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        pgoff_t                 fallocend;      /* highest fallocate endindex */
  22        struct list_head        shrinklist;     /* shrinkable hpage inodes */
  23        struct list_head        swaplist;       /* chain of maybes on swap */
  24        struct shared_policy    policy;         /* NUMA memory alloc policy */
  25        struct simple_xattrs    xattrs;         /* list of xattrs */
  26        atomic_t                stop_eviction;  /* hold when working on inode */
  27        struct timespec64       i_crtime;       /* file creation time */
  28        struct inode            vfs_inode;
  29};
  30
  31struct shmem_sb_info {
  32        unsigned long max_blocks;   /* How many blocks are allowed */
  33        struct percpu_counter used_blocks;  /* How many are allocated */
  34        unsigned long max_inodes;   /* How many inodes are allowed */
  35        unsigned long free_inodes;  /* How many are left for allocation */
  36        raw_spinlock_t stat_lock;   /* Serialize shmem_sb_info changes */
  37        umode_t mode;               /* Mount mode for root directory */
  38        unsigned char huge;         /* Whether to try for hugepages */
  39        kuid_t uid;                 /* Mount uid for root directory */
  40        kgid_t gid;                 /* Mount gid for root directory */
  41        bool full_inums;            /* If i_ino should be uint or ino_t */
  42        ino_t next_ino;             /* The next per-sb inode number to use */
  43        ino_t __percpu *ino_batch;  /* The next per-cpu inode number to use */
  44        struct mempolicy *mpol;     /* default memory policy for mappings */
  45        spinlock_t shrinklist_lock;   /* Protects shrinklist */
  46        struct list_head shrinklist;  /* List of shinkable inodes */
  47        unsigned long shrinklist_len; /* Length of shrinklist */
  48};
  49
  50static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
  51{
  52        return container_of(inode, struct shmem_inode_info, vfs_inode);
  53}
  54
  55/*
  56 * Functions in mm/shmem.c called directly from elsewhere:
  57 */
  58extern const struct fs_parameter_spec shmem_fs_parameters[];
  59extern int shmem_init(void);
  60extern int shmem_init_fs_context(struct fs_context *fc);
  61extern struct file *shmem_file_setup(const char *name,
  62                                        loff_t size, unsigned long flags);
  63extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
  64                                            unsigned long flags);
  65extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
  66                const char *name, loff_t size, unsigned long flags);
  67extern int shmem_zero_setup(struct vm_area_struct *);
  68extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
  69                unsigned long len, unsigned long pgoff, unsigned long flags);
  70extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts);
  71#ifdef CONFIG_SHMEM
  72extern const struct address_space_operations shmem_aops;
  73static inline bool shmem_mapping(struct address_space *mapping)
  74{
  75        return mapping->a_ops == &shmem_aops;
  76}
  77#else
  78static inline bool shmem_mapping(struct address_space *mapping)
  79{
  80        return false;
  81}
  82#endif /* CONFIG_SHMEM */
  83extern void shmem_unlock_mapping(struct address_space *mapping);
  84extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
  85                                        pgoff_t index, gfp_t gfp_mask);
  86extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
  87int shmem_unuse(unsigned int type);
  88
  89extern bool shmem_is_huge(struct vm_area_struct *vma,
  90                          struct inode *inode, pgoff_t index);
  91static inline bool shmem_huge_enabled(struct vm_area_struct *vma)
  92{
  93        return shmem_is_huge(vma, file_inode(vma->vm_file), vma->vm_pgoff);
  94}
  95extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
  96extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
  97                                                pgoff_t start, pgoff_t end);
  98
  99/* Flag allocation requirements to shmem_getpage */
 100enum sgp_type {
 101        SGP_READ,       /* don't exceed i_size, don't allocate page */
 102        SGP_NOALLOC,    /* similar, but fail on hole or use fallocated page */
 103        SGP_CACHE,      /* don't exceed i_size, may allocate page */
 104        SGP_WRITE,      /* may exceed i_size, may allocate !Uptodate page */
 105        SGP_FALLOC,     /* like SGP_WRITE, but make existing page Uptodate */
 106};
 107
 108extern int shmem_getpage(struct inode *inode, pgoff_t index,
 109                struct page **pagep, enum sgp_type sgp);
 110
 111static inline struct page *shmem_read_mapping_page(
 112                                struct address_space *mapping, pgoff_t index)
 113{
 114        return shmem_read_mapping_page_gfp(mapping, index,
 115                                        mapping_gfp_mask(mapping));
 116}
 117
 118static inline bool shmem_file(struct file *file)
 119{
 120        if (!IS_ENABLED(CONFIG_SHMEM))
 121                return false;
 122        if (!file || !file->f_mapping)
 123                return false;
 124        return shmem_mapping(file->f_mapping);
 125}
 126
 127/*
 128 * If fallocate(FALLOC_FL_KEEP_SIZE) has been used, there may be pages
 129 * beyond i_size's notion of EOF, which fallocate has committed to reserving:
 130 * which split_huge_page() must therefore not delete.  This use of a single
 131 * "fallocend" per inode errs on the side of not deleting a reservation when
 132 * in doubt: there are plenty of cases when it preserves unreserved pages.
 133 */
 134static inline pgoff_t shmem_fallocend(struct inode *inode, pgoff_t eof)
 135{
 136        return max(eof, SHMEM_I(inode)->fallocend);
 137}
 138
 139extern bool shmem_charge(struct inode *inode, long pages);
 140extern void shmem_uncharge(struct inode *inode, long pages);
 141
 142#ifdef CONFIG_USERFAULTFD
 143#ifdef CONFIG_SHMEM
 144extern int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
 145                                  struct vm_area_struct *dst_vma,
 146                                  unsigned long dst_addr,
 147                                  unsigned long src_addr,
 148                                  bool zeropage,
 149                                  struct page **pagep);
 150#else /* !CONFIG_SHMEM */
 151#define shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \
 152                               src_addr, zeropage, pagep)       ({ BUG(); 0; })
 153#endif /* CONFIG_SHMEM */
 154#endif /* CONFIG_USERFAULTFD */
 155
 156#endif
 157