shmem.c 67.7 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>
#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/generic_acl.h>
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#include <linux/mman.h>
#include <linux/pagemap.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/vfs.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>

#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long))
#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE)
#define BLOCKS_PER_PAGE  (PAGE_CACHE_SIZE/512)

#define SHMEM_MAX_INDEX  (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1))
#define SHMEM_MAX_BYTES  ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT)

#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_ACCOUNT) ?
		security_vm_enough_memory_kern(VM_ACCT(size)) : 0;
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}

static inline void shmem_unacct_size(unsigned long flags, loff_t size)
{
	if (flags & VM_ACCOUNT)
		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_ACCOUNT) ?
		0 : security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE));
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}

static inline void shmem_unacct_blocks(unsigned long flags, long pages)
{
	if (!(flags & VM_ACCOUNT))
		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 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;
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		punch_hole = 1;
	}

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	topdir = info->i_indirect;
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	if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) {
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		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;
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		nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size, needs_lock);
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	}
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	/*
	 * If there are no indirect blocks or we are punching a hole
	 * below indirect blocks, nothing to be done.
	 */
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	if (!topdir || limit <= SHMEM_NR_DIRECT)
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		goto done2;

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	/*
	 * 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.
	 */

608
	upper_limit -= SHMEM_NR_DIRECT;
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	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;
628
			if (!diroff && !offset && upper_limit >= stage) {
629 630 631 632 633 634 635
				if (needs_lock) {
					spin_lock(needs_lock);
					*dir = NULL;
					spin_unlock(needs_lock);
					needs_lock = NULL;
				} else
					*dir = NULL;
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				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;
661 662
			if (punch_hole)
				needs_lock = &info->lock;
663
			if (upper_limit >= stage) {
664 665 666 667 668 669 670
				if (needs_lock) {
					spin_lock(needs_lock);
					*dir = NULL;
					spin_unlock(needs_lock);
					needs_lock = NULL;
				} else
					*dir = NULL;
671 672 673
				nr_pages_to_free++;
				list_add(&middir->lru, &pages_to_free);
			}
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			shmem_dir_unmap(dir);
			cond_resched();
			dir = shmem_dir_map(middir);
			diroff = 0;
		}
679
		punch_lock = needs_lock;
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		subdir = dir[diroff];
681 682 683 684 685 686 687 688 689 690 691 692
		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,
697
					offset, size, &dir, punch_lock);
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			if (!dir)
				dir = shmem_dir_map(middir);
			nr_swaps_freed += freed;
701
			if (offset || punch_lock) {
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				spin_lock(&info->lock);
703 704
				set_page_private(subdir,
					page_private(subdir) - freed);
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705
				spin_unlock(&info->lock);
706 707
			} else
				BUG_ON(page_private(subdir) != freed);
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708
		}
709
		offset = 0;
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	}
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.
721 722 723 724 725
		 *
		 * 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.
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726
		 */
727
		truncate_inode_pages_range(inode->i_mapping, start, end);
728 729 730
		if (punch_hole)
			unmap_mapping_range(inode->i_mapping, start,
							end - start, 1);
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	}

	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);
	}
}

750 751 752 753 754
static void shmem_truncate(struct inode *inode)
{
	shmem_truncate_range(inode, inode->i_size, (loff_t)-1);
}

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static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
{
	struct inode *inode = dentry->d_inode;
	struct page *page = NULL;
	int error;

761
	if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
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		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);
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				if (page)
					unlock_page(page);
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			}
			/*
			 * 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);
796 797 798 799
#ifdef CONFIG_TMPFS_POSIX_ACL
	if (!error && (attr->ia_valid & ATTR_MODE))
		error = generic_acl_chmod(inode, &shmem_acl_ops);
#endif
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	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) {
810
		truncate_inode_pages(inode->i_mapping, 0);
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		shmem_unacct_size(info->flags, inode->i_size);
		inode->i_size = 0;
		shmem_truncate(inode);
		if (!list_empty(&info->swaplist)) {
815
			mutex_lock(&shmem_swaplist_mutex);
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816
			list_del_init(&info->swaplist);
817
			mutex_unlock(&shmem_swaplist_mutex);
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		}
	}
820
	BUG_ON(inode->i_blocks);
821
	shmem_free_inode(inode->i_sb);
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	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;
847
	int error;
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	idx = 0;
	ptr = info->i_direct;
	spin_lock(&info->lock);
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	if (!info->swapped) {
		list_del_init(&info->swaplist);
		goto lost2;
	}
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	limit = info->next_index;
	size = limit;
	if (size > SHMEM_NR_DIRECT)
		size = SHMEM_NR_DIRECT;
	offset = shmem_find_swp(entry, ptr, ptr+size);
861
	if (offset >= 0)
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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);
872 873 874 875 876 877 878 879
			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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			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;
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		if (subdir && page_private(subdir)) {
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			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);
900
			shmem_swp_unmap(ptr);
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			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;
914 915 916
	inode = igrab(&info->vfs_inode);
	spin_unlock(&info->lock);

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	/*
	 * 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);
926 927 928 929 930
	mutex_unlock(&shmem_swaplist_mutex);

	error = 1;
	if (!inode)
		goto out;
931
	/* Precharge page using GFP_KERNEL while we can wait */
932
	error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
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	if (error)
		goto out;
935
	error = radix_tree_preload(GFP_KERNEL);
936 937 938 939
	if (error) {
		mem_cgroup_uncharge_cache_page(page);
		goto out;
	}
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	error = 1;
941 942 943

	spin_lock(&info->lock);
	ptr = shmem_swp_entry(info, idx, NULL);
944
	if (ptr && ptr->val == entry.val) {
N
Nick Piggin 已提交
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		error = add_to_page_cache_locked(page, inode->i_mapping,
H
Hugh Dickins 已提交
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						idx, GFP_NOWAIT);
947 948 949 950
		/* does mem_cgroup_uncharge_cache_page on error */
	} else	/* we must compensate for our precharge above */
		mem_cgroup_uncharge_cache_page(page);

