Merge tag 'ktest-v5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux...
[linux-2.6-microblaze.git] / fs / hugetlbfs / inode.c
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/signal.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/fs_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 <linux/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 enum hugetlbfs_size_type { NO_SIZE, SIZE_STD, SIZE_PERCENT };
49
50 struct hugetlbfs_fs_context {
51         struct hstate           *hstate;
52         unsigned long long      max_size_opt;
53         unsigned long long      min_size_opt;
54         long                    max_hpages;
55         long                    nr_inodes;
56         long                    min_hpages;
57         enum hugetlbfs_size_type max_val_type;
58         enum hugetlbfs_size_type min_val_type;
59         kuid_t                  uid;
60         kgid_t                  gid;
61         umode_t                 mode;
62 };
63
64 int sysctl_hugetlb_shm_group;
65
66 enum hugetlb_param {
67         Opt_gid,
68         Opt_min_size,
69         Opt_mode,
70         Opt_nr_inodes,
71         Opt_pagesize,
72         Opt_size,
73         Opt_uid,
74 };
75
76 static const struct fs_parameter_spec hugetlb_param_specs[] = {
77         fsparam_u32   ("gid",           Opt_gid),
78         fsparam_string("min_size",      Opt_min_size),
79         fsparam_u32   ("mode",          Opt_mode),
80         fsparam_string("nr_inodes",     Opt_nr_inodes),
81         fsparam_string("pagesize",      Opt_pagesize),
82         fsparam_string("size",          Opt_size),
83         fsparam_u32   ("uid",           Opt_uid),
84         {}
85 };
86
87 static const struct fs_parameter_description hugetlb_fs_parameters = {
88         .name           = "hugetlbfs",
89         .specs          = hugetlb_param_specs,
90 };
91
92 #ifdef CONFIG_NUMA
93 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
94                                         struct inode *inode, pgoff_t index)
95 {
96         vma->vm_policy = mpol_shared_policy_lookup(&HUGETLBFS_I(inode)->policy,
97                                                         index);
98 }
99
100 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
101 {
102         mpol_cond_put(vma->vm_policy);
103 }
104 #else
105 static inline void hugetlb_set_vma_policy(struct vm_area_struct *vma,
106                                         struct inode *inode, pgoff_t index)
107 {
108 }
109
110 static inline void hugetlb_drop_vma_policy(struct vm_area_struct *vma)
111 {
112 }
113 #endif
114
115 static void huge_pagevec_release(struct pagevec *pvec)
116 {
117         int i;
118
119         for (i = 0; i < pagevec_count(pvec); ++i)
120                 put_page(pvec->pages[i]);
121
122         pagevec_reinit(pvec);
123 }
124
125 /*
126  * Mask used when checking the page offset value passed in via system
127  * calls.  This value will be converted to a loff_t which is signed.
128  * Therefore, we want to check the upper PAGE_SHIFT + 1 bits of the
129  * value.  The extra bit (- 1 in the shift value) is to take the sign
130  * bit into account.
131  */
132 #define PGOFF_LOFFT_MAX \
133         (((1UL << (PAGE_SHIFT + 1)) - 1) <<  (BITS_PER_LONG - (PAGE_SHIFT + 1)))
134
135 static int hugetlbfs_file_mmap(struct file *file, struct vm_area_struct *vma)
136 {
137         struct inode *inode = file_inode(file);
138         loff_t len, vma_len;
139         int ret;
140         struct hstate *h = hstate_file(file);
141
142         /*
143          * vma address alignment (but not the pgoff alignment) has
144          * already been checked by prepare_hugepage_range.  If you add
145          * any error returns here, do so after setting VM_HUGETLB, so
146          * is_vm_hugetlb_page tests below unmap_region go the right
147          * way when do_mmap_pgoff unwinds (may be important on powerpc
148          * and ia64).
149          */
150         vma->vm_flags |= VM_HUGETLB | VM_DONTEXPAND;
151         vma->vm_ops = &hugetlb_vm_ops;
152
153         /*
154          * page based offset in vm_pgoff could be sufficiently large to
155          * overflow a loff_t when converted to byte offset.  This can
156          * only happen on architectures where sizeof(loff_t) ==
157          * sizeof(unsigned long).  So, only check in those instances.
158          */
159         if (sizeof(unsigned long) == sizeof(loff_t)) {
160                 if (vma->vm_pgoff & PGOFF_LOFFT_MAX)
161                         return -EINVAL;
162         }
163
164         /* must be huge page aligned */
165         if (vma->vm_pgoff & (~huge_page_mask(h) >> PAGE_SHIFT))
166                 return -EINVAL;
167
168         vma_len = (loff_t)(vma->vm_end - vma->vm_start);
169         len = vma_len + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
170         /* check for overflow */
171         if (len < vma_len)
172                 return -EINVAL;
173
174         inode_lock(inode);
175         file_accessed(file);
176
177         ret = -ENOMEM;
178         if (hugetlb_reserve_pages(inode,
179                                 vma->vm_pgoff >> huge_page_order(h),
180                                 len >> huge_page_shift(h), vma,
181                                 vma->vm_flags))
182                 goto out;
183
184         ret = 0;
185         if (vma->vm_flags & VM_WRITE && inode->i_size < len)
186                 i_size_write(inode, len);
187 out:
188         inode_unlock(inode);
189
190         return ret;
191 }
192
193 /*
194  * Called under down_write(mmap_sem).
