text: /* 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/fiemap.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 <asm/byteorder.h>
  #include <uapi/linux/fs.h>
  
  struct backing_dev_info;
  struct bdi_writeback;
  struct bio;
  struct export_operations;
  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_description;
  
  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 struct files_stat_struct files_stat;
  extern unsigned long get_max_files(void);
  extern unsigned int sysctl_nr_open;
  extern struct inodes_stat_t inodes_stat;
  extern int leases_enable, lease_break_time;
  extern int sysctl_protected_symlinks;
  extern int sysctl_protected_hardlinks;
  extern int sysctl_protected_fifos;
  extern int sysctl_protected_regular;
  
  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/kmem): 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 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)
  
  /*
   * Flag for rw_copy_check_uvector and compat_rw_copy_check_uvector
   * that indicates that they should check the contents of the iovec are
   * valid, but not check the memory that the iovec elements
   * points too.
   */
  #define CHECK_IOVEC_ONLY -1
  
  /*
   * Attribute flags.  These should be or-ed together to figure out what
   * has been changed!
   */
  #define ATTR_MODE	(1 << 0)
  #define ATTR_UID	(1 << 1)
  #define ATTR_GID	(1 << 2)
  #define ATTR_SIZE	(1 << 3)
  #define ATTR_ATIME	(1 << 4)
  #define ATTR_MTIME	(1 << 5)
  #define ATTR_CTIME	(1 << 6)
  #define ATTR_ATIME_SET	(1 << 7)
  #define ATTR_MTIME_SET	(1 << 8)
  #define ATTR_FORCE	(1 << 9) /* Not a change, but a change it */
  #define ATTR_KILL_SUID	(1 << 11)
  #define ATTR_KILL_SGID	(1 << 12)
  #define ATTR_FILE	(1 << 13)
  #define ATTR_KILL_PRIV	(1 << 14)
  #define ATTR_OPEN	(1 << 15) /* Truncating from open(O_TRUNC) */
  #define ATTR_TIMES_SET	(1 << 16)
  #define ATTR_TOUCH	(1 << 17)
  
  /*
   * Whiteout is represented by a char device.  The following constants define the
   * mode and device number to use.
   */
  #define WHITEOUT_MODE 0
  #define WHITEOUT_DEV 0
  
  /*
   * This is the Inode Attributes structure, used for notify_change().  It
   * uses the above definitions as flags, to know which values have changed.
   * Also, in this manner, a Filesystem can look at only the values it cares
   * about.  Basically, these are the attributes that the VFS layer can
   * request to change from the FS layer.
   *
   * Derek Atkins <warlord@MIT.EDU> 94-10-20
   */
  struct iattr {
  	unsigned int	ia_valid;
  	umode_t		ia_mode;
  	kuid_t		ia_uid;
  	kgid_t		ia_gid;
  	loff_t		ia_size;
  	struct timespec64 ia_atime;
  	struct timespec64 ia_mtime;
  	struct timespec64 ia_ctime;
  
  	/*
  	 * Not an attribute, but an auxiliary info for filesystems wanting to
  	 * implement an ftruncate() like method.  NOTE: filesystem should
  	 * check for (ia_valid & ATTR_FILE), and not for (ia_file != NULL).
  	 */
  	struct file	*ia_file;
  };
  
  /*
   * Includes for diskquotas.
   */
  #include <linux/quota.h>
  
  /*
   * Maximum number of layers of fs stack.  Needs to be limited to
   * prevent kernel stack overflow
   */
  #define FILESYSTEM_MAX_STACK_DEPTH 2
  
  /** 
   * enum positive_aop_returns - aop return codes with specific semantics
   *
   * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has
   * 			    completed, that the page is still locked, and
   * 			    should be considered active.  The VM uses this hint
   * 			    to return the page to the active list -- it won't
   * 			    be a candidate for writeback again in the near
   * 			    future.  Other callers must be careful to unlock
   * 			    the page if they get this return.  Returned by
   * 			    writepage(); 
   *
   * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has
   *  			unlocked it and the page might have been truncated.
   *  			The caller should back up to acquiring a new page and
   *  			trying again.  The aop will be taking reasonable
   *  			precautions not to livelock.  If the caller held a page
   *  			reference, it should drop it before retrying.  Returned
   *  			by readpage().
   *
   * 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,
  };
  
  #define AOP_FLAG_CONT_EXPAND		0x0001 /* called from cont_expand */
  #define AOP_FLAG_NOFS			0x0002 /* used by filesystem to direct
  						* helper code (eg buffer layer)
  						* to clear GFP_FS from alloc */
  
  /*
   * oh the beauties of C type declarations.
   */
  struct page;
  struct address_space;
  struct writeback_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,
  };
  
  #define IOCB_EVENTFD		(1 << 0)
  #define IOCB_APPEND		(1 << 1)
  #define IOCB_DIRECT		(1 << 2)
  #define IOCB_HIPRI		(1 << 3)
  #define IOCB_DSYNC		(1 << 4)
  #define IOCB_SYNC		(1 << 5)
  #define IOCB_WRITE		(1 << 6)
  #define IOCB_NOWAIT		(1 << 7)
  
  struct kiocb {
  	struct file		*ki_filp;
  
  	/* The 'ki_filp' pointer is shared in a union for aio */
  	randomized_struct_fields_start
  
  	loff_t			ki_pos;
  	void (*ki_complete)(struct kiocb *iocb, long ret, long ret2);
  	void			*private;
  	int			ki_flags;
  	u16			ki_hint;
  	u16			ki_ioprio; /* See linux/ioprio.h */
  	unsigned int		ki_cookie; /* for ->iopoll */
  
  	randomized_struct_fields_end
  };
  
  static inline bool is_sync_kiocb(struct kiocb *kiocb)
  {
  	return kiocb->ki_complete == NULL;
  }
  
  /*
   * "descriptor" for what we're up to with a read.
   * This allows us to use the same read code yet
   * have multiple different users of the data that
   * we read from a file.
   *
   * The simplest case just copies the data to user
   * mode.
   */
  typedef struct {
  	size_t written;
  	size_t count;
  	union {
  		char __user *buf;
  		void *data;
  	} arg;
  	int error;
  } read_descriptor_t;
  
  typedef int (*read_actor_t)(read_descriptor_t *, struct page *,
  		unsigned long, unsigned long);
  
  struct address_space_operations {
  	int (*writepage)(struct page *page, struct writeback_control *wbc);
  	int (*readpage)(struct file *, struct page *);
  
