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/backing-dev.h>
  22 #include <linux/hugetlb.h>
  23 #include <linux/pagevec.h>
  24 #include <linux/quotaops.h>
  25 #include <linux/slab.h>
  26 #include <linux/dnotify.h>
  27 #include <linux/statfs.h>
  28 #include <linux/security.h>
  29
  30 #include <asm/uaccess.h>
  31
  32 /* some random number */
  33 #define HUGETLBFS_MAGIC 0x958458f6
  34
  35 static struct super_operations hugetlbfs_ops;
  36 static struct address_space_operations hugetlbfs_aops;
  37 struct file_operations hugetlbfs_file_operations;
  38 static struct inode_operations hugetlbfs_dir_inode_operations;
  39 static struct inode_operations hugetlbfs_inode_operations;
  40
  41 static struct backing_dev_info hugetlbfs_backing_dev_info = {
  42         .ra_pages       = 0,    /* No readahead */
  43         .capabilities   = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
  44 };
  45
  46 int sysctl_hugetlb_shm_group;
  47
  48 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
  49 {
  50         struct inode *inode = file->f_dentry->d_inode;
  51         struct address_space *mapping = inode->i_mapping;
  52         loff_t len, vma_len;
  53         int ret;
  54
  55         if ((vma->vm_flags & (VM_MAYSHARE | VM_WRITE)) == VM_WRITE)
  56                 return -EINVAL;
  57
  58         if (vma->vm_pgoff & (HPAGE_SIZE / PAGE_SIZE - 1))
  59                 return -EINVAL;
  60
  61         if (vma->vm_start & ~HPAGE_MASK)
  62                 return -EINVAL;
  63
  64         if (vma->vm_end & ~HPAGE_MASK)
  65                 return -EINVAL;
  66
  67         if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
  68                 return -EINVAL;
  69
  70         vma_len = (loff_t)(vma->vm_end - vma->vm_start);
  71
  72         down(&inode->i_sem);
  73         file_accessed(file);
  74         vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
  75         vma->vm_ops = &hugetlb_vm_ops;
  76
  77         ret = -ENOMEM;
  78         len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
  79         if (!(vma->vm_flags & VM_WRITE) && len > inode->i_size)
  80                 goto out;
  81
  82         ret = hugetlb_prefault(mapping, vma);
  83         if (ret)
  84                 goto out;
  85
  86         if (inode->i_size < len)
  87                 inode->i_size = len;
  88 out:
  89         up(&inode->i_sem);
  90
  91         return ret;
  92 }
  93
  94 /*
  95  * Called under down_write(mmap_sem).
  96  */
  97
  98 #ifdef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
  99 unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 100                 unsigned long len, unsigned long pgoff, unsigned long flags);
 101 #else
 102 static unsigned long
 103 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 104                 unsigned long len, unsigned long pgoff, unsigned long flags)
 105 {
 106         struct mm_struct *mm = current->mm;
 107         struct vm_area_struct *vma;
 108         unsigned long start_addr;
 109
 110         if (len & ~HPAGE_MASK)
 111                 return -EINVAL;
 112         if (len > TASK_SIZE)
 113                 return -ENOMEM;
 114
 115         if (addr) {
 116                 addr = ALIGN(addr, HPAGE_SIZE);
 117                 vma = find_vma(mm, addr);
 118                 if (TASK_SIZE - len >= addr &&
 119                     (!vma || addr + len <= vma->vm_start))
 120                         return addr;
 121         }
 122
 123         start_addr = mm->free_area_cache;
 124
 125         if (len <= mm->cached_hole_size)
 126                 start_addr = TASK_UNMAPPED_BASE;
 127
 128 full_search:
 129         addr = ALIGN(start_addr, HPAGE_SIZE);
 130
 131         for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
 132                 /* At this point:  (!vma || addr < vma->vm_end). */
 133                 if (TASK_SIZE - len < addr) {
 134                         /*
 135                          * Start a new search - just in case we missed
 136                          * some holes.
