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kernel-fxtec-pro1x/mm/shmem.c
Josef Bacik afa2db2fb6 tmpfs: truncate prealloc blocks past i_size 
One of the rocksdb people noticed that when you do something like this

    fallocate(fd, FALLOC_FL_KEEP_SIZE, 0, 10M)
    pwrite(fd, buf, 5M, 0)
    ftruncate(5M)

on tmpfs, the file would still take up 10M: which led to super fun
issues because we were getting ENOSPC before we thought we should be
getting ENOSPC.  This patch fixes the problem, and mirrors what all the
other fs'es do (and was agreed to be the correct behaviour at LSF).

I tested it locally to make sure it worked properly with the following

    xfs_io -f -c "falloc -k 0 10M" -c "pwrite 0 5M" -c "truncate 5M" file

Without the patch we have "Blocks: 20480", with the patch we have the
correct value of "Blocks: 10240".

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2015-06-24 17:49:45 -07:00

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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/ramfs.h>
#include <linux/pagemap.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/export.h>
#include <linux/swap.h>
#include <linux/uio.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/posix_acl_xattr.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/falloc.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 <linux/syscalls.h>
#include <linux/fcntl.h>
#include <uapi/linux/memfd.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
/*
* shmem_fallocate communicates with shmem_fault or shmem_writepage via
* inode->i_private (with i_mutex making sure that it has only one user at
* a time): we would prefer not to enlarge the shmem inode just for that.
*/
struct shmem_falloc {
wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
pgoff_t start; /* start of range currently being fallocated */
pgoff_t next; /* the next page offset to be fallocated */
pgoff_t nr_falloced; /* how many new pages have been fallocated */
pgoff_t nr_unswapped; /* how often writepage refused to swap out */
};
/* 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 !Uptodate page */
SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
};
#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 bool shmem_should_replace_page(struct page *page, gfp_t gfp);
static int shmem_replace_page(struct page **pagep, gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index);
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_mm(current->mm, 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));
}
static inline int shmem_reacct_size(unsigned long flags,
loff_t oldsize, loff_t newsize)
{
if (!(flags & VM_NORESERVE)) {
if (VM_ACCT(newsize) > VM_ACCT(oldsize))
return security_vm_enough_memory_mm(current->mm,
VM_ACCT(newsize) - VM_ACCT(oldsize));
else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
}
return 0;
}
/*
* ... 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_mm(current->mm, 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 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;
VM_BUG_ON(!expected);
VM_BUG_ON(!replacement);
pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
if (!pslot)
return -ENOENT;
item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
if (item != expected)
return -ENOENT;
radix_tree_replace_slot(pslot, replacement);
return 0;
}
/*
* Sometimes, before we decide whether to proceed or to fail, we must check
* that an entry was not already brought back from swap by a racing thread.
*
* Checking page is not enough: by the time a SwapCache page is locked, it
* might be reused, and again be SwapCache, using the same swap as before.
*/
static bool shmem_confirm_swap(struct address_space *mapping,
pgoff_t index, swp_entry_t swap)
{
void *item;
rcu_read_lock();
item = radix_tree_lookup(&mapping->page_tree, index);
rcu_read_unlock();
return item == swp_to_radix_entry(swap);
}
/*
* 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, void *expected)
{
int error;
VM_BUG_ON_PAGE(!PageLocked(page), page);
VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
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);
}
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);
}
/*
* 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)
{
void *old;
spin_lock_irq(&mapping->tree_lock);
old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
spin_unlock_irq(&mapping->tree_lock);
if (old != radswap)
return -ENOENT;
free_swap_and_cache(radix_to_swp_entry(radswap));
return 0;
}
/*
* SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
*/
void shmem_unlock_mapping(struct address_space *mapping)
{
struct pagevec pvec;
pgoff_t indices[PAGEVEC_SIZE];
pgoff_t index = 0;
pagevec_init(&pvec, 0);
/*
* Minor point, but we might as well stop if someone else SHM_LOCKs it.
*/
while (!mapping_unevictable(mapping)) {
/*
* Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
* has finished, if it hits a row of PAGEVEC_SIZE swap entries.
*/
pvec.nr = find_get_entries(mapping, index,
PAGEVEC_SIZE, pvec.pages, indices);
if (!pvec.nr)
break;
index = indices[pvec.nr - 1] + 1;
pagevec_remove_exceptionals(&pvec);
check_move_unevictable_pages(pvec.pages, pvec.nr);
pagevec_release(&pvec);
cond_resched();
}
}
/*
* Remove range of pages and swap entries from radix tree, and free them.
* If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
*/
static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
bool unfalloc)
{
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;
pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
struct pagevec pvec;
pgoff_t indices[PAGEVEC_SIZE];
long nr_swaps_freed = 0;
pgoff_t index;
int i;
if (lend == -1)
end = -1; /* unsigned, so actually very big */
pagevec_init(&pvec, 0);
index = start;
while (index < end) {
pvec.nr = find_get_entries(mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE),
pvec.pages, indices);
if (!pvec.nr)
break;
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)) {
if (unfalloc)
continue;
nr_swaps_freed += !shmem_free_swap(mapping,
index, page);
continue;
}
if (!trylock_page(page))
continue;
if (!unfalloc || !PageUptodate(page)) {
if (page->mapping == mapping) {
VM_BUG_ON_PAGE(PageWriteback(page), page);
truncate_inode_page(mapping, page);
}
}
unlock_page(page);
}
pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
cond_resched();
index++;
}
if (partial_start) {
struct page *page = NULL;
shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
if (page) {
unsigned int top = PAGE_CACHE_SIZE;
if (start > end) {
top = partial_end;
partial_end = 0;
}
zero_user_segment(page, partial_start, top);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
}
}
if (partial_end) {
struct page *page = NULL;
shmem_getpage(inode, end, &page, SGP_READ, NULL);
if (page) {
zero_user_segment(page, 0, partial_end);
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
}
}
if (start >= end)
return;
index = start;
while (index < end) {
cond_resched();
pvec.nr = find_get_entries(mapping, index,
min(end - index, (pgoff_t)PAGEVEC_SIZE),
pvec.pages, indices);
if (!pvec.nr) {
/* If all gone or hole-punch or unfalloc, we're done */
if (index == start || end != -1)
break;
/* But if truncating, restart to make sure all gone */
index = start;
continue;
}
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)) {
if (unfalloc)
continue;
if (shmem_free_swap(mapping, index, page)) {
