shmem.c 69.2 KB
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/*
 * Resizable virtual memory filesystem for Linux.
 *
 * Copyright (C) 2000 Linus Torvalds.
 *		 2000 Transmeta Corp.
 *		 2000-2001 Christoph Rohland
 *		 2000-2001 SAP AG
 *		 2002 Red Hat Inc.
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 * Copyright (C) 2002-2005 Hugh Dickins.
 * Copyright (C) 2002-2005 VERITAS Software Corporation.
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 * Copyright (C) 2004 Andi Kleen, SuSE Labs
 *
 * Extended attribute support for tmpfs:
 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
 *
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 * tiny-shmem:
 * Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
 *
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 * This file is released under the GPL.
 */

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#include <linux/fs.h>
#include <linux/init.h>
#include <linux/vfs.h>
#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/file.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/swap.h>

static struct vfsmount *shm_mnt;

#ifdef CONFIG_SHMEM
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/*
 * This virtual memory filesystem is heavily based on the ramfs. It
 * extends ramfs by the ability to use swap and honor resource limits
 * which makes it a completely usable filesystem.
 */

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#include <linux/xattr.h>
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#include <linux/exportfs.h>
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#include <linux/posix_acl.h>
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#include <linux/generic_acl.h>
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#include <linux/mman.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/backing-dev.h>
#include <linux/shmem_fs.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/security.h>
#include <linux/swapops.h>
#include <linux/mempolicy.h>
#include <linux/namei.h>
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#include <linux/ctype.h>
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#include <linux/migrate.h>
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#include <linux/highmem.h>
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#include <linux/seq_file.h>
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#include <linux/magic.h>
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#include <asm/uaccess.h>
#include <asm/div64.h>
#include <asm/pgtable.h>

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/*
 * The maximum size of a shmem/tmpfs file is limited by the maximum size of
 * its triple-indirect swap vector - see illustration at shmem_swp_entry().
 *
 * With 4kB page size, maximum file size is just over 2TB on a 32-bit kernel,
 * but one eighth of that on a 64-bit kernel.  With 8kB page size, maximum
 * file size is just over 4TB on a 64-bit kernel, but 16TB on a 32-bit kernel,
 * MAX_LFS_FILESIZE being then more restrictive than swap vector layout.
 *
 * We use / and * instead of shifts in the definitions below, so that the swap
 * vector can be tested with small even values (e.g. 20) for ENTRIES_PER_PAGE.
 */
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#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
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#define ENTRIES_PER_PAGEPAGE ((unsigned long long)ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
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#define SHMSWP_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
#define SHMSWP_MAX_BYTES (SHMSWP_MAX_INDEX << PAGE_CACHE_SHIFT)
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#define SHMEM_MAX_BYTES  min_t(unsigned long long, SHMSWP_MAX_BYTES, MAX_LFS_FILESIZE)
#define SHMEM_MAX_INDEX  ((unsigned long)((SHMEM_MAX_BYTES+1) >> PAGE_CACHE_SHIFT))

#define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)
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#define VM_ACCT(size)    (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)

/* info->flags needs VM_flags to handle pagein/truncate races efficiently */
#define SHMEM_PAGEIN	 VM_READ
#define SHMEM_TRUNCATE	 VM_WRITE

/* Definition to limit shmem_truncate's steps between cond_rescheds */
#define LATENCY_LIMIT	 64

/* Pretend that each entry is of this size in directory's i_size */
#define BOGO_DIRENT_SIZE 20

/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
enum sgp_type {
	SGP_READ,	/* don't exceed i_size, don't allocate page */
	SGP_CACHE,	/* don't exceed i_size, may allocate page */
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	SGP_DIRTY,	/* like SGP_CACHE, but set new page dirty */
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	SGP_WRITE,	/* may exceed i_size, may allocate page */
};

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#ifdef CONFIG_TMPFS
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static unsigned long shmem_default_max_blocks(void)
{
	return totalram_pages / 2;
}

static unsigned long shmem_default_max_inodes(void)
{
	return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
}
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#endif
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static int shmem_getpage(struct inode *inode, unsigned long idx,
			 struct page **pagep, enum sgp_type sgp, int *type);

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static inline struct page *shmem_dir_alloc(gfp_t gfp_mask)
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{
	/*
	 * The above definition of ENTRIES_PER_PAGE, and the use of
	 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE:
	 * might be reconsidered if it ever diverges from PAGE_SIZE.
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	 *
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	 * Mobility flags are masked out as swap vectors cannot move
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	 */
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	return alloc_pages((gfp_mask & ~GFP_MOVABLE_MASK) | __GFP_ZERO,
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				PAGE_CACHE_SHIFT-PAGE_SHIFT);
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}

static inline void shmem_dir_free(struct page *page)
{
	__free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT);
}

static struct page **shmem_dir_map(struct page *page)
{
	return (struct page **)kmap_atomic(page, KM_USER0);
}

static inline void shmem_dir_unmap(struct page **dir)
{
	kunmap_atomic(dir, KM_USER0);
}

static swp_entry_t *shmem_swp_map(struct page *page)
{
	return (swp_entry_t *)kmap_atomic(page, KM_USER1);
}

static inline void shmem_swp_balance_unmap(void)
{
	/*
	 * When passing a pointer to an i_direct entry, to code which
	 * also handles indirect entries and so will shmem_swp_unmap,
	 * we must arrange for the preempt count to remain in balance.
	 * What kmap_atomic of a lowmem page does depends on config
	 * and architecture, so pretend to kmap_atomic some lowmem page.
	 */
	(void) kmap_atomic(ZERO_PAGE(0), KM_USER1);
}

static inline void shmem_swp_unmap(swp_entry_t *entry)
{
	kunmap_atomic(entry, KM_USER1);
}

static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
{
	return sb->s_fs_info;
}

/*
 * shmem_file_setup pre-accounts the whole fixed size of a VM object,
 * for shared memory and for shared anonymous (/dev/zero) mappings
 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
 * consistent with the pre-accounting of private mappings ...
 */
static inline int shmem_acct_size(unsigned long flags, loff_t size)
{
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	return (flags & VM_NORESERVE) ?
		0 : security_vm_enough_memory_kern(VM_ACCT(size));
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}

static inline void shmem_unacct_size(unsigned long flags, loff_t size)
{
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	if (!(flags & VM_NORESERVE))
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		vm_unacct_memory(VM_ACCT(size));
}

/*
 * ... whereas tmpfs objects are accounted incrementally as
 * pages are allocated, in order to allow huge sparse files.
 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
 */
static inline int shmem_acct_block(unsigned long flags)
{
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	return (flags & VM_NORESERVE) ?
		security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
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}

static inline void shmem_unacct_blocks(unsigned long flags, long pages)
{
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	if (flags & VM_NORESERVE)
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		vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
}

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static const struct super_operations shmem_ops;
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static const struct address_space_operations shmem_aops;
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static const struct file_operations shmem_file_operations;
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static const struct inode_operations shmem_inode_operations;
static const struct inode_operations shmem_dir_inode_operations;
static const struct inode_operations shmem_special_inode_operations;
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static const struct vm_operations_struct shmem_vm_ops;
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static struct backing_dev_info shmem_backing_dev_info  __read_mostly = {
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	.ra_pages	= 0,	/* No readahead */
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	.capabilities	= BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
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	.unplug_io_fn	= default_unplug_io_fn,
};

static LIST_HEAD(shmem_swaplist);
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static DEFINE_MUTEX(shmem_swaplist_mutex);
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static void shmem_free_blocks(struct inode *inode, long pages)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
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	if (sbinfo->max_blocks) {
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		spin_lock(&sbinfo->stat_lock);
		sbinfo->free_blocks += pages;
		inode->i_blocks -= pages*BLOCKS_PER_PAGE;
		spin_unlock(&sbinfo->stat_lock);
	}
}

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static int shmem_reserve_inode(struct super_block *sb)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
	if (sbinfo->max_inodes) {
		spin_lock(&sbinfo->stat_lock);
		if (!sbinfo->free_inodes) {
			spin_unlock(&sbinfo->stat_lock);
			return -ENOSPC;
		}
		sbinfo->free_inodes--;
		spin_unlock(&sbinfo->stat_lock);
	}
	return 0;
}

static void shmem_free_inode(struct super_block *sb)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
	if (sbinfo->max_inodes) {
		spin_lock(&sbinfo->stat_lock);
		sbinfo->free_inodes++;
		spin_unlock(&sbinfo->stat_lock);
	}
}

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/**
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 * shmem_recalc_inode - recalculate the size of an inode
 * @inode: inode to recalc
 *
 * We have to calculate the free blocks since the mm can drop
 * undirtied hole pages behind our back.
 *
 * But normally   info->alloced == inode->i_mapping->nrpages + info->swapped
 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
 *
 * It has to be called with the spinlock held.
 */
static void shmem_recalc_inode(struct inode *inode)
{
	struct shmem_inode_info *info = SHMEM_I(inode);
	long freed;

	freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
	if (freed > 0) {
		info->alloced -= freed;
		shmem_unacct_blocks(info->flags, freed);
		shmem_free_blocks(inode, freed);
	}
}

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/**
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 * shmem_swp_entry - find the swap vector position in the info structure
 * @info:  info structure for the inode
 * @index: index of the page to find
 * @page:  optional page to add to the structure. Has to be preset to
 *         all zeros
 *
 * If there is no space allocated yet it will return NULL when
 * page is NULL, else it will use the page for the needed block,
 * setting it to NULL on return to indicate that it has been used.
 *
 * The swap vector is organized the following way:
 *
 * There are SHMEM_NR_DIRECT entries directly stored in the
 * shmem_inode_info structure. So small files do not need an addional
 * allocation.
 *
 * For pages with index > SHMEM_NR_DIRECT there is the pointer
 * i_indirect which points to a page which holds in the first half
 * doubly indirect blocks, in the second half triple indirect blocks:
 *
 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the
 * following layout (for SHMEM_NR_DIRECT == 16):
 *
 * i_indirect -> dir --> 16-19
 * 	      |	     +-> 20-23
 * 	      |
 * 	      +-->dir2 --> 24-27
 * 	      |	       +-> 28-31
 * 	      |	       +-> 32-35
 * 	      |	       +-> 36-39
 * 	      |
 * 	      +-->dir3 --> 40-43
 * 	       	       +-> 44-47
 * 	      	       +-> 48-51
 * 	      	       +-> 52-55
 */
static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page)
{
	unsigned long offset;
	struct page **dir;
	struct page *subdir;

	if (index < SHMEM_NR_DIRECT) {
		shmem_swp_balance_unmap();
		return info->i_direct+index;
	}
	if (!info->i_indirect) {
		if (page) {
			info->i_indirect = *page;
			*page = NULL;
		}
		return NULL;			/* need another page */
	}

	index -= SHMEM_NR_DIRECT;
	offset = index % ENTRIES_PER_PAGE;
	index /= ENTRIES_PER_PAGE;
	dir = shmem_dir_map(info->i_indirect);

	if (index >= ENTRIES_PER_PAGE/2) {
		index -= ENTRIES_PER_PAGE/2;
		dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE;
		index %= ENTRIES_PER_PAGE;
		subdir = *dir;
		if (!subdir) {
			if (page) {
				*dir = *page;
				*page = NULL;
			}
			shmem_dir_unmap(dir);
			return NULL;		/* need another page */
		}
		shmem_dir_unmap(dir);
		dir = shmem_dir_map(subdir);
	}

	dir += index;
	subdir = *dir;
	if (!subdir) {
		if (!page || !(subdir = *page)) {
			shmem_dir_unmap(dir);
			return NULL;		/* need a page */
		}
		*dir = subdir;
		*page = NULL;
	}
	shmem_dir_unmap(dir);
	return shmem_swp_map(subdir) + offset;
}

static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value)
{
	long incdec = value? 1: -1;

	entry->val = value;
	info->swapped += incdec;
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	if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) {
		struct page *page = kmap_atomic_to_page(entry);
		set_page_private(page, page_private(page) + incdec);
	}
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}

