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 static struct vfsmount *shm_mnt;
38
39 #ifdef CONFIG_SHMEM
40 /*
41 * This virtual memory filesystem is heavily based on the ramfs. It
42 * extends ramfs by the ability to use swap and honor resource limits
43 * which makes it a completely usable filesystem.
44 */
45
46 #include <linux/xattr.h>
47 #include <linux/exportfs.h>
48 #include <linux/posix_acl.h>
49 #include <linux/posix_acl_xattr.h>
50 #include <linux/mman.h>
51 #include <linux/string.h>
52 #include <linux/slab.h>
53 #include <linux/backing-dev.h>
54 #include <linux/shmem_fs.h>
55 #include <linux/writeback.h>
56 #include <linux/blkdev.h>
57 #include <linux/pagevec.h>
58 #include <linux/percpu_counter.h>
59 #include <linux/falloc.h>
60 #include <linux/splice.h>
61 #include <linux/security.h>
62 #include <linux/swapops.h>
63 #include <linux/mempolicy.h>
64 #include <linux/namei.h>
65 #include <linux/ctype.h>
66 #include <linux/migrate.h>
67 #include <linux/highmem.h>
68 #include <linux/seq_file.h>
69 #include <linux/magic.h>
70 #include <linux/syscalls.h>
71 #include <linux/fcntl.h>
72 #include <uapi/linux/memfd.h>
73
74 #include <asm/uaccess.h>
75 #include <asm/pgtable.h>
76
77 #include "internal.h"
78
79 #define BLOCKS_PER_PAGE (PAGE_SIZE/512)
80 #define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
81
82 /* Pretend that each entry is of this size in directory's i_size */
83 #define BOGO_DIRENT_SIZE 20
84
85 /* Symlink up to this size is kmalloc'ed instead of using a swappable page */
86 #define SHORT_SYMLINK_LEN 128
87
88 /*
89 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
90 * inode->i_private (with i_mutex making sure that it has only one user at
91 * a time): we would prefer not to enlarge the shmem inode just for that.
92 */
93 struct shmem_falloc {
94 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
95 pgoff_t start; /* start of range currently being fallocated */
96 pgoff_t next; /* the next page offset to be fallocated */
97 pgoff_t nr_falloced; /* how many new pages have been fallocated */
98 pgoff_t nr_unswapped; /* how often writepage refused to swap out */
99 };
100
101 #ifdef CONFIG_TMPFS
102 static unsigned long shmem_default_max_blocks(void)
103 {
104 return totalram_pages / 2;
105 }
106
107 static unsigned long shmem_default_max_inodes(void)
108 {
109 return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
110 }
111 #endif
112
113 static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
114 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
115 struct shmem_inode_info *info, pgoff_t index);
116 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
117 struct page **pagep, enum sgp_type sgp,
118 gfp_t gfp, struct mm_struct *fault_mm, int *fault_type);
119
120 int shmem_getpage(struct inode *inode, pgoff_t index,
121 struct page **pagep, enum sgp_type sgp)
122 {
123 return shmem_getpage_gfp(inode, index, pagep, sgp,
124 mapping_gfp_mask(inode->i_mapping), NULL, NULL);
125 }
126
127 static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
128 {
129 return sb->s_fs_info;
130 }
131
132 /*
133 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
134 * for shared memory and for shared anonymous (/dev/zero) mappings
135 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
136 * consistent with the pre-accounting of private mappings ...
137 */
138 static inline int shmem_acct_size(unsigned long flags, loff_t size)
139 {
140 return (flags & VM_NORESERVE) ?
141 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
142 }
143
144 static inline void shmem_unacct_size(unsigned long flags, loff_t size)
145 {
146 if (!(flags & VM_NORESERVE))
147 vm_unacct_memory(VM_ACCT(size));
148 }
149
150 static inline int shmem_reacct_size(unsigned long flags,
151 loff_t oldsize, loff_t newsize)
152 {
153 if (!(flags & VM_NORESERVE)) {
154 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
155 return security_vm_enough_memory_mm(current->mm,
156 VM_ACCT(newsize) - VM_ACCT(oldsize));
157 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
158 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
159 }
160 return 0;
161 }
162
163 /*
164 * ... whereas tmpfs objects are accounted incrementally as
165 * pages are allocated, in order to allow large sparse files.
166 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
167 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
168 */
169 static inline int shmem_acct_block(unsigned long flags, long pages)
170 {
171 if (!(flags & VM_NORESERVE))
172 return 0;
173
174 return security_vm_enough_memory_mm(current->mm,
175 pages * VM_ACCT(PAGE_SIZE));
176 }
177
178 static inline void shmem_unacct_blocks(unsigned long flags, long pages)
179 {
180 if (flags & VM_NORESERVE)
181 vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
182 }
183
184 static const struct super_operations shmem_ops;
185 static const struct address_space_operations shmem_aops;
186 static const struct file_operations shmem_file_operations;
187 static const struct inode_operations shmem_inode_operations;
188 static const struct inode_operations shmem_dir_inode_operations;
189 static const struct inode_operations shmem_special_inode_operations;
190 static const struct vm_operations_struct shmem_vm_ops;
191 static struct file_system_type shmem_fs_type;
192
193 static LIST_HEAD(shmem_swaplist);
194 static DEFINE_MUTEX(shmem_swaplist_mutex);
195
196 static int shmem_reserve_inode(struct super_block *sb)
197 {
198 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
199 if (sbinfo->max_inodes) {
200 spin_lock(&sbinfo->stat_lock);
201 if (!sbinfo->free_inodes) {
202 spin_unlock(&sbinfo->stat_lock);
203 return -ENOSPC;
204 }
205 sbinfo->free_inodes--;
206 spin_unlock(&sbinfo->stat_lock);
207 }
208 return 0;
209 }
210
211 static void shmem_free_inode(struct super_block *sb)
212 {
213 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
214 if (sbinfo->max_inodes) {
215 spin_lock(&sbinfo->stat_lock);
216 sbinfo->free_inodes++;
217 spin_unlock(&sbinfo->stat_lock);
218 }
219 }
220
221 /**
222 * shmem_recalc_inode - recalculate the block usage of an inode
223 * @inode: inode to recalc
224 *
225 * We have to calculate the free blocks since the mm can drop
226 * undirtied hole pages behind our back.
227 *
228 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
229 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
230 *
231 * It has to be called with the spinlock held.
232 */
233 static void shmem_recalc_inode(struct inode *inode)
234 {
235 struct shmem_inode_info *info = SHMEM_I(inode);
236 long freed;
237
238 freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
239 if (freed > 0) {
240 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
241 if (sbinfo->max_blocks)
242 percpu_counter_add(&sbinfo->used_blocks, -freed);
243 info->alloced -= freed;
244 inode->i_blocks -= freed * BLOCKS_PER_PAGE;
245 shmem_unacct_blocks(info->flags, freed);
246 }
247 }
248
249 bool shmem_charge(struct inode *inode, long pages)
250 {
251 struct shmem_inode_info *info = SHMEM_I(inode);
252 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
253 unsigned long flags;
254
255 if (shmem_acct_block(info->flags, pages))
256 return false;
257 spin_lock_irqsave(&info->lock, flags);
258 info->alloced += pages;
259 inode->i_blocks += pages * BLOCKS_PER_PAGE;
260 shmem_recalc_inode(inode);
261 spin_unlock_irqrestore(&info->lock, flags);
262 inode->i_mapping->nrpages += pages;
263
264 if (!sbinfo->max_blocks)
265 return true;
266 if (percpu_counter_compare(&sbinfo->used_blocks,
267 sbinfo->max_blocks - pages) > 0) {
268 inode->i_mapping->nrpages -= pages;
269 spin_lock_irqsave(&info->lock, flags);
270 info->alloced -= pages;
271 shmem_recalc_inode(inode);
272 spin_unlock_irqrestore(&info->lock, flags);
273 shmem_unacct_blocks(info->flags, pages);
274 return false;
275 }
276 percpu_counter_add(&sbinfo->used_blocks, pages);
277 return true;
278 }
279
280 void shmem_uncharge(struct inode *inode, long pages)
281 {
282 struct shmem_inode_info *info = SHMEM_I(inode);
283 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
284 unsigned long flags;
285
286 spin_lock_irqsave(&info->lock, flags);
287 info->alloced -= pages;
288 inode->i_blocks -= pages * BLOCKS_PER_PAGE;
289 shmem_recalc_inode(inode);
290 spin_unlock_irqrestore(&info->lock, flags);
291
292 if (sbinfo->max_blocks)
293 percpu_counter_sub(&sbinfo->used_blocks, pages);
294 shmem_unacct_blocks(info->flags, pages);
295 }
296
297 /*
298 * Replace item expected in radix tree by a new item, while holding tree lock.
299 */
300 static int shmem_radix_tree_replace(struct address_space *mapping,
301 pgoff_t index, void *expected, void *replacement)
302 {
303 void **pslot;
304 void *item;
305
306 VM_BUG_ON(!expected);
307 VM_BUG_ON(!replacement);
308 pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
309 if (!pslot)
310 return -ENOENT;
311 item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
312 if (item != expected)
313 return -ENOENT;
314 radix_tree_replace_slot(pslot, replacement);
315 return 0;
316 }
317
318 /*
319 * Sometimes, before we decide whether to proceed or to fail, we must check
320 * that an entry was not already brought back from swap by a racing thread.
321 *
322 * Checking page is not enough: by the time a SwapCache page is locked, it
323 * might be reused, and again be SwapCache, using the same swap as before.
324 */
325 static bool shmem_confirm_swap(struct address_space *mapping,
326 pgoff_t index, swp_entry_t swap)
327 {
328 void *item;
329
330 rcu_read_lock();
331 item = radix_tree_lookup(&mapping->page_tree, index);
332 rcu_read_unlock();
333 return item == swp_to_radix_entry(swap);
334 }
335
336 /*
337 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
338 *
339 * SHMEM_HUGE_NEVER:
340 * disables huge pages for the mount;
341 * SHMEM_HUGE_ALWAYS:
342 * enables huge pages for the mount;
343 * SHMEM_HUGE_WITHIN_SIZE:
344 * only allocate huge pages if the page will be fully within i_size,
345 * also respect fadvise()/madvise() hints;
346 * SHMEM_HUGE_ADVISE:
347 * only allocate huge pages if requested with fadvise()/madvise();
348 */
349
350 #define SHMEM_HUGE_NEVER 0
351 #define SHMEM_HUGE_ALWAYS 1
352 #define SHMEM_HUGE_WITHIN_SIZE 2
353 #define SHMEM_HUGE_ADVISE 3
354
355 /*
356 * Special values.
357 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
358 *
359 * SHMEM_HUGE_DENY:
360 * disables huge on shm_mnt and all mounts, for emergency use;
361 * SHMEM_HUGE_FORCE:
362 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
363 *
364 */
365 #define SHMEM_HUGE_DENY (-1)
366 #define SHMEM_HUGE_FORCE (-2)
367
368 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
369 /* ifdef here to avoid bloating shmem.o when not necessary */
370
371 int shmem_huge __read_mostly;
372
373 static int shmem_parse_huge(const char *str)
374 {
375 if (!strcmp(str, "never"))
376 return SHMEM_HUGE_NEVER;
377 if (!strcmp(str, "always"))
378 return SHMEM_HUGE_ALWAYS;
379 if (!strcmp(str, "within_size"))
380 return SHMEM_HUGE_WITHIN_SIZE;
381 if (!strcmp(str, "advise"))
382 return SHMEM_HUGE_ADVISE;
383 if (!strcmp(str, "deny"))
384 return SHMEM_HUGE_DENY;
385 if (!strcmp(str, "force"))
386 return SHMEM_HUGE_FORCE;
387 return -EINVAL;
388 }
389
390 static const char *shmem_format_huge(int huge)
391 {
392 switch (huge) {
393 case SHMEM_HUGE_NEVER:
394 return "never";
395 case SHMEM_HUGE_ALWAYS:
396 return "always";
397 case SHMEM_HUGE_WITHIN_SIZE:
398 return "within_size";
399 case SHMEM_HUGE_ADVISE:
400 return "advise";
401 case SHMEM_HUGE_DENY:
402 return "deny";
403 case SHMEM_HUGE_FORCE:
404 return "force";
405 default:
406 VM_BUG_ON(1);
407 return "bad_val";
408 }
409 }
410
411 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
412 struct shrink_control *sc, unsigned long nr_to_split)
413 {
414 LIST_HEAD(list), *pos, *next;
415 struct inode *inode;
416 struct shmem_inode_info *info;
417 struct page *page;
418 unsigned long batch = sc ? sc->nr_to_scan : 128;
419 int removed = 0, split = 0;
420
421 if (list_empty(&sbinfo->shrinklist))
422 return SHRINK_STOP;
423
424 spin_lock(&sbinfo->shrinklist_lock);
425 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
426 info = list_entry(pos, struct shmem_inode_info, shrinklist);
427
428 /* pin the inode */
429 inode = igrab(&info->vfs_inode);
430
431 /* inode is about to be evicted */
432 if (!inode) {
433 list_del_init(&info->shrinklist);
434 removed++;
435 goto next;
436 }
437
438 /* Check if there's anything to gain */
439 if (round_up(inode->i_size, PAGE_SIZE) ==
440 round_up(inode->i_size, HPAGE_PMD_SIZE)) {
441 list_del_init(&info->shrinklist);
442 removed++;
443 iput(inode);
444 goto next;
445 }
446
447 list_move(&info->shrinklist, &list);
448 next:
449 if (!--batch)
450 break;
451 }
452 spin_unlock(&sbinfo->shrinklist_lock);
453
454 list_for_each_safe(pos, next, &list) {
455 int ret;
456
457 info = list_entry(pos, struct shmem_inode_info, shrinklist);
458 inode = &info->vfs_inode;
459
460 if (nr_to_split && split >= nr_to_split) {
461 iput(inode);
462 continue;
463 }
464
465 page = find_lock_page(inode->i_mapping,
466 (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
467 if (!page)
468 goto drop;
469
470 if (!PageTransHuge(page)) {
471 unlock_page(page);
472 put_page(page);
473 goto drop;
474 }
475
476 ret = split_huge_page(page);
477 unlock_page(page);
478 put_page(page);
479
480 if (ret) {
481 /* split failed: leave it on the list */
482 iput(inode);
483 continue;
484 }
485
486 split++;
487 drop:
488 list_del_init(&info->shrinklist);
489 removed++;
490 iput(inode);
491 }
492
493 spin_lock(&sbinfo->shrinklist_lock);
494 list_splice_tail(&list, &sbinfo->shrinklist);
495 sbinfo->shrinklist_len -= removed;
496 spin_unlock(&sbinfo->shrinklist_lock);
497
498 return split;
499 }
500
501 static long shmem_unused_huge_scan(struct super_block *sb,
502 struct shrink_control *sc)
503 {
504 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
505
506 if (!READ_ONCE(sbinfo->shrinklist_len))
507 return SHRINK_STOP;
508
509 return shmem_unused_huge_shrink(sbinfo, sc, 0);
510 }
511
512 static long shmem_unused_huge_count(struct super_block *sb,
513 struct shrink_control *sc)
514 {
515 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
516 return READ_ONCE(sbinfo->shrinklist_len);
517 }
518 #else /* !CONFIG_TRANSPARENT_HUGE_PAGECACHE */
519
520 #define shmem_huge SHMEM_HUGE_DENY
521
522 static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
523 struct shrink_control *sc, unsigned long nr_to_split)
524 {
525 return 0;
526 }
527 #endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
528
529 /*
530 * Like add_to_page_cache_locked, but error if expected item has gone.
531 */
532 static int shmem_add_to_page_cache(struct page *page,
533 struct address_space *mapping,
534 pgoff_t index, void *expected)
535 {
536 int error, nr = hpage_nr_pages(page);
537
538 VM_BUG_ON_PAGE(PageTail(page), page);
539 VM_BUG_ON_PAGE(index != round_down(index, nr), page);
540 VM_BUG_ON_PAGE(!PageLocked(page), page);
541 VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
542 VM_BUG_ON(expected && PageTransHuge(page));
543
544 page_ref_add(page, nr);
545 page->mapping = mapping;
546 page->index = index;
547
548 spin_lock_irq(&mapping->tree_lock);
549 if (PageTransHuge(page)) {
550 void __rcu **results;
551 pgoff_t idx;
552 int i;
553
554 error = 0;
555 if (radix_tree_gang_lookup_slot(&mapping->page_tree,
556 &results, &idx, index, 1) &&
557 idx < index + HPAGE_PMD_NR) {
558 error = -EEXIST;
559 }
560
561 if (!error) {
562 for (i = 0; i < HPAGE_PMD_NR; i++) {
563 error = radix_tree_insert(&mapping->page_tree,
564 index + i, page + i);
565 VM_BUG_ON(error);
566 }
567 count_vm_event(THP_FILE_ALLOC);
568 }
569 } else if (!expected) {
570 error = radix_tree_insert(&mapping->page_tree, index, page);
571 } else {
572 error = shmem_radix_tree_replace(mapping, index, expected,
573 page);
574 }
575
576 if (!error) {
577 mapping->nrpages += nr;
578 if (PageTransHuge(page))
579 __inc_node_page_state(page, NR_SHMEM_THPS);
580 __mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
581 __mod_node_page_state(page_pgdat(page), NR_SHMEM, nr);
582 spin_unlock_irq(&mapping->tree_lock);
583 } else {
584 page->mapping = NULL;
585 spin_unlock_irq(&mapping->tree_lock);
586 page_ref_sub(page, nr);
587 }
588 return error;
589 }
590
591 /*
592 * Like delete_from_page_cache, but substitutes swap for page.
