xref: /openbmc/linux/fs/hugetlbfs/inode.c (revision 64c70b1c)
1 /*
2  * hugetlbpage-backed filesystem.  Based on ramfs.
3  *
4  * William Irwin, 2002
5  *
6  * Copyright (C) 2002 Linus Torvalds.
7  */
8 
9 #include <linux/module.h>
10 #include <linux/thread_info.h>
11 #include <asm/current.h>
12 #include <linux/sched.h>		/* remove ASAP */
13 #include <linux/fs.h>
14 #include <linux/mount.h>
15 #include <linux/file.h>
16 #include <linux/writeback.h>
17 #include <linux/pagemap.h>
18 #include <linux/highmem.h>
19 #include <linux/init.h>
20 #include <linux/string.h>
21 #include <linux/capability.h>
22 #include <linux/backing-dev.h>
23 #include <linux/hugetlb.h>
24 #include <linux/pagevec.h>
25 #include <linux/mman.h>
26 #include <linux/quotaops.h>
27 #include <linux/slab.h>
28 #include <linux/dnotify.h>
29 #include <linux/statfs.h>
30 #include <linux/security.h>
31 
32 #include <asm/uaccess.h>
33 
34 /* some random number */
35 #define HUGETLBFS_MAGIC	0x958458f6
36 
37 static const struct super_operations hugetlbfs_ops;
38 static const struct address_space_operations hugetlbfs_aops;
39 const struct file_operations hugetlbfs_file_operations;
40 static const struct inode_operations hugetlbfs_dir_inode_operations;
41 static const struct inode_operations hugetlbfs_inode_operations;
42 
43 static struct backing_dev_info hugetlbfs_backing_dev_info = {
44 	.ra_pages	= 0,	/* No readahead */
45 	.capabilities	= BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
46 };
47 
48 int sysctl_hugetlb_shm_group;
49 
50 static void huge_pagevec_release(struct pagevec *pvec)
51 {
52 	int i;
53 
54 	for (i = 0; i < pagevec_count(pvec); ++i)
55 		put_page(pvec->pages[i]);
56 
57 	pagevec_reinit(pvec);
58 }
59 
60 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
61 {
62 	struct inode *inode = file->f_path.dentry->d_inode;
63 	loff_t len, vma_len;
64 	int ret;
65 
66 	/*
67 	 * vma alignment has already been checked by prepare_hugepage_range.
68 	 * If you add any error returns here, do so after setting VM_HUGETLB,
69 	 * so is_vm_hugetlb_page tests below unmap_region go the right way
70 	 * when do_mmap_pgoff unwinds (may be important on powerpc and ia64).
71 	 */
72 	vma->vm_flags |= VM_HUGETLB | VM_RESERVED;
73 	vma->vm_ops = &hugetlb_vm_ops;
74 
75 	vma_len = (loff_t)(vma->vm_end - vma->vm_start);
76 
77 	mutex_lock(&inode->i_mutex);
78 	file_accessed(file);
79 
80 	ret = -ENOMEM;
81 	len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
82 
83 	if (vma->vm_flags & VM_MAYSHARE &&
84 	    hugetlb_reserve_pages(inode, vma->vm_pgoff >> (HPAGE_SHIFT-PAGE_SHIFT),
85 				  len >> HPAGE_SHIFT))
86 		goto out;
87 
88 	ret = 0;
89 	hugetlb_prefault_arch_hook(vma->vm_mm);
90 	if (vma->vm_flags & VM_WRITE && inode->i_size < len)
91 		inode->i_size = len;
92 out:
93 	mutex_unlock(&inode->i_mutex);
94 
95 	return ret;
96 }
97 
98 /*
99  * Called under down_write(mmap_sem).
