1/*
   2 * Resizable virtual memory filesystem for Linux.
   3 *
   4 * Copyright (C) 2000 Linus Torvalds.
   5 *		 2000 Transmeta Corp.
   6 *		 2000-2001 Christoph Rohland
   7 *		 2000-2001 SAP AG
   8 *		 2002 Red Hat Inc.
   9 * Copyright (C) 2002-2011 Hugh Dickins.
  10 * Copyright (C) 2011 Google Inc.
  11 * Copyright (C) 2002-2005 VERITAS Software Corporation.
  12 * Copyright (C) 2004 Andi Kleen, SuSE Labs
  13 *
  14 * Extended attribute support for tmpfs:
  15 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
  16 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
  17 *
  18 * tiny-shmem:
  19 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
  20 *
  21 * This file is released under the GPL.
  22 */
  23
  24#include <linux/fs.h>
  25#include <linux/init.h>
  26#include <linux/vfs.h>
  27#include <linux/mount.h>
  28#include <linux/ramfs.h>
  29#include <linux/pagemap.h>
  30#include <linux/file.h>
 
  31#include <linux/mm.h>
 
  32#include <linux/sched/signal.h>
  33#include <linux/export.h>
 
  34#include <linux/swap.h>
  35#include <linux/uio.h>
  36#include <linux/khugepaged.h>
  37#include <linux/hugetlb.h>
 
 
 
 
 
  38
  39#include <asm/tlbflush.h> /* for arch/microblaze update_mmu_cache() */
  40
  41static struct vfsmount *shm_mnt;
  42
  43#ifdef CONFIG_SHMEM
  44/*
  45 * This virtual memory filesystem is heavily based on the ramfs. It
  46 * extends ramfs by the ability to use swap and honor resource limits
  47 * which makes it a completely usable filesystem.
  48 */
  49
  50#include <linux/xattr.h>
  51#include <linux/exportfs.h>
  52#include <linux/posix_acl.h>
  53#include <linux/posix_acl_xattr.h>
  54#include <linux/mman.h>
  55#include <linux/string.h>
  56#include <linux/slab.h>
  57#include <linux/backing-dev.h>
  58#include <linux/shmem_fs.h>
  59#include <linux/writeback.h>
  60#include <linux/blkdev.h>
  61#include <linux/pagevec.h>
  62#include <linux/percpu_counter.h>
  63#include <linux/falloc.h>
  64#include <linux/splice.h>
  65#include <linux/security.h>
  66#include <linux/swapops.h>
  67#include <linux/mempolicy.h>
  68#include <linux/namei.h>
  69#include <linux/ctype.h>
  70#include <linux/migrate.h>
  71#include <linux/highmem.h>
  72#include <linux/seq_file.h>
  73#include <linux/magic.h>
  74#include <linux/syscalls.h>
  75#include <linux/fcntl.h>
  76#include <uapi/linux/memfd.h>
  77#include <linux/userfaultfd_k.h>
  78#include <linux/rmap.h>
  79#include <linux/uuid.h>
 
 
  80
  81#include <linux/uaccess.h>
  82#include <asm/pgtable.h>
  83
  84#include "internal.h"
  85
  86#define BLOCKS_PER_PAGE  (PAGE_SIZE/512)
  87#define VM_ACCT(size)    (PAGE_ALIGN(size) >> PAGE_SHIFT)
  88
  89/* Pretend that each entry is of this size in directory's i_size */
  90#define BOGO_DIRENT_SIZE 20
  91
 
 
 
  92/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
  93#define SHORT_SYMLINK_LEN 128
  94
  95/*
  96 * shmem_fallocate communicates with shmem_fault or shmem_writepage via
  97 * inode->i_private (with i_mutex making sure that it has only one user at
  98 * a time): we would prefer not to enlarge the shmem inode just for that.
  99 */
 100struct shmem_falloc {
 101	wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
 102	pgoff_t start;		/* start of range currently being fallocated */
 103	pgoff_t next;		/* the next page offset to be fallocated */
 104	pgoff_t nr_falloced;	/* how many new pages have been fallocated */
 105	pgoff_t nr_unswapped;	/* how often writepage refused to swap out */
 106};
 107
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 108#ifdef CONFIG_TMPFS
 109static unsigned long shmem_default_max_blocks(void)
 110{
 111	return totalram_pages / 2;
 112}
 113
 114static unsigned long shmem_default_max_inodes(void)
 115{
 116	return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
 
 
 
 117}
 118#endif
 119
 120static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
 121static int shmem_replace_page(struct page **pagep, gfp_t gfp,
 122				struct shmem_inode_info *info, pgoff_t index);
 123static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 124		struct page **pagep, enum sgp_type sgp,
 125		gfp_t gfp, struct vm_area_struct *vma,
 126		struct vm_fault *vmf, int *fault_type);
 127
 128int shmem_getpage(struct inode *inode, pgoff_t index,
 129		struct page **pagep, enum sgp_type sgp)
 130{
 131	return shmem_getpage_gfp(inode, index, pagep, sgp,
 132		mapping_gfp_mask(inode->i_mapping), NULL, NULL, NULL);
 133}
 134
 135static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
 136{
 137	return sb->s_fs_info;
 138}
 139
 140/*
 141 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
 142 * for shared memory and for shared anonymous (/dev/zero) mappings
 143 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
 144 * consistent with the pre-accounting of private mappings ...
 145 */
 146static inline int shmem_acct_size(unsigned long flags, loff_t size)
 147{
 148	return (flags & VM_NORESERVE) ?
 149		0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
 150}
 151
 152static inline void shmem_unacct_size(unsigned long flags, loff_t size)
 153{
 154	if (!(flags & VM_NORESERVE))
 155		vm_unacct_memory(VM_ACCT(size));
 156}
 157
 158static inline int shmem_reacct_size(unsigned long flags,
 159		loff_t oldsize, loff_t newsize)
 160{
 161	if (!(flags & VM_NORESERVE)) {
 162		if (VM_ACCT(newsize) > VM_ACCT(oldsize))
 163			return security_vm_enough_memory_mm(current->mm,
 164					VM_ACCT(newsize) - VM_ACCT(oldsize));
 165		else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
 166			vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
 167	}
 168	return 0;
 169}
 170
 171/*
 172 * ... whereas tmpfs objects are accounted incrementally as
 173 * pages are allocated, in order to allow large sparse files.
 174 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
 175 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
 176 */
 177static inline int shmem_acct_block(unsigned long flags, long pages)
 178{
 179	if (!(flags & VM_NORESERVE))
 180		return 0;
 181
 182	return security_vm_enough_memory_mm(current->mm,
 183			pages * VM_ACCT(PAGE_SIZE));
 184}
 185
 186static inline void shmem_unacct_blocks(unsigned long flags, long pages)
 187{
 188	if (flags & VM_NORESERVE)
 189		vm_unacct_memory(pages * VM_ACCT(PAGE_SIZE));
 190}
 191
 192static inline bool shmem_inode_acct_block(struct inode *inode, long pages)
 193{
 194	struct shmem_inode_info *info = SHMEM_I(inode);
 195	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 
 196
 197	if (shmem_acct_block(info->flags, pages))
 198		return false;
 199
 
 200	if (sbinfo->max_blocks) {
 201		if (percpu_counter_compare(&sbinfo->used_blocks,
 202					   sbinfo->max_blocks - pages) > 0)
 
 
 
 
 
 
 
 
 
 
 203			goto unacct;
 204		percpu_counter_add(&sbinfo->used_blocks, pages);
 205	}
 206
 207	return true;
 208
 209unacct:
 210	shmem_unacct_blocks(info->flags, pages);
 211	return false;
 212}
 213
 214static inline void shmem_inode_unacct_blocks(struct inode *inode, long pages)
 215{
 216	struct shmem_inode_info *info = SHMEM_I(inode);
 217	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 218
 
 
 
 219	if (sbinfo->max_blocks)
 220		percpu_counter_sub(&sbinfo->used_blocks, pages);
 221	shmem_unacct_blocks(info->flags, pages);
 222}
 223
 224static const struct super_operations shmem_ops;
 225static const struct address_space_operations shmem_aops;
 226static const struct file_operations shmem_file_operations;
 227static const struct inode_operations shmem_inode_operations;
 228static const struct inode_operations shmem_dir_inode_operations;
 229static const struct inode_operations shmem_special_inode_operations;
 230static const struct vm_operations_struct shmem_vm_ops;
 
 231static struct file_system_type shmem_fs_type;
 232
 
 
 
 
 
 
 
 
 
 
 
 233bool vma_is_shmem(struct vm_area_struct *vma)
 234{
 235	return vma->vm_ops == &shmem_vm_ops;
 236}
 237
 238static LIST_HEAD(shmem_swaplist);
 239static DEFINE_MUTEX(shmem_swaplist_mutex);
 240
 241static int shmem_reserve_inode(struct super_block *sb)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 242{
 243	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 244	if (sbinfo->max_inodes) {
 245		spin_lock(&sbinfo->stat_lock);
 246		if (!sbinfo->free_inodes) {
 247			spin_unlock(&sbinfo->stat_lock);
 248			return -ENOSPC;
 
 
 
 
 
 249		}
 250		sbinfo->free_inodes--;
 251		spin_unlock(&sbinfo->stat_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 252	}
 
 253	return 0;
 254}
 255
 256static void shmem_free_inode(struct super_block *sb)
 257{
 258	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 259	if (sbinfo->max_inodes) {
 260		spin_lock(&sbinfo->stat_lock);
 261		sbinfo->free_inodes++;
 262		spin_unlock(&sbinfo->stat_lock);
 263	}
 264}
 265
 266/**
 267 * shmem_recalc_inode - recalculate the block usage of an inode
 268 * @inode: inode to recalc
 
 
 269 *
 270 * We have to calculate the free blocks since the mm can drop
 271 * undirtied hole pages behind our back.
 272 *
 273 * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
 274 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
 275 *
 276 * It has to be called with the spinlock held.
 277 */
 278static void shmem_recalc_inode(struct inode *inode)
 279{
 280	struct shmem_inode_info *info = SHMEM_I(inode);
 281	long freed;
 282
 283	freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
 284	if (freed > 0) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 285		info->alloced -= freed;
 286		inode->i_blocks -= freed * BLOCKS_PER_PAGE;
 
 
 
 287		shmem_inode_unacct_blocks(inode, freed);
 288	}
 289}
 290
 291bool shmem_charge(struct inode *inode, long pages)
 292{
 293	struct shmem_inode_info *info = SHMEM_I(inode);
 294	unsigned long flags;
 295
 296	if (!shmem_inode_acct_block(inode, pages))
 297		return false;
 298
 299	spin_lock_irqsave(&info->lock, flags);
 300	info->alloced += pages;
 301	inode->i_blocks += pages * BLOCKS_PER_PAGE;
 302	shmem_recalc_inode(inode);
 303	spin_unlock_irqrestore(&info->lock, flags);
 304	inode->i_mapping->nrpages += pages;
 305
 
 306	return true;
 307}
 308
 309void shmem_uncharge(struct inode *inode, long pages)
 310{
 311	struct shmem_inode_info *info = SHMEM_I(inode);
 312	unsigned long flags;
 313
 314	spin_lock_irqsave(&info->lock, flags);
 315	info->alloced -= pages;
 316	inode->i_blocks -= pages * BLOCKS_PER_PAGE;
 317	shmem_recalc_inode(inode);
 318	spin_unlock_irqrestore(&info->lock, flags);
 319
 320	shmem_inode_unacct_blocks(inode, pages);
 321}
 322
 323/*
 324 * Replace item expected in radix tree by a new item, while holding tree lock.
 325 */
 326static int shmem_radix_tree_replace(struct address_space *mapping,
 327			pgoff_t index, void *expected, void *replacement)
 328{
 329	struct radix_tree_node *node;
 330	void **pslot;
 331	void *item;
 332
 333	VM_BUG_ON(!expected);
 334	VM_BUG_ON(!replacement);
 335	item = __radix_tree_lookup(&mapping->i_pages, index, &node, &pslot);
 336	if (!item)
 337		return -ENOENT;
 338	if (item != expected)
 339		return -ENOENT;
 340	__radix_tree_replace(&mapping->i_pages, node, pslot,
 341			     replacement, NULL);
 342	return 0;
 343}
 344
 345/*
 346 * Sometimes, before we decide whether to proceed or to fail, we must check
 347 * that an entry was not already brought back from swap by a racing thread.
 348 *
 349 * Checking page is not enough: by the time a SwapCache page is locked, it
 350 * might be reused, and again be SwapCache, using the same swap as before.
 351 */
 352static bool shmem_confirm_swap(struct address_space *mapping,
 353			       pgoff_t index, swp_entry_t swap)
 354{
 355	void *item;
 356
 357	rcu_read_lock();
 358	item = radix_tree_lookup(&mapping->i_pages, index);
 359	rcu_read_unlock();
 360	return item == swp_to_radix_entry(swap);
 361}
 362
 363/*
 364 * Definitions for "huge tmpfs": tmpfs mounted with the huge= option
 365 *
 366 * SHMEM_HUGE_NEVER:
 367 *	disables huge pages for the mount;
 368 * SHMEM_HUGE_ALWAYS:
 369 *	enables huge pages for the mount;
 370 * SHMEM_HUGE_WITHIN_SIZE:
 371 *	only allocate huge pages if the page will be fully within i_size,
 372 *	also respect fadvise()/madvise() hints;
 373 * SHMEM_HUGE_ADVISE:
 374 *	only allocate huge pages if requested with fadvise()/madvise();
 375 */
 376
 377#define SHMEM_HUGE_NEVER	0
 378#define SHMEM_HUGE_ALWAYS	1
 379#define SHMEM_HUGE_WITHIN_SIZE	2
 380#define SHMEM_HUGE_ADVISE	3
 381
 382/*
 383 * Special values.
 384 * Only can be set via /sys/kernel/mm/transparent_hugepage/shmem_enabled:
 385 *
 386 * SHMEM_HUGE_DENY:
 387 *	disables huge on shm_mnt and all mounts, for emergency use;
 388 * SHMEM_HUGE_FORCE:
 389 *	enables huge on shm_mnt and all mounts, w/o needing option, for testing;
 390 *
 391 */
 392#define SHMEM_HUGE_DENY		(-1)
 393#define SHMEM_HUGE_FORCE	(-2)
 394
 395#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 396/* ifdef here to avoid bloating shmem.o when not necessary */
 397
 398int shmem_huge __read_mostly;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 399
 400#if defined(CONFIG_SYSFS) || defined(CONFIG_TMPFS)
 401static int shmem_parse_huge(const char *str)
 402{
 
 
 
 
 
 403	if (!strcmp(str, "never"))
 404		return SHMEM_HUGE_NEVER;
 405	if (!strcmp(str, "always"))
 406		return SHMEM_HUGE_ALWAYS;
 407	if (!strcmp(str, "within_size"))
 408		return SHMEM_HUGE_WITHIN_SIZE;
 409	if (!strcmp(str, "advise"))
 410		return SHMEM_HUGE_ADVISE;
 411	if (!strcmp(str, "deny"))
 412		return SHMEM_HUGE_DENY;
 413	if (!strcmp(str, "force"))
 414		return SHMEM_HUGE_FORCE;
 415	return -EINVAL;
 
 
 
 
 
 
 
 
 
 
 
 
 416}
 417
 
 418static const char *shmem_format_huge(int huge)
 419{
 420	switch (huge) {
 421	case SHMEM_HUGE_NEVER:
 422		return "never";
 423	case SHMEM_HUGE_ALWAYS:
 424		return "always";
 425	case SHMEM_HUGE_WITHIN_SIZE:
 426		return "within_size";
 427	case SHMEM_HUGE_ADVISE:
 428		return "advise";
 429	case SHMEM_HUGE_DENY:
 430		return "deny";
 431	case SHMEM_HUGE_FORCE:
 432		return "force";
 433	default:
 434		VM_BUG_ON(1);
 435		return "bad_val";
 436	}
 437}
 438#endif
 439
 440static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
 441		struct shrink_control *sc, unsigned long nr_to_split)
 442{
 443	LIST_HEAD(list), *pos, *next;
 444	LIST_HEAD(to_remove);
 445	struct inode *inode;
 446	struct shmem_inode_info *info;
 447	struct page *page;
 448	unsigned long batch = sc ? sc->nr_to_scan : 128;
 449	int removed = 0, split = 0;
 450
 451	if (list_empty(&sbinfo->shrinklist))
 452		return SHRINK_STOP;
 453
 454	spin_lock(&sbinfo->shrinklist_lock);
 455	list_for_each_safe(pos, next, &sbinfo->shrinklist) {
 456		info = list_entry(pos, struct shmem_inode_info, shrinklist);
 457
 458		/* pin the inode */
 459		inode = igrab(&info->vfs_inode);
 460
 461		/* inode is about to be evicted */
 462		if (!inode) {
 463			list_del_init(&info->shrinklist);
 464			removed++;
 465			goto next;
 466		}
 467
 468		/* Check if there's anything to gain */
 469		if (round_up(inode->i_size, PAGE_SIZE) ==
 470				round_up(inode->i_size, HPAGE_PMD_SIZE)) {
 471			list_move(&info->shrinklist, &to_remove);
 472			removed++;
 473			goto next;
 474		}
 475
 476		list_move(&info->shrinklist, &list);
 477next:
 
 478		if (!--batch)
 479			break;
 480	}
 481	spin_unlock(&sbinfo->shrinklist_lock);
 482
 483	list_for_each_safe(pos, next, &to_remove) {
 484		info = list_entry(pos, struct shmem_inode_info, shrinklist);
 485		inode = &info->vfs_inode;
 486		list_del_init(&info->shrinklist);
 487		iput(inode);
 488	}
 489
 490	list_for_each_safe(pos, next, &list) {
 
 
 491		int ret;
 492
 493		info = list_entry(pos, struct shmem_inode_info, shrinklist);
 494		inode = &info->vfs_inode;
 495
 496		if (nr_to_split && split >= nr_to_split)
 497			goto leave;
 
 
 
 
 
 498
 499		page = find_get_page(inode->i_mapping,
 500				(inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT);
 501		if (!page)
 502			goto drop;
 
 503
 504		/* No huge page at the end of the file: nothing to split */
 505		if (!PageTransHuge(page)) {
 506			put_page(page);
 
 
 507			goto drop;
 508		}
 509
 510		/*
 511		 * Leave the inode on the list if we failed to lock
 512		 * the page at this time.
 513		 *
 514		 * Waiting for the lock may lead to deadlock in the
 515		 * reclaim path.
 516		 */
 517		if (!trylock_page(page)) {
 518			put_page(page);
 519			goto leave;
 520		}
 521
 522		ret = split_huge_page(page);
 523		unlock_page(page);
 524		put_page(page);
 525
 526		/* If split failed leave the inode on the list */
 527		if (ret)
 528			goto leave;
 529
 
 530		split++;
 531drop:
 532		list_del_init(&info->shrinklist);
 533		removed++;
 534leave:
 
 
 
 
 
 
 
 
 
 
 
