blob: 3a9b6d179cbdf492da7924012fd85aa8241a64f1 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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
35static struct super_operations hugetlbfs_ops;
36static struct address_space_operations hugetlbfs_aops;
37struct file_operations hugetlbfs_file_operations;
38static struct inode_operations hugetlbfs_dir_inode_operations;
39static struct inode_operations hugetlbfs_inode_operations;
40
41static 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
46int sysctl_hugetlb_shm_group;
47
48static 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;
88out:
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
99unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
100 unsigned long len, unsigned long pgoff, unsigned long flags);
101#else
102static unsigned long
103hugetlb_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
Wolfgang Wander1363c3c2005-06-21 17:14:49 -0700125 if (len <= mm->cached_hole_size)
126 start_addr = TASK_UNMAPPED_BASE;
127
Linus Torvalds1da177e2005-04-16 15:20:36 -0700128full_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 */
156static int hugetlbfs_readpage(struct file *file, struct page * page)
157{
158 unlock_page(page);
159 return -EINVAL;
160}
161
162static int hugetlbfs_prepare_write(struct file *file,
163 struct page *page, unsigned offset, unsigned to)
164{
165 return -EINVAL;
166}
167
168static int hugetlbfs_commit_write(struct file *file,
169 struct page *page, unsigned offset, unsigned to)
170{
171 return -EINVAL;
172}
173
174static 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
184static 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
192static 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
225static 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
251static 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);
272out_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
291static 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 */
303static inline void
304hugetlb_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_length;
312 unsigned long v_offset;
313
314 h_vm_pgoff = vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT);
315 v_offset = (h_pgoff - h_vm_pgoff) << HPAGE_SHIFT;
316 /*
317 * Is this VMA fully outside the truncation point?
318 */
319 if (h_vm_pgoff >= h_pgoff)
320 v_offset = 0;
321
322 v_length = vma->vm_end - vma->vm_start;
323
324 zap_hugepage_range(vma,
325 vma->vm_start + v_offset,
326 v_length - v_offset);
327 }
328}
329
330/*
331 * Expanding truncates are not allowed.
332 */
333static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
334{
335 unsigned long pgoff;
336 struct address_space *mapping = inode->i_mapping;
337
338 if (offset > inode->i_size)
339 return -EINVAL;
340
341 BUG_ON(offset & ~HPAGE_MASK);
342 pgoff = offset >> HPAGE_SHIFT;
343
344 inode->i_size = offset;
345 spin_lock(&mapping->i_mmap_lock);
346 if (!prio_tree_empty(&mapping->i_mmap))
347 hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
348 spin_unlock(&mapping->i_mmap_lock);
349 truncate_hugepages(mapping, offset);
350 return 0;
351}
352
353static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
354{
355 struct inode *inode = dentry->d_inode;
356 int error;
357 unsigned int ia_valid = attr->ia_valid;
358
359 BUG_ON(!inode);
360
361 error = inode_change_ok(inode, attr);
362 if (error)
363 goto out;
364
365 if (ia_valid & ATTR_SIZE) {
366 error = -EINVAL;
367 if (!(attr->ia_size & ~HPAGE_MASK))
368 error = hugetlb_vmtruncate(inode, attr->ia_size);
369 if (error)
370 goto out;
371 attr->ia_valid &= ~ATTR_SIZE;
372 }
373 error = inode_setattr(inode, attr);
374out:
375 return error;
376}
377
378static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid,
379 gid_t gid, int mode, dev_t dev)
380{
381 struct inode *inode;
382 struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
383
384 if (sbinfo->free_inodes >= 0) {
385 spin_lock(&sbinfo->stat_lock);
386 if (!sbinfo->free_inodes) {
387 spin_unlock(&sbinfo->stat_lock);
388 return NULL;
389 }
390 sbinfo->free_inodes--;
391 spin_unlock(&sbinfo->stat_lock);
392 }
393
394 inode = new_inode(sb);
395 if (inode) {
396 struct hugetlbfs_inode_info *info;
397 inode->i_mode = mode;
398 inode->i_uid = uid;
399 inode->i_gid = gid;
400 inode->i_blksize = HPAGE_SIZE;
401 inode->i_blocks = 0;
402 inode->i_mapping->a_ops = &hugetlbfs_aops;
403 inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
404 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
405 info = HUGETLBFS_I(inode);
406 mpol_shared_policy_init(&info->policy);
407 switch (mode & S_IFMT) {
408 default:
409 init_special_inode(inode, mode, dev);
410 break;
411 case S_IFREG:
412 inode->i_op = &hugetlbfs_inode_operations;
413 inode->i_fop = &hugetlbfs_file_operations;
414 break;
415 case S_IFDIR:
416 inode->i_op = &hugetlbfs_dir_inode_operations;
417 inode->i_fop = &simple_dir_operations;
418
419 /* directory inodes start off with i_nlink == 2 (for "." entry) */
420 inode->i_nlink++;
421 break;
422 case S_IFLNK:
423 inode->i_op = &page_symlink_inode_operations;
424 break;
425 }
426 }
427 return inode;
428}
429
430/*
431 * File creation. Allocate an inode, and we're done..
