fs/hugetlbfs/inode.c

   1 /*
   2  * hugetlbpage-backed filesystem.  Based on ramfs.
   3  *
   4  * William Irwin, 2002
   5  *
   6  * Copyright (C) 2002 Linus Torvalds.
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/thread_info.h>
  11 #include <asm/current.h>
  12 #include <linux/sched.h>                /* remove ASAP */
  13 #include <linux/fs.h>
  14 #include <linux/mount.h>
  15 #include <linux/file.h>
  16 #include <linux/writeback.h>
  17 #include <linux/pagemap.h>
  18 #include <linux/highmem.h>
  19 #include <linux/init.h>
  20 #include <linux/string.h>
  21 #include <linux/capability.h>
  22 #include <linux/backing-dev.h>
  23 #include <linux/hugetlb.h>
  24 #include <linux/pagevec.h>
  25 #include <linux/mman.h>
  26 #include <linux/quotaops.h>
  27 #include <linux/slab.h>
  28 #include <linux/dnotify.h>
  29 #include <linux/statfs.h>
  30 #include <linux/security.h>
  31
  32 #include <asm/uaccess.h>
  33
  34 /* some random number */
  35 #define HUGETLBFS_MAGIC 0x958458f6
  36
  37 static const struct super_operations hugetlbfs_ops;
  38 static const struct address_space_operations hugetlbfs_aops;
  39 const struct file_operations hugetlbfs_file_operations;
  40 static const struct inode_operations hugetlbfs_dir_inode_operations;
  41 static const struct inode_operations hugetlbfs_inode_operations;
  42
  43 static struct backing_dev_info hugetlbfs_backing_dev_info = {
  44         .ra_pages       = 0,    /* No readahead */
  45         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  46 };
  47
  48 int sysctl_hugetlb_shm_group;
  49
  50 static void huge_pagevec_release(struct pagevec *pvec)
  51 {
  52         int i;
  53
  54         for (i = 0; i < pagevec_count(pvec); ++i)
  55                 put_page(pvec->pages[i]);
  56
  57         pagevec_reinit(pvec);
  58 }
  59
  60 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
  61 {
  62         struct inode *inode = file->f_path.dentry->d_inode;
  63         loff_t len, vma_len;
  64         int ret;
  65
  66         /*
  67          * vma alignment has already been checked by prepare_hugepage_range.
  68          * If you add any error returns here, do so after setting VM_HUGETLB,
  69          * so is_vm_hugetlb_page tests below unmap_region go the right way
  70          * when do_mmap_pgoff unwinds (may be important on powerpc and ia64).
  71          */
  72         vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
  73         vma->vm_ops = &hugetlb_vm_ops;
  74
  75         vma_len = (loff_t)(vma->vm_end - vma->vm_start);
  76
  77         mutex_lock(&inode->i_mutex);
  78         file_accessed(file);
  79
  80         ret = -ENOMEM;
  81         len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
  82
  83         if (vma->vm_flags & VM_MAYSHARE &&
  84             hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
  85                                   len >> HPAGE_SHIFT))
  86                 goto out;
  87
  88         ret = 0;
  89         hugetlb_prefault_arch_hook(vma->vm_mm);
  90         if (vma->vm_flags & VM_WRITE && inode->i_size < len)
  91                 inode->i_size = len;
  92 out:
  93         mutex_unlock(&inode->i_mutex);
  94
  95         return ret;
  96 }
  97
  98 /*
  99  * Called under down_write(mmap_sem).