 535		iput(inode);
 536	}
 537
 538	spin_lock(&sbinfo->shrinklist_lock);
 539	list_splice_tail(&list, &sbinfo->shrinklist);
 540	sbinfo->shrinklist_len -= removed;
 541	spin_unlock(&sbinfo->shrinklist_lock);
 542
 543	return split;
 544}
 545
 546static long shmem_unused_huge_scan(struct super_block *sb,
 547		struct shrink_control *sc)
 548{
 549	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 550
 551	if (!READ_ONCE(sbinfo->shrinklist_len))
 552		return SHRINK_STOP;
 553
 554	return shmem_unused_huge_shrink(sbinfo, sc, 0);
 555}
 556
 557static long shmem_unused_huge_count(struct super_block *sb,
 558		struct shrink_control *sc)
 559{
 560	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 561	return READ_ONCE(sbinfo->shrinklist_len);
 562}
 563#else /* !CONFIG_TRANSPARENT_HUGE_PAGECACHE */
 564
 565#define shmem_huge SHMEM_HUGE_DENY
 566
 567static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo,
 568		struct shrink_control *sc, unsigned long nr_to_split)
 569{
 570	return 0;
 571}
 572#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 573
 574/*
 575 * Like add_to_page_cache_locked, but error if expected item has gone.
 576 */
 577static int shmem_add_to_page_cache(struct page *page,
 578				   struct address_space *mapping,
 579				   pgoff_t index, void *expected)
 580{
 581	int error, nr = hpage_nr_pages(page);
 
 582
 583	VM_BUG_ON_PAGE(PageTail(page), page);
 584	VM_BUG_ON_PAGE(index != round_down(index, nr), page);
 585	VM_BUG_ON_PAGE(!PageLocked(page), page);
 586	VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
 587	VM_BUG_ON(expected && PageTransHuge(page));
 588
 589	page_ref_add(page, nr);
 590	page->mapping = mapping;
 591	page->index = index;
 592
 593	xa_lock_irq(&mapping->i_pages);
 594	if (PageTransHuge(page)) {
 595		void __rcu **results;
 596		pgoff_t idx;
 597		int i;
 598
 599		error = 0;
 600		if (radix_tree_gang_lookup_slot(&mapping->i_pages,
 601					&results, &idx, index, 1) &&
 602				idx < index + HPAGE_PMD_NR) {
 603			error = -EEXIST;
 604		}
 605
 606		if (!error) {
 607			for (i = 0; i < HPAGE_PMD_NR; i++) {
 608				error = radix_tree_insert(&mapping->i_pages,
 609						index + i, page + i);
 610				VM_BUG_ON(error);
 611			}
 612			count_vm_event(THP_FILE_ALLOC);
 613		}
 614	} else if (!expected) {
 615		error = radix_tree_insert(&mapping->i_pages, index, page);
 616	} else {
 617		error = shmem_radix_tree_replace(mapping, index, expected,
 618								 page);
 619	}
 620
 621	if (!error) {
 622		mapping->nrpages += nr;
 623		if (PageTransHuge(page))
 624			__inc_node_page_state(page, NR_SHMEM_THPS);
 625		__mod_node_page_state(page_pgdat(page), NR_FILE_PAGES, nr);
 626		__mod_node_page_state(page_pgdat(page), NR_SHMEM, nr);
 627		xa_unlock_irq(&mapping->i_pages);
 628	} else {
 629		page->mapping = NULL;
 630		xa_unlock_irq(&mapping->i_pages);
 631		page_ref_sub(page, nr);
 632	}
 633	return error;
 
 634}
 635
 636/*
 637 * Like delete_from_page_cache, but substitutes swap for page.
 638 */
 639static void shmem_delete_from_page_cache(struct page *page, void *radswap)
 640{
 641	struct address_space *mapping = page->mapping;
 
 642	int error;
 643
 644	VM_BUG_ON_PAGE(PageCompound(page), page);
 645
 646	xa_lock_irq(&mapping->i_pages);
 647	error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
 648	page->mapping = NULL;
 649	mapping->nrpages--;
 650	__dec_node_page_state(page, NR_FILE_PAGES);
 651	__dec_node_page_state(page, NR_SHMEM);
 652	xa_unlock_irq(&mapping->i_pages);
 653	put_page(page);
 654	BUG_ON(error);
 655}
 656
 657/*
 658 * Remove swap entry from radix tree, free the swap and its page cache.
 
 
 659 */
 660static int shmem_free_swap(struct address_space *mapping,
 661			   pgoff_t index, void *radswap)
 662{
 
 663	void *old;
 664
 665	xa_lock_irq(&mapping->i_pages);
 666	old = radix_tree_delete_item(&mapping->i_pages, index, radswap);
 667	xa_unlock_irq(&mapping->i_pages);
 668	if (old != radswap)
 669		return -ENOENT;
 670	free_swap_and_cache(radix_to_swp_entry(radswap));
 671	return 0;
 
 672}
 673
 674/*
 675 * Determine (in bytes) how many of the shmem object's pages mapped by the
 676 * given offsets are swapped out.
 677 *
 678 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
 679 * as long as the inode doesn't go away and racy results are not a problem.
 680 */
 681unsigned long shmem_partial_swap_usage(struct address_space *mapping,
 682						pgoff_t start, pgoff_t end)
 683{
 684	struct radix_tree_iter iter;
 685	void **slot;
 686	struct page *page;
 687	unsigned long swapped = 0;
 
 688
 689	rcu_read_lock();
 690
 691	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
 692		if (iter.index >= end)
 693			break;
 694
 695		page = radix_tree_deref_slot(slot);
 696
 697		if (radix_tree_deref_retry(page)) {
 698			slot = radix_tree_iter_retry(&iter);
 699			continue;
 700		}
 701
 702		if (radix_tree_exceptional_entry(page))
 703			swapped++;
 704
 705		if (need_resched()) {
 706			slot = radix_tree_iter_resume(slot, &iter);
 707			cond_resched_rcu();
 708		}
 709	}
 710
 711	rcu_read_unlock();
 712
 713	return swapped << PAGE_SHIFT;
 714}
 715
 716/*
 717 * Determine (in bytes) how many of the shmem object's pages mapped by the
 718 * given vma is swapped out.
 719 *
 720 * This is safe to call without i_mutex or the i_pages lock thanks to RCU,
 721 * as long as the inode doesn't go away and racy results are not a problem.
 722 */
 723unsigned long shmem_swap_usage(struct vm_area_struct *vma)
 724{
 725	struct inode *inode = file_inode(vma->vm_file);
 726	struct shmem_inode_info *info = SHMEM_I(inode);
 727	struct address_space *mapping = inode->i_mapping;
 728	unsigned long swapped;
 729
 730	/* Be careful as we don't hold info->lock */
 731	swapped = READ_ONCE(info->swapped);
 732
 733	/*
 734	 * The easier cases are when the shmem object has nothing in swap, or
 735	 * the vma maps it whole. Then we can simply use the stats that we
 736	 * already track.
 737	 */
 738	if (!swapped)
 739		return 0;
 740
 741	if (!vma->vm_pgoff && vma->vm_end - vma->vm_start >= inode->i_size)
 742		return swapped << PAGE_SHIFT;
 743
 744	/* Here comes the more involved part */
 745	return shmem_partial_swap_usage(mapping,
 746			linear_page_index(vma, vma->vm_start),
 747			linear_page_index(vma, vma->vm_end));
 748}
 749
 750/*
 751 * SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
 752 */
 753void shmem_unlock_mapping(struct address_space *mapping)
 754{
 755	struct pagevec pvec;
 756	pgoff_t indices[PAGEVEC_SIZE];
 757	pgoff_t index = 0;
 758
 759	pagevec_init(&pvec);
 760	/*
 761	 * Minor point, but we might as well stop if someone else SHM_LOCKs it.
 762	 */
 763	while (!mapping_unevictable(mapping)) {
 764		/*
 765		 * Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
 766		 * has finished, if it hits a row of PAGEVEC_SIZE swap entries.
 767		 */
 768		pvec.nr = find_get_entries(mapping, index,
 769					   PAGEVEC_SIZE, pvec.pages, indices);
 770		if (!pvec.nr)
 771			break;
 772		index = indices[pvec.nr - 1] + 1;
 773		pagevec_remove_exceptionals(&pvec);
 774		check_move_unevictable_pages(pvec.pages, pvec.nr);
 775		pagevec_release(&pvec);
 776		cond_resched();
 777	}
 778}
 779
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 780/*
 781 * Remove range of pages and swap entries from radix tree, and free them.
 782 * If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
 783 */
 784static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 785								 bool unfalloc)
 786{
 787	struct address_space *mapping = inode->i_mapping;
 788	struct shmem_inode_info *info = SHMEM_I(inode);
 789	pgoff_t start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
 790	pgoff_t end = (lend + 1) >> PAGE_SHIFT;
 791	unsigned int partial_start = lstart & (PAGE_SIZE - 1);
 792	unsigned int partial_end = (lend + 1) & (PAGE_SIZE - 1);
 793	struct pagevec pvec;
 794	pgoff_t indices[PAGEVEC_SIZE];
 
 
 795	long nr_swaps_freed = 0;
 796	pgoff_t index;
 797	int i;
 798
 799	if (lend == -1)
 800		end = -1;	/* unsigned, so actually very big */
 801
 802	pagevec_init(&pvec);
 803	index = start;
 804	while (index < end) {
 805		pvec.nr = find_get_entries(mapping, index,
 806			min(end - index, (pgoff_t)PAGEVEC_SIZE),
 807			pvec.pages, indices);
 808		if (!pvec.nr)
 809			break;
 810		for (i = 0; i < pagevec_count(&pvec); i++) {
 811			struct page *page = pvec.pages[i];
 812
 813			index = indices[i];
 814			if (index >= end)
 815				break;
 
 
 
 816
 817			if (radix_tree_exceptional_entry(page)) {
 818				if (unfalloc)
 819					continue;
 820				nr_swaps_freed += !shmem_free_swap(mapping,
 821								index, page);
 822				continue;
 823			}
 824
 825			VM_BUG_ON_PAGE(page_to_pgoff(page) != index, page);
 826
 827			if (!trylock_page(page))
 828				continue;
 829
 830			if (PageTransTail(page)) {
 831				/* Middle of THP: zero out the page */
 832				clear_highpage(page);
 833				unlock_page(page);
 834				continue;
 835			} else if (PageTransHuge(page)) {
 836				if (index == round_down(end, HPAGE_PMD_NR)) {
 837					/*
 838					 * Range ends in the middle of THP:
 839					 * zero out the page
 840					 */
 841					clear_highpage(page);
 842					unlock_page(page);
 843					continue;
 844				}
 845				index += HPAGE_PMD_NR - 1;
 846				i += HPAGE_PMD_NR - 1;
 847			}
 848
 849			if (!unfalloc || !PageUptodate(page)) {
 850				VM_BUG_ON_PAGE(PageTail(page), page);
 851				if (page_mapping(page) == mapping) {
 852					VM_BUG_ON_PAGE(PageWriteback(page), page);
 853					truncate_inode_page(mapping, page);
 854				}
 855			}
 856			unlock_page(page);
 857		}
 858		pagevec_remove_exceptionals(&pvec);
 859		pagevec_release(&pvec);
 860		cond_resched();
 861		index++;
 862	}
 863
 864	if (partial_start) {
 865		struct page *page = NULL;
 866		shmem_getpage(inode, start - 1, &page, SGP_READ);
 867		if (page) {
 868			unsigned int top = PAGE_SIZE;
 869			if (start > end) {
 870				top = partial_end;
 871				partial_end = 0;
 872			}
 873			zero_user_segment(page, partial_start, top);
 874			set_page_dirty(page);
 875			unlock_page(page);
 876			put_page(page);
 877		}
 878	}
 879	if (partial_end) {
 880		struct page *page = NULL;
 881		shmem_getpage(inode, end, &page, SGP_READ);
 882		if (page) {
 883			zero_user_segment(page, 0, partial_end);
 884			set_page_dirty(page);
 885			unlock_page(page);
 886			put_page(page);
 887		}
 
 
 
 
 
 
 
 
 888	}
 889	if (start >= end)
 890		return;
 891
 892	index = start;
 893	while (index < end) {
 894		cond_resched();
 895
 896		pvec.nr = find_get_entries(mapping, index,
 897				min(end - index, (pgoff_t)PAGEVEC_SIZE),
 898				pvec.pages, indices);
 899		if (!pvec.nr) {
 900			/* If all gone or hole-punch or unfalloc, we're done */
 901			if (index == start || end != -1)
 902				break;
 903			/* But if truncating, restart to make sure all gone */
 904			index = start;
 905			continue;
 906		}
 907		for (i = 0; i < pagevec_count(&pvec); i++) {
 908			struct page *page = pvec.pages[i];
 909
 910			index = indices[i];
 911			if (index >= end)
 912				break;
 913
 914			if (radix_tree_exceptional_entry(page)) {
 915				if (unfalloc)
 916					continue;
 917				if (shmem_free_swap(mapping, index, page)) {
 
 918					/* Swap was replaced by page: retry */
 919					index--;
 920					break;
 921				}
 922				nr_swaps_freed++;
 923				continue;
 924			}
 925
 926			lock_page(page);
 927
 928			if (PageTransTail(page)) {
 929				/* Middle of THP: zero out the page */
 930				clear_highpage(page);
 931				unlock_page(page);
 932				/*
 933				 * Partial thp truncate due 'start' in middle
 934				 * of THP: don't need to look on these pages
 935				 * again on !pvec.nr restart.
 936				 */
 937				if (index != round_down(end, HPAGE_PMD_NR))
 938					start++;
 939				continue;
 940			} else if (PageTransHuge(page)) {
 941				if (index == round_down(end, HPAGE_PMD_NR)) {
 942					/*
 943					 * Range ends in the middle of THP:
 944					 * zero out the page
 945					 */
 946					clear_highpage(page);
 947					unlock_page(page);
 948					continue;
 949				}
 950				index += HPAGE_PMD_NR - 1;
 951				i += HPAGE_PMD_NR - 1;
 952			}
 953
 954			if (!unfalloc || !PageUptodate(page)) {
 955				VM_BUG_ON_PAGE(PageTail(page), page);
 956				if (page_mapping(page) == mapping) {
 957					VM_BUG_ON_PAGE(PageWriteback(page), page);
 958					truncate_inode_page(mapping, page);
 959				} else {
 960					/* Page was replaced by swap: retry */
 961					unlock_page(page);
 962					index--;
 963					break;
 964				}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 965			}
 966			unlock_page(page);
 967		}
 968		pagevec_remove_exceptionals(&pvec);
 969		pagevec_release(&pvec);
 970		index++;
 971	}
 972
 973	spin_lock_irq(&info->lock);
 974	info->swapped -= nr_swaps_freed;
 975	shmem_recalc_inode(inode);
 976	spin_unlock_irq(&info->lock);
 977}
 978
 979void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 980{
 981	shmem_undo_range(inode, lstart, lend, false);
 982	inode->i_ctime = inode->i_mtime = current_time(inode);
 
 983}
 984EXPORT_SYMBOL_GPL(shmem_truncate_range);
 985
 986static int shmem_getattr(const struct path *path, struct kstat *stat,
 
 987			 u32 request_mask, unsigned int query_flags)
 988{
 989	struct inode *inode = path->dentry->d_inode;
 990	struct shmem_inode_info *info = SHMEM_I(inode);
 991
 992	if (info->alloced - info->swapped != inode->i_mapping->nrpages) {
 993		spin_lock_irq(&info->lock);
 994		shmem_recalc_inode(inode);
 995		spin_unlock_irq(&info->lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 996	}
 997	generic_fillattr(inode, stat);
 998	return 0;
 999}
1000
1001static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 
1002{
1003	struct inode *inode = d_inode(dentry);
1004	struct shmem_inode_info *info = SHMEM_I(inode);
1005	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
1006	int error;
 
 
1007
1008	error = setattr_prepare(dentry, attr);
1009	if (error)
1010		return error;
1011
 
 
 
 
 
 
1012	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
1013		loff_t oldsize = inode->i_size;
1014		loff_t newsize = attr->ia_size;
1015
1016		/* protected by i_mutex */
1017		if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
1018		    (newsize > oldsize && (info->seals & F_SEAL_GROW)))
1019			return -EPERM;
1020
1021		if (newsize != oldsize) {
1022			error = shmem_reacct_size(SHMEM_I(inode)->flags,
1023					oldsize, newsize);
1024			if (error)
1025				return error;
1026			i_size_write(inode, newsize);
1027			inode->i_ctime = inode->i_mtime = current_time(inode);
 
 
1028		}
1029		if (newsize <= oldsize) {
1030			loff_t holebegin = round_up(newsize, PAGE_SIZE);
1031			if (oldsize > holebegin)
1032				unmap_mapping_range(inode->i_mapping,
1033							holebegin, 0, 1);
1034			if (info->alloced)
1035				shmem_truncate_range(inode,
1036							newsize, (loff_t)-1);
1037			/* unmap again to remove racily COWed private pages */
1038			if (oldsize > holebegin)
1039				unmap_mapping_range(inode->i_mapping,
1040							holebegin, 0, 1);
1041
1042			/*
1043			 * Part of the huge page can be beyond i_size: subject
1044			 * to shrink under memory pressure.
1045			 */
1046			if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
1047				spin_lock(&sbinfo->shrinklist_lock);
1048				/*
1049				 * _careful to defend against unlocked access to
1050				 * ->shrink_list in shmem_unused_huge_shrink()
1051				 */
1052				if (list_empty_careful(&info->shrinklist)) {
1053					list_add_tail(&info->shrinklist,
1054							&sbinfo->shrinklist);
1055					sbinfo->shrinklist_len++;
1056				}
1057				spin_unlock(&sbinfo->shrinklist_lock);
1058			}
1059		}
1060	}
1061
1062	setattr_copy(inode, attr);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1063	if (attr->ia_valid & ATTR_MODE)
1064		error = posix_acl_chmod(inode, inode->i_mode);
 
 
 
 
 
 
1065	return error;
1066}
1067
1068static void shmem_evict_inode(struct inode *inode)
1069{
1070	struct shmem_inode_info *info = SHMEM_I(inode);
1071	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 
1072
1073	if (inode->i_mapping->a_ops == &shmem_aops) {
1074		shmem_unacct_size(info->flags, inode->i_size);
1075		inode->i_size = 0;
 
1076		shmem_truncate_range(inode, 0, (loff_t)-1);
1077		if (!list_empty(&info->shrinklist)) {
1078			spin_lock(&sbinfo->shrinklist_lock);
1079			if (!list_empty(&info->shrinklist)) {
1080				list_del_init(&info->shrinklist);
1081				sbinfo->shrinklist_len--;
1082			}
1083			spin_unlock(&sbinfo->shrinklist_lock);
1084		}
1085		if (!list_empty(&info->swaplist)) {
 
 
 
1086			mutex_lock(&shmem_swaplist_mutex);
1087			list_del_init(&info->swaplist);
 
 
1088			mutex_unlock(&shmem_swaplist_mutex);
1089		}
1090	}
1091
1092	simple_xattrs_free(&info->xattrs);
 
1093	WARN_ON(inode->i_blocks);
1094	shmem_free_inode(inode->i_sb);
1095	clear_inode(inode);
 
 
 
 
1096}
1097
1098static unsigned long find_swap_entry(struct radix_tree_root *root, void *item)
1099{
1100	struct radix_tree_iter iter;
1101	void **slot;
1102	unsigned long found = -1;
1103	unsigned int checked = 0;
 
1104
1105	rcu_read_lock();
1106	radix_tree_for_each_slot(slot, root, &iter, 0) {
1107		if (*slot == item) {
1108			found = iter.index;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1109			break;
 
 
 
 
1110		}
1111		checked++;
1112		if ((checked % 4096) != 0)
1113			continue;
1114		slot = radix_tree_iter_resume(slot, &iter);
1115		cond_resched_rcu();
1116	}
1117
1118	rcu_read_unlock();
1119	return found;
 
1120}
1121
1122/*
1123 * If swap found in inode, free it and move page from swapcache to filecache.
 