100  */
101 
102 #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
103 static unsigned long
104 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
105 		unsigned long len, unsigned long pgoff, unsigned long flags)
106 {
107 	struct mm_struct *mm = current->mm;
108 	struct vm_area_struct *vma;
109 	unsigned long start_addr;
110 
111 	if (len & ~HPAGE_MASK)
112 		return -EINVAL;
113 	if (len > TASK_SIZE)
114 		return -ENOMEM;
115 
116 	if (flags & MAP_FIXED) {
117 		if (prepare_hugepage_range(addr, len, pgoff))
118 			return -EINVAL;
119 		return addr;
120 	}
121 
122 	if (addr) {
123 		addr = ALIGN(addr, HPAGE_SIZE);
124 		vma = find_vma(mm, addr);
125 		if (TASK_SIZE - len >= addr &&
126 		    (!vma || addr + len <= vma->vm_start))
127 			return addr;
128 	}
129 
130 	start_addr = mm->free_area_cache;
131 
132 	if (len <= mm->cached_hole_size)
133 		start_addr = TASK_UNMAPPED_BASE;
134 
135 full_search:
136 	addr = ALIGN(start_addr, HPAGE_SIZE);
137 
138 	for (vma = find_vma(mm, addr); ; vma = vma->vm_next) {
139 		/* At this point:  (!vma || addr < vma->vm_end). */
140 		if (TASK_SIZE - len < addr) {
141 			/*
142 			 * Start a new search - just in case we missed
143 			 * some holes.
144 			 */
145 			if (start_addr != TASK_UNMAPPED_BASE) {
146 				start_addr = TASK_UNMAPPED_BASE;
147 				goto full_search;
148 			}
149 			return -ENOMEM;
150 		}
151 
152 		if (!vma || addr + len <= vma->vm_start)
153 			return addr;
154 		addr = ALIGN(vma->vm_end, HPAGE_SIZE);
155 	}
156 }
157 #endif
158 
159 /*
160  * Read a page. Again trivial. If it didn't already exist
161  * in the page cache, it is zero-filled.
162  */
163 static int hugetlbfs_readpage(struct file *file, struct page * page)
164 {
165 	unlock_page(page);
166 	return -EINVAL;
167 }
168 
169 static int hugetlbfs_prepare_write(struct file *file,
170 			struct page *page, unsigned offset, unsigned to)
171 {
172 	return -EINVAL;
173 }
174 
175 static int hugetlbfs_commit_write(struct file *file,
176 			struct page *page, unsigned offset, unsigned to)
177 {
178 	return -EINVAL;
179 }
180 
181 static void truncate_huge_page(struct page *page)
182 {
183 	cancel_dirty_page(page, /* No IO accounting for huge pages? */0);
184 	ClearPageUptodate(page);
185 	remove_from_page_cache(page);
186 	put_page(page);
187 }
188 
189 static void truncate_hugepages(struct inode *inode, loff_t lstart)
190 {
191 	struct address_space *mapping = &inode->i_data;
192 	const pgoff_t start = lstart >> HPAGE_SHIFT;
193 	struct pagevec pvec;
194 	pgoff_t next;
195 	int i, freed = 0;
196 
197 	pagevec_init(&pvec, 0);
198 	next = start;
199 	while (1) {
200 		if (!pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) {
201 			if (next == start)
202 				break;
203 			next = start;
204 			continue;
205 		}
206 
207 		for (i = 0; i < pagevec_count(&pvec); ++i) {
208 			struct page *page = pvec.pages[i];
209 
210 			lock_page(page);
211 			if (page->index > next)
212 				next = page->index;
213 			++next;
214 			truncate_huge_page(page);
215 			unlock_page(page);
216 			hugetlb_put_quota(mapping);
217 			freed++;
218 		}
219 		huge_pagevec_release(&pvec);
220 	}
221 	BUG_ON(!lstart && mapping->nrpages);
222 	hugetlb_unreserve_pages(inode, start, freed);
223 }
224 
225 static void hugetlbfs_delete_inode(struct inode *inode)
226 {
227 	truncate_hugepages(inode, 0);
228 	clear_inode(inode);
229 }
230 
231 static void hugetlbfs_forget_inode(struct inode *inode) __releases(inode_lock)
232 {
233 	struct super_block *sb = inode->i_sb;
234 
235 	if (!hlist_unhashed(&inode->i_hash)) {
236 		if (!(inode->i_state & (I_DIRTY|I_LOCK)))
237 			list_move(&inode->i_list, &inode_unused);
238 		inodes_stat.nr_unused++;
239 		if (!sb || (sb->s_flags & MS_ACTIVE)) {
240 			spin_unlock(&inode_lock);
241 			return;
242 		}
243 		inode->i_state |= I_WILL_FREE;
244 		spin_unlock(&inode_lock);
245 		/*
246 		 * write_inode_now is a noop as we set BDI_CAP_NO_WRITEBACK
247 		 * in our backing_dev_info.
