/* SPDX-License-Identifier: GPL-2.0 */
/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2008  Miklos Szeredi <miklos@szeredi.hu>
*/

#ifndef _FS_FUSE_I_H
#define _FS_FUSE_I_H

#ifndef pr_fmt
# define pr_fmt(fmt) "fuse: " fmt
#endif

#include "args.h"
#include <linux/fuse.h>
#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/wait.h>
#include <linux/list.h>
#include <linux/spinlock.h>
#include <linux/mm.h>
#include <linux/backing-dev.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/rbtree.h>
#include <linux/poll.h>
#include <linux/workqueue.h>
#include <linux/kref.h>
#include <linux/xattr.h>
#include <linux/pid_namespace.h>
#include <linux/refcount.h>
#include <linux/user_namespace.h>

/** Default max number of pages that can be used in a single read request */
#define FUSE_DEFAULT_MAX_PAGES_PER_REQ 32

/** Bias for fi->writectr, meaning new writepages must not be sent */
#define FUSE_NOWRITE INT_MIN

/** Maximum length of a filename, not including terminating null */

/* maximum, small enough for FUSE_MIN_READ_BUFFER*/
#define FUSE_NAME_LOW_MAX 1024
/* maximum, but needs a request buffer > FUSE_MIN_READ_BUFFER */
#define FUSE_NAME_MAX (PATH_MAX - 1)

/** Number of dentries for each connection in the control filesystem */
#define FUSE_CTL_NUM_DENTRIES 5

/*
 * Dentries invalidation workqueue period, in seconds.  The value of this
 * parameter shall be >= FUSE_DENTRY_INVAL_FREQ_MIN seconds, or 0 (zero), in
 * which case no workqueue will be created.
 */
extern unsigned inval_wq __read_mostly;

/** Maximum of max_pages received in init_out */
extern unsigned int fuse_max_pages_limit;

/** List of active connections */
extern struct list_head fuse_conn_list;

/** Global mutex protecting fuse_conn_list and the control filesystem */
extern struct mutex fuse_mutex;

/** Module parameters */
extern unsigned int max_user_bgreq;
extern unsigned int max_user_congthresh;

struct fuse_forget_link;

/**
 * struct fuse_submount_lookup - Submount lookup tracking
 */
struct fuse_submount_lookup {
        /** @count: Refcount */
        refcount_t count;

        /**
         * @nodeid: Unique ID, which identifies the inode between userspace
         * and kernel
         */
        u64 nodeid;

        /** @forget: The request used for sending the FORGET message */
        struct fuse_forget_link *forget;
};

/* Container for data related to mapping to backing file */
struct fuse_backing {
        struct file *file;
        const struct cred *cred;

        /* refcount */
        refcount_t count;
        struct rcu_head rcu;
};

/**
 * struct fuse_inode - FUSE inode
 */
struct fuse_inode {
        /** @inode: Inode data */
        struct inode inode;

        /**
         * @nodeid: Unique ID, which identifies the inode between userspace
         * and kernel
         */
        u64 nodeid;

        /** @nlookup: Number of lookups on this inode */
        u64 nlookup;

        /** @forget: The request used for sending the FORGET message */
        struct fuse_forget_link *forget;

        /** @i_time: Time in jiffies until the file attributes are valid */
        u64 i_time;

        /** @inval_mask: Which attributes are invalid */
        u32 inval_mask;

        /**
         * @orig_i_mode: The sticky bit in inode->i_mode may have been removed,
         * so preserve the original mode
         */
        umode_t orig_i_mode;

        /** @i_btime: Cache birthtime */
        struct timespec64 i_btime;

        /** @orig_ino: 64-bit inode number */
        u64 orig_ino;

        /** @attr_version: Version of last attribute change */
        u64 attr_version;

        union {
                /* read/write io cache (regular file only) */
                struct {
                        /**
                         * @write_files: Files usable in writepage.
                         * Protected by fi->lock
                         */
                        struct list_head write_files;

                        /**
                         * @queued_writes: Writepages pending on truncate or
                         * fsync
                         */
                        struct list_head queued_writes;

                        /**
                         * @writectr: Number of sent writes, a negative bias
                         * (FUSE_NOWRITE) means more writes are blocked
                         */
                        int writectr;

                        /** @iocachectr: Number of files/maps using page cache */
                        int iocachectr;

                        /** @page_waitq: Waitq for writepage completion */
                        wait_queue_head_t page_waitq;

                        /** @direct_io_waitq: waitq for direct-io completion */
                        wait_queue_head_t direct_io_waitq;
                };

                /** @rdc: readdir cache (directory only) */
                struct {
                        /** @cached: true if fully cached */
                        bool cached;

                        /** @size: size of cache */
                        loff_t size;

                        /**
                         * @pos: position at end of cache (position of next
                         * entry)
                         */
                        loff_t pos;

                        /** @version: version of the cache */
                        u64 version;

                        /**
                         * @mtime: modification time of directory when cache was
                         * started
                         */
                        struct timespec64 mtime;

                        /**
                         * @epoch: epoch of fc when cache was started
                         */
                        int epoch;