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/**
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 * shmem_swp_alloc - get the position of the swap entry for the page.
 * @info:	info structure for the inode
 * @index:	index of the page to find
 * @sgp:	check and recheck i_size? skip allocation?
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 *
 * If the entry does not exist, allocate it.
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 */
static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp)
{
	struct inode *inode = &info->vfs_inode;
	struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
	struct page *page = NULL;
	swp_entry_t *entry;

	if (sgp != SGP_WRITE &&
	    ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode))
		return ERR_PTR(-EINVAL);

	while (!(entry = shmem_swp_entry(info, index, &page))) {
		if (sgp == SGP_READ)
			return shmem_swp_map(ZERO_PAGE(0));
		/*
		 * Test free_blocks against 1 not 0, since we have 1 data
		 * page (and perhaps indirect index pages) yet to allocate:
		 * a waste to allocate index if we cannot allocate data.
		 */
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		if (sbinfo->max_blocks) {
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			spin_lock(&sbinfo->stat_lock);
			if (sbinfo->free_blocks <= 1) {
				spin_unlock(&sbinfo->stat_lock);
				return ERR_PTR(-ENOSPC);
			}
			sbinfo->free_blocks--;
			inode->i_blocks += BLOCKS_PER_PAGE;
			spin_unlock(&sbinfo->stat_lock);
		}

		spin_unlock(&info->lock);
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		page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping));
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		if (page)
			set_page_private(page, 0);
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		spin_lock(&info->lock);

		if (!page) {
			shmem_free_blocks(inode, 1);
			return ERR_PTR(-ENOMEM);
		}
		if (sgp != SGP_WRITE &&
		    ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
			entry = ERR_PTR(-EINVAL);
			break;
		}
		if (info->next_index <= index)
			info->next_index = index + 1;
	}
	if (page) {
		/* another task gave its page, or truncated the file */
		shmem_free_blocks(inode, 1);
		shmem_dir_free(page);
	}
	if (info->next_index <= index && !IS_ERR(entry))
		info->next_index = index + 1;
	return entry;
}

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/**
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 * shmem_free_swp - free some swap entries in a directory
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 * @dir:        pointer to the directory
 * @edir:       pointer after last entry of the directory
 * @punch_lock: pointer to spinlock when needed for the holepunch case
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 */
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static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir,
						spinlock_t *punch_lock)
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{
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	spinlock_t *punch_unlock = NULL;
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	swp_entry_t *ptr;
	int freed = 0;

	for (ptr = dir; ptr < edir; ptr++) {
		if (ptr->val) {
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			if (unlikely(punch_lock)) {
				punch_unlock = punch_lock;
				punch_lock = NULL;
				spin_lock(punch_unlock);
				if (!ptr->val)
					continue;
			}
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			free_swap_and_cache(*ptr);
			*ptr = (swp_entry_t){0};
			freed++;
		}
	}
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	if (punch_unlock)
		spin_unlock(punch_unlock);
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	return freed;
}

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static int shmem_map_and_free_swp(struct page *subdir, int offset,
		int limit, struct page ***dir, spinlock_t *punch_lock)
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{
	swp_entry_t *ptr;
	int freed = 0;

	ptr = shmem_swp_map(subdir);
	for (; offset < limit; offset += LATENCY_LIMIT) {
		int size = limit - offset;
		if (size > LATENCY_LIMIT)
			size = LATENCY_LIMIT;
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		freed += shmem_free_swp(ptr+offset, ptr+offset+size,
							punch_lock);
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		if (need_resched()) {
			shmem_swp_unmap(ptr);
			if (*dir) {
				shmem_dir_unmap(*dir);
				*dir = NULL;
			}
			cond_resched();
			ptr = shmem_swp_map(subdir);
		}
	}
	shmem_swp_unmap(ptr);
	return freed;
}

static void shmem_free_pages(struct list_head *next)
{
	struct page *page;
	int freed = 0;

	do {
		page = container_of(next, struct page, lru);
		next = next->next;
		shmem_dir_free(page);
		freed++;
		if (freed >= LATENCY_LIMIT) {
			cond_resched();
			freed = 0;
		}
	} while (next);
}

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static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end)
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{
	struct shmem_inode_info *info = SHMEM_I(inode);
	unsigned long idx;
	unsigned long size;
	unsigned long limit;
	unsigned long stage;
	unsigned long diroff;
	struct page **dir;
	struct page *topdir;
	struct page *middir;
	struct page *subdir;
	swp_entry_t *ptr;
	LIST_HEAD(pages_to_free);
	long nr_pages_to_free = 0;
	long nr_swaps_freed = 0;
	int offset;
	int freed;
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	int punch_hole;
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	spinlock_t *needs_lock;
	spinlock_t *punch_lock;
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	unsigned long upper_limit;
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	inode->i_ctime = inode->i_mtime = CURRENT_TIME;
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	idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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	if (idx >= info->next_index)
		return;

	spin_lock(&info->lock);
	info->flags |= SHMEM_TRUNCATE;
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	if (likely(end == (loff_t) -1)) {
		limit = info->next_index;
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		upper_limit = SHMEM_MAX_INDEX;
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		info->next_index = idx;
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		needs_lock = NULL;
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		punch_hole = 0;
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	} else {
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		if (end + 1 >= inode->i_size) {	/* we may free a little more */
			limit = (inode->i_size + PAGE_CACHE_SIZE - 1) >>
							PAGE_CACHE_SHIFT;
			upper_limit = SHMEM_MAX_INDEX;
		} else {
			limit = (end + 1) >> PAGE_CACHE_SHIFT;
			upper_limit = limit;
		}
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		needs_lock = &info->lock;
584 585 586
		punch_hole = 1;
	}

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587
	topdir = info->i_indirect;
588
	if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
L
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589 590 591 592 593 594 595 596 597 598 599
		info->i_indirect = NULL;
		nr_pages_to_free++;
		list_add(&topdir->lru, &pages_to_free);
	}
	spin_unlock(&info->lock);

	if (info->swapped && idx < SHMEM_NR_DIRECT) {
		ptr = info->i_direct;
		size = limit;
		if (size > SHMEM_NR_DIRECT)
			size = SHMEM_NR_DIRECT;
600
		nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
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Linus Torvalds 已提交
601
	}
602 603 604 605 606

	/*
	 * If there are no indirect blocks or we are punching a hole
	 * below indirect blocks, nothing to be done.
	 */
607
	if (!topdir || limit <= SHMEM_NR_DIRECT)
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Linus Torvalds 已提交
608 609
		goto done2;

610 611 612 613 614 615 616 617 618 619 620 621 622
	/*
	 * The truncation case has already dropped info->lock, and we're safe
	 * because i_size and next_index have already been lowered, preventing
	 * access beyond.  But in the punch_hole case, we still need to take
	 * the lock when updating the swap directory, because there might be
	 * racing accesses by shmem_getpage(SGP_CACHE), shmem_unuse_inode or
	 * shmem_writepage.  However, whenever we find we can remove a whole
	 * directory page (not at the misaligned start or end of the range),
	 * we first NULLify its pointer in the level above, and then have no
	 * need to take the lock when updating its contents: needs_lock and
	 * punch_lock (either pointing to info->lock or NULL) manage this.
	 */

623
	upper_limit -= SHMEM_NR_DIRECT;
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624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642
	limit -= SHMEM_NR_DIRECT;
	idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0;
	offset = idx % ENTRIES_PER_PAGE;
	idx -= offset;

	dir = shmem_dir_map(topdir);
	stage = ENTRIES_PER_PAGEPAGE/2;
	if (idx < ENTRIES_PER_PAGEPAGE/2) {
		middir = topdir;
		diroff = idx/ENTRIES_PER_PAGE;
	} else {
		dir += ENTRIES_PER_PAGE/2;
		dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE;
		while (stage <= idx)
			stage += ENTRIES_PER_PAGEPAGE;
		middir = *dir;
		if (*dir) {
			diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) %
				ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE;
643
			if (!diroff && !offset && upper_limit >= stage) {
644 645 646 647 648 649 650
				if (needs_lock) {
					spin_lock(needs_lock);
					*dir = NULL;
					spin_unlock(needs_lock);
					needs_lock = NULL;
				} else
					*dir = NULL;
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651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675
				nr_pages_to_free++;
				list_add(&middir->lru, &pages_to_free);
			}
			shmem_dir_unmap(dir);
			dir = shmem_dir_map(middir);
		} else {
			diroff = 0;
			offset = 0;
			idx = stage;
		}
	}

	for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) {
		if (unlikely(idx == stage)) {
			shmem_dir_unmap(dir);
			dir = shmem_dir_map(topdir) +
			    ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
			while (!*dir) {
				dir++;
				idx += ENTRIES_PER_PAGEPAGE;
				if (idx >= limit)
					goto done1;
			}
			stage = idx + ENTRIES_PER_PAGEPAGE;
			middir = *dir;
676 677
			if (punch_hole)
				needs_lock = &info->lock;
678
			if (upper_limit >= stage) {
679 680 681 682 683 684 685
				if (needs_lock) {
					spin_lock(needs_lock);
					*dir = NULL;
					spin_unlock(needs_lock);
					needs_lock = NULL;
				} else
					*dir = NULL;
686 687 688
				nr_pages_to_free++;
				list_add(&middir->lru, &pages_to_free);
			}
L
Linus Torvalds 已提交
689 690 691 692 693
			shmem_dir_unmap(dir);
			cond_resched();
			dir = shmem_dir_map(middir);
			diroff = 0;
		}
694
		punch_lock = needs_lock;
L
Linus Torvalds 已提交
695
		subdir = dir[diroff];
696 697 698 699 700 701 702 703 704 705 706 707
		if (subdir && !offset && upper_limit-idx >= ENTRIES_PER_PAGE) {
			if (needs_lock) {
				spin_lock(needs_lock);
				dir[diroff] = NULL;
				spin_unlock(needs_lock);
				punch_lock = NULL;
			} else
				dir[diroff] = NULL;
			nr_pages_to_free++;
			list_add(&subdir->lru, &pages_to_free);
		}
		if (subdir && page_private(subdir) /* has swap entries */) {
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			size = limit - idx;
			if (size > ENTRIES_PER_PAGE)
				size = ENTRIES_PER_PAGE;
			freed = shmem_map_and_free_swp(subdir,
712
					offset, size, &dir, punch_lock);
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713 714 715
			if (!dir)
				dir = shmem_dir_map(middir);
			nr_swaps_freed += freed;
716
			if (offset || punch_lock) {
L
Linus Torvalds 已提交
717
				spin_lock(&info->lock);
718 719
				set_page_private(subdir,
					page_private(subdir) - freed);
L
Linus Torvalds 已提交
720
				spin_unlock(&info->lock);
721 722
			} else
				BUG_ON(page_private(subdir) != freed);
L
Linus Torvalds 已提交
723
		}
724
		offset = 0;
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725 726 727 728 729 730 731 732 733 734 735
	}
done1:
	shmem_dir_unmap(dir);
done2:
	if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) {
		/*
		 * Call truncate_inode_pages again: racing shmem_unuse_inode
		 * may have swizzled a page in from swap since vmtruncate or
		 * generic_delete_inode did it, before we lowered next_index.
		 * Also, though shmem_getpage checks i_size before adding to
		 * cache, no recheck after: so fix the narrow window there too.
736 737 738 739 740
		 *
		 * Recalling truncate_inode_pages_range and unmap_mapping_range
		 * every time for punch_hole (which never got a chance to clear
		 * SHMEM_PAGEIN at the start of vmtruncate_range) is expensive,
		 * yet hardly ever necessary: try to optimize them out later.
L
Linus Torvalds 已提交
741
		 */
742
		truncate_inode_pages_range(inode->i_mapping, start, end);
743 744 745
		if (punch_hole)
			unmap_mapping_range(inode->i_mapping, start,
							end - start, 1);
L
Linus Torvalds 已提交
746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764
	}

	spin_lock(&info->lock);
	info->flags &= ~SHMEM_TRUNCATE;
	info->swapped -= nr_swaps_freed;
	if (nr_pages_to_free)
		shmem_free_blocks(inode, nr_pages_to_free);
	shmem_recalc_inode(inode);
	spin_unlock(&info->lock);

	/*
	 * Empty swap vector directory pages to be freed?
	 */
	if (!list_empty(&pages_to_free)) {
		pages_to_free.prev->next = NULL;
		shmem_free_pages(pages_to_free.next);
	}
}

