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