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/pagemap.h>
  29#include <linux/file.h>
  30#include <linux/mm.h>
  31#include <linux/module.h>
  32#include <linux/swap.h>
 
 
  33
  34static struct vfsmount *shm_mnt;
  35
  36#ifdef CONFIG_SHMEM
  37/*
  38 * This virtual memory filesystem is heavily based on the ramfs. It
  39 * extends ramfs by the ability to use swap and honor resource limits
  40 * which makes it a completely usable filesystem.
  41 */
  42
  43#include <linux/xattr.h>
  44#include <linux/exportfs.h>
  45#include <linux/posix_acl.h>
  46#include <linux/generic_acl.h>
  47#include <linux/mman.h>
  48#include <linux/string.h>
  49#include <linux/slab.h>
  50#include <linux/backing-dev.h>
  51#include <linux/shmem_fs.h>
  52#include <linux/writeback.h>
  53#include <linux/blkdev.h>
  54#include <linux/pagevec.h>
  55#include <linux/percpu_counter.h>
 
  56#include <linux/splice.h>
  57#include <linux/security.h>
  58#include <linux/swapops.h>
  59#include <linux/mempolicy.h>
  60#include <linux/namei.h>
  61#include <linux/ctype.h>
  62#include <linux/migrate.h>
  63#include <linux/highmem.h>
  64#include <linux/seq_file.h>
  65#include <linux/magic.h>
 
 
 
  66
  67#include <asm/uaccess.h>
  68#include <asm/pgtable.h>
  69
  70#define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
  71#define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
 
 
  72
  73/* Pretend that each entry is of this size in directory's i_size */
  74#define BOGO_DIRENT_SIZE 20
  75
  76/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
  77#define SHORT_SYMLINK_LEN 128
  78
  79struct shmem_xattr {
  80	struct list_head list;	/* anchored by shmem_inode_info->xattr_list */
  81	char *name;		/* xattr name */
  82	size_t size;
  83	char value[0];
  84};
  85
  86/* Flag allocation requirements to shmem_getpage */
  87enum sgp_type {
  88	SGP_READ,	/* don't exceed i_size, don't allocate page */
  89	SGP_CACHE,	/* don't exceed i_size, may allocate page */
  90	SGP_DIRTY,	/* like SGP_CACHE, but set new page dirty */
  91	SGP_WRITE,	/* may exceed i_size, may allocate page */
  92};
  93
  94#ifdef CONFIG_TMPFS
  95static unsigned long shmem_default_max_blocks(void)
  96{
  97	return totalram_pages / 2;
  98}
  99
 100static unsigned long shmem_default_max_inodes(void)
 101{
 102	return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
 103}
 104#endif
 105
 
 
 
 106static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 107	struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
 
 108
 109static inline int shmem_getpage(struct inode *inode, pgoff_t index,
 110	struct page **pagep, enum sgp_type sgp, int *fault_type)
 111{
 112	return shmem_getpage_gfp(inode, index, pagep, sgp,
 113			mapping_gfp_mask(inode->i_mapping), fault_type);
 114}
 115
 116static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
 117{
 118	return sb->s_fs_info;
 119}
 120
 121/*
 122 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
 123 * for shared memory and for shared anonymous (/dev/zero) mappings
 124 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
 125 * consistent with the pre-accounting of private mappings ...
 126 */
 127static inline int shmem_acct_size(unsigned long flags, loff_t size)
 128{
 129	return (flags & VM_NORESERVE) ?
 130		0 : security_vm_enough_memory_kern(VM_ACCT(size));
 131}
 132
 133static inline void shmem_unacct_size(unsigned long flags, loff_t size)
 134{
 135	if (!(flags & VM_NORESERVE))
 136		vm_unacct_memory(VM_ACCT(size));
 137}
 138
 
 
 
 
 
 
 
 
 
 
 
 
 
 139/*
 140 * ... whereas tmpfs objects are accounted incrementally as
 141 * pages are allocated, in order to allow huge sparse files.
 142 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
 143 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
 144 */
 145static inline int shmem_acct_block(unsigned long flags)
 146{
 147	return (flags & VM_NORESERVE) ?
 148		security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
 
 
 
 149}
 150
 151static inline void shmem_unacct_blocks(unsigned long flags, long pages)
 152{
 153	if (flags & VM_NORESERVE)
 154		vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
 155}
 156
 157static const struct super_operations shmem_ops;
 158static const struct address_space_operations shmem_aops;
 159static const struct file_operations shmem_file_operations;
 160static const struct inode_operations shmem_inode_operations;
 161static const struct inode_operations shmem_dir_inode_operations;
 162static const struct inode_operations shmem_special_inode_operations;
 163static const struct vm_operations_struct shmem_vm_ops;
 164
 165static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
 166	.ra_pages	= 0,	/* No readahead */
 167	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
 168};
 169
 170static LIST_HEAD(shmem_swaplist);
 171static DEFINE_MUTEX(shmem_swaplist_mutex);
 172
 173static int shmem_reserve_inode(struct super_block *sb)
 174{
 175	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 176	if (sbinfo->max_inodes) {
 177		spin_lock(&sbinfo->stat_lock);
 178		if (!sbinfo->free_inodes) {
 179			spin_unlock(&sbinfo->stat_lock);
 180			return -ENOSPC;
 181		}
 182		sbinfo->free_inodes--;
 183		spin_unlock(&sbinfo->stat_lock);
 184	}
 185	return 0;
 186}
 187
 188static void shmem_free_inode(struct super_block *sb)
 189{
 190	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
 191	if (sbinfo->max_inodes) {
 192		spin_lock(&sbinfo->stat_lock);
 193		sbinfo->free_inodes++;
 194		spin_unlock(&sbinfo->stat_lock);
 195	}
 196}
 197
 198/**
 199 * shmem_recalc_inode - recalculate the block usage of an inode
 200 * @inode: inode to recalc
 201 *
 202 * We have to calculate the free blocks since the mm can drop
 203 * undirtied hole pages behind our back.
 204 *
 205 * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
 206 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
 207 *
 208 * It has to be called with the spinlock held.
 209 */
 210static void shmem_recalc_inode(struct inode *inode)
 211{
 212	struct shmem_inode_info *info = SHMEM_I(inode);
 213	long freed;
 214
 215	freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
 216	if (freed > 0) {
 217		struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
 218		if (sbinfo->max_blocks)
 219			percpu_counter_add(&sbinfo->used_blocks, -freed);
 220		info->alloced -= freed;
 221		inode->i_blocks -= freed * BLOCKS_PER_PAGE;
 222		shmem_unacct_blocks(info->flags, freed);
 223	}
 224}
 225
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 226/*
 227 * Replace item expected in radix tree by a new item, while holding tree lock.
 228 */
 229static int shmem_radix_tree_replace(struct address_space *mapping,
 230			pgoff_t index, void *expected, void *replacement)
 231{
 
 232	void **pslot;
 233	void *item = NULL;
 234
 235	VM_BUG_ON(!expected);
 236	pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
 237	if (pslot)
 238		item = radix_tree_deref_slot_protected(pslot,
 239							&mapping->tree_lock);
 240	if (item != expected)
 241		return -ENOENT;
 242	if (replacement)
 243		radix_tree_replace_slot(pslot, replacement);
 244	else
 245		radix_tree_delete(&mapping->page_tree, index);
 246	return 0;
 247}
 248
 249/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 250 * Like add_to_page_cache_locked, but error if expected item has gone.
 251 */
 252static int shmem_add_to_page_cache(struct page *page,
 253				   struct address_space *mapping,
 254				   pgoff_t index, gfp_t gfp, void *expected)
 255{
 256	int error = 0;
 257
 258	VM_BUG_ON(!PageLocked(page));
 259	VM_BUG_ON(!PageSwapBacked(page));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 260
 261	if (!expected)
 262		error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
 263	if (!error) {
 264		page_cache_get(page);
 265		page->mapping = mapping;
 266		page->index = index;
 267
 268		spin_lock_irq(&mapping->tree_lock);
 269		if (!expected)
 270			error = radix_tree_insert(&mapping->page_tree,
 271							index, page);
 272		else
 273			error = shmem_radix_tree_replace(mapping, index,
 274							expected, page);
 275		if (!error) {
 276			mapping->nrpages++;
 277			__inc_zone_page_state(page, NR_FILE_PAGES);
 278			__inc_zone_page_state(page, NR_SHMEM);
 279			spin_unlock_irq(&mapping->tree_lock);
 280		} else {
 281			page->mapping = NULL;
 282			spin_unlock_irq(&mapping->tree_lock);
 283			page_cache_release(page);
 284		}
 285		if (!expected)
 286			radix_tree_preload_end();
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 287	}
 288	if (error)
 289		mem_cgroup_uncharge_cache_page(page);
 290	return error;
 291}
 292
 293/*
 294 * Like delete_from_page_cache, but substitutes swap for page.
 295 */
 296static void shmem_delete_from_page_cache(struct page *page, void *radswap)
 297{
 298	struct address_space *mapping = page->mapping;
 299	int error;
 300
 
 
 301	spin_lock_irq(&mapping->tree_lock);
 302	error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
 303	page->mapping = NULL;
 304	mapping->nrpages--;
 305	__dec_zone_page_state(page, NR_FILE_PAGES);
 306	__dec_zone_page_state(page, NR_SHMEM);
 307	spin_unlock_irq(&mapping->tree_lock);
 308	page_cache_release(page);
 309	BUG_ON(error);
 310}
 311
 312/*
 313 * Like find_get_pages, but collecting swap entries as well as pages.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 314 */
 315static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
 316					pgoff_t start, unsigned int nr_pages,
 317					struct page **pages, pgoff_t *indices)
 318{
 319	unsigned int i;
 320	unsigned int ret;
 321	unsigned int nr_found;
 322
 323	rcu_read_lock();
 324restart:
 325	nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
 326				(void ***)pages, indices, start, nr_pages);
 327	ret = 0;
 328	for (i = 0; i < nr_found; i++) {
 329		struct page *page;
 330repeat:
 331		page = radix_tree_deref_slot((void **)pages[i]);
 332		if (unlikely(!page))
 333			continue;
 334		if (radix_tree_exception(page)) {
 335			if (radix_tree_deref_retry(page))
 336				goto restart;
 337			/*
 338			 * Otherwise, we must be storing a swap entry
 339			 * here as an exceptional entry: so return it
 340			 * without attempting to raise page count.
 341			 */
 342			goto export;
 343		}
 344		if (!page_cache_get_speculative(page))
 345			goto repeat;
 346
 347		/* Has the page moved? */
 348		if (unlikely(page != *((void **)pages[i]))) {
 349			page_cache_release(page);
 350			goto repeat;
 351		}
 352export:
 353		indices[ret] = indices[i];
 354		pages[ret] = page;
 355		ret++;
 356	}
 357	if (unlikely(!ret && nr_found))
 358		goto restart;
 359	rcu_read_unlock();
 360	return ret;
 
 361}
 362
 363/*
 364 * Remove swap entry from radix tree, free the swap and its page cache.
 