248 		 */
249 		write_inode_now(inode, 1);
250 		spin_lock(&inode_lock);
251 		inode->i_state &= ~I_WILL_FREE;
252 		inodes_stat.nr_unused--;
253 		hlist_del_init(&inode->i_hash);
254 	}
255 	list_del_init(&inode->i_list);
256 	list_del_init(&inode->i_sb_list);
257 	inode->i_state |= I_FREEING;
258 	inodes_stat.nr_inodes--;
259 	spin_unlock(&inode_lock);
260 	truncate_hugepages(inode, 0);
261 	clear_inode(inode);
262 	destroy_inode(inode);
263 }
264 
265 static void hugetlbfs_drop_inode(struct inode *inode)
266 {
267 	if (!inode->i_nlink)
268 		generic_delete_inode(inode);
269 	else
270 		hugetlbfs_forget_inode(inode);
271 }
272 
273 static inline void
274 hugetlb_vmtruncate_list(struct prio_tree_root *root, pgoff_t pgoff)
275 {
276 	struct vm_area_struct *vma;
277 	struct prio_tree_iter iter;
278 
279 	vma_prio_tree_foreach(vma, &iter, root, pgoff, ULONG_MAX) {
280 		unsigned long v_offset;
281 
282 		/*
283 		 * Can the expression below overflow on 32-bit arches?
284 		 * No, because the prio_tree returns us only those vmas
285 		 * which overlap the truncated area starting at pgoff,
286 		 * and no vma on a 32-bit arch can span beyond the 4GB.
287 		 */
288 		if (vma->vm_pgoff < pgoff)
289 			v_offset = (pgoff - vma->vm_pgoff) << PAGE_SHIFT;
290 		else
291 			v_offset = 0;
292 
293 		__unmap_hugepage_range(vma,
294 				vma->vm_start + v_offset, vma->vm_end);
295 	}
296 }
297 
298 /*
299  * Expanding truncates are not allowed.
300  */
301 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
302 {
303 	pgoff_t pgoff;
304 	struct address_space *mapping = inode->i_mapping;
305 
306 	if (offset > inode->i_size)
307 		return -EINVAL;
308 
309 	BUG_ON(offset & ~HPAGE_MASK);
310 	pgoff = offset >> PAGE_SHIFT;
311 
312 	inode->i_size = offset;
313 	spin_lock(&mapping->i_mmap_lock);
314 	if (!prio_tree_empty(&mapping->i_mmap))
315 		hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
316 	spin_unlock(&mapping->i_mmap_lock);
317 	truncate_hugepages(inode, offset);
318 	return 0;
319 }
320 
321 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
322 {
323 	struct inode *inode = dentry->d_inode;
324 	int error;
325 	unsigned int ia_valid = attr->ia_valid;
326 
327 	BUG_ON(!inode);
328 
329 	error = inode_change_ok(inode, attr);
330 	if (error)
331 		goto out;
332 
333 	if (ia_valid & ATTR_SIZE) {
334 		error = -EINVAL;
335 		if (!(attr->ia_size & ~HPAGE_MASK))
336 			error = hugetlb_vmtruncate(inode, attr->ia_size);
337 		if (error)
338 			goto out;
339 		attr->ia_valid &= ~ATTR_SIZE;
340 	}
341 	error = inode_setattr(inode, attr);
342 out:
343 	return error;
344 }
345 
346 static struct inode *hugetlbfs_get_inode(struct super_block *sb, uid_t uid,
347 					gid_t gid, int mode, dev_t dev)
348 {
349 	struct inode *inode;
350 
351 	inode = new_inode(sb);
352 	if (inode) {
353 		struct hugetlbfs_inode_info *info;
354 		inode->i_mode = mode;
355 		inode->i_uid = uid;
356 		inode->i_gid = gid;
357 		inode->i_blocks = 0;
358 		inode->i_mapping->a_ops = &hugetlbfs_aops;
359 		inode->i_mapping->backing_dev_info =&hugetlbfs_backing_dev_info;
360 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
361 		INIT_LIST_HEAD(&inode->i_mapping->private_list);
362 		info = HUGETLBFS_I(inode);