951 952
	if (error == -EEXIST) {
		struct page *filepage = find_get_page(inode->i_mapping, idx);
953
		error = 1;
954 955 956 957 958 959 960 961 962 963 964
		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) {
965 966
		delete_from_swap_cache(page);
		set_page_dirty(page);
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		info->flags |= SHMEM_PAGEIN;
968 969 970
		shmem_swp_set(info, ptr, 0);
		swap_free(entry);
		error = 1;	/* not an error, but entry was found */
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	}
972 973
	if (ptr)
		shmem_swp_unmap(ptr);
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	spin_unlock(&info->lock);
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	radix_tree_preload_end();
976 977 978 979 980
out:
	unlock_page(page);
	page_cache_release(page);
	iput(inode);		/* allows for NULL */
	return error;
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}

/*
 * 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;

992
	mutex_lock(&shmem_swaplist_mutex);
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	list_for_each_safe(p, next, &shmem_swaplist) {
		info = list_entry(p, struct shmem_inode_info, swaplist);
H
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995
		found = shmem_unuse_inode(info, entry, page);
996
		cond_resched();
997 998
		if (found)
			goto out;
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	}
1000
	mutex_unlock(&shmem_swaplist_mutex);
1001
out:	return found;	/* 0 or 1 or -ENOMEM */
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}

/*
 * 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;
1022
	if (!total_swap_pages)
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		goto redirty;

1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037
	/*
	 * 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,
	 * and not for pdflush or sync.  However, in those cases, we do still
	 * want to check if there's a redundant swappage to be discarded.
	 */
	if (wbc->for_reclaim)
		swap = get_swap_page();
	else
		swap.val = 0;

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	spin_lock(&info->lock);
	if (index >= info->next_index) {
		BUG_ON(!(info->flags & SHMEM_TRUNCATE));
		goto unlock;
	}
	entry = shmem_swp_entry(info, index, NULL);
1044 1045 1046 1047 1048 1049 1050 1051 1052
	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);
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1054
	if (swap.val && add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
1055
		remove_from_page_cache(page);
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		shmem_swp_set(info, entry, swap.val);
		shmem_swp_unmap(entry);
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1058 1059 1060 1061
		if (list_empty(&info->swaplist))
			inode = igrab(inode);
		else
			inode = NULL;
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1062
		spin_unlock(&info->lock);
1063
		swap_duplicate(swap);
1064
		BUG_ON(page_mapped(page));
1065 1066
		page_cache_release(page);	/* pagecache ref */
		set_page_dirty(page);
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		unlock_page(page);
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		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);
		}
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		return 0;
	}

	shmem_swp_unmap(entry);
unlock:
	spin_unlock(&info->lock);
	swap_free(swap);
redirty:
	set_page_dirty(page);
1084 1085 1086 1087
	if (wbc->for_reclaim)
		return AOP_WRITEPAGE_ACTIVATE;	/* Return with page locked */
	unlock_page(page);
	return 0;
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}

#ifdef CONFIG_NUMA
1091
#ifdef CONFIG_TMPFS
1092
static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
1093
{
1094
	char buffer[64];
1095

1096
	if (!mpol || mpol->mode == MPOL_DEFAULT)
1097
		return;		/* show nothing */
1098

1099
	mpol_to_str(buffer, sizeof(buffer), mpol, 1);
1100 1101

	seq_printf(seq, ",mpol=%s", buffer);
1102
}
1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114

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;
}
1115 1116
#endif /* CONFIG_TMPFS */

1117 1118
static struct page *shmem_swapin(swp_entry_t entry, gfp_t gfp,
			struct shmem_inode_info *info, unsigned long idx)
L
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{
1120
	struct mempolicy mpol, *spol;
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1121
	struct vm_area_struct pvma;
1122
	struct page *page;
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1124 1125 1126
	spol = mpol_cond_copy(&mpol,
				mpol_shared_policy_lookup(&info->policy, idx));

L
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	/* Create a pseudo vma that just contains the policy */
1128
	pvma.vm_start = 0;
L
Linus Torvalds 已提交
1129
	pvma.vm_pgoff = idx;
1130
	pvma.vm_ops = NULL;
1131
	pvma.vm_policy = spol;
1132
	page = swapin_readahead(entry, gfp, &pvma, 0);
L
Linus Torvalds 已提交
1133 1134 1135
	return page;
}

1136 1137
static struct page *shmem_alloc_page(gfp_t gfp,
			struct shmem_inode_info *info, unsigned long idx)
L
Linus Torvalds 已提交
1138 1139 1140
{
	struct vm_area_struct pvma;

1141 1142
	/* Create a pseudo vma that just contains the policy */
	pvma.vm_start = 0;
L
Linus Torvalds 已提交
1143
	pvma.vm_pgoff = idx;
1144 1145
	pvma.vm_ops = NULL;
	pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
1146 1147 1148 1149 1150

	/*
	 * alloc_page_vma() will drop the shared policy reference
	 */
	return alloc_page_vma(gfp, &pvma, 0);
L
Linus Torvalds 已提交
1151
}
1152 1153
#else /* !CONFIG_NUMA */
#ifdef CONFIG_TMPFS
1154
static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *p)
1155 1156 1157 1158
{
}
#endif /* CONFIG_TMPFS */

1159 1160
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
1161
{
1162
	return swapin_readahead(entry, gfp, NULL, 0);
L
Linus Torvalds 已提交
1163 1164
}