593 */
594 static void shmem_delete_from_page_cache(struct page *page, void *radswap)
595 {
596 struct address_space *mapping = page->mapping;
597 int error;
598
599 VM_BUG_ON_PAGE(PageCompound(page), page);
600
601 spin_lock_irq(&mapping->tree_lock);
602 error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
603 page->mapping = NULL;
604 mapping->nrpages--;
605 __dec_node_page_state(page, NR_FILE_PAGES);
606 __dec_node_page_state(page, NR_SHMEM);
607 spin_unlock_irq(&mapping->tree_lock);
608 put_page(page);
609 BUG_ON(error);
610 }
611
612 /*
613 * Remove swap entry from radix tree, free the swap and its page cache.
614 */
615 static int shmem_free_swap(struct address_space *mapping,
616 pgoff_t index, void *radswap)
617 {
618 void *old;
619
620 spin_lock_irq(&mapping->tree_lock);
621 old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
622 spin_unlock_irq(&mapping->tree_lock);
623 if (old != radswap)
624 return -ENOENT;
625 free_swap_and_cache(radix_to_swp_entry(radswap));
626 return 0;
627 }
628
629 /*
630 * Determine (in bytes) how many of the shmem object's pages mapped by the
631 * given offsets are swapped out.
632 *
633 * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU,
634 * as long as the inode doesn't go away and racy results are not a problem.
635 */
636 unsigned long shmem_partial_swap_usage(struct address_space *mapping,
637 pgoff_t start, pgoff_t end)
638 {
639 struct radix_tree_iter iter;
640 void **slot;
641 struct page *page;
642 unsigned long swapped = 0;
643
644 rcu_read_lock();
645
646 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
647 if (iter.index >= end)
648 break;
649
650 page = radix_tree_deref_slot(slot);
651
652 if (radix_tree_deref_retry(page)) {
653 slot = radix_tree_iter_retry(&iter);
654 continue;
655 }
656
657 if (radix_tree_exceptional_entry(page))
658 swapped++;
659
660 if (need_resched()) {
661 cond_resched_rcu();
662 slot = radix_tree_iter_next(&iter);
663 }
664 }
665
666 rcu_read_unlock();
667
668 return swapped << PAGE_SHIFT;
669 }
670
671 /*
672 * Determine (in bytes) how many of the shmem object's pages mapped by the
673 * given vma is swapped out.
674 *
675 * This is safe to call without i_mutex or mapping->tree_lock thanks to RCU,
676 * as long as the inode doesn't go away and racy results are not a problem.
677 */
678 unsigned long shmem_swap_usage(struct vm_area_struct *vma)
679 {
680 struct inode *inode = file_inode(vma->vm_file);
681 struct shmem_inode_info *info = SHMEM_I(inode);
682 struct address_space *mapping = inode->i_mapping;
683 unsigned long swapped;
684
685 /* Be careful as we don't hold info->lock */
686 swapped = READ_ONCE(info->swapped);
687
688 /*
689 * The easier cases are when the shmem object has nothing in swap, or
690 * the vma maps it whole. Then we can simply use the stats that we
691 * already track.
692 */
693 if (!swapped)
694 return 0;
695
696 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
697 return swapped << PAGE_SHIFT;
698
699 /* Here comes the more involved part */
700 return shmem_partial_swap_usage(mapping,
701 linear_page_index(vma, vma->vm_start),
702 linear_page_index(vma, vma->vm_end));
703 }
704
705 /*
706 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
707 */
708 void shmem_unlock_mapping(struct address_space *mapping)
709 {
710 struct pagevec pvec;
711 pgoff_t indices[PAGEVEC_SIZE];
712 pgoff_t index = 0;
713
714 pagevec_init(&pvec, 0);
715 /*
716 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
717 */
718 while (!mapping_unevictable(mapping)) {
719 /*
720 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
721 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
722 */
723 pvec.nr = find_get_entries(mapping, index,
724 PAGEVEC_SIZE, pvec.pages, indices);
725 if (!pvec.nr)
726 break;
727 index = indices[pvec.nr - 1] + 1;
728 pagevec_remove_exceptionals(&pvec);
729 check_move_unevictable_pages(pvec.pages, pvec.nr);
730 pagevec_release(&pvec);
731 cond_resched();
732 }
733 }
734
735 /*
736 * Remove range of pages and swap entries from radix tree, and free them.
737 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
738 */
739 static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
740 bool unfalloc)
741 {
742 struct address_space *mapping = inode->i_mapping;
743 struct shmem_inode_info *info = SHMEM_I(inode);
744 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
745 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
746 unsigned int partial_start = lstart & (PAGE_SIZE - 1);
747 unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1);
748 struct pagevec pvec;
749 pgoff_t indices[PAGEVEC_SIZE];
750 long nr_swaps_freed = 0;
751 pgoff_t index;
752 int i;
753
754 if (lend == -1)
755 end = -1; /* unsigned, so actually very big */
756
757 pagevec_init(&pvec, 0);
758 index = start;
759 while (index < end) {
760 pvec.nr = find_get_entries(mapping, index,
761 min(end - index, (pgoff_t)PAGEVEC_SIZE),
762 pvec.pages, indices);
763 if (!pvec.nr)
764 break;
765 for (i = 0; i < pagevec_count(&pvec); i++) {
766 struct page *page = pvec.pages[i];
767
768 index = indices[i];
769 if (index >= end)
770 break;
771
772 if (radix_tree_exceptional_entry(page)) {
773 if (unfalloc)
774 continue;
775 nr_swaps_freed += !shmem_free_swap(mapping,
776 index, page);
777 continue;
778 }
779
780 VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
781
782 if (!trylock_page(page))
783 continue;
784
785 if (PageTransTail(page)) {
786 /* Middle of THP: zero out the page */
787 clear_highpage(page);
788 unlock_page(page);
789 continue;
790 } else if (PageTransHuge(page)) {
791 if (index == round_down(end, HPAGE_PMD_NR)) {
792 /*
793 * Range ends in the middle of THP:
794 * zero out the page
795 */
796 clear_highpage(page);
797 unlock_page(page);
798 continue;
799 }
800 index += HPAGE_PMD_NR - 1;
801 i += HPAGE_PMD_NR - 1;
802 }
803
804 if (!unfalloc || !PageUptodate(page)) {
805 VM_BUG_ON_PAGE(PageTail(page), page);
806 if (page_mapping(page) == mapping) {
807 VM_BUG_ON_PAGE(PageWriteback(page), page);
808 truncate_inode_page(mapping, page);
809 }
810 }
811 unlock_page(page);
812 }
813 pagevec_remove_exceptionals(&pvec);
814 pagevec_release(&pvec);
815 cond_resched();
816 index++;
817 }
818
819 if (partial_start) {
820 struct page *page = NULL;
821 shmem_getpage(inode, start - 1, &page, SGP_READ);
822 if (page) {
823 unsigned int top = PAGE_SIZE;
824 if (start > end) {
825 top = partial_end;
826 partial_end = 0;
827 }
828 zero_user_segment(page, partial_start, top);
829 set_page_dirty(page);
830 unlock_page(page);
831 put_page(page);
832 }
833 }
834 if (partial_end) {
835 struct page *page = NULL;
836 shmem_getpage(inode, end, &page, SGP_READ);
837 if (page) {
838 zero_user_segment(page, 0, partial_end);
839 set_page_dirty(page);
840 unlock_page(page);
841 put_page(page);
842 }
843 }
844 if (start >= end)
845 return;
846
847 index = start;
848 while (index < end) {
849 cond_resched();
850
851 pvec.nr = find_get_entries(mapping, index,
852 min(end - index, (pgoff_t)PAGEVEC_SIZE),
853 pvec.pages, indices);
854 if (!pvec.nr) {
855 /* If all gone or hole-punch or unfalloc, we're done */
856 if (index == start || end != -1)
857 break;
858 /* But if truncating, restart to make sure all gone */
859 index = start;
860 continue;
861 }
862 for (i = 0; i < pagevec_count(&pvec); i++) {
863 struct page *page = pvec.pages[i];
864
865 index = indices[i];
866 if (index >= end)
867 break;
868
869 if (radix_tree_exceptional_entry(page)) {
870 if (unfalloc)
871 continue;
872 if (shmem_free_swap(mapping, index, page)) {
873 /* Swap was replaced by page: retry */
874 index--;
875 break;
876 }
877 nr_swaps_freed++;
878 continue;
879 }
880
881 lock_page(page);
882
883 if (PageTransTail(page)) {
884 /* Middle of THP: zero out the page */
885 clear_highpage(page);
886 unlock_page(page);
887 /*
888 * Partial thp truncate due 'start' in middle
889 * of THP: don't need to look on these pages
890 * again on !pvec.nr restart.
891 */
892 if (index != round_down(end, HPAGE_PMD_NR))
893 start++;
894 continue;
895 } else if (PageTransHuge(page)) {
896 if (index == round_down(end, HPAGE_PMD_NR)) {
897 /*
898 * Range ends in the middle of THP:
899 * zero out the page
900 */
901 clear_highpage(page);
902 unlock_page(page);
903 continue;
904 }
905 index += HPAGE_PMD_NR - 1;
906 i += HPAGE_PMD_NR - 1;
907 }
908
909 if (!unfalloc || !PageUptodate(page)) {
910 VM_BUG_ON_PAGE(PageTail(page), page);
911 if (page_mapping(page) == mapping) {
912 VM_BUG_ON_PAGE(PageWriteback(page), page);
913 truncate_inode_page(mapping, page);
914 } else {
915 /* Page was replaced by swap: retry */
916 unlock_page(page);
917 index--;
918 break;
919 }
920 }
921 unlock_page(page);
922 }
923 pagevec_remove_exceptionals(&pvec);
924 pagevec_release(&pvec);
925 index++;
926 }
927
928 spin_lock_irq(&info->lock);
929 info->swapped -= nr_swaps_freed;
930 shmem_recalc_inode(inode);
931 spin_unlock_irq(&info->lock);
932 }
933
934 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
935 {
936 shmem_undo_range(inode, lstart, lend, false);
937 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
938 }
939 EXPORT_SYMBOL_GPL(shmem_truncate_range);
940
941 static int shmem_getattr(struct vfsmount *mnt, struct dentry *dentry,
942 struct kstat *stat)
943 {
944 struct inode *inode = dentry->d_inode;
945 struct shmem_inode_info *info = SHMEM_I(inode);
946
947 if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
948 spin_lock_irq(&info->lock);
949 shmem_recalc_inode(inode);
950 spin_unlock_irq(&info->lock);
951 }
952 generic_fillattr(inode, stat);
953 return 0;
954 }
955
956 static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
957 {
958 struct inode *inode = d_inode(dentry);
959 struct shmem_inode_info *info = SHMEM_I(inode);
960 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
961 int error;
962
963 error = inode_change_ok(inode, attr);
964 if (error)
965 return error;
966
967 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
968 loff_t oldsize = inode->i_size;
969 loff_t newsize = attr->ia_size;
970
971 /* protected by i_mutex */
972 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
973 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
974 return -EPERM;
975
976 if (newsize != oldsize) {
977 error = shmem_reacct_size(SHMEM_I(inode)->flags,
978 oldsize, newsize);
979 if (error)
980 return error;
981 i_size_write(inode, newsize);
982 inode->i_ctime = inode->i_mtime = CURRENT_TIME;
983 }
984 if (newsize <= oldsize) {
985 loff_t holebegin = round_up(newsize, PAGE_SIZE);
986 if (oldsize > holebegin)
987 unmap_mapping_range(inode->i_mapping,
988 holebegin, 0, 1);
989 if (info->alloced)
990 shmem_truncate_range(inode,
991 newsize, (loff_t)-1);
992 /* unmap again to remove racily COWed private pages */
993 if (oldsize > holebegin)
994 unmap_mapping_range(inode->i_mapping,
995 holebegin, 0, 1);
996
997 /*
998 * Part of the huge page can be beyond i_size: subject
999 * to shrink under memory pressure.
1000 */
1001 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
1002 spin_lock(&sbinfo->shrinklist_lock);
1003 if (list_empty(&info->shrinklist)) {
1004 list_add_tail(&info->shrinklist,
1005 &sbinfo->shrinklist);
1006 sbinfo->shrinklist_len++;
1007 }
1008 spin_unlock(&sbinfo->shrinklist_lock);
1009 }
1010 }
1011 }
1012
1013 setattr_copy(inode, attr);
1014 if (attr->ia_valid & ATTR_MODE)
1015 error = posix_acl_chmod(inode, inode->i_mode);
1016 return error;
1017 }
1018
1019 static void shmem_evict_inode(struct inode *inode)
1020 {
1021 struct shmem_inode_info *info = SHMEM_I(inode);
1022 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1023
1024 if (inode->i_mapping->a_ops == &shmem_aops) {
1025 shmem_unacct_size(info->flags, inode->i_size);
1026 inode->i_size = 0;
1027 shmem_truncate_range(inode, 0, (loff_t)-1);
1028 if (!list_empty(&info->shrinklist)) {
1029 spin_lock(&sbinfo->shrinklist_lock);
1030 if (!list_empty(&info->shrinklist)) {
1031 list_del_init(&info->shrinklist);
1032 sbinfo->shrinklist_len--;
1033 }
1034 spin_unlock(&sbinfo->shrinklist_lock);
1035 }
1036 if (!list_empty(&info->swaplist)) {
1037 mutex_lock(&shmem_swaplist_mutex);
1038 list_del_init(&info->swaplist);
1039 mutex_unlock(&shmem_swaplist_mutex);
1040 }
1041 }
1042
1043 simple_xattrs_free(&info->xattrs);
1044 WARN_ON(inode->i_blocks);
1045 shmem_free_inode(inode->i_sb);
1046 clear_inode(inode);
1047 }
1048
1049 /*
1050 * If swap found in inode, free it and move page from swapcache to filecache.
1051 */
1052 static int shmem_unuse_inode(struct shmem_inode_info *info,
1053 swp_entry_t swap, struct page **pagep)
1054 {
1055 struct address_space *mapping = info->vfs_inode.i_mapping;
1056 void *radswap;
1057 pgoff_t index;
1058 gfp_t gfp;
1059 int error = 0;
1060
1061 radswap = swp_to_radix_entry(swap);
1062 index = radix_tree_locate_item(&mapping->page_tree, radswap);
1063 if (index == -1)
1064 return -EAGAIN; /* tell shmem_unuse we found nothing */
1065
1066 /*
1067 * Move _head_ to start search for next from here.
1068 * But be careful: shmem_evict_inode checks list_empty without taking
1069 * mutex, and there's an instant in list_move_tail when info->swaplist
1070 * would appear empty, if it were the only one on shmem_swaplist.
1071 */
1072 if (shmem_swaplist.next != &info->swaplist)
1073 list_move_tail(&shmem_swaplist, &info->swaplist);
1074
1075 gfp = mapping_gfp_mask(mapping);
1076 if (shmem_should_replace_page(*pagep, gfp)) {
1077 mutex_unlock(&shmem_swaplist_mutex);
1078 error = shmem_replace_page(pagep, gfp, info, index);
1079 mutex_lock(&shmem_swaplist_mutex);
1080 /*
1081 * We needed to drop mutex to make that restrictive page
1082 * allocation, but the inode might have been freed while we
1083 * dropped it: although a racing shmem_evict_inode() cannot
1084 * complete without emptying the radix_tree, our page lock
1085 * on this swapcache page is not enough to prevent that -
1086 * free_swap_and_cache() of our swap entry will only
1087 * trylock_page(), removing swap from radix_tree whatever.
1088 *
1089 * We must not proceed to shmem_add_to_page_cache() if the
1090 * inode has been freed, but of course we cannot rely on
1091 * inode or mapping or info to check that. However, we can
1092 * safely check if our swap entry is still in use (and here
1093 * it can't have got reused for another page): if it's still
1094 * in use, then the inode cannot have been freed yet, and we
1095 * can safely proceed (if it's no longer in use, that tells
1096 * nothing about the inode, but we don't need to unuse swap).
1097 */
1098 if (!page_swapcount(*pagep))
1099 error = -ENOENT;
1100 }
1101
1102 /*
1103 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
1104 * but also to hold up shmem_evict_inode(): so inode cannot be freed
1105 * beneath us (pagelock doesn't help until the page is in pagecache).
