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linux/mm/shmem.c
Al Viro 34c80b1d93 vfs: switch ->show_options() to struct dentry * 
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2012-01-06 23:19:54 -05:00

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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) 2002-2011 Hugh Dickins.
* Copyright (C) 2011 Google Inc.
* 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>
*
* tiny-shmem:
* Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
*
* This file is released under the GPL.
*/
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/vfs.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/export.h>
#include <linux/swap.h>
static struct vfsmount *shm_mnt;
#ifdef CONFIG_SHMEM
/*
* 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/xattr.h>
#include <linux/exportfs.h>
#include <linux/posix_acl.h>
#include <linux/generic_acl.h>
#include <linux/mman.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/backing-dev.h>
#include <linux/shmem_fs.h>
#include <linux/writeback.h>
#include <linux/blkdev.h>
#include <linux/pagevec.h>
#include <linux/percpu_counter.h>
#include <linux/splice.h>
#include <linux/security.h>
#include <linux/swapops.h>
#include <linux/mempolicy.h>
#include <linux/namei.h>
#include <linux/ctype.h>
#include <linux/migrate.h>
#include <linux/highmem.h>
#include <linux/seq_file.h>
#include <linux/magic.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
/* Pretend that each entry is of this size in directory's i_size */
#define BOGO_DIRENT_SIZE 20
/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
#define SHORT_SYMLINK_LEN 128
struct shmem_xattr {
struct list_head list; /* anchored by shmem_inode_info->xattr_list */
char *name; /* xattr name */
size_t size;
char value[0];
};
/* Flag allocation requirements to shmem_getpage */
enum sgp_type {
SGP_READ, /* don't exceed i_size, don't allocate page */
SGP_CACHE, /* don't exceed i_size, may allocate page */
SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
SGP_WRITE, /* may exceed i_size, may allocate page */
};
#ifdef CONFIG_TMPFS
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);
}
#endif
static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
static inline int shmem_getpage(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp, int *fault_type)
{
return shmem_getpage_gfp(inode, index, pagep, sgp,
mapping_gfp_mask(inode->i_mapping), fault_type);
}
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_NORESERVE) ?
0 : security_vm_enough_memory_kern(VM_ACCT(size));
}
static inline void shmem_unacct_size(unsigned long flags, loff_t size)
{
if (!(flags & VM_NORESERVE))
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_NORESERVE) ?
security_vm_enough_memory_kern(VM_ACCT(PAGE_CACHE_SIZE)) : 0;
}
static inline void shmem_unacct_blocks(unsigned long flags, long pages)
{
if (flags & VM_NORESERVE)
vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
}
static const struct super_operations shmem_ops;
static const struct address_space_operations shmem_aops;
static const struct file_operations shmem_file_operations;
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;
static const 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_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
};
static LIST_HEAD(shmem_swaplist);
static DEFINE_MUTEX(shmem_swaplist_mutex);
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);
}
}
/**
* shmem_recalc_inode - recalculate the block usage 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) {
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_blocks)
percpu_counter_add(&sbinfo->used_blocks, -freed);
info->alloced -= freed;
inode->i_blocks -= freed * BLOCKS_PER_PAGE;
shmem_unacct_blocks(info->flags, freed);
}
}
/*
* Replace item expected in radix tree by a new item, while holding tree lock.
*/
static int shmem_radix_tree_replace(struct address_space *mapping,
pgoff_t index, void *expected, void *replacement)
{
void **pslot;
void *item = NULL;
VM_BUG_ON(!expected);
pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
if (pslot)
item = radix_tree_deref_slot_protected(pslot,
&mapping->tree_lock);
if (item != expected)
return -ENOENT;
if (replacement)
radix_tree_replace_slot(pslot, replacement);
else
radix_tree_delete(&mapping->page_tree, index);
return 0;
}
/*
* Like add_to_page_cache_locked, but error if expected item has gone.
*/
static int shmem_add_to_page_cache(struct page *page,
struct address_space *mapping,
pgoff_t index, gfp_t gfp, void *expected)
{
int error = 0;
VM_BUG_ON(!PageLocked(page));
VM_BUG_ON(!PageSwapBacked(page));
if (!expected)
error = radix_tree_preload(gfp & GFP_RECLAIM_MASK);
if (!error) {
page_cache_get(page);
page->mapping = mapping;
page->index = index;
spin_lock_irq(&mapping->tree_lock);
if (!expected)
error = radix_tree_insert(&mapping->page_tree,
index, page);
else
error = shmem_radix_tree_replace(mapping, index,
expected, page);
if (!error) {
mapping->nrpages++;
__inc_zone_page_state(page, NR_FILE_PAGES);
__inc_zone_page_state(page, NR_SHMEM);
spin_unlock_irq(&mapping->tree_lock);
} else {
page->mapping = NULL;
spin_unlock_irq(&mapping->tree_lock);
page_cache_release(page);
}
if (!expected)
radix_tree_preload_end();
}
if (error)
mem_cgroup_uncharge_cache_page(page);
return error;
}
/*
* Like delete_from_page_cache, but substitutes swap for page.
*/
static void shmem_delete_from_page_cache(struct page *page, void *radswap)
{
struct address_space *mapping = page->mapping;
int error;
spin_lock_irq(&mapping->tree_lock);
error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
page->mapping = NULL;
mapping->nrpages--;
__dec_zone_page_state(page, NR_FILE_PAGES);
__dec_zone_page_state(page, NR_SHMEM);
spin_unlock_irq(&mapping->tree_lock);
page_cache_release(page);
BUG_ON(error);
}
/*
* Like find_get_pages, but collecting swap entries as well as pages.
*/
static unsigned shmem_find_get_pages_and_swap(struct address_space *mapping,
pgoff_t start, unsigned int nr_pages,
struct page **pages, pgoff_t *indices)
{
unsigned int i;
unsigned int ret;
unsigned int nr_found;
rcu_read_lock();
restart:
nr_found = radix_tree_gang_lookup_slot(&mapping->page_tree,
(void ***)pages, indices, start, nr_pages);
ret = 0;
for (i = 0; i < nr_found; i++) {
struct page *page;
repeat:
page = radix_tree_deref_slot((void **)pages[i]);
if (unlikely(!page))
continue;
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page))
goto restart;
/*
* Otherwise, we must be storing a swap entry
* here as an exceptional entry: so return it
* without attempting to raise page count.
