mirror of
https://github.com/torvalds/linux.git
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777eda2c5b
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
3465 lines
90 KiB
C
3465 lines
90 KiB
C
/*
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* Resizable virtual memory filesystem for Linux.
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*
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* Copyright (C) 2000 Linus Torvalds.
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* 2000 Transmeta Corp.
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* 2000-2001 Christoph Rohland
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* 2000-2001 SAP AG
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* 2002 Red Hat Inc.
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* Copyright (C) 2002-2011 Hugh Dickins.
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* Copyright (C) 2011 Google Inc.
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* Copyright (C) 2002-2005 VERITAS Software Corporation.
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* Copyright (C) 2004 Andi Kleen, SuSE Labs
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*
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* Extended attribute support for tmpfs:
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* Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net>
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* Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com>
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*
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* tiny-shmem:
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* Copyright (c) 2004, 2008 Matt Mackall <mpm@selenic.com>
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*
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* This file is released under the GPL.
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*/
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/vfs.h>
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#include <linux/mount.h>
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#include <linux/ramfs.h>
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#include <linux/pagemap.h>
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#include <linux/file.h>
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#include <linux/mm.h>
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#include <linux/export.h>
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#include <linux/swap.h>
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#include <linux/aio.h>
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static struct vfsmount *shm_mnt;
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#ifdef CONFIG_SHMEM
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/*
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* This virtual memory filesystem is heavily based on the ramfs. It
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* extends ramfs by the ability to use swap and honor resource limits
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* which makes it a completely usable filesystem.
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*/
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#include <linux/xattr.h>
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#include <linux/exportfs.h>
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#include <linux/posix_acl.h>
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#include <linux/posix_acl_xattr.h>
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#include <linux/mman.h>
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#include <linux/string.h>
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#include <linux/slab.h>
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#include <linux/backing-dev.h>
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#include <linux/shmem_fs.h>
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#include <linux/writeback.h>
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#include <linux/blkdev.h>
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#include <linux/pagevec.h>
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#include <linux/percpu_counter.h>
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#include <linux/falloc.h>
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#include <linux/splice.h>
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#include <linux/security.h>
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#include <linux/swapops.h>
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#include <linux/mempolicy.h>
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#include <linux/namei.h>
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#include <linux/ctype.h>
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#include <linux/migrate.h>
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#include <linux/highmem.h>
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#include <linux/seq_file.h>
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#include <linux/magic.h>
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#include <linux/syscalls.h>
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#include <linux/fcntl.h>
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#include <uapi/linux/memfd.h>
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#include <asm/uaccess.h>
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#include <asm/pgtable.h>
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#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512)
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#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT)
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/* Pretend that each entry is of this size in directory's i_size */
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#define BOGO_DIRENT_SIZE 20
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/* Symlink up to this size is kmalloc'ed instead of using a swappable page */
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#define SHORT_SYMLINK_LEN 128
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/*
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* shmem_fallocate communicates with shmem_fault or shmem_writepage via
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* inode->i_private (with i_mutex making sure that it has only one user at
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* a time): we would prefer not to enlarge the shmem inode just for that.
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*/
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struct shmem_falloc {
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wait_queue_head_t *waitq; /* faults into hole wait for punch to end */
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pgoff_t start; /* start of range currently being fallocated */
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pgoff_t next; /* the next page offset to be fallocated */
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pgoff_t nr_falloced; /* how many new pages have been fallocated */
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pgoff_t nr_unswapped; /* how often writepage refused to swap out */
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};
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/* Flag allocation requirements to shmem_getpage */
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enum sgp_type {
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SGP_READ, /* don't exceed i_size, don't allocate page */
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SGP_CACHE, /* don't exceed i_size, may allocate page */
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SGP_DIRTY, /* like SGP_CACHE, but set new page dirty */
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SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
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SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
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};
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#ifdef CONFIG_TMPFS
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static unsigned long shmem_default_max_blocks(void)
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{
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return totalram_pages / 2;
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}
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static unsigned long shmem_default_max_inodes(void)
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{
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return min(totalram_pages - totalhigh_pages, totalram_pages / 2);
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}
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#endif
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static bool shmem_should_replace_page(struct page *page, gfp_t gfp);
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static int shmem_replace_page(struct page **pagep, gfp_t gfp,
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struct shmem_inode_info *info, pgoff_t index);
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static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
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struct page **pagep, enum sgp_type sgp, gfp_t gfp, int *fault_type);
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static inline int shmem_getpage(struct inode *inode, pgoff_t index,
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struct page **pagep, enum sgp_type sgp, int *fault_type)
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{
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return shmem_getpage_gfp(inode, index, pagep, sgp,
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mapping_gfp_mask(inode->i_mapping), fault_type);
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}
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static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb)
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{
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return sb->s_fs_info;
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}
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/*
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* shmem_file_setup pre-accounts the whole fixed size of a VM object,
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* for shared memory and for shared anonymous (/dev/zero) mappings
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* (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1),
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* consistent with the pre-accounting of private mappings ...
