TOMOYO Linux Cross Reference
Linux/include/linux/fs.h

   /* SPDX-License-Identifier: GPL-2.0 */
   #ifndef _LINUX_FS_H
   #define _LINUX_FS_H
   
   #include <linux/linkage.h>
   #include <linux/wait_bit.h>
   #include <linux/kdev_t.h>
   #include <linux/dcache.h>
   #include <linux/path.h>
  #include <linux/stat.h>
  #include <linux/cache.h>
  #include <linux/list.h>
  #include <linux/list_lru.h>
  #include <linux/llist.h>
  #include <linux/radix-tree.h>
  #include <linux/xarray.h>
  #include <linux/rbtree.h>
  #include <linux/init.h>
  #include <linux/pid.h>
  #include <linux/bug.h>
  #include <linux/mutex.h>
  #include <linux/rwsem.h>
  #include <linux/mm_types.h>
  #include <linux/capability.h>
  #include <linux/semaphore.h>
  #include <linux/fcntl.h>
  #include <linux/rculist_bl.h>
  #include <linux/atomic.h>
  #include <linux/shrinker.h>
  #include <linux/migrate_mode.h>
  #include <linux/uidgid.h>
  #include <linux/lockdep.h>
  #include <linux/percpu-rwsem.h>
  #include <linux/workqueue.h>
  #include <linux/delayed_call.h>
  #include <linux/uuid.h>
  #include <linux/errseq.h>
  #include <linux/ioprio.h>
  #include <linux/fs_types.h>
  #include <linux/build_bug.h>
  #include <linux/stddef.h>
  #include <linux/mount.h>
  #include <linux/cred.h>
  #include <linux/mnt_idmapping.h>
  #include <linux/slab.h>
  #include <linux/maple_tree.h>
  #include <linux/rw_hint.h>
  
  #include <asm/byteorder.h>
  #include <uapi/linux/fs.h>
  
  struct backing_dev_info;
  struct bdi_writeback;
  struct bio;
  struct io_comp_batch;
  struct export_operations;
  struct fiemap_extent_info;
  struct hd_geometry;
  struct iovec;
  struct kiocb;
  struct kobject;
  struct pipe_inode_info;
  struct poll_table_struct;
  struct kstatfs;
  struct vm_area_struct;
  struct vfsmount;
  struct cred;
  struct swap_info_struct;
  struct seq_file;
  struct workqueue_struct;
  struct iov_iter;
  struct fscrypt_inode_info;
  struct fscrypt_operations;
  struct fsverity_info;
  struct fsverity_operations;
  struct fsnotify_mark_connector;
  struct fsnotify_sb_info;
  struct fs_context;
  struct fs_parameter_spec;
  struct fileattr;
  struct iomap_ops;
  
  extern void __init inode_init(void);
  extern void __init inode_init_early(void);
  extern void __init files_init(void);
  extern void __init files_maxfiles_init(void);
  
  extern unsigned long get_max_files(void);
  extern unsigned int sysctl_nr_open;
  
  typedef __kernel_rwf_t rwf_t;
  
  struct buffer_head;
  typedef int (get_block_t)(struct inode *inode, sector_t iblock,
                          struct buffer_head *bh_result, int create);
  typedef int (dio_iodone_t)(struct kiocb *iocb, loff_t offset,
                          ssize_t bytes, void *private);
  
  #define MAY_EXEC                0x00000001
 #define MAY_WRITE               0x00000002
 #define MAY_READ                0x00000004
 #define MAY_APPEND              0x00000008
 #define MAY_ACCESS              0x00000010
 #define MAY_OPEN                0x00000020
 #define MAY_CHDIR               0x00000040
 /* called from RCU mode, don't block */
 #define MAY_NOT_BLOCK           0x00000080
 
 /*
  * flags in file.f_mode.  Note that FMODE_READ and FMODE_WRITE must correspond
  * to O_WRONLY and O_RDWR via the strange trick in do_dentry_open()
  */
 
 /* file is open for reading */
 #define FMODE_READ              ((__force fmode_t)(1 << 0))
 /* file is open for writing */
 #define FMODE_WRITE             ((__force fmode_t)(1 << 1))
 /* file is seekable */
 #define FMODE_LSEEK             ((__force fmode_t)(1 << 2))
 /* file can be accessed using pread */
 #define FMODE_PREAD             ((__force fmode_t)(1 << 3))
 /* file can be accessed using pwrite */
 #define FMODE_PWRITE            ((__force fmode_t)(1 << 4))
 /* File is opened for execution with sys_execve / sys_uselib */
 #define FMODE_EXEC              ((__force fmode_t)(1 << 5))
 /* File writes are restricted (block device specific) */
 #define FMODE_WRITE_RESTRICTED  ((__force fmode_t)(1 << 6))
 /* File supports atomic writes */
 #define FMODE_CAN_ATOMIC_WRITE  ((__force fmode_t)(1 << 7))
 
 /* FMODE_* bit 8 */
 
 /* 32bit hashes as llseek() offset (for directories) */
 #define FMODE_32BITHASH         ((__force fmode_t)(1 << 9))
 /* 64bit hashes as llseek() offset (for directories) */
 #define FMODE_64BITHASH         ((__force fmode_t)(1 << 10))
 
 /*
  * 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)(1 << 11))
 
 /* Expect random access pattern */
 #define FMODE_RANDOM            ((__force fmode_t)(1 << 12))
 
 /* File is huge (eg. /dev/mem): treat loff_t as unsigned */
 #define FMODE_UNSIGNED_OFFSET   ((__force fmode_t)(1 << 13))
 
 /* File is opened with O_PATH; almost nothing can be done with it */
 #define FMODE_PATH              ((__force fmode_t)(1 << 14))
 
 /* File needs atomic accesses to f_pos */
 #define FMODE_ATOMIC_POS        ((__force fmode_t)(1 << 15))
 /* Write access to underlying fs */
 #define FMODE_WRITER            ((__force fmode_t)(1 << 16))
 /* Has read method(s) */
 #define FMODE_CAN_READ          ((__force fmode_t)(1 << 17))
 /* Has write method(s) */
 #define FMODE_CAN_WRITE         ((__force fmode_t)(1 << 18))
 
 #define FMODE_OPENED            ((__force fmode_t)(1 << 19))
 #define FMODE_CREATED           ((__force fmode_t)(1 << 20))
 
 /* File is stream-like */
 #define FMODE_STREAM            ((__force fmode_t)(1 << 21))
 
 /* File supports DIRECT IO */
 #define FMODE_CAN_ODIRECT       ((__force fmode_t)(1 << 22))
 
 #define FMODE_NOREUSE           ((__force fmode_t)(1 << 23))
 
 /* FMODE_* bit 24 */
 
 /* File is embedded in backing_file object */
 #define FMODE_BACKING           ((__force fmode_t)(1 << 25))
 
 /* File was opened by fanotify and shouldn't generate fanotify events */
 #define FMODE_NONOTIFY          ((__force fmode_t)(1 << 26))
 
 /* File is capable of returning -EAGAIN if I/O will block */
 #define FMODE_NOWAIT            ((__force fmode_t)(1 << 27))
 
 /* File represents mount that needs unmounting */
 #define FMODE_NEED_UNMOUNT      ((__force fmode_t)(1 << 28))
 
 /* File does not contribute to nr_files count */
 #define FMODE_NOACCOUNT         ((__force fmode_t)(1 << 29))
 
 /*
  * 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)
 #define ATTR_DELEG      (1 << 18) /* Delegated attrs. Don't break write delegations */
 
 /*
  * Whiteout is represented by a char device.  The following constants define the
  * mode and device number to use.
  */
 #define WHITEOUT_MODE 0
 #define WHITEOUT_DEV 0
 
 /*
  * This is the Inode Attributes structure, used for notify_change().  It
  * uses the above definitions as flags, to know which values have changed.
  * Also, in this manner, a Filesystem can look at only the values it cares
  * about.  Basically, these are the attributes that the VFS layer can
  * request to change from the FS layer.
  *
  * Derek Atkins <warlord@MIT.EDU> 94-10-20
  */
 struct iattr {
         unsigned int    ia_valid;
         umode_t         ia_mode;
         /*
          * The two anonymous unions wrap structures with the same member.
          *
          * Filesystems raising FS_ALLOW_IDMAP need to use ia_vfs{g,u}id which
          * are a dedicated type requiring the filesystem to use the dedicated
          * helpers. Other filesystem can continue to use ia_{g,u}id until they
          * have been ported.
          *
          * They always contain the same value. In other words FS_ALLOW_IDMAP
          * pass down the same value on idmapped mounts as they would on regular
          * mounts.
          */
         union {
                 kuid_t          ia_uid;
                 vfsuid_t        ia_vfsuid;
         };
         union {
                 kgid_t          ia_gid;
                 vfsgid_t        ia_vfsgid;
         };
         loff_t          ia_size;
         struct timespec64 ia_atime;
         struct timespec64 ia_mtime;
         struct timespec64 ia_ctime;
 
         /*
          * Not an attribute, but an auxiliary info for filesystems wanting to
          * implement an ftruncate() like method.  NOTE: filesystem should
          * check for (ia_valid & ATTR_FILE), and not for (ia_file != NULL).
          */
         struct file     *ia_file;
 };
 
 /*
  * Includes for diskquotas.
  */
 #include <linux/quota.h>
 
 /*
  * Maximum number of layers of fs stack.  Needs to be limited to
  * prevent kernel stack overflow
  */
 #define FILESYSTEM_MAX_STACK_DEPTH 2
 
 /** 
  * enum positive_aop_returns - aop return codes with specific semantics
  *
  * @AOP_WRITEPAGE_ACTIVATE: Informs the caller that page writeback has
  *                          completed, that the page is still locked, and
  *                          should be considered active.  The VM uses this hint
  *                          to return the page to the active list -- it won't
  *                          be a candidate for writeback again in the near
  *                          future.  Other callers must be careful to unlock
  *                          the page if they get this return.  Returned by
  *                          writepage(); 
  *
  * @AOP_TRUNCATED_PAGE: The AOP method that was handed a locked page has
  *                      unlocked it and the page might have been truncated.
  *                      The caller should back up to acquiring a new page and
  *                      trying again.  The aop will be taking reasonable
  *                      precautions not to livelock.  If the caller held a page
  *                      reference, it should drop it before retrying.  Returned
  *                      by read_folio().
  *
  * address_space_operation functions return these large constants to indicate
  * special semantics to the caller.  These are much larger than the bytes in a
  * page to allow for functions that return the number of bytes operated on in a
  * given page.
  */
 
 enum positive_aop_returns {
         AOP_WRITEPAGE_ACTIVATE  = 0x80000,
         AOP_TRUNCATED_PAGE      = 0x80001,
 };
 
 /*
  * oh the beauties of C type declarations.
  */
 struct page;
 struct address_space;
 struct writeback_control;
 struct readahead_control;
 
 /* Match RWF_* bits to IOCB bits */
 #define IOCB_HIPRI              (__force int) RWF_HIPRI
 #define IOCB_DSYNC              (__force int) RWF_DSYNC
 #define IOCB_SYNC               (__force int) RWF_SYNC
 #define IOCB_NOWAIT             (__force int) RWF_NOWAIT
 #define IOCB_APPEND             (__force int) RWF_APPEND
 #define IOCB_ATOMIC             (__force int) RWF_ATOMIC
 
 /* non-RWF related bits - start at 16 */
 #define IOCB_EVENTFD            (1 << 16)
 #define IOCB_DIRECT             (1 << 17)
 #define IOCB_WRITE              (1 << 18)
 /* iocb->ki_waitq is valid */
 #define IOCB_WAITQ              (1 << 19)
 #define IOCB_NOIO               (1 << 20)
 /* can use bio alloc cache */
 #define IOCB_ALLOC_CACHE        (1 << 21)
 /*
  * IOCB_DIO_CALLER_COMP can be set by the iocb owner, to indicate that the
  * iocb completion can be passed back to the owner for execution from a safe
  * context rather than needing to be punted through a workqueue. If this
  * flag is set, the bio completion handling may set iocb->dio_complete to a
  * handler function and iocb->private to context information for that handler.
  * The issuer should call the handler with that context information from task
  * context to complete the processing of the iocb. Note that while this
  * provides a task context for the dio_complete() callback, it should only be
  * used on the completion side for non-IO generating completions. It's fine to
  * call blocking functions from this callback, but they should not wait for
  * unrelated IO (like cache flushing, new IO generation, etc).
  */
 #define IOCB_DIO_CALLER_COMP    (1 << 22)
 /* kiocb is a read or write operation submitted by fs/aio.c. */
 #define IOCB_AIO_RW             (1 << 23)
 
 /* for use in trace events */
 #define TRACE_IOCB_STRINGS \
         { IOCB_HIPRI,           "HIPRI" }, \
         { IOCB_DSYNC,           "DSYNC" }, \
         { IOCB_SYNC,            "SYNC" }, \
         { IOCB_NOWAIT,          "NOWAIT" }, \
         { IOCB_APPEND,          "APPEND" }, \
         { IOCB_ATOMIC,          "ATOMIC"}, \
         { IOCB_EVENTFD,         "EVENTFD"}, \
         { IOCB_DIRECT,          "DIRECT" }, \
         { IOCB_WRITE,           "WRITE" }, \
         { IOCB_WAITQ,           "WAITQ" }, \
         { IOCB_NOIO,            "NOIO" }, \
         { IOCB_ALLOC_CACHE,     "ALLOC_CACHE" }, \
         { IOCB_DIO_CALLER_COMP, "CALLER_COMP" }
 
 struct kiocb {
         struct file             *ki_filp;
         loff_t                  ki_pos;
         void (*ki_complete)(struct kiocb *iocb, long ret);
         void                    *private;
         int                     ki_flags;
         u16                     ki_ioprio; /* See linux/ioprio.h */
         union {
                 /*
                  * Only used for async buffered reads, where it denotes the
                  * page waitqueue associated with completing the read. Valid
                  * IFF IOCB_WAITQ is set.
                  */
                 struct wait_page_queue  *ki_waitq;
                 /*
                  * Can be used for O_DIRECT IO, where the completion handling
                  * is punted back to the issuer of the IO. May only be set
                  * if IOCB_DIO_CALLER_COMP is set by the issuer, and the issuer
                  * must then check for presence of this handler when ki_complete
                  * is invoked. The data passed in to this handler must be
                  * assigned to ->private when dio_complete is assigned.
                  */
                 ssize_t (*dio_complete)(void *data);
         };
 };
 
 static inline bool is_sync_kiocb(struct kiocb *kiocb)
 {
         return kiocb->ki_complete == NULL;
 }
 
 struct address_space_operations {
         int (*writepage)(struct page *page, struct writeback_control *wbc);
         int (*read_folio)(struct file *, struct folio *);
 
         /* Write back some dirty pages from this mapping. */
         int (*writepages)(struct address_space *, struct writeback_control *);
 
         /* Mark a folio dirty.  Return true if this dirtied it */
         bool (*dirty_folio)(struct address_space *, struct folio *);
 
         void (*readahead)(struct readahead_control *);
 
         int (*write_begin)(struct file *, struct address_space *mapping,
                                 loff_t pos, unsigned len,
                                 struct page **pagep, void **fsdata);
         int (*write_end)(struct file *, struct address_space *mapping,
                                 loff_t pos, unsigned len, unsigned copied,
                                 struct page *page, void *fsdata);
 
         /* Unfortunately this kludge is needed for FIBMAP. Don't use it */
         sector_t (*bmap)(struct address_space *, sector_t);
         void (*invalidate_folio) (struct folio *, size_t offset, size_t len);
         bool (*release_folio)(struct folio *, gfp_t);
         void (*free_folio)(struct folio *folio);
         ssize_t (*direct_IO)(struct kiocb *, struct iov_iter *iter);
         /*
          * migrate the contents of a folio to the specified target. If
          * migrate_mode is MIGRATE_ASYNC, it must not block.
          */
         int (*migrate_folio)(struct address_space *, struct folio *dst,
                         struct folio *src, enum migrate_mode);
         int (*launder_folio)(struct folio *);
         bool (*is_partially_uptodate) (struct folio *, size_t from,
                         size_t count);
         void (*is_dirty_writeback) (struct folio *, bool *dirty, bool *wb);
         int (*error_remove_folio)(struct address_space *, struct folio *);
 