*/
goto export;
}
if (!page_cache_get_speculative(page))
goto repeat;
/* Has the page moved? */
if (unlikely(page != *((void **)pages[i]))) {
page_cache_release(page);
goto repeat;
}
export:
indices[ret] = indices[i];
pages[ret] = page;
ret++;
}
if (unlikely(!ret && nr_found))
goto restart;
rcu_read_unlock();
return ret;
}
/*
* Remove swap entry from radix tree, free the swap and its page cache.
*/
static int shmem_free_swap(struct address_space *mapping,
pgoff_t index, void *radswap)
{
int error;
spin_lock_irq(&mapping->tree_lock);
error = shmem_radix_tree_replace(mapping, index, radswap, NULL);
spin_unlock_irq(&mapping->tree_lock);
if (!error)
free_swap_and_cache(radix_to_swp_entry(radswap));
return error;
}
/*
* Pagevec may contain swap entries, so shuffle up pages before releasing.
*/
static void shmem_pagevec_release(struct pagevec *pvec)
{
int i, j;
for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];
if (!radix_tree_exceptional_entry(page))
pvec->pages[j++] = page;
}
pvec->nr = j;
pagevec_release(pvec);
}
/*
* Remove range of pages and swap entries from radix tree, and free them.
*/
void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
{
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info = SHMEM_I(inode);
pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
unsigned partial = lstart & (PAGE_CACHE_SIZE - 1);
pgoff_t end = (lend >> PAGE_CACHE_SHIFT);
struct pagevec pvec;
pgoff_t indices[PAGEVEC_SIZE];
long nr_swaps_freed = 0;
pgoff_t index;
int i;
BUG_ON((lend & (PAGE_CACHE_SIZE - 1)) != (PAGE_CACHE_SIZE - 1));
pagevec_init(&pvec, 0);
index = start;
while (index <= end) {
pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
pvec.pages, indices);
if (!pvec.nr)
break;
mem_cgroup_uncharge_start();
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
index = indices[i];
if (index > end)
break;
if (radix_tree_exceptional_entry(page)) {
nr_swaps_freed += !shmem_free_swap(mapping,
index, page);
continue;
}
if (!trylock_page(page))
continue;
if (page->mapping == mapping) {
VM_BUG_ON(PageWriteback(page));
truncate_inode_page(mapping, page);
}
unlock_page(page);
}
shmem_pagevec_release(&pvec);
mem_cgroup_uncharge_end();
cond_resched();
index++;
}
if (partial) {
struct page *page = NULL;
shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
if (page) {
zero_user_segment(page, partial, PAGE_CACHE_SIZE);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
}
}
index = start;
for ( ; ; ) {
cond_resched();
pvec.nr = shmem_find_get_pages_and_swap(mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1,
pvec.pages, indices);
if (!pvec.nr) {
if (index == start)
break;
index = start;
continue;
}
if (index == start && indices[0] > end) {
shmem_pagevec_release(&pvec);
break;
}
mem_cgroup_uncharge_start();
for (i = 0; i < pagevec_count(&pvec); i++) {
struct page *page = pvec.pages[i];
index = indices[i];
if (index > end)
break;
if (radix_tree_exceptional_entry(page)) {
nr_swaps_freed += !shmem_free_swap(mapping,
index, page);
continue;
}
lock_page(page);
if (page->mapping == mapping) {
VM_BUG_ON(PageWriteback(page));
truncate_inode_page(mapping, page);
}
unlock_page(page);
}
shmem_pagevec_release(&pvec);
mem_cgroup_uncharge_end();
index++;
}
spin_lock(&info->lock);
info->swapped -= nr_swaps_freed;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
}
EXPORT_SYMBOL_GPL(shmem_truncate_range);
static int shmem_setattr(struct dentry *dentry, struct iattr *attr)
{
struct inode *inode = dentry->d_inode;
int error;
error = inode_change_ok(inode, attr);
if (error)
return error;
if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) {
loff_t oldsize = inode->i_size;
loff_t newsize = attr->ia_size;
if (newsize != oldsize) {
i_size_write(inode, newsize);
inode->i_ctime = inode->i_mtime = CURRENT_TIME;
}
if (newsize < oldsize) {
loff_t holebegin = round_up(newsize, PAGE_SIZE);
unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
shmem_truncate_range(inode, newsize, (loff_t)-1);
/* unmap again to remove racily COWed private pages */
unmap_mapping_range(inode->i_mapping, holebegin, 0, 1);
}
}
setattr_copy(inode, attr);
#ifdef CONFIG_TMPFS_POSIX_ACL
if (attr->ia_valid & ATTR_MODE)
error = generic_acl_chmod(inode);
#endif
return error;
}
static void shmem_evict_inode(struct inode *inode)
{
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_xattr *xattr, *nxattr;
if (inode->i_mapping->a_ops == &shmem_aops) {
shmem_unacct_size(info->flags, inode->i_size);
inode->i_size = 0;
shmem_truncate_range(inode, 0, (loff_t)-1);
if (!list_empty(&info->swaplist)) {
mutex_lock(&shmem_swaplist_mutex);
list_del_init(&info->swaplist);
mutex_unlock(&shmem_swaplist_mutex);
}
} else
kfree(info->symlink);
list_for_each_entry_safe(xattr, nxattr, &info->xattr_list, list) {
kfree(xattr->name);
kfree(xattr);
}
BUG_ON(inode->i_blocks);
shmem_free_inode(inode->i_sb);
end_writeback(inode);
}
/*
* If swap found in inode, free it and move page from swapcache to filecache.
*/
static int shmem_unuse_inode(struct shmem_inode_info *info,
swp_entry_t swap, struct page *page)
{
struct address_space *mapping = info->vfs_inode.i_mapping;
void *radswap;
pgoff_t index;
int error;
radswap = swp_to_radix_entry(swap);
index = radix_tree_locate_item(&mapping->page_tree, radswap);
if (index == -1)
return 0;
/*
* Move _head_ to start search for next from here.
* But be careful: shmem_evict_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.
*/
if (shmem_swaplist.next != &info->swaplist)
list_move_tail(&shmem_swaplist, &info->swaplist);
/*
* We rely on shmem_swaplist_mutex, not only to protect the swaplist,
* but also to hold up shmem_evict_inode(): so inode cannot be freed
* beneath us (pagelock doesn't help until the page is in pagecache).
*/
error = shmem_add_to_page_cache(page, mapping, index,
GFP_NOWAIT, radswap);
/* which does mem_cgroup_uncharge_cache_page on error */
if (error != -ENOMEM) {
/*
* Truncation and eviction use free_swap_and_cache(), which
* only does trylock page: if we raced, best clean up here.