432 */
433static int hugetlbfs_mknod(struct inode *dir,
434 struct dentry *dentry, int mode, dev_t dev)
435{
436 struct inode *inode;
437 int error = -ENOSPC;
438 gid_t gid;
439
440 if (dir->i_mode & S_ISGID) {
441 gid = dir->i_gid;
442 if (S_ISDIR(mode))
443 mode |= S_ISGID;
444 } else {
445 gid = current->fsgid;
446 }
447 inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
448 if (inode) {
449 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
450 d_instantiate(dentry, inode);
451 dget(dentry); /* Extra count - pin the dentry in core */
452 error = 0;
453 }
454 return error;
455}
456
457static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
458{
459 int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
460 if (!retval)
461 dir->i_nlink++;
462 return retval;
463}
464
465static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
466{
467 return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
468}
469
470static int hugetlbfs_symlink(struct inode *dir,
471 struct dentry *dentry, const char *symname)
472{
473 struct inode *inode;
474 int error = -ENOSPC;
475 gid_t gid;
476
477 if (dir->i_mode & S_ISGID)
478 gid = dir->i_gid;
479 else
480 gid = current->fsgid;
481
482 inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
483 gid, S_IFLNK|S_IRWXUGO, 0);
484 if (inode) {
485 int l = strlen(symname)+1;
486 error = page_symlink(inode, symname, l);
487 if (!error) {
488 d_instantiate(dentry, inode);
489 dget(dentry);
490 } else
491 iput(inode);
492 }
493 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
494
495 return error;
496}
497
498/*
499 * For direct-IO reads into hugetlb pages
500 */
501static int hugetlbfs_set_page_dirty(struct page *page)
502{
503 return 0;
504}
505
506static int hugetlbfs_statfs(struct super_block *sb, struct kstatfs *buf)
507{
508 struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
509
510 buf->f_type = HUGETLBFS_MAGIC;
511 buf->f_bsize = HPAGE_SIZE;
512 if (sbinfo) {
513 spin_lock(&sbinfo->stat_lock);
514 buf->f_blocks = sbinfo->max_blocks;
515 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
516 buf->f_files = sbinfo->max_inodes;
517 buf->f_ffree = sbinfo->free_inodes;
518 spin_unlock(&sbinfo->stat_lock);
519 }
520 buf->f_namelen = NAME_MAX;
521 return 0;
522}
523
524static void hugetlbfs_put_super(struct super_block *sb)
525{
526 struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
527
528 if (sbi) {
529 sb->s_fs_info = NULL;
530 kfree(sbi);
531 }
532}
533
534static kmem_cache_t *hugetlbfs_inode_cachep;
535
536static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
537{
538 struct hugetlbfs_inode_info *p;
539
540 p = kmem_cache_alloc(hugetlbfs_inode_cachep, SLAB_KERNEL);
541 if (!p)
542 return NULL;
543 return &p->vfs_inode;
544}
545
546static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
547{
548 struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
549
550 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
551 SLAB_CTOR_CONSTRUCTOR)
552 inode_init_once(&ei->vfs_inode);
553}
554
555static void hugetlbfs_destroy_inode(struct inode *inode)
556{
557 mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
558 kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
559}
560
561static struct address_space_operations hugetlbfs_aops = {
562 .readpage = hugetlbfs_readpage,
563 .prepare_write = hugetlbfs_prepare_write,
564 .commit_write = hugetlbfs_commit_write,
565 .set_page_dirty = hugetlbfs_set_page_dirty,
566};
567
568struct file_operations hugetlbfs_file_operations = {
569 .mmap = hugetlbfs_file_mmap,
570 .fsync = simple_sync_file,