363 		mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, NULL);
364 		switch (mode & S_IFMT) {
365 		default:
366 			init_special_inode(inode, mode, dev);
367 			break;
368 		case S_IFREG:
369 			inode->i_op = &hugetlbfs_inode_operations;
370 			inode->i_fop = &hugetlbfs_file_operations;
371 			break;
372 		case S_IFDIR:
373 			inode->i_op = &hugetlbfs_dir_inode_operations;
374 			inode->i_fop = &simple_dir_operations;
375 
376 			/* directory inodes start off with i_nlink == 2 (for "." entry) */
377 			inc_nlink(inode);
378 			break;
379 		case S_IFLNK:
380 			inode->i_op = &page_symlink_inode_operations;
381 			break;
382 		}
383 	}
384 	return inode;
385 }
386 
387 /*
388  * File creation. Allocate an inode, and we're done..
389  */
390 static int hugetlbfs_mknod(struct inode *dir,
391 			struct dentry *dentry, int mode, dev_t dev)
392 {
393 	struct inode *inode;
394 	int error = -ENOSPC;
395 	gid_t gid;
396 
397 	if (dir->i_mode & S_ISGID) {
398 		gid = dir->i_gid;
399 		if (S_ISDIR(mode))
400 			mode |= S_ISGID;
401 	} else {
402 		gid = current->fsgid;
403 	}
404 	inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid, gid, mode, dev);
405 	if (inode) {
406 		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
407 		d_instantiate(dentry, inode);
408 		dget(dentry);	/* Extra count - pin the dentry in core */
409 		error = 0;
410 	}
411 	return error;
412 }
413 
414 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
415 {
416 	int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
417 	if (!retval)
418 		inc_nlink(dir);
419 	return retval;
420 }
421 
422 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, int mode, struct nameidata *nd)
423 {
424 	return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
425 }
426 
427 static int hugetlbfs_symlink(struct inode *dir,
428 			struct dentry *dentry, const char *symname)
429 {
430 	struct inode *inode;
431 	int error = -ENOSPC;
432 	gid_t gid;
433 
434 	if (dir->i_mode & S_ISGID)
435 		gid = dir->i_gid;
436 	else
437 		gid = current->fsgid;
438 
439 	inode = hugetlbfs_get_inode(dir->i_sb, current->fsuid,
440 					gid, S_IFLNK|S_IRWXUGO, 0);
441 	if (inode) {
442 		int l = strlen(symname)+1;
443 		error = page_symlink(inode, symname, l);
444 		if (!error) {
445 			d_instantiate(dentry, inode);
446 			dget(dentry);
447 		} else
448 			iput(inode);
449 	}
450 	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
451 
452 	return error;
453 }
454 
455 /*
456  * mark the head page dirty
457  */
458 static int hugetlbfs_set_page_dirty(struct page *page)
459 {
460 	struct page *head = compound_head(page);
461 
462 	SetPageDirty(head);
463 	return 0;
464 }
465 
466 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
467 {
468 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
469 
470 	buf->f_type = HUGETLBFS_MAGIC;
471 	buf->f_bsize = HPAGE_SIZE;
472 	if (sbinfo) {
473 		spin_lock(&sbinfo->stat_lock);
474 		/* If no limits set, just report 0 for max/free/used
475 		 * blocks, like simple_statfs() */
476 		if (sbinfo->max_blocks >= 0) {
477 			buf->f_blocks = sbinfo->max_blocks;
478 			buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
479 			buf->f_files = sbinfo->max_inodes;
480 			buf->f_ffree = sbinfo->free_inodes;
