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linux/mm/shmem.c

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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.
* Copyright (C) 2002-2005 Hugh Dickins.
* Copyright (C) 2002-2005 VERITAS Software Corporation.
* 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>
*
* This file is released under the GPL.
*/
/*
* 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.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/file.h>
#include <linux/swap.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/mount.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>
#include <asm/uaccess.h>
#include <asm/div64.h>
#include <asm/pgtable.h>
/* This magic number is used in glibc for posix shared memory */
#define TMPFS_MAGIC 0x01021994
#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
/* Keep swapped page count in private field of indirect struct page */
#define nr_swapped private
/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */
enum sgp_type {
SGP_QUICK, /* don't try more than file page cache lookup */
SGP_READ, /* don't exceed i_size, don't allocate page */
SGP_CACHE, /* don't exceed i_size, may allocate page */
SGP_WRITE, /* may exceed i_size, may allocate page */
};
static int shmem_getpage(struct inode *inode, unsigned long idx,
struct page **pagep, enum sgp_type sgp, int *type);
static inline struct page *shmem_dir_alloc(unsigned int gfp_mask)
{
/*
* 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.
*/
return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT);
}
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)
{
return (flags & VM_ACCOUNT)?
security_vm_enough_memory(VM_ACCT(size)): 0;
}
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)
{
return (flags & VM_ACCOUNT)?
0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE));
}
static inline void shmem_unacct_blocks(unsigned long flags, long pages)
{
if (!(flags & VM_ACCOUNT))
vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
}
static struct super_operations shmem_ops;
static struct address_space_operations shmem_aops;
static struct file_operations shmem_file_operations;
static struct inode_operations shmem_inode_operations;
static struct inode_operations shmem_dir_inode_operations;
static struct vm_operations_struct shmem_vm_ops;
static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
.ra_pages = 0, /* No readahead */
.capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK,
.unplug_io_fn = default_unplug_io_fn,
};
static LIST_HEAD(shmem_swaplist);
static DEFINE_SPINLOCK(shmem_swaplist_lock);
static void shmem_free_blocks(struct inode *inode, long pages)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_blocks) {
spin_lock(&sbinfo->stat_lock);
sbinfo->free_blocks += pages;
inode->i_blocks -= pages*BLOCKS_PER_PAGE;
spin_unlock(&sbinfo->stat_lock);
}
}
/*
* 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);
}
}
/*
* 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;
if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT)
kmap_atomic_to_page(entry)->nr_swapped += incdec;
}
/*
* shmem_swp_alloc - get the position of the swap entry for the page.
* If it does not exist allocate the entry.
*
* @info: info structure for the inode
* @index: index of the page to find
* @sgp: check and recheck i_size? skip allocation?
*/
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.
*/
if (sbinfo->max_blocks) {
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);
page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO);
if (page) {
page->nr_swapped = 0;
}
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;
}
/*
* shmem_free_swp - free some swap entries in a directory
*
* @dir: pointer to the directory
* @edir: pointer after last entry of the directory
*/
static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir)
{
swp_entry_t *ptr;
int freed = 0;
for (ptr = dir; ptr < edir; ptr++) {
if (ptr->val) {
free_swap_and_cache(*ptr);
*ptr = (swp_entry_t){0};
freed++;
}
}
return freed;
}
static int shmem_map_and_free_swp(struct page *subdir,
int offset, int limit, struct page ***dir)
{
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;
freed += shmem_free_swp(ptr+offset, ptr+offset+size);
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);
}
static void shmem_truncate(struct inode *inode)
{
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;
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
if (idx >= info->next_index)
return;
spin_lock(&info->lock);
info->flags |= SHMEM_TRUNCATE;
limit = info->next_index;
info->next_index = idx;
topdir = info->i_indirect;
if (topdir && idx <= SHMEM_NR_DIRECT) {
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;
nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size);
}
if (!topdir)
goto done2;
BUG_ON(limit <= SHMEM_NR_DIRECT);
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;
if (!diroff && !offset) {
*dir = NULL;
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;
*dir = NULL;
nr_pages_to_free++;
list_add(&middir->lru, &pages_to_free);
shmem_dir_unmap(dir);
cond_resched();
dir = shmem_dir_map(middir);
diroff = 0;
}
subdir = dir[diroff];
if (subdir && subdir->nr_swapped) {
size = limit - idx;
if (size > ENTRIES_PER_PAGE)
size = ENTRIES_PER_PAGE;
freed = shmem_map_and_free_swp(subdir,
offset, size, &dir);
if (!dir)
dir = shmem_dir_map(middir);
nr_swaps_freed += freed;
if (offset)
spin_lock(&info->lock);
subdir->nr_swapped -= freed;
if (offset)
spin_unlock(&info->lock);
BUG_ON(subdir->nr_swapped > offset);
}
if (offset)
offset = 0;
else if (subdir) {
dir[diroff] = NULL;
nr_pages_to_free++;
list_add(&subdir->lru, &pages_to_free);
}
}
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.