*/
delete_from_swap_cache(page);
set_page_dirty(page);
if (!error) {
spin_lock(&info->lock);
info->swapped--;
spin_unlock(&info->lock);
swap_free(swap);
}
error = 1; /* not an error, but entry was found */
}
return error;
}
/*
* Search through swapped inodes to find and replace swap by page.
*/
int shmem_unuse(swp_entry_t swap, struct page *page)
{
struct list_head *this, *next;
struct shmem_inode_info *info;
int found = 0;
int error;
/*
* Charge page using GFP_KERNEL while we can wait, before taking
* the shmem_swaplist_mutex which might hold up shmem_writepage().
* Charged back to the user (not to caller) when swap account is used.
*/
error = mem_cgroup_cache_charge(page, current->mm, GFP_KERNEL);
if (error)
goto out;
/* No radix_tree_preload: swap entry keeps a place for page in tree */
mutex_lock(&shmem_swaplist_mutex);
list_for_each_safe(this, next, &shmem_swaplist) {
info = list_entry(this, struct shmem_inode_info, swaplist);
if (info->swapped)
found = shmem_unuse_inode(info, swap, page);
else
list_del_init(&info->swaplist);
cond_resched();
if (found)
break;
}
mutex_unlock(&shmem_swaplist_mutex);
if (!found)
mem_cgroup_uncharge_cache_page(page);
if (found < 0)
error = found;
out:
unlock_page(page);
page_cache_release(page);
return error;
}
/*
* 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;
struct address_space *mapping;
struct inode *inode;
swp_entry_t swap;
pgoff_t index;
BUG_ON(!PageLocked(page));
mapping = page->mapping;
index = page->index;
inode = mapping->host;
info = SHMEM_I(inode);
if (info->flags & VM_LOCKED)
goto redirty;
if (!total_swap_pages)
goto redirty;
/*
* shmem_backing_dev_info's capabilities prevent regular writeback or
* sync from ever calling shmem_writepage; but a stacking filesystem
* might use ->writepage of its underlying filesystem, in which case
* tmpfs should write out to swap only in response to memory pressure,
* and not for the writeback threads or sync.
*/
if (!wbc->for_reclaim) {
WARN_ON_ONCE(1); /* Still happens? Tell us about it! */
goto redirty;
}
swap = get_swap_page();
if (!swap.val)
goto redirty;
/*
* Add inode to shmem_unuse()'s list of swapped-out inodes,
* if it's not already there. Do it now before the page is
* moved to swap cache, when its pagelock no longer protects
* the inode from eviction. But don't unlock the mutex until
* we've incremented swapped, because shmem_unuse_inode() will
* prune a !swapped inode from the swaplist under this mutex.
*/
mutex_lock(&shmem_swaplist_mutex);
if (list_empty(&info->swaplist))
list_add_tail(&info->swaplist, &shmem_swaplist);
if (add_to_swap_cache(page, swap, GFP_ATOMIC) == 0) {
swap_shmem_alloc(swap);
shmem_delete_from_page_cache(page, swp_to_radix_entry(swap));
spin_lock(&info->lock);
info->swapped++;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
mutex_unlock(&shmem_swaplist_mutex);
BUG_ON(page_mapped(page));
swap_writepage(page, wbc);
return 0;
}
mutex_unlock(&shmem_swaplist_mutex);
swapcache_free(swap, NULL);
redirty:
set_page_dirty(page);
if (wbc->for_reclaim)
return AOP_WRITEPAGE_ACTIVATE; /* Return with page locked */
unlock_page(page);
return 0;
}
#ifdef CONFIG_NUMA
#ifdef CONFIG_TMPFS
static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
{
char buffer[64];
if (!mpol || mpol->mode == MPOL_DEFAULT)
return; /* show nothing */
mpol_to_str(buffer, sizeof(buffer), mpol, 1);
seq_printf(seq, ",mpol=%s", buffer);
}
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;
}
#endif /* CONFIG_TMPFS */
static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
struct mempolicy mpol, *spol;
struct vm_area_struct pvma;
spol = mpol_cond_copy(&mpol,
mpol_shared_policy_lookup(&info->policy, index));
/* Create a pseudo vma that just contains the policy */
pvma.vm_start = 0;
pvma.vm_pgoff = index;
pvma.vm_ops = NULL;
pvma.vm_policy = spol;
return swapin_readahead(swap, gfp, &pvma, 0);
}
static struct page *shmem_alloc_page(gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
struct vm_area_struct pvma;
/* Create a pseudo vma that just contains the policy */
pvma.vm_start = 0;
pvma.vm_pgoff = index;
pvma.vm_ops = NULL;
pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
/*
* alloc_page_vma() will drop the shared policy reference
*/
return alloc_page_vma(gfp, &pvma, 0);
}
#else /* !CONFIG_NUMA */
#ifdef CONFIG_TMPFS
static inline void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
{
}
#endif /* CONFIG_TMPFS */
static inline struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
return swapin_readahead(swap, gfp, NULL, 0);
}
static inline struct page *shmem_alloc_page(gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
return alloc_page(gfp);
}
#endif /* CONFIG_NUMA */
#if !defined(CONFIG_NUMA) || !defined(CONFIG_TMPFS)
static inline struct mempolicy *shmem_get_sbmpol(struct shmem_sb_info *sbinfo)
{
return NULL;
}
#endif
/*
* shmem_getpage_gfp - find page in cache, or get from swap, or allocate
*
* 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_gfp(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type)
{
struct address_space *mapping = inode->i_mapping;
struct shmem_inode_info *info;
struct shmem_sb_info *sbinfo;
struct page *page;
swp_entry_t swap;
int error;
int once = 0;
if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
return -EFBIG;
repeat:
swap.val = 0;
page = find_lock_page(mapping, index);
if (radix_tree_exceptional_entry(page)) {
swap = radix_to_swp_entry(page);
page = NULL;
}
if (sgp != SGP_WRITE &&
((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
error = -EINVAL;
goto failed;
}
if (page || (sgp == SGP_READ && !swap.val)) {
/*
* Once we can get the page lock, it must be uptodate:
* if there were an error in reading back from swap,
* the page would not be inserted into the filecache.
*/
BUG_ON(page && !PageUptodate(page));
*pagep = page;
return 0;
}
/*
* Fast cache lookup did not find it:
* bring it back from swap or allocate.