         /* swapfile support */
         int (*swap_activate)(struct swap_info_struct *sis, struct file *file,
                                 sector_t *span);
         void (*swap_deactivate)(struct file *file);
         int (*swap_rw)(struct kiocb *iocb, struct iov_iter *iter);
 };
 
 extern const struct address_space_operations empty_aops;
 
 /**
  * struct address_space - Contents of a cacheable, mappable object.
  * @host: Owner, either the inode or the block_device.
  * @i_pages: Cached pages.
  * @invalidate_lock: Guards coherency between page cache contents and
  *   file offset->disk block mappings in the filesystem during invalidates.
  *   It is also used to block modification of page cache contents through
  *   memory mappings.
  * @gfp_mask: Memory allocation flags to use for allocating pages.
  * @i_mmap_writable: Number of VM_SHARED, VM_MAYWRITE mappings.
  * @nr_thps: Number of THPs in the pagecache (non-shmem only).
  * @i_mmap: Tree of private and shared mappings.
  * @i_mmap_rwsem: Protects @i_mmap and @i_mmap_writable.
  * @nrpages: Number of page entries, protected by the i_pages lock.
  * @writeback_index: Writeback starts here.
  * @a_ops: Methods.
  * @flags: Error bits and flags (AS_*).
  * @wb_err: The most recent error which has occurred.
  * @i_private_lock: For use by the owner of the address_space.
  * @i_private_list: For use by the owner of the address_space.
  * @i_private_data: For use by the owner of the address_space.
  */
 struct address_space {
         struct inode            *host;
         struct xarray           i_pages;
         struct rw_semaphore     invalidate_lock;
         gfp_t                   gfp_mask;
         atomic_t                i_mmap_writable;
 #ifdef CONFIG_READ_ONLY_THP_FOR_FS
         /* number of thp, only for non-shmem files */
         atomic_t                nr_thps;
 #endif
         struct rb_root_cached   i_mmap;
         unsigned long           nrpages;
         pgoff_t                 writeback_index;
         const struct address_space_operations *a_ops;
         unsigned long           flags;
         errseq_t                wb_err;
         spinlock_t              i_private_lock;
         struct list_head        i_private_list;
         struct rw_semaphore     i_mmap_rwsem;
         void *                  i_private_data;
 } __attribute__((aligned(sizeof(long)))) __randomize_layout;
         /*
          * On most architectures that alignment is already the case; but
          * must be enforced here for CRIS, to let the least significant bit
          * of struct page's "mapping" pointer be used for PAGE_MAPPING_ANON.
          */
 
 /* XArray tags, for tagging dirty and writeback pages in the pagecache. */
 #define PAGECACHE_TAG_DIRTY     XA_MARK_0
 #define PAGECACHE_TAG_WRITEBACK XA_MARK_1
 #define PAGECACHE_TAG_TOWRITE   XA_MARK_2
 
 /*
  * Returns true if any of the pages in the mapping are marked with the tag.
  */
 static inline bool mapping_tagged(struct address_space *mapping, xa_mark_t tag)
 {
         return xa_marked(&mapping->i_pages, tag);
 }
 
 static inline void i_mmap_lock_write(struct address_space *mapping)
 {
         down_write(&mapping->i_mmap_rwsem);
 }
 
 static inline int i_mmap_trylock_write(struct address_space *mapping)
 {
         return down_write_trylock(&mapping->i_mmap_rwsem);
 }
 
 static inline void i_mmap_unlock_write(struct address_space *mapping)
 {
         up_write(&mapping->i_mmap_rwsem);
 }
 
 static inline int i_mmap_trylock_read(struct address_space *mapping)
 {
         return down_read_trylock(&mapping->i_mmap_rwsem);
 }
 
 static inline void i_mmap_lock_read(struct address_space *mapping)
 {
         down_read(&mapping->i_mmap_rwsem);
 }
 
 static inline void i_mmap_unlock_read(struct address_space *mapping)
 {
         up_read(&mapping->i_mmap_rwsem);
 }
 
 static inline void i_mmap_assert_locked(struct address_space *mapping)
 {
         lockdep_assert_held(&mapping->i_mmap_rwsem);
 }
 
 static inline void i_mmap_assert_write_locked(struct address_space *mapping)
 {
         lockdep_assert_held_write(&mapping->i_mmap_rwsem);
 }
 
 /*
  * Might pages of this file be mapped into userspace?
  */
 static inline int mapping_mapped(struct address_space *mapping)
 {
         return  !RB_EMPTY_ROOT(&mapping->i_mmap.rb_root);
 }
 
 /*
  * Might pages of this file have been modified in userspace?
  * Note that i_mmap_writable counts all VM_SHARED, VM_MAYWRITE vmas: do_mmap
  * marks vma as VM_SHARED if it is shared, and the file was opened for
  * writing i.e. vma may be mprotected writable even if now readonly.
  *
  * If i_mmap_writable is negative, no new writable mappings are allowed. You
  * can only deny writable mappings, if none exists right now.
  */
 static inline int mapping_writably_mapped(struct address_space *mapping)
 {
         return atomic_read(&mapping->i_mmap_writable) > 0;
 }
 
 static inline int mapping_map_writable(struct address_space *mapping)
 {
         return atomic_inc_unless_negative(&mapping->i_mmap_writable) ?
                 0 : -EPERM;
 }
 
 static inline void mapping_unmap_writable(struct address_space *mapping)
 {
         atomic_dec(&mapping->i_mmap_writable);
 }
 
 static inline int mapping_deny_writable(struct address_space *mapping)
 {
         return atomic_dec_unless_positive(&mapping->i_mmap_writable) ?
                 0 : -EBUSY;
 }
 
 static inline void mapping_allow_writable(struct address_space *mapping)
 {
         atomic_inc(&mapping->i_mmap_writable);
 }
 
 /*
  * Use sequence counter to get consistent i_size on 32-bit processors.
  */
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
 #include <linux/seqlock.h>
 #define __NEED_I_SIZE_ORDERED
 #define i_size_ordered_init(inode) seqcount_init(&inode->i_size_seqcount)
 #else
 #define i_size_ordered_init(inode) do { } while (0)
 #endif
 
 struct posix_acl;
 #define ACL_NOT_CACHED ((void *)(-1))
 /*
  * ACL_DONT_CACHE is for stacked filesystems, that rely on underlying fs to
  * cache the ACL.  This also means that ->get_inode_acl() can be called in RCU
  * mode with the LOOKUP_RCU flag.
  */
 #define ACL_DONT_CACHE ((void *)(-3))
 
 static inline struct posix_acl *
 uncached_acl_sentinel(struct task_struct *task)
 {
         return (void *)task + 1;
 }
 
 static inline bool
 is_uncached_acl(struct posix_acl *acl)
 {
         return (long)acl & 1;
 }
 
 #define IOP_FASTPERM    0x0001
 #define IOP_LOOKUP      0x0002
 #define IOP_NOFOLLOW    0x0004
 #define IOP_XATTR       0x0008
 #define IOP_DEFAULT_READLINK    0x0010
 
 /*
  * 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;
         time64_t                i_atime_sec;
         time64_t                i_mtime_sec;
         time64_t                i_ctime_sec;
         u32                     i_atime_nsec;
         u32                     i_mtime_nsec;
         u32                     i_ctime_nsec;
         u32                     i_generation;
         spinlock_t              i_lock; /* i_blocks, i_bytes, maybe i_size */
         unsigned short          i_bytes;
         u8                      i_blkbits;
         enum rw_hint            i_write_hint;
         blkcnt_t                i_blocks;
 
 #ifdef __NEED_I_SIZE_ORDERED
         seqcount_t              i_size_seqcount;
 #endif
 
         /* Misc */
         unsigned long           i_state;
         struct rw_semaphore     i_rwsem;
 
         unsigned long           dirtied_when;   /* jiffies of first dirtying */
         unsigned long           dirtied_time_when;
 
         struct hlist_node       i_hash;
         struct list_head        i_io_list;      /* backing dev IO list */
 #ifdef CONFIG_CGROUP_WRITEBACK
         struct bdi_writeback    *i_wb;          /* the associated cgroup wb */
 
         /* foreign inode detection, see wbc_detach_inode() */
         int                     i_wb_frn_winner;
         u16                     i_wb_frn_avg_time;
         u16                     i_wb_frn_history;
 #endif
         struct list_head        i_lru;          /* inode LRU list */
         struct list_head        i_sb_list;
         struct list_head        i_wb_list;      /* backing dev writeback list */
         union {
                 struct hlist_head       i_dentry;
                 struct rcu_head         i_rcu;
         };
         atomic64_t              i_version;
         atomic64_t              i_sequence; /* see futex */
         atomic_t                i_count;
         atomic_t                i_dio_count;
         atomic_t                i_writecount;
 #if defined(CONFIG_IMA) || defined(CONFIG_FILE_LOCKING)
         atomic_t                i_readcount; /* struct files open RO */
 #endif
         union {
                 const struct file_operations    *i_fop; /* former ->i_op->default_file_ops */
                 void (*free_inode)(struct inode *);
         };
         struct file_lock_context        *i_flctx;
         struct address_space    i_data;
         struct list_head        i_devices;
         union {
                 struct pipe_inode_info  *i_pipe;
                 struct cdev             *i_cdev;
                 char                    *i_link;
                 unsigned                i_dir_seq;
         };
 
 
 #ifdef CONFIG_FSNOTIFY
         __u32                   i_fsnotify_mask; /* all events this inode cares about */
         /* 32-bit hole reserved for expanding i_fsnotify_mask */
         struct fsnotify_mark_connector __rcu    *i_fsnotify_marks;
 #endif
 
 #ifdef CONFIG_FS_ENCRYPTION
         struct fscrypt_inode_info       *i_crypt_info;
 #endif
 
 #ifdef CONFIG_FS_VERITY
         struct fsverity_info    *i_verity_info;
 #endif
 
         void                    *i_private; /* fs or device private pointer */
 } __randomize_layout;
 
 struct timespec64 timestamp_truncate(struct timespec64 t, struct inode *inode);
 
 static inline unsigned int i_blocksize(const struct inode *node)
 {
         return (1 << node->i_blkbits);
 }
 
 static inline int inode_unhashed(struct inode *inode)
 {
         return hlist_unhashed(&inode->i_hash);
 }
 
 /*
  * __mark_inode_dirty expects inodes to be hashed.  Since we don't
  * want special inodes in the fileset inode space, we make them
  * appear hashed, but do not put on any lists.  hlist_del()
  * will work fine and require no locking.
  */
 static inline void inode_fake_hash(struct inode *inode)
 {
         hlist_add_fake(&inode->i_hash);
 }
 
 /*
  * inode->i_mutex nesting subclasses for the lock validator:
  *
  * 0: the object of the current VFS operation
  * 1: parent
  * 2: child/target
  * 3: xattr
  * 4: second non-directory
  * 5: second parent (when locking independent directories in rename)
  *
  * I_MUTEX_NONDIR2 is for certain operations (such as rename) which lock two
  * non-directories at once.
  *
  * The locking order between these classes is
  * parent[2] -> child -> grandchild -> normal -> xattr -> second non-directory
  */
 enum inode_i_mutex_lock_class
 {
         I_MUTEX_NORMAL,
         I_MUTEX_PARENT,
         I_MUTEX_CHILD,
         I_MUTEX_XATTR,
         I_MUTEX_NONDIR2,
         I_MUTEX_PARENT2,
 };
 
 static inline void inode_lock(struct inode *inode)
 {
         down_write(&inode->i_rwsem);
 }
 
 static inline void inode_unlock(struct inode *inode)
 {
         up_write(&inode->i_rwsem);
 }
 
 static inline void inode_lock_shared(struct inode *inode)
 {
         down_read(&inode->i_rwsem);
 }
 
 static inline void inode_unlock_shared(struct inode *inode)
 {
         up_read(&inode->i_rwsem);
 }
 
 static inline int inode_trylock(struct inode *inode)
 {
         return down_write_trylock(&inode->i_rwsem);
 }
 
 static inline int inode_trylock_shared(struct inode *inode)
 {
         return down_read_trylock(&inode->i_rwsem);
 }
 
 static inline int inode_is_locked(struct inode *inode)
 {
         return rwsem_is_locked(&inode->i_rwsem);
 }
 
 static inline void inode_lock_nested(struct inode *inode, unsigned subclass)
 {
         down_write_nested(&inode->i_rwsem, subclass);
 }
 
 static inline void inode_lock_shared_nested(struct inode *inode, unsigned subclass)
 {
         down_read_nested(&inode->i_rwsem, subclass);
 }
 
 static inline void filemap_invalidate_lock(struct address_space *mapping)
 {
         down_write(&mapping->invalidate_lock);
 }
 
 static inline void filemap_invalidate_unlock(struct address_space *mapping)
 {
         up_write(&mapping->invalidate_lock);
 }
 
 static inline void filemap_invalidate_lock_shared(struct address_space *mapping)
 {
         down_read(&mapping->invalidate_lock);
 }
 
 static inline int filemap_invalidate_trylock_shared(
                                         struct address_space *mapping)
 {
         return down_read_trylock(&mapping->invalidate_lock);
 }
 
 static inline void filemap_invalidate_unlock_shared(
                                         struct address_space *mapping)
 {
         up_read(&mapping->invalidate_lock);
 }
 
 void lock_two_nondirectories(struct inode *, struct inode*);
 void unlock_two_nondirectories(struct inode *, struct inode*);
 
 void filemap_invalidate_lock_two(struct address_space *mapping1,
                                  struct address_space *mapping2);
 void filemap_invalidate_unlock_two(struct address_space *mapping1,
                                    struct address_space *mapping2);
 
 
 /*
  * NOTE: in a 32bit arch with a preemptable kernel and
  * an UP compile the i_size_read/write must be atomic
  * with respect to the local cpu (unlike with preempt disabled),
  * but they don't need to be atomic with respect to other cpus like in
  * true SMP (so they need either to either locally disable irq around
  * the read or for example on x86 they can be still implemented as a
  * cmpxchg8b without the need of the lock prefix). For SMP compiles
  * and 64bit archs it makes no difference if preempt is enabled or not.
  */
 static inline loff_t i_size_read(const struct inode *inode)
 {
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
         loff_t i_size;
         unsigned int seq;
 
         do {
                 seq = read_seqcount_begin(&inode->i_size_seqcount);
                 i_size = inode->i_size;
         } while (read_seqcount_retry(&inode->i_size_seqcount, seq));
         return i_size;
 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)
         loff_t i_size;
 
         preempt_disable();
         i_size = inode->i_size;
         preempt_enable();
         return i_size;
 #else
         /* Pairs with smp_store_release() in i_size_write() */
         return smp_load_acquire(&inode->i_size);
 #endif
 }
 
