]> git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - mm/shmem.c
Merge tag 'dm-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/device...
[mirror_ubuntu-artful-kernel.git] / mm / shmem.c
1 /*
2 * Resizable virtual memory filesystem for Linux.
3 *
4 * Copyright (C) 2000 Linus Torvalds.
5 * 2000 Transmeta Corp.
6 * 2000-2001 Christoph Rohland
7 * 2000-2001 SAP AG
8 * 2002 Red Hat Inc.
9 * Copyright (C) 2002-2011 Hugh Dickins.
10 * Copyright (C) 2011 Google Inc.
11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
13 *
14 * Extended attribute support for tmpfs:
15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
17 *
18 * tiny-shmem:
19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
20 *
21 * This file is released under the GPL.
22 */
23
24 #include <linux/fs.h>
25 #include <linux/init.h>
26 #include <linux/vfs.h>
27 #include <linux/mount.h>
28 #include <linux/ramfs.h>
29 #include <linux/pagemap.h>
30 #include <linux/file.h>
31 #include <linux/mm.h>
32 #include <linux/export.h>
33 #include <linux/swap.h>
34 #include <linux/uio.h>
35 #include <linux/khugepaged.h>
36
37 #include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */
38
39 static struct vfsmount *shm_mnt;
40
41 #ifdef CONFIG_SHMEM
42 /*
43 * This virtual memory filesystem is heavily based on the ramfs. It
44 * extends ramfs by the ability to use swap and honor resource limits
45 * which makes it a completely usable filesystem.
46 */
47
48 #include <linux/xattr.h>
49 #include <linux/exportfs.h>
50 #include <linux/posix_acl.h>
51 #include <linux/posix_acl_xattr.h>
52 #include <linux/mman.h>
53 #include <linux/string.h>
54 #include <linux/slab.h>
55 #include <linux/backing-dev.h>
56 #include <linux/shmem_fs.h>
57 #include <linux/writeback.h>
58 #include <linux/blkdev.h>
59 #include <linux/pagevec.h>
60 #include <linux/percpu_counter.h>
61 #include <linux/falloc.h>
62 #include <linux/splice.h>
63 #include <linux/security.h>
64 #include <linux/swapops.h>
65 #include <linux/mempolicy.h>
66 #include <linux/namei.h>
67 #include <linux/ctype.h>
68 #include <linux/migrate.h>
69 #include <linux/highmem.h>
70 #include <linux/seq_file.h>
71 #include <linux/magic.h>
72 #include <linux/syscalls.h>
73 #include <linux/fcntl.h>
74 #include <uapi/linux/memfd.h>
75 #include <linux/userfaultfd_k.h>
76 #include <linux/rmap.h>
77
78 #include <linux/uaccess.h>
79 #include <asm/pgtable.h>
80
81 #include "internal.h"
82
83 #define BLOCKS_PER_PAGE (PAGE_SIZE/512)
84 #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
85
86 /* Pretend that each entry is of this size in directory's i_size */
87 #define BOGO_DIRENT_SIZE 20
88
89 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
90 #define SHORT_SYMLINK_LEN 128
91
92 /*
93 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
94 * inode->i_private (with i_mutex making sure that it has only one user at
95 * a time): we would prefer not to enlarge the shmem inode just for that.
96 */
97 struct shmem_falloc {
98 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
99 pgoff_t start; /* start of range currently being fallocated */
100 pgoff_t next; /* the next page offset to be fallocated */
101 pgoff_t nr_falloced; /* how many new pages have been fallocated */
102 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
103 };
104
105 #ifdef CONFIG_TMPFS
106 static unsigned long shmem_default_max_blocks(void)
107 {
108 return totalram_pages / 2;
109 }
110
111 static unsigned long shmem_default_max_inodes(void)
112 {
113 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
114 }
115 #endif
116
117 static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
118 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
119 struct shmem_inode_info *info, pgoff_t index);
120 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
121 struct page **pagep, enum sgp_type sgp,
122 gfp_t gfp, struct vm_area_struct *vma,
123 struct vm_fault *vmf, int *fault_type);
124
125 int shmem_getpage(struct inode *inode, pgoff_t index,
126 struct page **pagep, enum sgp_type sgp)
127 {
128 return shmem_getpage_gfp(inode, index, pagep, sgp,
129 mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
130 }
131
132 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
133 {
134 return sb->s_fs_info;
135 }
136
137 /*
138 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
139 * for shared memory and for shared anonymous (/dev/zero) mappings
140 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
141 * consistent with the pre-accounting of private mappings ...
142 */
143 static inline int shmem_acct_size(unsigned long flags, loff_t size)
144 {
145 return (flags & VM_NORESERVE) ?
146 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
147 }
148
149 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
150 {
151 if (!(flags & VM_NORESERVE))
152 vm_unacct_memory(VM_ACCT(size));
153 }
154
155 static inline int shmem_reacct_size(unsigned long flags,
156 loff_t oldsize, loff_t newsize)
157 {
158 if (!(flags & VM_NORESERVE)) {
159 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
160 return security_vm_enough_memory_mm(current->mm,
161 VM_ACCT(newsize) - VM_ACCT(oldsize));
162 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
163 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
164 }
165 return 0;
166 }
167
168 /*
169 * ... whereas tmpfs objects are accounted incrementally as
170 * pages are allocated, in order to allow large sparse files.
171 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
172 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
173 */
174 static inline int shmem_acct_block(unsigned long flags, long pages)
175 {
176 if (!(flags & VM_NORESERVE))
177 return 0;
178
179 return security_vm_enough_memory_mm(current->mm,
180 pages * VM_ACCT(PAGE_SIZE));
181 }
182
183 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
184 {
185 if (flags & VM_NORESERVE)
186 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
187 }
188
189 static const struct super_operations shmem_ops;
190 static const struct address_space_operations shmem_aops;
191 static const struct file_operations shmem_file_operations;
192 static const struct inode_operations shmem_inode_operations;
193 static const struct inode_operations shmem_dir_inode_operations;
194 static const struct inode_operations shmem_special_inode_operations;
195 static const struct vm_operations_struct shmem_vm_ops;
196 static struct file_system_type shmem_fs_type;
197
198 bool vma_is_shmem(struct vm_area_struct *vma)
199 {
200 return vma->vm_ops == &shmem_vm_ops;
201 }
202
203 static LIST_HEAD(shmem_swaplist);
204 static DEFINE_MUTEX(shmem_swaplist_mutex);
205
206 static int shmem_reserve_inode(struct super_block *sb)
207 {
208 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
209 if (sbinfo->max_inodes) {
210 spin_lock(&sbinfo->stat_lock);
211 if (!sbinfo->free_inodes) {
212 spin_unlock(&sbinfo->stat_lock);
213 return -ENOSPC;
214 }
215 sbinfo->free_inodes--;
216 spin_unlock(&sbinfo->stat_lock);
217 }
218 return 0;
219 }
220
221 static void shmem_free_inode(struct super_block *sb)
222 {
223 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
224 if (sbinfo->max_inodes) {
225 spin_lock(&sbinfo->stat_lock);
226 sbinfo->free_inodes++;
227 spin_unlock(&sbinfo->stat_lock);
228 }
229 }
230
231 /**
232 * shmem_recalc_inode - recalculate the block usage of an inode
233 * @inode: inode to recalc
234 *
235 * We have to calculate the free blocks since the mm can drop
236 * undirtied hole pages behind our back.
237 *
238 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
239 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
240 *
241 * It has to be called with the spinlock held.
242 */
243 static void shmem_recalc_inode(struct inode *inode)
244 {
245 struct shmem_inode_info *info = SHMEM_I(inode);
246 long freed;
247
248 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
249 if (freed > 0) {
250 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
251 if (sbinfo->max_blocks)
252 percpu_counter_add(&sbinfo->used_blocks, -freed);
253 info->alloced -= freed;
254 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
255 shmem_unacct_blocks(info->flags, freed);
256 }
257 }
258
259 bool shmem_charge(struct inode *inode, long pages)
260 {
261 struct shmem_inode_info *info = SHMEM_I(inode);
262 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
263 unsigned long flags;
264
265 if (shmem_acct_block(info->flags, pages))
266 return false;
267 spin_lock_irqsave(&info->lock, flags);
268 info->alloced += pages;
269 inode->i_blocks += pages * BLOCKS_PER_PAGE;
270 shmem_recalc_inode(inode);
271 spin_unlock_irqrestore(&info->lock, flags);
272 inode->i_mapping->nrpages += pages;
273
274 if (!sbinfo->max_blocks)
275 return true;
276 if (percpu_counter_compare(&sbinfo->used_blocks,
277 sbinfo->max_blocks - pages) > 0) {
278 inode->i_mapping->nrpages -= pages;
279 spin_lock_irqsave(&info->lock, flags);
280 info->alloced -= pages;
281 shmem_recalc_inode(inode);
282 spin_unlock_irqrestore(&info->lock, flags);
283 shmem_unacct_blocks(info->flags, pages);
284 return false;
285 }
286 percpu_counter_add(&sbinfo->used_blocks, pages);
287 return true;
288 }
289
290 void shmem_uncharge(struct inode *inode, long pages)
291 {
292 struct shmem_inode_info *info = SHMEM_I(inode);
293 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
294 unsigned long flags;
295
296 spin_lock_irqsave(&info->lock, flags);
297 info->alloced -= pages;
298 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
299 shmem_recalc_inode(inode);
300 spin_unlock_irqrestore(&info->lock, flags);
301
302 if (sbinfo->max_blocks)
303 percpu_counter_sub(&sbinfo->used_blocks, pages);
304 shmem_unacct_blocks(info->flags, pages);
305 }
306
307 /*
308 * Replace item expected in radix tree by a new item, while holding tree lock.
309 */
310 static int shmem_radix_tree_replace(struct address_space *mapping,
311 pgoff_t index, void *expected, void *replacement)
312 {
313 struct radix_tree_node *node;
314 void **pslot;
315 void *item;
316
317 VM_BUG_ON(!expected);
318 VM_BUG_ON(!replacement);
319 item = __radix_tree_lookup(&mapping->page_tree, index, &node, &pslot);
320 if (!item)
321 return -ENOENT;
322 if (item != expected)
323 return -ENOENT;
324 __radix_tree_replace(&mapping->page_tree, node, pslot,
325 replacement, NULL, NULL);
326 return 0;
327 }
328
329 /*
330 * Sometimes, before we decide whether to proceed or to fail, we must check
331 * that an entry was not already brought back from swap by a racing thread.
332 *
333 * Checking page is not enough: by the time a SwapCache page is locked, it
334 * might be reused, and again be SwapCache, using the same swap as before.
335 */
336 static bool shmem_confirm_swap(struct address_space *mapping,
337 pgoff_t index, swp_entry_t swap)
338 {
339 void *item;
340
341 rcu_read_lock();
342 item = radix_tree_lookup(&mapping->page_tree, index);
343 rcu_read_unlock();
344 return item == swp_to_radix_entry(swap);
345 }
346
347 /*
348 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
349 *
350 * SHMEM_HUGE_NEVER:
351 * disables huge pages for the mount;
352 * SHMEM_HUGE_ALWAYS:
353 * enables huge pages for the mount;
354 * SHMEM_HUGE_WITHIN_SIZE:
355 * only allocate huge pages if the page will be fully within i_size,
356 * also respect fadvise()/madvise() hints;
357 * SHMEM_HUGE_ADVISE:
358 * only allocate huge pages if requested with fadvise()/madvise();
359 */
360
361 #define SHMEM_HUGE_NEVER 0
362 #define SHMEM_HUGE_ALWAYS 1
363 #define SHMEM_HUGE_WITHIN_SIZE 2
364 #define SHMEM_HUGE_ADVISE 3
365
366 /*
367 * Special values.
368 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
369 *
370 * SHMEM_HUGE_DENY:
371 * disables huge on shm_mnt and all mounts, for emergency use;
372 * SHMEM_HUGE_FORCE:
373 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
374 *
375 */
376 #define SHMEM_HUGE_DENY (-1)
377 #define SHMEM_HUGE_FORCE (-2)
378
379 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
380 /* ifdef here to avoid bloating shmem.o when not necessary */
381
382 int shmem_huge __read_mostly;
383
384 #if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
385 static int shmem_parse_huge(const char *str)
386 {
387 if (!strcmp(str, "never"))
388 return SHMEM_HUGE_NEVER;
389 if (!strcmp(str, "always"))
390 return SHMEM_HUGE_ALWAYS;
391 if (!strcmp(str, "within_size"))
392 return SHMEM_HUGE_WITHIN_SIZE;
393 if (!strcmp(str, "advise"))
394 return SHMEM_HUGE_ADVISE;
395 if (!strcmp(str, "deny"))
396 return SHMEM_HUGE_DENY;
397 if (!strcmp(str, "force"))
398 return SHMEM_HUGE_FORCE;
399 return -EINVAL;
400 }
401
402 static const char *shmem_format_huge(int huge)
403 {
404 switch (huge) {
405 case SHMEM_HUGE_NEVER:
406 return "never";
407 case SHMEM_HUGE_ALWAYS:
408 return "always";
409 case SHMEM_HUGE_WITHIN_SIZE:
410 return "within_size";
411 case SHMEM_HUGE_ADVISE:
412 return "advise";
413 case SHMEM_HUGE_DENY:
414 return "deny";
415 case SHMEM_HUGE_FORCE:
416 return "force";
417 default:
418 VM_BUG_ON(1);
419 return "bad_val";
420 }
421 }
422 #endif
423
424 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
425 struct shrink_control *sc, unsigned long nr_to_split)
426 {
427 LIST_HEAD(list), *pos, *next;
428 LIST_HEAD(to_remove);
429 struct inode *inode;
430 struct shmem_inode_info *info;
431 struct page *page;
432 unsigned long batch = sc ? sc->nr_to_scan : 128;
433 int removed = 0, split = 0;
434
435 if (list_empty(&sbinfo->shrinklist))
436 return SHRINK_STOP;
437
438 spin_lock(&sbinfo->shrinklist_lock);
439 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
440 info = list_entry(pos, struct shmem_inode_info, shrinklist);
441
442 /* pin the inode */
443 inode = igrab(&info->vfs_inode);
444
445 /* inode is about to be evicted */
446 if (!inode) {
447 list_del_init(&info->shrinklist);
448 removed++;
449 goto next;
450 }
451
452 /* Check if there's anything to gain */
453 if (round_up(inode->i_size, PAGE_SIZE) ==
454 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
455 list_move(&info->shrinklist, &to_remove);
456 removed++;
457 goto next;
458 }
459
460 list_move(&info->shrinklist, &list);
461 next:
462 if (!--batch)
463 break;
464 }
465 spin_unlock(&sbinfo->shrinklist_lock);
466
467 list_for_each_safe(pos, next, &to_remove) {
468 info = list_entry(pos, struct shmem_inode_info, shrinklist);
469 inode = &info->vfs_inode;
470 list_del_init(&info->shrinklist);
471 iput(inode);
472 }
473
474 list_for_each_safe(pos, next, &list) {
475 int ret;
476
477 info = list_entry(pos, struct shmem_inode_info, shrinklist);
478 inode = &info->vfs_inode;
479
480 if (nr_to_split && split >= nr_to_split) {
481 iput(inode);
482 continue;
483 }
484
485 page = find_lock_page(inode->i_mapping,
486 (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
487 if (!page)
488 goto drop;
489
490 if (!PageTransHuge(page)) {
491 unlock_page(page);
492 put_page(page);
493 goto drop;
494 }
495
496 ret = split_huge_page(page);
497 unlock_page(page);
498 put_page(page);
499
500 if (ret) {
501 /* split failed: leave it on the list */
502 iput(inode);
503 continue;
504 }
505
506 split++;
507 drop:
508 list_del_init(&info->shrinklist);
509 removed++;
510 iput(inode);
511 }
512
513 spin_lock(&sbinfo->shrinklist_lock);
514 list_splice_tail(&list, &sbinfo->shrinklist);
515 sbinfo->shrinklist_len -= removed;
516 spin_unlock(&sbinfo->shrinklist_lock);
517
518 return split;
519 }
520
521 static long shmem_unused_huge_scan(struct super_block *sb,
522 struct shrink_control *sc)
523 {
524 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
525
526 if (!READ_ONCE(sbinfo->shrinklist_len))
527 return SHRINK_STOP;
528
529 return shmem_unused_huge_shrink(sbinfo, sc, 0);
530 }
531
532 static long shmem_unused_huge_count(struct super_block *sb,
533 struct shrink_control *sc)
534 {
535 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
536 return READ_ONCE(sbinfo->shrinklist_len);
537 }
538 #else /* !CONFIG_TRANSPARENT_HUGE_PAGECACHE */
539
540 #define shmem_huge SHMEM_HUGE_DENY
541
542 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
543 struct shrink_control *sc, unsigned long nr_to_split)
544 {
545 return 0;
546 }
547 #endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
548
549 /*
550 * Like add_to_page_cache_locked, but error if expected item has gone.
