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/falloc.h>
15#include <linux/fs.h>
16#include <linux/mount.h>
17#include <linux/file.h>
18#include <linux/kernel.h>
19#include <linux/writeback.h>
20#include <linux/pagemap.h>
21#include <linux/highmem.h>
22#include <linux/init.h>
23#include <linux/string.h>
24#include <linux/capability.h>
25#include <linux/ctype.h>
26#include <linux/backing-dev.h>
27#include <linux/hugetlb.h>
28#include <linux/pagevec.h>
29#include <linux/fs_parser.h>
30#include <linux/mman.h>
31#include <linux/slab.h>
32#include <linux/dnotify.h>
33#include <linux/statfs.h>
34#include <linux/security.h>
35#include <linux/magic.h>
36#include <linux/migrate.h>
37#include <linux/uio.h>
38
39#include <linux/uaccess.h>
40#include <linux/sched/mm.h>
41
42static const struct address_space_operations hugetlbfs_aops;
43const struct file_operations hugetlbfs_file_operations;
44static const struct inode_operations hugetlbfs_dir_inode_operations;
45static const struct inode_operations hugetlbfs_inode_operations;
46
47enum hugetlbfs_size_type { NO_SIZE, SIZE_STD, SIZE_PERCENT };
48
49struct hugetlbfs_fs_context {
50 struct hstate *hstate;
51 unsigned long long max_size_opt;
52 unsigned long long min_size_opt;
53 long max_hpages;
54 long nr_inodes;
55 long min_hpages;
56 enum hugetlbfs_size_type max_val_type;
57 enum hugetlbfs_size_type min_val_type;
58 kuid_t uid;
59 kgid_t gid;
60 umode_t mode;
61};
62
63int sysctl_hugetlb_shm_group;
64
65enum hugetlb_param {
66 Opt_gid,
67 Opt_min_size,
68 Opt_mode,
69 Opt_nr_inodes,
70 Opt_pagesize,
71 Opt_size,
72 Opt_uid,
73};
74
75static const struct fs_parameter_spec hugetlb_fs_parameters[] = {
76 fsparam_u32 ("gid", Opt_gid),
77 fsparam_string("min_size", Opt_min_size),
78 fsparam_u32oct("mode", Opt_mode),
79 fsparam_string("nr_inodes", Opt_nr_inodes),
80 fsparam_string("pagesize", Opt_pagesize),
81 fsparam_string("size", Opt_size),
82 fsparam_u32 ("uid", Opt_uid),
83 {}
84};
85
86/*
87 * Mask used when checking the page offset value passed in via system
88 * calls. This value will be converted to a loff_t which is signed.
89 * Therefore, we want to check the upper PAGE_SHIFT + 1 bits of the
90 * value. The extra bit (- 1 in the shift value) is to take the sign
91 * bit into account.
92 */
93#define PGOFF_LOFFT_MAX \
94 (((1UL << (PAGE_SHIFT + 1)) - 1) << (BITS_PER_LONG - (PAGE_SHIFT + 1)))
95
96static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
97{
98 struct inode *inode = file_inode(f: file);
99 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
100 loff_t len, vma_len;
101 int ret;
102 struct hstate *h = hstate_file(f: file);
103
104 /*
105 * vma address alignment (but not the pgoff alignment) has
106 * already been checked by prepare_hugepage_range. If you add
107 * any error returns here, do so after setting VM_HUGETLB, so
108 * is_vm_hugetlb_page tests below unmap_region go the right
109 * way when do_mmap unwinds (may be important on powerpc
110 * and ia64).
111 */
112 vm_flags_set(vma, VM_HUGETLB | VM_DONTEXPAND);
113 vma->vm_ops = &hugetlb_vm_ops;
114
115 ret = seal_check_write(seals: info->seals, vma);
116 if (ret)
117 return ret;
118
119 /*
120 * page based offset in vm_pgoff could be sufficiently large to
121 * overflow a loff_t when converted to byte offset. This can
122 * only happen on architectures where sizeof(loff_t) ==
123 * sizeof(unsigned long). So, only check in those instances.
124 */
125 if (sizeof(unsigned long) == sizeof(loff_t)) {
126 if (vma->vm_pgoff & PGOFF_LOFFT_MAX)
127 return -EINVAL;
128 }
129
130 /* must be huge page aligned */
131 if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))
132 return -EINVAL;
133
134 vma_len = (loff_t)(vma->vm_end - vma->vm_start);
135 len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
136 /* check for overflow */
137 if (len < vma_len)
138 return -EINVAL;
139
140 inode_lock(inode);
141 file_accessed(file);
142
143 ret = -ENOMEM;
144 if (!hugetlb_reserve_pages(inode,
145 from: vma->vm_pgoff >> huge_page_order(h),
146 to: len >> huge_page_shift(h), vma,
147 vm_flags: vma->vm_flags))
148 goto out;
149
150 ret = 0;
151 if (vma->vm_flags & VM_WRITE && inode->i_size < len)
152 i_size_write(inode, i_size: len);
153out:
154 inode_unlock(inode);
155
156 return ret;
157}
158
159/*
160 * Called under mmap_write_lock(mm).
161 */
162
163static unsigned long
164hugetlb_get_unmapped_area_bottomup(struct file *file, unsigned long addr,
165 unsigned long len, unsigned long pgoff, unsigned long flags)
166{
167 struct hstate *h = hstate_file(f: file);
168 struct vm_unmapped_area_info info;
169
170 info.flags = 0;
171 info.length = len;
172 info.low_limit = current->mm->mmap_base;
173 info.high_limit = arch_get_mmap_end(addr, len, flags);
174 info.align_mask = PAGE_MASK & ~huge_page_mask(h);
175 info.align_offset = 0;
176 return vm_unmapped_area(info: &info);
177}
178
179static unsigned long
180hugetlb_get_unmapped_area_topdown(struct file *file, unsigned long addr,
181 unsigned long len, unsigned long pgoff, unsigned long flags)
182{
183 struct hstate *h = hstate_file(f: file);
184 struct vm_unmapped_area_info info;
185
186 info.flags = VM_UNMAPPED_AREA_TOPDOWN;
187 info.length = len;
188 info.low_limit = PAGE_SIZE;
189 info.high_limit = arch_get_mmap_base(addr, current->mm->mmap_base);
190 info.align_mask = PAGE_MASK & ~huge_page_mask(h);
191 info.align_offset = 0;
192 addr = vm_unmapped_area(info: &info);
193
194 /*
195 * A failed mmap() very likely causes application failure,
196 * so fall back to the bottom-up function here. This scenario
197 * can happen with large stack limits and large mmap()
198 * allocations.
199 */
200 if (unlikely(offset_in_page(addr))) {
201 VM_BUG_ON(addr != -ENOMEM);
202 info.flags = 0;
203 info.low_limit = current->mm->mmap_base;
204 info.high_limit = arch_get_mmap_end(addr, len, flags);
205 addr = vm_unmapped_area(info: &info);
206 }
207
208 return addr;
209}
210
211unsigned long
212generic_hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
213 unsigned long len, unsigned long pgoff,
214 unsigned long flags)
215{
216 struct mm_struct *mm = current->mm;
217 struct vm_area_struct *vma;
218 struct hstate *h = hstate_file(f: file);
219 const unsigned long mmap_end = arch_get_mmap_end(addr, len, flags);
220
221 if (len & ~huge_page_mask(h))
222 return -EINVAL;
223 if (len > TASK_SIZE)
224 return -ENOMEM;
225
226 if (flags & MAP_FIXED) {
227 if (prepare_hugepage_range(file, addr, len))
228 return -EINVAL;
229 return addr;
230 }
231
232 if (addr) {
233 addr = ALIGN(addr, huge_page_size(h));
234 vma = find_vma(mm, addr);
235 if (mmap_end - len >= addr &&
236 (!vma || addr + len <= vm_start_gap(vma)))
237 return addr;
238 }
239
240 /*
241 * Use mm->get_unmapped_area value as a hint to use topdown routine.