  	/* Write back some dirty pages from this mapping. */
  	int (*writepages)(struct address_space *, struct writeback_control *);
  
  	/* Set a page dirty.  Return true if this dirtied it */
  	int (*set_page_dirty)(struct page *page);
  
  	/*
  	 * Reads in the requested pages. Unlike ->readpage(), this is
  	 * PURELY used for read-ahead!.
  	 */
  	int (*readpages)(struct file *filp, struct address_space *mapping,
  			struct list_head *pages, unsigned nr_pages);
  
  	int (*write_begin)(struct file *, struct address_space *mapping,
  				loff_t pos, unsigned len, unsigned flags,
  				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 (*invalidatepage) (struct page *, unsigned int, unsigned int);
  	int (*releasepage) (struct page *, gfp_t);
  	void (*freepage)(struct page *);
  	ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
  	/*
  	 * migrate the contents of a page to the specified target. If
  	 * migrate_mode is MIGRATE_ASYNC, it must not block.
  	 */
  	int (*migratepage) (struct address_space *,
  			struct page *, struct page *, enum migrate_mode);
  	bool (*isolate_page)(struct page *, isolate_mode_t);
  	void (*putback_page)(struct page *);
  	int (*launder_page) (struct page *);
  	int (*is_partially_uptodate) (struct page *, unsigned long,
  					unsigned long);
  	void (*is_dirty_writeback) (struct page *, bool *, bool *);
  	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);
  };
  
  extern const struct address_space_operations empty_aops;
  
  /*
   * pagecache_write_begin/pagecache_write_end must be used by general code
   * to write into the pagecache.
   */
  int pagecache_write_begin(struct file *, struct address_space *mapping,
  				loff_t pos, unsigned len, unsigned flags,
  				struct page **pagep, void **fsdata);
  
  int pagecache_write_end(struct file *, struct address_space *mapping,
  				loff_t pos, unsigned len, unsigned copied,
  				struct page *page, void *fsdata);
  
  /**
   * struct address_space - Contents of a cacheable, mappable object.
   * @host: Owner, either the inode or the block_device.
   * @i_pages: Cached pages.
   * @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.
   * @nrexceptional: Shadow or DAX 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;
  	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;
  	unsigned long		nrexceptional;
  	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.
  	 */
  struct request_queue;
  
  struct block_device {
  	dev_t			bd_dev;  /* not a kdev_t - it's a search key */
  	int			bd_openers;
  	struct inode *		bd_inode;	/* will die */
  	struct super_block *	bd_super;
  	struct mutex		bd_mutex;	/* open/close mutex */
  	void *			bd_claiming;
  	void *			bd_holder;
  	int			bd_holders;
  	bool			bd_write_holder;
  #ifdef CONFIG_SYSFS
  	struct list_head	bd_holder_disks;
  #endif
  	struct block_device *	bd_contains;
  	unsigned		bd_block_size;
  	u8			bd_partno;
  	struct hd_struct *	bd_part;
  	/* number of times partitions within this device have been opened. */
  	unsigned		bd_part_count;
  	int			bd_invalidated;
  	struct gendisk *	bd_disk;
  	struct request_queue *  bd_queue;
  	struct backing_dev_info *bd_bdi;
  	struct list_head	bd_list;
  	/*
  	 * Private data.  You must have bd_claim'ed the block_device
  	 * to use this.  NOTE:  bd_claim allows an owner to claim
  	 * the same device multiple times, the owner must take special
  	 * care to not mess up bd_private for that case.
  	 */
  	unsigned long		bd_private;
  
  	/* The counter of freeze processes */
  	int			bd_fsfreeze_count;
  	/* Mutex for freeze */
  	struct mutex		bd_fsfreeze_mutex;
  } __randomize_layout;
  
  /* 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 void i_mmap_unlock_write(struct address_space *mapping)
  {
  	up_write(&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);
  }
  
  /*
   * 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_pgoff
   * 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))
  #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;
  	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 block_device	*i_bdev;
  		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);
  }
  
  void lock_two_nondirectories(struct inode *, struct inode*);
  void unlock_two_nondirectories(struct inode *, struct inode*);
  
  /*
   * 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_PREEMPT)
  	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_PREEMPT)
  	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);
  }
  
  extern struct block_device *I_BDEV(struct inode *inode);
  
  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 */
  };
  
  /*
   * Track a single file's readahead state
   */
  struct file_ra_state {
  	pgoff_t start;			/* where readahead started */
  	unsigned int size;		/* # of readahead pages */
  	unsigned int async_size;	/* do asynchronous readahead when
  					   there are only # of pages ahead */
  
  	unsigned int ra_pages;		/* Maximum readahead window */
  	unsigned int mmap_miss;		/* Cache miss stat for mmap accesses */
  	loff_t prev_pos;		/* Cache last read() position */
  };
  
  /*
   * Check if @index falls in the readahead windows.
   */
  static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
  {
  	return (index >= ra->start &&
  		index <  ra->start + ra->size);
  }
  
  struct file {
  	union {
  		struct llist_node	fu_llist;
  		struct rcu_head 	fu_rcuhead;
  	} f_u;
  	struct path		f_path;
  	struct inode		*f_inode;	/* cached value */
  	const struct file_operations	*f_op;
  
  	/*
  	 * Protects f_ep_links, f_flags.
  	 * Must not be taken from IRQ context.
  	 */
  	spinlock_t		f_lock;
  	enum rw_hint		f_write_hint;
  	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 list_head	f_ep_links;
  	struct list_head	f_tfile_llink;
  #endif /* #ifdef CONFIG_EPOLL */
  	struct address_space	*f_mapping;
  	errseq_t		f_wb_err;
  } __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[0];
  };
  
  static inline struct file *get_file(struct file *f)
  {
  	atomic_long_inc(&f->f_count);
  	return f;
  }
  #define get_file_rcu_many(x, cnt)	\
  	atomic_long_add_unless(&(x)->f_count, (cnt), 0)
  #define get_file_rcu(x) get_file_rcu_many((x), 1)
  #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_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 {
  	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 **);
  };
  