1106 */
1107 if (!error)
1108 error = shmem_add_to_page_cache(*pagep, mapping, index,
1109 radswap);
1110 if (error != -ENOMEM) {
1111 /*
1112 * Truncation and eviction use free_swap_and_cache(), which
1113 * only does trylock page: if we raced, best clean up here.
1114 */
1115 delete_from_swap_cache(*pagep);
1116 set_page_dirty(*pagep);
1117 if (!error) {
1118 spin_lock_irq(&info->lock);
1119 info->swapped--;
1120 spin_unlock_irq(&info->lock);
1121 swap_free(swap);
1122 }
1123 }
1124 return error;
1125 }
1126
1127 /*
1128 * Search through swapped inodes to find and replace swap by page.
1129 */
1130 int shmem_unuse(swp_entry_t swap, struct page *page)
1131 {
1132 struct list_head *this, *next;
1133 struct shmem_inode_info *info;
1134 struct mem_cgroup *memcg;
1135 int error = 0;
1136
1137 /*
1138 * There's a faint possibility that swap page was replaced before
1139 * caller locked it: caller will come back later with the right page.
1140 */
1141 if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
1142 goto out;
1143
1144 /*
1145 * Charge page using GFP_KERNEL while we can wait, before taking
1146 * the shmem_swaplist_mutex which might hold up shmem_writepage().
1147 * Charged back to the user (not to caller) when swap account is used.
1148 */
1149 error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg,
1150 false);
1151 if (error)
1152 goto out;
1153 /* No radix_tree_preload: swap entry keeps a place for page in tree */
1154 error = -EAGAIN;
1155
1156 mutex_lock(&shmem_swaplist_mutex);
1157 list_for_each_safe(this, next, &shmem_swaplist) {
1158 info = list_entry(this, struct shmem_inode_info, swaplist);
1159 if (info->swapped)
1160 error = shmem_unuse_inode(info, swap, &page);
1161 else
1162 list_del_init(&info->swaplist);
1163 cond_resched();
1164 if (error != -EAGAIN)
1165 break;
1166 /* found nothing in this: move on to search the next */
1167 }
1168 mutex_unlock(&shmem_swaplist_mutex);
1169
1170 if (error) {
1171 if (error != -ENOMEM)
1172 error = 0;
1173 mem_cgroup_cancel_charge(page, memcg, false);
1174 } else
1175 mem_cgroup_commit_charge(page, memcg, true, false);
1176 out:
1177 unlock_page(page);
1178 put_page(page);
1179 return error;
1180 }
1181
1182 /*
1183 * Move the page from the page cache to the swap cache.
1184 */
1185 static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1186 {
1187 struct shmem_inode_info *info;
1188 struct address_space *mapping;
1189 struct inode *inode;
1190 swp_entry_t swap;
1191 pgoff_t index;
1192
1193 VM_BUG_ON_PAGE(PageCompound(page), page);
1194 BUG_ON(!PageLocked(page));
1195 mapping = page->mapping;
1196 index = page->index;
1197 inode = mapping->host;
1198 info = SHMEM_I(inode);
1199 if (info->flags & VM_LOCKED)
1200 goto redirty;
1201 if (!total_swap_pages)
1202 goto redirty;
1203
1204 /*
1205 * Our capabilities prevent regular writeback or sync from ever calling
1206 * shmem_writepage; but a stacking filesystem might use ->writepage of
1207 * its underlying filesystem, in which case tmpfs should write out to
1208 * swap only in response to memory pressure, and not for the writeback
1209 * threads or sync.
1210 */
1211 if (!wbc->for_reclaim) {
1212 WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
1213 goto redirty;
1214 }
1215
1216 /*
1217 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1218 * value into swapfile.c, the only way we can correctly account for a
1219 * fallocated page arriving here is now to initialize it and write it.
1220 *
1221 * That's okay for a page already fallocated earlier, but if we have
1222 * not yet completed the fallocation, then (a) we want to keep track
1223 * of this page in case we have to undo it, and (b) it may not be a
1224 * good idea to continue anyway, once we're pushing into swap. So
1225 * reactivate the page, and let shmem_fallocate() quit when too many.
1226 */
1227 if (!PageUptodate(page)) {
1228 if (inode->i_private) {
1229 struct shmem_falloc *shmem_falloc;
1230 spin_lock(&inode->i_lock);
1231 shmem_falloc = inode->i_private;
1232 if (shmem_falloc &&
1233 !shmem_falloc->waitq &&
1234 index >= shmem_falloc->start &&
1235 index < shmem_falloc->next)
1236 shmem_falloc->nr_unswapped++;
1237 else
1238 shmem_falloc = NULL;
1239 spin_unlock(&inode->i_lock);
1240 if (shmem_falloc)
1241 goto redirty;
1242 }
1243 clear_highpage(page);
1244 flush_dcache_page(page);
1245 SetPageUptodate(page);
1246 }
1247
1248 swap = get_swap_page();
1249 if (!swap.val)
1250 goto redirty;
1251
1252 if (mem_cgroup_try_charge_swap(page, swap))
1253 goto free_swap;
1254
1255 /*
1256 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1257 * if it's not already there. Do it now before the page is
1258 * moved to swap cache, when its pagelock no longer protects
1259 * the inode from eviction. But don't unlock the mutex until
1260 * we've incremented swapped, because shmem_unuse_inode() will
1261 * prune a !swapped inode from the swaplist under this mutex.
1262 */
1263 mutex_lock(&shmem_swaplist_mutex);
1264 if (list_empty(&info->swaplist))
1265 list_add_tail(&info->swaplist, &shmem_swaplist);
1266
1267 if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1268 spin_lock_irq(&info->lock);
1269 shmem_recalc_inode(inode);
1270 info->swapped++;
1271 spin_unlock_irq(&info->lock);
1272
1273 swap_shmem_alloc(swap);
1274 shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1275
1276 mutex_unlock(&shmem_swaplist_mutex);
1277 BUG_ON(page_mapped(page));
1278 swap_writepage(page, wbc);
1279 return 0;
1280 }
1281
1282 mutex_unlock(&shmem_swaplist_mutex);
1283 free_swap:
1284 swapcache_free(swap);
1285 redirty:
1286 set_page_dirty(page);
1287 if (wbc->for_reclaim)
1288 return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
1289 unlock_page(page);
1290 return 0;
1291 }
1292
1293 #if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1294 static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1295 {
1296 char buffer[64];
1297
1298 if (!mpol || mpol->mode == MPOL_DEFAULT)
1299 return; /* show nothing */
1300
1301 mpol_to_str(buffer, sizeof(buffer), mpol);
1302
1303 seq_printf(seq, ",mpol=%s", buffer);
1304 }
1305
1306 static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1307 {
1308 struct mempolicy *mpol = NULL;
1309 if (sbinfo->mpol) {
1310 spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1311 mpol = sbinfo->mpol;
1312 mpol_get(mpol);
1313 spin_unlock(&sbinfo->stat_lock);
1314 }
1315 return mpol;
1316 }
1317 #else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1318 static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1319 {
1320 }
1321 static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1322 {
1323 return NULL;
1324 }
1325 #endif /* CONFIG_NUMA && CONFIG_TMPFS */
1326 #ifndef CONFIG_NUMA
1327 #define vm_policy vm_private_data
1328 #endif
1329
1330 static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1331 struct shmem_inode_info *info, pgoff_t index)
1332 {
1333 /* Create a pseudo vma that just contains the policy */
1334 vma->vm_start = 0;
1335 /* Bias interleave by inode number to distribute better across nodes */
1336 vma->vm_pgoff = index + info->vfs_inode.i_ino;
1337 vma->vm_ops = NULL;
1338 vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
1339 }
1340
1341 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
1342 {
1343 /* Drop reference taken by mpol_shared_policy_lookup() */
1344 mpol_cond_put(vma->vm_policy);
1345 }
1346
1347 static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1348 struct shmem_inode_info *info, pgoff_t index)
1349 {
1350 struct vm_area_struct pvma;
1351 struct page *page;
1352
1353 shmem_pseudo_vma_init(&pvma, info, index);
1354 page = swapin_readahead(swap, gfp, &pvma, 0);
1355 shmem_pseudo_vma_destroy(&pvma);
1356
1357 return page;
1358 }
1359
1360 static struct page *shmem_alloc_hugepage(gfp_t gfp,
1361 struct shmem_inode_info *info, pgoff_t index)
1362 {
1363 struct vm_area_struct pvma;
1364 struct inode *inode = &info->vfs_inode;
1365 struct address_space *mapping = inode->i_mapping;
1366 pgoff_t idx, hindex;
1367 void __rcu **results;
1368 struct page *page;
1369
1370 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1371 return NULL;
1372
1373 hindex = round_down(index, HPAGE_PMD_NR);
1374 rcu_read_lock();
1375 if (radix_tree_gang_lookup_slot(&mapping->page_tree, &results, &idx,
1376 hindex, 1) && idx < hindex + HPAGE_PMD_NR) {
1377 rcu_read_unlock();
1378 return NULL;
1379 }
1380 rcu_read_unlock();
1381
1382 shmem_pseudo_vma_init(&pvma, info, hindex);
1383 page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
1384 HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), true);
1385 shmem_pseudo_vma_destroy(&pvma);
1386 if (page)
1387 prep_transhuge_page(page);
1388 return page;
1389 }
1390
1391 static struct page *shmem_alloc_page(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 = alloc_page_vma(gfp, &pvma, 0);
1399 shmem_pseudo_vma_destroy(&pvma);
1400
1401 return page;
1402 }
1403
1404 static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
1405 struct shmem_inode_info *info, struct shmem_sb_info *sbinfo,
1406 pgoff_t index, bool huge)
1407 {
1408 struct page *page;
1409 int nr;
1410 int err = -ENOSPC;
1411
1412 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1413 huge = false;
1414 nr = huge ? HPAGE_PMD_NR : 1;
1415
1416 if (shmem_acct_block(info->flags, nr))
1417 goto failed;
1418 if (sbinfo->max_blocks) {
1419 if (percpu_counter_compare(&sbinfo->used_blocks,
1420 sbinfo->max_blocks - nr) > 0)
1421 goto unacct;
1422 percpu_counter_add(&sbinfo->used_blocks, nr);
1423 }
1424
1425 if (huge)
1426 page = shmem_alloc_hugepage(gfp, info, index);
1427 else
1428 page = shmem_alloc_page(gfp, info, index);
1429 if (page) {
1430 __SetPageLocked(page);
1431 __SetPageSwapBacked(page);
1432 return page;
1433 }
1434
1435 err = -ENOMEM;
1436 if (sbinfo->max_blocks)
1437 percpu_counter_add(&sbinfo->used_blocks, -nr);
1438 unacct:
1439 shmem_unacct_blocks(info->flags, nr);
1440 failed:
1441 return ERR_PTR(err);
1442 }
1443
1444 /*
1445 * When a page is moved from swapcache to shmem filecache (either by the
1446 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1447 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1448 * ignorance of the mapping it belongs to. If that mapping has special
1449 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1450 * we may need to copy to a suitable page before moving to filecache.
1451 *
1452 * In a future release, this may well be extended to respect cpuset and
1453 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1454 * but for now it is a simple matter of zone.
1455 */
1456 static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
1457 {
1458 return page_zonenum(page) > gfp_zone(gfp);
1459 }
1460
1461 static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1462 struct shmem_inode_info *info, pgoff_t index)
1463 {
1464 struct page *oldpage, *newpage;
1465 struct address_space *swap_mapping;
1466 pgoff_t swap_index;
1467 int error;
1468
1469 oldpage = *pagep;
1470 swap_index = page_private(oldpage);
1471 swap_mapping = page_mapping(oldpage);
1472
1473 /*
1474 * We have arrived here because our zones are constrained, so don't
1475 * limit chance of success by further cpuset and node constraints.
1476 */
1477 gfp &= ~GFP_CONSTRAINT_MASK;
1478 newpage = shmem_alloc_page(gfp, info, index);
1479 if (!newpage)
1480 return -ENOMEM;
1481
1482 get_page(newpage);
1483 copy_highpage(newpage, oldpage);
1484 flush_dcache_page(newpage);
1485
1486 __SetPageLocked(newpage);
1487 __SetPageSwapBacked(newpage);
1488 SetPageUptodate(newpage);
1489 set_page_private(newpage, swap_index);
1490 SetPageSwapCache(newpage);
1491
1492 /*
1493 * Our caller will very soon move newpage out of swapcache, but it's
1494 * a nice clean interface for us to replace oldpage by newpage there.
1495 */
1496 spin_lock_irq(&swap_mapping->tree_lock);
1497 error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
1498 newpage);
1499 if (!error) {
1500 __inc_node_page_state(newpage, NR_FILE_PAGES);
1501 __dec_node_page_state(oldpage, NR_FILE_PAGES);
1502 }
1503 spin_unlock_irq(&swap_mapping->tree_lock);
1504
1505 if (unlikely(error)) {
1506 /*
1507 * Is this possible? I think not, now that our callers check
1508 * both PageSwapCache and page_private after getting page lock;
1509 * but be defensive. Reverse old to newpage for clear and free.
1510 */
1511 oldpage = newpage;
1512 } else {
1513 mem_cgroup_migrate(oldpage, newpage);
1514 lru_cache_add_anon(newpage);
1515 *pagep = newpage;
1516 }
1517
1518 ClearPageSwapCache(oldpage);
1519 set_page_private(oldpage, 0);
1520
1521 unlock_page(oldpage);
1522 put_page(oldpage);
1523 put_page(oldpage);
1524 return error;
1525 }
1526
1527 /*
1528 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1529 *
1530 * If we allocate a new one we do not mark it dirty. That's up to the
1531 * vm. If we swap it in we mark it dirty since we also free the swap
1532 * entry since a page cannot live in both the swap and page cache.
1533 *
1534 * fault_mm and fault_type are only supplied by shmem_fault:
1535 * otherwise they are NULL.
1536 */
1537 static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1538 struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1539 struct mm_struct *fault_mm, int *fault_type)
1540 {
1541 struct address_space *mapping = inode->i_mapping;
1542 struct shmem_inode_info *info;
1543 struct shmem_sb_info *sbinfo;
1544 struct mm_struct *charge_mm;
1545 struct mem_cgroup *memcg;
1546 struct page *page;
1547 swp_entry_t swap;
1548 enum sgp_type sgp_huge = sgp;
1549 pgoff_t hindex = index;
1550 int error;
1551 int once = 0;
1552 int alloced = 0;
1553
1554 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1555 return -EFBIG;
1556 if (sgp == SGP_NOHUGE || sgp == SGP_HUGE)
1557 sgp = SGP_CACHE;
1558 repeat:
1559 swap.val = 0;
1560 page = find_lock_entry(mapping, index);
1561 if (radix_tree_exceptional_entry(page)) {
1562 swap = radix_to_swp_entry(page);
1563 page = NULL;
1564 }
1565
1566 if (sgp <= SGP_CACHE &&
1567 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1568 error = -EINVAL;
1569 goto unlock;
1570 }
1571
1572 if (page && sgp == SGP_WRITE)
1573 mark_page_accessed(page);
1574
1575 /* fallocated page? */
1576 if (page && !PageUptodate(page)) {
1577 if (sgp != SGP_READ)
1578 goto clear;
1579 unlock_page(page);
1580 put_page(page);
1581 page = NULL;
1582 }
1583 if (page || (sgp == SGP_READ && !swap.val)) {
1584 *pagep = page;
1585 return 0;
1586 }
1587
1588 /*
1589 * Fast cache lookup did not find it:
1590 * bring it back from swap or allocate.
1591 */
1592 info = SHMEM_I(inode);
1593 sbinfo = SHMEM_SB(inode->i_sb);
1594 charge_mm = fault_mm ? : current->mm;
1595
1596 if (swap.val) {
1597 /* Look it up and read it in.. */
1598 page = lookup_swap_cache(swap);
1599 if (!page) {
1600 /* Or update major stats only when swapin succeeds?? */
1601 if (fault_type) {
1602 *fault_type |= VM_FAULT_MAJOR;
1603 count_vm_event(PGMAJFAULT);
1604 mem_cgroup_count_vm_event(fault_mm, PGMAJFAULT);
1605 }
1606 /* Here we actually start the io */
1607 page = shmem_swapin(swap, gfp, info, index);
1608 if (!page) {
1609 error = -ENOMEM;
1610 goto failed;
1611 }
1612 }
1613
1614 /* We have to do this with page locked to prevent races */
1615 lock_page(page);
1616 if (!PageSwapCache(page) || page_private(page) != swap.val ||
1617 !shmem_confirm_swap(mapping, index, swap)) {
1618 error = -EEXIST; /* try again */
1619 goto unlock;
1620 }
1621 if (!PageUptodate(page)) {
1622 error = -EIO;
1623 goto failed;
1624 }
1625 wait_on_page_writeback(page);
1626
1627 if (shmem_should_replace_page(page, gfp)) {
1628 error = shmem_replace_page(&page, gfp, info, index);
1629 if (error)
1630 goto failed;
1631 }
1632
1633 error = mem_cgroup_try_charge(page, charge_mm, gfp, &memcg,
1634 false);
1635 if (!error) {
1636 error = shmem_add_to_page_cache(page, mapping, index,
1637 swp_to_radix_entry(swap));
1638 /*
1639 * We already confirmed swap under page lock, and make
1640 * no memory allocation here, so usually no possibility
1641 * of error; but free_swap_and_cache() only trylocks a
1642 * page, so it is just possible that the entry has been
1643 * truncated or holepunched since swap was confirmed.