1165 1166
static inline struct page *shmem_alloc_page(gfp_t gfp,
			struct shmem_inode_info *info, unsigned long idx)
L
Linus Torvalds 已提交
1167
{
1168
	return alloc_page(gfp);
L
Linus Torvalds 已提交
1169
}
1170
#endif /* CONFIG_NUMA */
L
Linus Torvalds 已提交
1171

1172 1173 1174 1175 1176 1177 1178
#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
1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195
/*
 * 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;
1196
	gfp_t gfp;
L
Linus Torvalds 已提交
1197 1198 1199 1200
	int error;

	if (idx >= SHMEM_MAX_INDEX)
		return -EFBIG;
1201 1202

	if (type)
N
Nick Piggin 已提交
1203
		*type = 0;
1204

L
Linus Torvalds 已提交
1205 1206 1207 1208
	/*
	 * 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
1209
	 * But shmem_readpage (required for splice) passes in a locked
1210 1211
	 * 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
1212 1213 1214 1215 1216 1217 1218
	 */
repeat:
	if (!filepage)
		filepage = find_lock_page(mapping, idx);
	if (filepage && PageUptodate(filepage))
		goto done;
	error = 0;
1219
	gfp = mapping_gfp_mask(mapping);
H
Hugh Dickins 已提交
1220 1221 1222 1223 1224 1225 1226 1227 1228 1229
	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
1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246

	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
1247
			if (type && !(*type & VM_FAULT_MAJOR)) {
1248
				__count_vm_event(PGMAJFAULT);
N
Nick Piggin 已提交
1249
				*type |= VM_FAULT_MAJOR;
L
Linus Torvalds 已提交
1250
			}
1251
			spin_unlock(&info->lock);
1252
			swappage = shmem_swapin(swap, gfp, info, idx);
L
Linus Torvalds 已提交
1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273
			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
1274
		if (!trylock_page(swappage)) {
L
Linus Torvalds 已提交
1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309
			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
1310 1311
		} else if (!(error = add_to_page_cache_locked(swappage, mapping,
					idx, GFP_NOWAIT))) {
L
Linus Torvalds 已提交
1312 1313 1314
			info->flags |= SHMEM_PAGEIN;
			shmem_swp_set(info, entry, 0);
			shmem_swp_unmap(entry);
1315
			delete_from_swap_cache(swappage);
L
Linus Torvalds 已提交
1316 1317
			spin_unlock(&info->lock);
			filepage = swappage;
1318
			set_page_dirty(filepage);
L
Linus Torvalds 已提交
1319 1320 1321 1322 1323
			swap_free(swap);
		} else {
			shmem_swp_unmap(entry);
			spin_unlock(&info->lock);
			unlock_page(swappage);
1324
			page_cache_release(swappage);
1325 1326
			if (error == -ENOMEM) {
				/* allow reclaim from this memory cgroup */
1327 1328 1329
				error = mem_cgroup_shrink_usage(current->mm,
								gfp);
				if (error)
1330 1331
					goto failed;
			}
L
Linus Torvalds 已提交
1332 1333 1334 1335 1336 1337
			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
1338
		    (!PageUptodate(filepage) || !trylock_page(filepage))) {
L
Linus Torvalds 已提交
1339 1340 1341 1342 1343 1344 1345 1346 1347 1348
			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);
1349
		if (sbinfo->max_blocks) {
L
Linus Torvalds 已提交
1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367
			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) {
1368 1369
			int ret;

L
Linus Torvalds 已提交
1370
			spin_unlock(&info->lock);
1371
			filepage = shmem_alloc_page(gfp, info, idx);
L
Linus Torvalds 已提交
1372 1373 1374 1375 1376 1377
			if (!filepage) {
				shmem_unacct_blocks(info->flags, 1);
				shmem_free_blocks(inode, 1);
				error = -ENOMEM;
				goto failed;
			}
R
Rik van Riel 已提交
1378
			SetPageSwapBacked(filepage);
L
Linus Torvalds 已提交
1379

1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390
			/* Precharge page while we can wait, compensate after */
			error = mem_cgroup_cache_charge(filepage, current->mm,
							gfp & ~__GFP_HIGHMEM);
			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
1391 1392 1393 1394 1395 1396 1397 1398
			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);
			}
1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409
			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
1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423
				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);
1424
		clear_highpage(filepage);
L
Linus Torvalds 已提交
1425 1426
		flush_dcache_page(filepage);
		SetPageUptodate(filepage);
1427 1428
		if (sgp == SGP_DIRTY)
			set_page_dirty(filepage);
L
Linus Torvalds 已提交
1429 1430
	}
done:
H
Hugh Dickins 已提交
1431
	*pagep = filepage;
L
Linus Torvalds 已提交
1432 1433 1434 1435 1436 1437 1438 1439 1440 1441
	return 0;

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

N
Nick Piggin 已提交
1442
static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
L
Linus Torvalds 已提交
1443
{
1444
	struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1445
	int error;
N
Nick Piggin 已提交
1446
	int ret;
L
Linus Torvalds 已提交
1447

N
Nick Piggin 已提交
1448 1449
	if (((loff_t)vmf->pgoff << PAGE_CACHE_SHIFT) >= i_size_read(inode))
		return VM_FAULT_SIGBUS;
1450

1451
	error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
N
Nick Piggin 已提交
1452 1453
	if (error)
		return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
L
Linus Torvalds 已提交
1454

N
Nick Piggin 已提交
1455
	return ret | VM_FAULT_LOCKED;
L
Linus Torvalds 已提交
1456 1457 1458
}

#ifdef CONFIG_NUMA
A
Adrian Bunk 已提交
1459
static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
L
Linus Torvalds 已提交
1460
{
1461
	struct inode *i = vma->vm_file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1462 1463 1464
	return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
}