  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);
  #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 *user)
  {
  	return -EINVAL;
  }
  
  static inline int fcntl_setlk64(unsigned int fd, struct file *file,
  				unsigned int cmd, struct flock64 __user *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) {}
  #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_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)
  
  /*
   *	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_MULTIROOT	0x00000008	/* Multiple roots to the dentry tree */
  
  /* 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
  
  /* 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;	/* for get_super_thawed() */
  	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
  	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 */
  
  	/*
  	 * Saved pool identifier for cleancache (-1 means none)
  	 */
  	int cleancache_poolid;
  
  	struct shrinker s_shrink;	/* per-sb shrinker handle */
  
  	/* Number of inodes with nlink == 0 but still referenced */
  	atomic_long_t s_remove_count;
  
  	/* Pending fsnotify inode refs */
  	atomic_long_t s_fsnotify_inode_refs;
  
  	/* Being remounted read-only */
  	int s_readonly_remount;
  
  	/* 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;
  
  /* 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(inode->i_sb->s_user_ns, inode->i_uid);
  }
  
  static inline gid_t i_gid_read(const struct inode *inode)
  {
  	return from_kgid(inode->i_sb->s_user_ns, inode->i_gid);
  }
  
  static inline void i_uid_write(struct inode *inode, uid_t uid)
  {
  	inode->i_uid = make_kuid(inode->i_sb->s_user_ns, uid);
  }
  
  static inline void i_gid_write(struct inode *inode, gid_t gid)
  {
  	inode->i_gid = make_kgid(inode->i_sb->s_user_ns, gid);
  }
  
  extern struct timespec64 timespec64_trunc(struct timespec64 t, unsigned gran);
  extern struct timespec64 current_time(struct inode *inode);
  
  /*
   * Snapshotting support.
   */
  
  void __sb_end_write(struct super_block *sb, int level);
  int __sb_start_write(struct super_block *sb, int level, bool wait);
  
  #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_)
  
  /**
   * 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, true);
  }
  
  static inline int sb_start_write_trylock(struct super_block *sb)
  {
  	return __sb_start_write(sb, SB_FREEZE_WRITE, false);
  }
  
  /**
   * 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_sem in lock ordering. Page fault
   * handling code implies lock dependency:
   *
   * mmap_sem
   *   -> sb_start_pagefault
   */
  static inline void sb_start_pagefault(struct super_block *sb)
  {
  	__sb_start_write(sb, SB_FREEZE_PAGEFAULT, true);
  }
  
  /*
   * 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, true);
  }
  
  static inline int sb_start_intwrite_trylock(struct super_block *sb)
  {
  	return __sb_start_write(sb, SB_FREEZE_FS, false);
  }
  
  
  extern bool inode_owner_or_capable(const struct inode *inode);
  
  /*
   * VFS helper functions..
   */
  extern int vfs_create(struct inode *, struct dentry *, umode_t, bool);
  extern int vfs_mkdir(struct inode *, struct dentry *, umode_t);
  extern int vfs_mknod(struct inode *, struct dentry *, umode_t, dev_t);
  extern int vfs_symlink(struct inode *, struct dentry *, const char *);
  extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct inode **);
  extern int vfs_rmdir(struct inode *, struct dentry *);
  extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
  extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
  extern int vfs_whiteout(struct inode *, struct dentry *);
  
  extern struct dentry *vfs_tmpfile(struct dentry *dentry, umode_t mode,
  				  int open_flag);
  
  int vfs_mkobj(struct dentry *, umode_t,
  		int (*f)(struct dentry *, umode_t, void *),
  		void *);
  
  extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
  
  /*
   * VFS file helper functions.
   */
  extern void inode_init_owner(struct inode *inode, const struct inode *dir,
  			umode_t mode);
  extern bool may_open_dev(const struct path *path);
  /*
   * VFS FS_IOC_FIEMAP helper definitions.
   */
  struct fiemap_extent_info {
  	unsigned int fi_flags;		/* Flags as passed from user */
  	unsigned int fi_extents_mapped;	/* Number of mapped extents */
  	unsigned int fi_extents_max;	/* Size of fiemap_extent array */
  	struct fiemap_extent __user *fi_extents_start; /* Start of
  							fiemap_extent array */
  };
  int fiemap_fill_next_extent(struct fiemap_extent_info *info, u64 logical,
  			    u64 phys, u64 len, u32 flags);
  int fiemap_check_flags(struct fiemap_extent_info *fieinfo, u32 fs_flags);
  
  /*
   * 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;
  };
  
  struct block_device_operations;
  
  /* These macros are for out of kernel modules to test that
   * the kernel supports the unlocked_ioctl and compat_ioctl
   * fields in struct file_operations. */
  #define HAVE_COMPAT_IOCTL 1
  #define HAVE_UNLOCKED_IOCTL 1
  
  /*
   * 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 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, bool spin);
  	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);
  	long (*dynamic_remap)(struct file *file1, struct file *file2,
  			      loff_t offset1, loff_t offset2,
  			      loff_t count);
  	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);
  } __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 inode *, int);
  	struct posix_acl * (*get_acl)(struct inode *, int);
  
  	int (*readlink) (struct dentry *, char __user *,int);
  
  	int (*create) (struct inode *,struct dentry *, umode_t, bool);
  	int (*link) (struct dentry *,struct inode *,struct dentry *);
  	int (*unlink) (struct inode *,struct dentry *);
  	int (*symlink) (struct inode *,struct dentry *,const char *);
  	int (*mkdir) (struct inode *,struct dentry *,umode_t);
  	int (*rmdir) (struct inode *,struct dentry *);
  	int (*mknod) (struct inode *,struct dentry *,umode_t,dev_t);
  	int (*rename) (struct inode *, struct dentry *,
  			struct inode *, struct dentry *, unsigned int);
  	int (*setattr) (struct dentry *, struct iattr *);
  	int (*getattr) (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 inode *, struct dentry *, umode_t);
  	int (*set_acl)(struct inode *, struct posix_acl *, int);
  } ____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);
  }
  
  ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
  			      unsigned long nr_segs, unsigned long fast_segs,
  			      struct iovec *fast_pointer,
  			      struct iovec **ret_pointer);
  
  extern ssize_t __vfs_read(struct file *, char __user *, size_t, loff_t *);
  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_readv(struct file *, const struct iovec __user *,
  		unsigned long, loff_t *, rwf_t);
  extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
  				   loff_t, size_t, unsigned int);
  extern ssize_t generic_copy_file_range(struct file *file_in, loff_t pos_in,
  				       struct file *file_out, loff_t pos_out,
  				       size_t len, unsigned int flags);
  extern int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
  					 struct file *file_out, loff_t pos_out,
  					 loff_t *count,
  					 unsigned int remap_flags);
  extern loff_t do_clone_file_range(struct file *file_in, loff_t pos_in,
  				  struct file *file_out, loff_t pos_out,
  				  loff_t len, unsigned int remap_flags);
  extern loff_t vfs_clone_file_range(struct file *file_in, loff_t pos_in,
  				   struct file *file_out, loff_t pos_out,
  				   loff_t len, unsigned int remap_flags);
  extern int vfs_dedupe_file_range(struct file *file,
  				 struct file_dedupe_range *same);
  extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos,
  					struct file *dst_file, loff_t dst_pos,
  					loff_t len, unsigned int remap_flags);
  
  
  struct super_operations {
     	struct inode *(*alloc_inode)(struct super_block *sb);
  	void (*destroy_inode)(struct inode *);
  	void (*free_inode)(struct inode *);
  
     	void (*dirty_inode) (struct inode *, int flags);
  	int (*write_inode) (struct inode *, struct writeback_control *wbc);
  	int (*drop_inode) (struct inode *);
  	void (*evict_inode) (struct inode *);
  	void (*put_super) (struct super_block *);
  	int (*sync_fs)(struct super_block *sb, int wait);
  	int (*freeze_super) (struct super_block *);
  	int (*freeze_fs) (struct super_block *);
  	int (*thaw_super) (struct super_block *);
  	int (*unfreeze_fs) (struct super_block *);
  	int (*statfs) (struct dentry *, struct kstatfs *);
  	int (*remount_fs) (struct super_block *, int *, char *);
  	void (*umount_begin) (struct super_block *);
  
  	int (*show_options)(struct seq_file *, struct dentry *);
  	int (*show_devname)(struct seq_file *, struct dentry *);
  	int (*show_path)(struct seq_file *, struct dentry *);
  	int (*show_stats)(struct seq_file *, struct dentry *);
  #ifdef CONFIG_QUOTA
  	ssize_t (*quota_read)(struct super_block *, int, char *, size_t, loff_t);
  	ssize_t (*quota_write)(struct super_block *, int, const char *, size_t, loff_t);
  	struct dquot **(*get_dquots)(struct inode *);
  #endif
  	int (*bdev_try_to_free_page)(struct super_block*, struct page*, gfp_t);
  	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	/* Writes are synced at once */
  #define S_NOATIME	2	/* Do not update access times */
  #define S_APPEND	4	/* Append-only file */
  #define S_IMMUTABLE	8	/* Immutable file */
  #define S_DEAD		16	/* removed, but still open directory */
  #define S_NOQUOTA	32	/* Inode is not counted to quota */
  #define S_DIRSYNC	64	/* Directory modifications are synchronous */
  #define S_NOCMTIME	128	/* Do not update file c/mtime */
  #define S_SWAPFILE	256	/* Do not truncate: swapon got its bmaps */
  #define S_PRIVATE	512	/* Inode is fs-internal */
  #define S_IMA		1024	/* Inode has an associated IMA struct */
  #define S_AUTOMOUNT	2048	/* Automount/referral quasi-directory */
  #define S_NOSEC		4096	/* no suid or xattr security attributes */
  #ifdef CONFIG_FS_DAX
  #define S_DAX		8192	/* Direct Access, avoiding the page cache */
  #else
  #define S_DAX		0	/* Make all the DAX code disappear */
  #endif
  #define S_ENCRYPTED	16384	/* Encrypted file (using fs/crypto/) */
  #define S_CASEFOLD	32768	/* Casefolded file */
  #define S_VERITY	65536	/* Verity file (using fs/verity/) */
  
  /*
   * 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 inode *inode)
  {
  	return !uid_valid(inode->i_uid) || !gid_valid(inode->i_gid);
  }
  
  static inline enum rw_hint file_write_hint(struct file *file)
  {
  	if (file->f_write_hint != WRITE_LIFE_NOT_SET)
  		return file->f_write_hint;
  
  	return file_inode(file)->i_write_hint;
  }
  
  static inline int iocb_flags(struct file *file);
  
  static inline u16 ki_hint_validate(enum rw_hint hint)
  {
  	typeof(((struct kiocb *)0)->ki_hint) max_hint = -1;
  
  	if (hint <= max_hint)
  		return hint;
  	return 0;
  }
  
  static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
  {
  	*kiocb = (struct kiocb) {
  		.ki_filp = filp,
  		.ki_flags = iocb_flags(filp),
  		.ki_hint = ki_hint_validate(file_write_hint(filp)),
  		.ki_ioprio = get_current_ioprio(),
  	};
  }
  
  /*
   * Inode state bits.  Protected by inode->i_lock
   *
   * Three bits determine the dirty state of the inode, I_DIRTY_SYNC,
   * I_DIRTY_DATASYNC and I_DIRTY_PAGES.
   *
   * 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().  i_atime is 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
   *			mtime has changed in it.
   * I_DIRTY_PAGES	Inode has dirty pages.  Inode itself may be clean.
   * 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.
   *
   * 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_DIRTY_TIME_EXPIRED	12
  #define I_DIRTY_TIME_EXPIRED	(1 << __I_DIRTY_TIME_EXPIRED)
  #define I_WB_SWITCH		(1 << 13)
  #define I_OVL_INUSE		(1 << 14)
  #define I_CREATING		(1 << 15)
  