551 */
552 static int shmem_add_to_page_cache(struct page *page,
553 struct address_space *mapping,
554 pgoff_t index, void *expected)
555 {
556 int error, nr = hpage_nr_pages(page);
557
558 VM_BUG_ON_PAGE(PageTail(page), page);
559 VM_BUG_ON_PAGE(index != round_down(index, nr), page);
560 VM_BUG_ON_PAGE(!PageLocked(page), page);
561 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
562 VM_BUG_ON(expected && PageTransHuge(page));
563
564 page_ref_add(page, nr);
565 page->mapping = mapping;
566 page->index = index;
567
568 spin_lock_irq(&mapping->tree_lock);
569 if (PageTransHuge(page)) {
570 void __rcu **results;
571 pgoff_t idx;
572 int i;
573
574 error = 0;
575 if (radix_tree_gang_lookup_slot(&mapping->page_tree,
576 &results, &idx, index, 1) &&
577 idx < index + HPAGE_PMD_NR) {
578 error = -EEXIST;
579 }
580
581 if (!error) {
582 for (i = 0; i < HPAGE_PMD_NR; i++) {
583 error = radix_tree_insert(&mapping->page_tree,
584 index + i, page + i);
585 VM_BUG_ON(error);
586 }
587 count_vm_event(THP_FILE_ALLOC);
588 }
589 } else if (!expected) {
590 error = radix_tree_insert(&mapping->page_tree, index, page);
591 } else {
592 error = shmem_radix_tree_replace(mapping, index, expected,
593 page);
594 }
595
596 if (!error) {
597 mapping->nrpages += nr;
598 if (PageTransHuge(page))
599 __inc_node_page_state(page, NR_SHMEM_THPS);
600 __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
601 __mod_node_page_state(page_pgdat(page), NR_SHMEM, nr);
602 spin_unlock_irq(&mapping->tree_lock);
603 } else {
604 page->mapping = NULL;
605 spin_unlock_irq(&mapping->tree_lock);
606 page_ref_sub(page, nr);
607 }
608 return error;
609 }
610
611 /*
612 * Like delete_from_page_cache, but substitutes swap for page.
613 */
614 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
615 {
616 struct address_space *mapping = page->mapping;
617 int error;
618
619 VM_BUG_ON_PAGE(PageCompound(page), page);
620
621 spin_lock_irq(&mapping->tree_lock);
622 error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
623 page->mapping = NULL;
624 mapping->nrpages--;
625 __dec_node_page_state(page, NR_FILE_PAGES);
626 __dec_node_page_state(page, NR_SHMEM);
627 spin_unlock_irq(&mapping->tree_lock);
628 put_page(page);
629 BUG_ON(error);
630 }
631
632 /*
633 * Remove swap entry from radix tree, free the swap and its page cache.
634 */
635 static int shmem_free_swap(struct address_space *mapping,
636 pgoff_t index, void *radswap)
637 {
638 void *old;
639
640 spin_lock_irq(&mapping->tree_lock);
641 old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
642 spin_unlock_irq(&mapping->tree_lock);
643 if (old != radswap)
644 return -ENOENT;
645 free_swap_and_cache(radix_to_swp_entry(radswap));
646 return 0;
647 }
648
649 /*
650 * Determine (in bytes) how many of the shmem object's pages mapped by the
651 * given offsets are swapped out.
652 *
653 * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU,
654 * as long as the inode doesn't go away and racy results are not a problem.
655 */
656 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
657 pgoff_t start, pgoff_t end)
658 {
659 struct radix_tree_iter iter;
660 void **slot;
661 struct page *page;
662 unsigned long swapped = 0;
663
664 rcu_read_lock();
665
666 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
667 if (iter.index >= end)
668 break;
669
670 page = radix_tree_deref_slot(slot);
671
672 if (radix_tree_deref_retry(page)) {
673 slot = radix_tree_iter_retry(&iter);
674 continue;
675 }
676
677 if (radix_tree_exceptional_entry(page))
678 swapped++;
679
680 if (need_resched()) {
681 slot = radix_tree_iter_resume(slot, &iter);
682 cond_resched_rcu();
683 }
684 }
685
686 rcu_read_unlock();
687
688 return swapped << PAGE_SHIFT;
689 }
690
691 /*
692 * Determine (in bytes) how many of the shmem object's pages mapped by the
693 * given vma is swapped out.
694 *
695 * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU,
696 * as long as the inode doesn't go away and racy results are not a problem.
697 */
698 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
699 {
700 struct inode *inode = file_inode(vma->vm_file);
701 struct shmem_inode_info *info = SHMEM_I(inode);
702 struct address_space *mapping = inode->i_mapping;
703 unsigned long swapped;
704
705 /* Be careful as we don't hold info->lock */
706 swapped = READ_ONCE(info->swapped);
707
708 /*
709 * The easier cases are when the shmem object has nothing in swap, or
710 * the vma maps it whole. Then we can simply use the stats that we
711 * already track.
712 */
713 if (!swapped)
714 return 0;
715
716 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
717 return swapped << PAGE_SHIFT;
718
719 /* Here comes the more involved part */
720 return shmem_partial_swap_usage(mapping,
721 linear_page_index(vma, vma->vm_start),
722 linear_page_index(vma, vma->vm_end));
723 }
724
725 /*
726 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
727 */
728 void shmem_unlock_mapping(struct address_space *mapping)
729 {
730 struct pagevec pvec;
731 pgoff_t indices[PAGEVEC_SIZE];
732 pgoff_t index = 0;
733
734 pagevec_init(&pvec, 0);
735 /*
736 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
737 */
738 while (!mapping_unevictable(mapping)) {
739 /*
740 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
741 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
742 */
743 pvec.nr = find_get_entries(mapping, index,
744 PAGEVEC_SIZE, pvec.pages, indices);
745 if (!pvec.nr)
746 break;
747 index = indices[pvec.nr - 1] + 1;
748 pagevec_remove_exceptionals(&pvec);
749 check_move_unevictable_pages(pvec.pages, pvec.nr);
750 pagevec_release(&pvec);
751 cond_resched();
752 }
753 }
754
755 /*
756 * Remove range of pages and swap entries from radix tree, and free them.
757 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
758 */
759 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
760 bool unfalloc)
761 {
762 struct address_space *mapping = inode->i_mapping;
763 struct shmem_inode_info *info = SHMEM_I(inode);
764 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
765 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
766 unsigned int partial_start = lstart & (PAGE_SIZE - 1);
767 unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1);
768 struct pagevec pvec;
769 pgoff_t indices[PAGEVEC_SIZE];
770 long nr_swaps_freed = 0;
771 pgoff_t index;
772 int i;
773
774 if (lend == -1)
775 end = -1; /* unsigned, so actually very big */
776
777 pagevec_init(&pvec, 0);
778 index = start;
779 while (index < end) {
780 pvec.nr = find_get_entries(mapping, index,
781 min(end - index, (pgoff_t)PAGEVEC_SIZE),
782 pvec.pages, indices);
783 if (!pvec.nr)
784 break;
785 for (i = 0; i < pagevec_count(&pvec); i++) {
786 struct page *page = pvec.pages[i];
787
788 index = indices[i];
789 if (index >= end)
790 break;
791
792 if (radix_tree_exceptional_entry(page)) {
793 if (unfalloc)
794 continue;
795 nr_swaps_freed += !shmem_free_swap(mapping,
796 index, page);
797 continue;
798 }
799
800 VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
801
802 if (!trylock_page(page))
803 continue;
804
805 if (PageTransTail(page)) {
806 /* Middle of THP: zero out the page */
807 clear_highpage(page);
808 unlock_page(page);
809 continue;
810 } else if (PageTransHuge(page)) {
811 if (index == round_down(end, HPAGE_PMD_NR)) {
812 /*
813 * Range ends in the middle of THP:
814 * zero out the page
815 */
816 clear_highpage(page);
817 unlock_page(page);
818 continue;
819 }
820 index += HPAGE_PMD_NR - 1;
821 i += HPAGE_PMD_NR - 1;
822 }
823
824 if (!unfalloc || !PageUptodate(page)) {
825 VM_BUG_ON_PAGE(PageTail(page), page);
826 if (page_mapping(page) == mapping) {
827 VM_BUG_ON_PAGE(PageWriteback(page), page);
828 truncate_inode_page(mapping, page);
829 }
830 }
831 unlock_page(page);
832 }
833 pagevec_remove_exceptionals(&pvec);
834 pagevec_release(&pvec);
835 cond_resched();
836 index++;
837 }
838
839 if (partial_start) {
840 struct page *page = NULL;
841 shmem_getpage(inode, start - 1, &page, SGP_READ);
842 if (page) {
843 unsigned int top = PAGE_SIZE;
844 if (start > end) {
845 top = partial_end;
846 partial_end = 0;
847 }
848 zero_user_segment(page, partial_start, top);
849 set_page_dirty(page);
850 unlock_page(page);
851 put_page(page);
852 }
853 }
854 if (partial_end) {
855 struct page *page = NULL;
856 shmem_getpage(inode, end, &page, SGP_READ);
857 if (page) {
858 zero_user_segment(page, 0, partial_end);
859 set_page_dirty(page);
860 unlock_page(page);
861 put_page(page);
862 }
863 }
864 if (start >= end)
865 return;
866
867 index = start;
868 while (index < end) {
869 cond_resched();
870
871 pvec.nr = find_get_entries(mapping, index,
872 min(end - index, (pgoff_t)PAGEVEC_SIZE),
873 pvec.pages, indices);
874 if (!pvec.nr) {
875 /* If all gone or hole-punch or unfalloc, we're done */
876 if (index == start || end != -1)
877 break;
878 /* But if truncating, restart to make sure all gone */
879 index = start;
880 continue;
881 }
882 for (i = 0; i < pagevec_count(&pvec); i++) {
883 struct page *page = pvec.pages[i];
884
885 index = indices[i];
886 if (index >= end)
887 break;
888
889 if (radix_tree_exceptional_entry(page)) {
890 if (unfalloc)
891 continue;
892 if (shmem_free_swap(mapping, index, page)) {
893 /* Swap was replaced by page: retry */
894 index--;
895 break;
896 }
897 nr_swaps_freed++;
898 continue;
899 }
900
901 lock_page(page);
902
903 if (PageTransTail(page)) {
904 /* Middle of THP: zero out the page */
905 clear_highpage(page);
906 unlock_page(page);
907 /*
908 * Partial thp truncate due 'start' in middle
909 * of THP: don't need to look on these pages
910 * again on !pvec.nr restart.
911 */
912 if (index != round_down(end, HPAGE_PMD_NR))
913 start++;
914 continue;
915 } else if (PageTransHuge(page)) {
916 if (index == round_down(end, HPAGE_PMD_NR)) {
917 /*
918 * Range ends in the middle of THP:
919 * zero out the page
920 */
921 clear_highpage(page);
922 unlock_page(page);
923 continue;
924 }
925 index += HPAGE_PMD_NR - 1;
926 i += HPAGE_PMD_NR - 1;
927 }
928
929 if (!unfalloc || !PageUptodate(page)) {
930 VM_BUG_ON_PAGE(PageTail(page), page);
931 if (page_mapping(page) == mapping) {
932 VM_BUG_ON_PAGE(PageWriteback(page), page);
933 truncate_inode_page(mapping, page);
934 } else {
935 /* Page was replaced by swap: retry */
936 unlock_page(page);
937 index--;
938 break;
939 }
940 }
941 unlock_page(page);
942 }
943 pagevec_remove_exceptionals(&pvec);
944 pagevec_release(&pvec);
945 index++;
946 }
947
948 spin_lock_irq(&info->lock);
949 info->swapped -= nr_swaps_freed;
950 shmem_recalc_inode(inode);
951 spin_unlock_irq(&info->lock);
952 }
953
954 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
955 {
956 shmem_undo_range(inode, lstart, lend, false);
957 inode->i_ctime = inode->i_mtime = current_time(inode);
958 }
959 EXPORT_SYMBOL_GPL(shmem_truncate_range);
960
961 static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry,
962 struct kstat *stat)
963 {
964 struct inode *inode = dentry->d_inode;
965 struct shmem_inode_info *info = SHMEM_I(inode);
966
967 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
968 spin_lock_irq(&info->lock);
969 shmem_recalc_inode(inode);
970 spin_unlock_irq(&info->lock);
971 }
972 generic_fillattr(inode, stat);
973 return 0;
974 }
975
976 static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
977 {
978 struct inode *inode = d_inode(dentry);
979 struct shmem_inode_info *info = SHMEM_I(inode);
980 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
981 int error;
982
983 error = setattr_prepare(dentry, attr);
984 if (error)
985 return error;
986
987 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
988 loff_t oldsize = inode->i_size;
989 loff_t newsize = attr->ia_size;
990
991 /* protected by i_mutex */
992 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
993 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
994 return -EPERM;
995
996 if (newsize != oldsize) {
997 error = shmem_reacct_size(SHMEM_I(inode)->flags,
998 oldsize, newsize);
999 if (error)
1000 return error;
1001 i_size_write(inode, newsize);
1002 inode->i_ctime = inode->i_mtime = current_time(inode);
1003 }
1004 if (newsize <= oldsize) {
1005 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1006 if (oldsize > holebegin)
1007 unmap_mapping_range(inode->i_mapping,
1008 holebegin, 0, 1);
1009 if (info->alloced)
1010 shmem_truncate_range(inode,
1011 newsize, (loff_t)-1);
1012 /* unmap again to remove racily COWed private pages */
1013 if (oldsize > holebegin)
1014 unmap_mapping_range(inode->i_mapping,
1015 holebegin, 0, 1);
1016
1017 /*
1018 * Part of the huge page can be beyond i_size: subject
1019 * to shrink under memory pressure.
1020 */
1021 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
1022 spin_lock(&sbinfo->shrinklist_lock);
1023 if (list_empty(&info->shrinklist)) {
1024 list_add_tail(&info->shrinklist,
1025 &sbinfo->shrinklist);
1026 sbinfo->shrinklist_len++;
1027 }
1028 spin_unlock(&sbinfo->shrinklist_lock);
1029 }
1030 }
1031 }
1032
1033 setattr_copy(inode, attr);
1034 if (attr->ia_valid & ATTR_MODE)
1035 error = posix_acl_chmod(inode, inode->i_mode);
1036 return error;
1037 }
1038
1039 static void shmem_evict_inode(struct inode *inode)
1040 {
1041 struct shmem_inode_info *info = SHMEM_I(inode);
1042 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1043
1044 if (inode->i_mapping->a_ops == &shmem_aops) {
1045 shmem_unacct_size(info->flags, inode->i_size);
1046 inode->i_size = 0;
1047 shmem_truncate_range(inode, 0, (loff_t)-1);
1048 if (!list_empty(&info->shrinklist)) {
1049 spin_lock(&sbinfo->shrinklist_lock);
1050 if (!list_empty(&info->shrinklist)) {
1051 list_del_init(&info->shrinklist);
1052 sbinfo->shrinklist_len--;
1053 }
1054 spin_unlock(&sbinfo->shrinklist_lock);
1055 }
1056 if (!list_empty(&info->swaplist)) {
1057 mutex_lock(&shmem_swaplist_mutex);
1058 list_del_init(&info->swaplist);
1059 mutex_unlock(&shmem_swaplist_mutex);
1060 }
1061 }
1062
1063 simple_xattrs_free(&info->xattrs);
1064 WARN_ON(inode->i_blocks);
1065 shmem_free_inode(inode->i_sb);
1066 clear_inode(inode);
1067 }
1068
1069 static unsigned long find_swap_entry(struct radix_tree_root *root, void *item)
1070 {
1071 struct radix_tree_iter iter;
1072 void **slot;
1073 unsigned long found = -1;
1074 unsigned int checked = 0;
1075
1076 rcu_read_lock();
1077 radix_tree_for_each_slot(slot, root, &iter, 0) {
1078 if (*slot == item) {
1079 found = iter.index;
1080 break;
1081 }
1082 checked++;
1083 if ((checked % 4096) != 0)
1084 continue;
1085 slot = radix_tree_iter_resume(slot, &iter);
1086 cond_resched_rcu();
1087 }
1088
1089 rcu_read_unlock();
1090 return found;
1091 }
1092
1093 /*
1094 * If swap found in inode, free it and move page from swapcache to filecache.
1095 */
1096 static int shmem_unuse_inode(struct shmem_inode_info *info,
1097 swp_entry_t swap, struct page **pagep)
1098 {
1099 struct address_space *mapping = info->vfs_inode.i_mapping;
1100 void *radswap;
1101 pgoff_t index;
1102 gfp_t gfp;
1103 int error = 0;
1104
1105 radswap = swp_to_radix_entry(swap);
1106 index = find_swap_entry(&mapping->page_tree, radswap);
1107 if (index == -1)
1108 return -EAGAIN; /* tell shmem_unuse we found nothing */
1109
1110 /*
1111 * Move _head_ to start search for next from here.
1112 * But be careful: shmem_evict_inode checks list_empty without taking
1113 * mutex, and there's an instant in list_move_tail when info->swaplist
1114 * would appear empty, if it were the only one on shmem_swaplist.
