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       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                 :          3 :         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                 :          1 :         if (!file || !file->f_mapping)
     109                 :            :                 return false;
     110                 :          1 :         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