 100  */
 101
 102 #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 103 static unsigned long
 104 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 105                 unsigned long len, unsigned long pgoff, unsigned long flags)
 106 {
 107         struct mm_struct *mm = current->mm;
 108         struct vm_area_struct *vma;
 109         unsigned long start_addr;
 110
 111         if (len & ~HPAGE_MASK)
 112                 return -EINVAL;
 113         if (len > TASK_SIZE)
 114                 return -ENOMEM;
 115
 116         if (flags & MAP_FIXED) {
 117                 if (prepare_hugepage_range(addr, len, pgoff))
 118                         return -EINVAL;
 119                 return addr;
 120         }
 121
 122         if (addr) {
 123                 addr = ALIGN(addr, HPAGE_SIZE);
 124                 vma = find_vma(mm, addr);
 125                 if (TASK_SIZE - len >= addr &&
 126                     (!vma || addr + len <= vma->vm_start))
 127                         return addr;
 128         }
 129
 130         start_addr = mm->free_area_cache;
 131
 132         if (len <= mm->cached_hole_size)
 133                 start_addr = TASK_UNMAPPED_BASE;
 134
 135 full_search:
 136         addr = ALIGN(start_addr, HPAGE_SIZE);
 137
 138         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 139                 /* At this point:  (!vma || addr < vma->vm_end). */
 140                 if (TASK_SIZE - len < addr) {
 141                         /*
 142                          * Start a new search - just in case we missed
 143                          * some holes.
 144                          */
 145                         if (start_addr != TASK_UNMAPPED_BASE) {
 146                                 start_addr = TASK_UNMAPPED_BASE;
 147                                 goto full_search;
 148                         }
 149                         return -ENOMEM;
 150                 }
 151
 152                 if (!vma || addr + len <= vma->vm_start)
 153                         return addr;
 154                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 155         }
 156 }
 157 #endif
 158
 159 /*
 160  * Read a page. Again trivial. If it didn't already exist
 161  * in the page cache, it is zero-filled.
 162  */
 163 static int hugetlbfs_readpage(struct file *file, struct page * page)
 164 {
 165         unlock_page(page);
 166         return -EINVAL;
 167 }
 168
 169 static int hugetlbfs_prepare_write(struct file *file,
 170                         struct page *page, unsigned offset, unsigned to)
 171 {
 172         return -EINVAL;
 173 }
 174
 175 static int hugetlbfs_commit_write(struct file *file,
 176                         struct page *page, unsigned offset, unsigned to)
 177 {
 178         return -EINVAL;
 179 }
 180
 181 static void truncate_huge_page(struct page *page)
 182 {
 183         cancel_dirty_page(page, /* No IO accounting for huge pages? */0);
 184         ClearPageUptodate(page);
 185         remove_from_page_cache(page);
 186         put_page(page);
 187 }
 188
 189 static void truncate_hugepages(struct inode *inode, loff_t lstart)
 190 {
 191         struct address_space *mapping = &inode->i_data;
 192         const pgoff_t start = lstart >> HPAGE_SHIFT;
 193         struct pagevec pvec;
 194         pgoff_t next;
 195         int i, freed = 0;
 196
 197         pagevec_init(&pvec, 0);
 198         next = start;
 199         while (1) {
 200                 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
 201                         if (next == start)
 202                                 break;
 203                         next = start;
 204                         continue;
 205                 }
 206
 207                 for (i = 0; i < pagevec_count(&pvec); ++i) {
 208                         struct page *page = pvec.pages[i];
 209
 210                         lock_page(page);
 211                         if (page->index > next)
 212                                 next = page->index;
 213                         ++next;
 214                         truncate_huge_page(page);
 215                         unlock_page(page);
 216                         hugetlb_put_quota(mapping);
 217                         freed++;
 218                 }
 219                 huge_pagevec_release(&pvec);
 220         }
 221         BUG_ON(!lstart && mapping->nrpages);
 222         hugetlb_unreserve_pages(inode, start, freed);
 223 }
 224
 225 static void hugetlbfs_delete_inode(struct inode *inode)
 226 {
 227         truncate_hugepages(inode, 0);
 228         clear_inode(inode);
 229 }
 230
 231 static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
 232 {
 233         struct super_block *sb = inode->i_sb;
 234
 235         if (!hlist_unhashed(&inode->i_hash)) {
 236                 if (!(inode->i_state & (I_DIRTY|I_LOCK)))
 237                         list_move(&inode->i_list, &inode_unused);
 238                 inodes_stat.nr_unused++;
 239                 if (!sb || (sb->s_flags & MS_ACTIVE)) {
 240                         spin_unlock(&inode_lock);
 241                         return;
 242                 }
 243                 inode->i_state |= I_WILL_FREE;
 244                 spin_unlock(&inode_lock);
 245                 /*
 246                  * write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
 247                  * in our backing_dev_info.