                        /**
                         * @iversion: iversion of directory when cache was
                         * started
                         */
                        u64 iversion;

                        /** @lock: protects above fields */
                        spinlock_t lock;
                } rdc;
        };

        /** @state: Miscellaneous bits describing inode state */
        unsigned long state;

        /**
         * @mutex: Lock for serializing lookup and readdir for back
         * compatibility
         */
        struct mutex mutex;

        /** @lock: Lock to protect write-related fields */
        spinlock_t lock;

#ifdef CONFIG_FUSE_DAX
        /**
         * @dax: Dax specific inode data
         */
        struct fuse_inode_dax *dax;
#endif
        /** @submount_lookup: Submount specific lookup tracking */
        struct fuse_submount_lookup *submount_lookup;
#ifdef CONFIG_FUSE_PASSTHROUGH
        /** @fb: Reference to backing file in passthrough mode */
        struct fuse_backing *fb;
#endif

        /**
         * @cached_i_blkbits: The underlying inode->i_blkbits value will not
         * be modified, so preserve the blocksize specified by the server.
         */
        u8 cached_i_blkbits;
};

/** FUSE inode state bits */
enum {
        /** Advise readdirplus  */
        FUSE_I_ADVISE_RDPLUS,
        /** Initialized with readdirplus */
        FUSE_I_INIT_RDPLUS,
        /** An operation changing file size is in progress  */
        FUSE_I_SIZE_UNSTABLE,
        /* Bad inode */
        FUSE_I_BAD,
        /* Has btime */
        FUSE_I_BTIME,
        /* Wants or already has page cache IO */
        FUSE_I_CACHE_IO_MODE,
        /*
         * Client has exclusive access to the inode, either because fs is local
         * or the fuse server has an exclusive "lease" on distributed fs
         */
        FUSE_I_EXCLUSIVE,
};

struct fuse_conn;
struct fuse_mount;
union fuse_file_args;

/**
 * struct fuse_file - FUSE-specific file data
 */
struct fuse_file {
        /** @fm: Fuse connection for this file */
        struct fuse_mount *fm;

        /** @args: Argument space reserved for open/release */
        union fuse_file_args *args;

        /** @kh: Kernel file handle guaranteed to be unique */
        u64 kh;

        /** @fh: File handle used by userspace */
        u64 fh;

        /** @nodeid: Node id of this file */
        u64 nodeid;

        /** @count: Refcount */
        refcount_t count;

        /** @open_flags: FOPEN_* flags returned by open */
        u32 open_flags;

        /** @write_entry: Entry on inode's write_files list */
        struct list_head write_entry;

        /** @readdir: Readdir-related */
        struct {
                /** @pos: Dir stream position */
                loff_t pos;

                /** @cache_off: Offset in cache */
                loff_t cache_off;

                /** @version: Version of cache we are reading */
                u64 version;

        } readdir;

        /** @polled_node: RB node to be linked on fuse_conn->polled_files */
        struct rb_node polled_node;

        /** @poll_wait: Wait queue head for poll */
        wait_queue_head_t poll_wait;

        /** @iomode: Does file hold a fi->iocachectr refcount? */
        enum { IOM_NONE, IOM_CACHED, IOM_UNCACHED } iomode;

#ifdef CONFIG_FUSE_PASSTHROUGH
        /** @passthrough: Reference to backing file in passthrough mode */
        struct file *passthrough;
        /** @cred: passthrough file credentials */
        const struct cred *cred;
#endif

        /** @flock: Has flock been performed on this file? */
        bool flock:1;
};

struct fuse_release_args {
        struct fuse_args args;
        struct fuse_release_in inarg;
        struct inode *inode;
};

union fuse_file_args {
        /* Used during open() */
        struct fuse_open_out open_outarg;
        /* Used during release() */
        struct fuse_release_args release_args;
};

#define FUSE_ARGS(args) struct fuse_args args = {}

/** The request IO state (for asynchronous processing) */
struct fuse_io_priv {
        struct kref refcnt;
        struct work_struct work;
        int async;
        spinlock_t lock;
        unsigned reqs;
        ssize_t bytes;
        size_t size;
        __u64 offset;
        bool write;
        bool should_dirty;
        int err;
        struct kiocb *iocb;
        struct completion *done;
        bool blocking;
};

#define FUSE_IO_PRIV_SYNC(i) \
{                                       \
        .refcnt = KREF_INIT(1),         \
        .async = 0,                     \
        .iocb = i,                      \
}

enum fuse_dax_mode {
        FUSE_DAX_INODE_DEFAULT, /* default */
        FUSE_DAX_ALWAYS,        /* "-o dax=always" */
        FUSE_DAX_NEVER,         /* "-o dax=never" */
        FUSE_DAX_INODE_USER,    /* "-o dax=inode" */
};

static inline bool fuse_is_inode_dax_mode(enum fuse_dax_mode mode)
{
        return mode == FUSE_DAX_INODE_DEFAULT || mode == FUSE_DAX_INODE_USER;
}

struct fuse_fs_context {
        struct fuse_dev *fud;
        unsigned int rootmode;
        kuid_t user_id;
        kgid_t group_id;
        bool is_bdev:1;
        bool rootmode_present:1;
        bool user_id_present:1;
        bool group_id_present:1;
        bool default_permissions:1;
        bool allow_other:1;
        bool destroy:1;
        bool no_control:1;
        bool no_force_umount:1;
        bool legacy_opts_show:1;
        enum fuse_dax_mode dax_mode;
        unsigned int max_read;
        unsigned int blksize;
        const char *subtype;

