root/include/linux/shmem_fs.h

INCLUDED FROM

DEFINITIONS

1. SHMEM_I
2. shmem_mapping
3. shmem_read_mapping_page
4. shmem_file
5. shmem_huge_enabled

   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 
  14 struct 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 
  28 struct 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 
  44 static 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  */
  52 extern const struct fs_parameter_description shmem_fs_parameters;
  53 extern int shmem_init(void);
  54 extern int shmem_init_fs_context(struct fs_context *fc);
  55 extern struct file *shmem_file_setup(const char *name,
  56                                         loff_t size, unsigned long flags);
  57 extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
  58                                             unsigned long flags);
  59 extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
  60                 const char *name, loff_t size, unsigned long flags);
  61 extern int shmem_zero_setup(struct vm_area_struct *);
  62 extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
  63                 unsigned long len, unsigned long pgoff, unsigned long flags);
  64 extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
  65 #ifdef CONFIG_SHMEM
  66 extern bool shmem_mapping(struct address_space *mapping);
  67 #else
  68 static inline bool shmem_mapping(struct address_space *mapping)
  69 {
  70         return false;
  71 }
  72 #endif /* CONFIG_SHMEM */
  73 extern void shmem_unlock_mapping(struct address_space *mapping);
  74 extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
  75                                         pgoff_t index, gfp_t gfp_mask);
  76 extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
  77 extern int shmem_unuse(unsigned int type, bool frontswap,
  78                        unsigned long *fs_pages_to_unuse);
  79 
  80 extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
  81 extern 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 */
  85 enum 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 
  94 extern int shmem_getpage(struct inode *inode, pgoff_t index,
  95                 struct page **pagep, enum sgp_type sgp);
  96 
  97 static 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 
 104 static 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 
 113 extern bool shmem_charge(struct inode *inode, long pages);
 114 extern void shmem_uncharge(struct inode *inode, long pages);
 115 
 116 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
 117 extern bool shmem_huge_enabled(struct vm_area_struct *vma);
 118 #else
 119 static inline bool shmem_huge_enabled(struct vm_area_struct *vma)
 120 {
 121         return false;
 122 }
 123 #endif
 124 
 125 #ifdef CONFIG_SHMEM
 126 extern 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);
 131 extern 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