/* Swap was replaced by page: retry */
index--;
break;
}
nr_swaps_freed++;
continue;
}
lock_page(page);
if (!unfalloc || !PageUptodate(page)) {
if (page->mapping == mapping) {
VM_BUG_ON_PAGE(PageWriteback(page), page);
truncate_inode_page(mapping, page);
} else {
/* Page was replaced by swap: retry */
unlock_page(page);
index--;
break;
}
}
unlock_page(page);
}
pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
index++;
}
spin_lock(&info->lock);
info->swapped -= nr_swaps_freed;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
}
void shmem_truncate_range(struct inode *inode, loff_t lstart, loff_t lend)
{
shmem_undo_range(inode, lstart, lend, false);
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 = d_inode(dentry);
struct shmem_inode_info *info = SHMEM_I(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;
/* protected by i_mutex */
if ((newsize < oldsize && (info->seals & F_SEAL_SHRINK)) ||
(newsize > oldsize && (info->seals & F_SEAL_GROW)))
return -EPERM;
if (newsize != oldsize) {
error = shmem_reacct_size(SHMEM_I(inode)->flags,
oldsize, newsize);
if (error)
return error;
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);
if (attr->ia_valid & ATTR_MODE)
error = posix_acl_chmod(inode, inode->i_mode);
return error;
}
static void shmem_evict_inode(struct inode *inode)
{
struct shmem_inode_info *info = SHMEM_I(inode);
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);
simple_xattrs_free(&info->xattrs);
WARN_ON(inode->i_blocks);
shmem_free_inode(inode->i_sb);
clear_inode(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 **pagep)
{
struct address_space *mapping = info->vfs_inode.i_mapping;
void *radswap;
pgoff_t index;
gfp_t gfp;
int error = 0;
radswap = swp_to_radix_entry(swap);
index = radix_tree_locate_item(&mapping->page_tree, radswap);
if (index == -1)
return -EAGAIN; /* tell shmem_unuse we found nothing */
/*
* 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);
gfp = mapping_gfp_mask(mapping);
if (shmem_should_replace_page(*pagep, gfp)) {
mutex_unlock(&shmem_swaplist_mutex);
error = shmem_replace_page(pagep, gfp, info, index);
mutex_lock(&shmem_swaplist_mutex);
/*
* We needed to drop mutex to make that restrictive page
* allocation, but the inode might have been freed while we
* dropped it: although a racing shmem_evict_inode() cannot
* complete without emptying the radix_tree, our page lock
* on this swapcache page is not enough to prevent that -
* free_swap_and_cache() of our swap entry will only
* trylock_page(), removing swap from radix_tree whatever.
*
* We must not proceed to shmem_add_to_page_cache() if the
* inode has been freed, but of course we cannot rely on
* inode or mapping or info to check that. However, we can
* safely check if our swap entry is still in use (and here
* it can't have got reused for another page): if it's still
* in use, then the inode cannot have been freed yet, and we
* can safely proceed (if it's no longer in use, that tells
* nothing about the inode, but we don't need to unuse swap).
*/
if (!page_swapcount(*pagep))
error = -ENOENT;
}
/*
* 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).
*/
if (!error)
error = shmem_add_to_page_cache(*pagep, mapping, index,
radswap);
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(*pagep);
set_page_dirty(*pagep);
if (!error) {
spin_lock(&info->lock);
info->swapped--;
spin_unlock(&info->lock);
swap_free(swap);
}
}
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;
struct mem_cgroup *memcg;
int error = 0;
/*
* There's a faint possibility that swap page was replaced before
* caller locked it: caller will come back later with the right page.
*/
if (unlikely(!PageSwapCache(page) || page_private(page) != swap.val))
goto out;
/*
* 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_try_charge(page, current->mm, GFP_KERNEL, &memcg);
if (error)
goto out;
/* No radix_tree_preload: swap entry keeps a place for page in tree */
error = -EAGAIN;
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)
error = shmem_unuse_inode(info, swap, &page);
else
list_del_init(&info->swaplist);
cond_resched();
if (error != -EAGAIN)
break;
/* found nothing in this: move on to search the next */
}
mutex_unlock(&shmem_swaplist_mutex);
if (error) {
if (error != -ENOMEM)
error = 0;
mem_cgroup_cancel_charge(page, memcg);
} else
mem_cgroup_commit_charge(page, memcg, true);
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;
/*
* Our 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;
}
/*
* This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC
* value into swapfile.c, the only way we can correctly account for a
* fallocated page arriving here is now to initialize it and write it.
*
* That's okay for a page already fallocated earlier, but if we have
* not yet completed the fallocation, then (a) we want to keep track
* of this page in case we have to undo it, and (b) it may not be a
* good idea to continue anyway, once we're pushing into swap. So
* reactivate the page, and let shmem_fallocate() quit when too many.
*/
if (!PageUptodate(page)) {
if (inode->i_private) {
struct shmem_falloc *shmem_falloc;
spin_lock(&inode->i_lock);
shmem_falloc = inode->i_private;
if (shmem_falloc &&
!shmem_falloc->waitq &&
index >= shmem_falloc->start &&
index < shmem_falloc->next)
shmem_falloc->nr_unswapped++;
else
shmem_falloc = NULL;
spin_unlock(&inode->i_lock);
if (shmem_falloc)
goto redirty;
}
clear_highpage(page);
flush_dcache_page(page);
SetPageUptodate(page);
}
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);
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);
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 vm_area_struct pvma;
struct page *page;
/* Create a pseudo vma that just contains the policy */
pvma.vm_start = 0;
/* Bias interleave by inode number to distribute better across nodes */
pvma.vm_pgoff = index + info->vfs_inode.i_ino;
pvma.vm_ops = NULL;
pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
page = swapin_readahead(swap, gfp, &pvma, 0);
/* Drop reference taken by mpol_shared_policy_lookup() */
mpol_cond_put(pvma.vm_policy);
return page;
}
static struct page *shmem_alloc_page(gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
struct vm_area_struct pvma;
struct page *page;
/* Create a pseudo vma that just contains the policy */
pvma.vm_start = 0;
/* Bias interleave by inode number to distribute better across nodes */
pvma.vm_pgoff = index + info->vfs_inode.i_ino;
pvma.vm_ops = NULL;
pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index);
page = alloc_page_vma(gfp, &pvma, 0);
/* Drop reference taken by mpol_shared_policy_lookup() */
mpol_cond_put(pvma.vm_policy);
return page;
}
#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
/*
* When a page is moved from swapcache to shmem filecache (either by the
* usual swapin of shmem_getpage_gfp(), or by the less common swapoff of
* shmem_unuse_inode()), it may have been read in earlier from swap, in
* ignorance of the mapping it belongs to. If that mapping has special
* constraints (like the gma500 GEM driver, which requires RAM below 4GB),
* we may need to copy to a suitable page before moving to filecache.
*
* In a future release, this may well be extended to respect cpuset and
* NUMA mempolicy, and applied also to anonymous pages in do_swap_page();
* but for now it is a simple matter of zone.