 
 
 
 365 */
 366static int shmem_free_swap(struct address_space *mapping,
 367			   pgoff_t index, void *radswap)
 368{
 369	int error;
 
 
 
 370
 371	spin_lock_irq(&mapping->tree_lock);
 372	error = shmem_radix_tree_replace(mapping, index, radswap, NULL);
 373	spin_unlock_irq(&mapping->tree_lock);
 374	if (!error)
 375		free_swap_and_cache(radix_to_swp_entry(radswap));
 376	return error;
 
 
 
 
 
 
 
 
 
 
 
 
 377}
 378
 379/*
 380 * Pagevec may contain swap entries, so shuffle up pages before releasing.
 381 */
 382static void shmem_pagevec_release(struct pagevec *pvec)
 383{
 384	int i, j;
 
 
 385
 386	for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
 387		struct page *page = pvec->pages[i];
 388		if (!radix_tree_exceptional_entry(page))
 389			pvec->pages[j++] = page;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 390	}
 391	pvec->nr = j;
 392	pagevec_release(pvec);
 393}
 394
 395/*
 396 * Remove range of pages and swap entries from radix tree, and free them.
 
 397 */
 398void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
 
 399{
 400	struct address_space *mapping = inode->i_mapping;
 401	struct shmem_inode_info *info = SHMEM_I(inode);
 402	pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
 403	unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
 404	pgoff_t end = (lend >> PAGE_CACHE_SHIFT);
 
 405	struct pagevec pvec;
 406	pgoff_t indices[PAGEVEC_SIZE];
 407	long nr_swaps_freed = 0;
 408	pgoff_t index;
 409	int i;
 410
 411	BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
 
 412
 413	pagevec_init(&pvec, 0);
 414	index = start;
 415	while (index <= end) {
 416		pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
 417			min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 418							pvec.pages, indices);
 419		if (!pvec.nr)
 420			break;
 421		mem_cgroup_uncharge_start();
 422		for (i = 0; i < pagevec_count(&pvec); i++) {
 423			struct page *page = pvec.pages[i];
 424
 425			index = indices[i];
 426			if (index > end)
 427				break;
 428
 429			if (radix_tree_exceptional_entry(page)) {
 
 
 430				nr_swaps_freed += !shmem_free_swap(mapping,
 431								index, page);
 432				continue;
 433			}
 434
 
 
 435			if (!trylock_page(page))
 436				continue;
 437			if (page->mapping == mapping) {
 438				VM_BUG_ON(PageWriteback(page));
 439				truncate_inode_page(mapping, page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 440			}
 441			unlock_page(page);
 442		}
 443		shmem_pagevec_release(&pvec);
 444		mem_cgroup_uncharge_end();
 445		cond_resched();
 446		index++;
 447	}
 448
 449	if (partial) {
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 450		struct page *page = NULL;
 451		shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
 452		if (page) {
 453			zero_user_segment(page, partial, PAGE_CACHE_SIZE);
 454			set_page_dirty(page);
 455			unlock_page(page);
 456			page_cache_release(page);
 457		}
 458	}
 
 
 459
 460	index = start;
 461	for ( ; ; ) {
 462		cond_resched();
 463		pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
 464			min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
 465							pvec.pages, indices);
 
 466		if (!pvec.nr) {
 467			if (index == start)
 
 468				break;
 
 469			index = start;
 470			continue;
 471		}
 472		if (index == start && indices[0] > end) {
 473			shmem_pagevec_release(&pvec);
 474			break;
 475		}
 476		mem_cgroup_uncharge_start();
 477		for (i = 0; i < pagevec_count(&pvec); i++) {
 478			struct page *page = pvec.pages[i];
 479
 480			index = indices[i];
 481			if (index > end)
 482				break;
 483
 484			if (radix_tree_exceptional_entry(page)) {
 485				nr_swaps_freed += !shmem_free_swap(mapping,
 486								index, page);
 
 
 
 
 
 
 487				continue;
 488			}
 489
 490			lock_page(page);
 491			if (page->mapping == mapping) {
 492				VM_BUG_ON(PageWriteback(page));
 493				truncate_inode_page(mapping, page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 494			}
 495			unlock_page(page);
 496		}
 497		shmem_pagevec_release(&pvec);
 498		mem_cgroup_uncharge_end();
 499		index++;
 500	}
 501
 502	spin_lock(&info->lock);
 503	info->swapped -= nr_swaps_freed;
 504	shmem_recalc_inode(inode);
 505	spin_unlock(&info->lock);
 
 506
 507	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 
 
 
 508}
 509EXPORT_SYMBOL_GPL(shmem_truncate_range);
 510
 511static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
 
 512{
 513	struct inode *inode = dentry->d_inode;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 514	int error;
 515
 516	error = inode_change_ok(inode, attr);
 517	if (error)
 518		return error;
 519
 520	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
 521		loff_t oldsize = inode->i_size;
 522		loff_t newsize = attr->ia_size;
 523
 
 
 
 
 
 524		if (newsize != oldsize) {
 
 
 
 
 525			i_size_write(inode, newsize);
 526			inode->i_ctime = inode->i_mtime = CURRENT_TIME;
 527		}
 528		if (newsize < oldsize) {
 529			loff_t holebegin = round_up(newsize, PAGE_SIZE);
 530			unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
 531			shmem_truncate_range(inode, newsize, (loff_t)-1);
 
 
 
 
 532			/* unmap again to remove racily COWed private pages */
 533			unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 534		}
 535	}
 536
 537	setattr_copy(inode, attr);
 538#ifdef CONFIG_TMPFS_POSIX_ACL
 539	if (attr->ia_valid & ATTR_MODE)
 540		error = generic_acl_chmod(inode);
 541#endif
 542	return error;
 543}
 544
 545static void shmem_evict_inode(struct inode *inode)
 546{
 547	struct shmem_inode_info *info = SHMEM_I(inode);
 548	struct shmem_xattr *xattr, *nxattr;
 549
 550	if (inode->i_mapping->a_ops == &shmem_aops) {
 551		shmem_unacct_size(info->flags, inode->i_size);
 552		inode->i_size = 0;
 553		shmem_truncate_range(inode, 0, (loff_t)-1);
 
 
 
 
 
 
 
 
 554		if (!list_empty(&info->swaplist)) {
 555			mutex_lock(&shmem_swaplist_mutex);
 556			list_del_init(&info->swaplist);
 557			mutex_unlock(&shmem_swaplist_mutex);
 558		}
 559	} else
 560		kfree(info->symlink);
 561
 562	list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
 563		kfree(xattr->name);
 564		kfree(xattr);
 565	}
 566	BUG_ON(inode->i_blocks);
 
 
 567	shmem_free_inode(inode->i_sb);
 568	end_writeback(inode);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 569}
 570
 571/*
 572 * If swap found in inode, free it and move page from swapcache to filecache.
 573 */
 574static int shmem_unuse_inode(struct shmem_inode_info *info,
 575			     swp_entry_t swap, struct page *page)
 576{
 577	struct address_space *mapping = info->vfs_inode.i_mapping;
 578	void *radswap;
 579	pgoff_t index;
 580	int error;
 
 581
 582	radswap = swp_to_radix_entry(swap);
 583	index = radix_tree_locate_item(&mapping->page_tree, radswap);
 584	if (index == -1)
 585		return 0;
 586
 587	/*
 588	 * Move _head_ to start search for next from here.
 589	 * But be careful: shmem_evict_inode checks list_empty without taking
 590	 * mutex, and there's an instant in list_move_tail when info->swaplist
 591	 * would appear empty, if it were the only one on shmem_swaplist.
 592	 */
 593	if (shmem_swaplist.next != &info->swaplist)
 594		list_move_tail(&shmem_swaplist, &info->swaplist);
 595
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 596	/*
 597	 * We rely on shmem_swaplist_mutex, not only to protect the swaplist,
 598	 * but also to hold up shmem_evict_inode(): so inode cannot be freed
 599	 * beneath us (pagelock doesn't help until the page is in pagecache).
 600	 */
 601	error = shmem_add_to_page_cache(page, mapping, index,
 602						GFP_NOWAIT, radswap);
 603	/* which does mem_cgroup_uncharge_cache_page on error */
 604
 605	if (error != -ENOMEM) {
 606		/*
 607		 * Truncation and eviction use free_swap_and_cache(), which
 608		 * only does trylock page: if we raced, best clean up here.
 609		 */
 610		delete_from_swap_cache(page);
 611		set_page_dirty(page);
 612		if (!error) {
 613			spin_lock(&info->lock);
 614			info->swapped--;
 615			spin_unlock(&info->lock);
 616			swap_free(swap);
 617		}
 618		error = 1;	/* not an error, but entry was found */
 619	}
 620	return error;
 621}
 622
 623/*
 624 * Search through swapped inodes to find and replace swap by page.
 625 */
 626int shmem_unuse(swp_entry_t swap, struct page *page)
 627{
 628	struct list_head *this, *next;
 629	struct shmem_inode_info *info;
 630	int found = 0;
 631	int error;
 
 
 
 
 
 
 
 632
 633	/*
 634	 * Charge page using GFP_KERNEL while we can wait, before taking
 635	 * the shmem_swaplist_mutex which might hold up shmem_writepage().
 636	 * Charged back to the user (not to caller) when swap account is used.
 637	 */
 638	error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
 
 639	if (error)
 640		goto out;
 641	/* No radix_tree_preload: swap entry keeps a place for page in tree */
 
 642
 643	mutex_lock(&shmem_swaplist_mutex);
 644	list_for_each_safe(this, next, &shmem_swaplist) {
 645		info = list_entry(this, struct shmem_inode_info, swaplist);
 646		if (info->swapped)
 647			found = shmem_unuse_inode(info, swap, page);
 648		else
 649			list_del_init(&info->swaplist);
 650		cond_resched();
 651		if (found)
 652			break;
 
 653	}
 654	mutex_unlock(&shmem_swaplist_mutex);
 655
 656	if (!found)
 657		mem_cgroup_uncharge_cache_page(page);
 658	if (found < 0)
 659		error = found;
 