242 * If architectures have special needs, they should define their own
243 * version of hugetlb_get_unmapped_area.
244 */
245 if (mm->get_unmapped_area == arch_get_unmapped_area_topdown)
246 return hugetlb_get_unmapped_area_topdown(file, addr, len,
247 pgoff, flags);
248 return hugetlb_get_unmapped_area_bottomup(file, addr, len,
249 pgoff, flags);
250}
251
252#ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
253static unsigned long
254hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
255 unsigned long len, unsigned long pgoff,
256 unsigned long flags)
257{
258 return generic_hugetlb_get_unmapped_area(file, addr, len, pgoff, flags);
259}
260#endif
261
262/*
263 * Someone wants to read @bytes from a HWPOISON hugetlb @page from @offset.
264 * Returns the maximum number of bytes one can read without touching the 1st raw
265 * HWPOISON subpage.
266 *
267 * The implementation borrows the iteration logic from copy_page_to_iter*.
268 */
269static size_t adjust_range_hwpoison(struct page *page, size_t offset, size_t bytes)
270{
271 size_t n = 0;
272 size_t res = 0;
273
274 /* First subpage to start the loop. */
275 page = nth_page(page, offset / PAGE_SIZE);
276 offset %= PAGE_SIZE;
277 while (1) {
278 if (is_raw_hwpoison_page_in_hugepage(page))
279 break;
280
281 /* Safe to read n bytes without touching HWPOISON subpage. */
282 n = min(bytes, (size_t)PAGE_SIZE - offset);
283 res += n;
284 bytes -= n;
285 if (!bytes || !n)
286 break;
287 offset += n;
288 if (offset == PAGE_SIZE) {
289 page = nth_page(page, 1);
290 offset = 0;
291 }
292 }
293
294 return res;
295}
296
297/*
298 * Support for read() - Find the page attached to f_mapping and copy out the
299 * data. This provides functionality similar to filemap_read().
300 */
301static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
302{
303 struct file *file = iocb->ki_filp;
304 struct hstate *h = hstate_file(f: file);
305 struct address_space *mapping = file->f_mapping;
306 struct inode *inode = mapping->host;
307 unsigned long index = iocb->ki_pos >> huge_page_shift(h);
308 unsigned long offset = iocb->ki_pos & ~huge_page_mask(h);
309 unsigned long end_index;
310 loff_t isize;
311 ssize_t retval = 0;
312
313 while (iov_iter_count(i: to)) {
314 struct folio *folio;
315 size_t nr, copied, want;
316
317 /* nr is the maximum number of bytes to copy from this page */
318 nr = huge_page_size(h);
319 isize = i_size_read(inode);
320 if (!isize)
321 break;
322 end_index = (isize - 1) >> huge_page_shift(h);
323 if (index > end_index)
324 break;
325 if (index == end_index) {
326 nr = ((isize - 1) & ~huge_page_mask(h)) + 1;
327 if (nr <= offset)
328 break;
329 }
330 nr = nr - offset;
331
332 /* Find the folio */
333 folio = filemap_lock_hugetlb_folio(h, mapping, idx: index);
334 if (IS_ERR(ptr: folio)) {
335 /*
336 * We have a HOLE, zero out the user-buffer for the
337 * length of the hole or request.
338 */
339 copied = iov_iter_zero(bytes: nr, to);
340 } else {
341 folio_unlock(folio);
342
343 if (!folio_test_has_hwpoisoned(folio))
344 want = nr;
345 else {
346 /*
347 * Adjust how many bytes safe to read without
348 * touching the 1st raw HWPOISON subpage after
349 * offset.
350 */
351 want = adjust_range_hwpoison(page: &folio->page, offset, bytes: nr);
352 if (want == 0) {
353 folio_put(folio);
354 retval = -EIO;
355 break;
356 }
357 }
358
359 /*
360 * We have the folio, copy it to user space buffer.
361 */
362 copied = copy_folio_to_iter(folio, offset, bytes: want, i: to);
363 folio_put(folio);
364 }
365 offset += copied;
366 retval += copied;
367 if (copied != nr && iov_iter_count(i: to)) {
368 if (!retval)
369 retval = -EFAULT;
370 break;
371 }
372 index += offset >> huge_page_shift(h);
373 offset &= ~huge_page_mask(h);
374 }
375 iocb->ki_pos = ((loff_t)index << huge_page_shift(h)) + offset;
376 return retval;
377}
378
379static int hugetlbfs_write_begin(struct file *file,
380 struct address_space *mapping,
381 loff_t pos, unsigned len,
382 struct page **pagep, void **fsdata)
383{
384 return -EINVAL;
385}
386
387static int hugetlbfs_write_end(struct file *file, struct address_space *mapping,
388 loff_t pos, unsigned len, unsigned copied,
389 struct page *page, void *fsdata)
390{
391 BUG();
392 return -EINVAL;
393}
394
395static void hugetlb_delete_from_page_cache(struct folio *folio)
396{
397 folio_clear_dirty(folio);
398 folio_clear_uptodate(folio);
399 filemap_remove_folio(folio);
400}
401
402/*
403 * Called with i_mmap_rwsem held for inode based vma maps. This makes
404 * sure vma (and vm_mm) will not go away. We also hold the hugetlb fault
405 * mutex for the page in the mapping. So, we can not race with page being
406 * faulted into the vma.
407 */
408static bool hugetlb_vma_maps_page(struct vm_area_struct *vma,
409 unsigned long addr, struct page *page)
410{
411 pte_t *ptep, pte;
412
413 ptep = hugetlb_walk(vma, addr, sz: huge_page_size(h: hstate_vma(vma)));
414 if (!ptep)
415 return false;
416
417 pte = huge_ptep_get(ptep);
418 if (huge_pte_none(pte) || !pte_present(a: pte))
419 return false;
420
421 if (pte_page(pte) == page)
422 return true;
423
424 return false;
425}
426
427/*
428 * Can vma_offset_start/vma_offset_end overflow on 32-bit arches?
429 * No, because the interval tree returns us only those vmas
430 * which overlap the truncated area starting at pgoff,
431 * and no vma on a 32-bit arch can span beyond the 4GB.
432 */
433static unsigned long vma_offset_start(struct vm_area_struct *vma, pgoff_t start)
434{
435 unsigned long offset = 0;
436
437 if (vma->vm_pgoff < start)
438 offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
439
440 return vma->vm_start + offset;
441}
442
443static unsigned long vma_offset_end(struct vm_area_struct *vma, pgoff_t end)
444{
445 unsigned long t_end;
446
447 if (!end)
448 return vma->vm_end;
449
450 t_end = ((end - vma->vm_pgoff) << PAGE_SHIFT) + vma->vm_start;
451 if (t_end > vma->vm_end)
452 t_end = vma->vm_end;
453 return t_end;
454}
455
456/*
457 * Called with hugetlb fault mutex held. Therefore, no more mappings to
458 * this folio can be created while executing the routine.