1115 */
1116 if (shmem_swaplist.next != &info->swaplist)
1117 list_move_tail(&shmem_swaplist, &info->swaplist);
1118
1119 gfp = mapping_gfp_mask(mapping);
1120 if (shmem_should_replace_page(*pagep, gfp)) {
1121 mutex_unlock(&shmem_swaplist_mutex);
1122 error = shmem_replace_page(pagep, gfp, info, index);
1123 mutex_lock(&shmem_swaplist_mutex);
1124 /*
1125 * We needed to drop mutex to make that restrictive page
1126 * allocation, but the inode might have been freed while we
1127 * dropped it: although a racing shmem_evict_inode() cannot
1128 * complete without emptying the radix_tree, our page lock
1129 * on this swapcache page is not enough to prevent that -
1130 * free_swap_and_cache() of our swap entry will only
1131 * trylock_page(), removing swap from radix_tree whatever.
1132 *
1133 * We must not proceed to shmem_add_to_page_cache() if the
1134 * inode has been freed, but of course we cannot rely on
1135 * inode or mapping or info to check that. However, we can
1136 * safely check if our swap entry is still in use (and here
1137 * it can't have got reused for another page): if it's still
1138 * in use, then the inode cannot have been freed yet, and we
1139 * can safely proceed (if it's no longer in use, that tells
1140 * nothing about the inode, but we don't need to unuse swap).
1141 */
1142 if (!page_swapcount(*pagep))
1143 error = -ENOENT;
1144 }
1145
1146 /*
1147 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
1148 * but also to hold up shmem_evict_inode(): so inode cannot be freed
1149 * beneath us (pagelock doesn't help until the page is in pagecache).
1150 */
1151 if (!error)
1152 error = shmem_add_to_page_cache(*pagep, mapping, index,
1153 radswap);
1154 if (error != -ENOMEM) {
1155 /*
1156 * Truncation and eviction use free_swap_and_cache(), which
1157 * only does trylock page: if we raced, best clean up here.
1158 */
1159 delete_from_swap_cache(*pagep);
1160 set_page_dirty(*pagep);
1161 if (!error) {
1162 spin_lock_irq(&info->lock);
1163 info->swapped--;
1164 spin_unlock_irq(&info->lock);
1165 swap_free(swap);
1166 }
1167 }
1168 return error;
1169 }
1170
1171 /*
1172 * Search through swapped inodes to find and replace swap by page.
1173 */
1174 int shmem_unuse(swp_entry_t swap, struct page *page)
1175 {
1176 struct list_head *this, *next;
1177 struct shmem_inode_info *info;
1178 struct mem_cgroup *memcg;
1179 int error = 0;
1180
1181 /*
1182 * There's a faint possibility that swap page was replaced before
1183 * caller locked it: caller will come back later with the right page.
1184 */
1185 if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
1186 goto out;
1187
1188 /*
1189 * Charge page using GFP_KERNEL while we can wait, before taking
1190 * the shmem_swaplist_mutex which might hold up shmem_writepage().
1191 * Charged back to the user (not to caller) when swap account is used.
1192 */
1193 error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg,
1194 false);
1195 if (error)
1196 goto out;
1197 /* No radix_tree_preload: swap entry keeps a place for page in tree */
1198 error = -EAGAIN;
1199
1200 mutex_lock(&shmem_swaplist_mutex);
1201 list_for_each_safe(this, next, &shmem_swaplist) {
1202 info = list_entry(this, struct shmem_inode_info, swaplist);
1203 if (info->swapped)
1204 error = shmem_unuse_inode(info, swap, &page);
1205 else
1206 list_del_init(&info->swaplist);
1207 cond_resched();
1208 if (error != -EAGAIN)
1209 break;
1210 /* found nothing in this: move on to search the next */
1211 }
1212 mutex_unlock(&shmem_swaplist_mutex);
1213
1214 if (error) {
1215 if (error != -ENOMEM)
1216 error = 0;
1217 mem_cgroup_cancel_charge(page, memcg, false);
1218 } else
1219 mem_cgroup_commit_charge(page, memcg, true, false);
1220 out:
1221 unlock_page(page);
1222 put_page(page);
1223 return error;
1224 }
1225
1226 /*
1227 * Move the page from the page cache to the swap cache.
1228 */
1229 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1230 {
1231 struct shmem_inode_info *info;
1232 struct address_space *mapping;
1233 struct inode *inode;
1234 swp_entry_t swap;
1235 pgoff_t index;
1236
1237 VM_BUG_ON_PAGE(PageCompound(page), page);
1238 BUG_ON(!PageLocked(page));
1239 mapping = page->mapping;
1240 index = page->index;
1241 inode = mapping->host;
1242 info = SHMEM_I(inode);
1243 if (info->flags & VM_LOCKED)
1244 goto redirty;
1245 if (!total_swap_pages)
1246 goto redirty;
1247
1248 /*
1249 * Our capabilities prevent regular writeback or sync from ever calling
1250 * shmem_writepage; but a stacking filesystem might use ->writepage of
1251 * its underlying filesystem, in which case tmpfs should write out to
1252 * swap only in response to memory pressure, and not for the writeback
1253 * threads or sync.
1254 */
1255 if (!wbc->for_reclaim) {
1256 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1257 goto redirty;
1258 }
1259
1260 /*
1261 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1262 * value into swapfile.c, the only way we can correctly account for a
1263 * fallocated page arriving here is now to initialize it and write it.
1264 *
1265 * That's okay for a page already fallocated earlier, but if we have
1266 * not yet completed the fallocation, then (a) we want to keep track
1267 * of this page in case we have to undo it, and (b) it may not be a
1268 * good idea to continue anyway, once we're pushing into swap. So
1269 * reactivate the page, and let shmem_fallocate() quit when too many.
1270 */
1271 if (!PageUptodate(page)) {
1272 if (inode->i_private) {
1273 struct shmem_falloc *shmem_falloc;
1274 spin_lock(&inode->i_lock);
1275 shmem_falloc = inode->i_private;
1276 if (shmem_falloc &&
1277 !shmem_falloc->waitq &&
1278 index >= shmem_falloc->start &&
1279 index < shmem_falloc->next)
1280 shmem_falloc->nr_unswapped++;
1281 else
1282 shmem_falloc = NULL;
1283 spin_unlock(&inode->i_lock);
1284 if (shmem_falloc)
1285 goto redirty;
1286 }
1287 clear_highpage(page);
1288 flush_dcache_page(page);
1289 SetPageUptodate(page);
1290 }
1291
1292 swap = get_swap_page();
1293 if (!swap.val)
1294 goto redirty;
1295
1296 if (mem_cgroup_try_charge_swap(page, swap))
1297 goto free_swap;
1298
1299 /*
1300 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1301 * if it's not already there. Do it now before the page is
1302 * moved to swap cache, when its pagelock no longer protects
1303 * the inode from eviction. But don't unlock the mutex until
1304 * we've incremented swapped, because shmem_unuse_inode() will
1305 * prune a !swapped inode from the swaplist under this mutex.
1306 */
1307 mutex_lock(&shmem_swaplist_mutex);
1308 if (list_empty(&info->swaplist))
1309 list_add_tail(&info->swaplist, &shmem_swaplist);
1310
1311 if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1312 spin_lock_irq(&info->lock);
1313 shmem_recalc_inode(inode);
1314 info->swapped++;
1315 spin_unlock_irq(&info->lock);
1316
1317 swap_shmem_alloc(swap);
1318 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1319
1320 mutex_unlock(&shmem_swaplist_mutex);
1321 BUG_ON(page_mapped(page));
1322 swap_writepage(page, wbc);
1323 return 0;
1324 }
1325
1326 mutex_unlock(&shmem_swaplist_mutex);
1327 free_swap:
1328 swapcache_free(swap);
1329 redirty:
1330 set_page_dirty(page);
1331 if (wbc->for_reclaim)
1332 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1333 unlock_page(page);
1334 return 0;
1335 }
1336
1337 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1338 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1339 {
1340 char buffer[64];
1341
1342 if (!mpol || mpol->mode == MPOL_DEFAULT)
1343 return; /* show nothing */
1344
1345 mpol_to_str(buffer, sizeof(buffer), mpol);
1346
1347 seq_printf(seq, ",mpol=%s", buffer);
1348 }
1349
1350 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1351 {
1352 struct mempolicy *mpol = NULL;
1353 if (sbinfo->mpol) {
1354 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1355 mpol = sbinfo->mpol;
1356 mpol_get(mpol);
1357 spin_unlock(&sbinfo->stat_lock);
1358 }
1359 return mpol;
1360 }
1361 #else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1362 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1363 {
1364 }
1365 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1366 {
1367 return NULL;
1368 }
1369 #endif /* CONFIG_NUMA && CONFIG_TMPFS */
1370 #ifndef CONFIG_NUMA
1371 #define vm_policy vm_private_data
1372 #endif
1373
1374 static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1375 struct shmem_inode_info *info, pgoff_t index)
1376 {
1377 /* Create a pseudo vma that just contains the policy */
1378 vma->vm_start = 0;
1379 /* Bias interleave by inode number to distribute better across nodes */
1380 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1381 vma->vm_ops = NULL;
1382 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1383 }
1384
1385 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1386 {
1387 /* Drop reference taken by mpol_shared_policy_lookup() */
1388 mpol_cond_put(vma->vm_policy);
1389 }
1390
1391 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1392 struct shmem_inode_info *info, pgoff_t index)
1393 {
1394 struct vm_area_struct pvma;
1395 struct page *page;
1396
1397 shmem_pseudo_vma_init(&pvma, info, index);
1398 page = swapin_readahead(swap, gfp, &pvma, 0);
1399 shmem_pseudo_vma_destroy(&pvma);
1400
1401 return page;
1402 }
1403
1404 static struct page *shmem_alloc_hugepage(gfp_t gfp,
1405 struct shmem_inode_info *info, pgoff_t index)
1406 {
1407 struct vm_area_struct pvma;
1408 struct inode *inode = &info->vfs_inode;
1409 struct address_space *mapping = inode->i_mapping;
1410 pgoff_t idx, hindex;
1411 void __rcu **results;
1412 struct page *page;
1413
1414 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1415 return NULL;
1416
1417 hindex = round_down(index, HPAGE_PMD_NR);
1418 rcu_read_lock();
1419 if (radix_tree_gang_lookup_slot(&mapping->page_tree, &results, &idx,
1420 hindex, 1) && idx < hindex + HPAGE_PMD_NR) {
1421 rcu_read_unlock();
1422 return NULL;
1423 }
1424 rcu_read_unlock();
1425
1426 shmem_pseudo_vma_init(&pvma, info, hindex);
1427 page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
1428 HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), true);
1429 shmem_pseudo_vma_destroy(&pvma);
1430 if (page)
1431 prep_transhuge_page(page);
1432 return page;
1433 }
1434
1435 static struct page *shmem_alloc_page(gfp_t gfp,
1436 struct shmem_inode_info *info, pgoff_t index)
1437 {
1438 struct vm_area_struct pvma;
1439 struct page *page;
1440
1441 shmem_pseudo_vma_init(&pvma, info, index);
1442 page = alloc_page_vma(gfp, &pvma, 0);
1443 shmem_pseudo_vma_destroy(&pvma);
1444
1445 return page;
1446 }
1447
1448 static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
1449 struct shmem_inode_info *info, struct shmem_sb_info *sbinfo,
1450 pgoff_t index, bool huge)
1451 {
1452 struct page *page;
1453 int nr;
1454 int err = -ENOSPC;
1455
1456 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1457 huge = false;
1458 nr = huge ? HPAGE_PMD_NR : 1;
1459
1460 if (shmem_acct_block(info->flags, nr))
1461 goto failed;
1462 if (sbinfo->max_blocks) {
1463 if (percpu_counter_compare(&sbinfo->used_blocks,
1464 sbinfo->max_blocks - nr) > 0)
1465 goto unacct;
1466 percpu_counter_add(&sbinfo->used_blocks, nr);
1467 }
1468
1469 if (huge)
1470 page = shmem_alloc_hugepage(gfp, info, index);
1471 else
1472 page = shmem_alloc_page(gfp, info, index);
1473 if (page) {
1474 __SetPageLocked(page);
1475 __SetPageSwapBacked(page);
1476 return page;
1477 }
1478
1479 err = -ENOMEM;
1480 if (sbinfo->max_blocks)
1481 percpu_counter_add(&sbinfo->used_blocks, -nr);
1482 unacct:
1483 shmem_unacct_blocks(info->flags, nr);
1484 failed:
1485 return ERR_PTR(err);
1486 }
1487
1488 /*
1489 * When a page is moved from swapcache to shmem filecache (either by the
1490 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1491 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1492 * ignorance of the mapping it belongs to. If that mapping has special
1493 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1494 * we may need to copy to a suitable page before moving to filecache.
1495 *
1496 * In a future release, this may well be extended to respect cpuset and
1497 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1498 * but for now it is a simple matter of zone.
1499 */
1500 static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
1501 {
1502 return page_zonenum(page) > gfp_zone(gfp);
1503 }
1504
1505 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1506 struct shmem_inode_info *info, pgoff_t index)
1507 {
1508 struct page *oldpage, *newpage;
1509 struct address_space *swap_mapping;
1510 pgoff_t swap_index;
1511 int error;
1512
1513 oldpage = *pagep;
1514 swap_index = page_private(oldpage);
1515 swap_mapping = page_mapping(oldpage);
1516
1517 /*
1518 * We have arrived here because our zones are constrained, so don't
1519 * limit chance of success by further cpuset and node constraints.
1520 */
1521 gfp &= ~GFP_CONSTRAINT_MASK;
1522 newpage = shmem_alloc_page(gfp, info, index);
1523 if (!newpage)
1524 return -ENOMEM;
1525
1526 get_page(newpage);
1527 copy_highpage(newpage, oldpage);
1528 flush_dcache_page(newpage);
1529
1530 __SetPageLocked(newpage);
1531 __SetPageSwapBacked(newpage);
1532 SetPageUptodate(newpage);
1533 set_page_private(newpage, swap_index);
1534 SetPageSwapCache(newpage);
1535
1536 /*
1537 * Our caller will very soon move newpage out of swapcache, but it's
1538 * a nice clean interface for us to replace oldpage by newpage there.
1539 */
1540 spin_lock_irq(&swap_mapping->tree_lock);
1541 error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
1542 newpage);
1543 if (!error) {
1544 __inc_node_page_state(newpage, NR_FILE_PAGES);
1545 __dec_node_page_state(oldpage, NR_FILE_PAGES);
1546 }
1547 spin_unlock_irq(&swap_mapping->tree_lock);
1548
1549 if (unlikely(error)) {
1550 /*
1551 * Is this possible? I think not, now that our callers check
1552 * both PageSwapCache and page_private after getting page lock;
1553 * but be defensive. Reverse old to newpage for clear and free.
1554 */
1555 oldpage = newpage;
1556 } else {
1557 mem_cgroup_migrate(oldpage, newpage);
1558 lru_cache_add_anon(newpage);
1559 *pagep = newpage;
1560 }
1561
1562 ClearPageSwapCache(oldpage);
1563 set_page_private(oldpage, 0);
1564
1565 unlock_page(oldpage);
1566 put_page(oldpage);
1567 put_page(oldpage);
1568 return error;
1569 }
1570
1571 /*
1572 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1573 *
1574 * If we allocate a new one we do not mark it dirty. That's up to the
1575 * vm. If we swap it in we mark it dirty since we also free the swap
1576 * entry since a page cannot live in both the swap and page cache.
1577 *
1578 * fault_mm and fault_type are only supplied by shmem_fault:
1579 * otherwise they are NULL.
1580 */
1581 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1582 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1583 struct vm_area_struct *vma, struct vm_fault *vmf, int *fault_type)
1584 {
1585 struct address_space *mapping = inode->i_mapping;
1586 struct shmem_inode_info *info = SHMEM_I(inode);
1587 struct shmem_sb_info *sbinfo;
1588 struct mm_struct *charge_mm;
1589 struct mem_cgroup *memcg;
1590 struct page *page;
1591 swp_entry_t swap;
1592 enum sgp_type sgp_huge = sgp;
1593 pgoff_t hindex = index;
1594 int error;
1595 int once = 0;
1596 int alloced = 0;
1597
1598 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1599 return -EFBIG;
1600 if (sgp == SGP_NOHUGE || sgp == SGP_HUGE)
1601 sgp = SGP_CACHE;
1602 repeat:
1603 swap.val = 0;
1604 page = find_lock_entry(mapping, index);
1605 if (radix_tree_exceptional_entry(page)) {
1606 swap = radix_to_swp_entry(page);
1607 page = NULL;
1608 }
1609
1610 if (sgp <= SGP_CACHE &&
1611 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1612 error = -EINVAL;
1613 goto unlock;
1614 }
1615
1616 if (page && sgp == SGP_WRITE)
1617 mark_page_accessed(page);
1618
1619 /* fallocated page? */
1620 if (page && !PageUptodate(page)) {
1621 if (sgp != SGP_READ)
1622 goto clear;
1623 unlock_page(page);
1624 put_page(page);
1625 page = NULL;
1626 }
1627 if (page || (sgp == SGP_READ && !swap.val)) {
1628 *pagep = page;
1629 return 0;
1630 }
1631
1632 /*
1633 * Fast cache lookup did not find it:
1634 * bring it back from swap or allocate.
