage_shift);
1043         }
1044         return 0;
1045 }
1046
1047 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1048 {
1049         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
1050         struct hstate *h = hstate_inode(d_inode(dentry));
1051
1052         buf->f_type = HUGETLBFS_MAGIC;
1053         buf->f_bsize = huge_page_size(h);
1054         if (sbinfo) {
1055                 spin_lock(&sbinfo->stat_lock);
1056                 /* If no limits set, just report 0 for max/free/used
1057                  * blocks, like simple_statfs() */
1058                 if (sbinfo->spool) {
1059                         long free_pages;
1060
1061                         spin_lock(&sbinfo->spool->lock);
1062                         buf->f_blocks = sbinfo->spool->max_hpages;
1063                         free_pages = sbinfo->spool->max_hpages
1064                                 - sbinfo->spool->used_hpages;
1065                         buf->f_bavail = buf->f_bfree = free_pages;
1066                         spin_unlock(&sbinfo->spool->lock);
1067                         buf->f_files = sbinfo->max_inodes;
1068                         buf->f_ffree = sbinfo->free_inodes;
1069                 }
1070                 spin_unlock(&sbinfo->stat_lock);
1071         }
1072         buf->f_namelen = NAME_MAX;
1073         return 0;
1074 }
1075
1076 static void hugetlbfs_put_super(struct super_block *sb)
1077 {
1078         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
1079
1080         if (sbi) {
1081                 sb->s_fs_info = NULL;
1082
1083                 if (sbi->spool)
1084                         hugepage_put_subpool(sbi->spool);
1085
1086                 kfree(sbi);
1087         }
1088 }
1089
1090 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1091 {
1092         if (sbinfo->free_inodes >= 0) {
1093                 spin_lock(&sbinfo->stat_lock);
1094                 if (unlikely(!sbinfo->free_inodes)) {
1095                         spin_unlock(&sbinfo->stat_lock);
1096                         return 0;
1097                 }
1098                 sbinfo->free_inodes--;
1099                 spin_unlock(&sbinfo->stat_lock);
1100         }
1101
1102         return 1;
1103 }
1104
1105 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1106 {
1107         if (sbinfo->free_inodes >= 0) {
1108                 spin_lock(&sbinfo->stat_lock);
1109                 sbinfo->free_inodes++;
1110                 spin_unlock(&sbinfo->stat_lock);
1111         }
1112 }
1113
1114
1115 static struct kmem_cache *hugetlbfs_inode_cachep;
1116
1117 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
1118 {
1119         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
1120         struct hugetlbfs_inode_info *p;
1121
1122         if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
1123                 return NULL;
1124         p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);
1125         if (unlikely(!p)) {
1126                 hugetlbfs_inc_free_inodes(sbinfo);
1127                 return NULL;
1128         }
1129
1130         /*
1131          * Any time after allocation, hugetlbfs_destroy_inode can be called
1132          * for the inode.  mpol_free_shared_policy is unconditionally called
1133          * as part of hugetlbfs_destroy_inode.  So, initialize policy here
1134          * in case of a quick call to destroy.
1135          *
1136          * Note that the policy is initialized even if we are creating a
1137          * private inode.  This simplifies hugetlbfs_destroy_inode.