459 */
460static void hugetlb_unmap_file_folio(struct hstate *h,
461 struct address_space *mapping,
462 struct folio *folio, pgoff_t index)
463{
464 struct rb_root_cached *root = &mapping->i_mmap;
465 struct hugetlb_vma_lock *vma_lock;
466 struct page *page = &folio->page;
467 struct vm_area_struct *vma;
468 unsigned long v_start;
469 unsigned long v_end;
470 pgoff_t start, end;
471
472 start = index * pages_per_huge_page(h);
473 end = (index + 1) * pages_per_huge_page(h);
474
475 i_mmap_lock_write(mapping);
476retry:
477 vma_lock = NULL;
478 vma_interval_tree_foreach(vma, root, start, end - 1) {
479 v_start = vma_offset_start(vma, start);
480 v_end = vma_offset_end(vma, end);
481
482 if (!hugetlb_vma_maps_page(vma, addr: v_start, page))
483 continue;
484
485 if (!hugetlb_vma_trylock_write(vma)) {
486 vma_lock = vma->vm_private_data;
487 /*
488 * If we can not get vma lock, we need to drop
489 * immap_sema and take locks in order. First,
490 * take a ref on the vma_lock structure so that
491 * we can be guaranteed it will not go away when
492 * dropping immap_sema.
493 */
494 kref_get(kref: &vma_lock->refs);
495 break;
496 }
497
498 unmap_hugepage_range(vma, v_start, v_end, NULL,
499 ZAP_FLAG_DROP_MARKER);
500 hugetlb_vma_unlock_write(vma);
501 }
502
503 i_mmap_unlock_write(mapping);
504
505 if (vma_lock) {
506 /*
507 * Wait on vma_lock. We know it is still valid as we have
508 * a reference. We must 'open code' vma locking as we do
509 * not know if vma_lock is still attached to vma.
510 */
511 down_write(sem: &vma_lock->rw_sema);
512 i_mmap_lock_write(mapping);
513
514 vma = vma_lock->vma;
515 if (!vma) {
516 /*
517 * If lock is no longer attached to vma, then just
518 * unlock, drop our reference and retry looking for
519 * other vmas.
520 */
521 up_write(sem: &vma_lock->rw_sema);
522 kref_put(kref: &vma_lock->refs, release: hugetlb_vma_lock_release);
523 goto retry;
524 }
525
526 /*
527 * vma_lock is still attached to vma. Check to see if vma
528 * still maps page and if so, unmap.
529 */
530 v_start = vma_offset_start(vma, start);
531 v_end = vma_offset_end(vma, end);
532 if (hugetlb_vma_maps_page(vma, addr: v_start, page))
533 unmap_hugepage_range(vma, v_start, v_end, NULL,
534 ZAP_FLAG_DROP_MARKER);
535
536 kref_put(kref: &vma_lock->refs, release: hugetlb_vma_lock_release);
537 hugetlb_vma_unlock_write(vma);
538
539 goto retry;
540 }
541}
542
543static void
544hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end,
545 zap_flags_t zap_flags)
546{
547 struct vm_area_struct *vma;
548
549 /*
550 * end == 0 indicates that the entire range after start should be
551 * unmapped. Note, end is exclusive, whereas the interval tree takes
552 * an inclusive "last".
553 */
554 vma_interval_tree_foreach(vma, root, start, end ? end - 1 : ULONG_MAX) {
555 unsigned long v_start;
556 unsigned long v_end;
557
558 if (!hugetlb_vma_trylock_write(vma))
559 continue;
560
561 v_start = vma_offset_start(vma, start);
562 v_end = vma_offset_end(vma, end);
563
564 unmap_hugepage_range(vma, v_start, v_end, NULL, zap_flags);
565
566 /*
567 * Note that vma lock only exists for shared/non-private
568 * vmas. Therefore, lock is not held when calling
569 * unmap_hugepage_range for private vmas.
570 */
571 hugetlb_vma_unlock_write(vma);
572 }
573}
574
575/*
576 * Called with hugetlb fault mutex held.
577 * Returns true if page was actually removed, false otherwise.
578 */
579static bool remove_inode_single_folio(struct hstate *h, struct inode *inode,
580 struct address_space *mapping,
581 struct folio *folio, pgoff_t index,
582 bool truncate_op)
583{
584 bool ret = false;
585
586 /*
587 * If folio is mapped, it was faulted in after being
588 * unmapped in caller. Unmap (again) while holding
589 * the fault mutex. The mutex will prevent faults
590 * until we finish removing the folio.
591 */
592 if (unlikely(folio_mapped(folio)))
593 hugetlb_unmap_file_folio(h, mapping, folio, index);
594
595 folio_lock(folio);
596 /*
597 * We must remove the folio from page cache before removing
598 * the region/ reserve map (hugetlb_unreserve_pages). In
599 * rare out of memory conditions, removal of the region/reserve
600 * map could fail. Correspondingly, the subpool and global
601 * reserve usage count can need to be adjusted.
602 */
603 VM_BUG_ON_FOLIO(folio_test_hugetlb_restore_reserve(folio), folio);
604 hugetlb_delete_from_page_cache(folio);
605 ret = true;
606 if (!truncate_op) {
607 if (unlikely(hugetlb_unreserve_pages(inode, index,
608 index + 1, 1)))
609 hugetlb_fix_reserve_counts(inode);
610 }
611
612 folio_unlock(folio);
613 return ret;
614}
615
616/*
617 * remove_inode_hugepages handles two distinct cases: truncation and hole
618 * punch. There are subtle differences in operation for each case.
619 *
620 * truncation is indicated by end of range being LLONG_MAX
621 * In this case, we first scan the range and release found pages.
622 * After releasing pages, hugetlb_unreserve_pages cleans up region/reserve
623 * maps and global counts. Page faults can race with truncation.
624 * During faults, hugetlb_no_page() checks i_size before page allocation,
625 * and again after obtaining page table lock. It will 'back out'
626 * allocations in the truncated range.
627 * hole punch is indicated if end is not LLONG_MAX
628 * In the hole punch case we scan the range and release found pages.
629 * Only when releasing a page is the associated region/reserve map
630 * deleted. The region/reserve map for ranges without associated
631 * pages are not modified. Page faults can race with hole punch.
632 * This is indicated if we find a mapped page.
633 * Note: If the passed end of range value is beyond the end of file, but
634 * not LLONG_MAX this routine still performs a hole punch operation.
635 */
636static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
637 loff_t lend)
638{
639 struct hstate *h = hstate_inode(i: inode);
640 struct address_space *mapping = &inode->i_data;
641 const pgoff_t end = lend >> PAGE_SHIFT;
642 struct folio_batch fbatch;
643 pgoff_t next, index;
644 int i, freed = 0;
645 bool truncate_op = (lend == LLONG_MAX);
646
647 folio_batch_init(fbatch: &fbatch);
648 next = lstart >> PAGE_SHIFT;
649 while (filemap_get_folios(mapping, start: &next, end: end - 1, fbatch: &fbatch)) {
650 for (i = 0; i < folio_batch_count(fbatch: &fbatch); ++i) {
651 struct folio *folio = fbatch.folios[i];
652 u32 hash = 0;
653
654 index = folio->index >> huge_page_order(h);
655 hash = hugetlb_fault_mutex_hash(mapping, idx: index);
656 mutex_lock(&hugetlb_fault_mutex_table[hash]);
657
658 /*
659 * Remove folio that was part of folio_batch.
660 */
661 if (remove_inode_single_folio(h, inode, mapping, folio,
662 index, truncate_op))
663 freed++;
664
665 mutex_unlock(lock: &hugetlb_fault_mutex_table[hash]);
666 }
667 folio_batch_release(fbatch: &fbatch);
668 cond_resched();
669 }
670
671 if (truncate_op)
672 (void)hugetlb_unreserve_pages(inode,
673 start: lstart >> huge_page_shift(h),
674 LONG_MAX, freed);
675}
676
677static void hugetlbfs_evict_inode(struct inode *inode)
678{
679 struct resv_map *resv_map;
680
681 remove_inode_hugepages(inode, lstart: 0, LLONG_MAX);
682
683 /*
684 * Get the resv_map from the address space embedded in the inode.
