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/fileattr.h>
32#include <linux/mm.h>
33#include <linux/random.h>
34#include <linux/sched/signal.h>
35#include <linux/export.h>
36#include <linux/shmem_fs.h>
37#include <linux/swap.h>
38#include <linux/uio.h>
39#include <linux/hugetlb.h>
40#include <linux/fs_parser.h>
41#include <linux/swapfile.h>
42#include <linux/iversion.h>
43#include <linux/unicode.h>
44#include "swap.h"
45
46static struct vfsmount *shm_mnt __ro_after_init;
47
48#ifdef CONFIG_SHMEM
49/*
50 * This virtual memory filesystem is heavily based on the ramfs. It
51 * extends ramfs by the ability to use swap and honor resource limits
52 * which makes it a completely usable filesystem.
53 */
54
55#include <linux/xattr.h>
56#include <linux/exportfs.h>
57#include <linux/posix_acl.h>
58#include <linux/posix_acl_xattr.h>
59#include <linux/mman.h>
60#include <linux/string.h>
61#include <linux/slab.h>
62#include <linux/backing-dev.h>
63#include <linux/writeback.h>
64#include <linux/pagevec.h>
65#include <linux/percpu_counter.h>
66#include <linux/falloc.h>
67#include <linux/splice.h>
68#include <linux/security.h>
69#include <linux/swapops.h>
70#include <linux/mempolicy.h>
71#include <linux/namei.h>
72#include <linux/ctype.h>
73#include <linux/migrate.h>
74#include <linux/highmem.h>
75#include <linux/seq_file.h>
76#include <linux/magic.h>
77#include <linux/syscalls.h>
78#include <linux/fcntl.h>
79#include <uapi/linux/memfd.h>
80#include <linux/rmap.h>
81#include <linux/uuid.h>
82#include <linux/quotaops.h>
83#include <linux/rcupdate_wait.h>
84
85#include <linux/uaccess.h>
86
87#include "internal.h"
88
89#define VM_ACCT(size) (PAGE_ALIGN(size) >> PAGE_SHIFT)
90
91/* Pretend that each entry is of this size in directory's i_size */
92#define BOGO_DIRENT_SIZE 20
93
94/* Pretend that one inode + its dentry occupy this much memory */
95#define BOGO_INODE_SIZE 1024
96
97/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
98#define SHORT_SYMLINK_LEN 128
99
100/*
101 * shmem_fallocate communicates with shmem_fault or shmem_writeout via
102 * inode->i_private (with i_rwsem making sure that it has only one user at
103 * a time): we would prefer not to enlarge the shmem inode just for that.
104 */
105struct shmem_falloc {
106 wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
107 pgoff_t start; /* start of range currently being fallocated */
108 pgoff_t next; /* the next page offset to be fallocated */
109 pgoff_t nr_falloced; /* how many new pages have been fallocated */
110 pgoff_t nr_unswapped; /* how often writeout refused to swap out */
111};
112
113struct shmem_options {
114 unsigned long long blocks;
115 unsigned long long inodes;
116 struct mempolicy *mpol;
117 kuid_t uid;
118 kgid_t gid;
119 umode_t mode;
120 bool full_inums;
121 int huge;
122 int seen;
123 bool noswap;
124 unsigned short quota_types;
125 struct shmem_quota_limits qlimits;
126#if IS_ENABLED(CONFIG_UNICODE)
127 struct unicode_map *encoding;
128 bool strict_encoding;
129#endif
130#define SHMEM_SEEN_BLOCKS 1
131#define SHMEM_SEEN_INODES 2
132#define SHMEM_SEEN_HUGE 4
133#define SHMEM_SEEN_INUMS 8
134#define SHMEM_SEEN_NOSWAP 16
135#define SHMEM_SEEN_QUOTA 32
136};
137
138#ifdef CONFIG_TRANSPARENT_HUGEPAGE
139static unsigned long huge_shmem_orders_always __read_mostly;
140static unsigned long huge_shmem_orders_madvise __read_mostly;
141static unsigned long huge_shmem_orders_inherit __read_mostly;
142static unsigned long huge_shmem_orders_within_size __read_mostly;
143static bool shmem_orders_configured __initdata;
144#endif
145
146#ifdef CONFIG_TMPFS
147static unsigned long shmem_default_max_blocks(void)
148{
149 return totalram_pages() / 2;
150}
151
152static unsigned long shmem_default_max_inodes(void)
153{
154 unsigned long nr_pages = totalram_pages();
155
156 return min3(nr_pages - totalhigh_pages(), nr_pages / 2,
157 ULONG_MAX / BOGO_INODE_SIZE);
158}
159#endif
160
161static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
162 struct folio **foliop, enum sgp_type sgp, gfp_t gfp,
163 struct vm_area_struct *vma, vm_fault_t *fault_type);
164
165static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
166{
167 return sb->s_fs_info;
168}
169
170/*
171 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
172 * for shared memory and for shared anonymous (/dev/zero) mappings
173 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
174 * consistent with the pre-accounting of private mappings ...
175 */
176static inline int shmem_acct_size(unsigned long flags, loff_t size)
177{
178 return (flags & VM_NORESERVE) ?
179 0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
180}
181
182static inline void shmem_unacct_size(unsigned long flags, loff_t size)
183{
184 if (!(flags & VM_NORESERVE))
185 vm_unacct_memory(VM_ACCT(size));
186}
187
188static inline int shmem_reacct_size(unsigned long flags,
189 loff_t oldsize, loff_t newsize)
190{
191 if (!(flags & VM_NORESERVE)) {
192 if (VM_ACCT(newsize) > VM_ACCT(oldsize))
193 return security_vm_enough_memory_mm(current->mm,
194 VM_ACCT(newsize) - VM_ACCT(oldsize));
195 else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
196 vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
197 }
198 return 0;
199}
200
201/*
202 * ... whereas tmpfs objects are accounted incrementally as
203 * pages are allocated, in order to allow large sparse files.
204 * shmem_get_folio reports shmem_acct_blocks failure as -ENOSPC not -ENOMEM,
205 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
206 */
207static inline int shmem_acct_blocks(unsigned long flags, long pages)
208{
209 if (!(flags & VM_NORESERVE))
210 return 0;
211
212 return security_vm_enough_memory_mm(current->mm,
213 pages: pages * VM_ACCT(PAGE_SIZE));
214}
215
216static inline void shmem_unacct_blocks(unsigned long flags, long pages)
217{
218 if (flags & VM_NORESERVE)
219 vm_unacct_memory(pages: pages * VM_ACCT(PAGE_SIZE));
220}
221
222static int shmem_inode_acct_blocks(struct inode *inode, long pages)
223{
224 struct shmem_inode_info *info = SHMEM_I(inode);
225 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
226 int err = -ENOSPC;
227
228 if (shmem_acct_blocks(flags: info->flags, pages))
229 return err;
230
231 might_sleep(); /* when quotas */
232 if (sbinfo->max_blocks) {
233 if (!percpu_counter_limited_add(fbc: &sbinfo->used_blocks,
234 limit: sbinfo->max_blocks, amount: pages))
235 goto unacct;
236
237 err = dquot_alloc_block_nodirty(inode, nr: pages);
238 if (err) {
239 percpu_counter_sub(fbc: &sbinfo->used_blocks, amount: pages);
240 goto unacct;
241 }
242 } else {
243 err = dquot_alloc_block_nodirty(inode, nr: pages);
244 if (err)
245 goto unacct;
246 }
247
248 return 0;
249
250unacct:
251 shmem_unacct_blocks(flags: info->flags, pages);
252 return err;
253}
254
255static void shmem_inode_unacct_blocks(struct inode *inode, long pages)
256{
257 struct shmem_inode_info *info = SHMEM_I(inode);
258 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
259
260 might_sleep(); /* when quotas */
261 dquot_free_block_nodirty(inode, nr: pages);
262
263 if (sbinfo->max_blocks)
264 percpu_counter_sub(fbc: &sbinfo->used_blocks, amount: pages);
265 shmem_unacct_blocks(flags: info->flags, pages);
266}
267
268static const struct super_operations shmem_ops;
269static const struct address_space_operations shmem_aops;
270static const struct file_operations shmem_file_operations;
271static const struct inode_operations shmem_inode_operations;
272static const struct inode_operations shmem_dir_inode_operations;
273static const struct inode_operations shmem_special_inode_operations;
274static const struct vm_operations_struct shmem_vm_ops;
275static const struct vm_operations_struct shmem_anon_vm_ops;
276static struct file_system_type shmem_fs_type;
277
278bool shmem_mapping(const struct address_space *mapping)
279{
280 return mapping->a_ops == &shmem_aops;
281}
282EXPORT_SYMBOL_GPL(shmem_mapping);
283
284bool vma_is_anon_shmem(const struct vm_area_struct *vma)
285{
286 return vma->vm_ops == &shmem_anon_vm_ops;
287}
288
289bool vma_is_shmem(const struct vm_area_struct *vma)
290{
291 return vma_is_anon_shmem(vma) || vma->vm_ops == &shmem_vm_ops;
292}
293
294static LIST_HEAD(shmem_swaplist);
295static DEFINE_SPINLOCK(shmem_swaplist_lock);
296
297#ifdef CONFIG_TMPFS_QUOTA
298
299static int shmem_enable_quotas(struct super_block *sb,
300 unsigned short quota_types)
301{
302 int type, err = 0;
303
304 sb_dqopt(sb)->flags |= DQUOT_QUOTA_SYS_FILE | DQUOT_NOLIST_DIRTY;
305 for (type = 0; type < SHMEM_MAXQUOTAS; type++) {
306 if (!(quota_types & (1 << type)))
307 continue;
308 err = dquot_load_quota_sb(sb, type, QFMT_SHMEM,
309 DQUOT_USAGE_ENABLED |
310 DQUOT_LIMITS_ENABLED);
311 if (err)
312 goto out_err;
313 }
314 return 0;
315
316out_err:
317 pr_warn("tmpfs: failed to enable quota tracking (type=%d, err=%d)\n",
318 type, err);
319 for (type--; type >= 0; type--)
320 dquot_quota_off(sb, type);
321 return err;
322}
323
324static void shmem_disable_quotas(struct super_block *sb)
325{
326 int type;
327
328 for (type = 0; type < SHMEM_MAXQUOTAS; type++)
329 dquot_quota_off(sb, type);
330}
331
332static struct dquot __rcu **shmem_get_dquots(struct inode *inode)
333{
334 return SHMEM_I(inode)->i_dquot;
335}
336#endif /* CONFIG_TMPFS_QUOTA */
337
338/*
339 * shmem_reserve_inode() performs bookkeeping to reserve a shmem inode, and
340 * produces a novel ino for the newly allocated inode.
341 *
342 * It may also be called when making a hard link to permit the space needed by
343 * each dentry. However, in that case, no new inode number is needed since that
344 * internally draws from another pool of inode numbers (currently global
345 * get_next_ino()). This case is indicated by passing NULL as inop.
346 */
347#define SHMEM_INO_BATCH 1024
348static int shmem_reserve_inode(struct super_block *sb, ino_t *inop)
349{
350 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
351 ino_t ino;
352
353 if (!(sb->s_flags & SB_KERNMOUNT)) {
354 raw_spin_lock(&sbinfo->stat_lock);
355 if (sbinfo->max_inodes) {
356 if (sbinfo->free_ispace < BOGO_INODE_SIZE) {
357 raw_spin_unlock(&sbinfo->stat_lock);
358 return -ENOSPC;
359 }
360 sbinfo->free_ispace -= BOGO_INODE_SIZE;
361 }
362 if (inop) {
363 ino = sbinfo->next_ino++;
364 if (unlikely(is_zero_ino(ino)))
365 ino = sbinfo->next_ino++;
366 if (unlikely(!sbinfo->full_inums &&
367 ino > UINT_MAX)) {
368 /*
369 * Emulate get_next_ino uint wraparound for
370 * compatibility
371 */
372 if (IS_ENABLED(CONFIG_64BIT))
373 pr_warn("%s: inode number overflow on device %d, consider using inode64 mount option\n",
374 __func__, MINOR(sb->s_dev));
375 sbinfo->next_ino = 1;
376 ino = sbinfo->next_ino++;
377 }
378 *inop = ino;
379 }
380 raw_spin_unlock(&sbinfo->stat_lock);
381 } else if (inop) {
382 /*
383 * __shmem_file_setup, one of our callers, is lock-free: it
384 * doesn't hold stat_lock in shmem_reserve_inode since
385 * max_inodes is always 0, and is called from potentially
386 * unknown contexts. As such, use a per-cpu batched allocator
387 * which doesn't require the per-sb stat_lock unless we are at
388 * the batch boundary.
389 *
390 * We don't need to worry about inode{32,64} since SB_KERNMOUNT
391 * shmem mounts are not exposed to userspace, so we don't need
392 * to worry about things like glibc compatibility.
393 */
394 ino_t *next_ino;
395
396 next_ino = per_cpu_ptr(sbinfo->ino_batch, get_cpu());
397 ino = *next_ino;
398 if (unlikely(ino % SHMEM_INO_BATCH == 0)) {
399 raw_spin_lock(&sbinfo->stat_lock);
400 ino = sbinfo->next_ino;
401 sbinfo->next_ino += SHMEM_INO_BATCH;
402 raw_spin_unlock(&sbinfo->stat_lock);
403 if (unlikely(is_zero_ino(ino)))
404 ino++;
405 }
406 *inop = ino;
407 *next_ino = ++ino;
408 put_cpu();
409 }
410
411 return 0;
412}
413
414static void shmem_free_inode(struct super_block *sb, size_t freed_ispace)
415{
416 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
417 if (sbinfo->max_inodes) {
418 raw_spin_lock(&sbinfo->stat_lock);
419 sbinfo->free_ispace += BOGO_INODE_SIZE + freed_ispace;
420 raw_spin_unlock(&sbinfo->stat_lock);
421 }
422}
423
424/**
425 * shmem_recalc_inode - recalculate the block usage of an inode
426 * @inode: inode to recalc
427 * @alloced: the change in number of pages allocated to inode
428 * @swapped: the change in number of pages swapped from inode
429 *
430 * We have to calculate the free blocks since the mm can drop
431 * undirtied hole pages behind our back.
432 *
433 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped
434 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
435 *
436 * Return: true if swapped was incremented from 0, for shmem_writeout().
437 */
438static bool shmem_recalc_inode(struct inode *inode, long alloced, long swapped)
439{
440 struct shmem_inode_info *info = SHMEM_I(inode);
441 bool first_swapped = false;
442 long freed;
443
444 spin_lock(lock: &info->lock);
445 info->alloced += alloced;
446 info->swapped += swapped;
447 freed = info->alloced - info->swapped -
448 READ_ONCE(inode->i_mapping->nrpages);
449 /*
450 * Special case: whereas normally shmem_recalc_inode() is called
451 * after i_mapping->nrpages has already been adjusted (up or down),
452 * shmem_writeout() has to raise swapped before nrpages is lowered -
453 * to stop a racing shmem_recalc_inode() from thinking that a page has
454 * been freed. Compensate here, to avoid the need for a followup call.
455 */
456 if (swapped > 0) {
457 if (info->swapped == swapped)
458 first_swapped = true;
459 freed += swapped;
460 }
461 if (freed > 0)
462 info->alloced -= freed;
463 spin_unlock(lock: &info->lock);
464
465 /* The quota case may block */
466 if (freed > 0)
467 shmem_inode_unacct_blocks(inode, pages: freed);
468 return first_swapped;
469}
470
471bool shmem_charge(struct inode *inode, long pages)
472{
473 struct address_space *mapping = inode->i_mapping;
474
475 if (shmem_inode_acct_blocks(inode, pages))
476 return false;
477
478 /* nrpages adjustment first, then shmem_recalc_inode() when balanced */
479 xa_lock_irq(&mapping->i_pages);
480 mapping->nrpages += pages;
481 xa_unlock_irq(&mapping->i_pages);
482
483 shmem_recalc_inode(inode, alloced: pages, swapped: 0);
484 return true;
485}
486
487void shmem_uncharge(struct inode *inode, long pages)
488{
489 /* pages argument is currently unused: keep it to help debugging */
490 /* nrpages adjustment done by __filemap_remove_folio() or caller */
491
492 shmem_recalc_inode(inode, alloced: 0, swapped: 0);
493}
494
495/*
496 * Replace item expected in xarray by a new item, while holding xa_lock.
497 */
498static int shmem_replace_entry(struct address_space *mapping,
499 pgoff_t index, void *expected, void *replacement)
500{
501 XA_STATE(xas, &mapping->i_pages, index);
502 void *item;
503
504 VM_BUG_ON(!expected);
505 VM_BUG_ON(!replacement);
506 item = xas_load(&xas);
507 if (item != expected)
508 return -ENOENT;
509 xas_store(&xas, entry: replacement);
510 return 0;
511}
512
513/*
514 * Sometimes, before we decide whether to proceed or to fail, we must check
515 * that an entry was not already brought back or split by a racing thread.
516 *
517 * Checking folio is not enough: by the time a swapcache folio is locked, it
518 * might be reused, and again be swapcache, using the same swap as before.
519 * Returns the swap entry's order if it still presents, else returns -1.
520 */
521static int shmem_confirm_swap(struct address_space *mapping, pgoff_t index,
522 swp_entry_t swap)
523{
524 XA_STATE(xas, &mapping->i_pages, index);
525 int ret = -1;
526 void *entry;
527
528 rcu_read_lock();
529 do {
530 entry = xas_load(&xas);
531 if (entry == swp_to_radix_entry(entry: swap))
532 ret = xas_get_order(xas: &xas);
533 } while (xas_retry(xas: &xas, entry));
534 rcu_read_unlock();
535 return ret;
536}
537
538/*
539 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
540 *
541 * SHMEM_HUGE_NEVER:
542 * disables huge pages for the mount;
543 * SHMEM_HUGE_ALWAYS:
544 * enables huge pages for the mount;
545 * SHMEM_HUGE_WITHIN_SIZE:
546 * only allocate huge pages if the page will be fully within i_size,
547 * also respect madvise() hints;
548 * SHMEM_HUGE_ADVISE:
549 * only allocate huge pages if requested with madvise();
550 */
551
552#define SHMEM_HUGE_NEVER 0
553#define SHMEM_HUGE_ALWAYS 1
554#define SHMEM_HUGE_WITHIN_SIZE 2
555#define SHMEM_HUGE_ADVISE 3
556
557/*
558 * Special values.
559 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
560 *
561 * SHMEM_HUGE_DENY:
562 * disables huge on shm_mnt and all mounts, for emergency use;
563 * SHMEM_HUGE_FORCE:
564 * enables huge on shm_mnt and all mounts, w/o needing option, for testing;
565 *
566 */
567#define SHMEM_HUGE_DENY (-1)
568#define SHMEM_HUGE_FORCE (-2)
569
570#ifdef CONFIG_TRANSPARENT_HUGEPAGE
571/* ifdef here to avoid bloating shmem.o when not necessary */
572
573static int shmem_huge __read_mostly = SHMEM_HUGE_NEVER;
574static int tmpfs_huge __read_mostly = SHMEM_HUGE_NEVER;
575
576static unsigned int shmem_get_orders_within_size(struct inode *inode,
577 unsigned long within_size_orders, pgoff_t index,
578 loff_t write_end)
579{
580 pgoff_t aligned_index;
581 unsigned long order;
582 loff_t i_size;
583
584 order = highest_order(within_size_orders);
585 while (within_size_orders) {
586 aligned_index = round_up(index + 1, 1 << order);
587 i_size = max(write_end, i_size_read(inode));
588 i_size = round_up(i_size, PAGE_SIZE);
589 if (i_size >> PAGE_SHIFT >= aligned_index)
590 return within_size_orders;
591
592 order = next_order(&within_size_orders, order);
593 }
594
595 return 0;
596}
597
598static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
599 loff_t write_end, bool shmem_huge_force,
600 struct vm_area_struct *vma,
601 vm_flags_t vm_flags)
602{
603 unsigned int maybe_pmd_order = HPAGE_PMD_ORDER > MAX_PAGECACHE_ORDER ?
604 0 : BIT(HPAGE_PMD_ORDER);
605 unsigned long within_size_orders;
606
607 if (!S_ISREG(inode->i_mode))
608 return 0;
609 if (shmem_huge == SHMEM_HUGE_DENY)
610 return 0;
611 if (shmem_huge_force || shmem_huge == SHMEM_HUGE_FORCE)
612 return maybe_pmd_order;
613
614 /*
615 * The huge order allocation for anon shmem is controlled through
616 * the mTHP interface, so we still use PMD-sized huge order to
617 * check whether global control is enabled.
618 *
619 * For tmpfs mmap()'s huge order, we still use PMD-sized order to
620 * allocate huge pages due to lack of a write size hint.
621 *
622 * For tmpfs with 'huge=always' or 'huge=within_size' mount option,
623 * we will always try PMD-sized order first. If that failed, it will
624 * fall back to small large folios.
625 */
626 switch (SHMEM_SB(inode->i_sb)->huge) {
627 case SHMEM_HUGE_ALWAYS:
628 if (vma)
629 return maybe_pmd_order;
630
631 return THP_ORDERS_ALL_FILE_DEFAULT;
632 case SHMEM_HUGE_WITHIN_SIZE:
633 if (vma)
634 within_size_orders = maybe_pmd_order;
635 else
636 within_size_orders = THP_ORDERS_ALL_FILE_DEFAULT;
637
638 within_size_orders = shmem_get_orders_within_size(inode, within_size_orders,
639 index, write_end);
640 if (within_size_orders > 0)
641 return within_size_orders;
642
643 fallthrough;
644 case SHMEM_HUGE_ADVISE:
645 if (vm_flags & VM_HUGEPAGE)
646 return maybe_pmd_order;
647 fallthrough;
648 default:
649 return 0;
650 }
651}
652
653static int shmem_parse_huge(const char *str)
654{
655 int huge;
656
657 if (!str)
658 return -EINVAL;
659
660 if (!strcmp(str, "never"))
661 huge = SHMEM_HUGE_NEVER;
662 else if (!strcmp(str, "always"))
663 huge = SHMEM_HUGE_ALWAYS;
664 else if (!strcmp(str, "within_size"))
665 huge = SHMEM_HUGE_WITHIN_SIZE;
666 else if (!strcmp(str, "advise"))
667 huge = SHMEM_HUGE_ADVISE;
668 else if (!strcmp(str, "deny"))
669 huge = SHMEM_HUGE_DENY;
670 else if (!strcmp(str, "force"))
671 huge = SHMEM_HUGE_FORCE;
672 else
673 return -EINVAL;
674
675 if (!has_transparent_hugepage() &&
676 huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
677 return -EINVAL;
678
679 /* Do not override huge allocation policy with non-PMD sized mTHP */
680 if (huge == SHMEM_HUGE_FORCE &&
681 huge_shmem_orders_inherit != BIT(HPAGE_PMD_ORDER))
682 return -EINVAL;
683
684 return huge;
685}
686
687#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
688static const char *shmem_format_huge(int huge)
689{
690 switch (huge) {
691 case SHMEM_HUGE_NEVER:
692 return "never";
693 case SHMEM_HUGE_ALWAYS:
694 return "always";
695 case SHMEM_HUGE_WITHIN_SIZE:
696 return "within_size";
697 case SHMEM_HUGE_ADVISE:
698 return "advise";
699 case SHMEM_HUGE_DENY:
700 return "deny";
701 case SHMEM_HUGE_FORCE:
702 return "force";
703 default:
704 VM_BUG_ON(1);
705 return "bad_val";
706 }
707}
708#endif
709
710static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
711 struct shrink_control *sc, unsigned long nr_to_free)
712{
713 LIST_HEAD(list), *pos, *next;
714 struct inode *inode;
715 struct shmem_inode_info *info;
716 struct folio *folio;
717 unsigned long batch = sc ? sc->nr_to_scan : 128;
718 unsigned long split = 0, freed = 0;
719
720 if (list_empty(&sbinfo->shrinklist))
721 return SHRINK_STOP;
722
723 spin_lock(&sbinfo->shrinklist_lock);
724 list_for_each_safe(pos, next, &sbinfo->shrinklist) {
725 info = list_entry(pos, struct shmem_inode_info, shrinklist);
726
727 /* pin the inode */
728 inode = igrab(&info->vfs_inode);
729
730 /* inode is about to be evicted */
731 if (!inode) {
732 list_del_init(&info->shrinklist);
733 goto next;
734 }
735
736 list_move(&info->shrinklist, &list);
737next:
738 sbinfo->shrinklist_len--;
739 if (!--batch)
740 break;
741 }
742 spin_unlock(&sbinfo->shrinklist_lock);
743
744 list_for_each_safe(pos, next, &list) {
745 pgoff_t next, end;
746 loff_t i_size;
747 int ret;
748
749 info = list_entry(pos, struct shmem_inode_info, shrinklist);
750 inode = &info->vfs_inode;
751
752 if (nr_to_free && freed >= nr_to_free)
753 goto move_back;
754
755 i_size = i_size_read(inode);
756 folio = filemap_get_entry(inode->i_mapping, i_size / PAGE_SIZE);
757 if (!folio || xa_is_value(folio))
758 goto drop;
759
760 /* No large folio at the end of the file: nothing to split */
761 if (!folio_test_large(folio)) {
762 folio_put(folio);
763 goto drop;
764 }
765
766 /* Check if there is anything to gain from splitting */
767 next = folio_next_index(folio);
768 end = shmem_fallocend(inode, DIV_ROUND_UP(i_size, PAGE_SIZE));
769 if (end <= folio->index || end >= next) {
770 folio_put(folio);
771 goto drop;
772 }
773
774 /*
775 * Move the inode on the list back to shrinklist if we failed
776 * to lock the page at this time.
777 *
778 * Waiting for the lock may lead to deadlock in the
779 * reclaim path.
780 */
781 if (!folio_trylock(folio)) {
782 folio_put(folio);
783 goto move_back;
784 }
785
786 ret = split_folio(folio);
787 folio_unlock(folio);
788 folio_put(folio);
789
790 /* If split failed move the inode on the list back to shrinklist */
791 if (ret)
792 goto move_back;
793
794 freed += next - end;
795 split++;
796drop:
797 list_del_init(&info->shrinklist);
798 goto put;
799move_back:
800 /*
801 * Make sure the inode is either on the global list or deleted
802 * from any local list before iput() since it could be deleted
803 * in another thread once we put the inode (then the local list
804 * is corrupted).