 248                  */
 249                 write_inode_now(inode, 1);
 250                 spin_lock(&inode_lock);
 251                 inode->i_state &= ~I_WILL_FREE;
 252                 inodes_stat.nr_unused--;
 253                 hlist_del_init(&inode->i_hash);
 254         }
 255         list_del_init(&inode->i_list);
 256         list_del_init(&inode->i_sb_list);
 257         inode->i_state |= I_FREEING;
 258         inodes_stat.nr_inodes--;
 259         spin_unlock(&inode_lock);
 260         truncate_hugepages(inode, 0);
 261         clear_inode(inode);
 262         destroy_inode(inode);
 263 }
 264
 265 static void hugetlbfs_drop_inode(struct inode *inode)
 266 {
 267         if (!inode->i_nlink)
 268                 generic_delete_inode(inode);
 269         else
 270                 hugetlbfs_forget_inode(inode);
 271 }
 272
 273 static inline void
 274 hugetlb_vmtruncate_list(struct prio_tree_root *root, pgoff_t pgoff)
 275 {
 276         struct vm_area_struct *vma;
 277         struct prio_tree_iter iter;
 278
 279         vma_prio_tree_foreach(vma, &iter, root, pgoff, ULONG_MAX) {
 280                 unsigned long v_offset;
 281
 282                 /*
 283                  * Can the expression below overflow on 32-bit arches?
 284                  * No, because the prio_tree returns us only those vmas
 285                  * which overlap the truncated area starting at pgoff,
 286                  * and no vma on a 32-bit arch can span beyond the 4GB.
 287                  */
 288                 if (vma->vm_pgoff < pgoff)
 289                         v_offset = (pgoff - vma->vm_pgoff) << PAGE_SHIFT;
 290                 else
 291                         v_offset = 0;
 292
 293                 __unmap_hugepage_range(vma,
 294                                 vma->vm_start + v_offset, vma->vm_end);
 295         }
 296 }
 297
 298 /*
 299  * Expanding truncates are not allowed.
 300  */
 301 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 302 {
 303         pgoff_t pgoff;
 304         struct address_space *mapping = inode->i_mapping;
 305
 306         if (offset > inode->i_size)
 307                 return -EINVAL;
 308
 309         BUG_ON(offset & ~HPAGE_MASK);
 310         pgoff = offset >> PAGE_SHIFT;
 311
 312         inode->i_size = offset;
 313         spin_lock(&mapping->i_mmap_lock);
 314         if (!prio_tree_empty(&mapping->i_mmap))
 315                 hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
 316         spin_unlock(&mapping->i_mmap_lock);
 317         truncate_hugepages(inode, offset);
 318         return 0;
 319 }
 320
 321 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
 322 {
 323         struct inode *inode = dentry->d_inode;
 324         int error;
 325         unsigned int ia_valid = attr->ia_valid;
 326
 327         BUG_ON(!inode);
 328
 329         error = inode_change_ok(inode, attr);
 330         if (error)
 331                 goto out;
 332
 333         if (ia_valid & ATTR_SIZE) {
 334                 error = -EINVAL;
 335                 if (!(attr->ia_size & ~HPAGE_MASK))
 336                         error = hugetlb_vmtruncate(inode, attr->ia_size);
 337                 if (error)
 338                         goto out;
 339                 attr->ia_valid &= ~ATTR_SIZE;
 340         }
 341         error = inode_setattr(inode, attr);
 342 out:
 343         return error;
 344 }
 345
 346 static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid,
 347                                         gid_t gid, int mode, dev_t dev)
 348 {
 349         struct inode *inode;
 350
 351         inode = new_inode(sb);
 352         if (inode) {
 353                 struct hugetlbfs_inode_info *info;
 354                 inode->i_mode = mode;
 355                 inode->i_uid = uid;
 356                 inode->i_gid = gid;
 357                 inode->i_blocks = 0;
 358                 inode->i_mapping->a_ops = &hugetlbfs_aops;
 359                 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
 360                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 361                 INIT_LIST_HEAD(&inode->i_mapping->private_list);
 362                 info = HUGETLBFS_I(inode);
 363                 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, NULL);
 364                 switch (mode & S_IFMT) {
 365                 default:
 366                         init_special_inode(inode, mode, dev);
 367                         break;
 368                 case S_IFREG:
 369                         inode->i_op = &hugetlbfs_inode_operations;
 370                         inode->i_fop = &hugetlbfs_file_operations;
 371                         break;
 372                 case S_IFDIR:
 373                         inode->i_op = &hugetlbfs_dir_inode_operations;
 374                         inode->i_fop = &simple_dir_operations;
 375
 376                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 377                         inc_nlink(inode);
 378                         break;
 379                 case S_IFLNK:
 380                         inode->i_op = &page_symlink_inode_operations;
 381                         break;
 382                 }
 383         }
 384         return inode;
 385 }
 386
 387 /*
 388  * File creation. Allocate an inode, and we're done..