685 * This is the address space which points to any resv_map allocated
686 * at inode creation time. If this is a device special inode,
687 * i_mapping may not point to the original address space.
688 */
689 resv_map = (struct resv_map *)(&inode->i_data)->private_data;
690 /* Only regular and link inodes have associated reserve maps */
691 if (resv_map)
692 resv_map_release(ref: &resv_map->refs);
693 clear_inode(inode);
694}
695
696static void hugetlb_vmtruncate(struct inode *inode, loff_t offset)
697{
698 pgoff_t pgoff;
699 struct address_space *mapping = inode->i_mapping;
700 struct hstate *h = hstate_inode(i: inode);
701
702 BUG_ON(offset & ~huge_page_mask(h));
703 pgoff = offset >> PAGE_SHIFT;
704
705 i_size_write(inode, i_size: offset);
706 i_mmap_lock_write(mapping);
707 if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
708 hugetlb_vmdelete_list(root: &mapping->i_mmap, start: pgoff, end: 0,
709 ZAP_FLAG_DROP_MARKER);
710 i_mmap_unlock_write(mapping);
711 remove_inode_hugepages(inode, lstart: offset, LLONG_MAX);
712}
713
714static void hugetlbfs_zero_partial_page(struct hstate *h,
715 struct address_space *mapping,
716 loff_t start,
717 loff_t end)
718{
719 pgoff_t idx = start >> huge_page_shift(h);
720 struct folio *folio;
721
722 folio = filemap_lock_hugetlb_folio(h, mapping, idx);
723 if (IS_ERR(ptr: folio))
724 return;
725
726 start = start & ~huge_page_mask(h);
727 end = end & ~huge_page_mask(h);
728 if (!end)
729 end = huge_page_size(h);
730
731 folio_zero_segment(folio, start: (size_t)start, xend: (size_t)end);
732
733 folio_unlock(folio);
734 folio_put(folio);
735}
736
737static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
738{
739 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
740 struct address_space *mapping = inode->i_mapping;
741 struct hstate *h = hstate_inode(i: inode);
742 loff_t hpage_size = huge_page_size(h);
743 loff_t hole_start, hole_end;
744
745 /*
746 * hole_start and hole_end indicate the full pages within the hole.
747 */
748 hole_start = round_up(offset, hpage_size);
749 hole_end = round_down(offset + len, hpage_size);
750
751 inode_lock(inode);
752
753 /* protected by i_rwsem */
754 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
755 inode_unlock(inode);
756 return -EPERM;
757 }
758
759 i_mmap_lock_write(mapping);
760
761 /* If range starts before first full page, zero partial page. */
762 if (offset < hole_start)
763 hugetlbfs_zero_partial_page(h, mapping,
764 start: offset, min(offset + len, hole_start));
765
766 /* Unmap users of full pages in the hole. */
767 if (hole_end > hole_start) {
768 if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
769 hugetlb_vmdelete_list(root: &mapping->i_mmap,
770 start: hole_start >> PAGE_SHIFT,
771 end: hole_end >> PAGE_SHIFT, zap_flags: 0);
772 }
773
774 /* If range extends beyond last full page, zero partial page. */
775 if ((offset + len) > hole_end && (offset + len) > hole_start)
776 hugetlbfs_zero_partial_page(h, mapping,
777 start: hole_end, end: offset + len);
778
779 i_mmap_unlock_write(mapping);
780
781 /* Remove full pages from the file. */
782 if (hole_end > hole_start)
783 remove_inode_hugepages(inode, lstart: hole_start, lend: hole_end);
784
785 inode_unlock(inode);
786
787 return 0;
788}
789
790static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
791 loff_t len)
792{
793 struct inode *inode = file_inode(f: file);
794 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
795 struct address_space *mapping = inode->i_mapping;
796 struct hstate *h = hstate_inode(i: inode);
797 struct vm_area_struct pseudo_vma;
798 struct mm_struct *mm = current->mm;
799 loff_t hpage_size = huge_page_size(h);
800 unsigned long hpage_shift = huge_page_shift(h);
801 pgoff_t start, index, end;
802 int error;
803 u32 hash;
804
805 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
806 return -EOPNOTSUPP;
807
808 if (mode & FALLOC_FL_PUNCH_HOLE)
809 return hugetlbfs_punch_hole(inode, offset, len);
810
811 /*
812 * Default preallocate case.
813 * For this range, start is rounded down and end is rounded up
814 * as well as being converted to page offsets.
815 */
816 start = offset >> hpage_shift;
817 end = (offset + len + hpage_size - 1) >> hpage_shift;
818
819 inode_lock(inode);
820
821 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
822 error = inode_newsize_ok(inode, offset: offset + len);
823 if (error)
824 goto out;
825
826 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
827 error = -EPERM;
828 goto out;
829 }
830
831 /*
832 * Initialize a pseudo vma as this is required by the huge page
833 * allocation routines.
834 */
835 vma_init(vma: &pseudo_vma, mm);
836 vm_flags_init(vma: &pseudo_vma, VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
837 pseudo_vma.vm_file = file;
838
839 for (index = start; index < end; index++) {
840 /*
841 * This is supposed to be the vaddr where the page is being
842 * faulted in, but we have no vaddr here.
843 */
844 struct folio *folio;
845 unsigned long addr;
846
847 cond_resched();
848
849 /*
850 * fallocate(2) manpage permits EINTR; we may have been
851 * interrupted because we are using up too much memory.
852 */
853 if (signal_pending(current)) {
854 error = -EINTR;
855 break;
856 }
857
858 /* addr is the offset within the file (zero based) */
859 addr = index * hpage_size;
860
861 /* mutex taken here, fault path and hole punch */
862 hash = hugetlb_fault_mutex_hash(mapping, idx: index);
863 mutex_lock(&hugetlb_fault_mutex_table[hash]);
864
865 /* See if already present in mapping to avoid alloc/free */
866 folio = filemap_get_folio(mapping, index: index << huge_page_order(h));
867 if (!IS_ERR(ptr: folio)) {
868 folio_put(folio);
869 mutex_unlock(lock: &hugetlb_fault_mutex_table[hash]);
870 continue;
871 }
872
873 /*
874 * Allocate folio without setting the avoid_reserve argument.
875 * There certainly are no reserves associated with the
876 * pseudo_vma. However, there could be shared mappings with
877 * reserves for the file at the inode level. If we fallocate
878 * folios in these areas, we need to consume the reserves
879 * to keep reservation accounting consistent.
