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

struct swap_iocb;

/* inode in-kernel data */

#ifdef CONFIG_TMPFS_QUOTA
#define SHMEM_MAXQUOTAS 2
#endif

/* Suppress pre-accounting of the entire object size. */
#define SHMEM_F_NORESERVE       BIT(0)
/* Disallow swapping. */
#define SHMEM_F_LOCKED          BIT(1)
/*
 * Disallow growing, shrinking, or hole punching in the inode. Combined with
 * folio pinning, makes sure the inode's mapping stays fixed.
 *
 * In some ways similar to F_SEAL_GROW | F_SEAL_SHRINK, but can be removed and
 * isn't directly visible to userspace.
 */
#define SHMEM_F_MAPPING_FROZEN  BIT(2)

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 */
        union {
            struct offset_ctx   dir_offsets;    /* stable directory offsets */
            struct {
                struct list_head shrinklist;    /* shrinkable hpage inodes */
                struct list_head swaplist;      /* chain of maybes on swap */
            };
        };
        struct timespec64       i_crtime;       /* file creation time */
        struct shared_policy    policy;         /* NUMA memory alloc policy */
        struct simple_xattrs    xattrs;         /* list of xattrs */
        pgoff_t                 fallocend;      /* highest fallocate endindex */
        unsigned int            fsflags;        /* for FS_IOC_[SG]ETFLAGS */
        atomic_t                stop_eviction;  /* hold when working on inode */
#ifdef CONFIG_TMPFS_QUOTA
        struct dquot __rcu      *i_dquot[MAXQUOTAS];
#endif
        struct inode            vfs_inode;
};

#define SHMEM_FL_USER_VISIBLE           (FS_FL_USER_VISIBLE | FS_CASEFOLD_FL)
#define SHMEM_FL_USER_MODIFIABLE \
        (FS_IMMUTABLE_FL | FS_APPEND_FL | FS_NODUMP_FL | FS_NOATIME_FL | FS_CASEFOLD_FL)
#define SHMEM_FL_INHERITED              (FS_NODUMP_FL | FS_NOATIME_FL | FS_CASEFOLD_FL)

struct shmem_quota_limits {
        qsize_t usrquota_bhardlimit; /* Default user quota block hard limit */
        qsize_t usrquota_ihardlimit; /* Default user quota inode hard limit */
        qsize_t grpquota_bhardlimit; /* Default group quota block hard limit */
        qsize_t grpquota_ihardlimit; /* Default group quota inode hard limit */
};

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_ispace;  /* How much ispace 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 */
        bool noswap;                /* ignores VM reclaim / swap requests */
        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 */
        struct shmem_quota_limits qlimits; /* Default quota limits */
};

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 void shmem_init(void);
extern int shmem_init_fs_context(struct fs_context *fc);
struct file *shmem_file_setup(const char *name, loff_t size, vma_flags_t flags);
struct file *shmem_kernel_file_setup(const char *name, loff_t size, vma_flags_t vma_flags);
extern struct file *shmem_file_setup_with_mnt(struct vfsmount *mnt,
                const char *name, loff_t size, vma_flags_t flags);
int shmem_zero_setup(struct vm_area_struct *vma);
int shmem_zero_setup_desc(struct vm_area_desc *desc);
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(const struct address_space *mapping);
#else
static inline bool shmem_mapping(const struct address_space *mapping)
{
        return false;
}
#endif /* CONFIG_SHMEM */
void shmem_unlock_mapping(struct address_space *mapping);
struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
                                        pgoff_t index, gfp_t gfp_mask);
int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
                struct list_head *folio_list);
void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
int shmem_unuse(unsigned int type);

#ifdef CONFIG_TRANSPARENT_HUGEPAGE
unsigned long shmem_allowable_huge_orders(struct inode *inode,
                                struct vm_area_struct *vma, pgoff_t index,
                                loff_t write_end, bool shmem_huge_force);
bool shmem_hpage_pmd_enabled(void);
#else
static inline unsigned long shmem_allowable_huge_orders(struct inode *inode,
                                struct vm_area_struct *vma, pgoff_t index,
                                loff_t write_end, bool shmem_huge_force)
{
        return 0;
}

static inline bool shmem_hpage_pmd_enabled(void)
{
        return false;
}
#endif

#ifdef CONFIG_SHMEM
extern unsigned long shmem_swap_usage(struct vm_area_struct *vma);
extern void shmem_uncharge(struct inode *inode, long pages);
#else
static inline unsigned long shmem_swap_usage(struct vm_area_struct *vma)
{
        return 0;
}

static inline void shmem_uncharge(struct inode *inode, long pages)
{
}
#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 {
        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 */
};

int shmem_get_folio(struct inode *inode, pgoff_t index, loff_t write_end,
                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)
{
        return shmem_read_folio_gfp(mapping, index, mapping_gfp_mask(mapping));
}

static inline struct page *shmem_read_mapping_page(
                                struct address_space *mapping, pgoff_t index)
{
        return shmem_read_mapping_page_gfp(mapping, index,
                                        mapping_gfp_mask(mapping));
}

static inline bool shmem_file(struct file *file)
{
        if (!IS_ENABLED(CONFIG_SHMEM))
                return false;
        if (!file || !file->f_mapping)
                return false;
        return shmem_mapping(file->f_mapping);
}

/* Must be called with inode lock taken exclusive. */
static inline void shmem_freeze(struct inode *inode, bool freeze)
{
        if (freeze)
                SHMEM_I(inode)->flags |= SHMEM_F_MAPPING_FROZEN;
        else
                SHMEM_I(inode)->flags &= ~SHMEM_F_MAPPING_FROZEN;
}

/*
 * 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);

#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(dst_pmd, dst_vma, dst_addr, \
                               src_addr, flags, foliop) ({ BUG(); 0; })
#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 0x7fffffffffffffffLL /* 2^63-1 */
#define SHMEM_QUOTA_MAX_INO_LIMIT 0x7fffffffffffffffLL

#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