 137                          */
 138                         if (start_addr != TASK_UNMAPPED_BASE) {
 139                                 start_addr = TASK_UNMAPPED_BASE;
 140                                 goto full_search;
 141                         }
 142                         return -ENOMEM;
 143                 }
 144
 145                 if (!vma || addr + len <= vma->vm_start)
 146                         return addr;
 147                 addr = ALIGN(vma->vm_end, HPAGE_SIZE);
 148         }
 149 }
 150 #endif
 151
 152 /*
 153  * Read a page. Again trivial. If it didn't already exist
 154  * in the page cache, it is zero-filled.
 155  */
 156 static int hugetlbfs_readpage(struct file *file, struct page * page)
 157 {
 158         unlock_page(page);
 159         return -EINVAL;
 160 }
 161
 162 static int hugetlbfs_prepare_write(struct file *file,
 163                         struct page *page, unsigned offset, unsigned to)
 164 {
 165         return -EINVAL;
 166 }
 167
 168 static int hugetlbfs_commit_write(struct file *file,
 169                         struct page *page, unsigned offset, unsigned to)
 170 {
 171         return -EINVAL;
 172 }
 173
 174 static void huge_pagevec_release(struct pagevec *pvec)
 175 {
 176         int i;
 177
 178         for (i = 0; i < pagevec_count(pvec); ++i)
 179                 put_page(pvec->pages[i]);
 180
 181         pagevec_reinit(pvec);
 182 }
 183
 184 static void truncate_huge_page(struct page *page)
 185 {
 186         clear_page_dirty(page);
 187         ClearPageUptodate(page);
 188         remove_from_page_cache(page);
 189         put_page(page);
 190 }
 191
 192 static void truncate_hugepages(struct address_space *mapping, loff_t lstart)
 193 {
 194         const pgoff_t start = lstart >> HPAGE_SHIFT;
 195         struct pagevec pvec;
 196         pgoff_t next;
 197         int i;
 198
 199         pagevec_init(&pvec, 0);
 200         next = start;
 201         while (1) {
 202                 if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
 203                         if (next == start)
 204                                 break;
 205                         next = start;
 206                         continue;
 207                 }
 208
 209                 for (i = 0; i < pagevec_count(&pvec); ++i) {
 210                         struct page *page = pvec.pages[i];
 211
 212                         lock_page(page);
 213                         if (page->index > next)
 214                                 next = page->index;
 215                         ++next;
 216                         truncate_huge_page(page);
 217                         unlock_page(page);
 218                         hugetlb_put_quota(mapping);
 219                 }
 220                 huge_pagevec_release(&pvec);
 221         }
 222         BUG_ON(!lstart && mapping->nrpages);
 223 }
 224
 225 static void hugetlbfs_delete_inode(struct inode *inode)
 226 {
 227         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(inode->i_sb);
 228
 229         hlist_del_init(&inode->i_hash);
 230         list_del_init(&inode->i_list);
 231         list_del_init(&inode->i_sb_list);
 232         inode->i_state |= I_FREEING;
 233         inodes_stat.nr_inodes--;
 234         spin_unlock(&inode_lock);
 235
 236         if (inode->i_data.nrpages)
 237                 truncate_hugepages(&inode->i_data, 0);
 238
 239         security_inode_delete(inode);
 240
 241         if (sbinfo->free_inodes >= 0) {
 242                 spin_lock(&sbinfo->stat_lock);
 243                 sbinfo->free_inodes++;
 244                 spin_unlock(&sbinfo->stat_lock);
 245         }
 246
 247         clear_inode(inode);
 248         destroy_inode(inode);
 249 }
 250
 251 static void hugetlbfs_forget_inode(struct inode *inode)
 252 {
 253         struct super_block *super_block = inode->i_sb;
 254         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(super_block);
 255
 256         if (hlist_unhashed(&inode->i_hash))
 257                 goto out_truncate;
 258
 259         if (!(inode->i_state & (I_DIRTY|I_LOCK))) {
 260                 list_del(&inode->i_list);