880 */
881 folio = alloc_hugetlb_folio(vma: &pseudo_vma, addr, avoid_reserve: 0);
882 if (IS_ERR(ptr: folio)) {
883 mutex_unlock(lock: &hugetlb_fault_mutex_table[hash]);
884 error = PTR_ERR(ptr: folio);
885 goto out;
886 }
887 clear_huge_page(page: &folio->page, addr_hint: addr, pages_per_huge_page: pages_per_huge_page(h));
888 __folio_mark_uptodate(folio);
889 error = hugetlb_add_to_page_cache(folio, mapping, idx: index);
890 if (unlikely(error)) {
891 restore_reserve_on_error(h, vma: &pseudo_vma, address: addr, folio);
892 folio_put(folio);
893 mutex_unlock(lock: &hugetlb_fault_mutex_table[hash]);
894 goto out;
895 }
896
897 mutex_unlock(lock: &hugetlb_fault_mutex_table[hash]);
898
899 folio_set_hugetlb_migratable(folio);
900 /*
901 * folio_unlock because locked by hugetlb_add_to_page_cache()
902 * folio_put() due to reference from alloc_hugetlb_folio()
903 */
904 folio_unlock(folio);
905 folio_put(folio);
906 }
907
908 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
909 i_size_write(inode, i_size: offset + len);
910 inode_set_ctime_current(inode);
911out:
912 inode_unlock(inode);
913 return error;
914}
915
916static int hugetlbfs_setattr(struct mnt_idmap *idmap,
917 struct dentry *dentry, struct iattr *attr)
918{
919 struct inode *inode = d_inode(dentry);
920 struct hstate *h = hstate_inode(i: inode);
921 int error;
922 unsigned int ia_valid = attr->ia_valid;
923 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
924
925 error = setattr_prepare(&nop_mnt_idmap, dentry, attr);
926 if (error)
927 return error;
928
929 if (ia_valid & ATTR_SIZE) {
930 loff_t oldsize = inode->i_size;
931 loff_t newsize = attr->ia_size;
932
933 if (newsize & ~huge_page_mask(h))
934 return -EINVAL;
935 /* protected by i_rwsem */
936 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
937 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
938 return -EPERM;
939 hugetlb_vmtruncate(inode, offset: newsize);
940 }
941
942 setattr_copy(&nop_mnt_idmap, inode, attr);
943 mark_inode_dirty(inode);
944 return 0;
945}
946
947static struct inode *hugetlbfs_get_root(struct super_block *sb,
948 struct hugetlbfs_fs_context *ctx)
949{
950 struct inode *inode;
951
952 inode = new_inode(sb);
953 if (inode) {
954 inode->i_ino = get_next_ino();
955 inode->i_mode = S_IFDIR | ctx->mode;
956 inode->i_uid = ctx->uid;
957 inode->i_gid = ctx->gid;
958 simple_inode_init_ts(inode);
959 inode->i_op = &hugetlbfs_dir_inode_operations;
960 inode->i_fop = &simple_dir_operations;
961 /* directory inodes start off with i_nlink == 2 (for "." entry) */
962 inc_nlink(inode);
963 lockdep_annotate_inode_mutex_key(inode);
964 }
965 return inode;
966}
967
968/*
969 * Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
970 * be taken from reclaim -- unlike regular filesystems. This needs an
971 * annotation because huge_pmd_share() does an allocation under hugetlb's
972 * i_mmap_rwsem.
973 */
974static struct lock_class_key hugetlbfs_i_mmap_rwsem_key;
975
976static struct inode *hugetlbfs_get_inode(struct super_block *sb,
977 struct inode *dir,
978 umode_t mode, dev_t dev)
979{
980 struct inode *inode;
981 struct resv_map *resv_map = NULL;
982
983 /*
984 * Reserve maps are only needed for inodes that can have associated
985 * page allocations.
986 */
987 if (S_ISREG(mode) || S_ISLNK(mode)) {
988 resv_map = resv_map_alloc();
989 if (!resv_map)
990 return NULL;
991 }
992
993 inode = new_inode(sb);
994 if (inode) {
995 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
996
997 inode->i_ino = get_next_ino();
998 inode_init_owner(idmap: &nop_mnt_idmap, inode, dir, mode);
999 lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
1000 &hugetlbfs_i_mmap_rwsem_key);
1001 inode->i_mapping->a_ops = &hugetlbfs_aops;
1002 simple_inode_init_ts(inode);
1003 inode->i_mapping->private_data = resv_map;
1004 info->seals = F_SEAL_SEAL;
1005 switch (mode & S_IFMT) {
1006 default:
1007 init_special_inode(inode, mode, dev);
1008 break;
1009 case S_IFREG:
1010 inode->i_op = &hugetlbfs_inode_operations;
1011 inode->i_fop = &hugetlbfs_file_operations;
1012 break;
1013 case S_IFDIR:
1014 inode->i_op = &hugetlbfs_dir_inode_operations;
1015 inode->i_fop = &simple_dir_operations;
1016
1017 /* directory inodes start off with i_nlink == 2 (for "." entry) */
1018 inc_nlink(inode);
1019 break;
1020 case S_IFLNK:
1021 inode->i_op = &page_symlink_inode_operations;
1022 inode_nohighmem(inode);
1023 break;
1024 }
1025 lockdep_annotate_inode_mutex_key(inode);
1026 } else {
1027 if (resv_map)
1028 kref_put(kref: &resv_map->refs, release: resv_map_release);
1029 }
1030
1031 return inode;
1032}
1033
1034/*
1035 * File creation. Allocate an inode, and we're done..
1036 */
1037static int hugetlbfs_mknod(struct mnt_idmap *idmap, struct inode *dir,
1038 struct dentry *dentry, umode_t mode, dev_t dev)
1039{
1040 struct inode *inode;
1041
1042 inode = hugetlbfs_get_inode(sb: dir->i_sb, dir, mode, dev);
1043 if (!inode)
1044 return -ENOSPC;
1045 inode_set_mtime_to_ts(inode: dir, ts: inode_set_ctime_current(inode: dir));
1046 d_instantiate(dentry, inode);
1047 dget(dentry);/* Extra count - pin the dentry in core */
1048 return 0;
1049}
1050
1051static int hugetlbfs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
1052 struct dentry *dentry, umode_t mode)
1053{
1054 int retval = hugetlbfs_mknod(idmap: &nop_mnt_idmap, dir, dentry,
1055 mode: mode | S_IFDIR, dev: 0);
1056 if (!retval)
1057 inc_nlink(inode: dir);
1058 return retval;
1059}
1060
1061static int hugetlbfs_create(struct mnt_idmap *idmap,
1062 struct inode *dir, struct dentry *dentry,
1063 umode_t mode, bool excl)
1064{
1065 return hugetlbfs_mknod(idmap: &nop_mnt_idmap, dir, dentry, mode: mode | S_IFREG, dev: 0);
1066}
1067
1068static int hugetlbfs_tmpfile(struct mnt_idmap *idmap,
1069 struct inode *dir, struct file *file,
1070 umode_t mode)
1071{
1072 struct inode *inode;
1073
1074 inode = hugetlbfs_get_inode(sb: dir->i_sb, dir, mode: mode | S_IFREG, dev: 0);
1075 if (!inode)
1076 return -ENOSPC;
1077 inode_set_mtime_to_ts(inode: dir, ts: inode_set_ctime_current(inode: dir));
1078 d_tmpfile(file, inode);
1079 return finish_open_simple(file, error: 0);
1080}
1081
1082static int hugetlbfs_symlink(struct mnt_idmap *idmap,
1083 struct inode *dir, struct dentry *dentry,
1084 const char *symname)
1085{
1086 struct inode *inode;
1087 int error = -ENOSPC;
1088
1089 inode = hugetlbfs_get_inode(sb: dir->i_sb, dir, S_IFLNK|S_IRWXUGO, dev: 0);
1090 if (inode) {
1091 int l = strlen(symname)+1;
1092 error = page_symlink(inode, symname, len: l);
1093 if (!error) {
1094 d_instantiate(dentry, inode);
1095 dget(dentry);
1096 } else
1097 iput(inode);
1098 }
1099 inode_set_mtime_to_ts(inode: dir, ts: inode_set_ctime_current(inode: dir));
1100
1101 return error;
1102}
1103
1104#ifdef CONFIG_MIGRATION
1105static int hugetlbfs_migrate_folio(struct address_space *mapping,
1106 struct folio *dst, struct folio *src,
1107 enum migrate_mode mode)
1108{
1109 int rc;
1110
1111 rc = migrate_huge_page_move_mapping(mapping, dst, src);
1112 if (rc != MIGRATEPAGE_SUCCESS)
1113 return rc;
1114
1115 if (hugetlb_folio_subpool(folio: src)) {
1116 hugetlb_set_folio_subpool(folio: dst,
1117 subpool: hugetlb_folio_subpool(folio: src));
1118 hugetlb_set_folio_subpool(folio: src, NULL);
1119 }
1120
1121 if (mode != MIGRATE_SYNC_NO_COPY)
1122 folio_migrate_copy(newfolio: dst, folio: src);
1123 else
1124 folio_migrate_flags(newfolio: dst, folio: src);
1125
1126 return MIGRATEPAGE_SUCCESS;
1127}
1128#else
1129#define hugetlbfs_migrate_folio NULL
1130#endif
1131
1132static int hugetlbfs_error_remove_page(struct address_space *mapping,
1133 struct page *page)
1134{
1135 return 0;
1136}
1137
1138/*
1139 * Display the mount options in /proc/mounts.