 
 660out:
 661	unlock_page(page);
 662	page_cache_release(page);
 663	return error;
 664}
 665
 666/*
 667 * Move the page from the page cache to the swap cache.
 668 */
 669static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 670{
 671	struct shmem_inode_info *info;
 672	struct address_space *mapping;
 673	struct inode *inode;
 674	swp_entry_t swap;
 675	pgoff_t index;
 676
 
 677	BUG_ON(!PageLocked(page));
 678	mapping = page->mapping;
 679	index = page->index;
 680	inode = mapping->host;
 681	info = SHMEM_I(inode);
 682	if (info->flags & VM_LOCKED)
 683		goto redirty;
 684	if (!total_swap_pages)
 685		goto redirty;
 686
 687	/*
 688	 * shmem_backing_dev_info's capabilities prevent regular writeback or
 689	 * sync from ever calling shmem_writepage; but a stacking filesystem
 690	 * might use ->writepage of its underlying filesystem, in which case
 691	 * tmpfs should write out to swap only in response to memory pressure,
 692	 * and not for the writeback threads or sync.
 693	 */
 694	if (!wbc->for_reclaim) {
 695		WARN_ON_ONCE(1);	/* Still happens? Tell us about it! */
 696		goto redirty;
 697	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 698	swap = get_swap_page();
 699	if (!swap.val)
 700		goto redirty;
 701
 
 
 
 702	/*
 703	 * Add inode to shmem_unuse()'s list of swapped-out inodes,
 704	 * if it's not already there.  Do it now before the page is
 705	 * moved to swap cache, when its pagelock no longer protects
 706	 * the inode from eviction.  But don't unlock the mutex until
 707	 * we've incremented swapped, because shmem_unuse_inode() will
 708	 * prune a !swapped inode from the swaplist under this mutex.
 709	 */
 710	mutex_lock(&shmem_swaplist_mutex);
 711	if (list_empty(&info->swaplist))
 712		list_add_tail(&info->swaplist, &shmem_swaplist);
 713
 714	if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
 
 
 
 
 
 715		swap_shmem_alloc(swap);
 716		shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
 717
 718		spin_lock(&info->lock);
 719		info->swapped++;
 720		shmem_recalc_inode(inode);
 721		spin_unlock(&info->lock);
 722
 723		mutex_unlock(&shmem_swaplist_mutex);
 724		BUG_ON(page_mapped(page));
 725		swap_writepage(page, wbc);
 726		return 0;
 727	}
 728
 729	mutex_unlock(&shmem_swaplist_mutex);
 730	swapcache_free(swap, NULL);
 
 731redirty:
 732	set_page_dirty(page);
 733	if (wbc->for_reclaim)
 734		return AOP_WRITEPAGE_ACTIVATE;	/* Return with page locked */
 735	unlock_page(page);
 736	return 0;
 737}
 738
 739#ifdef CONFIG_NUMA
 740#ifdef CONFIG_TMPFS
 741static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
 742{
 743	char buffer[64];
 744
 745	if (!mpol || mpol->mode == MPOL_DEFAULT)
 746		return;		/* show nothing */
 747
 748	mpol_to_str(buffer, sizeof(buffer), mpol, 1);
 749
 750	seq_printf(seq, ",mpol=%s", buffer);
 751}
 752
 753static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
 754{
 755	struct mempolicy *mpol = NULL;
 756	if (sbinfo->mpol) {
 757		spin_lock(&sbinfo->stat_lock);	/* prevent replace/use races */
 758		mpol = sbinfo->mpol;
 759		mpol_get(mpol);
 760		spin_unlock(&sbinfo->stat_lock);
 761	}
 762	return mpol;
 763}
 764#endif /* CONFIG_TMPFS */
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 765
 766static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
 767			struct shmem_inode_info *info, pgoff_t index)
 768{
 769	struct mempolicy mpol, *spol;
 770	struct vm_area_struct pvma;
 
 771
 772	spol = mpol_cond_copy(&mpol,
 773			mpol_shared_policy_lookup(&info->policy, index));
 
 774
 775	/* Create a pseudo vma that just contains the policy */
 776	pvma.vm_start = 0;
 777	pvma.vm_pgoff = index;
 778	pvma.vm_ops = NULL;
 779	pvma.vm_policy = spol;
 780	return swapin_readahead(swap, gfp, &pvma, 0);
 781}
 782
 783static struct page *shmem_alloc_page(gfp_t gfp,
 784			struct shmem_inode_info *info, pgoff_t index)
 785{
 786	struct vm_area_struct pvma;
 
 
 
 
 
 787
 788	/* Create a pseudo vma that just contains the policy */
 789	pvma.vm_start = 0;
 790	pvma.vm_pgoff = index;
 791	pvma.vm_ops = NULL;
 792	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
 793
 794	/*
 795	 * alloc_page_vma() will drop the shared policy reference
 796	 */
 797	return alloc_page_vma(gfp, &pvma, 0);
 
 
 
 
 
 
 
 
 
 
 
 
 798}
 799#else /* !CONFIG_NUMA */
 800#ifdef CONFIG_TMPFS
 801static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
 802{
 
 
 
 
 
 
 
 
 803}
 804#endif /* CONFIG_TMPFS */
 805
 806static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
 807			struct shmem_inode_info *info, pgoff_t index)
 
 808{
 809	return swapin_readahead(swap, gfp, NULL, 0);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 810}
 811
 812static inline struct page *shmem_alloc_page(gfp_t gfp,
 813			struct shmem_inode_info *info, pgoff_t index)
 
 
 
 
 
 
 
 
 
 
 
 814{
 815	return alloc_page(gfp);
 816}
 817#endif /* CONFIG_NUMA */
 818
 819#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
 820static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
 821{
 822	return NULL;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 823}
 824#endif
 825
 826/*
 827 * shmem_getpage_gfp - find page in cache, or get from swap, or allocate
 828 *
 829 * If we allocate a new one we do not mark it dirty. That's up to the
 830 * vm. If we swap it in we mark it dirty since we also free the swap
 831 * entry since a page cannot live in both the swap and page cache
 
 
 
 832 */
 833static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 834	struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
 
 835{
 836	struct address_space *mapping = inode->i_mapping;
 837	struct shmem_inode_info *info;
 838	struct shmem_sb_info *sbinfo;
 
 
 839	struct page *page;
 840	swp_entry_t swap;
 
 
 841	int error;
 842	int once = 0;
 
 843
 844	if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
 845		return -EFBIG;
 
 
 846repeat:
 847	swap.val = 0;
 848	page = find_lock_page(mapping, index);
 849	if (radix_tree_exceptional_entry(page)) {
 850		swap = radix_to_swp_entry(page);
 851		page = NULL;
 852	}
 853
 854	if (sgp != SGP_WRITE &&
 855	    ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
 856		error = -EINVAL;
 857		goto failed;
 858	}
 859
 
 
 
 
 
 
 
 
 
 
 
 860	if (page || (sgp == SGP_READ && !swap.val)) {
 861		/*
 862		 * Once we can get the page lock, it must be uptodate:
 863		 * if there were an error in reading back from swap,
 864		 * the page would not be inserted into the filecache.
 865		 */
 866		BUG_ON(page && !PageUptodate(page));
 867		*pagep = page;
 868		return 0;
 869	}
 870
 871	/*
 872	 * Fast cache lookup did not find it:
 873	 * bring it back from swap or allocate.
 874	 */
 875	info = SHMEM_I(inode);
 876	sbinfo = SHMEM_SB(inode->i_sb);
 
 877
 878	if (swap.val) {
 879		/* Look it up and read it in.. */
 880		page = lookup_swap_cache(swap);
 881		if (!page) {
 882			/* here we actually do the io */
 883			if (fault_type)
 884				*fault_type |= VM_FAULT_MAJOR;
 
 
 
 
 885			page = shmem_swapin(swap, gfp, info, index);
 886			if (!page) {
 887				error = -ENOMEM;
 888				goto failed;
 889			}
 890		}
 891
 892		/* We have to do this with page locked to prevent races */
 893		lock_page(page);
 
 
 
 
 
 894		if (!PageUptodate(page)) {
 895			error = -EIO;
 896			goto failed;
 897		}
 898		wait_on_page_writeback(page);
 899
 900		/* Someone may have already done it for us */
 901		if (page->mapping) {
 902			if (page->mapping == mapping &&
 903			    page->index == index)
 904				goto done;
 905			error = -EEXIST;
 906			goto failed;
 907		}
 908
 909		error = mem_cgroup_cache_charge(page, current->mm,
 910						gfp & GFP_RECLAIM_MASK);
 911		if (!error)
 912			error = shmem_add_to_page_cache(page, mapping, index,
 913						gfp, swp_to_radix_entry(swap));
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 914		if (error)
 915			goto failed;
 916
 917		spin_lock(&info->lock);
 
 
 918		info->swapped--;
 919		shmem_recalc_inode(inode);
 920		spin_unlock(&info->lock);
 
 
 
 921
 922		delete_from_swap_cache(page);
 923		set_page_dirty(page);
 924		swap_free(swap);
 925
 926	} else {
 927		if (shmem_acct_block(info->flags)) {
 928			error = -ENOSPC;
 929			goto failed;
 930		}
 931		if (sbinfo->max_blocks) {
 932			if (percpu_counter_compare(&sbinfo->used_blocks,
 933						sbinfo->max_blocks) >= 0) {
 934				error = -ENOSPC;
 935				goto unacct;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 936			}
 937			percpu_counter_inc(&sbinfo->used_blocks);
 938		}
 939
 940		page = shmem_alloc_page(gfp, info, index);
 941		if (!page) {
 942			error = -ENOMEM;
 943			goto decused;
 944		}
 945
 946		SetPageSwapBacked(page);
 947		__set_page_locked(page);
 948		error = mem_cgroup_cache_charge(page, current->mm,
 949						gfp & GFP_RECLAIM_MASK);
 950		if (!error)
 951			error = shmem_add_to_page_cache(page, mapping, index,
 952						gfp, NULL);
 953		if (error)
 954			goto decused;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 955		lru_cache_add_anon(page);
 956
 957		spin_lock(&info->lock);
 958		info->alloced++;
 959		inode->i_blocks += BLOCKS_PER_PAGE;
 960		shmem_recalc_inode(inode);
 961		spin_unlock(&info->lock);
 
 962
 963		clear_highpage(page);
 964		flush_dcache_page(page);
 965		SetPageUptodate(page);
 966		if (sgp == SGP_DIRTY)
 967			set_page_dirty(page);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 968	}
 969done:
 970	/* Perhaps the file has been truncated since we checked */
 971	if (sgp != SGP_WRITE &&
 972	    ((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
 