 389  */
 390 static int hugetlbfs_mknod(struct inode *dir,
 391                         struct dentry *dentry, int mode, dev_t dev)
 392 {
 393         struct inode *inode;
 394         int error = -ENOSPC;
 395         gid_t gid;
 396
 397         if (dir->i_mode & S_ISGID) {
 398                 gid = dir->i_gid;
 399                 if (S_ISDIR(mode))
 400                         mode |= S_ISGID;
 401         } else {
 402                 gid = current->fsgid;
 403         }
 404         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
 405         if (inode) {
 406                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 407                 d_instantiate(dentry, inode);
 408                 dget(dentry);   /* Extra count - pin the dentry in core */
 409                 error = 0;
 410         }
 411         return error;
 412 }
 413
 414 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 415 {
 416         int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
 417         if (!retval)
 418                 inc_nlink(dir);
 419         return retval;
 420 }
 421
 422 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
 423 {
 424         return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
 425 }
 426
 427 static int hugetlbfs_symlink(struct inode *dir,
 428                         struct dentry *dentry, const char *symname)
 429 {
 430         struct inode *inode;
 431         int error = -ENOSPC;
 432         gid_t gid;
 433
 434         if (dir->i_mode & S_ISGID)
 435                 gid = dir->i_gid;
 436         else
 437                 gid = current->fsgid;
 438
 439         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
 440                                         gid, S_IFLNK|S_IRWXUGO, 0);
 441         if (inode) {
 442                 int l = strlen(symname)+1;
 443                 error = page_symlink(inode, symname, l);
 444                 if (!error) {
 445                         d_instantiate(dentry, inode);
 446                         dget(dentry);
 447                 } else
 448                         iput(inode);
 449         }
 450         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 451
 452         return error;
 453 }
 454
 455 /*
 456  * mark the head page dirty
 457  */
 458 static int hugetlbfs_set_page_dirty(struct page *page)
 459 {
 460         struct page *head = compound_head(page);
 461
 462         SetPageDirty(head);
 463         return 0;
 464 }
 465
 466 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 467 {
 468         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
 469
 470         buf->f_type = HUGETLBFS_MAGIC;
 471         buf->f_bsize = HPAGE_SIZE;
 472         if (sbinfo) {
 473                 spin_lock(&sbinfo->stat_lock);
 474                 /* If no limits set, just report 0 for max/free/used
 475                  * blocks, like simple_statfs() */
 476                 if (sbinfo->max_blocks >= 0) {
 477                         buf->f_blocks = sbinfo->max_blocks;
 478                         buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
 479                         buf->f_files = sbinfo->max_inodes;
 480                         buf->f_ffree = sbinfo->free_inodes;
 481                 }
 482                 spin_unlock(&sbinfo->stat_lock);
 483         }
 484         buf->f_namelen = NAME_MAX;
 485         return 0;
 486 }
 487
 488 static void hugetlbfs_put_super(struct super_block *sb)
 489 {
 490         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
 491
 492         if (sbi) {
 493                 sb->s_fs_info = NULL;
 494                 kfree(sbi);
 495         }
 496 }
 497
 498 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
 499 {
 500         if (sbinfo->free_inodes >= 0) {
 501                 spin_lock(&sbinfo->stat_lock);
 502                 if (unlikely(!sbinfo->free_inodes)) {
 503                         spin_unlock(&sbinfo->stat_lock);
 504                         return 0;