*/
truncate_inode_pages(inode->i_mapping, inode->i_size);
}
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);
}
}
static int shmem_notify_change(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = dentry->d_inode;
struct page *page = NULL;
int error;
if (attr->ia_valid & ATTR_SIZE) {
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);
}
/*
* 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);
if (page)
page_cache_release(page);
return error;
}
static void shmem_delete_inode(struct inode *inode)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
struct shmem_inode_info *info = SHMEM_I(inode);
if (inode->i_op->truncate == shmem_truncate) {
shmem_unacct_size(info->flags, inode->i_size);
inode->i_size = 0;
shmem_truncate(inode);
if (!list_empty(&info->swaplist)) {
spin_lock(&shmem_swaplist_lock);
list_del_init(&info->swaplist);
spin_unlock(&shmem_swaplist_lock);
}
}
BUG_ON(inode->i_blocks);
if (sbinfo->max_inodes) {
spin_lock(&sbinfo->stat_lock);
sbinfo->free_inodes++;
spin_unlock(&sbinfo->stat_lock);
}
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;
idx = 0;
ptr = info->i_direct;
spin_lock(&info->lock);
limit = info->next_index;
size = limit;
if (size > SHMEM_NR_DIRECT)
size = SHMEM_NR_DIRECT;
offset = shmem_find_swp(entry, ptr, ptr+size);
if (offset >= 0) {
shmem_swp_balance_unmap();
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);
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;
if (subdir && subdir->nr_swapped) {
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);
if (offset >= 0) {
shmem_dir_unmap(dir);
goto found;
}
shmem_swp_unmap(ptr);
}
}
lost1:
shmem_dir_unmap(dir-1);
lost2:
spin_unlock(&info->lock);
return 0;
found:
idx += offset;
inode = &info->vfs_inode;
if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) {
info->flags |= SHMEM_PAGEIN;
shmem_swp_set(info, ptr + offset, 0);
}
shmem_swp_unmap(ptr);
spin_unlock(&info->lock);
/*
* Decrement swap count even when the entry is left behind:
* try_to_unuse will skip over mms, then reincrement count.