  #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);
  }
  
  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 *);
  static inline void file_accessed(struct file *file)
  {
  	if (!(file->f_flags & O_NOATIME))
  		touch_atime(&file->f_path);
  }
  
  extern int file_modified(struct file *file);
  
  int sync_inode(struct inode *inode, struct writeback_control *wbc);
  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_RENAME_DOES_D_MOVE	32768	/* FS will handle d_move() during rename() internally. */
  	int (*init_fs_context)(struct fs_context *);
  	const struct fs_parameter_description *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 i_mutex_dir_key;
  };
  
  #define MODULE_ALIAS_FS(NAME) MODULE_ALIAS("fs-" NAME)
  
  #ifdef CONFIG_BLOCK
  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));
  #else
  static inline 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))
  {
  	return ERR_PTR(-ENODEV);
  }
  #endif
  extern struct dentry *mount_single(struct file_system_type *fs_type,
  	int flags, void *data,
  	int (*fill_super)(struct super_block *, void *, int));
  extern struct dentry *mount_nodev(struct file_system_type *fs_type,
  	int flags, void *data,
  	int (*fill_super)(struct super_block *, void *, int));
  extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path);
  void generic_shutdown_super(struct super_block *sb);
  #ifdef CONFIG_BLOCK
  void kill_block_super(struct super_block *sb);
  #else
  static inline void kill_block_super(struct super_block *sb)
  {
  	BUG();
  }
  #endif
  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 struct vfsmount *kern_mount(struct file_system_type *);
  extern void kern_unmount(struct vfsmount *mnt);
  extern int may_umount_tree(struct vfsmount *);
  extern int may_umount(struct vfsmount *);
  extern long do_mount(const char *, const char __user *,
  		     const char *, unsigned long, void *);
  extern struct vfsmount *collect_mounts(const struct path *);
  extern void drop_collected_mounts(struct vfsmount *);
  extern int iterate_mounts(int (*)(struct vfsmount *, void *), void *,
  			  struct vfsmount *);
  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 bool our_mnt(struct vfsmount *mnt);
  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_MANDATORY_FILE_LOCKING
  extern int locks_mandatory_locked(struct file *);
  extern int locks_mandatory_area(struct inode *, struct file *, loff_t, loff_t, unsigned char);
  
  /*
   * Candidates for mandatory locking have the setgid bit set
   * but no group execute bit -  an otherwise meaningless combination.
   */
  
  static inline int __mandatory_lock(struct inode *ino)
  {
  	return (ino->i_mode & (S_ISGID | S_IXGRP)) == S_ISGID;
  }
  
  /*
   * ... and these candidates should be on SB_MANDLOCK mounted fs,
   * otherwise these will be advisory locks
   */
  
  static inline int mandatory_lock(struct inode *ino)
  {
  	return IS_MANDLOCK(ino) && __mandatory_lock(ino);
  }
  
  static inline int locks_verify_locked(struct file *file)
  {
  	if (mandatory_lock(locks_inode(file)))
  		return locks_mandatory_locked(file);
  	return 0;
  }
  
  static inline int locks_verify_truncate(struct inode *inode,
  				    struct file *f,
  				    loff_t size)
  {
  	if (!inode->i_flctx || !mandatory_lock(inode))
  		return 0;
  
  	if (size < inode->i_size) {
  		return locks_mandatory_area(inode, f, size, inode->i_size - 1,
  				F_WRLCK);
  	} else {
  		return locks_mandatory_area(inode, f, inode->i_size, size - 1,
  				F_WRLCK);
  	}
  }
  
  #else /* !CONFIG_MANDATORY_FILE_LOCKING */
  
  static inline int locks_mandatory_locked(struct file *file)
  {
  	return 0;
  }
  
  static inline int locks_mandatory_area(struct inode *inode, struct file *filp,
                                         loff_t start, loff_t end, unsigned char type)
  {
  	return 0;
  }
  
  static inline int __mandatory_lock(struct inode *inode)
  {
  	return 0;
  }
  
  static inline int mandatory_lock(struct inode *inode)
  {
  	return 0;
  }
  
  static inline int locks_verify_locked(struct file *file)
  {
  	return 0;
  }
  
  static inline int locks_verify_truncate(struct inode *inode, struct file *filp,
  					size_t size)
  {
  	return 0;
  }
  
  #endif /* CONFIG_MANDATORY_FILE_LOCKING */
  
  
  #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);
  
  extern long vfs_truncate(const struct path *, loff_t);
  extern int do_truncate(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(struct dentry *, struct vfsmount *,
  				   const char *, int, umode_t);
  extern struct file * dentry_open(const struct path *, int, const struct 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(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/ioctl.c */
  
  extern int ioctl_preallocate(struct file *filp, void __user *argp);
  
  /* 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))
  
  #ifdef CONFIG_BLOCK
  extern int register_blkdev(unsigned int, const char *);
  extern void unregister_blkdev(unsigned int, const char *);
  extern void bdev_unhash_inode(dev_t dev);
  extern struct block_device *bdget(dev_t);
  extern struct block_device *bdgrab(struct block_device *bdev);
  extern void bd_set_size(struct block_device *, loff_t size);
  extern void bd_forget(struct inode *inode);
  extern void bdput(struct block_device *);
  extern void invalidate_bdev(struct block_device *);
  extern void iterate_bdevs(void (*)(struct block_device *, void *), void *);
  extern int sync_blockdev(struct block_device *bdev);
  extern void kill_bdev(struct block_device *);
  extern struct super_block *freeze_bdev(struct block_device *);
  extern void emergency_thaw_all(void);
  extern void emergency_thaw_bdev(struct super_block *sb);
  extern int thaw_bdev(struct block_device *bdev, struct super_block *sb);
  extern int fsync_bdev(struct block_device *);
  
  extern struct super_block *blockdev_superblock;
  
  static inline bool sb_is_blkdev_sb(struct super_block *sb)
  {
  	return sb == blockdev_superblock;
  }
  #else
  static inline void bd_forget(struct inode *inode) {}
  static inline int sync_blockdev(struct block_device *bdev) { return 0; }
  static inline void kill_bdev(struct block_device *bdev) {}
  static inline void invalidate_bdev(struct block_device *bdev) {}
  
  static inline struct super_block *freeze_bdev(struct block_device *sb)
  {
  	return NULL;
  }
  
  static inline int thaw_bdev(struct block_device *bdev, struct super_block *sb)
  {
  	return 0;
  }
  
