text: #ifndef _UAPI_LINUX_FS_H
  #define _UAPI_LINUX_FS_H
  
  /*
   * This file has definitions for some important file table
   * structures etc.
   */
  
  #include <linux/limits.h>
  #include <linux/ioctl.h>
  #include <linux/types.h>
  
  /*
   * It's silly to have NR_OPEN bigger than NR_FILE, but you can change
   * the file limit at runtime and only root can increase the per-process
   * nr_file rlimit, so it's safe to set up a ridiculously high absolute
   * upper limit on files-per-process.
   *
   * Some programs (notably those using select()) may have to be 
   * recompiled to take full advantage of the new limits..  
   */
  
  /* Fixed constants first: */
  #undef NR_OPEN
  #define INR_OPEN_CUR 1024	/* Initial setting for nfile rlimits */
  #define INR_OPEN_MAX 4096	/* Hard limit for nfile rlimits */
  
  #define BLOCK_SIZE_BITS 10
  #define BLOCK_SIZE (1<<BLOCK_SIZE_BITS)
  
  #define SEEK_SET	0	/* seek relative to beginning of file */
  #define SEEK_CUR	1	/* seek relative to current file position */
  #define SEEK_END	2	/* seek relative to end of file */
  #define SEEK_DATA	3	/* seek to the next data */
  #define SEEK_HOLE	4	/* seek to the next hole */
  #define SEEK_MAX	SEEK_HOLE
  
  struct fstrim_range {
  	__u64 start;
  	__u64 len;
  	__u64 minlen;
  };
  
  /* And dynamically-tunable limits and defaults: */
  struct files_stat_struct {
  	unsigned long nr_files;		/* read only */
  	unsigned long nr_free_files;	/* read only */
  	unsigned long max_files;		/* tunable */
  };
  
  struct inodes_stat_t {
  	int nr_inodes;
  	int nr_unused;
  	int dummy[5];		/* padding for sysctl ABI compatibility */
  };
  
  
  #define NR_FILE  8192	/* this can well be larger on a larger system */
  
  
  /*
   * These are the fs-independent mount-flags: up to 32 flags are supported
   */
  #define MS_RDONLY	 1	/* Mount read-only */
  #define MS_NOSUID	 2	/* Ignore suid and sgid bits */
  #define MS_NODEV	 4	/* Disallow access to device special files */
  #define MS_NOEXEC	 8	/* Disallow program execution */
  #define MS_SYNCHRONOUS	16	/* Writes are synced at once */
  #define MS_REMOUNT	32	/* Alter flags of a mounted FS */
  #define MS_MANDLOCK	64	/* Allow mandatory locks on an FS */
  #define MS_DIRSYNC	128	/* Directory modifications are synchronous */
  #define MS_NOATIME	1024	/* Do not update access times. */
  #define MS_NODIRATIME	2048	/* Do not update directory access times */
  #define MS_BIND		4096
  #define MS_MOVE		8192
  #define MS_REC		16384
  #define MS_VERBOSE	32768	/* War is peace. Verbosity is silence.
  				   MS_VERBOSE is deprecated. */
  #define MS_SILENT	32768
  #define MS_POSIXACL	(1<<16)	/* VFS does not apply the umask */
  #define MS_UNBINDABLE	(1<<17)	/* change to unbindable */
  #define MS_PRIVATE	(1<<18)	/* change to private */
  #define MS_SLAVE	(1<<19)	/* change to slave */
  #define MS_SHARED	(1<<20)	/* change to shared */
  #define MS_RELATIME	(1<<21)	/* Update atime relative to mtime/ctime. */
  #define MS_KERNMOUNT	(1<<22) /* this is a kern_mount call */
  #define MS_I_VERSION	(1<<23) /* Update inode I_version field */
  #define MS_STRICTATIME	(1<<24) /* Always perform atime updates */
  #define MS_NOSEC	(1<<28)
  #define MS_BORN		(1<<29)
  #define MS_ACTIVE	(1<<30)
  #define MS_NOUSER	(1<<31)
  
  /*
   * Superblock flags that can be altered by MS_REMOUNT
   */
  #define MS_RMT_MASK	(MS_RDONLY|MS_SYNCHRONOUS|MS_MANDLOCK|MS_I_VERSION)
  
  /*
   * Old magic mount flag and mask
   */
  #define MS_MGC_VAL 0xC0ED0000
  #define MS_MGC_MSK 0xffff0000
  
  /* the read-only stuff doesn't really belong here, but any other place is
     probably as bad and I don't want to create yet another include file. */
  
  #define BLKROSET   _IO(0x12,93)	/* set device read-only (0 = read-write) */
  #define BLKROGET   _IO(0x12,94)	/* get read-only status (0 = read_write) */
  #define BLKRRPART  _IO(0x12,95)	/* re-read partition table */
  #define BLKGETSIZE _IO(0x12,96)	/* return device size /512 (long *arg) */
  #define BLKFLSBUF  _IO(0x12,97)	/* flush buffer cache */
  #define BLKRASET   _IO(0x12,98)	/* set read ahead for block device */
  #define BLKRAGET   _IO(0x12,99)	/* get current read ahead setting */
  #define BLKFRASET  _IO(0x12,100)/* set filesystem (mm/filemap.c) read-ahead */
  #define BLKFRAGET  _IO(0x12,101)/* get filesystem (mm/filemap.c) read-ahead */
  #define BLKSECTSET _IO(0x12,102)/* set max sectors per request (ll_rw_blk.c) */
  #define BLKSECTGET _IO(0x12,103)/* get max sectors per request (ll_rw_blk.c) */
  #define BLKSSZGET  _IO(0x12,104)/* get block device sector size */
  #if 0
  #define BLKPG      _IO(0x12,105)/* See blkpg.h */
  