195  */
196
197 #ifndef HAVE_ARCH_HUGETLB_UNMAPPED_AREA
198 static unsigned long
199 hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
200                 unsigned long len, unsigned long pgoff, unsigned long flags)
201 {
202         struct mm_struct *mm = current->mm;
203         struct vm_area_struct *vma;
204         struct hstate *h = hstate_file(file);
205         struct vm_unmapped_area_info info;
206
207         if (len & ~huge_page_mask(h))
208                 return -EINVAL;
209         if (len > TASK_SIZE)
210                 return -ENOMEM;
211
212         if (flags & MAP_FIXED) {
213                 if (prepare_hugepage_range(file, addr, len))
214                         return -EINVAL;
215                 return addr;
216         }
217
218         if (addr) {
219                 addr = ALIGN(addr, huge_page_size(h));
220                 vma = find_vma(mm, addr);
221                 if (TASK_SIZE - len >= addr &&
222                     (!vma || addr + len <= vm_start_gap(vma)))
223                         return addr;
224         }
225
226         info.flags = 0;
227         info.length = len;
228         info.low_limit = TASK_UNMAPPED_BASE;
229         info.high_limit = TASK_SIZE;
230         info.align_mask = PAGE_MASK & ~huge_page_mask(h);
231         info.align_offset = 0;
232         return vm_unmapped_area(&info);
233 }
234 #endif
235
236 static size_t
237 hugetlbfs_read_actor(struct page *page, unsigned long offset,
238                         struct iov_iter *to, unsigned long size)
239 {
240         size_t copied = 0;
241         int i, chunksize;
242
243         /* Find which 4k chunk and offset with in that chunk */
244         i = offset >> PAGE_SHIFT;
245         offset = offset & ~PAGE_MASK;
246
247         while (size) {
248                 size_t n;
249                 chunksize = PAGE_SIZE;
250                 if (offset)
251                         chunksize -= offset;
252                 if (chunksize > size)
253                         chunksize = size;
254                 n = copy_page_to_iter(&page[i], offset, chunksize, to);
255                 copied += n;
256                 if (n != chunksize)
257                         return copied;
258                 offset = 0;
259                 size -= chunksize;
260                 i++;
261         }
262         return copied;
263 }
264
265 /*
266  * Support for read() - Find the page attached to f_mapping and copy out the
267  * data. Its *very* similar to do_generic_mapping_read(), we can't use that
268  * since it has PAGE_SIZE assumptions.
269  */
270 static ssize_t hugetlbfs_read_iter(struct kiocb *iocb, struct iov_iter *to)
271 {
272         struct file *file = iocb->ki_filp;
273         struct hstate *h = hstate_file(file);
274         struct address_space *mapping = file->f_mapping;
275         struct inode *inode = mapping->host;
276         unsigned long index = iocb->ki_pos >> huge_page_shift(h);
277         unsigned long offset = iocb->ki_pos & ~huge_page_mask(h);
278         unsigned long end_index;
279         loff_t isize;
280         ssize_t retval = 0;
281
282         while (iov_iter_count(to)) {
283                 struct page *page;
284                 size_t nr, copied;
285
286                 /* nr is the maximum number of bytes to copy from this page */
287                 nr = huge_page_size(h);
288                 isize = i_size_read(inode);
289                 if (!isize)
290                         break;
291                 end_index = (isize - 1) >> huge_page_shift(h);
292                 if (index > end_index)
293                         break;
294                 if (index == end_index) {
295                         nr = ((isize - 1) & ~huge_page_mask(h)) + 1;
296                         if (nr <= offset)
297                                 break;
298                 }
299                 nr = nr - offset;
300
301                 /* Find the page */
302                 page = find_lock_page(mapping, index);
303                 if (unlikely(page == NULL)) {
304                         /*
305                          * We have a HOLE, zero out the user-buffer for the
306                          * length of the hole or request.
307                          */
308                         copied = iov_iter_zero(nr, to);
309                 } else {
310                         unlock_page(page);
311
312                         /*
313                          * We have the page, copy it to user space buffer.
314                          */
315                         copied = hugetlbfs_read_actor(page, offset, to, nr);
316                         put_page(page);
317                 }
318                 offset += copied;
319                 retval += copied;
320                 if (copied != nr && iov_iter_count(to)) {
321                         if (!retval)
322                                 retval = -EFAULT;
323                         break;
324                 }
325                 index += offset >> huge_page_shift(h);
326                 offset &= ~huge_page_mask(h);
327         }
328         iocb->ki_pos = ((loff_t)index << huge_page_shift(h)) + offset;
329         return retval;
330 }
331
332 static int hugetlbfs_write_begin(struct file *file,
333                         struct address_space *mapping,
334                         loff_t pos, unsigned len, unsigned flags,
335                         struct page **pagep, void **fsdata)
336 {
337         return -EINVAL;
338 }
339
340 static int hugetlbfs_write_end(struct file *file, struct address_space *mapping,
341                         loff_t pos, unsigned len, unsigned copied,
342                         struct page *page, void *fsdata)
343 {
344         BUG();
345         return -EINVAL;
346 }
347
348 static void remove_huge_page(struct page *page)
349 {
350         ClearPageDirty(page);
351         ClearPageUptodate(page);
352         delete_from_page_cache(page);
353 }
354
355 static void
356 hugetlb_vmdelete_list(struct rb_root_cached *root, pgoff_t start, pgoff_t end)
357 {
358         struct vm_area_struct *vma;
359
360         /*
361          * end == 0 indicates that the entire range after
362          * start should be unmapped.
363          */
364         vma_interval_tree_foreach(vma, root, start, end ? end : ULONG_MAX) {
365                 unsigned long v_offset;
366                 unsigned long v_end;
367
368                 /*
369                  * Can the expression below overflow on 32-bit arches?
370                  * No, because the interval tree returns us only those vmas
371                  * which overlap the truncated area starting at pgoff,
372                  * and no vma on a 32-bit arch can span beyond the 4GB.
373                  */
374                 if (vma->vm_pgoff < start)
375                         v_offset = (start - vma->vm_pgoff) << PAGE_SHIFT;
376                 else
377                         v_offset = 0;
378
379                 if (!end)
380                         v_end = vma->vm_end;
381                 else {
382                         v_end = ((end - vma->vm_pgoff) << PAGE_SHIFT)
383                                                         + vma->vm_start;
384                         if (v_end > vma->vm_end)
385                                 v_end = vma->vm_end;
386                 }
387
388                 unmap_hugepage_range(vma, vma->vm_start + v_offset, v_end,
389                                                                         NULL);
390         }
391 }
392
393 /*
394  * remove_inode_hugepages handles two distinct cases: truncation and hole
395  * punch.  There are subtle differences in operation for each case.
396  *
397  * truncation is indicated by end of range being LLONG_MAX
398  *      In this case, we first scan the range and release found pages.
399  *      After releasing pages, hugetlb_unreserve_pages cleans up region/reserv
400  *      maps and global counts.  Page faults can not race with truncation
401  *      in this routine.  hugetlb_no_page() prevents page faults in the
402  *      truncated range.  It checks i_size before allocation, and again after
403  *      with the page table lock for the page held.  The same lock must be
404  *      acquired to unmap a page.
405  * hole punch is indicated if end is not LLONG_MAX
406  *      In the hole punch case we scan the range and release found pages.
407  *      Only when releasing a page is the associated region/reserv map
408  *      deleted.  The region/reserv map for ranges without associated
409  *      pages are not modified.  Page faults can race with hole punch.
410  *      This is indicated if we find a mapped page.
411  * Note: If the passed end of range value is beyond the end of file, but
412  * not LLONG_MAX this routine still performs a hole punch operation.