481 		}
482 		spin_unlock(&sbinfo->stat_lock);
483 	}
484 	buf->f_namelen = NAME_MAX;
485 	return 0;
486 }
487 
488 static void hugetlbfs_put_super(struct super_block *sb)
489 {
490 	struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
491 
492 	if (sbi) {
493 		sb->s_fs_info = NULL;
494 		kfree(sbi);
495 	}
496 }
497 
498 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
499 {
500 	if (sbinfo->free_inodes >= 0) {
501 		spin_lock(&sbinfo->stat_lock);
502 		if (unlikely(!sbinfo->free_inodes)) {
503 			spin_unlock(&sbinfo->stat_lock);
504 			return 0;
505 		}
506 		sbinfo->free_inodes--;
507 		spin_unlock(&sbinfo->stat_lock);
508 	}
509 
510 	return 1;
511 }
512 
513 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
514 {
515 	if (sbinfo->free_inodes >= 0) {
516 		spin_lock(&sbinfo->stat_lock);
517 		sbinfo->free_inodes++;
518 		spin_unlock(&sbinfo->stat_lock);
519 	}
520 }
521 
522 
523 static struct kmem_cache *hugetlbfs_inode_cachep;
524 
525 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
526 {
527 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
528 	struct hugetlbfs_inode_info *p;
529 
530 	if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
531 		return NULL;
532 	p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);
533 	if (unlikely(!p)) {
534 		hugetlbfs_inc_free_inodes(sbinfo);
535 		return NULL;
536 	}
537 	return &p->vfs_inode;
538 }
539 
540 static void hugetlbfs_destroy_inode(struct inode *inode)
541 {
542 	hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
543 	mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
544 	kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
545 }
546 
547 static const struct address_space_operations hugetlbfs_aops = {
548 	.readpage	= hugetlbfs_readpage,
549 	.prepare_write	= hugetlbfs_prepare_write,
550 	.commit_write	= hugetlbfs_commit_write,
551 	.set_page_dirty	= hugetlbfs_set_page_dirty,
552 };
553 
554 
555 static void init_once(void *foo, struct kmem_cache *cachep, unsigned long flags)
556 {
557 	struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
558 
559 	inode_init_once(&ei->vfs_inode);
560 }
561 
562 const struct file_operations hugetlbfs_file_operations = {
563 	.mmap			= hugetlbfs_file_mmap,
564 	.fsync			= simple_sync_file,
565 	.get_unmapped_area	= hugetlb_get_unmapped_area,
566 };
567 
568 static const struct inode_operations hugetlbfs_dir_inode_operations = {
569 	.create		= hugetlbfs_create,
570 	.lookup		= simple_lookup,
571 	.link		= simple_link,
572 	.unlink		= simple_unlink,
573 	.symlink	= hugetlbfs_symlink,
574 	.mkdir		= hugetlbfs_mkdir,
575 	.rmdir		= simple_rmdir,
576 	.mknod		= hugetlbfs_mknod,
577 	.rename		= simple_rename,
578 	.setattr	= hugetlbfs_setattr,
579 };
580 
581 static const struct inode_operations hugetlbfs_inode_operations = {
582 	.setattr	= hugetlbfs_setattr,
583 };
584 
585 static const struct super_operations hugetlbfs_ops = {
586 	.alloc_inode    = hugetlbfs_alloc_inode,
587 	.destroy_inode  = hugetlbfs_destroy_inode,
588 	.statfs		= hugetlbfs_statfs,
589 	.delete_inode	= hugetlbfs_delete_inode,
590 	.drop_inode	= hugetlbfs_drop_inode,
591 	.put_super	= hugetlbfs_put_super,
592 };
593 
594 static int