805 */
806 spin_lock(&sbinfo->shrinklist_lock);
807 list_move(&info->shrinklist, &sbinfo->shrinklist);
808 sbinfo->shrinklist_len++;
809 spin_unlock(&sbinfo->shrinklist_lock);
810put:
811 iput(inode);
812 }
813
814 return split;
815}
816
817static long shmem_unused_huge_scan(struct super_block *sb,
818 struct shrink_control *sc)
819{
820 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
821
822 if (!READ_ONCE(sbinfo->shrinklist_len))
823 return SHRINK_STOP;
824
825 return shmem_unused_huge_shrink(sbinfo, sc, 0);
826}
827
828static long shmem_unused_huge_count(struct super_block *sb,
829 struct shrink_control *sc)
830{
831 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
832 return READ_ONCE(sbinfo->shrinklist_len);
833}
834#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
835
836#define shmem_huge SHMEM_HUGE_DENY
837
838static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
839 struct shrink_control *sc, unsigned long nr_to_free)
840{
841 return 0;
842}
843
844static unsigned int shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
845 loff_t write_end, bool shmem_huge_force,
846 struct vm_area_struct *vma,
847 vm_flags_t vm_flags)
848{
849 return 0;
850}
851#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
852
853static void shmem_update_stats(struct folio *folio, int nr_pages)
854{
855 if (folio_test_pmd_mappable(folio))
856 __lruvec_stat_mod_folio(folio, idx: NR_SHMEM_THPS, val: nr_pages);
857 __lruvec_stat_mod_folio(folio, idx: NR_FILE_PAGES, val: nr_pages);
858 __lruvec_stat_mod_folio(folio, idx: NR_SHMEM, val: nr_pages);
859}
860
861/*
862 * Somewhat like filemap_add_folio, but error if expected item has gone.
863 */
864static int shmem_add_to_page_cache(struct folio *folio,
865 struct address_space *mapping,
866 pgoff_t index, void *expected, gfp_t gfp)
867{
868 XA_STATE_ORDER(xas, &mapping->i_pages, index, folio_order(folio));
869 unsigned long nr = folio_nr_pages(folio);
870 swp_entry_t iter, swap;
871 void *entry;
872
873 VM_BUG_ON_FOLIO(index != round_down(index, nr), folio);
874 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
875 VM_BUG_ON_FOLIO(!folio_test_swapbacked(folio), folio);
876
877 folio_ref_add(folio, nr);
878 folio->mapping = mapping;
879 folio->index = index;
880
881 gfp &= GFP_RECLAIM_MASK;
882 folio_throttle_swaprate(folio, gfp);
883 swap = radix_to_swp_entry(arg: expected);
884
885 do {
886 iter = swap;
887 xas_lock_irq(&xas);
888 xas_for_each_conflict(&xas, entry) {
889 /*
890 * The range must either be empty, or filled with
891 * expected swap entries. Shmem swap entries are never
892 * partially freed without split of both entry and
893 * folio, so there shouldn't be any holes.
894 */
895 if (!expected || entry != swp_to_radix_entry(entry: iter)) {
896 xas_set_err(xas: &xas, err: -EEXIST);
897 goto unlock;
898 }
899 iter.val += 1 << xas_get_order(xas: &xas);
900 }
901 if (expected && iter.val - nr != swap.val) {
902 xas_set_err(xas: &xas, err: -EEXIST);
903 goto unlock;
904 }
905 xas_store(&xas, entry: folio);
906 if (xas_error(xas: &xas))
907 goto unlock;
908 shmem_update_stats(folio, nr_pages: nr);
909 mapping->nrpages += nr;
910unlock:
911 xas_unlock_irq(&xas);
912 } while (xas_nomem(&xas, gfp));
913
914 if (xas_error(xas: &xas)) {
915 folio->mapping = NULL;
916 folio_ref_sub(folio, nr);
917 return xas_error(xas: &xas);
918 }
919
920 return 0;
921}
922
923/*
924 * Somewhat like filemap_remove_folio, but substitutes swap for @folio.
925 */
926static void shmem_delete_from_page_cache(struct folio *folio, void *radswap)
927{
928 struct address_space *mapping = folio->mapping;
929 long nr = folio_nr_pages(folio);
930 int error;
931
932 xa_lock_irq(&mapping->i_pages);
933 error = shmem_replace_entry(mapping, index: folio->index, expected: folio, replacement: radswap);
934 folio->mapping = NULL;
935 mapping->nrpages -= nr;
936 shmem_update_stats(folio, nr_pages: -nr);
937 xa_unlock_irq(&mapping->i_pages);
938 folio_put_refs(folio, refs: nr);
939 BUG_ON(error);
940}
941
942/*
943 * Remove swap entry from page cache, free the swap and its page cache. Returns
944 * the number of pages being freed. 0 means entry not found in XArray (0 pages
945 * being freed).
946 */
947static long shmem_free_swap(struct address_space *mapping,
948 pgoff_t index, void *radswap)
949{
950 int order = xa_get_order(&mapping->i_pages, index);
951 void *old;
952
953 old = xa_cmpxchg_irq(xa: &mapping->i_pages, index, old: radswap, NULL, gfp: 0);
954 if (old != radswap)
955 return 0;
956 free_swap_and_cache_nr(entry: radix_to_swp_entry(arg: radswap), nr: 1 << order);
957
958 return 1 << order;
959}
960
961/*
962 * Determine (in bytes) how many of the shmem object's pages mapped by the
963 * given offsets are swapped out.
964 *
965 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
966 * as long as the inode doesn't go away and racy results are not a problem.
967 */
968unsigned long shmem_partial_swap_usage(struct address_space *mapping,
969 pgoff_t start, pgoff_t end)
970{
971 XA_STATE(xas, &mapping->i_pages, start);
972 struct folio *folio;
973 unsigned long swapped = 0;
974 unsigned long max = end - 1;
975
976 rcu_read_lock();
977 xas_for_each(&xas, folio, max) {
978 if (xas_retry(xas: &xas, entry: folio))
979 continue;
980 if (xa_is_value(entry: folio))
981 swapped += 1 << xas_get_order(xas: &xas);
982 if (xas.xa_index == max)
983 break;
984 if (need_resched()) {
985 xas_pause(&xas);
986 cond_resched_rcu();
987 }
988 }
989 rcu_read_unlock();
990
991 return swapped << PAGE_SHIFT;
992}
993
994/*
995 * Determine (in bytes) how many of the shmem object's pages mapped by the
996 * given vma is swapped out.
997 *
998 * This is safe to call without i_rwsem or the i_pages lock thanks to RCU,
999 * as long as the inode doesn't go away and racy results are not a problem.
1000 */
1001unsigned long shmem_swap_usage(struct vm_area_struct *vma)
1002{
1003 struct inode *inode = file_inode(f: vma->vm_file);
1004 struct shmem_inode_info *info = SHMEM_I(inode);
1005 struct address_space *mapping = inode->i_mapping;
1006 unsigned long swapped;
1007
1008 /* Be careful as we don't hold info->lock */
1009 swapped = READ_ONCE(info->swapped);
1010
1011 /*
1012 * The easier cases are when the shmem object has nothing in swap, or
1013 * the vma maps it whole. Then we can simply use the stats that we
1014 * already track.
1015 */
1016 if (!swapped)
1017 return 0;
1018
1019 if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
1020 return swapped << PAGE_SHIFT;
1021
1022 /* Here comes the more involved part */
1023 return shmem_partial_swap_usage(mapping, start: vma->vm_pgoff,
1024 end: vma->vm_pgoff + vma_pages(vma));
1025}
1026
1027/*
1028 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
1029 */
1030void shmem_unlock_mapping(struct address_space *mapping)
1031{
1032 struct folio_batch fbatch;
1033 pgoff_t index = 0;
1034
1035 folio_batch_init(fbatch: &fbatch);
1036 /*
1037 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
1038 */
1039 while (!mapping_unevictable(mapping) &&
1040 filemap_get_folios(mapping, start: &index, end: ~0UL, fbatch: &fbatch)) {
1041 check_move_unevictable_folios(fbatch: &fbatch);
1042 folio_batch_release(fbatch: &fbatch);
1043 cond_resched();
1044 }
1045}
1046
1047static struct folio *shmem_get_partial_folio(struct inode *inode, pgoff_t index)
1048{
1049 struct folio *folio;
1050
1051 /*
1052 * At first avoid shmem_get_folio(,,,SGP_READ): that fails
1053 * beyond i_size, and reports fallocated folios as holes.
1054 */
1055 folio = filemap_get_entry(mapping: inode->i_mapping, index);
1056 if (!folio)
1057 return folio;
1058 if (!xa_is_value(entry: folio)) {
1059 folio_lock(folio);
1060 if (folio->mapping == inode->i_mapping)
1061 return folio;
1062 /* The folio has been swapped out */
1063 folio_unlock(folio);
1064 folio_put(folio);
1065 }
1066 /*
1067 * But read a folio back from swap if any of it is within i_size
1068 * (although in some cases this is just a waste of time).
1069 */
1070 folio = NULL;
1071 shmem_get_folio(inode, index, write_end: 0, foliop: &folio, sgp: SGP_READ);
1072 return folio;
1073}
1074
1075/*
1076 * Remove range of pages and swap entries from page cache, and free them.
1077 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
1078 */
1079static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
1080 bool unfalloc)
1081{
1082 struct address_space *mapping = inode->i_mapping;
1083 struct shmem_inode_info *info = SHMEM_I(inode);
1084 pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
1085 pgoff_t end = (lend + 1) >> PAGE_SHIFT;
1086 struct folio_batch fbatch;
1087 pgoff_t indices[PAGEVEC_SIZE];
1088 struct folio *folio;
1089 bool same_folio;
1090 long nr_swaps_freed = 0;
1091 pgoff_t index;
1092 int i;
1093
1094 if (lend == -1)
1095 end = -1; /* unsigned, so actually very big */
1096
1097 if (info->fallocend > start && info->fallocend <= end && !unfalloc)
1098 info->fallocend = start;
1099
1100 folio_batch_init(fbatch: &fbatch);
1101 index = start;
1102 while (index < end && find_lock_entries(mapping, start: &index, end: end - 1,
1103 fbatch: &fbatch, indices)) {
1104 for (i = 0; i < folio_batch_count(fbatch: &fbatch); i++) {
1105 folio = fbatch.folios[i];
1106
1107 if (xa_is_value(entry: folio)) {
1108 if (unfalloc)
1109 continue;
1110 nr_swaps_freed += shmem_free_swap(mapping,
1111 index: indices[i], radswap: folio);
1112 continue;
1113 }
1114
1115 if (!unfalloc || !folio_test_uptodate(folio))
1116 truncate_inode_folio(mapping, folio);
1117 folio_unlock(folio);
1118 }
1119 folio_batch_remove_exceptionals(fbatch: &fbatch);
1120 folio_batch_release(fbatch: &fbatch);
1121 cond_resched();
1122 }
1123
1124 /*
1125 * When undoing a failed fallocate, we want none of the partial folio
1126 * zeroing and splitting below, but shall want to truncate the whole
1127 * folio when !uptodate indicates that it was added by this fallocate,
1128 * even when [lstart, lend] covers only a part of the folio.
1129 */
1130 if (unfalloc)
1131 goto whole_folios;
1132
1133 same_folio = (lstart >> PAGE_SHIFT) == (lend >> PAGE_SHIFT);
1134 folio = shmem_get_partial_folio(inode, index: lstart >> PAGE_SHIFT);
1135 if (folio) {
1136 same_folio = lend < folio_pos(folio) + folio_size(folio);
1137 folio_mark_dirty(folio);
1138 if (!truncate_inode_partial_folio(folio, start: lstart, end: lend)) {
1139 start = folio_next_index(folio);
1140 if (same_folio)
1141 end = folio->index;
1142 }
1143 folio_unlock(folio);
1144 folio_put(folio);
1145 folio = NULL;
1146 }
1147
1148 if (!same_folio)
1149 folio = shmem_get_partial_folio(inode, index: lend >> PAGE_SHIFT);
1150 if (folio) {
1151 folio_mark_dirty(folio);
1152 if (!truncate_inode_partial_folio(folio, start: lstart, end: lend))
1153 end = folio->index;
1154 folio_unlock(folio);
1155 folio_put(folio);
1156 }
1157
1158whole_folios:
1159
1160 index = start;
1161 while (index < end) {
1162 cond_resched();
1163
1164 if (!find_get_entries(mapping, start: &index, end: end - 1, fbatch: &fbatch,
1165 indices)) {
1166 /* If all gone or hole-punch or unfalloc, we're done */
1167 if (index == start || end != -1)
1168 break;
1169 /* But if truncating, restart to make sure all gone */
1170 index = start;
1171 continue;
1172 }
1173 for (i = 0; i < folio_batch_count(fbatch: &fbatch); i++) {
1174 folio = fbatch.folios[i];
1175
1176 if (xa_is_value(entry: folio)) {
1177 long swaps_freed;
1178
1179 if (unfalloc)
1180 continue;
1181 swaps_freed = shmem_free_swap(mapping, index: indices[i], radswap: folio);
1182 if (!swaps_freed) {
1183 /* Swap was replaced by page: retry */
1184 index = indices[i];
1185 break;
1186 }
1187 nr_swaps_freed += swaps_freed;
1188 continue;
1189 }
1190
1191 folio_lock(folio);
1192
1193 if (!unfalloc || !folio_test_uptodate(folio)) {
1194 if (folio_mapping(folio) != mapping) {
1195 /* Page was replaced by swap: retry */
1196 folio_unlock(folio);
1197 index = indices[i];
1198 break;
1199 }
1200 VM_BUG_ON_FOLIO(folio_test_writeback(folio),
1201 folio);
1202
1203 if (!folio_test_large(folio)) {
1204 truncate_inode_folio(mapping, folio);
1205 } else if (truncate_inode_partial_folio(folio, start: lstart, end: lend)) {
1206 /*
1207 * If we split a page, reset the loop so
1208 * that we pick up the new sub pages.
1209 * Otherwise the THP was entirely
1210 * dropped or the target range was
1211 * zeroed, so just continue the loop as
1212 * is.
1213 */
1214 if (!folio_test_large(folio)) {
1215 folio_unlock(folio);
1216 index = start;
1217 break;
1218 }
1219 }
1220 }
1221 folio_unlock(folio);
1222 }
1223 folio_batch_remove_exceptionals(fbatch: &fbatch);
1224 folio_batch_release(fbatch: &fbatch);
1225 }
1226
1227 shmem_recalc_inode(inode, alloced: 0, swapped: -nr_swaps_freed);
1228}
1229
1230void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
1231{
1232 shmem_undo_range(inode, lstart, lend, unfalloc: false);
1233 inode_set_mtime_to_ts(inode, ts: inode_set_ctime_current(inode));
1234 inode_inc_iversion(inode);
1235}
1236EXPORT_SYMBOL_GPL(shmem_truncate_range);
1237
1238static int shmem_getattr(struct mnt_idmap *idmap,
1239 const struct path *path, struct kstat *stat,
1240 u32 request_mask, unsigned int query_flags)
1241{
1242 struct inode *inode = path->dentry->d_inode;
1243 struct shmem_inode_info *info = SHMEM_I(inode);
1244
1245 if (info->alloced - info->swapped != inode->i_mapping->nrpages)
1246 shmem_recalc_inode(inode, alloced: 0, swapped: 0);
1247
1248 if (info->fsflags & FS_APPEND_FL)
1249 stat->attributes |= STATX_ATTR_APPEND;
1250 if (info->fsflags & FS_IMMUTABLE_FL)
1251 stat->attributes |= STATX_ATTR_IMMUTABLE;
1252 if (info->fsflags & FS_NODUMP_FL)
1253 stat->attributes |= STATX_ATTR_NODUMP;
1254 stat->attributes_mask |= (STATX_ATTR_APPEND |
1255 STATX_ATTR_IMMUTABLE |
1256 STATX_ATTR_NODUMP);
1257 generic_fillattr(idmap, request_mask, inode, stat);
1258
1259 if (shmem_huge_global_enabled(inode, index: 0, write_end: 0, shmem_huge_force: false, NULL, vm_flags: 0))
1260 stat->blksize = HPAGE_PMD_SIZE;
1261
1262 if (request_mask & STATX_BTIME) {
1263 stat->result_mask |= STATX_BTIME;
1264 stat->btime.tv_sec = info->i_crtime.tv_sec;
1265 stat->btime.tv_nsec = info->i_crtime.tv_nsec;
1266 }
1267
1268 return 0;
1269}
1270
1271static int shmem_setattr(struct mnt_idmap *idmap,
1272 struct dentry *dentry, struct iattr *attr)
1273{
1274 struct inode *inode = d_inode(dentry);
1275 struct shmem_inode_info *info = SHMEM_I(inode);
1276 int error;
1277 bool update_mtime = false;
1278 bool update_ctime = true;
1279
1280 error = setattr_prepare(idmap, dentry, attr);
1281 if (error)
1282 return error;
1283
1284 if ((info->seals & F_SEAL_EXEC) && (attr->ia_valid & ATTR_MODE)) {
1285 if ((inode->i_mode ^ attr->ia_mode) & 0111) {
1286 return -EPERM;
1287 }
1288 }
1289
1290 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1291 loff_t oldsize = inode->i_size;
1292 loff_t newsize = attr->ia_size;
1293
1294 /* protected by i_rwsem */
1295 if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1296 (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1297 return -EPERM;
1298
1299 if (newsize != oldsize) {
1300 error = shmem_reacct_size(flags: SHMEM_I(inode)->flags,
1301 oldsize, newsize);
1302 if (error)
1303 return error;
1304 i_size_write(inode, i_size: newsize);
1305 update_mtime = true;
1306 } else {
1307 update_ctime = false;
1308 }
1309 if (newsize <= oldsize) {
1310 loff_t holebegin = round_up(newsize, PAGE_SIZE);
1311 if (oldsize > holebegin)
1312 unmap_mapping_range(mapping: inode->i_mapping,
1313 holebegin, holelen: 0, even_cows: 1);
1314 if (info->alloced)
1315 shmem_truncate_range(inode,
1316 newsize, (loff_t)-1);
1317 /* unmap again to remove racily COWed private pages */
1318 if (oldsize > holebegin)
1319 unmap_mapping_range(mapping: inode->i_mapping,
1320 holebegin, holelen: 0, even_cows: 1);
1321 }
1322 }
1323
1324 if (is_quota_modification(idmap, inode, ia: attr)) {
1325 error = dquot_initialize(inode);
1326 if (error)
1327 return error;
1328 }
1329
1330 /* Transfer quota accounting */
1331 if (i_uid_needs_update(idmap, attr, inode) ||
1332 i_gid_needs_update(idmap, attr, inode)) {
1333 error = dquot_transfer(idmap, inode, iattr: attr);
1334 if (error)
1335 return error;
1336 }
1337
1338 setattr_copy(idmap, inode, attr);
1339 if (attr->ia_valid & ATTR_MODE)
1340 error = posix_acl_chmod(idmap, dentry, inode->i_mode);
1341 if (!error && update_ctime) {
1342 inode_set_ctime_current(inode);
1343 if (update_mtime)
1344 inode_set_mtime_to_ts(inode, ts: inode_get_ctime(inode));
1345 inode_inc_iversion(inode);
1346 }
1347 return error;
1348}
1349
1350static void shmem_evict_inode(struct inode *inode)
1351{
1352 struct shmem_inode_info *info = SHMEM_I(inode);
1353 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
1354 size_t freed = 0;
1355
1356 if (shmem_mapping(inode->i_mapping)) {
1357 shmem_unacct_size(flags: info->flags, size: inode->i_size);
1358 inode->i_size = 0;
1359 mapping_set_exiting(mapping: inode->i_mapping);
1360 shmem_truncate_range(inode, 0, (loff_t)-1);
1361 if (!list_empty(head: &info->shrinklist)) {
1362 spin_lock(lock: &sbinfo->shrinklist_lock);
1363 if (!list_empty(head: &info->shrinklist)) {
1364 list_del_init(entry: &info->shrinklist);
1365 sbinfo->shrinklist_len--;
1366 }
1367 spin_unlock(lock: &sbinfo->shrinklist_lock);
1368 }
1369 while (!list_empty(head: &info->swaplist)) {
1370 /* Wait while shmem_unuse() is scanning this inode... */
1371 wait_var_event(&info->stop_eviction,
1372 !atomic_read(&info->stop_eviction));
1373 spin_lock(lock: &shmem_swaplist_lock);
1374 /* ...but beware of the race if we peeked too early */
1375 if (!atomic_read(v: &info->stop_eviction))
1376 list_del_init(entry: &info->swaplist);
1377 spin_unlock(lock: &shmem_swaplist_lock);
1378 }
1379 }
1380
1381 simple_xattrs_free(xattrs: &info->xattrs, freed_space: sbinfo->max_inodes ? &freed : NULL);
1382 shmem_free_inode(sb: inode->i_sb, freed_ispace: freed);
1383 WARN_ON(inode->i_blocks);
1384 clear_inode(inode);
1385#ifdef CONFIG_TMPFS_QUOTA
1386 dquot_free_inode(inode);
1387 dquot_drop(inode);
1388#endif
1389}
1390
1391static unsigned int shmem_find_swap_entries(struct address_space *mapping,
1392 pgoff_t start, struct folio_batch *fbatch,
1393 pgoff_t *indices, unsigned int type)
1394{
1395 XA_STATE(xas, &mapping->i_pages, start);
1396 struct folio *folio;
1397 swp_entry_t entry;
1398
1399 rcu_read_lock();
1400 xas_for_each(&xas, folio, ULONG_MAX) {
1401 if (xas_retry(xas: &xas, entry: folio))
1402 continue;
1403
1404 if (!xa_is_value(entry: folio))
1405 continue;
1406
1407 entry = radix_to_swp_entry(arg: folio);
1408 /*
1409 * swapin error entries can be found in the mapping. But they're
1410 * deliberately ignored here as we've done everything we can do.
1411 */
1412 if (swp_type(entry) != type)
1413 continue;
1414
1415 indices[folio_batch_count(fbatch)] = xas.xa_index;
1416 if (!folio_batch_add(fbatch, folio))
1417 break;
1418
1419 if (need_resched()) {
1420 xas_pause(&xas);
1421 cond_resched_rcu();
1422 }
1423 }
1424 rcu_read_unlock();
1425
1426 return folio_batch_count(fbatch);
1427}
1428
1429/*
1430 * Move the swapped pages for an inode to page cache. Returns the count
1431 * of pages swapped in, or the error in case of failure.
1432 */
1433static int shmem_unuse_swap_entries(struct inode *inode,
1434 struct folio_batch *fbatch, pgoff_t *indices)
1435{
1436 int i = 0;
1437 int ret = 0;
1438 int error = 0;
1439 struct address_space *mapping = inode->i_mapping;
1440
1441 for (i = 0; i < folio_batch_count(fbatch); i++) {
1442 struct folio *folio = fbatch->folios[i];
1443
1444 error = shmem_swapin_folio(inode, index: indices[i], foliop: &folio, sgp: SGP_CACHE,
1445 gfp: mapping_gfp_mask(mapping), NULL, NULL);
1446 if (error == 0) {
1447 folio_unlock(folio);
1448 folio_put(folio);
1449 ret++;
1450 }
1451 if (error == -ENOMEM)
1452 break;
1453 error = 0;
1454 }
1455 return error ? error : ret;
1456}
1457
1458/*
1459 * If swap found in inode, free it and move page from swapcache to filecache.
1460 */
1461static int shmem_unuse_inode(struct inode *inode, unsigned int type)
1462{
1463 struct address_space *mapping = inode->i_mapping;
1464 pgoff_t start = 0;
1465 struct folio_batch fbatch;
1466 pgoff_t indices[PAGEVEC_SIZE];
1467 int ret = 0;
1468
1469 do {
1470 folio_batch_init(fbatch: &fbatch);
1471 if (!shmem_find_swap_entries(mapping, start, fbatch: &fbatch,
1472 indices, type)) {
1473 ret = 0;
1474 break;
1475 }
1476
1477 ret = shmem_unuse_swap_entries(inode, fbatch: &fbatch, indices);
1478 if (ret < 0)
1479 break;
1480
1481 start = indices[folio_batch_count(fbatch: &fbatch) - 1];
1482 } while (true);
1483
1484 return ret;
1485}
1486
1487/*
1488 * Read all the shared memory data that resides in the swap
1489 * device 'type' back into memory, so the swap device can be
1490 * unused.
1491 */
1492int shmem_unuse(unsigned int type)
1493{
1494 struct shmem_inode_info *info, *next;
1495 int error = 0;
1496
1497 if (list_empty(head: &shmem_swaplist))
1498 return 0;
1499
1500 spin_lock(lock: &shmem_swaplist_lock);
1501start_over:
1502 list_for_each_entry_safe(info, next, &shmem_swaplist, swaplist) {
1503 if (!info->swapped) {
1504 list_del_init(entry: &info->swaplist);
1505 continue;
1506 }
1507 /*
1508 * Drop the swaplist mutex while searching the inode for swap;
1509 * but before doing so, make sure shmem_evict_inode() will not
1510 * remove placeholder inode from swaplist, nor let it be freed
1511 * (igrab() would protect from unlink, but not from unmount).
1512 */
1513 atomic_inc(v: &info->stop_eviction);
1514 spin_unlock(lock: &shmem_swaplist_lock);
1515
1516 error = shmem_unuse_inode(inode: &info->vfs_inode, type);
1517 cond_resched();
1518
1519 spin_lock(lock: &shmem_swaplist_lock);
1520 if (atomic_dec_and_test(v: &info->stop_eviction))
1521 wake_up_var(var: &info->stop_eviction);
1522 if (error)
1523 break;
1524 if (list_empty(head: &info->swaplist))
1525 goto start_over;
1526 next = list_next_entry(info, swaplist);
1527 if (!info->swapped)
1528 list_del_init(entry: &info->swaplist);
1529 }
1530 spin_unlock(lock: &shmem_swaplist_lock);
1531
1532 return error;
1533}
1534
1535/**
1536 * shmem_writeout - Write the folio to swap
1537 * @folio: The folio to write
1538 * @plug: swap plug
1539 * @folio_list: list to put back folios on split
1540 *
1541 * Move the folio from the page cache to the swap cache.
1542 */
1543int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
1544 struct list_head *folio_list)
1545{
1546 struct address_space *mapping = folio->mapping;
1547 struct inode *inode = mapping->host;
1548 struct shmem_inode_info *info = SHMEM_I(inode);
1549 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
1550 pgoff_t index;
1551 int nr_pages;
1552 bool split = false;
1553
1554 if ((info->flags & VM_LOCKED) || sbinfo->noswap)
1555 goto redirty;
1556
1557 if (!total_swap_pages)
1558 goto redirty;
1559
1560 /*
1561 * If CONFIG_THP_SWAP is not enabled, the large folio should be
1562 * split when swapping.
1563 *
1564 * And shrinkage of pages beyond i_size does not split swap, so
1565 * swapout of a large folio crossing i_size needs to split too
1566 * (unless fallocate has been used to preallocate beyond EOF).
1567 */
1568 if (folio_test_large(folio)) {
1569 index = shmem_fallocend(inode,
1570 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE));
1571 if ((index > folio->index && index < folio_next_index(folio)) ||
1572 !IS_ENABLED(CONFIG_THP_SWAP))
1573 split = true;
1574 }
1575
1576 if (split) {
1577try_split:
1578 /* Ensure the subpages are still dirty */
1579 folio_test_set_dirty(folio);
1580 if (split_folio_to_list(folio, list: folio_list))
1581 goto redirty;
1582 folio_clear_dirty(folio);
1583 }
1584
1585 index = folio->index;
1586 nr_pages = folio_nr_pages(folio);
1587
1588 /*
1589 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1590 * value into swapfile.c, the only way we can correctly account for a
1591 * fallocated folio arriving here is now to initialize it and write it.
1592 *
1593 * That's okay for a folio already fallocated earlier, but if we have
1594 * not yet completed the fallocation, then (a) we want to keep track
1595 * of this folio in case we have to undo it, and (b) it may not be a
1596 * good idea to continue anyway, once we're pushing into swap. So
1597 * reactivate the folio, and let shmem_fallocate() quit when too many.