1635 */
1636 sbinfo = SHMEM_SB(inode->i_sb);
1637 charge_mm = vma ? vma->vm_mm : current->mm;
1638
1639 if (swap.val) {
1640 /* Look it up and read it in.. */
1641 page = lookup_swap_cache(swap);
1642 if (!page) {
1643 /* Or update major stats only when swapin succeeds?? */
1644 if (fault_type) {
1645 *fault_type |= VM_FAULT_MAJOR;
1646 count_vm_event(PGMAJFAULT);
1647 mem_cgroup_count_vm_event(charge_mm,
1648 PGMAJFAULT);
1649 }
1650 /* Here we actually start the io */
1651 page = shmem_swapin(swap, gfp, info, index);
1652 if (!page) {
1653 error = -ENOMEM;
1654 goto failed;
1655 }
1656 }
1657
1658 /* We have to do this with page locked to prevent races */
1659 lock_page(page);
1660 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1661 !shmem_confirm_swap(mapping, index, swap)) {
1662 error = -EEXIST; /* try again */
1663 goto unlock;
1664 }
1665 if (!PageUptodate(page)) {
1666 error = -EIO;
1667 goto failed;
1668 }
1669 wait_on_page_writeback(page);
1670
1671 if (shmem_should_replace_page(page, gfp)) {
1672 error = shmem_replace_page(&page, gfp, info, index);
1673 if (error)
1674 goto failed;
1675 }
1676
1677 error = mem_cgroup_try_charge(page, charge_mm, gfp, &memcg,
1678 false);
1679 if (!error) {
1680 error = shmem_add_to_page_cache(page, mapping, index,
1681 swp_to_radix_entry(swap));
1682 /*
1683 * We already confirmed swap under page lock, and make
1684 * no memory allocation here, so usually no possibility
1685 * of error; but free_swap_and_cache() only trylocks a
1686 * page, so it is just possible that the entry has been
1687 * truncated or holepunched since swap was confirmed.
1688 * shmem_undo_range() will have done some of the
1689 * unaccounting, now delete_from_swap_cache() will do
1690 * the rest.
1691 * Reset swap.val? No, leave it so "failed" goes back to
1692 * "repeat": reading a hole and writing should succeed.
1693 */
1694 if (error) {
1695 mem_cgroup_cancel_charge(page, memcg, false);
1696 delete_from_swap_cache(page);
1697 }
1698 }
1699 if (error)
1700 goto failed;
1701
1702 mem_cgroup_commit_charge(page, memcg, true, false);
1703
1704 spin_lock_irq(&info->lock);
1705 info->swapped--;
1706 shmem_recalc_inode(inode);
1707 spin_unlock_irq(&info->lock);
1708
1709 if (sgp == SGP_WRITE)
1710 mark_page_accessed(page);
1711
1712 delete_from_swap_cache(page);
1713 set_page_dirty(page);
1714 swap_free(swap);
1715
1716 } else {
1717 if (vma && userfaultfd_missing(vma)) {
1718 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1719 return 0;
1720 }
1721
1722 /* shmem_symlink() */
1723 if (mapping->a_ops != &shmem_aops)
1724 goto alloc_nohuge;
1725 if (shmem_huge == SHMEM_HUGE_DENY || sgp_huge == SGP_NOHUGE)
1726 goto alloc_nohuge;
1727 if (shmem_huge == SHMEM_HUGE_FORCE)
1728 goto alloc_huge;
1729 switch (sbinfo->huge) {
1730 loff_t i_size;
1731 pgoff_t off;
1732 case SHMEM_HUGE_NEVER:
1733 goto alloc_nohuge;
1734 case SHMEM_HUGE_WITHIN_SIZE:
1735 off = round_up(index, HPAGE_PMD_NR);
1736 i_size = round_up(i_size_read(inode), PAGE_SIZE);
1737 if (i_size >= HPAGE_PMD_SIZE &&
1738 i_size >> PAGE_SHIFT >= off)
1739 goto alloc_huge;
1740 /* fallthrough */
1741 case SHMEM_HUGE_ADVISE:
1742 if (sgp_huge == SGP_HUGE)
1743 goto alloc_huge;
1744 /* TODO: implement fadvise() hints */
1745 goto alloc_nohuge;
1746 }
1747
1748 alloc_huge:
1749 page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
1750 index, true);
1751 if (IS_ERR(page)) {
1752 alloc_nohuge: page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
1753 index, false);
1754 }
1755 if (IS_ERR(page)) {
1756 int retry = 5;
1757 error = PTR_ERR(page);
1758 page = NULL;
1759 if (error != -ENOSPC)
1760 goto failed;
1761 /*
1762 * Try to reclaim some spece by splitting a huge page
1763 * beyond i_size on the filesystem.
1764 */
1765 while (retry--) {
1766 int ret;
1767 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1768 if (ret == SHRINK_STOP)
1769 break;
1770 if (ret)
1771 goto alloc_nohuge;
1772 }
1773 goto failed;
1774 }
1775
1776 if (PageTransHuge(page))
1777 hindex = round_down(index, HPAGE_PMD_NR);
1778 else
1779 hindex = index;
1780
1781 if (sgp == SGP_WRITE)
1782 __SetPageReferenced(page);
1783
1784 error = mem_cgroup_try_charge(page, charge_mm, gfp, &memcg,
1785 PageTransHuge(page));
1786 if (error)
1787 goto unacct;
1788 error = radix_tree_maybe_preload_order(gfp & GFP_RECLAIM_MASK,
1789 compound_order(page));
1790 if (!error) {
1791 error = shmem_add_to_page_cache(page, mapping, hindex,
1792 NULL);
1793 radix_tree_preload_end();
1794 }
1795 if (error) {
1796 mem_cgroup_cancel_charge(page, memcg,
1797 PageTransHuge(page));
1798 goto unacct;
1799 }
1800 mem_cgroup_commit_charge(page, memcg, false,
1801 PageTransHuge(page));
1802 lru_cache_add_anon(page);
1803
1804 spin_lock_irq(&info->lock);
1805 info->alloced += 1 << compound_order(page);
1806 inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
1807 shmem_recalc_inode(inode);
1808 spin_unlock_irq(&info->lock);
1809 alloced = true;
1810
1811 if (PageTransHuge(page) &&
1812 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1813 hindex + HPAGE_PMD_NR - 1) {
1814 /*
1815 * Part of the huge page is beyond i_size: subject
1816 * to shrink under memory pressure.
1817 */
1818 spin_lock(&sbinfo->shrinklist_lock);
1819 if (list_empty(&info->shrinklist)) {
1820 list_add_tail(&info->shrinklist,
1821 &sbinfo->shrinklist);
1822 sbinfo->shrinklist_len++;
1823 }
1824 spin_unlock(&sbinfo->shrinklist_lock);
1825 }
1826
1827 /*
1828 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1829 */
1830 if (sgp == SGP_FALLOC)
1831 sgp = SGP_WRITE;
1832 clear:
1833 /*
1834 * Let SGP_WRITE caller clear ends if write does not fill page;
1835 * but SGP_FALLOC on a page fallocated earlier must initialize
1836 * it now, lest undo on failure cancel our earlier guarantee.
1837 */
1838 if (sgp != SGP_WRITE && !PageUptodate(page)) {
1839 struct page *head = compound_head(page);
1840 int i;
1841
1842 for (i = 0; i < (1 << compound_order(head)); i++) {
1843 clear_highpage(head + i);
1844 flush_dcache_page(head + i);
1845 }
1846 SetPageUptodate(head);
1847 }
1848 }
1849
1850 /* Perhaps the file has been truncated since we checked */
1851 if (sgp <= SGP_CACHE &&
1852 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1853 if (alloced) {
1854 ClearPageDirty(page);
1855 delete_from_page_cache(page);
1856 spin_lock_irq(&info->lock);
1857 shmem_recalc_inode(inode);
1858 spin_unlock_irq(&info->lock);
1859 }
1860 error = -EINVAL;
1861 goto unlock;
1862 }
1863 *pagep = page + index - hindex;
1864 return 0;
1865
1866 /*
1867 * Error recovery.
1868 */
1869 unacct:
1870 if (sbinfo->max_blocks)
1871 percpu_counter_sub(&sbinfo->used_blocks,
1872 1 << compound_order(page));
1873 shmem_unacct_blocks(info->flags, 1 << compound_order(page));
1874
1875 if (PageTransHuge(page)) {
1876 unlock_page(page);
1877 put_page(page);
1878 goto alloc_nohuge;
1879 }
1880 failed:
1881 if (swap.val && !shmem_confirm_swap(mapping, index, swap))
1882 error = -EEXIST;
1883 unlock:
1884 if (page) {
1885 unlock_page(page);
1886 put_page(page);
1887 }
1888 if (error == -ENOSPC && !once++) {
1889 spin_lock_irq(&info->lock);
1890 shmem_recalc_inode(inode);
1891 spin_unlock_irq(&info->lock);
1892 goto repeat;
1893 }
1894 if (error == -EEXIST) /* from above or from radix_tree_insert */
1895 goto repeat;
1896 return error;
1897 }
1898
1899 /*
1900 * This is like autoremove_wake_function, but it removes the wait queue
1901 * entry unconditionally - even if something else had already woken the
1902 * target.
1903 */
1904 static int synchronous_wake_function(wait_queue_t *wait, unsigned mode, int sync, void *key)
1905 {
1906 int ret = default_wake_function(wait, mode, sync, key);
1907 list_del_init(&wait->task_list);
1908 return ret;
1909 }
1910
1911 static int shmem_fault(struct vm_fault *vmf)
1912 {
1913 struct vm_area_struct *vma = vmf->vma;
1914 struct inode *inode = file_inode(vma->vm_file);
1915 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
1916 enum sgp_type sgp;
1917 int error;
1918 int ret = VM_FAULT_LOCKED;
1919
1920 /*
1921 * Trinity finds that probing a hole which tmpfs is punching can
1922 * prevent the hole-punch from ever completing: which in turn
1923 * locks writers out with its hold on i_mutex. So refrain from
1924 * faulting pages into the hole while it's being punched. Although
1925 * shmem_undo_range() does remove the additions, it may be unable to
1926 * keep up, as each new page needs its own unmap_mapping_range() call,
1927 * and the i_mmap tree grows ever slower to scan if new vmas are added.
1928 *
1929 * It does not matter if we sometimes reach this check just before the
1930 * hole-punch begins, so that one fault then races with the punch:
1931 * we just need to make racing faults a rare case.
1932 *
1933 * The implementation below would be much simpler if we just used a
1934 * standard mutex or completion: but we cannot take i_mutex in fault,
1935 * and bloating every shmem inode for this unlikely case would be sad.
1936 */
1937 if (unlikely(inode->i_private)) {
1938 struct shmem_falloc *shmem_falloc;
1939
1940 spin_lock(&inode->i_lock);
1941 shmem_falloc = inode->i_private;
1942 if (shmem_falloc &&
1943 shmem_falloc->waitq &&
1944 vmf->pgoff >= shmem_falloc->start &&
1945 vmf->pgoff < shmem_falloc->next) {
1946 wait_queue_head_t *shmem_falloc_waitq;
1947 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
1948
1949 ret = VM_FAULT_NOPAGE;
1950 if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
1951 !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
1952 /* It's polite to up mmap_sem if we can */
1953 up_read(&vma->vm_mm->mmap_sem);
1954 ret = VM_FAULT_RETRY;
1955 }
1956
1957 shmem_falloc_waitq = shmem_falloc->waitq;
1958 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
1959 TASK_UNINTERRUPTIBLE);
1960 spin_unlock(&inode->i_lock);
1961 schedule();
1962
1963 /*
1964 * shmem_falloc_waitq points into the shmem_fallocate()
1965 * stack of the hole-punching task: shmem_falloc_waitq
1966 * is usually invalid by the time we reach here, but
1967 * finish_wait() does not dereference it in that case;
1968 * though i_lock needed lest racing with wake_up_all().
1969 */
1970 spin_lock(&inode->i_lock);
1971 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
1972 spin_unlock(&inode->i_lock);
1973 return ret;
1974 }
1975 spin_unlock(&inode->i_lock);
1976 }
1977
1978 sgp = SGP_CACHE;
1979 if (vma->vm_flags & VM_HUGEPAGE)
1980 sgp = SGP_HUGE;
1981 else if (vma->vm_flags & VM_NOHUGEPAGE)
1982 sgp = SGP_NOHUGE;
1983
1984 error = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
1985 gfp, vma, vmf, &ret);
1986 if (error)
1987 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1988 return ret;
1989 }
1990
1991 unsigned long shmem_get_unmapped_area(struct file *file,
1992 unsigned long uaddr, unsigned long len,
1993 unsigned long pgoff, unsigned long flags)
1994 {
1995 unsigned long (*get_area)(struct file *,
1996 unsigned long, unsigned long, unsigned long, unsigned long);
1997 unsigned long addr;
1998 unsigned long offset;
1999 unsigned long inflated_len;
2000 unsigned long inflated_addr;
2001 unsigned long inflated_offset;
2002
2003 if (len > TASK_SIZE)
2004 return -ENOMEM;
2005
2006 get_area = current->mm->get_unmapped_area;
2007 addr = get_area(file, uaddr, len, pgoff, flags);
2008
2009 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
2010 return addr;
2011 if (IS_ERR_VALUE(addr))
2012 return addr;
2013 if (addr & ~PAGE_MASK)
2014 return addr;
2015 if (addr > TASK_SIZE - len)
2016 return addr;
2017
2018 if (shmem_huge == SHMEM_HUGE_DENY)
2019 return addr;
2020 if (len < HPAGE_PMD_SIZE)
2021 return addr;
2022 if (flags & MAP_FIXED)
2023 return addr;
2024 /*
2025 * Our priority is to support MAP_SHARED mapped hugely;
2026 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2027 * But if caller specified an address hint, respect that as before.
2028 */
2029 if (uaddr)
2030 return addr;
2031
2032 if (shmem_huge != SHMEM_HUGE_FORCE) {
2033 struct super_block *sb;
2034
2035 if (file) {
2036 VM_BUG_ON(file->f_op != &shmem_file_operations);
2037 sb = file_inode(file)->i_sb;
2038 } else {
2039 /*
2040 * Called directly from mm/mmap.c, or drivers/char/mem.c
2041 * for "/dev/zero", to create a shared anonymous object.
2042 */
2043 if (IS_ERR(shm_mnt))
2044 return addr;
2045 sb = shm_mnt->mnt_sb;
2046 }
2047 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2048 return addr;
2049 }
2050
2051 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2052 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
2053 return addr;
2054 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2055 return addr;
2056
2057 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2058 if (inflated_len > TASK_SIZE)
2059 return addr;
2060 if (inflated_len < len)
2061 return addr;
2062
2063 inflated_addr = get_area(NULL, 0, inflated_len, 0, flags);
2064 if (IS_ERR_VALUE(inflated_addr))
2065 return addr;
2066 if (inflated_addr & ~PAGE_MASK)
2067 return addr;
2068
2069 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2070 inflated_addr += offset - inflated_offset;
2071 if (inflated_offset > offset)
2072 inflated_addr += HPAGE_PMD_SIZE;
2073
2074 if (inflated_addr > TASK_SIZE - len)
2075 return addr;
2076 return inflated_addr;
2077 }
2078
2079 #ifdef CONFIG_NUMA
2080 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2081 {
2082 struct inode *inode = file_inode(vma->vm_file);
2083 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2084 }
2085
2086 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2087 unsigned long addr)
2088 {
2089 struct inode *inode = file_inode(vma->vm_file);
2090 pgoff_t index;
2091
2092 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2093 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2094 }
2095 #endif
2096
2097 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2098 {
2099 struct inode *inode = file_inode(file);
2100 struct shmem_inode_info *info = SHMEM_I(inode);
2101 int retval = -ENOMEM;
2102
2103 spin_lock_irq(&info->lock);
2104 if (lock && !(info->flags & VM_LOCKED)) {
2105 if (!user_shm_lock(inode->i_size, user))
2106 goto out_nomem;
2107 info->flags |= VM_LOCKED;
2108 mapping_set_unevictable(file->f_mapping);
2109 }
2110 if (!lock && (info->flags & VM_LOCKED) && user) {
2111 user_shm_unlock(inode->i_size, user);
2112 info->flags &= ~VM_LOCKED;
2113 mapping_clear_unevictable(file->f_mapping);
2114 }
2115 retval = 0;
2116
2117 out_nomem:
2118 spin_unlock_irq(&info->lock);
2119 return retval;
2120 }
2121
2122 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2123 {
2124 file_accessed(file);
2125 vma->vm_ops = &shmem_vm_ops;
2126 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
2127 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
2128 (vma->vm_end & HPAGE_PMD_MASK)) {
2129 khugepaged_enter(vma, vma->vm_flags);
2130 }
2131 return 0;
2132 }
2133
2134 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2135 umode_t mode, dev_t dev, unsigned long flags)
2136 {
2137 struct inode *inode;
2138 struct shmem_inode_info *info;
2139 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2140
2141 if (shmem_reserve_inode(sb))
2142 return NULL;
2143
2144 inode = new_inode(sb);
2145 if (inode) {
2146 inode->i_ino = get_next_ino();
2147 inode_init_owner(inode, dir, mode);
2148 inode->i_blocks = 0;
2149 inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2150 inode->i_generation = get_seconds();
2151 info = SHMEM_I(inode);
2152 memset(info, 0, (char *)inode - (char *)info);
2153 spin_lock_init(&info->lock);
2154 info->seals = F_SEAL_SEAL;
2155 info->flags = flags & VM_NORESERVE;
2156 INIT_LIST_HEAD(&info->shrinklist);
2157 INIT_LIST_HEAD(&info->swaplist);
2158 simple_xattrs_init(&info->xattrs);
2159 cache_no_acl(inode);
2160
2161 switch (mode & S_IFMT) {
2162 default:
2163 inode->i_op = &shmem_special_inode_operations;
2164 init_special_inode(inode, mode, dev);
2165 break;
2166 case S_IFREG:
2167 inode->i_mapping->a_ops = &shmem_aops;
2168 inode->i_op = &shmem_inode_operations;
2169 inode->i_fop = &shmem_file_operations;
2170 mpol_shared_policy_init(&info->policy,
2171 shmem_get_sbmpol(sbinfo));
2172 break;
2173 case S_IFDIR:
2174 inc_nlink(inode);
2175 /* Some things misbehave if size == 0 on a directory */
2176 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2177 inode->i_op = &shmem_dir_inode_operations;
2178 inode->i_fop = &simple_dir_operations;
2179 break;
2180 case S_IFLNK:
2181 /*
2182 * Must not load anything in the rbtree,
2183 * mpol_free_shared_policy will not be called.