595 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
596 {
597 	char *opt, *value, *rest;
598 
599 	if (!options)
600 		return 0;
601 	while ((opt = strsep(&options, ",")) != NULL) {
602 		if (!*opt)
603 			continue;
604 
605 		value = strchr(opt, '=');
606 		if (!value || !*value)
607 			return -EINVAL;
608 		else
609 			*value++ = '\0';
610 
611 		if (!strcmp(opt, "uid"))
612 			pconfig->uid = simple_strtoul(value, &value, 0);
613 		else if (!strcmp(opt, "gid"))
614 			pconfig->gid = simple_strtoul(value, &value, 0);
615 		else if (!strcmp(opt, "mode"))
616 			pconfig->mode = simple_strtoul(value,&value,0) & 0777U;
617 		else if (!strcmp(opt, "size")) {
618 			unsigned long long size = memparse(value, &rest);
619 			if (*rest == '%') {
620 				size <<= HPAGE_SHIFT;
621 				size *= max_huge_pages;
622 				do_div(size, 100);
623 				rest++;
624 			}
625 			pconfig->nr_blocks = (size >> HPAGE_SHIFT);
626 			value = rest;
627 		} else if (!strcmp(opt,"nr_inodes")) {
628 			pconfig->nr_inodes = memparse(value, &rest);
629 			value = rest;
630 		} else
631 			return -EINVAL;
632 
633 		if (*value)
634 			return -EINVAL;
635 	}
636 	return 0;
637 }
638 
639 static int
640 hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
641 {
642 	struct inode * inode;
643 	struct dentry * root;
644 	int ret;
645 	struct hugetlbfs_config config;
646 	struct hugetlbfs_sb_info *sbinfo;
647 
648 	config.nr_blocks = -1; /* No limit on size by default */
649 	config.nr_inodes = -1; /* No limit on number of inodes by default */
650 	config.uid = current->fsuid;
651 	config.gid = current->fsgid;
652 	config.mode = 0755;
653 	ret = hugetlbfs_parse_options(data, &config);
654 
655 	if (ret)
656 		return ret;
657 
658 	sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
659 	if (!sbinfo)
660 		return -ENOMEM;
661 	sb->s_fs_info = sbinfo;
662 	spin_lock_init(&sbinfo->stat_lock);
663 	sbinfo->max_blocks = config.nr_blocks;
664 	sbinfo->free_blocks = config.nr_blocks;
665 	sbinfo->max_inodes = config.nr_inodes;
666 	sbinfo->free_inodes = config.nr_inodes;
667 	sb->s_maxbytes = MAX_LFS_FILESIZE;
668 	sb->s_blocksize = HPAGE_SIZE;
669 	sb->s_blocksize_bits = HPAGE_SHIFT;
670 	sb->s_magic = HUGETLBFS_MAGIC;
671 	sb->s_op = &hugetlbfs_ops;
672 	sb->s_time_gran = 1;
673 	inode = hugetlbfs_get_inode(sb, config.uid, config.gid,
674 					S_IFDIR | config.mode, 0);
675 	if (!inode)
676 		goto out_free;
677 
678 	root = d_alloc_root(inode);
679 	if (!root) {
680 		iput(inode);
681 		goto out_free;
682 	}
683 	sb->s_root = root;
684 	return 0;
685 out_free:
686 	kfree(sbinfo);
687 	return -ENOMEM;
688 }
689 
690 int hugetlb_get_quota(struct address_space *mapping)
691 {
692 	int ret = 0;
693 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
694 
695 	if (sbinfo->free_blocks > -1) {
696 		spin_lock(&sbinfo->stat_lock);
697 		if (sbinfo->free_blocks > 0)
698 			sbinfo->free_blocks--;
699 		else
700 			ret = -ENOMEM;
701 		spin_unlock(&sbinfo->stat_lock);
702 	}
703 
704 	return ret;
705 }
706 
707 void hugetlb_put_quota(struct address_space *mapping)
708 {
709 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(mapping->host->i_sb);
710 
711 	if (sbinfo->free_blocks > -1) {
712 		spin_lock(&sbinfo->stat_lock);
713 		sbinfo->free_blocks++;
