/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_FS_H
#define _LINUX_FS_H

#include <linux/linkage.h>
#include <linux/wait_bit.h>
#include <linux/kdev_t.h>
#include <linux/dcache.h>
#include <linux/path.h>
#include <linux/stat.h>
#include <linux/cache.h>
#include <linux/list.h>
#include <linux/list_lru.h>
#include <linux/llist.h>
#include <linux/radix-tree.h>
#include <linux/xarray.h>
#include <linux/rbtree.h>
#include <linux/init.h>
#include <linux/pid.h>
#include <linux/bug.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/mm_types.h>
#include <linux/capability.h>
#include <linux/semaphore.h>
#include <linux/fcntl.h>
#include <linux/rculist_bl.h>
#include <linux/atomic.h>
#include <linux/shrinker.h>
#include <linux/migrate_mode.h>
#include <linux/uidgid.h>
#include <linux/lockdep.h>
#include <linux/percpu-rwsem.h>
#include <linux/workqueue.h>
#include <linux/delayed_call.h>
#include <linux/uuid.h>
#include <linux/errseq.h>
#include <linux/ioprio.h>
#include <linux/fs_types.h>
#include <linux/build_bug.h>
#include <linux/stddef.h>
#include <linux/mount.h>
#include <linux/cred.h>
#include <linux/mnt_idmapping.h>
#include <linux/slab.h>

#include <asm/byteorder.h>
#include <uapi/linux/fs.h>

struct backing_dev_info;
struct bdi_writeback;
struct bio;
struct io_comp_batch;
struct export_operations;
struct fiemap_extent_info;
struct hd_geometry;
struct iovec;
struct kiocb;
struct kobject;
struct pipe_inode_info;
struct poll_table_struct;
struct kstatfs;
struct vm_area_struct;
struct vfsmount;
struct cred;
struct swap_info_struct;
struct seq_file;
struct workqueue_struct;
struct iov_iter;
struct fscrypt_info;
struct fscrypt_operations;
struct fsverity_info;
struct fsverity_operations;
struct fs_context;
struct fs_parameter_spec;
struct fileattr;

extern void __init inode_init(void);
extern void __init inode_init_early(void);
extern void __init files_init(void);
extern void __init files_maxfiles_init(void);

extern unsigned long get_max_files(void);
extern unsigned int sysctl_nr_open;

typedef __kernel_rwf_t rwf_t;

struct buffer_head;
typedef int (get_block_t)(struct inode *inode, sector_t iblock,
                        struct buffer_head *bh_result, int create);
typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
                        ssize_t bytes, void *private);

#define MAY_EXEC                0x00000001
#define MAY_WRITE               0x00000002
#define MAY_READ                0x00000004
#define MAY_APPEND              0x00000008
#define MAY_ACCESS              0x00000010
#define MAY_OPEN                0x00000020
#define MAY_CHDIR               0x00000040
/* called from RCU mode, don't block */
#define MAY_NOT_BLOCK           0x00000080

/*
 * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond
 * to O_WRONLY and O_RDWR via the strange trick in do_dentry_open()
 */

/* file is open for reading */
#define FMODE_READ              ((__force fmode_t)0x1)
/* file is open for writing */
#define FMODE_WRITE             ((__force fmode_t)0x2)
/* file is seekable */
#define FMODE_LSEEK             ((__force fmode_t)0x4)
/* file can be accessed using pread */
#define FMODE_PREAD             ((__force fmode_t)0x8)
/* file can be accessed using pwrite */
#define FMODE_PWRITE            ((__force fmode_t)0x10)
/* File is opened for execution with sys_execve / sys_uselib */
#define FMODE_EXEC              ((__force fmode_t)0x20)
/* File is opened with O_NDELAY (only set for block devices) */
#define FMODE_NDELAY            ((__force fmode_t)0x40)
/* File is opened with O_EXCL (only set for block devices) */
#define FMODE_EXCL              ((__force fmode_t)0x80)
/* File is opened using open(.., 3, ..) and is writeable only for ioctls
   (specialy hack for floppy.c) */
#define FMODE_WRITE_IOCTL       ((__force fmode_t)0x100)
/* 32bit hashes as llseek() offset (for directories) */
#define FMODE_32BITHASH         ((__force fmode_t)0x200)
/* 64bit hashes as llseek() offset (for directories) */
#define FMODE_64BITHASH         ((__force fmode_t)0x400)

/*
 * Don't update ctime and mtime.
 *
 * Currently a special hack for the XFS open_by_handle ioctl, but we'll
 * hopefully graduate it to a proper O_CMTIME flag supported by open(2) soon.
 */
#define FMODE_NOCMTIME          ((__force fmode_t)0x800)

/* Expect random access pattern */
#define FMODE_RANDOM            ((__force fmode_t)0x1000)

/* File is huge (eg. /dev/mem): treat loff_t as unsigned */
#define FMODE_UNSIGNED_OFFSET   ((__force fmode_t)0x2000)

/* File is opened with O_PATH; almost nothing can be done with it */
#define FMODE_PATH              ((__force fmode_t)0x4000)

/* File needs atomic accesses to f_pos */
#define FMODE_ATOMIC_POS        ((__force fmode_t)0x8000)
/* Write access to underlying fs */
#define FMODE_WRITER            ((__force fmode_t)0x10000)
/* Has read method(s) */
#define FMODE_CAN_READ          ((__force fmode_t)0x20000)
/* Has write method(s) */
#define FMODE_CAN_WRITE         ((__force fmode_t)0x40000)

#define FMODE_OPENED            ((__force fmode_t)0x80000)
#define FMODE_CREATED           ((__force fmode_t)0x100000)

/* File is stream-like */
#define FMODE_STREAM            ((__force fmode_t)0x200000)

/* File supports DIRECT IO */
#define FMODE_CAN_ODIRECT       ((__force fmode_t)0x400000)

/* File was opened by fanotify and shouldn't generate fanotify events */
#define FMODE_NONOTIFY          ((__force fmode_t)0x4000000)

/* File is capable of returning -EAGAIN if I/O will block */
#define FMODE_NOWAIT            ((__force fmode_t)0x8000000)

/* File represents mount that needs unmounting */
#define FMODE_NEED_UNMOUNT      ((__force fmode_t)0x10000000)

/* File does not contribute to nr_files count */
#define FMODE_NOACCOUNT         ((__force fmode_t)0x20000000)

/* File supports async buffered reads */
#define FMODE_BUF_RASYNC        ((__force fmode_t)0x40000000)

/*
 * Attribute flags.  These should be or-ed together to figure out what
 * has been changed!
 */
#define ATTR_MODE       (1 << 0)
#define ATTR_UID        (1 << 1)
#define ATTR_GID        (1 << 2)
#define ATTR_SIZE       (1 << 3)
#define ATTR_ATIME      (1 << 4)
#define ATTR_MTIME      (1 << 5)
#define ATTR_CTIME      (1 << 6)
#define ATTR_ATIME_SET  (1 << 7)
#define ATTR_MTIME_SET  (1 << 8)
#define ATTR_FORCE      (1 << 9) /* Not a change, but a change it */
#define ATTR_KILL_SUID  (1 << 11)
#define ATTR_KILL_SGID  (1 << 12)
#define ATTR_FILE       (1 << 13)
#define ATTR_KILL_PRIV  (1 << 14)
#define ATTR_OPEN       (1 << 15) /* Truncating from open(O_TRUNC) */
#define ATTR_TIMES_SET  (1 << 16)
#define ATTR_TOUCH      (1 << 17)

/*
 * Whiteout is represented by a char device.  The following constants define the
 * mode and device number to use.
 */
#define WHITEOUT_MODE 0
#define WHITEOUT_DEV 0

/*
 * This is the Inode Attributes structure, used for notify_change().  It
 * uses the above definitions as flags, to know which values have changed.
 * Also, in this manner, a Filesystem can look at only the values it cares
 * about.  Basically, these are the attributes that the VFS layer can
 * request to change from the FS layer.
 *
 * Derek Atkins <warlord@MIT.EDU> 94-10-20
 */
struct iattr {
        unsigned int    ia_valid;
        umode_t         ia_mode;
        kuid_t          ia_uid;
        kgid_t          ia_gid;
        loff_t          ia_size;
        struct timespec64 ia_atime;
        struct timespec64 ia_mtime;
        struct timespec64 ia_ctime;

        /*
         * Not an attribute, but an auxiliary info for filesystems wanting to
         * implement an ftruncate() like method.  NOTE: filesystem should
         * check for (ia_valid & ATTR_FILE), and not for (ia_file != NULL).
         */
        struct file     *ia_file;
};

/*
 * Includes for diskquotas.
 */
#include <linux/quota.h>

/*
 * Maximum number of layers of fs stack.  Needs to be limited to
 * prevent kernel stack overflow
 */
#define FILESYSTEM_MAX_STACK_DEPTH 2

/** 
 * enum positive_aop_returns - aop return codes with specific semantics
 *
 * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has
 *                          completed, that the page is still locked, and
 *                          should be considered active.  The VM uses this hint
 *                          to return the page to the active list -- it won't
 *                          be a candidate for writeback again in the near
 *                          future.  Other callers must be careful to unlock
 *                          the page if they get this return.  Returned by
 *                          writepage(); 
 *
 * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has
 *                      unlocked it and the page might have been truncated.
 *                      The caller should back up to acquiring a new page and
 *                      trying again.  The aop will be taking reasonable
 *                      precautions not to livelock.  If the caller held a page
 *                      reference, it should drop it before retrying.  Returned
 *                      by read_folio().
 *
 * address_space_operation functions return these large constants to indicate
 * special semantics to the caller.  These are much larger than the bytes in a
 * page to allow for functions that return the number of bytes operated on in a
 * given page.
 */

enum positive_aop_returns {
        AOP_WRITEPAGE_ACTIVATE  = 0x80000,
        AOP_TRUNCATED_PAGE      = 0x80001,
};

/*
 * oh the beauties of C type declarations.
 */
struct page;
struct address_space;
struct writeback_control;
struct readahead_control;

/*
 * Write life time hint values.
 * Stored in struct inode as u8.
 */
enum rw_hint {
        WRITE_LIFE_NOT_SET      = 0,
        WRITE_LIFE_NONE         = RWH_WRITE_LIFE_NONE,
        WRITE_LIFE_SHORT        = RWH_WRITE_LIFE_SHORT,
        WRITE_LIFE_MEDIUM       = RWH_WRITE_LIFE_MEDIUM,
        WRITE_LIFE_LONG         = RWH_WRITE_LIFE_LONG,
        WRITE_LIFE_EXTREME      = RWH_WRITE_LIFE_EXTREME,
};

/* Match RWF_* bits to IOCB bits */
#define IOCB_HIPRI              (__force int) RWF_HIPRI
#define IOCB_DSYNC              (__force int) RWF_DSYNC
#define IOCB_SYNC               (__force int) RWF_SYNC
#define IOCB_NOWAIT             (__force int) RWF_NOWAIT
#define IOCB_APPEND             (__force int) RWF_APPEND

/* non-RWF related bits - start at 16 */
#define IOCB_EVENTFD            (1 << 16)
#define IOCB_DIRECT             (1 << 17)
#define IOCB_WRITE              (1 << 18)
/* iocb->ki_waitq is valid */
#define IOCB_WAITQ              (1 << 19)
#define IOCB_NOIO               (1 << 20)
/* can use bio alloc cache */
#define IOCB_ALLOC_CACHE        (1 << 21)

struct kiocb {
        struct file             *ki_filp;

        /* The 'ki_filp' pointer is shared in a union for aio */
        randomized_struct_fields_start

        loff_t                  ki_pos;
        void (*ki_complete)(struct kiocb *iocb, long ret);
        void                    *private;
        int                     ki_flags;
        u16                     ki_ioprio; /* See linux/ioprio.h */
        struct wait_page_queue  *ki_waitq; /* for async buffered IO */
        randomized_struct_fields_end
};

static inline bool is_sync_kiocb(struct kiocb *kiocb)
{
        return kiocb->ki_complete == NULL;
}

struct address_space_operations {
        int (*writepage)(struct page *page, struct writeback_control *wbc);
        int (*read_folio)(struct file *, struct folio *);

        /* Write back some dirty pages from this mapping. */
        int (*writepages)(struct address_space *, struct writeback_control *);

        /* Mark a folio dirty.  Return true if this dirtied it */
        bool (*dirty_folio)(struct address_space *, struct folio *);

        void (*readahead)(struct readahead_control *);

        int (*write_begin)(struct file *, struct address_space *mapping,
                                loff_t pos, unsigned len,
                                struct page **pagep, void **fsdata);
        int (*write_end)(struct file *, struct address_space *mapping,
                                loff_t pos, unsigned len, unsigned copied,
                                struct page *page, void *fsdata);

        /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
        sector_t (*bmap)(struct address_space *, sector_t);
        void (*invalidate_folio) (struct folio *, size_t offset, size_t len);
        bool (*release_folio)(struct folio *, gfp_t);
        void (*free_folio)(struct folio *folio);
        ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
        /*
         * migrate the contents of a page to the specified target. If
         * migrate_mode is MIGRATE_ASYNC, it must not block.
         */
        int (*migratepage) (struct address_space *,
                        struct page *, struct page *, enum migrate_mode);
        bool (*isolate_page)(struct page *, isolate_mode_t);
        void (*putback_page)(struct page *);
        int (*launder_folio)(struct folio *);
        bool (*is_partially_uptodate) (struct folio *, size_t from,
                        size_t count);
        void (*is_dirty_writeback) (struct folio *, bool *dirty, bool *wb);
        int (*error_remove_page)(struct address_space *, struct page *);