571 .get_unmapped_area = hugetlb_get_unmapped_area,
572};
573
574static struct inode_operations hugetlbfs_dir_inode_operations = {
575 .create = hugetlbfs_create,
576 .lookup = simple_lookup,
577 .link = simple_link,
578 .unlink = simple_unlink,
579 .symlink = hugetlbfs_symlink,
580 .mkdir = hugetlbfs_mkdir,
581 .rmdir = simple_rmdir,
582 .mknod = hugetlbfs_mknod,
583 .rename = simple_rename,
584 .setattr = hugetlbfs_setattr,
585};
586
587static struct inode_operations hugetlbfs_inode_operations = {
588 .setattr = hugetlbfs_setattr,
589};
590
591static struct super_operations hugetlbfs_ops = {
592 .alloc_inode = hugetlbfs_alloc_inode,
593 .destroy_inode = hugetlbfs_destroy_inode,
594 .statfs = hugetlbfs_statfs,
595 .drop_inode = hugetlbfs_drop_inode,
596 .put_super = hugetlbfs_put_super,
597};
598
599static int
600hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
601{
602 char *opt, *value, *rest;
603
604 if (!options)
605 return 0;
606 while ((opt = strsep(&options, ",")) != NULL) {
607 if (!*opt)
608 continue;
609
610 value = strchr(opt, '=');
611 if (!value || !*value)
612 return -EINVAL;
613 else
614 *value++ = '\0';
615
616 if (!strcmp(opt, "uid"))
617 pconfig->uid = simple_strtoul(value, &value, 0);
618 else if (!strcmp(opt, "gid"))
619 pconfig->gid = simple_strtoul(value, &value, 0);
620 else if (!strcmp(opt, "mode"))
621 pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
622 else if (!strcmp(opt, "size")) {
623 unsigned long long size = memparse(value, &rest);
624 if (*rest == '%') {
625 size <<= HPAGE_SHIFT;
626 size *= max_huge_pages;
627 do_div(size, 100);
628 rest++;
629 }
630 size &= HPAGE_MASK;
631 pconfig->nr_blocks = (size >> HPAGE_SHIFT);
632 value = rest;
633 } else if (!strcmp(opt,"nr_inodes")) {
634 pconfig->nr_inodes = memparse(value, &rest);
635 value = rest;
636 } else
637 return -EINVAL;
638
639 if (*value)
640 return -EINVAL;
641 }
642 return 0;
643}
644
645static int
646hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
647{
648 struct inode * inode;
649 struct dentry * root;
650 int ret;
651 struct hugetlbfs_config config;
652 struct hugetlbfs_sb_info *sbinfo;
653
654 config.nr_blocks = -1; /* No limit on size by default */
655 config.nr_inodes = -1; /* No limit on number of inodes by default */
656 config.uid = current->fsuid;
657 config.gid = current->fsgid;
658 config.mode = 0755;
659 ret = hugetlbfs_parse_options(data, &config);
660
661 if (ret)
662 return ret;
663
664 sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
665 if (!sbinfo)
666 return -ENOMEM;
667 sb->s_fs_info = sbinfo;
668 spin_lock_init(&sbinfo->stat_lock);
669 sbinfo->max_blocks = config.nr_blocks;
670 sbinfo->free_blocks = config.nr_blocks;
671 sbinfo->max_inodes = config.nr_inodes;
672 sbinfo->free_inodes = config.nr_inodes;
673 sb->s_maxbytes = MAX_LFS_FILESIZE;
674 sb->s_blocksize = HPAGE_SIZE;
675 sb->s_blocksize_bits = HPAGE_SHIFT;
676 sb->s_magic = HUGETLBFS_MAGIC;
677 sb->s_op = &hugetlbfs_ops;
678 sb->s_time_gran = 1;
679 inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
680 S_IFDIR | config.mode, 0);
681 if (!inode)
682 goto out_free;
683
684 root = d_alloc_root(inode);
685 if (!root) {
686 iput(inode);
687 goto out_free;
688 }
689 sb->s_root = root;
690 return 0;
691out_free:
692 kfree(sbinfo);
693 return -ENOMEM;
694}
695
696int hugetlb_get_quota(struct address_space *mapping)
697{
698 int ret = 0;
699 struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
700
701 if (sbinfo->free_blocks > -1) {
702 spin_lock(&sbinfo->stat_lock);
703 if (sbinfo->free_blocks > 0)
704 sbinfo->free_blocks--;
705 else
706 ret = -ENOMEM;