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*/
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static inline int shmem_acct_size(unsigned long flags, loff_t size)
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{
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return (flags & VM_NORESERVE) ?
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0 : security_vm_enough_memory_mm(current->mm, VM_ACCT(size));
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}
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static inline void shmem_unacct_size(unsigned long flags, loff_t size)
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{
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if (!(flags & VM_NORESERVE))
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vm_unacct_memory(VM_ACCT(size));
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}
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static inline int shmem_reacct_size(unsigned long flags,
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loff_t oldsize, loff_t newsize)
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{
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if (!(flags & VM_NORESERVE)) {
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if (VM_ACCT(newsize) > VM_ACCT(oldsize))
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return security_vm_enough_memory_mm(current->mm,
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VM_ACCT(newsize) - VM_ACCT(oldsize));
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else if (VM_ACCT(newsize) < VM_ACCT(oldsize))
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vm_unacct_memory(VM_ACCT(oldsize) - VM_ACCT(newsize));
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}
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return 0;
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}
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/*
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* ... whereas tmpfs objects are accounted incrementally as
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* pages are allocated, in order to allow huge sparse files.
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* shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM,
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* so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM.
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*/
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static inline int shmem_acct_block(unsigned long flags)
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{
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return (flags & VM_NORESERVE) ?
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security_vm_enough_memory_mm(current->mm, VM_ACCT(PAGE_CACHE_SIZE)) : 0;
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}
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static inline void shmem_unacct_blocks(unsigned long flags, long pages)
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{
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if (flags & VM_NORESERVE)
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vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE));
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}
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static const struct super_operations shmem_ops;
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static const struct address_space_operations shmem_aops;
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static const struct file_operations shmem_file_operations;
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static const struct inode_operations shmem_inode_operations;
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static const struct inode_operations shmem_dir_inode_operations;
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static const struct inode_operations shmem_special_inode_operations;
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static const struct vm_operations_struct shmem_vm_ops;
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static struct backing_dev_info shmem_backing_dev_info __read_mostly = {
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.ra_pages = 0, /* No readahead */
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.capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK | BDI_CAP_SWAP_BACKED,
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};
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static LIST_HEAD(shmem_swaplist);
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static DEFINE_MUTEX(shmem_swaplist_mutex);
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static int shmem_reserve_inode(struct super_block *sb)
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{
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struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
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if (sbinfo->max_inodes) {
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spin_lock(&sbinfo->stat_lock);
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if (!sbinfo->free_inodes) {
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spin_unlock(&sbinfo->stat_lock);
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return -ENOSPC;
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}
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sbinfo->free_inodes--;
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spin_unlock(&sbinfo->stat_lock);
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}
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return 0;
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}
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static void shmem_free_inode(struct super_block *sb)
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{
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struct shmem_sb_info *sbinfo = SHMEM_SB(sb);
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if (sbinfo->max_inodes) {
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spin_lock(&sbinfo->stat_lock);
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sbinfo->free_inodes++;
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spin_unlock(&sbinfo->stat_lock);
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}
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}
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/**
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* shmem_recalc_inode - recalculate the block usage of an inode
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* @inode: inode to recalc
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*
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* We have to calculate the free blocks since the mm can drop
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* undirtied hole pages behind our back.
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*
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* But normally info->alloced == inode->i_mapping->nrpages + info->swapped
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* So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped)
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*
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* It has to be called with the spinlock held.
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*/
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static void shmem_recalc_inode(struct inode *inode)
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{
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struct shmem_inode_info *info = SHMEM_I(inode);
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long freed;
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freed = info->alloced - info->swapped - inode->i_mapping->nrpages;
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if (freed > 0) {
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struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb);
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if (sbinfo->max_blocks)
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percpu_counter_add(&sbinfo->used_blocks, -freed);
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info->alloced -= freed;
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inode->i_blocks -= freed * BLOCKS_PER_PAGE;
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shmem_unacct_blocks(info->flags, freed);
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}
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}
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/*
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* Replace item expected in radix tree by a new item, while holding tree lock.