        /* swapfile support */
        int (*swap_activate)(struct swap_info_struct *sis, struct file *file,
                                sector_t *span);
        void (*swap_deactivate)(struct file *file);
        int (*swap_rw)(struct kiocb *iocb, struct iov_iter *iter);
};

extern const struct address_space_operations empty_aops;

/**
 * struct address_space - Contents of a cacheable, mappable object.
 * @host: Owner, either the inode or the block_device.
 * @i_pages: Cached pages.
 * @invalidate_lock: Guards coherency between page cache contents and
 *   file offset->disk block mappings in the filesystem during invalidates.
 *   It is also used to block modification of page cache contents through
 *   memory mappings.
 * @gfp_mask: Memory allocation flags to use for allocating pages.
 * @i_mmap_writable: Number of VM_SHARED mappings.
 * @nr_thps: Number of THPs in the pagecache (non-shmem only).
 * @i_mmap: Tree of private and shared mappings.
 * @i_mmap_rwsem: Protects @i_mmap and @i_mmap_writable.
 * @nrpages: Number of page entries, protected by the i_pages lock.
 * @writeback_index: Writeback starts here.
 * @a_ops: Methods.
 * @flags: Error bits and flags (AS_*).
 * @wb_err: The most recent error which has occurred.
 * @private_lock: For use by the owner of the address_space.
 * @private_list: For use by the owner of the address_space.
 * @private_data: For use by the owner of the address_space.
 */
struct address_space {
        struct inode            *host;
        struct xarray           i_pages;
        struct rw_semaphore     invalidate_lock;
        gfp_t                   gfp_mask;
        atomic_t                i_mmap_writable;
#ifdef CONFIG_READ_ONLY_THP_FOR_FS
        /* number of thp, only for non-shmem files */
        atomic_t                nr_thps;
#endif
        struct rb_root_cached   i_mmap;
        struct rw_semaphore     i_mmap_rwsem;
        unsigned long           nrpages;
        pgoff_t                 writeback_index;
        const struct address_space_operations *a_ops;
        unsigned long           flags;
        errseq_t                wb_err;
        spinlock_t              private_lock;
        struct list_head        private_list;
        void                    *private_data;
} __attribute__((aligned(sizeof(long)))) __randomize_layout;
        /*
         * On most architectures that alignment is already the case; but
         * must be enforced here for CRIS, to let the least significant bit
         * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
         */

/* XArray tags, for tagging dirty and writeback pages in the pagecache. */
#define PAGECACHE_TAG_DIRTY     XA_MARK_0
#define PAGECACHE_TAG_WRITEBACK XA_MARK_1
#define PAGECACHE_TAG_TOWRITE   XA_MARK_2

/*
 * Returns true if any of the pages in the mapping are marked with the tag.
 */
static inline bool mapping_tagged(struct address_space *mapping, xa_mark_t tag)
{
        return xa_marked(&mapping->i_pages, tag);
}

static inline void i_mmap_lock_write(struct address_space *mapping)
{
        down_write(&mapping->i_mmap_rwsem);
}

static inline int i_mmap_trylock_write(struct address_space *mapping)
{
        return down_write_trylock(&mapping->i_mmap_rwsem);
}

static inline void i_mmap_unlock_write(struct address_space *mapping)
{
        up_write(&mapping->i_mmap_rwsem);
}

static inline int i_mmap_trylock_read(struct address_space *mapping)
{
        return down_read_trylock(&mapping->i_mmap_rwsem);
}

static inline void i_mmap_lock_read(struct address_space *mapping)
{
        down_read(&mapping->i_mmap_rwsem);
}

static inline void i_mmap_unlock_read(struct address_space *mapping)
{
        up_read(&mapping->i_mmap_rwsem);
}

static inline void i_mmap_assert_locked(struct address_space *mapping)
{
        lockdep_assert_held(&mapping->i_mmap_rwsem);
}

static inline void i_mmap_assert_write_locked(struct address_space *mapping)
{
        lockdep_assert_held_write(&mapping->i_mmap_rwsem);
}

/*
 * Might pages of this file be mapped into userspace?
 */
static inline int mapping_mapped(struct address_space *mapping)
{
        return  !RB_EMPTY_ROOT(&mapping->i_mmap.rb_root);
}

/*
 * Might pages of this file have been modified in userspace?
 * Note that i_mmap_writable counts all VM_SHARED vmas: do_mmap
 * marks vma as VM_SHARED if it is shared, and the file was opened for
 * writing i.e. vma may be mprotected writable even if now readonly.
 *
 * If i_mmap_writable is negative, no new writable mappings are allowed. You
 * can only deny writable mappings, if none exists right now.
 */
static inline int mapping_writably_mapped(struct address_space *mapping)
{
        return atomic_read(&mapping->i_mmap_writable) > 0;
}

static inline int mapping_map_writable(struct address_space *mapping)
{
        return atomic_inc_unless_negative(&mapping->i_mmap_writable) ?
                0 : -EPERM;
}

static inline void mapping_unmap_writable(struct address_space *mapping)
{
        atomic_dec(&mapping->i_mmap_writable);
}

static inline int mapping_deny_writable(struct address_space *mapping)
{
        return atomic_dec_unless_positive(&mapping->i_mmap_writable) ?
                0 : -EBUSY;
}

static inline void mapping_allow_writable(struct address_space *mapping)
{
        atomic_inc(&mapping->i_mmap_writable);
}

/*
 * Use sequence counter to get consistent i_size on 32-bit processors.
 */
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
#include <linux/seqlock.h>
#define __NEED_I_SIZE_ORDERED
#define i_size_ordered_init(inode) seqcount_init(&inode->i_size_seqcount)
#else
#define i_size_ordered_init(inode) do { } while (0)
#endif

struct posix_acl;
#define ACL_NOT_CACHED ((void *)(-1))
/*
 * ACL_DONT_CACHE is for stacked filesystems, that rely on underlying fs to
 * cache the ACL.  This also means that ->get_acl() can be called in RCU mode
 * with the LOOKUP_RCU flag.
 */
#define ACL_DONT_CACHE ((void *)(-3))

static inline struct posix_acl *
uncached_acl_sentinel(struct task_struct *task)
{
        return (void *)task + 1;
}

static inline bool
is_uncached_acl(struct posix_acl *acl)
{
        return (long)acl & 1;
}

#define IOP_FASTPERM    0x0001
#define IOP_LOOKUP      0x0002
#define IOP_NOFOLLOW    0x0004
#define IOP_XATTR       0x0008
#define IOP_DEFAULT_READLINK    0x0010

struct fsnotify_mark_connector;

/*
 * Keep mostly read-only and often accessed (especially for
 * the RCU path lookup and 'stat' data) fields at the beginning
 * of the 'struct inode'
 */
struct inode {
        umode_t                 i_mode;
        unsigned short          i_opflags;
        kuid_t                  i_uid;
        kgid_t                  i_gid;
        unsigned int            i_flags;

#ifdef CONFIG_FS_POSIX_ACL
        struct posix_acl        *i_acl;
        struct posix_acl        *i_default_acl;
#endif

        const struct inode_operations   *i_op;
        struct super_block      *i_sb;
        struct address_space    *i_mapping;

#ifdef CONFIG_SECURITY
        void                    *i_security;
#endif

        /* Stat data, not accessed from path walking */
        unsigned long           i_ino;
        /*
         * Filesystems may only read i_nlink directly.  They shall use the
         * following functions for modification:
         *
         *    (set|clear|inc|drop)_nlink
         *    inode_(inc|dec)_link_count
         */
        union {
                const unsigned int i_nlink;
                unsigned int __i_nlink;
        };
        dev_t                   i_rdev;
        loff_t                  i_size;
        struct timespec64       i_atime;
        struct timespec64       i_mtime;
        struct timespec64       i_ctime;
        spinlock_t              i_lock; /* i_blocks, i_bytes, maybe i_size */
        unsigned short          i_bytes;
        u8                      i_blkbits;
        u8                      i_write_hint;
        blkcnt_t                i_blocks;

#ifdef __NEED_I_SIZE_ORDERED
        seqcount_t              i_size_seqcount;
#endif

        /* Misc */
        unsigned long           i_state;
        struct rw_semaphore     i_rwsem;

        unsigned long           dirtied_when;   /* jiffies of first dirtying */
        unsigned long           dirtied_time_when;

        struct hlist_node       i_hash;
        struct list_head        i_io_list;      /* backing dev IO list */
#ifdef CONFIG_CGROUP_WRITEBACK
        struct bdi_writeback    *i_wb;          /* the associated cgroup wb */

        /* foreign inode detection, see wbc_detach_inode() */
        int                     i_wb_frn_winner;
        u16                     i_wb_frn_avg_time;
        u16                     i_wb_frn_history;
#endif
        struct list_head        i_lru;          /* inode LRU list */
        struct list_head        i_sb_list;
        struct list_head        i_wb_list;      /* backing dev writeback list */
        union {
                struct hlist_head       i_dentry;
                struct rcu_head         i_rcu;
        };
        atomic64_t              i_version;
        atomic64_t              i_sequence; /* see futex */
        atomic_t                i_count;
        atomic_t                i_dio_count;
        atomic_t                i_writecount;
#if defined(CONFIG_IMA) || defined(CONFIG_FILE_LOCKING)
        atomic_t                i_readcount; /* struct files open RO */
#endif
        union {
                const struct file_operations    *i_fop; /* former ->i_op->default_file_ops */
                void (*free_inode)(struct inode *);
        };
        struct file_lock_context        *i_flctx;
        struct address_space    i_data;
        struct list_head        i_devices;
        union {
                struct pipe_inode_info  *i_pipe;
                struct cdev             *i_cdev;
                char                    *i_link;
                unsigned                i_dir_seq;
        };

        __u32                   i_generation;

#ifdef CONFIG_FSNOTIFY
        __u32                   i_fsnotify_mask; /* all events this inode cares about */
        struct fsnotify_mark_connector __rcu    *i_fsnotify_marks;
#endif

#ifdef CONFIG_FS_ENCRYPTION
        struct fscrypt_info     *i_crypt_info;
#endif

#ifdef CONFIG_FS_VERITY
        struct fsverity_info    *i_verity_info;
#endif

        void                    *i_private; /* fs or device private pointer */
} __randomize_layout;

struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode);

static inline unsigned int i_blocksize(const struct inode *node)
{
        return (1 << node->i_blkbits);
}

static inline int inode_unhashed(struct inode *inode)
{
        return hlist_unhashed(&inode->i_hash);
}

/*
 * __mark_inode_dirty expects inodes to be hashed.  Since we don't
 * want special inodes in the fileset inode space, we make them
 * appear hashed, but do not put on any lists.  hlist_del()
 * will work fine and require no locking.
 */
static inline void inode_fake_hash(struct inode *inode)
{
        hlist_add_fake(&inode->i_hash);
}

/*
 * inode->i_mutex nesting subclasses for the lock validator:
 *
 * 0: the object of the current VFS operation
 * 1: parent
 * 2: child/target
 * 3: xattr
 * 4: second non-directory
 * 5: second parent (when locking independent directories in rename)
 *
 * I_MUTEX_NONDIR2 is for certain operations (such as rename) which lock two
 * non-directories at once.
 *
 * The locking order between these classes is
 * parent[2] -> child -> grandchild -> normal -> xattr -> second non-directory
 */
enum inode_i_mutex_lock_class
{
        I_MUTEX_NORMAL,
        I_MUTEX_PARENT,
        I_MUTEX_CHILD,
        I_MUTEX_XATTR,
        I_MUTEX_NONDIR2,
        I_MUTEX_PARENT2,
};

static inline void inode_lock(struct inode *inode)
{
        down_write(&inode->i_rwsem);
}

static inline void inode_unlock(struct inode *inode)
{
        up_write(&inode->i_rwsem);
}

static inline void inode_lock_shared(struct inode *inode)
{
        down_read(&inode->i_rwsem);
}

static inline void inode_unlock_shared(struct inode *inode)
{
        up_read(&inode->i_rwsem);
}

static inline int inode_trylock(struct inode *inode)
{
        return down_write_trylock(&inode->i_rwsem);
}

static inline int inode_trylock_shared(struct inode *inode)
{
        return down_read_trylock(&inode->i_rwsem);
}

static inline int inode_is_locked(struct inode *inode)
{
        return rwsem_is_locked(&inode->i_rwsem);
}

static inline void inode_lock_nested(struct inode *inode, unsigned subclass)
{
        down_write_nested(&inode->i_rwsem, subclass);
}

static inline void inode_lock_shared_nested(struct inode *inode, unsigned subclass)
{
        down_read_nested(&inode->i_rwsem, subclass);
}

static inline void filemap_invalidate_lock(struct address_space *mapping)
{
        down_write(&mapping->invalidate_lock);
}

static inline void filemap_invalidate_unlock(struct address_space *mapping)
{
        up_write(&mapping->invalidate_lock);
}

static inline void filemap_invalidate_lock_shared(struct address_space *mapping)
{
        down_read(&mapping->invalidate_lock);
}

static inline int filemap_invalidate_trylock_shared(
                                        struct address_space *mapping)
{
        return down_read_trylock(&mapping->invalidate_lock);
}

static inline void filemap_invalidate_unlock_shared(
                                        struct address_space *mapping)
{
        up_read(&mapping->invalidate_lock);
}

void lock_two_nondirectories(struct inode *, struct inode*);
void unlock_two_nondirectories(struct inode *, struct inode*);

void filemap_invalidate_lock_two(struct address_space *mapping1,
                                 struct address_space *mapping2);
void filemap_invalidate_unlock_two(struct address_space *mapping1,
                                   struct address_space *mapping2);