 261                 list_add(&inode->i_list, &inode_unused);
 262         }
 263         inodes_stat.nr_unused++;
 264         if (!super_block || (super_block->s_flags & MS_ACTIVE)) {
 265                 spin_unlock(&inode_lock);
 266                 return;
 267         }
 268
 269         /* write_inode_now() ? */
 270         inodes_stat.nr_unused--;
 271         hlist_del_init(&inode->i_hash);
 272 out_truncate:
 273         list_del_init(&inode->i_list);
 274         list_del_init(&inode->i_sb_list);
 275         inode->i_state |= I_FREEING;
 276         inodes_stat.nr_inodes--;
 277         spin_unlock(&inode_lock);
 278         if (inode->i_data.nrpages)
 279                 truncate_hugepages(&inode->i_data, 0);
 280
 281         if (sbinfo->free_inodes >= 0) {
 282                 spin_lock(&sbinfo->stat_lock);
 283                 sbinfo->free_inodes++;
 284                 spin_unlock(&sbinfo->stat_lock);
 285         }
 286
 287         clear_inode(inode);
 288         destroy_inode(inode);
 289 }
 290
 291 static void hugetlbfs_drop_inode(struct inode *inode)
 292 {
 293         if (!inode->i_nlink)
 294                 hugetlbfs_delete_inode(inode);
 295         else
 296                 hugetlbfs_forget_inode(inode);
 297 }
 298
 299 /*
 300  * h_pgoff is in HPAGE_SIZE units.
 301  * vma->vm_pgoff is in PAGE_SIZE units.
 302  */
 303 static inline void
 304 hugetlb_vmtruncate_list(struct prio_tree_root *root, unsigned long h_pgoff)
 305 {
 306         struct vm_area_struct *vma;
 307         struct prio_tree_iter iter;
 308
 309         vma_prio_tree_foreach(vma, &iter, root, h_pgoff, ULONG_MAX) {
 310                 unsigned long h_vm_pgoff;
 311                 unsigned long v_offset;
 312
 313                 h_vm_pgoff = vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT);
 314                 v_offset = (h_pgoff - h_vm_pgoff) << HPAGE_SHIFT;
 315                 /*
 316                  * Is this VMA fully outside the truncation point?
 317                  */
 318                 if (h_vm_pgoff >= h_pgoff)
 319                         v_offset = 0;
 320
 321                 unmap_hugepage_range(vma,
 322                                 vma->vm_start + v_offset, vma->vm_end);
 323         }
 324 }
 325
 326 /*
 327  * Expanding truncates are not allowed.
 328  */
 329 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
 330 {
 331         unsigned long pgoff;
 332         struct address_space *mapping = inode->i_mapping;
 333
 334         if (offset > inode->i_size)
 335                 return -EINVAL;
 336
 337         BUG_ON(offset & ~HPAGE_MASK);
 338         pgoff = offset >> HPAGE_SHIFT;
 339
 340         inode->i_size = offset;
 341         spin_lock(&mapping->i_mmap_lock);
 342         if (!prio_tree_empty(&mapping->i_mmap))
 343                 hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
 344         spin_unlock(&mapping->i_mmap_lock);
 345         truncate_hugepages(mapping, offset);
 346         return 0;
 347 }
 348
 349 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
 350 {
 351         struct inode *inode = dentry->d_inode;
 352         int error;
 353         unsigned int ia_valid = attr->ia_valid;
 354
 355         BUG_ON(!inode);
 356
 357         error = inode_change_ok(inode, attr);
 358         if (error)
 359                 goto out;
 360
 361         if (ia_valid & ATTR_SIZE) {
 362                 error = -EINVAL;
 363                 if (!(attr->ia_size & ~HPAGE_MASK))
 364                         error = hugetlb_vmtruncate(inode, attr->ia_size);
 365                 if (error)
 366                         goto out;
 367                 attr->ia_valid &= ~ATTR_SIZE;
 368         }
 369         error = inode_setattr(inode, attr);
 370 out:
 371         return error;
 372 }
 373
 374 static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid,
 375                                         gid_t gid, int mode, dev_t dev)
 376 {
 377         struct inode *inode;
 378         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
 379
 380         if (sbinfo->free_inodes >= 0) {
 381                 spin_lock(&sbinfo->stat_lock);