 505                 }
 506                 sbinfo->free_inodes--;
 507                 spin_unlock(&sbinfo->stat_lock);
 508         }
 509
 510         return 1;
 511 }
 512
 513 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
 514 {
 515         if (sbinfo->free_inodes >= 0) {
 516                 spin_lock(&sbinfo->stat_lock);
 517                 sbinfo->free_inodes++;
 518                 spin_unlock(&sbinfo->stat_lock);
 519         }
 520 }
 521
 522
 523 static struct kmem_cache *hugetlbfs_inode_cachep;
 524
 525 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
 526 {
 527         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
 528         struct hugetlbfs_inode_info *p;
 529
 530         if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
 531                 return NULL;
 532         p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);
 533         if (unlikely(!p)) {
 534                 hugetlbfs_inc_free_inodes(sbinfo);
 535                 return NULL;
 536         }
 537         return &p->vfs_inode;
 538 }
 539
 540 static void hugetlbfs_destroy_inode(struct inode *inode)
 541 {
 542         hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
 543         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
 544         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
 545 }
 546
 547 static const struct address_space_operations hugetlbfs_aops = {
 548         .readpage       = hugetlbfs_readpage,
 549         .prepare_write  = hugetlbfs_prepare_write,
 550         .commit_write   = hugetlbfs_commit_write,
 551         .set_page_dirty = hugetlbfs_set_page_dirty,
 552 };
 553
 554
 555 static void init_once(void *foo, struct kmem_cache *cachep, unsigned long flags)
 556 {
 557         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
 558
 559         inode_init_once(&ei->vfs_inode);
 560 }
 561
 562 const struct file_operations hugetlbfs_file_operations = {
 563         .mmap                   = hugetlbfs_file_mmap,
 564         .fsync                  = simple_sync_file,
 565         .get_unmapped_area      = hugetlb_get_unmapped_area,
 566 };
 567
 568 static const struct inode_operations hugetlbfs_dir_inode_operations = {
 569         .create         = hugetlbfs_create,
 570         .lookup         = simple_lookup,
 571         .link           = simple_link,
 572         .unlink         = simple_unlink,
 573         .symlink        = hugetlbfs_symlink,
 574         .mkdir          = hugetlbfs_mkdir,
 575         .rmdir          = simple_rmdir,
 576         .mknod          = hugetlbfs_mknod,
 577         .rename         = simple_rename,
 578         .setattr        = hugetlbfs_setattr,
 579 };
 580
 581 static const struct inode_operations hugetlbfs_inode_operations = {
 582         .setattr        = hugetlbfs_setattr,
 583 };
 584
 585 static const struct super_operations hugetlbfs_ops = {
 586         .alloc_inode    = hugetlbfs_alloc_inode,
 587         .destroy_inode  = hugetlbfs_destroy_inode,
 588         .statfs         = hugetlbfs_statfs,
 589         .delete_inode   = hugetlbfs_delete_inode,
 590         .drop_inode     = hugetlbfs_drop_inode,
 591         .put_super      = hugetlbfs_put_super,
 592 };
 593
 594 static int
 595 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
 596 {
 597         char *opt, *value, *rest;
 598
 599         if (!options)
 600                 return 0;
 601         while ((opt = strsep(&options, ",")) != NULL) {
 602                 if (!*opt)
 603                         continue;
 604
 605                 value = strchr(opt, '=');
 606                 if (!value || !*value)
 607                         return -EINVAL;
 608                 else
 609                         *value++ = '\0';
 610
 611                 if (!strcmp(opt, "uid"))
 612                         pconfig->uid = simple_strtoul(value, &value, 0);
 613                 else if (!strcmp(opt, "gid"))