1124 */
1125static int shmem_unuse_inode(struct shmem_inode_info *info,
1126			     swp_entry_t swap, struct page **pagep)
1127{
1128	struct address_space *mapping = info->vfs_inode.i_mapping;
1129	void *radswap;
1130	pgoff_t index;
1131	gfp_t gfp;
1132	int error = 0;
 
1133
1134	radswap = swp_to_radix_entry(swap);
1135	index = find_swap_entry(&mapping->i_pages, radswap);
1136	if (index == -1)
1137		return -EAGAIN;	/* tell shmem_unuse we found nothing */
1138
1139	/*
1140	 * Move _head_ to start search for next from here.
1141	 * But be careful: shmem_evict_inode checks list_empty without taking
1142	 * mutex, and there's an instant in list_move_tail when info->swaplist
1143	 * would appear empty, if it were the only one on shmem_swaplist.
1144	 */
1145	if (shmem_swaplist.next != &info->swaplist)
1146		list_move_tail(&shmem_swaplist, &info->swaplist);
1147
1148	gfp = mapping_gfp_mask(mapping);
1149	if (shmem_should_replace_page(*pagep, gfp)) {
1150		mutex_unlock(&shmem_swaplist_mutex);
1151		error = shmem_replace_page(pagep, gfp, info, index);
1152		mutex_lock(&shmem_swaplist_mutex);
1153		/*
1154		 * We needed to drop mutex to make that restrictive page
1155		 * allocation, but the inode might have been freed while we
1156		 * dropped it: although a racing shmem_evict_inode() cannot
1157		 * complete without emptying the radix_tree, our page lock
1158		 * on this swapcache page is not enough to prevent that -
1159		 * free_swap_and_cache() of our swap entry will only
1160		 * trylock_page(), removing swap from radix_tree whatever.
1161		 *
1162		 * We must not proceed to shmem_add_to_page_cache() if the
1163		 * inode has been freed, but of course we cannot rely on
1164		 * inode or mapping or info to check that.  However, we can
1165		 * safely check if our swap entry is still in use (and here
1166		 * it can't have got reused for another page): if it's still
1167		 * in use, then the inode cannot have been freed yet, and we
1168		 * can safely proceed (if it's no longer in use, that tells
1169		 * nothing about the inode, but we don't need to unuse swap).
1170		 */
1171		if (!page_swapcount(*pagep))
1172			error = -ENOENT;
1173	}
 
 
1174
1175	/*
1176	 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
1177	 * but also to hold up shmem_evict_inode(): so inode cannot be freed
1178	 * beneath us (pagelock doesn't help until the page is in pagecache).
1179	 */
1180	if (!error)
1181		error = shmem_add_to_page_cache(*pagep, mapping, index,
1182						radswap);
1183	if (error != -ENOMEM) {
1184		/*
1185		 * Truncation and eviction use free_swap_and_cache(), which
1186		 * only does trylock page: if we raced, best clean up here.
1187		 */
1188		delete_from_swap_cache(*pagep);
1189		set_page_dirty(*pagep);
1190		if (!error) {
1191			spin_lock_irq(&info->lock);
1192			info->swapped--;
1193			spin_unlock_irq(&info->lock);
1194			swap_free(swap);
1195		}
1196	}
1197	return error;
 
 
 
 
 
 
 
1198}
1199
1200/*
1201 * Search through swapped inodes to find and replace swap by page.
 
 
1202 */
1203int shmem_unuse(swp_entry_t swap, struct page *page)
1204{
1205	struct list_head *this, *next;
1206	struct shmem_inode_info *info;
1207	struct mem_cgroup *memcg;
1208	int error = 0;
1209
1210	/*
1211	 * There's a faint possibility that swap page was replaced before
1212	 * caller locked it: caller will come back later with the right page.
1213	 */
1214	if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
1215		goto out;
1216
1217	/*
1218	 * Charge page using GFP_KERNEL while we can wait, before taking
1219	 * the shmem_swaplist_mutex which might hold up shmem_writepage().
1220	 * Charged back to the user (not to caller) when swap account is used.
1221	 */
1222	error = mem_cgroup_try_charge(page, current->mm, GFP_KERNEL, &memcg,
1223			false);
1224	if (error)
1225		goto out;
1226	/* No radix_tree_preload: swap entry keeps a place for page in tree */
1227	error = -EAGAIN;
1228
1229	mutex_lock(&shmem_swaplist_mutex);
1230	list_for_each_safe(this, next, &shmem_swaplist) {
1231		info = list_entry(this, struct shmem_inode_info, swaplist);
1232		if (info->swapped)
1233			error = shmem_unuse_inode(info, swap, &page);
1234		else
1235			list_del_init(&info->swaplist);
 
 
 
 
 
 
 
 
 
 
 
 
1236		cond_resched();
1237		if (error != -EAGAIN)
 
 
 
 
 
 
 
1238			break;
1239		/* found nothing in this: move on to search the next */
1240	}
1241	mutex_unlock(&shmem_swaplist_mutex);
1242
1243	if (error) {
1244		if (error != -ENOMEM)
1245			error = 0;
1246		mem_cgroup_cancel_charge(page, memcg, false);
1247	} else
1248		mem_cgroup_commit_charge(page, memcg, true, false);
1249out:
1250	unlock_page(page);
1251	put_page(page);
1252	return error;
1253}
1254
1255/*
1256 * Move the page from the page cache to the swap cache.
1257 */
1258static int shmem_writepage(struct page *page, struct writeback_control *wbc)
1259{
1260	struct shmem_inode_info *info;
1261	struct address_space *mapping;
1262	struct inode *inode;
 
 
1263	swp_entry_t swap;
1264	pgoff_t index;
1265
1266	VM_BUG_ON_PAGE(PageCompound(page), page);
1267	BUG_ON(!PageLocked(page));
1268	mapping = page->mapping;
1269	index = page->index;
1270	inode = mapping->host;
1271	info = SHMEM_I(inode);
1272	if (info->flags & VM_LOCKED)
1273		goto redirty;
1274	if (!total_swap_pages)
1275		goto redirty;
1276
1277	/*
1278	 * Our capabilities prevent regular writeback or sync from ever calling
1279	 * shmem_writepage; but a stacking filesystem might use ->writepage of
1280	 * its underlying filesystem, in which case tmpfs should write out to
1281	 * swap only in response to memory pressure, and not for the writeback
1282	 * threads or sync.
1283	 */
1284	if (!wbc->for_reclaim) {
1285		WARN_ON_ONCE(1);	/* Still happens? Tell us about it! */
1286		goto redirty;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1287	}
1288
 
 
 
1289	/*
1290	 * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
1291	 * value into swapfile.c, the only way we can correctly account for a
1292	 * fallocated page arriving here is now to initialize it and write it.
1293	 *
1294	 * That's okay for a page already fallocated earlier, but if we have
1295	 * not yet completed the fallocation, then (a) we want to keep track
1296	 * of this page in case we have to undo it, and (b) it may not be a
1297	 * good idea to continue anyway, once we're pushing into swap.  So
1298	 * reactivate the page, and let shmem_fallocate() quit when too many.
1299	 */
1300	if (!PageUptodate(page)) {
1301		if (inode->i_private) {
1302			struct shmem_falloc *shmem_falloc;
1303			spin_lock(&inode->i_lock);
1304			shmem_falloc = inode->i_private;
1305			if (shmem_falloc &&
1306			    !shmem_falloc->waitq &&
1307			    index >= shmem_falloc->start &&
1308			    index < shmem_falloc->next)
1309				shmem_falloc->nr_unswapped++;
1310			else
1311				shmem_falloc = NULL;
1312			spin_unlock(&inode->i_lock);
1313			if (shmem_falloc)
1314				goto redirty;
1315		}
1316		clear_highpage(page);
1317		flush_dcache_page(page);
1318		SetPageUptodate(page);
1319	}
1320
1321	swap = get_swap_page(page);
1322	if (!swap.val)
1323		goto redirty;
 
1324
1325	if (mem_cgroup_try_charge_swap(page, swap))
1326		goto free_swap;
1327
1328	/*
1329	 * Add inode to shmem_unuse()'s list of swapped-out inodes,
1330	 * if it's not already there.  Do it now before the page is
1331	 * moved to swap cache, when its pagelock no longer protects
1332	 * the inode from eviction.  But don't unlock the mutex until
1333	 * we've incremented swapped, because shmem_unuse_inode() will
1334	 * prune a !swapped inode from the swaplist under this mutex.
1335	 */
1336	mutex_lock(&shmem_swaplist_mutex);
1337	if (list_empty(&info->swaplist))
1338		list_add_tail(&info->swaplist, &shmem_swaplist);
1339
1340	if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1341		spin_lock_irq(&info->lock);
1342		shmem_recalc_inode(inode);
1343		info->swapped++;
1344		spin_unlock_irq(&info->lock);
1345
1346		swap_shmem_alloc(swap);
1347		shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
1348
1349		mutex_unlock(&shmem_swaplist_mutex);
1350		BUG_ON(page_mapped(page));
1351		swap_writepage(page, wbc);
1352		return 0;
1353	}
1354
1355	mutex_unlock(&shmem_swaplist_mutex);
1356free_swap:
1357	put_swap_page(page, swap);
1358redirty:
1359	set_page_dirty(page);
1360	if (wbc->for_reclaim)
1361		return AOP_WRITEPAGE_ACTIVATE;	/* Return with page locked */
1362	unlock_page(page);
1363	return 0;
1364}
1365
1366#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
1367static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1368{
1369	char buffer[64];
1370
1371	if (!mpol || mpol->mode == MPOL_DEFAULT)
1372		return;		/* show nothing */
1373
1374	mpol_to_str(buffer, sizeof(buffer), mpol);
1375
1376	seq_printf(seq, ",mpol=%s", buffer);
1377}
1378
1379static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1380{
1381	struct mempolicy *mpol = NULL;
1382	if (sbinfo->mpol) {
1383		spin_lock(&sbinfo->stat_lock);	/* prevent replace/use races */
1384		mpol = sbinfo->mpol;
1385		mpol_get(mpol);
1386		spin_unlock(&sbinfo->stat_lock);
1387	}
1388	return mpol;
1389}
1390#else /* !CONFIG_NUMA || !CONFIG_TMPFS */
1391static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1392{
1393}
1394static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
1395{
1396	return NULL;
1397}
1398#endif /* CONFIG_NUMA && CONFIG_TMPFS */
1399#ifndef CONFIG_NUMA
1400#define vm_policy vm_private_data
1401#endif
1402
1403static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
1404		struct shmem_inode_info *info, pgoff_t index)
 
 
 
1405{
1406	/* Create a pseudo vma that just contains the policy */
1407	vma->vm_start = 0;
1408	/* Bias interleave by inode number to distribute better across nodes */
1409	vma->vm_pgoff = index + info->vfs_inode.i_ino;
1410	vma->vm_ops = NULL;
1411	vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
 
 
 
1412}
1413
1414static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
 
 
 
 
1415{
1416	/* Drop reference taken by mpol_shared_policy_lookup() */
1417	mpol_cond_put(vma->vm_policy);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1418}
1419
1420static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
1421			struct shmem_inode_info *info, pgoff_t index)
1422{
1423	struct vm_area_struct pvma;
1424	struct page *page;
1425	struct vm_fault vmf;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1426
1427	shmem_pseudo_vma_init(&pvma, info, index);
1428	vmf.vma = &pvma;
1429	vmf.address = 0;
1430	page = swap_cluster_readahead(swap, gfp, &vmf);
1431	shmem_pseudo_vma_destroy(&pvma);
1432
1433	return page;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1434}
1435
1436static struct page *shmem_alloc_hugepage(gfp_t gfp,
1437		struct shmem_inode_info *info, pgoff_t index)
 
1438{
1439	struct vm_area_struct pvma;
1440	struct inode *inode = &info->vfs_inode;
1441	struct address_space *mapping = inode->i_mapping;
1442	pgoff_t idx, hindex;
1443	void __rcu **results;
1444	struct page *page;
1445
1446	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1447		return NULL;
 
 
 
1448
1449	hindex = round_down(index, HPAGE_PMD_NR);
1450	rcu_read_lock();
1451	if (radix_tree_gang_lookup_slot(&mapping->i_pages, &results, &idx,
1452				hindex, 1) && idx < hindex + HPAGE_PMD_NR) {
1453		rcu_read_unlock();
1454		return NULL;
 
 
 
 
 
 
 
 
 
 
 
1455	}
1456	rcu_read_unlock();
1457
1458	shmem_pseudo_vma_init(&pvma, info, hindex);
1459	page = alloc_pages_vma(gfp | __GFP_COMP | __GFP_NORETRY | __GFP_NOWARN,
1460			HPAGE_PMD_ORDER, &pvma, 0, numa_node_id(), true);
1461	shmem_pseudo_vma_destroy(&pvma);
1462	if (page)
1463		prep_transhuge_page(page);
1464	return page;
 
1465}
 
1466
1467static struct page *shmem_alloc_page(gfp_t gfp,
1468			struct shmem_inode_info *info, pgoff_t index)
1469{
1470	struct vm_area_struct pvma;
1471	struct page *page;
 
1472
1473	shmem_pseudo_vma_init(&pvma, info, index);
1474	page = alloc_page_vma(gfp, &pvma, 0);
1475	shmem_pseudo_vma_destroy(&pvma);
1476
1477	return page;
1478}
1479
1480static struct page *shmem_alloc_and_acct_page(gfp_t gfp,
1481		struct inode *inode,
1482		pgoff_t index, bool huge)
1483{
 
1484	struct shmem_inode_info *info = SHMEM_I(inode);
1485	struct page *page;
1486	int nr;
1487	int err = -ENOSPC;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1488
1489	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
1490		huge = false;
1491	nr = huge ? HPAGE_PMD_NR : 1;
1492
1493	if (!shmem_inode_acct_block(inode, nr))
1494		goto failed;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1495
1496	if (huge)
1497		page = shmem_alloc_hugepage(gfp, info, index);
1498	else
1499		page = shmem_alloc_page(gfp, info, index);
1500	if (page) {
1501		__SetPageLocked(page);
1502		__SetPageSwapBacked(page);
1503		return page;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1504	}
1505
1506	err = -ENOMEM;
1507	shmem_inode_unacct_blocks(inode, nr);
1508failed:
1509	return ERR_PTR(err);
 
 
 
 
1510}
1511
1512/*
1513 * When a page is moved from swapcache to shmem filecache (either by the
1514 * usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
1515 * shmem_unuse_inode()), it may have been read in earlier from swap, in
1516 * ignorance of the mapping it belongs to.  If that mapping has special
1517 * constraints (like the gma500 GEM driver, which requires RAM below 4GB),
1518 * we may need to copy to a suitable page before moving to filecache.
1519 *
1520 * In a future release, this may well be extended to respect cpuset and
1521 * NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
1522 * but for now it is a simple matter of zone.
1523 */
1524static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
1525{
1526	return page_zonenum(page) > gfp_zone(gfp);
1527}
1528
1529static int shmem_replace_page(struct page **pagep, gfp_t gfp,
1530				struct shmem_inode_info *info, pgoff_t index)
1531{
1532	struct page *oldpage, *newpage;
1533	struct address_space *swap_mapping;
1534	pgoff_t swap_index;
1535	int error;
1536
1537	oldpage = *pagep;
1538	swap_index = page_private(oldpage);
1539	swap_mapping = page_mapping(oldpage);
1540
1541	/*
1542	 * We have arrived here because our zones are constrained, so don't
1543	 * limit chance of success by further cpuset and node constraints.
1544	 */
1545	gfp &= ~GFP_CONSTRAINT_MASK;
1546	newpage = shmem_alloc_page(gfp, info, index);
1547	if (!newpage)
 
 
 
 
 
 
 
 
1548		return -ENOMEM;
1549
1550	get_page(newpage);
1551	copy_highpage(newpage, oldpage);
1552	flush_dcache_page(newpage);
1553
1554	__SetPageLocked(newpage);
1555	__SetPageSwapBacked(newpage);
1556	SetPageUptodate(newpage);
1557	set_page_private(newpage, swap_index);
1558	SetPageSwapCache(newpage);
1559
1560	/*
1561	 * Our caller will very soon move newpage out of swapcache, but it's
1562	 * a nice clean interface for us to replace oldpage by newpage there.
1563	 */
1564	xa_lock_irq(&swap_mapping->i_pages);
1565	error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
1566								   newpage);
 
 
 
 
 
 
 
 
 
1567	if (!error) {
1568		__inc_node_page_state(newpage, NR_FILE_PAGES);
1569		__dec_node_page_state(oldpage, NR_FILE_PAGES);
 
1570	}
1571	xa_unlock_irq(&swap_mapping->i_pages);
1572
1573	if (unlikely(error)) {
1574		/*
1575		 * Is this possible?  I think not, now that our callers check
1576		 * both PageSwapCache and page_private after getting page lock;
1577		 * but be defensive.  Reverse old to newpage for clear and free.
 
1578		 */
1579		oldpage = newpage;
1580	} else {
1581		mem_cgroup_migrate(oldpage, newpage);
1582		lru_cache_add_anon(newpage);
1583		*pagep = newpage;
1584	}
1585
1586	ClearPageSwapCache(oldpage);
1587	set_page_private(oldpage, 0);
1588
1589	unlock_page(oldpage);
1590	put_page(oldpage);
1591	put_page(oldpage);
 
 
 
 
1592	return error;
1593}
1594
1595/*
1596 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
1597 *
1598 * If we allocate a new one we do not mark it dirty. That's up to the
1599 * vm. If we swap it in we mark it dirty since we also free the swap
1600 * entry since a page cannot live in both the swap and page cache.
1601 *
1602 * fault_mm and fault_type are only supplied by shmem_fault:
1603 * otherwise they are NULL.
1604 */
1605static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
1606	struct page **pagep, enum sgp_type sgp, gfp_t gfp,
1607	struct vm_area_struct *vma, struct vm_fault *vmf, int *fault_type)
1608{
1609	struct address_space *mapping = inode->i_mapping;
1610	struct shmem_inode_info *info = SHMEM_I(inode);
1611	struct shmem_sb_info *sbinfo;
1612	struct mm_struct *charge_mm;
1613	struct mem_cgroup *memcg;
1614	struct page *page;
1615	swp_entry_t swap;
1616	enum sgp_type sgp_huge = sgp;
1617	pgoff_t hindex = index;
1618	int error;
1619	int once = 0;
1620	int alloced = 0;
1621
1622	if (index > (MAX_LFS_FILESIZE >> PAGE_SHIFT))
1623		return -EFBIG;
1624	if (sgp == SGP_NOHUGE || sgp == SGP_HUGE)
1625		sgp = SGP_CACHE;
1626repeat:
1627	swap.val = 0;
1628	page = find_lock_entry(mapping, index);
1629	if (radix_tree_exceptional_entry(page)) {
1630		swap = radix_to_swp_entry(page);
1631		page = NULL;
1632	}
1633
1634	if (sgp <= SGP_CACHE &&
1635	    ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1636		error = -EINVAL;
1637		goto unlock;
1638	}
1639
1640	if (page && sgp == SGP_WRITE)
1641		mark_page_accessed(page);
1642
1643	/* fallocated page? */
1644	if (page && !PageUptodate(page)) {
1645		if (sgp != SGP_READ)
1646			goto clear;
1647		unlock_page(page);
1648		put_page(page);
1649		page = NULL;
1650	}
1651	if (page || (sgp == SGP_READ && !swap.val)) {
1652		*pagep = page;
1653		return 0;
1654	}
1655
 
 
 
1656	/*
1657	 * Fast cache lookup did not find it:
1658	 * bring it back from swap or allocate.
 