 /*
  * NOTE: unlike i_size_read(), i_size_write() does need locking around it
  * (normally i_mutex), otherwise on 32bit/SMP an update of i_size_seqcount
  * can be lost, resulting in subsequent i_size_read() calls spinning forever.
  */
 static inline void i_size_write(struct inode *inode, loff_t i_size)
 {
 #if BITS_PER_LONG==32 && defined(CONFIG_SMP)
         preempt_disable();
         write_seqcount_begin(&inode->i_size_seqcount);
         inode->i_size = i_size;
         write_seqcount_end(&inode->i_size_seqcount);
         preempt_enable();
 #elif BITS_PER_LONG==32 && defined(CONFIG_PREEMPTION)
         preempt_disable();
         inode->i_size = i_size;
         preempt_enable();
 #else
         /*
          * Pairs with smp_load_acquire() in i_size_read() to ensure
          * changes related to inode size (such as page contents) are
          * visible before we see the changed inode size.
          */
         smp_store_release(&inode->i_size, i_size);
 #endif
 }
 
 static inline unsigned iminor(const struct inode *inode)
 {
         return MINOR(inode->i_rdev);
 }
 
 static inline unsigned imajor(const struct inode *inode)
 {
         return MAJOR(inode->i_rdev);
 }
 
 struct fown_struct {
         rwlock_t lock;          /* protects pid, uid, euid fields */
         struct pid *pid;        /* pid or -pgrp where SIGIO should be sent */
         enum pid_type pid_type; /* Kind of process group SIGIO should be sent to */
         kuid_t uid, euid;       /* uid/euid of process setting the owner */
         int signum;             /* posix.1b rt signal to be delivered on IO */
 };
 
 /**
  * struct file_ra_state - Track a file's readahead state.
  * @start: Where the most recent readahead started.
  * @size: Number of pages read in the most recent readahead.
  * @async_size: Numer of pages that were/are not needed immediately
  *      and so were/are genuinely "ahead".  Start next readahead when
  *      the first of these pages is accessed.
  * @ra_pages: Maximum size of a readahead request, copied from the bdi.
  * @mmap_miss: How many mmap accesses missed in the page cache.
  * @prev_pos: The last byte in the most recent read request.
  *
  * When this structure is passed to ->readahead(), the "most recent"
  * readahead means the current readahead.
  */
 struct file_ra_state {
         pgoff_t start;
         unsigned int size;
         unsigned int async_size;
         unsigned int ra_pages;
         unsigned int mmap_miss;
         loff_t prev_pos;
 };
 
 /*
  * Check if @index falls in the readahead windows.
  */
 static inline int ra_has_index(struct file_ra_state *ra, pgoff_t index)
 {
         return (index >= ra->start &&
                 index <  ra->start + ra->size);
 }
 
 /*
  * f_{lock,count,pos_lock} members can be highly contended and share
  * the same cacheline. f_{lock,mode} are very frequently used together
  * and so share the same cacheline as well. The read-mostly
  * f_{path,inode,op} are kept on a separate cacheline.
  */
 struct file {
         union {
                 /* fput() uses task work when closing and freeing file (default). */
                 struct callback_head    f_task_work;
                 /* fput() must use workqueue (most kernel threads). */
                 struct llist_node       f_llist;
                 unsigned int            f_iocb_flags;
         };
 
         /*
          * Protects f_ep, f_flags.
          * Must not be taken from IRQ context.
          */
         spinlock_t              f_lock;
         fmode_t                 f_mode;
         atomic_long_t           f_count;
         struct mutex            f_pos_lock;
         loff_t                  f_pos;
         unsigned int            f_flags;
         struct fown_struct      f_owner;
         const struct cred       *f_cred;
         struct file_ra_state    f_ra;
         struct path             f_path;
         struct inode            *f_inode;       /* cached value */
         const struct file_operations    *f_op;
 
         u64                     f_version;
 #ifdef CONFIG_SECURITY
         void                    *f_security;
 #endif
         /* needed for tty driver, and maybe others */
         void                    *private_data;
 
 #ifdef CONFIG_EPOLL
         /* Used by fs/eventpoll.c to link all the hooks to this file */
         struct hlist_head       *f_ep;
 #endif /* #ifdef CONFIG_EPOLL */
         struct address_space    *f_mapping;
         errseq_t                f_wb_err;
         errseq_t                f_sb_err; /* for syncfs */
 } __randomize_layout
   __attribute__((aligned(4)));  /* lest something weird decides that 2 is OK */
 
 struct file_handle {
         __u32 handle_bytes;
         int handle_type;
         /* file identifier */
         unsigned char f_handle[] __counted_by(handle_bytes);
 };
 
 static inline struct file *get_file(struct file *f)
 {
         long prior = atomic_long_fetch_inc_relaxed(&f->f_count);
         WARN_ONCE(!prior, "struct file::f_count incremented from zero; use-after-free condition present!\n");
         return f;
 }
 
 struct file *get_file_rcu(struct file __rcu **f);
 struct file *get_file_active(struct file **f);
 
 #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
 
 /* legacy typedef, should eventually be removed */
 typedef void *fl_owner_t;
 
 struct file_lock;
 struct file_lease;
 
 /* The following constant reflects the upper bound of the file/locking space */
 #ifndef OFFSET_MAX
 #define OFFSET_MAX      type_max(loff_t)
 #define OFFT_OFFSET_MAX type_max(off_t)
 #endif
 
 extern void send_sigio(struct fown_struct *fown, int fd, int band);
 
 static inline struct inode *file_inode(const struct file *f)
 {
         return f->f_inode;
 }
 
 /*
  * file_dentry() is a relic from the days that overlayfs was using files with a
  * "fake" path, meaning, f_path on overlayfs and f_inode on underlying fs.
  * In those days, file_dentry() was needed to get the underlying fs dentry that
  * matches f_inode.
  * Files with "fake" path should not exist nowadays, so use an assertion to make
  * sure that file_dentry() was not papering over filesystem bugs.
  */
 static inline struct dentry *file_dentry(const struct file *file)
 {
         struct dentry *dentry = file->f_path.dentry;
 
         WARN_ON_ONCE(d_inode(dentry) != file_inode(file));
         return dentry;
 }
 
 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, int who, 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       BIT(0)  /* Mount read-only */
 #define SB_NOSUID       BIT(1)  /* Ignore suid and sgid bits */
 #define SB_NODEV        BIT(2)  /* Disallow access to device special files */
 #define SB_NOEXEC       BIT(3)  /* Disallow program execution */
 #define SB_SYNCHRONOUS  BIT(4)  /* Writes are synced at once */
 #define SB_MANDLOCK     BIT(6)  /* Allow mandatory locks on an FS */
 #define SB_DIRSYNC      BIT(7)  /* Directory modifications are synchronous */
 #define SB_NOATIME      BIT(10) /* Do not update access times. */
 #define SB_NODIRATIME   BIT(11) /* Do not update directory access times */
 #define SB_SILENT       BIT(15)
 #define SB_POSIXACL     BIT(16) /* Supports POSIX ACLs */
 #define SB_INLINECRYPT  BIT(17) /* Use blk-crypto for encrypted files */
 #define SB_KERNMOUNT    BIT(22) /* this is a kern_mount call */
 #define SB_I_VERSION    BIT(23) /* Update inode I_version field */
 #define SB_LAZYTIME     BIT(25) /* Update the on-disk [acm]times lazily */
 
 /* These sb flags are internal to the kernel */
 #define SB_DEAD         BIT(21)
 #define SB_DYING        BIT(24)
 #define SB_SUBMOUNT     BIT(26)
 #define SB_FORCE        BIT(27)
 #define SB_NOSEC        BIT(28)
 #define SB_BORN         BIT(29)
 #define SB_ACTIVE       BIT(30)
 #define SB_NOUSER       BIT(31)
 
 /* These flags relate to encoding and casefolding */
 #define SB_ENC_STRICT_MODE_FL   (1 << 0)
 
 #define sb_has_strict_encoding(sb) \
         (sb->s_encoding_flags & SB_ENC_STRICT_MODE_FL)
 
 /*
  *      Umount options
  */
 
 #define MNT_FORCE       0x00000001      /* Attempt to forcibily umount */
 #define MNT_DETACH      0x00000002      /* Just detach from the tree */
 #define MNT_EXPIRE      0x00000004      /* Mark for expiry */
 #define UMOUNT_NOFOLLOW 0x00000008      /* Don't follow symlink on umount */
 #define UMOUNT_UNUSED   0x80000000      /* Flag guaranteed to be unused */
 
 /* sb->s_iflags */
 #define SB_I_CGROUPWB   0x00000001      /* cgroup-aware writeback enabled */
 #define SB_I_NOEXEC     0x00000002      /* Ignore executables on this fs */
 #define SB_I_NODEV      0x00000004      /* Ignore devices on this fs */
 #define SB_I_STABLE_WRITES 0x00000008   /* don't modify blks until WB is done */
 
 /* sb->s_iflags to limit user namespace mounts */
 #define SB_I_USERNS_VISIBLE             0x00000010 /* fstype already mounted */
 #define SB_I_IMA_UNVERIFIABLE_SIGNATURE 0x00000020
 #define SB_I_UNTRUSTED_MOUNTER          0x00000040
 #define SB_I_EVM_HMAC_UNSUPPORTED       0x00000080
 
 #define SB_I_SKIP_SYNC  0x00000100      /* Skip superblock at global sync */
 #define SB_I_PERSB_BDI  0x00000200      /* has a per-sb bdi */
 #define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */
 #define SB_I_RETIRED    0x00000800      /* superblock shouldn't be reused */
 #define SB_I_NOUMASK    0x00001000      /* VFS does not apply umask */
 
 /* 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 {
         unsigned short                  frozen;         /* Is sb frozen? */
         int                             freeze_kcount;  /* How many kernel freeze requests? */
         int                             freeze_ucount;  /* How many userspace freeze requests? */
         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 * const *s_xattr;
 #ifdef CONFIG_FS_ENCRYPTION
         const struct fscrypt_operations *s_cop;
         struct fscrypt_keyring  *s_master_keys; /* master crypto keys in use */
 #endif
 #ifdef CONFIG_FS_VERITY
         const struct fsverity_operations *s_vop;
 #endif
 #if IS_ENABLED(CONFIG_UNICODE)
         struct unicode_map *s_encoding;
         __u16 s_encoding_flags;
 #endif
         struct hlist_bl_head    s_roots;        /* alternate root dentries for NFS */
         struct list_head        s_mounts;       /* list of mounts; _not_ for fs use */
         struct block_device     *s_bdev;        /* can go away once we use an accessor for @s_bdev_file */
         struct file             *s_bdev_file;
         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_info 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_sb_info *s_fsnotify_info;
 #endif
 
         /*
          * q: why are s_id and s_sysfs_name not the same? both are human
          * readable strings that identify the filesystem
          * a: s_id is allowed to change at runtime; it's used in log messages,
          * and we want to when a device starts out as single device (s_id is dev
          * name) but then a device is hot added and we have to switch to
          * identifying it by UUID
          * but s_sysfs_name is a handle for programmatic access, and can't
          * change at runtime
          */
         char                    s_id[32];       /* Informational name */
         uuid_t                  s_uuid;         /* UUID */
         u8                      s_uuid_len;     /* Default 16, possibly smaller for weird filesystems */
 
         /* if set, fs shows up under sysfs at /sys/fs/$FSTYP/s_sysfs_name */
         char                    s_sysfs_name[UUID_STRING_LEN + 1];
 
         unsigned int            s_max_links;
 
         /*
          * The next field is for VFS *only*. No filesystems have any business
          * even looking at it. You had been warned.
          */
         struct mutex s_vfs_rename_mutex;        /* Kludge */
 
         /*
          * Filesystem subtype.  If non-empty the filesystem type field
          * in /proc/mounts will be "type.subtype"
          */
         const char *s_subtype;
 
         const struct dentry_operations *s_d_op; /* default d_op for dentries */
 
         struct shrinker *s_shrink;      /* per-sb shrinker handle */
 
         /* Number of inodes with nlink == 0 but still referenced */
         atomic_long_t s_remove_count;
 
         /* Read-only state of the superblock is being changed */
         int s_readonly_remount;
 
         /* per-sb errseq_t for reporting writeback errors via syncfs */
         errseq_t s_wb_err;
 
         /* AIO completions deferred from interrupt context */
         struct workqueue_struct *s_dio_done_wq;
         struct hlist_head s_pins;
 
         /*
          * Owning user namespace and default context in which to
          * interpret filesystem uids, gids, quotas, device nodes,
          * xattrs and security labels.
          */
         struct user_namespace *s_user_ns;
 
         /*
          * The list_lru structure is essentially just a pointer to a table
          * of per-node lru lists, each of which has its own spinlock.
          * There is no need to put them into separate cachelines.
          */
         struct list_lru         s_dentry_lru;
         struct list_lru         s_inode_lru;
         struct rcu_head         rcu;
         struct work_struct      destroy_work;
 
         struct mutex            s_sync_lock;    /* sync serialisation lock */
 
         /*
          * Indicates how deep in a filesystem stack this SB is
          */
         int s_stack_depth;
 
         /* s_inode_list_lock protects s_inodes */
         spinlock_t              s_inode_list_lock ____cacheline_aligned_in_smp;
         struct list_head        s_inodes;       /* all inodes */
 
         spinlock_t              s_inode_wblist_lock;
         struct list_head        s_inodes_wb;    /* writeback inodes */
 } __randomize_layout;
 
 static inline struct user_namespace *i_user_ns(const struct inode *inode)
 {
         return inode->i_sb->s_user_ns;
 }
 
 /* Helper functions so that in most cases filesystems will
  * not need to deal directly with kuid_t and kgid_t and can
  * instead deal with the raw numeric values that are stored
  * in the filesystem.
  */
 static inline uid_t i_uid_read(const struct inode *inode)
 {
         return from_kuid(i_user_ns(inode), inode->i_uid);
 }
 
 static inline gid_t i_gid_read(const struct inode *inode)
 {
         return from_kgid(i_user_ns(inode), inode->i_gid);
 }
 
 static inline void i_uid_write(struct inode *inode, uid_t uid)
 {
         inode->i_uid = make_kuid(i_user_ns(inode), uid);
 }
 
 static inline void i_gid_write(struct inode *inode, gid_t gid)
 {
         inode->i_gid = make_kgid(i_user_ns(inode), gid);
 }
 
 /**
  * i_uid_into_vfsuid - map an inode's i_uid down according to an idmapping
  * @idmap: idmap of the mount the inode was found from
  * @inode: inode to map
  *
  * Return: whe inode's i_uid mapped down according to @idmap.
  * If the inode's i_uid has no mapping INVALID_VFSUID is returned.
  */
 static inline vfsuid_t i_uid_into_vfsuid(struct mnt_idmap *idmap,
                                          const struct inode *inode)
 {
         return make_vfsuid(idmap, i_user_ns(inode), inode->i_uid);
 }
 
 /**
  * i_uid_needs_update - check whether inode's i_uid needs to be updated
  * @idmap: idmap of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Check whether the $inode's i_uid field needs to be updated taking idmapped
  * mounts into account if the filesystem supports it.
  *
  * Return: true if @inode's i_uid field needs to be updated, false if not.
  */
 static inline bool i_uid_needs_update(struct mnt_idmap *idmap,
                                       const struct iattr *attr,
                                       const struct inode *inode)
 {
         return ((attr->ia_valid & ATTR_UID) &&
                 !vfsuid_eq(attr->ia_vfsuid,
                            i_uid_into_vfsuid(idmap, inode)));
 }
 
 /**
  * i_uid_update - update @inode's i_uid field
  * @idmap: idmap of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Safely update @inode's i_uid field translating the vfsuid of any idmapped
  * mount into the filesystem kuid.
  */
 static inline void i_uid_update(struct mnt_idmap *idmap,
                                 const struct iattr *attr,
                                 struct inode *inode)
 {
         if (attr->ia_valid & ATTR_UID)
                 inode->i_uid = from_vfsuid(idmap, i_user_ns(inode),
                                            attr->ia_vfsuid);
 }
 
 /**
  * i_gid_into_vfsgid - map an inode's i_gid down according to an idmapping
  * @idmap: idmap of the mount the inode was found from
  * @inode: inode to map
  *
  * Return: the inode's i_gid mapped down according to @idmap.
  * If the inode's i_gid has no mapping INVALID_VFSGID is returned.
  */
 static inline vfsgid_t i_gid_into_vfsgid(struct mnt_idmap *idmap,
                                          const struct inode *inode)
 {
         return make_vfsgid(idmap, i_user_ns(inode), inode->i_gid);
 }
 