765 766 767 768 769
static void shmem_truncate(struct inode *inode)
{
	shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
}

L
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770 771 772 773 774 775
static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;
	struct page *page = NULL;
	int error;

776
	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
L
Linus Torvalds 已提交
777 778 779 780 781 782 783 784 785 786 787 788
		if (attr->ia_size < inode->i_size) {
			/*
			 * If truncating down to a partial page, then
			 * if that page is already allocated, hold it
			 * in memory until the truncation is over, so
			 * truncate_partial_page cannnot miss it were
			 * it assigned to swap.
			 */
			if (attr->ia_size & (PAGE_CACHE_SIZE-1)) {
				(void) shmem_getpage(inode,
					attr->ia_size>>PAGE_CACHE_SHIFT,
						&page, SGP_READ, NULL);
H
Hugh Dickins 已提交
789 790
				if (page)
					unlock_page(page);
L
Linus Torvalds 已提交
791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810
			}
			/*
			 * Reset SHMEM_PAGEIN flag so that shmem_truncate can
			 * detect if any pages might have been added to cache
			 * after truncate_inode_pages.  But we needn't bother
			 * if it's being fully truncated to zero-length: the
			 * nrpages check is efficient enough in that case.
			 */
			if (attr->ia_size) {
				struct shmem_inode_info *info = SHMEM_I(inode);
				spin_lock(&info->lock);
				info->flags &= ~SHMEM_PAGEIN;
				spin_unlock(&info->lock);
			}
		}
	}

	error = inode_change_ok(inode, attr);
	if (!error)
		error = inode_setattr(inode, attr);
811 812
#ifdef CONFIG_TMPFS_POSIX_ACL
	if (!error && (attr->ia_valid & ATTR_MODE))
813
		error = generic_acl_chmod(inode);
814
#endif
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815 816 817 818 819 820 821 822 823 824
	if (page)
		page_cache_release(page);
	return error;
}

static void shmem_delete_inode(struct inode *inode)
{
	struct shmem_inode_info *info = SHMEM_I(inode);

	if (inode->i_op->truncate == shmem_truncate) {
825
		truncate_inode_pages(inode->i_mapping, 0);
L
Linus Torvalds 已提交
826 827 828 829
		shmem_unacct_size(info->flags, inode->i_size);
		inode->i_size = 0;
		shmem_truncate(inode);
		if (!list_empty(&info->swaplist)) {
830
			mutex_lock(&shmem_swaplist_mutex);
L
Linus Torvalds 已提交
831
			list_del_init(&info->swaplist);
832
			mutex_unlock(&shmem_swaplist_mutex);
L
Linus Torvalds 已提交
833 834
		}
	}
835
	BUG_ON(inode->i_blocks);
836
	shmem_free_inode(inode->i_sb);
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837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861
	clear_inode(inode);
}

static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir)
{
	swp_entry_t *ptr;

	for (ptr = dir; ptr < edir; ptr++) {
		if (ptr->val == entry.val)
			return ptr - dir;
	}
	return -1;
}

static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page)
{
	struct inode *inode;
	unsigned long idx;
	unsigned long size;
	unsigned long limit;
	unsigned long stage;
	struct page **dir;
	struct page *subdir;
	swp_entry_t *ptr;
	int offset;
862
	int error;
L
Linus Torvalds 已提交
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	idx = 0;
	ptr = info->i_direct;
	spin_lock(&info->lock);
H
Hugh Dickins 已提交
867 868 869 870
	if (!info->swapped) {
		list_del_init(&info->swaplist);
		goto lost2;
	}
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871 872 873 874 875
	limit = info->next_index;
	size = limit;
	if (size > SHMEM_NR_DIRECT)
		size = SHMEM_NR_DIRECT;
	offset = shmem_find_swp(entry, ptr, ptr+size);
876
	if (offset >= 0)
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Linus Torvalds 已提交
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		goto found;
	if (!info->i_indirect)
		goto lost2;

	dir = shmem_dir_map(info->i_indirect);
	stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2;

	for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) {
		if (unlikely(idx == stage)) {
			shmem_dir_unmap(dir-1);
887 888 889 890 891 892 893 894
			if (cond_resched_lock(&info->lock)) {
				/* check it has not been truncated */
				if (limit > info->next_index) {
					limit = info->next_index;
					if (idx >= limit)
						goto lost2;
				}
			}
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895 896 897 898 899 900 901 902 903 904 905 906 907 908
			dir = shmem_dir_map(info->i_indirect) +
			    ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE;
			while (!*dir) {
				dir++;
				idx += ENTRIES_PER_PAGEPAGE;
				if (idx >= limit)
					goto lost1;
			}
			stage = idx + ENTRIES_PER_PAGEPAGE;
			subdir = *dir;
			shmem_dir_unmap(dir);
			dir = shmem_dir_map(subdir);
		}
		subdir = *dir;
H
Hugh Dickins 已提交
909
		if (subdir && page_private(subdir)) {
L
Linus Torvalds 已提交
910 911 912 913 914
			ptr = shmem_swp_map(subdir);
			size = limit - idx;
			if (size > ENTRIES_PER_PAGE)
				size = ENTRIES_PER_PAGE;
			offset = shmem_find_swp(entry, ptr, ptr+size);
915
			shmem_swp_unmap(ptr);
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Linus Torvalds 已提交
916 917 918 919 920 921 922 923 924 925 926 927 928
			if (offset >= 0) {
				shmem_dir_unmap(dir);
				goto found;
			}
		}
	}
lost1:
	shmem_dir_unmap(dir-1);
lost2:
	spin_unlock(&info->lock);
	return 0;
found:
	idx += offset;
929 930 931
	inode = igrab(&info->vfs_inode);
	spin_unlock(&info->lock);

H
Hugh Dickins 已提交
932 933 934 935 936 937 938 939 940
	/*
	 * Move _head_ to start search for next from here.
	 * But be careful: shmem_delete_inode checks list_empty without taking
	 * mutex, and there's an instant in list_move_tail when info->swaplist
	 * would appear empty, if it were the only one on shmem_swaplist.  We
	 * could avoid doing it if inode NULL; or use this minor optimization.
	 */
	if (shmem_swaplist.next != &info->swaplist)
		list_move_tail(&shmem_swaplist, &info->swaplist);
941 942 943 944 945
	mutex_unlock(&shmem_swaplist_mutex);

	error = 1;
	if (!inode)
		goto out;
K
KAMEZAWA Hiroyuki 已提交
946
	/*
947 948 949
	 * Charge page using GFP_KERNEL while we can wait.
	 * Charged back to the user(not to caller) when swap account is used.
	 * add_to_page_cache() will be called with GFP_NOWAIT.
K
KAMEZAWA Hiroyuki 已提交
950
	 */
951
	error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
H
Hugh Dickins 已提交
952 953
	if (error)
		goto out;
954
	error = radix_tree_preload(GFP_KERNEL);
955 956 957 958
	if (error) {
		mem_cgroup_uncharge_cache_page(page);
		goto out;
	}
H
Hugh Dickins 已提交
959
	error = 1;
960 961 962

	spin_lock(&info->lock);
	ptr = shmem_swp_entry(info, idx, NULL);
963
	if (ptr && ptr->val == entry.val) {
N
Nick Piggin 已提交
964
		error = add_to_page_cache_locked(page, inode->i_mapping,
H
Hugh Dickins 已提交
965
						idx, GFP_NOWAIT);
966 967 968 969
		/* does mem_cgroup_uncharge_cache_page on error */
	} else	/* we must compensate for our precharge above */
		mem_cgroup_uncharge_cache_page(page);

970 971
	if (error == -EEXIST) {
		struct page *filepage = find_get_page(inode->i_mapping, idx);
972
		error = 1;
973 974 975 976 977 978 979 980 981 982 983
		if (filepage) {
			/*
			 * There might be a more uptodate page coming down
			 * from a stacked writepage: forget our swappage if so.
			 */
			if (PageUptodate(filepage))
				error = 0;
			page_cache_release(filepage);
		}
	}
	if (!error) {
984 985
		delete_from_swap_cache(page);
		set_page_dirty(page);
L
Linus Torvalds 已提交
986
		info->flags |= SHMEM_PAGEIN;
987 988 989
		shmem_swp_set(info, ptr, 0);
		swap_free(entry);
		error = 1;	/* not an error, but entry was found */
L
Linus Torvalds 已提交
990
	}
991 992
	if (ptr)
		shmem_swp_unmap(ptr);
L
Linus Torvalds 已提交
993
	spin_unlock(&info->lock);
H
Hugh Dickins 已提交
994
	radix_tree_preload_end();
995 996 997 998 999
out:
	unlock_page(page);
	page_cache_release(page);
	iput(inode);		/* allows for NULL */
	return error;
L
Linus Torvalds 已提交
1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
}

/*
 * shmem_unuse() search for an eventually swapped out shmem page.
 */
int shmem_unuse(swp_entry_t entry, struct page *page)
{
	struct list_head *p, *next;
	struct shmem_inode_info *info;
	int found = 0;

1011
	mutex_lock(&shmem_swaplist_mutex);
L
Linus Torvalds 已提交
1012 1013
	list_for_each_safe(p, next, &shmem_swaplist) {
		info = list_entry(p, struct shmem_inode_info, swaplist);
H
Hugh Dickins 已提交
1014
		found = shmem_unuse_inode(info, entry, page);
1015
		cond_resched();
1016 1017
		if (found)
			goto out;
L
Linus Torvalds 已提交
1018
	}
1019
	mutex_unlock(&shmem_swaplist_mutex);
H
Hugh Dickins 已提交
1020 1021 1022 1023 1024 1025 1026 1027
	/*
	 * Can some race bring us here?  We've been holding page lock,
	 * so I think not; but would rather try again later than BUG()
	 */
	unlock_page(page);
	page_cache_release(page);
out:
	return (found < 0) ? found : 0;
L
Linus Torvalds 已提交
1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047
}

/*
 * Move the page from the page cache to the swap cache.
 */
static int shmem_writepage(struct page *page, struct writeback_control *wbc)
{
	struct shmem_inode_info *info;
	swp_entry_t *entry, swap;
	struct address_space *mapping;
	unsigned long index;
	struct inode *inode;

	BUG_ON(!PageLocked(page));
	mapping = page->mapping;
	index = page->index;
	inode = mapping->host;
	info = SHMEM_I(inode);
	if (info->flags & VM_LOCKED)
		goto redirty;
1048
	if (!total_swap_pages)
L
Linus Torvalds 已提交
1049 1050
		goto redirty;

1051 1052 1053 1054 1055
	/*
	 * shmem_backing_dev_info's capabilities prevent regular writeback or
	 * sync from ever calling shmem_writepage; but a stacking filesystem
	 * may use the ->writepage of its underlying filesystem, in which case
	 * tmpfs should write out to swap only in response to memory pressure,
1056 1057 1058
	 * and not for the writeback threads or sync.  However, in those cases,
	 * we do still want to check if there's a redundant swappage to be
	 * discarded.
1059 1060 1061 1062 1063 1064
	 */
	if (wbc->for_reclaim)
		swap = get_swap_page();
	else
		swap.val = 0;

L
Linus Torvalds 已提交
1065 1066 1067 1068 1069 1070
	spin_lock(&info->lock);
	if (index >= info->next_index) {
		BUG_ON(!(info->flags & SHMEM_TRUNCATE));
		goto unlock;
	}
	entry = shmem_swp_entry(info, index, NULL);
1071 1072 1073 1074 1075 1076 1077 1078 1079
	if (entry->val) {
		/*
		 * The more uptodate page coming down from a stacked
		 * writepage should replace our old swappage.
		 */
		free_swap_and_cache(*entry);
		shmem_swp_set(info, entry, 0);
	}
	shmem_recalc_inode(inode);
L
Linus Torvalds 已提交
1080

