xref: /openbmc/linux/fs/hugetlbfs/inode.c (revision 32981ea5)
1 /*
2  * hugetlbpage-backed filesystem.  Based on ramfs.
3  *
4  * Nadia Yvette Chambers, 2002
5  *
6  * Copyright (C) 2002 Linus Torvalds.
7  * License: GPL
8  */
9 
10 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11 
12 #include <linux/thread_info.h>
13 #include <asm/current.h>
14 #include <linux/sched.h>		/* remove ASAP */
15 #include <linux/falloc.h>
16 #include <linux/fs.h>
17 #include <linux/mount.h>
18 #include <linux/file.h>
19 #include <linux/kernel.h>
20 #include <linux/writeback.h>
21 #include <linux/pagemap.h>
22 #include <linux/highmem.h>
23 #include <linux/init.h>
24 #include <linux/string.h>
25 #include <linux/capability.h>
26 #include <linux/ctype.h>
27 #include <linux/backing-dev.h>
28 #include <linux/hugetlb.h>
29 #include <linux/pagevec.h>
30 #include <linux/parser.h>
31 #include <linux/mman.h>
32 #include <linux/slab.h>
33 #include <linux/dnotify.h>
34 #include <linux/statfs.h>
35 #include <linux/security.h>
36 #include <linux/magic.h>
37 #include <linux/migrate.h>
38 #include <linux/uio.h>
39 
40 #include <asm/uaccess.h>
41 
42 static const struct super_operations hugetlbfs_ops;
43 static const struct address_space_operations hugetlbfs_aops;
44 const struct file_operations hugetlbfs_file_operations;
45 static const struct inode_operations hugetlbfs_dir_inode_operations;
46 static const struct inode_operations hugetlbfs_inode_operations;
47 
48 struct hugetlbfs_config {
49 	kuid_t   uid;
50 	kgid_t   gid;
51 	umode_t mode;
52 	long	max_hpages;
53 	long	nr_inodes;
54 	struct hstate *hstate;
55 	long    min_hpages;
56 };
57 
58 struct hugetlbfs_inode_info {
59 	struct shared_policy policy;
60 	struct inode vfs_inode;
61 };
62 
63 static inline struct hugetlbfs_inode_info *HUGETLBFS_I(struct inode *inode)
64 {
65 	return container_of(inode, struct hugetlbfs_inode_info, vfs_inode);
66 }
67 
68 int sysctl_hugetlb_shm_group;
69 
70 enum {
71 	Opt_size, Opt_nr_inodes,
72 	Opt_mode, Opt_uid, Opt_gid,
73 	Opt_pagesize, Opt_min_size,
74 	Opt_err,
75 };
76 
77 static const match_table_t tokens = {
78 	{Opt_size,	"size=%s"},
79 	{Opt_nr_inodes,	"nr_inodes=%s"},
80 	{Opt_mode,	"mode=%o"},
81 	{Opt_uid,	"uid=%u"},
82 	{Opt_gid,	"gid=%u"},
83 	{Opt_pagesize,	"pagesize=%s"},
84 	{Opt_min_size,	"min_size=%s"},
85 	{Opt_err,	NULL},
86 };
87 
88 #ifdef CONFIG_NUMA
89 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
90 					struct inode *inode, pgoff_t index)
91 {
92 	vma->vm_policy = mpol_shared_policy_lookup(&HUGETLBFS_I(inode)->policy,
93 							index);
94 }
95 
96 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
97 {
98 	mpol_cond_put(vma->vm_policy);
99 }
100 #else
101 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
102 					struct inode *inode, pgoff_t index)
103 {
104 }
105 
106 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
107 {
108 }
109 #endif
110 
111 static void huge_pagevec_release(struct pagevec *pvec)
112 {
113 	int i;
114 
115 	for (i = 0; i < pagevec_count(pvec); ++i)
116 		put_page(pvec->pages[i]);
117 
118 	pagevec_reinit(pvec);
119 }
120 
121 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
122 {
123 	struct inode *inode = file_inode(file);
124 	loff_t len, vma_len;
125 	int ret;
126 	struct hstate *h = hstate_file(file);
127 
128 	/*
129 	 * vma address alignment (but not the pgoff alignment) has
130 	 * already been checked by prepare_hugepage_range.  If you add
131 	 * any error returns here, do so after setting VM_HUGETLB, so
132 	 * is_vm_hugetlb_page tests below unmap_region go the right
133 	 * way when do_mmap_pgoff unwinds (may be important on powerpc
134 	 * and ia64).
135 	 */
136 	vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
137 	vma->vm_ops = &hugetlb_vm_ops;
138 
139 	if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))
140 		return -EINVAL;
141 
142 	vma_len = (loff_t)(vma->vm_end - vma->vm_start);
143 
144 	inode_lock(inode);
145 	file_accessed(file);
146 
147 	ret = -ENOMEM;
148 	len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
149 
150 	if (hugetlb_reserve_pages(inode,
151 				vma->vm_pgoff >> huge_page_order(h),
152 				len >> huge_page_shift(h), vma,
153 				vma->vm_flags))
154 		goto out;
155 
156 	ret = 0;
157 	if (vma->vm_flags & VM_WRITE && inode->i_size < len)
158 		inode->i_size = len;
159 out:
160 	inode_unlock(inode);
161 
162 	return ret;
163 }
164 
165 /*
166  * Called under down_write(mmap_sem).