 /**
  * i_gid_needs_update - check whether inode's i_gid needs to be updated
  * @idmap: idmap of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Check whether the $inode's i_gid field needs to be updated taking idmapped
  * mounts into account if the filesystem supports it.
  *
  * Return: true if @inode's i_gid field needs to be updated, false if not.
  */
 static inline bool i_gid_needs_update(struct mnt_idmap *idmap,
                                       const struct iattr *attr,
                                       const struct inode *inode)
 {
         return ((attr->ia_valid & ATTR_GID) &&
                 !vfsgid_eq(attr->ia_vfsgid,
                            i_gid_into_vfsgid(idmap, inode)));
 }
 
 /**
  * i_gid_update - update @inode's i_gid field
  * @idmap: idmap of the mount the inode was found from
  * @attr: the new attributes of @inode
  * @inode: the inode to update
  *
  * Safely update @inode's i_gid field translating the vfsgid of any idmapped
  * mount into the filesystem kgid.
  */
 static inline void i_gid_update(struct mnt_idmap *idmap,
                                 const struct iattr *attr,
                                 struct inode *inode)
 {
         if (attr->ia_valid & ATTR_GID)
                 inode->i_gid = from_vfsgid(idmap, i_user_ns(inode),
                                            attr->ia_vfsgid);
 }
 
 /**
  * inode_fsuid_set - initialize inode's i_uid field with callers fsuid
  * @inode: inode to initialize
  * @idmap: idmap of the mount the inode was found from
  *
  * Initialize the i_uid field of @inode. If the inode was found/created via
  * an idmapped mount map the caller's fsuid according to @idmap.
  */
 static inline void inode_fsuid_set(struct inode *inode,
                                    struct mnt_idmap *idmap)
 {
         inode->i_uid = mapped_fsuid(idmap, i_user_ns(inode));
 }
 
 /**
  * inode_fsgid_set - initialize inode's i_gid field with callers fsgid
  * @inode: inode to initialize
  * @idmap: idmap of the mount the inode was found from
  *
  * Initialize the i_gid field of @inode. If the inode was found/created via
  * an idmapped mount map the caller's fsgid according to @idmap.
  */
 static inline void inode_fsgid_set(struct inode *inode,
                                    struct mnt_idmap *idmap)
 {
         inode->i_gid = mapped_fsgid(idmap, i_user_ns(inode));
 }
 
 /**
  * fsuidgid_has_mapping() - check whether caller's fsuid/fsgid is mapped
  * @sb: the superblock we want a mapping in
  * @idmap: idmap of the relevant mount
  *
  * Check whether the caller's fsuid and fsgid have a valid mapping in the
  * s_user_ns of the superblock @sb. If the caller is on an idmapped mount map
  * the caller's fsuid and fsgid according to the @idmap first.
  *
  * Return: true if fsuid and fsgid is mapped, false if not.
  */
 static inline bool fsuidgid_has_mapping(struct super_block *sb,
                                         struct mnt_idmap *idmap)
 {
         struct user_namespace *fs_userns = sb->s_user_ns;
         kuid_t kuid;
         kgid_t kgid;
 
         kuid = mapped_fsuid(idmap, fs_userns);
         if (!uid_valid(kuid))
                 return false;
         kgid = mapped_fsgid(idmap, fs_userns);
         if (!gid_valid(kgid))
                 return false;
         return kuid_has_mapping(fs_userns, kuid) &&
                kgid_has_mapping(fs_userns, kgid);
 }
 
 struct timespec64 current_time(struct inode *inode);
 struct timespec64 inode_set_ctime_current(struct inode *inode);
 
 static inline time64_t inode_get_atime_sec(const struct inode *inode)
 {
         return inode->i_atime_sec;
 }
 
 static inline long inode_get_atime_nsec(const struct inode *inode)
 {
         return inode->i_atime_nsec;
 }
 
 static inline struct timespec64 inode_get_atime(const struct inode *inode)
 {
         struct timespec64 ts = { .tv_sec  = inode_get_atime_sec(inode),
                                  .tv_nsec = inode_get_atime_nsec(inode) };
 
         return ts;
 }
 
 static inline struct timespec64 inode_set_atime_to_ts(struct inode *inode,
                                                       struct timespec64 ts)
 {
         inode->i_atime_sec = ts.tv_sec;
         inode->i_atime_nsec = ts.tv_nsec;
         return ts;
 }
 
 static inline struct timespec64 inode_set_atime(struct inode *inode,
                                                 time64_t sec, long nsec)
 {
         struct timespec64 ts = { .tv_sec  = sec,
                                  .tv_nsec = nsec };
 
         return inode_set_atime_to_ts(inode, ts);
 }
 
 static inline time64_t inode_get_mtime_sec(const struct inode *inode)
 {
         return inode->i_mtime_sec;
 }
 
 static inline long inode_get_mtime_nsec(const struct inode *inode)
 {
         return inode->i_mtime_nsec;
 }
 
 static inline struct timespec64 inode_get_mtime(const struct inode *inode)
 {
         struct timespec64 ts = { .tv_sec  = inode_get_mtime_sec(inode),
                                  .tv_nsec = inode_get_mtime_nsec(inode) };
         return ts;
 }
 
 static inline struct timespec64 inode_set_mtime_to_ts(struct inode *inode,
                                                       struct timespec64 ts)
 {
         inode->i_mtime_sec = ts.tv_sec;
         inode->i_mtime_nsec = ts.tv_nsec;
         return ts;
 }
 
 static inline struct timespec64 inode_set_mtime(struct inode *inode,
                                                 time64_t sec, long nsec)
 {
         struct timespec64 ts = { .tv_sec  = sec,
                                  .tv_nsec = nsec };
         return inode_set_mtime_to_ts(inode, ts);
 }
 
 static inline time64_t inode_get_ctime_sec(const struct inode *inode)
 {
         return inode->i_ctime_sec;
 }
 
 static inline long inode_get_ctime_nsec(const struct inode *inode)
 {
         return inode->i_ctime_nsec;
 }
 
 static inline struct timespec64 inode_get_ctime(const struct inode *inode)
 {
         struct timespec64 ts = { .tv_sec  = inode_get_ctime_sec(inode),
                                  .tv_nsec = inode_get_ctime_nsec(inode) };
 
         return ts;
 }
 
 static inline struct timespec64 inode_set_ctime_to_ts(struct inode *inode,
                                                       struct timespec64 ts)
 {
         inode->i_ctime_sec = ts.tv_sec;
         inode->i_ctime_nsec = ts.tv_nsec;
         return ts;
 }
 
 /**
  * inode_set_ctime - set the ctime in the inode
  * @inode: inode in which to set the ctime
  * @sec: tv_sec value to set
  * @nsec: tv_nsec value to set
  *
  * Set the ctime in @inode to { @sec, @nsec }
  */
 static inline struct timespec64 inode_set_ctime(struct inode *inode,
                                                 time64_t sec, long nsec)
 {
         struct timespec64 ts = { .tv_sec  = sec,
                                  .tv_nsec = nsec };
 
         return inode_set_ctime_to_ts(inode, ts);
 }
 
 struct timespec64 simple_inode_init_ts(struct inode *inode);
 
 /*
  * Snapshotting support.
  */
 
 /*
  * These are internal functions, please use sb_start_{write,pagefault,intwrite}
  * instead.
  */
 static inline void __sb_end_write(struct super_block *sb, int level)
 {
         percpu_up_read(sb->s_writers.rw_sem + level-1);
 }
 
 static inline void __sb_start_write(struct super_block *sb, int level)
 {
         percpu_down_read(sb->s_writers.rw_sem + level - 1);
 }
 
 static inline bool __sb_start_write_trylock(struct super_block *sb, int level)
 {
         return percpu_down_read_trylock(sb->s_writers.rw_sem + level - 1);
 }
 
 #define __sb_writers_acquired(sb, lev)  \
         percpu_rwsem_acquire(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)
 #define __sb_writers_release(sb, lev)   \
         percpu_rwsem_release(&(sb)->s_writers.rw_sem[(lev)-1], 1, _THIS_IP_)
 
 /**
  * __sb_write_started - check if sb freeze level is held
  * @sb: the super we write to
  * @level: the freeze level
  *
  * * > 0 - sb freeze level is held
  * *   0 - sb freeze level is not held
  * * < 0 - !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN
  */
 static inline int __sb_write_started(const struct super_block *sb, int level)
 {
         return lockdep_is_held_type(sb->s_writers.rw_sem + level - 1, 1);
 }
 
 /**
  * sb_write_started - check if SB_FREEZE_WRITE is held
  * @sb: the super we write to
  *
  * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN.
  */
 static inline bool sb_write_started(const struct super_block *sb)
 {
         return __sb_write_started(sb, SB_FREEZE_WRITE);
 }
 
 /**
  * sb_write_not_started - check if SB_FREEZE_WRITE is not held
  * @sb: the super we write to
  *
  * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN.
  */
 static inline bool sb_write_not_started(const struct super_block *sb)
 {
         return __sb_write_started(sb, SB_FREEZE_WRITE) <= 0;
 }
 
 /**
  * file_write_started - check if SB_FREEZE_WRITE is held
  * @file: the file we write to
  *
  * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN.
  * May be false positive with !S_ISREG, because file_start_write() has
  * no effect on !S_ISREG.
  */
 static inline bool file_write_started(const struct file *file)
 {
         if (!S_ISREG(file_inode(file)->i_mode))
                 return true;
         return sb_write_started(file_inode(file)->i_sb);
 }
 
 /**
  * file_write_not_started - check if SB_FREEZE_WRITE is not held
  * @file: the file we write to
  *
  * May be false positive with !CONFIG_LOCKDEP/LOCK_STATE_UNKNOWN.
  * May be false positive with !S_ISREG, because file_start_write() has
  * no effect on !S_ISREG.
  */
 static inline bool file_write_not_started(const struct file *file)
 {
         if (!S_ISREG(file_inode(file)->i_mode))
                 return true;
         return sb_write_not_started(file_inode(file)->i_sb);
 }
 
 /**
  * sb_end_write - drop write access to a superblock
  * @sb: the super we wrote to
  *
  * Decrement number of writers to the filesystem. Wake up possible waiters
  * wanting to freeze the filesystem.
  */
 static inline void sb_end_write(struct super_block *sb)
 {
         __sb_end_write(sb, SB_FREEZE_WRITE);
 }
 
 /**
  * sb_end_pagefault - drop write access to a superblock from a page fault
  * @sb: the super we wrote to
  *
  * Decrement number of processes handling write page fault to the filesystem.
  * Wake up possible waiters wanting to freeze the filesystem.
  */
 static inline void sb_end_pagefault(struct super_block *sb)
 {
         __sb_end_write(sb, SB_FREEZE_PAGEFAULT);
 }
 
 /**
  * sb_end_intwrite - drop write access to a superblock for internal fs purposes
  * @sb: the super we wrote to
  *
  * Decrement fs-internal number of writers to the filesystem.  Wake up possible
  * waiters wanting to freeze the filesystem.
  */
 static inline void sb_end_intwrite(struct super_block *sb)
 {
         __sb_end_write(sb, SB_FREEZE_FS);
 }
 
 /**
  * sb_start_write - get write access to a superblock
  * @sb: the super we write to
  *
  * When a process wants to write data or metadata to a file system (i.e. dirty
  * a page or an inode), it should embed the operation in a sb_start_write() -
  * sb_end_write() pair to get exclusion against file system freezing. This
  * function increments number of writers preventing freezing. If the file
  * system is already frozen, the function waits until the file system is
  * thawed.
  *
  * Since freeze protection behaves as a lock, users have to preserve
  * ordering of freeze protection and other filesystem locks. Generally,
  * freeze protection should be the outermost lock. In particular, we have:
  *
  * sb_start_write
  *   -> i_mutex                 (write path, truncate, directory ops, ...)
  *   -> s_umount                (freeze_super, thaw_super)
  */
 static inline void sb_start_write(struct super_block *sb)
 {
         __sb_start_write(sb, SB_FREEZE_WRITE);
 }
 
 static inline bool sb_start_write_trylock(struct super_block *sb)
 {
         return __sb_start_write_trylock(sb, SB_FREEZE_WRITE);
 }
 
 /**
  * sb_start_pagefault - get write access to a superblock from a page fault
  * @sb: the super we write to
  *
  * When a process starts handling write page fault, it should embed the
  * operation into sb_start_pagefault() - sb_end_pagefault() pair to get
  * exclusion against file system freezing. This is needed since the page fault
  * is going to dirty a page. This function increments number of running page
  * faults preventing freezing. If the file system is already frozen, the
  * function waits until the file system is thawed.
  *
  * Since page fault freeze protection behaves as a lock, users have to preserve
  * ordering of freeze protection and other filesystem locks. It is advised to
  * put sb_start_pagefault() close to mmap_lock in lock ordering. Page fault
  * handling code implies lock dependency:
  *
  * mmap_lock
  *   -> sb_start_pagefault
  */
 static inline void sb_start_pagefault(struct super_block *sb)
 {
         __sb_start_write(sb, SB_FREEZE_PAGEFAULT);
 }
 
 /**
  * sb_start_intwrite - get write access to a superblock for internal fs purposes
  * @sb: the super we write to
  *
  * This is the third level of protection against filesystem freezing. It is
  * free for use by a filesystem. The only requirement is that it must rank
  * below sb_start_pagefault.
  *
  * For example filesystem can call sb_start_intwrite() when starting a
  * transaction which somewhat eases handling of freezing for internal sources
  * of filesystem changes (internal fs threads, discarding preallocation on file
  * close, etc.).
  */
 static inline void sb_start_intwrite(struct super_block *sb)
 {
         __sb_start_write(sb, SB_FREEZE_FS);
 }
 
 static inline bool sb_start_intwrite_trylock(struct super_block *sb)
 {
         return __sb_start_write_trylock(sb, SB_FREEZE_FS);
 }
 
 bool inode_owner_or_capable(struct mnt_idmap *idmap,
                             const struct inode *inode);
 
 /*
  * VFS helper functions..
  */
 int vfs_create(struct mnt_idmap *, struct inode *,
                struct dentry *, umode_t, bool);
 int vfs_mkdir(struct mnt_idmap *, struct inode *,
               struct dentry *, umode_t);
 int vfs_mknod(struct mnt_idmap *, struct inode *, struct dentry *,
               umode_t, dev_t);
 int vfs_symlink(struct mnt_idmap *, struct inode *,
                 struct dentry *, const char *);
 int vfs_link(struct dentry *, struct mnt_idmap *, struct inode *,
              struct dentry *, struct inode **);
 int vfs_rmdir(struct mnt_idmap *, struct inode *, struct dentry *);
 int vfs_unlink(struct mnt_idmap *, struct inode *, struct dentry *,
                struct inode **);
 
 /**
  * struct renamedata - contains all information required for renaming
  * @old_mnt_idmap:     idmap of the old mount the inode was found from
  * @old_dir:           parent of source
  * @old_dentry:                source
  * @new_mnt_idmap:     idmap of the new mount the inode was found from
  * @new_dir:           parent of destination
  * @new_dentry:                destination
  * @delegated_inode:   returns an inode needing a delegation break
  * @flags:             rename flags
  */
 struct renamedata {
         struct mnt_idmap *old_mnt_idmap;
         struct inode *old_dir;
         struct dentry *old_dentry;
         struct mnt_idmap *new_mnt_idmap;
         struct inode *new_dir;
         struct dentry *new_dentry;
         struct inode **delegated_inode;
         unsigned int flags;
 } __randomize_layout;
 
 int vfs_rename(struct renamedata *);
 
 static inline int vfs_whiteout(struct mnt_idmap *idmap,
                                struct inode *dir, struct dentry *dentry)
 {
         return vfs_mknod(idmap, dir, dentry, S_IFCHR | WHITEOUT_MODE,
                          WHITEOUT_DEV);
 }
 
 struct file *kernel_tmpfile_open(struct mnt_idmap *idmap,
                                  const struct path *parentpath,
                                  umode_t mode, int open_flag,
                                  const struct cred *cred);
 struct file *kernel_file_open(const struct path *path, int flags,
                               const struct cred *cred);
 
 int vfs_mkobj(struct dentry *, umode_t,
                 int (*f)(struct dentry *, umode_t, void *),
                 void *);
 
 int vfs_fchown(struct file *file, uid_t user, gid_t group);
 int vfs_fchmod(struct file *file, umode_t mode);
 int vfs_utimes(const struct path *path, struct timespec64 *times);
 
 extern long vfs_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 
 #ifdef CONFIG_COMPAT
 extern long compat_ptr_ioctl(struct file *file, unsigned int cmd,
                                         unsigned long arg);
 #else
 #define compat_ptr_ioctl NULL
 #endif
 