        /* DAX device, may be NULL */
        struct dax_device *dax_dev;
};

struct fuse_sync_bucket {
        /* count is a possible scalability bottleneck */
        atomic_t count;
        wait_queue_head_t waitq;
        struct rcu_head rcu;
};

/**
 * struct fuse_conn - A Fuse connection.
 *
 * This structure is created, when the root filesystem is mounted, and
 * is destroyed, when the client device is closed and the last
 * fuse_mount is destroyed.
 */
struct fuse_conn {
        /**
         * @lock: Lock protecting:
         * - polled_files
         * - backing_files_map
         * - curr_bucket
         */
        spinlock_t lock;

        /** @count: Refcount */
        refcount_t count;

        /** @epoch: Current epoch for up-to-date dentries */
        atomic_t epoch;

        /** @epoch_work: Used to invalidate dentries from old epochs */
        struct work_struct epoch_work;

        /** @rcu: Used to delay freeing fuse_conn, making it safe */
        struct rcu_head rcu;

        /** @user_id: The user id for this mount */
        kuid_t user_id;

        /** @group_id: The group id for this mount */
        kgid_t group_id;

        /** @pid_ns: The pid namespace for this mount */
        struct pid_namespace *pid_ns;

        /** @user_ns: The user namespace for this mount */
        struct user_namespace *user_ns;

        /** @max_read: Maximum read size */
        unsigned max_read;

        /** @max_write: Maximum write size */
        unsigned max_write;

        /**
         * @max_pages: Maximum number of pages that can be used in a
         * single request
         */
        unsigned int max_pages;

        /**
         * @max_pages_limit: Constrain ->max_pages to this value during
         * feature negotiation
         */
        unsigned int max_pages_limit;

        /** @chan: transport layer object */
        struct fuse_chan *chan;

        /** @khctr: The next unique kernel file handle */
        atomic64_t khctr;

        /**
         * @polled_files: rbtree of fuse_files waiting for poll events
         * indexed by ph
         */
        struct rb_root polled_files;

        /**
         * @congestion_threshold: Number of background requests at which
         * congestion starts
         */
        unsigned congestion_threshold;

        /**
         * @conn_error: Connection failed (version mismatch).  Cannot race with
         * setting other bitfields since it is only set once in INIT
         * reply, before any other request, and never cleared
         */
        unsigned conn_error:1;

        /** @conn_init: Connection successful.  Only set in INIT */
        unsigned conn_init:1;

        /** @async_read: Do readahead asynchronously?  Only set in INIT */
        unsigned async_read:1;

        /**
         * @abort_err: Return an unique read error after abort.
         * Only set in INIT
         */
        unsigned abort_err:1;

        /**
         * @atomic_o_trunc: Do not send separate SETATTR request before
         * open(O_TRUNC)
         */
        unsigned atomic_o_trunc:1;

        /**
         * @export_support: Filesystem supports NFS exporting.
         * Only set in INIT
         */
        unsigned export_support:1;

        /** @writeback_cache: write-back cache policy (default is write-through) */
        unsigned writeback_cache:1;

        /**
         * @parallel_dirops: allow parallel lookups and readdir (default is
         * serialized)
         */
        unsigned parallel_dirops:1;

        /**
         * @handle_killpriv: handle fs handles killing suid/sgid/cap on
         * write/chown/trunc
         */
        unsigned handle_killpriv:1;

        /** @cache_symlinks: cache READLINK responses in page cache */
        unsigned cache_symlinks:1;

        /** @legacy_opts_show: show legacy mount options */
        unsigned int legacy_opts_show:1;

        /**
         * @handle_killpriv_v2:
         * fs kills suid/sgid/cap on write/chown/trunc. suid is killed on
         * write/trunc only if caller did not have CAP_FSETID.  sgid is killed
         * on write/truncate only if caller did not have CAP_FSETID as well as
         * file has group execute permission.
         */
        unsigned handle_killpriv_v2:1;

        /*
         * The following bitfields are only for optimization purposes
         * and hence races in setting them will not cause malfunction
         */

        /** @no_open: Is open/release not implemented by fs? */
        unsigned no_open:1;

        /** @no_opendir: Is opendir/releasedir not implemented by fs? */
        unsigned no_opendir:1;

        /** @no_fsync: Is fsync not implemented by fs? */
        unsigned no_fsync:1;

        /** @no_fsyncdir: Is fsyncdir not implemented by fs? */
        unsigned no_fsyncdir:1;

        /** @no_flush: Is flush not implemented by fs? */
        unsigned no_flush:1;

        /** @no_setxattr: Is setxattr not implemented by fs? */
        unsigned no_setxattr:1;