167  */
168 
169 #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
170 static unsigned long
171 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
172 		unsigned long len, unsigned long pgoff, unsigned long flags)
173 {
174 	struct mm_struct *mm = current->mm;
175 	struct vm_area_struct *vma;
176 	struct hstate *h = hstate_file(file);
177 	struct vm_unmapped_area_info info;
178 
179 	if (len & ~huge_page_mask(h))
180 		return -EINVAL;
181 	if (len > TASK_SIZE)
182 		return -ENOMEM;
183 
184 	if (flags & MAP_FIXED) {
185 		if (prepare_hugepage_range(file, addr, len))
186 			return -EINVAL;
187 		return addr;
188 	}
189 
190 	if (addr) {
191 		addr = ALIGN(addr, huge_page_size(h));
192 		vma = find_vma(mm, addr);
193 		if (TASK_SIZE - len >= addr &&
194 		    (!vma || addr + len <= vma->vm_start))
195 			return addr;
196 	}
197 
198 	info.flags = 0;
199 	info.length = len;
200 	info.low_limit = TASK_UNMAPPED_BASE;
201 	info.high_limit = TASK_SIZE;
202 	info.align_mask = PAGE_MASK & ~huge_page_mask(h);
203 	info.align_offset = 0;
204 	return vm_unmapped_area(&info);
205 }
206 #endif
207 
208 static size_t
209 hugetlbfs_read_actor(struct page *page, unsigned long offset,
210 			struct iov_iter *to, unsigned long size)
211 {
212 	size_t copied = 0;
213 	int i, chunksize;
214 
215 	/* Find which 4k chunk and offset with in that chunk */
216 	i = offset >> PAGE_SHIFT;
217 	offset = offset & ~PAGE_MASK;
218 
219 	while (size) {
220 		size_t n;
221 		chunksize = PAGE_SIZE;
222 		if (offset)
223 			chunksize -= offset;
224 		if (chunksize > size)
225 			chunksize = size;
226 		n = copy_page_to_iter(&page[i], offset, chunksize, to);
227 		copied += n;
228 		if (n != chunksize)
229 			return copied;
230 		offset = 0;
231 		size -= chunksize;
232 		i++;
233 	}
234 	return copied;
235 }
236 
237 /*
238  * Support for read() - Find the page attached to f_mapping and copy out the
239  * data. Its *very* similar to do_generic_mapping_read(), we can't use that
240  * since it has PAGE_SIZE assumptions.
241  */
242 static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
243 {
244 	struct file *file = iocb->ki_filp;
245 	struct hstate *h = hstate_file(file);
246 	struct address_space *mapping = file->f_mapping;
247 	struct inode *inode = mapping->host;
248 	unsigned long index = iocb->ki_pos >> huge_page_shift(h);
249 	unsigned long offset = iocb->ki_pos & ~huge_page_mask(h);
250 	unsigned long end_index;
251 	loff_t isize;
252 	ssize_t retval = 0;
253 
254 	while (iov_iter_count(to)) {
255 		struct page *page;
256 		size_t nr, copied;
257 
258 		/* nr is the maximum number of bytes to copy from this page */
259 		nr = huge_page_size(h);
260 		isize = i_size_read(inode);
261 		if (!isize)
262 			break;
263 		end_index = (isize - 1) >> huge_page_shift(h);
264 		if (index > end_index)
265 			break;
266 		if (index == end_index) {
267 			nr = ((isize - 1) & ~huge_page_mask(h)) + 1;
268 			if (nr <= offset)
269 				break;
270 		}
271 		nr = nr - offset;
272 
273 		/* Find the page */
274 		page = find_lock_page(mapping, index);
275 		if (unlikely(page == NULL)) {
276 			/*
277 			 * We have a HOLE, zero out the user-buffer for the
278 			 * length of the hole or request.
279 			 */
280 			copied = iov_iter_zero(nr, to);
281 		} else {
282 			unlock_page(page);
283 
284 			/*
285 			 * We have the page, copy it to user space buffer.
286 			 */
287 			copied = hugetlbfs_read_actor(page, offset, to, nr);
288 			put_page(page);
289 		}
290 		offset += copied;
291 		retval += copied;
292 		if (copied != nr && iov_iter_count(to)) {
293 			if (!retval)
294 				retval = -EFAULT;
295 			break;
296 		}
297 		index += offset >> huge_page_shift(h);
298 		offset &= ~huge_page_mask(h);
299 	}
300 	iocb->ki_pos = ((loff_t)index << huge_page_shift(h)) + offset;
301 	return retval;
302 }
303 
304 static int hugetlbfs_write_begin(struct file *file,
305 			struct address_space *mapping,
306 			loff_t pos, unsigned len, unsigned flags,
307 			struct page **pagep, void **fsdata)
308 {
309 	return -EINVAL;
310 }
311 
312 static int hugetlbfs_write_end(struct file *file, struct address_space *mapping,
313 			loff_t pos, unsigned len, unsigned copied,
314 			struct page *page, void *fsdata)
315 {
316 	BUG();
317 	return -EINVAL;
318 }
319 
320 static void remove_huge_page(struct page *page)
321 {
322 	ClearPageDirty(page);
323 	ClearPageUptodate(page);
324 	delete_from_page_cache(page);
325 }
326 
327 static void
328 hugetlb_vmdelete_list(struct rb_root *root, pgoff_t start, pgoff_t end)
329 {
330 	struct vm_area_struct *vma;
331 
332 	/*
333 	 * end == 0 indicates that the entire range after
334 	 * start should be unmapped.
335 	 */
336 	vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) {
337 		unsigned long v_offset;
338 		unsigned long v_end;
339 
340 		/*
341 		 * Can the expression below overflow on 32-bit arches?
342 		 * No, because the interval tree returns us only those vmas
343 		 * which overlap the truncated area starting at pgoff,
344 		 * and no vma on a 32-bit arch can span beyond the 4GB.
345 		 */
346 		if (vma->vm_pgoff < start)
347 			v_offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
348 		else
349 			v_offset = 0;
350 
351 		if (!end)
352 			v_end = vma->vm_end;
353 		else {
354 			v_end = ((end - vma->vm_pgoff) << PAGE_SHIFT)
355 							+ vma->vm_start;
356 			if (v_end > vma->vm_end)
357 				v_end = vma->vm_end;
358 		}
359 
360 		unmap_hugepage_range(vma, vma->vm_start + v_offset, v_end,
361 									NULL);
362 	}
363 }
364 
365 /*
366  * remove_inode_hugepages handles two distinct cases: truncation and hole
367  * punch.  There are subtle differences in operation for each case.