*/
info = SHMEM_I(inode);
sbinfo = SHMEM_SB(inode->i_sb);
if (swap.val) {
/* Look it up and read it in.. */
page = lookup_swap_cache(swap);
if (!page) {
/* here we actually do the io */
if (fault_type)
*fault_type |= VM_FAULT_MAJOR;
page = shmem_swapin(swap, gfp, info, index);
if (!page) {
error = -ENOMEM;
goto failed;
}
}
/* We have to do this with page locked to prevent races */
lock_page(page);
if (!PageUptodate(page)) {
error = -EIO;
goto failed;
}
wait_on_page_writeback(page);
/* Someone may have already done it for us */
if (page->mapping) {
if (page->mapping == mapping &&
page->index == index)
goto done;
error = -EEXIST;
goto failed;
}
error = mem_cgroup_cache_charge(page, current->mm,
gfp & GFP_RECLAIM_MASK);
if (!error)
error = shmem_add_to_page_cache(page, mapping, index,
gfp, swp_to_radix_entry(swap));
if (error)
goto failed;
spin_lock(&info->lock);
info->swapped--;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
delete_from_swap_cache(page);
set_page_dirty(page);
swap_free(swap);
} else {
if (shmem_acct_block(info->flags)) {
error = -ENOSPC;
goto failed;
}
if (sbinfo->max_blocks) {
if (percpu_counter_compare(&sbinfo->used_blocks,
sbinfo->max_blocks) >= 0) {
error = -ENOSPC;
goto unacct;
}
percpu_counter_inc(&sbinfo->used_blocks);
}
page = shmem_alloc_page(gfp, info, index);
if (!page) {
error = -ENOMEM;
goto decused;
}
SetPageSwapBacked(page);
__set_page_locked(page);
error = mem_cgroup_cache_charge(page, current->mm,
gfp & GFP_RECLAIM_MASK);
if (!error)
error = shmem_add_to_page_cache(page, mapping, index,
gfp, NULL);
if (error)
goto decused;
lru_cache_add_anon(page);
spin_lock(&info->lock);
info->alloced++;
inode->i_blocks += BLOCKS_PER_PAGE;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
clear_highpage(page);
flush_dcache_page(page);
SetPageUptodate(page);
if (sgp == SGP_DIRTY)
set_page_dirty(page);
}
done:
/* Perhaps the file has been truncated since we checked */
if (sgp != SGP_WRITE &&
((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
error = -EINVAL;
goto trunc;
}
*pagep = page;
return 0;
/*
* Error recovery.
*/
trunc:
ClearPageDirty(page);
delete_from_page_cache(page);
spin_lock(&info->lock);
info->alloced--;
inode->i_blocks -= BLOCKS_PER_PAGE;
spin_unlock(&info->lock);
decused:
if (sbinfo->max_blocks)
percpu_counter_add(&sbinfo->used_blocks, -1);
unacct:
shmem_unacct_blocks(info->flags, 1);
failed:
if (swap.val && error != -EINVAL) {
struct page *test = find_get_page(mapping, index);
if (test && !radix_tree_exceptional_entry(test))
page_cache_release(test);
/* Have another try if the entry has changed */
if (test != swp_to_radix_entry(swap))
error = -EEXIST;
}
if (page) {
unlock_page(page);
page_cache_release(page);
}
if (error == -ENOSPC && !once++) {
info = SHMEM_I(inode);
spin_lock(&info->lock);
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
goto repeat;
}
if (error == -EEXIST)
goto repeat;
return error;
}
static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
int error;
int ret = VM_FAULT_LOCKED;
error = shmem_getpage(inode, vmf->pgoff, &vmf->page, SGP_CACHE, &ret);
if (error)
return ((error == -ENOMEM) ? VM_FAULT_OOM : VM_FAULT_SIGBUS);
if (ret & VM_FAULT_MAJOR) {
count_vm_event(PGMAJFAULT);
mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
}
return ret;
}
#ifdef CONFIG_NUMA
static int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *mpol)
{
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
return mpol_set_shared_policy(&SHMEM_I(inode)->policy, vma, mpol);
}
static struct mempolicy *shmem_get_policy(struct vm_area_struct *vma,
unsigned long addr)
{
struct inode *inode = vma->vm_file->f_path.dentry->d_inode;
pgoff_t index;
index = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
return mpol_shared_policy_lookup(&SHMEM_I(inode)->policy, index);
}
#endif
int shmem_lock(struct file *file, int lock, struct user_struct *user)
{
struct inode *inode = file->f_path.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;
mapping_set_unevictable(file->f_mapping);
}
if (!lock && (info->flags & VM_LOCKED) && user) {
user_shm_unlock(inode->i_size, user);
info->flags &= ~VM_LOCKED;
mapping_clear_unevictable(file->f_mapping);
/*
* Ensure that a racing putback_lru_page() can see
* the pages of this mapping are evictable when we
* skip them due to !PageLRU during the scan.