1081
	if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1082
		remove_from_page_cache(page);
L
Linus Torvalds 已提交
1083 1084
		shmem_swp_set(info, entry, swap.val);
		shmem_swp_unmap(entry);
H
Hugh Dickins 已提交
1085 1086 1087 1088
		if (list_empty(&info->swaplist))
			inode = igrab(inode);
		else
			inode = NULL;
L
Linus Torvalds 已提交
1089
		spin_unlock(&info->lock);
H
Hugh Dickins 已提交
1090
		swap_shmem_alloc(swap);
1091
		BUG_ON(page_mapped(page));
1092
		page_cache_release(page);	/* pagecache ref */
H
Hugh Dickins 已提交
1093
		swap_writepage(page, wbc);
H
Hugh Dickins 已提交
1094 1095 1096 1097 1098 1099 1100
		if (inode) {
			mutex_lock(&shmem_swaplist_mutex);
			/* move instead of add in case we're racing */
			list_move_tail(&info->swaplist, &shmem_swaplist);
			mutex_unlock(&shmem_swaplist_mutex);
			iput(inode);
		}
L
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1101 1102 1103 1104 1105 1106
		return 0;
	}

	shmem_swp_unmap(entry);
unlock:
	spin_unlock(&info->lock);
1107 1108 1109 1110
	/*
	 * add_to_swap_cache() doesn't return -EEXIST, so we can safely
	 * clear SWAP_HAS_CACHE flag.
	 */
1111
	swapcache_free(swap, NULL);
L
Linus Torvalds 已提交
1112 1113
redirty:
	set_page_dirty(page);
1114 1115 1116 1117
	if (wbc->for_reclaim)
		return AOP_WRITEPAGE_ACTIVATE;	/* Return with page locked */
	unlock_page(page);
	return 0;
L
Linus Torvalds 已提交
1118 1119 1120
}

#ifdef CONFIG_NUMA
1121
#ifdef CONFIG_TMPFS
1122
static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1123
{
1124
	char buffer[64];
1125

1126
	if (!mpol || mpol->mode == MPOL_DEFAULT)
1127
		return;		/* show nothing */
1128

1129
	mpol_to_str(buffer, sizeof(buffer), mpol, 1);
1130 1131

	seq_printf(seq, ",mpol=%s", buffer);
1132
}
1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144

static struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
{
	struct mempolicy *mpol = NULL;
	if (sbinfo->mpol) {
		spin_lock(&sbinfo->stat_lock);	/* prevent replace/use races */
		mpol = sbinfo->mpol;
		mpol_get(mpol);
		spin_unlock(&sbinfo->stat_lock);
	}
	return mpol;
}
1145 1146
#endif /* CONFIG_TMPFS */

1147 1148
static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
			struct shmem_inode_info *info, unsigned long idx)
L
Linus Torvalds 已提交
1149
{
1150
	struct mempolicy mpol, *spol;
L
Linus Torvalds 已提交
1151
	struct vm_area_struct pvma;
1152
	struct page *page;
L
Linus Torvalds 已提交
1153

1154 1155 1156
	spol = mpol_cond_copy(&mpol,
				mpol_shared_policy_lookup(&info->policy, idx));

L
Linus Torvalds 已提交
1157
	/* Create a pseudo vma that just contains the policy */
1158
	pvma.vm_start = 0;
L
Linus Torvalds 已提交
1159
	pvma.vm_pgoff = idx;
1160
	pvma.vm_ops = NULL;
1161
	pvma.vm_policy = spol;
1162
	page = swapin_readahead(entry, gfp, &pvma, 0);
L
Linus Torvalds 已提交
1163 1164 1165
	return page;
}

1166 1167
static struct page *shmem_alloc_page(gfp_t gfp,
			struct shmem_inode_info *info, unsigned long idx)
L
Linus Torvalds 已提交
1168 1169 1170
{
	struct vm_area_struct pvma;

1171 1172
	/* Create a pseudo vma that just contains the policy */
	pvma.vm_start = 0;
L
Linus Torvalds 已提交
1173
	pvma.vm_pgoff = idx;
1174 1175
	pvma.vm_ops = NULL;
	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1176 1177 1178 1179 1180

	/*
	 * alloc_page_vma() will drop the shared policy reference
	 */
	return alloc_page_vma(gfp, &pvma, 0);
L
Linus Torvalds 已提交
1181
}
1182 1183
#else /* !CONFIG_NUMA */
#ifdef CONFIG_TMPFS
1184
static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
1185 1186 1187 1188
{
}
#endif /* CONFIG_TMPFS */

1189 1190
static inline struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
			struct shmem_inode_info *info, unsigned long idx)
L
Linus Torvalds 已提交
1191
{
1192
	return swapin_readahead(entry, gfp, NULL, 0);
L
Linus Torvalds 已提交
1193 1194
}

1195 1196
static inline struct page *shmem_alloc_page(gfp_t gfp,
			struct shmem_inode_info *info, unsigned long idx)
L
Linus Torvalds 已提交
1197
{
1198
	return alloc_page(gfp);
L
Linus Torvalds 已提交
1199
}
1200
#endif /* CONFIG_NUMA */
L
Linus Torvalds 已提交
1201

1202 1203 1204 1205 1206 1207 1208
#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
{
	return NULL;
}
#endif

L
Linus Torvalds 已提交
1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225
/*
 * shmem_getpage - either get the page from swap or allocate a new one
 *
 * If we allocate a new one we do not mark it dirty. That's up to the
 * vm. If we swap it in we mark it dirty since we also free the swap
 * entry since a page cannot live in both the swap and page cache
 */
static int shmem_getpage(struct inode *inode, unsigned long idx,
			struct page **pagep, enum sgp_type sgp, int *type)
{
	struct address_space *mapping = inode->i_mapping;
	struct shmem_inode_info *info = SHMEM_I(inode);
	struct shmem_sb_info *sbinfo;
	struct page *filepage = *pagep;
	struct page *swappage;
	swp_entry_t *entry;
	swp_entry_t swap;
1226
	gfp_t gfp;
L
Linus Torvalds 已提交
1227 1228 1229 1230
	int error;

	if (idx >= SHMEM_MAX_INDEX)
		return -EFBIG;
1231 1232

	if (type)
N
Nick Piggin 已提交
1233
		*type = 0;
1234

L
Linus Torvalds 已提交
1235 1236 1237 1238
	/*
	 * Normally, filepage is NULL on entry, and either found
	 * uptodate immediately, or allocated and zeroed, or read
	 * in under swappage, which is then assigned to filepage.
H
Hugh Dickins 已提交
1239
	 * But shmem_readpage (required for splice) passes in a locked
1240 1241
	 * filepage, which may be found not uptodate by other callers
	 * too, and may need to be copied from the swappage read in.
L
Linus Torvalds 已提交
1242 1243 1244 1245 1246 1247 1248
	 */
repeat:
	if (!filepage)
		filepage = find_lock_page(mapping, idx);
	if (filepage && PageUptodate(filepage))
		goto done;
	error = 0;
1249
	gfp = mapping_gfp_mask(mapping);
H
Hugh Dickins 已提交
1250 1251 1252 1253 1254 1255 1256 1257 1258 1259
	if (!filepage) {
		/*
		 * Try to preload while we can wait, to not make a habit of
		 * draining atomic reserves; but don't latch on to this cpu.
		 */
		error = radix_tree_preload(gfp & ~__GFP_HIGHMEM);
		if (error)
			goto failed;
		radix_tree_preload_end();
	}
L
Linus Torvalds 已提交
1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276

	spin_lock(&info->lock);
	shmem_recalc_inode(inode);
	entry = shmem_swp_alloc(info, idx, sgp);
	if (IS_ERR(entry)) {
		spin_unlock(&info->lock);
		error = PTR_ERR(entry);
		goto failed;
	}
	swap = *entry;

	if (swap.val) {
		/* Look it up and read it in.. */
		swappage = lookup_swap_cache(swap);
		if (!swappage) {
			shmem_swp_unmap(entry);
			/* here we actually do the io */
N
Nick Piggin 已提交
1277
			if (type && !(*type & VM_FAULT_MAJOR)) {
1278
				__count_vm_event(PGMAJFAULT);
N
Nick Piggin 已提交
1279
				*type |= VM_FAULT_MAJOR;
L
Linus Torvalds 已提交
1280
			}
1281
			spin_unlock(&info->lock);
1282
			swappage = shmem_swapin(swap, gfp, info, idx);
L
Linus Torvalds 已提交
1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303
			if (!swappage) {
				spin_lock(&info->lock);
				entry = shmem_swp_alloc(info, idx, sgp);
				if (IS_ERR(entry))
					error = PTR_ERR(entry);
				else {
					if (entry->val == swap.val)
						error = -ENOMEM;
					shmem_swp_unmap(entry);
				}
				spin_unlock(&info->lock);
				if (error)
					goto failed;
				goto repeat;
			}
			wait_on_page_locked(swappage);
			page_cache_release(swappage);
			goto repeat;
		}

		/* We have to do this with page locked to prevent races */
N
Nick Piggin 已提交
1304
		if (!trylock_page(swappage)) {
L
Linus Torvalds 已提交
1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			wait_on_page_locked(swappage);
			page_cache_release(swappage);
			goto repeat;
		}
		if (PageWriteback(swappage)) {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			wait_on_page_writeback(swappage);
			unlock_page(swappage);
			page_cache_release(swappage);
			goto repeat;
		}
		if (!PageUptodate(swappage)) {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			unlock_page(swappage);
			page_cache_release(swappage);
			error = -EIO;
			goto failed;
		}

		if (filepage) {
			shmem_swp_set(info, entry, 0);
			shmem_swp_unmap(entry);
			delete_from_swap_cache(swappage);
			spin_unlock(&info->lock);
			copy_highpage(filepage, swappage);
			unlock_page(swappage);
			page_cache_release(swappage);
			flush_dcache_page(filepage);
			SetPageUptodate(filepage);
			set_page_dirty(filepage);
			swap_free(swap);
N
Nick Piggin 已提交
1340 1341
		} else if (!(error = add_to_page_cache_locked(swappage, mapping,
					idx, GFP_NOWAIT))) {
L
Linus Torvalds 已提交
1342 1343 1344
			info->flags |= SHMEM_PAGEIN;
			shmem_swp_set(info, entry, 0);
			shmem_swp_unmap(entry);
1345
			delete_from_swap_cache(swappage);
L
Linus Torvalds 已提交
1346 1347
			spin_unlock(&info->lock);
			filepage = swappage;
1348
			set_page_dirty(filepage);
L
Linus Torvalds 已提交
1349 1350 1351 1352
			swap_free(swap);
		} else {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
1353
			if (error == -ENOMEM) {
1354 1355 1356 1357 1358 1359
				/*
				 * reclaim from proper memory cgroup and
				 * call memcg's OOM if needed.
				 */
				error = mem_cgroup_shmem_charge_fallback(
								swappage,
1360
								current->mm,
1361
								gfp);
1362 1363 1364
				if (error) {
					unlock_page(swappage);
					page_cache_release(swappage);
1365
					goto failed;
1366
				}
1367
			}
1368 1369
			unlock_page(swappage);
			page_cache_release(swappage);
L
Linus Torvalds 已提交
1370 1371 1372 1373 1374 1375
			goto repeat;
		}
	} else if (sgp == SGP_READ && !filepage) {
		shmem_swp_unmap(entry);
		filepage = find_get_page(mapping, idx);
		if (filepage &&
N
Nick Piggin 已提交
1376
		    (!PageUptodate(filepage) || !trylock_page(filepage))) {
L
Linus Torvalds 已提交
1377 1378 1379 1380 1381 1382 1383 1384 1385 1386
			spin_unlock(&info->lock);
			wait_on_page_locked(filepage);
			page_cache_release(filepage);
			filepage = NULL;
			goto repeat;
		}
		spin_unlock(&info->lock);
	} else {
		shmem_swp_unmap(entry);
		sbinfo = SHMEM_SB(inode->i_sb);
1387
		if (sbinfo->max_blocks) {
L
Linus Torvalds 已提交
1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405
			spin_lock(&sbinfo->stat_lock);
			if (sbinfo->free_blocks == 0 ||
			    shmem_acct_block(info->flags)) {
				spin_unlock(&sbinfo->stat_lock);
				spin_unlock(&info->lock);
				error = -ENOSPC;
				goto failed;
			}
			sbinfo->free_blocks--;
			inode->i_blocks += BLOCKS_PER_PAGE;
			spin_unlock(&sbinfo->stat_lock);
		} else if (shmem_acct_block(info->flags)) {
			spin_unlock(&info->lock);
			error = -ENOSPC;
			goto failed;
		}

		if (!filepage) {
1406 1407
			int ret;