 614                         pconfig->gid = simple_strtoul(value, &value, 0);
 615                 else if (!strcmp(opt, "mode"))
 616                         pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
 617                 else if (!strcmp(opt, "size")) {
 618                         unsigned long long size = memparse(value, &rest);
 619                         if (*rest == '%') {
 620                                 size <<= HPAGE_SHIFT;
 621                                 size *= max_huge_pages;
 622                                 do_div(size, 100);
 623                                 rest++;
 624                         }
 625                         pconfig->nr_blocks = (size >> HPAGE_SHIFT);
 626                         value = rest;
 627                 } else if (!strcmp(opt,"nr_inodes")) {
 628                         pconfig->nr_inodes = memparse(value, &rest);
 629                         value = rest;
 630                 } else
 631                         return -EINVAL;
 632
 633                 if (*value)
 634                         return -EINVAL;
 635         }
 636         return 0;
 637 }
 638
 639 static int
 640 hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
 641 {
 642         struct inode * inode;
 643         struct dentry * root;
 644         int ret;
 645         struct hugetlbfs_config config;
 646         struct hugetlbfs_sb_info *sbinfo;
 647
 648         config.nr_blocks = -1; /* No limit on size by default */
 649         config.nr_inodes = -1; /* No limit on number of inodes by default */
 650         config.uid = current->fsuid;
 651         config.gid = current->fsgid;
 652         config.mode = 0755;
 653         ret = hugetlbfs_parse_options(data, &config);
 654
 655         if (ret)
 656                 return ret;
 657
 658         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
 659         if (!sbinfo)
 660                 return -ENOMEM;
 661         sb->s_fs_info = sbinfo;
 662         spin_lock_init(&sbinfo->stat_lock);
 663         sbinfo->max_blocks = config.nr_blocks;
 664         sbinfo->free_blocks = config.nr_blocks;
 665         sbinfo->max_inodes = config.nr_inodes;
 666         sbinfo->free_inodes = config.nr_inodes;
 667         sb->s_maxbytes = MAX_LFS_FILESIZE;
 668         sb->s_blocksize = HPAGE_SIZE;
 669         sb->s_blocksize_bits = HPAGE_SHIFT;
 670         sb->s_magic = HUGETLBFS_MAGIC;
 671         sb->s_op = &hugetlbfs_ops;
 672         sb->s_time_gran = 1;
 673         inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
 674                                         S_IFDIR | config.mode, 0);
 675         if (!inode)
 676                 goto out_free;
 677
 678         root = d_alloc_root(inode);
 679         if (!root) {
 680                 iput(inode);
 681                 goto out_free;
 682         }
 683         sb->s_root = root;
 684         return 0;
 685 out_free:
 686         kfree(sbinfo);
 687         return -ENOMEM;
 688 }
 689
 690 int hugetlb_get_quota(struct address_space *mapping)
 691 {
 692         int ret = 0;
 693         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
 694
 695         if (sbinfo->free_blocks > -1) {
 696                 spin_lock(&sbinfo->stat_lock);
 697                 if (sbinfo->free_blocks > 0)
 698                         sbinfo->free_blocks--;
 699                 else
 700                         ret = -ENOMEM;
 701                 spin_unlock(&sbinfo->stat_lock);
 702         }
 703
 704         return ret;
 705 }
 706
 707 void hugetlb_put_quota(struct address_space *mapping)
 708 {
 709         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
 710
 711         if (sbinfo->free_blocks > -1) {
 712                 spin_lock(&sbinfo->stat_lock);
 713                 sbinfo->free_blocks++;
 714                 spin_unlock(&sbinfo->stat_lock);
 715         }
 716 }
 717
 718 static int hugetlbfs_get_sb(struct file_system_type *fs_type,
 719         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 720 {