        /** @setxattr_ext: Does file server support extended setxattr */
        unsigned setxattr_ext:1;

        /** @no_getxattr: Is getxattr not implemented by fs? */
        unsigned no_getxattr:1;

        /** @no_listxattr: Is listxattr not implemented by fs? */
        unsigned no_listxattr:1;

        /** @no_removexattr: Is removexattr not implemented by fs? */
        unsigned no_removexattr:1;

        /** @no_lock: Are posix file locking primitives not implemented by fs? */
        unsigned no_lock:1;

        /** @no_access: Is access not implemented by fs? */
        unsigned no_access:1;

        /** @no_create: Is create not implemented by fs? */
        unsigned no_create:1;

        /** @no_bmap: Is bmap not implemented by fs? */
        unsigned no_bmap:1;

        /** @no_poll: Is poll not implemented by fs? */
        unsigned no_poll:1;

        /** @big_writes: Do multi-page cached writes */
        unsigned big_writes:1;

        /** @dont_mask: Don't apply umask to creation modes */
        unsigned dont_mask:1;

        /** @no_flock: Are BSD file locking primitives not implemented by fs? */
        unsigned no_flock:1;

        /** @no_fallocate: Is fallocate not implemented by fs? */
        unsigned no_fallocate:1;

        /** @no_rename2: Is rename with flags implemented by fs? */
        unsigned no_rename2:1;

        /** @auto_inval_data: Use enhanced/automatic page cache invalidation. */
        unsigned auto_inval_data:1;

        /**
         * @explicit_inval_data: Filesystem is fully responsible for page cache
         * invalidation.
         */
        unsigned explicit_inval_data:1;

        /** @do_readdirplus: Does the filesystem support readdirplus? */
        unsigned do_readdirplus:1;

        /** @readdirplus_auto: Does the filesystem want adaptive readdirplus? */
        unsigned readdirplus_auto:1;

        /**
         * @async_dio: Does the filesystem support asynchronous direct-IO
         * submission?
         */
        unsigned async_dio:1;

        /** @no_lseek: Is lseek not implemented by fs? */
        unsigned no_lseek:1;

        /** @posix_acl: Does the filesystem support posix acls? */
        unsigned posix_acl:1;

        /**
         * @default_permissions: Check permissions based on the file mode
         * or not?
         */
        unsigned default_permissions:1;

        /**
         * @allow_other: Allow other than the mounter user to access the
         * filesystem ?
         */
        unsigned allow_other:1;

        /** @no_copy_file_range: Does the filesystem support copy_file_range? */
        unsigned no_copy_file_range:1;

        /**
         * @no_copy_file_range_64: Does the filesystem support
         * copy_file_range_64?
         */
        unsigned no_copy_file_range_64:1;

        /** @destroy: Send DESTROY request */
        unsigned int destroy:1;

        /** @delete_stale: Delete dentries that have gone stale */
        unsigned int delete_stale:1;

        /** @no_control: Do not create entry in fusectl fs */
        unsigned int no_control:1;

        /** @no_force_umount: Do not allow MNT_FORCE umount */
        unsigned int no_force_umount:1;

        /** @auto_submounts: Auto-mount submounts announced by the server */
        unsigned int auto_submounts:1;

        /** @sync_fs: Propagate syncfs() to server */
        unsigned int sync_fs:1;

        /** @init_security: Initialize security xattrs when creating a new inode */
        unsigned int init_security:1;

        /**
         * @create_supp_group: Add supplementary group info when creating
         * a new inode
         */
        unsigned int create_supp_group:1;

        /** @inode_dax: Does the filesystem support per inode DAX? */
        unsigned int inode_dax:1;

        /** @no_tmpfile: Is tmpfile not implemented by fs? */
        unsigned int no_tmpfile:1;

        /**
         * @direct_io_allow_mmap: Relax restrictions to allow shared mmap
         * in FOPEN_DIRECT_IO mode
         */
        unsigned int direct_io_allow_mmap:1;

        /** @no_statx: Is statx not implemented by fs? */
        unsigned int no_statx:1;

        /** @passthrough: Passthrough support for read/write IO */
        unsigned int passthrough:1;

        /** @use_pages_for_kvec_io: Use pages instead of pointer for kernel I/O */
        unsigned int use_pages_for_kvec_io:1;

        /** @no_link: Is link not implemented by fs? */
        unsigned int no_link:1;

        /** @sync_init: Is synchronous FUSE_INIT allowed? */
        unsigned int sync_init:1;

        /** @max_stack_depth: Maximum stack depth for passthrough backing files */
        int max_stack_depth;

        /** @minor: Negotiated minor version */
        unsigned minor;

        /** @entry: Entry on the fuse_conn_list */
        struct list_head entry;

        /** @dev: Device ID from the root super block */
        dev_t dev;

        /** @scramble_key: Key for lock owner ID scrambling */
        u32 scramble_key[4];

        /** @attr_version: Version counter for attribute changes */
        atomic64_t attr_version;

        /** @evict_ctr: Version counter for evict inode */
        atomic64_t evict_ctr;

        /** @name_max: maximum file name length */
        u32 name_max;