 
 
 
 
 
 
 973		error = -EINVAL;
 974		goto trunc;
 975	}
 976	*pagep = page;
 977	return 0;
 978
 979	/*
 980	 * Error recovery.
 981	 */
 982trunc:
 983	ClearPageDirty(page);
 984	delete_from_page_cache(page);
 985	spin_lock(&info->lock);
 986	info->alloced--;
 987	inode->i_blocks -= BLOCKS_PER_PAGE;
 988	spin_unlock(&info->lock);
 989decused:
 990	if (sbinfo->max_blocks)
 991		percpu_counter_add(&sbinfo->used_blocks, -1);
 992unacct:
 993	shmem_unacct_blocks(info->flags, 1);
 994failed:
 995	if (swap.val && error != -EINVAL) {
 996		struct page *test = find_get_page(mapping, index);
 997		if (test && !radix_tree_exceptional_entry(test))
 998			page_cache_release(test);
 999		/* Have another try if the entry has changed */
1000		if (test != swp_to_radix_entry(swap))
1001			error = -EEXIST;
1002	}
 
 
 
 
1003	if (page) {
1004		unlock_page(page);
1005		page_cache_release(page);
1006	}
1007	if (error == -ENOSPC && !once++) {
1008		info = SHMEM_I(inode);
1009		spin_lock(&info->lock);
1010		shmem_recalc_inode(inode);
1011		spin_unlock(&info->lock);
1012		goto repeat;
1013	}
1014	if (error == -EEXIST)
1015		goto repeat;
1016	return error;
1017}
1018
 
 
 
 
 
 
 
 
 
 
 
 
1019static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
1020{
1021	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
 
 
1022	int error;
1023	int ret = VM_FAULT_LOCKED;
1024
1025	error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1026	if (error)
1027		return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
1028
1029	if (ret & VM_FAULT_MAJOR) {
1030		count_vm_event(PGMAJFAULT);
1031		mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
1032	}
1033	return ret;
1034}
1035
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1036#ifdef CONFIG_NUMA
1037static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
1038{
1039	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1040	return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
1041}
1042
1043static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
1044					  unsigned long addr)
1045{
1046	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
1047	pgoff_t index;
1048
1049	index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
1050	return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
1051}
1052#endif
1053
1054int shmem_lock(struct file *file, int lock, struct user_struct *user)
1055{
1056	struct inode *inode = file->f_path.dentry->d_inode;
1057	struct shmem_inode_info *info = SHMEM_I(inode);
1058	int retval = -ENOMEM;
1059
1060	spin_lock(&info->lock);
1061	if (lock && !(info->flags & VM_LOCKED)) {
1062		if (!user_shm_lock(inode->i_size, user))
1063			goto out_nomem;
1064		info->flags |= VM_LOCKED;
1065		mapping_set_unevictable(file->f_mapping);
1066	}
1067	if (!lock && (info->flags & VM_LOCKED) && user) {
1068		user_shm_unlock(inode->i_size, user);
1069		info->flags &= ~VM_LOCKED;
1070		mapping_clear_unevictable(file->f_mapping);
1071		scan_mapping_unevictable_pages(file->f_mapping);
1072	}
1073	retval = 0;
1074
1075out_nomem:
1076	spin_unlock(&info->lock);
1077	return retval;
1078}
1079
1080static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
1081{
1082	file_accessed(file);
1083	vma->vm_ops = &shmem_vm_ops;
1084	vma->vm_flags |= VM_CAN_NONLINEAR;
 
 
 
 
1085	return 0;
1086}
1087
1088static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
1089				     int mode, dev_t dev, unsigned long flags)
1090{
1091	struct inode *inode;
1092	struct shmem_inode_info *info;
1093	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
1094
1095	if (shmem_reserve_inode(sb))
1096		return NULL;
1097
1098	inode = new_inode(sb);
1099	if (inode) {
1100		inode->i_ino = get_next_ino();
1101		inode_init_owner(inode, dir, mode);
1102		inode->i_blocks = 0;
1103		inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
1104		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1105		inode->i_generation = get_seconds();
1106		info = SHMEM_I(inode);
1107		memset(info, 0, (char *)inode - (char *)info);
1108		spin_lock_init(&info->lock);
 
1109		info->flags = flags & VM_NORESERVE;
 
1110		INIT_LIST_HEAD(&info->swaplist);
1111		INIT_LIST_HEAD(&info->xattr_list);
1112		cache_no_acl(inode);
1113
1114		switch (mode & S_IFMT) {
1115		default:
1116			inode->i_op = &shmem_special_inode_operations;
1117			init_special_inode(inode, mode, dev);
1118			break;
1119		case S_IFREG:
1120			inode->i_mapping->a_ops = &shmem_aops;
1121			inode->i_op = &shmem_inode_operations;
1122			inode->i_fop = &shmem_file_operations;
1123			mpol_shared_policy_init(&info->policy,
1124						 shmem_get_sbmpol(sbinfo));
1125			break;
1126		case S_IFDIR:
1127			inc_nlink(inode);
1128			/* Some things misbehave if size == 0 on a directory */
1129			inode->i_size = 2 * BOGO_DIRENT_SIZE;
1130			inode->i_op = &shmem_dir_inode_operations;
1131			inode->i_fop = &simple_dir_operations;
1132			break;
1133		case S_IFLNK:
1134			/*
1135			 * Must not load anything in the rbtree,
1136			 * mpol_free_shared_policy will not be called.
1137			 */
1138			mpol_shared_policy_init(&info->policy, NULL);
1139			break;
1140		}
1141	} else
1142		shmem_free_inode(sb);
1143	return inode;
1144}
1145
 
 
 
 
 
 
 
 
1146#ifdef CONFIG_TMPFS
1147static const struct inode_operations shmem_symlink_inode_operations;
1148static const struct inode_operations shmem_short_symlink_operations;
1149
 
 
 
 
 
 
1150static int
1151shmem_write_begin(struct file *file, struct address_space *mapping,
1152			loff_t pos, unsigned len, unsigned flags,
1153			struct page **pagep, void **fsdata)
1154{
1155	struct inode *inode = mapping->host;
1156	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
1157	return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
 
 
 
 
 
 
 
 
 
 
1158}
1159
1160static int
1161shmem_write_end(struct file *file, struct address_space *mapping,
1162			loff_t pos, unsigned len, unsigned copied,
1163			struct page *page, void *fsdata)
1164{
1165	struct inode *inode = mapping->host;
1166
1167	if (pos + copied > inode->i_size)
1168		i_size_write(inode, pos + copied);
1169
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1170	set_page_dirty(page);
1171	unlock_page(page);
1172	page_cache_release(page);
1173
1174	return copied;
1175}
1176
1177static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
1178{
1179	struct inode *inode = filp->f_path.dentry->d_inode;
 
1180	struct address_space *mapping = inode->i_mapping;
1181	pgoff_t index;
1182	unsigned long offset;
1183	enum sgp_type sgp = SGP_READ;
 
 
 
1184
1185	/*
1186	 * Might this read be for a stacking filesystem?  Then when reading
1187	 * holes of a sparse file, we actually need to allocate those pages,
1188	 * and even mark them dirty, so it cannot exceed the max_blocks limit.
1189	 */
1190	if (segment_eq(get_fs(), KERNEL_DS))
1191		sgp = SGP_DIRTY;
1192
1193	index = *ppos >> PAGE_CACHE_SHIFT;
1194	offset = *ppos & ~PAGE_CACHE_MASK;
1195
1196	for (;;) {
1197		struct page *page = NULL;
1198		pgoff_t end_index;
1199		unsigned long nr, ret;
1200		loff_t i_size = i_size_read(inode);
1201
1202		end_index = i_size >> PAGE_CACHE_SHIFT;
1203		if (index > end_index)
1204			break;
1205		if (index == end_index) {
1206			nr = i_size & ~PAGE_CACHE_MASK;
1207			if (nr <= offset)
1208				break;
1209		}
1210
1211		desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
1212		if (desc->error) {
1213			if (desc->error == -EINVAL)
1214				desc->error = 0;
1215			break;
1216		}
1217		if (page)
 
 
1218			unlock_page(page);
 
1219
1220		/*
1221		 * We must evaluate after, since reads (unlike writes)
1222		 * are called without i_mutex protection against truncate
1223		 */
1224		nr = PAGE_CACHE_SIZE;
1225		i_size = i_size_read(inode);
1226		end_index = i_size >> PAGE_CACHE_SHIFT;
1227		if (index == end_index) {
1228			nr = i_size & ~PAGE_CACHE_MASK;
1229			if (nr <= offset) {
1230				if (page)
1231					page_cache_release(page);
1232				break;
1233			}
1234		}
1235		nr -= offset;
1236
1237		if (page) {
1238			/*
1239			 * If users can be writing to this page using arbitrary
1240			 * virtual addresses, take care about potential aliasing
1241			 * before reading the page on the kernel side.
1242			 */
1243			if (mapping_writably_mapped(mapping))
1244				flush_dcache_page(page);
1245			/*
1246			 * Mark the page accessed if we read the beginning.
1247			 */
1248			if (!offset)
1249				mark_page_accessed(page);
1250		} else {
1251			page = ZERO_PAGE(0);
1252			page_cache_get(page);
1253		}
1254
1255		/*
1256		 * Ok, we have the page, and it's up-to-date, so
1257		 * now we can copy it to user space...
1258		 *
1259		 * The actor routine returns how many bytes were actually used..
1260		 * NOTE! This may not be the same as how much of a user buffer
1261		 * we filled up (we may be padding etc), so we can only update
1262		 * "pos" here (the actor routine has to update the user buffer
1263		 * pointers and the remaining count).
1264		 */
1265		ret = actor(desc, page, offset, nr);
 
1266		offset += ret;
1267		index += offset >> PAGE_CACHE_SHIFT;
1268		offset &= ~PAGE_CACHE_MASK;
1269
1270		page_cache_release(page);
1271		if (ret != nr || !desc->count)
1272			break;
1273
 
 
 
1274		cond_resched();
1275	}
1276
1277	*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
1278	file_accessed(filp);
 
1279}
1280
1281static ssize_t shmem_file_aio_read(struct kiocb *iocb,
1282		const struct iovec *iov, unsigned long nr_segs, loff_t pos)
 
 
 
