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Linux/fs/hugetlbfs/inode.c

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

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