1644 * shmem_undo_range() will have done some of the
1645 * unaccounting, now delete_from_swap_cache() will do
1646 * the rest.
1647 * Reset swap.val? No, leave it so "failed" goes back to
1648 * "repeat": reading a hole and writing should succeed.
1649 */
1650 if (error) {
1651 mem_cgroup_cancel_charge(page, memcg, false);
1652 delete_from_swap_cache(page);
1653 }
1654 }
1655 if (error)
1656 goto failed;
1657
1658 mem_cgroup_commit_charge(page, memcg, true, false);
1659
1660 spin_lock_irq(&info->lock);
1661 info->swapped--;
1662 shmem_recalc_inode(inode);
1663 spin_unlock_irq(&info->lock);
1664
1665 if (sgp == SGP_WRITE)
1666 mark_page_accessed(page);
1667
1668 delete_from_swap_cache(page);
1669 set_page_dirty(page);
1670 swap_free(swap);
1671
1672 } else {
1673 /* shmem_symlink() */
1674 if (mapping->a_ops != &shmem_aops)
1675 goto alloc_nohuge;
1676 if (shmem_huge == SHMEM_HUGE_DENY || sgp_huge == SGP_NOHUGE)
1677 goto alloc_nohuge;
1678 if (shmem_huge == SHMEM_HUGE_FORCE)
1679 goto alloc_huge;
1680 switch (sbinfo->huge) {
1681 loff_t i_size;
1682 pgoff_t off;
1683 case SHMEM_HUGE_NEVER:
1684 goto alloc_nohuge;
1685 case SHMEM_HUGE_WITHIN_SIZE:
1686 off = round_up(index, HPAGE_PMD_NR);
1687 i_size = round_up(i_size_read(inode), PAGE_SIZE);
1688 if (i_size >= HPAGE_PMD_SIZE &&
1689 i_size >> PAGE_SHIFT >= off)
1690 goto alloc_huge;
1691 /* fallthrough */
1692 case SHMEM_HUGE_ADVISE:
1693 if (sgp_huge == SGP_HUGE)
1694 goto alloc_huge;
1695 /* TODO: implement fadvise() hints */
1696 goto alloc_nohuge;
1697 }
1698
1699 alloc_huge:
1700 page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
1701 index, true);
1702 if (IS_ERR(page)) {
1703 alloc_nohuge: page = shmem_alloc_and_acct_page(gfp, info, sbinfo,
1704 index, false);
1705 }
1706 if (IS_ERR(page)) {
1707 int retry = 5;
1708 error = PTR_ERR(page);
1709 page = NULL;
1710 if (error != -ENOSPC)
1711 goto failed;
1712 /*
1713 * Try to reclaim some spece by splitting a huge page
1714 * beyond i_size on the filesystem.
1715 */
1716 while (retry--) {
1717 int ret;
1718 ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1719 if (ret == SHRINK_STOP)
1720 break;
1721 if (ret)
1722 goto alloc_nohuge;
1723 }
1724 goto failed;
1725 }
1726
1727 if (PageTransHuge(page))
1728 hindex = round_down(index, HPAGE_PMD_NR);
1729 else
1730 hindex = index;
1731
1732 if (sgp == SGP_WRITE)
1733 __SetPageReferenced(page);
1734
1735 error = mem_cgroup_try_charge(page, charge_mm, gfp, &memcg,
1736 PageTransHuge(page));
1737 if (error)
1738 goto unacct;
1739 error = radix_tree_maybe_preload_order(gfp & GFP_RECLAIM_MASK,
1740 compound_order(page));
1741 if (!error) {
1742 error = shmem_add_to_page_cache(page, mapping, hindex,
1743 NULL);
1744 radix_tree_preload_end();
1745 }
1746 if (error) {
1747 mem_cgroup_cancel_charge(page, memcg,
1748 PageTransHuge(page));
1749 goto unacct;
1750 }
1751 mem_cgroup_commit_charge(page, memcg, false,
1752 PageTransHuge(page));
1753 lru_cache_add_anon(page);
1754
1755 spin_lock_irq(&info->lock);
1756 info->alloced += 1 << compound_order(page);
1757 inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
1758 shmem_recalc_inode(inode);
1759 spin_unlock_irq(&info->lock);
1760 alloced = true;
1761
1762 if (PageTransHuge(page) &&
1763 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1764 hindex + HPAGE_PMD_NR - 1) {
1765 /*
1766 * Part of the huge page is beyond i_size: subject
1767 * to shrink under memory pressure.
1768 */
1769 spin_lock(&sbinfo->shrinklist_lock);
1770 if (list_empty(&info->shrinklist)) {
1771 list_add_tail(&info->shrinklist,
1772 &sbinfo->shrinklist);
1773 sbinfo->shrinklist_len++;
1774 }
1775 spin_unlock(&sbinfo->shrinklist_lock);
1776 }
1777
1778 /*
1779 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
1780 */
1781 if (sgp == SGP_FALLOC)
1782 sgp = SGP_WRITE;
1783 clear:
1784 /*
1785 * Let SGP_WRITE caller clear ends if write does not fill page;
1786 * but SGP_FALLOC on a page fallocated earlier must initialize
1787 * it now, lest undo on failure cancel our earlier guarantee.
1788 */
1789 if (sgp != SGP_WRITE && !PageUptodate(page)) {
1790 struct page *head = compound_head(page);
1791 int i;
1792
1793 for (i = 0; i < (1 << compound_order(head)); i++) {
1794 clear_highpage(head + i);
1795 flush_dcache_page(head + i);
1796 }
1797 SetPageUptodate(head);
1798 }
1799 }
1800
1801 /* Perhaps the file has been truncated since we checked */
1802 if (sgp <= SGP_CACHE &&
1803 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1804 if (alloced) {
1805 ClearPageDirty(page);
1806 delete_from_page_cache(page);
1807 spin_lock_irq(&info->lock);
1808 shmem_recalc_inode(inode);
1809 spin_unlock_irq(&info->lock);
1810 }
1811 error = -EINVAL;
1812 goto unlock;
1813 }
1814 *pagep = page + index - hindex;
1815 return 0;
1816
1817 /*
1818 * Error recovery.
1819 */
1820 unacct:
1821 if (sbinfo->max_blocks)
1822 percpu_counter_sub(&sbinfo->used_blocks,
1823 1 << compound_order(page));
1824 shmem_unacct_blocks(info->flags, 1 << compound_order(page));
1825
1826 if (PageTransHuge(page)) {
1827 unlock_page(page);
1828 put_page(page);
1829 goto alloc_nohuge;
1830 }
1831 failed:
1832 if (swap.val && !shmem_confirm_swap(mapping, index, swap))
1833 error = -EEXIST;
1834 unlock:
1835 if (page) {
1836 unlock_page(page);
1837 put_page(page);
1838 }
1839 if (error == -ENOSPC && !once++) {
1840 info = SHMEM_I(inode);
1841 spin_lock_irq(&info->lock);
1842 shmem_recalc_inode(inode);
1843 spin_unlock_irq(&info->lock);
1844 goto repeat;
1845 }
1846 if (error == -EEXIST) /* from above or from radix_tree_insert */
1847 goto repeat;
1848 return error;
1849 }
1850
1851 static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1852 {
1853 struct inode *inode = file_inode(vma->vm_file);
1854 gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
1855 enum sgp_type sgp;
1856 int error;
1857 int ret = VM_FAULT_LOCKED;
1858
1859 /*
1860 * Trinity finds that probing a hole which tmpfs is punching can
1861 * prevent the hole-punch from ever completing: which in turn
1862 * locks writers out with its hold on i_mutex. So refrain from
1863 * faulting pages into the hole while it's being punched. Although
1864 * shmem_undo_range() does remove the additions, it may be unable to
1865 * keep up, as each new page needs its own unmap_mapping_range() call,
1866 * and the i_mmap tree grows ever slower to scan if new vmas are added.
1867 *
1868 * It does not matter if we sometimes reach this check just before the
1869 * hole-punch begins, so that one fault then races with the punch:
1870 * we just need to make racing faults a rare case.
1871 *
1872 * The implementation below would be much simpler if we just used a
1873 * standard mutex or completion: but we cannot take i_mutex in fault,
1874 * and bloating every shmem inode for this unlikely case would be sad.
1875 */
1876 if (unlikely(inode->i_private)) {
1877 struct shmem_falloc *shmem_falloc;
1878
1879 spin_lock(&inode->i_lock);
1880 shmem_falloc = inode->i_private;
1881 if (shmem_falloc &&
1882 shmem_falloc->waitq &&
1883 vmf->pgoff >= shmem_falloc->start &&
1884 vmf->pgoff < shmem_falloc->next) {
1885 wait_queue_head_t *shmem_falloc_waitq;
1886 DEFINE_WAIT(shmem_fault_wait);
1887
1888 ret = VM_FAULT_NOPAGE;
1889 if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
1890 !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
1891 /* It's polite to up mmap_sem if we can */
1892 up_read(&vma->vm_mm->mmap_sem);
1893 ret = VM_FAULT_RETRY;
1894 }
1895
1896 shmem_falloc_waitq = shmem_falloc->waitq;
1897 prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
1898 TASK_UNINTERRUPTIBLE);
1899 spin_unlock(&inode->i_lock);
1900 schedule();
1901
1902 /*
1903 * shmem_falloc_waitq points into the shmem_fallocate()
1904 * stack of the hole-punching task: shmem_falloc_waitq
1905 * is usually invalid by the time we reach here, but
1906 * finish_wait() does not dereference it in that case;
1907 * though i_lock needed lest racing with wake_up_all().
1908 */
1909 spin_lock(&inode->i_lock);
1910 finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
1911 spin_unlock(&inode->i_lock);
1912 return ret;
1913 }
1914 spin_unlock(&inode->i_lock);
1915 }
1916
1917 sgp = SGP_CACHE;
1918 if (vma->vm_flags & VM_HUGEPAGE)
1919 sgp = SGP_HUGE;
1920 else if (vma->vm_flags & VM_NOHUGEPAGE)
1921 sgp = SGP_NOHUGE;
1922
1923 error = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
1924 gfp, vma->vm_mm, &ret);
1925 if (error)
1926 return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1927 return ret;
1928 }
1929
1930 unsigned long shmem_get_unmapped_area(struct file *file,
1931 unsigned long uaddr, unsigned long len,
1932 unsigned long pgoff, unsigned long flags)
1933 {
1934 unsigned long (*get_area)(struct file *,
1935 unsigned long, unsigned long, unsigned long, unsigned long);
1936 unsigned long addr;
1937 unsigned long offset;
1938 unsigned long inflated_len;
1939 unsigned long inflated_addr;
1940 unsigned long inflated_offset;
1941
1942 if (len > TASK_SIZE)
1943 return -ENOMEM;
1944
1945 get_area = current->mm->get_unmapped_area;
1946 addr = get_area(file, uaddr, len, pgoff, flags);
1947
1948 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1949 return addr;
1950 if (IS_ERR_VALUE(addr))
1951 return addr;
1952 if (addr & ~PAGE_MASK)
1953 return addr;
1954 if (addr > TASK_SIZE - len)
1955 return addr;
1956
1957 if (shmem_huge == SHMEM_HUGE_DENY)
1958 return addr;
1959 if (len < HPAGE_PMD_SIZE)
1960 return addr;
1961 if (flags & MAP_FIXED)
1962 return addr;
1963 /*
1964 * Our priority is to support MAP_SHARED mapped hugely;
1965 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
1966 * But if caller specified an address hint, respect that as before.
1967 */
1968 if (uaddr)
1969 return addr;
1970
1971 if (shmem_huge != SHMEM_HUGE_FORCE) {
1972 struct super_block *sb;
1973
1974 if (file) {
1975 VM_BUG_ON(file->f_op != &shmem_file_operations);
1976 sb = file_inode(file)->i_sb;
1977 } else {
1978 /*
1979 * Called directly from mm/mmap.c, or drivers/char/mem.c
1980 * for "/dev/zero", to create a shared anonymous object.
1981 */
1982 if (IS_ERR(shm_mnt))
1983 return addr;
1984 sb = shm_mnt->mnt_sb;
1985 }
1986 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
1987 return addr;
1988 }
1989
1990 offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
1991 if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
1992 return addr;
1993 if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
1994 return addr;
1995
1996 inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
1997 if (inflated_len > TASK_SIZE)
1998 return addr;
1999 if (inflated_len < len)
2000 return addr;
2001
2002 inflated_addr = get_area(NULL, 0, inflated_len, 0, flags);
2003 if (IS_ERR_VALUE(inflated_addr))
2004 return addr;
2005 if (inflated_addr & ~PAGE_MASK)
2006 return addr;
2007
2008 inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2009 inflated_addr += offset - inflated_offset;
2010 if (inflated_offset > offset)
2011 inflated_addr += HPAGE_PMD_SIZE;
2012
2013 if (inflated_addr > TASK_SIZE - len)
2014 return addr;
2015 return inflated_addr;
2016 }
2017
2018 #ifdef CONFIG_NUMA
2019 static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2020 {
2021 struct inode *inode = file_inode(vma->vm_file);
2022 return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2023 }
2024
2025 static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2026 unsigned long addr)
2027 {
2028 struct inode *inode = file_inode(vma->vm_file);
2029 pgoff_t index;
2030
2031 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2032 return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2033 }
2034 #endif
2035
2036 int shmem_lock(struct file *file, int lock, struct user_struct *user)
2037 {
2038 struct inode *inode = file_inode(file);
2039 struct shmem_inode_info *info = SHMEM_I(inode);
2040 int retval = -ENOMEM;
2041
2042 spin_lock_irq(&info->lock);
2043 if (lock && !(info->flags & VM_LOCKED)) {
2044 if (!user_shm_lock(inode->i_size, user))
2045 goto out_nomem;
2046 info->flags |= VM_LOCKED;
2047 mapping_set_unevictable(file->f_mapping);
2048 }
2049 if (!lock && (info->flags & VM_LOCKED) && user) {
2050 user_shm_unlock(inode->i_size, user);
2051 info->flags &= ~VM_LOCKED;
2052 mapping_clear_unevictable(file->f_mapping);
2053 }
2054 retval = 0;
2055
2056 out_nomem:
2057 spin_unlock_irq(&info->lock);
2058 return retval;
2059 }
2060
2061 static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2062 {
2063 file_accessed(file);
2064 vma->vm_ops = &shmem_vm_ops;
2065 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
2066 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
2067 (vma->vm_end & HPAGE_PMD_MASK)) {
2068 khugepaged_enter(vma, vma->vm_flags);
2069 }
2070 return 0;
2071 }
2072
2073 static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2074 umode_t mode, dev_t dev, unsigned long flags)
2075 {
2076 struct inode *inode;
2077 struct shmem_inode_info *info;
2078 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2079
2080 if (shmem_reserve_inode(sb))
2081 return NULL;
2082
2083 inode = new_inode(sb);
2084 if (inode) {
2085 inode->i_ino = get_next_ino();
2086 inode_init_owner(inode, dir, mode);
2087 inode->i_blocks = 0;
2088 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
2089 inode->i_generation = get_seconds();
2090 info = SHMEM_I(inode);
2091 memset(info, 0, (char *)inode - (char *)info);
2092 spin_lock_init(&info->lock);
2093 info->seals = F_SEAL_SEAL;
2094 info->flags = flags & VM_NORESERVE;
2095 INIT_LIST_HEAD(&info->shrinklist);
2096 INIT_LIST_HEAD(&info->swaplist);
2097 simple_xattrs_init(&info->xattrs);
2098 cache_no_acl(inode);
2099
2100 switch (mode & S_IFMT) {
2101 default:
2102 inode->i_op = &shmem_special_inode_operations;
2103 init_special_inode(inode, mode, dev);
2104 break;
2105 case S_IFREG:
2106 inode->i_mapping->a_ops = &shmem_aops;
2107 inode->i_op = &shmem_inode_operations;
2108 inode->i_fop = &shmem_file_operations;
2109 mpol_shared_policy_init(&info->policy,
2110 shmem_get_sbmpol(sbinfo));
2111 break;
2112 case S_IFDIR:
2113 inc_nlink(inode);
2114 /* Some things misbehave if size == 0 on a directory */
2115 inode->i_size = 2 * BOGO_DIRENT_SIZE;
2116 inode->i_op = &shmem_dir_inode_operations;
2117 inode->i_fop = &simple_dir_operations;
2118 break;
2119 case S_IFLNK:
2120 /*
2121 * Must not load anything in the rbtree,
2122 * mpol_free_shared_policy will not be called.