A
Adrian Bunk 已提交
1465 1466
static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
					  unsigned long addr)
L
Linus Torvalds 已提交
1467
{
1468
	struct inode *i = vma->vm_file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1469 1470 1471 1472 1473 1474 1475 1476 1477
	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)
{
1478
	struct inode *inode = file->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1479 1480 1481 1482 1483 1484 1485 1486
	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;
1487
		mapping_set_unevictable(file->f_mapping);
L
Linus Torvalds 已提交
1488 1489 1490 1491
	}
	if (!lock && (info->flags & VM_LOCKED) && user) {
		user_shm_unlock(inode->i_size, user);
		info->flags &= ~VM_LOCKED;
1492 1493
		mapping_clear_unevictable(file->f_mapping);
		scan_mapping_unevictable_pages(file->f_mapping);
L
Linus Torvalds 已提交
1494 1495
	}
	retval = 0;
1496

L
Linus Torvalds 已提交
1497 1498 1499 1500 1501
out_nomem:
	spin_unlock(&info->lock);
	return retval;
}

1502
static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
L
Linus Torvalds 已提交
1503 1504 1505
{
	file_accessed(file);
	vma->vm_ops = &shmem_vm_ops;
N
Nick Piggin 已提交
1506
	vma->vm_flags |= VM_CAN_NONLINEAR;
L
Linus Torvalds 已提交
1507 1508 1509 1510 1511 1512 1513 1514 1515 1516
	return 0;
}

static struct inode *
shmem_get_inode(struct super_block *sb, int mode, dev_t dev)
{
	struct inode *inode;
	struct shmem_inode_info *info;
	struct shmem_sb_info *sbinfo = SHMEM_SB(sb);

1517 1518
	if (shmem_reserve_inode(sb))
		return NULL;
L
Linus Torvalds 已提交
1519 1520 1521 1522

	inode = new_inode(sb);
	if (inode) {
		inode->i_mode = mode;
1523 1524
		inode->i_uid = current_fsuid();
		inode->i_gid = current_fsgid();
L
Linus Torvalds 已提交
1525 1526 1527
		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;
1528
		inode->i_generation = get_seconds();
L
Linus Torvalds 已提交
1529 1530 1531 1532 1533 1534 1535
		info = SHMEM_I(inode);
		memset(info, 0, (char *)inode - (char *)info);
		spin_lock_init(&info->lock);
		INIT_LIST_HEAD(&info->swaplist);

		switch (mode & S_IFMT) {
		default:
1536
			inode->i_op = &shmem_special_inode_operations;
L
Linus Torvalds 已提交
1537 1538 1539
			init_special_inode(inode, mode, dev);
			break;
		case S_IFREG:
1540
			inode->i_mapping->a_ops = &shmem_aops;
L
Linus Torvalds 已提交
1541 1542
			inode->i_op = &shmem_inode_operations;
			inode->i_fop = &shmem_file_operations;
1543 1544
			mpol_shared_policy_init(&info->policy,
						 shmem_get_sbmpol(sbinfo));
L
Linus Torvalds 已提交
1545 1546
			break;
		case S_IFDIR:
1547
			inc_nlink(inode);
L
Linus Torvalds 已提交
1548 1549 1550 1551 1552 1553 1554 1555 1556 1557
			/* 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.
			 */
1558
			mpol_shared_policy_init(&info->policy, NULL);
L
Linus Torvalds 已提交
1559 1560
			break;
		}
1561 1562
	} else
		shmem_free_inode(sb);
L
Linus Torvalds 已提交
1563 1564 1565 1566
	return inode;
}

#ifdef CONFIG_TMPFS
1567 1568
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_symlink_inline_operations;
L
Linus Torvalds 已提交
1569 1570

/*
N
Nick Piggin 已提交
1571
 * Normally tmpfs avoids the use of shmem_readpage and shmem_write_begin;
1572 1573
 * 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.
L
Linus Torvalds 已提交
1574
 */
1575 1576 1577 1578 1579 1580 1581 1582
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;
}

L
Linus Torvalds 已提交
1583
static int
N
Nick Piggin 已提交
1584 1585 1586
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
1587
{
N
Nick Piggin 已提交
1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600
	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
Hugh Dickins 已提交
1601 1602 1603 1604
	if (pos + copied > inode->i_size)
		i_size_write(inode, pos + copied);

	unlock_page(page);
N
Nick Piggin 已提交
1605 1606 1607 1608
	set_page_dirty(page);
	page_cache_release(page);

	return copied;
L
Linus Torvalds 已提交
1609 1610 1611 1612
}

static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
{
1613
	struct inode *inode = filp->f_path.dentry->d_inode;
L
Linus Torvalds 已提交
1614 1615
	struct address_space *mapping = inode->i_mapping;
	unsigned long index, offset;
1616 1617 1618 1619 1620 1621 1622 1623 1624
	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;
L
Linus Torvalds 已提交
1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642

	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;
		}

1643
		desc->error = shmem_getpage(inode, index, &page, sgp, NULL);
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Linus Torvalds 已提交
1644 1645 1646 1647 1648
		if (desc->error) {
			if (desc->error == -EINVAL)
				desc->error = 0;
			break;
		}
H
Hugh Dickins 已提交
1649 1650
		if (page)
			unlock_page(page);
L
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1651 1652 1653

		/*
		 * We must evaluate after, since reads (unlike writes)
1654
		 * are called without i_mutex protection against truncate
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		 */
		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
1682
		} else {
L
Linus Torvalds 已提交
1683
			page = ZERO_PAGE(0);
N
Nick Piggin 已提交
1684 1685
			page_cache_get(page);
		}
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1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712