1598 */
1599 if (!folio_test_uptodate(folio)) {
1600 if (inode->i_private) {
1601 struct shmem_falloc *shmem_falloc;
1602 spin_lock(lock: &inode->i_lock);
1603 shmem_falloc = inode->i_private;
1604 if (shmem_falloc &&
1605 !shmem_falloc->waitq &&
1606 index >= shmem_falloc->start &&
1607 index < shmem_falloc->next)
1608 shmem_falloc->nr_unswapped += nr_pages;
1609 else
1610 shmem_falloc = NULL;
1611 spin_unlock(lock: &inode->i_lock);
1612 if (shmem_falloc)
1613 goto redirty;
1614 }
1615 folio_zero_range(folio, start: 0, length: folio_size(folio));
1616 flush_dcache_folio(folio);
1617 folio_mark_uptodate(folio);
1618 }
1619
1620 if (!folio_alloc_swap(folio, __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN)) {
1621 bool first_swapped = shmem_recalc_inode(inode, alloced: 0, swapped: nr_pages);
1622 int error;
1623
1624 /*
1625 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1626 * if it's not already there. Do it now before the folio is
1627 * removed from page cache, when its pagelock no longer
1628 * protects the inode from eviction. And do it now, after
1629 * we've incremented swapped, because shmem_unuse() will
1630 * prune a !swapped inode from the swaplist.
1631 */
1632 if (first_swapped) {
1633 spin_lock(lock: &shmem_swaplist_lock);
1634 if (list_empty(head: &info->swaplist))
1635 list_add(new: &info->swaplist, head: &shmem_swaplist);
1636 spin_unlock(lock: &shmem_swaplist_lock);
1637 }
1638
1639 swap_shmem_alloc(folio->swap, nr_pages);
1640 shmem_delete_from_page_cache(folio, radswap: swp_to_radix_entry(entry: folio->swap));
1641
1642 BUG_ON(folio_mapped(folio));
1643 error = swap_writeout(folio, swap_plug: plug);
1644 if (error != AOP_WRITEPAGE_ACTIVATE) {
1645 /* folio has been unlocked */
1646 return error;
1647 }
1648
1649 /*
1650 * The intention here is to avoid holding on to the swap when
1651 * zswap was unable to compress and unable to writeback; but
1652 * it will be appropriate if other reactivate cases are added.
1653 */
1654 error = shmem_add_to_page_cache(folio, mapping, index,
1655 expected: swp_to_radix_entry(entry: folio->swap),
1656 __GFP_HIGH | __GFP_NOMEMALLOC | __GFP_NOWARN);
1657 /* Swap entry might be erased by racing shmem_free_swap() */
1658 if (!error) {
1659 shmem_recalc_inode(inode, alloced: 0, swapped: -nr_pages);
1660 swap_free_nr(entry: folio->swap, nr_pages);
1661 }
1662
1663 /*
1664 * The swap_cache_del_folio() below could be left for
1665 * shrink_folio_list()'s folio_free_swap() to dispose of;
1666 * but I'm a little nervous about letting this folio out of
1667 * shmem_writeout() in a hybrid half-tmpfs-half-swap state
1668 * e.g. folio_mapping(folio) might give an unexpected answer.
1669 */
1670 swap_cache_del_folio(folio);
1671 goto redirty;
1672 }
1673 if (nr_pages > 1)
1674 goto try_split;
1675redirty:
1676 folio_mark_dirty(folio);
1677 return AOP_WRITEPAGE_ACTIVATE; /* Return with folio locked */
1678}
1679EXPORT_SYMBOL_GPL(shmem_writeout);
1680
1681#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1682static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1683{
1684 char buffer[64];
1685
1686 if (!mpol || mpol->mode == MPOL_DEFAULT)
1687 return; /* show nothing */
1688
1689 mpol_to_str(buffer, maxlen: sizeof(buffer), pol: mpol);
1690
1691 seq_printf(m: seq, fmt: ",mpol=%s", buffer);
1692}
1693
1694static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1695{
1696 struct mempolicy *mpol = NULL;
1697 if (sbinfo->mpol) {
1698 raw_spin_lock(&sbinfo->stat_lock); /* prevent replace/use races */
1699 mpol = sbinfo->mpol;
1700 mpol_get(pol: mpol);
1701 raw_spin_unlock(&sbinfo->stat_lock);
1702 }
1703 return mpol;
1704}
1705#else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1706static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1707{
1708}
1709static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1710{
1711 return NULL;
1712}
1713#endif /* CONFIG_NUMA && CONFIG_TMPFS */
1714
1715static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
1716 pgoff_t index, unsigned int order, pgoff_t *ilx);
1717
1718static struct folio *shmem_swapin_cluster(swp_entry_t swap, gfp_t gfp,
1719 struct shmem_inode_info *info, pgoff_t index)
1720{
1721 struct mempolicy *mpol;
1722 pgoff_t ilx;
1723 struct folio *folio;
1724
1725 mpol = shmem_get_pgoff_policy(info, index, order: 0, ilx: &ilx);
1726 folio = swap_cluster_readahead(entry: swap, flag: gfp, mpol, ilx);
1727 mpol_cond_put(pol: mpol);
1728
1729 return folio;
1730}
1731
1732/*
1733 * Make sure huge_gfp is always more limited than limit_gfp.
1734 * Some of the flags set permissions, while others set limitations.
1735 */
1736static gfp_t limit_gfp_mask(gfp_t huge_gfp, gfp_t limit_gfp)
1737{
1738 gfp_t allowflags = __GFP_IO | __GFP_FS | __GFP_RECLAIM;
1739 gfp_t denyflags = __GFP_NOWARN | __GFP_NORETRY;
1740 gfp_t zoneflags = limit_gfp & GFP_ZONEMASK;
1741 gfp_t result = huge_gfp & ~(allowflags | GFP_ZONEMASK);
1742
1743 /* Allow allocations only from the originally specified zones. */
1744 result |= zoneflags;
1745
1746 /*
1747 * Minimize the result gfp by taking the union with the deny flags,
1748 * and the intersection of the allow flags.
1749 */
1750 result |= (limit_gfp & denyflags);
1751 result |= (huge_gfp & limit_gfp) & allowflags;
1752
1753 return result;
1754}
1755
1756#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1757bool shmem_hpage_pmd_enabled(void)
1758{
1759 if (shmem_huge == SHMEM_HUGE_DENY)
1760 return false;
1761 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_always))
1762 return true;
1763 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_madvise))
1764 return true;
1765 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_within_size))
1766 return true;
1767 if (test_bit(HPAGE_PMD_ORDER, &huge_shmem_orders_inherit) &&
1768 shmem_huge != SHMEM_HUGE_NEVER)
1769 return true;
1770
1771 return false;
1772}
1773
1774unsigned long shmem_allowable_huge_orders(struct inode *inode,
1775 struct vm_area_struct *vma, pgoff_t index,
1776 loff_t write_end, bool shmem_huge_force)
1777{
1778 unsigned long mask = READ_ONCE(huge_shmem_orders_always);
1779 unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size);
1780 vm_flags_t vm_flags = vma ? vma->vm_flags : 0;
1781 unsigned int global_orders;
1782
1783 if (thp_disabled_by_hw() || (vma && vma_thp_disabled(vma, vm_flags, shmem_huge_force)))
1784 return 0;
1785
1786 global_orders = shmem_huge_global_enabled(inode, index, write_end,
1787 shmem_huge_force, vma, vm_flags);
1788 /* Tmpfs huge pages allocation */
1789 if (!vma || !vma_is_anon_shmem(vma))
1790 return global_orders;
1791
1792 /*
1793 * Following the 'deny' semantics of the top level, force the huge
1794 * option off from all mounts.
1795 */
1796 if (shmem_huge == SHMEM_HUGE_DENY)
1797 return 0;
1798
1799 /*
1800 * Only allow inherit orders if the top-level value is 'force', which
1801 * means non-PMD sized THP can not override 'huge' mount option now.
1802 */
1803 if (shmem_huge == SHMEM_HUGE_FORCE)
1804 return READ_ONCE(huge_shmem_orders_inherit);
1805
1806 /* Allow mTHP that will be fully within i_size. */
1807 mask |= shmem_get_orders_within_size(inode, within_size_orders, index, 0);
1808
1809 if (vm_flags & VM_HUGEPAGE)
1810 mask |= READ_ONCE(huge_shmem_orders_madvise);
1811
1812 if (global_orders > 0)
1813 mask |= READ_ONCE(huge_shmem_orders_inherit);
1814
1815 return THP_ORDERS_ALL_FILE_DEFAULT & mask;
1816}
1817
1818static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault *vmf,
1819 struct address_space *mapping, pgoff_t index,
1820 unsigned long orders)
1821{
1822 struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
1823 pgoff_t aligned_index;
1824 unsigned long pages;
1825 int order;
1826
1827 if (vma) {
1828 orders = thp_vma_suitable_orders(vma, vmf->address, orders);
1829 if (!orders)
1830 return 0;
1831 }
1832
1833 /* Find the highest order that can add into the page cache */
1834 order = highest_order(orders);
1835 while (orders) {
1836 pages = 1UL << order;
1837 aligned_index = round_down(index, pages);
1838 /*
1839 * Check for conflict before waiting on a huge allocation.
1840 * Conflict might be that a huge page has just been allocated
1841 * and added to page cache by a racing thread, or that there
1842 * is already at least one small page in the huge extent.
1843 * Be careful to retry when appropriate, but not forever!
1844 * Elsewhere -EEXIST would be the right code, but not here.
1845 */
1846 if (!xa_find(&mapping->i_pages, &aligned_index,
1847 aligned_index + pages - 1, XA_PRESENT))
1848 break;
1849 order = next_order(&orders, order);
1850 }
1851
1852 return orders;
1853}
1854#else
1855static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault *vmf,
1856 struct address_space *mapping, pgoff_t index,
1857 unsigned long orders)
1858{
1859 return 0;
1860}
1861#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
1862
1863static struct folio *shmem_alloc_folio(gfp_t gfp, int order,
1864 struct shmem_inode_info *info, pgoff_t index)
1865{
1866 struct mempolicy *mpol;
1867 pgoff_t ilx;
1868 struct folio *folio;
1869
1870 mpol = shmem_get_pgoff_policy(info, index, order, ilx: &ilx);
1871 folio = folio_alloc_mpol(gfp, order, mpol, ilx, numa_node_id());
1872 mpol_cond_put(pol: mpol);
1873
1874 return folio;
1875}
1876
1877static struct folio *shmem_alloc_and_add_folio(struct vm_fault *vmf,
1878 gfp_t gfp, struct inode *inode, pgoff_t index,
1879 struct mm_struct *fault_mm, unsigned long orders)
1880{
1881 struct address_space *mapping = inode->i_mapping;
1882 struct shmem_inode_info *info = SHMEM_I(inode);
1883 unsigned long suitable_orders = 0;
1884 struct folio *folio = NULL;
1885 long pages;
1886 int error, order;
1887
1888 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
1889 orders = 0;
1890
1891 if (orders > 0) {
1892 suitable_orders = shmem_suitable_orders(inode, vmf,
1893 mapping, index, orders);
1894
1895 order = highest_order(orders: suitable_orders);
1896 while (suitable_orders) {
1897 pages = 1UL << order;
1898 index = round_down(index, pages);
1899 folio = shmem_alloc_folio(gfp, order, info, index);
1900 if (folio)
1901 goto allocated;
1902
1903 if (pages == HPAGE_PMD_NR)
1904 count_vm_event(THP_FILE_FALLBACK);
1905 count_mthp_stat(order, item: MTHP_STAT_SHMEM_FALLBACK);
1906 order = next_order(orders: &suitable_orders, prev: order);
1907 }
1908 } else {
1909 pages = 1;
1910 folio = shmem_alloc_folio(gfp, order: 0, info, index);
1911 }
1912 if (!folio)
1913 return ERR_PTR(error: -ENOMEM);
1914
1915allocated:
1916 __folio_set_locked(folio);
1917 __folio_set_swapbacked(folio);
1918
1919 gfp &= GFP_RECLAIM_MASK;
1920 error = mem_cgroup_charge(folio, mm: fault_mm, gfp);
1921 if (error) {
1922 if (xa_find(xa: &mapping->i_pages, index: &index,
1923 max: index + pages - 1, XA_PRESENT)) {
1924 error = -EEXIST;
1925 } else if (pages > 1) {
1926 if (pages == HPAGE_PMD_NR) {
1927 count_vm_event(THP_FILE_FALLBACK);
1928 count_vm_event(THP_FILE_FALLBACK_CHARGE);
1929 }
1930 count_mthp_stat(order: folio_order(folio), item: MTHP_STAT_SHMEM_FALLBACK);
1931 count_mthp_stat(order: folio_order(folio), item: MTHP_STAT_SHMEM_FALLBACK_CHARGE);
1932 }
1933 goto unlock;
1934 }
1935
1936 error = shmem_add_to_page_cache(folio, mapping, index, NULL, gfp);
1937 if (error)
1938 goto unlock;
1939
1940 error = shmem_inode_acct_blocks(inode, pages);
1941 if (error) {
1942 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
1943 long freed;
1944 /*
1945 * Try to reclaim some space by splitting a few
1946 * large folios beyond i_size on the filesystem.
1947 */
1948 shmem_unused_huge_shrink(sbinfo, NULL, nr_to_free: pages);
1949 /*
1950 * And do a shmem_recalc_inode() to account for freed pages:
1951 * except our folio is there in cache, so not quite balanced.
1952 */
1953 spin_lock(lock: &info->lock);
1954 freed = pages + info->alloced - info->swapped -
1955 READ_ONCE(mapping->nrpages);
1956 if (freed > 0)
1957 info->alloced -= freed;
1958 spin_unlock(lock: &info->lock);
1959 if (freed > 0)
1960 shmem_inode_unacct_blocks(inode, pages: freed);
1961 error = shmem_inode_acct_blocks(inode, pages);
1962 if (error) {
1963 filemap_remove_folio(folio);
1964 goto unlock;
1965 }
1966 }
1967
1968 shmem_recalc_inode(inode, alloced: pages, swapped: 0);
1969 folio_add_lru(folio);
1970 return folio;
1971
1972unlock:
1973 folio_unlock(folio);
1974 folio_put(folio);
1975 return ERR_PTR(error);
1976}
1977
1978static struct folio *shmem_swap_alloc_folio(struct inode *inode,
1979 struct vm_area_struct *vma, pgoff_t index,
1980 swp_entry_t entry, int order, gfp_t gfp)
1981{
1982 struct shmem_inode_info *info = SHMEM_I(inode);
1983 int nr_pages = 1 << order;
1984 struct folio *new;
1985 gfp_t alloc_gfp;
1986 void *shadow;
1987
1988 /*
1989 * We have arrived here because our zones are constrained, so don't
1990 * limit chance of success with further cpuset and node constraints.
1991 */
1992 gfp &= ~GFP_CONSTRAINT_MASK;
1993 alloc_gfp = gfp;
1994 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
1995 if (WARN_ON_ONCE(order))
1996 return ERR_PTR(error: -EINVAL);
1997 } else if (order) {
1998 /*
1999 * If uffd is active for the vma, we need per-page fault
2000 * fidelity to maintain the uffd semantics, then fallback
2001 * to swapin order-0 folio, as well as for zswap case.
2002 * Any existing sub folio in the swap cache also blocks
2003 * mTHP swapin.
2004 */
2005 if ((vma && unlikely(userfaultfd_armed(vma))) ||
2006 !zswap_never_enabled() ||
2007 non_swapcache_batch(entry, max_nr: nr_pages) != nr_pages)
2008 goto fallback;
2009
2010 alloc_gfp = limit_gfp_mask(huge_gfp: vma_thp_gfp_mask(vma), limit_gfp: gfp);
2011 }
2012retry:
2013 new = shmem_alloc_folio(gfp: alloc_gfp, order, info, index);
2014 if (!new) {
2015 new = ERR_PTR(error: -ENOMEM);
2016 goto fallback;
2017 }
2018
2019 if (mem_cgroup_swapin_charge_folio(folio: new, mm: vma ? vma->vm_mm : NULL,
2020 gfp: alloc_gfp, entry)) {
2021 folio_put(folio: new);
2022 new = ERR_PTR(error: -ENOMEM);
2023 goto fallback;
2024 }
2025
2026 /*
2027 * Prevent parallel swapin from proceeding with the swap cache flag.
2028 *
2029 * Of course there is another possible concurrent scenario as well,
2030 * that is to say, the swap cache flag of a large folio has already
2031 * been set by swapcache_prepare(), while another thread may have
2032 * already split the large swap entry stored in the shmem mapping.
2033 * In this case, shmem_add_to_page_cache() will help identify the
2034 * concurrent swapin and return -EEXIST.
2035 */
2036 if (swapcache_prepare(entry, nr: nr_pages)) {
2037 folio_put(folio: new);
2038 new = ERR_PTR(error: -EEXIST);
2039 /* Try smaller folio to avoid cache conflict */
2040 goto fallback;
2041 }
2042
2043 __folio_set_locked(folio: new);
2044 __folio_set_swapbacked(folio: new);
2045 new->swap = entry;
2046
2047 memcg1_swapin(entry, nr_pages);
2048 shadow = swap_cache_get_shadow(entry);
2049 if (shadow)
2050 workingset_refault(folio: new, shadow);
2051 folio_add_lru(new);
2052 swap_read_folio(folio: new, NULL);
2053 return new;
2054fallback:
2055 /* Order 0 swapin failed, nothing to fallback to, abort */
2056 if (!order)
2057 return new;
2058 entry.val += index - round_down(index, nr_pages);
2059 alloc_gfp = gfp;
2060 nr_pages = 1;
2061 order = 0;
2062 goto retry;
2063}
2064
2065/*
2066 * When a page is moved from swapcache to shmem filecache (either by the
2067 * usual swapin of shmem_get_folio_gfp(), or by the less common swapoff of
2068 * shmem_unuse_inode()), it may have been read in earlier from swap, in
2069 * ignorance of the mapping it belongs to. If that mapping has special
2070 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
2071 * we may need to copy to a suitable page before moving to filecache.
2072 *
2073 * In a future release, this may well be extended to respect cpuset and
2074 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
2075 * but for now it is a simple matter of zone.
2076 */
2077static bool shmem_should_replace_folio(struct folio *folio, gfp_t gfp)
2078{
2079 return folio_zonenum(folio) > gfp_zone(flags: gfp);
2080}
2081
2082static int shmem_replace_folio(struct folio **foliop, gfp_t gfp,
2083 struct shmem_inode_info *info, pgoff_t index,
2084 struct vm_area_struct *vma)
2085{
2086 struct swap_cluster_info *ci;
2087 struct folio *new, *old = *foliop;
2088 swp_entry_t entry = old->swap;
2089 int nr_pages = folio_nr_pages(folio: old);
2090 int error = 0;
2091
2092 /*
2093 * We have arrived here because our zones are constrained, so don't
2094 * limit chance of success by further cpuset and node constraints.
2095 */
2096 gfp &= ~GFP_CONSTRAINT_MASK;
2097#ifdef CONFIG_TRANSPARENT_HUGEPAGE
2098 if (nr_pages > 1) {
2099 gfp_t huge_gfp = vma_thp_gfp_mask(vma);
2100
2101 gfp = limit_gfp_mask(huge_gfp, gfp);
2102 }
2103#endif
2104
2105 new = shmem_alloc_folio(gfp, order: folio_order(folio: old), info, index);
2106 if (!new)
2107 return -ENOMEM;
2108
2109 folio_ref_add(folio: new, nr: nr_pages);
2110 folio_copy(dst: new, src: old);
2111 flush_dcache_folio(folio: new);
2112
2113 __folio_set_locked(folio: new);
2114 __folio_set_swapbacked(folio: new);
2115 folio_mark_uptodate(folio: new);
2116 new->swap = entry;
2117 folio_set_swapcache(folio: new);
2118
2119 ci = swap_cluster_get_and_lock_irq(folio: old);
2120 __swap_cache_replace_folio(ci, old, new);
2121 mem_cgroup_replace_folio(old, new);
2122 shmem_update_stats(folio: new, nr_pages);
2123 shmem_update_stats(folio: old, nr_pages: -nr_pages);
2124 swap_cluster_unlock_irq(ci);
2125
2126 folio_add_lru(new);
2127 *foliop = new;
2128
2129 folio_clear_swapcache(folio: old);
2130 old->private = NULL;
2131
2132 folio_unlock(folio: old);
2133 /*
2134 * The old folio are removed from swap cache, drop the 'nr_pages'
2135 * reference, as well as one temporary reference getting from swap
2136 * cache.
2137 */
2138 folio_put_refs(folio: old, refs: nr_pages + 1);
2139 return error;
2140}
2141
2142static void shmem_set_folio_swapin_error(struct inode *inode, pgoff_t index,
2143 struct folio *folio, swp_entry_t swap,
2144 bool skip_swapcache)
2145{
2146 struct address_space *mapping = inode->i_mapping;
2147 swp_entry_t swapin_error;
2148 void *old;
2149 int nr_pages;
2150
2151 swapin_error = make_poisoned_swp_entry();
2152 old = xa_cmpxchg_irq(xa: &mapping->i_pages, index,
2153 old: swp_to_radix_entry(entry: swap),
2154 entry: swp_to_radix_entry(entry: swapin_error), gfp: 0);
2155 if (old != swp_to_radix_entry(entry: swap))
2156 return;
2157
2158 nr_pages = folio_nr_pages(folio);
2159 folio_wait_writeback(folio);
2160 if (!skip_swapcache)
2161 swap_cache_del_folio(folio);
2162 /*
2163 * Don't treat swapin error folio as alloced. Otherwise inode->i_blocks
2164 * won't be 0 when inode is released and thus trigger WARN_ON(i_blocks)
2165 * in shmem_evict_inode().
2166 */
2167 shmem_recalc_inode(inode, alloced: -nr_pages, swapped: -nr_pages);
2168 swap_free_nr(entry: swap, nr_pages);
2169}
2170
2171static int shmem_split_large_entry(struct inode *inode, pgoff_t index,
2172 swp_entry_t swap, gfp_t gfp)
2173{
2174 struct address_space *mapping = inode->i_mapping;
2175 XA_STATE_ORDER(xas, &mapping->i_pages, index, 0);
2176 int split_order = 0;
2177 int i;
2178
2179 /* Convert user data gfp flags to xarray node gfp flags */
2180 gfp &= GFP_RECLAIM_MASK;
2181
2182 for (;;) {
2183 void *old = NULL;
2184 int cur_order;
2185 pgoff_t swap_index;
2186
2187 xas_lock_irq(&xas);
2188 old = xas_load(&xas);
2189 if (!xa_is_value(entry: old) || swp_to_radix_entry(entry: swap) != old) {
2190 xas_set_err(xas: &xas, err: -EEXIST);
2191 goto unlock;
2192 }
2193
2194 cur_order = xas_get_order(xas: &xas);
2195 if (!cur_order)
2196 goto unlock;
2197
2198 /* Try to split large swap entry in pagecache */
2199 swap_index = round_down(index, 1 << cur_order);
2200 split_order = xas_try_split_min_order(order: cur_order);
2201
2202 while (cur_order > 0) {
2203 pgoff_t aligned_index =
2204 round_down(index, 1 << cur_order);
2205 pgoff_t swap_offset = aligned_index - swap_index;
2206
2207 xas_set_order(xas: &xas, index, order: split_order);
2208 xas_try_split(xas: &xas, entry: old, order: cur_order);
2209 if (xas_error(xas: &xas))
2210 goto unlock;
2211
2212 /*
2213 * Re-set the swap entry after splitting, and the swap
2214 * offset of the original large entry must be continuous.
2215 */
2216 for (i = 0; i < 1 << cur_order;
2217 i += (1 << split_order)) {
2218 swp_entry_t tmp;
2219
2220 tmp = swp_entry(type: swp_type(entry: swap),
2221 offset: swp_offset(entry: swap) + swap_offset +
2222 i);
2223 __xa_store(&mapping->i_pages, index: aligned_index + i,
2224 entry: swp_to_radix_entry(entry: tmp), 0);
2225 }
2226 cur_order = split_order;
2227 split_order = xas_try_split_min_order(order: split_order);
2228 }
2229
2230unlock:
2231 xas_unlock_irq(&xas);
2232
2233 if (!xas_nomem(&xas, gfp))
2234 break;
2235 }
2236
2237 if (xas_error(xas: &xas))
2238 return xas_error(xas: &xas);
2239
2240 return 0;
2241}
2242
2243/*
2244 * Swap in the folio pointed to by *foliop.
2245 * Caller has to make sure that *foliop contains a valid swapped folio.
2246 * Returns 0 and the folio in foliop if success. On failure, returns the
2247 * error code and NULL in *foliop.
2248 */
2249static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
2250 struct folio **foliop, enum sgp_type sgp,
2251 gfp_t gfp, struct vm_area_struct *vma,
2252 vm_fault_t *fault_type)
2253{
2254 struct address_space *mapping = inode->i_mapping;
2255 struct mm_struct *fault_mm = vma ? vma->vm_mm : NULL;
2256 struct shmem_inode_info *info = SHMEM_I(inode);
2257 swp_entry_t swap, index_entry;
2258 struct swap_info_struct *si;
2259 struct folio *folio = NULL;
2260 bool skip_swapcache = false;
2261 int error, nr_pages, order;
2262 pgoff_t offset;
2263
2264 VM_BUG_ON(!*foliop || !xa_is_value(*foliop));
2265 index_entry = radix_to_swp_entry(arg: *foliop);
2266 swap = index_entry;
2267 *foliop = NULL;
2268
2269 if (is_poisoned_swp_entry(entry: index_entry))
2270 return -EIO;
2271
2272 si = get_swap_device(entry: index_entry);
2273 order = shmem_confirm_swap(mapping, index, swap: index_entry);
2274 if (unlikely(!si)) {
2275 if (order < 0)
2276 return -EEXIST;
2277 else
2278 return -EINVAL;
2279 }
2280 if (unlikely(order < 0)) {
2281 put_swap_device(si);
2282 return -EEXIST;
2283 }
2284
2285 /* index may point to the middle of a large entry, get the sub entry */
2286 if (order) {
2287 offset = index - round_down(index, 1 << order);
2288 swap = swp_entry(type: swp_type(entry: swap), offset: swp_offset(entry: swap) + offset);
2289 }
2290
2291 /* Look it up and read it in.. */
2292 folio = swap_cache_get_folio(entry: swap);
2293 if (!folio) {
2294 if (data_race(si->flags & SWP_SYNCHRONOUS_IO)) {
2295 /* Direct swapin skipping swap cache & readahead */
2296 folio = shmem_swap_alloc_folio(inode, vma, index,
2297 entry: index_entry, order, gfp);
2298 if (IS_ERR(ptr: folio)) {
2299 error = PTR_ERR(ptr: folio);
2300 folio = NULL;
2301 goto failed;
2302 }
2303 skip_swapcache = true;
2304 } else {
2305 /* Cached swapin only supports order 0 folio */
2306 folio = shmem_swapin_cluster(swap, gfp, info, index);
2307 if (!folio) {
2308 error = -ENOMEM;
2309 goto failed;
2310 }
2311 }
2312 if (fault_type) {
2313 *fault_type |= VM_FAULT_MAJOR;
2314 count_vm_event(item: PGMAJFAULT);
2315 count_memcg_event_mm(mm: fault_mm, idx: PGMAJFAULT);
2316 }
2317 } else {
2318 swap_update_readahead(folio, NULL, addr: 0);
2319 }
2320
2321 if (order > folio_order(folio)) {
2322 /*
2323 * Swapin may get smaller folios due to various reasons:
2324 * It may fallback to order 0 due to memory pressure or race,
2325 * swap readahead may swap in order 0 folios into swapcache
2326 * asynchronously, while the shmem mapping can still stores
2327 * large swap entries. In such cases, we should split the
2328 * large swap entry to prevent possible data corruption.