368  *
369  * truncation is indicated by end of range being LLONG_MAX
370  *	In this case, we first scan the range and release found pages.
371  *	After releasing pages, hugetlb_unreserve_pages cleans up region/reserv
372  *	maps and global counts.  Page faults can not race with truncation
373  *	in this routine.  hugetlb_no_page() prevents page faults in the
374  *	truncated range.  It checks i_size before allocation, and again after
375  *	with the page table lock for the page held.  The same lock must be
376  *	acquired to unmap a page.
377  * hole punch is indicated if end is not LLONG_MAX
378  *	In the hole punch case we scan the range and release found pages.
379  *	Only when releasing a page is the associated region/reserv map
380  *	deleted.  The region/reserv map for ranges without associated
381  *	pages are not modified.  Page faults can race with hole punch.
382  *	This is indicated if we find a mapped page.
383  * Note: If the passed end of range value is beyond the end of file, but
384  * not LLONG_MAX this routine still performs a hole punch operation.
385  */
386 static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
387 				   loff_t lend)
388 {
389 	struct hstate *h = hstate_inode(inode);
390 	struct address_space *mapping = &inode->i_data;
391 	const pgoff_t start = lstart >> huge_page_shift(h);
392 	const pgoff_t end = lend >> huge_page_shift(h);
393 	struct vm_area_struct pseudo_vma;
394 	struct pagevec pvec;
395 	pgoff_t next;
396 	int i, freed = 0;
397 	long lookup_nr = PAGEVEC_SIZE;
398 	bool truncate_op = (lend == LLONG_MAX);
399 
400 	memset(&pseudo_vma, 0, sizeof(struct vm_area_struct));
401 	pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
402 	pagevec_init(&pvec, 0);
403 	next = start;
404 	while (next < end) {
405 		/*
406 		 * Don't grab more pages than the number left in the range.
407 		 */
408 		if (end - next < lookup_nr)
409 			lookup_nr = end - next;
410 
411 		/*
412 		 * When no more pages are found, we are done.
413 		 */
414 		if (!pagevec_lookup(&pvec, mapping, next, lookup_nr))
415 			break;
416 
417 		for (i = 0; i < pagevec_count(&pvec); ++i) {
418 			struct page *page = pvec.pages[i];
419 			bool rsv_on_error;
420 			u32 hash;
421 
422 			/*
423 			 * The page (index) could be beyond end.  This is
424 			 * only possible in the punch hole case as end is
425 			 * max page offset in the truncate case.
426 			 */
427 			next = page->index;
428 			if (next >= end)
429 				break;
430 
431 			hash = hugetlb_fault_mutex_hash(h, current->mm,
432 							&pseudo_vma,
433 							mapping, next, 0);
434 			mutex_lock(&hugetlb_fault_mutex_table[hash]);
435 
436 			/*
437 			 * If page is mapped, it was faulted in after being
438 			 * unmapped in caller.  Unmap (again) now after taking
439 			 * the fault mutex.  The mutex will prevent faults
440 			 * until we finish removing the page.
441 			 *
442 			 * This race can only happen in the hole punch case.
443 			 * Getting here in a truncate operation is a bug.
444 			 */
445 			if (unlikely(page_mapped(page))) {
446 				BUG_ON(truncate_op);
447 
448 				i_mmap_lock_write(mapping);
449 				hugetlb_vmdelete_list(&mapping->i_mmap,
450 					next * pages_per_huge_page(h),
451 					(next + 1) * pages_per_huge_page(h));
452 				i_mmap_unlock_write(mapping);
453 			}
454 
455 			lock_page(page);
456 			/*
457 			 * We must free the huge page and remove from page
458 			 * cache (remove_huge_page) BEFORE removing the
459 			 * region/reserve map (hugetlb_unreserve_pages).  In
460 			 * rare out of memory conditions, removal of the
461 			 * region/reserve map could fail.  Before free'ing
462 			 * the page, note PagePrivate which is used in case
463 			 * of error.
464 			 */
465 			rsv_on_error = !PagePrivate(page);
466 			remove_huge_page(page);
467 			freed++;
468 			if (!truncate_op) {
469 				if (unlikely(hugetlb_unreserve_pages(inode,
470 							next, next + 1, 1)))
471 					hugetlb_fix_reserve_counts(inode,
472 								rsv_on_error);
473 			}
474 
475 			unlock_page(page);
476 			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
477 		}
478 		++next;
479 		huge_pagevec_release(&pvec);
480 		cond_resched();
481 	}
482 
483 	if (truncate_op)
484 		(void)hugetlb_unreserve_pages(inode, start, LONG_MAX, freed);
485 }
486 
487 static void hugetlbfs_evict_inode(struct inode *inode)
488 {
489 	struct resv_map *resv_map;
490 
491 	remove_inode_hugepages(inode, 0, LLONG_MAX);
492 	resv_map = (struct resv_map *)inode->i_mapping->private_data;
493 	/* root inode doesn't have the resv_map, so we should check it */
494 	if (resv_map)
495 		resv_map_release(&resv_map->refs);
496 	clear_inode(inode);
497 }
498 
499 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
500 {
501 	pgoff_t pgoff;
502 	struct address_space *mapping = inode->i_mapping;
503 	struct hstate *h = hstate_inode(inode);
504 
505 	BUG_ON(offset & ~huge_page_mask(h));
506 	pgoff = offset >> PAGE_SHIFT;
507 
508 	i_size_write(inode, offset);
509 	i_mmap_lock_write(mapping);
510 	if (!RB_EMPTY_ROOT(&mapping->i_mmap))
511 		hugetlb_vmdelete_list(&mapping->i_mmap, pgoff, 0);
512 	i_mmap_unlock_write(mapping);
513 	remove_inode_hugepages(inode, offset, LLONG_MAX);
514 	return 0;
515 }
516 
517 static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
518 {
519 	struct hstate *h = hstate_inode(inode);
520 	loff_t hpage_size = huge_page_size(h);
521 	loff_t hole_start, hole_end;
522 
523 	/*
524 	 * For hole punch round up the beginning offset of the hole and
525 	 * round down the end.