        /** @release: Called on final put */
        void (*release)(struct fuse_conn *);

        /**
         * @killsb: Read/write semaphore to hold when accessing the sb of any
         * fuse_mount belonging to this connection
         */
        struct rw_semaphore killsb;

#ifdef CONFIG_FUSE_DAX
        /** @dax_mode: Dax mode */
        enum fuse_dax_mode dax_mode;

        /** @dax: Dax specific conn data, non-NULL if DAX is enabled */
        struct fuse_conn_dax *dax;
#endif

        /** @mounts: List of filesystems using this connection */
        struct list_head mounts;

        /** @curr_bucket: New writepages go into this bucket */
        struct fuse_sync_bucket __rcu *curr_bucket;

#ifdef CONFIG_FUSE_PASSTHROUGH
        /** @backing_files_map: IDR for backing files ids */
        struct idr backing_files_map;
#endif
};

/*
 * Represents a mounted filesystem, potentially a submount.
 *
 * This object allows sharing a fuse_conn between separate mounts to
 * allow submounts with dedicated superblocks and thus separate device
 * IDs.
 */
struct fuse_mount {
        /* Underlying (potentially shared) connection to the FUSE server */
        struct fuse_conn *fc;

        /*
         * Super block for this connection (fc->killsb must be held when
         * accessing this).
         */
        struct super_block *sb;

        /* Entry on fc->mounts */
        struct list_head fc_entry;
        struct rcu_head rcu;
};

/*
 * Empty header for FUSE opcodes without specific header needs.
 * Used as a placeholder in args->in_args[0] for consistency
 * across all FUSE operations, simplifying request handling.
 */
struct fuse_zero_header {};

static inline void fuse_set_zero_arg0(struct fuse_args *args)
{
        args->in_args[0].size = sizeof(struct fuse_zero_header);
        args->in_args[0].value = NULL;
}

static inline struct fuse_mount *get_fuse_mount_super(struct super_block *sb)
{
        return sb->s_fs_info;
}

static inline struct fuse_conn *get_fuse_conn_super(struct super_block *sb)
{
        return get_fuse_mount_super(sb)->fc;
}

static inline struct fuse_mount *get_fuse_mount(struct inode *inode)
{
        return get_fuse_mount_super(inode->i_sb);
}

static inline struct fuse_conn *get_fuse_conn(struct inode *inode)
{
        return get_fuse_mount_super(inode->i_sb)->fc;
}

static inline struct fuse_inode *get_fuse_inode(const struct inode *inode)
{
        return container_of(inode, struct fuse_inode, inode);
}

static inline u64 get_node_id(struct inode *inode)
{
        return get_fuse_inode(inode)->nodeid;
}

static inline int invalid_nodeid(u64 nodeid)
{
        return !nodeid || nodeid == FUSE_ROOT_ID;
}

static inline u64 fuse_get_attr_version(struct fuse_conn *fc)
{
        return atomic64_read(&fc->attr_version);
}

static inline u64 fuse_get_evict_ctr(struct fuse_conn *fc)
{
        return atomic64_read(&fc->evict_ctr);
}

static inline bool fuse_stale_inode(const struct inode *inode, int generation,
                                    struct fuse_attr *attr)
{
        return inode->i_generation != generation ||
                inode_wrong_type(inode, attr->mode);
}

static inline void fuse_make_bad(struct inode *inode)
{
        set_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state);
}

static inline bool fuse_is_bad(struct inode *inode)
{
        return unlikely(test_bit(FUSE_I_BAD, &get_fuse_inode(inode)->state));
}

static inline bool fuse_inode_is_exclusive(const struct inode *inode)
{
        const struct fuse_inode *fi = get_fuse_inode(inode);

        return test_bit(FUSE_I_EXCLUSIVE, &fi->state);
}

static inline struct folio **fuse_folios_alloc(unsigned int nfolios, gfp_t flags,
                                               struct fuse_folio_desc **desc)
{
        struct folio **folios;

        folios = kzalloc(nfolios * (sizeof(struct folio *) +
                                    sizeof(struct fuse_folio_desc)), flags);
        *desc = (void *) (folios + nfolios);

        return folios;
}

static inline void fuse_folio_descs_length_init(struct fuse_folio_desc *descs,
                                                unsigned int index,
                                                unsigned int nr_folios)
{
        int i;

        for (i = index; i < index + nr_folios; i++)
                descs[i].length = PAGE_SIZE - descs[i].offset;
}

static inline void fuse_sync_bucket_dec(struct fuse_sync_bucket *bucket)
{
        /* Need RCU protection to prevent use after free after the decrement */
        rcu_read_lock();
        if (atomic_dec_and_test(&bucket->count))
                wake_up(&bucket->waitq);
        rcu_read_unlock();
}

/** Device operations */
extern const struct file_operations fuse_dev_operations;

extern const struct dentry_operations fuse_dentry_operations;

/*
 * Get a filled in inode
 */
struct inode *fuse_iget(struct super_block *sb, u64 nodeid,
                        int generation, struct fuse_attr *attr,
                        u64 attr_valid, u64 attr_version,
                        u64 evict_ctr);

int fuse_lookup_name(struct super_block *sb, u64 nodeid, const struct qstr *name,
                     struct fuse_entry_out *outarg, struct inode **inode);