 382                 if (!sbinfo->free_inodes) {
 383                         spin_unlock(&sbinfo->stat_lock);
 384                         return NULL;
 385                 }
 386                 sbinfo->free_inodes--;
 387                 spin_unlock(&sbinfo->stat_lock);
 388         }
 389
 390         inode = new_inode(sb);
 391         if (inode) {
 392                 struct hugetlbfs_inode_info *info;
 393                 inode->i_mode = mode;
 394                 inode->i_uid = uid;
 395                 inode->i_gid = gid;
 396                 inode->i_blksize = HPAGE_SIZE;
 397                 inode->i_blocks = 0;
 398                 inode->i_mapping->a_ops = &hugetlbfs_aops;
 399                 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
 400                 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
 401                 info = HUGETLBFS_I(inode);
 402                 mpol_shared_policy_init(&info->policy);
 403                 switch (mode & S_IFMT) {
 404                 default:
 405                         init_special_inode(inode, mode, dev);
 406                         break;
 407                 case S_IFREG:
 408                         inode->i_op = &hugetlbfs_inode_operations;
 409                         inode->i_fop = &hugetlbfs_file_operations;
 410                         break;
 411                 case S_IFDIR:
 412                         inode->i_op = &hugetlbfs_dir_inode_operations;
 413                         inode->i_fop = &simple_dir_operations;
 414
 415                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
 416                         inode->i_nlink++;
 417                         break;
 418                 case S_IFLNK:
 419                         inode->i_op = &page_symlink_inode_operations;
 420                         break;
 421                 }
 422         }
 423         return inode;
 424 }
 425
 426 /*
 427  * File creation. Allocate an inode, and we're done..
 428  */
 429 static int hugetlbfs_mknod(struct inode *dir,
 430                         struct dentry *dentry, int mode, dev_t dev)
 431 {
 432         struct inode *inode;
 433         int error = -ENOSPC;
 434         gid_t gid;
 435
 436         if (dir->i_mode & S_ISGID) {
 437                 gid = dir->i_gid;
 438                 if (S_ISDIR(mode))
 439                         mode |= S_ISGID;
 440         } else {
 441                 gid = current->fsgid;
 442         }
 443         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
 444         if (inode) {
 445                 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 446                 d_instantiate(dentry, inode);
 447                 dget(dentry);   /* Extra count - pin the dentry in core */
 448                 error = 0;
 449         }
 450         return error;
 451 }
 452
 453 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 454 {
 455         int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
 456         if (!retval)
 457                 dir->i_nlink++;
 458         return retval;
 459 }
 460
 461 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
 462 {
 463         return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
 464 }
 465
 466 static int hugetlbfs_symlink(struct inode *dir,
 467                         struct dentry *dentry, const char *symname)
 468 {
 469         struct inode *inode;
 470         int error = -ENOSPC;
 471         gid_t gid;
 472
 473         if (dir->i_mode & S_ISGID)
 474                 gid = dir->i_gid;
 475         else
 476                 gid = current->fsgid;
 477
 478         inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
 479                                         gid, S_IFLNK|S_IRWXUGO, 0);
 480         if (inode) {
 481                 int l = strlen(symname)+1;
 482                 error = page_symlink(inode, symname, l);
 483                 if (!error) {
 484                         d_instantiate(dentry, inode);
 485                         dget(dentry);
 486                 } else
 487                         iput(inode);
 488         }
 489         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 490