1138          */
1139         mpol_shared_policy_init(&p->policy, NULL);
1140
1141         return &p->vfs_inode;
1142 }
1143
1144 static void hugetlbfs_free_inode(struct inode *inode)
1145 {
1146         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
1147 }
1148
1149 static void hugetlbfs_destroy_inode(struct inode *inode)
1150 {
1151         hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
1152         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
1153 }
1154
1155 static const struct address_space_operations hugetlbfs_aops = {
1156         .write_begin    = hugetlbfs_write_begin,
1157         .write_end      = hugetlbfs_write_end,
1158         .set_page_dirty = hugetlbfs_set_page_dirty,
1159         .migratepage    = hugetlbfs_migrate_page,
1160         .error_remove_page      = hugetlbfs_error_remove_page,
1161 };
1162
1163
1164 static void init_once(void *foo)
1165 {
1166         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
1167
1168         inode_init_once(&ei->vfs_inode);
1169 }
1170
1171 const struct file_operations hugetlbfs_file_operations = {
1172         .read_iter              = hugetlbfs_read_iter,
1173         .mmap                   = hugetlbfs_file_mmap,
1174         .fsync                  = noop_fsync,
1175         .get_unmapped_area      = hugetlb_get_unmapped_area,
1176         .llseek                 = default_llseek,
1177         .fallocate              = hugetlbfs_fallocate,
1178 };
1179
1180 static const struct inode_operations hugetlbfs_dir_inode_operations = {
1181         .create         = hugetlbfs_create,
1182         .lookup         = simple_lookup,
1183         .link           = simple_link,
1184         .unlink         = simple_unlink,
1185         .symlink        = hugetlbfs_symlink,
1186         .mkdir          = hugetlbfs_mkdir,
1187         .rmdir          = simple_rmdir,
1188         .mknod          = hugetlbfs_mknod,
1189         .rename         = simple_rename,
1190         .setattr        = hugetlbfs_setattr,
1191         .tmpfile        = hugetlbfs_tmpfile,
1192 };
1193
1194 static const struct inode_operations hugetlbfs_inode_operations = {
1195         .setattr        = hugetlbfs_setattr,
1196 };
1197
1198 static const struct super_operations hugetlbfs_ops = {
1199         .alloc_inode    = hugetlbfs_alloc_inode,
1200         .free_inode     = hugetlbfs_free_inode,
1201         .destroy_inode  = hugetlbfs_destroy_inode,
1202         .evict_inode    = hugetlbfs_evict_inode,
1203         .statfs         = hugetlbfs_statfs,
1204         .put_super      = hugetlbfs_put_super,
1205         .show_options   = hugetlbfs_show_options,
1206 };
1207
1208 /*
1209  * Convert size option passed from command line to number of huge pages
1210  * in the pool specified by hstate.  Size option could be in bytes
1211  * (val_type == SIZE_STD) or percentage of the pool (val_type == SIZE_PERCENT).
1212  */
1213 static long
1214 hugetlbfs_size_to_hpages(struct hstate *h, unsigned long long size_opt,
1215                          enum hugetlbfs_size_type val_type)
1216 {
1217         if (val_type == NO_SIZE)
1218                 return -1;
1219
1220         if (val_type == SIZE_PERCENT) {
1221                 size_opt <<= huge_page_shift(h);
1222                 size_opt *= h->max_huge_pages;
1223                 do_div(size_opt, 100);
1224         }
1225
1226         size_opt >>= huge_page_shift(h);
1227         return size_opt;
1228 }
1229
1230 /*
1231  * Parse one mount parameter.
