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