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*/
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static int shmem_radix_tree_replace(struct address_space *mapping,
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pgoff_t index, void *expected, void *replacement)
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{
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void **pslot;
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void *item;
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VM_BUG_ON(!expected);
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VM_BUG_ON(!replacement);
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pslot = radix_tree_lookup_slot(&mapping->page_tree, index);
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if (!pslot)
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return -ENOENT;
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item = radix_tree_deref_slot_protected(pslot, &mapping->tree_lock);
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if (item != expected)
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return -ENOENT;
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radix_tree_replace_slot(pslot, replacement);
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return 0;
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}
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/*
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* Sometimes, before we decide whether to proceed or to fail, we must check
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* that an entry was not already brought back from swap by a racing thread.
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*
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* Checking page is not enough: by the time a SwapCache page is locked, it
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* might be reused, and again be SwapCache, using the same swap as before.
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*/
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static bool shmem_confirm_swap(struct address_space *mapping,
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pgoff_t index, swp_entry_t swap)
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{
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void *item;
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rcu_read_lock();
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item = radix_tree_lookup(&mapping->page_tree, index);
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rcu_read_unlock();
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return item == swp_to_radix_entry(swap);
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}
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/*
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* Like add_to_page_cache_locked, but error if expected item has gone.
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*/
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static int shmem_add_to_page_cache(struct page *page,
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struct address_space *mapping,
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pgoff_t index, void *expected)
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{
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int error;
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VM_BUG_ON_PAGE(!PageLocked(page), page);
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VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
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page_cache_get(page);
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page->mapping = mapping;
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page->index = index;
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spin_lock_irq(&mapping->tree_lock);
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if (!expected)
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error = radix_tree_insert(&mapping->page_tree, index, page);
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else
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error = shmem_radix_tree_replace(mapping, index, expected,
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page);
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if (!error) {
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mapping->nrpages++;
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__inc_zone_page_state(page, NR_FILE_PAGES);
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__inc_zone_page_state(page, NR_SHMEM);
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spin_unlock_irq(&mapping->tree_lock);
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} else {
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page->mapping = NULL;
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spin_unlock_irq(&mapping->tree_lock);
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page_cache_release(page);
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}
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return error;
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}
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/*
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* Like delete_from_page_cache, but substitutes swap for page.
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*/
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static void shmem_delete_from_page_cache(struct page *page, void *radswap)
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{
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struct address_space *mapping = page->mapping;
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int error;
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spin_lock_irq(&mapping->tree_lock);
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error = shmem_radix_tree_replace(mapping, page->index, page, radswap);
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page->mapping = NULL;
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mapping->nrpages--;
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__dec_zone_page_state(page, NR_FILE_PAGES);
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__dec_zone_page_state(page, NR_SHMEM);
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spin_unlock_irq(&mapping->tree_lock);
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page_cache_release(page);
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BUG_ON(error);
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}
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/*
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* Remove swap entry from radix tree, free the swap and its page cache.
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*/
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static int shmem_free_swap(struct address_space *mapping,
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pgoff_t index, void *radswap)
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{
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void *old;
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spin_lock_irq(&mapping->tree_lock);
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old = radix_tree_delete_item(&mapping->page_tree, index, radswap);
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spin_unlock_irq(&mapping->tree_lock);
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if (old != radswap)
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return -ENOENT;
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free_swap_and_cache(radix_to_swp_entry(radswap));
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return 0;
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}
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/*
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* SysV IPC SHM_UNLOCK restore Unevictable pages to their evictable lists.
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*/
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void shmem_unlock_mapping(struct address_space *mapping)
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{
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struct pagevec pvec;
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pgoff_t indices[PAGEVEC_SIZE];
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pgoff_t index = 0;
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pagevec_init(&pvec, 0);
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/*
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* Minor point, but we might as well stop if someone else SHM_LOCKs it.
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*/
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while (!mapping_unevictable(mapping)) {
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/*
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* Avoid pagevec_lookup(): find_get_pages() returns 0 as if it
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* has finished, if it hits a row of PAGEVEC_SIZE swap entries.
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*/
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pvec.nr = find_get_entries(mapping, index,
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PAGEVEC_SIZE, pvec.pages, indices);
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if (!pvec.nr)
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break;
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index = indices[pvec.nr - 1] + 1;
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pagevec_remove_exceptionals(&pvec);
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check_move_unevictable_pages(pvec.pages, pvec.nr);
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pagevec_release(&pvec);
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cond_resched();
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}
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}
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/*
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* Remove range of pages and swap entries from radix tree, and free them.