/*
 * NOTE: in a 32bit arch with a preemptable kernel and
 * an UP compile the i_size_read/write must be atomic
 * with respect to the local cpu (unlike with preempt disabled),
 * but they don't need to be atomic with respect to other cpus like in
 * true SMP (so they need either to either locally disable irq around
 * the read or for example on x86 they can be still implemented as a
 * cmpxchg8b without the need of the lock prefix). For SMP compiles
 * and 64bit archs it makes no difference if preempt is enabled or not.
 */
static inline loff_t i_size_read(const struct inode *inode)
{
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
        loff_t i_size;
        unsigned int seq;

        do {
                seq = read_seqcount_begin(&inode->i_size_seqcount);
                i_size = inode->i_size;
        } while (read_seqcount_retry(&inode->i_size_seqcount, seq));
        return i_size;
#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)
        loff_t i_size;

        preempt_disable();
        i_size = inode->i_size;
        preempt_enable();
        return i_size;
#else
        return inode->i_size;
#endif
}

/*
 * NOTE: unlike i_size_read(), i_size_write() does need locking around it
 * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount
 * can be lost, resulting in subsequent i_size_read() calls spinning forever.
 */
static inline void i_size_write(struct inode *inode, loff_t i_size)
{
#if BITS_PER_LONG==32 && defined(CONFIG_SMP)
        preempt_disable();
        write_seqcount_begin(&inode->i_size_seqcount);
        inode->i_size = i_size;
        write_seqcount_end(&inode->i_size_seqcount);
        preempt_enable();
#elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)
        preempt_disable();
        inode->i_size = i_size;
        preempt_enable();
#else
        inode->i_size = i_size;
#endif
}

static inline unsigned iminor(const struct inode *inode)
{
        return MINOR(inode->i_rdev);
}

static inline unsigned imajor(const struct inode *inode)
{
        return MAJOR(inode->i_rdev);
}

struct fown_struct {
        rwlock_t lock;          /* protects pid, uid, euid fields */
        struct pid *pid;        /* pid or -pgrp where SIGIO should be sent */
        enum pid_type pid_type; /* Kind of process group SIGIO should be sent to */
        kuid_t uid, euid;       /* uid/euid of process setting the owner */
        int signum;             /* posix.1b rt signal to be delivered on IO */
};

/**
 * struct file_ra_state - Track a file's readahead state.
 * @start: Where the most recent readahead started.
 * @size: Number of pages read in the most recent readahead.
 * @async_size: Numer of pages that were/are not needed immediately
 *      and so were/are genuinely "ahead".  Start next readahead when
 *      the first of these pages is accessed.
 * @ra_pages: Maximum size of a readahead request, copied from the bdi.
 * @mmap_miss: How many mmap accesses missed in the page cache.
 * @prev_pos: The last byte in the most recent read request.
 *
 * When this structure is passed to ->readahead(), the "most recent"
 * readahead means the current readahead.
 */
struct file_ra_state {
        pgoff_t start;
        unsigned int size;
        unsigned int async_size;
        unsigned int ra_pages;
        unsigned int mmap_miss;
        loff_t prev_pos;
};

/*
 * Check if @index falls in the readahead windows.
 */
static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
{
        return (index >= ra->start &&
                index <  ra->start + ra->size);
}

struct file {
        union {
                struct llist_node       fu_llist;
                struct rcu_head         fu_rcuhead;
        } f_u;
        struct path             f_path;
        struct inode            *f_inode;       /* cached value */
        const struct file_operations    *f_op;

        /*
         * Protects f_ep, f_flags.
         * Must not be taken from IRQ context.
         */
        spinlock_t              f_lock;
        atomic_long_t           f_count;
        unsigned int            f_flags;
        fmode_t                 f_mode;
        struct mutex            f_pos_lock;
        loff_t                  f_pos;
        struct fown_struct      f_owner;
        const struct cred       *f_cred;
        struct file_ra_state    f_ra;

        u64                     f_version;
#ifdef CONFIG_SECURITY
        void                    *f_security;
#endif
        /* needed for tty driver, and maybe others */
        void                    *private_data;

#ifdef CONFIG_EPOLL
        /* Used by fs/eventpoll.c to link all the hooks to this file */
        struct hlist_head       *f_ep;
#endif /* #ifdef CONFIG_EPOLL */
        struct address_space    *f_mapping;
        errseq_t                f_wb_err;
        errseq_t                f_sb_err; /* for syncfs */
} __randomize_layout
  __attribute__((aligned(4)));  /* lest something weird decides that 2 is OK */

struct file_handle {
        __u32 handle_bytes;
        int handle_type;
        /* file identifier */
        unsigned char f_handle[];
};

static inline struct file *get_file(struct file *f)
{
        atomic_long_inc(&f->f_count);
        return f;
}
#define get_file_rcu(x) atomic_long_inc_not_zero(&(x)->f_count)
#define file_count(x)   atomic_long_read(&(x)->f_count)

#define MAX_NON_LFS     ((1UL<<31) - 1)

/* Page cache limit. The filesystems should put that into their s_maxbytes 
   limits, otherwise bad things can happen in VM. */ 
#if BITS_PER_LONG==32
#define MAX_LFS_FILESIZE        ((loff_t)ULONG_MAX << PAGE_SHIFT)
#elif BITS_PER_LONG==64
#define MAX_LFS_FILESIZE        ((loff_t)LLONG_MAX)
#endif

#define FL_POSIX        1
#define FL_FLOCK        2
#define FL_DELEG        4       /* NFSv4 delegation */
#define FL_ACCESS       8       /* not trying to lock, just looking */
#define FL_EXISTS       16      /* when unlocking, test for existence */
#define FL_LEASE        32      /* lease held on this file */
#define FL_CLOSE        64      /* unlock on close */
#define FL_SLEEP        128     /* A blocking lock */
#define FL_DOWNGRADE_PENDING    256 /* Lease is being downgraded */
#define FL_UNLOCK_PENDING       512 /* Lease is being broken */
#define FL_OFDLCK       1024    /* lock is "owned" by struct file */

#define FL_LAYOUT       2048    /* outstanding pNFS layout */
#define FL_RECLAIM      4096    /* reclaiming from a reboot server */

#define FL_CLOSE_POSIX (FL_POSIX | FL_CLOSE)

/*
 * Special return value from posix_lock_file() and vfs_lock_file() for
 * asynchronous locking.
 */
#define FILE_LOCK_DEFERRED 1

/* legacy typedef, should eventually be removed */
typedef void *fl_owner_t;

struct file_lock;

struct file_lock_operations {
        void (*fl_copy_lock)(struct file_lock *, struct file_lock *);
        void (*fl_release_private)(struct file_lock *);
};

struct lock_manager_operations {
        void *lm_mod_owner;
        fl_owner_t (*lm_get_owner)(fl_owner_t);
        void (*lm_put_owner)(fl_owner_t);
        void (*lm_notify)(struct file_lock *);  /* unblock callback */
        int (*lm_grant)(struct file_lock *, int);
        bool (*lm_break)(struct file_lock *);
        int (*lm_change)(struct file_lock *, int, struct list_head *);
        void (*lm_setup)(struct file_lock *, void **);
        bool (*lm_breaker_owns_lease)(struct file_lock *);
        bool (*lm_lock_expirable)(struct file_lock *cfl);
        void (*lm_expire_lock)(void);
};

struct lock_manager {
        struct list_head list;
        /*
         * NFSv4 and up also want opens blocked during the grace period;
         * NLM doesn't care:
         */
        bool block_opens;
};

struct net;
void locks_start_grace(struct net *, struct lock_manager *);
void locks_end_grace(struct lock_manager *);
bool locks_in_grace(struct net *);
bool opens_in_grace(struct net *);

/* that will die - we need it for nfs_lock_info */
#include <linux/nfs_fs_i.h>

/*
 * struct file_lock represents a generic "file lock". It's used to represent
 * POSIX byte range locks, BSD (flock) locks, and leases. It's important to
 * note that the same struct is used to represent both a request for a lock and
 * the lock itself, but the same object is never used for both.
 *
 * FIXME: should we create a separate "struct lock_request" to help distinguish
 * these two uses?
 *
 * The varous i_flctx lists are ordered by:
 *
 * 1) lock owner
 * 2) lock range start
 * 3) lock range end
 *
 * Obviously, the last two criteria only matter for POSIX locks.
 */
struct file_lock {
        struct file_lock *fl_blocker;   /* The lock, that is blocking us */
        struct list_head fl_list;       /* link into file_lock_context */
        struct hlist_node fl_link;      /* node in global lists */
        struct list_head fl_blocked_requests;   /* list of requests with
                                                 * ->fl_blocker pointing here
                                                 */
        struct list_head fl_blocked_member;     /* node in
                                                 * ->fl_blocker->fl_blocked_requests
                                                 */
        fl_owner_t fl_owner;
        unsigned int fl_flags;
        unsigned char fl_type;
        unsigned int fl_pid;
        int fl_link_cpu;                /* what cpu's list is this on? */
        wait_queue_head_t fl_wait;
        struct file *fl_file;
        loff_t fl_start;
        loff_t fl_end;

        struct fasync_struct *  fl_fasync; /* for lease break notifications */
        /* for lease breaks: */
        unsigned long fl_break_time;
        unsigned long fl_downgrade_time;

        const struct file_lock_operations *fl_ops;      /* Callbacks for filesystems */
        const struct lock_manager_operations *fl_lmops; /* Callbacks for lockmanagers */
        union {
                struct nfs_lock_info    nfs_fl;
                struct nfs4_lock_info   nfs4_fl;
                struct {
                        struct list_head link;  /* link in AFS vnode's pending_locks list */
                        int state;              /* state of grant or error if -ve */
                        unsigned int    debug_id;
                } afs;
        } fl_u;
} __randomize_layout;

struct file_lock_context {
        spinlock_t              flc_lock;
        struct list_head        flc_flock;
        struct list_head        flc_posix;
        struct list_head        flc_lease;
};

/* The following constant reflects the upper bound of the file/locking space */
#ifndef OFFSET_MAX
#define INT_LIMIT(x)    (~((x)1 << (sizeof(x)*8 - 1)))
#define OFFSET_MAX      INT_LIMIT(loff_t)
#define OFFT_OFFSET_MAX INT_LIMIT(off_t)
#endif

extern void send_sigio(struct fown_struct *fown, int fd, int band);

#define locks_inode(f) file_inode(f)

#ifdef CONFIG_FILE_LOCKING
extern int fcntl_getlk(struct file *, unsigned int, struct flock *);
extern int fcntl_setlk(unsigned int, struct file *, unsigned int,
                        struct flock *);

#if BITS_PER_LONG == 32
extern int fcntl_getlk64(struct file *, unsigned int, struct flock64 *);
extern int fcntl_setlk64(unsigned int, struct file *, unsigned int,
                        struct flock64 *);
#endif

extern int fcntl_setlease(unsigned int fd, struct file *filp, long arg);
extern int fcntl_getlease(struct file *filp);

/* fs/locks.c */
void locks_free_lock_context(struct inode *inode);
void locks_free_lock(struct file_lock *fl);
extern void locks_init_lock(struct file_lock *);
extern struct file_lock * locks_alloc_lock(void);
extern void locks_copy_lock(struct file_lock *, struct file_lock *);
extern void locks_copy_conflock(struct file_lock *, struct file_lock *);
extern void locks_remove_posix(struct file *, fl_owner_t);
extern void locks_remove_file(struct file *);
extern void locks_release_private(struct file_lock *);
extern void posix_test_lock(struct file *, struct file_lock *);
extern int posix_lock_file(struct file *, struct file_lock *, struct file_lock *);
extern int locks_delete_block(struct file_lock *);
extern int vfs_test_lock(struct file *, struct file_lock *);
extern int vfs_lock_file(struct file *, unsigned int, struct file_lock *, struct file_lock *);
extern int vfs_cancel_lock(struct file *filp, struct file_lock *fl);
extern int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl);
extern int __break_lease(struct inode *inode, unsigned int flags, unsigned int type);
extern void lease_get_mtime(struct inode *, struct timespec64 *time);
extern int generic_setlease(struct file *, long, struct file_lock **, void **priv);
extern int vfs_setlease(struct file *, long, struct file_lock **, void **);
extern int lease_modify(struct file_lock *, int, struct list_head *);

struct notifier_block;
extern int lease_register_notifier(struct notifier_block *);
extern void lease_unregister_notifier(struct notifier_block *);

struct files_struct;
extern void show_fd_locks(struct seq_file *f,
                         struct file *filp, struct files_struct *files);
extern bool locks_owner_has_blockers(struct file_lock_context *flctx,
                        fl_owner_t owner);
#else /* !CONFIG_FILE_LOCKING */
static inline int fcntl_getlk(struct file *file, unsigned int cmd,
                              struct flock __user *user)
{
        return -EINVAL;
}

static inline int fcntl_setlk(unsigned int fd, struct file *file,
                              unsigned int cmd, struct flock __user *user)
{
        return -EACCES;
}