*/
static bool shmem_should_replace_page(struct page *page, gfp_t gfp)
{
return page_zonenum(page) > gfp_zone(gfp);
}
static int shmem_replace_page(struct page **pagep, gfp_t gfp,
struct shmem_inode_info *info, pgoff_t index)
{
struct page *oldpage, *newpage;
struct address_space *swap_mapping;
pgoff_t swap_index;
int error;
oldpage = *pagep;
swap_index = page_private(oldpage);
swap_mapping = page_mapping(oldpage);
/*
* We have arrived here because our zones are constrained, so don't
* limit chance of success by further cpuset and node constraints.
*/
gfp &= ~GFP_CONSTRAINT_MASK;
newpage = shmem_alloc_page(gfp, info, index);
if (!newpage)
return -ENOMEM;
page_cache_get(newpage);
copy_highpage(newpage, oldpage);
flush_dcache_page(newpage);
__set_page_locked(newpage);
SetPageUptodate(newpage);
SetPageSwapBacked(newpage);
set_page_private(newpage, swap_index);
SetPageSwapCache(newpage);
/*
* Our caller will very soon move newpage out of swapcache, but it's
* a nice clean interface for us to replace oldpage by newpage there.
*/
spin_lock_irq(&swap_mapping->tree_lock);
error = shmem_radix_tree_replace(swap_mapping, swap_index, oldpage,
newpage);
if (!error) {
__inc_zone_page_state(newpage, NR_FILE_PAGES);
__dec_zone_page_state(oldpage, NR_FILE_PAGES);
}
spin_unlock_irq(&swap_mapping->tree_lock);
if (unlikely(error)) {
/*
* Is this possible? I think not, now that our callers check
* both PageSwapCache and page_private after getting page lock;
* but be defensive. Reverse old to newpage for clear and free.
*/
oldpage = newpage;
} else {
mem_cgroup_migrate(oldpage, newpage, true);
lru_cache_add_anon(newpage);
*pagep = newpage;
}
ClearPageSwapCache(oldpage);
set_page_private(oldpage, 0);
unlock_page(oldpage);
page_cache_release(oldpage);
page_cache_release(oldpage);
return error;
}
/*
* 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 mem_cgroup *memcg;
struct page *page;
swp_entry_t swap;
int error;
int once = 0;
int alloced = 0;
if (index > (MAX_LFS_FILESIZE >> PAGE_CACHE_SHIFT))
return -EFBIG;
repeat:
swap.val = 0;
page = find_lock_entry(mapping, index);
if (radix_tree_exceptional_entry(page)) {
swap = radix_to_swp_entry(page);
page = NULL;
}
if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
error = -EINVAL;
goto failed;
}
if (page && sgp == SGP_WRITE)
mark_page_accessed(page);
/* fallocated page? */
if (page && !PageUptodate(page)) {
if (sgp != SGP_READ)
goto clear;
unlock_page(page);
page_cache_release(page);
page = NULL;
}
if (page || (sgp == SGP_READ && !swap.val)) {
*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 (!PageSwapCache(page) || page_private(page) != swap.val ||
!shmem_confirm_swap(mapping, index, swap)) {
error = -EEXIST; /* try again */
goto unlock;
}
if (!PageUptodate(page)) {
error = -EIO;
goto failed;
}
wait_on_page_writeback(page);
if (shmem_should_replace_page(page, gfp)) {
error = shmem_replace_page(&page, gfp, info, index);
if (error)
goto failed;
}
error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
if (!error) {
error = shmem_add_to_page_cache(page, mapping, index,
swp_to_radix_entry(swap));
/*
* We already confirmed swap under page lock, and make
* no memory allocation here, so usually no possibility
* of error; but free_swap_and_cache() only trylocks a
* page, so it is just possible that the entry has been
* truncated or holepunched since swap was confirmed.
* shmem_undo_range() will have done some of the
* unaccounting, now delete_from_swap_cache() will do
* the rest.
* Reset swap.val? No, leave it so "failed" goes back to
* "repeat": reading a hole and writing should succeed.
*/
if (error) {
mem_cgroup_cancel_charge(page, memcg);
delete_from_swap_cache(page);
}
}
if (error)
goto failed;
mem_cgroup_commit_charge(page, memcg, true);
spin_lock(&info->lock);
info->swapped--;
shmem_recalc_inode(inode);
spin_unlock(&info->lock);
if (sgp == SGP_WRITE)
mark_page_accessed(page);
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);
if (sgp == SGP_WRITE)
__SetPageReferenced(page);
error = mem_cgroup_try_charge(page, current->mm, gfp, &memcg);
if (error)
goto decused;
error = radix_tree_maybe_preload(gfp & GFP_RECLAIM_MASK);
if (!error) {
error = shmem_add_to_page_cache(page, mapping, index,
NULL);
radix_tree_preload_end();
}
if (error) {
mem_cgroup_cancel_charge(page, memcg);
goto decused;
}
mem_cgroup_commit_charge(page, memcg, false);
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);
alloced = true;
/*
* Let SGP_FALLOC use the SGP_WRITE optimization on a new page.
*/
if (sgp == SGP_FALLOC)
sgp = SGP_WRITE;
clear:
/*
* Let SGP_WRITE caller clear ends if write does not fill page;
* but SGP_FALLOC on a page fallocated earlier must initialize
* it now, lest undo on failure cancel our earlier guarantee.
*/
if (sgp != SGP_WRITE) {
clear_highpage(page);
flush_dcache_page(page);
SetPageUptodate(page);
}
if (sgp == SGP_DIRTY)
set_page_dirty(page);
}
/* Perhaps the file has been truncated since we checked */
if (sgp != SGP_WRITE && sgp != SGP_FALLOC &&
((loff_t)index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) {
error = -EINVAL;
if (alloced)
goto trunc;
else
goto failed;
}
*pagep = page;
return 0;
/*
* Error recovery.
*/
trunc:
info = SHMEM_I(inode);
ClearPageDirty(page);
delete_from_page_cache(page);
spin_lock(&info->lock);
info->alloced--;
inode->i_blocks -= BLOCKS_PER_PAGE;
spin_unlock(&info->lock);
decused:
sbinfo = SHMEM_SB(inode->i_sb);
if (sbinfo->max_blocks)
percpu_counter_add(&sbinfo->used_blocks, -1);
unacct:
shmem_unacct_blocks(info->flags, 1);
failed:
if (swap.val && error != -EINVAL &&
!shmem_confirm_swap(mapping, index, swap))
error = -EEXIST;
unlock:
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) /* from above or from radix_tree_insert */
goto repeat;
return error;
}
static int shmem_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct inode *inode = file_inode(vma->vm_file);
int error;
int ret = VM_FAULT_LOCKED;
/*
* Trinity finds that probing a hole which tmpfs is punching can
* prevent the hole-punch from ever completing: which in turn
* locks writers out with its hold on i_mutex. So refrain from
* faulting pages into the hole while it's being punched. Although
* shmem_undo_range() does remove the additions, it may be unable to
* keep up, as each new page needs its own unmap_mapping_range() call,
* and the i_mmap tree grows ever slower to scan if new vmas are added.