526 	 */
527 	hole_start = round_up(offset, hpage_size);
528 	hole_end = round_down(offset + len, hpage_size);
529 
530 	if (hole_end > hole_start) {
531 		struct address_space *mapping = inode->i_mapping;
532 
533 		inode_lock(inode);
534 		i_mmap_lock_write(mapping);
535 		if (!RB_EMPTY_ROOT(&mapping->i_mmap))
536 			hugetlb_vmdelete_list(&mapping->i_mmap,
537 						hole_start >> PAGE_SHIFT,
538 						hole_end  >> PAGE_SHIFT);
539 		i_mmap_unlock_write(mapping);
540 		remove_inode_hugepages(inode, hole_start, hole_end);
541 		inode_unlock(inode);
542 	}
543 
544 	return 0;
545 }
546 
547 static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
548 				loff_t len)
549 {
550 	struct inode *inode = file_inode(file);
551 	struct address_space *mapping = inode->i_mapping;
552 	struct hstate *h = hstate_inode(inode);
553 	struct vm_area_struct pseudo_vma;
554 	struct mm_struct *mm = current->mm;
555 	loff_t hpage_size = huge_page_size(h);
556 	unsigned long hpage_shift = huge_page_shift(h);
557 	pgoff_t start, index, end;
558 	int error;
559 	u32 hash;
560 
561 	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
562 		return -EOPNOTSUPP;
563 
564 	if (mode & FALLOC_FL_PUNCH_HOLE)
565 		return hugetlbfs_punch_hole(inode, offset, len);
566 
567 	/*
568 	 * Default preallocate case.
569 	 * For this range, start is rounded down and end is rounded up
570 	 * as well as being converted to page offsets.
571 	 */
572 	start = offset >> hpage_shift;
573 	end = (offset + len + hpage_size - 1) >> hpage_shift;
574 
575 	inode_lock(inode);
576 
577 	/* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
578 	error = inode_newsize_ok(inode, offset + len);
579 	if (error)
580 		goto out;
581 
582 	/*
583 	 * Initialize a pseudo vma as this is required by the huge page
584 	 * allocation routines.  If NUMA is configured, use page index
585 	 * as input to create an allocation policy.
586 	 */
587 	memset(&pseudo_vma, 0, sizeof(struct vm_area_struct));
588 	pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
589 	pseudo_vma.vm_file = file;
590 
591 	for (index = start; index < end; index++) {
592 		/*
593 		 * This is supposed to be the vaddr where the page is being
594 		 * faulted in, but we have no vaddr here.
595 		 */
596 		struct page *page;
597 		unsigned long addr;
598 		int avoid_reserve = 0;
599 
600 		cond_resched();
601 
602 		/*
603 		 * fallocate(2) manpage permits EINTR; we may have been
604 		 * interrupted because we are using up too much memory.
605 		 */
606 		if (signal_pending(current)) {
607 			error = -EINTR;
608 			break;
609 		}
610 
611 		/* Set numa allocation policy based on index */
612 		hugetlb_set_vma_policy(&pseudo_vma, inode, index);
613 
614 		/* addr is the offset within the file (zero based) */
615 		addr = index * hpage_size;
616 
617 		/* mutex taken here, fault path and hole punch */
618 		hash = hugetlb_fault_mutex_hash(h, mm, &pseudo_vma, mapping,
619 						index, addr);
620 		mutex_lock(&hugetlb_fault_mutex_table[hash]);
621 
622 		/* See if already present in mapping to avoid alloc/free */
623 		page = find_get_page(mapping, index);
624 		if (page) {
625 			put_page(page);
626 			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
627 			hugetlb_drop_vma_policy(&pseudo_vma);
628 			continue;
629 		}
630 
631 		/* Allocate page and add to page cache */
632 		page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
633 		hugetlb_drop_vma_policy(&pseudo_vma);
634 		if (IS_ERR(page)) {
635 			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
636 			error = PTR_ERR(page);
637 			goto out;
638 		}
639 		clear_huge_page(page, addr, pages_per_huge_page(h));
640 		__SetPageUptodate(page);
641 		error = huge_add_to_page_cache(page, mapping, index);
642 		if (unlikely(error)) {
643 			put_page(page);
644 			mutex_unlock(&hugetlb_fault_mutex_table[hash]);
645 			goto out;
646 		}
647 
648 		mutex_unlock(&hugetlb_fault_mutex_table[hash]);
649 
650 		/*
651 		 * page_put due to reference from alloc_huge_page()
652 		 * unlock_page because locked by add_to_page_cache()
653 		 */
654 		put_page(page);
655 		unlock_page(page);
656 	}
657 
658 	if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
659 		i_size_write(inode, offset + len);
660 	inode->i_ctime = CURRENT_TIME;
661 out:
662 	inode_unlock(inode);
663 	return error;
664 }
665 
666 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
667 {
668 	struct inode *inode = d_inode(dentry);
669 	struct hstate *h = hstate_inode(inode);
670 	int error;
671 	unsigned int ia_valid = attr->ia_valid;
672 
673 	BUG_ON(!inode);
674 
675 	error = inode_change_ok(inode, attr);
676 	if (error)
677 		return error;
678 
679 	if (ia_valid & ATTR_SIZE) {
680 		error = -EINVAL;
681 		if (attr->ia_size & ~huge_page_mask(h))
682 			return -EINVAL;
683 		error = hugetlb_vmtruncate(inode, attr->ia_size);
684 		if (error)
685 			return error;
686 	}
687 
688 	setattr_copy(inode, attr);
689 	mark_inode_dirty(inode);
690 	return 0;
691 }
692 
693 static struct inode *hugetlbfs_get_root(struct super_block *sb,
694 					struct hugetlbfs_config *config)
695 {
696 	struct inode *inode;
697 
698 	inode = new_inode(sb);
699 	if (inode) {
700 		struct hugetlbfs_inode_info *info;
701 		inode->i_ino = get_next_ino();
702 		inode->i_mode = S_IFDIR | config->mode;
703 		inode->i_uid = config->uid;
704 		inode->i_gid = config->gid;
705 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
706 		info = HUGETLBFS_I(inode);
707 		mpol_shared_policy_init(&info->policy, NULL);
708 		inode->i_op = &hugetlbfs_dir_inode_operations;
709 		inode->i_fop = &simple_dir_operations;
710 		/* directory inodes start off with i_nlink == 2 (for "." entry) */
711 		inc_nlink(inode);
712 		lockdep_annotate_inode_mutex_key(inode);
713 	}
714 	return inode;
715 }
716 
717 /*
718  * Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
719  * be taken from reclaim -- unlike regular filesystems. This needs an
720  * annotation because huge_pmd_share() does an allocation under hugetlb's
721  * i_mmap_rwsem.