1283{
1284	struct file *filp = iocb->ki_filp;
1285	ssize_t retval;
1286	unsigned long seg;
1287	size_t count;
1288	loff_t *ppos = &iocb->ki_pos;
1289
1290	retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
1291	if (retval)
1292		return retval;
1293
1294	for (seg = 0; seg < nr_segs; seg++) {
1295		read_descriptor_t desc;
1296
1297		desc.written = 0;
1298		desc.arg.buf = iov[seg].iov_base;
1299		desc.count = iov[seg].iov_len;
1300		if (desc.count == 0)
1301			continue;
1302		desc.error = 0;
1303		do_shmem_file_read(filp, ppos, &desc, file_read_actor);
1304		retval += desc.written;
1305		if (desc.error) {
1306			retval = retval ?: desc.error;
1307			break;
1308		}
1309		if (desc.count > 0)
1310			break;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1311	}
1312	return retval;
1313}
1314
1315static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
1316				struct pipe_inode_info *pipe, size_t len,
1317				unsigned int flags)
1318{
1319	struct address_space *mapping = in->f_mapping;
1320	struct inode *inode = mapping->host;
1321	unsigned int loff, nr_pages, req_pages;
1322	struct page *pages[PIPE_DEF_BUFFERS];
1323	struct partial_page partial[PIPE_DEF_BUFFERS];
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1324	struct page *page;
1325	pgoff_t index, end_index;
1326	loff_t isize, left;
1327	int error, page_nr;
1328	struct splice_pipe_desc spd = {
1329		.pages = pages,
1330		.partial = partial,
1331		.flags = flags,
1332		.ops = &page_cache_pipe_buf_ops,
1333		.spd_release = spd_release_page,
1334	};
1335
1336	isize = i_size_read(inode);
1337	if (unlikely(*ppos >= isize))
1338		return 0;
1339
1340	left = isize - *ppos;
1341	if (unlikely(left < len))
1342		len = left;
 
 
 
 
 
 
 
 
 
 
1343
1344	if (splice_grow_spd(pipe, &spd))
1345		return -ENOMEM;
 
 
 
 
 
1346
1347	index = *ppos >> PAGE_CACHE_SHIFT;
1348	loff = *ppos & ~PAGE_CACHE_MASK;
1349	req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
1350	nr_pages = min(req_pages, pipe->buffers);
1351
1352	spd.nr_pages = find_get_pages_contig(mapping, index,
1353						nr_pages, spd.pages);
1354	index += spd.nr_pages;
1355	error = 0;
 
 
 
 
 
 
 
1356
1357	while (spd.nr_pages < nr_pages) {
1358		error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
1359		if (error)
 
 
1360			break;
1361		unlock_page(page);
1362		spd.pages[spd.nr_pages++] = page;
1363		index++;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1364	}
1365
1366	index = *ppos >> PAGE_CACHE_SHIFT;
1367	nr_pages = spd.nr_pages;
1368	spd.nr_pages = 0;
 
 
 
 
1369
1370	for (page_nr = 0; page_nr < nr_pages; page_nr++) {
1371		unsigned int this_len;
 
 
 
1372
1373		if (!len)
1374			break;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1375
1376		this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
1377		page = spd.pages[page_nr];
 
 
 
 
 
 
 
 
 
 
 
1378
1379		if (!PageUptodate(page) || page->mapping != mapping) {
1380			error = shmem_getpage(inode, index, &page,
1381							SGP_CACHE, NULL);
1382			if (error)
1383				break;
1384			unlock_page(page);
1385			page_cache_release(spd.pages[page_nr]);
1386			spd.pages[page_nr] = page;
 
1387		}
 
1388
1389		isize = i_size_read(inode);
1390		end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
1391		if (unlikely(!isize || index > end_index))
1392			break;
1393
1394		if (end_index == index) {
1395			unsigned int plen;
 
 
 
1396
1397			plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
1398			if (plen <= loff)
1399				break;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1400
1401			this_len = min(this_len, plen - loff);
1402			len = this_len;
 
 
 
 
 
 
 
 
1403		}
1404
1405		spd.partial[page_nr].offset = loff;
1406		spd.partial[page_nr].len = this_len;
1407		len -= this_len;
1408		loff = 0;
1409		spd.nr_pages++;
1410		index++;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1411	}
1412
1413	while (page_nr < nr_pages)
1414		page_cache_release(spd.pages[page_nr++]);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1415
1416	if (spd.nr_pages)
1417		error = splice_to_pipe(pipe, &spd);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1418
1419	splice_shrink_spd(pipe, &spd);
 
 
 
 
 
 
1420
1421	if (error > 0) {
1422		*ppos += error;
1423		file_accessed(in);
 
 
 
 
 
 
 
 
1424	}
 
 
 
 
 
 
 
 
 
 
1425	return error;
1426}
1427
1428static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
1429{
1430	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
1431
1432	buf->f_type = TMPFS_MAGIC;
1433	buf->f_bsize = PAGE_CACHE_SIZE;
1434	buf->f_namelen = NAME_MAX;
1435	if (sbinfo->max_blocks) {
1436		buf->f_blocks = sbinfo->max_blocks;
1437		buf->f_bavail =
1438		buf->f_bfree  = sbinfo->max_blocks -
1439				percpu_counter_sum(&sbinfo->used_blocks);
1440	}
1441	if (sbinfo->max_inodes) {
1442		buf->f_files = sbinfo->max_inodes;
1443		buf->f_ffree = sbinfo->free_inodes;
1444	}
1445	/* else leave those fields 0 like simple_statfs */
1446	return 0;
1447}
1448
1449/*
1450 * File creation. Allocate an inode, and we're done..
1451 */
1452static int
1453shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
1454{
1455	struct inode *inode;
1456	int error = -ENOSPC;
1457
1458	inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
1459	if (inode) {
 
 
 
1460		error = security_inode_init_security(inode, dir,
1461						     &dentry->d_name, NULL,
1462						     NULL, NULL);
1463		if (error) {
1464			if (error != -EOPNOTSUPP) {
1465				iput(inode);
1466				return error;
1467			}
1468		}
1469#ifdef CONFIG_TMPFS_POSIX_ACL
1470		error = generic_acl_init(inode, dir);
1471		if (error) {
1472			iput(inode);
1473			return error;
1474		}
1475#else
1476		error = 0;
1477#endif
1478		dir->i_size += BOGO_DIRENT_SIZE;
1479		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1480		d_instantiate(dentry, inode);
1481		dget(dentry); /* Extra count - pin the dentry in core */
1482	}
1483	return error;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1484}
1485
1486static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
1487{
1488	int error;
1489
1490	if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
1491		return error;
1492	inc_nlink(dir);
1493	return 0;
1494}
1495
1496static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
1497		struct nameidata *nd)
1498{
1499	return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
1500}
1501
1502/*
1503 * Link a file..
1504 */
1505static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
1506{
1507	struct inode *inode = old_dentry->d_inode;
1508	int ret;
1509
1510	/*
1511	 * No ordinary (disk based) filesystem counts links as inodes;
1512	 * but each new link needs a new dentry, pinning lowmem, and
1513	 * tmpfs dentries cannot be pruned until they are unlinked.
1514	 */
1515	ret = shmem_reserve_inode(inode->i_sb);
1516	if (ret)
1517		goto out;
1518
1519	dir->i_size += BOGO_DIRENT_SIZE;
1520	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1521	inc_nlink(inode);
1522	ihold(inode);	/* New dentry reference */
1523	dget(dentry);		/* Extra pinning count for the created dentry */
1524	d_instantiate(dentry, inode);
1525out:
1526	return ret;
1527}
1528
1529static int shmem_unlink(struct inode *dir, struct dentry *dentry)
1530{
1531	struct inode *inode = dentry->d_inode;
1532
1533	if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
1534		shmem_free_inode(inode->i_sb);
1535
1536	dir->i_size -= BOGO_DIRENT_SIZE;
1537	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1538	drop_nlink(inode);
1539	dput(dentry);	/* Undo the count from "create" - this does all the work */
1540	return 0;
1541}
1542
1543static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
1544{
1545	if (!simple_empty(dentry))
1546		return -ENOTEMPTY;
1547
1548	drop_nlink(dentry->d_inode);
1549	drop_nlink(dir);
1550	return shmem_unlink(dir, dentry);
1551}
1552
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1553/*
1554 * The VFS layer already does all the dentry stuff for rename,
1555 * we just have to decrement the usage count for the target if
1556 * it exists so that the VFS layer correctly free's it when it
1557 * gets overwritten.
1558 */
1559static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
1560{
1561	struct inode *inode = old_dentry->d_inode;
1562	int they_are_dirs = S_ISDIR(inode->i_mode);
1563
 
 
 
 
 
 
1564	if (!simple_empty(new_dentry))
1565		return -ENOTEMPTY;
1566
1567	if (new_dentry->d_inode) {
 
 
 
 
 
 
 
 
1568		(void) shmem_unlink(new_dir, new_dentry);
1569		if (they_are_dirs)
 
1570			drop_nlink(old_dir);
 
1571	} else if (they_are_dirs) {
1572		drop_nlink(old_dir);
1573		inc_nlink(new_dir);
1574	}
1575
1576	old_dir->i_size -= BOGO_DIRENT_SIZE;
1577	new_dir->i_size += BOGO_DIRENT_SIZE;
1578	old_dir->i_ctime = old_dir->i_mtime =
1579	new_dir->i_ctime = new_dir->i_mtime =
1580	inode->i_ctime = CURRENT_TIME;
1581	return 0;
1582}
1583
1584static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
1585{
1586	int error;
1587	int len;
1588	struct inode *inode;
1589	struct page *page;
1590	char *kaddr;
1591	struct shmem_inode_info *info;
1592
1593	len = strlen(symname) + 1;
1594	if (len > PAGE_CACHE_SIZE)
1595		return -ENAMETOOLONG;
1596
1597	inode = shmem_get_inode(dir->i_sb, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
1598	if (!inode)
1599		return -ENOSPC;
1600
1601	error = security_inode_init_security(inode, dir, &dentry->d_name, NULL,
1602					     NULL, NULL);
1603	if (error) {
1604		if (error != -EOPNOTSUPP) {
1605			iput(inode);
1606			return error;
1607		}
1608		error = 0;
1609	}
1610
1611	info = SHMEM_I(inode);
1612	inode->i_size = len-1;
1613	if (len <= SHORT_SYMLINK_LEN) {
1614		info->symlink = kmemdup(symname, len, GFP_KERNEL);
1615		if (!info->symlink) {
1616			iput(inode);
1617			return -ENOMEM;
1618		}
1619		inode->i_op = &shmem_short_symlink_operations;
1620	} else {
1621		error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
 