1659	 */
1660	sbinfo = SHMEM_SB(inode->i_sb);
1661	charge_mm = vma ? vma->vm_mm : current->mm;
 
1662
1663	if (swap.val) {
1664		/* Look it up and read it in.. */
1665		page = lookup_swap_cache(swap, NULL, 0);
1666		if (!page) {
1667			/* Or update major stats only when swapin succeeds?? */
1668			if (fault_type) {
1669				*fault_type |= VM_FAULT_MAJOR;
1670				count_vm_event(PGMAJFAULT);
1671				count_memcg_event_mm(charge_mm, PGMAJFAULT);
1672			}
1673			/* Here we actually start the io */
1674			page = shmem_swapin(swap, gfp, info, index);
1675			if (!page) {
1676				error = -ENOMEM;
1677				goto failed;
1678			}
1679		}
1680
1681		/* We have to do this with page locked to prevent races */
1682		lock_page(page);
1683		if (!PageSwapCache(page) || page_private(page) != swap.val ||
1684		    !shmem_confirm_swap(mapping, index, swap)) {
1685			error = -EEXIST;	/* try again */
 
 
 
1686			goto unlock;
1687		}
1688		if (!PageUptodate(page)) {
1689			error = -EIO;
1690			goto failed;
1691		}
1692		wait_on_page_writeback(page);
1693
1694		if (shmem_should_replace_page(page, gfp)) {
1695			error = shmem_replace_page(&page, gfp, info, index);
1696			if (error)
1697				goto failed;
 
 
 
1698		}
1699
1700		error = mem_cgroup_try_charge(page, charge_mm, gfp, &memcg,
1701				false);
1702		if (!error) {
1703			error = shmem_add_to_page_cache(page, mapping, index,
1704						swp_to_radix_entry(swap));
 
 
 
1705			/*
1706			 * We already confirmed swap under page lock, and make
1707			 * no memory allocation here, so usually no possibility
1708			 * of error; but free_swap_and_cache() only trylocks a
1709			 * page, so it is just possible that the entry has been
1710			 * truncated or holepunched since swap was confirmed.
1711			 * shmem_undo_range() will have done some of the
1712			 * unaccounting, now delete_from_swap_cache() will do
1713			 * the rest.
1714			 * Reset swap.val? No, leave it so "failed" goes back to
1715			 * "repeat": reading a hole and writing should succeed.
1716			 */
1717			if (error) {
1718				mem_cgroup_cancel_charge(page, memcg, false);
1719				delete_from_swap_cache(page);
 
 
 
 
1720			}
1721		}
1722		if (error)
1723			goto failed;
1724
1725		mem_cgroup_commit_charge(page, memcg, true, false);
 
1726
1727		spin_lock_irq(&info->lock);
1728		info->swapped--;
1729		shmem_recalc_inode(inode);
1730		spin_unlock_irq(&info->lock);
 
 
 
 
 
 
1731
1732		if (sgp == SGP_WRITE)
1733			mark_page_accessed(page);
 
1734
1735		delete_from_swap_cache(page);
1736		set_page_dirty(page);
1737		swap_free(swap);
1738
1739	} else {
1740		if (vma && userfaultfd_missing(vma)) {
1741			*fault_type = handle_userfault(vmf, VM_UFFD_MISSING);
1742			return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1743		}
1744
1745		/* shmem_symlink() */
1746		if (mapping->a_ops != &shmem_aops)
1747			goto alloc_nohuge;
1748		if (shmem_huge == SHMEM_HUGE_DENY || sgp_huge == SGP_NOHUGE)
1749			goto alloc_nohuge;
1750		if (shmem_huge == SHMEM_HUGE_FORCE)
1751			goto alloc_huge;
1752		switch (sbinfo->huge) {
1753			loff_t i_size;
1754			pgoff_t off;
1755		case SHMEM_HUGE_NEVER:
1756			goto alloc_nohuge;
1757		case SHMEM_HUGE_WITHIN_SIZE:
1758			off = round_up(index, HPAGE_PMD_NR);
1759			i_size = round_up(i_size_read(inode), PAGE_SIZE);
1760			if (i_size >= HPAGE_PMD_SIZE &&
1761					i_size >> PAGE_SHIFT >= off)
1762				goto alloc_huge;
1763			/* fallthrough */
1764		case SHMEM_HUGE_ADVISE:
1765			if (sgp_huge == SGP_HUGE)
1766				goto alloc_huge;
1767			/* TODO: implement fadvise() hints */
1768			goto alloc_nohuge;
1769		}
1770
1771alloc_huge:
1772		page = shmem_alloc_and_acct_page(gfp, inode, index, true);
1773		if (IS_ERR(page)) {
1774alloc_nohuge:		page = shmem_alloc_and_acct_page(gfp, inode,
1775					index, false);
1776		}
1777		if (IS_ERR(page)) {
1778			int retry = 5;
1779			error = PTR_ERR(page);
1780			page = NULL;
1781			if (error != -ENOSPC)
1782				goto failed;
1783			/*
1784			 * Try to reclaim some spece by splitting a huge page
1785			 * beyond i_size on the filesystem.
1786			 */
1787			while (retry--) {
1788				int ret;
1789				ret = shmem_unused_huge_shrink(sbinfo, NULL, 1);
1790				if (ret == SHRINK_STOP)
1791					break;
1792				if (ret)
1793					goto alloc_nohuge;
1794			}
1795			goto failed;
1796		}
1797
1798		if (PageTransHuge(page))
1799			hindex = round_down(index, HPAGE_PMD_NR);
1800		else
1801			hindex = index;
1802
1803		if (sgp == SGP_WRITE)
1804			__SetPageReferenced(page);
1805
1806		error = mem_cgroup_try_charge(page, charge_mm, gfp, &memcg,
1807				PageTransHuge(page));
1808		if (error)
1809			goto unacct;
1810		error = radix_tree_maybe_preload_order(gfp & GFP_RECLAIM_MASK,
1811				compound_order(page));
1812		if (!error) {
1813			error = shmem_add_to_page_cache(page, mapping, hindex,
1814							NULL);
1815			radix_tree_preload_end();
1816		}
1817		if (error) {
1818			mem_cgroup_cancel_charge(page, memcg,
1819					PageTransHuge(page));
1820			goto unacct;
 
 
1821		}
1822		mem_cgroup_commit_charge(page, memcg, false,
1823				PageTransHuge(page));
1824		lru_cache_add_anon(page);
1825
1826		spin_lock_irq(&info->lock);
1827		info->alloced += 1 << compound_order(page);
1828		inode->i_blocks += BLOCKS_PER_PAGE << compound_order(page);
1829		shmem_recalc_inode(inode);
1830		spin_unlock_irq(&info->lock);
1831		alloced = true;
1832
1833		if (PageTransHuge(page) &&
1834				DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE) <
1835				hindex + HPAGE_PMD_NR - 1) {
1836			/*
1837			 * Part of the huge page is beyond i_size: subject
1838			 * to shrink under memory pressure.
1839			 */
1840			spin_lock(&sbinfo->shrinklist_lock);
1841			/*
1842			 * _careful to defend against unlocked access to
1843			 * ->shrink_list in shmem_unused_huge_shrink()
1844			 */
1845			if (list_empty_careful(&info->shrinklist)) {
1846				list_add_tail(&info->shrinklist,
1847						&sbinfo->shrinklist);
1848				sbinfo->shrinklist_len++;
1849			}
1850			spin_unlock(&sbinfo->shrinklist_lock);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1851		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1852
 
 
 
 
 
 
 
1853		/*
1854		 * Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
 
1855		 */
1856		if (sgp == SGP_FALLOC)
1857			sgp = SGP_WRITE;
1858clear:
1859		/*
1860		 * Let SGP_WRITE caller clear ends if write does not fill page;
1861		 * but SGP_FALLOC on a page fallocated earlier must initialize
1862		 * it now, lest undo on failure cancel our earlier guarantee.
1863		 */
1864		if (sgp != SGP_WRITE && !PageUptodate(page)) {
1865			struct page *head = compound_head(page);
1866			int i;
1867
1868			for (i = 0; i < (1 << compound_order(head)); i++) {
1869				clear_highpage(head + i);
1870				flush_dcache_page(head + i);
1871			}
1872			SetPageUptodate(head);
1873		}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1874	}
1875
1876	/* Perhaps the file has been truncated since we checked */
1877	if (sgp <= SGP_CACHE &&
1878	    ((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) {
1879		if (alloced) {
1880			ClearPageDirty(page);
1881			delete_from_page_cache(page);
1882			spin_lock_irq(&info->lock);
1883			shmem_recalc_inode(inode);
1884			spin_unlock_irq(&info->lock);
1885		}
1886		error = -EINVAL;
1887		goto unlock;
1888	}
1889	*pagep = page + index - hindex;
 
1890	return 0;
1891
1892	/*
1893	 * Error recovery.
1894	 */
1895unacct:
1896	shmem_inode_unacct_blocks(inode, 1 << compound_order(page));
1897
1898	if (PageTransHuge(page)) {
1899		unlock_page(page);
1900		put_page(page);
1901		goto alloc_nohuge;
1902	}
1903failed:
1904	if (swap.val && !shmem_confirm_swap(mapping, index, swap))
1905		error = -EEXIST;
1906unlock:
1907	if (page) {
1908		unlock_page(page);
1909		put_page(page);
1910	}
1911	if (error == -ENOSPC && !once++) {
1912		spin_lock_irq(&info->lock);
1913		shmem_recalc_inode(inode);
1914		spin_unlock_irq(&info->lock);
1915		goto repeat;
1916	}
1917	if (error == -EEXIST)	/* from above or from radix_tree_insert */
1918		goto repeat;
1919	return error;
1920}
1921
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1922/*
1923 * This is like autoremove_wake_function, but it removes the wait queue
1924 * entry unconditionally - even if something else had already woken the
1925 * target.
1926 */
1927static int synchronous_wake_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *key)
 
1928{
1929	int ret = default_wake_function(wait, mode, sync, key);
1930	list_del_init(&wait->entry);
1931	return ret;
1932}
1933
1934static int shmem_fault(struct vm_fault *vmf)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1935{
1936	struct vm_area_struct *vma = vmf->vma;
1937	struct inode *inode = file_inode(vma->vm_file);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1938	gfp_t gfp = mapping_gfp_mask(inode->i_mapping);
1939	enum sgp_type sgp;
1940	int error;
1941	int ret = VM_FAULT_LOCKED;
1942
1943	/*
1944	 * Trinity finds that probing a hole which tmpfs is punching can
1945	 * prevent the hole-punch from ever completing: which in turn
1946	 * locks writers out with its hold on i_mutex.  So refrain from
1947	 * faulting pages into the hole while it's being punched.  Although
1948	 * shmem_undo_range() does remove the additions, it may be unable to
1949	 * keep up, as each new page needs its own unmap_mapping_range() call,
1950	 * and the i_mmap tree grows ever slower to scan if new vmas are added.
1951	 *
1952	 * It does not matter if we sometimes reach this check just before the
1953	 * hole-punch begins, so that one fault then races with the punch:
1954	 * we just need to make racing faults a rare case.
1955	 *
1956	 * The implementation below would be much simpler if we just used a
1957	 * standard mutex or completion: but we cannot take i_mutex in fault,
1958	 * and bloating every shmem inode for this unlikely case would be sad.
1959	 */
1960	if (unlikely(inode->i_private)) {
1961		struct shmem_falloc *shmem_falloc;
1962
1963		spin_lock(&inode->i_lock);
1964		shmem_falloc = inode->i_private;
1965		if (shmem_falloc &&
1966		    shmem_falloc->waitq &&
1967		    vmf->pgoff >= shmem_falloc->start &&
1968		    vmf->pgoff < shmem_falloc->next) {
1969			wait_queue_head_t *shmem_falloc_waitq;
1970			DEFINE_WAIT_FUNC(shmem_fault_wait, synchronous_wake_function);
1971
1972			ret = VM_FAULT_NOPAGE;
1973			if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
1974			   !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
1975				/* It's polite to up mmap_sem if we can */
1976				up_read(&vma->vm_mm->mmap_sem);
1977				ret = VM_FAULT_RETRY;
1978			}
1979
1980			shmem_falloc_waitq = shmem_falloc->waitq;
1981			prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
1982					TASK_UNINTERRUPTIBLE);
1983			spin_unlock(&inode->i_lock);
1984			schedule();
1985
1986			/*
1987			 * shmem_falloc_waitq points into the shmem_fallocate()
1988			 * stack of the hole-punching task: shmem_falloc_waitq
1989			 * is usually invalid by the time we reach here, but
1990			 * finish_wait() does not dereference it in that case;
1991			 * though i_lock needed lest racing with wake_up_all().
1992			 */
1993			spin_lock(&inode->i_lock);
1994			finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
1995			spin_unlock(&inode->i_lock);
1996			return ret;
1997		}
1998		spin_unlock(&inode->i_lock);
1999	}
2000
2001	sgp = SGP_CACHE;
2002
2003	if ((vma->vm_flags & VM_NOHUGEPAGE) ||
2004	    test_bit(MMF_DISABLE_THP, &vma->vm_mm->flags))
2005		sgp = SGP_NOHUGE;
2006	else if (vma->vm_flags & VM_HUGEPAGE)
2007		sgp = SGP_HUGE;
2008
2009	error = shmem_getpage_gfp(inode, vmf->pgoff, &vmf->page, sgp,
2010				  gfp, vma, vmf, &ret);
2011	if (error)
2012		return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
2013	return ret;
2014}
2015
2016unsigned long shmem_get_unmapped_area(struct file *file,
2017				      unsigned long uaddr, unsigned long len,
2018				      unsigned long pgoff, unsigned long flags)
2019{
2020	unsigned long (*get_area)(struct file *,
2021		unsigned long, unsigned long, unsigned long, unsigned long);
2022	unsigned long addr;
2023	unsigned long offset;
2024	unsigned long inflated_len;
2025	unsigned long inflated_addr;
2026	unsigned long inflated_offset;
 
2027
2028	if (len > TASK_SIZE)
2029		return -ENOMEM;
2030
2031	get_area = current->mm->get_unmapped_area;
2032	addr = get_area(file, uaddr, len, pgoff, flags);
2033
2034	if (!IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE))
2035		return addr;
2036	if (IS_ERR_VALUE(addr))
2037		return addr;
2038	if (addr & ~PAGE_MASK)
2039		return addr;
2040	if (addr > TASK_SIZE - len)
2041		return addr;
2042
2043	if (shmem_huge == SHMEM_HUGE_DENY)
2044		return addr;
2045	if (len < HPAGE_PMD_SIZE)
2046		return addr;
2047	if (flags & MAP_FIXED)
2048		return addr;
2049	/*
2050	 * Our priority is to support MAP_SHARED mapped hugely;
2051	 * and support MAP_PRIVATE mapped hugely too, until it is COWed.
2052	 * But if caller specified an address hint, respect that as before.
 
2053	 */
2054	if (uaddr)
2055		return addr;
2056
 
2057	if (shmem_huge != SHMEM_HUGE_FORCE) {
2058		struct super_block *sb;
 
 
2059
2060		if (file) {
2061			VM_BUG_ON(file->f_op != &shmem_file_operations);
2062			sb = file_inode(file)->i_sb;
2063		} else {
2064			/*
2065			 * Called directly from mm/mmap.c, or drivers/char/mem.c
2066			 * for "/dev/zero", to create a shared anonymous object.
2067			 */
2068			if (IS_ERR(shm_mnt))
2069				return addr;
2070			sb = shm_mnt->mnt_sb;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2071		}
2072		if (SHMEM_SB(sb)->huge == SHMEM_HUGE_NEVER)
2073			return addr;
2074	}
2075
2076	offset = (pgoff << PAGE_SHIFT) & (HPAGE_PMD_SIZE-1);
2077	if (offset && offset + len < 2 * HPAGE_PMD_SIZE)
 
 
 
2078		return addr;
2079	if ((addr & (HPAGE_PMD_SIZE-1)) == offset)
2080		return addr;
2081
2082	inflated_len = len + HPAGE_PMD_SIZE - PAGE_SIZE;
2083	if (inflated_len > TASK_SIZE)
2084		return addr;
2085	if (inflated_len < len)
2086		return addr;
2087
2088	inflated_addr = get_area(NULL, 0, inflated_len, 0, flags);
 
2089	if (IS_ERR_VALUE(inflated_addr))
2090		return addr;
2091	if (inflated_addr & ~PAGE_MASK)
2092		return addr;
2093
2094	inflated_offset = inflated_addr & (HPAGE_PMD_SIZE-1);
2095	inflated_addr += offset - inflated_offset;
2096	if (inflated_offset > offset)
2097		inflated_addr += HPAGE_PMD_SIZE;
2098
2099	if (inflated_addr > TASK_SIZE - len)
2100		return addr;
2101	return inflated_addr;
2102}
2103
2104#ifdef CONFIG_NUMA
2105static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
2106{
2107	struct inode *inode = file_inode(vma->vm_file);
2108	return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
2109}
2110
2111static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
2112					  unsigned long addr)
2113{
2114	struct inode *inode = file_inode(vma->vm_file);
2115	pgoff_t index;
2116
 
 
 
 
 
 
 
2117	index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
2118	return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
2119}
2120#endif
2121
2122int shmem_lock(struct file *file, int lock, struct user_struct *user)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2123{
2124	struct inode *inode = file_inode(file);
2125	struct shmem_inode_info *info = SHMEM_I(inode);
2126	int retval = -ENOMEM;
2127
2128	spin_lock_irq(&info->lock);
 
 
 