#if BITS_PER_LONG == 32
static inline int fcntl_getlk64(struct file *file, unsigned int cmd,
                                struct flock64 *user)
{
        return -EINVAL;
}

static inline int fcntl_setlk64(unsigned int fd, struct file *file,
                                unsigned int cmd, struct flock64 *user)
{
        return -EACCES;
}
#endif
static inline int fcntl_setlease(unsigned int fd, struct file *filp, long arg)
{
        return -EINVAL;
}

static inline int fcntl_getlease(struct file *filp)
{
        return F_UNLCK;
}

static inline void
locks_free_lock_context(struct inode *inode)
{
}

static inline void locks_init_lock(struct file_lock *fl)
{
        return;
}

static inline void locks_copy_conflock(struct file_lock *new, struct file_lock *fl)
{
        return;
}

static inline void locks_copy_lock(struct file_lock *new, struct file_lock *fl)
{
        return;
}

static inline void locks_remove_posix(struct file *filp, fl_owner_t owner)
{
        return;
}

static inline void locks_remove_file(struct file *filp)
{
        return;
}

static inline void posix_test_lock(struct file *filp, struct file_lock *fl)
{
        return;
}

static inline int posix_lock_file(struct file *filp, struct file_lock *fl,
                                  struct file_lock *conflock)
{
        return -ENOLCK;
}

static inline int locks_delete_block(struct file_lock *waiter)
{
        return -ENOENT;
}

static inline int vfs_test_lock(struct file *filp, struct file_lock *fl)
{
        return 0;
}

static inline int vfs_lock_file(struct file *filp, unsigned int cmd,
                                struct file_lock *fl, struct file_lock *conf)
{
        return -ENOLCK;
}

static inline int vfs_cancel_lock(struct file *filp, struct file_lock *fl)
{
        return 0;
}

static inline int locks_lock_inode_wait(struct inode *inode, struct file_lock *fl)
{
        return -ENOLCK;
}

static inline int __break_lease(struct inode *inode, unsigned int mode, unsigned int type)
{
        return 0;
}

static inline void lease_get_mtime(struct inode *inode,
                                   struct timespec64 *time)
{
        return;
}

static inline int generic_setlease(struct file *filp, long arg,
                                    struct file_lock **flp, void **priv)
{
        return -EINVAL;
}

static inline int vfs_setlease(struct file *filp, long arg,
                               struct file_lock **lease, void **priv)
{
        return -EINVAL;
}

static inline int lease_modify(struct file_lock *fl, int arg,
                               struct list_head *dispose)
{
        return -EINVAL;
}

struct files_struct;
static inline void show_fd_locks(struct seq_file *f,
                        struct file *filp, struct files_struct *files) {}
static inline bool locks_owner_has_blockers(struct file_lock_context *flctx,
                        fl_owner_t owner)
{
        return false;
}
#endif /* !CONFIG_FILE_LOCKING */

static inline struct inode *file_inode(const struct file *f)
{
        return f->f_inode;
}

static inline struct dentry *file_dentry(const struct file *file)
{
        return d_real(file->f_path.dentry, file_inode(file));
}

static inline int locks_lock_file_wait(struct file *filp, struct file_lock *fl)
{
        return locks_lock_inode_wait(locks_inode(filp), fl);
}

struct fasync_struct {
        rwlock_t                fa_lock;
        int                     magic;
        int                     fa_fd;
        struct fasync_struct    *fa_next; /* singly linked list */
        struct file             *fa_file;
        struct rcu_head         fa_rcu;
};

#define FASYNC_MAGIC 0x4601

/* SMP safe fasync helpers: */
extern int fasync_helper(int, struct file *, int, struct fasync_struct **);
extern struct fasync_struct *fasync_insert_entry(int, struct file *, struct fasync_struct **, struct fasync_struct *);
extern int fasync_remove_entry(struct file *, struct fasync_struct **);
extern struct fasync_struct *fasync_alloc(void);
extern void fasync_free(struct fasync_struct *);

/* can be called from interrupts */
extern void kill_fasync(struct fasync_struct **, int, int);

extern void __f_setown(struct file *filp, struct pid *, enum pid_type, int force);
extern int f_setown(struct file *filp, unsigned long arg, int force);
extern void f_delown(struct file *filp);
extern pid_t f_getown(struct file *filp);
extern int send_sigurg(struct fown_struct *fown);

/*
 * sb->s_flags.  Note that these mirror the equivalent MS_* flags where
 * represented in both.
 */
#define SB_RDONLY        1      /* Mount read-only */
#define SB_NOSUID        2      /* Ignore suid and sgid bits */
#define SB_NODEV         4      /* Disallow access to device special files */
#define SB_NOEXEC        8      /* Disallow program execution */
#define SB_SYNCHRONOUS  16      /* Writes are synced at once */
#define SB_MANDLOCK     64      /* Allow mandatory locks on an FS */
#define SB_DIRSYNC      128     /* Directory modifications are synchronous */
#define SB_NOATIME      1024    /* Do not update access times. */
#define SB_NODIRATIME   2048    /* Do not update directory access times */
#define SB_SILENT       32768
#define SB_POSIXACL     (1<<16) /* VFS does not apply the umask */
#define SB_INLINECRYPT  (1<<17) /* Use blk-crypto for encrypted files */
#define SB_KERNMOUNT    (1<<22) /* this is a kern_mount call */
#define SB_I_VERSION    (1<<23) /* Update inode I_version field */
#define SB_LAZYTIME     (1<<25) /* Update the on-disk [acm]times lazily */

/* These sb flags are internal to the kernel */
#define SB_SUBMOUNT     (1<<26)
#define SB_FORCE        (1<<27)
#define SB_NOSEC        (1<<28)
#define SB_BORN         (1<<29)
#define SB_ACTIVE       (1<<30)
#define SB_NOUSER       (1<<31)

/* These flags relate to encoding and casefolding */
#define SB_ENC_STRICT_MODE_FL   (1 << 0)

#define sb_has_strict_encoding(sb) \
        (sb->s_encoding_flags & SB_ENC_STRICT_MODE_FL)

/*
 *      Umount options
 */

#define MNT_FORCE       0x00000001      /* Attempt to forcibily umount */
#define MNT_DETACH      0x00000002      /* Just detach from the tree */
#define MNT_EXPIRE      0x00000004      /* Mark for expiry */
#define UMOUNT_NOFOLLOW 0x00000008      /* Don't follow symlink on umount */
#define UMOUNT_UNUSED   0x80000000      /* Flag guaranteed to be unused */

/* sb->s_iflags */
#define SB_I_CGROUPWB   0x00000001      /* cgroup-aware writeback enabled */
#define SB_I_NOEXEC     0x00000002      /* Ignore executables on this fs */
#define SB_I_NODEV      0x00000004      /* Ignore devices on this fs */
#define SB_I_STABLE_WRITES 0x00000008   /* don't modify blks until WB is done */

/* sb->s_iflags to limit user namespace mounts */
#define SB_I_USERNS_VISIBLE             0x00000010 /* fstype already mounted */
#define SB_I_IMA_UNVERIFIABLE_SIGNATURE 0x00000020
#define SB_I_UNTRUSTED_MOUNTER          0x00000040

#define SB_I_SKIP_SYNC  0x00000100      /* Skip superblock at global sync */
#define SB_I_PERSB_BDI  0x00000200      /* has a per-sb bdi */
#define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */

/* Possible states of 'frozen' field */
enum {
        SB_UNFROZEN = 0,                /* FS is unfrozen */
        SB_FREEZE_WRITE = 1,            /* Writes, dir ops, ioctls frozen */
        SB_FREEZE_PAGEFAULT = 2,        /* Page faults stopped as well */
        SB_FREEZE_FS = 3,               /* For internal FS use (e.g. to stop
                                         * internal threads if needed) */
        SB_FREEZE_COMPLETE = 4,         /* ->freeze_fs finished successfully */
};

#define SB_FREEZE_LEVELS (SB_FREEZE_COMPLETE - 1)

struct sb_writers {
        int                             frozen;         /* Is sb frozen? */
        wait_queue_head_t               wait_unfrozen;  /* wait for thaw */
        struct percpu_rw_semaphore      rw_sem[SB_FREEZE_LEVELS];
};

struct super_block {
        struct list_head        s_list;         /* Keep this first */
        dev_t                   s_dev;          /* search index; _not_ kdev_t */
        unsigned char           s_blocksize_bits;
        unsigned long           s_blocksize;
        loff_t                  s_maxbytes;     /* Max file size */
        struct file_system_type *s_type;
        const struct super_operations   *s_op;
        const struct dquot_operations   *dq_op;
        const struct quotactl_ops       *s_qcop;
        const struct export_operations *s_export_op;
        unsigned long           s_flags;
        unsigned long           s_iflags;       /* internal SB_I_* flags */
        unsigned long           s_magic;
        struct dentry           *s_root;
        struct rw_semaphore     s_umount;
        int                     s_count;
        atomic_t                s_active;
#ifdef CONFIG_SECURITY
        void                    *s_security;
#endif
        const struct xattr_handler **s_xattr;
#ifdef CONFIG_FS_ENCRYPTION
        const struct fscrypt_operations *s_cop;
        struct key              *s_master_keys; /* master crypto keys in use */
#endif
#ifdef CONFIG_FS_VERITY
        const struct fsverity_operations *s_vop;
#endif
#if IS_ENABLED(CONFIG_UNICODE)
        struct unicode_map *s_encoding;
        __u16 s_encoding_flags;
#endif
        struct hlist_bl_head    s_roots;        /* alternate root dentries for NFS */
        struct list_head        s_mounts;       /* list of mounts; _not_ for fs use */
        struct block_device     *s_bdev;
        struct backing_dev_info *s_bdi;
        struct mtd_info         *s_mtd;
        struct hlist_node       s_instances;
        unsigned int            s_quota_types;  /* Bitmask of supported quota types */
        struct quota_info       s_dquot;        /* Diskquota specific options */

        struct sb_writers       s_writers;

        /*
         * Keep s_fs_info, s_time_gran, s_fsnotify_mask, and
         * s_fsnotify_marks together for cache efficiency. They are frequently
         * accessed and rarely modified.
         */
        void                    *s_fs_info;     /* Filesystem private info */

        /* Granularity of c/m/atime in ns (cannot be worse than a second) */
        u32                     s_time_gran;
        /* Time limits for c/m/atime in seconds */
        time64_t                   s_time_min;
        time64_t                   s_time_max;
#ifdef CONFIG_FSNOTIFY
        __u32                   s_fsnotify_mask;
        struct fsnotify_mark_connector __rcu    *s_fsnotify_marks;
#endif

        char                    s_id[32];       /* Informational name */
        uuid_t                  s_uuid;         /* UUID */

        unsigned int            s_max_links;
        fmode_t                 s_mode;

        /*
         * The next field is for VFS *only*. No filesystems have any business
         * even looking at it. You had been warned.
         */
        struct mutex s_vfs_rename_mutex;        /* Kludge */

        /*
         * Filesystem subtype.  If non-empty the filesystem type field
         * in /proc/mounts will be "type.subtype"
         */
        const char *s_subtype;

        const struct dentry_operations *s_d_op; /* default d_op for dentries */

        struct shrinker s_shrink;       /* per-sb shrinker handle */

        /* Number of inodes with nlink == 0 but still referenced */
        atomic_long_t s_remove_count;

        /*
         * Number of inode/mount/sb objects that are being watched, note that
         * inodes objects are currently double-accounted.
         */
        atomic_long_t s_fsnotify_connectors;

        /* Being remounted read-only */
        int s_readonly_remount;

        /* per-sb errseq_t for reporting writeback errors via syncfs */
        errseq_t s_wb_err;

        /* AIO completions deferred from interrupt context */
        struct workqueue_struct *s_dio_done_wq;
        struct hlist_head s_pins;

        /*
         * Owning user namespace and default context in which to
         * interpret filesystem uids, gids, quotas, device nodes,
         * xattrs and security labels.
         */
        struct user_namespace *s_user_ns;

        /*
         * The list_lru structure is essentially just a pointer to a table
         * of per-node lru lists, each of which has its own spinlock.
         * There is no need to put them into separate cachelines.
         */
        struct list_lru         s_dentry_lru;
        struct list_lru         s_inode_lru;
        struct rcu_head         rcu;
        struct work_struct      destroy_work;

        struct mutex            s_sync_lock;    /* sync serialisation lock */

        /*
         * Indicates how deep in a filesystem stack this SB is
         */
        int s_stack_depth;

        /* s_inode_list_lock protects s_inodes */
        spinlock_t              s_inode_list_lock ____cacheline_aligned_in_smp;
        struct list_head        s_inodes;       /* all inodes */

        spinlock_t              s_inode_wblist_lock;
        struct list_head        s_inodes_wb;    /* writeback inodes */
} __randomize_layout;

static inline struct user_namespace *i_user_ns(const struct inode *inode)
{
        return inode->i_sb->s_user_ns;
}

/* Helper functions so that in most cases filesystems will
 * not need to deal directly with kuid_t and kgid_t and can
 * instead deal with the raw numeric values that are stored
 * in the filesystem.
 */
static inline uid_t i_uid_read(const struct inode *inode)
{
        return from_kuid(i_user_ns(inode), inode->i_uid);
}

static inline gid_t i_gid_read(const struct inode *inode)
{
        return from_kgid(i_user_ns(inode), inode->i_gid);
}

static inline void i_uid_write(struct inode *inode, uid_t uid)
{
        inode->i_uid = make_kuid(i_user_ns(inode), uid);
}

static inline void i_gid_write(struct inode *inode, gid_t gid)
{
        inode->i_gid = make_kgid(i_user_ns(inode), gid);
}