722  */
723 static struct lock_class_key hugetlbfs_i_mmap_rwsem_key;
724 
725 static struct inode *hugetlbfs_get_inode(struct super_block *sb,
726 					struct inode *dir,
727 					umode_t mode, dev_t dev)
728 {
729 	struct inode *inode;
730 	struct resv_map *resv_map;
731 
732 	resv_map = resv_map_alloc();
733 	if (!resv_map)
734 		return NULL;
735 
736 	inode = new_inode(sb);
737 	if (inode) {
738 		struct hugetlbfs_inode_info *info;
739 		inode->i_ino = get_next_ino();
740 		inode_init_owner(inode, dir, mode);
741 		lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
742 				&hugetlbfs_i_mmap_rwsem_key);
743 		inode->i_mapping->a_ops = &hugetlbfs_aops;
744 		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
745 		inode->i_mapping->private_data = resv_map;
746 		info = HUGETLBFS_I(inode);
747 		/*
748 		 * The policy is initialized here even if we are creating a
749 		 * private inode because initialization simply creates an
750 		 * an empty rb tree and calls rwlock_init(), later when we
751 		 * call mpol_free_shared_policy() it will just return because
752 		 * the rb tree will still be empty.
753 		 */
754 		mpol_shared_policy_init(&info->policy, NULL);
755 		switch (mode & S_IFMT) {
756 		default:
757 			init_special_inode(inode, mode, dev);
758 			break;
759 		case S_IFREG:
760 			inode->i_op = &hugetlbfs_inode_operations;
761 			inode->i_fop = &hugetlbfs_file_operations;
762 			break;
763 		case S_IFDIR:
764 			inode->i_op = &hugetlbfs_dir_inode_operations;
765 			inode->i_fop = &simple_dir_operations;
766 
767 			/* directory inodes start off with i_nlink == 2 (for "." entry) */
768 			inc_nlink(inode);
769 			break;
770 		case S_IFLNK:
771 			inode->i_op = &page_symlink_inode_operations;
772 			inode_nohighmem(inode);
773 			break;
774 		}
775 		lockdep_annotate_inode_mutex_key(inode);
776 	} else
777 		kref_put(&resv_map->refs, resv_map_release);
778 
779 	return inode;
780 }
781 
782 /*
783  * File creation. Allocate an inode, and we're done..
784  */
785 static int hugetlbfs_mknod(struct inode *dir,
786 			struct dentry *dentry, umode_t mode, dev_t dev)
787 {
788 	struct inode *inode;
789 	int error = -ENOSPC;
790 
791 	inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
792 	if (inode) {
793 		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
794 		d_instantiate(dentry, inode);
795 		dget(dentry);	/* Extra count - pin the dentry in core */
796 		error = 0;
797 	}
798 	return error;
799 }
800 
801 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
802 {
803 	int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
804 	if (!retval)
805 		inc_nlink(dir);
806 	return retval;
807 }
808 
809 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
810 {
811 	return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
812 }
813 
814 static int hugetlbfs_symlink(struct inode *dir,
815 			struct dentry *dentry, const char *symname)
816 {
817 	struct inode *inode;
818 	int error = -ENOSPC;
819 
820 	inode = hugetlbfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
821 	if (inode) {
822 		int l = strlen(symname)+1;
823 		error = page_symlink(inode, symname, l);
824 		if (!error) {
825 			d_instantiate(dentry, inode);
826 			dget(dentry);
827 		} else
828 			iput(inode);
829 	}
830 	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
831 
832 	return error;
833 }
834 
835 /*
836  * mark the head page dirty
837  */
838 static int hugetlbfs_set_page_dirty(struct page *page)
839 {
840 	struct page *head = compound_head(page);
841 
842 	SetPageDirty(head);
843 	return 0;
844 }
845 
846 static int hugetlbfs_migrate_page(struct address_space *mapping,
847 				struct page *newpage, struct page *page,
848 				enum migrate_mode mode)
849 {
850 	int rc;
851 
852 	rc = migrate_huge_page_move_mapping(mapping, newpage, page);
853 	if (rc != MIGRATEPAGE_SUCCESS)
854 		return rc;
855 	migrate_page_copy(newpage, page);
856 
857 	return MIGRATEPAGE_SUCCESS;
858 }
859 
860 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
861 {
862 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
863 	struct hstate *h = hstate_inode(d_inode(dentry));
864 
865 	buf->f_type = HUGETLBFS_MAGIC;
866 	buf->f_bsize = huge_page_size(h);
867 	if (sbinfo) {
868 		spin_lock(&sbinfo->stat_lock);
869 		/* If no limits set, just report 0 for max/free/used