1232  */
1233 static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
1234 {
1235         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1236         struct fs_parse_result result;
1237         char *rest;
1238         unsigned long ps;
1239         int opt;
1240
1241         opt = fs_parse(fc, hugetlb_fs_parameters, param, &result);
1242         if (opt < 0)
1243                 return opt;
1244
1245         switch (opt) {
1246         case Opt_uid:
1247                 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
1248                 if (!uid_valid(ctx->uid))
1249                         goto bad_val;
1250                 return 0;
1251
1252         case Opt_gid:
1253                 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
1254                 if (!gid_valid(ctx->gid))
1255                         goto bad_val;
1256                 return 0;
1257
1258         case Opt_mode:
1259                 ctx->mode = result.uint_32 & 01777U;
1260                 return 0;
1261
1262         case Opt_size:
1263                 /* memparse() will accept a K/M/G without a digit */
1264                 if (!isdigit(param->string[0]))
1265                         goto bad_val;
1266                 ctx->max_size_opt = memparse(param->string, &rest);
1267                 ctx->max_val_type = SIZE_STD;
1268                 if (*rest == '%')
1269                         ctx->max_val_type = SIZE_PERCENT;
1270                 return 0;
1271
1272         case Opt_nr_inodes:
1273                 /* memparse() will accept a K/M/G without a digit */
1274                 if (!isdigit(param->string[0]))
1275                         goto bad_val;
1276                 ctx->nr_inodes = memparse(param->string, &rest);
1277                 return 0;
1278
1279         case Opt_pagesize:
1280                 ps = memparse(param->string, &rest);
1281                 ctx->hstate = size_to_hstate(ps);
1282                 if (!ctx->hstate) {
1283                         pr_err("Unsupported page size %lu MB\n", ps >> 20);
1284                         return -EINVAL;
1285                 }
1286                 return 0;
1287
1288         case Opt_min_size:
1289                 /* memparse() will accept a K/M/G without a digit */
1290                 if (!isdigit(param->string[0]))
1291                         goto bad_val;
1292                 ctx->min_size_opt = memparse(param->string, &rest);
1293                 ctx->min_val_type = SIZE_STD;
1294                 if (*rest == '%')
1295                         ctx->min_val_type = SIZE_PERCENT;
1296                 return 0;
1297
1298         default:
1299                 return -EINVAL;
1300         }
1301
1302 bad_val:
1303         return invalfc(fc, "Bad value '%s' for mount option '%s'\n",
1304                       param->string, param->key);
1305 }
1306
1307 /*
1308  * Validate the parsed options.
1309  */
1310 static int hugetlbfs_validate(struct fs_context *fc)
1311 {
1312         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1313
1314         /*
1315          * Use huge page pool size (in hstate) to convert the size
1316          * options to number of huge pages.  If NO_SIZE, -1 is returned.
1317          */
1318         ctx->max_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
1319                                                    ctx->max_size_opt,
1320                                                    ctx->max_val_type);
1321         ctx->min_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
1322                                                    ctx->min_size_opt,
1323                                                    ctx->min_val_type);
1324
1325         /*
1326          * If max_size was specified, then min_size must be smaller
1327          */
1328         if (ctx->max_val_type > NO_SIZE &&
1329             ctx->min_hpages > ctx->max_hpages) {
1330                 pr_err("Minimum size can not be greater than maximum size\n");
1331                 return -EINVAL;
1332         }
1333
1334         return 0;
1335 }
1336
1337 static int
1338 hugetlbfs_fill_super(struct super_block *sb, struct fs_context *fc)
1339 {
1340         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1341         struct hugetlbfs_sb_info *sbinfo;
1342
1343         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
1344         if (!sbinfo)
1345                 return -ENOMEM;
1346         sb->s_fs_info = sbinfo;
1347         spin_lock_init(&sbinfo->stat_lock);
1348         sbinfo->hstate          = ctx->hstate;
1349         sbinfo->max_inodes      = ctx->nr_inodes;
1350         sbinfo->free_inodes     = ctx->nr_inodes;
1351         sbinfo->spool           = NULL;
1352         sbinfo->uid             = ctx->uid;
1353         sbinfo->gid             = ctx->gid;
1354         sbinfo->mode            = ctx->mode;
1355
1356         /*
1357          * Allocate and initialize subpool if maximum or minimum size is
1358          * specified.  Any needed reservations (for minimim size) are taken
1359          * taken when the subpool is created.
1360          */
1361         if (ctx->max_hpages != -1 || ctx->min_hpages != -1) {
1362                 sbinfo->spool = hugepage_new_subpool(ctx->hstate,
1363                                                      ctx->max_hpages,
1364                                                      ctx->min_hpages);
1365                 if (!sbinfo->spool)
1366                         goto out_free;
1367         }
1368         sb->s_maxbytes = MAX_LFS_FILESIZE;
1369         sb->s_blocksize = huge_page_size(ctx->hstate);
1370         sb->s_blocksize_bits = huge_page_shift(ctx->hstate);
1371         sb->s_magic = HUGETLBFS_MAGIC;
1372         sb->s_op = &hugetlbfs_ops;
1373         sb->s_time_gran = 1;
1374
1375         /*
1376          * Due to the special and limited functionality of hugetlbfs, it does
1377          * not work well as a stacking filesystem.