/*
 * Initialize READ or READDIR request
 */
struct fuse_io_args {
        union {
                struct {
                        struct fuse_read_in in;
                        u64 attr_ver;
                } read;
                struct {
                        struct fuse_write_in in;
                        struct fuse_write_out out;
                        bool folio_locked;
                } write;
        };
        struct fuse_args_pages ap;
        struct fuse_io_priv *io;
        struct fuse_file *ff;
};

void fuse_read_args_fill(struct fuse_io_args *ia, struct file *file, loff_t pos,
                         size_t count, int opcode);


struct fuse_file *fuse_file_alloc(struct fuse_mount *fm, bool release);
void fuse_file_free(struct fuse_file *ff);
int fuse_finish_open(struct inode *inode, struct file *file);

void fuse_sync_release(struct fuse_inode *fi, struct fuse_file *ff,
                       unsigned int flags);

/*
 * Send RELEASE or RELEASEDIR request
 */
void fuse_release_common(struct file *file, bool isdir);

/*
 * Send FSYNC or FSYNCDIR request
 */
int fuse_fsync_common(struct file *file, loff_t start, loff_t end,
                      int datasync, int opcode);

/*
 * Notify poll wakeup
 */
int fuse_notify_poll_wakeup(struct fuse_conn *fc,
                            struct fuse_notify_poll_wakeup_out *outarg);

/*
 * Initialize file operations on a regular file
 */
void fuse_init_file_inode(struct inode *inode, unsigned int flags);

/*
 * Initialize inode operations on regular files and special files
 */
void fuse_init_common(struct inode *inode);

/*
 * Initialize inode and file operations on a directory
 */
void fuse_init_dir(struct inode *inode);

/*
 * Initialize inode operations on a symlink
 */
void fuse_init_symlink(struct inode *inode);

/*
 * Change attributes of an inode
 */
void fuse_change_attributes(struct inode *inode, struct fuse_attr *attr,
                            struct fuse_statx *sx,
                            u64 attr_valid, u64 attr_version);

void fuse_change_attributes_common(struct inode *inode, struct fuse_attr *attr,
                                   struct fuse_statx *sx,
                                   u64 attr_valid, u32 cache_mask,
                                   u64 evict_ctr);

u32 fuse_get_cache_mask(struct inode *inode);

int fuse_ctl_init(void);
void __exit fuse_ctl_cleanup(void);

/*
 * Simple request sending that does request allocation and freeing
 */
ssize_t __fuse_simple_request(struct mnt_idmap *idmap,
                              struct fuse_mount *fm,
                              struct fuse_args *args);

static inline ssize_t fuse_simple_request(struct fuse_mount *fm, struct fuse_args *args)
{
        return __fuse_simple_request(&invalid_mnt_idmap, fm, args);
}

static inline ssize_t fuse_simple_idmap_request(struct mnt_idmap *idmap,
                                                struct fuse_mount *fm,
                                                struct fuse_args *args)
{
        return __fuse_simple_request(idmap, fm, args);
}

int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args,
                           gfp_t gfp_flags);
int fuse_simple_notify_reply(struct fuse_mount *fm, struct fuse_args *args, u64 unique);

void fuse_dentry_tree_init(void);
void fuse_dentry_tree_cleanup(void);

void fuse_epoch_work(struct work_struct *work);

/*
 * Invalidate inode attributes
 */

/* Attributes possibly changed on data modification */
#define FUSE_STATX_MODIFY       (STATX_MTIME | STATX_CTIME | STATX_BLOCKS)

/* Attributes possibly changed on data and/or size modification */
#define FUSE_STATX_MODSIZE      (FUSE_STATX_MODIFY | STATX_SIZE)

/* Attributes possibly changed on directory modification */
#define FUSE_STATX_MODDIR       (FUSE_STATX_MODSIZE | STATX_NLINK)

void fuse_invalidate_attr(struct inode *inode);
void fuse_invalidate_attr_mask(struct inode *inode, u32 mask);

void fuse_invalidate_entry_cache(struct dentry *entry);

void fuse_invalidate_atime(struct inode *inode);

u64 fuse_time_to_jiffies(u64 sec, u32 nsec);
#define ATTR_TIMEOUT(o) \
        fuse_time_to_jiffies((o)->attr_valid, (o)->attr_valid_nsec)

void fuse_change_entry_timeout(struct dentry *entry, struct fuse_entry_out *o);

/*
 * Initialize fuse_conn
 */
void fuse_conn_init(struct fuse_conn *fc, struct fuse_mount *fm,
                    struct user_namespace *user_ns, struct fuse_chan *fch);

int fuse_send_init(struct fuse_mount *fm);

/**
 * fuse_fill_super_common - Fill in superblock and initialize fuse connection
 * @sb: partially-initialized superblock to fill in
 * @ctx: mount context
 */
int fuse_fill_super_common(struct super_block *sb, struct fuse_fs_context *ctx);