2329 */
2330 error = shmem_split_large_entry(inode, index, swap: index_entry, gfp);
2331 if (error)
2332 goto failed_nolock;
2333 }
2334
2335 /*
2336 * If the folio is large, round down swap and index by folio size.
2337 * No matter what race occurs, the swap layer ensures we either get
2338 * a valid folio that has its swap entry aligned by size, or a
2339 * temporarily invalid one which we'll abort very soon and retry.
2340 *
2341 * shmem_add_to_page_cache ensures the whole range contains expected
2342 * entries and prevents any corruption, so any race split is fine
2343 * too, it will succeed as long as the entries are still there.
2344 */
2345 nr_pages = folio_nr_pages(folio);
2346 if (nr_pages > 1) {
2347 swap.val = round_down(swap.val, nr_pages);
2348 index = round_down(index, nr_pages);
2349 }
2350
2351 /*
2352 * We have to do this with the folio locked to prevent races.
2353 * The shmem_confirm_swap below only checks if the first swap
2354 * entry matches the folio, that's enough to ensure the folio
2355 * is not used outside of shmem, as shmem swap entries
2356 * and swap cache folios are never partially freed.
2357 */
2358 folio_lock(folio);
2359 if ((!skip_swapcache && !folio_test_swapcache(folio)) ||
2360 shmem_confirm_swap(mapping, index, swap) < 0 ||
2361 folio->swap.val != swap.val) {
2362 error = -EEXIST;
2363 goto unlock;
2364 }
2365 if (!folio_test_uptodate(folio)) {
2366 error = -EIO;
2367 goto failed;
2368 }
2369 folio_wait_writeback(folio);
2370
2371 /*
2372 * Some architectures may have to restore extra metadata to the
2373 * folio after reading from swap.
2374 */
2375 arch_swap_restore(entry: folio_swap(entry: swap, folio), folio);
2376
2377 if (shmem_should_replace_folio(folio, gfp)) {
2378 error = shmem_replace_folio(foliop: &folio, gfp, info, index, vma);
2379 if (error)
2380 goto failed;
2381 }
2382
2383 error = shmem_add_to_page_cache(folio, mapping, index,
2384 expected: swp_to_radix_entry(entry: swap), gfp);
2385 if (error)
2386 goto failed;
2387
2388 shmem_recalc_inode(inode, alloced: 0, swapped: -nr_pages);
2389
2390 if (sgp == SGP_WRITE)
2391 folio_mark_accessed(folio);
2392
2393 if (skip_swapcache) {
2394 folio->swap.val = 0;
2395 swapcache_clear(si, entry: swap, nr: nr_pages);
2396 } else {
2397 swap_cache_del_folio(folio);
2398 }
2399 folio_mark_dirty(folio);
2400 swap_free_nr(entry: swap, nr_pages);
2401 put_swap_device(si);
2402
2403 *foliop = folio;
2404 return 0;
2405failed:
2406 if (shmem_confirm_swap(mapping, index, swap) < 0)
2407 error = -EEXIST;
2408 if (error == -EIO)
2409 shmem_set_folio_swapin_error(inode, index, folio, swap,
2410 skip_swapcache);
2411unlock:
2412 if (folio)
2413 folio_unlock(folio);
2414failed_nolock:
2415 if (skip_swapcache)
2416 swapcache_clear(si, entry: folio->swap, nr: folio_nr_pages(folio));
2417 if (folio)
2418 folio_put(folio);
2419 put_swap_device(si);
2420
2421 return error;
2422}
2423
2424/*
2425 * shmem_get_folio_gfp - find page in cache, or get from swap, or allocate
2426 *
2427 * If we allocate a new one we do not mark it dirty. That's up to the
2428 * vm. If we swap it in we mark it dirty since we also free the swap
2429 * entry since a page cannot live in both the swap and page cache.
2430 *
2431 * vmf and fault_type are only supplied by shmem_fault: otherwise they are NULL.
2432 */
2433static int shmem_get_folio_gfp(struct inode *inode, pgoff_t index,
2434 loff_t write_end, struct folio **foliop, enum sgp_type sgp,
2435 gfp_t gfp, struct vm_fault *vmf, vm_fault_t *fault_type)
2436{
2437 struct vm_area_struct *vma = vmf ? vmf->vma : NULL;
2438 struct mm_struct *fault_mm;
2439 struct folio *folio;
2440 int error;
2441 bool alloced;
2442 unsigned long orders = 0;
2443
2444 if (WARN_ON_ONCE(!shmem_mapping(inode->i_mapping)))
2445 return -EINVAL;
2446
2447 if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
2448 return -EFBIG;
2449repeat:
2450 if (sgp <= SGP_CACHE &&
2451 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode))
2452 return -EINVAL;
2453
2454 alloced = false;
2455 fault_mm = vma ? vma->vm_mm : NULL;
2456
2457 folio = filemap_get_entry(mapping: inode->i_mapping, index);
2458 if (folio && vma && userfaultfd_minor(vma)) {
2459 if (!xa_is_value(entry: folio))
2460 folio_put(folio);
2461 *fault_type = handle_userfault(vmf, VM_UFFD_MINOR);
2462 return 0;
2463 }
2464
2465 if (xa_is_value(entry: folio)) {
2466 error = shmem_swapin_folio(inode, index, foliop: &folio,
2467 sgp, gfp, vma, fault_type);
2468 if (error == -EEXIST)
2469 goto repeat;
2470
2471 *foliop = folio;
2472 return error;
2473 }
2474
2475 if (folio) {
2476 folio_lock(folio);
2477
2478 /* Has the folio been truncated or swapped out? */
2479 if (unlikely(folio->mapping != inode->i_mapping)) {
2480 folio_unlock(folio);
2481 folio_put(folio);
2482 goto repeat;
2483 }
2484 if (sgp == SGP_WRITE)
2485 folio_mark_accessed(folio);
2486 if (folio_test_uptodate(folio))
2487 goto out;
2488 /* fallocated folio */
2489 if (sgp != SGP_READ)
2490 goto clear;
2491 folio_unlock(folio);
2492 folio_put(folio);
2493 }
2494
2495 /*
2496 * SGP_READ: succeed on hole, with NULL folio, letting caller zero.
2497 * SGP_NOALLOC: fail on hole, with NULL folio, letting caller fail.
2498 */
2499 *foliop = NULL;
2500 if (sgp == SGP_READ)
2501 return 0;
2502 if (sgp == SGP_NOALLOC)
2503 return -ENOENT;
2504
2505 /*
2506 * Fast cache lookup and swap lookup did not find it: allocate.
2507 */
2508
2509 if (vma && userfaultfd_missing(vma)) {
2510 *fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
2511 return 0;
2512 }
2513
2514 /* Find hugepage orders that are allowed for anonymous shmem and tmpfs. */
2515 orders = shmem_allowable_huge_orders(inode, vma, index, write_end, shmem_huge_force: false);
2516 if (orders > 0) {
2517 gfp_t huge_gfp;
2518
2519 huge_gfp = vma_thp_gfp_mask(vma);
2520 huge_gfp = limit_gfp_mask(huge_gfp, limit_gfp: gfp);
2521 folio = shmem_alloc_and_add_folio(vmf, gfp: huge_gfp,
2522 inode, index, fault_mm, orders);
2523 if (!IS_ERR(ptr: folio)) {
2524 if (folio_test_pmd_mappable(folio))
2525 count_vm_event(THP_FILE_ALLOC);
2526 count_mthp_stat(order: folio_order(folio), item: MTHP_STAT_SHMEM_ALLOC);
2527 goto alloced;
2528 }
2529 if (PTR_ERR(ptr: folio) == -EEXIST)
2530 goto repeat;
2531 }
2532
2533 folio = shmem_alloc_and_add_folio(vmf, gfp, inode, index, fault_mm, orders: 0);
2534 if (IS_ERR(ptr: folio)) {
2535 error = PTR_ERR(ptr: folio);
2536 if (error == -EEXIST)
2537 goto repeat;
2538 folio = NULL;
2539 goto unlock;
2540 }
2541
2542alloced:
2543 alloced = true;
2544 if (folio_test_large(folio) &&
2545 DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
2546 folio_next_index(folio)) {
2547 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
2548 struct shmem_inode_info *info = SHMEM_I(inode);
2549 /*
2550 * Part of the large folio is beyond i_size: subject
2551 * to shrink under memory pressure.
2552 */
2553 spin_lock(lock: &sbinfo->shrinklist_lock);
2554 /*
2555 * _careful to defend against unlocked access to
2556 * ->shrink_list in shmem_unused_huge_shrink()
2557 */
2558 if (list_empty_careful(head: &info->shrinklist)) {
2559 list_add_tail(new: &info->shrinklist,
2560 head: &sbinfo->shrinklist);
2561 sbinfo->shrinklist_len++;
2562 }
2563 spin_unlock(lock: &sbinfo->shrinklist_lock);
2564 }
2565
2566 if (sgp == SGP_WRITE)
2567 folio_set_referenced(folio);
2568 /*
2569 * Let SGP_FALLOC use the SGP_WRITE optimization on a new folio.
2570 */
2571 if (sgp == SGP_FALLOC)
2572 sgp = SGP_WRITE;
2573clear:
2574 /*
2575 * Let SGP_WRITE caller clear ends if write does not fill folio;
2576 * but SGP_FALLOC on a folio fallocated earlier must initialize
2577 * it now, lest undo on failure cancel our earlier guarantee.
2578 */
2579 if (sgp != SGP_WRITE && !folio_test_uptodate(folio)) {
2580 long i, n = folio_nr_pages(folio);
2581
2582 for (i = 0; i < n; i++)
2583 clear_highpage(folio_page(folio, i));
2584 flush_dcache_folio(folio);
2585 folio_mark_uptodate(folio);
2586 }
2587
2588 /* Perhaps the file has been truncated since we checked */
2589 if (sgp <= SGP_CACHE &&
2590 ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
2591 error = -EINVAL;
2592 goto unlock;
2593 }
2594out:
2595 *foliop = folio;
2596 return 0;
2597
2598 /*
2599 * Error recovery.
2600 */
2601unlock:
2602 if (alloced)
2603 filemap_remove_folio(folio);
2604 shmem_recalc_inode(inode, alloced: 0, swapped: 0);
2605 if (folio) {
2606 folio_unlock(folio);
2607 folio_put(folio);
2608 }
2609 return error;
2610}
2611
2612/**
2613 * shmem_get_folio - find, and lock a shmem folio.
2614 * @inode: inode to search
2615 * @index: the page index.
2616 * @write_end: end of a write, could extend inode size
2617 * @foliop: pointer to the folio if found
2618 * @sgp: SGP_* flags to control behavior
2619 *
2620 * Looks up the page cache entry at @inode & @index. If a folio is
2621 * present, it is returned locked with an increased refcount.
2622 *
2623 * If the caller modifies data in the folio, it must call folio_mark_dirty()
2624 * before unlocking the folio to ensure that the folio is not reclaimed.
2625 * There is no need to reserve space before calling folio_mark_dirty().
2626 *
2627 * When no folio is found, the behavior depends on @sgp:
2628 * - for SGP_READ, *@foliop is %NULL and 0 is returned
2629 * - for SGP_NOALLOC, *@foliop is %NULL and -ENOENT is returned
2630 * - for all other flags a new folio is allocated, inserted into the
2631 * page cache and returned locked in @foliop.
2632 *
2633 * Context: May sleep.
2634 * Return: 0 if successful, else a negative error code.
2635 */
2636int shmem_get_folio(struct inode *inode, pgoff_t index, loff_t write_end,
2637 struct folio **foliop, enum sgp_type sgp)
2638{
2639 return shmem_get_folio_gfp(inode, index, write_end, foliop, sgp,
2640 gfp: mapping_gfp_mask(mapping: inode->i_mapping), NULL, NULL);
2641}
2642EXPORT_SYMBOL_GPL(shmem_get_folio);
2643
2644/*
2645 * This is like autoremove_wake_function, but it removes the wait queue
2646 * entry unconditionally - even if something else had already woken the
2647 * target.
2648 */
2649static int synchronous_wake_function(wait_queue_entry_t *wait,
2650 unsigned int mode, int sync, void *key)
2651{
2652 int ret = default_wake_function(wq_entry: wait, mode, flags: sync, key);
2653 list_del_init(entry: &wait->entry);
2654 return ret;
2655}
2656
2657/*
2658 * Trinity finds that probing a hole which tmpfs is punching can
2659 * prevent the hole-punch from ever completing: which in turn
2660 * locks writers out with its hold on i_rwsem. So refrain from
2661 * faulting pages into the hole while it's being punched. Although
2662 * shmem_undo_range() does remove the additions, it may be unable to
2663 * keep up, as each new page needs its own unmap_mapping_range() call,
2664 * and the i_mmap tree grows ever slower to scan if new vmas are added.
2665 *
2666 * It does not matter if we sometimes reach this check just before the
2667 * hole-punch begins, so that one fault then races with the punch:
2668 * we just need to make racing faults a rare case.
2669 *
2670 * The implementation below would be much simpler if we just used a
2671 * standard mutex or completion: but we cannot take i_rwsem in fault,
2672 * and bloating every shmem inode for this unlikely case would be sad.
2673 */
2674static vm_fault_t shmem_falloc_wait(struct vm_fault *vmf, struct inode *inode)
2675{
2676 struct shmem_falloc *shmem_falloc;
2677 struct file *fpin = NULL;
2678 vm_fault_t ret = 0;
2679
2680 spin_lock(lock: &inode->i_lock);
2681 shmem_falloc = inode->i_private;
2682 if (shmem_falloc &&
2683 shmem_falloc->waitq &&
2684 vmf->pgoff >= shmem_falloc->start &&
2685 vmf->pgoff < shmem_falloc->next) {
2686 wait_queue_head_t *shmem_falloc_waitq;
2687 DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
2688
2689 ret = VM_FAULT_NOPAGE;
2690 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
2691 shmem_falloc_waitq = shmem_falloc->waitq;
2692 prepare_to_wait(wq_head: shmem_falloc_waitq, wq_entry: &shmem_fault_wait,
2693 TASK_UNINTERRUPTIBLE);
2694 spin_unlock(lock: &inode->i_lock);
2695 schedule();
2696
2697 /*
2698 * shmem_falloc_waitq points into the shmem_fallocate()
2699 * stack of the hole-punching task: shmem_falloc_waitq
2700 * is usually invalid by the time we reach here, but
2701 * finish_wait() does not dereference it in that case;
2702 * though i_lock needed lest racing with wake_up_all().
2703 */
2704 spin_lock(lock: &inode->i_lock);
2705 finish_wait(wq_head: shmem_falloc_waitq, wq_entry: &shmem_fault_wait);
2706 }
2707 spin_unlock(lock: &inode->i_lock);
2708 if (fpin) {
2709 fput(fpin);
2710 ret = VM_FAULT_RETRY;
2711 }
2712 return ret;
2713}
2714
2715static vm_fault_t shmem_fault(struct vm_fault *vmf)
2716{
2717 struct inode *inode = file_inode(f: vmf->vma->vm_file);
2718 gfp_t gfp = mapping_gfp_mask(mapping: inode->i_mapping);
2719 struct folio *folio = NULL;
2720 vm_fault_t ret = 0;
2721 int err;
2722
2723 /*
2724 * Trinity finds that probing a hole which tmpfs is punching can
2725 * prevent the hole-punch from ever completing: noted in i_private.
2726 */
2727 if (unlikely(inode->i_private)) {
2728 ret = shmem_falloc_wait(vmf, inode);
2729 if (ret)
2730 return ret;
2731 }
2732
2733 WARN_ON_ONCE(vmf->page != NULL);
2734 err = shmem_get_folio_gfp(inode, index: vmf->pgoff, write_end: 0, foliop: &folio, sgp: SGP_CACHE,
2735 gfp, vmf, fault_type: &ret);
2736 if (err)
2737 return vmf_error(err);
2738 if (folio) {
2739 vmf->page = folio_file_page(folio, index: vmf->pgoff);
2740 ret |= VM_FAULT_LOCKED;
2741 }
2742 return ret;
2743}
2744
2745unsigned long shmem_get_unmapped_area(struct file *file,
2746 unsigned long uaddr, unsigned long len,
2747 unsigned long pgoff, unsigned long flags)
2748{
2749 unsigned long addr;
2750 unsigned long offset;
2751 unsigned long inflated_len;
2752 unsigned long inflated_addr;
2753 unsigned long inflated_offset;
2754 unsigned long hpage_size;
2755
2756 if (len > TASK_SIZE)
2757 return -ENOMEM;
2758
2759 addr = mm_get_unmapped_area(current->mm, filp: file, addr: uaddr, len, pgoff,
2760 flags);
2761
2762 if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE))
2763 return addr;
2764 if (IS_ERR_VALUE(addr))
2765 return addr;
2766 if (addr & ~PAGE_MASK)
2767 return addr;
2768 if (addr > TASK_SIZE - len)
2769 return addr;
2770
2771 if (shmem_huge == SHMEM_HUGE_DENY)
2772 return addr;
2773 if (flags & MAP_FIXED)
2774 return addr;
2775 /*
2776 * Our priority is to support MAP_SHARED mapped hugely;
2777 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2778 * But if caller specified an address hint and we allocated area there
2779 * successfully, respect that as before.
2780 */
2781 if (uaddr == addr)
2782 return addr;
2783
2784 hpage_size = HPAGE_PMD_SIZE;
2785 if (shmem_huge != SHMEM_HUGE_FORCE) {
2786 struct super_block *sb;
2787 unsigned long __maybe_unused hpage_orders;
2788 int order = 0;
2789
2790 if (file) {
2791 VM_BUG_ON(file->f_op != &shmem_file_operations);
2792 sb = file_inode(f: file)->i_sb;
2793 } else {
2794 /*
2795 * Called directly from mm/mmap.c, or drivers/char/mem.c
2796 * for "/dev/zero", to create a shared anonymous object.
2797 */
2798 if (IS_ERR(ptr: shm_mnt))
2799 return addr;
2800 sb = shm_mnt->mnt_sb;
2801
2802 /*
2803 * Find the highest mTHP order used for anonymous shmem to
2804 * provide a suitable alignment address.
2805 */
2806#ifdef CONFIG_TRANSPARENT_HUGEPAGE
2807 hpage_orders = READ_ONCE(huge_shmem_orders_always);
2808 hpage_orders |= READ_ONCE(huge_shmem_orders_within_size);
2809 hpage_orders |= READ_ONCE(huge_shmem_orders_madvise);
2810 if (SHMEM_SB(sb)->huge != SHMEM_HUGE_NEVER)
2811 hpage_orders |= READ_ONCE(huge_shmem_orders_inherit);
2812
2813 if (hpage_orders > 0) {
2814 order = highest_order(hpage_orders);
2815 hpage_size = PAGE_SIZE << order;
2816 }
2817#endif
2818 }
2819 if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER && !order)
2820 return addr;
2821 }
2822
2823 if (len < hpage_size)
2824 return addr;
2825
2826 offset = (pgoff << PAGE_SHIFT) & (hpage_size - 1);
2827 if (offset && offset + len < 2 * hpage_size)
2828 return addr;
2829 if ((addr & (hpage_size - 1)) == offset)
2830 return addr;
2831
2832 inflated_len = len + hpage_size - PAGE_SIZE;
2833 if (inflated_len > TASK_SIZE)
2834 return addr;
2835 if (inflated_len < len)
2836 return addr;
2837
2838 inflated_addr = mm_get_unmapped_area(current->mm, NULL, addr: uaddr,
2839 len: inflated_len, pgoff: 0, flags);
2840 if (IS_ERR_VALUE(inflated_addr))
2841 return addr;
2842 if (inflated_addr & ~PAGE_MASK)
2843 return addr;
2844
2845 inflated_offset = inflated_addr & (hpage_size - 1);
2846 inflated_addr += offset - inflated_offset;
2847 if (inflated_offset > offset)
2848 inflated_addr += hpage_size;
2849
2850 if (inflated_addr > TASK_SIZE - len)
2851 return addr;
2852 return inflated_addr;
2853}
2854
2855#ifdef CONFIG_NUMA
2856static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2857{
2858 struct inode *inode = file_inode(f: vma->vm_file);
2859 return mpol_set_shared_policy(sp: &SHMEM_I(inode)->policy, vma, mpol);
2860}
2861
2862static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2863 unsigned long addr, pgoff_t *ilx)
2864{
2865 struct inode *inode = file_inode(f: vma->vm_file);
2866 pgoff_t index;
2867
2868 /*
2869 * Bias interleave by inode number to distribute better across nodes;
2870 * but this interface is independent of which page order is used, so
2871 * supplies only that bias, letting caller apply the offset (adjusted
2872 * by page order, as in shmem_get_pgoff_policy() and get_vma_policy()).
2873 */
2874 *ilx = inode->i_ino;
2875 index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2876 return mpol_shared_policy_lookup(sp: &SHMEM_I(inode)->policy, idx: index);
2877}
2878
2879static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
2880 pgoff_t index, unsigned int order, pgoff_t *ilx)
2881{
2882 struct mempolicy *mpol;
2883
2884 /* Bias interleave by inode number to distribute better across nodes */
2885 *ilx = info->vfs_inode.i_ino + (index >> order);
2886
2887 mpol = mpol_shared_policy_lookup(sp: &info->policy, idx: index);
2888 return mpol ? mpol : get_task_policy(current);
2889}
2890#else
2891static struct mempolicy *shmem_get_pgoff_policy(struct shmem_inode_info *info,
2892 pgoff_t index, unsigned int order, pgoff_t *ilx)
2893{
2894 *ilx = 0;
2895 return NULL;
2896}
2897#endif /* CONFIG_NUMA */
2898
2899int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
2900{
2901 struct inode *inode = file_inode(f: file);
2902 struct shmem_inode_info *info = SHMEM_I(inode);
2903 int retval = -ENOMEM;
2904
2905 /*
2906 * What serializes the accesses to info->flags?
2907 * ipc_lock_object() when called from shmctl_do_lock(),
2908 * no serialization needed when called from shm_destroy().
2909 */
2910 if (lock && !(info->flags & VM_LOCKED)) {
2911 if (!user_shm_lock(inode->i_size, ucounts))
2912 goto out_nomem;
2913 info->flags |= VM_LOCKED;
2914 mapping_set_unevictable(mapping: file->f_mapping);
2915 }
2916 if (!lock && (info->flags & VM_LOCKED) && ucounts) {
2917 user_shm_unlock(inode->i_size, ucounts);
2918 info->flags &= ~VM_LOCKED;
2919 mapping_clear_unevictable(mapping: file->f_mapping);
2920 }
2921 retval = 0;
2922
2923out_nomem:
2924 return retval;
2925}
2926
2927static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2928{
2929 struct inode *inode = file_inode(f: file);
2930
2931 file_accessed(file);
2932 /* This is anonymous shared memory if it is unlinked at the time of mmap */
2933 if (inode->i_nlink)
2934 vma->vm_ops = &shmem_vm_ops;
2935 else
2936 vma->vm_ops = &shmem_anon_vm_ops;
2937 return 0;
2938}
2939
2940static int shmem_file_open(struct inode *inode, struct file *file)
2941{
2942 file->f_mode |= FMODE_CAN_ODIRECT;
2943 return generic_file_open(inode, filp: file);
2944}
2945
2946#ifdef CONFIG_TMPFS_XATTR
2947static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2948
2949#if IS_ENABLED(CONFIG_UNICODE)
2950/*
2951 * shmem_inode_casefold_flags - Deal with casefold file attribute flag
2952 *
2953 * The casefold file attribute needs some special checks. I can just be added to
2954 * an empty dir, and can't be removed from a non-empty dir.
2955 */
2956static int shmem_inode_casefold_flags(struct inode *inode, unsigned int fsflags,
2957 struct dentry *dentry, unsigned int *i_flags)
2958{
2959 unsigned int old = inode->i_flags;
2960 struct super_block *sb = inode->i_sb;
2961
2962 if (fsflags & FS_CASEFOLD_FL) {
2963 if (!(old & S_CASEFOLD)) {
2964 if (!sb->s_encoding)
2965 return -EOPNOTSUPP;
2966
2967 if (!S_ISDIR(inode->i_mode))
2968 return -ENOTDIR;
2969
2970 if (dentry && !simple_empty(dentry))
2971 return -ENOTEMPTY;
2972 }
2973
2974 *i_flags = *i_flags | S_CASEFOLD;
2975 } else if (old & S_CASEFOLD) {
2976 if (dentry && !simple_empty(dentry))
2977 return -ENOTEMPTY;
2978 }
2979
2980 return 0;
2981}
2982#else
2983static int shmem_inode_casefold_flags(struct inode *inode, unsigned int fsflags,
2984 struct dentry *dentry, unsigned int *i_flags)
2985{
2986 if (fsflags & FS_CASEFOLD_FL)
2987 return -EOPNOTSUPP;
2988
2989 return 0;
2990}
2991#endif
2992
2993/*
2994 * chattr's fsflags are unrelated to extended attributes,
2995 * but tmpfs has chosen to enable them under the same config option.
2996 */
2997static int shmem_set_inode_flags(struct inode *inode, unsigned int fsflags, struct dentry *dentry)
2998{
2999 unsigned int i_flags = 0;
3000 int ret;
3001
3002 ret = shmem_inode_casefold_flags(inode, fsflags, dentry, i_flags: &i_flags);
3003 if (ret)
3004 return ret;
3005
3006 if (fsflags & FS_NOATIME_FL)
3007 i_flags |= S_NOATIME;
3008 if (fsflags & FS_APPEND_FL)
3009 i_flags |= S_APPEND;
3010 if (fsflags & FS_IMMUTABLE_FL)
3011 i_flags |= S_IMMUTABLE;
3012 /*
3013 * But FS_NODUMP_FL does not require any action in i_flags.
