LXR linux/include/linux/shmem

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef __SHMEM_FS_H
   3#define __SHMEM_FS_H
   4
   5#include <linux/file.h>
   6#include <linux/swap.h>
   7#include <linux/mempolicy.h>
   8#include <linux/pagemap.h>
   9#include <linux/percpu_counter.h>
  10#include <linux/xattr.h>
  11
  12/* inode in-kernel data */
  13
  14struct shmem_inode_info {
  15        spinlock_t              lock;
  16        unsigned int            seals;          /* shmem seals */
  17        unsigned long           flags;
  18        unsigned long           alloced;        /* data pages alloced to file */
  19        unsigned long           swapped;        /* subtotal assigned to swap */
  20        struct list_head        shrinklist;     /* shrinkable hpage inodes */
  21        struct list_head        swaplist;       /* chain of maybes on swap */
  22        struct shared_policy    policy;         /* NUMA memory alloc policy */
  23        struct simple_xattrs    xattrs;         /* list of xattrs */
  24        atomic_t                stop_eviction;  /* hold when working on inode */
  25        struct inode            vfs_inode;
  26};
  27
  28struct shmem_sb_info {
  29        unsigned long max_blocks;   /* How many blocks are allowed */
  30        struct percpu_counter used_blocks;  /* How many are allocated */
  31        unsigned long max_inodes;   /* How many inodes are allowed */
  32        unsigned long free_inodes;  /* How many are left for allocation */
  33        spinlock_t stat_lock;       /* Serialize shmem_sb_info changes */
  34        umode_t mode;               /* Mount mode for root directory */
  35        unsigned char huge;         /* Whether to try for hugepages */
  36        kuid_t uid;                 /* Mount uid for root directory */
  37        kgid_t gid;                 /* Mount gid for root directory */
  38        struct mempolicy *mpol;     /* default memory policy for mappings */
  39        spinlock_t shrinklist_lock;   /* Protects shrinklist */
  40        struct list_head shrinklist;  /* List of shinkable inodes */
  41        unsigned long shrinklist_len; /* Length of shrinklist */
  42};
  43
  44static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
  45{
  46        return container_of(inode, struct shmem_inode_info, vfs_inode);
  47}
  48
  49/*
  50 * Functions in mm/shmem.c called directly from elsewhere:
  51 */
  52extern const struct fs_parameter_description shmem_fs_parameters;
  53extern int shmem_init(void);
  54extern int shmem_init_fs_context(struct fs_context *fc);
  55extern struct file *shmem_file_setup(const char *name,
  56                                        loff_t size, unsigned long flags);
  57extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
  58                                            unsigned long flags);
  59extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
  60                const char *name, loff_t size, unsigned long flags);
  61extern int shmem_zero_setup(struct vm_area_struct *);
  62extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
  63                unsigned long len, unsigned long pgoff, unsigned long flags);
  64extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
  65#ifdef CONFIG_SHMEM
  66extern bool shmem_mapping(struct address_space *mapping);
  67#else
  68static inline bool shmem_mapping(struct address_space *mapping)
  69{
  70        return false;
  71}
  72#endif /* CONFIG_SHMEM */
  73extern void shmem_unlock_mapping(struct address_space *mapping);
  74extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
  75                                        pgoff_t index, gfp_t gfp_mask);
  76extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
  77extern int shmem_unuse(unsigned int type, bool frontswap,
  78                       unsigned long *fs_pages_to_unuse);
  79
  80extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
  81extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
  82                                                pgoff_t start, pgoff_t end);
  83
  84/* Flag allocation requirements to shmem_getpage */
  85enum sgp_type {
  86        SGP_READ,       /* don't exceed i_size, don't allocate page */
  87        SGP_CACHE,      /* don't exceed i_size, may allocate page */
  88        SGP_NOHUGE,     /* like SGP_CACHE, but no huge pages */
  89        SGP_HUGE,       /* like SGP_CACHE, huge pages preferred */
  90        SGP_WRITE,      /* may exceed i_size, may allocate !Uptodate page */
  91        SGP_FALLOC,     /* like SGP_WRITE, but make existing page Uptodate */
  92};
  93
  94extern int shmem_getpage(struct inode *inode, pgoff_t index,
  95                struct page **pagep, enum sgp_type sgp);
  96
  97static inline struct page *shmem_read_mapping_page(
  98                                struct address_space *mapping, pgoff_t index)
  99{
 100        return shmem_read_mapping_page_gfp(mapping, index,
 101                                        mapping_gfp_mask(mapping));
 102}
 103
 104static inline bool shmem_file(struct file *file)
 105{
 106        if (!IS_ENABLED(CONFIG_SHMEM))
 107                return false;
 108        if (!file || !file->f_mapping)
 109                return false;
 110        return shmem_mapping(file->f_mapping);
 111}
 112
 113extern bool shmem_charge(struct inode *inode, long pages);
 114extern void shmem_uncharge(struct inode *inode, long pages);
 115
 116#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 117extern bool shmem_huge_enabled(struct vm_area_struct *vma);
 118#else
 119static inline bool shmem_huge_enabled(struct vm_area_struct *vma)
 120{
 121        return false;
 122}
 123#endif
 124
 125#ifdef CONFIG_SHMEM
 126extern int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
 127                                  struct vm_area_struct *dst_vma,
 128                                  unsigned long dst_addr,
 129                                  unsigned long src_addr,
 130                                  struct page **pagep);
 131extern int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
 132                                    pmd_t *dst_pmd,
 133                                    struct vm_area_struct *dst_vma,
 134                                    unsigned long dst_addr);
 135#else
 136#define shmem_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
 137                               src_addr, pagep)        ({ BUG(); 0; })
 138#define shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, \
 139                                 dst_addr)      ({ BUG(); 0; })
 140#endif
 141
 142#endif
 143