/**
 * fuse_mount_remove - Remove the mount from the connection
 * @fm: fuse_mount to remove
 *
 * Returns: whether this was the last mount
 */
bool fuse_mount_remove(struct fuse_mount *fm);

/*
 * Setup context ops for submounts
 */
int fuse_init_fs_context_submount(struct fs_context *fsc);

/*
 * Shut down the connection (possibly sending DESTROY request).
 */
void fuse_conn_destroy(struct fuse_mount *fm);

/* Drop the connection and free the fuse mount */
void fuse_mount_destroy(struct fuse_mount *fm);

/**
 * fuse_ctl_add_conn - Add connection to control filesystem
 * @fc: Fuse connection to add
 */
int fuse_ctl_add_conn(struct fuse_conn *fc);

/**
 * fuse_ctl_remove_conn - Remove connection from control filesystem
 * @fc: Fuse connection to remove
 */
void fuse_ctl_remove_conn(struct fuse_conn *fc);

/*
 * Is file type valid?
 */
int fuse_valid_type(int m);

bool fuse_invalid_attr(struct fuse_attr *attr);

/*
 * Is current process allowed to perform filesystem operation?
 */
bool fuse_allow_current_process(struct fuse_conn *fc);

u64 fuse_lock_owner_id(struct fuse_conn *fc, fl_owner_t id);

void fuse_flush_time_update(struct inode *inode);
void fuse_update_ctime(struct inode *inode);

int fuse_update_attributes(struct inode *inode, struct file *file, u32 mask);

void fuse_flush_writepages(struct inode *inode);

void fuse_set_nowrite(struct inode *inode);
void fuse_release_nowrite(struct inode *inode);

/*
 * Scan all fuse_mounts belonging to fc to find the first where
 * ilookup5() returns a result.  Return that result and the
 * respective fuse_mount in *fm (unless fm is NULL).
 *
 * The caller must hold fc->killsb.
 */
struct inode *fuse_ilookup(struct fuse_conn *fc, u64 nodeid,
                           struct fuse_mount **fm);

/*
 * File-system tells the kernel to invalidate cache for the given node id.
 */
int fuse_reverse_inval_inode(struct fuse_conn *fc, u64 nodeid,
                             loff_t offset, loff_t len);

/*
 * File-system tells the kernel to invalidate parent attributes and
 * the dentry matching parent/name.
 *
 * If the child_nodeid is non-zero and:
 *    - matches the inode number for the dentry matching parent/name,
 *    - is not a mount point
 *    - is a file or oan empty directory
 * then the dentry is unhashed (d_delete()).
 */
int fuse_reverse_inval_entry(struct fuse_conn *fc, u64 parent_nodeid,
                             u64 child_nodeid, struct qstr *name, u32 flags);

/*
 * Try to prune this inode.  If neither the inode itself nor dentries associated
 * with this inode have any external reference, then the inode can be freed.
 */
void fuse_try_prune_one_inode(struct fuse_conn *fc, u64 nodeid);

int fuse_do_open(struct fuse_mount *fm, u64 nodeid, struct file *file,
                 bool isdir);

/*
 * fuse_direct_io() flags
 */

/** If set, it is WRITE; otherwise - READ */
#define FUSE_DIO_WRITE (1 << 0)

/** CUSE pass fuse_direct_io() a file which f_mapping->host is not from FUSE */
#define FUSE_DIO_CUSE  (1 << 1)

ssize_t fuse_direct_io(struct fuse_io_priv *io, struct iov_iter *iter,
                       loff_t *ppos, int flags);
long fuse_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg,
                   unsigned int flags);
long fuse_ioctl_common(struct file *file, unsigned int cmd,
                       unsigned long arg, unsigned int flags);
__poll_t fuse_file_poll(struct file *file, poll_table *wait);

bool fuse_write_update_attr(struct inode *inode, loff_t pos, ssize_t written);

int fuse_flush_times(struct inode *inode, struct fuse_file *ff);
int fuse_write_inode(struct inode *inode, struct writeback_control *wbc);

int fuse_do_setattr(struct mnt_idmap *idmap, struct dentry *dentry,
                    struct iattr *attr, struct file *file);

void fuse_unlock_inode(struct inode *inode, bool locked);
bool fuse_lock_inode(struct inode *inode);

int fuse_setxattr(struct inode *inode, const char *name, const void *value,
                  size_t size, int flags, unsigned int extra_flags);
ssize_t fuse_getxattr(struct inode *inode, const char *name, void *value,
                      size_t size);
ssize_t fuse_listxattr(struct dentry *entry, char *list, size_t size);
int fuse_removexattr(struct inode *inode, const char *name);
extern const struct xattr_handler * const fuse_xattr_handlers[];

struct posix_acl;
struct posix_acl *fuse_get_inode_acl(struct inode *inode, int type, bool rcu);
struct posix_acl *fuse_get_acl(struct mnt_idmap *idmap,
                               struct dentry *dentry, int type);
int fuse_set_acl(struct mnt_idmap *, struct dentry *dentry,
                 struct posix_acl *acl, int type);