*
* It does not matter if we sometimes reach this check just before the
* hole-punch begins, so that one fault then races with the punch:
* we just need to make racing faults a rare case.
*
* The implementation below would be much simpler if we just used a
* standard mutex or completion: but we cannot take i_mutex in fault,
* and bloating every shmem inode for this unlikely case would be sad.
*/
if (unlikely(inode->i_private)) {
struct shmem_falloc *shmem_falloc;
spin_lock(&inode->i_lock);
shmem_falloc = inode->i_private;
if (shmem_falloc &&
shmem_falloc->waitq &&
vmf->pgoff >= shmem_falloc->start &&
vmf->pgoff < shmem_falloc->next) {
wait_queue_head_t *shmem_falloc_waitq;
DEFINE_WAIT(shmem_fault_wait);
ret = VM_FAULT_NOPAGE;
if ((vmf->flags & FAULT_FLAG_ALLOW_RETRY) &&
!(vmf->flags & FAULT_FLAG_RETRY_NOWAIT)) {
/* It's polite to up mmap_sem if we can */
up_read(&vma->vm_mm->mmap_sem);
ret = VM_FAULT_RETRY;
}
shmem_falloc_waitq = shmem_falloc->waitq;
prepare_to_wait(shmem_falloc_waitq, &shmem_fault_wait,
TASK_UNINTERRUPTIBLE);
spin_unlock(&inode->i_lock);
schedule();
/*
* shmem_falloc_waitq points into the shmem_fallocate()
* stack of the hole-punching task: shmem_falloc_waitq
* is usually invalid by the time we reach here, but
* finish_wait() does not dereference it in that case;
* though i_lock needed lest racing with wake_up_all().
*/
spin_lock(&inode->i_lock);
finish_wait(shmem_falloc_waitq, &shmem_fault_wait);
spin_unlock(&inode->i_lock);
return ret;
}
spin_unlock(&inode->i_lock);
}
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 = file_inode(vma->vm_file);
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 = file_inode(vma->vm_file);
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_inode(file);
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);
}
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, 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_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->seals = F_SEAL_SEAL;
info->flags = flags & VM_NORESERVE;
INIT_LIST_HEAD(&info->swaplist);
simple_xattrs_init(&info->xattrs);
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;
}
bool shmem_mapping(struct address_space *mapping)
{
if (!mapping->host)
return false;
return mapping->host->i_sb->s_op == &shmem_ops;
}
#ifdef CONFIG_TMPFS
static const struct inode_operations shmem_symlink_inode_operations;
static const struct inode_operations shmem_short_symlink_operations;
#ifdef CONFIG_TMPFS_XATTR
static int shmem_initxattrs(struct inode *, const struct xattr *, void *);
#else
#define shmem_initxattrs NULL
#endif
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;
struct shmem_inode_info *info = SHMEM_I(inode);
pgoff_t index = pos >> PAGE_CACHE_SHIFT;
/* i_mutex is held by caller */
if (unlikely(info->seals)) {
if (info->seals & F_SEAL_WRITE)
return -EPERM;
if ((info->seals & F_SEAL_GROW) && pos + len > inode->i_size)
return -EPERM;
}
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);
if (!PageUptodate(page)) {
if (copied < PAGE_CACHE_SIZE) {
unsigned from = pos & (PAGE_CACHE_SIZE - 1);
zero_user_segments(page, 0, from,
from + copied, PAGE_CACHE_SIZE);
}
SetPageUptodate(page);
}
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
return copied;
}
static ssize_t shmem_file_read_iter(struct kiocb *iocb, struct iov_iter *to)
{
struct file *file = iocb->ki_filp;
struct inode *inode = file_inode(file);
struct address_space *mapping = inode->i_mapping;
pgoff_t index;
unsigned long offset;
enum sgp_type sgp = SGP_READ;
int error = 0;
ssize_t retval = 0;
loff_t *ppos = &iocb->ki_pos;
/*
* 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 (!iter_is_iovec(to))
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;
}
error = shmem_getpage(inode, index, &page, sgp, NULL);
if (error) {
if (error == -EINVAL)
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...
*/
ret = copy_page_to_iter(page, offset, nr, to);
retval += ret;
offset += ret;
index += offset >> PAGE_CACHE_SHIFT;
offset &= ~PAGE_CACHE_MASK;
page_cache_release(page);
if (!iov_iter_count(to))
break;
if (ret < nr) {
error = -EFAULT;
break;
}
cond_resched();
}
*ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset;
file_accessed(file);
return retval ? retval : error;
}
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,
.nr_pages_max = PIPE_DEF_BUFFERS,
.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, spd.nr_pages_max);
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(&spd);
if (error > 0) {
*ppos += error;
file_accessed(in);
}
return error;
}
/*
* llseek SEEK_DATA or SEEK_HOLE through the radix_tree.
*/
static pgoff_t shmem_seek_hole_data(struct address_space *mapping,
pgoff_t index, pgoff_t end, int whence)
{
struct page *page;
struct pagevec pvec;
pgoff_t indices[PAGEVEC_SIZE];
bool done = false;
int i;
pagevec_init(&pvec, 0);
pvec.nr = 1; /* start small: we may be there already */
while (!done) {
pvec.nr = find_get_entries(mapping, index,
pvec.nr, pvec.pages, indices);
if (!pvec.nr) {
if (whence == SEEK_DATA)
index = end;
break;
}
for (i = 0; i < pvec.nr; i++, index++) {
if (index < indices[i]) {
if (whence == SEEK_HOLE) {
done = true;
break;
}
index = indices[i];
}
page = pvec.pages[i];
if (page && !radix_tree_exceptional_entry(page)) {
if (!PageUptodate(page))
page = NULL;
}
if (index >= end ||
(page && whence == SEEK_DATA) ||
(!page && whence == SEEK_HOLE)) {
done = true;
break;
}
}
pagevec_remove_exceptionals(&pvec);
pagevec_release(&pvec);
pvec.nr = PAGEVEC_SIZE;
cond_resched();
}
return index;
}
static loff_t shmem_file_llseek(struct file *file, loff_t offset, int whence)
{
struct address_space *mapping = file->f_mapping;
struct inode *inode = mapping->host;
pgoff_t start, end;
loff_t new_offset;
if (whence != SEEK_DATA && whence != SEEK_HOLE)
return generic_file_llseek_size(file, offset, whence,
MAX_LFS_FILESIZE, i_size_read(inode));
mutex_lock(&inode->i_mutex);
/* We're holding i_mutex so we can access i_size directly */
if (offset < 0)
offset = -EINVAL;
else if (offset >= inode->i_size)
offset = -ENXIO;
else {
start = offset >> PAGE_CACHE_SHIFT;
end = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
new_offset = shmem_seek_hole_data(mapping, start, end, whence);
new_offset <<= PAGE_CACHE_SHIFT;
if (new_offset > offset) {
if (new_offset < inode->i_size)
offset = new_offset;
else if (whence == SEEK_DATA)
offset = -ENXIO;
else
offset = inode->i_size;
}
}
if (offset >= 0)
offset = vfs_setpos(file, offset, MAX_LFS_FILESIZE);
mutex_unlock(&inode->i_mutex);
return offset;
}
/*
* We need a tag: a new tag would expand every radix_tree_node by 8 bytes,
* so reuse a tag which we firmly believe is never set or cleared on shmem.