 491         return error;
 492 }
 493
 494 /*
 495  * For direct-IO reads into hugetlb pages
 496  */
 497 static int hugetlbfs_set_page_dirty(struct page *page)
 498 {
 499         return 0;
 500 }
 501
 502 static int hugetlbfs_statfs(struct super_block *sb, struct kstatfs *buf)
 503 {
 504         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
 505
 506         buf->f_type = HUGETLBFS_MAGIC;
 507         buf->f_bsize = HPAGE_SIZE;
 508         if (sbinfo) {
 509                 spin_lock(&sbinfo->stat_lock);
 510                 buf->f_blocks = sbinfo->max_blocks;
 511                 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
 512                 buf->f_files = sbinfo->max_inodes;
 513                 buf->f_ffree = sbinfo->free_inodes;
 514                 spin_unlock(&sbinfo->stat_lock);
 515         }
 516         buf->f_namelen = NAME_MAX;
 517         return 0;
 518 }
 519
 520 static void hugetlbfs_put_super(struct super_block *sb)
 521 {
 522         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
 523
 524         if (sbi) {
 525                 sb->s_fs_info = NULL;
 526                 kfree(sbi);
 527         }
 528 }
 529
 530 static kmem_cache_t *hugetlbfs_inode_cachep;
 531
 532 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
 533 {
 534         struct hugetlbfs_inode_info *p;
 535
 536         p = kmem_cache_alloc(hugetlbfs_inode_cachep, SLAB_KERNEL);
 537         if (!p)
 538                 return NULL;
 539         return &p->vfs_inode;
 540 }
 541
 542 static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
 543 {
 544         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
 545
 546         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 547             SLAB_CTOR_CONSTRUCTOR)
 548                 inode_init_once(&ei->vfs_inode);
 549 }
 550
 551 static void hugetlbfs_destroy_inode(struct inode *inode)
 552 {
 553         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
 554         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
 555 }
 556
 557 static struct address_space_operations hugetlbfs_aops = {
 558         .readpage       = hugetlbfs_readpage,
 559         .prepare_write  = hugetlbfs_prepare_write,
 560         .commit_write   = hugetlbfs_commit_write,
 561         .set_page_dirty = hugetlbfs_set_page_dirty,
 562 };
 563
 564 struct file_operations hugetlbfs_file_operations = {
 565         .mmap                   = hugetlbfs_file_mmap,
 566         .fsync                  = simple_sync_file,
 567         .get_unmapped_area      = hugetlb_get_unmapped_area,
 568 };
 569
 570 static struct inode_operations hugetlbfs_dir_inode_operations = {
 571         .create         = hugetlbfs_create,
 572         .lookup         = simple_lookup,
 573         .link           = simple_link,
 574         .unlink         = simple_unlink,
 575         .symlink        = hugetlbfs_symlink,
 576         .mkdir          = hugetlbfs_mkdir,
 577         .rmdir          = simple_rmdir,
 578         .mknod          = hugetlbfs_mknod,
 579         .rename         = simple_rename,
 580         .setattr        = hugetlbfs_setattr,
 581 };
 582
 583 static struct inode_operations hugetlbfs_inode_operations = {
 584         .setattr        = hugetlbfs_setattr,
 585 };
 586
 587 static struct super_operations hugetlbfs_ops = {
 588         .alloc_inode    = hugetlbfs_alloc_inode,
 589         .destroy_inode  = hugetlbfs_destroy_inode,
 590         .statfs         = hugetlbfs_statfs,
 591         .drop_inode     = hugetlbfs_drop_inode,
 592         .put_super      = hugetlbfs_put_super,
 593 };
 594
 595 static int
 596 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
 597 {
 598         char *opt, *value, *rest;
 599
 600         if (!options)
 601                 return 0;
 602         while ((opt = strsep(&options, ",")) != NULL) {
 603                 if (!*opt)
 604                         continue;
 605
 606                 value = strchr(opt, '=');
 607                 if (!value || !*value)
 608                         return -EINVAL;
 609                 else
 610                         *value++ = '\0';
 611