3014 */
3015 inode_set_flags(inode, flags: i_flags, S_NOATIME | S_APPEND | S_IMMUTABLE | S_CASEFOLD);
3016
3017 return 0;
3018}
3019#else
3020static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags, struct dentry *dentry)
3021{
3022}
3023#define shmem_initxattrs NULL
3024#endif
3025
3026static struct offset_ctx *shmem_get_offset_ctx(struct inode *inode)
3027{
3028 return &SHMEM_I(inode)->dir_offsets;
3029}
3030
3031static struct inode *__shmem_get_inode(struct mnt_idmap *idmap,
3032 struct super_block *sb,
3033 struct inode *dir, umode_t mode,
3034 dev_t dev, unsigned long flags)
3035{
3036 struct inode *inode;
3037 struct shmem_inode_info *info;
3038 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3039 ino_t ino;
3040 int err;
3041
3042 err = shmem_reserve_inode(sb, inop: &ino);
3043 if (err)
3044 return ERR_PTR(error: err);
3045
3046 inode = new_inode(sb);
3047 if (!inode) {
3048 shmem_free_inode(sb, freed_ispace: 0);
3049 return ERR_PTR(error: -ENOSPC);
3050 }
3051
3052 inode->i_ino = ino;
3053 inode_init_owner(idmap, inode, dir, mode);
3054 inode->i_blocks = 0;
3055 simple_inode_init_ts(inode);
3056 inode->i_generation = get_random_u32();
3057 info = SHMEM_I(inode);
3058 memset(s: info, c: 0, n: (char *)inode - (char *)info);
3059 spin_lock_init(&info->lock);
3060 atomic_set(v: &info->stop_eviction, i: 0);
3061 info->seals = F_SEAL_SEAL;
3062 info->flags = flags & VM_NORESERVE;
3063 info->i_crtime = inode_get_mtime(inode);
3064 info->fsflags = (dir == NULL) ? 0 :
3065 SHMEM_I(inode: dir)->fsflags & SHMEM_FL_INHERITED;
3066 if (info->fsflags)
3067 shmem_set_inode_flags(inode, fsflags: info->fsflags, NULL);
3068 INIT_LIST_HEAD(list: &info->shrinklist);
3069 INIT_LIST_HEAD(list: &info->swaplist);
3070 simple_xattrs_init(xattrs: &info->xattrs);
3071 cache_no_acl(inode);
3072 if (sbinfo->noswap)
3073 mapping_set_unevictable(mapping: inode->i_mapping);
3074
3075 /* Don't consider 'deny' for emergencies and 'force' for testing */
3076 if (sbinfo->huge)
3077 mapping_set_large_folios(mapping: inode->i_mapping);
3078
3079 switch (mode & S_IFMT) {
3080 default:
3081 inode->i_op = &shmem_special_inode_operations;
3082 init_special_inode(inode, mode, dev);
3083 break;
3084 case S_IFREG:
3085 inode->i_mapping->a_ops = &shmem_aops;
3086 inode->i_op = &shmem_inode_operations;
3087 inode->i_fop = &shmem_file_operations;
3088 mpol_shared_policy_init(sp: &info->policy,
3089 mpol: shmem_get_sbmpol(sbinfo));
3090 break;
3091 case S_IFDIR:
3092 inc_nlink(inode);
3093 /* Some things misbehave if size == 0 on a directory */
3094 inode->i_size = 2 * BOGO_DIRENT_SIZE;
3095 inode->i_op = &shmem_dir_inode_operations;
3096 inode->i_fop = &simple_offset_dir_operations;
3097 simple_offset_init(octx: shmem_get_offset_ctx(inode));
3098 break;
3099 case S_IFLNK:
3100 /*
3101 * Must not load anything in the rbtree,
3102 * mpol_free_shared_policy will not be called.
3103 */
3104 mpol_shared_policy_init(sp: &info->policy, NULL);
3105 break;
3106 }
3107
3108 lockdep_annotate_inode_mutex_key(inode);
3109 return inode;
3110}
3111
3112#ifdef CONFIG_TMPFS_QUOTA
3113static struct inode *shmem_get_inode(struct mnt_idmap *idmap,
3114 struct super_block *sb, struct inode *dir,
3115 umode_t mode, dev_t dev, unsigned long flags)
3116{
3117 int err;
3118 struct inode *inode;
3119
3120 inode = __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
3121 if (IS_ERR(inode))
3122 return inode;
3123
3124 err = dquot_initialize(inode);
3125 if (err)
3126 goto errout;
3127
3128 err = dquot_alloc_inode(inode);
3129 if (err) {
3130 dquot_drop(inode);
3131 goto errout;
3132 }
3133 return inode;
3134
3135errout:
3136 inode->i_flags |= S_NOQUOTA;
3137 iput(inode);
3138 return ERR_PTR(err);
3139}
3140#else
3141static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
3142 struct super_block *sb, struct inode *dir,
3143 umode_t mode, dev_t dev, unsigned long flags)
3144{
3145 return __shmem_get_inode(idmap, sb, dir, mode, dev, flags);
3146}
3147#endif /* CONFIG_TMPFS_QUOTA */
3148
3149#ifdef CONFIG_USERFAULTFD
3150int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
3151 struct vm_area_struct *dst_vma,
3152 unsigned long dst_addr,
3153 unsigned long src_addr,
3154 uffd_flags_t flags,
3155 struct folio **foliop)
3156{
3157 struct inode *inode = file_inode(dst_vma->vm_file);
3158 struct shmem_inode_info *info = SHMEM_I(inode);
3159 struct address_space *mapping = inode->i_mapping;
3160 gfp_t gfp = mapping_gfp_mask(mapping);
3161 pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
3162 void *page_kaddr;
3163 struct folio *folio;
3164 int ret;
3165 pgoff_t max_off;
3166
3167 if (shmem_inode_acct_blocks(inode, 1)) {
3168 /*
3169 * We may have got a page, returned -ENOENT triggering a retry,
3170 * and now we find ourselves with -ENOMEM. Release the page, to
3171 * avoid a BUG_ON in our caller.
3172 */
3173 if (unlikely(*foliop)) {
3174 folio_put(*foliop);
3175 *foliop = NULL;
3176 }
3177 return -ENOMEM;
3178 }
3179
3180 if (!*foliop) {
3181 ret = -ENOMEM;
3182 folio = shmem_alloc_folio(gfp, 0, info, pgoff);
3183 if (!folio)
3184 goto out_unacct_blocks;
3185
3186 if (uffd_flags_mode_is(flags, MFILL_ATOMIC_COPY)) {
3187 page_kaddr = kmap_local_folio(folio, 0);
3188 /*
3189 * The read mmap_lock is held here. Despite the
3190 * mmap_lock being read recursive a deadlock is still
3191 * possible if a writer has taken a lock. For example:
3192 *
3193 * process A thread 1 takes read lock on own mmap_lock
3194 * process A thread 2 calls mmap, blocks taking write lock
3195 * process B thread 1 takes page fault, read lock on own mmap lock
3196 * process B thread 2 calls mmap, blocks taking write lock
3197 * process A thread 1 blocks taking read lock on process B
3198 * process B thread 1 blocks taking read lock on process A
3199 *
3200 * Disable page faults to prevent potential deadlock
3201 * and retry the copy outside the mmap_lock.
3202 */
3203 pagefault_disable();
3204 ret = copy_from_user(page_kaddr,
3205 (const void __user *)src_addr,
3206 PAGE_SIZE);
3207 pagefault_enable();
3208 kunmap_local(page_kaddr);
3209
3210 /* fallback to copy_from_user outside mmap_lock */
3211 if (unlikely(ret)) {
3212 *foliop = folio;
3213 ret = -ENOENT;
3214 /* don't free the page */
3215 goto out_unacct_blocks;
3216 }
3217
3218 flush_dcache_folio(folio);
3219 } else { /* ZEROPAGE */
3220 clear_user_highpage(&folio->page, dst_addr);
3221 }
3222 } else {
3223 folio = *foliop;
3224 VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
3225 *foliop = NULL;
3226 }
3227
3228 VM_BUG_ON(folio_test_locked(folio));
3229 VM_BUG_ON(folio_test_swapbacked(folio));
3230 __folio_set_locked(folio);
3231 __folio_set_swapbacked(folio);
3232 __folio_mark_uptodate(folio);
3233
3234 ret = -EFAULT;
3235 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
3236 if (unlikely(pgoff >= max_off))
3237 goto out_release;
3238
3239 ret = mem_cgroup_charge(folio, dst_vma->vm_mm, gfp);
3240 if (ret)
3241 goto out_release;
3242 ret = shmem_add_to_page_cache(folio, mapping, pgoff, NULL, gfp);
3243 if (ret)
3244 goto out_release;
3245
3246 ret = mfill_atomic_install_pte(dst_pmd, dst_vma, dst_addr,
3247 &folio->page, true, flags);
3248 if (ret)
3249 goto out_delete_from_cache;
3250
3251 shmem_recalc_inode(inode, 1, 0);
3252 folio_unlock(folio);
3253 return 0;
3254out_delete_from_cache:
3255 filemap_remove_folio(folio);
3256out_release:
3257 folio_unlock(folio);
3258 folio_put(folio);
3259out_unacct_blocks:
3260 shmem_inode_unacct_blocks(inode, 1);
3261 return ret;
3262}
3263#endif /* CONFIG_USERFAULTFD */
3264
3265#ifdef CONFIG_TMPFS
3266static const struct inode_operations shmem_symlink_inode_operations;
3267static const struct inode_operations shmem_short_symlink_operations;
3268
3269static int
3270shmem_write_begin(const struct kiocb *iocb, struct address_space *mapping,
3271 loff_t pos, unsigned len,
3272 struct folio **foliop, void **fsdata)
3273{
3274 struct inode *inode = mapping->host;
3275 struct shmem_inode_info *info = SHMEM_I(inode);
3276 pgoff_t index = pos >> PAGE_SHIFT;
3277 struct folio *folio;
3278 int ret = 0;
3279
3280 /* i_rwsem is held by caller */
3281 if (unlikely(info->seals & (F_SEAL_GROW |
3282 F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))) {
3283 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE))
3284 return -EPERM;
3285 if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
3286 return -EPERM;
3287 }
3288
3289 ret = shmem_get_folio(inode, index, pos + len, &folio, SGP_WRITE);
3290 if (ret)
3291 return ret;
3292
3293 if (folio_contain_hwpoisoned_page(folio)) {
3294 folio_unlock(folio);
3295 folio_put(folio);
3296 return -EIO;
3297 }
3298
3299 *foliop = folio;
3300 return 0;
3301}
3302
3303static int
3304shmem_write_end(const struct kiocb *iocb, struct address_space *mapping,
3305 loff_t pos, unsigned len, unsigned copied,
3306 struct folio *folio, void *fsdata)
3307{
3308 struct inode *inode = mapping->host;
3309
3310 if (pos + copied > inode->i_size)
3311 i_size_write(inode, i_size: pos + copied);
3312
3313 if (!folio_test_uptodate(folio)) {
3314 if (copied < folio_size(folio)) {
3315 size_t from = offset_in_folio(folio, pos);
3316 folio_zero_segments(folio, start1: 0, xend1: from,
3317 start2: from + copied, xend2: folio_size(folio));
3318 }
3319 folio_mark_uptodate(folio);
3320 }
3321 folio_mark_dirty(folio);
3322 folio_unlock(folio);
3323 folio_put(folio);
3324
3325 return copied;
3326}
3327
3328static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
3329{
3330 struct file *file = iocb->ki_filp;
3331 struct inode *inode = file_inode(f: file);
3332 struct address_space *mapping = inode->i_mapping;
3333 pgoff_t index;
3334 unsigned long offset;
3335 int error = 0;
3336 ssize_t retval = 0;
3337
3338 for (;;) {
3339 struct folio *folio = NULL;
3340 struct page *page = NULL;
3341 unsigned long nr, ret;
3342 loff_t end_offset, i_size = i_size_read(inode);
3343 bool fallback_page_copy = false;
3344 size_t fsize;
3345
3346 if (unlikely(iocb->ki_pos >= i_size))
3347 break;
3348
3349 index = iocb->ki_pos >> PAGE_SHIFT;
3350 error = shmem_get_folio(inode, index, 0, &folio, SGP_READ);
3351 if (error) {
3352 if (error == -EINVAL)
3353 error = 0;
3354 break;
3355 }
3356 if (folio) {
3357 folio_unlock(folio);
3358
3359 page = folio_file_page(folio, index);
3360 if (PageHWPoison(page)) {
3361 folio_put(folio);
3362 error = -EIO;
3363 break;
3364 }
3365
3366 if (folio_test_large(folio) &&
3367 folio_test_has_hwpoisoned(folio))
3368 fallback_page_copy = true;
3369 }
3370
3371 /*
3372 * We must evaluate after, since reads (unlike writes)
3373 * are called without i_rwsem protection against truncate
3374 */
3375 i_size = i_size_read(inode);
3376 if (unlikely(iocb->ki_pos >= i_size)) {
3377 if (folio)
3378 folio_put(folio);
3379 break;
3380 }
3381 end_offset = min_t(loff_t, i_size, iocb->ki_pos + to->count);
3382 if (folio && likely(!fallback_page_copy))
3383 fsize = folio_size(folio);
3384 else
3385 fsize = PAGE_SIZE;
3386 offset = iocb->ki_pos & (fsize - 1);
3387 nr = min_t(loff_t, end_offset - iocb->ki_pos, fsize - offset);
3388
3389 if (folio) {
3390 /*
3391 * If users can be writing to this page using arbitrary
3392 * virtual addresses, take care about potential aliasing
3393 * before reading the page on the kernel side.
3394 */
3395 if (mapping_writably_mapped(mapping)) {
3396 if (likely(!fallback_page_copy))
3397 flush_dcache_folio(folio);
3398 else
3399 flush_dcache_page(page);
3400 }
3401
3402 /*
3403 * Mark the folio accessed if we read the beginning.
3404 */
3405 if (!offset)
3406 folio_mark_accessed(folio);
3407 /*
3408 * Ok, we have the page, and it's up-to-date, so
3409 * now we can copy it to user space...
3410 */
3411 if (likely(!fallback_page_copy))
3412 ret = copy_folio_to_iter(folio, offset, bytes: nr, i: to);
3413 else
3414 ret = copy_page_to_iter(page, offset, bytes: nr, i: to);
3415 folio_put(folio);
3416 } else if (user_backed_iter(i: to)) {
3417 /*
3418 * Copy to user tends to be so well optimized, but
3419 * clear_user() not so much, that it is noticeably
3420 * faster to copy the zero page instead of clearing.
3421 */
3422 ret = copy_page_to_iter(ZERO_PAGE(0), offset, bytes: nr, i: to);
3423 } else {
3424 /*
3425 * But submitting the same page twice in a row to
3426 * splice() - or others? - can result in confusion:
3427 * so don't attempt that optimization on pipes etc.
3428 */
3429 ret = iov_iter_zero(bytes: nr, to);
3430 }
3431
3432 retval += ret;
3433 iocb->ki_pos += ret;
3434
3435 if (!iov_iter_count(i: to))
3436 break;
3437 if (ret < nr) {
3438 error = -EFAULT;
3439 break;
3440 }
3441 cond_resched();
3442 }
3443
3444 file_accessed(file);
3445 return retval ? retval : error;
3446}
3447
3448static ssize_t shmem_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
3449{
3450 struct file *file = iocb->ki_filp;
3451 struct inode *inode = file->f_mapping->host;
3452 ssize_t ret;
3453
3454 inode_lock(inode);
3455 ret = generic_write_checks(iocb, from);
3456 if (ret <= 0)
3457 goto unlock;
3458 ret = file_remove_privs(file);
3459 if (ret)
3460 goto unlock;
3461 ret = file_update_time(file);
3462 if (ret)
3463 goto unlock;
3464 ret = generic_perform_write(iocb, from);
3465unlock:
3466 inode_unlock(inode);
3467 return ret;
3468}
3469
3470static bool zero_pipe_buf_get(struct pipe_inode_info *pipe,
3471 struct pipe_buffer *buf)
3472{
3473 return true;
3474}
3475
3476static void zero_pipe_buf_release(struct pipe_inode_info *pipe,
3477 struct pipe_buffer *buf)
3478{
3479}
3480
3481static bool zero_pipe_buf_try_steal(struct pipe_inode_info *pipe,
3482 struct pipe_buffer *buf)
3483{
3484 return false;
3485}
3486
3487static const struct pipe_buf_operations zero_pipe_buf_ops = {
3488 .release = zero_pipe_buf_release,
3489 .try_steal = zero_pipe_buf_try_steal,
3490 .get = zero_pipe_buf_get,
3491};
3492
3493static size_t splice_zeropage_into_pipe(struct pipe_inode_info *pipe,
3494 loff_t fpos, size_t size)
3495{
3496 size_t offset = fpos & ~PAGE_MASK;
3497
3498 size = min_t(size_t, size, PAGE_SIZE - offset);
3499
3500 if (!pipe_is_full(pipe)) {
3501 struct pipe_buffer *buf = pipe_head_buf(pipe);
3502
3503 *buf = (struct pipe_buffer) {
3504 .ops = &zero_pipe_buf_ops,
3505 .page = ZERO_PAGE(0),
3506 .offset = offset,
3507 .len = size,
3508 };
3509 pipe->head++;
3510 }
3511
3512 return size;
3513}
3514
3515static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
3516 struct pipe_inode_info *pipe,
3517 size_t len, unsigned int flags)
3518{
3519 struct inode *inode = file_inode(f: in);
3520 struct address_space *mapping = inode->i_mapping;
3521 struct folio *folio = NULL;
3522 size_t total_spliced = 0, used, npages, n, part;
3523 loff_t isize;
3524 int error = 0;
3525
3526 /* Work out how much data we can actually add into the pipe */
3527 used = pipe_buf_usage(pipe);
3528 npages = max_t(ssize_t, pipe->max_usage - used, 0);
3529 len = min_t(size_t, len, npages * PAGE_SIZE);
3530
3531 do {
3532 bool fallback_page_splice = false;
3533 struct page *page = NULL;
3534 pgoff_t index;
3535 size_t size;
3536
3537 if (*ppos >= i_size_read(inode))
3538 break;
3539
3540 index = *ppos >> PAGE_SHIFT;
3541 error = shmem_get_folio(inode, index, 0, &folio, SGP_READ);
3542 if (error) {
3543 if (error == -EINVAL)
3544 error = 0;
3545 break;
3546 }
3547 if (folio) {
3548 folio_unlock(folio);
3549
3550 page = folio_file_page(folio, index);
3551 if (PageHWPoison(page)) {
3552 error = -EIO;
3553 break;
3554 }
3555
3556 if (folio_test_large(folio) &&
3557 folio_test_has_hwpoisoned(folio))
3558 fallback_page_splice = true;
3559 }
3560
3561 /*
3562 * i_size must be checked after we know the pages are Uptodate.
3563 *
3564 * Checking i_size after the check allows us to calculate
3565 * the correct value for "nr", which means the zero-filled
3566 * part of the page is not copied back to userspace (unless
3567 * another truncate extends the file - this is desired though).
3568 */
3569 isize = i_size_read(inode);
3570 if (unlikely(*ppos >= isize))
3571 break;
3572 /*
3573 * Fallback to PAGE_SIZE splice if the large folio has hwpoisoned
3574 * pages.
3575 */
3576 size = len;
3577 if (unlikely(fallback_page_splice)) {
3578 size_t offset = *ppos & ~PAGE_MASK;
3579
3580 size = umin(size, PAGE_SIZE - offset);
3581 }
3582 part = min_t(loff_t, isize - *ppos, size);
3583
3584 if (folio) {
3585 /*
3586 * If users can be writing to this page using arbitrary
3587 * virtual addresses, take care about potential aliasing
3588 * before reading the page on the kernel side.
3589 */
3590 if (mapping_writably_mapped(mapping)) {
3591 if (likely(!fallback_page_splice))
3592 flush_dcache_folio(folio);
3593 else
3594 flush_dcache_page(page);
3595 }
3596 folio_mark_accessed(folio);
3597 /*
3598 * Ok, we have the page, and it's up-to-date, so we can
3599 * now splice it into the pipe.
3600 */
3601 n = splice_folio_into_pipe(pipe, folio, fpos: *ppos, size: part);
3602 folio_put(folio);
3603 folio = NULL;
3604 } else {
3605 n = splice_zeropage_into_pipe(pipe, fpos: *ppos, size: part);
3606 }
3607
3608 if (!n)
3609 break;
3610 len -= n;
3611 total_spliced += n;
3612 *ppos += n;
3613 in->f_ra.prev_pos = *ppos;
3614 if (pipe_is_full(pipe))
3615 break;
3616
3617 cond_resched();
3618 } while (len);
3619
3620 if (folio)
3621 folio_put(folio);
3622
3623 file_accessed(file: in);
3624 return total_spliced ? total_spliced : error;
3625}
3626
3627static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
3628{
3629 struct address_space *mapping = file->f_mapping;
3630 struct inode *inode = mapping->host;
3631
3632 if (whence != SEEK_DATA && whence != SEEK_HOLE)
3633 return generic_file_llseek_size(file, offset, whence,
3634 MAX_LFS_FILESIZE, eof: i_size_read(inode));
3635 if (offset < 0)
3636 return -ENXIO;
3637
3638 inode_lock(inode);
3639 /* We're holding i_rwsem so we can access i_size directly */
3640 offset = mapping_seek_hole_data(mapping, start: offset, end: inode->i_size, whence);
3641 if (offset >= 0)
3642 offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
3643 inode_unlock(inode);
3644 return offset;
3645}
3646
3647static long shmem_fallocate(struct file *file, int mode, loff_t offset,
3648 loff_t len)
3649{
3650 struct inode *inode = file_inode(f: file);
3651 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
3652 struct shmem_inode_info *info = SHMEM_I(inode);
3653 struct shmem_falloc shmem_falloc;
3654 pgoff_t start, index, end, undo_fallocend;
3655 int error;
3656
3657 if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
3658 return -EOPNOTSUPP;
3659
3660 inode_lock(inode);
3661
3662 if (mode & FALLOC_FL_PUNCH_HOLE) {
3663 struct address_space *mapping = file->f_mapping;
3664 loff_t unmap_start = round_up(offset, PAGE_SIZE);
3665 loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
3666 DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
3667
3668 /* protected by i_rwsem */
3669 if (info->seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) {
3670 error = -EPERM;
3671 goto out;
3672 }
3673
3674 shmem_falloc.waitq = &shmem_falloc_waitq;
3675 shmem_falloc.start = (u64)unmap_start >> PAGE_SHIFT;
3676 shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
3677 spin_lock(lock: &inode->i_lock);
3678 inode->i_private = &shmem_falloc;
3679 spin_unlock(lock: &inode->i_lock);
3680
3681 if ((u64)unmap_end > (u64)unmap_start)
3682 unmap_mapping_range(mapping, holebegin: unmap_start,
3683 holelen: 1 + unmap_end - unmap_start, even_cows: 0);
3684 shmem_truncate_range(inode, offset, offset + len - 1);
3685 /* No need to unmap again: hole-punching leaves COWed pages */
3686
3687 spin_lock(lock: &inode->i_lock);
3688 inode->i_private = NULL;
3689 wake_up_all(&shmem_falloc_waitq);
3690 WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
3691 spin_unlock(lock: &inode->i_lock);
3692 error = 0;
3693 goto out;
3694 }
3695
3696 /* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
3697 error = inode_newsize_ok(inode, offset: offset + len);
3698 if (error)
3699 goto out;
3700
3701 if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
3702 error = -EPERM;
3703 goto out;
3704 }
3705
3706 start = offset >> PAGE_SHIFT;
3707 end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
3708 /* Try to avoid a swapstorm if len is impossible to satisfy */
3709 if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
3710 error = -ENOSPC;
3711 goto out;
3712 }
3713
3714 shmem_falloc.waitq = NULL;
3715 shmem_falloc.start = start;
3716 shmem_falloc.next = start;
3717 shmem_falloc.nr_falloced = 0;
3718 shmem_falloc.nr_unswapped = 0;
3719 spin_lock(lock: &inode->i_lock);
3720 inode->i_private = &shmem_falloc;
3721 spin_unlock(lock: &inode->i_lock);
3722
3723 /*
3724 * info->fallocend is only relevant when huge pages might be
3725 * involved: to prevent split_huge_page() freeing fallocated
3726 * pages when FALLOC_FL_KEEP_SIZE committed beyond i_size.
3727 */
3728 undo_fallocend = info->fallocend;
3729 if (info->fallocend < end)
3730 info->fallocend = end;
3731
3732 for (index = start; index < end; ) {
3733 struct folio *folio;
3734
3735 /*
3736 * Check for fatal signal so that we abort early in OOM
3737 * situations. We don't want to abort in case of non-fatal
3738 * signals as large fallocate can take noticeable time and
3739 * e.g. periodic timers may result in fallocate constantly
3740 * restarting.
3741 */
3742 if (fatal_signal_pending(current))
3743 error = -EINTR;
3744 else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
3745 error = -ENOMEM;
3746 else
3747 error = shmem_get_folio(inode, index, offset + len,
3748 &folio, SGP_FALLOC);
3749 if (error) {
3750 info->fallocend = undo_fallocend;
3751 /* Remove the !uptodate folios we added */
3752 if (index > start) {
3753 shmem_undo_range(inode,
3754 lstart: (loff_t)start << PAGE_SHIFT,
3755 lend: ((loff_t)index << PAGE_SHIFT) - 1, unfalloc: true);
3756 }
3757 goto undone;
3758 }
3759
3760 /*
3761 * Here is a more important optimization than it appears:
3762 * a second SGP_FALLOC on the same large folio will clear it,
3763 * making it uptodate and un-undoable if we fail later.
3764 */
3765 index = folio_next_index(folio);
3766 /* Beware 32-bit wraparound */
3767 if (!index)
3768 index--;
3769
3770 /*
3771 * Inform shmem_writeout() how far we have reached.
3772 * No need for lock or barrier: we have the page lock.
3773 */
3774 if (!folio_test_uptodate(folio))
3775 shmem_falloc.nr_falloced += index - shmem_falloc.next;
3776 shmem_falloc.next = index;
3777
3778 /*
3779 * If !uptodate, leave it that way so that freeable folios
3780 * can be recognized if we need to rollback on error later.
3781 * But mark it dirty so that memory pressure will swap rather
3782 * than free the folios we are allocating (and SGP_CACHE folios
3783 * might still be clean: we now need to mark those dirty too).
3784 */
3785 folio_mark_dirty(folio);
3786 folio_unlock(folio);
3787 folio_put(folio);
3788 cond_resched();
3789 }
3790
3791 if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
3792 i_size_write(inode, i_size: offset + len);
3793undone:
3794 spin_lock(lock: &inode->i_lock);
3795 inode->i_private = NULL;
3796 spin_unlock(lock: &inode->i_lock);
3797out:
3798 if (!error)
3799 file_modified(file);
3800 inode_unlock(inode);
3801 return error;
3802}
3803
3804static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
3805{
3806 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: dentry->d_sb);
3807
3808 buf->f_type = TMPFS_MAGIC;
3809 buf->f_bsize = PAGE_SIZE;
3810 buf->f_namelen = NAME_MAX;
3811 if (sbinfo->max_blocks) {
3812 buf->f_blocks = sbinfo->max_blocks;
3813 buf->f_bavail =
3814 buf->f_bfree = sbinfo->max_blocks -
3815 percpu_counter_sum(fbc: &sbinfo->used_blocks);
3816 }
3817 if (sbinfo->max_inodes) {
3818 buf->f_files = sbinfo->max_inodes;
3819 buf->f_ffree = sbinfo->free_ispace / BOGO_INODE_SIZE;
3820 }
3821 /* else leave those fields 0 like simple_statfs */
3822
3823 buf->f_fsid = uuid_to_fsid(uuid: dentry->d_sb->s_uuid.b);
3824
3825 return 0;
3826}
3827
3828/*
3829 * File creation. Allocate an inode, and we're done..