L
Linus Torvalds 已提交
1408
			spin_unlock(&info->lock);
1409
			filepage = shmem_alloc_page(gfp, info, idx);
L
Linus Torvalds 已提交
1410 1411 1412 1413 1414 1415
			if (!filepage) {
				shmem_unacct_blocks(info->flags, 1);
				shmem_free_blocks(inode, 1);
				error = -ENOMEM;
				goto failed;
			}
R
Rik van Riel 已提交
1416
			SetPageSwapBacked(filepage);
L
Linus Torvalds 已提交
1417

1418 1419
			/* Precharge page while we can wait, compensate after */
			error = mem_cgroup_cache_charge(filepage, current->mm,
K
KAMEZAWA Hiroyuki 已提交
1420
					GFP_KERNEL);
1421 1422 1423 1424 1425 1426 1427 1428
			if (error) {
				page_cache_release(filepage);
				shmem_unacct_blocks(info->flags, 1);
				shmem_free_blocks(inode, 1);
				filepage = NULL;
				goto failed;
			}

L
Linus Torvalds 已提交
1429 1430 1431 1432 1433 1434 1435 1436
			spin_lock(&info->lock);
			entry = shmem_swp_alloc(info, idx, sgp);
			if (IS_ERR(entry))
				error = PTR_ERR(entry);
			else {
				swap = *entry;
				shmem_swp_unmap(entry);
			}
1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447
			ret = error || swap.val;
			if (ret)
				mem_cgroup_uncharge_cache_page(filepage);
			else
				ret = add_to_page_cache_lru(filepage, mapping,
						idx, GFP_NOWAIT);
			/*
			 * At add_to_page_cache_lru() failure, uncharge will
			 * be done automatically.
			 */
			if (ret) {
L
Linus Torvalds 已提交
1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461
				spin_unlock(&info->lock);
				page_cache_release(filepage);
				shmem_unacct_blocks(info->flags, 1);
				shmem_free_blocks(inode, 1);
				filepage = NULL;
				if (error)
					goto failed;
				goto repeat;
			}
			info->flags |= SHMEM_PAGEIN;
		}

		info->alloced++;
		spin_unlock(&info->lock);
1462
		clear_highpage(filepage);
L
Linus Torvalds 已提交
1463 1464
		flush_dcache_page(filepage);
		SetPageUptodate(filepage);
1465 1466
		if (sgp == SGP_DIRTY)
			set_page_dirty(filepage);
L
Linus Torvalds 已提交
1467 1468
	}
done:
H
Hugh Dickins 已提交
1469
	*pagep = filepage;
L
Linus Torvalds 已提交
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479
	return 0;

failed:
	if (*pagep != filepage) {
		unlock_page(filepage);
		page_cache_release(filepage);
	}
	return error;
}

N
Nick Piggin 已提交
1480
static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
L
Linus Torvalds 已提交
1481
{
1482
	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1483
	int error;
N
Nick Piggin 已提交
1484
	int ret;
L
Linus Torvalds 已提交
1485

N
Nick Piggin 已提交
1486 1487
	if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
		return VM_FAULT_SIGBUS;
1488

1489
	error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
N
Nick Piggin 已提交
1490 1491
	if (error)
		return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
L
Linus Torvalds 已提交
1492

N
Nick Piggin 已提交
1493
	return ret | VM_FAULT_LOCKED;
L
Linus Torvalds 已提交
1494 1495 1496
}

#ifdef CONFIG_NUMA
A
Adrian Bunk 已提交
1497
static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
L
Linus Torvalds 已提交
1498
{
1499
	struct inode *i = vma->vm_file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1500 1501 1502
	return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
}

A
Adrian Bunk 已提交
1503 1504
static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
					  unsigned long addr)
L
Linus Torvalds 已提交
1505
{
1506
	struct inode *i = vma->vm_file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1507 1508 1509 1510 1511 1512 1513 1514 1515
	unsigned long idx;

	idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
	return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx);
}
#endif

int shmem_lock(struct file *file, int lock, struct user_struct *user)
{
1516
	struct inode *inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1517 1518 1519 1520 1521 1522 1523 1524
	struct shmem_inode_info *info = SHMEM_I(inode);
	int retval = -ENOMEM;

	spin_lock(&info->lock);
	if (lock && !(info->flags & VM_LOCKED)) {
		if (!user_shm_lock(inode->i_size, user))
			goto out_nomem;
		info->flags |= VM_LOCKED;
1525
		mapping_set_unevictable(file->f_mapping);
L
Linus Torvalds 已提交
1526 1527 1528 1529
	}
	if (!lock && (info->flags & VM_LOCKED) && user) {
		user_shm_unlock(inode->i_size, user);
		info->flags &= ~VM_LOCKED;
1530 1531
		mapping_clear_unevictable(file->f_mapping);
		scan_mapping_unevictable_pages(file->f_mapping);
L
Linus Torvalds 已提交
1532 1533
	}
	retval = 0;
1534

L
Linus Torvalds 已提交
1535 1536 1537 1538 1539
out_nomem:
	spin_unlock(&info->lock);
	return retval;
}

1540
static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
1541 1542 1543
{
	file_accessed(file);
	vma->vm_ops = &shmem_vm_ops;
N
Nick Piggin 已提交
1544
	vma->vm_flags |= VM_CAN_NONLINEAR;
L
Linus Torvalds 已提交
1545 1546 1547
	return 0;
}

1548 1549
static struct inode *shmem_get_inode(struct super_block *sb, int mode,
					dev_t dev, unsigned long flags)
L
Linus Torvalds 已提交
1550 1551 1552 1553 1554
{
	struct inode *inode;
	struct shmem_inode_info *info;
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);

1555 1556
	if (shmem_reserve_inode(sb))
		return NULL;
L
Linus Torvalds 已提交
1557 1558 1559 1560

	inode = new_inode(sb);
	if (inode) {
		inode->i_mode = mode;
1561 1562
		inode->i_uid = current_fsuid();
		inode->i_gid = current_fsgid();
L
Linus Torvalds 已提交
1563 1564 1565
		inode->i_blocks = 0;
		inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
		inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
1566
		inode->i_generation = get_seconds();
L
Linus Torvalds 已提交
1567 1568 1569
		info = SHMEM_I(inode);
		memset(info, 0, (char *)inode - (char *)info);
		spin_lock_init(&info->lock);
1570
		info->flags = flags & VM_NORESERVE;
L
Linus Torvalds 已提交
1571
		INIT_LIST_HEAD(&info->swaplist);
1572
		cache_no_acl(inode);
L
Linus Torvalds 已提交
1573 1574 1575

		switch (mode & S_IFMT) {
		default:
1576
			inode->i_op = &shmem_special_inode_operations;
L
Linus Torvalds 已提交
1577 1578 1579
			init_special_inode(inode, mode, dev);
			break;
		case S_IFREG:
1580
			inode->i_mapping->a_ops = &shmem_aops;
L
Linus Torvalds 已提交
1581 1582
			inode->i_op = &shmem_inode_operations;
			inode->i_fop = &shmem_file_operations;
1583 1584
			mpol_shared_policy_init(&info->policy,
						 shmem_get_sbmpol(sbinfo));
L
Linus Torvalds 已提交
1585 1586
			break;
		case S_IFDIR:
1587
			inc_nlink(inode);
L
Linus Torvalds 已提交
1588 1589 1590 1591 1592 1593 1594 1595 1596 1597
			/* Some things misbehave if size == 0 on a directory */
			inode->i_size = 2 * BOGO_DIRENT_SIZE;
			inode->i_op = &shmem_dir_inode_operations;
			inode->i_fop = &simple_dir_operations;
			break;
		case S_IFLNK:
			/*
			 * Must not load anything in the rbtree,
			 * mpol_free_shared_policy will not be called.
			 */
1598
			mpol_shared_policy_init(&info->policy, NULL);
L
Linus Torvalds 已提交
1599 1600
			break;
		}
1601 1602
	} else
		shmem_free_inode(sb);
L
Linus Torvalds 已提交
1603 1604 1605 1606
	return inode;
}

#ifdef CONFIG_TMPFS
1607 1608
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_symlink_inline_operations;
L
Linus Torvalds 已提交
1609 1610

/*
N
Nick Piggin 已提交
1611
 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1612 1613
 * but providing them allows a tmpfs file to be used for splice, sendfile, and
 * below the loop driver, in the generic fashion that many filesystems support.
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 */
1615 1616 1617 1618 1619 1620 1621 1622
static int shmem_readpage(struct file *file, struct page *page)
{
	struct inode *inode = page->mapping->host;
	int error = shmem_getpage(inode, page->index, &page, SGP_CACHE, NULL);
	unlock_page(page);
	return error;
}

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static int
N
Nick Piggin 已提交
1624 1625 1626
shmem_write_begin(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned flags,
			struct page **pagep, void **fsdata)
L
Linus Torvalds 已提交
1627
{
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1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640
	struct inode *inode = mapping->host;
	pgoff_t index = pos >> PAGE_CACHE_SHIFT;
	*pagep = NULL;
	return shmem_getpage(inode, index, pagep, SGP_WRITE, NULL);
}

static int
shmem_write_end(struct file *file, struct address_space *mapping,
			loff_t pos, unsigned len, unsigned copied,
			struct page *page, void *fsdata)
{
	struct inode *inode = mapping->host;

H
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1641 1642 1643
	if (pos + copied > inode->i_size)
		i_size_write(inode, pos + copied);

N
Nick Piggin 已提交
1644
	set_page_dirty(page);
1645
	unlock_page(page);
N
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1646 1647 1648
	page_cache_release(page);

	return copied;
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}

static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
{
1653
	struct inode *inode = filp->f_path.dentry->d_inode;
L
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	struct address_space *mapping = inode->i_mapping;
	unsigned long index, offset;
1656 1657 1658 1659 1660 1661 1662 1663 1664
	enum sgp_type sgp = SGP_READ;

	/*
	 * Might this read be for a stacking filesystem?  Then when reading
	 * holes of a sparse file, we actually need to allocate those pages,
	 * and even mark them dirty, so it cannot exceed the max_blocks limit.
	 */
	if (segment_eq(get_fs(), KERNEL_DS))
		sgp = SGP_DIRTY;
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1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682

	index = *ppos >> PAGE_CACHE_SHIFT;
	offset = *ppos & ~PAGE_CACHE_MASK;

	for (;;) {
		struct page *page = NULL;
		unsigned long end_index, nr, ret;
		loff_t i_size = i_size_read(inode);

		end_index = i_size >> PAGE_CACHE_SHIFT;
		if (index > end_index)
			break;
		if (index == end_index) {
			nr = i_size & ~PAGE_CACHE_MASK;
			if (nr <= offset)
				break;
		}

1683
		desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
L
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1684 1685 1686 1687 1688
		if (desc->error) {
			if (desc->error == -EINVAL)
				desc->error = 0;
			break;
		}
H
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1689 1690
		if (page)
			unlock_page(page);
L
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1691 1692 1693