 612                 if (!strcmp(opt, "uid"))
 613                         pconfig->uid = simple_strtoul(value, &value, 0);
 614                 else if (!strcmp(opt, "gid"))
 615                         pconfig->gid = simple_strtoul(value, &value, 0);
 616                 else if (!strcmp(opt, "mode"))
 617                         pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
 618                 else if (!strcmp(opt, "size")) {
 619                         unsigned long long size = memparse(value, &rest);
 620                         if (*rest == '%') {
 621                                 size <<= HPAGE_SHIFT;
 622                                 size *= max_huge_pages;
 623                                 do_div(size, 100);
 624                                 rest++;
 625                         }
 626                         size &= HPAGE_MASK;
 627                         pconfig->nr_blocks = (size >> HPAGE_SHIFT);
 628                         value = rest;
 629                 } else if (!strcmp(opt,"nr_inodes")) {
 630                         pconfig->nr_inodes = memparse(value, &rest);
 631                         value = rest;
 632                 } else
 633                         return -EINVAL;
 634
 635                 if (*value)
 636                         return -EINVAL;
 637         }
 638         return 0;
 639 }
 640
 641 static int
 642 hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
 643 {
 644         struct inode * inode;
 645         struct dentry * root;
 646         int ret;
 647         struct hugetlbfs_config config;
 648         struct hugetlbfs_sb_info *sbinfo;
 649
 650         config.nr_blocks = -1; /* No limit on size by default */
 651         config.nr_inodes = -1; /* No limit on number of inodes by default */
 652         config.uid = current->fsuid;
 653         config.gid = current->fsgid;
 654         config.mode = 0755;
 655         ret = hugetlbfs_parse_options(data, &config);
 656
 657         if (ret)
 658                 return ret;
 659
 660         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
 661         if (!sbinfo)
 662                 return -ENOMEM;
 663         sb->s_fs_info = sbinfo;
 664         spin_lock_init(&sbinfo->stat_lock);
 665         sbinfo->max_blocks = config.nr_blocks;
 666         sbinfo->free_blocks = config.nr_blocks;
 667         sbinfo->max_inodes = config.nr_inodes;
 668         sbinfo->free_inodes = config.nr_inodes;
 669         sb->s_maxbytes = MAX_LFS_FILESIZE;
 670         sb->s_blocksize = HPAGE_SIZE;
 671         sb->s_blocksize_bits = HPAGE_SHIFT;
 672         sb->s_magic = HUGETLBFS_MAGIC;
 673         sb->s_op = &hugetlbfs_ops;
 674         sb->s_time_gran = 1;
 675         inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
 676                                         S_IFDIR | config.mode, 0);
 677         if (!inode)
 678                 goto out_free;
 679
 680         root = d_alloc_root(inode);
 681         if (!root) {
 682                 iput(inode);
 683                 goto out_free;
 684         }
 685         sb->s_root = root;
 686         return 0;
 687 out_free:
 688         kfree(sbinfo);
 689         return -ENOMEM;
 690 }
 691
 692 int hugetlb_get_quota(struct address_space *mapping)
 693 {
 694         int ret = 0;
 695         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
 696
 697         if (sbinfo->free_blocks > -1) {
 698                 spin_lock(&sbinfo->stat_lock);
 699                 if (sbinfo->free_blocks > 0)
 700                         sbinfo->free_blocks--;
 701                 else
 702                         ret = -ENOMEM;
 703                 spin_unlock(&sbinfo->stat_lock);
 704         }
 705
 706         return ret;
 707 }
 708
 709 void hugetlb_put_quota(struct address_space *mapping)
 710 {
 711         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
 712
 713         if (sbinfo->free_blocks > -1) {
 714                 spin_lock(&sbinfo->stat_lock);
 715                 sbinfo->free_blocks++;
 716                 spin_unlock(&sbinfo->stat_lock);
 717         }
 718 }
 719
 720 static struct super_block *hugetlbfs_get_sb(struct file_system_type *fs_type,