		/*
		 * 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);
}

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1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744
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
1745 1746
}

1747
static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
L
Linus Torvalds 已提交
1748
{
1749
	struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
L
Linus Torvalds 已提交
1750 1751 1752 1753

	buf->f_type = TMPFS_MAGIC;
	buf->f_bsize = PAGE_CACHE_SIZE;
	buf->f_namelen = NAME_MAX;
1754 1755
	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;
1758 1759
	}
	if (sbinfo->max_inodes) {
L
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		buf->f_files = sbinfo->max_inodes;
		buf->f_ffree = sbinfo->free_inodes;
	}
	/* else leave those fields 0 like simple_statfs */
1764
	spin_unlock(&sbinfo->stat_lock);
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	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)
{
	struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev);
	int error = -ENOSPC;

	if (inode) {
1778 1779 1780 1781 1782 1783 1784
		error = security_inode_init_security(inode, dir, NULL, NULL,
						     NULL);
		if (error) {
			if (error != -EOPNOTSUPP) {
				iput(inode);
				return error;
			}
1785 1786 1787 1788 1789
		}
		error = shmem_acl_init(inode, dir);
		if (error) {
			iput(inode);
			return error;
1790
		}
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		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;
1810
	inc_nlink(dir);
L
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	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;
1826
	int ret;
L
Linus Torvalds 已提交
1827 1828 1829 1830 1831 1832

	/*
	 * 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.
	 */
1833 1834 1835
	ret = shmem_reserve_inode(inode->i_sb);
	if (ret)
		goto out;
L
Linus Torvalds 已提交
1836 1837 1838

	dir->i_size += BOGO_DIRENT_SIZE;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1839
	inc_nlink(inode);
L
Linus Torvalds 已提交
1840 1841 1842
	atomic_inc(&inode->i_count);	/* New dentry reference */
	dget(dentry);		/* Extra pinning count for the created dentry */
	d_instantiate(dentry, inode);
1843 1844
out:
	return ret;
L
Linus Torvalds 已提交
1845 1846 1847 1848 1849 1850
}

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

1851 1852
	if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode))
		shmem_free_inode(inode->i_sb);
L
Linus Torvalds 已提交
1853 1854 1855

	dir->i_size -= BOGO_DIRENT_SIZE;
	inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
1856
	drop_nlink(inode);
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Linus Torvalds 已提交
1857 1858 1859 1860 1861 1862 1863 1864 1865
	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;

1866 1867
	drop_nlink(dentry->d_inode);
	drop_nlink(dir);
L
Linus Torvalds 已提交
1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887
	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)
1888
			drop_nlink(old_dir);
L
Linus Torvalds 已提交
1889
	} else if (they_are_dirs) {
1890
		drop_nlink(old_dir);
1891
		inc_nlink(new_dir);
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Linus Torvalds 已提交
1892 1893 1894 1895 1896 1897 1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915 1916 1917 1918
	}

	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;

	inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
	if (!inode)
		return -ENOSPC;

1919 1920 1921 1922 1923 1924 1925 1926 1927 1928
	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
1929 1930 1931 1932 1933 1934 1935 1936 1937 1938 1939 1940
	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;
		}
H
Hugh Dickins 已提交
1941
		unlock_page(page);
1942
		inode->i_mapping->a_ops = &shmem_aops;
L
Linus Torvalds 已提交
1943 1944 1945 1946 1947 1948 1949 1950 1951 1952 1953 1954 1955 1956 1957 1958
		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);
		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;
}

1959
static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
L
Linus Torvalds 已提交
1960 1961
{
	nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
1962
	return NULL;
L
Linus Torvalds 已提交
1963 1964
}

1965
static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
L
Linus Torvalds 已提交
1966 1967 1968 1969
{
	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
1970 1971
	if (page)
		unlock_page(page);
1972
	return page;
L
Linus Torvalds 已提交
1973 1974
}

1975
static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
L
Linus Torvalds 已提交
1976 1977
{
	if (!IS_ERR(nd_get_link(nd))) {
1978
		struct page *page = cookie;
L
Linus Torvalds 已提交
1979 1980 1981 1982 1983 1984
		kunmap(page);
		mark_page_accessed(page);
		page_cache_release(page);
	}
}

1985
static const struct inode_operations shmem_symlink_inline_operations = {
L
Linus Torvalds 已提交
1986 1987 1988 1989
	.readlink	= generic_readlink,
	.follow_link	= shmem_follow_link_inline,
};

1990
static const struct inode_operations shmem_symlink_inode_operations = {
L
Linus Torvalds 已提交
1991 1992 1993 1994 1995 1996
	.truncate	= shmem_truncate,
	.readlink	= generic_readlink,
	.follow_link	= shmem_follow_link,
	.put_link	= shmem_put_link,
};

1997
#ifdef CONFIG_TMPFS_POSIX_ACL
1998
/*
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016
 * 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.
 */

static size_t shmem_xattr_security_list(struct inode *inode, char *list,
					size_t list_len, const char *name,
					size_t name_len)
{
	return security_inode_listsecurity(inode, list, list_len);
}

static int shmem_xattr_security_get(struct inode *inode, const char *name,
				    void *buffer, size_t size)
{
	if (strcmp(name, "") == 0)
		return -EINVAL;
2017
	return xattr_getsecurity(inode, name, buffer, size);
2018 2019 2020 2021 2022 2023 2024 2025 2026 2027
}

static int shmem_xattr_security_set(struct inode *inode, const char *name,
				    const void *value, size_t size, int flags)
{
	if (strcmp(name, "") == 0)
		return -EINVAL;
	return security_inode_setsecurity(inode, name, value, size, flags);
}