*/
smp_mb__after_clear_bit();
scan_mapping_unevictable_pages(file->f_mapping);
}
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;
vma->vm_flags |= VM_CAN_NONLINEAR;
return 0;
}
static struct inode *shmem_get_inode(struct super_block *sb, const struct inode *dir,
umode_t mode, dev_t dev, unsigned long flags)
{
struct inode *inode;
struct shmem_inode_info *info;
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
if (shmem_reserve_inode(sb))
return NULL;
inode = new_inode(sb);
if (inode) {
inode->i_ino = get_next_ino();
inode_init_owner(inode, dir, mode);
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;
inode->i_generation = get_seconds();
info = SHMEM_I(inode);
memset(info, 0, (char *)inode - (char *)info);
spin_lock_init(&info->lock);
info->flags = flags & VM_NORESERVE;
INIT_LIST_HEAD(&info->swaplist);
INIT_LIST_HEAD(&info->xattr_list);
cache_no_acl(inode);
switch (mode & S_IFMT) {
default:
inode->i_op = &shmem_special_inode_operations;
init_special_inode(inode, mode, dev);
break;
case S_IFREG:
inode->i_mapping->a_ops = &shmem_aops;
inode->i_op = &shmem_inode_operations;
inode->i_fop = &shmem_file_operations;
mpol_shared_policy_init(&info->policy,
shmem_get_sbmpol(sbinfo));
break;
case S_IFDIR:
inc_nlink(inode);
/* 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, NULL);
break;
}
} else
shmem_free_inode(sb);
return inode;
}
#ifdef CONFIG_TMPFS
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_short_symlink_operations;
static int
shmem_write_begin(struct file *file, struct address_space *mapping,
loff_t pos, unsigned len, unsigned flags,
struct page **pagep, void **fsdata)
{
struct inode *inode = mapping->host;
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
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;
if (pos + copied > inode->i_size)
i_size_write(inode, pos + copied);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
return copied;
}
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_path.dentry->d_inode;
struct address_space *mapping = inode->i_mapping;
pgoff_t index;
unsigned long offset;
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;
index = *ppos >> PAGE_CACHE_SHIFT;
offset = *ppos & ~PAGE_CACHE_MASK;
for (;;) {
struct page *page = NULL;
pgoff_t end_index;
unsigned long 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, NULL);
if (desc->error) {
if (desc->error == -EINVAL)
desc->error = 0;
break;
}
if (page)
unlock_page(page);
/*
* We must evaluate after, since reads (unlike writes)
* are called without i_mutex 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);
page_cache_get(page);
}
/*
* 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_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;
}
static ssize_t shmem_file_splice_read(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe, size_t len,
unsigned int flags)
{
struct address_space *mapping = in->f_mapping;
struct inode *inode = mapping->host;
unsigned int loff, nr_pages, req_pages;
struct page *pages[PIPE_DEF_BUFFERS];
struct partial_page partial[PIPE_DEF_BUFFERS];
struct page *page;
pgoff_t index, end_index;
loff_t isize, left;
int error, page_nr;
struct splice_pipe_desc spd = {
.pages = pages,
.partial = partial,
.flags = flags,
.ops = &page_cache_pipe_buf_ops,
.spd_release = spd_release_page,
};
isize = i_size_read(inode);
if (unlikely(*ppos >= isize))
return 0;
left = isize - *ppos;
if (unlikely(left < len))
len = left;
if (splice_grow_spd(pipe, &spd))
return -ENOMEM;
index = *ppos >> PAGE_CACHE_SHIFT;
loff = *ppos & ~PAGE_CACHE_MASK;
req_pages = (len + loff + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
nr_pages = min(req_pages, pipe->buffers);
spd.nr_pages = find_get_pages_contig(mapping, index,
nr_pages, spd.pages);
index += spd.nr_pages;
error = 0;
while (spd.nr_pages < nr_pages) {
error = shmem_getpage(inode, index, &page, SGP_CACHE, NULL);
if (error)
break;
unlock_page(page);
spd.pages[spd.nr_pages++] = page;
index++;
}
index = *ppos >> PAGE_CACHE_SHIFT;
nr_pages = spd.nr_pages;
spd.nr_pages = 0;
for (page_nr = 0; page_nr < nr_pages; page_nr++) {
unsigned int this_len;
if (!len)
break;
this_len = min_t(unsigned long, len, PAGE_CACHE_SIZE - loff);
page = spd.pages[page_nr];
if (!PageUptodate(page) || page->mapping != mapping) {
error = shmem_getpage(inode, index, &page,
SGP_CACHE, NULL);
if (error)
break;
unlock_page(page);
page_cache_release(spd.pages[page_nr]);
spd.pages[page_nr] = page;
}
isize = i_size_read(inode);
end_index = (isize - 1) >> PAGE_CACHE_SHIFT;
if (unlikely(!isize || index > end_index))
break;
if (end_index == index) {
unsigned int plen;
plen = ((isize - 1) & ~PAGE_CACHE_MASK) + 1;
if (plen <= loff)
break;
this_len = min(this_len, plen - loff);
len = this_len;
}
spd.partial[page_nr].offset = loff;
spd.partial[page_nr].len = this_len;
len -= this_len;
loff = 0;
spd.nr_pages++;
index++;
}
while (page_nr < nr_pages)
page_cache_release(spd.pages[page_nr++]);
if (spd.nr_pages)
error = splice_to_pipe(pipe, &spd);
splice_shrink_spd(pipe, &spd);
if (error > 0) {
*ppos += error;
file_accessed(in);
}
return error;
}
static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb);
buf->f_type = TMPFS_MAGIC;
buf->f_bsize = PAGE_CACHE_SIZE;
buf->f_namelen = NAME_MAX;
if (sbinfo->max_blocks) {
buf->f_blocks = sbinfo->max_blocks;
buf->f_bavail =
buf->f_bfree = sbinfo->max_blocks -
percpu_counter_sum(&sbinfo->used_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 */
return 0;
}
/*
* File creation. Allocate an inode, and we're done..
*/
static int
shmem_mknod(struct inode *dir, struct dentry *dentry, umode_t mode, dev_t dev)
{
struct inode *inode;
int error = -ENOSPC;
inode = shmem_get_inode(dir->i_sb, dir, mode, dev, VM_NORESERVE);
if (inode) {
error = security_inode_init_security(inode, dir,
&dentry->d_name,
NULL, NULL);
if (error) {
if (error != -EOPNOTSUPP) {
iput(inode);
return error;
}
}
#ifdef CONFIG_TMPFS_POSIX_ACL
error = generic_acl_init(inode, dir);
if (error) {
iput(inode);
return error;
}
#else
error = 0;
#endif
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, umode_t mode)
{
int error;
if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0)))
return error;
inc_nlink(dir);
return 0;
}
static int shmem_create(struct inode *dir, struct dentry *dentry, umode_t 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;
int ret;
/*
* 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.
