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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __SHMEM_FS_H
#define __SHMEM_FS_H
#include <linux/file.h>
#include <linux/swap.h>
#include <linux/mempolicy.h>
#include <linux/pagemap.h>
#include <linux/percpu_counter.h>
#include <linux/xattr.h>
#include <linux/fs_parser.h>
/* inode in-kernel data */
struct shmem_inode_info {
spinlock_t lock;
unsigned int seals; /* shmem seals */
unsigned long flags;
unsigned long alloced; /* data pages alloced to file */
unsigned long swapped; /* subtotal assigned to swap */
pgoff_t fallocend; /* highest fallocate endindex */
struct list_head shrinklist; /* shrinkable hpage inodes */
struct list_head swaplist; /* chain of maybes on swap */
struct shared_policy policy; /* NUMA memory alloc policy */
struct simple_xattrs xattrs; /* list of xattrs */
atomic_t stop_eviction; /* hold when working on inode */
struct inode vfs_inode;
struct shmem_sb_info {
unsigned long max_blocks; /* How many blocks are allowed */
struct percpu_counter used_blocks; /* How many are allocated */
unsigned long max_inodes; /* How many inodes are allowed */
unsigned long free_inodes; /* How many are left for allocation */
raw_spinlock_t stat_lock; /* Serialize shmem_sb_info changes */
umode_t mode; /* Mount mode for root directory */
unsigned char huge; /* Whether to try for hugepages */
kuid_t uid; /* Mount uid for root directory */
kgid_t gid; /* Mount gid for root directory */
bool full_inums; /* If i_ino should be uint or ino_t */
ino_t next_ino; /* The next per-sb inode number to use */
ino_t __percpu *ino_batch; /* The next per-cpu inode number to use */
struct mempolicy *mpol; /* default memory policy for mappings */
spinlock_t shrinklist_lock; /* Protects shrinklist */
struct list_head shrinklist; /* List of shinkable inodes */
unsigned long shrinklist_len; /* Length of shrinklist */
static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
return container_of(inode, struct shmem_inode_info, vfs_inode);
* Functions in mm/shmem.c called directly from elsewhere:
extern const struct fs_parameter_spec shmem_fs_parameters[];
extern int shmem_init(void);
extern int shmem_init_fs_context(struct fs_context *fc);
extern struct file *shmem_file_setup(const char *name,
loff_t size, unsigned long flags);
extern struct file *shmem_kernel_file_setup(const char *name, loff_t size,
unsigned long flags);
extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
const char *name, loff_t size, unsigned long flags);
extern int shmem_zero_setup(struct vm_area_struct *);
extern unsigned long shmem_get_unmapped_area(struct file *, unsigned long addr,
unsigned long len, unsigned long pgoff, unsigned long flags);
extern int shmem_lock(struct file *file, int lock, struct ucounts *ucounts);
extern const struct address_space_operations shmem_aops;
static inline bool shmem_mapping(struct address_space *mapping)
return mapping->a_ops == &shmem_aops;
static inline bool shmem_mapping(struct address_space *mapping)
return false;
#endif /* CONFIG_SHMEM */
extern void shmem_unlock_mapping(struct address_space *mapping);
extern struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
pgoff_t index, gfp_t gfp_mask);
extern void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end);
extern int shmem_unuse(unsigned int type, bool frontswap,
unsigned long *fs_pages_to_unuse);
extern bool shmem_is_huge(struct vm_area_struct *vma,
struct inode *inode, pgoff_t index);
static inline bool shmem_huge_enabled(struct vm_area_struct *vma)
return shmem_is_huge(vma, file_inode(vma->vm_file), vma->vm_pgoff);
extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
pgoff_t start, pgoff_t end);
/* Flag allocation requirements to shmem_getpage */
enum sgp_type {
SGP_READ, /* don't exceed i_size, don't allocate page */
SGP_NOALLOC, /* similar, but fail on hole or use fallocated page */
SGP_CACHE, /* don't exceed i_size, may allocate page */
SGP_WRITE, /* may exceed i_size, may allocate !Uptodate page */
SGP_FALLOC, /* like SGP_WRITE, but make existing page Uptodate */
extern int shmem_getpage(struct inode *inode, pgoff_t index,
struct page **pagep, enum sgp_type sgp);
static inline struct page *shmem_read_mapping_page(
struct address_space *mapping, pgoff_t index)
return shmem_read_mapping_page_gfp(mapping, index,
static inline bool shmem_file(struct file *file)
return false;
if (!file || !file->f_mapping)
return false;
return shmem_mapping(file->f_mapping);
* If fallocate(FALLOC_FL_KEEP_SIZE) has been used, there may be pages
* beyond i_size's notion of EOF, which fallocate has committed to reserving:
* which split_huge_page() must therefore not delete. This use of a single
* "fallocend" per inode errs on the side of not deleting a reservation when
* in doubt: there are plenty of cases when it preserves unreserved pages.
static inline pgoff_t shmem_fallocend(struct inode *inode, pgoff_t eof)
return max(eof, SHMEM_I(inode)->fallocend);
extern bool shmem_charge(struct inode *inode, long pages);
extern void shmem_uncharge(struct inode *inode, long pages);
extern int shmem_mfill_atomic_pte(struct mm_struct *dst_mm, pmd_t *dst_pmd,
struct vm_area_struct *dst_vma,
unsigned long dst_addr,
unsigned long src_addr,
bool zeropage,
struct page **pagep);
#else /* !CONFIG_SHMEM */
#define shmem_mfill_atomic_pte(dst_mm, dst_pmd, dst_vma, dst_addr, \
src_addr, zeropage, pagep) ({ BUG(); 0; })
#endif /* CONFIG_SHMEM */