 
2129	if (lock && !(info->flags & VM_LOCKED)) {
2130		if (!user_shm_lock(inode->i_size, user))
2131			goto out_nomem;
2132		info->flags |= VM_LOCKED;
2133		mapping_set_unevictable(file->f_mapping);
2134	}
2135	if (!lock && (info->flags & VM_LOCKED) && user) {
2136		user_shm_unlock(inode->i_size, user);
2137		info->flags &= ~VM_LOCKED;
2138		mapping_clear_unevictable(file->f_mapping);
2139	}
2140	retval = 0;
2141
2142out_nomem:
2143	spin_unlock_irq(&info->lock);
2144	return retval;
2145}
2146
2147static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
2148{
 
 
 
 
 
 
 
 
2149	file_accessed(file);
2150	vma->vm_ops = &shmem_vm_ops;
2151	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
2152			((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
2153			(vma->vm_end & HPAGE_PMD_MASK)) {
2154		khugepaged_enter(vma, vma->vm_flags);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2155	}
 
2156	return 0;
2157}
 
 
 
 
 
 
2158
2159static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
2160				     umode_t mode, dev_t dev, unsigned long flags)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2161{
2162	struct inode *inode;
2163	struct shmem_inode_info *info;
2164	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 
 
2165
2166	if (shmem_reserve_inode(sb))
2167		return NULL;
 
2168
2169	inode = new_inode(sb);
2170	if (inode) {
2171		inode->i_ino = get_next_ino();
2172		inode_init_owner(inode, dir, mode);
2173		inode->i_blocks = 0;
2174		inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(inode);
2175		inode->i_generation = get_seconds();
2176		info = SHMEM_I(inode);
2177		memset(info, 0, (char *)inode - (char *)info);
2178		spin_lock_init(&info->lock);
2179		info->seals = F_SEAL_SEAL;
2180		info->flags = flags & VM_NORESERVE;
2181		INIT_LIST_HEAD(&info->shrinklist);
2182		INIT_LIST_HEAD(&info->swaplist);
2183		simple_xattrs_init(&info->xattrs);
2184		cache_no_acl(inode);
2185
2186		switch (mode & S_IFMT) {
2187		default:
2188			inode->i_op = &shmem_special_inode_operations;
2189			init_special_inode(inode, mode, dev);
2190			break;
2191		case S_IFREG:
2192			inode->i_mapping->a_ops = &shmem_aops;
2193			inode->i_op = &shmem_inode_operations;
2194			inode->i_fop = &shmem_file_operations;
2195			mpol_shared_policy_init(&info->policy,
2196						 shmem_get_sbmpol(sbinfo));
2197			break;
2198		case S_IFDIR:
2199			inc_nlink(inode);
2200			/* Some things misbehave if size == 0 on a directory */
2201			inode->i_size = 2 * BOGO_DIRENT_SIZE;
2202			inode->i_op = &shmem_dir_inode_operations;
2203			inode->i_fop = &simple_dir_operations;
2204			break;
2205		case S_IFLNK:
2206			/*
2207			 * Must not load anything in the rbtree,
2208			 * mpol_free_shared_policy will not be called.
2209			 */
2210			mpol_shared_policy_init(&info->policy, NULL);
2211			break;
2212		}
2213	} else
2214		shmem_free_inode(sb);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2215	return inode;
2216}
2217
2218bool shmem_mapping(struct address_space *mapping)
 
 
 
2219{
2220	return mapping->a_ops == &shmem_aops;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2221}
 
2222
2223static int shmem_mfill_atomic_pte(struct mm_struct *dst_mm,
2224				  pmd_t *dst_pmd,
2225				  struct vm_area_struct *dst_vma,
2226				  unsigned long dst_addr,
2227				  unsigned long src_addr,
2228				  bool zeropage,
2229				  struct page **pagep)
2230{
2231	struct inode *inode = file_inode(dst_vma->vm_file);
2232	struct shmem_inode_info *info = SHMEM_I(inode);
2233	struct address_space *mapping = inode->i_mapping;
2234	gfp_t gfp = mapping_gfp_mask(mapping);
2235	pgoff_t pgoff = linear_page_index(dst_vma, dst_addr);
2236	struct mem_cgroup *memcg;
2237	spinlock_t *ptl;
2238	void *page_kaddr;
2239	struct page *page;
2240	pte_t _dst_pte, *dst_pte;
2241	int ret;
 
2242
2243	ret = -ENOMEM;
2244	if (!shmem_inode_acct_block(inode, 1))
2245		goto out;
 
 
 
 
 
 
 
 
 
2246
2247	if (!*pagep) {
2248		page = shmem_alloc_page(gfp, info, pgoff);
2249		if (!page)
 
2250			goto out_unacct_blocks;
2251
2252		if (!zeropage) {	/* mcopy_atomic */
2253			page_kaddr = kmap_atomic(page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2254			ret = copy_from_user(page_kaddr,
2255					     (const void __user *)src_addr,
2256					     PAGE_SIZE);
2257			kunmap_atomic(page_kaddr);
 
2258
2259			/* fallback to copy_from_user outside mmap_sem */
2260			if (unlikely(ret)) {
2261				*pagep = page;
2262				shmem_inode_unacct_blocks(inode, 1);
2263				/* don't free the page */
2264				return -EFAULT;
2265			}
2266		} else {		/* mfill_zeropage_atomic */
2267			clear_highpage(page);
 
 
2268		}
2269	} else {
2270		page = *pagep;
2271		*pagep = NULL;
 
2272	}
2273
2274	VM_BUG_ON(PageLocked(page) || PageSwapBacked(page));
2275	__SetPageLocked(page);
2276	__SetPageSwapBacked(page);
2277	__SetPageUptodate(page);
 
 
 
 
 
 
2278
2279	ret = mem_cgroup_try_charge(page, dst_mm, gfp, &memcg, false);
2280	if (ret)
2281		goto out_release;
2282
2283	ret = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
2284	if (!ret) {
2285		ret = shmem_add_to_page_cache(page, mapping, pgoff, NULL);
2286		radix_tree_preload_end();
2287	}
2288	if (ret)
2289		goto out_release_uncharge;
2290
2291	mem_cgroup_commit_charge(page, memcg, false, false);
2292
2293	_dst_pte = mk_pte(page, dst_vma->vm_page_prot);
2294	if (dst_vma->vm_flags & VM_WRITE)
2295		_dst_pte = pte_mkwrite(pte_mkdirty(_dst_pte));
2296
2297	ret = -EEXIST;
2298	dst_pte = pte_offset_map_lock(dst_mm, dst_pmd, dst_addr, &ptl);
2299	if (!pte_none(*dst_pte))
2300		goto out_release_uncharge_unlock;
2301
2302	lru_cache_add_anon(page);
2303
2304	spin_lock(&info->lock);
2305	info->alloced++;
2306	inode->i_blocks += BLOCKS_PER_PAGE;
2307	shmem_recalc_inode(inode);
2308	spin_unlock(&info->lock);
2309
2310	inc_mm_counter(dst_mm, mm_counter_file(page));
2311	page_add_file_rmap(page, false);
2312	set_pte_at(dst_mm, dst_addr, dst_pte, _dst_pte);
2313
2314	/* No need to invalidate - it was non-present before */
2315	update_mmu_cache(dst_vma, dst_addr, dst_pte);
2316	unlock_page(page);
2317	pte_unmap_unlock(dst_pte, ptl);
2318	ret = 0;
2319out:
2320	return ret;
2321out_release_uncharge_unlock:
2322	pte_unmap_unlock(dst_pte, ptl);
2323out_release_uncharge:
2324	mem_cgroup_cancel_charge(page, memcg, false);
2325out_release:
2326	unlock_page(page);
2327	put_page(page);
2328out_unacct_blocks:
2329	shmem_inode_unacct_blocks(inode, 1);
2330	goto out;
2331}
2332
2333int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm,
2334			   pmd_t *dst_pmd,
2335			   struct vm_area_struct *dst_vma,
2336			   unsigned long dst_addr,
2337			   unsigned long src_addr,
2338			   struct page **pagep)
2339{
2340	return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2341				      dst_addr, src_addr, false, pagep);
2342}
2343
2344int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
2345			     pmd_t *dst_pmd,
2346			     struct vm_area_struct *dst_vma,
2347			     unsigned long dst_addr)
2348{
2349	struct page *page = NULL;
2350
2351	return shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma,
2352				      dst_addr, 0, true, &page);
2353}
 
2354
2355#ifdef CONFIG_TMPFS
2356static const struct inode_operations shmem_symlink_inode_operations;
2357static const struct inode_operations shmem_short_symlink_operations;
2358
2359#ifdef CONFIG_TMPFS_XATTR
2360static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
2361#else
2362#define shmem_initxattrs NULL
2363#endif
2364
2365static int
2366shmem_write_begin(struct file *file, struct address_space *mapping,
2367			loff_t pos, unsigned len, unsigned flags,
2368			struct page **pagep, void **fsdata)
2369{
2370	struct inode *inode = mapping->host;
2371	struct shmem_inode_info *info = SHMEM_I(inode);
2372	pgoff_t index = pos >> PAGE_SHIFT;
 
 
2373
2374	/* i_mutex is held by caller */
2375	if (unlikely(info->seals & (F_SEAL_WRITE | F_SEAL_GROW))) {
2376		if (info->seals & F_SEAL_WRITE)
 
2377			return -EPERM;
2378		if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
2379			return -EPERM;
2380	}
2381
2382	return shmem_getpage(inode, index, pagep, SGP_WRITE);
 
 
 
 
 
 
 
 
 
 
 
 
2383}
2384
2385static int
2386shmem_write_end(struct file *file, struct address_space *mapping,
2387			loff_t pos, unsigned len, unsigned copied,
2388			struct page *page, void *fsdata)
2389{
2390	struct inode *inode = mapping->host;
2391
2392	if (pos + copied > inode->i_size)
2393		i_size_write(inode, pos + copied);
2394
2395	if (!PageUptodate(page)) {
2396		struct page *head = compound_head(page);
2397		if (PageTransCompound(page)) {
2398			int i;
2399
2400			for (i = 0; i < HPAGE_PMD_NR; i++) {
2401				if (head + i == page)
2402					continue;
2403				clear_highpage(head + i);
2404				flush_dcache_page(head + i);
2405			}
2406		}
2407		if (copied < PAGE_SIZE) {
2408			unsigned from = pos & (PAGE_SIZE - 1);
2409			zero_user_segments(page, 0, from,
2410					from + copied, PAGE_SIZE);
2411		}
2412		SetPageUptodate(head);
2413	}
2414	set_page_dirty(page);
2415	unlock_page(page);
2416	put_page(page);
2417
2418	return copied;
2419}
2420
2421static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
2422{
2423	struct file *file = iocb->ki_filp;
2424	struct inode *inode = file_inode(file);
2425	struct address_space *mapping = inode->i_mapping;
2426	pgoff_t index;
2427	unsigned long offset;
2428	enum sgp_type sgp = SGP_READ;
2429	int error = 0;
2430	ssize_t retval = 0;
2431	loff_t *ppos = &iocb->ki_pos;
2432
2433	/*
2434	 * Might this read be for a stacking filesystem?  Then when reading
2435	 * holes of a sparse file, we actually need to allocate those pages,
2436	 * and even mark them dirty, so it cannot exceed the max_blocks limit.
2437	 */
2438	if (!iter_is_iovec(to))
2439		sgp = SGP_CACHE;
2440
2441	index = *ppos >> PAGE_SHIFT;
2442	offset = *ppos & ~PAGE_MASK;
2443
2444	for (;;) {
 
2445		struct page *page = NULL;
2446		pgoff_t end_index;
2447		unsigned long nr, ret;
2448		loff_t i_size = i_size_read(inode);
 
 
2449
2450		end_index = i_size >> PAGE_SHIFT;
2451		if (index > end_index)
2452			break;
2453		if (index == end_index) {
2454			nr = i_size & ~PAGE_MASK;
2455			if (nr <= offset)
2456				break;
2457		}
2458
2459		error = shmem_getpage(inode, index, &page, sgp);
 
2460		if (error) {
2461			if (error == -EINVAL)
2462				error = 0;
2463			break;
2464		}
2465		if (page) {
2466			if (sgp == SGP_CACHE)
2467				set_page_dirty(page);
2468			unlock_page(page);
 
 
 
 
 
 
 
 
 
2469		}
2470
2471		/*
2472		 * We must evaluate after, since reads (unlike writes)
2473		 * are called without i_mutex protection against truncate
2474		 */
2475		nr = PAGE_SIZE;
2476		i_size = i_size_read(inode);
2477		end_index = i_size >> PAGE_SHIFT;
2478		if (index == end_index) {
2479			nr = i_size & ~PAGE_MASK;
2480			if (nr <= offset) {
2481				if (page)
2482					put_page(page);
2483				break;
2484			}
2485		}
2486		nr -= offset;
 
 
 
 
 
 
2487
2488		if (page) {
2489			/*
2490			 * If users can be writing to this page using arbitrary
2491			 * virtual addresses, take care about potential aliasing
2492			 * before reading the page on the kernel side.
2493			 */
2494			if (mapping_writably_mapped(mapping))
2495				flush_dcache_page(page);
 
 
 
 
 
2496			/*
2497			 * Mark the page accessed if we read the beginning.
2498			 */
2499			if (!offset)
2500				mark_page_accessed(page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2501		} else {
2502			page = ZERO_PAGE(0);
2503			get_page(page);
 
 
 
 
2504		}
2505
2506		/*
2507		 * Ok, we have the page, and it's up-to-date, so
2508		 * now we can copy it to user space...
2509		 */
2510		ret = copy_page_to_iter(page, offset, nr, to);
2511		retval += ret;
2512		offset += ret;
2513		index += offset >> PAGE_SHIFT;
2514		offset &= ~PAGE_MASK;
2515
2516		put_page(page);
2517		if (!iov_iter_count(to))
2518			break;
2519		if (ret < nr) {
2520			error = -EFAULT;
2521			break;
2522		}
2523		cond_resched();
2524	}
2525
2526	*ppos = ((loff_t) index << PAGE_SHIFT) + offset;
2527	file_accessed(file);
2528	return retval ? retval : error;
2529}
2530
2531/*
2532 * llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
2533 */
2534static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
2535				    pgoff_t index, pgoff_t end, int whence)
2536{
2537	struct page *page;
2538	struct pagevec pvec;
2539	pgoff_t indices[PAGEVEC_SIZE];
2540	bool done = false;
2541	int i;
2542
2543	pagevec_init(&pvec);
2544	pvec.nr = 1;		/* start small: we may be there already */
2545	while (!done) {
2546		pvec.nr = find_get_entries(mapping, index,
2547					pvec.nr, pvec.pages, indices);
2548		if (!pvec.nr) {
2549			if (whence == SEEK_DATA)
2550				index = end;
2551			break;
2552		}
2553		for (i = 0; i < pvec.nr; i++, index++) {
2554			if (index < indices[i]) {
2555				if (whence == SEEK_HOLE) {
2556					done = true;
2557					break;
2558				}
2559				index = indices[i];
2560			}
2561			page = pvec.pages[i];
2562			if (page && !radix_tree_exceptional_entry(page)) {
2563				if (!PageUptodate(page))
2564					page = NULL;
2565			}
2566			if (index >= end ||
2567			    (page && whence == SEEK_DATA) ||
2568			    (!page && whence == SEEK_HOLE)) {
2569				done = true;
2570				break;
2571			}
2572		}
2573		pagevec_remove_exceptionals(&pvec);
2574		pagevec_release(&pvec);
2575		pvec.nr = PAGEVEC_SIZE;
2576		cond_resched();
2577	}
2578	return index;
2579}
2580
2581static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
2582{
2583	struct address_space *mapping = file->f_mapping;
2584	struct inode *inode = mapping->host;
2585	pgoff_t start, end;
2586	loff_t new_offset;
2587
2588	if (whence != SEEK_DATA && whence != SEEK_HOLE)
2589		return generic_file_llseek_size(file, offset, whence,
2590					MAX_LFS_FILESIZE, i_size_read(inode));
2591	inode_lock(inode);
2592	/* We're holding i_mutex so we can access i_size directly */
2593
2594	if (offset < 0)
2595		offset = -EINVAL;
2596	else if (offset >= inode->i_size)
2597		offset = -ENXIO;
2598	else {
2599		start = offset >> PAGE_SHIFT;
2600		end = (inode->i_size + PAGE_SIZE - 1) >> PAGE_SHIFT;
2601		new_offset = shmem_seek_hole_data(mapping, start, end, whence);
2602		new_offset <<= PAGE_SHIFT;
2603		if (new_offset > offset) {
2604			if (new_offset < inode->i_size)
2605				offset = new_offset;
2606			else if (whence == SEEK_DATA)
2607				offset = -ENXIO;
2608			else
2609				offset = inode->i_size;
2610		}
2611	}
2612
2613	if (offset >= 0)
2614		offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
2615	inode_unlock(inode);
2616	return offset;
2617}
2618
2619/*
2620 * We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
2621 * so reuse a tag which we firmly believe is never set or cleared on shmem.
2622 */
2623#define SHMEM_TAG_PINNED        PAGECACHE_TAG_TOWRITE
2624#define LAST_SCAN               4       /* about 150ms max */
2625
2626static void shmem_tag_pins(struct address_space *mapping)
2627{
2628	struct radix_tree_iter iter;
2629	void **slot;
2630	pgoff_t start;
2631	struct page *page;
2632
2633	lru_add_drain();
2634	start = 0;
2635	rcu_read_lock();
2636
2637	radix_tree_for_each_slot(slot, &mapping->i_pages, &iter, start) {
2638		page = radix_tree_deref_slot(slot);
2639		if (!page || radix_tree_exception(page)) {
2640			if (radix_tree_deref_retry(page)) {
2641				slot = radix_tree_iter_retry(&iter);
2642				continue;
2643			}
2644		} else if (page_count(page) - page_mapcount(page) > 1) {
2645			xa_lock_irq(&mapping->i_pages);
2646			radix_tree_tag_set(&mapping->i_pages, iter.index,
2647					   SHMEM_TAG_PINNED);
2648			xa_unlock_irq(&mapping->i_pages);
2649		}
2650
2651		if (need_resched()) {
2652			slot = radix_tree_iter_resume(slot, &iter);
2653			cond_resched_rcu();
2654		}
2655	}
2656	rcu_read_unlock();
2657}
2658
2659/*
2660 * Setting SEAL_WRITE requires us to verify there's no pending writer. However,
2661 * via get_user_pages(), drivers might have some pending I/O without any active
2662 * user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages
2663 * and see whether it has an elevated ref-count. If so, we tag them and wait for
2664 * them to be dropped.
2665 * The caller must guarantee that no new user will acquire writable references
2666 * to those pages to avoid races.
2667 */
2668static int shmem_wait_for_pins(struct address_space *mapping)
2669{
2670	struct radix_tree_iter iter;
2671	void **slot;
2672	pgoff_t start;
2673	struct page *page;
2674	int error, scan;
2675
2676	shmem_tag_pins(mapping);
2677
2678	error = 0;
2679	for (scan = 0; scan <= LAST_SCAN; scan++) {
2680		if (!radix_tree_tagged(&mapping->i_pages, SHMEM_TAG_PINNED))
2681			break;
 