1622		if (error) {
1623			iput(inode);
1624			return error;
1625		}
1626		inode->i_mapping->a_ops = &shmem_aops;
1627		inode->i_op = &shmem_symlink_inode_operations;
1628		kaddr = kmap_atomic(page, KM_USER0);
1629		memcpy(kaddr, symname, len);
1630		kunmap_atomic(kaddr, KM_USER0);
1631		set_page_dirty(page);
1632		unlock_page(page);
1633		page_cache_release(page);
1634	}
1635	dir->i_size += BOGO_DIRENT_SIZE;
1636	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1637	d_instantiate(dentry, inode);
1638	dget(dentry);
1639	return 0;
1640}
1641
1642static void *shmem_follow_short_symlink(struct dentry *dentry, struct nameidata *nd)
1643{
1644	nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink);
1645	return NULL;
1646}
1647
1648static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
 
 
1649{
1650	struct page *page = NULL;
1651	int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
1652	nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
1653	if (page)
 
 
 
 
 
 
 
 
 
 
1654		unlock_page(page);
1655	return page;
1656}
1657
1658static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
1659{
1660	if (!IS_ERR(nd_get_link(nd))) {
1661		struct page *page = cookie;
1662		kunmap(page);
1663		mark_page_accessed(page);
1664		page_cache_release(page);
1665	}
 
 
1666}
1667
1668#ifdef CONFIG_TMPFS_XATTR
1669/*
1670 * Superblocks without xattr inode operations may get some security.* xattr
1671 * support from the LSM "for free". As soon as we have any other xattrs
1672 * like ACLs, we also need to implement the security.* handlers at
1673 * filesystem level, though.
1674 */
1675
1676static int shmem_xattr_get(struct dentry *dentry, const char *name,
1677			   void *buffer, size_t size)
1678{
1679	struct shmem_inode_info *info;
1680	struct shmem_xattr *xattr;
1681	int ret = -ENODATA;
1682
1683	info = SHMEM_I(dentry->d_inode);
1684
1685	spin_lock(&info->lock);
1686	list_for_each_entry(xattr, &info->xattr_list, list) {
1687		if (strcmp(name, xattr->name))
1688			continue;
1689
1690		ret = xattr->size;
1691		if (buffer) {
1692			if (size < xattr->size)
1693				ret = -ERANGE;
1694			else
1695				memcpy(buffer, xattr->value, xattr->size);
1696		}
1697		break;
1698	}
1699	spin_unlock(&info->lock);
1700	return ret;
1701}
1702
1703static int shmem_xattr_set(struct dentry *dentry, const char *name,
1704			   const void *value, size_t size, int flags)
1705{
1706	struct inode *inode = dentry->d_inode;
1707	struct shmem_inode_info *info = SHMEM_I(inode);
1708	struct shmem_xattr *xattr;
1709	struct shmem_xattr *new_xattr = NULL;
1710	size_t len;
1711	int err = 0;
1712
1713	/* value == NULL means remove */
1714	if (value) {
1715		/* wrap around? */
1716		len = sizeof(*new_xattr) + size;
1717		if (len <= sizeof(*new_xattr))
1718			return -ENOMEM;
1719
1720		new_xattr = kmalloc(len, GFP_KERNEL);
1721		if (!new_xattr)
1722			return -ENOMEM;
1723
1724		new_xattr->name = kstrdup(name, GFP_KERNEL);
 
 
1725		if (!new_xattr->name) {
1726			kfree(new_xattr);
1727			return -ENOMEM;
1728		}
1729
1730		new_xattr->size = size;
1731		memcpy(new_xattr->value, value, size);
1732	}
 
1733
1734	spin_lock(&info->lock);
1735	list_for_each_entry(xattr, &info->xattr_list, list) {
1736		if (!strcmp(name, xattr->name)) {
1737			if (flags & XATTR_CREATE) {
1738				xattr = new_xattr;
1739				err = -EEXIST;
1740			} else if (new_xattr) {
1741				list_replace(&xattr->list, &new_xattr->list);
1742			} else {
1743				list_del(&xattr->list);
1744			}
1745			goto out;
1746		}
1747	}
1748	if (flags & XATTR_REPLACE) {
1749		xattr = new_xattr;
1750		err = -ENODATA;
1751	} else {
1752		list_add(&new_xattr->list, &info->xattr_list);
1753		xattr = NULL;
1754	}
1755out:
1756	spin_unlock(&info->lock);
1757	if (xattr)
1758		kfree(xattr->name);
1759	kfree(xattr);
1760	return err;
1761}
1762
1763static const struct xattr_handler *shmem_xattr_handlers[] = {
1764#ifdef CONFIG_TMPFS_POSIX_ACL
1765	&generic_acl_access_handler,
1766	&generic_acl_default_handler,
1767#endif
1768	NULL
1769};
1770
1771static int shmem_xattr_validate(const char *name)
1772{
1773	struct { const char *prefix; size_t len; } arr[] = {
1774		{ XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
1775		{ XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
1776	};
1777	int i;
1778
1779	for (i = 0; i < ARRAY_SIZE(arr); i++) {
1780		size_t preflen = arr[i].len;
1781		if (strncmp(name, arr[i].prefix, preflen) == 0) {
1782			if (!name[preflen])
1783				return -EINVAL;
1784			return 0;
1785		}
1786	}
1787	return -EOPNOTSUPP;
1788}
1789
1790static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
1791			      void *buffer, size_t size)
 
1792{
1793	int err;
1794
1795	/*
1796	 * If this is a request for a synthetic attribute in the system.*
1797	 * namespace use the generic infrastructure to resolve a handler
1798	 * for it via sb->s_xattr.
1799	 */
1800	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
1801		return generic_getxattr(dentry, name, buffer, size);
1802
1803	err = shmem_xattr_validate(name);
1804	if (err)
1805		return err;
1806
1807	return shmem_xattr_get(dentry, name, buffer, size);
 
1808}
1809
1810static int shmem_setxattr(struct dentry *dentry, const char *name,
1811			  const void *value, size_t size, int flags)
 
 
1812{
1813	int err;
1814
1815	/*
1816	 * If this is a request for a synthetic attribute in the system.*
1817	 * namespace use the generic infrastructure to resolve a handler
1818	 * for it via sb->s_xattr.
1819	 */
1820	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
1821		return generic_setxattr(dentry, name, value, size, flags);
1822
1823	err = shmem_xattr_validate(name);
1824	if (err)
1825		return err;
1826
1827	if (size == 0)
1828		value = "";  /* empty EA, do not remove */
1829
1830	return shmem_xattr_set(dentry, name, value, size, flags);
1831
 
 
1832}
1833
1834static int shmem_removexattr(struct dentry *dentry, const char *name)
1835{
1836	int err;
1837
1838	/*
1839	 * If this is a request for a synthetic attribute in the system.*
1840	 * namespace use the generic infrastructure to resolve a handler
1841	 * for it via sb->s_xattr.
1842	 */
1843	if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
1844		return generic_removexattr(dentry, name);
1845
1846	err = shmem_xattr_validate(name);
1847	if (err)
1848		return err;
1849
1850	return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
1851}
 
 
 
1852
1853static bool xattr_is_trusted(const char *name)
1854{
1855	return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
1856}
 
 
 
 
 
1857
1858static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
1859{
1860	bool trusted = capable(CAP_SYS_ADMIN);
1861	struct shmem_xattr *xattr;
1862	struct shmem_inode_info *info;
1863	size_t used = 0;
1864
1865	info = SHMEM_I(dentry->d_inode);
1866
1867	spin_lock(&info->lock);
1868	list_for_each_entry(xattr, &info->xattr_list, list) {
1869		size_t len;
1870
1871		/* skip "trusted." attributes for unprivileged callers */
1872		if (!trusted && xattr_is_trusted(xattr->name))
1873			continue;
1874
1875		len = strlen(xattr->name) + 1;
1876		used += len;
1877		if (buffer) {
1878			if (size < used) {
1879				used = -ERANGE;
1880				break;
1881			}
1882			memcpy(buffer, xattr->name, len);
1883			buffer += len;
1884		}
1885	}
1886	spin_unlock(&info->lock);
1887
1888	return used;
1889}
1890#endif /* CONFIG_TMPFS_XATTR */
1891
1892static const struct inode_operations shmem_short_symlink_operations = {
1893	.readlink	= generic_readlink,
1894	.follow_link	= shmem_follow_short_symlink,
1895#ifdef CONFIG_TMPFS_XATTR
1896	.setxattr	= shmem_setxattr,
1897	.getxattr	= shmem_getxattr,
1898	.listxattr	= shmem_listxattr,
1899	.removexattr	= shmem_removexattr,
1900#endif
1901};
1902
1903static const struct inode_operations shmem_symlink_inode_operations = {
1904	.readlink	= generic_readlink,
1905	.follow_link	= shmem_follow_link,
1906	.put_link	= shmem_put_link,
1907#ifdef CONFIG_TMPFS_XATTR
1908	.setxattr	= shmem_setxattr,
1909	.getxattr	= shmem_getxattr,
1910	.listxattr	= shmem_listxattr,
1911	.removexattr	= shmem_removexattr,
1912#endif
1913};
1914
1915static struct dentry *shmem_get_parent(struct dentry *child)
1916{
1917	return ERR_PTR(-ESTALE);
1918}
1919
1920static int shmem_match(struct inode *ino, void *vfh)
1921{
1922	__u32 *fh = vfh;
1923	__u64 inum = fh[2];
1924	inum = (inum << 32) | fh[1];
1925	return ino->i_ino == inum && fh[0] == ino->i_generation;
1926}
1927
1928static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
1929		struct fid *fid, int fh_len, int fh_type)
1930{
1931	struct inode *inode;
1932	struct dentry *dentry = NULL;
1933	u64 inum = fid->raw[2];
1934	inum = (inum << 32) | fid->raw[1];
1935
1936	if (fh_len < 3)
1937		return NULL;
1938
 
 
 