*/
#define SHMEM_TAG_PINNED PAGECACHE_TAG_TOWRITE
#define LAST_SCAN 4 /* about 150ms max */
static void shmem_tag_pins(struct address_space *mapping)
{
struct radix_tree_iter iter;
void **slot;
pgoff_t start;
struct page *page;
lru_add_drain();
start = 0;
rcu_read_lock();
restart:
radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
page = radix_tree_deref_slot(slot);
if (!page || radix_tree_exception(page)) {
if (radix_tree_deref_retry(page))
goto restart;
} else if (page_count(page) - page_mapcount(page) > 1) {
spin_lock_irq(&mapping->tree_lock);
radix_tree_tag_set(&mapping->page_tree, iter.index,
SHMEM_TAG_PINNED);
spin_unlock_irq(&mapping->tree_lock);
}
if (need_resched()) {
cond_resched_rcu();
start = iter.index + 1;
goto restart;
}
}
rcu_read_unlock();
}
/*
* Setting SEAL_WRITE requires us to verify there's no pending writer. However,
* via get_user_pages(), drivers might have some pending I/O without any active
* user-space mappings (eg., direct-IO, AIO). Therefore, we look at all pages
* and see whether it has an elevated ref-count. If so, we tag them and wait for
* them to be dropped.
* The caller must guarantee that no new user will acquire writable references
* to those pages to avoid races.
*/
static int shmem_wait_for_pins(struct address_space *mapping)
{
struct radix_tree_iter iter;
void **slot;
pgoff_t start;
struct page *page;
int error, scan;
shmem_tag_pins(mapping);
error = 0;
for (scan = 0; scan <= LAST_SCAN; scan++) {
if (!radix_tree_tagged(&mapping->page_tree, SHMEM_TAG_PINNED))
break;
if (!scan)
lru_add_drain_all();
else if (schedule_timeout_killable((HZ << scan) / 200))
scan = LAST_SCAN;
start = 0;
rcu_read_lock();
restart:
radix_tree_for_each_tagged(slot, &mapping->page_tree, &iter,
start, SHMEM_TAG_PINNED) {
page = radix_tree_deref_slot(slot);
if (radix_tree_exception(page)) {
if (radix_tree_deref_retry(page))
goto restart;
page = NULL;
}
if (page &&
page_count(page) - page_mapcount(page) != 1) {
if (scan < LAST_SCAN)
goto continue_resched;
/*
* On the last scan, we clean up all those tags
* we inserted; but make a note that we still
* found pages pinned.
*/
error = -EBUSY;
}
spin_lock_irq(&mapping->tree_lock);
radix_tree_tag_clear(&mapping->page_tree,
iter.index, SHMEM_TAG_PINNED);
spin_unlock_irq(&mapping->tree_lock);
continue_resched:
if (need_resched()) {
cond_resched_rcu();
start = iter.index + 1;
goto restart;
}
}
rcu_read_unlock();
}
return error;
}
#define F_ALL_SEALS (F_SEAL_SEAL | \
F_SEAL_SHRINK | \
F_SEAL_GROW | \
F_SEAL_WRITE)
int shmem_add_seals(struct file *file, unsigned int seals)
{
struct inode *inode = file_inode(file);
struct shmem_inode_info *info = SHMEM_I(inode);
int error;
/*
* SEALING
* Sealing allows multiple parties to share a shmem-file but restrict
* access to a specific subset of file operations. Seals can only be
* added, but never removed. This way, mutually untrusted parties can
* share common memory regions with a well-defined policy. A malicious
* peer can thus never perform unwanted operations on a shared object.
*
* Seals are only supported on special shmem-files and always affect
* the whole underlying inode. Once a seal is set, it may prevent some
* kinds of access to the file. Currently, the following seals are
* defined:
* SEAL_SEAL: Prevent further seals from being set on this file
* SEAL_SHRINK: Prevent the file from shrinking
* SEAL_GROW: Prevent the file from growing
* SEAL_WRITE: Prevent write access to the file
*
* As we don't require any trust relationship between two parties, we
* must prevent seals from being removed. Therefore, sealing a file
* only adds a given set of seals to the file, it never touches
* existing seals. Furthermore, the "setting seals"-operation can be
* sealed itself, which basically prevents any further seal from being
* added.
*
* Semantics of sealing are only defined on volatile files. Only
* anonymous shmem files support sealing. More importantly, seals are
* never written to disk. Therefore, there's no plan to support it on
* other file types.