1378          */
1379         sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
1380         sb->s_root = d_make_root(hugetlbfs_get_root(sb, ctx));
1381         if (!sb->s_root)
1382                 goto out_free;
1383         return 0;
1384 out_free:
1385         kfree(sbinfo->spool);
1386         kfree(sbinfo);
1387         return -ENOMEM;
1388 }
1389
1390 static int hugetlbfs_get_tree(struct fs_context *fc)
1391 {
1392         int err = hugetlbfs_validate(fc);
1393         if (err)
1394                 return err;
1395         return get_tree_nodev(fc, hugetlbfs_fill_super);
1396 }
1397
1398 static void hugetlbfs_fs_context_free(struct fs_context *fc)
1399 {
1400         kfree(fc->fs_private);
1401 }
1402
1403 static const struct fs_context_operations hugetlbfs_fs_context_ops = {
1404         .free           = hugetlbfs_fs_context_free,
1405         .parse_param    = hugetlbfs_parse_param,
1406         .get_tree       = hugetlbfs_get_tree,
1407 };
1408
1409 static int hugetlbfs_init_fs_context(struct fs_context *fc)
1410 {
1411         struct hugetlbfs_fs_context *ctx;
1412
1413         ctx = kzalloc(sizeof(struct hugetlbfs_fs_context), GFP_KERNEL);
1414         if (!ctx)
1415                 return -ENOMEM;
1416
1417         ctx->max_hpages = -1; /* No limit on size by default */
1418         ctx->nr_inodes  = -1; /* No limit on number of inodes by default */
1419         ctx->uid        = current_fsuid();
1420         ctx->gid        = current_fsgid();
1421         ctx->mode       = 0755;
1422         ctx->hstate     = &default_hstate;
1423         ctx->min_hpages = -1; /* No default minimum size */
1424         ctx->max_val_type = NO_SIZE;
1425         ctx->min_val_type = NO_SIZE;
1426         fc->fs_private = ctx;
1427         fc->ops = &hugetlbfs_fs_context_ops;
1428         return 0;
1429 }
1430
1431 static struct file_system_type hugetlbfs_fs_type = {
1432         .name                   = "hugetlbfs",
1433         .init_fs_context        = hugetlbfs_init_fs_context,
1434         .parameters             = hugetlb_fs_parameters,
1435         .kill_sb                = kill_litter_super,
1436 };
1437
1438 static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE];
1439
1440 static int can_do_hugetlb_shm(void)
1441 {
1442         kgid_t shm_group;
1443         shm_group = make_kgid(&init_user_ns, sysctl_hugetlb_shm_group);
1444         return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
1445 }
1446
1447 static int get_hstate_idx(int page_size_log)
1448 {
1449         struct hstate *h = hstate_sizelog(page_size_log);
1450
1451         if (!h)
1452                 return -1;
1453         return h - hstates;
1454 }
1455
1456 /*
1457  * Note that size should be aligned to proper hugepage size in caller side,
1458  * otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
1459  */
1460 struct file *hugetlb_file_setup(const char *name, size_t size,
1461                                 vm_flags_t acctflag, struct user_struct **user,
1462                                 int creat_flags, int page_size_log)
1463 {
1464         struct inode *inode;
1465         struct vfsmount *mnt;
1466         int hstate_idx;
1467         struct file *file;
1468
1469         hstate_idx = get_hstate_idx(page_size_log);
1470         if (hstate_idx < 0)
1471                 return ERR_PTR(-ENODEV);
1472
1473         *user = NULL;
1474         mnt = hugetlbfs_vfsmount[hstate_idx];
1475         if (!mnt)
1476                 return ERR_PTR(-ENOENT);
1477
1478         if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
1479                 *user = current_user();
1480                 if (user_shm_lock(size, *user)) {
1481                         task_lock(current);
1482                         pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is deprecated\n",
1483                                 current->comm, current->pid);