1939	inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
1940			shmem_match, fid->raw);
1941	if (inode) {
1942		dentry = d_find_alias(inode);
1943		iput(inode);
1944	}
1945
1946	return dentry;
1947}
1948
1949static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
1950				int connectable)
1951{
1952	struct inode *inode = dentry->d_inode;
1953
1954	if (*len < 3) {
1955		*len = 3;
1956		return 255;
1957	}
1958
1959	if (inode_unhashed(inode)) {
1960		/* Unfortunately insert_inode_hash is not idempotent,
1961		 * so as we hash inodes here rather than at creation
1962		 * time, we need a lock to ensure we only try
1963		 * to do it once
1964		 */
1965		static DEFINE_SPINLOCK(lock);
1966		spin_lock(&lock);
1967		if (inode_unhashed(inode))
1968			__insert_inode_hash(inode,
1969					    inode->i_ino + inode->i_generation);
1970		spin_unlock(&lock);
1971	}
1972
1973	fh[0] = inode->i_generation;
1974	fh[1] = inode->i_ino;
1975	fh[2] = ((__u64)inode->i_ino) >> 32;
1976
1977	*len = 3;
1978	return 1;
1979}
1980
1981static const struct export_operations shmem_export_ops = {
1982	.get_parent     = shmem_get_parent,
1983	.encode_fh      = shmem_encode_fh,
1984	.fh_to_dentry	= shmem_fh_to_dentry,
1985};
1986
1987static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
1988			       bool remount)
1989{
1990	char *this_char, *value, *rest;
 
 
 
1991
1992	while (options != NULL) {
1993		this_char = options;
1994		for (;;) {
1995			/*
1996			 * NUL-terminate this option: unfortunately,
1997			 * mount options form a comma-separated list,
1998			 * but mpol's nodelist may also contain commas.
1999			 */
2000			options = strchr(options, ',');
2001			if (options == NULL)
2002				break;
2003			options++;
2004			if (!isdigit(*options)) {
2005				options[-1] = '\0';
2006				break;
2007			}
2008		}
2009		if (!*this_char)
2010			continue;
2011		if ((value = strchr(this_char,'=')) != NULL) {
2012			*value++ = 0;
2013		} else {
2014			printk(KERN_ERR
2015			    "tmpfs: No value for mount option '%s'\n",
2016			    this_char);
2017			return 1;
2018		}
2019
2020		if (!strcmp(this_char,"size")) {
2021			unsigned long long size;
2022			size = memparse(value,&rest);
2023			if (*rest == '%') {
2024				size <<= PAGE_SHIFT;
2025				size *= totalram_pages;
2026				do_div(size, 100);
2027				rest++;
2028			}
2029			if (*rest)
2030				goto bad_val;
2031			sbinfo->max_blocks =
2032				DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
2033		} else if (!strcmp(this_char,"nr_blocks")) {
2034			sbinfo->max_blocks = memparse(value, &rest);
2035			if (*rest)
2036				goto bad_val;
2037		} else if (!strcmp(this_char,"nr_inodes")) {
2038			sbinfo->max_inodes = memparse(value, &rest);
2039			if (*rest)
2040				goto bad_val;
2041		} else if (!strcmp(this_char,"mode")) {
2042			if (remount)
2043				continue;
2044			sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
2045			if (*rest)
2046				goto bad_val;
2047		} else if (!strcmp(this_char,"uid")) {
2048			if (remount)
2049				continue;
2050			sbinfo->uid = simple_strtoul(value, &rest, 0);
2051			if (*rest)
2052				goto bad_val;
 
 
 
2053		} else if (!strcmp(this_char,"gid")) {
2054			if (remount)
2055				continue;
2056			sbinfo->gid = simple_strtoul(value, &rest, 0);
2057			if (*rest)
2058				goto bad_val;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2059		} else if (!strcmp(this_char,"mpol")) {
2060			if (mpol_parse_str(value, &sbinfo->mpol, 1))
 
 
2061				goto bad_val;
 
2062		} else {
2063			printk(KERN_ERR "tmpfs: Bad mount option %s\n",
2064			       this_char);
2065			return 1;
2066		}
2067	}
 
2068	return 0;
2069
2070bad_val:
2071	printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
2072	       value, this_char);
 
 
2073	return 1;
2074
2075}
2076
2077static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
2078{
2079	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2080	struct shmem_sb_info config = *sbinfo;
2081	unsigned long inodes;
2082	int error = -EINVAL;
2083
 
2084	if (shmem_parse_options(data, &config, true))
2085		return error;
2086
2087	spin_lock(&sbinfo->stat_lock);
2088	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2089	if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
2090		goto out;
2091	if (config.max_inodes < inodes)
2092		goto out;
2093	/*
2094	 * Those tests disallow limited->unlimited while any are in use;
2095	 * but we must separately disallow unlimited->limited, because
2096	 * in that case we have no record of how much is already in use.
2097	 */
2098	if (config.max_blocks && !sbinfo->max_blocks)
2099		goto out;
2100	if (config.max_inodes && !sbinfo->max_inodes)
2101		goto out;
2102
2103	error = 0;
 
2104	sbinfo->max_blocks  = config.max_blocks;
2105	sbinfo->max_inodes  = config.max_inodes;
2106	sbinfo->free_inodes = config.max_inodes - inodes;
2107
2108	mpol_put(sbinfo->mpol);
2109	sbinfo->mpol        = config.mpol;	/* transfers initial ref */
 
 
 
 
 
2110out:
2111	spin_unlock(&sbinfo->stat_lock);
2112	return error;
2113}
2114
2115static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
2116{
2117	struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);
2118
2119	if (sbinfo->max_blocks != shmem_default_max_blocks())
2120		seq_printf(seq, ",size=%luk",
2121			sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
2122	if (sbinfo->max_inodes != shmem_default_max_inodes())
2123		seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
2124	if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
2125		seq_printf(seq, ",mode=%03o", sbinfo->mode);
2126	if (sbinfo->uid != 0)
2127		seq_printf(seq, ",uid=%u", sbinfo->uid);
2128	if (sbinfo->gid != 0)
2129		seq_printf(seq, ",gid=%u", sbinfo->gid);
 
 
 
 
 
 
 
2130	shmem_show_mpol(seq, sbinfo->mpol);
2131	return 0;
2132}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2133#endif /* CONFIG_TMPFS */
2134
2135static void shmem_put_super(struct super_block *sb)
2136{
2137	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2138
2139	percpu_counter_destroy(&sbinfo->used_blocks);
 
2140	kfree(sbinfo);
2141	sb->s_fs_info = NULL;
2142}
2143
2144int shmem_fill_super(struct super_block *sb, void *data, int silent)
2145{
2146	struct inode *inode;
2147	struct dentry *root;
2148	struct shmem_sb_info *sbinfo;
2149	int err = -ENOMEM;
2150
2151	/* Round up to L1_CACHE_BYTES to resist false sharing */
2152	sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2153				L1_CACHE_BYTES), GFP_KERNEL);
2154	if (!sbinfo)
2155		return -ENOMEM;
2156
2157	sbinfo->mode = S_IRWXUGO | S_ISVTX;
2158	sbinfo->uid = current_fsuid();
2159	sbinfo->gid = current_fsgid();
2160	sb->s_fs_info = sbinfo;
2161
2162#ifdef CONFIG_TMPFS
2163	/*
2164	 * Per default we only allow half of the physical ram per
2165	 * tmpfs instance, limiting inodes to one per page of lowmem;
2166	 * but the internal instance is left unlimited.
2167	 */
2168	if (!(sb->s_flags & MS_NOUSER)) {
2169		sbinfo->max_blocks = shmem_default_max_blocks();
2170		sbinfo->max_inodes = shmem_default_max_inodes();
2171		if (shmem_parse_options(data, sbinfo, false)) {
2172			err = -EINVAL;
2173			goto failed;
2174		}
 
 
2175	}
2176	sb->s_export_op = &shmem_export_ops;
 
2177#else
2178	sb->s_flags |= MS_NOUSER;
2179#endif
2180
2181	spin_lock_init(&sbinfo->stat_lock);
2182	if (percpu_counter_init(&sbinfo->used_blocks, 0))
2183		goto failed;
2184	sbinfo->free_inodes = sbinfo->max_inodes;
 
 
2185
2186	sb->s_maxbytes = MAX_LFS_FILESIZE;
2187	sb->s_blocksize = PAGE_CACHE_SIZE;
2188	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
2189	sb->s_magic = TMPFS_MAGIC;
2190	sb->s_op = &shmem_ops;
2191	sb->s_time_gran = 1;
2192#ifdef CONFIG_TMPFS_XATTR
2193	sb->s_xattr = shmem_xattr_handlers;
2194#endif
2195#ifdef CONFIG_TMPFS_POSIX_ACL
2196	sb->s_flags |= MS_POSIXACL;
2197#endif
2198
2199	inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
2200	if (!inode)
2201		goto failed;
2202	inode->i_uid = sbinfo->uid;
2203	inode->i_gid = sbinfo->gid;
2204	root = d_alloc_root(inode);
2205	if (!root)
2206		goto failed_iput;
2207	sb->s_root = root;
2208	return 0;
2209
2210failed_iput:
2211	iput(inode);
2212failed:
2213	shmem_put_super(sb);
2214	return err;
2215}
2216
2217static struct kmem_cache *shmem_inode_cachep;
2218
2219static struct inode *shmem_alloc_inode(struct super_block *sb)
2220{
2221	struct shmem_inode_info *info;
2222	info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
2223	if (!info)
2224		return NULL;
2225	return &info->vfs_inode;
2226}
2227
2228static void shmem_destroy_callback(struct rcu_head *head)
2229{
2230	struct inode *inode = container_of(head, struct inode, i_rcu);
2231	INIT_LIST_HEAD(&inode->i_dentry);
 
2232	kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
2233}
2234
2235static void shmem_destroy_inode(struct inode *inode)
2236{
2237	if ((inode->i_mode & S_IFMT) == S_IFREG)
2238		mpol_free_shared_policy(&SHMEM_I(inode)->policy);
2239	call_rcu(&inode->i_rcu, shmem_destroy_callback);
2240}
2241
2242static void shmem_init_inode(void *foo)
2243{
2244	struct shmem_inode_info *info = foo;
2245	inode_init_once(&info->vfs_inode);
2246}
2247
2248static int shmem_init_inodecache(void)
2249{
2250	shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
2251				sizeof(struct shmem_inode_info),
2252				0, SLAB_PANIC, shmem_init_inode);
2253	return 0;
2254}
2255
2256static void shmem_destroy_inodecache(void)
2257{
2258	kmem_cache_destroy(shmem_inode_cachep);
2259}
2260
2261static const struct address_space_operations shmem_aops = {
2262	.writepage	= shmem_writepage,
2263	.set_page_dirty	= __set_page_dirty_no_writeback,
2264#ifdef CONFIG_TMPFS
2265	.write_begin	= shmem_write_begin,
2266	.write_end	= shmem_write_end,
2267#endif
 