/**
 * i_uid_into_mnt - map an inode's i_uid down into a mnt_userns
 * @mnt_userns: user namespace of the mount the inode was found from
 * @inode: inode to map
 *
 * Return: the inode's i_uid mapped down according to @mnt_userns.
 * If the inode's i_uid has no mapping INVALID_UID is returned.
 */
static inline kuid_t i_uid_into_mnt(struct user_namespace *mnt_userns,
                                    const struct inode *inode)
{
        return mapped_kuid_fs(mnt_userns, i_user_ns(inode), inode->i_uid);
}

/**
 * i_gid_into_mnt - map an inode's i_gid down into a mnt_userns
 * @mnt_userns: user namespace of the mount the inode was found from
 * @inode: inode to map
 *
 * Return: the inode's i_gid mapped down according to @mnt_userns.
 * If the inode's i_gid has no mapping INVALID_GID is returned.
 */
static inline kgid_t i_gid_into_mnt(struct user_namespace *mnt_userns,
                                    const struct inode *inode)
{
        return mapped_kgid_fs(mnt_userns, i_user_ns(inode), inode->i_gid);
}

/**
 * inode_fsuid_set - initialize inode's i_uid field with callers fsuid
 * @inode: inode to initialize
 * @mnt_userns: user namespace of the mount the inode was found from
 *
 * Initialize the i_uid field of @inode. If the inode was found/created via
 * an idmapped mount map the caller's fsuid according to @mnt_users.
 */
static inline void inode_fsuid_set(struct inode *inode,
                                   struct user_namespace *mnt_userns)
{
        inode->i_uid = mapped_fsuid(mnt_userns, i_user_ns(inode));
}

/**
 * inode_fsgid_set - initialize inode's i_gid field with callers fsgid
 * @inode: inode to initialize
 * @mnt_userns: user namespace of the mount the inode was found from
 *
 * Initialize the i_gid field of @inode. If the inode was found/created via
 * an idmapped mount map the caller's fsgid according to @mnt_users.
 */
static inline void inode_fsgid_set(struct inode *inode,
                                   struct user_namespace *mnt_userns)
{
        inode->i_gid = mapped_fsgid(mnt_userns, i_user_ns(inode));
}

/**
 * fsuidgid_has_mapping() - check whether caller's fsuid/fsgid is mapped
 * @sb: the superblock we want a mapping in
 * @mnt_userns: user namespace of the relevant mount
 *
 * Check whether the caller's fsuid and fsgid have a valid mapping in the
 * s_user_ns of the superblock @sb. If the caller is on an idmapped mount map
 * the caller's fsuid and fsgid according to the @mnt_userns first.
 *
 * Return: true if fsuid and fsgid is mapped, false if not.
 */
static inline bool fsuidgid_has_mapping(struct super_block *sb,
                                        struct user_namespace *mnt_userns)
{
        struct user_namespace *fs_userns = sb->s_user_ns;
        kuid_t kuid;
        kgid_t kgid;

        kuid = mapped_fsuid(mnt_userns, fs_userns);
        if (!uid_valid(kuid))
                return false;
        kgid = mapped_fsgid(mnt_userns, fs_userns);
        if (!gid_valid(kgid))
                return false;
        return kuid_has_mapping(fs_userns, kuid) &&
               kgid_has_mapping(fs_userns, kgid);
}

extern struct timespec64 current_time(struct inode *inode);

/*
 * Snapshotting support.
 */

/*
 * These are internal functions, please use sb_start_{write,pagefault,intwrite}
 * instead.
 */
static inline void __sb_end_write(struct super_block *sb, int level)
{
        percpu_up_read(sb->s_writers.rw_sem + level-1);
}

static inline void __sb_start_write(struct super_block *sb, int level)
{
        percpu_down_read(sb->s_writers.rw_sem + level - 1);
}

static inline bool __sb_start_write_trylock(struct super_block *sb, int level)
{
        return percpu_down_read_trylock(sb->s_writers.rw_sem + level - 1);
}

#define __sb_writers_acquired(sb, lev)  \
        percpu_rwsem_acquire(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)
#define __sb_writers_release(sb, lev)   \
        percpu_rwsem_release(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)

static inline bool sb_write_started(const struct super_block *sb)
{
        return lockdep_is_held_type(sb->s_writers.rw_sem + SB_FREEZE_WRITE - 1, 1);
}

/**
 * sb_end_write - drop write access to a superblock
 * @sb: the super we wrote to
 *
 * Decrement number of writers to the filesystem. Wake up possible waiters
 * wanting to freeze the filesystem.
 */
static inline void sb_end_write(struct super_block *sb)
{
        __sb_end_write(sb, SB_FREEZE_WRITE);
}

/**
 * sb_end_pagefault - drop write access to a superblock from a page fault
 * @sb: the super we wrote to
 *
 * Decrement number of processes handling write page fault to the filesystem.
 * Wake up possible waiters wanting to freeze the filesystem.
 */
static inline void sb_end_pagefault(struct super_block *sb)
{
        __sb_end_write(sb, SB_FREEZE_PAGEFAULT);
}

/**
 * sb_end_intwrite - drop write access to a superblock for internal fs purposes
 * @sb: the super we wrote to
 *
 * Decrement fs-internal number of writers to the filesystem.  Wake up possible
 * waiters wanting to freeze the filesystem.
 */
static inline void sb_end_intwrite(struct super_block *sb)
{
        __sb_end_write(sb, SB_FREEZE_FS);
}

/**
 * sb_start_write - get write access to a superblock
 * @sb: the super we write to
 *
 * When a process wants to write data or metadata to a file system (i.e. dirty
 * a page or an inode), it should embed the operation in a sb_start_write() -
 * sb_end_write() pair to get exclusion against file system freezing. This
 * function increments number of writers preventing freezing. If the file
 * system is already frozen, the function waits until the file system is
 * thawed.
 *
 * Since freeze protection behaves as a lock, users have to preserve
 * ordering of freeze protection and other filesystem locks. Generally,
 * freeze protection should be the outermost lock. In particular, we have:
 *
 * sb_start_write
 *   -> i_mutex                 (write path, truncate, directory ops, ...)
 *   -> s_umount                (freeze_super, thaw_super)
 */
static inline void sb_start_write(struct super_block *sb)
{
        __sb_start_write(sb, SB_FREEZE_WRITE);
}

static inline bool sb_start_write_trylock(struct super_block *sb)
{
        return __sb_start_write_trylock(sb, SB_FREEZE_WRITE);
}

/**
 * sb_start_pagefault - get write access to a superblock from a page fault
 * @sb: the super we write to
 *
 * When a process starts handling write page fault, it should embed the
 * operation into sb_start_pagefault() - sb_end_pagefault() pair to get
 * exclusion against file system freezing. This is needed since the page fault
 * is going to dirty a page. This function increments number of running page
 * faults preventing freezing. If the file system is already frozen, the
 * function waits until the file system is thawed.
 *
 * Since page fault freeze protection behaves as a lock, users have to preserve
 * ordering of freeze protection and other filesystem locks. It is advised to
 * put sb_start_pagefault() close to mmap_lock in lock ordering. Page fault
 * handling code implies lock dependency:
 *
 * mmap_lock
 *   -> sb_start_pagefault
 */
static inline void sb_start_pagefault(struct super_block *sb)
{
        __sb_start_write(sb, SB_FREEZE_PAGEFAULT);
}

/**
 * sb_start_intwrite - get write access to a superblock for internal fs purposes
 * @sb: the super we write to
 *
 * This is the third level of protection against filesystem freezing. It is
 * free for use by a filesystem. The only requirement is that it must rank
 * below sb_start_pagefault.
 *
 * For example filesystem can call sb_start_intwrite() when starting a
 * transaction which somewhat eases handling of freezing for internal sources
 * of filesystem changes (internal fs threads, discarding preallocation on file
 * close, etc.).
 */
static inline void sb_start_intwrite(struct super_block *sb)
{
        __sb_start_write(sb, SB_FREEZE_FS);
}

static inline bool sb_start_intwrite_trylock(struct super_block *sb)
{
        return __sb_start_write_trylock(sb, SB_FREEZE_FS);
}

bool inode_owner_or_capable(struct user_namespace *mnt_userns,
                            const struct inode *inode);

/*
 * VFS helper functions..
 */
int vfs_create(struct user_namespace *, struct inode *,
               struct dentry *, umode_t, bool);
int vfs_mkdir(struct user_namespace *, struct inode *,
              struct dentry *, umode_t);
int vfs_mknod(struct user_namespace *, struct inode *, struct dentry *,
              umode_t, dev_t);
int vfs_symlink(struct user_namespace *, struct inode *,
                struct dentry *, const char *);
int vfs_link(struct dentry *, struct user_namespace *, struct inode *,
             struct dentry *, struct inode **);
int vfs_rmdir(struct user_namespace *, struct inode *, struct dentry *);
int vfs_unlink(struct user_namespace *, struct inode *, struct dentry *,
               struct inode **);

/**
 * struct renamedata - contains all information required for renaming
 * @old_mnt_userns:    old user namespace of the mount the inode was found from
 * @old_dir:           parent of source
 * @old_dentry:                source
 * @new_mnt_userns:    new user namespace of the mount the inode was found from
 * @new_dir:           parent of destination
 * @new_dentry:                destination
 * @delegated_inode:   returns an inode needing a delegation break
 * @flags:             rename flags
 */
struct renamedata {
        struct user_namespace *old_mnt_userns;
        struct inode *old_dir;
        struct dentry *old_dentry;
        struct user_namespace *new_mnt_userns;
        struct inode *new_dir;
        struct dentry *new_dentry;
        struct inode **delegated_inode;
        unsigned int flags;
} __randomize_layout;

int vfs_rename(struct renamedata *);

static inline int vfs_whiteout(struct user_namespace *mnt_userns,
                               struct inode *dir, struct dentry *dentry)
{
        return vfs_mknod(mnt_userns, dir, dentry, S_IFCHR | WHITEOUT_MODE,
                         WHITEOUT_DEV);
}

struct dentry *vfs_tmpfile(struct user_namespace *mnt_userns,
                           struct dentry *dentry, umode_t mode, int open_flag);

int vfs_mkobj(struct dentry *, umode_t,
                int (*f)(struct dentry *, umode_t, void *),
                void *);

int vfs_fchown(struct file *file, uid_t user, gid_t group);
int vfs_fchmod(struct file *file, umode_t mode);
int vfs_utimes(const struct path *path, struct timespec64 *times);

extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);

#ifdef CONFIG_COMPAT
extern long compat_ptr_ioctl(struct file *file, unsigned int cmd,
                                        unsigned long arg);
#else
#define compat_ptr_ioctl NULL
#endif

/*
 * VFS file helper functions.
 */
void inode_init_owner(struct user_namespace *mnt_userns, struct inode *inode,
                      const struct inode *dir, umode_t mode);
extern bool may_open_dev(const struct path *path);

/*
 * This is the "filldir" function type, used by readdir() to let
 * the kernel specify what kind of dirent layout it wants to have.
 * This allows the kernel to read directories into kernel space or
 * to have different dirent layouts depending on the binary type.
 */
struct dir_context;
typedef int (*filldir_t)(struct dir_context *, const char *, int, loff_t, u64,
                         unsigned);

struct dir_context {
        filldir_t actor;
        loff_t pos;
};

/*
 * These flags let !MMU mmap() govern direct device mapping vs immediate
 * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
 *
 * NOMMU_MAP_COPY:      Copy can be mapped (MAP_PRIVATE)
 * NOMMU_MAP_DIRECT:    Can be mapped directly (MAP_SHARED)
 * NOMMU_MAP_READ:      Can be mapped for reading
 * NOMMU_MAP_WRITE:     Can be mapped for writing
 * NOMMU_MAP_EXEC:      Can be mapped for execution
 */
#define NOMMU_MAP_COPY          0x00000001
#define NOMMU_MAP_DIRECT        0x00000008
#define NOMMU_MAP_READ          VM_MAYREAD
#define NOMMU_MAP_WRITE         VM_MAYWRITE
#define NOMMU_MAP_EXEC          VM_MAYEXEC

#define NOMMU_VMFLAGS \
        (NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC)

/*
 * These flags control the behavior of the remap_file_range function pointer.
 * If it is called with len == 0 that means "remap to end of source file".
 * See Documentation/filesystems/vfs.rst for more details about this call.
 *
 * REMAP_FILE_DEDUP: only remap if contents identical (i.e. deduplicate)
 * REMAP_FILE_CAN_SHORTEN: caller can handle a shortened request
 */
#define REMAP_FILE_DEDUP                (1 << 0)
#define REMAP_FILE_CAN_SHORTEN          (1 << 1)