 /*
  * VFS file helper functions.
  */
 void inode_init_owner(struct mnt_idmap *idmap, struct inode *inode,
                       const struct inode *dir, umode_t mode);
 extern bool may_open_dev(const struct path *path);
 umode_t mode_strip_sgid(struct mnt_idmap *idmap,
                         const struct inode *dir, umode_t mode);
 bool in_group_or_capable(struct mnt_idmap *idmap,
                          const struct inode *inode, vfsgid_t vfsgid);
 
 /*
  * 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.
  * Return 'true' to keep going and 'false' if there are no more entries.
  */
 struct dir_context;
 typedef bool (*filldir_t)(struct dir_context *, const char *, int, loff_t, u64,
                          unsigned);
 
 struct dir_context {
         filldir_t actor;
         loff_t pos;
 };
 
 /*
  * These flags let !MMU mmap() govern direct device mapping vs immediate
  * copying more easily for MAP_PRIVATE, especially for ROM filesystems.
  *
  * NOMMU_MAP_COPY:      Copy can be mapped (MAP_PRIVATE)
  * NOMMU_MAP_DIRECT:    Can be mapped directly (MAP_SHARED)
  * NOMMU_MAP_READ:      Can be mapped for reading
  * NOMMU_MAP_WRITE:     Can be mapped for writing
  * NOMMU_MAP_EXEC:      Can be mapped for execution
  */
 #define NOMMU_MAP_COPY          0x00000001
 #define NOMMU_MAP_DIRECT        0x00000008
 #define NOMMU_MAP_READ          VM_MAYREAD
 #define NOMMU_MAP_WRITE         VM_MAYWRITE
 #define NOMMU_MAP_EXEC          VM_MAYEXEC
 
 #define NOMMU_VMFLAGS \
         (NOMMU_MAP_READ | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC)
 
 /*
  * These flags control the behavior of the remap_file_range function pointer.
  * If it is called with len == 0 that means "remap to end of source file".
  * See Documentation/filesystems/vfs.rst for more details about this call.
  *
  * REMAP_FILE_DEDUP: only remap if contents identical (i.e. deduplicate)
  * REMAP_FILE_CAN_SHORTEN: caller can handle a shortened request
  */
 #define REMAP_FILE_DEDUP                (1 << 0)
 #define REMAP_FILE_CAN_SHORTEN          (1 << 1)
 
 /*
  * These flags signal that the caller is ok with altering various aspects of
  * the behavior of the remap operation.  The changes must be made by the
  * implementation; the vfs remap helper functions can take advantage of them.
  * Flags in this category exist to preserve the quirky behavior of the hoisted
  * btrfs clone/dedupe ioctls.
  */
 #define REMAP_FILE_ADVISORY             (REMAP_FILE_CAN_SHORTEN)
 
 /*
  * These flags control the behavior of vfs_copy_file_range().
  * They are not available to the user via syscall.
  *
  * COPY_FILE_SPLICE: call splice direct instead of fs clone/copy ops
  */
 #define COPY_FILE_SPLICE                (1 << 0)
 
 struct iov_iter;
 struct io_uring_cmd;
 struct offset_ctx;
 
 typedef unsigned int __bitwise fop_flags_t;
 
 struct file_operations {
         struct module *owner;
         fop_flags_t fop_flags;
         loff_t (*llseek) (struct file *, loff_t, int);
         ssize_t (*read) (struct file *, char __user *, size_t, loff_t *);
         ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
         ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
         ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
         int (*iopoll)(struct kiocb *kiocb, struct io_comp_batch *,
                         unsigned int flags);
         int (*iterate_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 *);
         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 *);
         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);
         void (*splice_eof)(struct file *file);
         int (*setlease)(struct file *, int, struct file_lease **, void **);
         long (*fallocate)(struct file *file, int mode, loff_t offset,
                           loff_t len);
         void (*show_fdinfo)(struct seq_file *m, struct file *f);
 #ifndef CONFIG_MMU
         unsigned (*mmap_capabilities)(struct file *);
 #endif
         ssize_t (*copy_file_range)(struct file *, loff_t, struct file *,
                         loff_t, size_t, unsigned int);
         loff_t (*remap_file_range)(struct file *file_in, loff_t pos_in,
                                    struct file *file_out, loff_t pos_out,
                                    loff_t len, unsigned int remap_flags);
         int (*fadvise)(struct file *, loff_t, loff_t, int);
         int (*uring_cmd)(struct io_uring_cmd *ioucmd, unsigned int issue_flags);
         int (*uring_cmd_iopoll)(struct io_uring_cmd *, struct io_comp_batch *,
                                 unsigned int poll_flags);
 } __randomize_layout;
 
 /* Supports async buffered reads */
 #define FOP_BUFFER_RASYNC       ((__force fop_flags_t)(1 << 0))
 /* Supports async buffered writes */
 #define FOP_BUFFER_WASYNC       ((__force fop_flags_t)(1 << 1))
 /* Supports synchronous page faults for mappings */
 #define FOP_MMAP_SYNC           ((__force fop_flags_t)(1 << 2))
 /* Supports non-exclusive O_DIRECT writes from multiple threads */
 #define FOP_DIO_PARALLEL_WRITE  ((__force fop_flags_t)(1 << 3))
 /* Contains huge pages */
 #define FOP_HUGE_PAGES          ((__force fop_flags_t)(1 << 4))
 
 /* Wrap a directory iterator that needs exclusive inode access */
 int wrap_directory_iterator(struct file *, struct dir_context *,
                             int (*) (struct file *, struct dir_context *));
 #define WRAP_DIR_ITER(x) \
         static int shared_##x(struct file *file , struct dir_context *ctx) \
         { return wrap_directory_iterator(file, ctx, x); }
 
 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 mnt_idmap *, struct inode *, int);
         struct posix_acl * (*get_inode_acl)(struct inode *, int, bool);
 
         int (*readlink) (struct dentry *, char __user *,int);
 
         int (*create) (struct mnt_idmap *, struct inode *,struct dentry *,
                        umode_t, bool);
         int (*link) (struct dentry *,struct inode *,struct dentry *);
         int (*unlink) (struct inode *,struct dentry *);
         int (*symlink) (struct mnt_idmap *, struct inode *,struct dentry *,
                         const char *);
         int (*mkdir) (struct mnt_idmap *, struct inode *,struct dentry *,
                       umode_t);
         int (*rmdir) (struct inode *,struct dentry *);
         int (*mknod) (struct mnt_idmap *, struct inode *,struct dentry *,
                       umode_t,dev_t);
         int (*rename) (struct mnt_idmap *, struct inode *, struct dentry *,
                         struct inode *, struct dentry *, unsigned int);
         int (*setattr) (struct mnt_idmap *, struct dentry *, struct iattr *);
         int (*getattr) (struct mnt_idmap *, 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 *, int);
         int (*atomic_open)(struct inode *, struct dentry *,
                            struct file *, unsigned open_flag,
                            umode_t create_mode);
         int (*tmpfile) (struct mnt_idmap *, struct inode *,
                         struct file *, umode_t);
         struct posix_acl *(*get_acl)(struct mnt_idmap *, struct dentry *,
                                      int);
         int (*set_acl)(struct mnt_idmap *, struct dentry *,
                        struct posix_acl *, int);
         int (*fileattr_set)(struct mnt_idmap *idmap,
                             struct dentry *dentry, struct fileattr *fa);
         int (*fileattr_get)(struct dentry *dentry, struct fileattr *fa);
         struct offset_ctx *(*get_offset_ctx)(struct inode *inode);
 } ____cacheline_aligned;
 
 static inline int call_mmap(struct file *file, struct vm_area_struct *vma)
 {
         return file->f_op->mmap(file, vma);
 }
 
 extern ssize_t vfs_read(struct file *, char __user *, size_t, loff_t *);
 extern ssize_t vfs_write(struct file *, const char __user *, size_t, loff_t *);
 extern ssize_t vfs_copy_file_range(struct file *, loff_t , struct file *,
                                    loff_t, size_t, unsigned int);
 int remap_verify_area(struct file *file, loff_t pos, loff_t len, bool write);
 int __generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
                                     struct file *file_out, loff_t pos_out,
                                     loff_t *len, unsigned int remap_flags,
                                     const struct iomap_ops *dax_read_ops);
 int generic_remap_file_range_prep(struct file *file_in, loff_t pos_in,
                                   struct file *file_out, loff_t pos_out,
                                   loff_t *count, unsigned int remap_flags);
 extern loff_t 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);
 
 /**
  * enum freeze_holder - holder of the freeze
  * @FREEZE_HOLDER_KERNEL: kernel wants to freeze or thaw filesystem
  * @FREEZE_HOLDER_USERSPACE: userspace wants to freeze or thaw filesystem
  * @FREEZE_MAY_NEST: whether nesting freeze and thaw requests is allowed
  *
  * Indicate who the owner of the freeze or thaw request is and whether
  * the freeze needs to be exclusive or can nest.
  * Without @FREEZE_MAY_NEST, multiple freeze and thaw requests from the
  * same holder aren't allowed. It is however allowed to hold a single
  * @FREEZE_HOLDER_USERSPACE and a single @FREEZE_HOLDER_KERNEL freeze at
  * the same time. This is relied upon by some filesystems during online
  * repair or similar.
  */
 enum freeze_holder {
         FREEZE_HOLDER_KERNEL    = (1U << 0),
         FREEZE_HOLDER_USERSPACE = (1U << 1),
         FREEZE_MAY_NEST         = (1U << 2),
 };
 
 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 *, enum freeze_holder who);
         int (*freeze_fs) (struct super_block *);
         int (*thaw_super) (struct super_block *, enum freeze_holder who);
         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 __rcu **(*get_dquots)(struct inode *);
 #endif
         long (*nr_cached_objects)(struct super_block *,
                                   struct shrink_control *);
         long (*free_cached_objects)(struct super_block *,
                                     struct shrink_control *);
         void (*shutdown)(struct super_block *sb);
 };
 
 /*
  * Inode flags - they have no relation to superblock flags now
  */
 #define S_SYNC          (1 << 0)  /* Writes are synced at once */
 #define S_NOATIME       (1 << 1)  /* Do not update access times */
 #define S_APPEND        (1 << 2)  /* Append-only file */
 #define S_IMMUTABLE     (1 << 3)  /* Immutable file */
 #define S_DEAD          (1 << 4)  /* removed, but still open directory */
 #define S_NOQUOTA       (1 << 5)  /* Inode is not counted to quota */
 #define S_DIRSYNC       (1 << 6)  /* Directory modifications are synchronous */
 #define S_NOCMTIME      (1 << 7)  /* Do not update file c/mtime */
 #define S_SWAPFILE      (1 << 8)  /* Do not truncate: swapon got its bmaps */
 #define S_PRIVATE       (1 << 9)  /* Inode is fs-internal */
 #define S_IMA           (1 << 10) /* Inode has an associated IMA struct */
 #define S_AUTOMOUNT     (1 << 11) /* Automount/referral quasi-directory */
 #define S_NOSEC         (1 << 12) /* no suid or xattr security attributes */
 #ifdef CONFIG_FS_DAX
 #define S_DAX           (1 << 13) /* Direct Access, avoiding the page cache */
 #else
 #define S_DAX           0         /* Make all the DAX code disappear */
 #endif
 #define S_ENCRYPTED     (1 << 14) /* Encrypted file (using fs/crypto/) */
 #define S_CASEFOLD      (1 << 15) /* Casefolded file */
 #define S_VERITY        (1 << 16) /* Verity file (using fs/verity/) */
 #define S_KERNEL_FILE   (1 << 17) /* File is in use by the kernel (eg. fs/cachefiles) */
 
 /*
  * Note that nosuid etc flags are inode-specific: setting some file-system
  * flags just means all the inodes inherit those flags by default. It might be
  * possible to override it selectively if you really wanted to with some
  * ioctl() that is not currently implemented.
  *
  * Exception: SB_RDONLY is always applied to the entire file system.
  *
  * Unfortunately, it is possible to change a filesystems flags with it mounted
  * with files in use.  This means that all of the inodes will not have their
  * i_flags updated.  Hence, i_flags no longer inherit the superblock mount
  * flags, so these have to be checked separately. -- rmk@arm.uk.linux.org
  */
 #define __IS_FLG(inode, flg)    ((inode)->i_sb->s_flags & (flg))
 
 static inline bool sb_rdonly(const struct super_block *sb) { return sb->s_flags & SB_RDONLY; }
 #define IS_RDONLY(inode)        sb_rdonly((inode)->i_sb)
 #define IS_SYNC(inode)          (__IS_FLG(inode, SB_SYNCHRONOUS) || \
                                         ((inode)->i_flags & S_SYNC))
 #define IS_DIRSYNC(inode)       (__IS_FLG(inode, SB_SYNCHRONOUS|SB_DIRSYNC) || \
                                         ((inode)->i_flags & (S_SYNC|S_DIRSYNC)))
 #define IS_MANDLOCK(inode)      __IS_FLG(inode, SB_MANDLOCK)
 #define IS_NOATIME(inode)       __IS_FLG(inode, SB_RDONLY|SB_NOATIME)
 #define IS_I_VERSION(inode)     __IS_FLG(inode, SB_I_VERSION)
 
 #define IS_NOQUOTA(inode)       ((inode)->i_flags & S_NOQUOTA)
 #define IS_APPEND(inode)        ((inode)->i_flags & S_APPEND)
 #define IS_IMMUTABLE(inode)     ((inode)->i_flags & S_IMMUTABLE)
 
 #ifdef CONFIG_FS_POSIX_ACL
 #define IS_POSIXACL(inode)      __IS_FLG(inode, SB_POSIXACL)
 #else
 #define IS_POSIXACL(inode)      0
 #endif
 
 #define IS_DEADDIR(inode)       ((inode)->i_flags & S_DEAD)
 #define IS_NOCMTIME(inode)      ((inode)->i_flags & S_NOCMTIME)
 
 #ifdef CONFIG_SWAP
 #define IS_SWAPFILE(inode)      ((inode)->i_flags & S_SWAPFILE)
 #else
 #define IS_SWAPFILE(inode)      ((void)(inode), 0U)
 #endif
 
 #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 mnt_idmap *idmap,
                                    struct inode *inode)
 {
         return !vfsuid_valid(i_uid_into_vfsuid(idmap, inode)) ||
                !vfsgid_valid(i_gid_into_vfsgid(idmap, inode));
 }
 
 static inline void init_sync_kiocb(struct kiocb *kiocb, struct file *filp)
 {
         *kiocb = (struct kiocb) {
                 .ki_filp = filp,
                 .ki_flags = filp->f_iocb_flags,
                 .ki_ioprio = get_current_ioprio(),
         };
 }
 
 static inline void kiocb_clone(struct kiocb *kiocb, struct kiocb *kiocb_src,
                                struct file *filp)
 {
         *kiocb = (struct kiocb) {
                 .ki_filp = filp,
                 .ki_flags = kiocb_src->ki_flags,
                 .ki_ioprio = kiocb_src->ki_ioprio,
                 .ki_pos = kiocb_src->ki_pos,
         };
 }
 