  static inline int emergency_thaw_bdev(struct super_block *sb)
  {
  	return 0;
  }
  
  static inline void iterate_bdevs(void (*f)(struct block_device *, void *), void *arg)
  {
  }
  
  static inline bool sb_is_blkdev_sb(struct super_block *sb)
  {
  	return false;
  }
  #endif
  extern int sync_filesystem(struct super_block *);
  extern const struct file_operations def_blk_fops;
  extern const struct file_operations def_chr_fops;
  #ifdef CONFIG_BLOCK
  extern int ioctl_by_bdev(struct block_device *, unsigned, unsigned long);
  extern int blkdev_ioctl(struct block_device *, fmode_t, unsigned, unsigned long);
  extern long compat_blkdev_ioctl(struct file *, unsigned, unsigned long);
  extern int blkdev_get(struct block_device *bdev, fmode_t mode, void *holder);
  extern struct block_device *blkdev_get_by_path(const char *path, fmode_t mode,
  					       void *holder);
  extern struct block_device *blkdev_get_by_dev(dev_t dev, fmode_t mode,
  					      void *holder);
  extern struct block_device *bd_start_claiming(struct block_device *bdev,
  					      void *holder);
  extern void bd_finish_claiming(struct block_device *bdev,
  			       struct block_device *whole, void *holder);
  extern void bd_abort_claiming(struct block_device *bdev,
  			      struct block_device *whole, void *holder);
  extern void blkdev_put(struct block_device *bdev, fmode_t mode);
  extern int __blkdev_reread_part(struct block_device *bdev);
  extern int blkdev_reread_part(struct block_device *bdev);
  
  #ifdef CONFIG_SYSFS
  extern int bd_link_disk_holder(struct block_device *bdev, struct gendisk *disk);
  extern void bd_unlink_disk_holder(struct block_device *bdev,
  				  struct gendisk *disk);
  #else
  static inline int bd_link_disk_holder(struct block_device *bdev,
  				      struct gendisk *disk)
  {
  	return 0;
  }
  static inline void bd_unlink_disk_holder(struct block_device *bdev,
  					 struct gendisk *disk)
  {
  }
  #endif
  #endif
  
  /* 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);
  }
  
  /* fs/block_dev.c */
  #define BDEVNAME_SIZE	32	/* Largest string for a blockdev identifier */
  #define BDEVT_SIZE	10	/* Largest string for MAJ:MIN for blkdev */
  
  #ifdef CONFIG_BLOCK
  #define BLKDEV_MAJOR_MAX	512
  extern const char *__bdevname(dev_t, char *buffer);
  extern const char *bdevname(struct block_device *bdev, char *buffer);
  extern struct block_device *lookup_bdev(const char *);
  extern void blkdev_show(struct seq_file *,off_t);
  
  #else
  #define BLKDEV_MAJOR_MAX	0
  #endif
  
  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 *);
  
  #ifdef CONFIG_BLOCK
  extern void check_disk_size_change(struct gendisk *disk,
  		struct block_device *bdev, bool verbose);
  extern int revalidate_disk(struct gendisk *);
  extern int check_disk_change(struct block_device *);
  extern int __invalidate_device(struct block_device *, bool);
  extern int invalidate_partition(struct gendisk *, int);
  #endif
  unsigned long invalidate_mapping_pages(struct address_space *mapping,
  					pgoff_t start, pgoff_t end);
  
  static inline void invalidate_remote_inode(struct inode *inode)
  {
  	if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode) ||
  	    S_ISLNK(inode->i_mode))
  		invalidate_mapping_pages(inode->i_mapping, 0, -1);
  }
  extern int invalidate_inode_pages2(struct address_space *mapping);
  extern int invalidate_inode_pages2_range(struct address_space *mapping,
  					 pgoff_t start, pgoff_t end);
  extern int write_inode_now(struct inode *, int);
  extern int filemap_fdatawrite(struct address_space *);
  extern int filemap_flush(struct address_space *);
  extern int filemap_fdatawait_keep_errors(struct address_space *mapping);
  extern int filemap_fdatawait_range(struct address_space *, loff_t lstart,
  				   loff_t lend);
  extern int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
  		loff_t start_byte, loff_t end_byte);
  
  static inline int filemap_fdatawait(struct address_space *mapping)
  {
  	return filemap_fdatawait_range(mapping, 0, LLONG_MAX);
  }
  
  extern bool filemap_range_has_page(struct address_space *, loff_t lstart,
  				  loff_t lend);
  extern int filemap_write_and_wait(struct address_space *mapping);
  extern int filemap_write_and_wait_range(struct address_space *mapping,
  				        loff_t lstart, loff_t lend);
  extern int __filemap_fdatawrite_range(struct address_space *mapping,
  				loff_t start, loff_t end, int sync_mode);
  extern int filemap_fdatawrite_range(struct address_space *mapping,
  				loff_t start, loff_t end);
  extern int filemap_check_errors(struct address_space *mapping);
  extern void __filemap_set_wb_err(struct address_space *mapping, int err);
  
  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);
  }
  
  /**
   * filemap_set_wb_err - set a writeback error on an address_space
   * @mapping: mapping in which to set writeback error
   * @err: error to be set in mapping
   *
   * When writeback fails in some way, we must record that error so that
   * userspace can be informed when fsync and the like are called.  We endeavor
   * to report errors on any file that was open at the time of the error.  Some
   * internal callers also need to know when writeback errors have occurred.
   *
   * When a writeback error occurs, most filesystems will want to call
   * filemap_set_wb_err to record the error in the mapping so that it will be
   * automatically reported whenever fsync is called on the file.
   */
  static inline void filemap_set_wb_err(struct address_space *mapping, int err)
  {
  	/* Fastpath for common case of no error */
  	if (unlikely(err))
  		__filemap_set_wb_err(mapping, err);
  }
  
  /**
   * filemap_check_wb_error - has an error occurred since the mark was sampled?
   * @mapping: mapping to check for writeback errors
   * @since: previously-sampled errseq_t
   *
   * Grab the errseq_t value from the mapping, and see if it has changed "since"
   * the given value was sampled.
   *
   * If it has then report the latest error set, otherwise return 0.
   */
  static inline int filemap_check_wb_err(struct address_space *mapping,
  					errseq_t since)
  {
  	return errseq_check(&mapping->wb_err, since);
  }
  