870 		 * blocks, like simple_statfs() */
871 		if (sbinfo->spool) {
872 			long free_pages;
873 
874 			spin_lock(&sbinfo->spool->lock);
875 			buf->f_blocks = sbinfo->spool->max_hpages;
876 			free_pages = sbinfo->spool->max_hpages
877 				- sbinfo->spool->used_hpages;
878 			buf->f_bavail = buf->f_bfree = free_pages;
879 			spin_unlock(&sbinfo->spool->lock);
880 			buf->f_files = sbinfo->max_inodes;
881 			buf->f_ffree = sbinfo->free_inodes;
882 		}
883 		spin_unlock(&sbinfo->stat_lock);
884 	}
885 	buf->f_namelen = NAME_MAX;
886 	return 0;
887 }
888 
889 static void hugetlbfs_put_super(struct super_block *sb)
890 {
891 	struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
892 
893 	if (sbi) {
894 		sb->s_fs_info = NULL;
895 
896 		if (sbi->spool)
897 			hugepage_put_subpool(sbi->spool);
898 
899 		kfree(sbi);
900 	}
901 }
902 
903 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
904 {
905 	if (sbinfo->free_inodes >= 0) {
906 		spin_lock(&sbinfo->stat_lock);
907 		if (unlikely(!sbinfo->free_inodes)) {
908 			spin_unlock(&sbinfo->stat_lock);
909 			return 0;
910 		}
911 		sbinfo->free_inodes--;
912 		spin_unlock(&sbinfo->stat_lock);
913 	}
914 
915 	return 1;
916 }
917 
918 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
919 {
920 	if (sbinfo->free_inodes >= 0) {
921 		spin_lock(&sbinfo->stat_lock);
922 		sbinfo->free_inodes++;
923 		spin_unlock(&sbinfo->stat_lock);
924 	}
925 }
926 
927 
928 static struct kmem_cache *hugetlbfs_inode_cachep;
929 
930 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
931 {
932 	struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
933 	struct hugetlbfs_inode_info *p;
934 
935 	if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
936 		return NULL;
937 	p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);
938 	if (unlikely(!p)) {
939 		hugetlbfs_inc_free_inodes(sbinfo);
940 		return NULL;
941 	}
942 	return &p->vfs_inode;
943 }
944 
945 static void hugetlbfs_i_callback(struct rcu_head *head)
946 {
947 	struct inode *inode = container_of(head, struct inode, i_rcu);
948 	kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
949 }
950 
951 static void hugetlbfs_destroy_inode(struct inode *inode)
952 {
953 	hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
954 	mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
955 	call_rcu(&inode->i_rcu, hugetlbfs_i_callback);
956 }
957 
958 static const struct address_space_operations hugetlbfs_aops = {
959 	.write_begin	= hugetlbfs_write_begin,
960 	.write_end	= hugetlbfs_write_end,
961 	.set_page_dirty	= hugetlbfs_set_page_dirty,
962 	.migratepage    = hugetlbfs_migrate_page,
963 };
964 
965 
966 static void init_once(void *foo)
967 {
968 	struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
969 
970 	inode_init_once(&ei->vfs_inode);
971 }
972 
973 const struct file_operations hugetlbfs_file_operations = {
974 	.read_iter		= hugetlbfs_read_iter,
975 	.mmap			= hugetlbfs_file_mmap,
976 	.fsync			= noop_fsync,
977 	.get_unmapped_area	= hugetlb_get_unmapped_area,
978 	.llseek			= default_llseek,
979 	.fallocate		= hugetlbfs_fallocate,
980 };
981 
982 static const struct inode_operations hugetlbfs_dir_inode_operations = {
983 	.create		= hugetlbfs_create,
984 	.lookup		= simple_lookup,
985 	.link		= simple_link,
986 	.unlink		= simple_unlink,
987 	.symlink	= hugetlbfs_symlink,
988 	.mkdir		= hugetlbfs_mkdir,
989 	.rmdir		= simple_rmdir,
990 	.mknod		= hugetlbfs_mknod,
991 	.rename		= simple_rename,
992 	.setattr	= hugetlbfs_setattr,
993 };
994 
995 static const struct inode_operations hugetlbfs_inode_operations = {
996 	.setattr	= hugetlbfs_setattr,
997 };
998 
999 static const struct super_operations hugetlbfs_ops = {
1000 	.alloc_inode    = hugetlbfs_alloc_inode,
1001 	.destroy_inode  = hugetlbfs_destroy_inode,
1002 	.evict_inode	= hugetlbfs_evict_inode,
1003 	.statfs		= hugetlbfs_statfs,
1004 	.put_super	= hugetlbfs_put_super,
1005 	.show_options	= generic_show_options,
1006 };
1007 
1008 enum { NO_SIZE, SIZE_STD, SIZE_PERCENT };
1009 
1010 /*
1011  * Convert size option passed from command line to number of huge pages
1012  * in the pool specified by hstate.  Size option could be in bytes
1013  * (val_type == SIZE_STD) or percentage of the pool (val_type == SIZE_PERCENT).