2028
static struct xattr_handler shmem_xattr_security_handler = {
2029 2030 2031 2032 2033 2034 2035 2036 2037 2038 2039 2040 2041 2042
	.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[] = {
	&shmem_xattr_acl_access_handler,
	&shmem_xattr_acl_default_handler,
	&shmem_xattr_security_handler,
	NULL
};
#endif

2043 2044 2045 2046 2047 2048 2049 2050 2051 2052 2053 2054 2055
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
2056 2057
static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
		struct fid *fid, int fh_len, int fh_type)
2058 2059
{
	struct inode *inode;
C
Christoph Hellwig 已提交
2060 2061 2062 2063 2064 2065
	struct dentry *dentry = NULL;
	u64 inum = fid->raw[2];
	inum = (inum << 32) | fid->raw[1];

	if (fh_len < 3)
		return NULL;
2066

C
Christoph Hellwig 已提交
2067 2068
	inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
			shmem_match, fid->raw);
2069
	if (inode) {
C
Christoph Hellwig 已提交
2070
		dentry = d_find_alias(inode);
2071 2072 2073
		iput(inode);
	}

C
Christoph Hellwig 已提交
2074
	return dentry;
2075 2076 2077 2078 2079 2080 2081 2082 2083 2084 2085 2086 2087 2088 2089 2090 2091 2092 2093 2094 2095 2096 2097 2098 2099 2100 2101 2102 2103 2104 2105 2106
}

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;
}

2107
static const struct export_operations shmem_export_ops = {
2108 2109
	.get_parent     = shmem_get_parent,
	.encode_fh      = shmem_encode_fh,
C
Christoph Hellwig 已提交
2110
	.fh_to_dentry	= shmem_fh_to_dentry,
2111 2112
};

2113 2114
static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
			       bool remount)
L
Linus Torvalds 已提交
2115 2116 2117
{
	char *this_char, *value, *rest;

2118 2119 2120 2121 2122 2123 2124 2125 2126 2127 2128 2129 2130 2131 2132 2133 2134
	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
2135 2136 2137 2138 2139 2140 2141 2142 2143 2144 2145 2146 2147 2148 2149 2150 2151 2152 2153 2154 2155 2156
		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;
2157 2158
			sbinfo->max_blocks =
				DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
L
Linus Torvalds 已提交
2159
		} else if (!strcmp(this_char,"nr_blocks")) {
2160
			sbinfo->max_blocks = memparse(value, &rest);
L
Linus Torvalds 已提交
2161 2162 2163
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"nr_inodes")) {
2164
			sbinfo->max_inodes = memparse(value, &rest);
L
Linus Torvalds 已提交
2165 2166 2167
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"mode")) {
2168
			if (remount)
L
Linus Torvalds 已提交
2169
				continue;
2170
			sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
L
Linus Torvalds 已提交
2171 2172 2173
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"uid")) {
2174
			if (remount)
L
Linus Torvalds 已提交
2175
				continue;
2176
			sbinfo->uid = simple_strtoul(value, &rest, 0);
L
Linus Torvalds 已提交
2177 2178 2179
			if (*rest)
				goto bad_val;
		} else if (!strcmp(this_char,"gid")) {
2180
			if (remount)
L
Linus Torvalds 已提交
2181
				continue;
2182
			sbinfo->gid = simple_strtoul(value, &rest, 0);
L
Linus Torvalds 已提交
2183 2184
			if (*rest)
				goto bad_val;
2185
		} else if (!strcmp(this_char,"mpol")) {
2186
			if (mpol_parse_str(value, &sbinfo->mpol, 1))
2187
				goto bad_val;
L
Linus Torvalds 已提交
2188 2189 2190 2191 2192 2193 2194 2195 2196 2197 2198 2199 2200 2201 2202 2203 2204 2205
		} 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);
2206
	struct shmem_sb_info config = *sbinfo;
2207 2208 2209 2210
	unsigned long blocks;
	unsigned long inodes;
	int error = -EINVAL;

2211
	if (shmem_parse_options(data, &config, true))
2212
		return error;
L
Linus Torvalds 已提交
2213

2214 2215 2216
	spin_lock(&sbinfo->stat_lock);
	blocks = sbinfo->max_blocks - sbinfo->free_blocks;
	inodes = sbinfo->max_inodes - sbinfo->free_inodes;
2217
	if (config.max_blocks < blocks)
2218
		goto out;
2219
	if (config.max_inodes < inodes)
2220 2221 2222 2223 2224 2225 2226
		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.
	 */
2227
	if (config.max_blocks && !sbinfo->max_blocks)
2228
		goto out;
2229
	if (config.max_inodes && !sbinfo->max_inodes)
2230 2231 2232
		goto out;

	error = 0;
2233 2234 2235 2236
	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;
2237 2238 2239

	mpol_put(sbinfo->mpol);
	sbinfo->mpol        = config.mpol;	/* transfers initial ref */
2240 2241 2242
out:
	spin_unlock(&sbinfo->stat_lock);
	return error;
L
Linus Torvalds 已提交
2243
}
2244 2245 2246 2247 2248 2249 2250 2251 2252 2253 2254 2255 2256 2257 2258 2259

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);
2260
	shmem_show_mpol(seq, sbinfo->mpol);
2261 2262 2263
	return 0;
}
#endif /* CONFIG_TMPFS */
L
Linus Torvalds 已提交
2264 2265 2266 2267 2268 2269 2270 2271 2272 2273 2274 2275

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

static int shmem_fill_super(struct super_block *sb,
			    void *data, int silent)
{
	struct inode *inode;
	struct dentry *root;
2276
	struct shmem_sb_info *sbinfo;
2277 2278 2279 2280 2281 2282 2283 2284 2285 2286 2287
	int err = -ENOMEM;