2123 */
2124 mpol_shared_policy_init(&info->policy, NULL);
2125 break;
2126 }
2127 } else
2128 shmem_free_inode(sb);
2129 return inode;
2130 }
2131
2132 bool shmem_mapping(struct address_space *mapping)
2133 {
2134 if (!mapping->host)
2135 return false;
2136
2137 return mapping->host->i_sb->s_op == &shmem_ops;
2138 }
2139
2140 #ifdef CONFIG_TMPFS
2141 static const struct inode_operations shmem_symlink_inode_operations;
2142 static const struct inode_operations shmem_short_symlink_operations;
2143
2144 #ifdef CONFIG_TMPFS_XATTR
2145 static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2146 #else
2147 #define shmem_initxattrs NULL
2148 #endif
2149
2150 static int
2151 shmem_write_begin(struct file *file, struct address_space *mapping,
2152 loff_t pos, unsigned len, unsigned flags,
2153 struct page **pagep, void **fsdata)
2154 {
2155 struct inode *inode = mapping->host;
2156 struct shmem_inode_info *info = SHMEM_I(inode);
2157 pgoff_t index = pos >> PAGE_SHIFT;
2158
2159 /* i_mutex is held by caller */
2160 if (unlikely(info->seals)) {
2161 if (info->seals & F_SEAL_WRITE)
2162 return -EPERM;
2163 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2164 return -EPERM;
2165 }
2166
2167 return shmem_getpage(inode, index, pagep, SGP_WRITE);
2168 }
2169
2170 static int
2171 shmem_write_end(struct file *file, struct address_space *mapping,
2172 loff_t pos, unsigned len, unsigned copied,
2173 struct page *page, void *fsdata)
2174 {
2175 struct inode *inode = mapping->host;
2176
2177 if (pos + copied > inode->i_size)
2178 i_size_write(inode, pos + copied);
2179
2180 if (!PageUptodate(page)) {
2181 struct page *head = compound_head(page);
2182 if (PageTransCompound(page)) {
2183 int i;
2184
2185 for (i = 0; i < HPAGE_PMD_NR; i++) {
2186 if (head + i == page)
2187 continue;
2188 clear_highpage(head + i);
2189 flush_dcache_page(head + i);
2190 }
2191 }
2192 if (copied < PAGE_SIZE) {
2193 unsigned from = pos & (PAGE_SIZE - 1);
2194 zero_user_segments(page, 0, from,
2195 from + copied, PAGE_SIZE);
2196 }
2197 SetPageUptodate(head);
2198 }
2199 set_page_dirty(page);
2200 unlock_page(page);
2201 put_page(page);
2202
2203 return copied;
2204 }
2205
2206 static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2207 {
2208 struct file *file = iocb->ki_filp;
2209 struct inode *inode = file_inode(file);
2210 struct address_space *mapping = inode->i_mapping;
2211 pgoff_t index;
2212 unsigned long offset;
2213 enum sgp_type sgp = SGP_READ;
2214 int error = 0;
2215 ssize_t retval = 0;
2216 loff_t *ppos = &iocb->ki_pos;
2217
2218 /*
2219 * Might this read be for a stacking filesystem? Then when reading
2220 * holes of a sparse file, we actually need to allocate those pages,
2221 * and even mark them dirty, so it cannot exceed the max_blocks limit.
2222 */
2223 if (!iter_is_iovec(to))
2224 sgp = SGP_CACHE;
2225
2226 index = *ppos >> PAGE_SHIFT;
2227 offset = *ppos & ~PAGE_MASK;
2228
2229 for (;;) {
2230 struct page *page = NULL;
2231 pgoff_t end_index;
2232 unsigned long nr, ret;
2233 loff_t i_size = i_size_read(inode);
2234
2235 end_index = i_size >> PAGE_SHIFT;
2236 if (index > end_index)
2237 break;
2238 if (index == end_index) {
2239 nr = i_size & ~PAGE_MASK;
2240 if (nr <= offset)
2241 break;
2242 }
2243
2244 error = shmem_getpage(inode, index, &page, sgp);
2245 if (error) {
2246 if (error == -EINVAL)
2247 error = 0;
2248 break;
2249 }
2250 if (page) {
2251 if (sgp == SGP_CACHE)
2252 set_page_dirty(page);
2253 unlock_page(page);
2254 }
2255
2256 /*
2257 * We must evaluate after, since reads (unlike writes)
2258 * are called without i_mutex protection against truncate
2259 */
2260 nr = PAGE_SIZE;
2261 i_size = i_size_read(inode);
2262 end_index = i_size >> PAGE_SHIFT;
2263 if (index == end_index) {
2264 nr = i_size & ~PAGE_MASK;
2265 if (nr <= offset) {
2266 if (page)
2267 put_page(page);
2268 break;
2269 }
2270 }
2271 nr -= offset;
2272
2273 if (page) {
2274 /*
2275 * If users can be writing to this page using arbitrary
2276 * virtual addresses, take care about potential aliasing
2277 * before reading the page on the kernel side.
2278 */
2279 if (mapping_writably_mapped(mapping))
2280 flush_dcache_page(page);
2281 /*
2282 * Mark the page accessed if we read the beginning.
2283 */
2284 if (!offset)
2285 mark_page_accessed(page);
2286 } else {
2287 page = ZERO_PAGE(0);
2288 get_page(page);
2289 }
2290
2291 /*
2292 * Ok, we have the page, and it's up-to-date, so
2293 * now we can copy it to user space...
2294 */
2295 ret = copy_page_to_iter(page, offset, nr, to);
2296 retval += ret;
2297 offset += ret;
2298 index += offset >> PAGE_SHIFT;
2299 offset &= ~PAGE_MASK;
2300
2301 put_page(page);
2302 if (!iov_iter_count(to))
2303 break;
2304 if (ret < nr) {
2305 error = -EFAULT;
2306 break;
2307 }
2308 cond_resched();
2309 }
2310
2311 *ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2312 file_accessed(file);
2313 return retval ? retval : error;
2314 }
2315
2316 static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
2317 struct pipe_inode_info *pipe, size_t len,
2318 unsigned int flags)
2319 {
2320 struct address_space *mapping = in->f_mapping;
2321 struct inode *inode = mapping->host;
2322 unsigned int loff, nr_pages, req_pages;
2323 struct page *pages[PIPE_DEF_BUFFERS];
2324 struct partial_page partial[PIPE_DEF_BUFFERS];
2325 struct page *page;
2326 pgoff_t index, end_index;
2327 loff_t isize, left;
2328 int error, page_nr;
2329 struct splice_pipe_desc spd = {
2330 .pages = pages,
2331 .partial = partial,
2332 .nr_pages_max = PIPE_DEF_BUFFERS,
2333 .flags = flags,
2334 .ops = &page_cache_pipe_buf_ops,
2335 .spd_release = spd_release_page,
2336 };
2337
2338 isize = i_size_read(inode);
2339 if (unlikely(*ppos >= isize))
2340 return 0;
2341
2342 left = isize - *ppos;
2343 if (unlikely(left < len))
2344 len = left;
2345
2346 if (splice_grow_spd(pipe, &spd))
2347 return -ENOMEM;
2348
2349 index = *ppos >> PAGE_SHIFT;
2350 loff = *ppos & ~PAGE_MASK;
2351 req_pages = (len + loff + PAGE_SIZE - 1) >> PAGE_SHIFT;
2352 nr_pages = min(req_pages, spd.nr_pages_max);
2353
2354 spd.nr_pages = find_get_pages_contig(mapping, index,
2355 nr_pages, spd.pages);
2356 index += spd.nr_pages;
2357 error = 0;
2358
2359 while (spd.nr_pages < nr_pages) {
2360 error = shmem_getpage(inode, index, &page, SGP_CACHE);
2361 if (error)
2362 break;
2363 unlock_page(page);
2364 spd.pages[spd.nr_pages++] = page;
2365 index++;
2366 }
2367
2368 index = *ppos >> PAGE_SHIFT;
2369 nr_pages = spd.nr_pages;
2370 spd.nr_pages = 0;
2371
2372 for (page_nr = 0; page_nr < nr_pages; page_nr++) {
2373 unsigned int this_len;
2374
2375 if (!len)
2376 break;
2377
2378 this_len = min_t(unsigned long, len, PAGE_SIZE - loff);
2379 page = spd.pages[page_nr];
2380
2381 if (!PageUptodate(page) || page->mapping != mapping) {
2382 error = shmem_getpage(inode, index, &page, SGP_CACHE);
2383 if (error)
2384 break;
2385 unlock_page(page);
2386 put_page(spd.pages[page_nr]);
2387 spd.pages[page_nr] = page;
2388 }
2389
2390 isize = i_size_read(inode);
2391 end_index = (isize - 1) >> PAGE_SHIFT;
2392 if (unlikely(!isize || index > end_index))
2393 break;
2394
2395 if (end_index == index) {
2396 unsigned int plen;
2397
2398 plen = ((isize - 1) & ~PAGE_MASK) + 1;
2399 if (plen <= loff)
2400 break;
2401
2402 this_len = min(this_len, plen - loff);
2403 len = this_len;
2404 }
2405
2406 spd.partial[page_nr].offset = loff;
2407 spd.partial[page_nr].len = this_len;
2408 len -= this_len;
2409 loff = 0;
2410 spd.nr_pages++;
2411 index++;
2412 }
2413
2414 while (page_nr < nr_pages)
2415 put_page(spd.pages[page_nr++]);
2416
2417 if (spd.nr_pages)
2418 error = splice_to_pipe(pipe, &spd);
2419
2420 splice_shrink_spd(&spd);
2421
2422 if (error > 0) {
2423 *ppos += error;
2424 file_accessed(in);
2425 }
2426 return error;
2427 }
2428
2429 /*
2430 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
2431 */
2432 static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
2433 pgoff_t index, pgoff_t end, int whence)
2434 {
2435 struct page *page;
2436 struct pagevec pvec;
2437 pgoff_t indices[PAGEVEC_SIZE];
2438 bool done = false;
2439 int i;
2440
2441 pagevec_init(&pvec, 0);
2442 pvec.nr = 1; /* start small: we may be there already */
2443 while (!done) {
2444 pvec.nr = find_get_entries(mapping, index,
2445 pvec.nr, pvec.pages, indices);
2446 if (!pvec.nr) {
2447 if (whence == SEEK_DATA)
2448 index = end;
2449 break;
2450 }
2451 for (i = 0; i < pvec.nr; i++, index++) {
2452 if (index < indices[i]) {
2453 if (whence == SEEK_HOLE) {
2454 done = true;
2455 break;
2456 }
2457 index = indices[i];
2458 }
2459 page = pvec.pages[i];
2460 if (page && !radix_tree_exceptional_entry(page)) {
2461 if (!PageUptodate(page))
2462 page = NULL;
2463 }
2464 if (index >= end ||
2465 (page && whence == SEEK_DATA) ||
2466 (!page && whence == SEEK_HOLE)) {
2467 done = true;
2468 break;
2469 }
2470 }
2471 pagevec_remove_exceptionals(&pvec);
2472 pagevec_release(&pvec);
2473 pvec.nr = PAGEVEC_SIZE;
2474 cond_resched();
2475 }
2476 return index;
2477 }
2478
2479 static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2480 {
2481 struct address_space *mapping = file->f_mapping;
2482 struct inode *inode = mapping->host;
2483 pgoff_t start, end;
2484 loff_t new_offset;
2485
2486 if (whence != SEEK_DATA && whence != SEEK_HOLE)
2487 return generic_file_llseek_size(file, offset, whence,
2488 MAX_LFS_FILESIZE, i_size_read(inode));
2489 inode_lock(inode);
2490 /* We're holding i_mutex so we can access i_size directly */
2491
2492 if (offset < 0)
2493 offset = -EINVAL;
2494 else if (offset >= inode->i_size)
2495 offset = -ENXIO;
2496 else {
2497 start = offset >> PAGE_SHIFT;
2498 end = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2499 new_offset = shmem_seek_hole_data(mapping, start, end, whence);
2500 new_offset <<= PAGE_SHIFT;
2501 if (new_offset > offset) {
2502 if (new_offset < inode->i_size)
2503 offset = new_offset;
2504 else if (whence == SEEK_DATA)
2505 offset = -ENXIO;
2506 else
2507 offset = inode->i_size;
2508 }
2509 }
2510
2511 if (offset >= 0)
2512 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2513 inode_unlock(inode);
2514 return offset;
2515 }
2516
2517 /*
2518 * We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
2519 * so reuse a tag which we firmly believe is never set or cleared on shmem.
2520 */
2521 #define SHMEM_TAG_PINNED PAGECACHE_TAG_TOWRITE
2522 #define LAST_SCAN 4 /* about 150ms max */
2523
2524 static void shmem_tag_pins(struct address_space *mapping)
2525 {
2526 struct radix_tree_iter iter;
2527 void **slot;
2528 pgoff_t start;
2529 struct page *page;
2530
2531 lru_add_drain();
2532 start = 0;
2533 rcu_read_lock();
2534
2535 radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
2536 page = radix_tree_deref_slot(slot);
2537 if (!page || radix_tree_exception(page)) {
2538 if (radix_tree_deref_retry(page)) {
2539 slot = radix_tree_iter_retry(&iter);
2540 continue;
2541 }
2542 } else if (page_count(page) - page_mapcount(page) > 1) {
2543 spin_lock_irq(&mapping->tree_lock);
2544 radix_tree_tag_set(&mapping->page_tree, iter.index,
2545 SHMEM_TAG_PINNED);
2546 spin_unlock_irq(&mapping->tree_lock);
2547 }
2548
2549 if (need_resched()) {
2550 cond_resched_rcu();
2551 slot = radix_tree_iter_next(&iter);
2552 }
2553 }
2554 rcu_read_unlock();
2555 }
2556
2557 /*
2558 * Setting SEAL_WRITE requires us to verify there's no pending writer. However,
2559 * via get_user_pages(), drivers might have some pending I/O without any active
2560 * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages
2561 * and see whether it has an elevated ref-count. If so, we tag them and wait for
2562 * them to be dropped.
2563 * The caller must guarantee that no new user will acquire writable references
2564 * to those pages to avoid races.
2565 */
2566 static int shmem_wait_for_pins(struct address_space *mapping)
2567 {
2568 struct radix_tree_iter iter;
2569 void **slot;
2570 pgoff_t start;
2571 struct page *page;
2572 int error, scan;
2573
2574 shmem_tag_pins(mapping);
2575
2576 error = 0;
2577 for (scan = 0; scan <= LAST_SCAN; scan++) {
2578 if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED))
2579 break;
2580
2581 if (!scan)
2582 lru_add_drain_all();
2583 else if (schedule_timeout_killable((HZ << scan) / 200))
2584 scan = LAST_SCAN;
2585
2586 start = 0;
2587 rcu_read_lock();
2588 radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter,
2589 start, SHMEM_TAG_PINNED) {
2590
2591 page = radix_tree_deref_slot(slot);
2592 if (radix_tree_exception(page)) {
2593 if (radix_tree_deref_retry(page)) {
2594 slot = radix_tree_iter_retry(&iter);
2595 continue;
2596 }
2597
2598 page = NULL;
2599 }
2600
2601 if (page &&
2602 page_count(page) - page_mapcount(page) != 1) {
2603 if (scan < LAST_SCAN)
2604 goto continue_resched;
2605
2606 /*
2607 * On the last scan, we clean up all those tags
2608 * we inserted; but make a note that we still
2609 * found pages pinned.
2610 */
2611 error = -EBUSY;
2612 }
2613
2614 spin_lock_irq(&mapping->tree_lock);
2615 radix_tree_tag_clear(&mapping->page_tree,
2616 iter.index, SHMEM_TAG_PINNED);
2617 spin_unlock_irq(&mapping->tree_lock);
2618 continue_resched:
2619 if (need_resched()) {
2620 cond_resched_rcu();
2621 slot = radix_tree_iter_next(&iter);
2622 }
2623 }
2624 rcu_read_unlock();
2625 }
2626
2627 return error;
2628 }
2629
2630 #define F_ALL_SEALS (F_SEAL_SEAL | \
2631 F_SEAL_SHRINK | \
2632 F_SEAL_GROW | \
2633 F_SEAL_WRITE)
2634
2635 int shmem_add_seals(struct file *file, unsigned int seals)
2636 {
2637 struct inode *inode = file_inode(file);
2638 struct shmem_inode_info *info = SHMEM_I(inode);
2639 int error;
2640
2641 /*
2642 * SEALING
2643 * Sealing allows multiple parties to share a shmem-file but restrict
2644 * access to a specific subset of file operations. Seals can only be
2645 * added, but never removed. This way, mutually untrusted parties can
2646 * share common memory regions with a well-defined policy. A malicious
2647 * peer can thus never perform unwanted operations on a shared object.