  /**
   * filemap_sample_wb_err - sample the current errseq_t to test for later errors
   * @mapping: mapping to be sampled
   *
   * Writeback errors are always reported relative to a particular sample point
   * in the past. This function provides those sample points.
   */
  static inline errseq_t filemap_sample_wb_err(struct address_space *mapping)
  {
  	return errseq_sample(&mapping->wb_err);
  }
  
  static inline int filemap_nr_thps(struct address_space *mapping)
  {
  #ifdef CONFIG_READ_ONLY_THP_FOR_FS
  	return atomic_read(&mapping->nr_thps);
  #else
  	return 0;
  #endif
  }
  
  static inline void filemap_nr_thps_inc(struct address_space *mapping)
  {
  #ifdef CONFIG_READ_ONLY_THP_FOR_FS
  	atomic_inc(&mapping->nr_thps);
  #else
  	WARN_ON_ONCE(1);
  #endif
  }
  
  static inline void filemap_nr_thps_dec(struct address_space *mapping)
  {
  #ifdef CONFIG_READ_ONLY_THP_FOR_FS
  	atomic_dec(&mapping->nr_thps);
  #else
  	WARN_ON_ONCE(1);
  #endif
  }
  
  extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
  			   int datasync);
  extern int vfs_fsync(struct file *file, int datasync);
  
  extern int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
  				unsigned int flags);
  
  /*
   * Sync the bytes written if this was a synchronous write.  Expect ki_pos
   * to already be updated for the write, and will return either the amount
   * of bytes passed in, or an error if syncing the file failed.
   */
  static inline ssize_t generic_write_sync(struct kiocb *iocb, ssize_t count)
  {
  	if (iocb->ki_flags & IOCB_DSYNC) {
  		int ret = vfs_fsync_range(iocb->ki_filp,
  				iocb->ki_pos - count, iocb->ki_pos - 1,
  				(iocb->ki_flags & IOCB_SYNC) ? 0 : 1);
  		if (ret)
  			return ret;
  	}
  
  	return count;
  }
  
  extern void emergency_sync(void);
  extern void emergency_remount(void);
  #ifdef CONFIG_BLOCK
  extern sector_t bmap(struct inode *, sector_t);
  #endif
  extern int notify_change(struct dentry *, struct iattr *, struct inode **);
  extern int inode_permission(struct inode *, int);
  extern int generic_permission(struct inode *, int);
  extern int __check_sticky(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 void file_start_write(struct file *file)
  {
  	if (!S_ISREG(file_inode(file)->i_mode))
  		return;
  	__sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, true);
  }
  
  static inline bool file_start_write_trylock(struct file *file)
  {
  	if (!S_ISREG(file_inode(file)->i_mode))
  		return true;
  	return __sb_start_write(file_inode(file)->i_sb, SB_FREEZE_WRITE, false);
  }
  
  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);
  }
  
  /*
   * get_write_access() gets write permission for a file.
   * put_write_access() releases this write permission.
   * This is used for regular files.
   * We cannot support write (and maybe mmap read-write shared) accesses and
   * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
   * can have the following values:
   * 0: no writers, no VM_DENYWRITE mappings
   * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
   * > 0: (i_writecount) users are writing 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);
  
  #define __kernel_read_file_id(id) \
  	id(UNKNOWN, unknown)		\
  	id(FIRMWARE, firmware)		\
  	id(FIRMWARE_PREALLOC_BUFFER, firmware)	\
  	id(MODULE, kernel-module)		\
  	id(KEXEC_IMAGE, kexec-image)		\
  	id(KEXEC_INITRAMFS, kexec-initramfs)	\
  	id(POLICY, security-policy)		\
  	id(X509_CERTIFICATE, x509-certificate)	\
  	id(MAX_ID, )
  
  #define __fid_enumify(ENUM, dummy) READING_ ## ENUM,
  #define __fid_stringify(dummy, str) #str,
  
  enum kernel_read_file_id {
  	__kernel_read_file_id(__fid_enumify)
  };
  
  static const char * const kernel_read_file_str[] = {
  	__kernel_read_file_id(__fid_stringify)
  };
  
  static inline const char *kernel_read_file_id_str(enum kernel_read_file_id id)
  {
  	if ((unsigned)id >= READING_MAX_ID)
  		return kernel_read_file_str[READING_UNKNOWN];
  
  	return kernel_read_file_str[id];
  }
  
  extern int kernel_read_file(struct file *, void **, loff_t *, loff_t,
  			    enum kernel_read_file_id);
  extern int kernel_read_file_from_path(const char *, void **, loff_t *, loff_t,
  				      enum kernel_read_file_id);
  extern int kernel_read_file_from_fd(int, void **, loff_t *, loff_t,
  				    enum kernel_read_file_id);
  extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *);
  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 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 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);
  
  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 *);
  
  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);
  
  #ifdef CONFIG_BLOCK
  extern int bdev_read_only(struct block_device *);
  #endif
  extern int set_blocksize(struct block_device *, int);
  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 *);
  extern int generic_remap_checks(struct file *file_in, loff_t pos_in,
  				struct file *file_out, loff_t pos_out,
  				loff_t *count, unsigned int remap_flags);
  extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
  extern int generic_copy_file_checks(struct file *file_in, loff_t pos_in,
  				    struct file *file_out, loff_t pos_out,
  				    size_t *count, unsigned int flags);
  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 *);
  extern ssize_t generic_perform_write(struct file *, struct iov_iter *, loff_t);
  
  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);
  
  /* fs/block_dev.c */
  extern ssize_t blkdev_read_iter(struct kiocb *iocb, struct iov_iter *to);
  extern ssize_t blkdev_write_iter(struct kiocb *iocb, struct iov_iter *from);
  extern int blkdev_fsync(struct file *filp, loff_t start, loff_t end,
  			int datasync);
  extern void block_sync_page(struct page *page);
  
  /* 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);
  extern loff_t no_llseek(struct file *file, loff_t offset, int whence);
  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);
  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,
  };
  
  void dio_end_io(struct bio *bio);
  void dio_warn_stale_pagecache(struct file *filp);
  