2184 */
2185 mpol_shared_policy_init(&info->policy, NULL);
2186 break;
2187 }
2188 } else
2189 shmem_free_inode(sb);
2190 return inode;
2191 }
2192
2193 bool shmem_mapping(struct address_space *mapping)
2194 {
2195 return mapping->a_ops == &shmem_aops;
2196 }
2197
2198 int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
2199 pmd_t *dst_pmd,
2200 struct vm_area_struct *dst_vma,
2201 unsigned long dst_addr,
2202 unsigned long src_addr,
2203 struct page **pagep)
2204 {
2205 struct inode *inode = file_inode(dst_vma->vm_file);
2206 struct shmem_inode_info *info = SHMEM_I(inode);
2207 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2208 struct address_space *mapping = inode->i_mapping;
2209 gfp_t gfp = mapping_gfp_mask(mapping);
2210 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2211 struct mem_cgroup *memcg;
2212 spinlock_t *ptl;
2213 void *page_kaddr;
2214 struct page *page;
2215 pte_t _dst_pte, *dst_pte;
2216 int ret;
2217
2218 ret = -ENOMEM;
2219 if (shmem_acct_block(info->flags, 1))
2220 goto out;
2221 if (sbinfo->max_blocks) {
2222 if (percpu_counter_compare(&sbinfo->used_blocks,
2223 sbinfo->max_blocks) >= 0)
2224 goto out_unacct_blocks;
2225 percpu_counter_inc(&sbinfo->used_blocks);
2226 }
2227
2228 if (!*pagep) {
2229 page = shmem_alloc_page(gfp, info, pgoff);
2230 if (!page)
2231 goto out_dec_used_blocks;
2232
2233 page_kaddr = kmap_atomic(page);
2234 ret = copy_from_user(page_kaddr, (const void __user *)src_addr,
2235 PAGE_SIZE);
2236 kunmap_atomic(page_kaddr);
2237
2238 /* fallback to copy_from_user outside mmap_sem */
2239 if (unlikely(ret)) {
2240 *pagep = page;
2241 if (sbinfo->max_blocks)
2242 percpu_counter_add(&sbinfo->used_blocks, -1);
2243 shmem_unacct_blocks(info->flags, 1);
2244 /* don't free the page */
2245 return -EFAULT;
2246 }
2247 } else {
2248 page = *pagep;
2249 *pagep = NULL;
2250 }
2251
2252 VM_BUG_ON(PageLocked(page) || PageSwapBacked(page));
2253 __SetPageLocked(page);
2254 __SetPageSwapBacked(page);
2255 __SetPageUptodate(page);
2256
2257 ret = mem_cgroup_try_charge(page, dst_mm, gfp, &memcg, false);
2258 if (ret)
2259 goto out_release;
2260
2261 ret = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
2262 if (!ret) {
2263 ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL);
2264 radix_tree_preload_end();
2265 }
2266 if (ret)
2267 goto out_release_uncharge;
2268
2269 mem_cgroup_commit_charge(page, memcg, false, false);
2270
2271 _dst_pte = mk_pte(page, dst_vma->vm_page_prot);
2272 if (dst_vma->vm_flags & VM_WRITE)
2273 _dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
2274
2275 ret = -EEXIST;
2276 dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
2277 if (!pte_none(*dst_pte))
2278 goto out_release_uncharge_unlock;
2279
2280 lru_cache_add_anon(page);
2281
2282 spin_lock(&info->lock);
2283 info->alloced++;
2284 inode->i_blocks += BLOCKS_PER_PAGE;
2285 shmem_recalc_inode(inode);
2286 spin_unlock(&info->lock);
2287
2288 inc_mm_counter(dst_mm, mm_counter_file(page));
2289 page_add_file_rmap(page, false);
2290 set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
2291
2292 /* No need to invalidate - it was non-present before */
2293 update_mmu_cache(dst_vma, dst_addr, dst_pte);
2294 unlock_page(page);
2295 pte_unmap_unlock(dst_pte, ptl);
2296 ret = 0;
2297 out:
2298 return ret;
2299 out_release_uncharge_unlock:
2300 pte_unmap_unlock(dst_pte, ptl);
2301 out_release_uncharge:
2302 mem_cgroup_cancel_charge(page, memcg, false);
2303 out_release:
2304 unlock_page(page);
2305 put_page(page);
2306 out_dec_used_blocks:
2307 if (sbinfo->max_blocks)
2308 percpu_counter_add(&sbinfo->used_blocks, -1);
2309 out_unacct_blocks:
2310 shmem_unacct_blocks(info->flags, 1);
2311 goto out;
2312 }
2313
2314 #ifdef CONFIG_TMPFS
2315 static const struct inode_operations shmem_symlink_inode_operations;
2316 static const struct inode_operations shmem_short_symlink_operations;
2317
2318 #ifdef CONFIG_TMPFS_XATTR
2319 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2320 #else
2321 #define shmem_initxattrs NULL
2322 #endif
2323
2324 static int
2325 shmem_write_begin(struct file *file, struct address_space *mapping,
2326 loff_t pos, unsigned len, unsigned flags,
2327 struct page **pagep, void **fsdata)
2328 {
2329 struct inode *inode = mapping->host;
2330 struct shmem_inode_info *info = SHMEM_I(inode);
2331 pgoff_t index = pos >> PAGE_SHIFT;
2332
2333 /* i_mutex is held by caller */
2334 if (unlikely(info->seals & (F_SEAL_WRITE | F_SEAL_GROW))) {
2335 if (info->seals & F_SEAL_WRITE)
2336 return -EPERM;
2337 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2338 return -EPERM;
2339 }
2340
2341 return shmem_getpage(inode, index, pagep, SGP_WRITE);
2342 }
2343
2344 static int
2345 shmem_write_end(struct file *file, struct address_space *mapping,
2346 loff_t pos, unsigned len, unsigned copied,
2347 struct page *page, void *fsdata)
2348 {
2349 struct inode *inode = mapping->host;
2350
2351 if (pos + copied > inode->i_size)
2352 i_size_write(inode, pos + copied);
2353
2354 if (!PageUptodate(page)) {
2355 struct page *head = compound_head(page);
2356 if (PageTransCompound(page)) {
2357 int i;
2358
2359 for (i = 0; i < HPAGE_PMD_NR; i++) {
2360 if (head + i == page)
2361 continue;
2362 clear_highpage(head + i);
2363 flush_dcache_page(head + i);
2364 }
2365 }
2366 if (copied < PAGE_SIZE) {
2367 unsigned from = pos & (PAGE_SIZE - 1);
2368 zero_user_segments(page, 0, from,
2369 from + copied, PAGE_SIZE);
2370 }
2371 SetPageUptodate(head);
2372 }
2373 set_page_dirty(page);
2374 unlock_page(page);
2375 put_page(page);
2376
2377 return copied;
2378 }
2379
2380 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2381 {
2382 struct file *file = iocb->ki_filp;
2383 struct inode *inode = file_inode(file);
2384 struct address_space *mapping = inode->i_mapping;
2385 pgoff_t index;
2386 unsigned long offset;
2387 enum sgp_type sgp = SGP_READ;
2388 int error = 0;
2389 ssize_t retval = 0;
2390 loff_t *ppos = &iocb->ki_pos;
2391
2392 /*
2393 * Might this read be for a stacking filesystem? Then when reading
2394 * holes of a sparse file, we actually need to allocate those pages,
2395 * and even mark them dirty, so it cannot exceed the max_blocks limit.
2396 */
2397 if (!iter_is_iovec(to))
2398 sgp = SGP_CACHE;
2399
2400 index = *ppos >> PAGE_SHIFT;
2401 offset = *ppos & ~PAGE_MASK;
2402
2403 for (;;) {
2404 struct page *page = NULL;
2405 pgoff_t end_index;
2406 unsigned long nr, ret;
2407 loff_t i_size = i_size_read(inode);
2408
2409 end_index = i_size >> PAGE_SHIFT;
2410 if (index > end_index)
2411 break;
2412 if (index == end_index) {
2413 nr = i_size & ~PAGE_MASK;
2414 if (nr <= offset)
2415 break;
2416 }
2417
2418 error = shmem_getpage(inode, index, &page, sgp);
2419 if (error) {
2420 if (error == -EINVAL)
2421 error = 0;
2422 break;
2423 }
2424 if (page) {
2425 if (sgp == SGP_CACHE)
2426 set_page_dirty(page);
2427 unlock_page(page);
2428 }
2429
2430 /*
2431 * We must evaluate after, since reads (unlike writes)
2432 * are called without i_mutex protection against truncate
2433 */
2434 nr = PAGE_SIZE;
2435 i_size = i_size_read(inode);
2436 end_index = i_size >> PAGE_SHIFT;
2437 if (index == end_index) {
2438 nr = i_size & ~PAGE_MASK;
2439 if (nr <= offset) {
2440 if (page)
2441 put_page(page);
2442 break;
2443 }
2444 }
2445 nr -= offset;
2446
2447 if (page) {
2448 /*
2449 * If users can be writing to this page using arbitrary
2450 * virtual addresses, take care about potential aliasing
2451 * before reading the page on the kernel side.
2452 */
2453 if (mapping_writably_mapped(mapping))
2454 flush_dcache_page(page);
2455 /*
2456 * Mark the page accessed if we read the beginning.
2457 */
2458 if (!offset)
2459 mark_page_accessed(page);
2460 } else {
2461 page = ZERO_PAGE(0);
2462 get_page(page);
2463 }
2464
2465 /*
2466 * Ok, we have the page, and it's up-to-date, so
2467 * now we can copy it to user space...
2468 */
2469 ret = copy_page_to_iter(page, offset, nr, to);
2470 retval += ret;
2471 offset += ret;
2472 index += offset >> PAGE_SHIFT;
2473 offset &= ~PAGE_MASK;
2474
2475 put_page(page);
2476 if (!iov_iter_count(to))
2477 break;
2478 if (ret < nr) {
2479 error = -EFAULT;
2480 break;
2481 }
2482 cond_resched();
2483 }
2484
2485 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2486 file_accessed(file);
2487 return retval ? retval : error;
2488 }
2489
2490 /*
2491 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
2492 */
2493 static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
2494 pgoff_t index, pgoff_t end, int whence)
2495 {
2496 struct page *page;
2497 struct pagevec pvec;
2498 pgoff_t indices[PAGEVEC_SIZE];
2499 bool done = false;
2500 int i;
2501
2502 pagevec_init(&pvec, 0);
2503 pvec.nr = 1; /* start small: we may be there already */
2504 while (!done) {
2505 pvec.nr = find_get_entries(mapping, index,
2506 pvec.nr, pvec.pages, indices);
2507 if (!pvec.nr) {
2508 if (whence == SEEK_DATA)
2509 index = end;
2510 break;
2511 }
2512 for (i = 0; i < pvec.nr; i++, index++) {
2513 if (index < indices[i]) {
2514 if (whence == SEEK_HOLE) {
2515 done = true;
2516 break;
2517 }
2518 index = indices[i];
2519 }
2520 page = pvec.pages[i];
2521 if (page && !radix_tree_exceptional_entry(page)) {
2522 if (!PageUptodate(page))
2523 page = NULL;
2524 }
2525 if (index >= end ||
2526 (page && whence == SEEK_DATA) ||
2527 (!page && whence == SEEK_HOLE)) {
2528 done = true;
2529 break;
2530 }
2531 }
2532 pagevec_remove_exceptionals(&pvec);
2533 pagevec_release(&pvec);
2534 pvec.nr = PAGEVEC_SIZE;
2535 cond_resched();
2536 }
2537 return index;
2538 }
2539
2540 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2541 {
2542 struct address_space *mapping = file->f_mapping;
2543 struct inode *inode = mapping->host;
2544 pgoff_t start, end;
2545 loff_t new_offset;
2546
2547 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2548 return generic_file_llseek_size(file, offset, whence,
2549 MAX_LFS_FILESIZE, i_size_read(inode));
2550 inode_lock(inode);
2551 /* We're holding i_mutex so we can access i_size directly */
2552
2553 if (offset < 0)
2554 offset = -EINVAL;
2555 else if (offset >= inode->i_size)
2556 offset = -ENXIO;
2557 else {
2558 start = offset >> PAGE_SHIFT;
2559 end = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2560 new_offset = shmem_seek_hole_data(mapping, start, end, whence);
2561 new_offset <<= PAGE_SHIFT;
2562 if (new_offset > offset) {
2563 if (new_offset < inode->i_size)
2564 offset = new_offset;
2565 else if (whence == SEEK_DATA)
2566 offset = -ENXIO;
2567 else
2568 offset = inode->i_size;
2569 }
2570 }
2571
2572 if (offset >= 0)
2573 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2574 inode_unlock(inode);
2575 return offset;
2576 }
2577
2578 /*
2579 * We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
2580 * so reuse a tag which we firmly believe is never set or cleared on shmem.
2581 */
2582 #define SHMEM_TAG_PINNED PAGECACHE_TAG_TOWRITE
2583 #define LAST_SCAN 4 /* about 150ms max */
2584
2585 static void shmem_tag_pins(struct address_space *mapping)
2586 {
2587 struct radix_tree_iter iter;
2588 void **slot;
2589 pgoff_t start;
2590 struct page *page;
2591
2592 lru_add_drain();
2593 start = 0;
2594 rcu_read_lock();
2595
2596 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
2597 page = radix_tree_deref_slot(slot);
2598 if (!page || radix_tree_exception(page)) {
2599 if (radix_tree_deref_retry(page)) {
2600 slot = radix_tree_iter_retry(&iter);
2601 continue;
2602 }
2603 } else if (page_count(page) - page_mapcount(page) > 1) {
2604 spin_lock_irq(&mapping->tree_lock);
2605 radix_tree_tag_set(&mapping->page_tree, iter.index,
2606 SHMEM_TAG_PINNED);
2607 spin_unlock_irq(&mapping->tree_lock);
2608 }
2609
2610 if (need_resched()) {
2611 slot = radix_tree_iter_resume(slot, &iter);
2612 cond_resched_rcu();
2613 }
2614 }
2615 rcu_read_unlock();
2616 }
2617
2618 /*
2619 * Setting SEAL_WRITE requires us to verify there's no pending writer. However,
2620 * via get_user_pages(), drivers might have some pending I/O without any active
2621 * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages
2622 * and see whether it has an elevated ref-count. If so, we tag them and wait for
2623 * them to be dropped.
2624 * The caller must guarantee that no new user will acquire writable references
2625 * to those pages to avoid races.
2626 */
2627 static int shmem_wait_for_pins(struct address_space *mapping)
2628 {
2629 struct radix_tree_iter iter;
2630 void **slot;
2631 pgoff_t start;
2632 struct page *page;
2633 int error, scan;
2634
2635 shmem_tag_pins(mapping);
2636
2637 error = 0;
2638 for (scan = 0; scan <= LAST_SCAN; scan++) {
2639 if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED))
2640 break;
2641
2642 if (!scan)
2643 lru_add_drain_all();
2644 else if (schedule_timeout_killable((HZ << scan) / 200))
2645 scan = LAST_SCAN;
2646
2647 start = 0;
2648 rcu_read_lock();
2649 radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter,
2650 start, SHMEM_TAG_PINNED) {
2651
2652 page = radix_tree_deref_slot(slot);
2653 if (radix_tree_exception(page)) {
2654 if (radix_tree_deref_retry(page)) {
2655 slot = radix_tree_iter_retry(&iter);
2656 continue;
2657 }
2658
2659 page = NULL;
2660 }
2661
2662 if (page &&
2663 page_count(page) - page_mapcount(page) != 1) {
2664 if (scan < LAST_SCAN)
2665 goto continue_resched;
2666
2667 /*
2668 * On the last scan, we clean up all those tags
2669 * we inserted; but make a note that we still
2670 * found pages pinned.