2648 *
2649 * Seals are only supported on special shmem-files and always affect
2650 * the whole underlying inode. Once a seal is set, it may prevent some
2651 * kinds of access to the file. Currently, the following seals are
2652 * defined:
2653 * SEAL_SEAL: Prevent further seals from being set on this file
2654 * SEAL_SHRINK: Prevent the file from shrinking
2655 * SEAL_GROW: Prevent the file from growing
2656 * SEAL_WRITE: Prevent write access to the file
2657 *
2658 * As we don't require any trust relationship between two parties, we
2659 * must prevent seals from being removed. Therefore, sealing a file
2660 * only adds a given set of seals to the file, it never touches
2661 * existing seals. Furthermore, the "setting seals"-operation can be
2662 * sealed itself, which basically prevents any further seal from being
2663 * added.
2664 *
2665 * Semantics of sealing are only defined on volatile files. Only
2666 * anonymous shmem files support sealing. More importantly, seals are
2667 * never written to disk. Therefore, there's no plan to support it on
2668 * other file types.
2669 */
2670
2671 if (file->f_op != &shmem_file_operations)
2672 return -EINVAL;
2673 if (!(file->f_mode & FMODE_WRITE))
2674 return -EPERM;
2675 if (seals & ~(unsigned int)F_ALL_SEALS)
2676 return -EINVAL;
2677
2678 inode_lock(inode);
2679
2680 if (info->seals & F_SEAL_SEAL) {
2681 error = -EPERM;
2682 goto unlock;
2683 }
2684
2685 if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) {
2686 error = mapping_deny_writable(file->f_mapping);
2687 if (error)
2688 goto unlock;
2689
2690 error = shmem_wait_for_pins(file->f_mapping);
2691 if (error) {
2692 mapping_allow_writable(file->f_mapping);
2693 goto unlock;
2694 }
2695 }
2696
2697 info->seals |= seals;
2698 error = 0;
2699
2700 unlock:
2701 inode_unlock(inode);
2702 return error;
2703 }
2704 EXPORT_SYMBOL_GPL(shmem_add_seals);
2705
2706 int shmem_get_seals(struct file *file)
2707 {
2708 if (file->f_op != &shmem_file_operations)
2709 return -EINVAL;
2710
2711 return SHMEM_I(file_inode(file))->seals;
2712 }
2713 EXPORT_SYMBOL_GPL(shmem_get_seals);
2714
2715 long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
2716 {
2717 long error;
2718
2719 switch (cmd) {
2720 case F_ADD_SEALS:
2721 /* disallow upper 32bit */
2722 if (arg > UINT_MAX)
2723 return -EINVAL;
2724
2725 error = shmem_add_seals(file, arg);
2726 break;
2727 case F_GET_SEALS:
2728 error = shmem_get_seals(file);
2729 break;
2730 default:
2731 error = -EINVAL;
2732 break;
2733 }
2734
2735 return error;
2736 }
2737
2738 static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2739 loff_t len)
2740 {
2741 struct inode *inode = file_inode(file);
2742 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2743 struct shmem_inode_info *info = SHMEM_I(inode);
2744 struct shmem_falloc shmem_falloc;
2745 pgoff_t start, index, end;
2746 int error;
2747
2748 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2749 return -EOPNOTSUPP;
2750
2751 inode_lock(inode);
2752
2753 if (mode & FALLOC_FL_PUNCH_HOLE) {
2754 struct address_space *mapping = file->f_mapping;
2755 loff_t unmap_start = round_up(offset, PAGE_SIZE);
2756 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2757 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2758
2759 /* protected by i_mutex */
2760 if (info->seals & F_SEAL_WRITE) {
2761 error = -EPERM;
2762 goto out;
2763 }
2764
2765 shmem_falloc.waitq = &shmem_falloc_waitq;
2766 shmem_falloc.start = unmap_start >> PAGE_SHIFT;
2767 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2768 spin_lock(&inode->i_lock);
2769 inode->i_private = &shmem_falloc;
2770 spin_unlock(&inode->i_lock);
2771
2772 if ((u64)unmap_end > (u64)unmap_start)
2773 unmap_mapping_range(mapping, unmap_start,
2774 1 + unmap_end - unmap_start, 0);
2775 shmem_truncate_range(inode, offset, offset + len - 1);
2776 /* No need to unmap again: hole-punching leaves COWed pages */
2777
2778 spin_lock(&inode->i_lock);
2779 inode->i_private = NULL;
2780 wake_up_all(&shmem_falloc_waitq);
2781 spin_unlock(&inode->i_lock);
2782 error = 0;
2783 goto out;
2784 }
2785
2786 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2787 error = inode_newsize_ok(inode, offset + len);
2788 if (error)
2789 goto out;
2790
2791 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2792 error = -EPERM;
2793 goto out;
2794 }
2795
2796 start = offset >> PAGE_SHIFT;
2797 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2798 /* Try to avoid a swapstorm if len is impossible to satisfy */
2799 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2800 error = -ENOSPC;
2801 goto out;
2802 }
2803
2804 shmem_falloc.waitq = NULL;
2805 shmem_falloc.start = start;
2806 shmem_falloc.next = start;
2807 shmem_falloc.nr_falloced = 0;
2808 shmem_falloc.nr_unswapped = 0;
2809 spin_lock(&inode->i_lock);
2810 inode->i_private = &shmem_falloc;
2811 spin_unlock(&inode->i_lock);
2812
2813 for (index = start; index < end; index++) {
2814 struct page *page;
2815
2816 /*
2817 * Good, the fallocate(2) manpage permits EINTR: we may have
2818 * been interrupted because we are using up too much memory.
2819 */
2820 if (signal_pending(current))
2821 error = -EINTR;
2822 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2823 error = -ENOMEM;
2824 else
2825 error = shmem_getpage(inode, index, &page, SGP_FALLOC);
2826 if (error) {
2827 /* Remove the !PageUptodate pages we added */
2828 if (index > start) {
2829 shmem_undo_range(inode,
2830 (loff_t)start << PAGE_SHIFT,
2831 ((loff_t)index << PAGE_SHIFT) - 1, true);
2832 }
2833 goto undone;
2834 }
2835
2836 /*
2837 * Inform shmem_writepage() how far we have reached.
2838 * No need for lock or barrier: we have the page lock.
2839 */
2840 shmem_falloc.next++;
2841 if (!PageUptodate(page))
2842 shmem_falloc.nr_falloced++;
2843
2844 /*
2845 * If !PageUptodate, leave it that way so that freeable pages
2846 * can be recognized if we need to rollback on error later.
2847 * But set_page_dirty so that memory pressure will swap rather
2848 * than free the pages we are allocating (and SGP_CACHE pages
2849 * might still be clean: we now need to mark those dirty too).
2850 */
2851 set_page_dirty(page);
2852 unlock_page(page);
2853 put_page(page);
2854 cond_resched();
2855 }
2856
2857 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2858 i_size_write(inode, offset + len);
2859 inode->i_ctime = CURRENT_TIME;
2860 undone:
2861 spin_lock(&inode->i_lock);
2862 inode->i_private = NULL;
2863 spin_unlock(&inode->i_lock);
2864 out:
2865 inode_unlock(inode);
2866 return error;
2867 }
2868
2869 static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2870 {
2871 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2872
2873 buf->f_type = TMPFS_MAGIC;
2874 buf->f_bsize = PAGE_SIZE;
2875 buf->f_namelen = NAME_MAX;
2876 if (sbinfo->max_blocks) {
2877 buf->f_blocks = sbinfo->max_blocks;
2878 buf->f_bavail =
2879 buf->f_bfree = sbinfo->max_blocks -
2880 percpu_counter_sum(&sbinfo->used_blocks);
2881 }
2882 if (sbinfo->max_inodes) {
2883 buf->f_files = sbinfo->max_inodes;
2884 buf->f_ffree = sbinfo->free_inodes;
2885 }
2886 /* else leave those fields 0 like simple_statfs */
2887 return 0;
2888 }
2889
2890 /*
2891 * File creation. Allocate an inode, and we're done..
2892 */
2893 static int
2894 shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
2895 {
2896 struct inode *inode;
2897 int error = -ENOSPC;
2898
2899 inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
2900 if (inode) {
2901 error = simple_acl_create(dir, inode);
2902 if (error)
2903 goto out_iput;
2904 error = security_inode_init_security(inode, dir,
2905 &dentry->d_name,
2906 shmem_initxattrs, NULL);
2907 if (error && error != -EOPNOTSUPP)
2908 goto out_iput;
2909
2910 error = 0;
2911 dir->i_size += BOGO_DIRENT_SIZE;
2912 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2913 d_instantiate(dentry, inode);
2914 dget(dentry); /* Extra count - pin the dentry in core */
2915 }
2916 return error;
2917 out_iput:
2918 iput(inode);
2919 return error;
2920 }
2921
2922 static int
2923 shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
2924 {
2925 struct inode *inode;
2926 int error = -ENOSPC;
2927
2928 inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
2929 if (inode) {
2930 error = security_inode_init_security(inode, dir,
2931 NULL,
2932 shmem_initxattrs, NULL);
2933 if (error && error != -EOPNOTSUPP)
2934 goto out_iput;
2935 error = simple_acl_create(dir, inode);
2936 if (error)
2937 goto out_iput;
2938 d_tmpfile(dentry, inode);
2939 }
2940 return error;
2941 out_iput:
2942 iput(inode);
2943 return error;
2944 }
2945
2946 static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
2947 {
2948 int error;
2949
2950 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
2951 return error;
2952 inc_nlink(dir);
2953 return 0;
2954 }
2955
2956 static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
2957 bool excl)
2958 {
2959 return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
2960 }
2961
2962 /*
2963 * Link a file..
2964 */
2965 static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
2966 {
2967 struct inode *inode = d_inode(old_dentry);
2968 int ret;
2969
2970 /*
2971 * No ordinary (disk based) filesystem counts links as inodes;
2972 * but each new link needs a new dentry, pinning lowmem, and
2973 * tmpfs dentries cannot be pruned until they are unlinked.
2974 */
2975 ret = shmem_reserve_inode(inode->i_sb);
2976 if (ret)
2977 goto out;
2978
2979 dir->i_size += BOGO_DIRENT_SIZE;
2980 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2981 inc_nlink(inode);
2982 ihold(inode); /* New dentry reference */
2983 dget(dentry); /* Extra pinning count for the created dentry */
2984 d_instantiate(dentry, inode);
2985 out:
2986 return ret;
2987 }
2988
2989 static int shmem_unlink(struct inode *dir, struct dentry *dentry)
2990 {
2991 struct inode *inode = d_inode(dentry);
2992
2993 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
2994 shmem_free_inode(inode->i_sb);
2995
2996 dir->i_size -= BOGO_DIRENT_SIZE;
2997 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
2998 drop_nlink(inode);
2999 dput(dentry); /* Undo the count from "create" - this does all the work */
3000 return 0;
3001 }
3002
3003 static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3004 {
3005 if (!simple_empty(dentry))
3006 return -ENOTEMPTY;
3007
3008 drop_nlink(d_inode(dentry));
3009 drop_nlink(dir);
3010 return shmem_unlink(dir, dentry);
3011 }
3012
3013 static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
3014 {
3015 bool old_is_dir = d_is_dir(old_dentry);
3016 bool new_is_dir = d_is_dir(new_dentry);
3017
3018 if (old_dir != new_dir && old_is_dir != new_is_dir) {
3019 if (old_is_dir) {
3020 drop_nlink(old_dir);
3021 inc_nlink(new_dir);
3022 } else {
3023 drop_nlink(new_dir);
3024 inc_nlink(old_dir);
3025 }
3026 }
3027 old_dir->i_ctime = old_dir->i_mtime =
3028 new_dir->i_ctime = new_dir->i_mtime =
3029 d_inode(old_dentry)->i_ctime =
3030 d_inode(new_dentry)->i_ctime = CURRENT_TIME;
3031
3032 return 0;
3033 }
3034
3035 static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
3036 {
3037 struct dentry *whiteout;
3038 int error;
3039
3040 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3041 if (!whiteout)
3042 return -ENOMEM;
3043
3044 error = shmem_mknod(old_dir, whiteout,
3045 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3046 dput(whiteout);
3047 if (error)
3048 return error;
3049
3050 /*
3051 * Cheat and hash the whiteout while the old dentry is still in
3052 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3053 *
3054 * d_lookup() will consistently find one of them at this point,
3055 * not sure which one, but that isn't even important.
3056 */
3057 d_rehash(whiteout);
3058 return 0;
3059 }
3060
3061 /*
3062 * The VFS layer already does all the dentry stuff for rename,
3063 * we just have to decrement the usage count for the target if
3064 * it exists so that the VFS layer correctly free's it when it
3065 * gets overwritten.
3066 */
3067 static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
3068 {
3069 struct inode *inode = d_inode(old_dentry);
3070 int they_are_dirs = S_ISDIR(inode->i_mode);
3071
3072 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3073 return -EINVAL;
3074
3075 if (flags & RENAME_EXCHANGE)
3076 return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
3077
3078 if (!simple_empty(new_dentry))
3079 return -ENOTEMPTY;
3080
3081 if (flags & RENAME_WHITEOUT) {
3082 int error;
3083
3084 error = shmem_whiteout(old_dir, old_dentry);
3085 if (error)
3086 return error;
3087 }
3088
3089 if (d_really_is_positive(new_dentry)) {
3090 (void) shmem_unlink(new_dir, new_dentry);
3091 if (they_are_dirs) {
3092 drop_nlink(d_inode(new_dentry));
3093 drop_nlink(old_dir);
3094 }
3095 } else if (they_are_dirs) {
3096 drop_nlink(old_dir);
3097 inc_nlink(new_dir);
3098 }
3099
3100 old_dir->i_size -= BOGO_DIRENT_SIZE;
3101 new_dir->i_size += BOGO_DIRENT_SIZE;
3102 old_dir->i_ctime = old_dir->i_mtime =
3103 new_dir->i_ctime = new_dir->i_mtime =
3104 inode->i_ctime = CURRENT_TIME;
3105 return 0;
3106 }
3107
3108 static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
3109 {
3110 int error;
3111 int len;
3112 struct inode *inode;
3113 struct page *page;
3114 struct shmem_inode_info *info;
3115
3116 len = strlen(symname) + 1;
3117 if (len > PAGE_SIZE)
3118 return -ENAMETOOLONG;
3119
3120 inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
3121 if (!inode)
3122 return -ENOSPC;
3123
3124 error = security_inode_init_security(inode, dir, &dentry->d_name,
3125 shmem_initxattrs, NULL);
3126 if (error) {
3127 if (error != -EOPNOTSUPP) {
3128 iput(inode);
3129 return error;
3130 }
3131 error = 0;
3132 }
3133
3134 info = SHMEM_I(inode);
3135 inode->i_size = len-1;
3136 if (len <= SHORT_SYMLINK_LEN) {
3137 inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3138 if (!inode->i_link) {
3139 iput(inode);
3140 return -ENOMEM;
3141 }
3142 inode->i_op = &shmem_short_symlink_operations;
3143 } else {
3144 inode_nohighmem(inode);
3145 error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3146 if (error) {
3147 iput(inode);
3148 return error;
3149 }
3150 inode->i_mapping->a_ops = &shmem_aops;
3151 inode->i_op = &shmem_symlink_inode_operations;
3152 memcpy(page_address(page), symname, len);
3153 SetPageUptodate(page);
3154 set_page_dirty(page);
3155 unlock_page(page);
3156 put_page(page);
3157 }
3158 dir->i_size += BOGO_DIRENT_SIZE;
3159 dir->i_ctime = dir->i_mtime = CURRENT_TIME;
3160 d_instantiate(dentry, inode);
3161 dget(dentry);
3162 return 0;
3163 }
3164
3165 static void shmem_put_link(void *arg)
3166 {
3167 mark_page_accessed(arg);
3168 put_page(arg);
3169 }
3170
3171 static const char *shmem_get_link(struct dentry *dentry,
3172 struct inode *inode,
3173 struct delayed_call *done)
3174 {
3175 struct page *page = NULL;
3176 int error;
3177 if (!dentry) {
3178 page = find_get_page(inode->i_mapping, 0);
3179 if (!page)
3180 return ERR_PTR(-ECHILD);
3181 if (!PageUptodate(page)) {
3182 put_page(page);
3183 return ERR_PTR(-ECHILD);
3184 }
3185 } else {
3186 error = shmem_getpage(inode, 0, &page, SGP_READ);
3187 if (error)
3188 return ERR_PTR(error);
3189 unlock_page(page);
3190 }
3191 set_delayed_call(done, shmem_put_link, page);
3192 return page_address(page);
3193 }
3194
3195 #ifdef CONFIG_TMPFS_XATTR
3196 /*
3197 * Superblocks without xattr inode operations may get some security.* xattr
3198 * support from the LSM "for free". As soon as we have any other xattrs
3199 * like ACLs, we also need to implement the security.* handlers at
3200 * filesystem level, though.