*/
swap_free(entry);
return 1;
}
/*
* 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;
spin_lock(&shmem_swaplist_lock);
list_for_each_safe(p, next, &shmem_swaplist) {
info = list_entry(p, struct shmem_inode_info, swaplist);
if (!info->swapped)
list_del_init(&info->swaplist);
else if (shmem_unuse_inode(info, entry, page)) {
/* move head to start search for next from here */
list_move_tail(&shmem_swaplist, &info->swaplist);
found = 1;
break;
}
}
spin_unlock(&shmem_swaplist_lock);
return found;
}
/*
* 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));
BUG_ON(page_mapped(page));
mapping = page->mapping;
index = page->index;
inode = mapping->host;
info = SHMEM_I(inode);
if (info->flags & VM_LOCKED)
goto redirty;
swap = get_swap_page();
if (!swap.val)
goto redirty;
spin_lock(&info->lock);
shmem_recalc_inode(inode);
if (index >= info->next_index) {
BUG_ON(!(info->flags & SHMEM_TRUNCATE));
goto unlock;
}
entry = shmem_swp_entry(info, index, NULL);
BUG_ON(!entry);
BUG_ON(entry->val);
if (move_to_swap_cache(page, swap) == 0) {
shmem_swp_set(info, entry, swap.val);
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
if (list_empty(&info->swaplist)) {
spin_lock(&shmem_swaplist_lock);
/* move instead of add in case we're racing */
list_move_tail(&info->swaplist, &shmem_swaplist);
spin_unlock(&shmem_swaplist_lock);
}
unlock_page(page);
return 0;
}
shmem_swp_unmap(entry);
unlock:
spin_unlock(&info->lock);
swap_free(swap);
redirty:
set_page_dirty(page);
return WRITEPAGE_ACTIVATE; /* Return with the page locked */
}
#ifdef CONFIG_NUMA
static struct page *shmem_swapin_async(struct shared_policy *p,
swp_entry_t entry, unsigned long idx)
{
struct page *page;
struct vm_area_struct pvma;
/* Create a pseudo vma that just contains the policy */
memset(&pvma, 0, sizeof(struct vm_area_struct));
pvma.vm_end = PAGE_SIZE;
pvma.vm_pgoff = idx;
pvma.vm_policy = mpol_shared_policy_lookup(p, idx);
page = read_swap_cache_async(entry, &pvma, 0);
mpol_free(pvma.vm_policy);
return page;
}
struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry,
unsigned long idx)
{
struct shared_policy *p = &info->policy;
int i, num;
struct page *page;
unsigned long offset;
num = valid_swaphandles(entry, &offset);
for (i = 0; i < num; offset++, i++) {
page = shmem_swapin_async(p,
swp_entry(swp_type(entry), offset), idx);
if (!page)
break;
page_cache_release(page);
}
lru_add_drain(); /* Push any new pages onto the LRU now */
return shmem_swapin_async(p, entry, idx);
}
static struct page *
shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info,
unsigned long idx)
{
struct vm_area_struct pvma;
struct page *page;
memset(&pvma, 0, sizeof(struct vm_area_struct));
pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx);
pvma.vm_pgoff = idx;
pvma.vm_end = PAGE_SIZE;
page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0);
mpol_free(pvma.vm_policy);
return page;
}
#else
static inline struct page *
shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx)
{
swapin_readahead(entry, 0, NULL);
return read_swap_cache_async(entry, NULL, 0);
}
static inline struct page *
shmem_alloc_page(unsigned int __nocast gfp,struct shmem_inode_info *info,
unsigned long idx)
{
return alloc_page(gfp | __GFP_ZERO);
}
#endif
/*
* 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;
int error;
if (idx >= SHMEM_MAX_INDEX)
return -EFBIG;
/*
* 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.
* But shmem_prepare_write passes in a locked filepage,
* which may be found not uptodate by other callers too,
* and may need to be copied from the swappage read in.
*/
repeat:
if (!filepage)
filepage = find_lock_page(mapping, idx);
if (filepage && PageUptodate(filepage))
goto done;
error = 0;
if (sgp == SGP_QUICK)
goto failed;
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);
spin_unlock(&info->lock);
/* here we actually do the io */
if (type && *type == VM_FAULT_MINOR) {
inc_page_state(pgmajfault);
*type = VM_FAULT_MAJOR;
}
swappage = shmem_swapin(info, swap, idx);
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 */
if (TestSetPageLocked(swappage)) {
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);
} else if (!(error = move_from_swap_cache(
swappage, idx, mapping))) {
info->flags |= SHMEM_PAGEIN;
shmem_swp_set(info, entry, 0);
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
filepage = swappage;
swap_free(swap);
} else {
shmem_swp_unmap(entry);
spin_unlock(&info->lock);
unlock_page(swappage);
page_cache_release(swappage);
if (error == -ENOMEM) {