3830 */
3831static int
3832shmem_mknod(struct mnt_idmap *idmap, struct inode *dir,
3833 struct dentry *dentry, umode_t mode, dev_t dev)
3834{
3835 struct inode *inode;
3836 int error;
3837
3838 if (!generic_ci_validate_strict_name(dir, name: &dentry->d_name))
3839 return -EINVAL;
3840
3841 inode = shmem_get_inode(idmap, sb: dir->i_sb, dir, mode, dev, VM_NORESERVE);
3842 if (IS_ERR(ptr: inode))
3843 return PTR_ERR(ptr: inode);
3844
3845 error = simple_acl_create(dir, inode);
3846 if (error)
3847 goto out_iput;
3848 error = security_inode_init_security(inode, dir, qstr: &dentry->d_name,
3849 initxattrs: shmem_initxattrs, NULL);
3850 if (error && error != -EOPNOTSUPP)
3851 goto out_iput;
3852
3853 error = simple_offset_add(octx: shmem_get_offset_ctx(inode: dir), dentry);
3854 if (error)
3855 goto out_iput;
3856
3857 dir->i_size += BOGO_DIRENT_SIZE;
3858 inode_set_mtime_to_ts(inode: dir, ts: inode_set_ctime_current(inode: dir));
3859 inode_inc_iversion(inode: dir);
3860
3861 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
3862 d_add(dentry, inode);
3863 else
3864 d_instantiate(dentry, inode);
3865
3866 dget(dentry); /* Extra count - pin the dentry in core */
3867 return error;
3868
3869out_iput:
3870 iput(inode);
3871 return error;
3872}
3873
3874static int
3875shmem_tmpfile(struct mnt_idmap *idmap, struct inode *dir,
3876 struct file *file, umode_t mode)
3877{
3878 struct inode *inode;
3879 int error;
3880
3881 inode = shmem_get_inode(idmap, sb: dir->i_sb, dir, mode, dev: 0, VM_NORESERVE);
3882 if (IS_ERR(ptr: inode)) {
3883 error = PTR_ERR(ptr: inode);
3884 goto err_out;
3885 }
3886 error = security_inode_init_security(inode, dir, NULL,
3887 initxattrs: shmem_initxattrs, NULL);
3888 if (error && error != -EOPNOTSUPP)
3889 goto out_iput;
3890 error = simple_acl_create(dir, inode);
3891 if (error)
3892 goto out_iput;
3893 d_tmpfile(file, inode);
3894
3895err_out:
3896 return finish_open_simple(file, error);
3897out_iput:
3898 iput(inode);
3899 return error;
3900}
3901
3902static struct dentry *shmem_mkdir(struct mnt_idmap *idmap, struct inode *dir,
3903 struct dentry *dentry, umode_t mode)
3904{
3905 int error;
3906
3907 error = shmem_mknod(idmap, dir, dentry, mode: mode | S_IFDIR, dev: 0);
3908 if (error)
3909 return ERR_PTR(error);
3910 inc_nlink(inode: dir);
3911 return NULL;
3912}
3913
3914static int shmem_create(struct mnt_idmap *idmap, struct inode *dir,
3915 struct dentry *dentry, umode_t mode, bool excl)
3916{
3917 return shmem_mknod(idmap, dir, dentry, mode: mode | S_IFREG, dev: 0);
3918}
3919
3920/*
3921 * Link a file..
3922 */
3923static int shmem_link(struct dentry *old_dentry, struct inode *dir,
3924 struct dentry *dentry)
3925{
3926 struct inode *inode = d_inode(dentry: old_dentry);
3927 int ret = 0;
3928
3929 /*
3930 * No ordinary (disk based) filesystem counts links as inodes;
3931 * but each new link needs a new dentry, pinning lowmem, and
3932 * tmpfs dentries cannot be pruned until they are unlinked.
3933 * But if an O_TMPFILE file is linked into the tmpfs, the
3934 * first link must skip that, to get the accounting right.
3935 */
3936 if (inode->i_nlink) {
3937 ret = shmem_reserve_inode(sb: inode->i_sb, NULL);
3938 if (ret)
3939 goto out;
3940 }
3941
3942 ret = simple_offset_add(octx: shmem_get_offset_ctx(inode: dir), dentry);
3943 if (ret) {
3944 if (inode->i_nlink)
3945 shmem_free_inode(sb: inode->i_sb, freed_ispace: 0);
3946 goto out;
3947 }
3948
3949 dir->i_size += BOGO_DIRENT_SIZE;
3950 inode_set_mtime_to_ts(inode: dir,
3951 ts: inode_set_ctime_to_ts(inode: dir, ts: inode_set_ctime_current(inode)));
3952 inode_inc_iversion(inode: dir);
3953 inc_nlink(inode);
3954 ihold(inode); /* New dentry reference */
3955 dget(dentry); /* Extra pinning count for the created dentry */
3956 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
3957 d_add(dentry, inode);
3958 else
3959 d_instantiate(dentry, inode);
3960out:
3961 return ret;
3962}
3963
3964static int shmem_unlink(struct inode *dir, struct dentry *dentry)
3965{
3966 struct inode *inode = d_inode(dentry);
3967
3968 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
3969 shmem_free_inode(sb: inode->i_sb, freed_ispace: 0);
3970
3971 simple_offset_remove(octx: shmem_get_offset_ctx(inode: dir), dentry);
3972
3973 dir->i_size -= BOGO_DIRENT_SIZE;
3974 inode_set_mtime_to_ts(inode: dir,
3975 ts: inode_set_ctime_to_ts(inode: dir, ts: inode_set_ctime_current(inode)));
3976 inode_inc_iversion(inode: dir);
3977 drop_nlink(inode);
3978 dput(dentry); /* Undo the count from "create" - does all the work */
3979
3980 /*
3981 * For now, VFS can't deal with case-insensitive negative dentries, so
3982 * we invalidate them
3983 */
3984 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
3985 d_invalidate(dentry);
3986
3987 return 0;
3988}
3989
3990static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3991{
3992 if (!simple_empty(dentry))
3993 return -ENOTEMPTY;
3994
3995 drop_nlink(inode: d_inode(dentry));
3996 drop_nlink(inode: dir);
3997 return shmem_unlink(dir, dentry);
3998}
3999
4000static int shmem_whiteout(struct mnt_idmap *idmap,
4001 struct inode *old_dir, struct dentry *old_dentry)
4002{
4003 struct dentry *whiteout;
4004 int error;
4005
4006 whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
4007 if (!whiteout)
4008 return -ENOMEM;
4009
4010 error = shmem_mknod(idmap, dir: old_dir, dentry: whiteout,
4011 S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
4012 dput(whiteout);
4013 if (error)
4014 return error;
4015
4016 /*
4017 * Cheat and hash the whiteout while the old dentry is still in
4018 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
4019 *
4020 * d_lookup() will consistently find one of them at this point,
4021 * not sure which one, but that isn't even important.
4022 */
4023 d_rehash(whiteout);
4024 return 0;
4025}
4026
4027/*
4028 * The VFS layer already does all the dentry stuff for rename,
4029 * we just have to decrement the usage count for the target if
4030 * it exists so that the VFS layer correctly free's it when it
4031 * gets overwritten.
4032 */
4033static int shmem_rename2(struct mnt_idmap *idmap,
4034 struct inode *old_dir, struct dentry *old_dentry,
4035 struct inode *new_dir, struct dentry *new_dentry,
4036 unsigned int flags)
4037{
4038 struct inode *inode = d_inode(dentry: old_dentry);
4039 int they_are_dirs = S_ISDIR(inode->i_mode);
4040 int error;
4041
4042 if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
4043 return -EINVAL;
4044
4045 if (flags & RENAME_EXCHANGE)
4046 return simple_offset_rename_exchange(old_dir, old_dentry,
4047 new_dir, new_dentry);
4048
4049 if (!simple_empty(new_dentry))
4050 return -ENOTEMPTY;
4051
4052 if (flags & RENAME_WHITEOUT) {
4053 error = shmem_whiteout(idmap, old_dir, old_dentry);
4054 if (error)
4055 return error;
4056 }
4057
4058 error = simple_offset_rename(old_dir, old_dentry, new_dir, new_dentry);
4059 if (error)
4060 return error;
4061
4062 if (d_really_is_positive(dentry: new_dentry)) {
4063 (void) shmem_unlink(dir: new_dir, dentry: new_dentry);
4064 if (they_are_dirs) {
4065 drop_nlink(inode: d_inode(dentry: new_dentry));
4066 drop_nlink(inode: old_dir);
4067 }
4068 } else if (they_are_dirs) {
4069 drop_nlink(inode: old_dir);
4070 inc_nlink(inode: new_dir);
4071 }
4072
4073 old_dir->i_size -= BOGO_DIRENT_SIZE;
4074 new_dir->i_size += BOGO_DIRENT_SIZE;
4075 simple_rename_timestamp(old_dir, old_dentry, new_dir, new_dentry);
4076 inode_inc_iversion(inode: old_dir);
4077 inode_inc_iversion(inode: new_dir);
4078 return 0;
4079}
4080
4081static int shmem_symlink(struct mnt_idmap *idmap, struct inode *dir,
4082 struct dentry *dentry, const char *symname)
4083{
4084 int error;
4085 int len;
4086 struct inode *inode;
4087 struct folio *folio;
4088 char *link;
4089
4090 len = strlen(symname) + 1;
4091 if (len > PAGE_SIZE)
4092 return -ENAMETOOLONG;
4093
4094 inode = shmem_get_inode(idmap, sb: dir->i_sb, dir, S_IFLNK | 0777, dev: 0,
4095 VM_NORESERVE);
4096 if (IS_ERR(ptr: inode))
4097 return PTR_ERR(ptr: inode);
4098
4099 error = security_inode_init_security(inode, dir, qstr: &dentry->d_name,
4100 initxattrs: shmem_initxattrs, NULL);
4101 if (error && error != -EOPNOTSUPP)
4102 goto out_iput;
4103
4104 error = simple_offset_add(octx: shmem_get_offset_ctx(inode: dir), dentry);
4105 if (error)
4106 goto out_iput;
4107
4108 inode->i_size = len-1;
4109 if (len <= SHORT_SYMLINK_LEN) {
4110 link = kmemdup(symname, len, GFP_KERNEL);
4111 if (!link) {
4112 error = -ENOMEM;
4113 goto out_remove_offset;
4114 }
4115 inode->i_op = &shmem_short_symlink_operations;
4116 inode_set_cached_link(inode, link, linklen: len - 1);
4117 } else {
4118 inode_nohighmem(inode);
4119 inode->i_mapping->a_ops = &shmem_aops;
4120 error = shmem_get_folio(inode, 0, 0, &folio, SGP_WRITE);
4121 if (error)
4122 goto out_remove_offset;
4123 inode->i_op = &shmem_symlink_inode_operations;
4124 memcpy(to: folio_address(folio), from: symname, len);
4125 folio_mark_uptodate(folio);
4126 folio_mark_dirty(folio);
4127 folio_unlock(folio);
4128 folio_put(folio);
4129 }
4130 dir->i_size += BOGO_DIRENT_SIZE;
4131 inode_set_mtime_to_ts(inode: dir, ts: inode_set_ctime_current(inode: dir));
4132 inode_inc_iversion(inode: dir);
4133 if (IS_ENABLED(CONFIG_UNICODE) && IS_CASEFOLDED(dir))
4134 d_add(dentry, inode);
4135 else
4136 d_instantiate(dentry, inode);
4137 dget(dentry);
4138 return 0;
4139
4140out_remove_offset:
4141 simple_offset_remove(octx: shmem_get_offset_ctx(inode: dir), dentry);
4142out_iput:
4143 iput(inode);
4144 return error;
4145}
4146
4147static void shmem_put_link(void *arg)
4148{
4149 folio_mark_accessed(arg);
4150 folio_put(folio: arg);
4151}
4152
4153static const char *shmem_get_link(struct dentry *dentry, struct inode *inode,
4154 struct delayed_call *done)
4155{
4156 struct folio *folio = NULL;
4157 int error;
4158
4159 if (!dentry) {
4160 folio = filemap_get_folio(mapping: inode->i_mapping, index: 0);
4161 if (IS_ERR(ptr: folio))
4162 return ERR_PTR(error: -ECHILD);
4163 if (PageHWPoison(folio_page(folio, 0)) ||
4164 !folio_test_uptodate(folio)) {
4165 folio_put(folio);
4166 return ERR_PTR(error: -ECHILD);
4167 }
4168 } else {
4169 error = shmem_get_folio(inode, 0, 0, &folio, SGP_READ);
4170 if (error)
4171 return ERR_PTR(error);
4172 if (!folio)
4173 return ERR_PTR(error: -ECHILD);
4174 if (PageHWPoison(folio_page(folio, 0))) {
4175 folio_unlock(folio);
4176 folio_put(folio);
4177 return ERR_PTR(error: -ECHILD);
4178 }
4179 folio_unlock(folio);
4180 }
4181 set_delayed_call(call: done, fn: shmem_put_link, arg: folio);
4182 return folio_address(folio);
4183}
4184
4185#ifdef CONFIG_TMPFS_XATTR
4186
4187static int shmem_fileattr_get(struct dentry *dentry, struct file_kattr *fa)
4188{
4189 struct shmem_inode_info *info = SHMEM_I(inode: d_inode(dentry));
4190
4191 fileattr_fill_flags(fa, flags: info->fsflags & SHMEM_FL_USER_VISIBLE);
4192
4193 return 0;
4194}
4195
4196static int shmem_fileattr_set(struct mnt_idmap *idmap,
4197 struct dentry *dentry, struct file_kattr *fa)
4198{
4199 struct inode *inode = d_inode(dentry);
4200 struct shmem_inode_info *info = SHMEM_I(inode);
4201 int ret, flags;
4202
4203 if (fileattr_has_fsx(fa))
4204 return -EOPNOTSUPP;
4205 if (fa->flags & ~SHMEM_FL_USER_MODIFIABLE)
4206 return -EOPNOTSUPP;
4207
4208 flags = (info->fsflags & ~SHMEM_FL_USER_MODIFIABLE) |
4209 (fa->flags & SHMEM_FL_USER_MODIFIABLE);
4210
4211 ret = shmem_set_inode_flags(inode, fsflags: flags, dentry);
4212
4213 if (ret)
4214 return ret;
4215
4216 info->fsflags = flags;
4217
4218 inode_set_ctime_current(inode);
4219 inode_inc_iversion(inode);
4220 return 0;
4221}
4222
4223/*
4224 * Superblocks without xattr inode operations may get some security.* xattr
4225 * support from the LSM "for free". As soon as we have any other xattrs
4226 * like ACLs, we also need to implement the security.* handlers at
4227 * filesystem level, though.
4228 */
4229
4230/*
4231 * Callback for security_inode_init_security() for acquiring xattrs.
4232 */
4233static int shmem_initxattrs(struct inode *inode,
4234 const struct xattr *xattr_array, void *fs_info)
4235{
4236 struct shmem_inode_info *info = SHMEM_I(inode);
4237 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
4238 const struct xattr *xattr;
4239 struct simple_xattr *new_xattr;
4240 size_t ispace = 0;
4241 size_t len;
4242
4243 if (sbinfo->max_inodes) {
4244 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
4245 ispace += simple_xattr_space(name: xattr->name,
4246 size: xattr->value_len + XATTR_SECURITY_PREFIX_LEN);
4247 }
4248 if (ispace) {
4249 raw_spin_lock(&sbinfo->stat_lock);
4250 if (sbinfo->free_ispace < ispace)
4251 ispace = 0;
4252 else
4253 sbinfo->free_ispace -= ispace;
4254 raw_spin_unlock(&sbinfo->stat_lock);
4255 if (!ispace)
4256 return -ENOSPC;
4257 }
4258 }
4259
4260 for (xattr = xattr_array; xattr->name != NULL; xattr++) {
4261 new_xattr = simple_xattr_alloc(value: xattr->value, size: xattr->value_len);
4262 if (!new_xattr)
4263 break;
4264
4265 len = strlen(xattr->name) + 1;
4266 new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
4267 GFP_KERNEL_ACCOUNT);
4268 if (!new_xattr->name) {
4269 kvfree(addr: new_xattr);
4270 break;
4271 }
4272
4273 memcpy(to: new_xattr->name, XATTR_SECURITY_PREFIX,
4274 XATTR_SECURITY_PREFIX_LEN);
4275 memcpy(to: new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
4276 from: xattr->name, len);
4277
4278 simple_xattr_add(xattrs: &info->xattrs, new_xattr);
4279 }
4280
4281 if (xattr->name != NULL) {
4282 if (ispace) {
4283 raw_spin_lock(&sbinfo->stat_lock);
4284 sbinfo->free_ispace += ispace;
4285 raw_spin_unlock(&sbinfo->stat_lock);
4286 }
4287 simple_xattrs_free(xattrs: &info->xattrs, NULL);
4288 return -ENOMEM;
4289 }
4290
4291 return 0;
4292}
4293
4294static int shmem_xattr_handler_get(const struct xattr_handler *handler,
4295 struct dentry *unused, struct inode *inode,
4296 const char *name, void *buffer, size_t size)
4297{
4298 struct shmem_inode_info *info = SHMEM_I(inode);
4299
4300 name = xattr_full_name(handler, name);
4301 return simple_xattr_get(xattrs: &info->xattrs, name, buffer, size);
4302}
4303
4304static int shmem_xattr_handler_set(const struct xattr_handler *handler,
4305 struct mnt_idmap *idmap,
4306 struct dentry *unused, struct inode *inode,
4307 const char *name, const void *value,
4308 size_t size, int flags)
4309{
4310 struct shmem_inode_info *info = SHMEM_I(inode);
4311 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: inode->i_sb);
4312 struct simple_xattr *old_xattr;
4313 size_t ispace = 0;
4314
4315 name = xattr_full_name(handler, name);
4316 if (value && sbinfo->max_inodes) {
4317 ispace = simple_xattr_space(name, size);
4318 raw_spin_lock(&sbinfo->stat_lock);
4319 if (sbinfo->free_ispace < ispace)
4320 ispace = 0;
4321 else
4322 sbinfo->free_ispace -= ispace;
4323 raw_spin_unlock(&sbinfo->stat_lock);
4324 if (!ispace)
4325 return -ENOSPC;
4326 }
4327
4328 old_xattr = simple_xattr_set(xattrs: &info->xattrs, name, value, size, flags);
4329 if (!IS_ERR(ptr: old_xattr)) {
4330 ispace = 0;
4331 if (old_xattr && sbinfo->max_inodes)
4332 ispace = simple_xattr_space(name: old_xattr->name,
4333 size: old_xattr->size);
4334 simple_xattr_free(xattr: old_xattr);
4335 old_xattr = NULL;
4336 inode_set_ctime_current(inode);
4337 inode_inc_iversion(inode);
4338 }
4339 if (ispace) {
4340 raw_spin_lock(&sbinfo->stat_lock);
4341 sbinfo->free_ispace += ispace;
4342 raw_spin_unlock(&sbinfo->stat_lock);
4343 }
4344 return PTR_ERR(ptr: old_xattr);
4345}
4346
4347static const struct xattr_handler shmem_security_xattr_handler = {
4348 .prefix = XATTR_SECURITY_PREFIX,
4349 .get = shmem_xattr_handler_get,
4350 .set = shmem_xattr_handler_set,
4351};
4352
4353static const struct xattr_handler shmem_trusted_xattr_handler = {
4354 .prefix = XATTR_TRUSTED_PREFIX,
4355 .get = shmem_xattr_handler_get,
4356 .set = shmem_xattr_handler_set,
4357};
4358
4359static const struct xattr_handler shmem_user_xattr_handler = {
4360 .prefix = XATTR_USER_PREFIX,
4361 .get = shmem_xattr_handler_get,
4362 .set = shmem_xattr_handler_set,
4363};
4364
4365static const struct xattr_handler * const shmem_xattr_handlers[] = {
4366 &shmem_security_xattr_handler,
4367 &shmem_trusted_xattr_handler,
4368 &shmem_user_xattr_handler,
4369 NULL
4370};
4371
4372static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
4373{
4374 struct shmem_inode_info *info = SHMEM_I(inode: d_inode(dentry));
4375 return simple_xattr_list(inode: d_inode(dentry), xattrs: &info->xattrs, buffer, size);
4376}
4377#endif /* CONFIG_TMPFS_XATTR */
4378
4379static const struct inode_operations shmem_short_symlink_operations = {
4380 .getattr = shmem_getattr,
4381 .setattr = shmem_setattr,
4382 .get_link = simple_get_link,
4383#ifdef CONFIG_TMPFS_XATTR
4384 .listxattr = shmem_listxattr,
4385#endif
4386};
4387
4388static const struct inode_operations shmem_symlink_inode_operations = {
4389 .getattr = shmem_getattr,
4390 .setattr = shmem_setattr,
4391 .get_link = shmem_get_link,
4392#ifdef CONFIG_TMPFS_XATTR
4393 .listxattr = shmem_listxattr,
4394#endif
4395};
4396
4397static struct dentry *shmem_get_parent(struct dentry *child)
4398{
4399 return ERR_PTR(error: -ESTALE);
4400}
4401
4402static int shmem_match(struct inode *ino, void *vfh)
4403{
4404 __u32 *fh = vfh;
4405 __u64 inum = fh[2];
4406 inum = (inum << 32) | fh[1];
4407 return ino->i_ino == inum && fh[0] == ino->i_generation;
4408}
4409
4410/* Find any alias of inode, but prefer a hashed alias */
4411static struct dentry *shmem_find_alias(struct inode *inode)
4412{
4413 struct dentry *alias = d_find_alias(inode);
4414
4415 return alias ?: d_find_any_alias(inode);
4416}
4417
4418static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
4419 struct fid *fid, int fh_len, int fh_type)
4420{
4421 struct inode *inode;
4422 struct dentry *dentry = NULL;
4423 u64 inum;
4424
4425 if (fh_len < 3)
4426 return NULL;
4427
4428 inum = fid->raw[2];
4429 inum = (inum << 32) | fid->raw[1];
4430
4431 inode = ilookup5(sb, hashval: (unsigned long)(inum + fid->raw[0]),
4432 test: shmem_match, data: fid->raw);
4433 if (inode) {
4434 dentry = shmem_find_alias(inode);
4435 iput(inode);
4436 }
4437
4438 return dentry;
4439}
4440
4441static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
4442 struct inode *parent)
4443{
4444 if (*len < 3) {
4445 *len = 3;
4446 return FILEID_INVALID;
4447 }
4448
4449 if (inode_unhashed(inode)) {
4450 /* Unfortunately insert_inode_hash is not idempotent,
4451 * so as we hash inodes here rather than at creation
4452 * time, we need a lock to ensure we only try
4453 * to do it once
4454 */
4455 static DEFINE_SPINLOCK(lock);
4456 spin_lock(lock: &lock);
4457 if (inode_unhashed(inode))
4458 __insert_inode_hash(inode,
4459 hashval: inode->i_ino + inode->i_generation);
4460 spin_unlock(lock: &lock);
4461 }
4462
4463 fh[0] = inode->i_generation;
4464 fh[1] = inode->i_ino;
4465 fh[2] = ((__u64)inode->i_ino) >> 32;
4466
4467 *len = 3;
4468 return 1;
4469}
4470
4471static const struct export_operations shmem_export_ops = {
4472 .get_parent = shmem_get_parent,
4473 .encode_fh = shmem_encode_fh,
4474 .fh_to_dentry = shmem_fh_to_dentry,
4475};
4476
4477enum shmem_param {
4478 Opt_gid,
4479 Opt_huge,
4480 Opt_mode,
4481 Opt_mpol,
4482 Opt_nr_blocks,
4483 Opt_nr_inodes,
4484 Opt_size,
4485 Opt_uid,
4486 Opt_inode32,
4487 Opt_inode64,
4488 Opt_noswap,
4489 Opt_quota,
4490 Opt_usrquota,
4491 Opt_grpquota,
4492 Opt_usrquota_block_hardlimit,
4493 Opt_usrquota_inode_hardlimit,
4494 Opt_grpquota_block_hardlimit,
4495 Opt_grpquota_inode_hardlimit,
4496 Opt_casefold_version,
4497 Opt_casefold,
4498 Opt_strict_encoding,
4499};
4500
4501static const struct constant_table shmem_param_enums_huge[] = {
4502 {"never", SHMEM_HUGE_NEVER },
4503 {.name: "always", SHMEM_HUGE_ALWAYS },
4504 {.name: "within_size", SHMEM_HUGE_WITHIN_SIZE },
4505 {.name: "advise", SHMEM_HUGE_ADVISE },
4506 {}
4507};
4508
4509const struct fs_parameter_spec shmem_fs_parameters[] = {
4510 fsparam_gid ("gid", Opt_gid),
4511 fsparam_enum ("huge", Opt_huge, shmem_param_enums_huge),
4512 fsparam_u32oct("mode", Opt_mode),
4513 fsparam_string("mpol", Opt_mpol),
4514 fsparam_string("nr_blocks", Opt_nr_blocks),
4515 fsparam_string("nr_inodes", Opt_nr_inodes),
4516 fsparam_string("size", Opt_size),
4517 fsparam_uid ("uid", Opt_uid),
4518 fsparam_flag ("inode32", Opt_inode32),
4519 fsparam_flag ("inode64", Opt_inode64),
4520 fsparam_flag ("noswap", Opt_noswap),
4521#ifdef CONFIG_TMPFS_QUOTA
4522 fsparam_flag ("quota", Opt_quota),
4523 fsparam_flag ("usrquota", Opt_usrquota),
4524 fsparam_flag ("grpquota", Opt_grpquota),
4525 fsparam_string("usrquota_block_hardlimit", Opt_usrquota_block_hardlimit),
4526 fsparam_string("usrquota_inode_hardlimit", Opt_usrquota_inode_hardlimit),
4527 fsparam_string("grpquota_block_hardlimit", Opt_grpquota_block_hardlimit),
4528 fsparam_string("grpquota_inode_hardlimit", Opt_grpquota_inode_hardlimit),
4529#endif
4530 fsparam_string("casefold", Opt_casefold_version),
4531 fsparam_flag ("casefold", Opt_casefold),
4532 fsparam_flag ("strict_encoding", Opt_strict_encoding),
4533 {}
4534};
4535
4536#if IS_ENABLED(CONFIG_UNICODE)
4537static int shmem_parse_opt_casefold(struct fs_context *fc, struct fs_parameter *param,
4538 bool latest_version)
4539{
4540 struct shmem_options *ctx = fc->fs_private;
4541 int version = UTF8_LATEST;
4542 struct unicode_map *encoding;
4543 char *version_str = param->string + 5;
4544
4545 if (!latest_version) {
4546 if (strncmp(param->string, "utf8-", 5))
4547 return invalfc(fc, "Only UTF-8 encodings are supported "
4548 "in the format: utf8-<version number>");
4549
4550 version = utf8_parse_version(version_str);
4551 if (version < 0)
4552 return invalfc(fc, "Invalid UTF-8 version: %s", version_str);
4553 }
4554
4555 encoding = utf8_load(version);
4556
4557 if (IS_ERR(encoding)) {
4558 return invalfc(fc, "Failed loading UTF-8 version: utf8-%u.%u.%u\n",
4559 unicode_major(version), unicode_minor(version),
4560 unicode_rev(version));
4561 }
4562
4563 pr_info("tmpfs: Using encoding : utf8-%u.%u.%u\n",
4564 unicode_major(version), unicode_minor(version), unicode_rev(version));
4565
4566 ctx->encoding = encoding;
4567
4568 return 0;
4569}
4570#else
4571static int shmem_parse_opt_casefold(struct fs_context *fc, struct fs_parameter *param,
4572 bool latest_version)
4573{
4574 return invalfc(fc, "tmpfs: Kernel not built with CONFIG_UNICODE\n");
4575}
4576#endif
4577
4578static int shmem_parse_one(struct fs_context *fc, struct fs_parameter *param)
4579{
4580 struct shmem_options *ctx = fc->fs_private;
4581 struct fs_parse_result result;
4582 unsigned long long size;
4583 char *rest;
4584 int opt;
4585 kuid_t kuid;
4586 kgid_t kgid;
4587
4588 opt = fs_parse(fc, desc: shmem_fs_parameters, param, result: &result);
4589 if (opt < 0)
4590 return opt;
4591
4592 switch (opt) {
4593 case Opt_size:
4594 size = memparse(ptr: param->string, retptr: &rest);
4595 if (*rest == '%') {
4596 size <<= PAGE_SHIFT;
4597 size *= totalram_pages();
4598 do_div(size, 100);
4599 rest++;
4600 }
4601 if (*rest)
4602 goto bad_value;
4603 ctx->blocks = DIV_ROUND_UP(size, PAGE_SIZE);
4604 ctx->seen |= SHMEM_SEEN_BLOCKS;
4605 break;
4606 case Opt_nr_blocks:
4607 ctx->blocks = memparse(ptr: param->string, retptr: &rest);
4608 if (*rest || ctx->blocks > LONG_MAX)
4609 goto bad_value;
4610 ctx->seen |= SHMEM_SEEN_BLOCKS;
4611 break;
4612 case Opt_nr_inodes:
4613 ctx->inodes = memparse(ptr: param->string, retptr: &rest);
4614 if (*rest || ctx->inodes > ULONG_MAX / BOGO_INODE_SIZE)
4615 goto bad_value;
4616 ctx->seen |= SHMEM_SEEN_INODES;
4617 break;
4618 case Opt_mode:
4619 ctx->mode = result.uint_32 & 07777;
4620 break;
4621 case Opt_uid:
4622 kuid = result.uid;
4623
4624 /*
4625 * The requested uid must be representable in the
4626 * filesystem's idmapping.