	/* Round up to L1_CACHE_BYTES to resist false sharing */
	sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info),
				L1_CACHE_BYTES), GFP_KERNEL);
	if (!sbinfo)
		return -ENOMEM;

	sbinfo->max_blocks = 0;
	sbinfo->max_inodes = 0;
	sbinfo->mode = S_IRWXUGO | S_ISVTX;
2288 2289
	sbinfo->uid = current_fsuid();
	sbinfo->gid = current_fsgid();
2290
	sbinfo->mpol = NULL;
2291
	sb->s_fs_info = sbinfo;
L
Linus Torvalds 已提交
2292

2293
#ifdef CONFIG_TMPFS
L
Linus Torvalds 已提交
2294 2295 2296 2297 2298 2299
	/*
	 * 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)) {
2300 2301 2302 2303 2304 2305
		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
2306
	}
2307
	sb->s_export_op = &shmem_export_ops;
L
Linus Torvalds 已提交
2308 2309 2310 2311
#else
	sb->s_flags |= MS_NOUSER;
#endif

2312
	spin_lock_init(&sbinfo->stat_lock);
2313 2314
	sbinfo->free_blocks = sbinfo->max_blocks;
	sbinfo->free_inodes = sbinfo->max_inodes;
2315

L
Linus Torvalds 已提交
2316 2317 2318 2319 2320
	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;
2321
	sb->s_time_gran = 1;
2322 2323 2324 2325
#ifdef CONFIG_TMPFS_POSIX_ACL
	sb->s_xattr = shmem_xattr_handlers;
	sb->s_flags |= MS_POSIXACL;
#endif
2326

2327
	inode = shmem_get_inode(sb, S_IFDIR | sbinfo->mode, 0);
L
Linus Torvalds 已提交
2328 2329
	if (!inode)
		goto failed;
2330 2331
	inode->i_uid = sbinfo->uid;
	inode->i_gid = sbinfo->gid;
L
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2332 2333 2334 2335 2336 2337 2338 2339 2340 2341 2342 2343 2344
	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;
}

2345
static struct kmem_cache *shmem_inode_cachep;
L
Linus Torvalds 已提交
2346 2347 2348 2349

static struct inode *shmem_alloc_inode(struct super_block *sb)
{
	struct shmem_inode_info *p;
2350
	p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
L
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2351 2352 2353 2354 2355 2356 2357 2358 2359 2360 2361
	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);
	}
2362
	shmem_acl_destroy_inode(inode);
L
Linus Torvalds 已提交
2363 2364 2365
	kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
}

2366
static void init_once(void *foo)
L
Linus Torvalds 已提交
2367 2368 2369
{
	struct shmem_inode_info *p = (struct shmem_inode_info *) foo;

C
Christoph Lameter 已提交
2370
	inode_init_once(&p->vfs_inode);
2371
#ifdef CONFIG_TMPFS_POSIX_ACL
C
Christoph Lameter 已提交
2372 2373
	p->i_acl = NULL;
	p->i_default_acl = NULL;
2374
#endif
L
Linus Torvalds 已提交
2375 2376 2377 2378 2379 2380
}

static int init_inodecache(void)
{
	shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
				sizeof(struct shmem_inode_info),
2381
				0, SLAB_PANIC, init_once);
L
Linus Torvalds 已提交
2382 2383 2384 2385 2386
	return 0;
}

static void destroy_inodecache(void)
{
2387
	kmem_cache_destroy(shmem_inode_cachep);
L
Linus Torvalds 已提交
2388 2389
}

2390
static const struct address_space_operations shmem_aops = {
L
Linus Torvalds 已提交
2391
	.writepage	= shmem_writepage,
2392
	.set_page_dirty	= __set_page_dirty_no_writeback,
L
Linus Torvalds 已提交
2393
#ifdef CONFIG_TMPFS
2394
	.readpage	= shmem_readpage,
N
Nick Piggin 已提交
2395 2396
	.write_begin	= shmem_write_begin,
	.write_end	= shmem_write_end,
L
Linus Torvalds 已提交
2397
#endif
2398
	.migratepage	= migrate_page,
L
Linus Torvalds 已提交
2399 2400
};

2401
static const struct file_operations shmem_file_operations = {
L
Linus Torvalds 已提交
2402 2403 2404
	.mmap		= shmem_mmap,
#ifdef CONFIG_TMPFS
	.llseek		= generic_file_llseek,
H
Hugh Dickins 已提交
2405
	.read		= do_sync_read,
H
Hugh Dickins 已提交
2406
	.write		= do_sync_write,
H
Hugh Dickins 已提交
2407
	.aio_read	= shmem_file_aio_read,
H
Hugh Dickins 已提交
2408
	.aio_write	= generic_file_aio_write,
L
Linus Torvalds 已提交
2409
	.fsync		= simple_sync_file,
2410 2411
	.splice_read	= generic_file_splice_read,
	.splice_write	= generic_file_splice_write,
L
Linus Torvalds 已提交
2412 2413 2414
#endif
};

2415
static const struct inode_operations shmem_inode_operations = {
L
Linus Torvalds 已提交
2416 2417
	.truncate	= shmem_truncate,
	.setattr	= shmem_notify_change,
2418
	.truncate_range	= shmem_truncate_range,
2419 2420 2421 2422 2423 2424 2425 2426
#ifdef CONFIG_TMPFS_POSIX_ACL
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= generic_listxattr,
	.removexattr	= generic_removexattr,
	.permission	= shmem_permission,
#endif

L
Linus Torvalds 已提交
2427 2428
};