*/
ret = shmem_reserve_inode(inode->i_sb);
if (ret)
goto out;
dir->i_size += BOGO_DIRENT_SIZE;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
inc_nlink(inode);
ihold(inode); /* New dentry reference */
dget(dentry); /* Extra pinning count for the created dentry */
d_instantiate(dentry, inode);
out:
return ret;
}
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))
shmem_free_inode(inode->i_sb);
dir->i_size -= BOGO_DIRENT_SIZE;
inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
drop_nlink(inode);
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;
drop_nlink(dentry->d_inode);
drop_nlink(dir);
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)
drop_nlink(old_dir);
} else if (they_are_dirs) {
drop_nlink(old_dir);
inc_nlink(new_dir);
}
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;
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, dir, S_IFLNK|S_IRWXUGO, 0, VM_NORESERVE);
if (!inode)
return -ENOSPC;
error = security_inode_init_security(inode, dir, &dentry->d_name,
NULL, NULL);
if (error) {
if (error != -EOPNOTSUPP) {
iput(inode);
return error;
}
error = 0;
}
info = SHMEM_I(inode);
inode->i_size = len-1;
if (len <= SHORT_SYMLINK_LEN) {
info->symlink = kmemdup(symname, len, GFP_KERNEL);
if (!info->symlink) {
iput(inode);
return -ENOMEM;
}
inode->i_op = &shmem_short_symlink_operations;
} else {
error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL);
if (error) {
iput(inode);
return error;
}
inode->i_mapping->a_ops = &shmem_aops;
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);
unlock_page(page);
page_cache_release(page);
}
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_short_symlink(struct dentry *dentry, struct nameidata *nd)
{
nd_set_link(nd, SHMEM_I(dentry->d_inode)->symlink);
return NULL;
}
static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd)
{
struct page *page = NULL;
int error = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL);
nd_set_link(nd, error ? ERR_PTR(error) : kmap(page));
if (page)
unlock_page(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);
}
}
#ifdef CONFIG_TMPFS_XATTR
/*
* Superblocks without xattr inode operations may get some security.* xattr
* support from the LSM "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 int shmem_xattr_get(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
struct shmem_inode_info *info;
struct shmem_xattr *xattr;
int ret = -ENODATA;
info = SHMEM_I(dentry->d_inode);
spin_lock(&info->lock);
list_for_each_entry(xattr, &info->xattr_list, list) {
if (strcmp(name, xattr->name))
continue;
ret = xattr->size;
if (buffer) {
if (size < xattr->size)
ret = -ERANGE;
else
memcpy(buffer, xattr->value, xattr->size);
}
break;
}
spin_unlock(&info->lock);
return ret;
}
static int shmem_xattr_set(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
struct inode *inode = dentry->d_inode;
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_xattr *xattr;
struct shmem_xattr *new_xattr = NULL;
size_t len;
int err = 0;
/* value == NULL means remove */
if (value) {
/* wrap around? */
len = sizeof(*new_xattr) + size;
if (len <= sizeof(*new_xattr))
return -ENOMEM;
new_xattr = kmalloc(len, GFP_KERNEL);
if (!new_xattr)
return -ENOMEM;
new_xattr->name = kstrdup(name, GFP_KERNEL);
if (!new_xattr->name) {
kfree(new_xattr);
return -ENOMEM;
}
new_xattr->size = size;
memcpy(new_xattr->value, value, size);
}
spin_lock(&info->lock);
list_for_each_entry(xattr, &info->xattr_list, list) {
if (!strcmp(name, xattr->name)) {
if (flags & XATTR_CREATE) {
xattr = new_xattr;
err = -EEXIST;
} else if (new_xattr) {
list_replace(&xattr->list, &new_xattr->list);
} else {
list_del(&xattr->list);
}
goto out;
}
}
if (flags & XATTR_REPLACE) {
xattr = new_xattr;
err = -ENODATA;
} else {
list_add(&new_xattr->list, &info->xattr_list);
xattr = NULL;
}
out:
spin_unlock(&info->lock);
if (xattr)
kfree(xattr->name);
kfree(xattr);
return err;
}
static const struct xattr_handler *shmem_xattr_handlers[] = {
#ifdef CONFIG_TMPFS_POSIX_ACL
&generic_acl_access_handler,
&generic_acl_default_handler,
#endif
NULL
};
static int shmem_xattr_validate(const char *name)
{
struct { const char *prefix; size_t len; } arr[] = {
{ XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN },
{ XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN }
};
int i;
for (i = 0; i < ARRAY_SIZE(arr); i++) {
size_t preflen = arr[i].len;
if (strncmp(name, arr[i].prefix, preflen) == 0) {
if (!name[preflen])
return -EINVAL;
return 0;
}
}
return -EOPNOTSUPP;
}
static ssize_t shmem_getxattr(struct dentry *dentry, const char *name,
void *buffer, size_t size)
{
int err;
/*
* If this is a request for a synthetic attribute in the system.*
* namespace use the generic infrastructure to resolve a handler
* for it via sb->s_xattr.
*/
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_getxattr(dentry, name, buffer, size);
err = shmem_xattr_validate(name);
if (err)
return err;
return shmem_xattr_get(dentry, name, buffer, size);
}
static int shmem_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
int err;
/*
* If this is a request for a synthetic attribute in the system.*
* namespace use the generic infrastructure to resolve a handler
* for it via sb->s_xattr.
*/
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_setxattr(dentry, name, value, size, flags);
err = shmem_xattr_validate(name);
if (err)
return err;
if (size == 0)
value = ""; /* empty EA, do not remove */
return shmem_xattr_set(dentry, name, value, size, flags);
}
static int shmem_removexattr(struct dentry *dentry, const char *name)
{
int err;
/*
* If this is a request for a synthetic attribute in the system.*
* namespace use the generic infrastructure to resolve a handler
* for it via sb->s_xattr.
*/
if (!strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN))
return generic_removexattr(dentry, name);
err = shmem_xattr_validate(name);
if (err)
return err;
return shmem_xattr_set(dentry, name, NULL, 0, XATTR_REPLACE);
}
static bool xattr_is_trusted(const char *name)
{
return !strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN);
}
static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
bool trusted = capable(CAP_SYS_ADMIN);
struct shmem_xattr *xattr;
struct shmem_inode_info *info;
size_t used = 0;
info = SHMEM_I(dentry->d_inode);
spin_lock(&info->lock);
list_for_each_entry(xattr, &info->xattr_list, list) {
size_t len;
/* skip "trusted." attributes for unprivileged callers */
if (!trusted && xattr_is_trusted(xattr->name))
continue;
len = strlen(xattr->name) + 1;
used += len;