1014  */
1015 static long long
1016 hugetlbfs_size_to_hpages(struct hstate *h, unsigned long long size_opt,
1017 								int val_type)
1018 {
1019 	if (val_type == NO_SIZE)
1020 		return -1;
1021 
1022 	if (val_type == SIZE_PERCENT) {
1023 		size_opt <<= huge_page_shift(h);
1024 		size_opt *= h->max_huge_pages;
1025 		do_div(size_opt, 100);
1026 	}
1027 
1028 	size_opt >>= huge_page_shift(h);
1029 	return size_opt;
1030 }
1031 
1032 static int
1033 hugetlbfs_parse_options(char *options, struct hugetlbfs_config *pconfig)
1034 {
1035 	char *p, *rest;
1036 	substring_t args[MAX_OPT_ARGS];
1037 	int option;
1038 	unsigned long long max_size_opt = 0, min_size_opt = 0;
1039 	int max_val_type = NO_SIZE, min_val_type = NO_SIZE;
1040 
1041 	if (!options)
1042 		return 0;
1043 
1044 	while ((p = strsep(&options, ",")) != NULL) {
1045 		int token;
1046 		if (!*p)
1047 			continue;
1048 
1049 		token = match_token(p, tokens, args);
1050 		switch (token) {
1051 		case Opt_uid:
1052 			if (match_int(&args[0], &option))
1053  				goto bad_val;
1054 			pconfig->uid = make_kuid(current_user_ns(), option);
1055 			if (!uid_valid(pconfig->uid))
1056 				goto bad_val;
1057 			break;
1058 
1059 		case Opt_gid:
1060 			if (match_int(&args[0], &option))
1061  				goto bad_val;
1062 			pconfig->gid = make_kgid(current_user_ns(), option);
1063 			if (!gid_valid(pconfig->gid))
1064 				goto bad_val;
1065 			break;
1066 
1067 		case Opt_mode:
1068 			if (match_octal(&args[0], &option))
1069  				goto bad_val;
1070 			pconfig->mode = option & 01777U;
1071 			break;
1072 
1073 		case Opt_size: {
1074 			/* memparse() will accept a K/M/G without a digit */
1075 			if (!isdigit(*args[0].from))
1076 				goto bad_val;
1077 			max_size_opt = memparse(args[0].from, &rest);
1078 			max_val_type = SIZE_STD;
1079 			if (*rest == '%')
1080 				max_val_type = SIZE_PERCENT;
1081 			break;
1082 		}
1083 
1084 		case Opt_nr_inodes:
1085 			/* memparse() will accept a K/M/G without a digit */
1086 			if (!isdigit(*args[0].from))
1087 				goto bad_val;
1088 			pconfig->nr_inodes = memparse(args[0].from, &rest);
1089 			break;
1090 
1091 		case Opt_pagesize: {
1092 			unsigned long ps;
1093 			ps = memparse(args[0].from, &rest);
1094 			pconfig->hstate = size_to_hstate(ps);
1095 			if (!pconfig->hstate) {
1096 				pr_err("Unsupported page size %lu MB\n",
1097 					ps >> 20);
1098 				return -EINVAL;
1099 			}
1100 			break;
1101 		}
1102 
1103 		case Opt_min_size: {
1104 			/* memparse() will accept a K/M/G without a digit */
1105 			if (!isdigit(*args[0].from))
1106 				goto bad_val;
1107 			min_size_opt = memparse(args[0].from, &rest);
1108 			min_val_type = SIZE_STD;
1109 			if (*rest == '%')
1110 				min_val_type = SIZE_PERCENT;
1111 			break;
1112 		}
1113 
1114 		default:
1115 			pr_err("Bad mount option: \"%s\"\n", p);
1116 			return -EINVAL;
1117 			break;
1118 		}
1119 	}
1120 
1121 	/*
1122 	 * Use huge page pool size (in hstate) to convert the size
1123 	 * options to number of huge pages.  If NO_SIZE, -1 is returned.
1124 	 */
1125 	pconfig->max_hpages = hugetlbfs_size_to_hpages(pconfig->hstate,
1126 						max_size_opt, max_val_type);
1127 	pconfig->min_hpages = hugetlbfs_size_to_hpages(pconfig->hstate,
1128 						min_size_opt, min_val_type);
1129 
1130 	/*
1131 	 * If max_size was specified, then min_size must be smaller
1132 	 */
1133 	if (max_val_type > NO_SIZE &&
1134 	    pconfig->min_hpages > pconfig->max_hpages) {
1135 		pr_err("minimum size can not be greater than maximum size\n");
1136 		return -EINVAL;
1137 	}
1138 
1139 	return 0;
1140 
1141 bad_val:
1142 	pr_err("Bad value '%s' for mount option '%s'\n", args[0].from, p);
1143  	return -EINVAL;
1144 }
1145 
1146 static int
1147 hugetlbfs_fill_super(struct super_block *sb, void *data, int silent)
1148 {
1149 	int ret;
1150 	struct hugetlbfs_config config;
1151 	struct hugetlbfs_sb_info *sbinfo;
1152 
1153 	save_mount_options(sb, data);
1154 
1155 	config.max_hpages = -1; /* No limit on size by default */
1156 	config.nr_inodes = -1; /* No limit on number of inodes by default */
1157 	config.uid = current_fsuid();
1158 	config.gid = current_fsgid();
1159 	config.mode = 0755;
1160 	config.hstate = &default_hstate;
1161 	config.min_hpages = -1; /* No default minimum size */
1162 	ret = hugetlbfs_parse_options(data, &config);
1163 	if (ret)
1164 		return ret;
1165 
1166 	sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
1167 	if (!sbinfo)
1168 		return -ENOMEM;
1169 	sb->s_fs_info = sbinfo;
1170 	sbinfo->hstate = config.hstate;
1171 	spin_lock_init(&sbinfo->stat_lock);
1172 	sbinfo->max_inodes = config.nr_inodes;
1173 	sbinfo->free_inodes = config.nr_inodes;
1174 	sbinfo->spool = NULL;
1175 	/*
1176 	 * Allocate and initialize subpool if maximum or minimum size is
1177 	 * specified.  Any needed reservations (for minimim size) are taken
1178 	 * taken when the subpool is created.