2671 */
2672 error = -EBUSY;
2673 }
2674
2675 spin_lock_irq(&mapping->tree_lock);
2676 radix_tree_tag_clear(&mapping->page_tree,
2677 iter.index, SHMEM_TAG_PINNED);
2678 spin_unlock_irq(&mapping->tree_lock);
2679 continue_resched:
2680 if (need_resched()) {
2681 slot = radix_tree_iter_resume(slot, &iter);
2682 cond_resched_rcu();
2683 }
2684 }
2685 rcu_read_unlock();
2686 }
2687
2688 return error;
2689 }
2690
2691 #define F_ALL_SEALS (F_SEAL_SEAL | \
2692 F_SEAL_SHRINK | \
2693 F_SEAL_GROW | \
2694 F_SEAL_WRITE)
2695
2696 int shmem_add_seals(struct file *file, unsigned int seals)
2697 {
2698 struct inode *inode = file_inode(file);
2699 struct shmem_inode_info *info = SHMEM_I(inode);
2700 int error;
2701
2702 /*
2703 * SEALING
2704 * Sealing allows multiple parties to share a shmem-file but restrict
2705 * access to a specific subset of file operations. Seals can only be
2706 * added, but never removed. This way, mutually untrusted parties can
2707 * share common memory regions with a well-defined policy. A malicious
2708 * peer can thus never perform unwanted operations on a shared object.
2709 *
2710 * Seals are only supported on special shmem-files and always affect
2711 * the whole underlying inode. Once a seal is set, it may prevent some
2712 * kinds of access to the file. Currently, the following seals are
2713 * defined:
2714 * SEAL_SEAL: Prevent further seals from being set on this file
2715 * SEAL_SHRINK: Prevent the file from shrinking
2716 * SEAL_GROW: Prevent the file from growing
2717 * SEAL_WRITE: Prevent write access to the file
2718 *
2719 * As we don't require any trust relationship between two parties, we
2720 * must prevent seals from being removed. Therefore, sealing a file
2721 * only adds a given set of seals to the file, it never touches
2722 * existing seals. Furthermore, the "setting seals"-operation can be
2723 * sealed itself, which basically prevents any further seal from being
2724 * added.
2725 *
2726 * Semantics of sealing are only defined on volatile files. Only
2727 * anonymous shmem files support sealing. More importantly, seals are
2728 * never written to disk. Therefore, there's no plan to support it on
2729 * other file types.
2730 */
2731
2732 if (file->f_op != &shmem_file_operations)
2733 return -EINVAL;
2734 if (!(file->f_mode & FMODE_WRITE))
2735 return -EPERM;
2736 if (seals & ~(unsigned int)F_ALL_SEALS)
2737 return -EINVAL;
2738
2739 inode_lock(inode);
2740
2741 if (info->seals & F_SEAL_SEAL) {
2742 error = -EPERM;
2743 goto unlock;
2744 }
2745
2746 if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) {
2747 error = mapping_deny_writable(file->f_mapping);
2748 if (error)
2749 goto unlock;
2750
2751 error = shmem_wait_for_pins(file->f_mapping);
2752 if (error) {
2753 mapping_allow_writable(file->f_mapping);
2754 goto unlock;
2755 }
2756 }
2757
2758 info->seals |= seals;
2759 error = 0;
2760
2761 unlock:
2762 inode_unlock(inode);
2763 return error;
2764 }
2765 EXPORT_SYMBOL_GPL(shmem_add_seals);
2766
2767 int shmem_get_seals(struct file *file)
2768 {
2769 if (file->f_op != &shmem_file_operations)
2770 return -EINVAL;
2771
2772 return SHMEM_I(file_inode(file))->seals;
2773 }
2774 EXPORT_SYMBOL_GPL(shmem_get_seals);
2775
2776 long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
2777 {
2778 long error;
2779
2780 switch (cmd) {
2781 case F_ADD_SEALS:
2782 /* disallow upper 32bit */
2783 if (arg > UINT_MAX)
2784 return -EINVAL;
2785
2786 error = shmem_add_seals(file, arg);
2787 break;
2788 case F_GET_SEALS:
2789 error = shmem_get_seals(file);
2790 break;
2791 default:
2792 error = -EINVAL;
2793 break;
2794 }
2795
2796 return error;
2797 }
2798
2799 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2800 loff_t len)
2801 {
2802 struct inode *inode = file_inode(file);
2803 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2804 struct shmem_inode_info *info = SHMEM_I(inode);
2805 struct shmem_falloc shmem_falloc;
2806 pgoff_t start, index, end;
2807 int error;
2808
2809 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2810 return -EOPNOTSUPP;
2811
2812 inode_lock(inode);
2813
2814 if (mode & FALLOC_FL_PUNCH_HOLE) {
2815 struct address_space *mapping = file->f_mapping;
2816 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2817 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2818 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2819
2820 /* protected by i_mutex */
2821 if (info->seals & F_SEAL_WRITE) {
2822 error = -EPERM;
2823 goto out;
2824 }
2825
2826 shmem_falloc.waitq = &shmem_falloc_waitq;
2827 shmem_falloc.start = unmap_start >> PAGE_SHIFT;
2828 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2829 spin_lock(&inode->i_lock);
2830 inode->i_private = &shmem_falloc;
2831 spin_unlock(&inode->i_lock);
2832
2833 if ((u64)unmap_end > (u64)unmap_start)
2834 unmap_mapping_range(mapping, unmap_start,
2835 1 + unmap_end - unmap_start, 0);
2836 shmem_truncate_range(inode, offset, offset + len - 1);
2837 /* No need to unmap again: hole-punching leaves COWed pages */
2838
2839 spin_lock(&inode->i_lock);
2840 inode->i_private = NULL;
2841 wake_up_all(&shmem_falloc_waitq);
2842 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.task_list));
2843 spin_unlock(&inode->i_lock);
2844 error = 0;
2845 goto out;
2846 }
2847
2848 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2849 error = inode_newsize_ok(inode, offset + len);
2850 if (error)
2851 goto out;
2852
2853 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2854 error = -EPERM;
2855 goto out;
2856 }
2857
2858 start = offset >> PAGE_SHIFT;
2859 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2860 /* Try to avoid a swapstorm if len is impossible to satisfy */
2861 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2862 error = -ENOSPC;
2863 goto out;
2864 }
2865
2866 shmem_falloc.waitq = NULL;
2867 shmem_falloc.start = start;
2868 shmem_falloc.next = start;
2869 shmem_falloc.nr_falloced = 0;
2870 shmem_falloc.nr_unswapped = 0;
2871 spin_lock(&inode->i_lock);
2872 inode->i_private = &shmem_falloc;
2873 spin_unlock(&inode->i_lock);
2874
2875 for (index = start; index < end; index++) {
2876 struct page *page;
2877
2878 /*
2879 * Good, the fallocate(2) manpage permits EINTR: we may have
2880 * been interrupted because we are using up too much memory.
2881 */
2882 if (signal_pending(current))
2883 error = -EINTR;
2884 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2885 error = -ENOMEM;
2886 else
2887 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2888 if (error) {
2889 /* Remove the !PageUptodate pages we added */
2890 if (index > start) {
2891 shmem_undo_range(inode,
2892 (loff_t)start << PAGE_SHIFT,
2893 ((loff_t)index << PAGE_SHIFT) - 1, true);
2894 }
2895 goto undone;
2896 }
2897
2898 /*
2899 * Inform shmem_writepage() how far we have reached.
2900 * No need for lock or barrier: we have the page lock.
2901 */
2902 shmem_falloc.next++;
2903 if (!PageUptodate(page))
2904 shmem_falloc.nr_falloced++;
2905
2906 /*
2907 * If !PageUptodate, leave it that way so that freeable pages
2908 * can be recognized if we need to rollback on error later.
2909 * But set_page_dirty so that memory pressure will swap rather
2910 * than free the pages we are allocating (and SGP_CACHE pages
2911 * might still be clean: we now need to mark those dirty too).
2912 */
2913 set_page_dirty(page);
2914 unlock_page(page);
2915 put_page(page);
2916 cond_resched();
2917 }
2918
2919 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2920 i_size_write(inode, offset + len);
2921 inode->i_ctime = current_time(inode);
2922 undone:
2923 spin_lock(&inode->i_lock);
2924 inode->i_private = NULL;
2925 spin_unlock(&inode->i_lock);
2926 out:
2927 inode_unlock(inode);
2928 return error;
2929 }
2930
2931 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2932 {
2933 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2934
2935 buf->f_type = TMPFS_MAGIC;
2936 buf->f_bsize = PAGE_SIZE;
2937 buf->f_namelen = NAME_MAX;
2938 if (sbinfo->max_blocks) {
2939 buf->f_blocks = sbinfo->max_blocks;
2940 buf->f_bavail =
2941 buf->f_bfree = sbinfo->max_blocks -
2942 percpu_counter_sum(&sbinfo->used_blocks);
2943 }
2944 if (sbinfo->max_inodes) {
2945 buf->f_files = sbinfo->max_inodes;
2946 buf->f_ffree = sbinfo->free_inodes;
2947 }
2948 /* else leave those fields 0 like simple_statfs */
2949 return 0;
2950 }
2951
2952 /*
2953 * File creation. Allocate an inode, and we're done..
2954 */
2955 static int
2956 shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
2957 {
2958 struct inode *inode;
2959 int error = -ENOSPC;
2960
2961 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2962 if (inode) {
2963 error = simple_acl_create(dir, inode);
2964 if (error)
2965 goto out_iput;
2966 error = security_inode_init_security(inode, dir,
2967 &dentry->d_name,
2968 shmem_initxattrs, NULL);
2969 if (error && error != -EOPNOTSUPP)
2970 goto out_iput;
2971
2972 error = 0;
2973 dir->i_size += BOGO_DIRENT_SIZE;
2974 dir->i_ctime = dir->i_mtime = current_time(dir);
2975 d_instantiate(dentry, inode);
2976 dget(dentry); /* Extra count - pin the dentry in core */
2977 }
2978 return error;
2979 out_iput:
2980 iput(inode);
2981 return error;
2982 }
2983
2984 static int
2985 shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
2986 {
2987 struct inode *inode;
2988 int error = -ENOSPC;
2989
2990 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2991 if (inode) {
2992 error = security_inode_init_security(inode, dir,
2993 NULL,
2994 shmem_initxattrs, NULL);
2995 if (error && error != -EOPNOTSUPP)
2996 goto out_iput;
2997 error = simple_acl_create(dir, inode);
2998 if (error)
2999 goto out_iput;
3000 d_tmpfile(dentry, inode);
3001 }
3002 return error;
3003 out_iput:
3004 iput(inode);
3005 return error;
3006 }
3007
3008 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
3009 {
3010 int error;
3011
3012 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
3013 return error;
3014 inc_nlink(dir);
3015 return 0;
3016 }
3017
3018 static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
3019 bool excl)
3020 {
3021 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
3022 }
3023
3024 /*
3025 * Link a file..
3026 */
3027 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
3028 {
3029 struct inode *inode = d_inode(old_dentry);
3030 int ret;
3031
3032 /*
3033 * No ordinary (disk based) filesystem counts links as inodes;
3034 * but each new link needs a new dentry, pinning lowmem, and
3035 * tmpfs dentries cannot be pruned until they are unlinked.
3036 */
3037 ret = shmem_reserve_inode(inode->i_sb);
3038 if (ret)
3039 goto out;
3040
3041 dir->i_size += BOGO_DIRENT_SIZE;
3042 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
3043 inc_nlink(inode);
3044 ihold(inode); /* New dentry reference */
3045 dget(dentry); /* Extra pinning count for the created dentry */
3046 d_instantiate(dentry, inode);
3047 out:
3048 return ret;
3049 }
3050
3051 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
3052 {
3053 struct inode *inode = d_inode(dentry);
3054
3055 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
3056 shmem_free_inode(inode->i_sb);
3057
3058 dir->i_size -= BOGO_DIRENT_SIZE;
3059 inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
3060 drop_nlink(inode);
3061 dput(dentry); /* Undo the count from "create" - this does all the work */
3062 return 0;
3063 }
3064
3065 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3066 {
3067 if (!simple_empty(dentry))
3068 return -ENOTEMPTY;
3069
3070 drop_nlink(d_inode(dentry));
3071 drop_nlink(dir);
3072 return shmem_unlink(dir, dentry);
3073 }
3074
3075 static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
3076 {
3077 bool old_is_dir = d_is_dir(old_dentry);
3078 bool new_is_dir = d_is_dir(new_dentry);
3079
3080 if (old_dir != new_dir && old_is_dir != new_is_dir) {
3081 if (old_is_dir) {
3082 drop_nlink(old_dir);
3083 inc_nlink(new_dir);
3084 } else {
3085 drop_nlink(new_dir);
3086 inc_nlink(old_dir);
3087 }
3088 }
3089 old_dir->i_ctime = old_dir->i_mtime =
3090 new_dir->i_ctime = new_dir->i_mtime =
3091 d_inode(old_dentry)->i_ctime =
3092 d_inode(new_dentry)->i_ctime = current_time(old_dir);
3093
3094 return 0;
3095 }
3096
3097 static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
3098 {
3099 struct dentry *whiteout;
3100 int error;
3101
3102 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3103 if (!whiteout)
3104 return -ENOMEM;
3105
3106 error = shmem_mknod(old_dir, whiteout,
3107 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3108 dput(whiteout);
3109 if (error)
3110 return error;
3111
3112 /*
3113 * Cheat and hash the whiteout while the old dentry is still in
3114 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3115 *
3116 * d_lookup() will consistently find one of them at this point,
3117 * not sure which one, but that isn't even important.
3118 */
3119 d_rehash(whiteout);
3120 return 0;
3121 }
3122
3123 /*
3124 * The VFS layer already does all the dentry stuff for rename,
3125 * we just have to decrement the usage count for the target if
3126 * it exists so that the VFS layer correctly free's it when it
3127 * gets overwritten.
3128 */
3129 static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
3130 {
3131 struct inode *inode = d_inode(old_dentry);
3132 int they_are_dirs = S_ISDIR(inode->i_mode);
3133
3134 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3135 return -EINVAL;
3136
3137 if (flags & RENAME_EXCHANGE)
3138 return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
3139
3140 if (!simple_empty(new_dentry))
3141 return -ENOTEMPTY;
3142
3143 if (flags & RENAME_WHITEOUT) {
3144 int error;
3145
3146 error = shmem_whiteout(old_dir, old_dentry);
3147 if (error)
3148 return error;
3149 }
3150
3151 if (d_really_is_positive(new_dentry)) {
3152 (void) shmem_unlink(new_dir, new_dentry);
3153 if (they_are_dirs) {
3154 drop_nlink(d_inode(new_dentry));
3155 drop_nlink(old_dir);
3156 }
3157 } else if (they_are_dirs) {
3158 drop_nlink(old_dir);
3159 inc_nlink(new_dir);
3160 }
3161
3162 old_dir->i_size -= BOGO_DIRENT_SIZE;
3163 new_dir->i_size += BOGO_DIRENT_SIZE;
3164 old_dir->i_ctime = old_dir->i_mtime =
3165 new_dir->i_ctime = new_dir->i_mtime =
3166 inode->i_ctime = current_time(old_dir);
3167 return 0;
3168 }
3169
3170 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
3171 {
3172 int error;
3173 int len;
3174 struct inode *inode;
3175 struct page *page;
3176 struct shmem_inode_info *info;
3177
3178 len = strlen(symname) + 1;
3179 if (len > PAGE_SIZE)
3180 return -ENAMETOOLONG;
3181
3182 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
3183 if (!inode)
3184 return -ENOSPC;
3185
3186 error = security_inode_init_security(inode, dir, &dentry->d_name,
3187 shmem_initxattrs, NULL);
3188 if (error) {
3189 if (error != -EOPNOTSUPP) {
3190 iput(inode);
3191 return error;
3192 }
3193 error = 0;
3194 }
3195
3196 info = SHMEM_I(inode);
3197 inode->i_size = len-1;
3198 if (len <= SHORT_SYMLINK_LEN) {
3199 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3200 if (!inode->i_link) {
3201 iput(inode);
3202 return -ENOMEM;
3203 }
3204 inode->i_op = &shmem_short_symlink_operations;
3205 } else {
3206 inode_nohighmem(inode);
3207 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3208 if (error) {
3209 iput(inode);
3210 return error;
3211 }
3212 inode->i_mapping->a_ops = &shmem_aops;
3213 inode->i_op = &shmem_symlink_inode_operations;
3214 memcpy(page_address(page), symname, len);
3215 SetPageUptodate(page);
3216 set_page_dirty(page);
3217 unlock_page(page);
3218 put_page(page);
3219 }
3220 dir->i_size += BOGO_DIRENT_SIZE;
3221 dir->i_ctime = dir->i_mtime = current_time(dir);
3222 d_instantiate(dentry, inode);
3223 dget(dentry);
3224 return 0;
3225 }
3226
3227 static void shmem_put_link(void *arg)
3228 {
3229 mark_page_accessed(arg);
3230 put_page(arg);
3231 }
3232
3233 static const char *shmem_get_link(struct dentry *dentry,
3234 struct inode *inode,
3235 struct delayed_call *done)
3236 {
3237 struct page *page = NULL;
3238 int error;
3239 if (!dentry) {
3240 page = find_get_page(inode->i_mapping, 0);
3241 if (!page)
3242 return ERR_PTR(-ECHILD);
3243 if (!PageUptodate(page)) {
3244 put_page(page);
3245 return ERR_PTR(-ECHILD);
3246 }
3247 } else {
3248 error = shmem_getpage(inode, 0, &page, SGP_READ);
3249 if (error)
3250 return ERR_PTR(error);
3251 unlock_page(page);
3252 }
3253 set_delayed_call(done, shmem_put_link, page);
3254 return page_address(page);
3255 }
3256
3257 #ifdef CONFIG_TMPFS_XATTR
3258 /*
3259 * Superblocks without xattr inode operations may get some security.* xattr
3260 * support from the LSM "for free". As soon as we have any other xattrs
3261 * like ACLs, we also need to implement the security.* handlers at
3262 * filesystem level, though.