714 		spin_unlock(&sbinfo->stat_lock);
715 	}
716 }
717 
718 static int hugetlbfs_get_sb(struct file_system_type *fs_type,
719 	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
720 {
721 	return get_sb_nodev(fs_type, flags, data, hugetlbfs_fill_super, mnt);
722 }
723 
724 static struct file_system_type hugetlbfs_fs_type = {
725 	.name		= "hugetlbfs",
726 	.get_sb		= hugetlbfs_get_sb,
727 	.kill_sb	= kill_litter_super,
728 };
729 
730 static struct vfsmount *hugetlbfs_vfsmount;
731 
732 static int can_do_hugetlb_shm(void)
733 {
734 	return likely(capable(CAP_IPC_LOCK) ||
735 			in_group_p(sysctl_hugetlb_shm_group) ||
736 			can_do_mlock());
737 }
738 
739 struct file *hugetlb_file_setup(const char *name, size_t size)
740 {
741 	int error = -ENOMEM;
742 	struct file *file;
743 	struct inode *inode;
744 	struct dentry *dentry, *root;
745 	struct qstr quick_string;
746 
747 	if (!hugetlbfs_vfsmount)
748 		return ERR_PTR(-ENOENT);
749 
750 	if (!can_do_hugetlb_shm())
751 		return ERR_PTR(-EPERM);
752 
753 	if (!user_shm_lock(size, current->user))
754 		return ERR_PTR(-ENOMEM);
755 
756 	root = hugetlbfs_vfsmount->mnt_root;
757 	quick_string.name = name;
758 	quick_string.len = strlen(quick_string.name);
759 	quick_string.hash = 0;
760 	dentry = d_alloc(root, &quick_string);
761 	if (!dentry)
762 		goto out_shm_unlock;
763 
764 	error = -ENFILE;
765 	file = get_empty_filp();
766 	if (!file)
767 		goto out_dentry;
768 
769 	error = -ENOSPC;
770 	inode = hugetlbfs_get_inode(root->d_sb, current->fsuid,
771 				current->fsgid, S_IFREG | S_IRWXUGO, 0);
772 	if (!inode)
773 		goto out_file;
774 
775 	error = -ENOMEM;
776 	if (hugetlb_reserve_pages(inode, 0, size >> HPAGE_SHIFT))
777 		goto out_inode;
778 
779 	d_instantiate(dentry, inode);
780 	inode->i_size = size;
781 	inode->i_nlink = 0;
782 	file->f_path.mnt = mntget(hugetlbfs_vfsmount);
783 	file->f_path.dentry = dentry;
784 	file->f_mapping = inode->i_mapping;
785 	file->f_op = &hugetlbfs_file_operations;
786 	file->f_mode = FMODE_WRITE | FMODE_READ;
787 	return file;
788 
789 out_inode:
790 	iput(inode);
791 out_file:
792 	put_filp(file);
793 out_dentry:
794 	dput(dentry);
795 out_shm_unlock:
796 	user_shm_unlock(size, current->user);
797 	return ERR_PTR(error);
798 }
799 
800 static int __init init_hugetlbfs_fs(void)
801 {
802 	int error;
803 	struct vfsmount *vfsmount;
804 
805 	hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
806 					sizeof(struct hugetlbfs_inode_info),
807 					0, 0, init_once, NULL);
808 	if (hugetlbfs_inode_cachep == NULL)
809 		return -ENOMEM;
810 
811 	error = register_filesystem(&hugetlbfs_fs_type);
812 	if (error)
813 		goto out;
814 
815 	vfsmount = kern_mount(&hugetlbfs_fs_type);
816 
817 	if (!IS_ERR(vfsmount)) {
818 		hugetlbfs_vfsmount = vfsmount;
819 		return 0;
820 	}
821 
822 	error = PTR_ERR(vfsmount);
823 
824  out:
825 	if (error)
826 		kmem_cache_destroy(hugetlbfs_inode_cachep);
827 	return error;
828 }
829 
830 static void __exit exit_hugetlbfs_fs(void)
831 {
832 	kmem_cache_destroy(hugetlbfs_inode_cachep);
833 	unregister_filesystem(&hugetlbfs_fs_type);
834 }
835 
836 module_init(init_hugetlbfs_fs)
837 module_exit(exit_hugetlbfs_fs)
838 
839 MODULE_LICENSE("GPL");
840