include/linux/shmem_fs.h

   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
  15 struct 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
  29 struct 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
  48 static 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  */
  56 extern const struct fs_parameter_spec shmem_fs_parameters[];
  57 extern int shmem_init(void);
  58 extern int shmem_init_fs_context(struct fs_context *fc);
  59 extern struct file *shmem_file_setup(const char *name,
  60                                         loff_t size, unsigned long flags);
  61 extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
  62                                             unsigned long flags);
  63 extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
  64                 const char *name, loff_t size, unsigned long flags);
  65 extern int shmem_zero_setup(struct vm_area_struct *);
  66 extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
  67                 unsigned long len, unsigned long pgoff, unsigned long flags);
  68 extern int shmem_lock(struct file *file, int lock, struct user_struct *user);
  69 #ifdef CONFIG_SHMEM
  70 extern const struct address_space_operations shmem_aops;
  71 static inline bool shmem_mapping(struct address_space *mapping)
  72 {
  73         return mapping->a_ops == &shmem_aops;
  74 }
  75 #else
  76 static inline bool shmem_mapping(struct address_space *mapping)
  77 {
  78         return false;
  79 }
  80 #endif /* CONFIG_SHMEM */
  81 extern void shmem_unlock_mapping(struct address_space *mapping);
  82 extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
  83                                         pgoff_t index, gfp_t gfp_mask);
  84 extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
  85 extern int shmem_unuse(unsigned int type, bool frontswap,
  86                        unsigned long *fs_pages_to_unuse);
  87
  88 extern bool shmem_huge_enabled(struct vm_area_struct *vma);
  89 extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
  90 extern 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 */
  94 enum 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
 103 extern int shmem_getpage(struct inode *inode, pgoff_t index,
 104                 struct page **pagep, enum sgp_type sgp);
 105
 106 static 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
 113 static 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
 122 extern bool shmem_charge(struct inode *inode, long pages);
 123 extern void shmem_uncharge(struct inode *inode, long pages);
 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