413  */
414 static void remove_inode_hugepages(struct inode *inode, loff_t lstart,
415                                    loff_t lend)
416 {
417         struct hstate *h = hstate_inode(inode);
418         struct address_space *mapping = &inode->i_data;
419         const pgoff_t start = lstart >> huge_page_shift(h);
420         const pgoff_t end = lend >> huge_page_shift(h);
421         struct vm_area_struct pseudo_vma;
422         struct pagevec pvec;
423         pgoff_t next, index;
424         int i, freed = 0;
425         bool truncate_op = (lend == LLONG_MAX);
426
427         vma_init(&pseudo_vma, current->mm);
428         pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
429         pagevec_init(&pvec);
430         next = start;
431         while (next < end) {
432                 /*
433                  * When no more pages are found, we are done.
434                  */
435                 if (!pagevec_lookup_range(&pvec, mapping, &next, end - 1))
436                         break;
437
438                 for (i = 0; i < pagevec_count(&pvec); ++i) {
439                         struct page *page = pvec.pages[i];
440                         u32 hash;
441
442                         index = page->index;
443                         hash = hugetlb_fault_mutex_hash(h, mapping, index, 0);
444                         mutex_lock(&hugetlb_fault_mutex_table[hash]);
445
446                         /*
447                          * If page is mapped, it was faulted in after being
448                          * unmapped in caller.  Unmap (again) now after taking
449                          * the fault mutex.  The mutex will prevent faults
450                          * until we finish removing the page.
451                          *
452                          * This race can only happen in the hole punch case.
453                          * Getting here in a truncate operation is a bug.
454                          */
455                         if (unlikely(page_mapped(page))) {
456                                 BUG_ON(truncate_op);
457
458                                 i_mmap_lock_write(mapping);
459                                 hugetlb_vmdelete_list(&mapping->i_mmap,
460                                         index * pages_per_huge_page(h),
461                                         (index + 1) * pages_per_huge_page(h));
462                                 i_mmap_unlock_write(mapping);
463                         }
464
465                         lock_page(page);
466                         /*
467                          * We must free the huge page and remove from page
468                          * cache (remove_huge_page) BEFORE removing the
469                          * region/reserve map (hugetlb_unreserve_pages).  In
470                          * rare out of memory conditions, removal of the
471                          * region/reserve map could fail. Correspondingly,
472                          * the subpool and global reserve usage count can need
473                          * to be adjusted.
474                          */
475                         VM_BUG_ON(PagePrivate(page));
476                         remove_huge_page(page);
477                         freed++;
478                         if (!truncate_op) {
479                                 if (unlikely(hugetlb_unreserve_pages(inode,
480                                                         index, index + 1, 1)))
481                                         hugetlb_fix_reserve_counts(inode);
482                         }
483
484                         unlock_page(page);
485                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
486                 }
487                 huge_pagevec_release(&pvec);
488                 cond_resched();
489         }
490
491         if (truncate_op)
492                 (void)hugetlb_unreserve_pages(inode, start, LONG_MAX, freed);
493 }
494
495 static void hugetlbfs_evict_inode(struct inode *inode)
496 {
497         struct resv_map *resv_map;
498
499         remove_inode_hugepages(inode, 0, LLONG_MAX);
500
501         /*
502          * Get the resv_map from the address space embedded in the inode.
503          * This is the address space which points to any resv_map allocated
504          * at inode creation time.  If this is a device special inode,
505          * i_mapping may not point to the original address space.
506          */
507         resv_map = (struct resv_map *)(&inode->i_data)->private_data;
508         /* Only regular and link inodes have associated reserve maps */
509         if (resv_map)
510                 resv_map_release(&resv_map->refs);
511         clear_inode(inode);
512 }
513
514 static int hugetlb_vmtruncate(struct inode *inode, loff_t offset)
515 {
516         pgoff_t pgoff;
517         struct address_space *mapping = inode->i_mapping;
518         struct hstate *h = hstate_inode(inode);
519
520         BUG_ON(offset & ~huge_page_mask(h));
521         pgoff = offset >> PAGE_SHIFT;
522
523         i_size_write(inode, offset);
524         i_mmap_lock_write(mapping);
525         if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
526                 hugetlb_vmdelete_list(&mapping->i_mmap, pgoff, 0);
527         i_mmap_unlock_write(mapping);
528         remove_inode_hugepages(inode, offset, LLONG_MAX);
529         return 0;
530 }
531
532 static long hugetlbfs_punch_hole(struct inode *inode, loff_t offset, loff_t len)
533 {
534         struct hstate *h = hstate_inode(inode);
535         loff_t hpage_size = huge_page_size(h);
536         loff_t hole_start, hole_end;
537
538         /*
539          * For hole punch round up the beginning offset of the hole and
540          * round down the end.
541          */
542         hole_start = round_up(offset, hpage_size);
543         hole_end = round_down(offset + len, hpage_size);
544
545         if (hole_end > hole_start) {
546                 struct address_space *mapping = inode->i_mapping;
547                 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
548
549                 inode_lock(inode);
550
551                 /* protected by i_mutex */
552                 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
553                         inode_unlock(inode);
554                         return -EPERM;
555                 }
556
557                 i_mmap_lock_write(mapping);
558                 if (!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root))
559                         hugetlb_vmdelete_list(&mapping->i_mmap,
560                                                 hole_start >> PAGE_SHIFT,
561                                                 hole_end  >> PAGE_SHIFT);
562                 i_mmap_unlock_write(mapping);
563                 remove_inode_hugepages(inode, hole_start, hole_end);
564                 inode_unlock(inode);
565         }
566
567         return 0;
568 }
569
570 static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
571                                 loff_t len)
572 {
573         struct inode *inode = file_inode(file);
574         struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
575         struct address_space *mapping = inode->i_mapping;
576         struct hstate *h = hstate_inode(inode);
577         struct vm_area_struct pseudo_vma;
578         struct mm_struct *mm = current->mm;
579         loff_t hpage_size = huge_page_size(h);
580         unsigned long hpage_shift = huge_page_shift(h);
581         pgoff_t start, index, end;
582         int error;
583         u32 hash;
584
585         if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
586                 return -EOPNOTSUPP;
587
588         if (mode & FALLOC_FL_PUNCH_HOLE)
589                 return hugetlbfs_punch_hole(inode, offset, len);
590
591         /*
592          * Default preallocate case.
593          * For this range, start is rounded down and end is rounded up
594          * as well as being converted to page offsets.
