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 /* 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;
 struct iomap_ops;
 
 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)
 
 /* File supports async nowait buffered writes */
 #define FMODE_BUF_WASYNC    ((__force fmode_t)0x80000000)
 
 /*
  * 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;
     /*
      * The two anonymous unions wrap structures with the same member.
      *
      * Filesystems raising FS_ALLOW_IDMAP need to use ia_vfs{g,u}id which
      * are a dedicated type requiring the filesystem to use the dedicated
      * helpers. Other filesystem can continue to use ia_{g,u}id until they
      * have been ported.
      *
      * They always contain the same value. In other words FS_ALLOW_IDMAP
      * pass down the same value on idmapped mounts as they would on regular
      * mounts.
      */
     union {
         kuid_t      ia_uid;
         vfsuid_t    ia_vfsuid;
     };
     union {
         kgid_t      ia_gid;
         vfsgid_t    ia_vfsgid;
     };
     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;
     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 */
 };
 
 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 folio to the specified target. If
      * migrate_mode is MIGRATE_ASYNC, it must not block.
      */
     int (*migrate_folio)(struct address_space *, struct folio *dst,
             struct folio *src, enum migrate_mode);
     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   f_llist;
         struct rcu_head     f_rcuhead;
         unsigned int        f_iocb_flags;
     };
     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 */
 #define SB_I_RETIRED    0x00000800  /* superblock shouldn't be reused */
 
 /* 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
  *
  * Note, this will eventually be removed completely in favor of the type-safe
  * i_uid_into_vfsuid().
  *
  * 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 AS_KUIDT(make_vfsuid(mnt_userns, i_user_ns(inode), inode->i_uid));
 }
 
 /**
  * i_uid_into_vfsuid - 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: whe inode's i_uid mapped down according to @mnt_userns.
  * If the inode's i_uid has no mapping INVALID_VFSUID is returned.
  */
 static inline vfsuid_t i_uid_into_vfsuid(struct user_namespace *mnt_userns,
                      const struct inode *inode)
 {
     return make_vfsuid(mnt_userns, i_user_ns(inode), inode->i_uid);
 }
 
 /**
  * i_uid_needs_update - check whether inode's i_uid needs to be updated
  * @mnt_userns: user namespace of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Check whether the $inode's i_uid field needs to be updated taking idmapped
  * mounts into account if the filesystem supports it.
  *
  * Return: true if @inode's i_uid field needs to be updated, false if not.
  */
 static inline bool i_uid_needs_update(struct user_namespace *mnt_userns,
                       const struct iattr *attr,
                       const struct inode *inode)
 {
     return ((attr->ia_valid & ATTR_UID) &&
         !vfsuid_eq(attr->ia_vfsuid,
                i_uid_into_vfsuid(mnt_userns, inode)));
 }
 
 /**
  * i_uid_update - update @inode's i_uid field
  * @mnt_userns: user namespace of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Safely update @inode's i_uid field translating the vfsuid of any idmapped
  * mount into the filesystem kuid.
  */
 static inline void i_uid_update(struct user_namespace *mnt_userns,
                 const struct iattr *attr,
                 struct inode *inode)
 {
     if (attr->ia_valid & ATTR_UID)
         inode->i_uid = from_vfsuid(mnt_userns, i_user_ns(inode),
                        attr->ia_vfsuid);
 }
 
 /**
  * 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
  *
  * Note, this will eventually be removed completely in favor of the type-safe
  * i_gid_into_vfsgid().
  *
  * 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 AS_KGIDT(make_vfsgid(mnt_userns, i_user_ns(inode), inode->i_gid));
 }
 
 /**
  * i_gid_into_vfsgid - 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_VFSGID is returned.
  */
 static inline vfsgid_t i_gid_into_vfsgid(struct user_namespace *mnt_userns,
                      const struct inode *inode)
 {
     return make_vfsgid(mnt_userns, i_user_ns(inode), inode->i_gid);
 }
 