/* let kswapd refresh zone for GFP_ATOMICs */
blk_congestion_wait(WRITE, HZ/50);
}
goto repeat;
}
} else if (sgp == SGP_READ && !filepage) {
shmem_swp_unmap(entry);
filepage = find_get_page(mapping, idx);
if (filepage &&
(!PageUptodate(filepage) || TestSetPageLocked(filepage))) {
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);
if (sbinfo->max_blocks) {
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) {
spin_unlock(&info->lock);
filepage = shmem_alloc_page(mapping_gfp_mask(mapping),
info,
idx);
if (!filepage) {
shmem_unacct_blocks(info->flags, 1);
shmem_free_blocks(inode, 1);
error = -ENOMEM;
goto failed;
}
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);
}
if (error || swap.val || 0 != add_to_page_cache_lru(
filepage, mapping, idx, GFP_ATOMIC)) {
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);
flush_dcache_page(filepage);
SetPageUptodate(filepage);
}
done:
if (*pagep != filepage) {
unlock_page(filepage);
*pagep = filepage;
}
return 0;
failed:
if (*pagep != filepage) {
unlock_page(filepage);
page_cache_release(filepage);
}
return error;
}
struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type)
{
struct inode *inode = vma->vm_file->f_dentry->d_inode;
struct page *page = NULL;
unsigned long idx;
int error;
idx = (address - vma->vm_start) >> PAGE_SHIFT;
idx += vma->vm_pgoff;
idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT;
if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode))
return NOPAGE_SIGBUS;
error = shmem_getpage(inode, idx, &page, SGP_CACHE, type);
if (error)
return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS;
mark_page_accessed(page);
return page;
}
static int shmem_populate(struct vm_area_struct *vma,
unsigned long addr, unsigned long len,
pgprot_t prot, unsigned long pgoff, int nonblock)
{
struct inode *inode = vma->vm_file->f_dentry->d_inode;
struct mm_struct *mm = vma->vm_mm;
enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE;
unsigned long size;
size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT;
if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size)
return -EINVAL;
while ((long) len > 0) {
struct page *page = NULL;
int err;
/*
* Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE
*/
err = shmem_getpage(inode, pgoff, &page, sgp, NULL);
if (err)
return err;
/* Page may still be null, but only if nonblock was set. */
if (page) {
mark_page_accessed(page);
err = install_page(mm, vma, addr, page, prot);
if (err) {
page_cache_release(page);
return err;
}
} else {
/* No page was found just because we can't read it in
* now (being here implies nonblock != 0), but the page
* may exist, so set the PTE to fault it in later. */
err = install_file_pte(mm, vma, addr, pgoff, prot);
if (err)
return err;
}
len -= PAGE_SIZE;
addr += PAGE_SIZE;
pgoff++;
}
return 0;
}
#ifdef CONFIG_NUMA
int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
{
struct inode *i = vma->vm_file->f_dentry->d_inode;
return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new);
}
struct mempolicy *
shmem_get_policy(struct vm_area_struct *vma, unsigned long addr)
{
struct inode *i = vma->vm_file->f_dentry->d_inode;
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)
{
struct inode *inode = file->f_dentry->d_inode;
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;
}
if (!lock && (info->flags & VM_LOCKED) && user) {
user_shm_unlock(inode->i_size, user);
info->flags &= ~VM_LOCKED;
}
retval = 0;
out_nomem:
spin_unlock(&info->lock);
return retval;
}
static int shmem_mmap(struct file *file, struct vm_area_struct *vma)
{
file_accessed(file);
vma->vm_ops = &shmem_vm_ops;
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);
if (sbinfo->max_inodes) {
spin_lock(&sbinfo->stat_lock);
if (!sbinfo->free_inodes) {
spin_unlock(&sbinfo->stat_lock);
return NULL;
}
sbinfo->free_inodes--;
spin_unlock(&sbinfo->stat_lock);
}
inode = new_inode(sb);
if (inode) {
inode->i_mode = mode;
inode->i_uid = current->fsuid;
inode->i_gid = current->fsgid;
inode->i_blksize = PAGE_CACHE_SIZE;
inode->i_blocks = 0;
inode->i_mapping->a_ops = &shmem_aops;
inode->i_mapping->backing_dev_info = &shmem_backing_dev_info;
inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
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:
init_special_inode(inode, mode, dev);
break;
case S_IFREG:
inode->i_op = &shmem_inode_operations;
inode->i_fop = &shmem_file_operations;
mpol_shared_policy_init(&info->policy);
break;
case S_IFDIR:
inode->i_nlink++;
/* 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.