2682
2683		if (!scan)
2684			lru_add_drain_all();
2685		else if (schedule_timeout_killable((HZ << scan) / 200))
2686			scan = LAST_SCAN;
2687
2688		start = 0;
2689		rcu_read_lock();
2690		radix_tree_for_each_tagged(slot, &mapping->i_pages, &iter,
2691					   start, SHMEM_TAG_PINNED) {
2692
2693			page = radix_tree_deref_slot(slot);
2694			if (radix_tree_exception(page)) {
2695				if (radix_tree_deref_retry(page)) {
2696					slot = radix_tree_iter_retry(&iter);
2697					continue;
2698				}
2699
2700				page = NULL;
2701			}
 
 
2702
2703			if (page &&
2704			    page_count(page) - page_mapcount(page) != 1) {
2705				if (scan < LAST_SCAN)
2706					goto continue_resched;
2707
2708				/*
2709				 * On the last scan, we clean up all those tags
2710				 * we inserted; but make a note that we still
2711				 * found pages pinned.
2712				 */
2713				error = -EBUSY;
2714			}
2715
2716			xa_lock_irq(&mapping->i_pages);
2717			radix_tree_tag_clear(&mapping->i_pages,
2718					     iter.index, SHMEM_TAG_PINNED);
2719			xa_unlock_irq(&mapping->i_pages);
2720continue_resched:
2721			if (need_resched()) {
2722				slot = radix_tree_iter_resume(slot, &iter);
2723				cond_resched_rcu();
2724			}
2725		}
2726		rcu_read_unlock();
2727	}
2728
2729	return error;
2730}
2731
2732static unsigned int *memfd_file_seals_ptr(struct file *file)
 
 
2733{
2734	if (file->f_op == &shmem_file_operations)
2735		return &SHMEM_I(file_inode(file))->seals;
2736
2737#ifdef CONFIG_HUGETLBFS
2738	if (file->f_op == &hugetlbfs_file_operations)
2739		return &HUGETLBFS_I(file_inode(file))->seals;
2740#endif
2741
2742	return NULL;
2743}
2744
2745#define F_ALL_SEALS (F_SEAL_SEAL | \
2746		     F_SEAL_SHRINK | \
2747		     F_SEAL_GROW | \
2748		     F_SEAL_WRITE)
2749
2750static int memfd_add_seals(struct file *file, unsigned int seals)
2751{
2752	struct inode *inode = file_inode(file);
2753	unsigned int *file_seals;
2754	int error;
2755
2756	/*
2757	 * SEALING
2758	 * Sealing allows multiple parties to share a shmem-file but restrict
2759	 * access to a specific subset of file operations. Seals can only be
2760	 * added, but never removed. This way, mutually untrusted parties can
2761	 * share common memory regions with a well-defined policy. A malicious
2762	 * peer can thus never perform unwanted operations on a shared object.
2763	 *
2764	 * Seals are only supported on special shmem-files and always affect
2765	 * the whole underlying inode. Once a seal is set, it may prevent some
2766	 * kinds of access to the file. Currently, the following seals are
2767	 * defined:
2768	 *   SEAL_SEAL: Prevent further seals from being set on this file
2769	 *   SEAL_SHRINK: Prevent the file from shrinking
2770	 *   SEAL_GROW: Prevent the file from growing
2771	 *   SEAL_WRITE: Prevent write access to the file
2772	 *
2773	 * As we don't require any trust relationship between two parties, we
2774	 * must prevent seals from being removed. Therefore, sealing a file
2775	 * only adds a given set of seals to the file, it never touches
2776	 * existing seals. Furthermore, the "setting seals"-operation can be
2777	 * sealed itself, which basically prevents any further seal from being
2778	 * added.
2779	 *
2780	 * Semantics of sealing are only defined on volatile files. Only
2781	 * anonymous shmem files support sealing. More importantly, seals are
2782	 * never written to disk. Therefore, there's no plan to support it on
2783	 * other file types.
2784	 */
2785
2786	if (!(file->f_mode & FMODE_WRITE))
2787		return -EPERM;
2788	if (seals & ~(unsigned int)F_ALL_SEALS)
2789		return -EINVAL;
 
 
 
 
 
2790
2791	inode_lock(inode);
 
 
 
 
2792
2793	file_seals = memfd_file_seals_ptr(file);
2794	if (!file_seals) {
2795		error = -EINVAL;
2796		goto unlock;
2797	}
2798
2799	if (*file_seals & F_SEAL_SEAL) {
2800		error = -EPERM;
2801		goto unlock;
2802	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2803
2804	if ((seals & F_SEAL_WRITE) && !(*file_seals & F_SEAL_WRITE)) {
2805		error = mapping_deny_writable(file->f_mapping);
2806		if (error)
2807			goto unlock;
2808
2809		error = shmem_wait_for_pins(file->f_mapping);
2810		if (error) {
2811			mapping_allow_writable(file->f_mapping);
2812			goto unlock;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2813		}
2814	}
2815
2816	*file_seals |= seals;
2817	error = 0;
 
 
 
 
 
 
2818
2819unlock:
2820	inode_unlock(inode);
2821	return error;
2822}
2823
2824static int memfd_get_seals(struct file *file)
2825{
2826	unsigned int *seals = memfd_file_seals_ptr(file);
2827
2828	return seals ? *seals : -EINVAL;
 
2829}
2830
2831long memfd_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
2832{
2833	long error;
2834
2835	switch (cmd) {
2836	case F_ADD_SEALS:
2837		/* disallow upper 32bit */
2838		if (arg > UINT_MAX)
2839			return -EINVAL;
2840
2841		error = memfd_add_seals(file, arg);
2842		break;
2843	case F_GET_SEALS:
2844		error = memfd_get_seals(file);
2845		break;
2846	default:
2847		error = -EINVAL;
2848		break;
2849	}
2850
2851	return error;
 
 
 
 
 
 
2852}
2853
2854static long shmem_fallocate(struct file *file, int mode, loff_t offset,
2855							 loff_t len)
2856{
2857	struct inode *inode = file_inode(file);
2858	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
2859	struct shmem_inode_info *info = SHMEM_I(inode);
2860	struct shmem_falloc shmem_falloc;
2861	pgoff_t start, index, end;
2862	int error;
2863
2864	if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
2865		return -EOPNOTSUPP;
2866
2867	inode_lock(inode);
2868
2869	if (mode & FALLOC_FL_PUNCH_HOLE) {
2870		struct address_space *mapping = file->f_mapping;
2871		loff_t unmap_start = round_up(offset, PAGE_SIZE);
2872		loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
2873		DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
2874
2875		/* protected by i_mutex */
2876		if (info->seals & F_SEAL_WRITE) {
2877			error = -EPERM;
2878			goto out;
2879		}
2880
2881		shmem_falloc.waitq = &shmem_falloc_waitq;
2882		shmem_falloc.start = unmap_start >> PAGE_SHIFT;
2883		shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
2884		spin_lock(&inode->i_lock);
2885		inode->i_private = &shmem_falloc;
2886		spin_unlock(&inode->i_lock);
2887
2888		if ((u64)unmap_end > (u64)unmap_start)
2889			unmap_mapping_range(mapping, unmap_start,
2890					    1 + unmap_end - unmap_start, 0);
2891		shmem_truncate_range(inode, offset, offset + len - 1);
2892		/* No need to unmap again: hole-punching leaves COWed pages */
2893
2894		spin_lock(&inode->i_lock);
2895		inode->i_private = NULL;
2896		wake_up_all(&shmem_falloc_waitq);
2897		WARN_ON_ONCE(!list_empty(&shmem_falloc_waitq.head));
2898		spin_unlock(&inode->i_lock);
2899		error = 0;
2900		goto out;
2901	}
2902
2903	/* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
2904	error = inode_newsize_ok(inode, offset + len);
2905	if (error)
2906		goto out;
2907
2908	if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
2909		error = -EPERM;
2910		goto out;
2911	}
2912
2913	start = offset >> PAGE_SHIFT;
2914	end = (offset + len + PAGE_SIZE - 1) >> PAGE_SHIFT;
2915	/* Try to avoid a swapstorm if len is impossible to satisfy */
2916	if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
2917		error = -ENOSPC;
2918		goto out;
2919	}
2920
2921	shmem_falloc.waitq = NULL;
2922	shmem_falloc.start = start;
2923	shmem_falloc.next  = start;
2924	shmem_falloc.nr_falloced = 0;
2925	shmem_falloc.nr_unswapped = 0;
2926	spin_lock(&inode->i_lock);
2927	inode->i_private = &shmem_falloc;
2928	spin_unlock(&inode->i_lock);
2929
2930	for (index = start; index < end; index++) {
2931		struct page *page;
 
 
 
 
 
 
 
 
 
2932
2933		/*
2934		 * Good, the fallocate(2) manpage permits EINTR: we may have
2935		 * been interrupted because we are using up too much memory.
 
 
 
2936		 */
2937		if (signal_pending(current))
2938			error = -EINTR;
2939		else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
2940			error = -ENOMEM;
2941		else
2942			error = shmem_getpage(inode, index, &page, SGP_FALLOC);
 
2943		if (error) {
2944			/* Remove the !PageUptodate pages we added */
 
2945			if (index > start) {
2946				shmem_undo_range(inode,
2947				    (loff_t)start << PAGE_SHIFT,
2948				    ((loff_t)index << PAGE_SHIFT) - 1, true);
2949			}
2950			goto undone;
2951		}
2952
2953		/*
 
 
 
 
 
 
 
 
 
 
2954		 * Inform shmem_writepage() how far we have reached.
2955		 * No need for lock or barrier: we have the page lock.
2956		 */
2957		shmem_falloc.next++;
2958		if (!PageUptodate(page))
2959			shmem_falloc.nr_falloced++;
2960
2961		/*
2962		 * If !PageUptodate, leave it that way so that freeable pages
2963		 * can be recognized if we need to rollback on error later.
2964		 * But set_page_dirty so that memory pressure will swap rather
2965		 * than free the pages we are allocating (and SGP_CACHE pages
2966		 * might still be clean: we now need to mark those dirty too).
2967		 */
2968		set_page_dirty(page);
2969		unlock_page(page);
2970		put_page(page);
2971		cond_resched();
2972	}
2973
2974	if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
2975		i_size_write(inode, offset + len);
2976	inode->i_ctime = current_time(inode);
2977undone:
2978	spin_lock(&inode->i_lock);
2979	inode->i_private = NULL;
2980	spin_unlock(&inode->i_lock);
2981out:
 
 
2982	inode_unlock(inode);
2983	return error;
2984}
2985
2986static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
2987{
2988	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
2989
2990	buf->f_type = TMPFS_MAGIC;
2991	buf->f_bsize = PAGE_SIZE;
2992	buf->f_namelen = NAME_MAX;
2993	if (sbinfo->max_blocks) {
2994		buf->f_blocks = sbinfo->max_blocks;
2995		buf->f_bavail =
2996		buf->f_bfree  = sbinfo->max_blocks -
2997				percpu_counter_sum(&sbinfo->used_blocks);
2998	}
2999	if (sbinfo->max_inodes) {
3000		buf->f_files = sbinfo->max_inodes;
3001		buf->f_ffree = sbinfo->free_inodes;
3002	}
3003	/* else leave those fields 0 like simple_statfs */
 
 
 
3004	return 0;
3005}
3006
3007/*
3008 * File creation. Allocate an inode, and we're done..
3009 */
3010static int
3011shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
 
3012{
3013	struct inode *inode;
3014	int error = -ENOSPC;
3015
3016	inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
3017	if (inode) {
3018		error = simple_acl_create(dir, inode);
3019		if (error)
3020			goto out_iput;
3021		error = security_inode_init_security(inode, dir,
3022						     &dentry->d_name,
3023						     shmem_initxattrs, NULL);
3024		if (error && error != -EOPNOTSUPP)
3025			goto out_iput;
3026
3027		error = 0;
3028		dir->i_size += BOGO_DIRENT_SIZE;
3029		dir->i_ctime = dir->i_mtime = current_time(dir);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3030		d_instantiate(dentry, inode);
3031		dget(dentry); /* Extra count - pin the dentry in core */
3032	}
3033	return error;
 
3034out_iput:
3035	iput(inode);
3036	return error;
3037}
3038
3039static int
3040shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
 
3041{
3042	struct inode *inode;
3043	int error = -ENOSPC;
3044
3045	inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
3046	if (inode) {
3047		error = security_inode_init_security(inode, dir,
3048						     NULL,
3049						     shmem_initxattrs, NULL);
3050		if (error && error != -EOPNOTSUPP)
3051			goto out_iput;
3052		error = simple_acl_create(dir, inode);
3053		if (error)
3054			goto out_iput;
3055		d_tmpfile(dentry, inode);
3056	}
3057	return error;
 
 
 
 
 
 
 
 
 
 
3058out_iput:
3059	iput(inode);
3060	return error;
3061}
3062
3063static int shmem_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 
3064{
3065	int error;
3066
3067	if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
 
3068		return error;
3069	inc_nlink(dir);
3070	return 0;
3071}
3072
3073static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t mode,
3074		bool excl)
3075{
3076	return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
3077}
3078
3079/*
3080 * Link a file..
3081 */
3082static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
 
3083{
3084	struct inode *inode = d_inode(old_dentry);
3085	int ret;
3086
3087	/*
3088	 * No ordinary (disk based) filesystem counts links as inodes;
3089	 * but each new link needs a new dentry, pinning lowmem, and
3090	 * tmpfs dentries cannot be pruned until they are unlinked.
 
 
3091	 */
3092	ret = shmem_reserve_inode(inode->i_sb);
3093	if (ret)
 
 
 
 
 
 
 
 
3094		goto out;
 
3095
3096	dir->i_size += BOGO_DIRENT_SIZE;
3097	inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
 
 
3098	inc_nlink(inode);
3099	ihold(inode);	/* New dentry reference */
3100	dget(dentry);		/* Extra pinning count for the created dentry */
3101	d_instantiate(dentry, inode);
 
 
 
3102out:
3103	return ret;
3104}
3105
3106static int shmem_unlink(struct inode *dir, struct dentry *dentry)
3107{
3108	struct inode *inode = d_inode(dentry);
3109
3110	if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
3111		shmem_free_inode(inode->i_sb);
 
 
3112
3113	dir->i_size -= BOGO_DIRENT_SIZE;
3114	inode->i_ctime = dir->i_ctime = dir->i_mtime = current_time(inode);
 
 
3115	drop_nlink(inode);
3116	dput(dentry);	/* Undo the count from "create" - this does all the work */
 
 
 
 
 
 
 
 
3117	return 0;
3118}
3119
3120static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
3121{
3122	if (!simple_empty(dentry))
3123		return -ENOTEMPTY;
3124
3125	drop_nlink(d_inode(dentry));
3126	drop_nlink(dir);
3127	return shmem_unlink(dir, dentry);
3128}
3129
3130static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
3131{
3132	bool old_is_dir = d_is_dir(old_dentry);
3133	bool new_is_dir = d_is_dir(new_dentry);
3134
3135	if (old_dir != new_dir && old_is_dir != new_is_dir) {
3136		if (old_is_dir) {
3137			drop_nlink(old_dir);
3138			inc_nlink(new_dir);
3139		} else {
3140			drop_nlink(new_dir);
3141			inc_nlink(old_dir);
3142		}
3143	}
3144	old_dir->i_ctime = old_dir->i_mtime =
3145	new_dir->i_ctime = new_dir->i_mtime =
3146	d_inode(old_dentry)->i_ctime =
3147	d_inode(new_dentry)->i_ctime = current_time(old_dir);
3148
3149	return 0;
3150}
3151
3152static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
3153{
3154	struct dentry *whiteout;
3155	int error;
3156
3157	whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
3158	if (!whiteout)
3159		return -ENOMEM;
3160
3161	error = shmem_mknod(old_dir, whiteout,
3162			    S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
3163	dput(whiteout);
3164	if (error)
3165		return error;
3166
3167	/*
3168	 * Cheat and hash the whiteout while the old dentry is still in
3169	 * place, instead of playing games with FS_RENAME_DOES_D_MOVE.
3170	 *
3171	 * d_lookup() will consistently find one of them at this point,
3172	 * not sure which one, but that isn't even important.
3173	 */
3174	d_rehash(whiteout);
3175	return 0;
3176}
3177
3178/*
3179 * The VFS layer already does all the dentry stuff for rename,
3180 * we just have to decrement the usage count for the target if
3181 * it exists so that the VFS layer correctly free's it when it
3182 * gets overwritten.
3183 */
3184static int shmem_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
 
 
 
3185{
3186	struct inode *inode = d_inode(old_dentry);
3187	int they_are_dirs = S_ISDIR(inode->i_mode);
 
3188
3189	if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
3190		return -EINVAL;
3191
3192	if (flags & RENAME_EXCHANGE)
3193		return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
 
3194
3195	if (!simple_empty(new_dentry))
3196		return -ENOTEMPTY;
3197
3198	if (flags & RENAME_WHITEOUT) {
3199		int error;
3200
3201		error = shmem_whiteout(old_dir, old_dentry);
3202		if (error)
3203			return error;
3204	}
3205
 
 
 
 
3206	if (d_really_is_positive(new_dentry)) {
3207		(void) shmem_unlink(new_dir, new_dentry);
3208		if (they_are_dirs) {
3209			drop_nlink(d_inode(new_dentry));
3210			drop_nlink(old_dir);
3211		}
3212	} else if (they_are_dirs) {
3213		drop_nlink(old_dir);
3214		inc_nlink(new_dir);
3215	}
3216
3217	old_dir->i_size -= BOGO_DIRENT_SIZE;
3218	new_dir->i_size += BOGO_DIRENT_SIZE;
3219	old_dir->i_ctime = old_dir->i_mtime =
3220	new_dir->i_ctime = new_dir->i_mtime =
3221	inode->i_ctime = current_time(old_dir);
3222	return 0;
3223}
3224
3225static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
 
3226{
3227	int error;
3228	int len;
3229	struct inode *inode;
3230	struct page *page;
3231
3232	len = strlen(symname) + 1;
3233	if (len > PAGE_SIZE)
3234		return -ENAMETOOLONG;
3235
3236	inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
3237	if (!inode)
3238		return -ENOSPC;
 
3239
3240	error = security_inode_init_security(inode, dir, &dentry->d_name,
3241					     shmem_initxattrs, NULL);
3242	if (error) {
3243		if (error != -EOPNOTSUPP) {
3244			iput(inode);
3245			return error;
3246		}
3247		error = 0;
3248	}
3249
3250	inode->i_size = len-1;
3251	if (len <= SHORT_SYMLINK_LEN) {
3252		inode->i_link = kmemdup(symname, len, GFP_KERNEL);
3253		if (!inode->i_link) {
3254			iput(inode);
3255			return -ENOMEM;
3256		}
3257		inode->i_op = &shmem_short_symlink_operations;
3258	} else {
3259		inode_nohighmem(inode);
3260		error = shmem_getpage(inode, 0, &page, SGP_WRITE);
3261		if (error) {
3262			iput(inode);
3263			return error;
3264		}
3265		inode->i_mapping->a_ops = &shmem_aops;
 
 
 
3266		inode->i_op = &shmem_symlink_inode_operations;
3267		memcpy(page_address(page), symname, len);
3268		SetPageUptodate(page);
3269		set_page_dirty(page);
3270		unlock_page(page);
3271		put_page(page);
3272	}
3273	dir->i_size += BOGO_DIRENT_SIZE;
3274	dir->i_ctime = dir->i_mtime = current_time(dir);
3275	d_instantiate(dentry, inode);
 
