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