 /**
  * i_gid_needs_update - check whether inode's i_gid needs to be updated
  * @mnt_userns: user namespace of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Check whether the $inode's i_gid field needs to be updated taking idmapped
  * mounts into account if the filesystem supports it.
  *
  * Return: true if @inode's i_gid field needs to be updated, false if not.
  */
 static inline bool i_gid_needs_update(struct user_namespace *mnt_userns,
                       const struct iattr *attr,
                       const struct inode *inode)
 {
     return ((attr->ia_valid & ATTR_GID) &&
         !vfsgid_eq(attr->ia_vfsgid,
                i_gid_into_vfsgid(mnt_userns, inode)));
 }
 
 /**
  * i_gid_update - update @inode's i_gid field
  * @mnt_userns: user namespace of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Safely update @inode's i_gid field translating the vfsgid of any idmapped
  * mount into the filesystem kgid.
  */
 static inline void i_gid_update(struct user_namespace *mnt_userns,
                 const struct iattr *attr,
                 struct inode *inode)
 {
     if (attr->ia_valid & ATTR_GID)
         inode->i_gid = from_vfsgid(mnt_userns, i_user_ns(inode),
                        attr->ia_vfsgid);
 }
 
 /**
  * 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);
 umode_t mode_strip_sgid(struct user_namespace *mnt_userns,
             const struct inode *dir, umode_t mode);
 
 /*
  * 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);
 int __generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
                     struct file *file_out, loff_t pos_out,
                     loff_t *len, unsigned int remap_flags,
                     const struct iomap_ops *dax_read_ops);
 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 !vfsuid_valid(i_uid_into_vfsuid(mnt_userns, inode)) ||
            !vfsgid_valid(i_gid_into_vfsgid(mnt_userns, inode));
 }
 
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
     *kiocb = (struct kiocb) {
         .ki_filp = filp,
         .ki_flags = filp->f_iocb_flags,
         .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 kiocb_modified(struct kiocb *iocb);
 
 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 retire_super(struct super_block *sb);
 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);
 
 static inline bool iocb_is_dsync(const struct kiocb *iocb)
 {
     return (iocb->ki_flags & IOCB_DSYNC) ||
         IS_SYNC(iocb->ki_filp->f_mapping->host);
 }
 
 /*
  * 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_is_dsync(iocb)) {
         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 *);
 
 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
         rwf_t flags);
 ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
         rwf_t flags);
 ssize_t vfs_iocb_iter_read(struct file *file, struct kiocb *iocb,
                struct iov_iter *iter);
 ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
                 struct iov_iter *iter);
 
 /* fs/splice.c */
 extern ssize_t generic_file_splice_read(struct file *, loff_t *,
         struct pipe_inode_info *, size_t, unsigned int);
 extern ssize_t iter_file_splice_write(struct pipe_inode_info *,
         struct file *, loff_t *, size_t, unsigned int);
 extern ssize_t generic_splice_sendpage(struct pipe_inode_info *pipe,
         struct file *out, loff_t *, size_t len, unsigned int flags);
 extern long do_splice_direct(struct file *in, loff_t *ppos, struct file *out,
         loff_t *opos, size_t len, unsigned int flags);
 
 
 extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
 extern loff_t noop_llseek(struct file *file, loff_t offset, int whence);
 #define no_llseek NULL
 extern loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize);
 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int whence);
 extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
         int whence, loff_t maxsize, loff_t eof);
 extern loff_t fixed_size_llseek(struct file *file, loff_t offset,
         int whence, loff_t size);
 extern loff_t no_seek_end_llseek_size(struct file *, loff_t, int, loff_t);
 extern loff_t no_seek_end_llseek(struct file *, loff_t, int);
 int rw_verify_area(int, struct file *, const loff_t *, size_t);
 extern int generic_file_open(struct inode * inode, struct file * filp);
 extern int nonseekable_open(struct inode * inode, struct file * filp);
 extern int stream_open(struct inode * inode, struct file * filp);
 