 721         return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super, mnt);
 722 }
 723
 724 static struct file_system_type hugetlbfs_fs_type = {
 725         .name           = "hugetlbfs",
 726         .get_sb         = hugetlbfs_get_sb,
 727         .kill_sb        = kill_litter_super,
 728 };
 729
 730 static struct vfsmount *hugetlbfs_vfsmount;
 731
 732 static int can_do_hugetlb_shm(void)
 733 {
 734         return likely(capable(CAP_IPC_LOCK) ||
 735                         in_group_p(sysctl_hugetlb_shm_group) ||
 736                         can_do_mlock());
 737 }
 738
 739 struct file *hugetlb_zero_setup(size_t size)
 740 {
 741         int error = -ENOMEM;
 742         struct file *file;
 743         struct inode *inode;
 744         struct dentry *dentry, *root;
 745         struct qstr quick_string;
 746         char buf[16];
 747         static atomic_t counter;
 748
 749         if (!hugetlbfs_vfsmount)
 750                 return ERR_PTR(-ENOENT);
 751
 752         if (!can_do_hugetlb_shm())
 753                 return ERR_PTR(-EPERM);
 754
 755         if (!user_shm_lock(size, current->user))
 756                 return ERR_PTR(-ENOMEM);
 757
 758         root = hugetlbfs_vfsmount->mnt_root;
 759         snprintf(buf, 16, "%u", atomic_inc_return(&counter));
 760         quick_string.name = buf;
 761         quick_string.len = strlen(quick_string.name);
 762         quick_string.hash = 0;
 763         dentry = d_alloc(root, &quick_string);
 764         if (!dentry)
 765                 goto out_shm_unlock;
 766
 767         error = -ENFILE;
 768         file = get_empty_filp();
 769         if (!file)
 770                 goto out_dentry;
 771
 772         error = -ENOSPC;
 773         inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
 774                                 current->fsgid, S_IFREG | S_IRWXUGO, 0);
 775         if (!inode)
 776                 goto out_file;
 777
 778         error = -ENOMEM;
 779         if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
 780                 goto out_inode;
 781
 782         d_instantiate(dentry, inode);
 783         inode->i_size = size;
 784         inode->i_nlink = 0;
 785         file->f_path.mnt = mntget(hugetlbfs_vfsmount);
 786         file->f_path.dentry = dentry;
 787         file->f_mapping = inode->i_mapping;
 788         file->f_op = &hugetlbfs_file_operations;
 789         file->f_mode = FMODE_WRITE | FMODE_READ;
 790         return file;
 791
 792 out_inode:
 793         iput(inode);
 794 out_file:
 795         put_filp(file);
 796 out_dentry:
 797         dput(dentry);
 798 out_shm_unlock:
 799         user_shm_unlock(size, current->user);
 800         return ERR_PTR(error);
 801 }
 802
 803 static int __init init_hugetlbfs_fs(void)
 804 {
 805         int error;
 806         struct vfsmount *vfsmount;
 807
 808         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
 809                                         sizeof(struct hugetlbfs_inode_info),
 810                                         0, 0, init_once, NULL);
 811         if (hugetlbfs_inode_cachep == NULL)
 812                 return -ENOMEM;
 813
 814         error = register_filesystem(&hugetlbfs_fs_type);
 815         if (error)
 816                 goto out;
 817
 818         vfsmount = kern_mount(&hugetlbfs_fs_type);
 819
 820         if (!IS_ERR(vfsmount)) {
 821                 hugetlbfs_vfsmount = vfsmount;
 822                 return 0;
 823         }
 824
 825         error = PTR_ERR(vfsmount);
 826
 827  out:
 828         if (error)
 829                 kmem_cache_destroy(hugetlbfs_inode_cachep);
 830         return error;
 831 }
 832
 833 static void __exit exit_hugetlbfs_fs(void)
 834 {
 835         kmem_cache_destroy(hugetlbfs_inode_cachep);
 836         unregister_filesystem(&hugetlbfs_fs_type);
 837 }
 838
 839 module_init(init_hugetlbfs_fs)
 840 module_exit(exit_hugetlbfs_fs)
 841
 842 MODULE_LICENSE("GPL");