1140 */
1141static int hugetlbfs_show_options(struct seq_file *m, struct dentry *root)
1142{
1143 struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb: root->d_sb);
1144 struct hugepage_subpool *spool = sbinfo->spool;
1145 unsigned long hpage_size = huge_page_size(h: sbinfo->hstate);
1146 unsigned hpage_shift = huge_page_shift(h: sbinfo->hstate);
1147 char mod;
1148
1149 if (!uid_eq(left: sbinfo->uid, GLOBAL_ROOT_UID))
1150 seq_printf(m, ",uid=%u",
1151 from_kuid_munged(&init_user_ns, sbinfo->uid));
1152 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
1153 seq_printf(m, ",gid=%u",
1154 from_kgid_munged(&init_user_ns, sbinfo->gid));
1155 if (sbinfo->mode != 0755)
1156 seq_printf(m, ",mode=%o", sbinfo->mode);
1157 if (sbinfo->max_inodes != -1)
1158 seq_printf(m, ",nr_inodes=%lu", sbinfo->max_inodes);
1159
1160 hpage_size /= 1024;
1161 mod = 'K';
1162 if (hpage_size >= 1024) {
1163 hpage_size /= 1024;
1164 mod = 'M';
1165 }
1166 seq_printf(m, ",pagesize=%lu%c", hpage_size, mod);
1167 if (spool) {
1168 if (spool->max_hpages != -1)
1169 seq_printf(m, ",size=%llu",
1170 (unsigned long long)spool->max_hpages << hpage_shift);
1171 if (spool->min_hpages != -1)
1172 seq_printf(m, ",min_size=%llu",
1173 (unsigned long long)spool->min_hpages << hpage_shift);
1174 }
1175 return 0;
1176}
1177
1178static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
1179{
1180 struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb: dentry->d_sb);
1181 struct hstate *h = hstate_inode(i: d_inode(dentry));
1182 u64 id = huge_encode_dev(dev: dentry->d_sb->s_dev);
1183
1184 buf->f_fsid = u64_to_fsid(v: id);
1185 buf->f_type = HUGETLBFS_MAGIC;
1186 buf->f_bsize = huge_page_size(h);
1187 if (sbinfo) {
1188 spin_lock(lock: &sbinfo->stat_lock);
1189 /* If no limits set, just report 0 or -1 for max/free/used
1190 * blocks, like simple_statfs() */
1191 if (sbinfo->spool) {
1192 long free_pages;
1193
1194 spin_lock_irq(lock: &sbinfo->spool->lock);
1195 buf->f_blocks = sbinfo->spool->max_hpages;
1196 free_pages = sbinfo->spool->max_hpages
1197 - sbinfo->spool->used_hpages;
1198 buf->f_bavail = buf->f_bfree = free_pages;
1199 spin_unlock_irq(lock: &sbinfo->spool->lock);
1200 buf->f_files = sbinfo->max_inodes;
1201 buf->f_ffree = sbinfo->free_inodes;
1202 }
1203 spin_unlock(lock: &sbinfo->stat_lock);
1204 }
1205 buf->f_namelen = NAME_MAX;
1206 return 0;
1207}
1208
1209static void hugetlbfs_put_super(struct super_block *sb)
1210{
1211 struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
1212
1213 if (sbi) {
1214 sb->s_fs_info = NULL;
1215
1216 if (sbi->spool)
1217 hugepage_put_subpool(spool: sbi->spool);
1218
1219 kfree(objp: sbi);
1220 }
1221}
1222
1223static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1224{
1225 if (sbinfo->free_inodes >= 0) {
1226 spin_lock(lock: &sbinfo->stat_lock);
1227 if (unlikely(!sbinfo->free_inodes)) {
1228 spin_unlock(lock: &sbinfo->stat_lock);
1229 return 0;
1230 }
1231 sbinfo->free_inodes--;
1232 spin_unlock(lock: &sbinfo->stat_lock);
1233 }
1234
1235 return 1;
1236}
1237
1238static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1239{
1240 if (sbinfo->free_inodes >= 0) {
1241 spin_lock(lock: &sbinfo->stat_lock);
1242 sbinfo->free_inodes++;
1243 spin_unlock(lock: &sbinfo->stat_lock);
1244 }
1245}
1246
1247
1248static struct kmem_cache *hugetlbfs_inode_cachep;
1249
1250static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
1251{
1252 struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
1253 struct hugetlbfs_inode_info *p;
1254
1255 if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
1256 return NULL;
1257 p = alloc_inode_sb(sb, cache: hugetlbfs_inode_cachep, GFP_KERNEL);
1258 if (unlikely(!p)) {
1259 hugetlbfs_inc_free_inodes(sbinfo);
1260 return NULL;
1261 }
1262 return &p->vfs_inode;
1263}
1264
1265static void hugetlbfs_free_inode(struct inode *inode)
1266{
1267 kmem_cache_free(s: hugetlbfs_inode_cachep, objp: HUGETLBFS_I(inode));
1268}
1269
1270static void hugetlbfs_destroy_inode(struct inode *inode)
1271{
1272 hugetlbfs_inc_free_inodes(sbinfo: HUGETLBFS_SB(sb: inode->i_sb));
1273}
1274
1275static const struct address_space_operations hugetlbfs_aops = {
1276 .write_begin = hugetlbfs_write_begin,
1277 .write_end = hugetlbfs_write_end,
1278 .dirty_folio = noop_dirty_folio,
1279 .migrate_folio = hugetlbfs_migrate_folio,
1280 .error_remove_page = hugetlbfs_error_remove_page,
1281};
1282
1283
1284static void init_once(void *foo)
1285{
1286 struct hugetlbfs_inode_info *ei = foo;
1287
1288 inode_init_once(&ei->vfs_inode);
1289}
1290
1291const struct file_operations hugetlbfs_file_operations = {
1292 .read_iter = hugetlbfs_read_iter,
1293 .mmap = hugetlbfs_file_mmap,
1294 .fsync = noop_fsync,
1295 .get_unmapped_area = hugetlb_get_unmapped_area,
1296 .llseek = default_llseek,
1297 .fallocate = hugetlbfs_fallocate,
1298};
1299
1300static const struct inode_operations hugetlbfs_dir_inode_operations = {
1301 .create = hugetlbfs_create,
1302 .lookup = simple_lookup,
1303 .link = simple_link,
1304 .unlink = simple_unlink,
1305 .symlink = hugetlbfs_symlink,
1306 .mkdir = hugetlbfs_mkdir,
1307 .rmdir = simple_rmdir,
1308 .mknod = hugetlbfs_mknod,
1309 .rename = simple_rename,
1310 .setattr = hugetlbfs_setattr,
1311 .tmpfile = hugetlbfs_tmpfile,
1312};
1313
1314static const struct inode_operations hugetlbfs_inode_operations = {
1315 .setattr = hugetlbfs_setattr,
1316};
1317
1318static const struct super_operations hugetlbfs_ops = {
1319 .alloc_inode = hugetlbfs_alloc_inode,
1320 .free_inode = hugetlbfs_free_inode,
1321 .destroy_inode = hugetlbfs_destroy_inode,
1322 .evict_inode = hugetlbfs_evict_inode,
1323 .statfs = hugetlbfs_statfs,
1324 .put_super = hugetlbfs_put_super,
1325 .show_options = hugetlbfs_show_options,
1326};
1327
1328/*
1329 * Convert size option passed from command line to number of huge pages
1330 * in the pool specified by hstate. Size option could be in bytes
1331 * (val_type == SIZE_STD) or percentage of the pool (val_type == SIZE_PERCENT).