3263 */
3264
3265 /*
3266 * Callback for security_inode_init_security() for acquiring xattrs.
3267 */
3268 static int shmem_initxattrs(struct inode *inode,
3269 const struct xattr *xattr_array,
3270 void *fs_info)
3271 {
3272 struct shmem_inode_info *info = SHMEM_I(inode);
3273 const struct xattr *xattr;
3274 struct simple_xattr *new_xattr;
3275 size_t len;
3276
3277 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3278 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3279 if (!new_xattr)
3280 return -ENOMEM;
3281
3282 len = strlen(xattr->name) + 1;
3283 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3284 GFP_KERNEL);
3285 if (!new_xattr->name) {
3286 kfree(new_xattr);
3287 return -ENOMEM;
3288 }
3289
3290 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3291 XATTR_SECURITY_PREFIX_LEN);
3292 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3293 xattr->name, len);
3294
3295 simple_xattr_list_add(&info->xattrs, new_xattr);
3296 }
3297
3298 return 0;
3299 }
3300
3301 static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3302 struct dentry *unused, struct inode *inode,
3303 const char *name, void *buffer, size_t size)
3304 {
3305 struct shmem_inode_info *info = SHMEM_I(inode);
3306
3307 name = xattr_full_name(handler, name);
3308 return simple_xattr_get(&info->xattrs, name, buffer, size);
3309 }
3310
3311 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3312 struct dentry *unused, struct inode *inode,
3313 const char *name, const void *value,
3314 size_t size, int flags)
3315 {
3316 struct shmem_inode_info *info = SHMEM_I(inode);
3317
3318 name = xattr_full_name(handler, name);
3319 return simple_xattr_set(&info->xattrs, name, value, size, flags);
3320 }
3321
3322 static const struct xattr_handler shmem_security_xattr_handler = {
3323 .prefix = XATTR_SECURITY_PREFIX,
3324 .get = shmem_xattr_handler_get,
3325 .set = shmem_xattr_handler_set,
3326 };
3327
3328 static const struct xattr_handler shmem_trusted_xattr_handler = {
3329 .prefix = XATTR_TRUSTED_PREFIX,
3330 .get = shmem_xattr_handler_get,
3331 .set = shmem_xattr_handler_set,
3332 };
3333
3334 static const struct xattr_handler *shmem_xattr_handlers[] = {
3335 #ifdef CONFIG_TMPFS_POSIX_ACL
3336 &posix_acl_access_xattr_handler,
3337 &posix_acl_default_xattr_handler,
3338 #endif
3339 &shmem_security_xattr_handler,
3340 &shmem_trusted_xattr_handler,
3341 NULL
3342 };
3343
3344 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3345 {
3346 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3347 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3348 }
3349 #endif /* CONFIG_TMPFS_XATTR */
3350
3351 static const struct inode_operations shmem_short_symlink_operations = {
3352 .get_link = simple_get_link,
3353 #ifdef CONFIG_TMPFS_XATTR
3354 .listxattr = shmem_listxattr,
3355 #endif
3356 };
3357
3358 static const struct inode_operations shmem_symlink_inode_operations = {
3359 .get_link = shmem_get_link,
3360 #ifdef CONFIG_TMPFS_XATTR
3361 .listxattr = shmem_listxattr,
3362 #endif
3363 };
3364
3365 static struct dentry *shmem_get_parent(struct dentry *child)
3366 {
3367 return ERR_PTR(-ESTALE);
3368 }
3369
3370 static int shmem_match(struct inode *ino, void *vfh)
3371 {
3372 __u32 *fh = vfh;
3373 __u64 inum = fh[2];
3374 inum = (inum << 32) | fh[1];
3375 return ino->i_ino == inum && fh[0] == ino->i_generation;
3376 }
3377
3378 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3379 struct fid *fid, int fh_len, int fh_type)
3380 {
3381 struct inode *inode;
3382 struct dentry *dentry = NULL;
3383 u64 inum;
3384
3385 if (fh_len < 3)
3386 return NULL;
3387
3388 inum = fid->raw[2];
3389 inum = (inum << 32) | fid->raw[1];
3390
3391 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3392 shmem_match, fid->raw);
3393 if (inode) {
3394 dentry = d_find_alias(inode);
3395 iput(inode);
3396 }
3397
3398 return dentry;
3399 }
3400
3401 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3402 struct inode *parent)
3403 {
3404 if (*len < 3) {
3405 *len = 3;
3406 return FILEID_INVALID;
3407 }
3408
3409 if (inode_unhashed(inode)) {
3410 /* Unfortunately insert_inode_hash is not idempotent,
3411 * so as we hash inodes here rather than at creation
3412 * time, we need a lock to ensure we only try
3413 * to do it once
3414 */
3415 static DEFINE_SPINLOCK(lock);
3416 spin_lock(&lock);
3417 if (inode_unhashed(inode))
3418 __insert_inode_hash(inode,
3419 inode->i_ino + inode->i_generation);
3420 spin_unlock(&lock);
3421 }
3422
3423 fh[0] = inode->i_generation;
3424 fh[1] = inode->i_ino;
3425 fh[2] = ((__u64)inode->i_ino) >> 32;
3426
3427 *len = 3;
3428 return 1;
3429 }
3430
3431 static const struct export_operations shmem_export_ops = {
3432 .get_parent = shmem_get_parent,
3433 .encode_fh = shmem_encode_fh,
3434 .fh_to_dentry = shmem_fh_to_dentry,
3435 };
3436
3437 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
3438 bool remount)
3439 {
3440 char *this_char, *value, *rest;
3441 struct mempolicy *mpol = NULL;
3442 uid_t uid;
3443 gid_t gid;
3444
3445 while (options != NULL) {
3446 this_char = options;
3447 for (;;) {
3448 /*
3449 * NUL-terminate this option: unfortunately,
3450 * mount options form a comma-separated list,
3451 * but mpol's nodelist may also contain commas.
3452 */
3453 options = strchr(options, ',');
3454 if (options == NULL)
3455 break;
3456 options++;
3457 if (!isdigit(*options)) {
3458 options[-1] = '\0';
3459 break;
3460 }
3461 }
3462 if (!*this_char)
3463 continue;
3464 if ((value = strchr(this_char,'=')) != NULL) {
3465 *value++ = 0;
3466 } else {
3467 pr_err("tmpfs: No value for mount option '%s'\n",
3468 this_char);
3469 goto error;
3470 }
3471
3472 if (!strcmp(this_char,"size")) {
3473 unsigned long long size;
3474 size = memparse(value,&rest);
3475 if (*rest == '%') {
3476 size <<= PAGE_SHIFT;
3477 size *= totalram_pages;
3478 do_div(size, 100);
3479 rest++;
3480 }
3481 if (*rest)
3482 goto bad_val;
3483 sbinfo->max_blocks =
3484 DIV_ROUND_UP(size, PAGE_SIZE);
3485 } else if (!strcmp(this_char,"nr_blocks")) {
3486 sbinfo->max_blocks = memparse(value, &rest);
3487 if (*rest)
3488 goto bad_val;
3489 } else if (!strcmp(this_char,"nr_inodes")) {
3490 sbinfo->max_inodes = memparse(value, &rest);
3491 if (*rest)
3492 goto bad_val;
3493 } else if (!strcmp(this_char,"mode")) {
3494 if (remount)
3495 continue;
3496 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
3497 if (*rest)
3498 goto bad_val;
3499 } else if (!strcmp(this_char,"uid")) {
3500 if (remount)
3501 continue;
3502 uid = simple_strtoul(value, &rest, 0);
3503 if (*rest)
3504 goto bad_val;
3505 sbinfo->uid = make_kuid(current_user_ns(), uid);
3506 if (!uid_valid(sbinfo->uid))
3507 goto bad_val;
3508 } else if (!strcmp(this_char,"gid")) {
3509 if (remount)
3510 continue;
3511 gid = simple_strtoul(value, &rest, 0);
3512 if (*rest)
3513 goto bad_val;
3514 sbinfo->gid = make_kgid(current_user_ns(), gid);
3515 if (!gid_valid(sbinfo->gid))
3516 goto bad_val;
3517 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3518 } else if (!strcmp(this_char, "huge")) {
3519 int huge;
3520 huge = shmem_parse_huge(value);
3521 if (huge < 0)
3522 goto bad_val;
3523 if (!has_transparent_hugepage() &&
3524 huge != SHMEM_HUGE_NEVER)
3525 goto bad_val;
3526 sbinfo->huge = huge;
3527 #endif
3528 #ifdef CONFIG_NUMA
3529 } else if (!strcmp(this_char,"mpol")) {
3530 mpol_put(mpol);
3531 mpol = NULL;
3532 if (mpol_parse_str(value, &mpol))
3533 goto bad_val;
3534 #endif
3535 } else {
3536 pr_err("tmpfs: Bad mount option %s\n", this_char);
3537 goto error;
3538 }
3539 }
3540 sbinfo->mpol = mpol;
3541 return 0;
3542
3543 bad_val:
3544 pr_err("tmpfs: Bad value '%s' for mount option '%s'\n",
3545 value, this_char);
3546 error:
3547 mpol_put(mpol);
3548 return 1;
3549
3550 }
3551
3552 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
3553 {
3554 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3555 struct shmem_sb_info config = *sbinfo;
3556 unsigned long inodes;
3557 int error = -EINVAL;
3558
3559 config.mpol = NULL;
3560 if (shmem_parse_options(data, &config, true))
3561 return error;
3562
3563 spin_lock(&sbinfo->stat_lock);
3564 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3565 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
3566 goto out;
3567 if (config.max_inodes < inodes)
3568 goto out;
3569 /*
3570 * Those tests disallow limited->unlimited while any are in use;
3571 * but we must separately disallow unlimited->limited, because
3572 * in that case we have no record of how much is already in use.
3573 */
3574 if (config.max_blocks && !sbinfo->max_blocks)
3575 goto out;
3576 if (config.max_inodes && !sbinfo->max_inodes)
3577 goto out;
3578
3579 error = 0;
3580 sbinfo->huge = config.huge;
3581 sbinfo->max_blocks = config.max_blocks;
3582 sbinfo->max_inodes = config.max_inodes;
3583 sbinfo->free_inodes = config.max_inodes - inodes;
3584
3585 /*
3586 * Preserve previous mempolicy unless mpol remount option was specified.
3587 */
3588 if (config.mpol) {
3589 mpol_put(sbinfo->mpol);
3590 sbinfo->mpol = config.mpol; /* transfers initial ref */
3591 }
3592 out:
3593 spin_unlock(&sbinfo->stat_lock);
3594 return error;
3595 }
3596
3597 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3598 {
3599 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3600
3601 if (sbinfo->max_blocks != shmem_default_max_blocks())
3602 seq_printf(seq, ",size=%luk",
3603 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3604 if (sbinfo->max_inodes != shmem_default_max_inodes())
3605 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3606 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
3607 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3608 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3609 seq_printf(seq, ",uid=%u",
3610 from_kuid_munged(&init_user_ns, sbinfo->uid));
3611 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3612 seq_printf(seq, ",gid=%u",
3613 from_kgid_munged(&init_user_ns, sbinfo->gid));
3614 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3615 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3616 if (sbinfo->huge)
3617 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3618 #endif
3619 shmem_show_mpol(seq, sbinfo->mpol);
3620 return 0;
3621 }
3622
3623 #define MFD_NAME_PREFIX "memfd:"
3624 #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
3625 #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
3626
3627 #define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
3628
3629 SYSCALL_DEFINE2(memfd_create,
3630 const char __user *, uname,
3631 unsigned int, flags)
3632 {
3633 struct shmem_inode_info *info;
3634 struct file *file;
3635 int fd, error;
3636 char *name;
3637 long len;
3638
3639 if (flags & ~(unsigned int)MFD_ALL_FLAGS)
3640 return -EINVAL;
3641
3642 /* length includes terminating zero */
3643 len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
3644 if (len <= 0)
3645 return -EFAULT;
3646 if (len > MFD_NAME_MAX_LEN + 1)
3647 return -EINVAL;
3648
3649 name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
3650 if (!name)
3651 return -ENOMEM;
3652
3653 strcpy(name, MFD_NAME_PREFIX);
3654 if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
3655 error = -EFAULT;
3656 goto err_name;
3657 }
3658
3659 /* terminating-zero may have changed after strnlen_user() returned */
3660 if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
3661 error = -EFAULT;
3662 goto err_name;
3663 }
3664
3665 fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
3666 if (fd < 0) {
3667 error = fd;
3668 goto err_name;
3669 }
3670
3671 file = shmem_file_setup(name, 0, VM_NORESERVE);
3672 if (IS_ERR(file)) {
3673 error = PTR_ERR(file);
3674 goto err_fd;
3675 }
3676 info = SHMEM_I(file_inode(file));
3677 file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
3678 file->f_flags |= O_RDWR | O_LARGEFILE;
3679 if (flags & MFD_ALLOW_SEALING)
3680 info->seals &= ~F_SEAL_SEAL;
3681
3682 fd_install(fd, file);
3683 kfree(name);
3684 return fd;
3685
3686 err_fd:
3687 put_unused_fd(fd);
3688 err_name:
3689 kfree(name);
3690 return error;
3691 }
3692
3693 #endif /* CONFIG_TMPFS */
3694
3695 static void shmem_put_super(struct super_block *sb)
3696 {
3697 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3698
3699 percpu_counter_destroy(&sbinfo->used_blocks);
3700 mpol_put(sbinfo->mpol);
3701 kfree(sbinfo);
3702 sb->s_fs_info = NULL;
3703 }
3704
3705 int shmem_fill_super(struct super_block *sb, void *data, int silent)
3706 {
3707 struct inode *inode;
3708 struct shmem_sb_info *sbinfo;
3709 int err = -ENOMEM;
3710
3711 /* Round up to L1_CACHE_BYTES to resist false sharing */
3712 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3713 L1_CACHE_BYTES), GFP_KERNEL);
3714 if (!sbinfo)
3715 return -ENOMEM;
3716
3717 sbinfo->mode = S_IRWXUGO | S_ISVTX;
3718 sbinfo->uid = current_fsuid();
3719 sbinfo->gid = current_fsgid();
3720 sb->s_fs_info = sbinfo;
3721
3722 #ifdef CONFIG_TMPFS
3723 /*
3724 * Per default we only allow half of the physical ram per
3725 * tmpfs instance, limiting inodes to one per page of lowmem;
3726 * but the internal instance is left unlimited.