4627 */
4628 if (!kuid_has_mapping(ns: fc->user_ns, uid: kuid))
4629 goto bad_value;
4630
4631 ctx->uid = kuid;
4632 break;
4633 case Opt_gid:
4634 kgid = result.gid;
4635
4636 /*
4637 * The requested gid must be representable in the
4638 * filesystem's idmapping.
4639 */
4640 if (!kgid_has_mapping(ns: fc->user_ns, gid: kgid))
4641 goto bad_value;
4642
4643 ctx->gid = kgid;
4644 break;
4645 case Opt_huge:
4646 ctx->huge = result.uint_32;
4647 if (ctx->huge != SHMEM_HUGE_NEVER &&
4648 !(IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE) &&
4649 has_transparent_hugepage()))
4650 goto unsupported_parameter;
4651 ctx->seen |= SHMEM_SEEN_HUGE;
4652 break;
4653 case Opt_mpol:
4654 if (IS_ENABLED(CONFIG_NUMA)) {
4655 mpol_put(pol: ctx->mpol);
4656 ctx->mpol = NULL;
4657 if (mpol_parse_str(str: param->string, mpol: &ctx->mpol))
4658 goto bad_value;
4659 break;
4660 }
4661 goto unsupported_parameter;
4662 case Opt_inode32:
4663 ctx->full_inums = false;
4664 ctx->seen |= SHMEM_SEEN_INUMS;
4665 break;
4666 case Opt_inode64:
4667 if (sizeof(ino_t) < 8) {
4668 return invalfc(fc,
4669 "Cannot use inode64 with <64bit inums in kernel\n");
4670 }
4671 ctx->full_inums = true;
4672 ctx->seen |= SHMEM_SEEN_INUMS;
4673 break;
4674 case Opt_noswap:
4675 if ((fc->user_ns != &init_user_ns) || !capable(CAP_SYS_ADMIN)) {
4676 return invalfc(fc,
4677 "Turning off swap in unprivileged tmpfs mounts unsupported");
4678 }
4679 ctx->noswap = true;
4680 ctx->seen |= SHMEM_SEEN_NOSWAP;
4681 break;
4682 case Opt_quota:
4683 if (fc->user_ns != &init_user_ns)
4684 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4685 ctx->seen |= SHMEM_SEEN_QUOTA;
4686 ctx->quota_types |= (QTYPE_MASK_USR | QTYPE_MASK_GRP);
4687 break;
4688 case Opt_usrquota:
4689 if (fc->user_ns != &init_user_ns)
4690 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4691 ctx->seen |= SHMEM_SEEN_QUOTA;
4692 ctx->quota_types |= QTYPE_MASK_USR;
4693 break;
4694 case Opt_grpquota:
4695 if (fc->user_ns != &init_user_ns)
4696 return invalfc(fc, "Quotas in unprivileged tmpfs mounts are unsupported");
4697 ctx->seen |= SHMEM_SEEN_QUOTA;
4698 ctx->quota_types |= QTYPE_MASK_GRP;
4699 break;
4700 case Opt_usrquota_block_hardlimit:
4701 size = memparse(ptr: param->string, retptr: &rest);
4702 if (*rest || !size)
4703 goto bad_value;
4704 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4705 return invalfc(fc,
4706 "User quota block hardlimit too large.");
4707 ctx->qlimits.usrquota_bhardlimit = size;
4708 break;
4709 case Opt_grpquota_block_hardlimit:
4710 size = memparse(ptr: param->string, retptr: &rest);
4711 if (*rest || !size)
4712 goto bad_value;
4713 if (size > SHMEM_QUOTA_MAX_SPC_LIMIT)
4714 return invalfc(fc,
4715 "Group quota block hardlimit too large.");
4716 ctx->qlimits.grpquota_bhardlimit = size;
4717 break;
4718 case Opt_usrquota_inode_hardlimit:
4719 size = memparse(ptr: param->string, retptr: &rest);
4720 if (*rest || !size)
4721 goto bad_value;
4722 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4723 return invalfc(fc,
4724 "User quota inode hardlimit too large.");
4725 ctx->qlimits.usrquota_ihardlimit = size;
4726 break;
4727 case Opt_grpquota_inode_hardlimit:
4728 size = memparse(ptr: param->string, retptr: &rest);
4729 if (*rest || !size)
4730 goto bad_value;
4731 if (size > SHMEM_QUOTA_MAX_INO_LIMIT)
4732 return invalfc(fc,
4733 "Group quota inode hardlimit too large.");
4734 ctx->qlimits.grpquota_ihardlimit = size;
4735 break;
4736 case Opt_casefold_version:
4737 return shmem_parse_opt_casefold(fc, param, latest_version: false);
4738 case Opt_casefold:
4739 return shmem_parse_opt_casefold(fc, param, latest_version: true);
4740 case Opt_strict_encoding:
4741#if IS_ENABLED(CONFIG_UNICODE)
4742 ctx->strict_encoding = true;
4743 break;
4744#else
4745 return invalfc(fc, "tmpfs: Kernel not built with CONFIG_UNICODE\n");
4746#endif
4747 }
4748 return 0;
4749
4750unsupported_parameter:
4751 return invalfc(fc, "Unsupported parameter '%s'", param->key);
4752bad_value:
4753 return invalfc(fc, "Bad value for '%s'", param->key);
4754}
4755
4756static char *shmem_next_opt(char **s)
4757{
4758 char *sbegin = *s;
4759 char *p;
4760
4761 if (sbegin == NULL)
4762 return NULL;
4763
4764 /*
4765 * NUL-terminate this option: unfortunately,
4766 * mount options form a comma-separated list,
4767 * but mpol's nodelist may also contain commas.
4768 */
4769 for (;;) {
4770 p = strchr(*s, ',');
4771 if (p == NULL)
4772 break;
4773 *s = p + 1;
4774 if (!isdigit(c: *(p+1))) {
4775 *p = '\0';
4776 return sbegin;
4777 }
4778 }
4779
4780 *s = NULL;
4781 return sbegin;
4782}
4783
4784static int shmem_parse_monolithic(struct fs_context *fc, void *data)
4785{
4786 return vfs_parse_monolithic_sep(fc, data, sep: shmem_next_opt);
4787}
4788
4789/*
4790 * Reconfigure a shmem filesystem.
4791 */
4792static int shmem_reconfigure(struct fs_context *fc)
4793{
4794 struct shmem_options *ctx = fc->fs_private;
4795 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: fc->root->d_sb);
4796 unsigned long used_isp;
4797 struct mempolicy *mpol = NULL;
4798 const char *err;
4799
4800 raw_spin_lock(&sbinfo->stat_lock);
4801 used_isp = sbinfo->max_inodes * BOGO_INODE_SIZE - sbinfo->free_ispace;
4802
4803 if ((ctx->seen & SHMEM_SEEN_BLOCKS) && ctx->blocks) {
4804 if (!sbinfo->max_blocks) {
4805 err = "Cannot retroactively limit size";
4806 goto out;
4807 }
4808 if (percpu_counter_compare(fbc: &sbinfo->used_blocks,
4809 rhs: ctx->blocks) > 0) {
4810 err = "Too small a size for current use";
4811 goto out;
4812 }
4813 }
4814 if ((ctx->seen & SHMEM_SEEN_INODES) && ctx->inodes) {
4815 if (!sbinfo->max_inodes) {
4816 err = "Cannot retroactively limit inodes";
4817 goto out;
4818 }
4819 if (ctx->inodes * BOGO_INODE_SIZE < used_isp) {
4820 err = "Too few inodes for current use";
4821 goto out;
4822 }
4823 }
4824
4825 if ((ctx->seen & SHMEM_SEEN_INUMS) && !ctx->full_inums &&
4826 sbinfo->next_ino > UINT_MAX) {
4827 err = "Current inum too high to switch to 32-bit inums";
4828 goto out;
4829 }
4830 if ((ctx->seen & SHMEM_SEEN_NOSWAP) && ctx->noswap && !sbinfo->noswap) {
4831 err = "Cannot disable swap on remount";
4832 goto out;
4833 }
4834 if (!(ctx->seen & SHMEM_SEEN_NOSWAP) && !ctx->noswap && sbinfo->noswap) {
4835 err = "Cannot enable swap on remount if it was disabled on first mount";
4836 goto out;
4837 }
4838
4839 if (ctx->seen & SHMEM_SEEN_QUOTA &&
4840 !sb_any_quota_loaded(sb: fc->root->d_sb)) {
4841 err = "Cannot enable quota on remount";
4842 goto out;
4843 }
4844
4845#ifdef CONFIG_TMPFS_QUOTA
4846#define CHANGED_LIMIT(name) \
4847 (ctx->qlimits.name## hardlimit && \
4848 (ctx->qlimits.name## hardlimit != sbinfo->qlimits.name## hardlimit))
4849
4850 if (CHANGED_LIMIT(usrquota_b) || CHANGED_LIMIT(usrquota_i) ||
4851 CHANGED_LIMIT(grpquota_b) || CHANGED_LIMIT(grpquota_i)) {
4852 err = "Cannot change global quota limit on remount";
4853 goto out;
4854 }
4855#endif /* CONFIG_TMPFS_QUOTA */
4856
4857 if (ctx->seen & SHMEM_SEEN_HUGE)
4858 sbinfo->huge = ctx->huge;
4859 if (ctx->seen & SHMEM_SEEN_INUMS)
4860 sbinfo->full_inums = ctx->full_inums;
4861 if (ctx->seen & SHMEM_SEEN_BLOCKS)
4862 sbinfo->max_blocks = ctx->blocks;
4863 if (ctx->seen & SHMEM_SEEN_INODES) {
4864 sbinfo->max_inodes = ctx->inodes;
4865 sbinfo->free_ispace = ctx->inodes * BOGO_INODE_SIZE - used_isp;
4866 }
4867
4868 /*
4869 * Preserve previous mempolicy unless mpol remount option was specified.
4870 */
4871 if (ctx->mpol) {
4872 mpol = sbinfo->mpol;
4873 sbinfo->mpol = ctx->mpol; /* transfers initial ref */
4874 ctx->mpol = NULL;
4875 }
4876
4877 if (ctx->noswap)
4878 sbinfo->noswap = true;
4879
4880 raw_spin_unlock(&sbinfo->stat_lock);
4881 mpol_put(pol: mpol);
4882 return 0;
4883out:
4884 raw_spin_unlock(&sbinfo->stat_lock);
4885 return invalfc(fc, "%s", err);
4886}
4887
4888static int shmem_show_options(struct seq_file *seq, struct dentry *root)
4889{
4890 struct shmem_sb_info *sbinfo = SHMEM_SB(sb: root->d_sb);
4891 struct mempolicy *mpol;
4892
4893 if (sbinfo->max_blocks != shmem_default_max_blocks())
4894 seq_printf(m: seq, fmt: ",size=%luk", K(sbinfo->max_blocks));
4895 if (sbinfo->max_inodes != shmem_default_max_inodes())
4896 seq_printf(m: seq, fmt: ",nr_inodes=%lu", sbinfo->max_inodes);
4897 if (sbinfo->mode != (0777 | S_ISVTX))
4898 seq_printf(m: seq, fmt: ",mode=%03ho", sbinfo->mode);
4899 if (!uid_eq(left: sbinfo->uid, GLOBAL_ROOT_UID))
4900 seq_printf(seq, ",uid=%u",
4901 from_kuid_munged(&init_user_ns, sbinfo->uid));
4902 if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
4903 seq_printf(seq, ",gid=%u",
4904 from_kgid_munged(&init_user_ns, sbinfo->gid));
4905
4906 /*
4907 * Showing inode{64,32} might be useful even if it's the system default,
4908 * since then people don't have to resort to checking both here and
4909 * /proc/config.gz to confirm 64-bit inums were successfully applied
4910 * (which may not even exist if IKCONFIG_PROC isn't enabled).
4911 *
4912 * We hide it when inode64 isn't the default and we are using 32-bit
4913 * inodes, since that probably just means the feature isn't even under
4914 * consideration.
4915 *
4916 * As such:
4917 *
4918 * +-----------------+-----------------+
4919 * | TMPFS_INODE64=y | TMPFS_INODE64=n |
4920 * +------------------+-----------------+-----------------+
4921 * | full_inums=true | show | show |
4922 * | full_inums=false | show | hide |
4923 * +------------------+-----------------+-----------------+
4924 *
4925 */
4926 if (IS_ENABLED(CONFIG_TMPFS_INODE64) || sbinfo->full_inums)
4927 seq_printf(seq, ",inode%d", (sbinfo->full_inums ? 64 : 32));
4928#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4929 /* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
4930 if (sbinfo->huge)
4931 seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
4932#endif
4933 mpol = shmem_get_sbmpol(sbinfo);
4934 shmem_show_mpol(seq, mpol);
4935 mpol_put(mpol);
4936 if (sbinfo->noswap)
4937 seq_printf(seq, ",noswap");
4938#ifdef CONFIG_TMPFS_QUOTA
4939 if (sb_has_quota_active(root->d_sb, USRQUOTA))
4940 seq_printf(seq, ",usrquota");
4941 if (sb_has_quota_active(root->d_sb, GRPQUOTA))
4942 seq_printf(seq, ",grpquota");
4943 if (sbinfo->qlimits.usrquota_bhardlimit)
4944 seq_printf(seq, ",usrquota_block_hardlimit=%lld",
4945 sbinfo->qlimits.usrquota_bhardlimit);
4946 if (sbinfo->qlimits.grpquota_bhardlimit)
4947 seq_printf(seq, ",grpquota_block_hardlimit=%lld",
4948 sbinfo->qlimits.grpquota_bhardlimit);
4949 if (sbinfo->qlimits.usrquota_ihardlimit)
4950 seq_printf(seq, ",usrquota_inode_hardlimit=%lld",
4951 sbinfo->qlimits.usrquota_ihardlimit);
4952 if (sbinfo->qlimits.grpquota_ihardlimit)
4953 seq_printf(seq, ",grpquota_inode_hardlimit=%lld",
4954 sbinfo->qlimits.grpquota_ihardlimit);
4955#endif
4956 return 0;
4957}
4958
4959#endif /* CONFIG_TMPFS */
4960
4961static void shmem_put_super(struct super_block *sb)
4962{
4963 struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
4964
4965#if IS_ENABLED(CONFIG_UNICODE)
4966 if (sb->s_encoding)
4967 utf8_unload(sb->s_encoding);
4968#endif
4969
4970#ifdef CONFIG_TMPFS_QUOTA
4971 shmem_disable_quotas(sb);
4972#endif
4973 free_percpu(pdata: sbinfo->ino_batch);
4974 percpu_counter_destroy(fbc: &sbinfo->used_blocks);
4975 mpol_put(pol: sbinfo->mpol);
4976 kfree(objp: sbinfo);
4977 sb->s_fs_info = NULL;
4978}
4979
4980#if IS_ENABLED(CONFIG_UNICODE) && defined(CONFIG_TMPFS)
4981static const struct dentry_operations shmem_ci_dentry_ops = {
4982 .d_hash = generic_ci_d_hash,
4983 .d_compare = generic_ci_d_compare,
4984};
4985#endif
4986
4987static int shmem_fill_super(struct super_block *sb, struct fs_context *fc)
4988{
4989 struct shmem_options *ctx = fc->fs_private;
4990 struct inode *inode;
4991 struct shmem_sb_info *sbinfo;
4992 int error = -ENOMEM;
4993
4994 /* Round up to L1_CACHE_BYTES to resist false sharing */
4995 sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
4996 L1_CACHE_BYTES), GFP_KERNEL);
4997 if (!sbinfo)
4998 return error;
4999
5000 sb->s_fs_info = sbinfo;
5001
5002#ifdef CONFIG_TMPFS
5003 /*
5004 * Per default we only allow half of the physical ram per
5005 * tmpfs instance, limiting inodes to one per page of lowmem;
5006 * but the internal instance is left unlimited.
5007 */
5008 if (!(sb->s_flags & SB_KERNMOUNT)) {
5009 if (!(ctx->seen & SHMEM_SEEN_BLOCKS))
5010 ctx->blocks = shmem_default_max_blocks();
5011 if (!(ctx->seen & SHMEM_SEEN_INODES))
5012 ctx->inodes = shmem_default_max_inodes();
5013 if (!(ctx->seen & SHMEM_SEEN_INUMS))
5014 ctx->full_inums = IS_ENABLED(CONFIG_TMPFS_INODE64);
5015 sbinfo->noswap = ctx->noswap;
5016 } else {
5017 sb->s_flags |= SB_NOUSER;
5018 }
5019 sb->s_export_op = &shmem_export_ops;
5020 sb->s_flags |= SB_NOSEC;
5021
5022#if IS_ENABLED(CONFIG_UNICODE)
5023 if (!ctx->encoding && ctx->strict_encoding) {
5024 pr_err("tmpfs: strict_encoding option without encoding is forbidden\n");
5025 error = -EINVAL;
5026 goto failed;
5027 }
5028
5029 if (ctx->encoding) {
5030 sb->s_encoding = ctx->encoding;
5031 set_default_d_op(sb, &shmem_ci_dentry_ops);
5032 if (ctx->strict_encoding)
5033 sb->s_encoding_flags = SB_ENC_STRICT_MODE_FL;
5034 }
5035#endif
5036
5037#else
5038 sb->s_flags |= SB_NOUSER;
5039#endif /* CONFIG_TMPFS */
5040 sb->s_d_flags |= DCACHE_DONTCACHE;
5041 sbinfo->max_blocks = ctx->blocks;
5042 sbinfo->max_inodes = ctx->inodes;
5043 sbinfo->free_ispace = sbinfo->max_inodes * BOGO_INODE_SIZE;
5044 if (sb->s_flags & SB_KERNMOUNT) {
5045 sbinfo->ino_batch = alloc_percpu(ino_t);
5046 if (!sbinfo->ino_batch)
5047 goto failed;
5048 }
5049 sbinfo->uid = ctx->uid;
5050 sbinfo->gid = ctx->gid;
5051 sbinfo->full_inums = ctx->full_inums;
5052 sbinfo->mode = ctx->mode;
5053#ifdef CONFIG_TRANSPARENT_HUGEPAGE
5054 if (ctx->seen & SHMEM_SEEN_HUGE)
5055 sbinfo->huge = ctx->huge;
5056 else
5057 sbinfo->huge = tmpfs_huge;
5058#endif
5059 sbinfo->mpol = ctx->mpol;
5060 ctx->mpol = NULL;
5061
5062 raw_spin_lock_init(&sbinfo->stat_lock);
5063 if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
5064 goto failed;
5065 spin_lock_init(&sbinfo->shrinklist_lock);
5066 INIT_LIST_HEAD(list: &sbinfo->shrinklist);
5067
5068 sb->s_maxbytes = MAX_LFS_FILESIZE;
5069 sb->s_blocksize = PAGE_SIZE;
5070 sb->s_blocksize_bits = PAGE_SHIFT;
5071 sb->s_magic = TMPFS_MAGIC;
5072 sb->s_op = &shmem_ops;
5073 sb->s_time_gran = 1;
5074#ifdef CONFIG_TMPFS_XATTR
5075 sb->s_xattr = shmem_xattr_handlers;
5076#endif
5077#ifdef CONFIG_TMPFS_POSIX_ACL
5078 sb->s_flags |= SB_POSIXACL;
5079#endif
5080 uuid_t uuid;
5081 uuid_gen(u: &uuid);
5082 super_set_uuid(sb, uuid: uuid.b, len: sizeof(uuid));
5083
5084#ifdef CONFIG_TMPFS_QUOTA
5085 if (ctx->seen & SHMEM_SEEN_QUOTA) {
5086 sb->dq_op = &shmem_quota_operations;
5087 sb->s_qcop = &dquot_quotactl_sysfile_ops;
5088 sb->s_quota_types = QTYPE_MASK_USR | QTYPE_MASK_GRP;
5089
5090 /* Copy the default limits from ctx into sbinfo */
5091 memcpy(&sbinfo->qlimits, &ctx->qlimits,
5092 sizeof(struct shmem_quota_limits));
5093
5094 if (shmem_enable_quotas(sb, ctx->quota_types))
5095 goto failed;
5096 }
5097#endif /* CONFIG_TMPFS_QUOTA */
5098
5099 inode = shmem_get_inode(idmap: &nop_mnt_idmap, sb, NULL,
5100 S_IFDIR | sbinfo->mode, dev: 0, VM_NORESERVE);
5101 if (IS_ERR(ptr: inode)) {
5102 error = PTR_ERR(ptr: inode);
5103 goto failed;
5104 }
5105 inode->i_uid = sbinfo->uid;
5106 inode->i_gid = sbinfo->gid;
5107 sb->s_root = d_make_root(inode);
5108 if (!sb->s_root)
5109 goto failed;
5110 return 0;
5111
5112failed:
5113 shmem_put_super(sb);
5114 return error;
5115}
5116
5117static int shmem_get_tree(struct fs_context *fc)
5118{
5119 return get_tree_nodev(fc, fill_super: shmem_fill_super);
5120}
5121
5122static void shmem_free_fc(struct fs_context *fc)
5123{
5124 struct shmem_options *ctx = fc->fs_private;
5125
5126 if (ctx) {
5127 mpol_put(pol: ctx->mpol);
5128 kfree(objp: ctx);
5129 }
5130}
5131
5132static const struct fs_context_operations shmem_fs_context_ops = {
5133 .free = shmem_free_fc,
5134 .get_tree = shmem_get_tree,
5135#ifdef CONFIG_TMPFS
5136 .parse_monolithic = shmem_parse_monolithic,
5137 .parse_param = shmem_parse_one,
5138 .reconfigure = shmem_reconfigure,
5139#endif
5140};
5141
5142static struct kmem_cache *shmem_inode_cachep __ro_after_init;
5143
5144static struct inode *shmem_alloc_inode(struct super_block *sb)
5145{
5146 struct shmem_inode_info *info;
5147 info = alloc_inode_sb(sb, shmem_inode_cachep, GFP_KERNEL);
5148 if (!info)
5149 return NULL;
5150 return &info->vfs_inode;
5151}
5152
5153static void shmem_free_in_core_inode(struct inode *inode)
5154{
5155 if (S_ISLNK(inode->i_mode))
5156 kfree(objp: inode->i_link);
5157 kmem_cache_free(s: shmem_inode_cachep, objp: SHMEM_I(inode));
5158}
5159
5160static void shmem_destroy_inode(struct inode *inode)
5161{
5162 if (S_ISREG(inode->i_mode))
5163 mpol_free_shared_policy(sp: &SHMEM_I(inode)->policy);
5164 if (S_ISDIR(inode->i_mode))
5165 simple_offset_destroy(octx: shmem_get_offset_ctx(inode));
5166}
5167
5168static void shmem_init_inode(void *foo)
5169{
5170 struct shmem_inode_info *info = foo;
5171 inode_init_once(&info->vfs_inode);
5172}
5173
5174static void __init shmem_init_inodecache(void)
5175{
5176 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
5177 sizeof(struct shmem_inode_info),
5178 0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
5179}
5180
5181static void __init shmem_destroy_inodecache(void)
5182{
5183 kmem_cache_destroy(s: shmem_inode_cachep);
5184}
5185
5186/* Keep the page in page cache instead of truncating it */
5187static int shmem_error_remove_folio(struct address_space *mapping,
5188 struct folio *folio)
5189{
5190 return 0;
5191}
5192
5193static const struct address_space_operations shmem_aops = {
5194 .dirty_folio = noop_dirty_folio,
5195#ifdef CONFIG_TMPFS
5196 .write_begin = shmem_write_begin,
5197 .write_end = shmem_write_end,
5198#endif
5199#ifdef CONFIG_MIGRATION
5200 .migrate_folio = migrate_folio,
5201#endif
5202 .error_remove_folio = shmem_error_remove_folio,
5203};
5204
5205static const struct file_operations shmem_file_operations = {
5206 .mmap = shmem_mmap,
5207 .open = shmem_file_open,
5208 .get_unmapped_area = shmem_get_unmapped_area,
5209#ifdef CONFIG_TMPFS
5210 .llseek = shmem_file_llseek,
5211 .read_iter = shmem_file_read_iter,
5212 .write_iter = shmem_file_write_iter,
5213 .fsync = noop_fsync,
5214 .splice_read = shmem_file_splice_read,
5215 .splice_write = iter_file_splice_write,
5216 .fallocate = shmem_fallocate,
5217#endif
5218};
5219
5220static const struct inode_operations shmem_inode_operations = {
5221 .getattr = shmem_getattr,
5222 .setattr = shmem_setattr,
5223#ifdef CONFIG_TMPFS_XATTR
5224 .listxattr = shmem_listxattr,
5225 .set_acl = simple_set_acl,
5226 .fileattr_get = shmem_fileattr_get,
5227 .fileattr_set = shmem_fileattr_set,
5228#endif
5229};
5230
5231static const struct inode_operations shmem_dir_inode_operations = {
5232#ifdef CONFIG_TMPFS
5233 .getattr = shmem_getattr,
5234 .create = shmem_create,
5235 .lookup = simple_lookup,
5236 .link = shmem_link,
5237 .unlink = shmem_unlink,
5238 .symlink = shmem_symlink,
5239 .mkdir = shmem_mkdir,
5240 .rmdir = shmem_rmdir,
5241 .mknod = shmem_mknod,
5242 .rename = shmem_rename2,
5243 .tmpfile = shmem_tmpfile,
5244 .get_offset_ctx = shmem_get_offset_ctx,
5245#endif
5246#ifdef CONFIG_TMPFS_XATTR
5247 .listxattr = shmem_listxattr,
5248 .fileattr_get = shmem_fileattr_get,
5249 .fileattr_set = shmem_fileattr_set,
5250#endif
5251#ifdef CONFIG_TMPFS_POSIX_ACL
5252 .setattr = shmem_setattr,
5253 .set_acl = simple_set_acl,
5254#endif
5255};
5256
5257static const struct inode_operations shmem_special_inode_operations = {
5258 .getattr = shmem_getattr,
5259#ifdef CONFIG_TMPFS_XATTR
5260 .listxattr = shmem_listxattr,
5261#endif
5262#ifdef CONFIG_TMPFS_POSIX_ACL
5263 .setattr = shmem_setattr,
5264 .set_acl = simple_set_acl,
5265#endif
5266};
5267
5268static const struct super_operations shmem_ops = {
5269 .alloc_inode = shmem_alloc_inode,
5270 .free_inode = shmem_free_in_core_inode,
5271 .destroy_inode = shmem_destroy_inode,
5272#ifdef CONFIG_TMPFS
5273 .statfs = shmem_statfs,
5274 .show_options = shmem_show_options,
5275#endif
5276#ifdef CONFIG_TMPFS_QUOTA
5277 .get_dquots = shmem_get_dquots,
5278#endif
5279 .evict_inode = shmem_evict_inode,
5280 .drop_inode = inode_just_drop,
5281 .put_super = shmem_put_super,
5282#ifdef CONFIG_TRANSPARENT_HUGEPAGE
5283 .nr_cached_objects = shmem_unused_huge_count,
5284 .free_cached_objects = shmem_unused_huge_scan,
5285#endif
5286};
5287
5288static const struct vm_operations_struct shmem_vm_ops = {
5289 .fault = shmem_fault,
5290 .map_pages = filemap_map_pages,
5291#ifdef CONFIG_NUMA
5292 .set_policy = shmem_set_policy,
5293 .get_policy = shmem_get_policy,
5294#endif
5295};
5296
5297static const struct vm_operations_struct shmem_anon_vm_ops = {
5298 .fault = shmem_fault,
5299 .map_pages = filemap_map_pages,
5300#ifdef CONFIG_NUMA
5301 .set_policy = shmem_set_policy,
5302 .get_policy = shmem_get_policy,
5303#endif
5304};
5305
5306int shmem_init_fs_context(struct fs_context *fc)
5307{
5308 struct shmem_options *ctx;
5309
5310 ctx = kzalloc(sizeof(struct shmem_options), GFP_KERNEL);
5311 if (!ctx)
5312 return -ENOMEM;
5313
5314 ctx->mode = 0777 | S_ISVTX;
5315 ctx->uid = current_fsuid();
5316 ctx->gid = current_fsgid();
5317
5318#if IS_ENABLED(CONFIG_UNICODE)
5319 ctx->encoding = NULL;
5320#endif
5321
5322 fc->fs_private = ctx;
5323 fc->ops = &shmem_fs_context_ops;
5324#ifdef CONFIG_TMPFS
5325 fc->sb_flags |= SB_I_VERSION;
5326#endif
5327 return 0;
5328}
5329
5330static struct file_system_type shmem_fs_type = {
5331 .owner = THIS_MODULE,
5332 .name = "tmpfs",
5333 .init_fs_context = shmem_init_fs_context,
5334#ifdef CONFIG_TMPFS
5335 .parameters = shmem_fs_parameters,
5336#endif
5337 .kill_sb = kill_litter_super,
5338 .fs_flags = FS_USERNS_MOUNT | FS_ALLOW_IDMAP | FS_MGTIME,
5339};
5340
5341#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
5342
5343#define __INIT_KOBJ_ATTR(_name, _mode, _show, _store) \
5344{ \
5345 .attr = { .name = __stringify(_name), .mode = _mode }, \
5346 .show = _show, \
5347 .store = _store, \
5348}
5349
5350#define TMPFS_ATTR_W(_name, _store) \
5351 static struct kobj_attribute tmpfs_attr_##_name = \
5352 __INIT_KOBJ_ATTR(_name, 0200, NULL, _store)
5353
5354#define TMPFS_ATTR_RW(_name, _show, _store) \
5355 static struct kobj_attribute tmpfs_attr_##_name = \
5356 __INIT_KOBJ_ATTR(_name, 0644, _show, _store)
5357
5358#define TMPFS_ATTR_RO(_name, _show) \
5359 static struct kobj_attribute tmpfs_attr_##_name = \
5360 __INIT_KOBJ_ATTR(_name, 0444, _show, NULL)
5361
5362#if IS_ENABLED(CONFIG_UNICODE)
5363static ssize_t casefold_show(struct kobject *kobj, struct kobj_attribute *a,
5364 char *buf)
5365{
5366 return sysfs_emit(buf, "supported\n");
5367}
5368TMPFS_ATTR_RO(casefold, casefold_show);
5369#endif
5370
5371static struct attribute *tmpfs_attributes[] = {
5372#if IS_ENABLED(CONFIG_UNICODE)
5373 &tmpfs_attr_casefold.attr,
5374#endif
5375 NULL
5376};
5377
5378static const struct attribute_group tmpfs_attribute_group = {
5379 .attrs = tmpfs_attributes,
5380 .name = "features"
5381};
5382
5383static struct kobject *tmpfs_kobj;
5384
5385static int __init tmpfs_sysfs_init(void)
5386{
5387 int ret;
5388
5389 tmpfs_kobj = kobject_create_and_add(name: "tmpfs", parent: fs_kobj);
5390 if (!tmpfs_kobj)
5391 return -ENOMEM;
5392
5393 ret = sysfs_create_group(kobj: tmpfs_kobj, grp: &tmpfs_attribute_group);
5394 if (ret)
5395 kobject_put(kobj: tmpfs_kobj);
5396
5397 return ret;
5398}
5399#endif /* CONFIG_SYSFS && CONFIG_TMPFS */
5400
5401void __init shmem_init(void)
5402{
5403 int error;
5404
5405 shmem_init_inodecache();
5406
5407#ifdef CONFIG_TMPFS_QUOTA
5408 register_quota_format(&shmem_quota_format);
5409#endif
5410
5411 error = register_filesystem(&shmem_fs_type);
5412 if (error) {
5413 pr_err("Could not register tmpfs\n");
5414 goto out2;
5415 }
5416
5417 shm_mnt = kern_mount(&shmem_fs_type);
5418 if (IS_ERR(ptr: shm_mnt)) {
5419 error = PTR_ERR(ptr: shm_mnt);
5420 pr_err("Could not kern_mount tmpfs\n");
5421 goto out1;
5422 }
5423
5424#if defined(CONFIG_SYSFS) && defined(CONFIG_TMPFS)
5425 error = tmpfs_sysfs_init();
5426 if (error) {
5427 pr_err("Could not init tmpfs sysfs\n");
5428 goto out1;
5429 }
5430#endif
5431
5432#ifdef CONFIG_TRANSPARENT_HUGEPAGE
5433 if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
5434 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
5435 else
5436 shmem_huge = SHMEM_HUGE_NEVER; /* just in case it was patched */
5437
5438 /*
5439 * Default to setting PMD-sized THP to inherit the global setting and
5440 * disable all other multi-size THPs.