 /*
  * Inode state bits.  Protected by inode->i_lock
  *
  * Four bits determine the dirty state of the inode: I_DIRTY_SYNC,
  * I_DIRTY_DATASYNC, I_DIRTY_PAGES, and I_DIRTY_TIME.
  *
  * Four bits define the lifetime of an inode.  Initially, inodes are I_NEW,
  * until that flag is cleared.  I_WILL_FREE, I_FREEING and I_CLEAR are set at
  * various stages of removing an inode.
  *
  * Two bits are used for locking and completion notification, I_NEW and I_SYNC.
  *
  * I_DIRTY_SYNC         Inode is dirty, but doesn't have to be written on
  *                      fdatasync() (unless I_DIRTY_DATASYNC is also set).
  *                      Timestamp updates are the usual cause.
  * I_DIRTY_DATASYNC     Data-related inode changes pending.  We keep track of
  *                      these changes separately from I_DIRTY_SYNC so that we
  *                      don't have to write inode on fdatasync() when only
  *                      e.g. the timestamps have changed.
  * I_DIRTY_PAGES        Inode has dirty pages.  Inode itself may be clean.
  * I_DIRTY_TIME         The inode itself has dirty timestamps, and the
  *                      lazytime mount option is enabled.  We keep track of this
  *                      separately from I_DIRTY_SYNC in order to implement
  *                      lazytime.  This gets cleared if I_DIRTY_INODE
  *                      (I_DIRTY_SYNC and/or I_DIRTY_DATASYNC) gets set. But
  *                      I_DIRTY_TIME can still be set if I_DIRTY_SYNC is already
  *                      in place because writeback might already be in progress
  *                      and we don't want to lose the time update
  * I_NEW                Serves as both a mutex and completion notification.
  *                      New inodes set I_NEW.  If two processes both create
  *                      the same inode, one of them will release its inode and
  *                      wait for I_NEW to be released before returning.
  *                      Inodes in I_WILL_FREE, I_FREEING or I_CLEAR state can
  *                      also cause waiting on I_NEW, without I_NEW actually
  *                      being set.  find_inode() uses this to prevent returning
  *                      nearly-dead inodes.
  * I_WILL_FREE          Must be set when calling write_inode_now() if i_count
  *                      is zero.  I_FREEING must be set when I_WILL_FREE is
  *                      cleared.
  * I_FREEING            Set when inode is about to be freed but still has dirty
  *                      pages or buffers attached or the inode itself is still
  *                      dirty.
  * I_CLEAR              Added by clear_inode().  In this state the inode is
  *                      clean and can be destroyed.  Inode keeps I_FREEING.
  *
  *                      Inodes that are I_WILL_FREE, I_FREEING or I_CLEAR are
  *                      prohibited for many purposes.  iget() must wait for
  *                      the inode to be completely released, then create it
  *                      anew.  Other functions will just ignore such inodes,
  *                      if appropriate.  I_NEW is used for waiting.
  *
  * I_SYNC               Writeback of inode is running. The bit is set during
  *                      data writeback, and cleared with a wakeup on the bit
  *                      address once it is done. The bit is also used to pin
  *                      the inode in memory for flusher thread.
  *
  * I_REFERENCED         Marks the inode as recently references on the LRU list.
  *
  * I_DIO_WAKEUP         Never set.  Only used as a key for wait_on_bit().
  *
  * I_WB_SWITCH          Cgroup bdi_writeback switching in progress.  Used to
  *                      synchronize competing switching instances and to tell
  *                      wb stat updates to grab the i_pages lock.  See
  *                      inode_switch_wbs_work_fn() for details.
  *
  * I_OVL_INUSE          Used by overlayfs to get exclusive ownership on upper
  *                      and work dirs among overlayfs mounts.
  *
  * I_CREATING           New object's inode in the middle of setting up.
  *
  * I_DONTCACHE          Evict inode as soon as it is not used anymore.
  *
  * I_SYNC_QUEUED        Inode is queued in b_io or b_more_io writeback lists.
  *                      Used to detect that mark_inode_dirty() should not move
  *                      inode between dirty lists.
  *
  * I_PINNING_FSCACHE_WB Inode is pinning an fscache object for writeback.
  *
  * I_LRU_ISOLATING      Inode is pinned being isolated from LRU without holding
  *                      i_count.
  *
  * Q: What is the difference between I_WILL_FREE and I_FREEING?
  */
 #define I_DIRTY_SYNC            (1 << 0)
 #define I_DIRTY_DATASYNC        (1 << 1)
 #define I_DIRTY_PAGES           (1 << 2)
 #define __I_NEW                 3
 #define I_NEW                   (1 << __I_NEW)
 #define I_WILL_FREE             (1 << 4)
 #define I_FREEING               (1 << 5)
 #define I_CLEAR                 (1 << 6)
 #define __I_SYNC                7
 #define I_SYNC                  (1 << __I_SYNC)
 #define I_REFERENCED            (1 << 8)
 #define __I_DIO_WAKEUP          9
 #define I_DIO_WAKEUP            (1 << __I_DIO_WAKEUP)
 #define I_LINKABLE              (1 << 10)
 #define I_DIRTY_TIME            (1 << 11)
 #define I_WB_SWITCH             (1 << 13)
 #define I_OVL_INUSE             (1 << 14)
 #define I_CREATING              (1 << 15)
 #define I_DONTCACHE             (1 << 16)
 #define I_SYNC_QUEUED           (1 << 17)
 #define I_PINNING_NETFS_WB      (1 << 18)
 #define __I_LRU_ISOLATING       19
 #define I_LRU_ISOLATING         (1 << __I_LRU_ISOLATING)
 
 #define I_DIRTY_INODE (I_DIRTY_SYNC | I_DIRTY_DATASYNC)
 #define I_DIRTY (I_DIRTY_INODE | I_DIRTY_PAGES)
 #define I_DIRTY_ALL (I_DIRTY | I_DIRTY_TIME)
 
 extern void __mark_inode_dirty(struct inode *, int);
 static inline void mark_inode_dirty(struct inode *inode)
 {
         __mark_inode_dirty(inode, I_DIRTY);
 }
 
 static inline void mark_inode_dirty_sync(struct inode *inode)
 {
         __mark_inode_dirty(inode, I_DIRTY_SYNC);
 }
 
 /*
  * Returns true if the given inode itself only has dirty timestamps (its pages
  * may still be dirty) and isn't currently being allocated or freed.
  * Filesystems should call this if when writing an inode when lazytime is
  * enabled, they want to opportunistically write the timestamps of other inodes
  * located very nearby on-disk, e.g. in the same inode block.  This returns true
  * if the given inode is in need of such an opportunistic update.  Requires
  * i_lock, or at least later re-checking under i_lock.
  */
 static inline bool inode_is_dirtytime_only(struct inode *inode)
 {
         return (inode->i_state & (I_DIRTY_TIME | I_NEW |
                                   I_FREEING | I_WILL_FREE)) == I_DIRTY_TIME;
 }
 
 extern void inc_nlink(struct inode *inode);
 extern void drop_nlink(struct inode *inode);
 extern void clear_nlink(struct inode *inode);
 extern void set_nlink(struct inode *inode, unsigned int nlink);
 
 static inline void inode_inc_link_count(struct inode *inode)
 {
         inc_nlink(inode);
         mark_inode_dirty(inode);
 }
 
 static inline void inode_dec_link_count(struct inode *inode)
 {
         drop_nlink(inode);
         mark_inode_dirty(inode);
 }
 
 enum file_time_flags {
         S_ATIME = 1,
         S_MTIME = 2,
         S_CTIME = 4,
         S_VERSION = 8,
 };
 
 extern bool atime_needs_update(const struct path *, struct inode *);
 extern void touch_atime(const struct path *);
 int inode_update_time(struct inode *inode, int flags);
 
 static inline void file_accessed(struct file *file)
 {
         if (!(file->f_flags & O_NOATIME))
                 touch_atime(&file->f_path);
 }
 
 extern int file_modified(struct file *file);
 int kiocb_modified(struct kiocb *iocb);
 
 int sync_inode_metadata(struct inode *inode, int wait);
 
 struct file_system_type {
         const char *name;
         int fs_flags;
 #define FS_REQUIRES_DEV         1 
 #define FS_BINARY_MOUNTDATA     2
 #define FS_HAS_SUBTYPE          4
 #define FS_USERNS_MOUNT         8       /* Can be mounted by userns root */
 #define FS_DISALLOW_NOTIFY_PERM 16      /* Disable fanotify permission events */
 #define FS_ALLOW_IDMAP         32      /* FS has been updated to handle vfs idmappings. */
 #define FS_RENAME_DOES_D_MOVE   32768   /* FS will handle d_move() during rename() internally. */
         int (*init_fs_context)(struct fs_context *);
         const struct fs_parameter_spec *parameters;
         struct dentry *(*mount) (struct file_system_type *, int,
                        const char *, void *);
         void (*kill_sb) (struct super_block *);
         struct module *owner;
         struct file_system_type * next;
         struct hlist_head fs_supers;
 
         struct lock_class_key s_lock_key;
         struct lock_class_key s_umount_key;
         struct lock_class_key s_vfs_rename_key;
         struct lock_class_key s_writers_key[SB_FREEZE_LEVELS];
 
         struct lock_class_key i_lock_key;
         struct lock_class_key i_mutex_key;
         struct lock_class_key invalidate_lock_key;
         struct lock_class_key i_mutex_dir_key;
 };
 
 #define MODULE_ALIAS_FS(NAME) MODULE_ALIAS("fs-" NAME)
 
 extern struct dentry *mount_bdev(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *data,
         int (*fill_super)(struct super_block *, void *, int));
 extern struct dentry *mount_single(struct file_system_type *fs_type,
         int flags, void *data,
         int (*fill_super)(struct super_block *, void *, int));
 extern struct dentry *mount_nodev(struct file_system_type *fs_type,
         int flags, void *data,
         int (*fill_super)(struct super_block *, void *, int));
 extern struct dentry *mount_subtree(struct vfsmount *mnt, const char *path);
 void retire_super(struct super_block *sb);
 void generic_shutdown_super(struct super_block *sb);
 void kill_block_super(struct super_block *sb);
 void kill_anon_super(struct super_block *sb);
 void kill_litter_super(struct super_block *sb);
 void deactivate_super(struct super_block *sb);
 void deactivate_locked_super(struct super_block *sb);
 int set_anon_super(struct super_block *s, void *data);
 int set_anon_super_fc(struct super_block *s, struct fs_context *fc);
 int get_anon_bdev(dev_t *);
 void free_anon_bdev(dev_t);
 struct super_block *sget_fc(struct fs_context *fc,
                             int (*test)(struct super_block *, struct fs_context *),
                             int (*set)(struct super_block *, struct fs_context *));
 struct super_block *sget(struct file_system_type *type,
                         int (*test)(struct super_block *,void *),
                         int (*set)(struct super_block *,void *),
                         int flags, void *data);
 struct super_block *sget_dev(struct fs_context *fc, dev_t dev);
 
 /* Alas, no aliases. Too much hassle with bringing module.h everywhere */
 #define fops_get(fops) \
         (((fops) && try_module_get((fops)->owner) ? (fops) : NULL))
 #define fops_put(fops) \
         do { if (fops) module_put((fops)->owner); } while(0)
 /*
  * This one is to be used *ONLY* from ->open() instances.
  * fops must be non-NULL, pinned down *and* module dependencies
  * should be sufficient to pin the caller down as well.
  */
 #define replace_fops(f, fops) \
         do {    \
                 struct file *__file = (f); \
                 fops_put(__file->f_op); \
                 BUG_ON(!(__file->f_op = (fops))); \
         } while(0)
 
 extern int register_filesystem(struct file_system_type *);
 extern int unregister_filesystem(struct file_system_type *);
 extern int vfs_statfs(const struct path *, struct kstatfs *);
 extern int user_statfs(const char __user *, struct kstatfs *);
 extern int fd_statfs(int, struct kstatfs *);
 int freeze_super(struct super_block *super, enum freeze_holder who);
 int thaw_super(struct super_block *super, enum freeze_holder who);
 extern __printf(2, 3)
 int super_setup_bdi_name(struct super_block *sb, char *fmt, ...);
 extern int super_setup_bdi(struct super_block *sb);
 
 static inline void super_set_uuid(struct super_block *sb, const u8 *uuid, unsigned len)
 {
         if (WARN_ON(len > sizeof(sb->s_uuid)))
                 len = sizeof(sb->s_uuid);
         sb->s_uuid_len = len;
         memcpy(&sb->s_uuid, uuid, len);
 }
 
 /* set sb sysfs name based on sb->s_bdev */
 static inline void super_set_sysfs_name_bdev(struct super_block *sb)
 {
         snprintf(sb->s_sysfs_name, sizeof(sb->s_sysfs_name), "%pg", sb->s_bdev);
 }
 
 /* set sb sysfs name based on sb->s_uuid */
 static inline void super_set_sysfs_name_uuid(struct super_block *sb)
 {
         WARN_ON(sb->s_uuid_len != sizeof(sb->s_uuid));
         snprintf(sb->s_sysfs_name, sizeof(sb->s_sysfs_name), "%pU", sb->s_uuid.b);
 }
 
 /* set sb sysfs name based on sb->s_id */
 static inline void super_set_sysfs_name_id(struct super_block *sb)
 {
         strscpy(sb->s_sysfs_name, sb->s_id, sizeof(sb->s_sysfs_name));
 }
 
 /* try to use something standard before you use this */
 __printf(2, 3)
 static inline void super_set_sysfs_name_generic(struct super_block *sb, const char *fmt, ...)
 {
         va_list args;
 
         va_start(args, fmt);
         vsnprintf(sb->s_sysfs_name, sizeof(sb->s_sysfs_name), fmt, args);
         va_end(args);
 }
 
 extern int current_umask(void);
 
 extern void ihold(struct inode * inode);
 extern void iput(struct inode *);
 int inode_update_timestamps(struct inode *inode, int flags);
 int generic_update_time(struct inode *, int);
 
 /* /sys/fs */
 extern struct kobject *fs_kobj;
 
 #define MAX_RW_COUNT (INT_MAX & PAGE_MASK)
 
 /* fs/open.c */
 struct audit_names;
 struct filename {
         const char              *name;  /* pointer to actual string */
         const __user char       *uptr;  /* original userland pointer */
         atomic_t                refcnt;
         struct audit_names      *aname;
         const char              iname[];
 };
 static_assert(offsetof(struct filename, iname) % sizeof(long) == 0);
 
 static inline struct mnt_idmap *file_mnt_idmap(const struct file *file)
 {
         return mnt_idmap(file->f_path.mnt);
 }
 
 /**
  * is_idmapped_mnt - check whether a mount is mapped
  * @mnt: the mount to check
  *
  * If @mnt has an non @nop_mnt_idmap attached to it then @mnt is mapped.
  *
  * Return: true if mount is mapped, false if not.
  */
 static inline bool is_idmapped_mnt(const struct vfsmount *mnt)
 {
         return mnt_idmap(mnt) != &nop_mnt_idmap;
 }
 
 extern long vfs_truncate(const struct path *, loff_t);
 int do_truncate(struct mnt_idmap *, struct dentry *, loff_t start,
                 unsigned int time_attrs, struct file *filp);
 extern int vfs_fallocate(struct file *file, int mode, loff_t offset,
                         loff_t len);
 extern long do_sys_open(int dfd, const char __user *filename, int flags,
                         umode_t mode);
 extern struct file *file_open_name(struct filename *, int, umode_t);
 extern struct file *filp_open(const char *, int, umode_t);
 extern struct file *file_open_root(const struct path *,
                                    const char *, int, umode_t);
 static inline struct file *file_open_root_mnt(struct vfsmount *mnt,
                                    const char *name, int flags, umode_t mode)
 {
         return file_open_root(&(struct path){.mnt = mnt, .dentry = mnt->mnt_root},
                               name, flags, mode);
 }
 struct file *dentry_open(const struct path *path, int flags,
                          const struct cred *creds);
 struct file *dentry_create(const struct path *path, int flags, umode_t mode,
                            const struct cred *cred);
 struct path *backing_file_user_path(struct file *f);
 