		/*
		 * We must evaluate after, since reads (unlike writes)
1694
		 * are called without i_mutex protection against truncate
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1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721
		 */
		nr = PAGE_CACHE_SIZE;
		i_size = i_size_read(inode);
		end_index = i_size >> PAGE_CACHE_SHIFT;
		if (index == end_index) {
			nr = i_size & ~PAGE_CACHE_MASK;
			if (nr <= offset) {
				if (page)
					page_cache_release(page);
				break;
			}
		}
		nr -= offset;

		if (page) {
			/*
			 * If users can be writing to this page using arbitrary
			 * virtual addresses, take care about potential aliasing
			 * before reading the page on the kernel side.
			 */
			if (mapping_writably_mapped(mapping))
				flush_dcache_page(page);
			/*
			 * Mark the page accessed if we read the beginning.
			 */
			if (!offset)
				mark_page_accessed(page);
N
Nick Piggin 已提交
1722
		} else {
L
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1723
			page = ZERO_PAGE(0);
N
Nick Piggin 已提交
1724 1725
			page_cache_get(page);
		}
L
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		/*
		 * Ok, we have the page, and it's up-to-date, so
		 * now we can copy it to user space...
		 *
		 * The actor routine returns how many bytes were actually used..
		 * NOTE! This may not be the same as how much of a user buffer
		 * we filled up (we may be padding etc), so we can only update
		 * "pos" here (the actor routine has to update the user buffer
		 * pointers and the remaining count).
		 */
		ret = actor(desc, page, offset, nr);
		offset += ret;
		index += offset >> PAGE_CACHE_SHIFT;
		offset &= ~PAGE_CACHE_MASK;

		page_cache_release(page);
		if (ret != nr || !desc->count)
			break;

		cond_resched();
	}

	*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
	file_accessed(filp);
}

H
Hugh Dickins 已提交
1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784
static ssize_t shmem_file_aio_read(struct kiocb *iocb,
		const struct iovec *iov, unsigned long nr_segs, loff_t pos)
{
	struct file *filp = iocb->ki_filp;
	ssize_t retval;
	unsigned long seg;
	size_t count;
	loff_t *ppos = &iocb->ki_pos;

	retval = generic_segment_checks(iov, &nr_segs, &count, VERIFY_WRITE);
	if (retval)
		return retval;

	for (seg = 0; seg < nr_segs; seg++) {
		read_descriptor_t desc;

		desc.written = 0;
		desc.arg.buf = iov[seg].iov_base;
		desc.count = iov[seg].iov_len;
		if (desc.count == 0)
			continue;
		desc.error = 0;
		do_shmem_file_read(filp, ppos, &desc, file_read_actor);
		retval += desc.written;
		if (desc.error) {
			retval = retval ?: desc.error;
			break;
		}
		if (desc.count > 0)
			break;
	}
	return retval;
L
Linus Torvalds 已提交
1785 1786
}

1787
static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
L
Linus Torvalds 已提交
1788
{
1789
	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
L
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1790 1791 1792 1793

	buf->f_type = TMPFS_MAGIC;
	buf->f_bsize = PAGE_CACHE_SIZE;
	buf->f_namelen = NAME_MAX;
1794 1795
	spin_lock(&sbinfo->stat_lock);
	if (sbinfo->max_blocks) {
L
Linus Torvalds 已提交
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		buf->f_blocks = sbinfo->max_blocks;
		buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
1798 1799
	}
	if (sbinfo->max_inodes) {
L
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1800 1801 1802 1803
		buf->f_files = sbinfo->max_inodes;
		buf->f_ffree = sbinfo->free_inodes;
	}
	/* else leave those fields 0 like simple_statfs */
1804
	spin_unlock(&sbinfo->stat_lock);
L
Linus Torvalds 已提交
1805 1806 1807 1808 1809 1810 1811 1812 1813
	return 0;
}

/*
 * File creation. Allocate an inode, and we're done..
 */
static int
shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
1814
	struct inode *inode;
L
Linus Torvalds 已提交
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	int error = -ENOSPC;

1817
	inode = shmem_get_inode(dir->i_sb, mode, dev, VM_NORESERVE);
L
Linus Torvalds 已提交
1818
	if (inode) {
1819 1820 1821 1822 1823 1824 1825
		error = security_inode_init_security(inode, dir, NULL, NULL,
						     NULL);
		if (error) {
			if (error != -EOPNOTSUPP) {
				iput(inode);
				return error;
			}
1826
		}
1827 1828
#ifdef CONFIG_TMPFS_POSIX_ACL
		error = generic_acl_init(inode, dir);
1829 1830 1831
		if (error) {
			iput(inode);
			return error;
1832
		}
A
Al Viro 已提交
1833 1834
#else
		error = 0;
1835
#endif
L
Linus Torvalds 已提交
1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854
		if (dir->i_mode & S_ISGID) {
			inode->i_gid = dir->i_gid;
			if (S_ISDIR(mode))
				inode->i_mode |= S_ISGID;
		}
		dir->i_size += BOGO_DIRENT_SIZE;
		dir->i_ctime = dir->i_mtime = CURRENT_TIME;
		d_instantiate(dentry, inode);
		dget(dentry); /* Extra count - pin the dentry in core */
	}
	return error;
}

static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
	int error;

	if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
		return error;
1855
	inc_nlink(dir);
L
Linus Torvalds 已提交
1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870
	return 0;
}

static int shmem_create(struct inode *dir, struct dentry *dentry, int mode,
		struct nameidata *nd)
{
	return shmem_mknod(dir, dentry, mode | S_IFREG, 0);
}

/*
 * Link a file..
 */
static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = old_dentry->d_inode;
1871
	int ret;
L
Linus Torvalds 已提交
1872 1873 1874 1875 1876 1877

	/*
	 * No ordinary (disk based) filesystem counts links as inodes;
	 * but each new link needs a new dentry, pinning lowmem, and
	 * tmpfs dentries cannot be pruned until they are unlinked.
	 */
1878 1879 1880
	ret = shmem_reserve_inode(inode->i_sb);
	if (ret)
		goto out;
L
Linus Torvalds 已提交
1881 1882 1883

	dir->i_size += BOGO_DIRENT_SIZE;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1884
	inc_nlink(inode);
L
Linus Torvalds 已提交
1885 1886 1887
	atomic_inc(&inode->i_count);	/* New dentry reference */
	dget(dentry);		/* Extra pinning count for the created dentry */
	d_instantiate(dentry, inode);
1888 1889
out:
	return ret;
L
Linus Torvalds 已提交
1890 1891 1892 1893 1894 1895
}

static int shmem_unlink(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = dentry->d_inode;

1896 1897
	if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
		shmem_free_inode(inode->i_sb);
L
Linus Torvalds 已提交
1898 1899 1900

	dir->i_size -= BOGO_DIRENT_SIZE;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1901
	drop_nlink(inode);
L
Linus Torvalds 已提交
1902 1903 1904 1905 1906 1907 1908 1909 1910
	dput(dentry);	/* Undo the count from "create" - this does all the work */
	return 0;
}

static int shmem_rmdir(struct inode *dir, struct dentry *dentry)
{
	if (!simple_empty(dentry))
		return -ENOTEMPTY;

1911 1912
	drop_nlink(dentry->d_inode);
	drop_nlink(dir);
L
Linus Torvalds 已提交
1913 1914 1915 1916 1917 1918 1919 1920 1921 1922 1923 1924 1925 1926 1927 1928 1929 1930 1931 1932
	return shmem_unlink(dir, dentry);
}

/*
 * The VFS layer already does all the dentry stuff for rename,
 * we just have to decrement the usage count for the target if
 * it exists so that the VFS layer correctly free's it when it
 * gets overwritten.
 */
static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
{
	struct inode *inode = old_dentry->d_inode;
	int they_are_dirs = S_ISDIR(inode->i_mode);

	if (!simple_empty(new_dentry))
		return -ENOTEMPTY;

	if (new_dentry->d_inode) {
		(void) shmem_unlink(new_dir, new_dentry);
		if (they_are_dirs)
1933
			drop_nlink(old_dir);
L
Linus Torvalds 已提交
1934
	} else if (they_are_dirs) {
1935
		drop_nlink(old_dir);
1936
		inc_nlink(new_dir);
L
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1937 1938 1939 1940 1941 1942 1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959
	}

	old_dir->i_size -= BOGO_DIRENT_SIZE;
	new_dir->i_size += BOGO_DIRENT_SIZE;
	old_dir->i_ctime = old_dir->i_mtime =
	new_dir->i_ctime = new_dir->i_mtime =
	inode->i_ctime = CURRENT_TIME;
	return 0;
}

static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname)
{
	int error;
	int len;
	struct inode *inode;
	struct page *page = NULL;
	char *kaddr;
	struct shmem_inode_info *info;

	len = strlen(symname) + 1;
	if (len > PAGE_CACHE_SIZE)
		return -ENAMETOOLONG;

1960
	inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
L
Linus Torvalds 已提交
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	if (!inode)
		return -ENOSPC;

1964 1965 1966 1967 1968 1969 1970 1971 1972 1973
	error = security_inode_init_security(inode, dir, NULL, NULL,
					     NULL);
	if (error) {
		if (error != -EOPNOTSUPP) {
			iput(inode);
			return error;
		}
		error = 0;
	}

L
Linus Torvalds 已提交
1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 1985
	info = SHMEM_I(inode);
	inode->i_size = len-1;
	if (len <= (char *)inode - (char *)info) {
		/* do it inline */
		memcpy(info, symname, len);
		inode->i_op = &shmem_symlink_inline_operations;
	} else {
		error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
		if (error) {
			iput(inode);
			return error;
		}
1986
		inode->i_mapping->a_ops = &shmem_aops;
L
Linus Torvalds 已提交
1987 1988 1989 1990 1991
		inode->i_op = &shmem_symlink_inode_operations;
		kaddr = kmap_atomic(page, KM_USER0);
		memcpy(kaddr, symname, len);
		kunmap_atomic(kaddr, KM_USER0);
		set_page_dirty(page);
1992
		unlock_page(page);
L
Linus Torvalds 已提交
1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003
		page_cache_release(page);
	}
	if (dir->i_mode & S_ISGID)
		inode->i_gid = dir->i_gid;
	dir->i_size += BOGO_DIRENT_SIZE;
	dir->i_ctime = dir->i_mtime = CURRENT_TIME;
	d_instantiate(dentry, inode);
	dget(dentry);
	return 0;
}

2004
static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
L
Linus Torvalds 已提交
2005 2006
{
	nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
2007
	return NULL;
L
Linus Torvalds 已提交
2008 2009
}

2010
static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
L
Linus Torvalds 已提交
2011 2012 2013 2014
{
	struct page *page = NULL;
	int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
	nd_set_link(nd, res ? ERR_PTR(res) : kmap(page));
H
Hugh Dickins 已提交
2015 2016
	if (page)
		unlock_page(page);
2017
	return page;
L
Linus Torvalds 已提交
2018 2019
}

2020
static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
L
Linus Torvalds 已提交
2021 2022
{
	if (!IS_ERR(nd_get_link(nd))) {
2023
		struct page *page = cookie;
L
Linus Torvalds 已提交
2024 2025 2026 2027 2028 2029
		kunmap(page);
		mark_page_accessed(page);
		page_cache_release(page);
	}
}

2030
static const struct inode_operations shmem_symlink_inline_operations = {
L
Linus Torvalds 已提交
2031 2032 2033 2034
	.readlink	= generic_readlink,
	.follow_link	= shmem_follow_link_inline,
};

2035
static const struct inode_operations shmem_symlink_inode_operations = {
L
Linus Torvalds 已提交
2036 2037 2038 2039 2040 2041
	.truncate	= shmem_truncate,
	.readlink	= generic_readlink,
	.follow_link	= shmem_follow_link,
	.put_link	= shmem_put_link,
};

2042
#ifdef CONFIG_TMPFS_POSIX_ACL
2043
/*
2044 2045 2046 2047 2048 2049
 * Superblocks without xattr inode operations will get security.* xattr
 * support from the VFS "for free". As soon as we have any other xattrs
 * like ACLs, we also need to implement the security.* handlers at
 * filesystem level, though.
 */

2050
static size_t shmem_xattr_security_list(struct dentry *dentry, char *list,
2051
					size_t list_len, const char *name,
2052
					size_t name_len, int handler_flags)
2053
{
2054
	return security_inode_listsecurity(dentry->d_inode, list, list_len);
2055 2056
}

2057 2058
static int shmem_xattr_security_get(struct dentry *dentry, const char *name,
		void *buffer, size_t size, int handler_flags)
2059 2060 2061
{
	if (strcmp(name, "") == 0)
		return -EINVAL;
2062
	return xattr_getsecurity(dentry->d_inode, name, buffer, size);
2063 2064
}

2065 2066
static int shmem_xattr_security_set(struct dentry *dentry, const char *name,
		const void *value, size_t size, int flags, int handler_flags)
2067 2068 2069
{
	if (strcmp(name, "") == 0)
		return -EINVAL;
2070 2071
	return security_inode_setsecurity(dentry->d_inode, name, value,
					  size, flags);
2072 2073
}