5441 */
5442 if (!shmem_orders_configured)
5443 huge_shmem_orders_inherit = BIT(HPAGE_PMD_ORDER);
5444#endif
5445 return;
5446
5447out1:
5448 unregister_filesystem(&shmem_fs_type);
5449out2:
5450#ifdef CONFIG_TMPFS_QUOTA
5451 unregister_quota_format(&shmem_quota_format);
5452#endif
5453 shmem_destroy_inodecache();
5454 shm_mnt = ERR_PTR(error);
5455}
5456
5457#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS)
5458static ssize_t shmem_enabled_show(struct kobject *kobj,
5459 struct kobj_attribute *attr, char *buf)
5460{
5461 static const int values[] = {
5462 SHMEM_HUGE_ALWAYS,
5463 SHMEM_HUGE_WITHIN_SIZE,
5464 SHMEM_HUGE_ADVISE,
5465 SHMEM_HUGE_NEVER,
5466 SHMEM_HUGE_DENY,
5467 SHMEM_HUGE_FORCE,
5468 };
5469 int len = 0;
5470 int i;
5471
5472 for (i = 0; i < ARRAY_SIZE(values); i++) {
5473 len += sysfs_emit_at(buf, len,
5474 shmem_huge == values[i] ? "%s[%s]" : "%s%s",
5475 i ? " " : "", shmem_format_huge(values[i]));
5476 }
5477 len += sysfs_emit_at(buf, len, "\n");
5478
5479 return len;
5480}
5481
5482static ssize_t shmem_enabled_store(struct kobject *kobj,
5483 struct kobj_attribute *attr, const char *buf, size_t count)
5484{
5485 char tmp[16];
5486 int huge, err;
5487
5488 if (count + 1 > sizeof(tmp))
5489 return -EINVAL;
5490 memcpy(tmp, buf, count);
5491 tmp[count] = '\0';
5492 if (count && tmp[count - 1] == '\n')
5493 tmp[count - 1] = '\0';
5494
5495 huge = shmem_parse_huge(tmp);
5496 if (huge == -EINVAL)
5497 return huge;
5498
5499 shmem_huge = huge;
5500 if (shmem_huge > SHMEM_HUGE_DENY)
5501 SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
5502
5503 err = start_stop_khugepaged();
5504 return err ? err : count;
5505}
5506
5507struct kobj_attribute shmem_enabled_attr = __ATTR_RW(shmem_enabled);
5508static DEFINE_SPINLOCK(huge_shmem_orders_lock);
5509
5510static ssize_t thpsize_shmem_enabled_show(struct kobject *kobj,
5511 struct kobj_attribute *attr, char *buf)
5512{
5513 int order = to_thpsize(kobj)->order;
5514 const char *output;
5515
5516 if (test_bit(order, &huge_shmem_orders_always))
5517 output = "[always] inherit within_size advise never";
5518 else if (test_bit(order, &huge_shmem_orders_inherit))
5519 output = "always [inherit] within_size advise never";
5520 else if (test_bit(order, &huge_shmem_orders_within_size))
5521 output = "always inherit [within_size] advise never";
5522 else if (test_bit(order, &huge_shmem_orders_madvise))
5523 output = "always inherit within_size [advise] never";
5524 else
5525 output = "always inherit within_size advise [never]";
5526
5527 return sysfs_emit(buf, "%s\n", output);
5528}
5529
5530static ssize_t thpsize_shmem_enabled_store(struct kobject *kobj,
5531 struct kobj_attribute *attr,
5532 const char *buf, size_t count)
5533{
5534 int order = to_thpsize(kobj)->order;
5535 ssize_t ret = count;
5536
5537 if (sysfs_streq(buf, "always")) {
5538 spin_lock(&huge_shmem_orders_lock);
5539 clear_bit(order, &huge_shmem_orders_inherit);
5540 clear_bit(order, &huge_shmem_orders_madvise);
5541 clear_bit(order, &huge_shmem_orders_within_size);
5542 set_bit(order, &huge_shmem_orders_always);
5543 spin_unlock(&huge_shmem_orders_lock);
5544 } else if (sysfs_streq(buf, "inherit")) {
5545 /* Do not override huge allocation policy with non-PMD sized mTHP */
5546 if (shmem_huge == SHMEM_HUGE_FORCE &&
5547 order != HPAGE_PMD_ORDER)
5548 return -EINVAL;
5549
5550 spin_lock(&huge_shmem_orders_lock);
5551 clear_bit(order, &huge_shmem_orders_always);
5552 clear_bit(order, &huge_shmem_orders_madvise);
5553 clear_bit(order, &huge_shmem_orders_within_size);
5554 set_bit(order, &huge_shmem_orders_inherit);
5555 spin_unlock(&huge_shmem_orders_lock);
5556 } else if (sysfs_streq(buf, "within_size")) {
5557 spin_lock(&huge_shmem_orders_lock);
5558 clear_bit(order, &huge_shmem_orders_always);
5559 clear_bit(order, &huge_shmem_orders_inherit);
5560 clear_bit(order, &huge_shmem_orders_madvise);
5561 set_bit(order, &huge_shmem_orders_within_size);
5562 spin_unlock(&huge_shmem_orders_lock);
5563 } else if (sysfs_streq(buf, "advise")) {
5564 spin_lock(&huge_shmem_orders_lock);
5565 clear_bit(order, &huge_shmem_orders_always);
5566 clear_bit(order, &huge_shmem_orders_inherit);
5567 clear_bit(order, &huge_shmem_orders_within_size);
5568 set_bit(order, &huge_shmem_orders_madvise);
5569 spin_unlock(&huge_shmem_orders_lock);
5570 } else if (sysfs_streq(buf, "never")) {
5571 spin_lock(&huge_shmem_orders_lock);
5572 clear_bit(order, &huge_shmem_orders_always);
5573 clear_bit(order, &huge_shmem_orders_inherit);
5574 clear_bit(order, &huge_shmem_orders_within_size);
5575 clear_bit(order, &huge_shmem_orders_madvise);
5576 spin_unlock(&huge_shmem_orders_lock);
5577 } else {
5578 ret = -EINVAL;
5579 }
5580
5581 if (ret > 0) {
5582 int err = start_stop_khugepaged();
5583
5584 if (err)
5585 ret = err;
5586 }
5587 return ret;
5588}
5589
5590struct kobj_attribute thpsize_shmem_enabled_attr =
5591 __ATTR(shmem_enabled, 0644, thpsize_shmem_enabled_show, thpsize_shmem_enabled_store);
5592#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_SYSFS */
5593
5594#if defined(CONFIG_TRANSPARENT_HUGEPAGE)
5595
5596static int __init setup_transparent_hugepage_shmem(char *str)
5597{
5598 int huge;
5599
5600 huge = shmem_parse_huge(str);
5601 if (huge == -EINVAL) {
5602 pr_warn("transparent_hugepage_shmem= cannot parse, ignored\n");
5603 return huge;
5604 }
5605
5606 shmem_huge = huge;
5607 return 1;
5608}
5609__setup("transparent_hugepage_shmem=", setup_transparent_hugepage_shmem);
5610
5611static int __init setup_transparent_hugepage_tmpfs(char *str)
5612{
5613 int huge;
5614
5615 huge = shmem_parse_huge(str);
5616 if (huge < 0) {
5617 pr_warn("transparent_hugepage_tmpfs= cannot parse, ignored\n");
5618 return huge;
5619 }
5620
5621 tmpfs_huge = huge;
5622 return 1;
5623}
5624__setup("transparent_hugepage_tmpfs=", setup_transparent_hugepage_tmpfs);
5625
5626static char str_dup[PAGE_SIZE] __initdata;
5627static int __init setup_thp_shmem(char *str)
5628{
5629 char *token, *range, *policy, *subtoken;
5630 unsigned long always, inherit, madvise, within_size;
5631 char *start_size, *end_size;
5632 int start, end, nr;
5633 char *p;
5634
5635 if (!str || strlen(str) + 1 > PAGE_SIZE)
5636 goto err;
5637 strscpy(str_dup, str);
5638
5639 always = huge_shmem_orders_always;
5640 inherit = huge_shmem_orders_inherit;
5641 madvise = huge_shmem_orders_madvise;
5642 within_size = huge_shmem_orders_within_size;
5643 p = str_dup;
5644 while ((token = strsep(&p, ";")) != NULL) {
5645 range = strsep(&token, ":");
5646 policy = token;
5647
5648 if (!policy)
5649 goto err;
5650
5651 while ((subtoken = strsep(&range, ",")) != NULL) {
5652 if (strchr(subtoken, '-')) {
5653 start_size = strsep(&subtoken, "-");
5654 end_size = subtoken;
5655
5656 start = get_order_from_str(start_size,
5657 THP_ORDERS_ALL_FILE_DEFAULT);
5658 end = get_order_from_str(end_size,
5659 THP_ORDERS_ALL_FILE_DEFAULT);
5660 } else {
5661 start_size = end_size = subtoken;
5662 start = end = get_order_from_str(subtoken,
5663 THP_ORDERS_ALL_FILE_DEFAULT);
5664 }
5665
5666 if (start < 0) {
5667 pr_err("invalid size %s in thp_shmem boot parameter\n",
5668 start_size);
5669 goto err;
5670 }
5671
5672 if (end < 0) {
5673 pr_err("invalid size %s in thp_shmem boot parameter\n",
5674 end_size);
5675 goto err;
5676 }
5677
5678 if (start > end)
5679 goto err;
5680
5681 nr = end - start + 1;
5682 if (!strcmp(policy, "always")) {
5683 bitmap_set(&always, start, nr);
5684 bitmap_clear(&inherit, start, nr);
5685 bitmap_clear(&madvise, start, nr);
5686 bitmap_clear(&within_size, start, nr);
5687 } else if (!strcmp(policy, "advise")) {
5688 bitmap_set(&madvise, start, nr);
5689 bitmap_clear(&inherit, start, nr);
5690 bitmap_clear(&always, start, nr);
5691 bitmap_clear(&within_size, start, nr);
5692 } else if (!strcmp(policy, "inherit")) {
5693 bitmap_set(&inherit, start, nr);
5694 bitmap_clear(&madvise, start, nr);
5695 bitmap_clear(&always, start, nr);
5696 bitmap_clear(&within_size, start, nr);
5697 } else if (!strcmp(policy, "within_size")) {
5698 bitmap_set(&within_size, start, nr);
5699 bitmap_clear(&inherit, start, nr);
5700 bitmap_clear(&madvise, start, nr);
5701 bitmap_clear(&always, start, nr);
5702 } else if (!strcmp(policy, "never")) {
5703 bitmap_clear(&inherit, start, nr);
5704 bitmap_clear(&madvise, start, nr);
5705 bitmap_clear(&always, start, nr);
5706 bitmap_clear(&within_size, start, nr);
5707 } else {
5708 pr_err("invalid policy %s in thp_shmem boot parameter\n", policy);
5709 goto err;
5710 }
5711 }
5712 }
5713
5714 huge_shmem_orders_always = always;
5715 huge_shmem_orders_madvise = madvise;
5716 huge_shmem_orders_inherit = inherit;
5717 huge_shmem_orders_within_size = within_size;
5718 shmem_orders_configured = true;
5719 return 1;
5720
5721err:
5722 pr_warn("thp_shmem=%s: error parsing string, ignoring setting\n", str);
5723 return 0;
5724}
5725__setup("thp_shmem=", setup_thp_shmem);
5726
5727#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
5728
5729#else /* !CONFIG_SHMEM */
5730
5731/*
5732 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
5733 *
5734 * This is intended for small system where the benefits of the full
5735 * shmem code (swap-backed and resource-limited) are outweighed by
5736 * their complexity. On systems without swap this code should be
5737 * effectively equivalent, but much lighter weight.
5738 */
5739
5740static struct file_system_type shmem_fs_type = {
5741 .name = "tmpfs",
5742 .init_fs_context = ramfs_init_fs_context,
5743 .parameters = ramfs_fs_parameters,
5744 .kill_sb = ramfs_kill_sb,
5745 .fs_flags = FS_USERNS_MOUNT,
5746};
5747
5748void __init shmem_init(void)
5749{
5750 BUG_ON(register_filesystem(&shmem_fs_type) != 0);
5751
5752 shm_mnt = kern_mount(&shmem_fs_type);
5753 BUG_ON(IS_ERR(shm_mnt));
5754}
5755
5756int shmem_unuse(unsigned int type)
5757{
5758 return 0;
5759}
5760
5761int shmem_lock(struct file *file, int lock, struct ucounts *ucounts)
5762{
5763 return 0;
5764}
5765
5766void shmem_unlock_mapping(struct address_space *mapping)
5767{
5768}
5769
5770#ifdef CONFIG_MMU
5771unsigned long shmem_get_unmapped_area(struct file *file,
5772 unsigned long addr, unsigned long len,
5773 unsigned long pgoff, unsigned long flags)
5774{
5775 return mm_get_unmapped_area(current->mm, file, addr, len, pgoff, flags);
5776}
5777#endif
5778
5779void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
5780{
5781 truncate_inode_pages_range(inode->i_mapping, lstart, lend);
5782}
5783EXPORT_SYMBOL_GPL(shmem_truncate_range);
5784
5785#define shmem_vm_ops generic_file_vm_ops
5786#define shmem_anon_vm_ops generic_file_vm_ops
5787#define shmem_file_operations ramfs_file_operations
5788#define shmem_acct_size(flags, size) 0
5789#define shmem_unacct_size(flags, size) do {} while (0)
5790
5791static inline struct inode *shmem_get_inode(struct mnt_idmap *idmap,
5792 struct super_block *sb, struct inode *dir,
5793 umode_t mode, dev_t dev, unsigned long flags)
5794{
5795 struct inode *inode = ramfs_get_inode(sb, dir, mode, dev);
5796 return inode ? inode : ERR_PTR(-ENOSPC);
5797}
5798
5799#endif /* CONFIG_SHMEM */
5800
5801/* common code */
5802
5803static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name,
5804 loff_t size, unsigned long flags, unsigned int i_flags)
5805{
5806 struct inode *inode;
5807 struct file *res;
5808
5809 if (IS_ERR(ptr: mnt))
5810 return ERR_CAST(ptr: mnt);
5811
5812 if (size < 0 || size > MAX_LFS_FILESIZE)
5813 return ERR_PTR(error: -EINVAL);
5814
5815 if (is_idmapped_mnt(mnt))
5816 return ERR_PTR(error: -EINVAL);
5817
5818 if (shmem_acct_size(flags, size))
5819 return ERR_PTR(error: -ENOMEM);
5820
5821 inode = shmem_get_inode(idmap: &nop_mnt_idmap, sb: mnt->mnt_sb, NULL,
5822 S_IFREG | S_IRWXUGO, dev: 0, flags);
5823 if (IS_ERR(ptr: inode)) {
5824 shmem_unacct_size(flags, size);
5825 return ERR_CAST(ptr: inode);
5826 }
5827 inode->i_flags |= i_flags;
5828 inode->i_size = size;
5829 clear_nlink(inode); /* It is unlinked */
5830 res = ERR_PTR(error: ramfs_nommu_expand_for_mapping(inode, newsize: size));
5831 if (!IS_ERR(ptr: res))
5832 res = alloc_file_pseudo(inode, mnt, name, O_RDWR,
5833 &shmem_file_operations);
5834 if (IS_ERR(ptr: res))
5835 iput(inode);
5836 return res;
5837}
5838
5839/**
5840 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
5841 * kernel internal. There will be NO LSM permission checks against the
5842 * underlying inode. So users of this interface must do LSM checks at a
5843 * higher layer. The users are the big_key and shm implementations. LSM
5844 * checks are provided at the key or shm level rather than the inode.
5845 * @name: name for dentry (to be seen in /proc/<pid>/maps)
5846 * @size: size to be set for the file
5847 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
5848 */
5849struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
5850{
5851 return __shmem_file_setup(mnt: shm_mnt, name, size, flags, S_PRIVATE);
5852}
5853EXPORT_SYMBOL_GPL(shmem_kernel_file_setup);
5854
5855/**
5856 * shmem_file_setup - get an unlinked file living in tmpfs
5857 * @name: name for dentry (to be seen in /proc/<pid>/maps)
5858 * @size: size to be set for the file
5859 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
5860 */
5861struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
5862{
5863 return __shmem_file_setup(mnt: shm_mnt, name, size, flags, i_flags: 0);
5864}
5865EXPORT_SYMBOL_GPL(shmem_file_setup);
5866
5867/**
5868 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
5869 * @mnt: the tmpfs mount where the file will be created
5870 * @name: name for dentry (to be seen in /proc/<pid>/maps)
5871 * @size: size to be set for the file
5872 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
5873 */
5874struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
5875 loff_t size, unsigned long flags)
5876{
5877 return __shmem_file_setup(mnt, name, size, flags, i_flags: 0);
5878}
5879EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
5880
5881/**
5882 * shmem_zero_setup - setup a shared anonymous mapping
5883 * @vma: the vma to be mmapped is prepared by do_mmap
5884 */
5885int shmem_zero_setup(struct vm_area_struct *vma)
5886{
5887 struct file *file;
5888 loff_t size = vma->vm_end - vma->vm_start;
5889
5890 /*
5891 * Cloning a new file under mmap_lock leads to a lock ordering conflict
5892 * between XFS directory reading and selinux: since this file is only
5893 * accessible to the user through its mapping, use S_PRIVATE flag to
5894 * bypass file security, in the same way as shmem_kernel_file_setup().
5895 */
5896 file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
5897 if (IS_ERR(ptr: file))
5898 return PTR_ERR(ptr: file);
5899
5900 if (vma->vm_file)
5901 fput(vma->vm_file);
5902 vma->vm_file = file;
5903 vma->vm_ops = &shmem_anon_vm_ops;
5904
5905 return 0;
5906}
5907
5908/**
5909 * shmem_read_folio_gfp - read into page cache, using specified page allocation flags.
5910 * @mapping: the folio's address_space
5911 * @index: the folio index
5912 * @gfp: the page allocator flags to use if allocating
5913 *
5914 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
5915 * with any new page allocations done using the specified allocation flags.
5916 * But read_cache_page_gfp() uses the ->read_folio() method: which does not
5917 * suit tmpfs, since it may have pages in swapcache, and needs to find those
5918 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
5919 *
5920 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
5921 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
5922 */
5923struct folio *shmem_read_folio_gfp(struct address_space *mapping,
5924 pgoff_t index, gfp_t gfp)
5925{
5926#ifdef CONFIG_SHMEM
5927 struct inode *inode = mapping->host;
5928 struct folio *folio;
5929 int error;
5930
5931 error = shmem_get_folio_gfp(inode, index, write_end: i_size_read(inode),
5932 foliop: &folio, sgp: SGP_CACHE, gfp, NULL, NULL);
5933 if (error)
5934 return ERR_PTR(error);
5935
5936 folio_unlock(folio);
5937 return folio;
5938#else
5939 /*
5940 * The tiny !SHMEM case uses ramfs without swap
5941 */
5942 return mapping_read_folio_gfp(mapping, index, gfp);
5943#endif
5944}
5945EXPORT_SYMBOL_GPL(shmem_read_folio_gfp);
5946
5947struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
5948 pgoff_t index, gfp_t gfp)
5949{
5950 struct folio *folio = shmem_read_folio_gfp(mapping, index, gfp);
5951 struct page *page;
5952
5953 if (IS_ERR(ptr: folio))
5954 return &folio->page;
5955
5956 page = folio_file_page(folio, index);
5957 if (PageHWPoison(page)) {
5958 folio_put(folio);
5959 return ERR_PTR(error: -EIO);
5960 }
5961
5962 return page;
5963}
5964EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
5965