2429
static const struct inode_operations shmem_dir_inode_operations = {
L
Linus Torvalds 已提交
2430 2431 2432 2433 2434 2435 2436 2437 2438 2439 2440
#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
2441 2442 2443 2444 2445 2446 2447 2448 2449 2450
#ifdef CONFIG_TMPFS_POSIX_ACL
	.setattr	= shmem_notify_change,
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= generic_listxattr,
	.removexattr	= generic_removexattr,
	.permission	= shmem_permission,
#endif
};

2451
static const struct inode_operations shmem_special_inode_operations = {
2452 2453 2454 2455 2456 2457 2458 2459
#ifdef CONFIG_TMPFS_POSIX_ACL
	.setattr	= shmem_notify_change,
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= generic_listxattr,
	.removexattr	= generic_removexattr,
	.permission	= shmem_permission,
#endif
L
Linus Torvalds 已提交
2460 2461
};

2462
static const struct super_operations shmem_ops = {
L
Linus Torvalds 已提交
2463 2464 2465 2466 2467
	.alloc_inode	= shmem_alloc_inode,
	.destroy_inode	= shmem_destroy_inode,
#ifdef CONFIG_TMPFS
	.statfs		= shmem_statfs,
	.remount_fs	= shmem_remount_fs,
2468
	.show_options	= shmem_show_options,
L
Linus Torvalds 已提交
2469 2470 2471 2472 2473 2474 2475
#endif
	.delete_inode	= shmem_delete_inode,
	.drop_inode	= generic_delete_inode,
	.put_super	= shmem_put_super,
};

static struct vm_operations_struct shmem_vm_ops = {
2476
	.fault		= shmem_fault,
L
Linus Torvalds 已提交
2477 2478 2479 2480 2481 2482 2483
#ifdef CONFIG_NUMA
	.set_policy     = shmem_set_policy,
	.get_policy     = shmem_get_policy,
#endif
};


2484 2485
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
2486
{
2487
	return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt);
L
Linus Torvalds 已提交
2488 2489 2490 2491 2492 2493 2494 2495 2496 2497 2498 2499 2500
}

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

static int __init init_tmpfs(void)
{
	int error;

P
Peter Zijlstra 已提交
2501 2502 2503 2504
	error = bdi_init(&shmem_backing_dev_info);
	if (error)
		goto out4;

L
Linus Torvalds 已提交
2505 2506 2507 2508 2509 2510 2511 2512 2513
	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;
	}
2514

2515
	shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER,
L
Linus Torvalds 已提交
2516 2517 2518 2519 2520 2521 2522 2523 2524 2525 2526 2527 2528
				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
2529 2530
	bdi_destroy(&shmem_backing_dev_info);
out4:
L
Linus Torvalds 已提交
2531 2532 2533
	shm_mnt = ERR_PTR(error);
	return error;
}
2534 2535 2536 2537 2538 2539 2540 2541 2542 2543 2544 2545 2546 2547 2548 2549 2550 2551 2552 2553 2554 2555 2556 2557 2558 2559 2560 2561 2562 2563 2564 2565 2566 2567 2568 2569 2570 2571 2572 2573 2574 2575 2576 2577 2578

#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,
};

static int __init init_tmpfs(void)
{
	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;
}

#define shmem_file_operations ramfs_file_operations
#define shmem_vm_ops generic_file_vm_ops
#define shmem_get_inode ramfs_get_inode
#define shmem_acct_size(a, b) 0
#define shmem_unacct_size(a, b) do {} while (0)
#define SHMEM_MAX_BYTES LLONG_MAX

#endif /* CONFIG_SHMEM */

/* common code */
L
Linus Torvalds 已提交
2579

2580
/**
L
Linus Torvalds 已提交
2581 2582 2583
 * 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
2584
 * @flags: vm_flags
L
Linus Torvalds 已提交
2585 2586 2587 2588 2589 2590 2591 2592 2593 2594 2595 2596 2597 2598 2599 2600 2601 2602 2603 2604 2605 2606 2607 2608 2609 2610 2611 2612 2613 2614 2615 2616 2617 2618 2619 2620 2621
 */
struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags)
{
	int error;
	struct file *file;
	struct inode *inode;
	struct dentry *dentry, *root;
	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;
	dentry = d_alloc(root, &this);
	if (!dentry)
		goto put_memory;

	error = -ENFILE;
	file = get_empty_filp();
	if (!file)
		goto put_dentry;

	error = -ENOSPC;
	inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0);
	if (!inode)
		goto close_file;

2622
#ifdef CONFIG_SHMEM
L
Linus Torvalds 已提交
2623
	SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
2624
#endif
L
Linus Torvalds 已提交
2625 2626 2627
	d_instantiate(dentry, inode);
	inode->i_size = size;
	inode->i_nlink = 0;	/* It is unlinked */
2628
	init_file(file, shm_mnt, dentry, FMODE_WRITE | FMODE_READ,
2629 2630 2631 2632 2633 2634 2635
		  &shmem_file_operations);

#ifndef CONFIG_MMU
	error = ramfs_nommu_expand_for_mapping(inode, size);
	if (error)
		goto close_file;
#endif
L
Linus Torvalds 已提交
2636 2637 2638 2639 2640 2641 2642 2643 2644 2645
	return file;

close_file:
	put_filp(file);
put_dentry:
	dput(dentry);
put_memory:
	shmem_unacct_size(flags, size);
	return ERR_PTR(error);
}
2646
EXPORT_SYMBOL_GPL(shmem_file_setup);
L
Linus Torvalds 已提交
2647

2648
/**
L
Linus Torvalds 已提交
2649 2650 2651 2652 2653 2654 2655 2656 2657 2658 2659 2660 2661 2662 2663 2664 2665 2666
 * 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;
}
2667 2668

module_init(init_tmpfs)