1484                         task_unlock(current);
1485                 } else {
1486                         *user = NULL;
1487                         return ERR_PTR(-EPERM);
1488                 }
1489         }
1490
1491         file = ERR_PTR(-ENOSPC);
1492         inode = hugetlbfs_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0);
1493         if (!inode)
1494                 goto out;
1495         if (creat_flags == HUGETLB_SHMFS_INODE)
1496                 inode->i_flags |= S_PRIVATE;
1497
1498         inode->i_size = size;
1499         clear_nlink(inode);
1500
1501         if (hugetlb_reserve_pages(inode, 0,
1502                         size >> huge_page_shift(hstate_inode(inode)), NULL,
1503                         acctflag))
1504                 file = ERR_PTR(-ENOMEM);
1505         else
1506                 file = alloc_file_pseudo(inode, mnt, name, O_RDWR,
1507                                         &hugetlbfs_file_operations);
1508         if (!IS_ERR(file))
1509                 return file;
1510
1511         iput(inode);
1512 out:
1513         if (*user) {
1514                 user_shm_unlock(size, *user);
1515                 *user = NULL;
1516         }
1517         return file;
1518 }
1519
1520 static struct vfsmount *__init mount_one_hugetlbfs(struct hstate *h)
1521 {
1522         struct fs_context *fc;
1523         struct vfsmount *mnt;
1524
1525         fc = fs_context_for_mount(&hugetlbfs_fs_type, SB_KERNMOUNT);
1526         if (IS_ERR(fc)) {
1527                 mnt = ERR_CAST(fc);
1528         } else {
1529                 struct hugetlbfs_fs_context *ctx = fc->fs_private;
1530                 ctx->hstate = h;
1531                 mnt = fc_mount(fc);
1532                 put_fs_context(fc);
1533         }
1534         if (IS_ERR(mnt))
1535                 pr_err("Cannot mount internal hugetlbfs for page size %uK",
1536                        1U << (h->order + PAGE_SHIFT - 10));
1537         return mnt;
1538 }
1539
1540 static int __init init_hugetlbfs_fs(void)
1541 {
1542         struct vfsmount *mnt;
1543         struct hstate *h;
1544         int error;
1545         int i;
1546
1547         if (!hugepages_supported()) {
1548                 pr_info("disabling because there are no supported hugepage sizes\n");
1549                 return -ENOTSUPP;
1550         }
1551
1552         error = -ENOMEM;
1553         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
1554                                         sizeof(struct hugetlbfs_inode_info),
1555                                         0, SLAB_ACCOUNT, init_once);
1556         if (hugetlbfs_inode_cachep == NULL)
1557                 goto out;
1558
1559         error = register_filesystem(&hugetlbfs_fs_type);
1560         if (error)
1561                 goto out_free;
1562
1563         /* default hstate mount is required */
1564         mnt = mount_one_hugetlbfs(&hstates[default_hstate_idx]);
1565         if (IS_ERR(mnt)) {
1566                 error = PTR_ERR(mnt);
1567                 goto out_unreg;
1568         }
1569         hugetlbfs_vfsmount[default_hstate_idx] = mnt;
1570
1571         /* other hstates are optional */
1572         i = 0;
1573         for_each_hstate(h) {
1574                 if (i == default_hstate_idx) {
1575                         i++;
1576                         continue;
1577                 }
1578
1579                 mnt = mount_one_hugetlbfs(h);
1580                 if (IS_ERR(mnt))
1581                         hugetlbfs_vfsmount[i] = NULL;
1582                 else
1583                         hugetlbfs_vfsmount[i] = mnt;
1584                 i++;
1585         }
1586
1587         return 0;
1588
1589  out_unreg:
1590         (void)unregister_filesystem(&hugetlbfs_fs_type);
1591  out_free:
1592         kmem_cache_destroy(hugetlbfs_inode_cachep);
1593  out:
1594         return error;
1595 }
1596 fs_initcall(init_hugetlbfs_fs)