/*
 * These flags signal that the caller is ok with altering various aspects of
 * the behavior of the remap operation.  The changes must be made by the
 * implementation; the vfs remap helper functions can take advantage of them.
 * Flags in this category exist to preserve the quirky behavior of the hoisted
 * btrfs clone/dedupe ioctls.
 */
#define REMAP_FILE_ADVISORY             (REMAP_FILE_CAN_SHORTEN)

struct iov_iter;
struct io_uring_cmd;

struct file_operations {
        struct module *owner;
        loff_t (*llseek) (struct file *, loff_t, int);
        ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
        ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
        ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
        ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
        int (*iopoll)(struct kiocb *kiocb, struct io_comp_batch *,
                        unsigned int flags);
        int (*iterate) (struct file *, struct dir_context *);
        int (*iterate_shared) (struct file *, struct dir_context *);
        __poll_t (*poll) (struct file *, struct poll_table_struct *);
        long (*unlocked_ioctl) (struct file *, unsigned int, unsigned long);
        long (*compat_ioctl) (struct file *, unsigned int, unsigned long);
        int (*mmap) (struct file *, struct vm_area_struct *);
        unsigned long mmap_supported_flags;
        int (*open) (struct inode *, struct file *);
        int (*flush) (struct file *, fl_owner_t id);
        int (*release) (struct inode *, struct file *);
        int (*fsync) (struct file *, loff_t, loff_t, int datasync);
        int (*fasync) (int, struct file *, int);
        int (*lock) (struct file *, int, struct file_lock *);
        ssize_t (*sendpage) (struct file *, struct page *, int, size_t, loff_t *, int);
        unsigned long (*get_unmapped_area)(struct file *, unsigned long, unsigned long, unsigned long, unsigned long);
        int (*check_flags)(int);
        int (*flock) (struct file *, int, struct file_lock *);
        ssize_t (*splice_write)(struct pipe_inode_info *, struct file *, loff_t *, size_t, unsigned int);
        ssize_t (*splice_read)(struct file *, loff_t *, struct pipe_inode_info *, size_t, unsigned int);
        int (*setlease)(struct file *, long, struct file_lock **, void **);
        long (*fallocate)(struct file *file, int mode, loff_t offset,
                          loff_t len);
        void (*show_fdinfo)(struct seq_file *m, struct file *f);
#ifndef CONFIG_MMU
        unsigned (*mmap_capabilities)(struct file *);
#endif
        ssize_t (*copy_file_range)(struct file *, loff_t, struct file *,
                        loff_t, size_t, unsigned int);

        loff_t (*remap_file_range)(struct file *file_in, loff_t pos_in,
                                   struct file *file_out, loff_t pos_out,
                                   loff_t len, unsigned int remap_flags);
        int (*fadvise)(struct file *, loff_t, loff_t, int);
        int (*uring_cmd)(struct io_uring_cmd *ioucmd, unsigned int issue_flags);
} __randomize_layout;

struct inode_operations {
        struct dentry * (*lookup) (struct inode *,struct dentry *, unsigned int);
        const char * (*get_link) (struct dentry *, struct inode *, struct delayed_call *);
        int (*permission) (struct user_namespace *, struct inode *, int);
        struct posix_acl * (*get_acl)(struct inode *, int, bool);

        int (*readlink) (struct dentry *, char __user *,int);

        int (*create) (struct user_namespace *, struct inode *,struct dentry *,
                       umode_t, bool);
        int (*link) (struct dentry *,struct inode *,struct dentry *);
        int (*unlink) (struct inode *,struct dentry *);
        int (*symlink) (struct user_namespace *, struct inode *,struct dentry *,
                        const char *);
        int (*mkdir) (struct user_namespace *, struct inode *,struct dentry *,
                      umode_t);
        int (*rmdir) (struct inode *,struct dentry *);
        int (*mknod) (struct user_namespace *, struct inode *,struct dentry *,
                      umode_t,dev_t);
        int (*rename) (struct user_namespace *, struct inode *, struct dentry *,
                        struct inode *, struct dentry *, unsigned int);
        int (*setattr) (struct user_namespace *, struct dentry *,
                        struct iattr *);
        int (*getattr) (struct user_namespace *, const struct path *,
                        struct kstat *, u32, unsigned int);
        ssize_t (*listxattr) (struct dentry *, char *, size_t);
        int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
                      u64 len);
        int (*update_time)(struct inode *, struct timespec64 *, int);
        int (*atomic_open)(struct inode *, struct dentry *,
                           struct file *, unsigned open_flag,
                           umode_t create_mode);
        int (*tmpfile) (struct user_namespace *, struct inode *,
                        struct dentry *, umode_t);
        int (*set_acl)(struct user_namespace *, struct inode *,
                       struct posix_acl *, int);
        int (*fileattr_set)(struct user_namespace *mnt_userns,
                            struct dentry *dentry, struct fileattr *fa);
        int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
} ____cacheline_aligned;

static inline ssize_t call_read_iter(struct file *file, struct kiocb *kio,
                                     struct iov_iter *iter)
{
        return file->f_op->read_iter(kio, iter);
}

static inline ssize_t call_write_iter(struct file *file, struct kiocb *kio,
                                      struct iov_iter *iter)
{
        return file->f_op->write_iter(kio, iter);
}

static inline int call_mmap(struct file *file, struct vm_area_struct *vma)
{
        return file->f_op->mmap(file, vma);
}

extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
                                   loff_t, size_t, unsigned int);
extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
                                       struct file *file_out, loff_t pos_out,
                                       size_t len, unsigned int flags);
extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
                                         struct file *file_out, loff_t pos_out,
                                         loff_t *count,
                                         unsigned int remap_flags);
extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
                                  struct file *file_out, loff_t pos_out,
                                  loff_t len, unsigned int remap_flags);
extern loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
                                   struct file *file_out, loff_t pos_out,
                                   loff_t len, unsigned int remap_flags);
extern int vfs_dedupe_file_range(struct file *file,
                                 struct file_dedupe_range *same);
extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
                                        struct file *dst_file, loff_t dst_pos,
                                        loff_t len, unsigned int remap_flags);


struct super_operations {
        struct inode *(*alloc_inode)(struct super_block *sb);
        void (*destroy_inode)(struct inode *);
        void (*free_inode)(struct inode *);

        void (*dirty_inode) (struct inode *, int flags);
        int (*write_inode) (struct inode *, struct writeback_control *wbc);
        int (*drop_inode) (struct inode *);
        void (*evict_inode) (struct inode *);
        void (*put_super) (struct super_block *);
        int (*sync_fs)(struct super_block *sb, int wait);
        int (*freeze_super) (struct super_block *);
        int (*freeze_fs) (struct super_block *);
        int (*thaw_super) (struct super_block *);
        int (*unfreeze_fs) (struct super_block *);
        int (*statfs) (struct dentry *, struct kstatfs *);
        int (*remount_fs) (struct super_block *, int *, char *);
        void (*umount_begin) (struct super_block *);

        int (*show_options)(struct seq_file *, struct dentry *);
        int (*show_devname)(struct seq_file *, struct dentry *);
        int (*show_path)(struct seq_file *, struct dentry *);
        int (*show_stats)(struct seq_file *, struct dentry *);
#ifdef CONFIG_QUOTA
        ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
        ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
        struct dquot **(*get_dquots)(struct inode *);
#endif
        long (*nr_cached_objects)(struct super_block *,
                                  struct shrink_control *);
        long (*free_cached_objects)(struct super_block *,
                                    struct shrink_control *);
};

/*
 * Inode flags - they have no relation to superblock flags now
 */
#define S_SYNC          (1 << 0)  /* Writes are synced at once */
#define S_NOATIME       (1 << 1)  /* Do not update access times */
#define S_APPEND        (1 << 2)  /* Append-only file */
#define S_IMMUTABLE     (1 << 3)  /* Immutable file */
#define S_DEAD          (1 << 4)  /* removed, but still open directory */
#define S_NOQUOTA       (1 << 5)  /* Inode is not counted to quota */
#define S_DIRSYNC       (1 << 6)  /* Directory modifications are synchronous */
#define S_NOCMTIME      (1 << 7)  /* Do not update file c/mtime */
#define S_SWAPFILE      (1 << 8)  /* Do not truncate: swapon got its bmaps */
#define S_PRIVATE       (1 << 9)  /* Inode is fs-internal */
#define S_IMA           (1 << 10) /* Inode has an associated IMA struct */
#define S_AUTOMOUNT     (1 << 11) /* Automount/referral quasi-directory */
#define S_NOSEC         (1 << 12) /* no suid or xattr security attributes */
#ifdef CONFIG_FS_DAX
#define S_DAX           (1 << 13) /* Direct Access, avoiding the page cache */
#else
#define S_DAX           0         /* Make all the DAX code disappear */
#endif
#define S_ENCRYPTED     (1 << 14) /* Encrypted file (using fs/crypto/) */
#define S_CASEFOLD      (1 << 15) /* Casefolded file */
#define S_VERITY        (1 << 16) /* Verity file (using fs/verity/) */
#define S_KERNEL_FILE   (1 << 17) /* File is in use by the kernel (eg. fs/cachefiles) */

/*
 * Note that nosuid etc flags are inode-specific: setting some file-system
 * flags just means all the inodes inherit those flags by default. It might be
 * possible to override it selectively if you really wanted to with some
 * ioctl() that is not currently implemented.
 *
 * Exception: SB_RDONLY is always applied to the entire file system.
 *
 * Unfortunately, it is possible to change a filesystems flags with it mounted
 * with files in use.  This means that all of the inodes will not have their
 * i_flags updated.  Hence, i_flags no longer inherit the superblock mount
 * flags, so these have to be checked separately. -- rmk@arm.uk.linux.org
 */
#define __IS_FLG(inode, flg)    ((inode)->i_sb->s_flags & (flg))

static inline bool sb_rdonly(const struct super_block *sb) { return sb->s_flags & SB_RDONLY; }
#define IS_RDONLY(inode)        sb_rdonly((inode)->i_sb)
#define IS_SYNC(inode)          (__IS_FLG(inode, SB_SYNCHRONOUS) || \
                                        ((inode)->i_flags & S_SYNC))
#define IS_DIRSYNC(inode)       (__IS_FLG(inode, SB_SYNCHRONOUS|SB_DIRSYNC) || \
                                        ((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
#define IS_MANDLOCK(inode)      __IS_FLG(inode, SB_MANDLOCK)
#define IS_NOATIME(inode)       __IS_FLG(inode, SB_RDONLY|SB_NOATIME)
#define IS_I_VERSION(inode)     __IS_FLG(inode, SB_I_VERSION)

#define IS_NOQUOTA(inode)       ((inode)->i_flags & S_NOQUOTA)
#define IS_APPEND(inode)        ((inode)->i_flags & S_APPEND)
#define IS_IMMUTABLE(inode)     ((inode)->i_flags & S_IMMUTABLE)
#define IS_POSIXACL(inode)      __IS_FLG(inode, SB_POSIXACL)

#define IS_DEADDIR(inode)       ((inode)->i_flags & S_DEAD)
#define IS_NOCMTIME(inode)      ((inode)->i_flags & S_NOCMTIME)
#define IS_SWAPFILE(inode)      ((inode)->i_flags & S_SWAPFILE)
#define IS_PRIVATE(inode)       ((inode)->i_flags & S_PRIVATE)
#define IS_IMA(inode)           ((inode)->i_flags & S_IMA)
#define IS_AUTOMOUNT(inode)     ((inode)->i_flags & S_AUTOMOUNT)
#define IS_NOSEC(inode)         ((inode)->i_flags & S_NOSEC)
#define IS_DAX(inode)           ((inode)->i_flags & S_DAX)
#define IS_ENCRYPTED(inode)     ((inode)->i_flags & S_ENCRYPTED)
#define IS_CASEFOLDED(inode)    ((inode)->i_flags & S_CASEFOLD)
#define IS_VERITY(inode)        ((inode)->i_flags & S_VERITY)

#define IS_WHITEOUT(inode)      (S_ISCHR(inode->i_mode) && \
                                 (inode)->i_rdev == WHITEOUT_DEV)

static inline bool HAS_UNMAPPED_ID(struct user_namespace *mnt_userns,
                                   struct inode *inode)
{
        return !uid_valid(i_uid_into_mnt(mnt_userns, inode)) ||
               !gid_valid(i_gid_into_mnt(mnt_userns, inode));
}

static inline int iocb_flags(struct file *file);

static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
{
        *kiocb = (struct kiocb) {
                .ki_filp = filp,
                .ki_flags = iocb_flags(filp),
                .ki_ioprio = get_current_ioprio(),
        };
}

static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
                               struct file *filp)
{
        *kiocb = (struct kiocb) {
                .ki_filp = filp,
                .ki_flags = kiocb_src->ki_flags,
                .ki_ioprio = kiocb_src->ki_ioprio,
                .ki_pos = kiocb_src->ki_pos,
        };
}