1332 */
1333static long
1334hugetlbfs_size_to_hpages(struct hstate *h, unsigned long long size_opt,
1335 enum hugetlbfs_size_type val_type)
1336{
1337 if (val_type == NO_SIZE)
1338 return -1;
1339
1340 if (val_type == SIZE_PERCENT) {
1341 size_opt <<= huge_page_shift(h);
1342 size_opt *= h->max_huge_pages;
1343 do_div(size_opt, 100);
1344 }
1345
1346 size_opt >>= huge_page_shift(h);
1347 return size_opt;
1348}
1349
1350/*
1351 * Parse one mount parameter.
1352 */
1353static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
1354{
1355 struct hugetlbfs_fs_context *ctx = fc->fs_private;
1356 struct fs_parse_result result;
1357 char *rest;
1358 unsigned long ps;
1359 int opt;
1360
1361 opt = fs_parse(fc, desc: hugetlb_fs_parameters, param, result: &result);
1362 if (opt < 0)
1363 return opt;
1364
1365 switch (opt) {
1366 case Opt_uid:
1367 ctx->uid = make_kuid(current_user_ns(), uid: result.uint_32);
1368 if (!uid_valid(uid: ctx->uid))
1369 goto bad_val;
1370 return 0;
1371
1372 case Opt_gid:
1373 ctx->gid = make_kgid(current_user_ns(), gid: result.uint_32);
1374 if (!gid_valid(gid: ctx->gid))
1375 goto bad_val;
1376 return 0;
1377
1378 case Opt_mode:
1379 ctx->mode = result.uint_32 & 01777U;
1380 return 0;
1381
1382 case Opt_size:
1383 /* memparse() will accept a K/M/G without a digit */
1384 if (!param->string || !isdigit(c: param->string[0]))
1385 goto bad_val;
1386 ctx->max_size_opt = memparse(ptr: param->string, retptr: &rest);
1387 ctx->max_val_type = SIZE_STD;
1388 if (*rest == '%')
1389 ctx->max_val_type = SIZE_PERCENT;
1390 return 0;
1391
1392 case Opt_nr_inodes:
1393 /* memparse() will accept a K/M/G without a digit */
1394 if (!param->string || !isdigit(c: param->string[0]))
1395 goto bad_val;
1396 ctx->nr_inodes = memparse(ptr: param->string, retptr: &rest);
1397 return 0;
1398
1399 case Opt_pagesize:
1400 ps = memparse(ptr: param->string, retptr: &rest);
1401 ctx->hstate = size_to_hstate(size: ps);
1402 if (!ctx->hstate) {
1403 pr_err("Unsupported page size %lu MB\n", ps / SZ_1M);
1404 return -EINVAL;
1405 }
1406 return 0;
1407
1408 case Opt_min_size:
1409 /* memparse() will accept a K/M/G without a digit */
1410 if (!param->string || !isdigit(c: param->string[0]))
1411 goto bad_val;
1412 ctx->min_size_opt = memparse(ptr: param->string, retptr: &rest);
1413 ctx->min_val_type = SIZE_STD;
1414 if (*rest == '%')
1415 ctx->min_val_type = SIZE_PERCENT;
1416 return 0;
1417
1418 default:
1419 return -EINVAL;
1420 }
1421
1422bad_val:
1423 return invalfc(fc, "Bad value '%s' for mount option '%s'\n",
1424 param->string, param->key);
1425}
1426
1427/*
1428 * Validate the parsed options.
1429 */
1430static int hugetlbfs_validate(struct fs_context *fc)
1431{
1432 struct hugetlbfs_fs_context *ctx = fc->fs_private;
1433
1434 /*
1435 * Use huge page pool size (in hstate) to convert the size
1436 * options to number of huge pages. If NO_SIZE, -1 is returned.
1437 */
1438 ctx->max_hpages = hugetlbfs_size_to_hpages(h: ctx->hstate,
1439 size_opt: ctx->max_size_opt,
1440 val_type: ctx->max_val_type);
1441 ctx->min_hpages = hugetlbfs_size_to_hpages(h: ctx->hstate,
1442 size_opt: ctx->min_size_opt,
1443 val_type: ctx->min_val_type);
1444
1445 /*
1446 * If max_size was specified, then min_size must be smaller
1447 */
1448 if (ctx->max_val_type > NO_SIZE &&
1449 ctx->min_hpages > ctx->max_hpages) {
1450 pr_err("Minimum size can not be greater than maximum size\n");
1451 return -EINVAL;
1452 }
1453
1454 return 0;
1455}
1456
1457static int
1458hugetlbfs_fill_super(struct super_block *sb, struct fs_context *fc)
1459{
1460 struct hugetlbfs_fs_context *ctx = fc->fs_private;
1461 struct hugetlbfs_sb_info *sbinfo;
1462
1463 sbinfo = kmalloc(size: sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
1464 if (!sbinfo)
1465 return -ENOMEM;
1466 sb->s_fs_info = sbinfo;
1467 spin_lock_init(&sbinfo->stat_lock);
1468 sbinfo->hstate = ctx->hstate;
1469 sbinfo->max_inodes = ctx->nr_inodes;
1470 sbinfo->free_inodes = ctx->nr_inodes;
1471 sbinfo->spool = NULL;
1472 sbinfo->uid = ctx->uid;
1473 sbinfo->gid = ctx->gid;
1474 sbinfo->mode = ctx->mode;
1475
1476 /*
1477 * Allocate and initialize subpool if maximum or minimum size is
1478 * specified. Any needed reservations (for minimum size) are taken
1479 * when the subpool is created.
1480 */
1481 if (ctx->max_hpages != -1 || ctx->min_hpages != -1) {
1482 sbinfo->spool = hugepage_new_subpool(h: ctx->hstate,
1483 max_hpages: ctx->max_hpages,
1484 min_hpages: ctx->min_hpages);
1485 if (!sbinfo->spool)
1486 goto out_free;
1487 }
1488 sb->s_maxbytes = MAX_LFS_FILESIZE;
1489 sb->s_blocksize = huge_page_size(h: ctx->hstate);
1490 sb->s_blocksize_bits = huge_page_shift(h: ctx->hstate);
1491 sb->s_magic = HUGETLBFS_MAGIC;
1492 sb->s_op = &hugetlbfs_ops;
1493 sb->s_time_gran = 1;
1494
1495 /*
1496 * Due to the special and limited functionality of hugetlbfs, it does
1497 * not work well as a stacking filesystem.