3201 */
3202
3203 /*
3204 * Callback for security_inode_init_security() for acquiring xattrs.
3205 */
3206 static int shmem_initxattrs(struct inode *inode,
3207 const struct xattr *xattr_array,
3208 void *fs_info)
3209 {
3210 struct shmem_inode_info *info = SHMEM_I(inode);
3211 const struct xattr *xattr;
3212 struct simple_xattr *new_xattr;
3213 size_t len;
3214
3215 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3216 new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3217 if (!new_xattr)
3218 return -ENOMEM;
3219
3220 len = strlen(xattr->name) + 1;
3221 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3222 GFP_KERNEL);
3223 if (!new_xattr->name) {
3224 kfree(new_xattr);
3225 return -ENOMEM;
3226 }
3227
3228 memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3229 XATTR_SECURITY_PREFIX_LEN);
3230 memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3231 xattr->name, len);
3232
3233 simple_xattr_list_add(&info->xattrs, new_xattr);
3234 }
3235
3236 return 0;
3237 }
3238
3239 static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3240 struct dentry *unused, struct inode *inode,
3241 const char *name, void *buffer, size_t size)
3242 {
3243 struct shmem_inode_info *info = SHMEM_I(inode);
3244
3245 name = xattr_full_name(handler, name);
3246 return simple_xattr_get(&info->xattrs, name, buffer, size);
3247 }
3248
3249 static int shmem_xattr_handler_set(const struct xattr_handler *handler,
3250 struct dentry *unused, struct inode *inode,
3251 const char *name, const void *value,
3252 size_t size, int flags)
3253 {
3254 struct shmem_inode_info *info = SHMEM_I(inode);
3255
3256 name = xattr_full_name(handler, name);
3257 return simple_xattr_set(&info->xattrs, name, value, size, flags);
3258 }
3259
3260 static const struct xattr_handler shmem_security_xattr_handler = {
3261 .prefix = XATTR_SECURITY_PREFIX,
3262 .get = shmem_xattr_handler_get,
3263 .set = shmem_xattr_handler_set,
3264 };
3265
3266 static const struct xattr_handler shmem_trusted_xattr_handler = {
3267 .prefix = XATTR_TRUSTED_PREFIX,
3268 .get = shmem_xattr_handler_get,
3269 .set = shmem_xattr_handler_set,
3270 };
3271
3272 static const struct xattr_handler *shmem_xattr_handlers[] = {
3273 #ifdef CONFIG_TMPFS_POSIX_ACL
3274 &posix_acl_access_xattr_handler,
3275 &posix_acl_default_xattr_handler,
3276 #endif
3277 &shmem_security_xattr_handler,
3278 &shmem_trusted_xattr_handler,
3279 NULL
3280 };
3281
3282 static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3283 {
3284 struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3285 return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3286 }
3287 #endif /* CONFIG_TMPFS_XATTR */
3288
3289 static const struct inode_operations shmem_short_symlink_operations = {
3290 .readlink = generic_readlink,
3291 .get_link = simple_get_link,
3292 #ifdef CONFIG_TMPFS_XATTR
3293 .setxattr = generic_setxattr,
3294 .getxattr = generic_getxattr,
3295 .listxattr = shmem_listxattr,
3296 .removexattr = generic_removexattr,
3297 #endif
3298 };
3299
3300 static const struct inode_operations shmem_symlink_inode_operations = {
3301 .readlink = generic_readlink,
3302 .get_link = shmem_get_link,
3303 #ifdef CONFIG_TMPFS_XATTR
3304 .setxattr = generic_setxattr,
3305 .getxattr = generic_getxattr,
3306 .listxattr = shmem_listxattr,
3307 .removexattr = generic_removexattr,
3308 #endif
3309 };
3310
3311 static struct dentry *shmem_get_parent(struct dentry *child)
3312 {
3313 return ERR_PTR(-ESTALE);
3314 }
3315
3316 static int shmem_match(struct inode *ino, void *vfh)
3317 {
3318 __u32 *fh = vfh;
3319 __u64 inum = fh[2];
3320 inum = (inum << 32) | fh[1];
3321 return ino->i_ino == inum && fh[0] == ino->i_generation;
3322 }
3323
3324 static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3325 struct fid *fid, int fh_len, int fh_type)
3326 {
3327 struct inode *inode;
3328 struct dentry *dentry = NULL;
3329 u64 inum;
3330
3331 if (fh_len < 3)
3332 return NULL;
3333
3334 inum = fid->raw[2];
3335 inum = (inum << 32) | fid->raw[1];
3336
3337 inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3338 shmem_match, fid->raw);
3339 if (inode) {
3340 dentry = d_find_alias(inode);
3341 iput(inode);
3342 }
3343
3344 return dentry;
3345 }
3346
3347 static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3348 struct inode *parent)
3349 {
3350 if (*len < 3) {
3351 *len = 3;
3352 return FILEID_INVALID;
3353 }
3354
3355 if (inode_unhashed(inode)) {
3356 /* Unfortunately insert_inode_hash is not idempotent,
3357 * so as we hash inodes here rather than at creation
3358 * time, we need a lock to ensure we only try
3359 * to do it once
3360 */
3361 static DEFINE_SPINLOCK(lock);
3362 spin_lock(&lock);
3363 if (inode_unhashed(inode))
3364 __insert_inode_hash(inode,
3365 inode->i_ino + inode->i_generation);
3366 spin_unlock(&lock);
3367 }
3368
3369 fh[0] = inode->i_generation;
3370 fh[1] = inode->i_ino;
3371 fh[2] = ((__u64)inode->i_ino) >> 32;
3372
3373 *len = 3;
3374 return 1;
3375 }
3376
3377 static const struct export_operations shmem_export_ops = {
3378 .get_parent = shmem_get_parent,
3379 .encode_fh = shmem_encode_fh,
3380 .fh_to_dentry = shmem_fh_to_dentry,
3381 };
3382
3383 static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
3384 bool remount)
3385 {
3386 char *this_char, *value, *rest;
3387 struct mempolicy *mpol = NULL;
3388 uid_t uid;
3389 gid_t gid;
3390
3391 while (options != NULL) {
3392 this_char = options;
3393 for (;;) {
3394 /*
3395 * NUL-terminate this option: unfortunately,
3396 * mount options form a comma-separated list,
3397 * but mpol's nodelist may also contain commas.
3398 */
3399 options = strchr(options, ',');
3400 if (options == NULL)
3401 break;
3402 options++;
3403 if (!isdigit(*options)) {
3404 options[-1] = '\0';
3405 break;
3406 }
3407 }
3408 if (!*this_char)
3409 continue;
3410 if ((value = strchr(this_char,'=')) != NULL) {
3411 *value++ = 0;
3412 } else {
3413 pr_err("tmpfs: No value for mount option '%s'\n",
3414 this_char);
3415 goto error;
3416 }
3417
3418 if (!strcmp(this_char,"size")) {
3419 unsigned long long size;
3420 size = memparse(value,&rest);
3421 if (*rest == '%') {
3422 size <<= PAGE_SHIFT;
3423 size *= totalram_pages;
3424 do_div(size, 100);
3425 rest++;
3426 }
3427 if (*rest)
3428 goto bad_val;
3429 sbinfo->max_blocks =
3430 DIV_ROUND_UP(size, PAGE_SIZE);
3431 } else if (!strcmp(this_char,"nr_blocks")) {
3432 sbinfo->max_blocks = memparse(value, &rest);
3433 if (*rest)
3434 goto bad_val;
3435 } else if (!strcmp(this_char,"nr_inodes")) {
3436 sbinfo->max_inodes = memparse(value, &rest);
3437 if (*rest)
3438 goto bad_val;
3439 } else if (!strcmp(this_char,"mode")) {
3440 if (remount)
3441 continue;
3442 sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
3443 if (*rest)
3444 goto bad_val;
3445 } else if (!strcmp(this_char,"uid")) {
3446 if (remount)
3447 continue;
3448 uid = simple_strtoul(value, &rest, 0);
3449 if (*rest)
3450 goto bad_val;
3451 sbinfo->uid = make_kuid(current_user_ns(), uid);
3452 if (!uid_valid(sbinfo->uid))
3453 goto bad_val;
3454 } else if (!strcmp(this_char,"gid")) {
3455 if (remount)
3456 continue;
3457 gid = simple_strtoul(value, &rest, 0);
3458 if (*rest)
3459 goto bad_val;
3460 sbinfo->gid = make_kgid(current_user_ns(), gid);
3461 if (!gid_valid(sbinfo->gid))
3462 goto bad_val;
3463 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3464 } else if (!strcmp(this_char, "huge")) {
3465 int huge;
3466 huge = shmem_parse_huge(value);
3467 if (huge < 0)
3468 goto bad_val;
3469 if (!has_transparent_hugepage() &&
3470 huge != SHMEM_HUGE_NEVER)
3471 goto bad_val;
3472 sbinfo->huge = huge;
3473 #endif
3474 #ifdef CONFIG_NUMA
3475 } else if (!strcmp(this_char,"mpol")) {
3476 mpol_put(mpol);
3477 mpol = NULL;
3478 if (mpol_parse_str(value, &mpol))
3479 goto bad_val;
3480 #endif
3481 } else {
3482 pr_err("tmpfs: Bad mount option %s\n", this_char);
3483 goto error;
3484 }
3485 }
3486 sbinfo->mpol = mpol;
3487 return 0;
3488
3489 bad_val:
3490 pr_err("tmpfs: Bad value '%s' for mount option '%s'\n",
3491 value, this_char);
3492 error:
3493 mpol_put(mpol);
3494 return 1;
3495
3496 }
3497
3498 static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
3499 {
3500 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3501 struct shmem_sb_info config = *sbinfo;
3502 unsigned long inodes;
3503 int error = -EINVAL;
3504
3505 config.mpol = NULL;
3506 if (shmem_parse_options(data, &config, true))
3507 return error;
3508
3509 spin_lock(&sbinfo->stat_lock);
3510 inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3511 if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
3512 goto out;
3513 if (config.max_inodes < inodes)
3514 goto out;
3515 /*
3516 * Those tests disallow limited->unlimited while any are in use;
3517 * but we must separately disallow unlimited->limited, because
3518 * in that case we have no record of how much is already in use.
3519 */
3520 if (config.max_blocks && !sbinfo->max_blocks)
3521 goto out;
3522 if (config.max_inodes && !sbinfo->max_inodes)
3523 goto out;
3524
3525 error = 0;
3526 sbinfo->huge = config.huge;
3527 sbinfo->max_blocks = config.max_blocks;
3528 sbinfo->max_inodes = config.max_inodes;
3529 sbinfo->free_inodes = config.max_inodes - inodes;
3530
3531 /*
3532 * Preserve previous mempolicy unless mpol remount option was specified.
3533 */
3534 if (config.mpol) {
3535 mpol_put(sbinfo->mpol);
3536 sbinfo->mpol = config.mpol; /* transfers initial ref */
3537 }
3538 out:
3539 spin_unlock(&sbinfo->stat_lock);
3540 return error;
3541 }
3542
3543 static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3544 {
3545 struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
3546
3547 if (sbinfo->max_blocks != shmem_default_max_blocks())
3548 seq_printf(seq, ",size=%luk",
3549 sbinfo->max_blocks << (PAGE_SHIFT - 10));
3550 if (sbinfo->max_inodes != shmem_default_max_inodes())
3551 seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3552 if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
3553 seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3554 if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3555 seq_printf(seq, ",uid=%u",
3556 from_kuid_munged(&init_user_ns, sbinfo->uid));
3557 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3558 seq_printf(seq, ",gid=%u",
3559 from_kgid_munged(&init_user_ns, sbinfo->gid));
3560 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3561 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3562 if (sbinfo->huge)
3563 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3564 #endif
3565 shmem_show_mpol(seq, sbinfo->mpol);
3566 return 0;
3567 }
3568
3569 #define MFD_NAME_PREFIX "memfd:"
3570 #define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
3571 #define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
3572
3573 #define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
3574
3575 SYSCALL_DEFINE2(memfd_create,
3576 const char __user *, uname,
3577 unsigned int, flags)
3578 {
3579 struct shmem_inode_info *info;
3580 struct file *file;
3581 int fd, error;
3582 char *name;
3583 long len;
3584
3585 if (flags & ~(unsigned int)MFD_ALL_FLAGS)
3586 return -EINVAL;
3587
3588 /* length includes terminating zero */
3589 len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
3590 if (len <= 0)
3591 return -EFAULT;
3592 if (len > MFD_NAME_MAX_LEN + 1)
3593 return -EINVAL;
3594
3595 name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
3596 if (!name)
3597 return -ENOMEM;
3598
3599 strcpy(name, MFD_NAME_PREFIX);
3600 if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
3601 error = -EFAULT;
3602 goto err_name;
3603 }
3604
3605 /* terminating-zero may have changed after strnlen_user() returned */
3606 if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
3607 error = -EFAULT;
3608 goto err_name;
3609 }
3610
3611 fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
3612 if (fd < 0) {
3613 error = fd;
3614 goto err_name;
3615 }
3616
3617 file = shmem_file_setup(name, 0, VM_NORESERVE);
3618 if (IS_ERR(file)) {
3619 error = PTR_ERR(file);
3620 goto err_fd;
3621 }
3622 info = SHMEM_I(file_inode(file));
3623 file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
3624 file->f_flags |= O_RDWR | O_LARGEFILE;
3625 if (flags & MFD_ALLOW_SEALING)
3626 info->seals &= ~F_SEAL_SEAL;
3627
3628 fd_install(fd, file);
3629 kfree(name);
3630 return fd;
3631
3632 err_fd:
3633 put_unused_fd(fd);
3634 err_name:
3635 kfree(name);
3636 return error;
3637 }
3638
3639 #endif /* CONFIG_TMPFS */
3640
3641 static void shmem_put_super(struct super_block *sb)
3642 {
3643 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3644
3645 percpu_counter_destroy(&sbinfo->used_blocks);
3646 mpol_put(sbinfo->mpol);
3647 kfree(sbinfo);
3648 sb->s_fs_info = NULL;
3649 }
3650
3651 int shmem_fill_super(struct super_block *sb, void *data, int silent)
3652 {
3653 struct inode *inode;
3654 struct shmem_sb_info *sbinfo;
3655 int err = -ENOMEM;
3656
3657 /* Round up to L1_CACHE_BYTES to resist false sharing */
3658 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3659 L1_CACHE_BYTES), GFP_KERNEL);
3660 if (!sbinfo)
3661 return -ENOMEM;
3662
3663 sbinfo->mode = S_IRWXUGO | S_ISVTX;
3664 sbinfo->uid = current_fsuid();
3665 sbinfo->gid = current_fsgid();
3666 sb->s_fs_info = sbinfo;
3667
3668 #ifdef CONFIG_TMPFS
3669 /*
3670 * Per default we only allow half of the physical ram per
3671 * tmpfs instance, limiting inodes to one per page of lowmem;
3672 * but the internal instance is left unlimited.