 /*
  * When mmapping a file on a stackable filesystem (e.g., overlayfs), the file
  * stored in ->vm_file is a backing file whose f_inode is on the underlying
  * filesystem.  When the mapped file path and inode number are displayed to
  * user (e.g. via /proc/<pid>/maps), these helpers should be used to get the
  * path and inode number to display to the user, which is the path of the fd
  * that user has requested to map and the inode number that would be returned
  * by fstat() on that same fd.
  */
 /* Get the path to display in /proc/<pid>/maps */
 static inline const struct path *file_user_path(struct file *f)
 {
         if (unlikely(f->f_mode & FMODE_BACKING))
                 return backing_file_user_path(f);
         return &f->f_path;
 }
 /* Get the inode whose inode number to display in /proc/<pid>/maps */
 static inline const struct inode *file_user_inode(struct file *f)
 {
         if (unlikely(f->f_mode & FMODE_BACKING))
                 return d_inode(backing_file_user_path(f)->dentry);
         return file_inode(f);
 }
 
 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);
 extern struct filename *getname_uflags(const char __user *, int);
 extern struct filename *getname(const char __user *);
 extern struct filename *getname_kernel(const char *);
 extern void putname(struct filename *name);
 
 extern int finish_open(struct file *file, struct dentry *dentry,
                         int (*open)(struct inode *, struct file *));
 extern int finish_no_open(struct file *file, struct dentry *dentry);
 
 /* Helper for the simple case when original dentry is used */
 static inline int finish_open_simple(struct file *file, int error)
 {
         if (error)
                 return error;
 
         return finish_open(file, file->f_path.dentry, NULL);
 }
 
 /* fs/dcache.c */
 extern void __init vfs_caches_init_early(void);
 extern void __init vfs_caches_init(void);
 
 extern struct kmem_cache *names_cachep;
 
 #define __getname()             kmem_cache_alloc(names_cachep, GFP_KERNEL)
 #define __putname(name)         kmem_cache_free(names_cachep, (void *)(name))
 
 extern struct super_block *blockdev_superblock;
 static inline bool sb_is_blkdev_sb(struct super_block *sb)
 {
         return IS_ENABLED(CONFIG_BLOCK) && sb == blockdev_superblock;
 }
 
 void emergency_thaw_all(void);
 extern int sync_filesystem(struct super_block *);
 extern const struct file_operations def_blk_fops;
 extern const struct file_operations def_chr_fops;
 
 /* fs/char_dev.c */
 #define CHRDEV_MAJOR_MAX 512
 /* Marks the bottom of the first segment of free char majors */
 #define CHRDEV_MAJOR_DYN_END 234
 /* Marks the top and bottom of the second segment of free char majors */
 #define CHRDEV_MAJOR_DYN_EXT_START 511
 #define CHRDEV_MAJOR_DYN_EXT_END 384
 
 extern int alloc_chrdev_region(dev_t *, unsigned, unsigned, const char *);
 extern int register_chrdev_region(dev_t, unsigned, const char *);
 extern int __register_chrdev(unsigned int major, unsigned int baseminor,
                              unsigned int count, const char *name,
                              const struct file_operations *fops);
 extern void __unregister_chrdev(unsigned int major, unsigned int baseminor,
                                 unsigned int count, const char *name);
 extern void unregister_chrdev_region(dev_t, unsigned);
 extern void chrdev_show(struct seq_file *,off_t);
 
 static inline int register_chrdev(unsigned int major, const char *name,
                                   const struct file_operations *fops)
 {
         return __register_chrdev(major, 0, 256, name, fops);
 }
 
 static inline void unregister_chrdev(unsigned int major, const char *name)
 {
         __unregister_chrdev(major, 0, 256, name);
 }
 
 extern void init_special_inode(struct inode *, umode_t, dev_t);
 
 /* Invalid inode operations -- fs/bad_inode.c */
 extern void make_bad_inode(struct inode *);
 extern bool is_bad_inode(struct inode *);
 
 extern int __must_check file_fdatawait_range(struct file *file, loff_t lstart,
                                                 loff_t lend);
 extern int __must_check file_check_and_advance_wb_err(struct file *file);
 extern int __must_check file_write_and_wait_range(struct file *file,
                                                 loff_t start, loff_t end);
 
 static inline int file_write_and_wait(struct file *file)
 {
         return file_write_and_wait_range(file, 0, LLONG_MAX);
 }
 
 extern int vfs_fsync_range(struct file *file, loff_t start, loff_t end,
                            int datasync);
 extern int vfs_fsync(struct file *file, int datasync);
 
 extern int sync_file_range(struct file *file, loff_t offset, loff_t nbytes,
                                 unsigned int flags);
 
 static inline bool iocb_is_dsync(const struct kiocb *iocb)
 {
         return (iocb->ki_flags & IOCB_DSYNC) ||
                 IS_SYNC(iocb->ki_filp->f_mapping->host);
 }
 
 /*
  * Sync the bytes written if this was a synchronous write.  Expect ki_pos
  * to already be updated for the write, and will return either the amount
  * of bytes passed in, or an error if syncing the file failed.
  */
 static inline ssize_t generic_write_sync(struct kiocb *iocb, ssize_t count)
 {
         if (iocb_is_dsync(iocb)) {
                 int ret = vfs_fsync_range(iocb->ki_filp,
                                 iocb->ki_pos - count, iocb->ki_pos - 1,
                                 (iocb->ki_flags & IOCB_SYNC) ? 0 : 1);
                 if (ret)
                         return ret;
         }
 
         return count;
 }
 
 extern void emergency_sync(void);
 extern void emergency_remount(void);
 
 #ifdef CONFIG_BLOCK
 extern int bmap(struct inode *inode, sector_t *block);
 #else
 static inline int bmap(struct inode *inode,  sector_t *block)
 {
         return -EINVAL;
 }
 #endif
 
 int notify_change(struct mnt_idmap *, struct dentry *,
                   struct iattr *, struct inode **);
 int inode_permission(struct mnt_idmap *, struct inode *, int);
 int generic_permission(struct mnt_idmap *, struct inode *, int);
 static inline int file_permission(struct file *file, int mask)
 {
         return inode_permission(file_mnt_idmap(file),
                                 file_inode(file), mask);
 }
 static inline int path_permission(const struct path *path, int mask)
 {
         return inode_permission(mnt_idmap(path->mnt),
                                 d_inode(path->dentry), mask);
 }
 int __check_sticky(struct mnt_idmap *idmap, struct inode *dir,
                    struct inode *inode);
 
 static inline bool execute_ok(struct inode *inode)
 {
         return (inode->i_mode & S_IXUGO) || S_ISDIR(inode->i_mode);
 }
 
 static inline bool inode_wrong_type(const struct inode *inode, umode_t mode)
 {
         return (inode->i_mode ^ mode) & S_IFMT;
 }
 
 /**
  * file_start_write - get write access to a superblock for regular file io
  * @file: the file we want to write to
  *
  * This is a variant of sb_start_write() which is a noop on non-regualr file.
  * Should be matched with a call to file_end_write().
  */
 static inline void file_start_write(struct file *file)
 {
         if (!S_ISREG(file_inode(file)->i_mode))
                 return;
         sb_start_write(file_inode(file)->i_sb);
 }
 
 static inline bool file_start_write_trylock(struct file *file)
 {
         if (!S_ISREG(file_inode(file)->i_mode))
                 return true;
         return sb_start_write_trylock(file_inode(file)->i_sb);
 }
 
 /**
  * file_end_write - drop write access to a superblock of a regular file
  * @file: the file we wrote to
  *
  * Should be matched with a call to file_start_write().
  */
 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);
 }
 
 /**
  * kiocb_start_write - get write access to a superblock for async file io
  * @iocb: the io context we want to submit the write with
  *
  * This is a variant of sb_start_write() for async io submission.
  * Should be matched with a call to kiocb_end_write().
  */
 static inline void kiocb_start_write(struct kiocb *iocb)
 {
         struct inode *inode = file_inode(iocb->ki_filp);
 
         sb_start_write(inode->i_sb);
         /*
          * Fool lockdep by telling it the lock got released so that it
          * doesn't complain about the held lock when we return to userspace.
          */
         __sb_writers_release(inode->i_sb, SB_FREEZE_WRITE);
 }
 
 /**
  * kiocb_end_write - drop write access to a superblock after async file io
  * @iocb: the io context we sumbitted the write with
  *
  * Should be matched with a call to kiocb_start_write().
  */
 static inline void kiocb_end_write(struct kiocb *iocb)
 {
         struct inode *inode = file_inode(iocb->ki_filp);
 
         /*
          * Tell lockdep we inherited freeze protection from submission thread.
          */
         __sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
         sb_end_write(inode->i_sb);
 }
 
 /*
  * This is used for regular files where some users -- especially the
  * currently executed binary in a process, previously handled via
  * VM_DENYWRITE -- cannot handle concurrent write (and maybe mmap
  * read-write shared) accesses.
  *
  * get_write_access() gets write permission for a file.
  * put_write_access() releases this write permission.
  * deny_write_access() denies write access to a file.
  * allow_write_access() re-enables write access to a file.
  *
  * The i_writecount field of an inode can have the following values:
  * 0: no write access, no denied write access
  * < 0: (-i_writecount) users that denied write access to the file.
  * > 0: (i_writecount) users that have write access to the file.
  *
  * Normally we operate on that counter with atomic_{inc,dec} and it's safe
  * except for the cases where we don't hold i_writecount yet. Then we need to
  * use {get,deny}_write_access() - these functions check the sign and refuse
  * to do the change if sign is wrong.
  */
 static inline int get_write_access(struct inode *inode)
 {
         return atomic_inc_unless_negative(&inode->i_writecount) ? 0 : -ETXTBSY;
 }
 static inline int deny_write_access(struct file *file)
 {
         struct inode *inode = file_inode(file);
         return atomic_dec_unless_positive(&inode->i_writecount) ? 0 : -ETXTBSY;
 }
 static inline void put_write_access(struct inode * inode)
 {
         atomic_dec(&inode->i_writecount);
 }
 static inline void allow_write_access(struct file *file)
 {
         if (file)
                 atomic_inc(&file_inode(file)->i_writecount);
 }
 static inline bool inode_is_open_for_write(const struct inode *inode)
 {
         return atomic_read(&inode->i_writecount) > 0;
 }
 
 #if defined(CONFIG_IMA) || defined(CONFIG_FILE_LOCKING)
 static inline void i_readcount_dec(struct inode *inode)
 {
         BUG_ON(atomic_dec_return(&inode->i_readcount) < 0);
 }
 static inline void i_readcount_inc(struct inode *inode)
 {
         atomic_inc(&inode->i_readcount);
 }
 #else
 static inline void i_readcount_dec(struct inode *inode)
 {
         return;
 }
 static inline void i_readcount_inc(struct inode *inode)
 {
         return;
 }
 #endif
 extern int do_pipe_flags(int *, int);
 
 extern ssize_t kernel_read(struct file *, void *, size_t, loff_t *);
 ssize_t __kernel_read(struct file *file, void *buf, size_t count, loff_t *pos);
 extern ssize_t kernel_write(struct file *, const void *, size_t, loff_t *);
 extern ssize_t __kernel_write(struct file *, const void *, size_t, loff_t *);
 extern struct file * open_exec(const char *);
  
 /* fs/dcache.c -- generic fs support functions */
 extern bool is_subdir(struct dentry *, struct dentry *);
 extern bool path_is_under(const struct path *, const struct path *);
 
 extern char *file_path(struct file *, char *, int);
 
 /**
  * is_dot_dotdot - returns true only if @name is "." or ".."
  * @name: file name to check
  * @len: length of file name, in bytes
  */
 static inline bool is_dot_dotdot(const char *name, size_t len)
 {
         return len && unlikely(name[0] == '.') &&
                 (len == 1 || (len == 2 && name[1] == '.'));
 }
 
 #include <linux/err.h>
 
 /* needed for stackable file system support */
 extern loff_t default_llseek(struct file *file, loff_t offset, int whence);
 
 extern loff_t vfs_llseek(struct file *file, loff_t offset, int whence);
 
 extern int inode_init_always(struct super_block *, struct inode *);
 extern void inode_init_once(struct inode *);
 extern void address_space_init_once(struct address_space *mapping);
 extern struct inode * igrab(struct inode *);
 extern ino_t iunique(struct super_block *, ino_t);
 extern int inode_needs_sync(struct inode *inode);
 extern int generic_delete_inode(struct inode *inode);
 static inline int generic_drop_inode(struct inode *inode)
 {
         return !inode->i_nlink || inode_unhashed(inode);
 }
 extern void d_mark_dontcache(struct inode *inode);
 
 extern struct inode *ilookup5_nowait(struct super_block *sb,
                 unsigned long hashval, int (*test)(struct inode *, void *),
                 void *data);
 extern struct inode *ilookup5(struct super_block *sb, unsigned long hashval,
                 int (*test)(struct inode *, void *), void *data);
 extern struct inode *ilookup(struct super_block *sb, unsigned long ino);
 
 extern struct inode *inode_insert5(struct inode *inode, unsigned long hashval,
                 int (*test)(struct inode *, void *),
                 int (*set)(struct inode *, void *),
                 void *data);
 struct inode *iget5_locked(struct super_block *, unsigned long,
                            int (*test)(struct inode *, void *),
                            int (*set)(struct inode *, void *), void *);
 struct inode *iget5_locked_rcu(struct super_block *, unsigned long,
                                int (*test)(struct inode *, void *),
                                int (*set)(struct inode *, void *), void *);
 extern struct inode * iget_locked(struct super_block *, unsigned long);
 extern struct inode *find_inode_nowait(struct super_block *,
                                        unsigned long,
                                        int (*match)(struct inode *,
                                                     unsigned long, void *),
                                        void *data);
 extern struct inode *find_inode_rcu(struct super_block *, unsigned long,
                                     int (*)(struct inode *, void *), void *);
 extern struct inode *find_inode_by_ino_rcu(struct super_block *, unsigned long);
 extern int insert_inode_locked4(struct inode *, unsigned long, int (*test)(struct inode *, void *), void *);
 extern int insert_inode_locked(struct inode *);
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 extern void lockdep_annotate_inode_mutex_key(struct inode *inode);
 #else
 static inline void lockdep_annotate_inode_mutex_key(struct inode *inode) { };
 #endif
 extern void unlock_new_inode(struct inode *);
 extern void discard_new_inode(struct inode *);
 extern unsigned int get_next_ino(void);
 extern void evict_inodes(struct super_block *sb);
 void dump_mapping(const struct address_space *);
 
 /*
  * Userspace may rely on the inode number being non-zero. For example, glibc
  * simply ignores files with zero i_ino in unlink() and other places.
  *
  * As an additional complication, if userspace was compiled with
  * _FILE_OFFSET_BITS=32 on a 64-bit kernel we'll only end up reading out the
  * lower 32 bits, so we need to check that those aren't zero explicitly. With
  * _FILE_OFFSET_BITS=64, this may cause some harmless false-negatives, but
  * better safe than sorry.
  */
 static inline bool is_zero_ino(ino_t ino)
 {
         return (u32)ino == 0;
 }
 
 extern void __iget(struct inode * inode);
 extern void iget_failed(struct inode *);
 extern void clear_inode(struct inode *);
 extern void __destroy_inode(struct inode *);
 extern struct inode *new_inode_pseudo(struct super_block *sb);
 extern struct inode *new_inode(struct super_block *sb);
 extern void free_inode_nonrcu(struct inode *inode);
 extern int setattr_should_drop_suidgid(struct mnt_idmap *, struct inode *);
 extern int file_remove_privs_flags(struct file *file, unsigned int flags);
 extern int file_remove_privs(struct file *);
 int setattr_should_drop_sgid(struct mnt_idmap *idmap,
                              const struct inode *inode);
 