 721         int flags, const char *dev_name, void *data)
 722 {
 723         return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super);
 724 }
 725
 726 static struct file_system_type hugetlbfs_fs_type = {
 727         .name           = "hugetlbfs",
 728         .get_sb         = hugetlbfs_get_sb,
 729         .kill_sb        = kill_litter_super,
 730 };
 731
 732 static struct vfsmount *hugetlbfs_vfsmount;
 733
 734 /*
 735  * Return the next identifier for a shm file
 736  */
 737 static unsigned long hugetlbfs_counter(void)
 738 {
 739         static DEFINE_SPINLOCK(lock);
 740         static unsigned long counter;
 741         unsigned long ret;
 742
 743         spin_lock(&lock);
 744         ret = ++counter;
 745         spin_unlock(&lock);
 746         return ret;
 747 }
 748
 749 static int can_do_hugetlb_shm(void)
 750 {
 751         return likely(capable(CAP_IPC_LOCK) ||
 752                         in_group_p(sysctl_hugetlb_shm_group) ||
 753                         can_do_mlock());
 754 }
 755
 756 struct file *hugetlb_zero_setup(size_t size)
 757 {
 758         int error = -ENOMEM;
 759         struct file *file;
 760         struct inode *inode;
 761         struct dentry *dentry, *root;
 762         struct qstr quick_string;
 763         char buf[16];
 764
 765         if (!can_do_hugetlb_shm())
 766                 return ERR_PTR(-EPERM);
 767
 768         if (!is_hugepage_mem_enough(size))
 769                 return ERR_PTR(-ENOMEM);
 770
 771         if (!user_shm_lock(size, current->user))
 772                 return ERR_PTR(-ENOMEM);
 773
 774         root = hugetlbfs_vfsmount->mnt_root;
 775         snprintf(buf, 16, "%lu", hugetlbfs_counter());
 776         quick_string.name = buf;
 777         quick_string.len = strlen(quick_string.name);
 778         quick_string.hash = 0;
 779         dentry = d_alloc(root, &quick_string);
 780         if (!dentry)
 781                 goto out_shm_unlock;
 782
 783         error = -ENFILE;
 784         file = get_empty_filp();
 785         if (!file)
 786                 goto out_dentry;
 787
 788         error = -ENOSPC;
 789         inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
 790                                 current->fsgid, S_IFREG | S_IRWXUGO, 0);
 791         if (!inode)
 792                 goto out_file;
 793
 794         d_instantiate(dentry, inode);
 795         inode->i_size = size;
 796         inode->i_nlink = 0;
 797         file->f_vfsmnt = mntget(hugetlbfs_vfsmount);
 798         file->f_dentry = dentry;
 799         file->f_mapping = inode->i_mapping;
 800         file->f_op = &hugetlbfs_file_operations;
 801         file->f_mode = FMODE_WRITE | FMODE_READ;
 802         return file;
 803
 804 out_file:
 805         put_filp(file);
 806 out_dentry:
 807         dput(dentry);
 808 out_shm_unlock:
 809         user_shm_unlock(size, current->user);
 810         return ERR_PTR(error);
 811 }
 812
 813 static int __init init_hugetlbfs_fs(void)
 814 {
 815         int error;
 816         struct vfsmount *vfsmount;
 817
 818         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
 819                                         sizeof(struct hugetlbfs_inode_info),
 820                                         0, 0, init_once, NULL);
 821         if (hugetlbfs_inode_cachep == NULL)
 822                 return -ENOMEM;
 823
 824         error = register_filesystem(&hugetlbfs_fs_type);
 825         if (error)
 826                 goto out;
 827
 828         vfsmount = kern_mount(&hugetlbfs_fs_type);
 829
 830         if (!IS_ERR(vfsmount)) {
 831                 hugetlbfs_vfsmount = vfsmount;
 832                 return 0;
 833         }
 834
 835         error = PTR_ERR(vfsmount);
 836
 837  out:
 838         if (error)
 839                 kmem_cache_destroy(hugetlbfs_inode_cachep);
 840         return error;
 841 }
 842
 843 static void __exit exit_hugetlbfs_fs(void)
 844 {
 845         kmem_cache_destroy(hugetlbfs_inode_cachep);
 846         unregister_filesystem(&hugetlbfs_fs_type);
 847 }
 848
 849 module_init(init_hugetlbfs_fs)
 850 module_exit(exit_hugetlbfs_fs)
 851
 852 MODULE_LICENSE("GPL");