  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);
  }
  
  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,
  		int nofs);
  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 *);
  extern void generic_fillattr(struct inode *, struct kstat *);
  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 *);
  
  extern int vfs_statx(int, const char __user *, int, struct kstat *, u32);
  extern int vfs_statx_fd(unsigned int, struct kstat *, u32, unsigned int);
  
  static inline int vfs_stat(const char __user *filename, struct kstat *stat)
  {
  	return vfs_statx(AT_FDCWD, filename, AT_NO_AUTOMOUNT,
  			 stat, STATX_BASIC_STATS);
  }
  static inline int vfs_lstat(const char __user *name, struct kstat *stat)
  {
  	return vfs_statx(AT_FDCWD, name, AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT,
  			 stat, STATX_BASIC_STATS);
  }
  static inline int vfs_fstatat(int dfd, const char __user *filename,
  			      struct kstat *stat, int flags)
  {
  	return vfs_statx(dfd, filename, flags | AT_NO_AUTOMOUNT,
  			 stat, STATX_BASIC_STATS);
  }
  static inline int vfs_fstat(int fd, struct kstat *stat)
  {
  	return vfs_statx_fd(fd, stat, STATX_BASIC_STATS, 0);
  }
  
  
  extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
  extern int vfs_readlink(struct dentry *, char __user *, int);
  
  extern int __generic_block_fiemap(struct inode *inode,
  				  struct fiemap_extent_info *fieinfo,
  				  loff_t start, loff_t len,
  				  get_block_t *get_block);
  extern int generic_block_fiemap(struct inode *inode,
  				struct fiemap_extent_info *fieinfo, u64 start,
  				u64 len, get_block_t *get_block);
  
  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_super_thawed(struct block_device *);
  extern struct super_block *get_super_exclusive_thawed(struct block_device *bdev);
  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 dentry *, struct iattr *);
  extern int simple_getattr(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(struct inode *, struct dentry *,
  			 struct inode *, struct dentry *, unsigned int);
  extern int noop_fsync(struct file *, loff_t, loff_t, int);
  extern int noop_set_page_dirty(struct page *page);
  extern void noop_invalidatepage(struct page *page, unsigned int offset,
  		unsigned int length);
  extern ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
  extern int simple_empty(struct dentry *);
  extern int simple_readpage(struct file *file, struct page *page);
  extern int simple_write_begin(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned flags,
  			struct page **pagep, void **fsdata);
  extern int simple_write_end(struct file *file, struct address_space *mapping,
  			loff_t pos, unsigned len, unsigned copied,
  			struct page *page, void *fsdata);
  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);
  
  #ifdef CONFIG_MIGRATION
  extern int buffer_migrate_page(struct address_space *,
  				struct page *, struct page *,
  				enum migrate_mode);
  extern int buffer_migrate_page_norefs(struct address_space *,
  				struct page *, struct page *,
  				enum migrate_mode);
  #else
  #define buffer_migrate_page NULL
  #define buffer_migrate_page_norefs NULL
  #endif
  
  extern int setattr_prepare(struct dentry *, struct iattr *);
  extern int inode_newsize_ok(const struct inode *, loff_t offset);
  extern void setattr_copy(struct inode *inode, const struct iattr *attr);
  
  extern int file_update_time(struct file *file);
  
  static inline bool io_is_direct(struct file *filp)
  {
  	return (filp->f_flags & O_DIRECT) || IS_DAX(filp->f_mapping->host);
  }
  
  static inline bool vma_is_dax(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 (!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 (io_is_direct(file))
  		res |= IOCB_DIRECT;
  	if ((file->f_flags & O_DSYNC) || IS_SYNC(file->f_mapping->host))
  		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)
  {
  	if (unlikely(flags & ~RWF_SUPPORTED))
  		return -EOPNOTSUPP;
  
  	if (flags & RWF_NOWAIT) {
  		if (!(ki->ki_filp->f_mode & FMODE_NOWAIT))
  			return -EOPNOTSUPP;
  		ki->ki_flags |= IOCB_NOWAIT;
  	}
  	if (flags & RWF_HIPRI)
  		ki->ki_flags |= IOCB_HIPRI;
  	if (flags & RWF_DSYNC)
  		ki->ki_flags |= IOCB_DSYNC;
  	if (flags & RWF_SYNC)
  		ki->ki_flags |= (IOCB_DSYNC | IOCB_SYNC);
  	if (flags & RWF_APPEND)
  		ki->ki_flags |= IOCB_APPEND;
  	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[0];
  };
  
  #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 proc_nr_files(struct ctl_table *table, int write,
  		  void __user *buffer, size_t *lenp, loff_t *ppos);
  int proc_nr_dentry(struct ctl_table *table, int write,
  		  void __user *buffer, size_t *lenp, loff_t *ppos);
  int proc_nr_inodes(struct ctl_table *table, int write,
  		   void __user *buffer, size_t *lenp, loff_t *ppos);
  int __init get_filesystem_list(char *buf);
  
  #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 inode *dir, struct inode *inode)
  {
  	if (!(dir->i_mode & S_ISVTX))
  		return 0;
  
  	return __check_sticky(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);
  
  #if defined(CONFIG_IO_URING)
  extern struct sock *io_uring_get_socket(struct file *file);
  #else
  static inline struct sock *io_uring_get_socket(struct file *file)
  {
  	return NULL;
  }
  #endif
  
  int vfs_ioc_setflags_prepare(struct inode *inode, unsigned int oldflags,
  			     unsigned int flags);
  
  int vfs_ioc_fssetxattr_check(struct inode *inode, const struct fsxattr *old_fa,
  			     struct fsxattr *fa);
  
  static inline void simple_fill_fsxattr(struct fsxattr *fa, __u32 xflags)
  {
  	memset(fa, 0, sizeof(*fa));
  	fa->fsx_xflags = xflags;
  }
  
  /*
   * Flush file data before changing attributes.  Caller must hold any locks
   * required to prevent further writes to this file until we're done setting
   * flags.
   */
  static inline int inode_drain_writes(struct inode *inode)
  {
  	inode_dio_wait(inode);
  	return filemap_write_and_wait(inode->i_mapping);
  }
  
  #endif /* _LINUX_FS_H */
  