linux/include/linux/shmem_fs.h

/* 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>
#include <linux/userfaultfd_k.h>

/* inode in-kernel data */

#ifdef CONFIG_TMPFS_QUOTA
#define SHMEM_MAXQUOTAS …
#endif

struct shmem_inode_info { … };

#define SHMEM_FL_USER_VISIBLE …
#define SHMEM_FL_USER_MODIFIABLE …
#define SHMEM_FL_INHERITED …

struct shmem_quota_limits { … };

struct shmem_sb_info { … };

static inline struct shmem_inode_info *SHMEM_I(struct inode *inode)
{ … }

/*
 * Functions in mm/shmem.c called directly from elsewhere:
 */
extern const struct fs_parameter_spec shmem_fs_parameters[];
extern void 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);
#ifdef CONFIG_SHMEM
bool shmem_mapping(struct address_space *mapping);
#else
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);
int shmem_unuse(unsigned int type);

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
extern bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
			  struct mm_struct *mm, unsigned long vm_flags);
unsigned long shmem_allowable_huge_orders(struct inode *inode,
				struct vm_area_struct *vma, pgoff_t index,
				bool global_huge);
#else
static __always_inline bool shmem_is_huge(struct inode *inode, pgoff_t index, bool shmem_huge_force,
					  struct mm_struct *mm, unsigned long vm_flags)
{
	return false;
}
static inline unsigned long shmem_allowable_huge_orders(struct inode *inode,
				struct vm_area_struct *vma, pgoff_t index,
				bool global_huge)
{
	return 0;
}
#endif

#ifdef CONFIG_SHMEM
extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
#else
static inline unsigned long shmem_swap_usage(struct vm_area_struct *vma)
{
	return 0;
}
#endif
extern unsigned long shmem_partial_swap_usage(struct address_space *mapping,
						pgoff_t start, pgoff_t end);

/* Flag allocation requirements to shmem_get_folio */
enum sgp_type { … };

int shmem_get_folio(struct inode *inode, pgoff_t index, struct folio **foliop,
		enum sgp_type sgp);
struct folio *shmem_read_folio_gfp(struct address_space *mapping,
		pgoff_t index, gfp_t gfp);

static inline struct folio *shmem_read_folio(struct address_space *mapping,
		pgoff_t index)
{ … }

static inline struct page *shmem_read_mapping_page(
				struct address_space *mapping, pgoff_t index)
{ … }

static inline bool shmem_file(struct file *file)
{ … }

/*
 * 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)
{ … }

extern bool shmem_charge(struct inode *inode, long pages);
extern void shmem_uncharge(struct inode *inode, long pages);

#ifdef CONFIG_USERFAULTFD
#ifdef CONFIG_SHMEM
extern int shmem_mfill_atomic_pte(pmd_t *dst_pmd,
				  struct vm_area_struct *dst_vma,
				  unsigned long dst_addr,
				  unsigned long src_addr,
				  uffd_flags_t flags,
				  struct folio **foliop);
#else /* !CONFIG_SHMEM */
#define shmem_mfill_atomic_pte …
#endif /* CONFIG_SHMEM */
#endif /* CONFIG_USERFAULTFD */

/*
 * Used space is stored as unsigned 64-bit value in bytes but
 * quota core supports only signed 64-bit values so use that
 * as a limit
 */
#define SHMEM_QUOTA_MAX_SPC_LIMIT …
#define SHMEM_QUOTA_MAX_INO_LIMIT …

#ifdef CONFIG_TMPFS_QUOTA
extern const struct dquot_operations shmem_quota_operations;
extern struct quota_format_type shmem_quota_format;
#endif /* CONFIG_TMPFS_QUOTA */

#endif