2268	.migratepage	= migrate_page,
 
2269	.error_remove_page = generic_error_remove_page,
2270};
2271
2272static const struct file_operations shmem_file_operations = {
2273	.mmap		= shmem_mmap,
 
2274#ifdef CONFIG_TMPFS
2275	.llseek		= generic_file_llseek,
2276	.read		= do_sync_read,
2277	.write		= do_sync_write,
2278	.aio_read	= shmem_file_aio_read,
2279	.aio_write	= generic_file_aio_write,
2280	.fsync		= noop_fsync,
2281	.splice_read	= shmem_file_splice_read,
2282	.splice_write	= generic_file_splice_write,
 
2283#endif
2284};
2285
2286static const struct inode_operations shmem_inode_operations = {
 
2287	.setattr	= shmem_setattr,
2288	.truncate_range	= shmem_truncate_range,
2289#ifdef CONFIG_TMPFS_XATTR
2290	.setxattr	= shmem_setxattr,
2291	.getxattr	= shmem_getxattr,
2292	.listxattr	= shmem_listxattr,
2293	.removexattr	= shmem_removexattr,
2294#endif
2295};
2296
2297static const struct inode_operations shmem_dir_inode_operations = {
2298#ifdef CONFIG_TMPFS
2299	.create		= shmem_create,
2300	.lookup		= simple_lookup,
2301	.link		= shmem_link,
2302	.unlink		= shmem_unlink,
2303	.symlink	= shmem_symlink,
2304	.mkdir		= shmem_mkdir,
2305	.rmdir		= shmem_rmdir,
2306	.mknod		= shmem_mknod,
2307	.rename		= shmem_rename,
 
2308#endif
2309#ifdef CONFIG_TMPFS_XATTR
2310	.setxattr	= shmem_setxattr,
2311	.getxattr	= shmem_getxattr,
2312	.listxattr	= shmem_listxattr,
2313	.removexattr	= shmem_removexattr,
2314#endif
2315#ifdef CONFIG_TMPFS_POSIX_ACL
2316	.setattr	= shmem_setattr,
 
2317#endif
2318};
2319
2320static const struct inode_operations shmem_special_inode_operations = {
2321#ifdef CONFIG_TMPFS_XATTR
2322	.setxattr	= shmem_setxattr,
2323	.getxattr	= shmem_getxattr,
2324	.listxattr	= shmem_listxattr,
2325	.removexattr	= shmem_removexattr,
2326#endif
2327#ifdef CONFIG_TMPFS_POSIX_ACL
2328	.setattr	= shmem_setattr,
 
2329#endif
2330};
2331
2332static const struct super_operations shmem_ops = {
2333	.alloc_inode	= shmem_alloc_inode,
2334	.destroy_inode	= shmem_destroy_inode,
2335#ifdef CONFIG_TMPFS
2336	.statfs		= shmem_statfs,
2337	.remount_fs	= shmem_remount_fs,
2338	.show_options	= shmem_show_options,
2339#endif
2340	.evict_inode	= shmem_evict_inode,
2341	.drop_inode	= generic_delete_inode,
2342	.put_super	= shmem_put_super,
 
 
 
 
2343};
2344
2345static const struct vm_operations_struct shmem_vm_ops = {
2346	.fault		= shmem_fault,
 
2347#ifdef CONFIG_NUMA
2348	.set_policy     = shmem_set_policy,
2349	.get_policy     = shmem_get_policy,
2350#endif
2351};
2352
2353static struct dentry *shmem_mount(struct file_system_type *fs_type,
2354	int flags, const char *dev_name, void *data)
2355{
2356	return mount_nodev(fs_type, flags, data, shmem_fill_super);
2357}
2358
2359static struct file_system_type shmem_fs_type = {
2360	.owner		= THIS_MODULE,
2361	.name		= "tmpfs",
2362	.mount		= shmem_mount,
2363	.kill_sb	= kill_litter_super,
 
2364};
2365
2366int __init shmem_init(void)
2367{
2368	int error;
2369
2370	error = bdi_init(&shmem_backing_dev_info);
2371	if (error)
2372		goto out4;
2373
2374	error = shmem_init_inodecache();
2375	if (error)
2376		goto out3;
2377
2378	error = register_filesystem(&shmem_fs_type);
2379	if (error) {
2380		printk(KERN_ERR "Could not register tmpfs\n");
2381		goto out2;
2382	}
2383
2384	shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER,
2385				 shmem_fs_type.name, NULL);
2386	if (IS_ERR(shm_mnt)) {
2387		error = PTR_ERR(shm_mnt);
2388		printk(KERN_ERR "Could not kern_mount tmpfs\n");
2389		goto out1;
2390	}
 
 
 
 
 
 
 
2391	return 0;
2392
2393out1:
2394	unregister_filesystem(&shmem_fs_type);
2395out2:
2396	shmem_destroy_inodecache();
2397out3:
2398	bdi_destroy(&shmem_backing_dev_info);
2399out4:
2400	shm_mnt = ERR_PTR(error);
2401	return error;
2402}
2403
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2404#else /* !CONFIG_SHMEM */
2405
2406/*
2407 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
2408 *
2409 * This is intended for small system where the benefits of the full
2410 * shmem code (swap-backed and resource-limited) are outweighed by
2411 * their complexity. On systems without swap this code should be
2412 * effectively equivalent, but much lighter weight.
2413 */
2414
2415#include <linux/ramfs.h>
2416
2417static struct file_system_type shmem_fs_type = {
2418	.name		= "tmpfs",
2419	.mount		= ramfs_mount,
2420	.kill_sb	= kill_litter_super,
 
2421};
2422
2423int __init shmem_init(void)
2424{
2425	BUG_ON(register_filesystem(&shmem_fs_type) != 0);
2426
2427	shm_mnt = kern_mount(&shmem_fs_type);
2428	BUG_ON(IS_ERR(shm_mnt));
2429
2430	return 0;
2431}
2432
2433int shmem_unuse(swp_entry_t swap, struct page *page)
2434{
2435	return 0;
2436}
2437
2438int shmem_lock(struct file *file, int lock, struct user_struct *user)
2439{
2440	return 0;
2441}
2442
 
 
 
 
 
 
 
 
 
 
 
 
 
2443void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
2444{
2445	truncate_inode_pages_range(inode->i_mapping, lstart, lend);
2446}
2447EXPORT_SYMBOL_GPL(shmem_truncate_range);
2448
2449#define shmem_vm_ops				generic_file_vm_ops
2450#define shmem_file_operations			ramfs_file_operations
2451#define shmem_get_inode(sb, dir, mode, dev, flags)	ramfs_get_inode(sb, dir, mode, dev)
2452#define shmem_acct_size(flags, size)		0
2453#define shmem_unacct_size(flags, size)		do {} while (0)
2454
2455#endif /* CONFIG_SHMEM */
2456
2457/* common code */
2458
2459/**
2460 * shmem_file_setup - get an unlinked file living in tmpfs
2461 * @name: name for dentry (to be seen in /proc/<pid>/maps
2462 * @size: size to be set for the file
2463 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
2464 */
2465struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
2466{
2467	int error;
2468	struct file *file;
2469	struct inode *inode;
2470	struct path path;
2471	struct dentry *root;
2472	struct qstr this;
2473
2474	if (IS_ERR(shm_mnt))
2475		return (void *)shm_mnt;
2476
2477	if (size < 0 || size > MAX_LFS_FILESIZE)
2478		return ERR_PTR(-EINVAL);
2479
2480	if (shmem_acct_size(flags, size))
2481		return ERR_PTR(-ENOMEM);
2482
2483	error = -ENOMEM;
2484	this.name = name;
2485	this.len = strlen(name);
2486	this.hash = 0; /* will go */
2487	root = shm_mnt->mnt_root;
2488	path.dentry = d_alloc(root, &this);
 
2489	if (!path.dentry)
2490		goto put_memory;
2491	path.mnt = mntget(shm_mnt);
2492
2493	error = -ENOSPC;
2494	inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
2495	if (!inode)
2496		goto put_dentry;
2497
 
2498	d_instantiate(path.dentry, inode);
2499	inode->i_size = size;
2500	inode->i_nlink = 0;	/* It is unlinked */
2501#ifndef CONFIG_MMU
2502	error = ramfs_nommu_expand_for_mapping(inode, size);
2503	if (error)
2504		goto put_dentry;
2505#endif
2506
2507	error = -ENFILE;
2508	file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
2509		  &shmem_file_operations);
2510	if (!file)
2511		goto put_dentry;
2512
2513	return file;
2514
2515put_dentry:
2516	path_put(&path);
2517put_memory:
2518	shmem_unacct_size(flags, size);
2519	return ERR_PTR(error);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
2520}
2521EXPORT_SYMBOL_GPL(shmem_file_setup);
2522
2523/**
2524 * shmem_zero_setup - setup a shared anonymous mapping
2525 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
2526 */
2527int shmem_zero_setup(struct vm_area_struct *vma)
2528{
2529	struct file *file;
2530	loff_t size = vma->vm_end - vma->vm_start;
2531
2532	file = shmem_file_setup("dev/zero", size, vma->vm_flags);
 
 
 
 
 
 
2533	if (IS_ERR(file))
2534		return PTR_ERR(file);
2535
2536	if (vma->vm_file)
2537		fput(vma->vm_file);
2538	vma->vm_file = file;
2539	vma->vm_ops = &shmem_vm_ops;
2540	vma->vm_flags |= VM_CAN_NONLINEAR;
 
 
 
 
 
 
2541	return 0;
2542}
2543
2544/**
2545 * shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
2546 * @mapping:	the page's address_space
2547 * @index:	the page index
2548 * @gfp:	the page allocator flags to use if allocating
2549 *
2550 * This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
2551 * with any new page allocations done using the specified allocation flags.
2552 * But read_cache_page_gfp() uses the ->readpage() method: which does not
2553 * suit tmpfs, since it may have pages in swapcache, and needs to find those
2554 * for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
2555 *
2556 * i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
2557 * with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
2558 */
2559struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
2560					 pgoff_t index, gfp_t gfp)
2561{
2562#ifdef CONFIG_SHMEM
2563	struct inode *inode = mapping->host;
2564	struct page *page;
2565	int error;
2566
2567	BUG_ON(mapping->a_ops != &shmem_aops);
2568	error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
 
2569	if (error)
2570		page = ERR_PTR(error);
2571	else
2572		unlock_page(page);
2573	return page;
2574#else
2575	/*
2576	 * The tiny !SHMEM case uses ramfs without swap
2577	 */
2578	return read_cache_page_gfp(mapping, index, gfp);
2579#endif
2580}
2581EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);