2074
static struct xattr_handler shmem_xattr_security_handler = {
2075 2076 2077 2078 2079 2080 2081
	.prefix = XATTR_SECURITY_PREFIX,
	.list   = shmem_xattr_security_list,
	.get    = shmem_xattr_security_get,
	.set    = shmem_xattr_security_set,
};

static struct xattr_handler *shmem_xattr_handlers[] = {
2082 2083
	&generic_acl_access_handler,
	&generic_acl_default_handler,
2084 2085 2086 2087 2088
	&shmem_xattr_security_handler,
	NULL
};
#endif

2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101
static struct dentry *shmem_get_parent(struct dentry *child)
{
	return ERR_PTR(-ESTALE);
}

static int shmem_match(struct inode *ino, void *vfh)
{
	__u32 *fh = vfh;
	__u64 inum = fh[2];
	inum = (inum << 32) | fh[1];
	return ino->i_ino == inum && fh[0] == ino->i_generation;
}

C
Christoph Hellwig 已提交
2102 2103
static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
		struct fid *fid, int fh_len, int fh_type)
2104 2105
{
	struct inode *inode;
C
Christoph Hellwig 已提交
2106 2107 2108 2109 2110 2111
	struct dentry *dentry = NULL;
	u64 inum = fid->raw[2];
	inum = (inum << 32) | fid->raw[1];

	if (fh_len < 3)
		return NULL;
2112

C
Christoph Hellwig 已提交
2113 2114
	inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
			shmem_match, fid->raw);
2115
	if (inode) {
C
Christoph Hellwig 已提交
2116
		dentry = d_find_alias(inode);
2117 2118 2119
		iput(inode);
	}

C
Christoph Hellwig 已提交
2120
	return dentry;
2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134 2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152
}

static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
				int connectable)
{
	struct inode *inode = dentry->d_inode;

	if (*len < 3)
		return 255;

	if (hlist_unhashed(&inode->i_hash)) {
		/* Unfortunately insert_inode_hash is not idempotent,
		 * so as we hash inodes here rather than at creation
		 * time, we need a lock to ensure we only try
		 * to do it once
		 */
		static DEFINE_SPINLOCK(lock);
		spin_lock(&lock);
		if (hlist_unhashed(&inode->i_hash))
			__insert_inode_hash(inode,
					    inode->i_ino + inode->i_generation);
		spin_unlock(&lock);
	}

	fh[0] = inode->i_generation;
	fh[1] = inode->i_ino;
	fh[2] = ((__u64)inode->i_ino) >> 32;

	*len = 3;
	return 1;
}

2153
static const struct export_operations shmem_export_ops = {
2154 2155
	.get_parent     = shmem_get_parent,
	.encode_fh      = shmem_encode_fh,
C
Christoph Hellwig 已提交
2156
	.fh_to_dentry	= shmem_fh_to_dentry,
2157 2158
};

2159 2160
static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
			       bool remount)
L
Linus Torvalds 已提交
2161 2162 2163
{
	char *this_char, *value, *rest;

2164 2165 2166 2167 2168 2169 2170 2171 2172 2173 2174 2175 2176 2177 2178 2179 2180
	while (options != NULL) {
		this_char = options;
		for (;;) {
			/*
			 * NUL-terminate this option: unfortunately,
			 * mount options form a comma-separated list,
			 * but mpol's nodelist may also contain commas.
			 */
			options = strchr(options, ',');
			if (options == NULL)
				break;
			options++;
			if (!isdigit(*options)) {
				options[-1] = '\0';
				break;
			}
		}
L
Linus Torvalds 已提交
2181 2182 2183 2184 2185 2186 2187 2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202
		if (!*this_char)
			continue;
		if ((value = strchr(this_char,'=')) != NULL) {
			*value++ = 0;
		} else {
			printk(KERN_ERR
			    "tmpfs: No value for mount option '%s'\n",
			    this_char);
			return 1;
		}

		if (!strcmp(this_char,"size")) {
			unsigned long long size;
			size = memparse(value,&rest);
			if (*rest == '%') {
				size <<= PAGE_SHIFT;
				size *= totalram_pages;
				do_div(size, 100);
				rest++;
			}
			if (*rest)
				goto bad_val;
2203 2204
			sbinfo->max_blocks =
				DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
L
Linus Torvalds 已提交
2205
		} else if (!strcmp(this_char,"nr_blocks")) {
2206
			sbinfo->max_blocks = memparse(value, &rest);
L
Linus Torvalds 已提交
2207 2208 2209
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"nr_inodes")) {
2210
			sbinfo->max_inodes = memparse(value, &rest);
L
Linus Torvalds 已提交
2211 2212 2213
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"mode")) {
2214
			if (remount)
L
Linus Torvalds 已提交
2215
				continue;
2216
			sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
L
Linus Torvalds 已提交
2217 2218 2219
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"uid")) {
2220
			if (remount)
L
Linus Torvalds 已提交
2221
				continue;
2222
			sbinfo->uid = simple_strtoul(value, &rest, 0);
L
Linus Torvalds 已提交
2223 2224 2225
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"gid")) {
2226
			if (remount)
L
Linus Torvalds 已提交
2227
				continue;
2228
			sbinfo->gid = simple_strtoul(value, &rest, 0);
L
Linus Torvalds 已提交
2229 2230
			if (*rest)
				goto bad_val;
2231
		} else if (!strcmp(this_char,"mpol")) {
2232
			if (mpol_parse_str(value, &sbinfo->mpol, 1))
2233
				goto bad_val;
L
Linus Torvalds 已提交
2234 2235 2236 2237 2238 2239 2240 2241 2242 2243 2244 2245 2246 2247 2248 2249 2250 2251
		} else {
			printk(KERN_ERR "tmpfs: Bad mount option %s\n",
			       this_char);
			return 1;
		}
	}
	return 0;

bad_val:
	printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
	       value, this_char);
	return 1;

}

static int shmem_remount_fs(struct super_block *sb, int *flags, char *data)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
2252
	struct shmem_sb_info config = *sbinfo;
2253 2254 2255 2256
	unsigned long blocks;
	unsigned long inodes;
	int error = -EINVAL;

2257
	if (shmem_parse_options(data, &config, true))
2258
		return error;
L
Linus Torvalds 已提交
2259

2260 2261 2262
	spin_lock(&sbinfo->stat_lock);
	blocks = sbinfo->max_blocks - sbinfo->free_blocks;
	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2263
	if (config.max_blocks < blocks)
2264
		goto out;
2265
	if (config.max_inodes < inodes)
2266 2267 2268 2269 2270 2271 2272
		goto out;
	/*
	 * Those tests also disallow limited->unlimited while any are in
	 * use, so i_blocks will always be zero when max_blocks is zero;
	 * but we must separately disallow unlimited->limited, because
	 * in that case we have no record of how much is already in use.
	 */
2273
	if (config.max_blocks && !sbinfo->max_blocks)
2274
		goto out;
2275
	if (config.max_inodes && !sbinfo->max_inodes)
2276 2277 2278
		goto out;

	error = 0;
2279 2280 2281 2282
	sbinfo->max_blocks  = config.max_blocks;
	sbinfo->free_blocks = config.max_blocks - blocks;
	sbinfo->max_inodes  = config.max_inodes;
	sbinfo->free_inodes = config.max_inodes - inodes;
2283 2284 2285

	mpol_put(sbinfo->mpol);
	sbinfo->mpol        = config.mpol;	/* transfers initial ref */
2286 2287 2288
out:
	spin_unlock(&sbinfo->stat_lock);
	return error;
L
Linus Torvalds 已提交
2289
}
2290 2291 2292 2293 2294 2295 2296 2297 2298 2299 2300 2301 2302 2303 2304 2305

static int shmem_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
	struct shmem_sb_info *sbinfo = SHMEM_SB(vfs->mnt_sb);

	if (sbinfo->max_blocks != shmem_default_max_blocks())
		seq_printf(seq, ",size=%luk",
			sbinfo->max_blocks << (PAGE_CACHE_SHIFT - 10));
	if (sbinfo->max_inodes != shmem_default_max_inodes())
		seq_printf(seq, ",nr_inodes=%lu", sbinfo->max_inodes);
	if (sbinfo->mode != (S_IRWXUGO | S_ISVTX))
		seq_printf(seq, ",mode=%03o", sbinfo->mode);
	if (sbinfo->uid != 0)
		seq_printf(seq, ",uid=%u", sbinfo->uid);
	if (sbinfo->gid != 0)
		seq_printf(seq, ",gid=%u", sbinfo->gid);
2306
	shmem_show_mpol(seq, sbinfo->mpol);
2307 2308 2309
	return 0;
}
#endif /* CONFIG_TMPFS */
L
Linus Torvalds 已提交
2310 2311 2312 2313 2314 2315 2316

static void shmem_put_super(struct super_block *sb)
{
	kfree(sb->s_fs_info);
	sb->s_fs_info = NULL;
}

2317
int shmem_fill_super(struct super_block *sb, void *data, int silent)
L
Linus Torvalds 已提交
2318 2319 2320
{
	struct inode *inode;
	struct dentry *root;
2321
	struct shmem_sb_info *sbinfo;
2322 2323 2324
	int err = -ENOMEM;

	/* Round up to L1_CACHE_BYTES to resist false sharing */
2325
	sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
2326 2327 2328 2329 2330
				L1_CACHE_BYTES), GFP_KERNEL);
	if (!sbinfo)
		return -ENOMEM;

	sbinfo->mode = S_IRWXUGO | S_ISVTX;
2331 2332
	sbinfo->uid = current_fsuid();
	sbinfo->gid = current_fsgid();
2333
	sb->s_fs_info = sbinfo;
L
Linus Torvalds 已提交
2334

2335
#ifdef CONFIG_TMPFS
L
Linus Torvalds 已提交
2336 2337 2338 2339 2340 2341
	/*
	 * Per default we only allow half of the physical ram per
	 * tmpfs instance, limiting inodes to one per page of lowmem;
	 * but the internal instance is left unlimited.
	 */
	if (!(sb->s_flags & MS_NOUSER)) {
2342 2343 2344 2345 2346 2347
		sbinfo->max_blocks = shmem_default_max_blocks();
		sbinfo->max_inodes = shmem_default_max_inodes();
		if (shmem_parse_options(data, sbinfo, false)) {
			err = -EINVAL;
			goto failed;
		}
L
Linus Torvalds 已提交
2348
	}
2349
	sb->s_export_op = &shmem_export_ops;
L
Linus Torvalds 已提交
2350 2351 2352 2353
#else
	sb->s_flags |= MS_NOUSER;
#endif

2354
	spin_lock_init(&sbinfo->stat_lock);
2355 2356
	sbinfo->free_blocks = sbinfo->max_blocks;
	sbinfo->free_inodes = sbinfo->max_inodes;
2357

L
Linus Torvalds 已提交
2358 2359 2360 2361 2362
	sb->s_maxbytes = SHMEM_MAX_BYTES;
	sb->s_blocksize = PAGE_CACHE_SIZE;
	sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
	sb->s_magic = TMPFS_MAGIC;
	sb->s_op = &shmem_ops;
2363
	sb->s_time_gran = 1;
2364 2365 2366 2367
#ifdef CONFIG_TMPFS_POSIX_ACL
	sb->s_xattr = shmem_xattr_handlers;
	sb->s_flags |= MS_POSIXACL;
#endif
2368

2369
	inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
L
Linus Torvalds 已提交
2370 2371
	if (!inode)
		goto failed;
2372 2373
	inode->i_uid = sbinfo->uid;
	inode->i_gid = sbinfo->gid;
L
Linus Torvalds 已提交
2374 2375 2376 2377 2378 2379 2380 2381 2382 2383 2384 2385 2386
	root = d_alloc_root(inode);
	if (!root)
		goto failed_iput;
	sb->s_root = root;
	return 0;

failed_iput:
	iput(inode);
failed:
	shmem_put_super(sb);
	return err;
}

2387
static struct kmem_cache *shmem_inode_cachep;
L
Linus Torvalds 已提交
2388 2389 2390 2391

static struct inode *shmem_alloc_inode(struct super_block *sb)
{
	struct shmem_inode_info *p;
2392
	p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
L
Linus Torvalds 已提交
2393 2394 2395 2396 2397 2398 2399 2400 2401 2402 2403 2404 2405 2406
	if (!p)
		return NULL;
	return &p->vfs_inode;
}

static void shmem_destroy_inode(struct inode *inode)
{
	if ((inode->i_mode & S_IFMT) == S_IFREG) {
		/* only struct inode is valid if it's an inline symlink */
		mpol_free_shared_policy(&SHMEM_I(inode)->policy);
	}
	kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
}