 
 
 
3276	dget(dentry);
3277	return 0;
 
 
 
 
 
 
3278}
3279
3280static void shmem_put_link(void *arg)
3281{
3282	mark_page_accessed(arg);
3283	put_page(arg);
3284}
3285
3286static const char *shmem_get_link(struct dentry *dentry,
3287				  struct inode *inode,
3288				  struct delayed_call *done)
3289{
3290	struct page *page = NULL;
3291	int error;
 
3292	if (!dentry) {
3293		page = find_get_page(inode->i_mapping, 0);
3294		if (!page)
3295			return ERR_PTR(-ECHILD);
3296		if (!PageUptodate(page)) {
3297			put_page(page);
 
3298			return ERR_PTR(-ECHILD);
3299		}
3300	} else {
3301		error = shmem_getpage(inode, 0, &page, SGP_READ);
3302		if (error)
3303			return ERR_PTR(error);
3304		unlock_page(page);
 
 
 
 
 
 
 
3305	}
3306	set_delayed_call(done, shmem_put_link, page);
3307	return page_address(page);
3308}
3309
3310#ifdef CONFIG_TMPFS_XATTR
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3311/*
3312 * Superblocks without xattr inode operations may get some security.* xattr
3313 * support from the LSM "for free". As soon as we have any other xattrs
3314 * like ACLs, we also need to implement the security.* handlers at
3315 * filesystem level, though.
3316 */
3317
3318/*
3319 * Callback for security_inode_init_security() for acquiring xattrs.
3320 */
3321static int shmem_initxattrs(struct inode *inode,
3322			    const struct xattr *xattr_array,
3323			    void *fs_info)
3324{
3325	struct shmem_inode_info *info = SHMEM_I(inode);
 
3326	const struct xattr *xattr;
3327	struct simple_xattr *new_xattr;
 
3328	size_t len;
3329
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3330	for (xattr = xattr_array; xattr->name != NULL; xattr++) {
3331		new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
3332		if (!new_xattr)
3333			return -ENOMEM;
3334
3335		len = strlen(xattr->name) + 1;
3336		new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
3337					  GFP_KERNEL);
3338		if (!new_xattr->name) {
3339			kfree(new_xattr);
3340			return -ENOMEM;
3341		}
3342
3343		memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
3344		       XATTR_SECURITY_PREFIX_LEN);
3345		memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
3346		       xattr->name, len);
3347
3348		simple_xattr_list_add(&info->xattrs, new_xattr);
 
 
 
 
 
 
 
 
 
 
3349	}
3350
3351	return 0;
3352}
3353
3354static int shmem_xattr_handler_get(const struct xattr_handler *handler,
3355				   struct dentry *unused, struct inode *inode,
3356				   const char *name, void *buffer, size_t size)
3357{
3358	struct shmem_inode_info *info = SHMEM_I(inode);
3359
3360	name = xattr_full_name(handler, name);
3361	return simple_xattr_get(&info->xattrs, name, buffer, size);
3362}
3363
3364static int shmem_xattr_handler_set(const struct xattr_handler *handler,
 
3365				   struct dentry *unused, struct inode *inode,
3366				   const char *name, const void *value,
3367				   size_t size, int flags)
3368{
3369	struct shmem_inode_info *info = SHMEM_I(inode);
 
 
 
3370
3371	name = xattr_full_name(handler, name);
3372	return simple_xattr_set(&info->xattrs, name, value, size, flags);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3373}
3374
3375static const struct xattr_handler shmem_security_xattr_handler = {
3376	.prefix = XATTR_SECURITY_PREFIX,
3377	.get = shmem_xattr_handler_get,
3378	.set = shmem_xattr_handler_set,
3379};
3380
3381static const struct xattr_handler shmem_trusted_xattr_handler = {
3382	.prefix = XATTR_TRUSTED_PREFIX,
3383	.get = shmem_xattr_handler_get,
3384	.set = shmem_xattr_handler_set,
3385};
3386
3387static const struct xattr_handler *shmem_xattr_handlers[] = {
3388#ifdef CONFIG_TMPFS_POSIX_ACL
3389	&posix_acl_access_xattr_handler,
3390	&posix_acl_default_xattr_handler,
3391#endif
 
 
3392	&shmem_security_xattr_handler,
3393	&shmem_trusted_xattr_handler,
 
3394	NULL
3395};
3396
3397static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
3398{
3399	struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
3400	return simple_xattr_list(d_inode(dentry), &info->xattrs, buffer, size);
3401}
3402#endif /* CONFIG_TMPFS_XATTR */
3403
3404static const struct inode_operations shmem_short_symlink_operations = {
 
 
3405	.get_link	= simple_get_link,
3406#ifdef CONFIG_TMPFS_XATTR
3407	.listxattr	= shmem_listxattr,
3408#endif
3409};
3410
3411static const struct inode_operations shmem_symlink_inode_operations = {
 
 
3412	.get_link	= shmem_get_link,
3413#ifdef CONFIG_TMPFS_XATTR
3414	.listxattr	= shmem_listxattr,
3415#endif
3416};
3417
3418static struct dentry *shmem_get_parent(struct dentry *child)
3419{
3420	return ERR_PTR(-ESTALE);
3421}
3422
3423static int shmem_match(struct inode *ino, void *vfh)
3424{
3425	__u32 *fh = vfh;
3426	__u64 inum = fh[2];
3427	inum = (inum << 32) | fh[1];
3428	return ino->i_ino == inum && fh[0] == ino->i_generation;
3429}
3430
 
 
 
 
 
 
 
 
3431static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
3432		struct fid *fid, int fh_len, int fh_type)
3433{
3434	struct inode *inode;
3435	struct dentry *dentry = NULL;
3436	u64 inum;
3437
3438	if (fh_len < 3)
3439		return NULL;
3440
3441	inum = fid->raw[2];
3442	inum = (inum << 32) | fid->raw[1];
3443
3444	inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
3445			shmem_match, fid->raw);
3446	if (inode) {
3447		dentry = d_find_alias(inode);
3448		iput(inode);
3449	}
3450
3451	return dentry;
3452}
3453
3454static int shmem_encode_fh(struct inode *inode, __u32 *fh, int *len,
3455				struct inode *parent)
3456{
3457	if (*len < 3) {
3458		*len = 3;
3459		return FILEID_INVALID;
3460	}
3461
3462	if (inode_unhashed(inode)) {
3463		/* Unfortunately insert_inode_hash is not idempotent,
3464		 * so as we hash inodes here rather than at creation
3465		 * time, we need a lock to ensure we only try
3466		 * to do it once
3467		 */
3468		static DEFINE_SPINLOCK(lock);
3469		spin_lock(&lock);
3470		if (inode_unhashed(inode))
3471			__insert_inode_hash(inode,
3472					    inode->i_ino + inode->i_generation);
3473		spin_unlock(&lock);
3474	}
3475
3476	fh[0] = inode->i_generation;
3477	fh[1] = inode->i_ino;
3478	fh[2] = ((__u64)inode->i_ino) >> 32;
3479
3480	*len = 3;
3481	return 1;
3482}
3483
3484static const struct export_operations shmem_export_ops = {
3485	.get_parent     = shmem_get_parent,
3486	.encode_fh      = shmem_encode_fh,
3487	.fh_to_dentry	= shmem_fh_to_dentry,
3488};
3489
3490static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
3491			       bool remount)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3492{
3493	char *this_char, *value, *rest;
3494	struct mempolicy *mpol = NULL;
3495	uid_t uid;
3496	gid_t gid;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3497
3498	while (options != NULL) {
3499		this_char = options;
3500		for (;;) {
3501			/*
3502			 * NUL-terminate this option: unfortunately,
3503			 * mount options form a comma-separated list,
3504			 * but mpol's nodelist may also contain commas.
3505			 */
3506			options = strchr(options, ',');
3507			if (options == NULL)
3508				break;
3509			options++;
3510			if (!isdigit(*options)) {
3511				options[-1] = '\0';
3512				break;
3513			}
3514		}
3515		if (!*this_char)
3516			continue;
3517		if ((value = strchr(this_char,'=')) != NULL) {
3518			*value++ = 0;
3519		} else {
3520			pr_err("tmpfs: No value for mount option '%s'\n",
3521			       this_char);
3522			goto error;
3523		}
3524
3525		if (!strcmp(this_char,"size")) {
3526			unsigned long long size;
3527			size = memparse(value,&rest);
3528			if (*rest == '%') {
3529				size <<= PAGE_SHIFT;
3530				size *= totalram_pages;
3531				do_div(size, 100);
3532				rest++;
3533			}
3534			if (*rest)
3535				goto bad_val;
3536			sbinfo->max_blocks =
3537				DIV_ROUND_UP(size, PAGE_SIZE);
3538		} else if (!strcmp(this_char,"nr_blocks")) {
3539			sbinfo->max_blocks = memparse(value, &rest);
3540			if (*rest)
3541				goto bad_val;
3542		} else if (!strcmp(this_char,"nr_inodes")) {
3543			sbinfo->max_inodes = memparse(value, &rest);
3544			if (*rest)
3545				goto bad_val;
3546		} else if (!strcmp(this_char,"mode")) {
3547			if (remount)
3548				continue;
3549			sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
3550			if (*rest)
3551				goto bad_val;
3552		} else if (!strcmp(this_char,"uid")) {
3553			if (remount)
3554				continue;
3555			uid = simple_strtoul(value, &rest, 0);
3556			if (*rest)
3557				goto bad_val;
3558			sbinfo->uid = make_kuid(current_user_ns(), uid);
3559			if (!uid_valid(sbinfo->uid))
3560				goto bad_val;
3561		} else if (!strcmp(this_char,"gid")) {
3562			if (remount)
3563				continue;
3564			gid = simple_strtoul(value, &rest, 0);
3565			if (*rest)
3566				goto bad_val;
3567			sbinfo->gid = make_kgid(current_user_ns(), gid);
3568			if (!gid_valid(sbinfo->gid))
3569				goto bad_val;
3570#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3571		} else if (!strcmp(this_char, "huge")) {
3572			int huge;
3573			huge = shmem_parse_huge(value);
3574			if (huge < 0)
3575				goto bad_val;
3576			if (!has_transparent_hugepage() &&
3577					huge != SHMEM_HUGE_NEVER)
3578				goto bad_val;
3579			sbinfo->huge = huge;
3580#endif
3581#ifdef CONFIG_NUMA
3582		} else if (!strcmp(this_char,"mpol")) {
3583			mpol_put(mpol);
3584			mpol = NULL;
3585			if (mpol_parse_str(value, &mpol))
3586				goto bad_val;
3587#endif
3588		} else {
3589			pr_err("tmpfs: Bad mount option %s\n", this_char);
3590			goto error;
3591		}
3592	}
3593	sbinfo->mpol = mpol;
3594	return 0;
3595
3596bad_val:
3597	pr_err("tmpfs: Bad value '%s' for mount option '%s'\n",
3598	       value, this_char);
3599error:
3600	mpol_put(mpol);
3601	return 1;
3602
3603}
3604
3605static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
 
 
 
3606{
3607	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3608	struct shmem_sb_info config = *sbinfo;
3609	unsigned long inodes;
3610	int error = -EINVAL;
 
3611
3612	config.mpol = NULL;
3613	if (shmem_parse_options(data, &config, true))
3614		return error;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3615
3616	spin_lock(&sbinfo->stat_lock);
3617	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
3618	if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
3619		goto out;
3620	if (config.max_inodes < inodes)
 
 
3621		goto out;
3622	/*
3623	 * Those tests disallow limited->unlimited while any are in use;
3624	 * but we must separately disallow unlimited->limited, because
3625	 * in that case we have no record of how much is already in use.
3626	 */
3627	if (config.max_blocks && !sbinfo->max_blocks)
 
 
 
3628		goto out;
3629	if (config.max_inodes && !sbinfo->max_inodes)
 
 
 
 
 
 
 
 
 
3630		goto out;
 
 
3631
3632	error = 0;
3633	sbinfo->huge = config.huge;
3634	sbinfo->max_blocks  = config.max_blocks;
3635	sbinfo->max_inodes  = config.max_inodes;
3636	sbinfo->free_inodes = config.max_inodes - inodes;
 
 
 
 
 
3637
3638	/*
3639	 * Preserve previous mempolicy unless mpol remount option was specified.
3640	 */
3641	if (config.mpol) {
3642		mpol_put(sbinfo->mpol);
3643		sbinfo->mpol = config.mpol;	/* transfers initial ref */
 
3644	}
 
 
 
 
 
 
 
3645out:
3646	spin_unlock(&sbinfo->stat_lock);
3647	return error;
3648}
3649
3650static int shmem_show_options(struct seq_file *seq, struct dentry *root)
3651{
3652	struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_sb);
 
3653
3654	if (sbinfo->max_blocks != shmem_default_max_blocks())
3655		seq_printf(seq, ",size=%luk",
3656			sbinfo->max_blocks << (PAGE_SHIFT - 10));
3657	if (sbinfo->max_inodes != shmem_default_max_inodes())
3658		seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
3659	if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
3660		seq_printf(seq, ",mode=%03ho", sbinfo->mode);
3661	if (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
3662		seq_printf(seq, ",uid=%u",
3663				from_kuid_munged(&init_user_ns, sbinfo->uid));
3664	if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
3665		seq_printf(seq, ",gid=%u",
3666				from_kgid_munged(&init_user_ns, sbinfo->gid));
3667#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3668	/* Rightly or wrongly, show huge mount option unmasked by shmem_huge */
3669	if (sbinfo->huge)
3670		seq_printf(seq, ",huge=%s", shmem_format_huge(sbinfo->huge));
3671#endif
3672	shmem_show_mpol(seq, sbinfo->mpol);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3673	return 0;
3674}
3675
3676#define MFD_NAME_PREFIX "memfd:"
3677#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
3678#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
3679
3680#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING | MFD_HUGETLB)
3681
3682SYSCALL_DEFINE2(memfd_create,
3683		const char __user *, uname,
3684		unsigned int, flags)
3685{
3686	unsigned int *file_seals;
3687	struct file *file;
3688	int fd, error;
3689	char *name;
3690	long len;
3691
3692	if (!(flags & MFD_HUGETLB)) {
3693		if (flags & ~(unsigned int)MFD_ALL_FLAGS)
3694			return -EINVAL;
3695	} else {
3696		/* Allow huge page size encoding in flags. */
3697		if (flags & ~(unsigned int)(MFD_ALL_FLAGS |
3698				(MFD_HUGE_MASK << MFD_HUGE_SHIFT)))
3699			return -EINVAL;
3700	}
3701
3702	/* length includes terminating zero */
3703	len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
3704	if (len <= 0)
3705		return -EFAULT;
3706	if (len > MFD_NAME_MAX_LEN + 1)
3707		return -EINVAL;
3708
3709	name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_KERNEL);
3710	if (!name)
3711		return -ENOMEM;
3712
3713	strcpy(name, MFD_NAME_PREFIX);
3714	if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
3715		error = -EFAULT;
3716		goto err_name;
3717	}
3718
3719	/* terminating-zero may have changed after strnlen_user() returned */
3720	if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
3721		error = -EFAULT;
3722		goto err_name;
3723	}
3724
3725	fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
3726	if (fd < 0) {
3727		error = fd;
3728		goto err_name;
3729	}
3730
3731	if (flags & MFD_HUGETLB) {
3732		struct user_struct *user = NULL;
3733
3734		file = hugetlb_file_setup(name, 0, VM_NORESERVE, &user,
3735					HUGETLB_ANONHUGE_INODE,
3736					(flags >> MFD_HUGE_SHIFT) &
3737					MFD_HUGE_MASK);
3738	} else
3739		file = shmem_file_setup(name, 0, VM_NORESERVE);
3740	if (IS_ERR(file)) {
3741		error = PTR_ERR(file);
3742		goto err_fd;
3743	}
3744	file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
3745	file->f_flags |= O_RDWR | O_LARGEFILE;
3746
3747	if (flags & MFD_ALLOW_SEALING) {
3748		file_seals = memfd_file_seals_ptr(file);
3749		*file_seals &= ~F_SEAL_SEAL;
3750	}
3751
3752	fd_install(fd, file);
3753	kfree(name);
3754	return fd;
3755
3756err_fd:
3757	put_unused_fd(fd);
3758err_name:
3759	kfree(name);
3760	return error;
3761}
3762
3763#endif /* CONFIG_TMPFS */
3764
3765static void shmem_put_super(struct super_block *sb)
3766{
3767	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
3768
 
 
 
 
 
 
 
 
 
3769	percpu_counter_destroy(&sbinfo->used_blocks);
3770	mpol_put(sbinfo->mpol);
3771	kfree(sbinfo);
3772	sb->s_fs_info = NULL;
3773}
3774
3775int shmem_fill_super(struct super_block *sb, void *data, int silent)
 
 
 
 
 
 
 
 
3776{
 
3777	struct inode *inode;
3778	struct shmem_sb_info *sbinfo;
3779	int err = -ENOMEM;
3780
3781	/* Round up to L1_CACHE_BYTES to resist false sharing */
3782	sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
3783				L1_CACHE_BYTES), GFP_KERNEL);
3784	if (!sbinfo)
3785		return -ENOMEM;
3786
3787	sbinfo->mode = S_IRWXUGO | S_ISVTX;
3788	sbinfo->uid = current_fsuid();
3789	sbinfo->gid = current_fsgid();
3790	sb->s_fs_info = sbinfo;
3791
3792#ifdef CONFIG_TMPFS
3793	/*
3794	 * Per default we only allow half of the physical ram per
3795	 * tmpfs instance, limiting inodes to one per page of lowmem;
3796	 * but the internal instance is left unlimited.
3797	 */
3798	if (!(sb->s_flags & SB_KERNMOUNT)) {
3799		sbinfo->max_blocks = shmem_default_max_blocks();
3800		sbinfo->max_inodes = shmem_default_max_inodes();
3801		if (shmem_parse_options(data, sbinfo, false)) {
3802			err = -EINVAL;
3803			goto failed;
3804		}
 
3805	} else {
3806		sb->s_flags |= SB_NOUSER;
3807	}
3808	sb->s_export_op = &shmem_export_ops;
3809	sb->s_flags |= SB_NOSEC;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3810#else
3811	sb->s_flags |= SB_NOUSER;
3812#endif
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3813
3814	spin_lock_init(&sbinfo->stat_lock);
3815	if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
3816		goto failed;
3817	sbinfo->free_inodes = sbinfo->max_inodes;
3818	spin_lock_init(&sbinfo->shrinklist_lock);
3819	INIT_LIST_HEAD(&sbinfo->shrinklist);
3820
3821	sb->s_maxbytes = MAX_LFS_FILESIZE;
3822	sb->s_blocksize = PAGE_SIZE;
3823	sb->s_blocksize_bits = PAGE_SHIFT;
3824	sb->s_magic = TMPFS_MAGIC;
3825	sb->s_op = &shmem_ops;
3826	sb->s_time_gran = 1;
3827#ifdef CONFIG_TMPFS_XATTR
3828	sb->s_xattr = shmem_xattr_handlers;
3829#endif
3830#ifdef CONFIG_TMPFS_POSIX_ACL
3831	sb->s_flags |= SB_POSIXACL;
3832#endif
3833	uuid_gen(&sb->s_uuid);
 