/*
 * Inode state bits.  Protected by inode->i_lock
 *
 * Four bits determine the dirty state of the inode: I_DIRTY_SYNC,
 * I_DIRTY_DATASYNC, I_DIRTY_PAGES, and I_DIRTY_TIME.
 *
 * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
 * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
 * various stages of removing an inode.
 *
 * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
 *
 * I_DIRTY_SYNC         Inode is dirty, but doesn't have to be written on
 *                      fdatasync() (unless I_DIRTY_DATASYNC is also set).
 *                      Timestamp updates are the usual cause.
 * I_DIRTY_DATASYNC     Data-related inode changes pending.  We keep track of
 *                      these changes separately from I_DIRTY_SYNC so that we
 *                      don't have to write inode on fdatasync() when only
 *                      e.g. the timestamps have changed.
 * I_DIRTY_PAGES        Inode has dirty pages.  Inode itself may be clean.
 * I_DIRTY_TIME         The inode itself only has dirty timestamps, and the
 *                      lazytime mount option is enabled.  We keep track of this
 *                      separately from I_DIRTY_SYNC in order to implement
 *                      lazytime.  This gets cleared if I_DIRTY_INODE
 *                      (I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) gets set.  I.e.
 *                      either I_DIRTY_TIME *or* I_DIRTY_INODE can be set in
 *                      i_state, but not both.  I_DIRTY_PAGES may still be set.
 * I_NEW                Serves as both a mutex and completion notification.
 *                      New inodes set I_NEW.  If two processes both create
 *                      the same inode, one of them will release its inode and
 *                      wait for I_NEW to be released before returning.
 *                      Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
 *                      also cause waiting on I_NEW, without I_NEW actually
 *                      being set.  find_inode() uses this to prevent returning
 *                      nearly-dead inodes.
 * I_WILL_FREE          Must be set when calling write_inode_now() if i_count
 *                      is zero.  I_FREEING must be set when I_WILL_FREE is
 *                      cleared.
 * I_FREEING            Set when inode is about to be freed but still has dirty
 *                      pages or buffers attached or the inode itself is still
 *                      dirty.
 * I_CLEAR              Added by clear_inode().  In this state the inode is
 *                      clean and can be destroyed.  Inode keeps I_FREEING.
 *
 *                      Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
 *                      prohibited for many purposes.  iget() must wait for
 *                      the inode to be completely released, then create it
 *                      anew.  Other functions will just ignore such inodes,
 *                      if appropriate.  I_NEW is used for waiting.
 *
 * I_SYNC               Writeback of inode is running. The bit is set during
 *                      data writeback, and cleared with a wakeup on the bit
 *                      address once it is done. The bit is also used to pin
 *                      the inode in memory for flusher thread.
 *
 * I_REFERENCED         Marks the inode as recently references on the LRU list.
 *
 * I_DIO_WAKEUP         Never set.  Only used as a key for wait_on_bit().
 *
 * I_WB_SWITCH          Cgroup bdi_writeback switching in progress.  Used to
 *                      synchronize competing switching instances and to tell
 *                      wb stat updates to grab the i_pages lock.  See
 *                      inode_switch_wbs_work_fn() for details.
 *
 * I_OVL_INUSE          Used by overlayfs to get exclusive ownership on upper
 *                      and work dirs among overlayfs mounts.
 *
 * I_CREATING           New object's inode in the middle of setting up.
 *
 * I_DONTCACHE          Evict inode as soon as it is not used anymore.
 *
 * I_SYNC_QUEUED        Inode is queued in b_io or b_more_io writeback lists.
 *                      Used to detect that mark_inode_dirty() should not move
 *                      inode between dirty lists.
 *
 * I_PINNING_FSCACHE_WB Inode is pinning an fscache object for writeback.
 *
 * Q: What is the difference between I_WILL_FREE and I_FREEING?
 */
#define I_DIRTY_SYNC            (1 << 0)
#define I_DIRTY_DATASYNC        (1 << 1)
#define I_DIRTY_PAGES           (1 << 2)
#define __I_NEW                 3
#define I_NEW                   (1 << __I_NEW)
#define I_WILL_FREE             (1 << 4)
#define I_FREEING               (1 << 5)
#define I_CLEAR                 (1 << 6)
#define __I_SYNC                7
#define I_SYNC                  (1 << __I_SYNC)
#define I_REFERENCED            (1 << 8)
#define __I_DIO_WAKEUP          9
#define I_DIO_WAKEUP            (1 << __I_DIO_WAKEUP)
#define I_LINKABLE              (1 << 10)
#define I_DIRTY_TIME            (1 << 11)
#define I_WB_SWITCH             (1 << 13)
#define I_OVL_INUSE             (1 << 14)
#define I_CREATING              (1 << 15)
#define I_DONTCACHE             (1 << 16)
#define I_SYNC_QUEUED           (1 << 17)
#define I_PINNING_FSCACHE_WB    (1 << 18)

#define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
#define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
#define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)

extern void __mark_inode_dirty(struct inode *, int);
static inline void mark_inode_dirty(struct inode *inode)
{
        __mark_inode_dirty(inode, I_DIRTY);
}

static inline void mark_inode_dirty_sync(struct inode *inode)
{
        __mark_inode_dirty(inode, I_DIRTY_SYNC);
}

/*
 * Returns true if the given inode itself only has dirty timestamps (its pages
 * may still be dirty) and isn't currently being allocated or freed.
 * Filesystems should call this if when writing an inode when lazytime is
 * enabled, they want to opportunistically write the timestamps of other inodes
 * located very nearby on-disk, e.g. in the same inode block.  This returns true
 * if the given inode is in need of such an opportunistic update.  Requires
 * i_lock, or at least later re-checking under i_lock.
 */
static inline bool inode_is_dirtytime_only(struct inode *inode)
{
        return (inode->i_state & (I_DIRTY_TIME | I_NEW |
                                  I_FREEING | I_WILL_FREE)) == I_DIRTY_TIME;
}

extern void inc_nlink(struct inode *inode);
extern void drop_nlink(struct inode *inode);
extern void clear_nlink(struct inode *inode);
extern void set_nlink(struct inode *inode, unsigned int nlink);

static inline void inode_inc_link_count(struct inode *inode)
{
        inc_nlink(inode);
        mark_inode_dirty(inode);
}

static inline void inode_dec_link_count(struct inode *inode)
{
        drop_nlink(inode);
        mark_inode_dirty(inode);
}

enum file_time_flags {
        S_ATIME = 1,
        S_MTIME = 2,
        S_CTIME = 4,
        S_VERSION = 8,
};

extern bool atime_needs_update(const struct path *, struct inode *);
extern void touch_atime(const struct path *);
int inode_update_time(struct inode *inode, struct timespec64 *time, int flags);

static inline void file_accessed(struct file *file)
{
        if (!(file->f_flags & O_NOATIME))
                touch_atime(&file->f_path);
}

extern int file_modified(struct file *file);

int sync_inode_metadata(struct inode *inode, int wait);

struct file_system_type {
        const char *name;
        int fs_flags;
#define FS_REQUIRES_DEV         1 
#define FS_BINARY_MOUNTDATA     2
#define FS_HAS_SUBTYPE          4
#define FS_USERNS_MOUNT         8       /* Can be mounted by userns root */
#define FS_DISALLOW_NOTIFY_PERM 16      /* Disable fanotify permission events */
#define FS_ALLOW_IDMAP         32      /* FS has been updated to handle vfs idmappings. */
#define FS_RENAME_DOES_D_MOVE   32768   /* FS will handle d_move() during rename() internally. */
        int (*init_fs_context)(struct fs_context *);
        const struct fs_parameter_spec *parameters;
        struct dentry *(*mount) (struct file_system_type *, int,
                       const char *, void *);
        void (*kill_sb) (struct super_block *);
        struct module *owner;
        struct file_system_type * next;
        struct hlist_head fs_supers;

        struct lock_class_key s_lock_key;
        struct lock_class_key s_umount_key;
        struct lock_class_key s_vfs_rename_key;
        struct lock_class_key s_writers_key[SB_FREEZE_LEVELS];

        struct lock_class_key i_lock_key;
        struct lock_class_key i_mutex_key;
        struct lock_class_key invalidate_lock_key;
        struct lock_class_key i_mutex_dir_key;
};

#define MODULE_ALIAS_FS(NAME) MODULE_ALIAS("fs-" NAME)

extern struct dentry *mount_bdev(struct file_system_type *fs_type,
        int flags, const char *dev_name, void *data,
        int (*fill_super)(struct super_block *, void *, int));
extern struct dentry *mount_single(struct file_system_type *fs_type,
        int flags, void *data,
        int (*fill_super)(struct super_block *, void *, int));
extern struct dentry *mount_nodev(struct file_system_type *fs_type,
        int flags, void *data,
        int (*fill_super)(struct super_block *, void *, int));
extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path);
void generic_shutdown_super(struct super_block *sb);
void kill_block_super(struct super_block *sb);
void kill_anon_super(struct super_block *sb);
void kill_litter_super(struct super_block *sb);
void deactivate_super(struct super_block *sb);
void deactivate_locked_super(struct super_block *sb);
int set_anon_super(struct super_block *s, void *data);
int set_anon_super_fc(struct super_block *s, struct fs_context *fc);
int get_anon_bdev(dev_t *);
void free_anon_bdev(dev_t);
struct super_block *sget_fc(struct fs_context *fc,
                            int (*test)(struct super_block *, struct fs_context *),
                            int (*set)(struct super_block *, struct fs_context *));
struct super_block *sget(struct file_system_type *type,
                        int (*test)(struct super_block *,void *),
                        int (*set)(struct super_block *,void *),
                        int flags, void *data);

/* Alas, no aliases. Too much hassle with bringing module.h everywhere */
#define fops_get(fops) \
        (((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
#define fops_put(fops) \
        do { if (fops) module_put((fops)->owner); } while(0)
/*
 * This one is to be used *ONLY* from ->open() instances.
 * fops must be non-NULL, pinned down *and* module dependencies
 * should be sufficient to pin the caller down as well.
 */
#define replace_fops(f, fops) \
        do {    \
                struct file *__file = (f); \
                fops_put(__file->f_op); \
                BUG_ON(!(__file->f_op = (fops))); \
        } while(0)

extern int register_filesystem(struct file_system_type *);
extern int unregister_filesystem(struct file_system_type *);
extern int vfs_statfs(const struct path *, struct kstatfs *);
extern int user_statfs(const char __user *, struct kstatfs *);
extern int fd_statfs(int, struct kstatfs *);
extern int freeze_super(struct super_block *super);
extern int thaw_super(struct super_block *super);
extern __printf(2, 3)
int super_setup_bdi_name(struct super_block *sb, char *fmt, ...);
extern int super_setup_bdi(struct super_block *sb);

extern int current_umask(void);

extern void ihold(struct inode * inode);
extern void iput(struct inode *);
extern int generic_update_time(struct inode *, struct timespec64 *, int);

/* /sys/fs */
extern struct kobject *fs_kobj;

#define MAX_RW_COUNT (INT_MAX & PAGE_MASK)

#ifdef CONFIG_FILE_LOCKING
static inline int break_lease(struct inode *inode, unsigned int mode)
{
        /*
         * Since this check is lockless, we must ensure that any refcounts
         * taken are done before checking i_flctx->flc_lease. Otherwise, we
         * could end up racing with tasks trying to set a new lease on this
         * file.
         */
        smp_mb();
        if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease))
                return __break_lease(inode, mode, FL_LEASE);
        return 0;
}

static inline int break_deleg(struct inode *inode, unsigned int mode)
{
        /*
         * Since this check is lockless, we must ensure that any refcounts
         * taken are done before checking i_flctx->flc_lease. Otherwise, we
         * could end up racing with tasks trying to set a new lease on this
         * file.
         */
        smp_mb();
        if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease))
                return __break_lease(inode, mode, FL_DELEG);
        return 0;
}

static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
{
        int ret;

        ret = break_deleg(inode, O_WRONLY|O_NONBLOCK);
        if (ret == -EWOULDBLOCK && delegated_inode) {
                *delegated_inode = inode;
                ihold(inode);
        }
        return ret;
}

static inline int break_deleg_wait(struct inode **delegated_inode)
{
        int ret;

        ret = break_deleg(*delegated_inode, O_WRONLY);
        iput(*delegated_inode);
        *delegated_inode = NULL;
        return ret;
}

static inline int break_layout(struct inode *inode, bool wait)
{
        smp_mb();
        if (inode->i_flctx && !list_empty_careful(&inode->i_flctx->flc_lease))
                return __break_lease(inode,
                                wait ? O_WRONLY : O_WRONLY | O_NONBLOCK,
                                FL_LAYOUT);
        return 0;
}

#else /* !CONFIG_FILE_LOCKING */
static inline int break_lease(struct inode *inode, unsigned int mode)
{
        return 0;
}

static inline int break_deleg(struct inode *inode, unsigned int mode)
{
        return 0;
}

static inline int try_break_deleg(struct inode *inode, struct inode **delegated_inode)
{
        return 0;
}

static inline int break_deleg_wait(struct inode **delegated_inode)
{
        BUG();
        return 0;
}

static inline int break_layout(struct inode *inode, bool wait)
{
        return 0;
}

#endif /* CONFIG_FILE_LOCKING */

/* fs/open.c */
struct audit_names;
struct filename {
        const char              *name;  /* pointer to actual string */
        const __user char       *uptr;  /* original userland pointer */
        int                     refcnt;
        struct audit_names      *aname;
        const char              iname[];
};
static_assert(offsetof(struct filename, iname) % sizeof(long) == 0);

static inline struct user_namespace *file_mnt_user_ns(struct file *file)
{
        return mnt_user_ns(file->f_path.mnt);
}