3727 */
3728 if (!(sb->s_flags & MS_KERNMOUNT)) {
3729 sbinfo->max_blocks = shmem_default_max_blocks();
3730 sbinfo->max_inodes = shmem_default_max_inodes();
3731 if (shmem_parse_options(data, sbinfo, false)) {
3732 err = -EINVAL;
3733 goto failed;
3734 }
3735 } else {
3736 sb->s_flags |= MS_NOUSER;
3737 }
3738 sb->s_export_op = &shmem_export_ops;
3739 sb->s_flags |= MS_NOSEC;
3740 #else
3741 sb->s_flags |= MS_NOUSER;
3742 #endif
3743
3744 spin_lock_init(&sbinfo->stat_lock);
3745 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3746 goto failed;
3747 sbinfo->free_inodes = sbinfo->max_inodes;
3748 spin_lock_init(&sbinfo->shrinklist_lock);
3749 INIT_LIST_HEAD(&sbinfo->shrinklist);
3750
3751 sb->s_maxbytes = MAX_LFS_FILESIZE;
3752 sb->s_blocksize = PAGE_SIZE;
3753 sb->s_blocksize_bits = PAGE_SHIFT;
3754 sb->s_magic = TMPFS_MAGIC;
3755 sb->s_op = &shmem_ops;
3756 sb->s_time_gran = 1;
3757 #ifdef CONFIG_TMPFS_XATTR
3758 sb->s_xattr = shmem_xattr_handlers;
3759 #endif
3760 #ifdef CONFIG_TMPFS_POSIX_ACL
3761 sb->s_flags |= MS_POSIXACL;
3762 #endif
3763
3764 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3765 if (!inode)
3766 goto failed;
3767 inode->i_uid = sbinfo->uid;
3768 inode->i_gid = sbinfo->gid;
3769 sb->s_root = d_make_root(inode);
3770 if (!sb->s_root)
3771 goto failed;
3772 return 0;
3773
3774 failed:
3775 shmem_put_super(sb);
3776 return err;
3777 }
3778
3779 static struct kmem_cache *shmem_inode_cachep;
3780
3781 static struct inode *shmem_alloc_inode(struct super_block *sb)
3782 {
3783 struct shmem_inode_info *info;
3784 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
3785 if (!info)
3786 return NULL;
3787 return &info->vfs_inode;
3788 }
3789
3790 static void shmem_destroy_callback(struct rcu_head *head)
3791 {
3792 struct inode *inode = container_of(head, struct inode, i_rcu);
3793 if (S_ISLNK(inode->i_mode))
3794 kfree(inode->i_link);
3795 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3796 }
3797
3798 static void shmem_destroy_inode(struct inode *inode)
3799 {
3800 if (S_ISREG(inode->i_mode))
3801 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3802 call_rcu(&inode->i_rcu, shmem_destroy_callback);
3803 }
3804
3805 static void shmem_init_inode(void *foo)
3806 {
3807 struct shmem_inode_info *info = foo;
3808 inode_init_once(&info->vfs_inode);
3809 }
3810
3811 static int shmem_init_inodecache(void)
3812 {
3813 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3814 sizeof(struct shmem_inode_info),
3815 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3816 return 0;
3817 }
3818
3819 static void shmem_destroy_inodecache(void)
3820 {
3821 kmem_cache_destroy(shmem_inode_cachep);
3822 }
3823
3824 static const struct address_space_operations shmem_aops = {
3825 .writepage = shmem_writepage,
3826 .set_page_dirty = __set_page_dirty_no_writeback,
3827 #ifdef CONFIG_TMPFS
3828 .write_begin = shmem_write_begin,
3829 .write_end = shmem_write_end,
3830 #endif
3831 #ifdef CONFIG_MIGRATION
3832 .migratepage = migrate_page,
3833 #endif
3834 .error_remove_page = generic_error_remove_page,
3835 };
3836
3837 static const struct file_operations shmem_file_operations = {
3838 .mmap = shmem_mmap,
3839 .get_unmapped_area = shmem_get_unmapped_area,
3840 #ifdef CONFIG_TMPFS
3841 .llseek = shmem_file_llseek,
3842 .read_iter = shmem_file_read_iter,
3843 .write_iter = generic_file_write_iter,
3844 .fsync = noop_fsync,
3845 .splice_read = generic_file_splice_read,
3846 .splice_write = iter_file_splice_write,
3847 .fallocate = shmem_fallocate,
3848 #endif
3849 };
3850
3851 static const struct inode_operations shmem_inode_operations = {
3852 .getattr = shmem_getattr,
3853 .setattr = shmem_setattr,
3854 #ifdef CONFIG_TMPFS_XATTR
3855 .listxattr = shmem_listxattr,
3856 .set_acl = simple_set_acl,
3857 #endif
3858 };
3859
3860 static const struct inode_operations shmem_dir_inode_operations = {
3861 #ifdef CONFIG_TMPFS
3862 .create = shmem_create,
3863 .lookup = simple_lookup,
3864 .link = shmem_link,
3865 .unlink = shmem_unlink,
3866 .symlink = shmem_symlink,
3867 .mkdir = shmem_mkdir,
3868 .rmdir = shmem_rmdir,
3869 .mknod = shmem_mknod,
3870 .rename = shmem_rename2,
3871 .tmpfile = shmem_tmpfile,
3872 #endif
3873 #ifdef CONFIG_TMPFS_XATTR
3874 .listxattr = shmem_listxattr,
3875 #endif
3876 #ifdef CONFIG_TMPFS_POSIX_ACL
3877 .setattr = shmem_setattr,
3878 .set_acl = simple_set_acl,
3879 #endif
3880 };
3881
3882 static const struct inode_operations shmem_special_inode_operations = {
3883 #ifdef CONFIG_TMPFS_XATTR
3884 .listxattr = shmem_listxattr,
3885 #endif
3886 #ifdef CONFIG_TMPFS_POSIX_ACL
3887 .setattr = shmem_setattr,
3888 .set_acl = simple_set_acl,
3889 #endif
3890 };
3891
3892 static const struct super_operations shmem_ops = {
3893 .alloc_inode = shmem_alloc_inode,
3894 .destroy_inode = shmem_destroy_inode,
3895 #ifdef CONFIG_TMPFS
3896 .statfs = shmem_statfs,
3897 .remount_fs = shmem_remount_fs,
3898 .show_options = shmem_show_options,
3899 #endif
3900 .evict_inode = shmem_evict_inode,
3901 .drop_inode = generic_delete_inode,
3902 .put_super = shmem_put_super,
3903 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3904 .nr_cached_objects = shmem_unused_huge_count,
3905 .free_cached_objects = shmem_unused_huge_scan,
3906 #endif
3907 };
3908
3909 static const struct vm_operations_struct shmem_vm_ops = {
3910 .fault = shmem_fault,
3911 .map_pages = filemap_map_pages,
3912 #ifdef CONFIG_NUMA
3913 .set_policy = shmem_set_policy,
3914 .get_policy = shmem_get_policy,
3915 #endif
3916 };
3917
3918 static struct dentry *shmem_mount(struct file_system_type *fs_type,
3919 int flags, const char *dev_name, void *data)
3920 {
3921 return mount_nodev(fs_type, flags, data, shmem_fill_super);
3922 }
3923
3924 static struct file_system_type shmem_fs_type = {
3925 .owner = THIS_MODULE,
3926 .name = "tmpfs",
3927 .mount = shmem_mount,
3928 .kill_sb = kill_litter_super,
3929 .fs_flags = FS_USERNS_MOUNT,
3930 };
3931
3932 int __init shmem_init(void)
3933 {
3934 int error;
3935
3936 /* If rootfs called this, don't re-init */
3937 if (shmem_inode_cachep)
3938 return 0;
3939
3940 error = shmem_init_inodecache();
3941 if (error)
3942 goto out3;
3943
3944 error = register_filesystem(&shmem_fs_type);
3945 if (error) {
3946 pr_err("Could not register tmpfs\n");
3947 goto out2;
3948 }
3949
3950 shm_mnt = kern_mount(&shmem_fs_type);
3951 if (IS_ERR(shm_mnt)) {
3952 error = PTR_ERR(shm_mnt);
3953 pr_err("Could not kern_mount tmpfs\n");
3954 goto out1;
3955 }
3956
3957 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3958 if (has_transparent_hugepage() && shmem_huge < SHMEM_HUGE_DENY)
3959 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3960 else
3961 shmem_huge = 0; /* just in case it was patched */
3962 #endif
3963 return 0;
3964
3965 out1:
3966 unregister_filesystem(&shmem_fs_type);
3967 out2:
3968 shmem_destroy_inodecache();
3969 out3:
3970 shm_mnt = ERR_PTR(error);
3971 return error;
3972 }
3973
3974 #if defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && defined(CONFIG_SYSFS)
3975 static ssize_t shmem_enabled_show(struct kobject *kobj,
3976 struct kobj_attribute *attr, char *buf)
3977 {
3978 int values[] = {
3979 SHMEM_HUGE_ALWAYS,
3980 SHMEM_HUGE_WITHIN_SIZE,
3981 SHMEM_HUGE_ADVISE,
3982 SHMEM_HUGE_NEVER,
3983 SHMEM_HUGE_DENY,
3984 SHMEM_HUGE_FORCE,
3985 };
3986 int i, count;
3987
3988 for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
3989 const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
3990
3991 count += sprintf(buf + count, fmt,
3992 shmem_format_huge(values[i]));
3993 }
3994 buf[count - 1] = '\n';
3995 return count;
3996 }
3997
3998 static ssize_t shmem_enabled_store(struct kobject *kobj,
3999 struct kobj_attribute *attr, const char *buf, size_t count)
4000 {
4001 char tmp[16];
4002 int huge;
4003
4004 if (count + 1 > sizeof(tmp))
4005 return -EINVAL;
4006 memcpy(tmp, buf, count);
4007 tmp[count] = '\0';
4008 if (count && tmp[count - 1] == '\n')
4009 tmp[count - 1] = '\0';
4010
4011 huge = shmem_parse_huge(tmp);
4012 if (huge == -EINVAL)
4013 return -EINVAL;
4014 if (!has_transparent_hugepage() &&
4015 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4016 return -EINVAL;
4017
4018 shmem_huge = huge;
4019 if (shmem_huge < SHMEM_HUGE_DENY)
4020 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4021 return count;
4022 }
4023
4024 struct kobj_attribute shmem_enabled_attr =
4025 __ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
4026 #endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE && CONFIG_SYSFS */
4027
4028 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
4029 bool shmem_huge_enabled(struct vm_area_struct *vma)
4030 {
4031 struct inode *inode = file_inode(vma->vm_file);
4032 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
4033 loff_t i_size;
4034 pgoff_t off;
4035
4036 if (shmem_huge == SHMEM_HUGE_FORCE)
4037 return true;
4038 if (shmem_huge == SHMEM_HUGE_DENY)
4039 return false;
4040 switch (sbinfo->huge) {
4041 case SHMEM_HUGE_NEVER:
4042 return false;
4043 case SHMEM_HUGE_ALWAYS:
4044 return true;
4045 case SHMEM_HUGE_WITHIN_SIZE:
4046 off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
4047 i_size = round_up(i_size_read(inode), PAGE_SIZE);
4048 if (i_size >= HPAGE_PMD_SIZE &&
4049 i_size >> PAGE_SHIFT >= off)
4050 return true;
4051 case SHMEM_HUGE_ADVISE:
4052 /* TODO: implement fadvise() hints */
4053 return (vma->vm_flags & VM_HUGEPAGE);
4054 default:
4055 VM_BUG_ON(1);
4056 return false;
4057 }
4058 }
4059 #endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
4060
4061 #else /* !CONFIG_SHMEM */
4062
4063 /*
4064 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4065 *
4066 * This is intended for small system where the benefits of the full
4067 * shmem code (swap-backed and resource-limited) are outweighed by
4068 * their complexity. On systems without swap this code should be
4069 * effectively equivalent, but much lighter weight.
4070 */
4071
4072 static struct file_system_type shmem_fs_type = {
4073 .name = "tmpfs",
4074 .mount = ramfs_mount,
4075 .kill_sb = kill_litter_super,
4076 .fs_flags = FS_USERNS_MOUNT,
4077 };
4078
4079 int __init shmem_init(void)
4080 {
4081 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4082
4083 shm_mnt = kern_mount(&shmem_fs_type);
4084 BUG_ON(IS_ERR(shm_mnt));
4085
4086 return 0;
4087 }
4088
4089 int shmem_unuse(swp_entry_t swap, struct page *page)
4090 {
4091 return 0;
4092 }
4093
4094 int shmem_lock(struct file *file, int lock, struct user_struct *user)
4095 {
4096 return 0;
4097 }
4098
4099 void shmem_unlock_mapping(struct address_space *mapping)
4100 {
4101 }
4102
4103 #ifdef CONFIG_MMU
4104 unsigned long shmem_get_unmapped_area(struct file *file,
4105 unsigned long addr, unsigned long len,
4106 unsigned long pgoff, unsigned long flags)
4107 {
4108 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4109 }
4110 #endif
4111
4112 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4113 {
4114 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4115 }
4116 EXPORT_SYMBOL_GPL(shmem_truncate_range);
4117
4118 #define shmem_vm_ops generic_file_vm_ops
4119 #define shmem_file_operations ramfs_file_operations
4120 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4121 #define shmem_acct_size(flags, size) 0
4122 #define shmem_unacct_size(flags, size) do {} while (0)
4123
4124 #endif /* CONFIG_SHMEM */
4125
4126 /* common code */
4127
4128 static const struct dentry_operations anon_ops = {
4129 .d_dname = simple_dname
4130 };
4131
4132 static struct file *__shmem_file_setup(const char *name, loff_t size,
4133 unsigned long flags, unsigned int i_flags)
4134 {
4135 struct file *res;
4136 struct inode *inode;
4137 struct path path;
4138 struct super_block *sb;
4139 struct qstr this;
4140
4141 if (IS_ERR(shm_mnt))
4142 return ERR_CAST(shm_mnt);
4143
4144 if (size < 0 || size > MAX_LFS_FILESIZE)
4145 return ERR_PTR(-EINVAL);
4146
4147 if (shmem_acct_size(flags, size))
4148 return ERR_PTR(-ENOMEM);
4149
4150 res = ERR_PTR(-ENOMEM);
4151 this.name = name;
4152 this.len = strlen(name);
4153 this.hash = 0; /* will go */
4154 sb = shm_mnt->mnt_sb;
4155 path.mnt = mntget(shm_mnt);
4156 path.dentry = d_alloc_pseudo(sb, &this);
4157 if (!path.dentry)
4158 goto put_memory;
4159 d_set_d_op(path.dentry, &anon_ops);
4160
4161 res = ERR_PTR(-ENOSPC);
4162 inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
4163 if (!inode)
4164 goto put_memory;
4165
4166 inode->i_flags |= i_flags;
4167 d_instantiate(path.dentry, inode);
4168 inode->i_size = size;
4169 clear_nlink(inode); /* It is unlinked */
4170 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4171 if (IS_ERR(res))
4172 goto put_path;
4173
4174 res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
4175 &shmem_file_operations);
4176 if (IS_ERR(res))
4177 goto put_path;
4178
4179 return res;
4180
4181 put_memory:
4182 shmem_unacct_size(flags, size);
4183 put_path:
4184 path_put(&path);
4185 return res;
4186 }
4187
4188 /**
4189 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4190 * kernel internal. There will be NO LSM permission checks against the
4191 * underlying inode. So users of this interface must do LSM checks at a
4192 * higher layer. The users are the big_key and shm implementations. LSM
4193 * checks are provided at the key or shm level rather than the inode.
4194 * @name: name for dentry (to be seen in /proc/<pid>/maps
4195 * @size: size to be set for the file
4196 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4197 */
4198 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4199 {
4200 return __shmem_file_setup(name, size, flags, S_PRIVATE);
4201 }
4202
4203 /**
4204 * shmem_file_setup - get an unlinked file living in tmpfs
4205 * @name: name for dentry (to be seen in /proc/<pid>/maps
4206 * @size: size to be set for the file
4207 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4208 */
4209 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4210 {
4211 return __shmem_file_setup(name, size, flags, 0);
4212 }
4213 EXPORT_SYMBOL_GPL(shmem_file_setup);
4214
4215 /**
4216 * shmem_zero_setup - setup a shared anonymous mapping
4217 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
4218 */
4219 int shmem_zero_setup(struct vm_area_struct *vma)
4220 {
4221 struct file *file;
4222 loff_t size = vma->vm_end - vma->vm_start;
4223
4224 /*
4225 * Cloning a new file under mmap_sem leads to a lock ordering conflict
4226 * between XFS directory reading and selinux: since this file is only
4227 * accessible to the user through its mapping, use S_PRIVATE flag to
4228 * bypass file security, in the same way as shmem_kernel_file_setup().
4229 */
4230 file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
4231 if (IS_ERR(file))
4232 return PTR_ERR(file);
4233
4234 if (vma->vm_file)
4235 fput(vma->vm_file);
4236 vma->vm_file = file;
4237 vma->vm_ops = &shmem_vm_ops;
4238
4239 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
4240 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
4241 (vma->vm_end & HPAGE_PMD_MASK)) {
4242 khugepaged_enter(vma, vma->vm_flags);
4243 }
4244
4245 return 0;
4246 }
4247
4248 /**
4249 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4250 * @mapping: the page's address_space
4251 * @index: the page index
4252 * @gfp: the page allocator flags to use if allocating
4253 *
4254 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4255 * with any new page allocations done using the specified allocation flags.
4256 * But read_cache_page_gfp() uses the ->readpage() method: which does not
4257 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4258 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4259 *
4260 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4261 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4262 */
4263 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4264 pgoff_t index, gfp_t gfp)
4265 {
4266 #ifdef CONFIG_SHMEM
4267 struct inode *inode = mapping->host;
4268 struct page *page;
4269 int error;
4270
4271 BUG_ON(mapping->a_ops != &shmem_aops);
4272 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4273 gfp, NULL, NULL, NULL);
4274 if (error)
4275 page = ERR_PTR(error);
4276 else
4277 unlock_page(page);
4278 return page;
4279 #else
4280 /*
4281 * The tiny !SHMEM case uses ramfs without swap
4282 */
4283 return read_cache_page_gfp(mapping, index, gfp);
4284 #endif
4285 }
4286 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);