595          */
596         start = offset >> hpage_shift;
597         end = (offset + len + hpage_size - 1) >> hpage_shift;
598
599         inode_lock(inode);
600
601         /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
602         error = inode_newsize_ok(inode, offset + len);
603         if (error)
604                 goto out;
605
606         if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
607                 error = -EPERM;
608                 goto out;
609         }
610
611         /*
612          * Initialize a pseudo vma as this is required by the huge page
613          * allocation routines.  If NUMA is configured, use page index
614          * as input to create an allocation policy.
615          */
616         vma_init(&pseudo_vma, mm);
617         pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
618         pseudo_vma.vm_file = file;
619
620         for (index = start; index < end; index++) {
621                 /*
622                  * This is supposed to be the vaddr where the page is being
623                  * faulted in, but we have no vaddr here.
624                  */
625                 struct page *page;
626                 unsigned long addr;
627                 int avoid_reserve = 0;
628
629                 cond_resched();
630
631                 /*
632                  * fallocate(2) manpage permits EINTR; we may have been
633                  * interrupted because we are using up too much memory.
634                  */
635                 if (signal_pending(current)) {
636                         error = -EINTR;
637                         break;
638                 }
639
640                 /* Set numa allocation policy based on index */
641                 hugetlb_set_vma_policy(&pseudo_vma, inode, index);
642
643                 /* addr is the offset within the file (zero based) */
644                 addr = index * hpage_size;
645
646                 /* mutex taken here, fault path and hole punch */
647                 hash = hugetlb_fault_mutex_hash(h, mapping, index, addr);
648                 mutex_lock(&hugetlb_fault_mutex_table[hash]);
649
650                 /* See if already present in mapping to avoid alloc/free */
651                 page = find_get_page(mapping, index);
652                 if (page) {
653                         put_page(page);
654                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
655                         hugetlb_drop_vma_policy(&pseudo_vma);
656                         continue;
657                 }
658
659                 /* Allocate page and add to page cache */
660                 page = alloc_huge_page(&pseudo_vma, addr, avoid_reserve);
661                 hugetlb_drop_vma_policy(&pseudo_vma);
662                 if (IS_ERR(page)) {
663                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
664                         error = PTR_ERR(page);
665                         goto out;
666                 }
667                 clear_huge_page(page, addr, pages_per_huge_page(h));
668                 __SetPageUptodate(page);
669                 error = huge_add_to_page_cache(page, mapping, index);
670                 if (unlikely(error)) {
671                         put_page(page);
672                         mutex_unlock(&hugetlb_fault_mutex_table[hash]);
673                         goto out;
674                 }
675
676                 mutex_unlock(&hugetlb_fault_mutex_table[hash]);
677
678                 /*
679                  * unlock_page because locked by add_to_page_cache()
680                  * page_put due to reference from alloc_huge_page()
681                  */
682                 unlock_page(page);
683                 put_page(page);
684         }
685
686         if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
687                 i_size_write(inode, offset + len);
688         inode->i_ctime = current_time(inode);
689 out:
690         inode_unlock(inode);
691         return error;
692 }
693
694 static int hugetlbfs_setattr(struct dentry *dentry, struct iattr *attr)
695 {
696         struct inode *inode = d_inode(dentry);
697         struct hstate *h = hstate_inode(inode);
698         int error;
699         unsigned int ia_valid = attr->ia_valid;
700         struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
701
702         BUG_ON(!inode);
703
704         error = setattr_prepare(dentry, attr);
705         if (error)
706                 return error;
707
708         if (ia_valid & ATTR_SIZE) {
709                 loff_t oldsize = inode->i_size;
710                 loff_t newsize = attr->ia_size;
711
712                 if (newsize & ~huge_page_mask(h))
713                         return -EINVAL;
714                 /* protected by i_mutex */
715                 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
716                     (newsize > oldsize && (info->seals & F_SEAL_GROW)))
717                         return -EPERM;
718                 error = hugetlb_vmtruncate(inode, newsize);
719                 if (error)
720                         return error;
721         }
722
723         setattr_copy(inode, attr);
724         mark_inode_dirty(inode);
725         return 0;
726 }
727
728 static struct inode *hugetlbfs_get_root(struct super_block *sb,
729                                         struct hugetlbfs_fs_context *ctx)
730 {
731         struct inode *inode;
732
733         inode = new_inode(sb);
734         if (inode) {
735                 inode->i_ino = get_next_ino();
736                 inode->i_mode = S_IFDIR | ctx->mode;
737                 inode->i_uid = ctx->uid;
738                 inode->i_gid = ctx->gid;
739                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
740                 inode->i_op = &hugetlbfs_dir_inode_operations;
741                 inode->i_fop = &simple_dir_operations;
742                 /* directory inodes start off with i_nlink == 2 (for "." entry) */
743                 inc_nlink(inode);
744                 lockdep_annotate_inode_mutex_key(inode);
745         }
746         return inode;
747 }
748
749 /*
750  * Hugetlbfs is not reclaimable; therefore its i_mmap_rwsem will never
751  * be taken from reclaim -- unlike regular filesystems. This needs an
752  * annotation because huge_pmd_share() does an allocation under hugetlb's
753  * i_mmap_rwsem.
754  */
755 static struct lock_class_key hugetlbfs_i_mmap_rwsem_key;
756
757 static struct inode *hugetlbfs_get_inode(struct super_block *sb,
758                                         struct inode *dir,
759                                         umode_t mode, dev_t dev)
760 {
761         struct inode *inode;
762         struct resv_map *resv_map = NULL;
763
764         /*
765          * Reserve maps are only needed for inodes that can have associated
766          * page allocations.
767          */
768         if (S_ISREG(mode) || S_ISLNK(mode)) {
769                 resv_map = resv_map_alloc();
770                 if (!resv_map)
771                         return NULL;
772         }
773
774         inode = new_inode(sb);
775         if (inode) {
776                 struct hugetlbfs_inode_info *info = HUGETLBFS_I(inode);
777
778                 inode->i_ino = get_next_ino();
779                 inode_init_owner(inode, dir, mode);
780                 lockdep_set_class(&inode->i_mapping->i_mmap_rwsem,
781                                 &hugetlbfs_i_mmap_rwsem_key);
782                 inode->i_mapping->a_ops = &hugetlbfs_aops;
783                 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
784                 inode->i_mapping->private_data = resv_map;
785                 info->seals = F_SEAL_SEAL;
786                 switch (mode & S_IFMT) {
787                 default:
788                         init_special_inode(inode, mode, dev);
789                         break;
790                 case S_IFREG:
791                         inode->i_op = &hugetlbfs_inode_operations;
792                         inode->i_fop = &hugetlbfs_file_operations;
793                         break;
794                 case S_IFDIR:
795                         inode->i_op = &hugetlbfs_dir_inode_operations;
796                         inode->i_fop = &simple_dir_operations;
797
798                         /* directory inodes start off with i_nlink == 2 (for "." entry) */
799                         inc_nlink(inode);
800                         break;
801                 case S_IFLNK:
802                         inode->i_op = &page_symlink_inode_operations;
803                         inode_nohighmem(inode);
804                         break;
805                 }
806                 lockdep_annotate_inode_mutex_key(inode);
807         } else {
808                 if (resv_map)
809                         kref_put(&resv_map->refs, resv_map_release);
810         }
811
812         return inode;
813 }
814
815 /*
816  * File creation. Allocate an inode, and we're done..