if (buffer) {
if (size < used) {
used = -ERANGE;
break;
}
memcpy(buffer, xattr->name, len);
buffer += len;
}
}
spin_unlock(&info->lock);
return used;
}
#endif /* CONFIG_TMPFS_XATTR */
static const struct inode_operations shmem_short_symlink_operations = {
.readlink = generic_readlink,
.follow_link = shmem_follow_short_symlink,
#ifdef CONFIG_TMPFS_XATTR
.setxattr = shmem_setxattr,
.getxattr = shmem_getxattr,
.listxattr = shmem_listxattr,
.removexattr = shmem_removexattr,
#endif
};
static const struct inode_operations shmem_symlink_inode_operations = {
.readlink = generic_readlink,
.follow_link = shmem_follow_link,
.put_link = shmem_put_link,
#ifdef CONFIG_TMPFS_XATTR
.setxattr = shmem_setxattr,
.getxattr = shmem_getxattr,
.listxattr = shmem_listxattr,
.removexattr = shmem_removexattr,
#endif
};
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;
}
static struct dentry *shmem_fh_to_dentry(struct super_block *sb,
struct fid *fid, int fh_len, int fh_type)
{
struct inode *inode;
struct dentry *dentry = NULL;
u64 inum = fid->raw[2];
inum = (inum << 32) | fid->raw[1];
if (fh_len < 3)
return NULL;
inode = ilookup5(sb, (unsigned long)(inum + fid->raw[0]),
shmem_match, fid->raw);
if (inode) {
dentry = d_find_alias(inode);
iput(inode);
}
return dentry;
}
static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len,
int connectable)
{
struct inode *inode = dentry->d_inode;
if (*len < 3) {
*len = 3;
return 255;
}
if (inode_unhashed(inode)) {
/* 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 (inode_unhashed(inode))
__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;
}
static const struct export_operations shmem_export_ops = {
.get_parent = shmem_get_parent,
.encode_fh = shmem_encode_fh,
.fh_to_dentry = shmem_fh_to_dentry,
};
static int shmem_parse_options(char *options, struct shmem_sb_info *sbinfo,
bool remount)
{
char *this_char, *value, *rest;
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;
}
}
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;
sbinfo->max_blocks =
DIV_ROUND_UP(size, PAGE_CACHE_SIZE);
} else if (!strcmp(this_char,"nr_blocks")) {
sbinfo->max_blocks = memparse(value, &rest);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"nr_inodes")) {
sbinfo->max_inodes = memparse(value, &rest);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"mode")) {
if (remount)
continue;
sbinfo->mode = simple_strtoul(value, &rest, 8) & 07777;
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"uid")) {
if (remount)
continue;
sbinfo->uid = simple_strtoul(value, &rest, 0);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"gid")) {
if (remount)
continue;
sbinfo->gid = simple_strtoul(value, &rest, 0);
if (*rest)
goto bad_val;
} else if (!strcmp(this_char,"mpol")) {
if (mpol_parse_str(value, &sbinfo->mpol, 1))
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);
struct shmem_sb_info config = *sbinfo;
unsigned long inodes;
int error = -EINVAL;
if (shmem_parse_options(data, &config, true))
return error;
spin_lock(&sbinfo->stat_lock);
inodes = sbinfo->max_inodes - sbinfo->free_inodes;
if (percpu_counter_compare(&sbinfo->used_blocks, config.max_blocks) > 0)
goto out;
if (config.max_inodes < inodes)
goto out;
/*
* Those tests disallow limited->unlimited while any are in use;
* but we must separately disallow unlimited->limited, because
* in that case we have no record of how much is already in use.
*/
if (config.max_blocks && !sbinfo->max_blocks)
goto out;
if (config.max_inodes && !sbinfo->max_inodes)
goto out;
error = 0;
sbinfo->max_blocks = config.max_blocks;
sbinfo->max_inodes = config.max_inodes;
sbinfo->free_inodes = config.max_inodes - inodes;
mpol_put(sbinfo->mpol);
sbinfo->mpol = config.mpol; /* transfers initial ref */
out:
spin_unlock(&sbinfo->stat_lock);
return error;
}
static int shmem_show_options(struct seq_file *seq, struct dentry *root)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(root->d_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=%03ho", sbinfo->mode);
if (sbinfo->uid != 0)
seq_printf(seq, ",uid=%u", sbinfo->uid);
if (sbinfo->gid != 0)
seq_printf(seq, ",gid=%u", sbinfo->gid);
shmem_show_mpol(seq, sbinfo->mpol);
return 0;
}
#endif /* CONFIG_TMPFS */
static void shmem_put_super(struct super_block *sb)
{
struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
percpu_counter_destroy(&sbinfo->used_blocks);
kfree(sbinfo);
sb->s_fs_info = NULL;
}
int shmem_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
struct dentry *root;
struct shmem_sb_info *sbinfo;
int err = -ENOMEM;
/* Round up to L1_CACHE_BYTES to resist false sharing */
sbinfo = kzalloc(max((int)sizeof(struct shmem_sb_info),
L1_CACHE_BYTES), GFP_KERNEL);
if (!sbinfo)
return -ENOMEM;
sbinfo->mode = S_IRWXUGO | S_ISVTX;
sbinfo->uid = current_fsuid();
sbinfo->gid = current_fsgid();
sb->s_fs_info = sbinfo;
#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)) {
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;
}
}
sb->s_export_op = &shmem_export_ops;
#else
sb->s_flags |= MS_NOUSER;
#endif
spin_lock_init(&sbinfo->stat_lock);
if (percpu_counter_init(&sbinfo->used_blocks, 0))
goto failed;
sbinfo->free_inodes = sbinfo->max_inodes;
sb->s_maxbytes = MAX_LFS_FILESIZE;
sb->s_blocksize = PAGE_CACHE_SIZE;
sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
sb->s_magic = TMPFS_MAGIC;
sb->s_op = &shmem_ops;
sb->s_time_gran = 1;
#ifdef CONFIG_TMPFS_XATTR
sb->s_xattr = shmem_xattr_handlers;
#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
sb->s_flags |= MS_POSIXACL;
#endif
inode = shmem_get_inode(sb, NULL, S_IFDIR | sbinfo->mode, 0, VM_NORESERVE);
if (!inode)
goto failed;
inode->i_uid = sbinfo->uid;
inode->i_gid = sbinfo->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 struct kmem_cache *shmem_inode_cachep;
static struct inode *shmem_alloc_inode(struct super_block *sb)
{
struct shmem_inode_info *info;
info = kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL);
if (!info)
return NULL;
return &info->vfs_inode;
}
static void shmem_destroy_callback(struct rcu_head *head)
{
struct inode *inode = container_of(head, struct inode, i_rcu);
kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode));
}
static void shmem_destroy_inode(struct inode *inode)
{
if (S_ISREG(inode->i_mode))
mpol_free_shared_policy(&SHMEM_I(inode)->policy);
call_rcu(&inode->i_rcu, shmem_destroy_callback);
}
static void shmem_init_inode(void *foo)
{
struct shmem_inode_info *info = foo;
inode_init_once(&info->vfs_inode);
}
static int shmem_init_inodecache(void)
{
shmem_inode_cachep = kmem_cache_create("shmem_inode_cache",