 #ifdef CONFIG_BLOCK
 typedef void (dio_submit_t)(struct bio *bio, struct inode *inode,
                 loff_t file_offset);
 
 enum {
     /* need locking between buffered and direct access */
     DIO_LOCKING = 0x01,
 
     /* filesystem does not support filling holes */
     DIO_SKIP_HOLES  = 0x02,
 };
 
 ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
                  struct block_device *bdev, struct iov_iter *iter,
                  get_block_t get_block,
                  dio_iodone_t end_io, dio_submit_t submit_io,
                  int flags);
 
 static inline ssize_t blockdev_direct_IO(struct kiocb *iocb,
                      struct inode *inode,
                      struct iov_iter *iter,
                      get_block_t get_block)
 {
     return __blockdev_direct_IO(iocb, inode, inode->i_sb->s_bdev, iter,
             get_block, NULL, NULL, DIO_LOCKING | DIO_SKIP_HOLES);
 }
 #endif
 
 void inode_dio_wait(struct inode *inode);
 
 /**
  * inode_dio_begin - signal start of a direct I/O requests
  * @inode: inode the direct I/O happens on
  *
  * This is called once we've finished processing a direct I/O request,
  * and is used to wake up callers waiting for direct I/O to be quiesced.
  */
 static inline void inode_dio_begin(struct inode *inode)
 {
     atomic_inc(&inode->i_dio_count);
 }
 
 /**
  * inode_dio_end - signal finish of a direct I/O requests
  * @inode: inode the direct I/O happens on
  *
  * This is called once we've finished processing a direct I/O request,
  * and is used to wake up callers waiting for direct I/O to be quiesced.
  */
 static inline void inode_dio_end(struct inode *inode)
 {
     if (atomic_dec_and_test(&inode->i_dio_count))
         wake_up_bit(&inode->i_state, __I_DIO_WAKEUP);
 }
 
 /*
  * Warn about a page cache invalidation failure diring a direct I/O write.
  */
 void dio_warn_stale_pagecache(struct file *filp);
 
 extern void inode_set_flags(struct inode *inode, unsigned int flags,
                 unsigned int mask);
 
 extern const struct file_operations generic_ro_fops;
 
 #define special_file(m) (S_ISCHR(m)||S_ISBLK(m)||S_ISFIFO(m)||S_ISSOCK(m))
 
 extern int readlink_copy(char __user *, int, const char *);
 extern int page_readlink(struct dentry *, char __user *, int);
 extern const char *page_get_link(struct dentry *, struct inode *,
                  struct delayed_call *);
 extern void page_put_link(void *);
 extern int page_symlink(struct inode *inode, const char *symname, int len);
 extern const struct inode_operations page_symlink_inode_operations;
 extern void kfree_link(void *);
 void generic_fillattr(struct user_namespace *, struct inode *, struct kstat *);
 void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
 extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
 extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
 void __inode_add_bytes(struct inode *inode, loff_t bytes);
 void inode_add_bytes(struct inode *inode, loff_t bytes);
 void __inode_sub_bytes(struct inode *inode, loff_t bytes);
 void inode_sub_bytes(struct inode *inode, loff_t bytes);
 static inline loff_t __inode_get_bytes(struct inode *inode)
 {
     return (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
 }
 loff_t inode_get_bytes(struct inode *inode);
 void inode_set_bytes(struct inode *inode, loff_t bytes);
 const char *simple_get_link(struct dentry *, struct inode *,
                 struct delayed_call *);
 extern const struct inode_operations simple_symlink_inode_operations;
 
 extern int iterate_dir(struct file *, struct dir_context *);
 