817  */
818 static int hugetlbfs_mknod(struct inode *dir,
819                         struct dentry *dentry, umode_t mode, dev_t dev)
820 {
821         struct inode *inode;
822         int error = -ENOSPC;
823
824         inode = hugetlbfs_get_inode(dir->i_sb, dir, mode, dev);
825         if (inode) {
826                 dir->i_ctime = dir->i_mtime = current_time(dir);
827                 d_instantiate(dentry, inode);
828                 dget(dentry);   /* Extra count - pin the dentry in core */
829                 error = 0;
830         }
831         return error;
832 }
833
834 static int hugetlbfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
835 {
836         int retval = hugetlbfs_mknod(dir, dentry, mode | S_IFDIR, 0);
837         if (!retval)
838                 inc_nlink(dir);
839         return retval;
840 }
841
842 static int hugetlbfs_create(struct inode *dir, struct dentry *dentry, umode_t mode, bool excl)
843 {
844         return hugetlbfs_mknod(dir, dentry, mode | S_IFREG, 0);
845 }
846
847 static int hugetlbfs_symlink(struct inode *dir,
848                         struct dentry *dentry, const char *symname)
849 {
850         struct inode *inode;
851         int error = -ENOSPC;
852
853         inode = hugetlbfs_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0);
854         if (inode) {
855                 int l = strlen(symname)+1;
856                 error = page_symlink(inode, symname, l);
857                 if (!error) {
858                         d_instantiate(dentry, inode);
859                         dget(dentry);
860                 } else
861                         iput(inode);
862         }
863         dir->i_ctime = dir->i_mtime = current_time(dir);
864
865         return error;
866 }
867
868 /*
869  * mark the head page dirty
870  */
871 static int hugetlbfs_set_page_dirty(struct page *page)
872 {
873         struct page *head = compound_head(page);
874
875         SetPageDirty(head);
876         return 0;
877 }
878
879 static int hugetlbfs_migrate_page(struct address_space *mapping,
880                                 struct page *newpage, struct page *page,
881                                 enum migrate_mode mode)
882 {
883         int rc;
884
885         rc = migrate_huge_page_move_mapping(mapping, newpage, page);
886         if (rc != MIGRATEPAGE_SUCCESS)
887                 return rc;
888
889         /*
890          * page_private is subpool pointer in hugetlb pages.  Transfer to
891          * new page.  PagePrivate is not associated with page_private for
892          * hugetlb pages and can not be set here as only page_huge_active
893          * pages can be migrated.
894          */
895         if (page_private(page)) {
896                 set_page_private(newpage, page_private(page));
897                 set_page_private(page, 0);
898         }
899
900         if (mode != MIGRATE_SYNC_NO_COPY)
901                 migrate_page_copy(newpage, page);
902         else
903                 migrate_page_states(newpage, page);
904
905         return MIGRATEPAGE_SUCCESS;
906 }
907
908 static int hugetlbfs_error_remove_page(struct address_space *mapping,
909                                 struct page *page)
910 {
911         struct inode *inode = mapping->host;
912         pgoff_t index = page->index;
913
914         remove_huge_page(page);
915         if (unlikely(hugetlb_unreserve_pages(inode, index, index + 1, 1)))
916                 hugetlb_fix_reserve_counts(inode);
917
918         return 0;
919 }
920
921 /*
922  * Display the mount options in /proc/mounts.
923  */
924 static int hugetlbfs_show_options(struct seq_file *m, struct dentry *root)
925 {
926         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(root->d_sb);
927         struct hugepage_subpool *spool = sbinfo->spool;
928         unsigned long hpage_size = huge_page_size(sbinfo->hstate);
929         unsigned hpage_shift = huge_page_shift(sbinfo->hstate);
930         char mod;
931
932         if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
933                 seq_printf(m, ",uid=%u",
934                            from_kuid_munged(&init_user_ns, sbinfo->uid));
935         if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
936                 seq_printf(m, ",gid=%u",
937                            from_kgid_munged(&init_user_ns, sbinfo->gid));
938         if (sbinfo->mode != 0755)
939                 seq_printf(m, ",mode=%o", sbinfo->mode);
940         if (sbinfo->max_inodes != -1)
941                 seq_printf(m, ",nr_inodes=%lu", sbinfo->max_inodes);
942
943         hpage_size /= 1024;
944         mod = 'K';
945         if (hpage_size >= 1024) {
946                 hpage_size /= 1024;
947                 mod = 'M';
948         }
949         seq_printf(m, ",pagesize=%lu%c", hpage_size, mod);
950         if (spool) {
951                 if (spool->max_hpages != -1)
952                         seq_printf(m, ",size=%llu",
953                                    (unsigned long long)spool->max_hpages << hpage_shift);
954                 if (spool->min_hpages != -1)
955                         seq_printf(m, ",min_size=%llu",
956                                    (unsigned long long)spool->min_hpages << hpage_shift);
957         }
958         return 0;
959 }
960
961 static int hugetlbfs_statfs(struct dentry *dentry, struct kstatfs *buf)
962 {
963         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(dentry->d_sb);
964         struct hstate *h = hstate_inode(d_inode(dentry));
965
966         buf->f_type = HUGETLBFS_MAGIC;
967         buf->f_bsize = huge_page_size(h);
968         if (sbinfo) {
969                 spin_lock(&sbinfo->stat_lock);
970                 /* If no limits set, just report 0 for max/free/used
971                  * blocks, like simple_statfs() */
972                 if (sbinfo->spool) {
973                         long free_pages;
974
975                         spin_lock(&sbinfo->spool->lock);
976                         buf->f_blocks = sbinfo->spool->max_hpages;
977                         free_pages = sbinfo->spool->max_hpages
978                                 - sbinfo->spool->used_hpages;