1498 */
1499 sb->s_stack_depth = FILESYSTEM_MAX_STACK_DEPTH;
1500 sb->s_root = d_make_root(hugetlbfs_get_root(sb, ctx));
1501 if (!sb->s_root)
1502 goto out_free;
1503 return 0;
1504out_free:
1505 kfree(objp: sbinfo->spool);
1506 kfree(objp: sbinfo);
1507 return -ENOMEM;
1508}
1509
1510static int hugetlbfs_get_tree(struct fs_context *fc)
1511{
1512 int err = hugetlbfs_validate(fc);
1513 if (err)
1514 return err;
1515 return get_tree_nodev(fc, fill_super: hugetlbfs_fill_super);
1516}
1517
1518static void hugetlbfs_fs_context_free(struct fs_context *fc)
1519{
1520 kfree(objp: fc->fs_private);
1521}
1522
1523static const struct fs_context_operations hugetlbfs_fs_context_ops = {
1524 .free = hugetlbfs_fs_context_free,
1525 .parse_param = hugetlbfs_parse_param,
1526 .get_tree = hugetlbfs_get_tree,
1527};
1528
1529static int hugetlbfs_init_fs_context(struct fs_context *fc)
1530{
1531 struct hugetlbfs_fs_context *ctx;
1532
1533 ctx = kzalloc(size: sizeof(struct hugetlbfs_fs_context), GFP_KERNEL);
1534 if (!ctx)
1535 return -ENOMEM;
1536
1537 ctx->max_hpages = -1; /* No limit on size by default */
1538 ctx->nr_inodes = -1; /* No limit on number of inodes by default */
1539 ctx->uid = current_fsuid();
1540 ctx->gid = current_fsgid();
1541 ctx->mode = 0755;
1542 ctx->hstate = &default_hstate;
1543 ctx->min_hpages = -1; /* No default minimum size */
1544 ctx->max_val_type = NO_SIZE;
1545 ctx->min_val_type = NO_SIZE;
1546 fc->fs_private = ctx;
1547 fc->ops = &hugetlbfs_fs_context_ops;
1548 return 0;
1549}
1550
1551static struct file_system_type hugetlbfs_fs_type = {
1552 .name = "hugetlbfs",
1553 .init_fs_context = hugetlbfs_init_fs_context,
1554 .parameters = hugetlb_fs_parameters,
1555 .kill_sb = kill_litter_super,
1556};
1557
1558static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE];
1559
1560static int can_do_hugetlb_shm(void)
1561{
1562 kgid_t shm_group;
1563 shm_group = make_kgid(from: &init_user_ns, gid: sysctl_hugetlb_shm_group);
1564 return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
1565}
1566
1567static int get_hstate_idx(int page_size_log)
1568{
1569 struct hstate *h = hstate_sizelog(page_size_log);
1570
1571 if (!h)
1572 return -1;
1573 return hstate_index(h);
1574}
1575
1576/*
1577 * Note that size should be aligned to proper hugepage size in caller side,
1578 * otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
1579 */
1580struct file *hugetlb_file_setup(const char *name, size_t size,
1581 vm_flags_t acctflag, int creat_flags,
1582 int page_size_log)
1583{
1584 struct inode *inode;
1585 struct vfsmount *mnt;
1586 int hstate_idx;
1587 struct file *file;
1588
1589 hstate_idx = get_hstate_idx(page_size_log);
1590 if (hstate_idx < 0)
1591 return ERR_PTR(error: -ENODEV);
1592
1593 mnt = hugetlbfs_vfsmount[hstate_idx];
1594 if (!mnt)
1595 return ERR_PTR(error: -ENOENT);
1596
1597 if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
1598 struct ucounts *ucounts = current_ucounts();
1599
1600 if (user_shm_lock(size, ucounts)) {
1601 pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is obsolete\n",
1602 current->comm, current->pid);
1603 user_shm_unlock(size, ucounts);
1604 }
1605 return ERR_PTR(error: -EPERM);
1606 }
1607
1608 file = ERR_PTR(error: -ENOSPC);
1609 inode = hugetlbfs_get_inode(sb: mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, dev: 0);
1610 if (!inode)
1611 goto out;
1612 if (creat_flags == HUGETLB_SHMFS_INODE)
1613 inode->i_flags |= S_PRIVATE;
1614
1615 inode->i_size = size;
1616 clear_nlink(inode);
1617
1618 if (!hugetlb_reserve_pages(inode, from: 0,
1619 to: size >> huge_page_shift(h: hstate_inode(i: inode)), NULL,
1620 vm_flags: acctflag))
1621 file = ERR_PTR(error: -ENOMEM);
1622 else
1623 file = alloc_file_pseudo(inode, mnt, name, O_RDWR,
1624 &hugetlbfs_file_operations);
1625 if (!IS_ERR(ptr: file))
1626 return file;
1627
1628 iput(inode);
1629out:
1630 return file;
1631}
1632
1633static struct vfsmount *__init mount_one_hugetlbfs(struct hstate *h)
1634{
1635 struct fs_context *fc;
1636 struct vfsmount *mnt;
1637
1638 fc = fs_context_for_mount(fs_type: &hugetlbfs_fs_type, SB_KERNMOUNT);
1639 if (IS_ERR(ptr: fc)) {
1640 mnt = ERR_CAST(ptr: fc);
1641 } else {
1642 struct hugetlbfs_fs_context *ctx = fc->fs_private;
1643 ctx->hstate = h;
1644 mnt = fc_mount(fc);
1645 put_fs_context(fc);
1646 }
1647 if (IS_ERR(ptr: mnt))
1648 pr_err("Cannot mount internal hugetlbfs for page size %luK",
1649 huge_page_size(h) / SZ_1K);
1650 return mnt;
1651}
1652
1653static int __init init_hugetlbfs_fs(void)
1654{
1655 struct vfsmount *mnt;
1656 struct hstate *h;
1657 int error;
1658 int i;
1659
1660 if (!hugepages_supported()) {
1661 pr_info("disabling because there are no supported hugepage sizes\n");
1662 return -ENOTSUPP;
1663 }
1664
1665 error = -ENOMEM;
1666 hugetlbfs_inode_cachep = kmem_cache_create(name: "hugetlbfs_inode_cache",
1667 size: sizeof(struct hugetlbfs_inode_info),
1668 align: 0, SLAB_ACCOUNT, ctor: init_once);
1669 if (hugetlbfs_inode_cachep == NULL)
1670 goto out;
1671
1672 error = register_filesystem(&hugetlbfs_fs_type);
1673 if (error)
1674 goto out_free;
1675
1676 /* default hstate mount is required */
1677 mnt = mount_one_hugetlbfs(h: &default_hstate);
1678 if (IS_ERR(ptr: mnt)) {
1679 error = PTR_ERR(ptr: mnt);
1680 goto out_unreg;
1681 }
1682 hugetlbfs_vfsmount[default_hstate_idx] = mnt;
1683
1684 /* other hstates are optional */
1685 i = 0;
1686 for_each_hstate(h) {
1687 if (i == default_hstate_idx) {
1688 i++;
1689 continue;
1690 }
1691
1692 mnt = mount_one_hugetlbfs(h);
1693 if (IS_ERR(ptr: mnt))
1694 hugetlbfs_vfsmount[i] = NULL;
1695 else
1696 hugetlbfs_vfsmount[i] = mnt;
1697 i++;
1698 }
1699
1700 return 0;
1701
1702 out_unreg:
1703 (void)unregister_filesystem(&hugetlbfs_fs_type);
1704 out_free:
1705 kmem_cache_destroy(s: hugetlbfs_inode_cachep);
1706 out:
1707 return error;
1708}
1709fs_initcall(init_hugetlbfs_fs)
1710

source code of linux/fs/hugetlbfs/inode.c