 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
         int flags);
 int vfs_fstat(int fd, struct kstat *stat);
 
 static inline int vfs_stat(const char __user *filename, struct kstat *stat)
 {
     return vfs_fstatat(AT_FDCWD, filename, stat, 0);
 }
 static inline int vfs_lstat(const char __user *name, struct kstat *stat)
 {
     return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
 }
 
 extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
 extern int vfs_readlink(struct dentry *, char __user *, int);
 
 extern struct file_system_type *get_filesystem(struct file_system_type *fs);
 extern void put_filesystem(struct file_system_type *fs);
 extern struct file_system_type *get_fs_type(const char *name);
 extern struct super_block *get_super(struct block_device *);
 extern struct super_block *get_active_super(struct block_device *bdev);
 extern void drop_super(struct super_block *sb);
 extern void drop_super_exclusive(struct super_block *sb);
 extern void iterate_supers(void (*)(struct super_block *, void *), void *);
 extern void iterate_supers_type(struct file_system_type *,
                     void (*)(struct super_block *, void *), void *);
 
 extern int dcache_dir_open(struct inode *, struct file *);
 extern int dcache_dir_close(struct inode *, struct file *);
 extern loff_t dcache_dir_lseek(struct file *, loff_t, int);
 extern int dcache_readdir(struct file *, struct dir_context *);
 extern int simple_setattr(struct user_namespace *, struct dentry *,
               struct iattr *);
 extern int simple_getattr(struct user_namespace *, const struct path *,
               struct kstat *, u32, unsigned int);
 extern int simple_statfs(struct dentry *, struct kstatfs *);
 extern int simple_open(struct inode *inode, struct file *file);
 extern int simple_link(struct dentry *, struct inode *, struct dentry *);
 extern int simple_unlink(struct inode *, struct dentry *);
 extern int simple_rmdir(struct inode *, struct dentry *);
 extern int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
                   struct inode *new_dir, struct dentry *new_dentry);
 extern int simple_rename(struct user_namespace *, struct inode *,
              struct dentry *, struct inode *, struct dentry *,
              unsigned int);
 extern void simple_recursive_removal(struct dentry *,
                               void (*callback)(struct dentry *));
 extern int noop_fsync(struct file *, loff_t, loff_t, int);
 extern ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
 extern int simple_empty(struct dentry *);
 extern int simple_write_begin(struct file *file, struct address_space *mapping,
             loff_t pos, unsigned len,
             struct page **pagep, void **fsdata);
 extern const struct address_space_operations ram_aops;
 extern int always_delete_dentry(const struct dentry *);
 extern struct inode *alloc_anon_inode(struct super_block *);
 extern int simple_nosetlease(struct file *, long, struct file_lock **, void **);
 extern const struct dentry_operations simple_dentry_operations;
 
 extern struct dentry *simple_lookup(struct inode *, struct dentry *, unsigned int flags);
 extern ssize_t generic_read_dir(struct file *, char __user *, size_t, loff_t *);
 extern const struct file_operations simple_dir_operations;
 extern const struct inode_operations simple_dir_inode_operations;
 extern void make_empty_dir_inode(struct inode *inode);
 extern bool is_empty_dir_inode(struct inode *inode);
 struct tree_descr { const char *name; const struct file_operations *ops; int mode; };
 struct dentry *d_alloc_name(struct dentry *, const char *);
 extern int simple_fill_super(struct super_block *, unsigned long,
                  const struct tree_descr *);
 extern int simple_pin_fs(struct file_system_type *, struct vfsmount **mount, int *count);
 extern void simple_release_fs(struct vfsmount **mount, int *count);
 
 extern ssize_t simple_read_from_buffer(void __user *to, size_t count,
             loff_t *ppos, const void *from, size_t available);
 extern ssize_t simple_write_to_buffer(void *to, size_t available, loff_t *ppos,
         const void __user *from, size_t count);
 
 extern int __generic_file_fsync(struct file *, loff_t, loff_t, int);
 extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
 
 extern int generic_check_addressable(unsigned, u64);
 
 extern void generic_set_encrypted_ci_d_ops(struct dentry *dentry);
 