3673 */
3674 if (!(sb->s_flags & MS_KERNMOUNT)) {
3675 sbinfo->max_blocks = shmem_default_max_blocks();
3676 sbinfo->max_inodes = shmem_default_max_inodes();
3677 if (shmem_parse_options(data, sbinfo, false)) {
3678 err = -EINVAL;
3679 goto failed;
3680 }
3681 } else {
3682 sb->s_flags |= MS_NOUSER;
3683 }
3684 sb->s_export_op = &shmem_export_ops;
3685 sb->s_flags |= MS_NOSEC;
3686 #else
3687 sb->s_flags |= MS_NOUSER;
3688 #endif
3689
3690 spin_lock_init(&sbinfo->stat_lock);
3691 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3692 goto failed;
3693 sbinfo->free_inodes = sbinfo->max_inodes;
3694 spin_lock_init(&sbinfo->shrinklist_lock);
3695 INIT_LIST_HEAD(&sbinfo->shrinklist);
3696
3697 sb->s_maxbytes = MAX_LFS_FILESIZE;
3698 sb->s_blocksize = PAGE_SIZE;
3699 sb->s_blocksize_bits = PAGE_SHIFT;
3700 sb->s_magic = TMPFS_MAGIC;
3701 sb->s_op = &shmem_ops;
3702 sb->s_time_gran = 1;
3703 #ifdef CONFIG_TMPFS_XATTR
3704 sb->s_xattr = shmem_xattr_handlers;
3705 #endif
3706 #ifdef CONFIG_TMPFS_POSIX_ACL
3707 sb->s_flags |= MS_POSIXACL;
3708 #endif
3709
3710 inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3711 if (!inode)
3712 goto failed;
3713 inode->i_uid = sbinfo->uid;
3714 inode->i_gid = sbinfo->gid;
3715 sb->s_root = d_make_root(inode);
3716 if (!sb->s_root)
3717 goto failed;
3718 return 0;
3719
3720 failed:
3721 shmem_put_super(sb);
3722 return err;
3723 }
3724
3725 static struct kmem_cache *shmem_inode_cachep;
3726
3727 static struct inode *shmem_alloc_inode(struct super_block *sb)
3728 {
3729 struct shmem_inode_info *info;
3730 info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
3731 if (!info)
3732 return NULL;
3733 return &info->vfs_inode;
3734 }
3735
3736 static void shmem_destroy_callback(struct rcu_head *head)
3737 {
3738 struct inode *inode = container_of(head, struct inode, i_rcu);
3739 if (S_ISLNK(inode->i_mode))
3740 kfree(inode->i_link);
3741 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3742 }
3743
3744 static void shmem_destroy_inode(struct inode *inode)
3745 {
3746 if (S_ISREG(inode->i_mode))
3747 mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3748 call_rcu(&inode->i_rcu, shmem_destroy_callback);
3749 }
3750
3751 static void shmem_init_inode(void *foo)
3752 {
3753 struct shmem_inode_info *info = foo;
3754 inode_init_once(&info->vfs_inode);
3755 }
3756
3757 static int shmem_init_inodecache(void)
3758 {
3759 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3760 sizeof(struct shmem_inode_info),
3761 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3762 return 0;
3763 }
3764
3765 static void shmem_destroy_inodecache(void)
3766 {
3767 kmem_cache_destroy(shmem_inode_cachep);
3768 }
3769
3770 static const struct address_space_operations shmem_aops = {
3771 .writepage = shmem_writepage,
3772 .set_page_dirty = __set_page_dirty_no_writeback,
3773 #ifdef CONFIG_TMPFS
3774 .write_begin = shmem_write_begin,
3775 .write_end = shmem_write_end,
3776 #endif
3777 #ifdef CONFIG_MIGRATION
3778 .migratepage = migrate_page,
3779 #endif
3780 .error_remove_page = generic_error_remove_page,
3781 };
3782
3783 static const struct file_operations shmem_file_operations = {
3784 .mmap = shmem_mmap,
3785 .get_unmapped_area = shmem_get_unmapped_area,
3786 #ifdef CONFIG_TMPFS
3787 .llseek = shmem_file_llseek,
3788 .read_iter = shmem_file_read_iter,
3789 .write_iter = generic_file_write_iter,
3790 .fsync = noop_fsync,
3791 .splice_read = shmem_file_splice_read,
3792 .splice_write = iter_file_splice_write,
3793 .fallocate = shmem_fallocate,
3794 #endif
3795 };
3796
3797 static const struct inode_operations shmem_inode_operations = {
3798 .getattr = shmem_getattr,
3799 .setattr = shmem_setattr,
3800 #ifdef CONFIG_TMPFS_XATTR
3801 .setxattr = generic_setxattr,
3802 .getxattr = generic_getxattr,
3803 .listxattr = shmem_listxattr,
3804 .removexattr = generic_removexattr,
3805 .set_acl = simple_set_acl,
3806 #endif
3807 };
3808
3809 static const struct inode_operations shmem_dir_inode_operations = {
3810 #ifdef CONFIG_TMPFS
3811 .create = shmem_create,
3812 .lookup = simple_lookup,
3813 .link = shmem_link,
3814 .unlink = shmem_unlink,
3815 .symlink = shmem_symlink,
3816 .mkdir = shmem_mkdir,
3817 .rmdir = shmem_rmdir,
3818 .mknod = shmem_mknod,
3819 .rename2 = shmem_rename2,
3820 .tmpfile = shmem_tmpfile,
3821 #endif
3822 #ifdef CONFIG_TMPFS_XATTR
3823 .setxattr = generic_setxattr,
3824 .getxattr = generic_getxattr,
3825 .listxattr = shmem_listxattr,
3826 .removexattr = generic_removexattr,
3827 #endif
3828 #ifdef CONFIG_TMPFS_POSIX_ACL
3829 .setattr = shmem_setattr,
3830 .set_acl = simple_set_acl,
3831 #endif
3832 };
3833
3834 static const struct inode_operations shmem_special_inode_operations = {
3835 #ifdef CONFIG_TMPFS_XATTR
3836 .setxattr = generic_setxattr,
3837 .getxattr = generic_getxattr,
3838 .listxattr = shmem_listxattr,
3839 .removexattr = generic_removexattr,
3840 #endif
3841 #ifdef CONFIG_TMPFS_POSIX_ACL
3842 .setattr = shmem_setattr,
3843 .set_acl = simple_set_acl,
3844 #endif
3845 };
3846
3847 static const struct super_operations shmem_ops = {
3848 .alloc_inode = shmem_alloc_inode,
3849 .destroy_inode = shmem_destroy_inode,
3850 #ifdef CONFIG_TMPFS
3851 .statfs = shmem_statfs,
3852 .remount_fs = shmem_remount_fs,
3853 .show_options = shmem_show_options,
3854 #endif
3855 .evict_inode = shmem_evict_inode,
3856 .drop_inode = generic_delete_inode,
3857 .put_super = shmem_put_super,
3858 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3859 .nr_cached_objects = shmem_unused_huge_count,
3860 .free_cached_objects = shmem_unused_huge_scan,
3861 #endif
3862 };
3863
3864 static const struct vm_operations_struct shmem_vm_ops = {
3865 .fault = shmem_fault,
3866 .map_pages = filemap_map_pages,
3867 #ifdef CONFIG_NUMA
3868 .set_policy = shmem_set_policy,
3869 .get_policy = shmem_get_policy,
3870 #endif
3871 };
3872
3873 static struct dentry *shmem_mount(struct file_system_type *fs_type,
3874 int flags, const char *dev_name, void *data)
3875 {
3876 return mount_nodev(fs_type, flags, data, shmem_fill_super);
3877 }
3878
3879 static struct file_system_type shmem_fs_type = {
3880 .owner = THIS_MODULE,
3881 .name = "tmpfs",
3882 .mount = shmem_mount,
3883 .kill_sb = kill_litter_super,
3884 .fs_flags = FS_USERNS_MOUNT,
3885 };
3886
3887 int __init shmem_init(void)
3888 {
3889 int error;
3890
3891 /* If rootfs called this, don't re-init */
3892 if (shmem_inode_cachep)
3893 return 0;
3894
3895 error = shmem_init_inodecache();
3896 if (error)
3897 goto out3;
3898
3899 error = register_filesystem(&shmem_fs_type);
3900 if (error) {
3901 pr_err("Could not register tmpfs\n");
3902 goto out2;
3903 }
3904
3905 shm_mnt = kern_mount(&shmem_fs_type);
3906 if (IS_ERR(shm_mnt)) {
3907 error = PTR_ERR(shm_mnt);
3908 pr_err("Could not kern_mount tmpfs\n");
3909 goto out1;
3910 }
3911
3912 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3913 if (has_transparent_hugepage() && shmem_huge < SHMEM_HUGE_DENY)
3914 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3915 else
3916 shmem_huge = 0; /* just in case it was patched */
3917 #endif
3918 return 0;
3919
3920 out1:
3921 unregister_filesystem(&shmem_fs_type);
3922 out2:
3923 shmem_destroy_inodecache();
3924 out3:
3925 shm_mnt = ERR_PTR(error);
3926 return error;
3927 }
3928
3929 #if defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && defined(CONFIG_SYSFS)
3930 static ssize_t shmem_enabled_show(struct kobject *kobj,
3931 struct kobj_attribute *attr, char *buf)
3932 {
3933 int values[] = {
3934 SHMEM_HUGE_ALWAYS,
3935 SHMEM_HUGE_WITHIN_SIZE,
3936 SHMEM_HUGE_ADVISE,
3937 SHMEM_HUGE_NEVER,
3938 SHMEM_HUGE_DENY,
3939 SHMEM_HUGE_FORCE,
3940 };
3941 int i, count;
3942
3943 for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
3944 const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
3945
3946 count += sprintf(buf + count, fmt,
3947 shmem_format_huge(values[i]));
3948 }
3949 buf[count - 1] = '\n';
3950 return count;
3951 }
3952
3953 static ssize_t shmem_enabled_store(struct kobject *kobj,
3954 struct kobj_attribute *attr, const char *buf, size_t count)
3955 {
3956 char tmp[16];
3957 int huge;
3958
3959 if (count + 1 > sizeof(tmp))
3960 return -EINVAL;
3961 memcpy(tmp, buf, count);
3962 tmp[count] = '\0';
3963 if (count && tmp[count - 1] == '\n')
3964 tmp[count - 1] = '\0';
3965
3966 huge = shmem_parse_huge(tmp);
3967 if (huge == -EINVAL)
3968 return -EINVAL;
3969 if (!has_transparent_hugepage() &&
3970 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
3971 return -EINVAL;
3972
3973 shmem_huge = huge;
3974 if (shmem_huge < SHMEM_HUGE_DENY)
3975 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
3976 return count;
3977 }
3978
3979 struct kobj_attribute shmem_enabled_attr =
3980 __ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
3981 #endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE && CONFIG_SYSFS */
3982
3983 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3984 bool shmem_huge_enabled(struct vm_area_struct *vma)
3985 {
3986 struct inode *inode = file_inode(vma->vm_file);
3987 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
3988 loff_t i_size;
3989 pgoff_t off;
3990
3991 if (shmem_huge == SHMEM_HUGE_FORCE)
3992 return true;
3993 if (shmem_huge == SHMEM_HUGE_DENY)
3994 return false;
3995 switch (sbinfo->huge) {
3996 case SHMEM_HUGE_NEVER:
3997 return false;
3998 case SHMEM_HUGE_ALWAYS:
3999 return true;
4000 case SHMEM_HUGE_WITHIN_SIZE:
4001 off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
4002 i_size = round_up(i_size_read(inode), PAGE_SIZE);
4003 if (i_size >= HPAGE_PMD_SIZE &&
4004 i_size >> PAGE_SHIFT >= off)
4005 return true;
4006 case SHMEM_HUGE_ADVISE:
4007 /* TODO: implement fadvise() hints */
4008 return (vma->vm_flags & VM_HUGEPAGE);
4009 default:
4010 VM_BUG_ON(1);
4011 return false;
4012 }
4013 }
4014 #endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
4015
4016 #else /* !CONFIG_SHMEM */
4017
4018 /*
4019 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4020 *
4021 * This is intended for small system where the benefits of the full
4022 * shmem code (swap-backed and resource-limited) are outweighed by
4023 * their complexity. On systems without swap this code should be
4024 * effectively equivalent, but much lighter weight.
4025 */
4026
4027 static struct file_system_type shmem_fs_type = {
4028 .name = "tmpfs",
4029 .mount = ramfs_mount,
4030 .kill_sb = kill_litter_super,
4031 .fs_flags = FS_USERNS_MOUNT,
4032 };
4033
4034 int __init shmem_init(void)
4035 {
4036 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4037
4038 shm_mnt = kern_mount(&shmem_fs_type);
4039 BUG_ON(IS_ERR(shm_mnt));
4040
4041 return 0;
4042 }
4043
4044 int shmem_unuse(swp_entry_t swap, struct page *page)
4045 {
4046 return 0;
4047 }
4048
4049 int shmem_lock(struct file *file, int lock, struct user_struct *user)
4050 {
4051 return 0;
4052 }
4053
4054 void shmem_unlock_mapping(struct address_space *mapping)
4055 {
4056 }
4057
4058 #ifdef CONFIG_MMU
4059 unsigned long shmem_get_unmapped_area(struct file *file,
4060 unsigned long addr, unsigned long len,
4061 unsigned long pgoff, unsigned long flags)
4062 {
4063 return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4064 }
4065 #endif
4066
4067 void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4068 {
4069 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4070 }
4071 EXPORT_SYMBOL_GPL(shmem_truncate_range);
4072
4073 #define shmem_vm_ops generic_file_vm_ops
4074 #define shmem_file_operations ramfs_file_operations
4075 #define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
4076 #define shmem_acct_size(flags, size) 0
4077 #define shmem_unacct_size(flags, size) do {} while (0)
4078
4079 #endif /* CONFIG_SHMEM */
4080
4081 /* common code */
4082
4083 static struct dentry_operations anon_ops = {
4084 .d_dname = simple_dname
4085 };
4086
4087 static struct file *__shmem_file_setup(const char *name, loff_t size,
4088 unsigned long flags, unsigned int i_flags)
4089 {
4090 struct file *res;
4091 struct inode *inode;
4092 struct path path;
4093 struct super_block *sb;
4094 struct qstr this;
4095
4096 if (IS_ERR(shm_mnt))
4097 return ERR_CAST(shm_mnt);
4098
4099 if (size < 0 || size > MAX_LFS_FILESIZE)
4100 return ERR_PTR(-EINVAL);
4101
4102 if (shmem_acct_size(flags, size))
4103 return ERR_PTR(-ENOMEM);
4104
4105 res = ERR_PTR(-ENOMEM);
4106 this.name = name;
4107 this.len = strlen(name);
4108 this.hash = 0; /* will go */
4109 sb = shm_mnt->mnt_sb;
4110 path.mnt = mntget(shm_mnt);
4111 path.dentry = d_alloc_pseudo(sb, &this);
4112 if (!path.dentry)
4113 goto put_memory;
4114 d_set_d_op(path.dentry, &anon_ops);
4115
4116 res = ERR_PTR(-ENOSPC);
4117 inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
4118 if (!inode)
4119 goto put_memory;
4120
4121 inode->i_flags |= i_flags;
4122 d_instantiate(path.dentry, inode);
4123 inode->i_size = size;
4124 clear_nlink(inode); /* It is unlinked */
4125 res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
4126 if (IS_ERR(res))
4127 goto put_path;
4128
4129 res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
4130 &shmem_file_operations);
4131 if (IS_ERR(res))
4132 goto put_path;
4133
4134 return res;
4135
4136 put_memory:
4137 shmem_unacct_size(flags, size);
4138 put_path:
4139 path_put(&path);
4140 return res;
4141 }
4142
4143 /**
4144 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4145 * kernel internal. There will be NO LSM permission checks against the
4146 * underlying inode. So users of this interface must do LSM checks at a
4147 * higher layer. The users are the big_key and shm implementations. LSM
4148 * checks are provided at the key or shm level rather than the inode.
4149 * @name: name for dentry (to be seen in /proc/<pid>/maps
4150 * @size: size to be set for the file
4151 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4152 */
4153 struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4154 {
4155 return __shmem_file_setup(name, size, flags, S_PRIVATE);
4156 }
4157
4158 /**
4159 * shmem_file_setup - get an unlinked file living in tmpfs
4160 * @name: name for dentry (to be seen in /proc/<pid>/maps
4161 * @size: size to be set for the file
4162 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4163 */
4164 struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4165 {
4166 return __shmem_file_setup(name, size, flags, 0);
4167 }
4168 EXPORT_SYMBOL_GPL(shmem_file_setup);
4169
4170 /**
4171 * shmem_zero_setup - setup a shared anonymous mapping
4172 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
4173 */
4174 int shmem_zero_setup(struct vm_area_struct *vma)
4175 {
4176 struct file *file;
4177 loff_t size = vma->vm_end - vma->vm_start;
4178
4179 /*
4180 * Cloning a new file under mmap_sem leads to a lock ordering conflict
4181 * between XFS directory reading and selinux: since this file is only
4182 * accessible to the user through its mapping, use S_PRIVATE flag to
4183 * bypass file security, in the same way as shmem_kernel_file_setup().
4184 */
4185 file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
4186 if (IS_ERR(file))
4187 return PTR_ERR(file);
4188
4189 if (vma->vm_file)
4190 fput(vma->vm_file);
4191 vma->vm_file = file;
4192 vma->vm_ops = &shmem_vm_ops;
4193
4194 if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
4195 ((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
4196 (vma->vm_end & HPAGE_PMD_MASK)) {
4197 khugepaged_enter(vma, vma->vm_flags);
4198 }
4199
4200 return 0;
4201 }
4202
4203 /**
4204 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4205 * @mapping: the page's address_space
4206 * @index: the page index
4207 * @gfp: the page allocator flags to use if allocating
4208 *
4209 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4210 * with any new page allocations done using the specified allocation flags.
4211 * But read_cache_page_gfp() uses the ->readpage() method: which does not
4212 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4213 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4214 *
4215 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4216 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4217 */
4218 struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4219 pgoff_t index, gfp_t gfp)
4220 {
4221 #ifdef CONFIG_SHMEM
4222 struct inode *inode = mapping->host;
4223 struct page *page;
4224 int error;
4225
4226 BUG_ON(mapping->a_ops != &shmem_aops);
4227 error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4228 gfp, NULL, NULL);
4229 if (error)
4230 page = ERR_PTR(error);
4231 else
4232 unlock_page(page);
4233 return page;
4234 #else
4235 /*
4236 * The tiny !SHMEM case uses ramfs without swap
4237 */
4238 return read_cache_page_gfp(mapping, index, gfp);
4239 #endif
4240 }
4241 EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
4242
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