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#include <linux/fs_parser.h>
  12
  13/* inode in-kernel data */
  14
  15struct shmem_inode_info {
  16        spinlock_t              lock;
  17        unsigned int            seals;          /* shmem seals */
  18        unsigned long           flags;
  19        unsigned long           alloced;        /* data pages alloced to file */
  20        unsigned long           swapped;        /* subtotal assigned to swap */
  21        struct list_head        shrinklist;     /* shrinkable hpage inodes */
  22        struct list_head        swaplist;       /* chain of maybes on swap */
  23        struct shared_policy    policy;         /* NUMA memory alloc policy */
  24        struct simple_xattrs    xattrs;         /* list of xattrs */
  25        atomic_t                stop_eviction;  /* hold when working on inode */
  26        struct inode            vfs_inode;
  27};
  28
  29struct shmem_sb_info {
  30        unsigned long max_blocks;   /* How many blocks are allowed */
  31        struct percpu_counter used_blocks;  /* How many are allocated */
  32        unsigned long max_inodes;   /* How many inodes are allowed */
  33        unsigned long free_inodes;  /* How many are left for allocation */
  34        spinlock_t stat_lock;       /* Serialize shmem_sb_info changes */
  35        umode_t mode;               /* Mount mode for root directory */
  36        unsigned char huge;         /* Whether to try for hugepages */
  37        kuid_t uid;                 /* Mount uid for root directory */
  38        kgid_t gid;                 /* Mount gid for root directory */
  39        bool full_inums;            /* If i_ino should be uint or ino_t */
  40        ino_t next_ino;             /* The next per-sb inode number to use */
  41        ino_t __percpu *ino_batch;  /* The next per-cpu inode number to use */
  42        struct mempolicy *mpol;     /* default memory policy for mappings */
  43        spinlock_t shrinklist_lock;   /* Protects shrinklist */
  44        struct list_head shrinklist;  /* List of shinkable inodes */
  45        unsigned long shrinklist_len; /* Length of shrinklist */
  46};
  47
  48static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
  49{
  50        return container_of(inode, struct shmem_inode_info, vfs_inode);
  51}
  52
  53/*
  54 * Functions in mm/shmem.c called directly from elsewhere:
  55 */
  56extern const struct fs_parameter_spec shmem_fs_parameters[];
  57extern int shmem_init(void);
  58extern int shmem_init_fs_context(struct fs_context *fc);
  59extern struct file *shmem_file_setup(const char *name,
  60                                        loff_t size, unsigned long flags);
  61extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
  62                                            unsigned long flags);
  63extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
  64                const char *name, loff_t size, unsigned long flags);
  65extern int shmem_zero_setup(struct vm_area_struct *);
  66extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
  67                unsigned long len, unsigned long pgoff, unsigned long flags);
  68extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
  69#ifdef CONFIG_SHMEM
  70extern const struct address_space_operations shmem_aops;
  71static inline bool shmem_mapping(struct address_space *mapping)
  72{
  73        return mapping->a_ops == &shmem_aops;
  74}
  75#else
  76static inline bool shmem_mapping(struct address_space *mapping)
  77{
  78        return false;
  79}
  80#endif /* CONFIG_SHMEM */
  81extern void shmem_unlock_mapping(struct address_space *mapping);
  82extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
  83                                        pgoff_t index, gfp_t gfp_mask);
  84extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
  85extern int shmem_unuse(unsigned int type, bool frontswap,
  86                       unsigned long *fs_pages_to_unuse);
  87
  88extern bool shmem_huge_enabled(struct vm_area_struct *vma);
  89extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
  90extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
  91                                                pgoff_t start, pgoff_t end);
  92
  93/* Flag allocation requirements to shmem_getpage */
  94enum sgp_type {
  95        SGP_READ,       /* don't exceed i_size, don't allocate page */
  96        SGP_CACHE,      /* don't exceed i_size, may allocate page */
  97        SGP_NOHUGE,     /* like SGP_CACHE, but no huge pages */
  98        SGP_HUGE,       /* like SGP_CACHE, huge pages preferred */
  99        SGP_WRITE,      /* may exceed i_size, may allocate !Uptodate page */
 100        SGP_FALLOC,     /* like SGP_WRITE, but make existing page Uptodate */
 101};
 102
 103extern int shmem_getpage(struct inode *inode, pgoff_t index,
 104                struct page **pagep, enum sgp_type sgp);
 105
 106static inline struct page *shmem_read_mapping_page(
 107                                struct address_space *mapping, pgoff_t index)
 108{
 109        return shmem_read_mapping_page_gfp(mapping, index,
 110                                        mapping_gfp_mask(mapping));
 111}
 112
 113static inline bool shmem_file(struct file *file)
 114{
 115        if (!IS_ENABLED(CONFIG_SHMEM))
 116                return false;
 117        if (!file || !file->f_mapping)
 118                return false;
 119        return shmem_mapping(file->f_mapping);
 120}
 121
 122extern bool shmem_charge(struct inode *inode, long pages);
 123extern void shmem_uncharge(struct inode *inode, long pages);
 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