*/
if (file->f_op != &shmem_file_operations)
return -EINVAL;
if (!(file->f_mode & FMODE_WRITE))
return -EPERM;
if (seals & ~(unsigned int)F_ALL_SEALS)
return -EINVAL;
mutex_lock(&inode->i_mutex);
if (info->seals & F_SEAL_SEAL) {
error = -EPERM;
goto unlock;
}
if ((seals & F_SEAL_WRITE) && !(info->seals & F_SEAL_WRITE)) {
error = mapping_deny_writable(file->f_mapping);
if (error)
goto unlock;
error = shmem_wait_for_pins(file->f_mapping);
if (error) {
mapping_allow_writable(file->f_mapping);
goto unlock;
}
}
info->seals |= seals;
error = 0;
unlock:
mutex_unlock(&inode->i_mutex);
return error;
}
EXPORT_SYMBOL_GPL(shmem_add_seals);
int shmem_get_seals(struct file *file)
{
if (file->f_op != &shmem_file_operations)
return -EINVAL;
return SHMEM_I(file_inode(file))->seals;
}
EXPORT_SYMBOL_GPL(shmem_get_seals);
long shmem_fcntl(struct file *file, unsigned int cmd, unsigned long arg)
{
long error;
switch (cmd) {
case F_ADD_SEALS:
/* disallow upper 32bit */
if (arg > UINT_MAX)
return -EINVAL;
error = shmem_add_seals(file, arg);
break;
case F_GET_SEALS:
error = shmem_get_seals(file);
break;
default:
error = -EINVAL;
break;
}
return error;
}
static long shmem_fallocate(struct file *file, int mode, loff_t offset,
loff_t len)
{
struct inode *inode = file_inode(file);
struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
struct shmem_inode_info *info = SHMEM_I(inode);
struct shmem_falloc shmem_falloc;
pgoff_t start, index, end;
int error;
if (mode & ~(FALLOC_FL_KEEP_SIZE | FALLOC_FL_PUNCH_HOLE))
return -EOPNOTSUPP;
mutex_lock(&inode->i_mutex);
if (mode & FALLOC_FL_PUNCH_HOLE) {
struct address_space *mapping = file->f_mapping;
loff_t unmap_start = round_up(offset, PAGE_SIZE);
loff_t unmap_end = round_down(offset + len, PAGE_SIZE) - 1;
DECLARE_WAIT_QUEUE_HEAD_ONSTACK(shmem_falloc_waitq);
/* protected by i_mutex */
if (info->seals & F_SEAL_WRITE) {
error = -EPERM;
goto out;
}
shmem_falloc.waitq = &shmem_falloc_waitq;
shmem_falloc.start = unmap_start >> PAGE_SHIFT;
shmem_falloc.next = (unmap_end + 1) >> PAGE_SHIFT;
spin_lock(&inode->i_lock);
inode->i_private = &shmem_falloc;
spin_unlock(&inode->i_lock);
if ((u64)unmap_end > (u64)unmap_start)
unmap_mapping_range(mapping, unmap_start,
1 + unmap_end - unmap_start, 0);
shmem_truncate_range(inode, offset, offset + len - 1);
/* No need to unmap again: hole-punching leaves COWed pages */
spin_lock(&inode->i_lock);
inode->i_private = NULL;
wake_up_all(&shmem_falloc_waitq);
spin_unlock(&inode->i_lock);
error = 0;
goto out;
}
/* We need to check rlimit even when FALLOC_FL_KEEP_SIZE */
error = inode_newsize_ok(inode, offset + len);
if (error)
goto out;
if ((info->seals & F_SEAL_GROW) && offset + len > inode->i_size) {
error = -EPERM;
goto out;
}
start = offset >> PAGE_CACHE_SHIFT;
end = (offset + len + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
/* Try to avoid a swapstorm if len is impossible to satisfy */
if (sbinfo->max_blocks && end - start > sbinfo->max_blocks) {
error = -ENOSPC;
goto out;
}
shmem_falloc.waitq = NULL;
shmem_falloc.start = start;
shmem_falloc.next = start;
shmem_falloc.nr_falloced = 0;
shmem_falloc.nr_unswapped = 0;
spin_lock(&inode->i_lock);
inode->i_private = &shmem_falloc;
spin_unlock(&inode->i_lock);
for (index = start; index < end; index++) {
struct page *page;
/*
* Good, the fallocate(2) manpage permits EINTR: we may have
* been interrupted because we are using up too much memory.
*/
if (signal_pending(current))
error = -EINTR;
else if (shmem_falloc.nr_unswapped > shmem_falloc.nr_falloced)
error = -ENOMEM;
else
error = shmem_getpage(inode, index, &page, SGP_FALLOC,
NULL);
if (error) {
/* Remove the !PageUptodate pages we added */
shmem_undo_range(inode,
(loff_t)start << PAGE_CACHE_SHIFT,
(loff_t)index << PAGE_CACHE_SHIFT, true);
goto undone;
}
/*
* Inform shmem_writepage() how far we have reached.
* No need for lock or barrier: we have the page lock.
*/
shmem_falloc.next++;
if (!PageUptodate(page))
shmem_falloc.nr_falloced++;
/*
* If !PageUptodate, leave it that way so that freeable pages
* can be recognized if we need to rollback on error later.
* But set_page_dirty so that memory pressure will swap rather
* than free the pages we are allocating (and SGP_CACHE pages
* might still be clean: we now need to mark those dirty too).
*/
set_page_dirty(page);
unlock_page(page);
page_cache_release(page);
cond_resched();
}
if (!(mode & FALLOC_FL_KEEP_SIZE) && offset + len > inode->i_size)
i_size_write(inode, offset + len);
inode->i_ctime = CURRENT_TIME;
undone:
spin_lock(&inode->i_lock);
inode->i_private = NULL;
spin_unlock(&inode->i_lock);
out:
mutex_unlock(&inode->i_mutex);
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 = simple_acl_create(dir, inode);
if (error)
goto out_iput;
error = security_inode_init_security(inode, dir,
&dentry->d_name,
shmem_initxattrs, NULL);
if (error && error != -EOPNOTSUPP)
goto out_iput;
error = 0;
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;
out_iput:
iput(inode);
return error;
}
static int
shmem_tmpfile(struct inode *dir, struct dentry *dentry, umode_t mode)
{
struct inode *inode;
int error = -ENOSPC;
inode = shmem_get_inode(dir->i_sb, dir, mode, 0, VM_NORESERVE);
if (inode) {
error = security_inode_init_security(inode, dir,
NULL,
shmem_initxattrs, NULL);
if (error && error != -EOPNOTSUPP)
goto out_iput;
error = simple_acl_create(dir, inode);
if (error)
goto out_iput;
d_tmpfile(dentry, inode);
}
return error;
out_iput:
iput(inode);
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,
bool excl)
{
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 = d_inode(old_dentry);
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 = d_inode(dentry);
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(d_inode(dentry));
drop_nlink(dir);
return shmem_unlink(dir, dentry);
}
static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
{
bool old_is_dir = d_is_dir(old_dentry);
bool new_is_dir = d_is_dir(new_dentry);
if (old_dir != new_dir && old_is_dir != new_is_dir) {
if (old_is_dir) {
drop_nlink(old_dir);
inc_nlink(new_dir);
} else {
drop_nlink(new_dir);
inc_nlink(old_dir);
}
}
old_dir->i_ctime = old_dir->i_mtime =
new_dir->i_ctime = new_dir->i_mtime =
d_inode(old_dentry)->i_ctime =
d_inode(new_dentry)->i_ctime = CURRENT_TIME;
return 0;
}
static int shmem_whiteout(struct inode *old_dir, struct dentry *old_dentry)
{
struct dentry *whiteout;
int error;
whiteout = d_alloc(old_dentry->d_parent, &old_dentry->d_name);
if (!whiteout)
return -ENOMEM;
error = shmem_mknod(old_dir, whiteout,
S_IFCHR | WHITEOUT_MODE, WHITEOUT_DEV);
dput(whiteout);
if (error)
return error;
/*
* Cheat and hash the whiteout while the old dentry is still in
* place, instead of playing games with FS_RENAME_DOES_D_MOVE.