  /* Some people are morons.  Do not use sizeof! */
  
  #define BLKELVGET  _IOR(0x12,106,size_t)/* elevator get */
  #define BLKELVSET  _IOW(0x12,107,size_t)/* elevator set */
  /* This was here just to show that the number is taken -
     probably all these _IO(0x12,*) ioctls should be moved to blkpg.h. */
  #endif
  /* A jump here: 108-111 have been used for various private purposes. */
  #define BLKBSZGET  _IOR(0x12,112,size_t)
  #define BLKBSZSET  _IOW(0x12,113,size_t)
  #define BLKGETSIZE64 _IOR(0x12,114,size_t)	/* return device size in bytes (u64 *arg) */
  #define BLKTRACESETUP _IOWR(0x12,115,struct blk_user_trace_setup)
  #define BLKTRACESTART _IO(0x12,116)
  #define BLKTRACESTOP _IO(0x12,117)
  #define BLKTRACETEARDOWN _IO(0x12,118)
  #define BLKDISCARD _IO(0x12,119)
  #define BLKIOMIN _IO(0x12,120)
  #define BLKIOOPT _IO(0x12,121)
  #define BLKALIGNOFF _IO(0x12,122)
  #define BLKPBSZGET _IO(0x12,123)
  #define BLKDISCARDZEROES _IO(0x12,124)
  #define BLKSECDISCARD _IO(0x12,125)
  #define BLKROTATIONAL _IO(0x12,126)
  #define BLKZEROOUT _IO(0x12,127)
  
  #define BMAP_IOCTL 1		/* obsolete - kept for compatibility */
  #define FIBMAP	   _IO(0x00,1)	/* bmap access */
  #define FIGETBSZ   _IO(0x00,2)	/* get the block size used for bmap */
  #define FIFREEZE	_IOWR('X', 119, int)	/* Freeze */
  #define FITHAW		_IOWR('X', 120, int)	/* Thaw */
  #define FITRIM		_IOWR('X', 121, struct fstrim_range)	/* Trim */
  
  #define	FS_IOC_GETFLAGS			_IOR('f', 1, long)
  #define	FS_IOC_SETFLAGS			_IOW('f', 2, long)
  #define	FS_IOC_GETVERSION		_IOR('v', 1, long)
  #define	FS_IOC_SETVERSION		_IOW('v', 2, long)
  #define FS_IOC_FIEMAP			_IOWR('f', 11, struct fiemap)
  #define FS_IOC32_GETFLAGS		_IOR('f', 1, int)
  #define FS_IOC32_SETFLAGS		_IOW('f', 2, int)
  #define FS_IOC32_GETVERSION		_IOR('v', 1, int)
  #define FS_IOC32_SETVERSION		_IOW('v', 2, int)
  
  /*
   * Inode flags (FS_IOC_GETFLAGS / FS_IOC_SETFLAGS)
   */
  #define	FS_SECRM_FL			0x00000001 /* Secure deletion */
  #define	FS_UNRM_FL			0x00000002 /* Undelete */
  #define	FS_COMPR_FL			0x00000004 /* Compress file */
  #define FS_SYNC_FL			0x00000008 /* Synchronous updates */
  #define FS_IMMUTABLE_FL			0x00000010 /* Immutable file */
  #define FS_APPEND_FL			0x00000020 /* writes to file may only append */
  #define FS_NODUMP_FL			0x00000040 /* do not dump file */
  #define FS_NOATIME_FL			0x00000080 /* do not update atime */
  /* Reserved for compression usage... */
  #define FS_DIRTY_FL			0x00000100
  #define FS_COMPRBLK_FL			0x00000200 /* One or more compressed clusters */
  #define FS_NOCOMP_FL			0x00000400 /* Don't compress */
  #define FS_ECOMPR_FL			0x00000800 /* Compression error */
  /* End compression flags --- maybe not all used */
  #define FS_BTREE_FL			0x00001000 /* btree format dir */
  #define FS_INDEX_FL			0x00001000 /* hash-indexed directory */
  #define FS_IMAGIC_FL			0x00002000 /* AFS directory */
  #define FS_JOURNAL_DATA_FL		0x00004000 /* Reserved for ext3 */
  #define FS_NOTAIL_FL			0x00008000 /* file tail should not be merged */
  #define FS_DIRSYNC_FL			0x00010000 /* dirsync behaviour (directories only) */
  #define FS_TOPDIR_FL			0x00020000 /* Top of directory hierarchies*/
  #define FS_EXTENT_FL			0x00080000 /* Extents */
  #define FS_DIRECTIO_FL			0x00100000 /* Use direct i/o */
  #define FS_NOCOW_FL			0x00800000 /* Do not cow file */
  #define FS_RESERVED_FL			0x80000000 /* reserved for ext2 lib */
  
  #define FS_FL_USER_VISIBLE		0x0003DFFF /* User visible flags */
  #define FS_FL_USER_MODIFIABLE		0x000380FF /* User modifiable flags */
  
  
  #define SYNC_FILE_RANGE_WAIT_BEFORE	1
  #define SYNC_FILE_RANGE_WRITE		2
  #define SYNC_FILE_RANGE_WAIT_AFTER	4
  
  #endif /* _UAPI_LINUX_FS_H */
  