/* readdir.c */
int fuse_readdir(struct file *file, struct dir_context *ctx);

void fuse_free_conn(struct fuse_conn *fc);

/* dax.c */

#define FUSE_IS_DAX(inode) (IS_ENABLED(CONFIG_FUSE_DAX) && IS_DAX(inode))

ssize_t fuse_dax_read_iter(struct kiocb *iocb, struct iov_iter *to);
ssize_t fuse_dax_write_iter(struct kiocb *iocb, struct iov_iter *from);
int fuse_dax_mmap(struct file *file, struct vm_area_struct *vma);
int fuse_dax_break_layouts(struct inode *inode, u64 dmap_start, u64 dmap_end);
int fuse_dax_conn_alloc(struct fuse_conn *fc, enum fuse_dax_mode mode,
                        struct dax_device *dax_dev);
void fuse_dax_conn_free(struct fuse_conn *fc);
bool fuse_dax_inode_alloc(struct super_block *sb, struct fuse_inode *fi);
void fuse_dax_inode_init(struct inode *inode, unsigned int flags);
void fuse_dax_inode_cleanup(struct inode *inode);
void fuse_dax_dontcache(struct inode *inode, unsigned int flags);
bool fuse_dax_check_alignment(struct fuse_conn *fc, unsigned int map_alignment);
void fuse_dax_cancel_work(struct fuse_conn *fc);

/* ioctl.c */
long fuse_file_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
long fuse_file_compat_ioctl(struct file *file, unsigned int cmd,
                            unsigned long arg);
int fuse_fileattr_get(struct dentry *dentry, struct file_kattr *fa);
int fuse_fileattr_set(struct mnt_idmap *idmap,
                      struct dentry *dentry, struct file_kattr *fa);

/* iomode.c */
int fuse_file_cached_io_open(struct inode *inode, struct fuse_file *ff);
int fuse_inode_uncached_io_start(struct fuse_inode *fi,
                                 struct fuse_backing *fb);
void fuse_inode_uncached_io_end(struct fuse_inode *fi);

int fuse_file_io_open(struct file *file, struct inode *inode);
void fuse_file_io_release(struct fuse_file *ff, struct inode *inode);

/* file.c */
struct fuse_file *fuse_file_open(struct fuse_mount *fm, u64 nodeid,
                                 unsigned int open_flags, bool isdir);
void fuse_file_release(struct inode *inode, struct fuse_file *ff,
                       unsigned int open_flags, fl_owner_t id, bool isdir);

/* backing.c */
#ifdef CONFIG_FUSE_PASSTHROUGH
struct fuse_backing *fuse_backing_get(struct fuse_backing *fb);
void fuse_backing_put(struct fuse_backing *fb);
struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc, int backing_id);
#else

static inline struct fuse_backing *fuse_backing_get(struct fuse_backing *fb)
{
        return NULL;
}

static inline void fuse_backing_put(struct fuse_backing *fb)
{
}
static inline struct fuse_backing *fuse_backing_lookup(struct fuse_conn *fc,
                                                       int backing_id)
{
        return NULL;
}
#endif

void fuse_backing_files_init(struct fuse_conn *fc);
void fuse_backing_files_free(struct fuse_conn *fc);

/* passthrough.c */
static inline struct fuse_backing *fuse_inode_backing(struct fuse_inode *fi)
{
#ifdef CONFIG_FUSE_PASSTHROUGH
        return READ_ONCE(fi->fb);
#else
        return NULL;
#endif
}

static inline struct fuse_backing *fuse_inode_backing_set(struct fuse_inode *fi,
                                                          struct fuse_backing *fb)
{
#ifdef CONFIG_FUSE_PASSTHROUGH
        return xchg(&fi->fb, fb);
#else
        return NULL;
#endif
}

struct fuse_backing *fuse_passthrough_open(struct file *file, int backing_id);
void fuse_passthrough_release(struct fuse_file *ff, struct fuse_backing *fb);

static inline struct file *fuse_file_passthrough(struct fuse_file *ff)
{
#ifdef CONFIG_FUSE_PASSTHROUGH
        return ff->passthrough;
#else
        return NULL;
#endif
}

ssize_t fuse_passthrough_read_iter(struct kiocb *iocb, struct iov_iter *iter);
ssize_t fuse_passthrough_write_iter(struct kiocb *iocb, struct iov_iter *iter);
ssize_t fuse_passthrough_splice_read(struct file *in, loff_t *ppos,
                                     struct pipe_inode_info *pipe,
                                     size_t len, unsigned int flags);
ssize_t fuse_passthrough_splice_write(struct pipe_inode_info *pipe,
                                      struct file *out, loff_t *ppos,
                                      size_t len, unsigned int flags);
ssize_t fuse_passthrough_mmap(struct file *file, struct vm_area_struct *vma);

#ifdef CONFIG_SYSCTL
extern int fuse_sysctl_register(void);
extern void fuse_sysctl_unregister(void);
#else
#define fuse_sysctl_register()          (0)
#define fuse_sysctl_unregister()        do { } while (0)
#endif /* CONFIG_SYSCTL */

#endif /* _FS_FUSE_I_H */