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* If !unfalloc, truncate or punch hole; if unfalloc, undo failed fallocate.
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*/
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static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
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bool unfalloc)
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{
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struct address_space *mapping = inode->i_mapping;
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struct shmem_inode_info *info = SHMEM_I(inode);
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pgoff_t start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
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pgoff_t end = (lend + 1) >> PAGE_CACHE_SHIFT;
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unsigned int partial_start = lstart & (PAGE_CACHE_SIZE - 1);
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unsigned int partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1);
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struct pagevec pvec;
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pgoff_t indices[PAGEVEC_SIZE];
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long nr_swaps_freed = 0;
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pgoff_t index;
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int i;
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if (lend == -1)
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end = -1; /* unsigned, so actually very big */
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pagevec_init(&pvec, 0);
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index = start;
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while (index < end) {
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pvec.nr = find_get_entries(mapping, index,
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min(end - index, (pgoff_t)PAGEVEC_SIZE),
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pvec.pages, indices);
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if (!pvec.nr)
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break;
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for (i = 0; i < pagevec_count(&pvec); i++) {
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struct page *page = pvec.pages[i];
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index = indices[i];
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if (index >= end)
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break;
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if (radix_tree_exceptional_entry(page)) {
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if (unfalloc)
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continue;
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nr_swaps_freed += !shmem_free_swap(mapping,
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index, page);
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continue;
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}
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if (!trylock_page(page))
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continue;
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if (!unfalloc || !PageUptodate(page)) {
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if (page->mapping == mapping) {
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VM_BUG_ON_PAGE(PageWriteback(page), page);
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truncate_inode_page(mapping, page);
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}
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}
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unlock_page(page);
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}
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pagevec_remove_exceptionals(&pvec);
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pagevec_release(&pvec);
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cond_resched();
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index++;
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}
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if (partial_start) {
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struct page *page = NULL;
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shmem_getpage(inode, start - 1, &page, SGP_READ, NULL);
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if (page) {
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unsigned int top = PAGE_CACHE_SIZE;
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if (start > end) {
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top = partial_end;
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partial_end = 0;
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}
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zero_user_segment(page, partial_start, top);
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set_page_dirty(page);
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unlock_page(page);
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page_cache_release(page);
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}
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}
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if (partial_end) {
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struct page *page = NULL;
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shmem_getpage(inode, end, &page, SGP_READ, NULL);
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if (page) {
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zero_user_segment(page, 0, partial_end);
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set_page_dirty(page);
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unlock_page(page);
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page_cache_release(page);
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}
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}
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if (start >= end)
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return;
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|
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 = dentry->d_inode;
|
|
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;
|
|
|
|
/*
|
|
* 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;
|
|
}
|
|
|
|
/*
|
|
* 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, false);
|
|
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 (including mem_cgroup_uncharge_swapcache).
|
|
* 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_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->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)
|
|
{
|
|
return mapping->backing_dev_info == &shmem_backing_dev_info;
|
|
}
|
|
|
|
#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 = 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);
|
|
}
|
|
|
|
static int shmem_exchange(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry)
|
|
{
|
|
bool old_is_dir = S_ISDIR(old_dentry->d_inode->i_mode);
|
|
bool new_is_dir = S_ISDIR(new_dentry->d_inode->i_mode);
|
|
|
|
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 =
|
|
old_dentry->d_inode->i_ctime =
|
|
new_dentry->d_inode->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 = old_dentry->d_inode;
|
|
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 (new_dentry->d_inode) {
|
|
(void) shmem_unlink(new_dir, new_dentry);
|
|
if (they_are_dirs) {
|
|
drop_nlink(new_dentry->d_inode);
|
|
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;
|
|
} 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 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.
|
|
*/
|
|
|
|
/*
|
|
* 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(dentry->d_inode);
|
|
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(dentry->d_inode);
|
|
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(dentry->d_inode);
|
|
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(dentry->d_inode);
|
|
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 = 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;
|
|
|
|
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 = new_sync_read,
|
|
.write = new_sync_write,
|
|
.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
|
|
.remap_pages = generic_file_remap_pages,
|
|
};
|
|
|
|
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 = 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 = 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:
|
|
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.
|
|
*/
|
|
|
|
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;
|
|
|
|
file = shmem_file_setup("dev/zero", size, vma->vm_flags);
|
|
if (IS_ERR(file))
|
|
return PTR_ERR(file);
|
|
|
|
if (vma->vm_file)
|
|
fput(vma->vm_file);
|
|
vma->vm_file = file;
|
|
vma->vm_ops = &shmem_vm_ops;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* 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);
|