sizeof(struct shmem_inode_info),
0, SLAB_PANIC, shmem_init_inode);
return 0;
}
static void shmem_destroy_inodecache(void)
{
kmem_cache_destroy(shmem_inode_cachep);
}
static const struct address_space_operations shmem_aops = {
.writepage = shmem_writepage,
.set_page_dirty = __set_page_dirty_no_writeback,
#ifdef CONFIG_TMPFS
.write_begin = shmem_write_begin,
.write_end = shmem_write_end,
#endif
.migratepage = migrate_page,
.error_remove_page = generic_error_remove_page,
};
static const struct file_operations shmem_file_operations = {
.mmap = shmem_mmap,
#ifdef CONFIG_TMPFS
.llseek = generic_file_llseek,
.read = do_sync_read,
.write = do_sync_write,
.aio_read = shmem_file_aio_read,
.aio_write = generic_file_aio_write,
.fsync = noop_fsync,
.splice_read = shmem_file_splice_read,
.splice_write = generic_file_splice_write,
#endif
};
static const struct inode_operations shmem_inode_operations = {
.setattr = shmem_setattr,
.truncate_range = shmem_truncate_range,
#ifdef CONFIG_TMPFS_XATTR
.setxattr = shmem_setxattr,
.getxattr = shmem_getxattr,
.listxattr = shmem_listxattr,
.removexattr = shmem_removexattr,
#endif
};
static const 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
#ifdef CONFIG_TMPFS_XATTR
.setxattr = shmem_setxattr,
.getxattr = shmem_getxattr,
.listxattr = shmem_listxattr,
.removexattr = shmem_removexattr,
#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
.setattr = shmem_setattr,
#endif
};
static const struct inode_operations shmem_special_inode_operations = {
#ifdef CONFIG_TMPFS_XATTR
.setxattr = shmem_setxattr,
.getxattr = shmem_getxattr,
.listxattr = shmem_listxattr,
.removexattr = shmem_removexattr,
#endif
#ifdef CONFIG_TMPFS_POSIX_ACL
.setattr = shmem_setattr,
#endif
};
static const 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,
.show_options = shmem_show_options,
#endif
.evict_inode = shmem_evict_inode,
.drop_inode = generic_delete_inode,
.put_super = shmem_put_super,
};
static const struct vm_operations_struct shmem_vm_ops = {
.fault = shmem_fault,
#ifdef CONFIG_NUMA
.set_policy = shmem_set_policy,
.get_policy = shmem_get_policy,
#endif
};
static struct dentry *shmem_mount(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data)
{
return mount_nodev(fs_type, flags, data, shmem_fill_super);
}
static struct file_system_type shmem_fs_type = {
.owner = THIS_MODULE,
.name = "tmpfs",
.mount = shmem_mount,
.kill_sb = kill_litter_super,
};
int __init shmem_init(void)
{
int error;
error = bdi_init(&shmem_backing_dev_info);
if (error)
goto out4;
error = shmem_init_inodecache();
if (error)
goto out3;
error = register_filesystem(&shmem_fs_type);
if (error) {
printk(KERN_ERR "Could not register tmpfs\n");
goto out2;
}
shm_mnt = vfs_kern_mount(&shmem_fs_type, MS_NOUSER,
shmem_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(&shmem_fs_type);
out2:
shmem_destroy_inodecache();
out3:
bdi_destroy(&shmem_backing_dev_info);
out4:
shm_mnt = ERR_PTR(error);
return error;
}
#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 shmem_fs_type = {
.name = "tmpfs",
.mount = ramfs_mount,
.kill_sb = kill_litter_super,
};
int __init shmem_init(void)
{
BUG_ON(register_filesystem(&shmem_fs_type) != 0);
shm_mnt = kern_mount(&shmem_fs_type);
BUG_ON(IS_ERR(shm_mnt));
return 0;
}
int shmem_unuse(swp_entry_t swap, struct page *page)
{
return 0;
}
int shmem_lock(struct file *file, int lock, struct user_struct *user)
{
return 0;
}
void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
{
truncate_inode_pages_range(inode->i_mapping, lstart, lend);
}
EXPORT_SYMBOL_GPL(shmem_truncate_range);
#define shmem_vm_ops generic_file_vm_ops
#define shmem_file_operations ramfs_file_operations
#define shmem_get_inode(sb, dir, mode, dev, flags) ramfs_get_inode(sb, dir, mode, dev)
#define shmem_acct_size(flags, size) 0
#define shmem_unacct_size(flags, size) do {} while (0)
#endif /* CONFIG_SHMEM */
/* common code */
/**
* 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
* @flags: VM_NORESERVE suppresses pre-accounting of the entire object size
*/
struct file *shmem_file_setup(const char *name, loff_t size, unsigned long flags)
{
int error;
struct file *file;
struct inode *inode;
struct path path;
struct dentry *root;
struct qstr this;
if (IS_ERR(shm_mnt))
return (void *)shm_mnt;
if (size < 0 || size > MAX_LFS_FILESIZE)
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;
path.dentry = d_alloc(root, &this);
if (!path.dentry)
goto put_memory;
path.mnt = mntget(shm_mnt);
error = -ENOSPC;
inode = shmem_get_inode(root->d_sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
if (!inode)
goto put_dentry;
d_instantiate(path.dentry, inode);
inode->i_size = size;
clear_nlink(inode); /* It is unlinked */
#ifndef CONFIG_MMU
error = ramfs_nommu_expand_for_mapping(inode, size);
if (error)
goto put_dentry;
#endif
error = -ENFILE;
file = alloc_file(&path, FMODE_WRITE | FMODE_READ,
&shmem_file_operations);
if (!file)
goto put_dentry;
return file;
put_dentry:
path_put(&path);
put_memory:
shmem_unacct_size(flags, size);
return ERR_PTR(error);
}
EXPORT_SYMBOL_GPL(shmem_file_setup);
/**
* 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;
vma->vm_flags |= VM_CAN_NONLINEAR;
return 0;
}
/**
* shmem_read_mapping_page_gfp - read into page cache, using specified page allocation flags.
* @mapping: the page's address_space
* @index: the page index
* @gfp: the page allocator flags to use if allocating
*
* This behaves as a tmpfs "read_cache_page_gfp(mapping, index, gfp)",
* with any new page allocations done using the specified allocation flags.
* But read_cache_page_gfp() uses the ->readpage() method: which does not
* suit tmpfs, since it may have pages in swapcache, and needs to find those
* for itself; although drivers/gpu/drm i915 and ttm rely upon this support.
*
* i915_gem_object_get_pages_gtt() mixes __GFP_NORETRY | __GFP_NOWARN in
* with the mapping_gfp_mask(), to avoid OOMing the machine unnecessarily.
*/
struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
pgoff_t index, gfp_t gfp)
{
#ifdef CONFIG_SHMEM
struct inode *inode = mapping->host;
struct page *page;
int error;
BUG_ON(mapping->a_ops != &shmem_aops);
error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, gfp, NULL);
if (error)
page = ERR_PTR(error);
else
unlock_page(page);
return page;
#else
/*
* The tiny !SHMEM case uses ramfs without swap
*/
return read_cache_page_gfp(mapping, index, gfp);
#endif
}
EXPORT_SYMBOL_GPL(shmem_read_mapping_page_gfp);
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