979                         buf->f_bavail = buf->f_bfree = free_pages;
980                         spin_unlock(&sbinfo->spool->lock);
981                         buf->f_files = sbinfo->max_inodes;
982                         buf->f_ffree = sbinfo->free_inodes;
983                 }
984                 spin_unlock(&sbinfo->stat_lock);
985         }
986         buf->f_namelen = NAME_MAX;
987         return 0;
988 }
989
990 static void hugetlbfs_put_super(struct super_block *sb)
991 {
992         struct hugetlbfs_sb_info *sbi = HUGETLBFS_SB(sb);
993
994         if (sbi) {
995                 sb->s_fs_info = NULL;
996
997                 if (sbi->spool)
998                         hugepage_put_subpool(sbi->spool);
999
1000                 kfree(sbi);
1001         }
1002 }
1003
1004 static inline int hugetlbfs_dec_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1005 {
1006         if (sbinfo->free_inodes >= 0) {
1007                 spin_lock(&sbinfo->stat_lock);
1008                 if (unlikely(!sbinfo->free_inodes)) {
1009                         spin_unlock(&sbinfo->stat_lock);
1010                         return 0;
1011                 }
1012                 sbinfo->free_inodes--;
1013                 spin_unlock(&sbinfo->stat_lock);
1014         }
1015
1016         return 1;
1017 }
1018
1019 static void hugetlbfs_inc_free_inodes(struct hugetlbfs_sb_info *sbinfo)
1020 {
1021         if (sbinfo->free_inodes >= 0) {
1022                 spin_lock(&sbinfo->stat_lock);
1023                 sbinfo->free_inodes++;
1024                 spin_unlock(&sbinfo->stat_lock);
1025         }
1026 }
1027
1028
1029 static struct kmem_cache *hugetlbfs_inode_cachep;
1030
1031 static struct inode *hugetlbfs_alloc_inode(struct super_block *sb)
1032 {
1033         struct hugetlbfs_sb_info *sbinfo = HUGETLBFS_SB(sb);
1034         struct hugetlbfs_inode_info *p;
1035
1036         if (unlikely(!hugetlbfs_dec_free_inodes(sbinfo)))
1037                 return NULL;
1038         p = kmem_cache_alloc(hugetlbfs_inode_cachep, GFP_KERNEL);
1039         if (unlikely(!p)) {
1040                 hugetlbfs_inc_free_inodes(sbinfo);
1041                 return NULL;
1042         }
1043
1044         /*
1045          * Any time after allocation, hugetlbfs_destroy_inode can be called
1046          * for the inode.  mpol_free_shared_policy is unconditionally called
1047          * as part of hugetlbfs_destroy_inode.  So, initialize policy here
1048          * in case of a quick call to destroy.
1049          *
1050          * Note that the policy is initialized even if we are creating a
1051          * private inode.  This simplifies hugetlbfs_destroy_inode.
1052          */
1053         mpol_shared_policy_init(&p->policy, NULL);
1054
1055         return &p->vfs_inode;
1056 }
1057
1058 static void hugetlbfs_free_inode(struct inode *inode)
1059 {
1060         kmem_cache_free(hugetlbfs_inode_cachep, HUGETLBFS_I(inode));
1061 }
1062
1063 static void hugetlbfs_destroy_inode(struct inode *inode)
1064 {
1065         hugetlbfs_inc_free_inodes(HUGETLBFS_SB(inode->i_sb));
1066         mpol_free_shared_policy(&HUGETLBFS_I(inode)->policy);
1067 }
1068
1069 static const struct address_space_operations hugetlbfs_aops = {
1070         .write_begin    = hugetlbfs_write_begin,
1071         .write_end      = hugetlbfs_write_end,
1072         .set_page_dirty = hugetlbfs_set_page_dirty,
1073         .migratepage    = hugetlbfs_migrate_page,
1074         .error_remove_page      = hugetlbfs_error_remove_page,
1075 };
1076
1077
1078 static void init_once(void *foo)
1079 {
1080         struct hugetlbfs_inode_info *ei = (struct hugetlbfs_inode_info *)foo;
1081
1082         inode_init_once(&ei->vfs_inode);
1083 }
1084
1085 const struct file_operations hugetlbfs_file_operations = {
1086         .read_iter              = hugetlbfs_read_iter,
1087         .mmap                   = hugetlbfs_file_mmap,
1088         .fsync                  = noop_fsync,
1089         .get_unmapped_area      = hugetlb_get_unmapped_area,
1090         .llseek                 = default_llseek,
1091         .fallocate              = hugetlbfs_fallocate,
1092 };
1093
1094 static const struct inode_operations hugetlbfs_dir_inode_operations = {
1095         .create         = hugetlbfs_create,
1096         .lookup         = simple_lookup,
1097         .link           = simple_link,
1098         .unlink         = simple_unlink,
1099         .symlink        = hugetlbfs_symlink,
1100         .mkdir          = hugetlbfs_mkdir,
1101         .rmdir          = simple_rmdir,
1102         .mknod          = hugetlbfs_mknod,
1103         .rename         = simple_rename,
1104         .setattr        = hugetlbfs_setattr,
1105 };
1106
1107 static const struct inode_operations hugetlbfs_inode_operations = {
1108         .setattr        = hugetlbfs_setattr,
1109 };
1110
1111 static const struct super_operations hugetlbfs_ops = {
1112         .alloc_inode    = hugetlbfs_alloc_inode,
1113         .free_inode     = hugetlbfs_free_inode,
1114         .destroy_inode  = hugetlbfs_destroy_inode,
1115         .evict_inode    = hugetlbfs_evict_inode,
1116         .statfs         = hugetlbfs_statfs,
1117         .put_super      = hugetlbfs_put_super,
1118         .show_options   = hugetlbfs_show_options,
1119 };
1120
1121 /*
1122  * Convert size option passed from command line to number of huge pages
1123  * in the pool specified by hstate.  Size option could be in bytes
1124  * (val_type == SIZE_STD) or percentage of the pool (val_type == SIZE_PERCENT).
1125  */
1126 static long
1127 hugetlbfs_size_to_hpages(struct hstate *h, unsigned long long size_opt,
1128                          enum hugetlbfs_size_type val_type)
1129 {
1130         if (val_type == NO_SIZE)
1131                 return -1;
1132
1133         if (val_type == SIZE_PERCENT) {
1134                 size_opt <<= huge_page_shift(h);
1135                 size_opt *= h->max_huge_pages;
1136                 do_div(size_opt, 100);
1137         }
1138
1139         size_opt >>= huge_page_shift(h);
1140         return size_opt;
1141 }
1142
1143 /*
1144  * Parse one mount parameter.