2407
static void init_once(void *foo)
L
Linus Torvalds 已提交
2408 2409 2410
{
	struct shmem_inode_info *p = (struct shmem_inode_info *) foo;

C
Christoph Lameter 已提交
2411
	inode_init_once(&p->vfs_inode);
L
Linus Torvalds 已提交
2412 2413 2414 2415 2416 2417
}

static int init_inodecache(void)
{
	shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
				sizeof(struct shmem_inode_info),
2418
				0, SLAB_PANIC, init_once);
L
Linus Torvalds 已提交
2419 2420 2421 2422 2423
	return 0;
}

static void destroy_inodecache(void)
{
2424
	kmem_cache_destroy(shmem_inode_cachep);
L
Linus Torvalds 已提交
2425 2426
}

2427
static const struct address_space_operations shmem_aops = {
L
Linus Torvalds 已提交
2428
	.writepage	= shmem_writepage,
2429
	.set_page_dirty	= __set_page_dirty_no_writeback,
L
Linus Torvalds 已提交
2430
#ifdef CONFIG_TMPFS
2431
	.readpage	= shmem_readpage,
N
Nick Piggin 已提交
2432 2433
	.write_begin	= shmem_write_begin,
	.write_end	= shmem_write_end,
L
Linus Torvalds 已提交
2434
#endif
2435
	.migratepage	= migrate_page,
2436
	.error_remove_page = generic_error_remove_page,
L
Linus Torvalds 已提交
2437 2438
};

2439
static const struct file_operations shmem_file_operations = {
L
Linus Torvalds 已提交
2440 2441 2442
	.mmap		= shmem_mmap,
#ifdef CONFIG_TMPFS
	.llseek		= generic_file_llseek,
H
Hugh Dickins 已提交
2443
	.read		= do_sync_read,
H
Hugh Dickins 已提交
2444
	.write		= do_sync_write,
H
Hugh Dickins 已提交
2445
	.aio_read	= shmem_file_aio_read,
H
Hugh Dickins 已提交
2446
	.aio_write	= generic_file_aio_write,
L
Linus Torvalds 已提交
2447
	.fsync		= simple_sync_file,
2448 2449
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
L
Linus Torvalds 已提交
2450 2451 2452
#endif
};

2453
static const struct inode_operations shmem_inode_operations = {
L
Linus Torvalds 已提交
2454 2455
	.truncate	= shmem_truncate,
	.setattr	= shmem_notify_change,
2456
	.truncate_range	= shmem_truncate_range,
2457 2458 2459 2460 2461
#ifdef CONFIG_TMPFS_POSIX_ACL
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= generic_listxattr,
	.removexattr	= generic_removexattr,
2462
	.check_acl	= generic_check_acl,
2463 2464
#endif

L
Linus Torvalds 已提交
2465 2466
};

2467
static const struct inode_operations shmem_dir_inode_operations = {
L
Linus Torvalds 已提交
2468 2469 2470 2471 2472 2473 2474 2475 2476 2477 2478
#ifdef CONFIG_TMPFS
	.create		= shmem_create,
	.lookup		= simple_lookup,
	.link		= shmem_link,
	.unlink		= shmem_unlink,
	.symlink	= shmem_symlink,
	.mkdir		= shmem_mkdir,
	.rmdir		= shmem_rmdir,
	.mknod		= shmem_mknod,
	.rename		= shmem_rename,
#endif
2479 2480 2481 2482 2483 2484
#ifdef CONFIG_TMPFS_POSIX_ACL
	.setattr	= shmem_notify_change,
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= generic_listxattr,
	.removexattr	= generic_removexattr,
2485
	.check_acl	= generic_check_acl,
2486 2487 2488
#endif
};

2489
static const struct inode_operations shmem_special_inode_operations = {
2490 2491 2492 2493 2494 2495
#ifdef CONFIG_TMPFS_POSIX_ACL
	.setattr	= shmem_notify_change,
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= generic_listxattr,
	.removexattr	= generic_removexattr,
2496
	.check_acl	= generic_check_acl,
2497
#endif
L
Linus Torvalds 已提交
2498 2499
};

2500
static const struct super_operations shmem_ops = {
L
Linus Torvalds 已提交
2501 2502 2503 2504 2505
	.alloc_inode	= shmem_alloc_inode,
	.destroy_inode	= shmem_destroy_inode,
#ifdef CONFIG_TMPFS
	.statfs		= shmem_statfs,
	.remount_fs	= shmem_remount_fs,
2506
	.show_options	= shmem_show_options,
L
Linus Torvalds 已提交
2507 2508 2509 2510 2511 2512
#endif
	.delete_inode	= shmem_delete_inode,
	.drop_inode	= generic_delete_inode,
	.put_super	= shmem_put_super,
};

2513
static const struct vm_operations_struct shmem_vm_ops = {
2514
	.fault		= shmem_fault,
L
Linus Torvalds 已提交
2515 2516 2517 2518 2519 2520 2521
#ifdef CONFIG_NUMA
	.set_policy     = shmem_set_policy,
	.get_policy     = shmem_get_policy,
#endif
};


2522 2523
static int shmem_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *data, struct vfsmount *mnt)
L
Linus Torvalds 已提交
2524
{
2525
	return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
L
Linus Torvalds 已提交
2526 2527 2528 2529 2530 2531 2532 2533 2534
}

static struct file_system_type tmpfs_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "tmpfs",
	.get_sb		= shmem_get_sb,
	.kill_sb	= kill_litter_super,
};

2535
int __init init_tmpfs(void)
L
Linus Torvalds 已提交
2536 2537 2538
{
	int error;

P
Peter Zijlstra 已提交
2539 2540 2541 2542
	error = bdi_init(&shmem_backing_dev_info);
	if (error)
		goto out4;

L
Linus Torvalds 已提交
2543 2544 2545 2546 2547 2548 2549 2550 2551
	error = init_inodecache();
	if (error)
		goto out3;

	error = register_filesystem(&tmpfs_fs_type);
	if (error) {
		printk(KERN_ERR "Could not register tmpfs\n");
		goto out2;
	}
2552

2553
	shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
L
Linus Torvalds 已提交
2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566
				tmpfs_fs_type.name, NULL);
	if (IS_ERR(shm_mnt)) {
		error = PTR_ERR(shm_mnt);
		printk(KERN_ERR "Could not kern_mount tmpfs\n");
		goto out1;
	}
	return 0;

out1:
	unregister_filesystem(&tmpfs_fs_type);
out2:
	destroy_inodecache();
out3:
P
Peter Zijlstra 已提交
2567 2568
	bdi_destroy(&shmem_backing_dev_info);
out4:
L
Linus Torvalds 已提交
2569 2570 2571
	shm_mnt = ERR_PTR(error);
	return error;
}
2572 2573 2574 2575 2576 2577 2578 2579 2580 2581 2582 2583 2584 2585 2586 2587 2588 2589 2590 2591

#else /* !CONFIG_SHMEM */

/*
 * tiny-shmem: simple shmemfs and tmpfs using ramfs code
 *
 * This is intended for small system where the benefits of the full
 * shmem code (swap-backed and resource-limited) are outweighed by
 * their complexity. On systems without swap this code should be
 * effectively equivalent, but much lighter weight.
 */

#include <linux/ramfs.h>

static struct file_system_type tmpfs_fs_type = {
	.name		= "tmpfs",
	.get_sb		= ramfs_get_sb,
	.kill_sb	= kill_litter_super,
};

2592
int __init init_tmpfs(void)
2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606
{
	BUG_ON(register_filesystem(&tmpfs_fs_type) != 0);

	shm_mnt = kern_mount(&tmpfs_fs_type);
	BUG_ON(IS_ERR(shm_mnt));

	return 0;
}

int shmem_unuse(swp_entry_t entry, struct page *page)
{
	return 0;
}

H
Hugh Dickins 已提交
2607 2608 2609 2610 2611
int shmem_lock(struct file *file, int lock, struct user_struct *user)
{
	return 0;
}

2612 2613 2614 2615 2616
#define shmem_vm_ops				generic_file_vm_ops
#define shmem_file_operations			ramfs_file_operations
#define shmem_get_inode(sb, mode, dev, flags)	ramfs_get_inode(sb, mode, dev)
#define shmem_acct_size(flags, size)		0
#define shmem_unacct_size(flags, size)		do {} while (0)
H
Hugh Dickins 已提交
2617
#define SHMEM_MAX_BYTES				MAX_LFS_FILESIZE
2618 2619 2620 2621

#endif /* CONFIG_SHMEM */

/* common code */
L
Linus Torvalds 已提交
2622

2623
/**
L
Linus Torvalds 已提交
2624 2625 2626
 * shmem_file_setup - get an unlinked file living in tmpfs
 * @name: name for dentry (to be seen in /proc/<pid>/maps
 * @size: size to be set for the file
2627
 * @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
L
Linus Torvalds 已提交
2628
 */
2629
struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
L
Linus Torvalds 已提交
2630 2631 2632 2633
{
	int error;
	struct file *file;
	struct inode *inode;
2634 2635
	struct path path;
	struct dentry *root;
L
Linus Torvalds 已提交
2636 2637 2638 2639 2640 2641 2642 2643 2644 2645 2646 2647 2648 2649 2650 2651
	struct qstr this;

	if (IS_ERR(shm_mnt))
		return (void *)shm_mnt;

	if (size < 0 || size > SHMEM_MAX_BYTES)
		return ERR_PTR(-EINVAL);

	if (shmem_acct_size(flags, size))
		return ERR_PTR(-ENOMEM);

	error = -ENOMEM;
	this.name = name;
	this.len = strlen(name);
	this.hash = 0; /* will go */
	root = shm_mnt->mnt_root;
2652 2653
	path.dentry = d_alloc(root, &this);
	if (!path.dentry)
L
Linus Torvalds 已提交
2654
		goto put_memory;
2655
	path.mnt = mntget(shm_mnt);
L
Linus Torvalds 已提交
2656 2657

	error = -ENOSPC;
2658
	inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0, flags);
L
Linus Torvalds 已提交
2659
	if (!inode)
2660
		goto put_dentry;
L
Linus Torvalds 已提交
2661

2662
	d_instantiate(path.dentry, inode);
L
Linus Torvalds 已提交
2663 2664
	inode->i_size = size;
	inode->i_nlink = 0;	/* It is unlinked */
2665 2666 2667
#ifndef CONFIG_MMU
	error = ramfs_nommu_expand_for_mapping(inode, size);
	if (error)
2668
		goto put_dentry;
2669
#endif
2670 2671

	error = -ENFILE;
2672
	file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
2673 2674 2675 2676
		  &shmem_file_operations);
	if (!file)
		goto put_dentry;

L
Linus Torvalds 已提交
2677 2678 2679
	return file;

put_dentry:
2680
	path_put(&path);
L
Linus Torvalds 已提交
2681 2682 2683 2684
put_memory:
	shmem_unacct_size(flags, size);
	return ERR_PTR(error);
}
2685
EXPORT_SYMBOL_GPL(shmem_file_setup);
L
Linus Torvalds 已提交
2686

2687
/**
L
Linus Torvalds 已提交
2688 2689 2690 2691 2692 2693 2694 2695 2696 2697 2698 2699 2700 2701 2702 2703 2704 2705
 * shmem_zero_setup - setup a shared anonymous mapping
 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff
 */
int shmem_zero_setup(struct vm_area_struct *vma)
{
	struct file *file;
	loff_t size = vma->vm_end - vma->vm_start;

	file = shmem_file_setup("dev/zero", size, vma->vm_flags);
	if (IS_ERR(file))
		return PTR_ERR(file);

	if (vma->vm_file)
		fput(vma->vm_file);
	vma->vm_file = file;
	vma->vm_ops = &shmem_vm_ops;
	return 0;
}