1179 	 */
1180 	if (config.max_hpages != -1 || config.min_hpages != -1) {
1181 		sbinfo->spool = hugepage_new_subpool(config.hstate,
1182 							config.max_hpages,
1183 							config.min_hpages);
1184 		if (!sbinfo->spool)
1185 			goto out_free;
1186 	}
1187 	sb->s_maxbytes = MAX_LFS_FILESIZE;
1188 	sb->s_blocksize = huge_page_size(config.hstate);
1189 	sb->s_blocksize_bits = huge_page_shift(config.hstate);
1190 	sb->s_magic = HUGETLBFS_MAGIC;
1191 	sb->s_op = &hugetlbfs_ops;
1192 	sb->s_time_gran = 1;
1193 	sb->s_root = d_make_root(hugetlbfs_get_root(sb, &config));
1194 	if (!sb->s_root)
1195 		goto out_free;
1196 	return 0;
1197 out_free:
1198 	kfree(sbinfo->spool);
1199 	kfree(sbinfo);
1200 	return -ENOMEM;
1201 }
1202 
1203 static struct dentry *hugetlbfs_mount(struct file_system_type *fs_type,
1204 	int flags, const char *dev_name, void *data)
1205 {
1206 	return mount_nodev(fs_type, flags, data, hugetlbfs_fill_super);
1207 }
1208 
1209 static struct file_system_type hugetlbfs_fs_type = {
1210 	.name		= "hugetlbfs",
1211 	.mount		= hugetlbfs_mount,
1212 	.kill_sb	= kill_litter_super,
1213 };
1214 
1215 static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE];
1216 
1217 static int can_do_hugetlb_shm(void)
1218 {
1219 	kgid_t shm_group;
1220 	shm_group = make_kgid(&init_user_ns, sysctl_hugetlb_shm_group);
1221 	return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
1222 }
1223 
1224 static int get_hstate_idx(int page_size_log)
1225 {
1226 	struct hstate *h = hstate_sizelog(page_size_log);
1227 
1228 	if (!h)
1229 		return -1;
1230 	return h - hstates;
1231 }
1232 
1233 static const struct dentry_operations anon_ops = {
1234 	.d_dname = simple_dname
1235 };
1236 
1237 /*
1238  * Note that size should be aligned to proper hugepage size in caller side,
1239  * otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
1240  */
1241 struct file *hugetlb_file_setup(const char *name, size_t size,
1242 				vm_flags_t acctflag, struct user_struct **user,
1243 				int creat_flags, int page_size_log)
1244 {
1245 	struct file *file = ERR_PTR(-ENOMEM);
1246 	struct inode *inode;
1247 	struct path path;
1248 	struct super_block *sb;
1249 	struct qstr quick_string;
1250 	int hstate_idx;
1251 
1252 	hstate_idx = get_hstate_idx(page_size_log);
1253 	if (hstate_idx < 0)
1254 		return ERR_PTR(-ENODEV);
1255 
1256 	*user = NULL;
1257 	if (!hugetlbfs_vfsmount[hstate_idx])
1258 		return ERR_PTR(-ENOENT);
1259 
1260 	if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
1261 		*user = current_user();
1262 		if (user_shm_lock(size, *user)) {
1263 			task_lock(current);
1264 			pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is deprecated\n",
1265 				current->comm, current->pid);
1266 			task_unlock(current);
1267 		} else {
1268 			*user = NULL;
1269 			return ERR_PTR(-EPERM);
1270 		}
1271 	}
1272 
1273 	sb = hugetlbfs_vfsmount[hstate_idx]->mnt_sb;
1274 	quick_string.name = name;
1275 	quick_string.len = strlen(quick_string.name);
1276 	quick_string.hash = 0;
1277 	path.dentry = d_alloc_pseudo(sb, &quick_string);
1278 	if (!path.dentry)
1279 		goto out_shm_unlock;
1280 
1281 	d_set_d_op(path.dentry, &anon_ops);
1282 	path.mnt = mntget(hugetlbfs_vfsmount[hstate_idx]);
1283 	file = ERR_PTR(-ENOSPC);
1284 	inode = hugetlbfs_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0);
1285 	if (!inode)
1286 		goto out_dentry;
1287 	if (creat_flags == HUGETLB_SHMFS_INODE)
1288 		inode->i_flags |= S_PRIVATE;
1289 
1290 	file = ERR_PTR(-ENOMEM);
1291 	if (hugetlb_reserve_pages(inode, 0,
1292 			size >> huge_page_shift(hstate_inode(inode)), NULL,
1293 			acctflag))
1294 		goto out_inode;
1295 
1296 	d_instantiate(path.dentry, inode);
1297 	inode->i_size = size;
1298 	clear_nlink(inode);
1299 
1300 	file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
1301 			&hugetlbfs_file_operations);
1302 	if (IS_ERR(file))
1303 		goto out_dentry; /* inode is already attached */
1304 
1305 	return file;
1306 
1307 out_inode:
1308 	iput(inode);
1309 out_dentry:
1310 	path_put(&path);
1311 out_shm_unlock:
1312 	if (*user) {
1313 		user_shm_unlock(size, *user);
1314 		*user = NULL;
1315 	}
1316 	return file;
1317 }
1318 
1319 static int __init init_hugetlbfs_fs(void)
1320 {
1321 	struct hstate *h;
1322 	int error;
1323 	int i;
1324 
1325 	if (!hugepages_supported()) {
1326 		pr_info("disabling because there are no supported hugepage sizes\n");
1327 		return -ENOTSUPP;
1328 	}
1329 
1330 	error = -ENOMEM;
1331 	hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
1332 					sizeof(struct hugetlbfs_inode_info),
1333 					0, SLAB_ACCOUNT, init_once);
1334 	if (hugetlbfs_inode_cachep == NULL)
1335 		goto out2;
1336 
1337 	error = register_filesystem(&hugetlbfs_fs_type);
1338 	if (error)
1339 		goto out;
1340 
1341 	i = 0;
1342 	for_each_hstate(h) {
1343 		char buf[50];
1344 		unsigned ps_kb = 1U << (h->order + PAGE_SHIFT - 10);
1345 
1346 		snprintf(buf, sizeof(buf), "pagesize=%uK", ps_kb);
1347 		hugetlbfs_vfsmount[i] = kern_mount_data(&hugetlbfs_fs_type,
1348 							buf);
1349 
1350 		if (IS_ERR(hugetlbfs_vfsmount[i])) {
1351 			pr_err("Cannot mount internal hugetlbfs for "
1352 				"page size %uK", ps_kb);
1353 			error = PTR_ERR(hugetlbfs_vfsmount[i]);
1354 			hugetlbfs_vfsmount[i] = NULL;
1355 		}
1356 		i++;
1357 	}
1358 	/* Non default hstates are optional */
1359 	if (!IS_ERR_OR_NULL(hugetlbfs_vfsmount[default_hstate_idx]))
1360 		return 0;
1361 
1362  out:
1363 	kmem_cache_destroy(hugetlbfs_inode_cachep);
1364  out2:
1365 	return error;
1366 }
1367 fs_initcall(init_hugetlbfs_fs)
1368