 /*
  * This must be used for allocating filesystems specific inodes to set
  * up the inode reclaim context correctly.
  */
 #define alloc_inode_sb(_sb, _cache, _gfp) kmem_cache_alloc_lru(_cache, &_sb->s_inode_lru, _gfp)
 
 extern void __insert_inode_hash(struct inode *, unsigned long hashval);
 static inline void insert_inode_hash(struct inode *inode)
 {
         __insert_inode_hash(inode, inode->i_ino);
 }
 
 extern void __remove_inode_hash(struct inode *);
 static inline void remove_inode_hash(struct inode *inode)
 {
         if (!inode_unhashed(inode) && !hlist_fake(&inode->i_hash))
                 __remove_inode_hash(inode);
 }
 
 extern void inode_sb_list_add(struct inode *inode);
 extern void inode_add_lru(struct inode *inode);
 
 extern int sb_set_blocksize(struct super_block *, int);
 extern int sb_min_blocksize(struct super_block *, int);
 
 extern int generic_file_mmap(struct file *, struct vm_area_struct *);
 extern int generic_file_readonly_mmap(struct file *, struct vm_area_struct *);
 extern ssize_t generic_write_checks(struct kiocb *, struct iov_iter *);
 int generic_write_checks_count(struct kiocb *iocb, loff_t *count);
 extern int generic_write_check_limits(struct file *file, loff_t pos,
                 loff_t *count);
 extern int generic_file_rw_checks(struct file *file_in, struct file *file_out);
 ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *to,
                 ssize_t already_read);
 extern ssize_t generic_file_read_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t __generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_write_iter(struct kiocb *, struct iov_iter *);
 extern ssize_t generic_file_direct_write(struct kiocb *, struct iov_iter *);
 ssize_t generic_perform_write(struct kiocb *, struct iov_iter *);
 ssize_t direct_write_fallback(struct kiocb *iocb, struct iov_iter *iter,
                 ssize_t direct_written, ssize_t buffered_written);
 
 ssize_t vfs_iter_read(struct file *file, struct iov_iter *iter, loff_t *ppos,
                 rwf_t flags);
 ssize_t vfs_iter_write(struct file *file, struct iov_iter *iter, loff_t *ppos,
                 rwf_t flags);
 ssize_t vfs_iocb_iter_read(struct file *file, struct kiocb *iocb,
                            struct iov_iter *iter);
 ssize_t vfs_iocb_iter_write(struct file *file, struct kiocb *iocb,
                             struct iov_iter *iter);
 
 /* fs/splice.c */
 ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
                             struct pipe_inode_info *pipe,
                             size_t len, unsigned int flags);
 ssize_t copy_splice_read(struct file *in, loff_t *ppos,
                          struct pipe_inode_info *pipe,
                          size_t len, unsigned int flags);
 extern ssize_t iter_file_splice_write(struct pipe_inode_info *,
                 struct file *, loff_t *, size_t, unsigned int);
 
 
 extern void
 file_ra_state_init(struct file_ra_state *ra, struct address_space *mapping);
 extern loff_t noop_llseek(struct file *file, loff_t offset, int whence);
 #define no_llseek NULL
 extern loff_t vfs_setpos(struct file *file, loff_t offset, loff_t maxsize);
 extern loff_t generic_file_llseek(struct file *file, loff_t offset, int whence);
 extern loff_t generic_file_llseek_size(struct file *file, loff_t offset,
                 int whence, loff_t maxsize, loff_t eof);
 extern loff_t fixed_size_llseek(struct file *file, loff_t offset,
                 int whence, loff_t size);
 extern loff_t no_seek_end_llseek_size(struct file *, loff_t, int, loff_t);
 extern loff_t no_seek_end_llseek(struct file *, loff_t, int);
 int rw_verify_area(int, struct file *, const loff_t *, size_t);
 extern int generic_file_open(struct inode * inode, struct file * filp);
 extern int nonseekable_open(struct inode * inode, struct file * filp);
 extern int stream_open(struct inode * inode, struct file * filp);
 
 #ifdef CONFIG_BLOCK
 typedef void (dio_submit_t)(struct bio *bio, struct inode *inode,
                             loff_t file_offset);
 
 enum {
         /* need locking between buffered and direct access */
         DIO_LOCKING     = 0x01,
 
         /* filesystem does not support filling holes */
         DIO_SKIP_HOLES  = 0x02,
 };
 
 ssize_t __blockdev_direct_IO(struct kiocb *iocb, struct inode *inode,
                              struct block_device *bdev, struct iov_iter *iter,
                              get_block_t get_block,
                              dio_iodone_t end_io,
                              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, 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);
 extern const struct inode_operations page_symlink_inode_operations;
 extern void kfree_link(void *);
 void generic_fillattr(struct mnt_idmap *, u32, struct inode *, struct kstat *);
 void generic_fill_statx_attr(struct inode *inode, struct kstat *stat);
 void generic_fill_statx_atomic_writes(struct kstat *stat,
                                       unsigned int unit_min,
                                       unsigned int unit_max);
 extern int vfs_getattr_nosec(const struct path *, struct kstat *, u32, unsigned int);
 extern int vfs_getattr(const struct path *, struct kstat *, u32, unsigned int);
 void __inode_add_bytes(struct inode *inode, loff_t bytes);
 void inode_add_bytes(struct inode *inode, loff_t bytes);
 void __inode_sub_bytes(struct inode *inode, loff_t bytes);
 void inode_sub_bytes(struct inode *inode, loff_t bytes);
 static inline loff_t __inode_get_bytes(struct inode *inode)
 {
         return (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
 }
 loff_t inode_get_bytes(struct inode *inode);
 void inode_set_bytes(struct inode *inode, loff_t bytes);
 const char *simple_get_link(struct dentry *, struct inode *,
                             struct delayed_call *);
 extern const struct inode_operations simple_symlink_inode_operations;
 
 extern int iterate_dir(struct file *, struct dir_context *);
 
 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
                 int flags);
 int vfs_fstat(int fd, struct kstat *stat);
 
 static inline int vfs_stat(const char __user *filename, struct kstat *stat)
 {
         return vfs_fstatat(AT_FDCWD, filename, stat, 0);
 }
 static inline int vfs_lstat(const char __user *name, struct kstat *stat)
 {
         return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
 }
 
 extern const char *vfs_get_link(struct dentry *, struct delayed_call *);
 extern int vfs_readlink(struct dentry *, char __user *, int);
 
 extern struct file_system_type *get_filesystem(struct file_system_type *fs);
 extern void put_filesystem(struct file_system_type *fs);
 extern struct file_system_type *get_fs_type(const char *name);
 extern 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 mnt_idmap *, struct dentry *,
                           struct iattr *);
 extern int simple_getattr(struct mnt_idmap *, 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 *);
 void simple_rename_timestamp(struct inode *old_dir, struct dentry *old_dentry,
                              struct inode *new_dir, struct dentry *new_dentry);
 extern int simple_rename_exchange(struct inode *old_dir, struct dentry *old_dentry,
                                   struct inode *new_dir, struct dentry *new_dentry);
 extern int simple_rename(struct mnt_idmap *, struct inode *,
                          struct dentry *, struct inode *, struct dentry *,
                          unsigned int);
 extern void simple_recursive_removal(struct dentry *,
                               void (*callback)(struct dentry *));
 extern int noop_fsync(struct file *, loff_t, loff_t, int);
 extern ssize_t noop_direct_IO(struct kiocb *iocb, struct iov_iter *iter);
 extern int simple_empty(struct dentry *);
 extern int simple_write_begin(struct file *file, struct address_space *mapping,
                         loff_t pos, unsigned len,
                         struct page **pagep, void **fsdata);
 extern const struct address_space_operations ram_aops;
 extern int always_delete_dentry(const struct dentry *);
 extern struct inode *alloc_anon_inode(struct super_block *);
 extern int simple_nosetlease(struct file *, int, struct file_lease **, 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);
 
 struct offset_ctx {
         struct maple_tree       mt;
         unsigned long           next_offset;
 };
 
 void simple_offset_init(struct offset_ctx *octx);
 int simple_offset_add(struct offset_ctx *octx, struct dentry *dentry);
 void simple_offset_remove(struct offset_ctx *octx, struct dentry *dentry);
 int simple_offset_empty(struct dentry *dentry);
 int simple_offset_rename(struct inode *old_dir, struct dentry *old_dentry,
                          struct inode *new_dir, struct dentry *new_dentry);
 int simple_offset_rename_exchange(struct inode *old_dir,
                                   struct dentry *old_dentry,
                                   struct inode *new_dir,
                                   struct dentry *new_dentry);
 void simple_offset_destroy(struct offset_ctx *octx);
 
 extern const struct file_operations simple_offset_dir_operations;
 
 extern int __generic_file_fsync(struct file *, loff_t, loff_t, int);
 extern int generic_file_fsync(struct file *, loff_t, loff_t, int);
 
 extern int generic_check_addressable(unsigned, u64);
 
 extern void generic_set_sb_d_ops(struct super_block *sb);
 extern int generic_ci_match(const struct inode *parent,
                             const struct qstr *name,
                             const struct qstr *folded_name,
                             const u8 *de_name, u32 de_name_len);
 
 static inline bool sb_has_encoding(const struct super_block *sb)
 {
 #if IS_ENABLED(CONFIG_UNICODE)
         return !!sb->s_encoding;
 #else
         return false;
 #endif
 }
 
 int may_setattr(struct mnt_idmap *idmap, struct inode *inode,
                 unsigned int ia_valid);
 int setattr_prepare(struct mnt_idmap *, struct dentry *, struct iattr *);
 extern int inode_newsize_ok(const struct inode *, loff_t offset);
 void setattr_copy(struct mnt_idmap *, struct inode *inode,
                   const struct iattr *attr);
 
 extern int file_update_time(struct file *file);
 
 static inline bool vma_is_dax(const struct vm_area_struct *vma)
 {
         return vma->vm_file && IS_DAX(vma->vm_file->f_mapping->host);
 }
 
 static inline bool vma_is_fsdax(struct vm_area_struct *vma)
 {
         struct inode *inode;
 
         if (!IS_ENABLED(CONFIG_FS_DAX) || !vma->vm_file)
                 return false;
         if (!vma_is_dax(vma))
                 return false;
         inode = file_inode(vma->vm_file);
         if (S_ISCHR(inode->i_mode))
                 return false; /* device-dax */
         return true;
 }
 
 static inline int iocb_flags(struct file *file)
 {
         int res = 0;
         if (file->f_flags & O_APPEND)
                 res |= IOCB_APPEND;
         if (file->f_flags & O_DIRECT)
                 res |= IOCB_DIRECT;
         if (file->f_flags & O_DSYNC)
                 res |= IOCB_DSYNC;
         if (file->f_flags & __O_SYNC)
                 res |= IOCB_SYNC;
         return res;
 }
 
 static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags,
                                      int rw_type)
 {
         int kiocb_flags = 0;
 
         /* make sure there's no overlap between RWF and private IOCB flags */
         BUILD_BUG_ON((__force int) RWF_SUPPORTED & IOCB_EVENTFD);
 
         if (!flags)
                 return 0;
         if (unlikely(flags & ~RWF_SUPPORTED))
                 return -EOPNOTSUPP;
         if (unlikely((flags & RWF_APPEND) && (flags & RWF_NOAPPEND)))
                 return -EINVAL;
 
         if (flags & RWF_NOWAIT) {
                 if (!(ki->ki_filp->f_mode & FMODE_NOWAIT))
                         return -EOPNOTSUPP;
                 kiocb_flags |= IOCB_NOIO;
         }
         if (flags & RWF_ATOMIC) {
                 if (rw_type != WRITE)
                         return -EOPNOTSUPP;
                 if (!(ki->ki_filp->f_mode & FMODE_CAN_ATOMIC_WRITE))
                         return -EOPNOTSUPP;
         }
         kiocb_flags |= (__force int) (flags & RWF_SUPPORTED);
         if (flags & RWF_SYNC)
                 kiocb_flags |= IOCB_DSYNC;
 
         if ((flags & RWF_NOAPPEND) && (ki->ki_flags & IOCB_APPEND)) {
                 if (IS_APPEND(file_inode(ki->ki_filp)))
                         return -EPERM;
                 ki->ki_flags &= ~IOCB_APPEND;
         }
 
         ki->ki_flags |= kiocb_flags;
         return 0;
 }
 
 /* Transaction based IO helpers */
 
 /*
  * An argresp is stored in an allocated page and holds the
  * size of the argument or response, along with its content
  */
 struct simple_transaction_argresp {
         ssize_t size;
         char data[];
 };
 
 #define SIMPLE_TRANSACTION_LIMIT (PAGE_SIZE - sizeof(struct simple_transaction_argresp))
 
 char *simple_transaction_get(struct file *file, const char __user *buf,
                                 size_t size);
 ssize_t simple_transaction_read(struct file *file, char __user *buf,
                                 size_t size, loff_t *pos);
 int simple_transaction_release(struct inode *inode, struct file *file);
 
 void simple_transaction_set(struct file *file, size_t n);
 
 /*
  * simple attribute files
  *
  * These attributes behave similar to those in sysfs:
  *
  * Writing to an attribute immediately sets a value, an open file can be
  * written to multiple times.
  *
  * Reading from an attribute creates a buffer from the value that might get
  * read with multiple read calls. When the attribute has been read
  * completely, no further read calls are possible until the file is opened
  * again.
  *
  * All attributes contain a text representation of a numeric value
  * that are accessed with the get() and set() functions.
  */
 #define DEFINE_SIMPLE_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, __is_signed)       \
 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   = (__is_signed) ? simple_attr_write_signed : simple_attr_write,        \
         .llseek  = generic_file_llseek,                                 \
 }
 
 #define DEFINE_SIMPLE_ATTRIBUTE(__fops, __get, __set, __fmt)            \
         DEFINE_SIMPLE_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, false)
 
 #define DEFINE_SIMPLE_ATTRIBUTE_SIGNED(__fops, __get, __set, __fmt)     \
         DEFINE_SIMPLE_ATTRIBUTE_XSIGNED(__fops, __get, __set, __fmt, true)
 
 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);
 ssize_t simple_attr_write_signed(struct file *file, const char __user *buf,
                                  size_t len, loff_t *ppos);
 
 struct ctl_table;
 int __init list_bdev_fs_names(char *buf, size_t size);
 
 #define __FMODE_EXEC            ((__force int) FMODE_EXEC)
 #define __FMODE_NONOTIFY        ((__force int) FMODE_NONOTIFY)
 
 #define ACC_MODE(x) ("\004\002\006\006"[(x)&O_ACCMODE])
 #define OPEN_FMODE(flag) ((__force fmode_t)(((flag + 1) & O_ACCMODE) | \
                                             (flag & __FMODE_NONOTIFY)))
 
 static inline bool is_sxid(umode_t mode)
 {
         return mode & (S_ISUID | S_ISGID);
 }
 
 static inline int check_sticky(struct mnt_idmap *idmap,
                                struct inode *dir, struct inode *inode)
 {
         if (!(dir->i_mode & S_ISVTX))
                 return 0;
 
         return __check_sticky(idmap, 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);
 }
 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);
 }
 static inline bool dir_emit_dotdot(struct file *file, struct dir_context *ctx)
 {
         return ctx->actor(ctx, "..", 2, ctx->pos,
                           d_parent_ino(file->f_path.dentry), DT_DIR);
 }
 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);
 
 static inline bool vfs_empty_path(int dfd, const char __user *path)
 {
         char c;
 
         if (dfd < 0)
                 return false;
 
         /* We now allow NULL to be used for empty path. */
         if (!path)
                 return true;
 
         if (unlikely(get_user(c, path)))
                 return false;
 
         return !c;
 }
 
 bool generic_atomic_write_valid(struct iov_iter *iter, loff_t pos);
 
 #endif /* _LINUX_FS_H */