*
* d_lookup() will consistently find one of them at this point,
* not sure which one, but that isn't even important.
*/
d_rehash(whiteout);
return 0;
}
/*
* 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_rename2(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry, unsigned int flags)
{
struct inode *inode = d_inode(old_dentry);
int they_are_dirs = S_ISDIR(inode->i_mode);
if (flags & ~(RENAME_NOREPLACE | RENAME_EXCHANGE | RENAME_WHITEOUT))
return -EINVAL;
if (flags & RENAME_EXCHANGE)
return shmem_exchange(old_dir, old_dentry, new_dir, new_dentry);
if (!simple_empty(new_dentry))
return -ENOTEMPTY;
if (flags & RENAME_WHITEOUT) {
int error;
error = shmem_whiteout(old_dir, old_dentry);
if (error)
return error;
}
if (d_really_is_positive(new_dentry)) {
(void) shmem_unlink(new_dir, new_dentry);
if (they_are_dirs) {
drop_nlink(d_inode(new_dentry));
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,
shmem_initxattrs, 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;
inode->i_link = info->symlink;
} 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);
memcpy(kaddr, symname, len);
kunmap_atomic(kaddr);
SetPageUptodate(page);
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 const char *shmem_follow_link(struct dentry *dentry, void **cookie)
{
struct page *page = NULL;
int error = shmem_getpage(d_inode(dentry), 0, &page, SGP_READ, NULL);
if (error)
return ERR_PTR(error);
unlock_page(page);
*cookie = page;
return kmap(page);
}
static void shmem_put_link(struct inode *unused, void *cookie)
{
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.
*/
/*
* Callback for security_inode_init_security() for acquiring xattrs.
*/
static int shmem_initxattrs(struct inode *inode,
const struct xattr *xattr_array,
void *fs_info)
{
struct shmem_inode_info *info = SHMEM_I(inode);
const struct xattr *xattr;
struct simple_xattr *new_xattr;
size_t len;
for (xattr = xattr_array; xattr->name != NULL; xattr++) {
new_xattr = simple_xattr_alloc(xattr->value, xattr->value_len);
if (!new_xattr)
return -ENOMEM;
len = strlen(xattr->name) + 1;
new_xattr->name = kmalloc(XATTR_SECURITY_PREFIX_LEN + len,
GFP_KERNEL);
if (!new_xattr->name) {
kfree(new_xattr);
return -ENOMEM;
}
memcpy(new_xattr->name, XATTR_SECURITY_PREFIX,
XATTR_SECURITY_PREFIX_LEN);
memcpy(new_xattr->name + XATTR_SECURITY_PREFIX_LEN,
xattr->name, len);
simple_xattr_list_add(&info->xattrs, new_xattr);
}
return 0;
}
static const struct xattr_handler *shmem_xattr_handlers[] = {
#ifdef CONFIG_TMPFS_POSIX_ACL
&posix_acl_access_xattr_handler,
&posix_acl_default_xattr_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)
{
struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
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 simple_xattr_get(&info->xattrs, name, buffer, size);
}
static int shmem_setxattr(struct dentry *dentry, const char *name,
const void *value, size_t size, int flags)
{
struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
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;
return simple_xattr_set(&info->xattrs, name, value, size, flags);
}
static int shmem_removexattr(struct dentry *dentry, const char *name)
{
struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
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 simple_xattr_remove(&info->xattrs, name);
}
static ssize_t shmem_listxattr(struct dentry *dentry, char *buffer, size_t size)
{
struct shmem_inode_info *info = SHMEM_I(d_inode(dentry));
return simple_xattr_list(&info->xattrs, buffer, size);
}
#endif /* CONFIG_TMPFS_XATTR */
static const struct inode_operations shmem_short_symlink_operations = {
.readlink = generic_readlink,
.follow_link = simple_follow_link,
#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;
if (fh_len < 3)
return NULL;
inum = fid->raw[2];
inum = (inum << 32) | fid->raw[1];
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 inode *inode, __u32 *fh, int *len,
struct inode *parent)
{
if (*len < 3) {
*len = 3;
return FILEID_INVALID;
}
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;
struct mempolicy *mpol = NULL;
uid_t uid;
gid_t gid;
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);
goto error;
}
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;
uid = simple_strtoul(value, &rest, 0);
if (*rest)
goto bad_val;
sbinfo->uid = make_kuid(current_user_ns(), uid);
if (!uid_valid(sbinfo->uid))
goto bad_val;
} else if (!strcmp(this_char,"gid")) {
if (remount)
continue;
gid = simple_strtoul(value, &rest, 0);
if (*rest)
goto bad_val;
sbinfo->gid = make_kgid(current_user_ns(), gid);
if (!gid_valid(sbinfo->gid))
goto bad_val;
} else if (!strcmp(this_char,"mpol")) {
mpol_put(mpol);
mpol = NULL;
if (mpol_parse_str(value, &mpol))
goto bad_val;
} else {
printk(KERN_ERR "tmpfs: Bad mount option %s\n",
this_char);
goto error;
}
}
sbinfo->mpol = mpol;
return 0;
bad_val:
printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n",
value, this_char);
error:
mpol_put(mpol);
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;
config.mpol = NULL;
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;
/*
* Preserve previous mempolicy unless mpol remount option was specified.