*/
mpol_shared_policy_init(&info->policy);
break;
}
} else if (sbinfo->max_inodes) {
spin_lock(&sbinfo->stat_lock);
sbinfo->free_inodes++;
spin_unlock(&sbinfo->stat_lock);
}
return inode;
}
#ifdef CONFIG_TMPFS
static struct inode_operations shmem_symlink_inode_operations;
static struct inode_operations shmem_symlink_inline_operations;
/*
* Normally tmpfs makes no use of shmem_prepare_write, but it
* lets a tmpfs file be used read-write below the loop driver.
*/
static int
shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to)
{
struct inode *inode = page->mapping->host;
return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL);
}
static ssize_t
shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos)
{
struct inode *inode = file->f_dentry->d_inode;
loff_t pos;
unsigned long written;
ssize_t err;
if ((ssize_t) count < 0)
return -EINVAL;
if (!access_ok(VERIFY_READ, buf, count))
return -EFAULT;
down(&inode->i_sem);
pos = *ppos;
written = 0;
err = generic_write_checks(file, &pos, &count, 0);
if (err || !count)
goto out;
err = remove_suid(file->f_dentry);
if (err)
goto out;
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
do {
struct page *page = NULL;
unsigned long bytes, index, offset;
char *kaddr;
int left;
offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */
index = pos >> PAGE_CACHE_SHIFT;
bytes = PAGE_CACHE_SIZE - offset;
if (bytes > count)
bytes = count;
/*
* We don't hold page lock across copy from user -
* what would it guard against? - so no deadlock here.
* But it still may be a good idea to prefault below.
*/
err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL);
if (err)
break;
left = bytes;
if (PageHighMem(page)) {
volatile unsigned char dummy;
__get_user(dummy, buf);
__get_user(dummy, buf + bytes - 1);
kaddr = kmap_atomic(page, KM_USER0);
left = __copy_from_user_inatomic(kaddr + offset,
buf, bytes);
kunmap_atomic(kaddr, KM_USER0);
}
if (left) {
kaddr = kmap(page);
left = __copy_from_user(kaddr + offset, buf, bytes);
kunmap(page);
}
written += bytes;
count -= bytes;
pos += bytes;
buf += bytes;
if (pos > inode->i_size)
i_size_write(inode, pos);
flush_dcache_page(page);
set_page_dirty(page);
mark_page_accessed(page);
page_cache_release(page);
if (left) {
pos -= left;
written -= left;
err = -EFAULT;
break;
}
/*
* Our dirty pages are not counted in nr_dirty,
* and we do not attempt to balance dirty pages.
*/
cond_resched();
} while (count);
*ppos = pos;
if (written)
err = written;
out:
up(&inode->i_sem);
return err;
}
static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor)
{
struct inode *inode = filp->f_dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
unsigned long index, offset;
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;
}
desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL);
if (desc->error) {
if (desc->error == -EINVAL)
desc->error = 0;
break;
}
/*
* We must evaluate after, since reads (unlike writes)
* are called without i_sem protection against truncate
*/
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);
} else
page = ZERO_PAGE(0);
/*
* 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);
}
static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos)
{
read_descriptor_t desc;
if ((ssize_t) count < 0)
return -EINVAL;
if (!access_ok(VERIFY_WRITE, buf, count))
return -EFAULT;
if (!count)
return 0;
desc.written = 0;
desc.count = count;
desc.arg.buf = buf;
desc.error = 0;
do_shmem_file_read(filp, ppos, &desc, file_read_actor);
if (desc.written)
return desc.written;
return desc.error;
}
static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos,
size_t count, read_actor_t actor, void *target)
{
read_descriptor_t desc;
if (!count)
return 0;
desc.written = 0;
desc.count = count;
desc.arg.data = target;
desc.error = 0;
do_shmem_file_read(in_file, ppos, &desc, actor);
if (desc.written)
return desc.written;
return desc.error;
}
static int shmem_statfs(struct super_block *sb, struct kstatfs *buf)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
buf->f_type = TMPFS_MAGIC;
buf->f_bsize = PAGE_CACHE_SIZE;
buf->f_namelen = NAME_MAX;
spin_lock(&sbinfo->stat_lock);
if (sbinfo->max_blocks) {
buf->f_blocks = sbinfo->max_blocks;
buf->f_bavail = buf->f_bfree = sbinfo->free_blocks;
}
if (sbinfo->max_inodes) {
buf->f_files = sbinfo->max_inodes;
buf->f_ffree = sbinfo->free_inodes;
}
/* else leave those fields 0 like simple_statfs */
spin_unlock(&sbinfo->stat_lock);
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) {
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 */
error = 0;
}
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;
dir->i_nlink++;
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;
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
/*
* 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.