707 spin_unlock(&sbinfo->stat_lock);
708 }
709
710 return ret;
711}
712
713void hugetlb_put_quota(struct address_space *mapping)
714{
715 struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
716
717 if (sbinfo->free_blocks > -1) {
718 spin_lock(&sbinfo->stat_lock);
719 sbinfo->free_blocks++;
720 spin_unlock(&sbinfo->stat_lock);
721 }
722}
723
724static struct super_block *hugetlbfs_get_sb(struct file_system_type *fs_type,
725 int flags, const char *dev_name, void *data)
726{
727 return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super);
728}
729
730static struct file_system_type hugetlbfs_fs_type = {
731 .name = "hugetlbfs",
732 .get_sb = hugetlbfs_get_sb,
733 .kill_sb = kill_litter_super,
734};
735
736static struct vfsmount *hugetlbfs_vfsmount;
737
738/*
739 * Return the next identifier for a shm file
740 */
741static unsigned long hugetlbfs_counter(void)
742{
743 static DEFINE_SPINLOCK(lock);
744 static unsigned long counter;
745 unsigned long ret;
746
747 spin_lock(&lock);
748 ret = ++counter;
749 spin_unlock(&lock);
750 return ret;
751}
752
753static int can_do_hugetlb_shm(void)
754{
755 return likely(capable(CAP_IPC_LOCK) ||
756 in_group_p(sysctl_hugetlb_shm_group) ||
757 can_do_mlock());
758}
759
760struct file *hugetlb_zero_setup(size_t size)
761{
762 int error = -ENOMEM;
763 struct file *file;
764 struct inode *inode;
765 struct dentry *dentry, *root;
766 struct qstr quick_string;
767 char buf[16];
768
769 if (!can_do_hugetlb_shm())
770 return ERR_PTR(-EPERM);
771
772 if (!is_hugepage_mem_enough(size))
773 return ERR_PTR(-ENOMEM);
774
775 if (!user_shm_lock(size, current->user))
776 return ERR_PTR(-ENOMEM);
777
778 root = hugetlbfs_vfsmount->mnt_root;
779 snprintf(buf, 16, "%lu", hugetlbfs_counter());
780 quick_string.name = buf;
781 quick_string.len = strlen(quick_string.name);
782 quick_string.hash = 0;
783 dentry = d_alloc(root, &quick_string);
784 if (!dentry)
785 goto out_shm_unlock;
786
787 error = -ENFILE;
788 file = get_empty_filp();
789 if (!file)
790 goto out_dentry;
791
792 error = -ENOSPC;
793 inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
794 current->fsgid, S_IFREG | S_IRWXUGO, 0);
795 if (!inode)
796 goto out_file;
797
798 d_instantiate(dentry, inode);
799 inode->i_size = size;
800 inode->i_nlink = 0;
801 file->f_vfsmnt = mntget(hugetlbfs_vfsmount);
802 file->f_dentry = dentry;
803 file->f_mapping = inode->i_mapping;
804 file->f_op = &hugetlbfs_file_operations;
805 file->f_mode = FMODE_WRITE | FMODE_READ;
806 return file;
807
808out_file:
809 put_filp(file);
810out_dentry:
811 dput(dentry);
812out_shm_unlock:
813 user_shm_unlock(size, current->user);
814 return ERR_PTR(error);
815}
816
817static int __init init_hugetlbfs_fs(void)
818{
819 int error;
820 struct vfsmount *vfsmount;
821
822 hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
823 sizeof(struct hugetlbfs_inode_info),
824 0, 0, init_once, NULL);
825 if (hugetlbfs_inode_cachep == NULL)
826 return -ENOMEM;
827
828 error = register_filesystem(&hugetlbfs_fs_type);
829 if (error)
830 goto out;
831
832 vfsmount = kern_mount(&hugetlbfs_fs_type);
833
834 if (!IS_ERR(vfsmount)) {
835 hugetlbfs_vfsmount = vfsmount;
836 return 0;
837 }
838
839 error = PTR_ERR(vfsmount);
840
841 out:
842 if (error)
843 kmem_cache_destroy(hugetlbfs_inode_cachep);
844 return error;
845}
846
847static void __exit exit_hugetlbfs_fs(void)
848{
849 kmem_cache_destroy(hugetlbfs_inode_cachep);
850 unregister_filesystem(&hugetlbfs_fs_type);
851}
852
853module_init(init_hugetlbfs_fs)
854module_exit(exit_hugetlbfs_fs)
855
856MODULE_LICENSE("GPL");