1145  */
1146 static int hugetlbfs_parse_param(struct fs_context *fc, struct fs_parameter *param)
1147 {
1148         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1149         struct fs_parse_result result;
1150         char *rest;
1151         unsigned long ps;
1152         int opt;
1153
1154         opt = fs_parse(fc, &hugetlb_fs_parameters, param, &result);
1155         if (opt < 0)
1156                 return opt;
1157
1158         switch (opt) {
1159         case Opt_uid:
1160                 ctx->uid = make_kuid(current_user_ns(), result.uint_32);
1161                 if (!uid_valid(ctx->uid))
1162                         goto bad_val;
1163                 return 0;
1164
1165         case Opt_gid:
1166                 ctx->gid = make_kgid(current_user_ns(), result.uint_32);
1167                 if (!gid_valid(ctx->gid))
1168                         goto bad_val;
1169                 return 0;
1170
1171         case Opt_mode:
1172                 ctx->mode = result.uint_32 & 01777U;
1173                 return 0;
1174
1175         case Opt_size:
1176                 /* memparse() will accept a K/M/G without a digit */
1177                 if (!isdigit(param->string[0]))
1178                         goto bad_val;
1179                 ctx->max_size_opt = memparse(param->string, &rest);
1180                 ctx->max_val_type = SIZE_STD;
1181                 if (*rest == '%')
1182                         ctx->max_val_type = SIZE_PERCENT;
1183                 return 0;
1184
1185         case Opt_nr_inodes:
1186                 /* memparse() will accept a K/M/G without a digit */
1187                 if (!isdigit(param->string[0]))
1188                         goto bad_val;
1189                 ctx->nr_inodes = memparse(param->string, &rest);
1190                 return 0;
1191
1192         case Opt_pagesize:
1193                 ps = memparse(param->string, &rest);
1194                 ctx->hstate = size_to_hstate(ps);
1195                 if (!ctx->hstate) {
1196                         pr_err("Unsupported page size %lu MB\n", ps >> 20);
1197                         return -EINVAL;
1198                 }
1199                 return 0;
1200
1201         case Opt_min_size:
1202                 /* memparse() will accept a K/M/G without a digit */
1203                 if (!isdigit(param->string[0]))
1204                         goto bad_val;
1205                 ctx->min_size_opt = memparse(param->string, &rest);
1206                 ctx->min_val_type = SIZE_STD;
1207                 if (*rest == '%')
1208                         ctx->min_val_type = SIZE_PERCENT;
1209                 return 0;
1210
1211         default:
1212                 return -EINVAL;
1213         }
1214
1215 bad_val:
1216         return invalf(fc, "hugetlbfs: Bad value '%s' for mount option '%s'\n",
1217                       param->string, param->key);
1218 }
1219
1220 /*
1221  * Validate the parsed options.
1222  */
1223 static int hugetlbfs_validate(struct fs_context *fc)
1224 {
1225         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1226
1227         /*
1228          * Use huge page pool size (in hstate) to convert the size
1229          * options to number of huge pages.  If NO_SIZE, -1 is returned.
1230          */
1231         ctx->max_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
1232                                                    ctx->max_size_opt,
1233                                                    ctx->max_val_type);
1234         ctx->min_hpages = hugetlbfs_size_to_hpages(ctx->hstate,
1235                                                    ctx->min_size_opt,
1236                                                    ctx->min_val_type);
1237
1238         /*
1239          * If max_size was specified, then min_size must be smaller
1240          */
1241         if (ctx->max_val_type > NO_SIZE &&
1242             ctx->min_hpages > ctx->max_hpages) {
1243                 pr_err("Minimum size can not be greater than maximum size\n");
1244                 return -EINVAL;
1245         }
1246
1247         return 0;
1248 }
1249
1250 static int
1251 hugetlbfs_fill_super(struct super_block *sb, struct fs_context *fc)
1252 {
1253         struct hugetlbfs_fs_context *ctx = fc->fs_private;
1254         struct hugetlbfs_sb_info *sbinfo;
1255
1256         sbinfo = kmalloc(sizeof(struct hugetlbfs_sb_info), GFP_KERNEL);
1257         if (!sbinfo)
1258                 return -ENOMEM;
1259         sb->s_fs_info = sbinfo;
1260         spin_lock_init(&sbinfo->stat_lock);
1261         sbinfo->hstate          = ctx->hstate;
1262         sbinfo->max_inodes      = ctx->nr_inodes;
1263         sbinfo->free_inodes     = ctx->nr_inodes;
1264         sbinfo->spool           = NULL;
1265         sbinfo->uid             = ctx->uid;
1266         sbinfo->gid             = ctx->gid;
1267         sbinfo->mode            = ctx->mode;
1268
1269         /*
1270          * Allocate and initialize subpool if maximum or minimum size is
1271          * specified.  Any needed reservations (for minimim size) are taken
1272          * taken when the subpool is created.