*/
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);
}
dir->i_size += BOGO_DIRENT_SIZE;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
inode->i_nlink++;
atomic_inc(&inode->i_count); /* New dentry reference */
dget(dentry); /* Extra pinning count for the created dentry */
d_instantiate(dentry, inode);
return 0;
}
static int shmem_unlink(struct inode *dir, struct dentry *dentry)
{
struct inode *inode = dentry->d_inode;
if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) {
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_inodes) {
spin_lock(&sbinfo->stat_lock);
sbinfo->free_inodes++;
spin_unlock(&sbinfo->stat_lock);
}
}
dir->i_size -= BOGO_DIRENT_SIZE;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
inode->i_nlink--;
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;
dir->i_nlink--;
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)
old_dir->i_nlink--;
} else if (they_are_dirs) {
old_dir->i_nlink--;
new_dir->i_nlink++;
}
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;
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;
}
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;
}
static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd)
{
nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode));
return NULL;
}
static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
{
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));
return page;
}
static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie)
{
if (!IS_ERR(nd_get_link(nd))) {
struct page *page = cookie;
kunmap(page);
mark_page_accessed(page);
page_cache_release(page);
}
}
static struct inode_operations shmem_symlink_inline_operations = {
.readlink = generic_readlink,
.follow_link = shmem_follow_link_inline,
};
static struct inode_operations shmem_symlink_inode_operations = {
.truncate = shmem_truncate,
.readlink = generic_readlink,
.follow_link = shmem_follow_link,
.put_link = shmem_put_link,
};
static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes)
{
char *this_char, *value, *rest;
while ((this_char = strsep(&options, ",")) != NULL) {
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;
*blocks = size >> PAGE_CACHE_SHIFT;
} else if (!strcmp(this_char,"nr_blocks")) {
*blocks = memparse(value,&rest);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"nr_inodes")) {
*inodes = memparse(value,&rest);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"mode")) {
if (!mode)
continue;
*mode = simple_strtoul(value,&rest,8);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"uid")) {
if (!uid)
continue;
*uid = simple_strtoul(value,&rest,0);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"gid")) {
if (!gid)
continue;
*gid = simple_strtoul(value,&rest,0);
if (*rest)
goto bad_val;
} 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);
unsigned long max_blocks = sbinfo->max_blocks;
unsigned long max_inodes = sbinfo->max_inodes;
unsigned long blocks;
unsigned long inodes;
int error = -EINVAL;
if (shmem_parse_options(data, NULL, NULL, NULL,
&max_blocks, &max_inodes))
return error;
spin_lock(&sbinfo->stat_lock);
blocks = sbinfo->max_blocks - sbinfo->free_blocks;
inodes = sbinfo->max_inodes - sbinfo->free_inodes;
if (max_blocks < blocks)
goto out;
if (max_inodes < inodes)
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.