/**
 * is_idmapped_mnt - check whether a mount is mapped
 * @mnt: the mount to check
 *
 * If @mnt has an idmapping attached different from the
 * filesystem's idmapping then @mnt is mapped.
 *
 * Return: true if mount is mapped, false if not.
 */
static inline bool is_idmapped_mnt(const struct vfsmount *mnt)
{
        return mnt_user_ns(mnt) != mnt->mnt_sb->s_user_ns;
}

extern long vfs_truncate(const struct path *, loff_t);
int do_truncate(struct user_namespace *, struct dentry *, loff_t start,
                unsigned int time_attrs, struct file *filp);
extern int vfs_fallocate(struct file *file, int mode, loff_t offset,
                        loff_t len);
extern long do_sys_open(int dfd, const char __user *filename, int flags,
                        umode_t mode);
extern struct file *file_open_name(struct filename *, int, umode_t);
extern struct file *filp_open(const char *, int, umode_t);
extern struct file *file_open_root(const struct path *,
                                   const char *, int, umode_t);
static inline struct file *file_open_root_mnt(struct vfsmount *mnt,
                                   const char *name, int flags, umode_t mode)
{
        return file_open_root(&(struct path){.mnt = mnt, .dentry = mnt->mnt_root},
                              name, flags, mode);
}
extern struct file * dentry_open(const struct path *, int, const struct cred *);
extern struct file *dentry_create(const struct path *path, int flags,
                                  umode_t mode, const struct cred *cred);
extern struct file * open_with_fake_path(const struct path *, int,
                                         struct inode*, const struct cred *);
static inline struct file *file_clone_open(struct file *file)
{
        return dentry_open(&file->f_path, file->f_flags, file->f_cred);
}
extern int filp_close(struct file *, fl_owner_t id);

extern struct filename *getname_flags(const char __user *, int, int *);
extern struct filename *getname_uflags(const char __user *, int);
extern struct filename *getname(const char __user *);
extern struct filename *getname_kernel(const char *);
extern void putname(struct filename *name);

extern int finish_open(struct file *file, struct dentry *dentry,
                        int (*open)(struct inode *, struct file *));
extern int finish_no_open(struct file *file, struct dentry *dentry);

/* fs/dcache.c */
extern void __init vfs_caches_init_early(void);
extern void __init vfs_caches_init(void);

extern struct kmem_cache *names_cachep;

#define __getname()             kmem_cache_alloc(names_cachep, GFP_KERNEL)
#define __putname(name)         kmem_cache_free(names_cachep, (void *)(name))

extern struct super_block *blockdev_superblock;
static inline bool sb_is_blkdev_sb(struct super_block *sb)
{
        return IS_ENABLED(CONFIG_BLOCK) && sb == blockdev_superblock;
}

void emergency_thaw_all(void);
extern int sync_filesystem(struct super_block *);
extern const struct file_operations def_blk_fops;
extern const struct file_operations def_chr_fops;

/* fs/char_dev.c */
#define CHRDEV_MAJOR_MAX 512
/* Marks the bottom of the first segment of free char majors */
#define CHRDEV_MAJOR_DYN_END 234
/* Marks the top and bottom of the second segment of free char majors */
#define CHRDEV_MAJOR_DYN_EXT_START 511
#define CHRDEV_MAJOR_DYN_EXT_END 384

extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
extern int register_chrdev_region(dev_t, unsigned, const char *);
extern int __register_chrdev(unsigned int major, unsigned int baseminor,
                             unsigned int count, const char *name,
                             const struct file_operations *fops);
extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
                                unsigned int count, const char *name);
extern void unregister_chrdev_region(dev_t, unsigned);
extern void chrdev_show(struct seq_file *,off_t);

static inline int register_chrdev(unsigned int major, const char *name,
                                  const struct file_operations *fops)
{
        return __register_chrdev(major, 0, 256, name, fops);
}

static inline void unregister_chrdev(unsigned int major, const char *name)
{
        __unregister_chrdev(major, 0, 256, name);
}

extern void init_special_inode(struct inode *, umode_t, dev_t);

/* Invalid inode operations -- fs/bad_inode.c */
extern void make_bad_inode(struct inode *);
extern bool is_bad_inode(struct inode *);

extern int __must_check file_fdatawait_range(struct file *file, loff_t lstart,
                                                loff_t lend);
extern int __must_check file_check_and_advance_wb_err(struct file *file);
extern int __must_check file_write_and_wait_range(struct file *file,
                                                loff_t start, loff_t end);

static inline int file_write_and_wait(struct file *file)
{
        return file_write_and_wait_range(file, 0, LLONG_MAX);
}

extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
                           int datasync);
extern int vfs_fsync(struct file *file, int datasync);

extern int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
                                unsigned int flags);

/*
 * Sync the bytes written if this was a synchronous write.  Expect ki_pos
 * to already be updated for the write, and will return either the amount
 * of bytes passed in, or an error if syncing the file failed.
 */
static inline ssize_t generic_write_sync(struct kiocb *iocb, ssize_t count)
{
        if (iocb->ki_flags & IOCB_DSYNC) {
                int ret = vfs_fsync_range(iocb->ki_filp,
                                iocb->ki_pos - count, iocb->ki_pos - 1,
                                (iocb->ki_flags & IOCB_SYNC) ? 0 : 1);
                if (ret)
                        return ret;
        }

        return count;
}

extern void emergency_sync(void);
extern void emergency_remount(void);

#ifdef CONFIG_BLOCK
extern int bmap(struct inode *inode, sector_t *block);
#else
static inline int bmap(struct inode *inode,  sector_t *block)
{
        return -EINVAL;
}
#endif

int notify_change(struct user_namespace *, struct dentry *,
                  struct iattr *, struct inode **);
int inode_permission(struct user_namespace *, struct inode *, int);
int generic_permission(struct user_namespace *, struct inode *, int);
static inline int file_permission(struct file *file, int mask)
{
        return inode_permission(file_mnt_user_ns(file),
                                file_inode(file), mask);
}
static inline int path_permission(const struct path *path, int mask)
{
        return inode_permission(mnt_user_ns(path->mnt),
                                d_inode(path->dentry), mask);
}
int __check_sticky(struct user_namespace *mnt_userns, struct inode *dir,
                   struct inode *inode);

static inline bool execute_ok(struct inode *inode)
{
        return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);
}

static inline bool inode_wrong_type(const struct inode *inode, umode_t mode)
{
        return (inode->i_mode ^ mode) & S_IFMT;
}

static inline void file_start_write(struct file *file)
{
        if (!S_ISREG(file_inode(file)->i_mode))
                return;
        sb_start_write(file_inode(file)->i_sb);
}

static inline bool file_start_write_trylock(struct file *file)
{
        if (!S_ISREG(file_inode(file)->i_mode))
                return true;
        return sb_start_write_trylock(file_inode(file)->i_sb);
}

static inline void file_end_write(struct file *file)
{
        if (!S_ISREG(file_inode(file)->i_mode))
                return;
        __sb_end_write(file_inode(file)->i_sb, SB_FREEZE_WRITE);
}

/*
 * This is used for regular files where some users -- especially the
 * currently executed binary in a process, previously handled via
 * VM_DENYWRITE -- cannot handle concurrent write (and maybe mmap
 * read-write shared) accesses.
 *
 * get_write_access() gets write permission for a file.
 * put_write_access() releases this write permission.
 * deny_write_access() denies write access to a file.
 * allow_write_access() re-enables write access to a file.
 *
 * The i_writecount field of an inode can have the following values:
 * 0: no write access, no denied write access
 * < 0: (-i_writecount) users that denied write access to the file.
 * > 0: (i_writecount) users that have write access to the file.
 *
 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
 * except for the cases where we don't hold i_writecount yet. Then we need to
 * use {get,deny}_write_access() - these functions check the sign and refuse
 * to do the change if sign is wrong.
 */
static inline int get_write_access(struct inode *inode)
{
        return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
}
static inline int deny_write_access(struct file *file)
{
        struct inode *inode = file_inode(file);
        return atomic_dec_unless_positive(&inode->i_writecount) ? 0 : -ETXTBSY;
}
static inline void put_write_access(struct inode * inode)
{
        atomic_dec(&inode->i_writecount);
}
static inline void allow_write_access(struct file *file)
{
        if (file)
                atomic_inc(&file_inode(file)->i_writecount);
}
static inline bool inode_is_open_for_write(const struct inode *inode)
{
        return atomic_read(&inode->i_writecount) > 0;
}

#if defined(CONFIG_IMA) || defined(CONFIG_FILE_LOCKING)
static inline void i_readcount_dec(struct inode *inode)
{
        BUG_ON(!atomic_read(&inode->i_readcount));
        atomic_dec(&inode->i_readcount);
}
static inline void i_readcount_inc(struct inode *inode)
{
        atomic_inc(&inode->i_readcount);
}
#else
static inline void i_readcount_dec(struct inode *inode)
{
        return;
}
static inline void i_readcount_inc(struct inode *inode)
{
        return;
}
#endif
extern int do_pipe_flags(int *, int);

extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *);
ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos);
extern ssize_t kernel_write(struct file *, const void *, size_t, loff_t *);
extern ssize_t __kernel_write(struct file *, const void *, size_t, loff_t *);
extern struct file * open_exec(const char *);
 
/* fs/dcache.c -- generic fs support functions */
extern bool is_subdir(struct dentry *, struct dentry *);
extern bool path_is_under(const struct path *, const struct path *);

extern char *file_path(struct file *, char *, int);

#include <linux/err.h>

/* needed for stackable file system support */
extern loff_t default_llseek(struct file *file, loff_t offset, int whence);

extern loff_t vfs_llseek(struct file *file, loff_t offset, int whence);

extern int inode_init_always(struct super_block *, struct inode *);
extern void inode_init_once(struct inode *);
extern void address_space_init_once(struct address_space *mapping);
extern struct inode * igrab(struct inode *);
extern ino_t iunique(struct super_block *, ino_t);
extern int inode_needs_sync(struct inode *inode);
extern int generic_delete_inode(struct inode *inode);
static inline int generic_drop_inode(struct inode *inode)
{
        return !inode->i_nlink || inode_unhashed(inode);
}
extern void d_mark_dontcache(struct inode *inode);

extern struct inode *ilookup5_nowait(struct super_block *sb,
                unsigned long hashval, int (*test)(struct inode *, void *),
                void *data);
extern struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
                int (*test)(struct inode *, void *), void *data);
extern struct inode *ilookup(struct super_block *sb, unsigned long ino);

extern struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
                int (*test)(struct inode *, void *),
                int (*set)(struct inode *, void *),
                void *data);
extern struct inode * iget5_locked(struct super_block *, unsigned long, int (*test)(struct inode *, void *), int (*set)(struct inode *, void *), void *);
extern struct inode * iget_locked(struct super_block *, unsigned long);
extern struct inode *find_inode_nowait(struct super_block *,
                                       unsigned long,
                                       int (*match)(struct inode *,
                                                    unsigned long, void *),
                                       void *data);
extern struct inode *find_inode_rcu(struct super_block *, unsigned long,
                                    int (*)(struct inode *, void *), void *);
extern struct inode *find_inode_by_ino_rcu(struct super_block *, unsigned long);
extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
extern int insert_inode_locked(struct inode *);
#ifdef CONFIG_DEBUG_LOCK_ALLOC
extern void lockdep_annotate_inode_mutex_key(struct inode *inode);
#else
static inline void lockdep_annotate_inode_mutex_key(struct inode *inode) { };
#endif
extern void unlock_new_inode(struct inode *);
extern void discard_new_inode(struct inode *);
extern unsigned int get_next_ino(void);
extern void evict_inodes(struct super_block *sb);
void dump_mapping(const struct address_space *);

/*
 * Userspace may rely on the the inode number being non-zero. For example, glibc
 * simply ignores files with zero i_ino in unlink() and other places.
 *
 * As an additional complication, if userspace was compiled with
 * _FILE_OFFSET_BITS=32 on a 64-bit kernel we'll only end up reading out the
 * lower 32 bits, so we need to check that those aren't zero explicitly. With
 * _FILE_OFFSET_BITS=64, this may cause some harmless false-negatives, but
 * better safe than sorry.
 */
static inline bool is_zero_ino(ino_t ino)
{
        return (u32)ino == 0;
}

extern void __iget(struct inode * inode);
extern void iget_failed(struct inode *);
extern void clear_inode(struct inode *);
extern void __destroy_inode(struct inode *);
extern struct inode *new_inode_pseudo(struct super_block *sb);
extern struct inode *new_inode(struct super_block *sb);
extern void free_inode_nonrcu(struct inode *inode);
extern int should_remove_suid(struct dentry *);
extern int file_remove_privs(struct file *);

/*
 * This must be used for allocating filesystems specific inodes to set
 * up the inode reclaim context correctly.
 */
static inline void *
alloc_inode_sb(struct super_block *sb, struct kmem_cache *cache, gfp_t gfp)
{
        return kmem_cache_alloc_lru(cache, &sb->s_inode_lru, gfp);
}

extern void __insert_inode_hash(struct inode *, unsigned long hashval);
static inline void insert_inode_hash(struct inode *inode)
{
        __insert_inode_hash(inode, inode->i_ino);
}

extern void __remove_inode_hash(struct inode *);
static inline void remove_inode_hash(struct inode *inode)
{
        if (!inode_unhashed(inode) && !hlist_fake(&inode->i_hash))
                __remove_inode_hash(inode);
}

extern void inode_sb_list_add(struct inode *inode);
extern void inode_add_lru(struct inode *inode);

extern int sb_set_blocksize(struct super_block *, int);
extern int sb_min_blocksize(struct super_block *, int);

extern int generic_file_mmap(struct file *, struct vm_area_struct *);
extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
int generic_write_checks_count(struct kiocb *iocb, loff_t *count);
extern int generic_write_check_limits(struct file *file, loff_t pos,
                loff_t *count);
extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *to,
                ssize_t already_read);
extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *);
ssize_t generic_perform_write(struct kiocb *, struct iov_iter *);