1273          */
1274         if (ctx->max_hpages != -1 || ctx->min_hpages != -1) {
1275                 sbinfo->spool = hugepage_new_subpool(ctx->hstate,
1276                                                      ctx->max_hpages,
1277                                                      ctx->min_hpages);
1278                 if (!sbinfo->spool)
1279                         goto out_free;
1280         }
1281         sb->s_maxbytes = MAX_LFS_FILESIZE;
1282         sb->s_blocksize = huge_page_size(ctx->hstate);
1283         sb->s_blocksize_bits = huge_page_shift(ctx->hstate);
1284         sb->s_magic = HUGETLBFS_MAGIC;
1285         sb->s_op = &hugetlbfs_ops;
1286         sb->s_time_gran = 1;
1287         sb->s_root = d_make_root(hugetlbfs_get_root(sb, ctx));
1288         if (!sb->s_root)
1289                 goto out_free;
1290         return 0;
1291 out_free:
1292         kfree(sbinfo->spool);
1293         kfree(sbinfo);
1294         return -ENOMEM;
1295 }
1296
1297 static int hugetlbfs_get_tree(struct fs_context *fc)
1298 {
1299         int err = hugetlbfs_validate(fc);
1300         if (err)
1301                 return err;
1302         return vfs_get_super(fc, vfs_get_independent_super, hugetlbfs_fill_super);
1303 }
1304
1305 static void hugetlbfs_fs_context_free(struct fs_context *fc)
1306 {
1307         kfree(fc->fs_private);
1308 }
1309
1310 static const struct fs_context_operations hugetlbfs_fs_context_ops = {
1311         .free           = hugetlbfs_fs_context_free,
1312         .parse_param    = hugetlbfs_parse_param,
1313         .get_tree       = hugetlbfs_get_tree,
1314 };
1315
1316 static int hugetlbfs_init_fs_context(struct fs_context *fc)
1317 {
1318         struct hugetlbfs_fs_context *ctx;
1319
1320         ctx = kzalloc(sizeof(struct hugetlbfs_fs_context), GFP_KERNEL);
1321         if (!ctx)
1322                 return -ENOMEM;
1323
1324         ctx->max_hpages = -1; /* No limit on size by default */
1325         ctx->nr_inodes  = -1; /* No limit on number of inodes by default */
1326         ctx->uid        = current_fsuid();
1327         ctx->gid        = current_fsgid();
1328         ctx->mode       = 0755;
1329         ctx->hstate     = &default_hstate;
1330         ctx->min_hpages = -1; /* No default minimum size */
1331         ctx->max_val_type = NO_SIZE;
1332         ctx->min_val_type = NO_SIZE;
1333         fc->fs_private = ctx;
1334         fc->ops = &hugetlbfs_fs_context_ops;
1335         return 0;
1336 }
1337
1338 static struct file_system_type hugetlbfs_fs_type = {
1339         .name                   = "hugetlbfs",
1340         .init_fs_context        = hugetlbfs_init_fs_context,
1341         .parameters             = &hugetlb_fs_parameters,
1342         .kill_sb                = kill_litter_super,
1343 };
1344
1345 static struct vfsmount *hugetlbfs_vfsmount[HUGE_MAX_HSTATE];
1346
1347 static int can_do_hugetlb_shm(void)
1348 {
1349         kgid_t shm_group;
1350         shm_group = make_kgid(&init_user_ns, sysctl_hugetlb_shm_group);
1351         return capable(CAP_IPC_LOCK) || in_group_p(shm_group);
1352 }
1353
1354 static int get_hstate_idx(int page_size_log)
1355 {
1356         struct hstate *h = hstate_sizelog(page_size_log);
1357
1358         if (!h)
1359                 return -1;
1360         return h - hstates;
1361 }
1362
1363 /*
1364  * Note that size should be aligned to proper hugepage size in caller side,
1365  * otherwise hugetlb_reserve_pages reserves one less hugepages than intended.
1366  */
1367 struct file *hugetlb_file_setup(const char *name, size_t size,
1368                                 vm_flags_t acctflag, struct user_struct **user,
1369                                 int creat_flags, int page_size_log)
1370 {
1371         struct inode *inode;
1372         struct vfsmount *mnt;
1373         int hstate_idx;
1374         struct file *file;
1375
1376         hstate_idx = get_hstate_idx(page_size_log);
1377         if (hstate_idx < 0)
1378                 return ERR_PTR(-ENODEV);
1379
1380         *user = NULL;
1381         mnt = hugetlbfs_vfsmount[hstate_idx];
1382         if (!mnt)
1383                 return ERR_PTR(-ENOENT);
1384
1385         if (creat_flags == HUGETLB_SHMFS_INODE && !can_do_hugetlb_shm()) {
1386                 *user = current_user();
1387                 if (user_shm_lock(size, *user)) {
1388                         task_lock(current);
1389                         pr_warn_once("%s (%d): Using mlock ulimits for SHM_HUGETLB is deprecated\n",
1390                                 current->comm, current->pid);
1391                         task_unlock(current);
1392                 } else {
1393                         *user = NULL;
1394                         return ERR_PTR(-EPERM);
1395                 }
1396         }
1397
1398         file = ERR_PTR(-ENOSPC);
1399         inode = hugetlbfs_get_inode(mnt->mnt_sb, NULL, S_IFREG | S_IRWXUGO, 0);
1400         if (!inode)
1401                 goto out;
1402         if (creat_flags == HUGETLB_SHMFS_INODE)
1403                 inode->i_flags |= S_PRIVATE;
1404
1405         inode->i_size = size;
1406         clear_nlink(inode);
1407
1408         if (hugetlb_reserve_pages(inode, 0,
1409                         size >> huge_page_shift(hstate_inode(inode)), NULL,
1410                         acctflag))
1411                 file = ERR_PTR(-ENOMEM);
1412         else
1413                 file = alloc_file_pseudo(inode, mnt, name, O_RDWR,
1414                                         &hugetlbfs_file_operations);
1415         if (!IS_ERR(file))
1416                 return file;
1417
1418         iput(inode);
1419 out:
1420         if (*user) {
1421                 user_shm_unlock(size, *user);
1422                 *user = NULL;
1423         }
1424         return file;
1425 }
1426
1427 static struct vfsmount *__init mount_one_hugetlbfs(struct hstate *h)
1428 {
1429         struct fs_context *fc;
1430         struct vfsmount *mnt;
1431
1432         fc = fs_context_for_mount(&hugetlbfs_fs_type, SB_KERNMOUNT);
1433         if (IS_ERR(fc)) {
1434                 mnt = ERR_CAST(fc);
1435         } else {
1436                 struct hugetlbfs_fs_context *ctx = fc->fs_private;
1437                 ctx->hstate = h;
1438                 mnt = fc_mount(fc);
1439                 put_fs_context(fc);
1440         }
1441         if (IS_ERR(mnt))
1442                 pr_err("Cannot mount internal hugetlbfs for page size %uK",
1443                        1U << (h->order + PAGE_SHIFT - 10));
1444         return mnt;
1445 }
1446
1447 static int __init init_hugetlbfs_fs(void)
1448 {
1449         struct vfsmount *mnt;
1450         struct hstate *h;
1451         int error;
1452         int i;
1453
1454         if (!hugepages_supported()) {
1455                 pr_info("disabling because there are no supported hugepage sizes\n");
1456                 return -ENOTSUPP;
1457         }
1458
1459         error = -ENOMEM;
1460         hugetlbfs_inode_cachep = kmem_cache_create("hugetlbfs_inode_cache",
1461                                         sizeof(struct hugetlbfs_inode_info),
1462                                         0, SLAB_ACCOUNT, init_once);
1463         if (hugetlbfs_inode_cachep == NULL)
1464                 goto out2;
1465
1466         error = register_filesystem(&hugetlbfs_fs_type);
1467         if (error)
1468                 goto out;
1469
1470         i = 0;
1471         for_each_hstate(h) {
1472                 mnt = mount_one_hugetlbfs(h);
1473                 if (IS_ERR(mnt) && i == 0) {
1474                         error = PTR_ERR(mnt);
1475                         goto out;
1476                 }
1477                 hugetlbfs_vfsmount[i] = mnt;
1478                 i++;
1479         }
1480
1481         return 0;
1482
1483  out:
1484         kmem_cache_destroy(hugetlbfs_inode_cachep);
1485  out2:
1486         return error;
1487 }
1488 fs_initcall(init_hugetlbfs_fs)