 int may_setattr(struct user_namespace *mnt_userns, struct inode *inode,
         unsigned int ia_valid);
 int setattr_prepare(struct user_namespace *, struct dentry *, struct iattr *);
 extern int inode_newsize_ok(const struct inode *, loff_t offset);
 void setattr_copy(struct user_namespace *, struct inode *inode,
           const struct iattr *attr);
 
 extern int file_update_time(struct file *file);
 
 static inline bool vma_is_dax(const struct vm_area_struct *vma)
 {
     return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
 }
 
 static inline bool vma_is_fsdax(struct vm_area_struct *vma)
 {
     struct inode *inode;
 
     if (!IS_ENABLED(CONFIG_FS_DAX) || !vma->vm_file)
         return false;
     if (!vma_is_dax(vma))
         return false;
     inode = file_inode(vma->vm_file);
     if (S_ISCHR(inode->i_mode))
         return false; /* device-dax */
     return true;
 }
 
 static inline int iocb_flags(struct file *file)
 {
     int res = 0;
     if (file->f_flags & O_APPEND)
         res |= IOCB_APPEND;
     if (file->f_flags & O_DIRECT)
         res |= IOCB_DIRECT;
     if (file->f_flags & O_DSYNC)
         res |= IOCB_DSYNC;
     if (file->f_flags & __O_SYNC)
         res |= IOCB_SYNC;
     return res;
 }
 
 static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags)
 {
     int kiocb_flags = 0;
 
     /* make sure there's no overlap between RWF and private IOCB flags */
     BUILD_BUG_ON((__force int) RWF_SUPPORTED & IOCB_EVENTFD);
 
     if (!flags)
         return 0;
     if (unlikely(flags & ~RWF_SUPPORTED))
         return -EOPNOTSUPP;
 
     if (flags & RWF_NOWAIT) {
         if (!(ki->ki_filp->f_mode & FMODE_NOWAIT))
             return -EOPNOTSUPP;
         kiocb_flags |= IOCB_NOIO;
     }
     kiocb_flags |= (__force int) (flags & RWF_SUPPORTED);
     if (flags & RWF_SYNC)
         kiocb_flags |= IOCB_DSYNC;
 
     ki->ki_flags |= kiocb_flags;
     return 0;
 }
 
 static inline ino_t parent_ino(struct dentry *dentry)
 {
     ino_t res;
 
     /*
      * Don't strictly need d_lock here? If the parent ino could change
      * then surely we'd have a deeper race in the caller?
      */
     spin_lock(&dentry->d_lock);
     res = dentry->d_parent->d_inode->i_ino;
     spin_unlock(&dentry->d_lock);
     return res;
 }
 
 /* Transaction based IO helpers */
 
 /*
  * An argresp is stored in an allocated page and holds the
  * size of the argument or response, along with its content
  */
 struct simple_transaction_argresp {
     ssize_t size;
     char data[];
 };
 
 #define SIMPLE_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct simple_transaction_argresp))
 
 char *simple_transaction_get(struct file *file, const char __user *buf,
                 size_t size);
 ssize_t simple_transaction_read(struct file *file, char __user *buf,
                 size_t size, loff_t *pos);
 int simple_transaction_release(struct inode *inode, struct file *file);
 
 void simple_transaction_set(struct file *file, size_t n);
 
 /*
  * simple attribute files
  *
  * These attributes behave similar to those in sysfs:
  *
  * Writing to an attribute immediately sets a value, an open file can be
  * written to multiple times.
  *
  * Reading from an attribute creates a buffer from the value that might get
  * read with multiple read calls. When the attribute has been read
  * completely, no further read calls are possible until the file is opened
  * again.
  *
  * All attributes contain a text representation of a numeric value
  * that are accessed with the get() and set() functions.
  */
 #define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)        \
 static int __fops ## _open(struct inode *inode, struct file *file)  \
 {                                   \
     __simple_attr_check_format(__fmt, 0ull);            \
     return simple_attr_open(inode, file, __get, __set, __fmt);  \
 }                                   \
 static const struct file_operations __fops = {              \
     .owner   = THIS_MODULE,                     \
     .open    = __fops ## _open,                 \
     .release = simple_attr_release,                 \
     .read    = simple_attr_read,                    \
     .write   = simple_attr_write,                   \
     .llseek  = generic_file_llseek,                 \
 }
 