*/
if (max_blocks && !sbinfo->max_blocks)
goto out;
if (max_inodes && !sbinfo->max_inodes)
goto out;
error = 0;
sbinfo->max_blocks = max_blocks;
sbinfo->free_blocks = max_blocks - blocks;
sbinfo->max_inodes = max_inodes;
sbinfo->free_inodes = max_inodes - inodes;
out:
spin_unlock(&sbinfo->stat_lock);
return error;
}
#endif
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;
int mode = S_IRWXUGO | S_ISVTX;
uid_t uid = current->fsuid;
gid_t gid = current->fsgid;
int err = -ENOMEM;
struct shmem_sb_info *sbinfo;
unsigned long blocks = 0;
unsigned long inodes = 0;
#ifdef CONFIG_TMPFS
/*
* 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)) {
blocks = totalram_pages / 2;
inodes = totalram_pages - totalhigh_pages;
if (inodes > blocks)
inodes = blocks;
if (shmem_parse_options(data, &mode, &uid, &gid,
&blocks, &inodes))
return -EINVAL;
}
#else
sb->s_flags |= MS_NOUSER;
#endif
/* 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;
spin_lock_init(&sbinfo->stat_lock);
sbinfo->max_blocks = blocks;
sbinfo->free_blocks = blocks;
sbinfo->max_inodes = inodes;
sbinfo->free_inodes = inodes;
sb->s_fs_info = sbinfo;
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;
inode = shmem_get_inode(sb, S_IFDIR | mode, 0);
if (!inode)
goto failed;
inode->i_uid = uid;
inode->i_gid = gid;
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;
}
static kmem_cache_t *shmem_inode_cachep;
static struct inode *shmem_alloc_inode(struct super_block *sb)
{
struct shmem_inode_info *p;
p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL);
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));
}
static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags)
{
struct shmem_inode_info *p = (struct shmem_inode_info *) foo;
if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
SLAB_CTOR_CONSTRUCTOR) {
inode_init_once(&p->vfs_inode);
}
}
static int init_inodecache(void)
{
shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
sizeof(struct shmem_inode_info),
0, 0, init_once, NULL);
if (shmem_inode_cachep == NULL)
return -ENOMEM;
return 0;
}
static void destroy_inodecache(void)
{
if (kmem_cache_destroy(shmem_inode_cachep))
printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n");
}
static struct address_space_operations shmem_aops = {
.writepage = shmem_writepage,
.set_page_dirty = __set_page_dirty_nobuffers,
#ifdef CONFIG_TMPFS
.prepare_write = shmem_prepare_write,
.commit_write = simple_commit_write,
#endif
};
static struct file_operations shmem_file_operations = {
.mmap = shmem_mmap,
#ifdef CONFIG_TMPFS
.llseek = generic_file_llseek,
.read = shmem_file_read,
.write = shmem_file_write,
.fsync = simple_sync_file,
.sendfile = shmem_file_sendfile,
#endif
};
static struct inode_operations shmem_inode_operations = {
.truncate = shmem_truncate,
.setattr = shmem_notify_change,
};
static struct inode_operations shmem_dir_inode_operations = {
#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
};
static struct super_operations shmem_ops = {
.alloc_inode = shmem_alloc_inode,
.destroy_inode = shmem_destroy_inode,
#ifdef CONFIG_TMPFS
.statfs = shmem_statfs,
.remount_fs = shmem_remount_fs,
#endif
.delete_inode = shmem_delete_inode,
.drop_inode = generic_delete_inode,
.put_super = shmem_put_super,
};
static struct vm_operations_struct shmem_vm_ops = {
.nopage = shmem_nopage,
.populate = shmem_populate,
#ifdef CONFIG_NUMA
.set_policy = shmem_set_policy,
.get_policy = shmem_get_policy,
#endif
};
static struct super_block *shmem_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return get_sb_nodev(fs_type, flags, data, shmem_fill_super);
}
static struct file_system_type tmpfs_fs_type = {
.owner = THIS_MODULE,
.name = "tmpfs",
.get_sb = shmem_get_sb,
.kill_sb = kill_litter_super,
};
static struct vfsmount *shm_mnt;
static int __init init_tmpfs(void)
{
int error;
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;
}
#ifdef CONFIG_TMPFS
devfs_mk_dir("shm");
#endif
shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER,
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:
shm_mnt = ERR_PTR(error);
return error;
}
module_init(init_tmpfs)
/*
* 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
*
*/
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;
SHMEM_I(inode)->flags = flags & VM_ACCOUNT;
d_instantiate(dentry, inode);
inode->i_size = size;
inode->i_nlink = 0; /* It is unlinked */
file->f_vfsmnt = mntget(shm_mnt);
file->f_dentry = dentry;
file->f_mapping = inode->i_mapping;
file->f_op = &shmem_file_operations;
file->f_mode = FMODE_WRITE | FMODE_READ;
return file;
close_file:
put_filp(file);
put_dentry:
dput(dentry);
put_memory:
shmem_unacct_size(flags, size);
return ERR_PTR(error);
}
/*
* 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;
}
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