 
 
 
 
 
 
 
 
 
 
 
3834
3835	inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
3836	if (!inode)
 
 
 
 
 
 
 
3837		goto failed;
 
3838	inode->i_uid = sbinfo->uid;
3839	inode->i_gid = sbinfo->gid;
3840	sb->s_root = d_make_root(inode);
3841	if (!sb->s_root)
3842		goto failed;
3843	return 0;
3844
3845failed:
3846	shmem_put_super(sb);
3847	return err;
3848}
3849
3850static struct kmem_cache *shmem_inode_cachep;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3851
3852static struct inode *shmem_alloc_inode(struct super_block *sb)
3853{
3854	struct shmem_inode_info *info;
3855	info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
3856	if (!info)
3857		return NULL;
3858	return &info->vfs_inode;
3859}
3860
3861static void shmem_destroy_callback(struct rcu_head *head)
3862{
3863	struct inode *inode = container_of(head, struct inode, i_rcu);
3864	if (S_ISLNK(inode->i_mode))
3865		kfree(inode->i_link);
3866	kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
3867}
3868
3869static void shmem_destroy_inode(struct inode *inode)
3870{
3871	if (S_ISREG(inode->i_mode))
3872		mpol_free_shared_policy(&SHMEM_I(inode)->policy);
3873	call_rcu(&inode->i_rcu, shmem_destroy_callback);
 
3874}
3875
3876static void shmem_init_inode(void *foo)
3877{
3878	struct shmem_inode_info *info = foo;
3879	inode_init_once(&info->vfs_inode);
3880}
3881
3882static void shmem_init_inodecache(void)
3883{
3884	shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
3885				sizeof(struct shmem_inode_info),
3886				0, SLAB_PANIC|SLAB_ACCOUNT, shmem_init_inode);
3887}
3888
3889static void shmem_destroy_inodecache(void)
3890{
3891	kmem_cache_destroy(shmem_inode_cachep);
3892}
3893
 
 
 
 
 
 
 
3894static const struct address_space_operations shmem_aops = {
3895	.writepage	= shmem_writepage,
3896	.set_page_dirty	= __set_page_dirty_no_writeback,
3897#ifdef CONFIG_TMPFS
3898	.write_begin	= shmem_write_begin,
3899	.write_end	= shmem_write_end,
3900#endif
3901#ifdef CONFIG_MIGRATION
3902	.migratepage	= migrate_page,
3903#endif
3904	.error_remove_page = generic_error_remove_page,
3905};
3906
3907static const struct file_operations shmem_file_operations = {
3908	.mmap		= shmem_mmap,
 
3909	.get_unmapped_area = shmem_get_unmapped_area,
3910#ifdef CONFIG_TMPFS
3911	.llseek		= shmem_file_llseek,
3912	.read_iter	= shmem_file_read_iter,
3913	.write_iter	= generic_file_write_iter,
3914	.fsync		= noop_fsync,
3915	.splice_read	= generic_file_splice_read,
3916	.splice_write	= iter_file_splice_write,
3917	.fallocate	= shmem_fallocate,
3918#endif
3919};
3920
3921static const struct inode_operations shmem_inode_operations = {
3922	.getattr	= shmem_getattr,
3923	.setattr	= shmem_setattr,
3924#ifdef CONFIG_TMPFS_XATTR
3925	.listxattr	= shmem_listxattr,
3926	.set_acl	= simple_set_acl,
 
 
3927#endif
3928};
3929
3930static const struct inode_operations shmem_dir_inode_operations = {
3931#ifdef CONFIG_TMPFS
 
3932	.create		= shmem_create,
3933	.lookup		= simple_lookup,
3934	.link		= shmem_link,
3935	.unlink		= shmem_unlink,
3936	.symlink	= shmem_symlink,
3937	.mkdir		= shmem_mkdir,
3938	.rmdir		= shmem_rmdir,
3939	.mknod		= shmem_mknod,
3940	.rename		= shmem_rename2,
3941	.tmpfile	= shmem_tmpfile,
 
3942#endif
3943#ifdef CONFIG_TMPFS_XATTR
3944	.listxattr	= shmem_listxattr,
 
 
3945#endif
3946#ifdef CONFIG_TMPFS_POSIX_ACL
3947	.setattr	= shmem_setattr,
3948	.set_acl	= simple_set_acl,
3949#endif
3950};
3951
3952static const struct inode_operations shmem_special_inode_operations = {
 
3953#ifdef CONFIG_TMPFS_XATTR
3954	.listxattr	= shmem_listxattr,
3955#endif
3956#ifdef CONFIG_TMPFS_POSIX_ACL
3957	.setattr	= shmem_setattr,
3958	.set_acl	= simple_set_acl,
3959#endif
3960};
3961
3962static const struct super_operations shmem_ops = {
3963	.alloc_inode	= shmem_alloc_inode,
 
3964	.destroy_inode	= shmem_destroy_inode,
3965#ifdef CONFIG_TMPFS
3966	.statfs		= shmem_statfs,
3967	.remount_fs	= shmem_remount_fs,
3968	.show_options	= shmem_show_options,
3969#endif
 
 
 
3970	.evict_inode	= shmem_evict_inode,
3971	.drop_inode	= generic_delete_inode,
3972	.put_super	= shmem_put_super,
3973#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3974	.nr_cached_objects	= shmem_unused_huge_count,
3975	.free_cached_objects	= shmem_unused_huge_scan,
3976#endif
3977};
3978
3979static const struct vm_operations_struct shmem_vm_ops = {
3980	.fault		= shmem_fault,
3981	.map_pages	= filemap_map_pages,
3982#ifdef CONFIG_NUMA
3983	.set_policy     = shmem_set_policy,
3984	.get_policy     = shmem_get_policy,
3985#endif
3986};
3987
3988static struct dentry *shmem_mount(struct file_system_type *fs_type,
3989	int flags, const char *dev_name, void *data)
 
 
 
 
 
 
 
 
3990{
3991	return mount_nodev(fs_type, flags, data, shmem_fill_super);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
3992}
3993
3994static struct file_system_type shmem_fs_type = {
3995	.owner		= THIS_MODULE,
3996	.name		= "tmpfs",
3997	.mount		= shmem_mount,
 
 
 
3998	.kill_sb	= kill_litter_super,
3999	.fs_flags	= FS_USERNS_MOUNT,
4000};
4001
4002int __init shmem_init(void)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4003{
4004	int error;
 
 
 
4005
4006	/* If rootfs called this, don't re-init */
4007	if (shmem_inode_cachep)
4008		return 0;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4009
4010	shmem_init_inodecache();
4011
 
 
 
 
4012	error = register_filesystem(&shmem_fs_type);
4013	if (error) {
4014		pr_err("Could not register tmpfs\n");
4015		goto out2;
4016	}
4017
4018	shm_mnt = kern_mount(&shmem_fs_type);
4019	if (IS_ERR(shm_mnt)) {
4020		error = PTR_ERR(shm_mnt);
4021		pr_err("Could not kern_mount tmpfs\n");
4022		goto out1;
4023	}
4024
4025#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 
 
 
 
 
 
 
 
4026	if (has_transparent_hugepage() && shmem_huge > SHMEM_HUGE_DENY)
4027		SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4028	else
4029		shmem_huge = 0; /* just in case it was patched */
 
 
 
 
 
 
 
4030#endif
4031	return 0;
4032
4033out1:
4034	unregister_filesystem(&shmem_fs_type);
4035out2:
 
 
 
4036	shmem_destroy_inodecache();
4037	shm_mnt = ERR_PTR(error);
4038	return error;
4039}
4040
4041#if defined(CONFIG_TRANSPARENT_HUGE_PAGECACHE) && defined(CONFIG_SYSFS)
4042static ssize_t shmem_enabled_show(struct kobject *kobj,
4043		struct kobj_attribute *attr, char *buf)
4044{
4045	int values[] = {
4046		SHMEM_HUGE_ALWAYS,
4047		SHMEM_HUGE_WITHIN_SIZE,
4048		SHMEM_HUGE_ADVISE,
4049		SHMEM_HUGE_NEVER,
4050		SHMEM_HUGE_DENY,
4051		SHMEM_HUGE_FORCE,
4052	};
4053	int i, count;
4054
4055	for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) {
4056		const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s ";
4057
4058		count += sprintf(buf + count, fmt,
4059				shmem_format_huge(values[i]));
 
 
4060	}
4061	buf[count - 1] = '\n';
4062	return count;
 
4063}
4064
4065static ssize_t shmem_enabled_store(struct kobject *kobj,
4066		struct kobj_attribute *attr, const char *buf, size_t count)
4067{
4068	char tmp[16];
4069	int huge;
4070
4071	if (count + 1 > sizeof(tmp))
4072		return -EINVAL;
4073	memcpy(tmp, buf, count);
4074	tmp[count] = '\0';
4075	if (count && tmp[count - 1] == '\n')
4076		tmp[count - 1] = '\0';
4077
4078	huge = shmem_parse_huge(tmp);
4079	if (huge == -EINVAL)
4080		return -EINVAL;
4081	if (!has_transparent_hugepage() &&
4082			huge != SHMEM_HUGE_NEVER && huge != SHMEM_HUGE_DENY)
4083		return -EINVAL;
4084
4085	shmem_huge = huge;
4086	if (shmem_huge > SHMEM_HUGE_DENY)
4087		SHMEM_SB(shm_mnt->mnt_sb)->huge = shmem_huge;
4088	return count;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4089}
4090
4091struct kobj_attribute shmem_enabled_attr =
4092	__ATTR(shmem_enabled, 0644, shmem_enabled_show, shmem_enabled_store);
4093#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE && CONFIG_SYSFS */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4094
4095#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
4096bool shmem_huge_enabled(struct vm_area_struct *vma)
 
 
 
 
 
 
 
 
 
 
 
4097{
4098	struct inode *inode = file_inode(vma->vm_file);
4099	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
4100	loff_t i_size;
4101	pgoff_t off;
4102
4103	if (shmem_huge == SHMEM_HUGE_FORCE)
4104		return true;
4105	if (shmem_huge == SHMEM_HUGE_DENY)
4106		return false;
4107	switch (sbinfo->huge) {
4108		case SHMEM_HUGE_NEVER:
4109			return false;
4110		case SHMEM_HUGE_ALWAYS:
4111			return true;
4112		case SHMEM_HUGE_WITHIN_SIZE:
4113			off = round_up(vma->vm_pgoff, HPAGE_PMD_NR);
4114			i_size = round_up(i_size_read(inode), PAGE_SIZE);
4115			if (i_size >= HPAGE_PMD_SIZE &&
4116					i_size >> PAGE_SHIFT >= off)
4117				return true;
4118			/* fall through */
4119		case SHMEM_HUGE_ADVISE:
4120			/* TODO: implement fadvise() hints */
4121			return (vma->vm_flags & VM_HUGEPAGE);
4122		default:
4123			VM_BUG_ON(1);
4124			return false;
4125	}
 
 
 
4126}
4127#endif /* CONFIG_TRANSPARENT_HUGE_PAGECACHE */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4128
4129#else /* !CONFIG_SHMEM */
4130
4131/*
4132 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
4133 *
4134 * This is intended for small system where the benefits of the full
4135 * shmem code (swap-backed and resource-limited) are outweighed by
4136 * their complexity. On systems without swap this code should be
4137 * effectively equivalent, but much lighter weight.
4138 */
4139
4140static struct file_system_type shmem_fs_type = {
4141	.name		= "tmpfs",
4142	.mount		= ramfs_mount,
4143	.kill_sb	= kill_litter_super,
 
4144	.fs_flags	= FS_USERNS_MOUNT,
4145};
4146
4147int __init shmem_init(void)
4148{
4149	BUG_ON(register_filesystem(&shmem_fs_type) != 0);
4150
4151	shm_mnt = kern_mount(&shmem_fs_type);
4152	BUG_ON(IS_ERR(shm_mnt));
4153
4154	return 0;
4155}
4156
4157int shmem_unuse(swp_entry_t swap, struct page *page)
4158{
4159	return 0;
4160}
4161
4162int shmem_lock(struct file *file, int lock, struct user_struct *user)
4163{
4164	return 0;
4165}
4166
4167void shmem_unlock_mapping(struct address_space *mapping)
4168{
4169}
4170
4171#ifdef CONFIG_MMU
4172unsigned long shmem_get_unmapped_area(struct file *file,
4173				      unsigned long addr, unsigned long len,
4174				      unsigned long pgoff, unsigned long flags)
4175{
4176	return current->mm->get_unmapped_area(file, addr, len, pgoff, flags);
4177}
4178#endif
4179
4180void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
4181{
4182	truncate_inode_pages_range(inode->i_mapping, lstart, lend);
4183}
4184EXPORT_SYMBOL_GPL(shmem_truncate_range);
4185
4186#define shmem_vm_ops				generic_file_vm_ops
 
4187#define shmem_file_operations			ramfs_file_operations
4188#define shmem_get_inode(sb, dir, mode, dev, flags)	ramfs_get_inode(sb, dir, mode, dev)
4189#define shmem_acct_size(flags, size)		0
4190#define shmem_unacct_size(flags, size)		do {} while (0)
4191
 
 
 
 
 
 
 
 
4192#endif /* CONFIG_SHMEM */
4193
4194/* common code */
4195
4196static const struct dentry_operations anon_ops = {
4197	.d_dname = simple_dname
4198};
4199
4200static struct file *__shmem_file_setup(struct vfsmount *mnt, const char *name, loff_t size,
4201				       unsigned long flags, unsigned int i_flags)
4202{
4203	struct file *res;
4204	struct inode *inode;
4205	struct path path;
4206	struct super_block *sb;
4207	struct qstr this;
4208
4209	if (IS_ERR(mnt))
4210		return ERR_CAST(mnt);
4211
4212	if (size < 0 || size > MAX_LFS_FILESIZE)
4213		return ERR_PTR(-EINVAL);
4214
4215	if (shmem_acct_size(flags, size))
4216		return ERR_PTR(-ENOMEM);
4217
4218	res = ERR_PTR(-ENOMEM);
4219	this.name = name;
4220	this.len = strlen(name);
4221	this.hash = 0; /* will go */
4222	sb = mnt->mnt_sb;
4223	path.mnt = mntget(mnt);
4224	path.dentry = d_alloc_pseudo(sb, &this);
4225	if (!path.dentry)
4226		goto put_memory;
4227	d_set_d_op(path.dentry, &anon_ops);
4228
4229	res = ERR_PTR(-ENOSPC);
4230	inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
4231	if (!inode)
4232		goto put_memory;
4233
 
 
 
 
 
 
4234	inode->i_flags |= i_flags;
4235	d_instantiate(path.dentry, inode);
4236	inode->i_size = size;
4237	clear_nlink(inode);	/* It is unlinked */
4238	res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
 
 
 
4239	if (IS_ERR(res))
4240		goto put_path;
4241
4242	res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
4243		  &shmem_file_operations);
4244	if (IS_ERR(res))
4245		goto put_path;
4246
4247	return res;
4248
4249put_memory:
4250	shmem_unacct_size(flags, size);
4251put_path:
4252	path_put(&path);
4253	return res;
4254}
4255
4256/**
4257 * shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
4258 * 	kernel internal.  There will be NO LSM permission checks against the
4259 * 	underlying inode.  So users of this interface must do LSM checks at a
4260 *	higher layer.  The users are the big_key and shm implementations.  LSM
4261 *	checks are provided at the key or shm level rather than the inode.
4262 * @name: name for dentry (to be seen in /proc/<pid>/maps
4263 * @size: size to be set for the file
4264 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4265 */
4266struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
4267{
4268	return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
4269}
 
4270
4271/**
4272 * shmem_file_setup - get an unlinked file living in tmpfs
4273 * @name: name for dentry (to be seen in /proc/<pid>/maps
4274 * @size: size to be set for the file
4275 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4276 */
4277struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
4278{
4279	return __shmem_file_setup(shm_mnt, name, size, flags, 0);
4280}
4281EXPORT_SYMBOL_GPL(shmem_file_setup);
4282
4283/**
4284 * shmem_file_setup_with_mnt - get an unlinked file living in tmpfs
4285 * @mnt: the tmpfs mount where the file will be created
4286 * @name: name for dentry (to be seen in /proc/<pid>/maps
4287 * @size: size to be set for the file
4288 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
4289 */
4290struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt, const char *name,
4291				       loff_t size, unsigned long flags)
4292{
4293	return __shmem_file_setup(mnt, name, size, flags, 0);
4294}
4295EXPORT_SYMBOL_GPL(shmem_file_setup_with_mnt);
4296
4297/**
4298 * shmem_zero_setup - setup a shared anonymous mapping
4299 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
4300 */
4301int shmem_zero_setup(struct vm_area_struct *vma)
4302{
4303	struct file *file;
4304	loff_t size = vma->vm_end - vma->vm_start;
4305
4306	/*
4307	 * Cloning a new file under mmap_sem leads to a lock ordering conflict
4308	 * between XFS directory reading and selinux: since this file is only
4309	 * accessible to the user through its mapping, use S_PRIVATE flag to
4310	 * bypass file security, in the same way as shmem_kernel_file_setup().
4311	 */
4312	file = shmem_kernel_file_setup("dev/zero", size, vma->vm_flags);
4313	if (IS_ERR(file))
4314		return PTR_ERR(file);
4315
4316	if (vma->vm_file)
4317		fput(vma->vm_file);
4318	vma->vm_file = file;
4319	vma->vm_ops = &shmem_vm_ops;
4320
4321	if (IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE) &&
4322			((vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK) <
4323			(vma->vm_end & HPAGE_PMD_MASK)) {
4324		khugepaged_enter(vma, vma->vm_flags);
4325	}
4326
4327	return 0;
4328}
4329
4330/**
4331 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
4332 * @mapping:	the page's address_space
4333 * @index:	the page index
4334 * @gfp:	the page allocator flags to use if allocating
4335 *
4336 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
4337 * with any new page allocations done using the specified allocation flags.
4338 * But read_cache_page_gfp() uses the ->readpage() method: which does not
4339 * suit tmpfs, since it may have pages in swapcache, and needs to find those
4340 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
4341 *
4342 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
4343 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
4344 */
4345struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
4346					 pgoff_t index, gfp_t gfp)
4347{
4348#ifdef CONFIG_SHMEM
4349	struct inode *inode = mapping->host;
4350	struct page *page;
4351	int error;
4352
4353	BUG_ON(mapping->a_ops != &shmem_aops);
4354	error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE,
4355				  gfp, NULL, NULL, NULL);
4356	if (error)
4357		page = ERR_PTR(error);
4358	else
4359		unlock_page(page);
4360	return page;
4361#else
4362	/*
4363	 * The tiny !SHMEM case uses ramfs without swap
4364	 */
4365	return read_cache_page_gfp(mapping, index, gfp);
4366#endif
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
4367}
4368EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);