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        struct mempolicy *mpol;     /* default memory policy for mappings */
  40        spinlock_t shrinklist_lock;   /* Protects shrinklist */
  41        struct list_head shrinklist;  /* List of shinkable inodes */
  42        unsigned long shrinklist_len; /* Length of shrinklist */
  43};
  44
  45static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
  46{
  47        return container_of(inode, struct shmem_inode_info, vfs_inode);
  48}
  49
  50/*
  51 * Functions in mm/shmem.c called directly from elsewhere:
  52 */
  53extern const struct fs_parameter_spec shmem_fs_parameters[];
  54extern int shmem_init(void);
  55extern int shmem_init_fs_context(struct fs_context *fc);
  56extern struct file *shmem_file_setup(const char *name,
  57                                        loff_t size, unsigned long flags);
  58extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
  59                                            unsigned long flags);
  60extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
  61                const char *name, loff_t size, unsigned long flags);
  62extern int shmem_zero_setup(struct vm_area_struct *);
  63extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
  64                unsigned long len, unsigned long pgoff, unsigned long flags);
  65extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
  66#ifdef CONFIG_SHMEM
  67extern bool shmem_mapping(struct address_space *mapping);
  68#else
  69static inline bool shmem_mapping(struct address_space *mapping)
  70{
  71        return false;
  72}
  73#endif /* CONFIG_SHMEM */
  74extern void shmem_unlock_mapping(struct address_space *mapping);
  75extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
  76                                        pgoff_t index, gfp_t gfp_mask);
  77extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
  78extern int shmem_unuse(unsigned int type, bool frontswap,
  79                       unsigned long *fs_pages_to_unuse);
  80
  81extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
  82extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
  83                                                pgoff_t start, pgoff_t end);
  84
  85/* Flag allocation requirements to shmem_getpage */
  86enum sgp_type {
  87        SGP_READ,       /* don't exceed i_size, don't allocate page */
  88        SGP_CACHE,      /* don't exceed i_size, may allocate page */
  89        SGP_NOHUGE,     /* like SGP_CACHE, but no huge pages */
  90        SGP_HUGE,       /* like SGP_CACHE, huge pages preferred */
  91        SGP_WRITE,      /* may exceed i_size, may allocate !Uptodate page */
  92        SGP_FALLOC,     /* like SGP_WRITE, but make existing page Uptodate */
  93};
  94
  95extern int shmem_getpage(struct inode *inode, pgoff_t index,
  96                struct page **pagep, enum sgp_type sgp);
  97
  98static inline struct page *shmem_read_mapping_page(
  99                                struct address_space *mapping, pgoff_t index)
 100{
 101        return shmem_read_mapping_page_gfp(mapping, index,
 102                                        mapping_gfp_mask(mapping));
 103}
 104
 105static inline bool shmem_file(struct file *file)
 106{
 107        if (!IS_ENABLED(CONFIG_SHMEM))
 108                return false;
 109        if (!file || !file->f_mapping)
 110                return false;
 111        return shmem_mapping(file->f_mapping);
 112}
 113
 114extern bool shmem_charge(struct inode *inode, long pages);
 115extern void shmem_uncharge(struct inode *inode, long pages);
 116
 117#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 118extern bool shmem_huge_enabled(struct vm_area_struct *vma);
 119#else
 120static inline bool shmem_huge_enabled(struct vm_area_struct *vma)
 121{
 122        return false;
 123}
 124#endif
 125
 126#ifdef CONFIG_SHMEM
 127extern int shmem_mcopy_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
 128                                  struct vm_area_struct *dst_vma,
 129                                  unsigned long dst_addr,
 130                                  unsigned long src_addr,
 131                                  struct page **pagep);
 132extern int shmem_mfill_zeropage_pte(struct mm_struct *dst_mm,
 133                                    pmd_t *dst_pmd,
 134                                    struct vm_area_struct *dst_vma,
 135                                    unsigned long dst_addr);
 136#else
 137#define shmem_mcopy_atomic_pte(dst_mm, dst_pte, dst_vma, dst_addr, \
 138                               src_addr, pagep)        ({ BUG(); 0; })
 139#define shmem_mfill_zeropage_pte(dst_mm, dst_pmd, dst_vma, \
 140                                 dst_addr)      ({ BUG(); 0; })
 141#endif
 142
 143#endif
 144