 static inline __printf(1, 2)
 void __simple_attr_check_format(const char *fmt, ...)
 {
     /* don't do anything, just let the compiler check the arguments; */
 }
 
 int simple_attr_open(struct inode *inode, struct file *file,
              int (*get)(void *, u64 *), int (*set)(void *, u64),
              const char *fmt);
 int simple_attr_release(struct inode *inode, struct file *file);
 ssize_t simple_attr_read(struct file *file, char __user *buf,
              size_t len, loff_t *ppos);
 ssize_t simple_attr_write(struct file *file, const char __user *buf,
               size_t len, loff_t *ppos);
 
 struct ctl_table;
 int __init list_bdev_fs_names(char *buf, size_t size);
 
 #define __FMODE_EXEC        ((__force int) FMODE_EXEC)
 #define __FMODE_NONOTIFY    ((__force int) FMODE_NONOTIFY)
 
 #define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
 #define OPEN_FMODE(flag) ((__force fmode_t)(((flag + 1) & O_ACCMODE) | \
                         (flag & __FMODE_NONOTIFY)))
 
 static inline bool is_sxid(umode_t mode)
 {
     return (mode & S_ISUID) || ((mode & S_ISGID) && (mode & S_IXGRP));
 }
 
 static inline int check_sticky(struct user_namespace *mnt_userns,
                    struct inode *dir, struct inode *inode)
 {
     if (!(dir->i_mode & S_ISVTX))
         return 0;
 
     return __check_sticky(mnt_userns, dir, inode);
 }
 
 static inline void inode_has_no_xattr(struct inode *inode)
 {
     if (!is_sxid(inode->i_mode) && (inode->i_sb->s_flags & SB_NOSEC))
         inode->i_flags |= S_NOSEC;
 }
 
 static inline bool is_root_inode(struct inode *inode)
 {
     return inode == inode->i_sb->s_root->d_inode;
 }
 
 static inline bool dir_emit(struct dir_context *ctx,
                 const char *name, int namelen,
                 u64 ino, unsigned type)
 {
     return ctx->actor(ctx, name, namelen, ctx->pos, ino, type) == 0;
 }
 static inline bool dir_emit_dot(struct file *file, struct dir_context *ctx)
 {
     return ctx->actor(ctx, ".", 1, ctx->pos,
               file->f_path.dentry->d_inode->i_ino, DT_DIR) == 0;
 }
 static inline bool dir_emit_dotdot(struct file *file, struct dir_context *ctx)
 {
     return ctx->actor(ctx, "..", 2, ctx->pos,
               parent_ino(file->f_path.dentry), DT_DIR) == 0;
 }
 static inline bool dir_emit_dots(struct file *file, struct dir_context *ctx)
 {
     if (ctx->pos == 0) {
         if (!dir_emit_dot(file, ctx))
             return false;
         ctx->pos = 1;
     }
     if (ctx->pos == 1) {
         if (!dir_emit_dotdot(file, ctx))
             return false;
         ctx->pos = 2;
     }
     return true;
 }
 static inline bool dir_relax(struct inode *inode)
 {
     inode_unlock(inode);
     inode_lock(inode);
     return !IS_DEADDIR(inode);
 }
 
 static inline bool dir_relax_shared(struct inode *inode)
 {
     inode_unlock_shared(inode);
     inode_lock_shared(inode);
     return !IS_DEADDIR(inode);
 }
 
 extern bool path_noexec(const struct path *path);
 extern void inode_nohighmem(struct inode *inode);
 
 /* mm/fadvise.c */
 extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len,
                int advice);
 extern int generic_fadvise(struct file *file, loff_t offset, loff_t len,
                int advice);
 
 #endif /* _LINUX_FS_H */