*/
if (config.mpol) {
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 (!uid_eq(sbinfo->uid, GLOBAL_ROOT_UID))
seq_printf(seq, ",uid=%u",
from_kuid_munged(&init_user_ns, sbinfo->uid));
if (!gid_eq(sbinfo->gid, GLOBAL_ROOT_GID))
seq_printf(seq, ",gid=%u",
from_kgid_munged(&init_user_ns, sbinfo->gid));
shmem_show_mpol(seq, sbinfo->mpol);
return 0;
}
#define MFD_NAME_PREFIX "memfd:"
#define MFD_NAME_PREFIX_LEN (sizeof(MFD_NAME_PREFIX) - 1)
#define MFD_NAME_MAX_LEN (NAME_MAX - MFD_NAME_PREFIX_LEN)
#define MFD_ALL_FLAGS (MFD_CLOEXEC | MFD_ALLOW_SEALING)
SYSCALL_DEFINE2(memfd_create,
const char __user *, uname,
unsigned int, flags)
{
struct shmem_inode_info *info;
struct file *file;
int fd, error;
char *name;
long len;
if (flags & ~(unsigned int)MFD_ALL_FLAGS)
return -EINVAL;
/* length includes terminating zero */
len = strnlen_user(uname, MFD_NAME_MAX_LEN + 1);
if (len <= 0)
return -EFAULT;
if (len > MFD_NAME_MAX_LEN + 1)
return -EINVAL;
name = kmalloc(len + MFD_NAME_PREFIX_LEN, GFP_TEMPORARY);
if (!name)
return -ENOMEM;
strcpy(name, MFD_NAME_PREFIX);
if (copy_from_user(&name[MFD_NAME_PREFIX_LEN], uname, len)) {
error = -EFAULT;
goto err_name;
}
/* terminating-zero may have changed after strnlen_user() returned */
if (name[len + MFD_NAME_PREFIX_LEN - 1]) {
error = -EFAULT;
goto err_name;
}
fd = get_unused_fd_flags((flags & MFD_CLOEXEC) ? O_CLOEXEC : 0);
if (fd < 0) {
error = fd;
goto err_name;
}
file = shmem_file_setup(name, 0, VM_NORESERVE);
if (IS_ERR(file)) {
error = PTR_ERR(file);
goto err_fd;
}
info = SHMEM_I(file_inode(file));
file->f_mode |= FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE;
file->f_flags |= O_RDWR | O_LARGEFILE;
if (flags & MFD_ALLOW_SEALING)
info->seals &= ~F_SEAL_SEAL;
fd_install(fd, file);
kfree(name);
return fd;
err_fd:
put_unused_fd(fd);
err_name:
kfree(name);
return error;
}
#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);
mpol_put(sbinfo->mpol);
kfree(sbinfo);
sb->s_fs_info = NULL;
}
int shmem_fill_super(struct super_block *sb, void *data, int silent)
{
struct inode *inode;
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_KERNMOUNT)) {
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;
}
} else {
sb->s_flags |= MS_NOUSER;
}
sb->s_export_op = &shmem_export_ops;
sb->s_flags |= MS_NOSEC;
#else
sb->s_flags |= MS_NOUSER;
#endif
spin_lock_init(&sbinfo->stat_lock);
if (percpu_counter_init(&sbinfo->used_blocks, 0, GFP_KERNEL))
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;
sb->s_root = d_make_root(inode);
if (!sb->s_root)
goto failed;
return 0;
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
#ifdef CONFIG_MIGRATION
.migratepage = migrate_page,
#endif
.error_remove_page = generic_error_remove_page,
};
static const struct file_operations shmem_file_operations = {
.mmap = shmem_mmap,
#ifdef CONFIG_TMPFS
.llseek = shmem_file_llseek,
.read_iter = shmem_file_read_iter,
.write_iter = generic_file_write_iter,
.fsync = noop_fsync,
.splice_read = shmem_file_splice_read,
.splice_write = iter_file_splice_write,
.fallocate = shmem_fallocate,
#endif
};
static const struct inode_operations shmem_inode_operations = {
.setattr = shmem_setattr,
#ifdef CONFIG_TMPFS_XATTR
.setxattr = shmem_setxattr,
.getxattr = shmem_getxattr,
.listxattr = shmem_listxattr,
.removexattr = shmem_removexattr,
.set_acl = simple_set_acl,
#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,
.rename2 = shmem_rename2,
.tmpfile = shmem_tmpfile,
#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,
.set_acl = simple_set_acl,
#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,
.set_acl = simple_set_acl,
#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,
.map_pages = filemap_map_pages,
#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,
.fs_flags = FS_USERNS_MOUNT,
};
int __init shmem_init(void)
{
int error;
/* If rootfs called this, don't re-init */
if (shmem_inode_cachep)
return 0;
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 = kern_mount(&shmem_fs_type);
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:
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.
*/
static struct file_system_type shmem_fs_type = {
.name = "tmpfs",
.mount = ramfs_mount,
.kill_sb = kill_litter_super,
.fs_flags = FS_USERNS_MOUNT,
};
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_unlock_mapping(struct address_space *mapping)
{
}
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 */
static struct dentry_operations anon_ops = {
.d_dname = simple_dname
};
static struct file *__shmem_file_setup(const char *name, loff_t size,
unsigned long flags, unsigned int i_flags)
{
struct file *res;
struct inode *inode;
struct path path;
struct super_block *sb;
struct qstr this;
if (IS_ERR(shm_mnt))
return ERR_CAST(shm_mnt);
if (size < 0 || size > MAX_LFS_FILESIZE)
return ERR_PTR(-EINVAL);
if (shmem_acct_size(flags, size))
return ERR_PTR(-ENOMEM);
res = ERR_PTR(-ENOMEM);
this.name = name;
this.len = strlen(name);
this.hash = 0; /* will go */
sb = shm_mnt->mnt_sb;
path.mnt = mntget(shm_mnt);
path.dentry = d_alloc_pseudo(sb, &this);
if (!path.dentry)
goto put_memory;
d_set_d_op(path.dentry, &anon_ops);
res = ERR_PTR(-ENOSPC);
inode = shmem_get_inode(sb, NULL, S_IFREG | S_IRWXUGO, 0, flags);
if (!inode)
goto put_memory;
inode->i_flags |= i_flags;
d_instantiate(path.dentry, inode);
inode->i_size = size;
clear_nlink(inode); /* It is unlinked */
res = ERR_PTR(ramfs_nommu_expand_for_mapping(inode, size));
if (IS_ERR(res))
goto put_path;
res = alloc_file(&path, FMODE_WRITE | FMODE_READ,
&shmem_file_operations);
if (IS_ERR(res))
goto put_path;
return res;
put_memory:
shmem_unacct_size(flags, size);
put_path:
path_put(&path);
return res;
}
/**
* shmem_kernel_file_setup - get an unlinked file living in tmpfs which must be
* kernel internal. There will be NO LSM permission checks against the
* underlying inode. So users of this interface must do LSM checks at a
* higher layer. The one user is the big_key implementation. LSM checks
* are provided at the key level rather than the inode level.
* @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_kernel_file_setup(const char *name, loff_t size, unsigned long flags)
{
return __shmem_file_setup(name, size, flags, S_PRIVATE);
}
/**
* 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)
{
return __shmem_file_setup(name, size, flags, 0);
}
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;
/*
* Cloning a new file under mmap_sem leads to a lock ordering conflict
* between XFS directory reading and selinux: since this file is only
* accessible to the user through its mapping, use S_PRIVATE flag to
* bypass file security, in the same way as shmem_kernel_file_setup().
*/
file = __shmem_file_setup("dev/zero", size, vma->vm_flags, S_PRIVATE);
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;
}
/**
* 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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