inode_vxfs(4)						     Kernel Interfaces Manual						     inode_vxfs(4)

NAME

       inode_vxfs - format of a VxFS file system inode

SYNOPSIS

DESCRIPTION

       A VxFS inode is typically 256 bytes in length, but an inode can also be 512 bytes.  You specify the inode size with

       An inode entry has the following format:

       The mode and type of file.

       The number of links to the file.

       The inode owner.

       The inode group.

       The size in bytes of the file.
		      Eight bytes are allocated.

       Time of last access, in
		      format.

       Time of last modification, in
		      format.

       Time of last inode change, in
		      format.

       These flags control the allocation and extension of files:
		      If set, the inode is invalid.  Cleared when is run.

		      If set,
			     the  file	cannot	be  extended  after  the current reservation is exceeded.  The reservation can be increased by the
			     ioctl, but the file is not automatically extended.

		      If set,
			     the file cannot be extended after the current reservation is exceeded.  This flag is typically  set  because  an  I/O
			     error occurred while extending a file.  Cleared on truncation or when setext is run.

		      If set, the
			     file  must  be allocated in extents of a fixed size and alignment.  If an extent of i_fixextsize blocks aligned on an
			     i_fixextsize boundary cannot be found, then the allocation fails.	The alignment is relative to the beginning of  the
			     allocation unit.

       Mapping type.  Indicates how to interpret the inode mapping area.  Currently there are four supported mapping types:
		      Mapping area is unused.  is used for files that have no associated data storage. Because there is no need for either extents
		      or immediate data, the mapping area is unused.  Block and character special files, for example, use this organization type.

		      Mapping area consists of an array of 32-bit extent block addresses
			     and sizes.

		      Mapping area itself is a data block.
			     This mapping is referred to as Immediate Inode Data.

		      Mapping area consists of typed-extent structures.

       Extended inode operation flag area.

       Extended inode operation data area.

       This field is a union.
		      The contents are determined by file type.

		      For devices, the following field is supported:

		      The device number of a block or character special device.

		      For directories, the following field is supported:

		      The parent directory inode inumber if the inode is a directory.
					This replaces the standard ``..'' (dot dot) entry in the  first  directory  block.   VxFS  does  not  have
					explicit ``.'' (dot ) and ``..'' (dot dot) entries.

		      For regular files, the following fields are supported:

		      The number of data blocks reserved for exclusive use by the
					file (preallocation).  A preallocation can be requested using an ioctl.  See vxfsio(7).

		      Set when the inode has a fixed extent size.
					The  default  is  to  have a variable extent size allocation policy.  A fixed extent size may be specified
					using ioctl. See vxfsio(7).

		      For structural files, the following fields are supported:

		      (Version 2 and later disk layouts only.)
					The inode number of the ``matching'' inode.  For replicated files, this is the inode of the replica.   For
					extent map reorganization files, this is the inode of the file being reorganized.

		      (Version 2 and later disk layouts only.)
					The index of the fileset associated with the inode.

       The number of blocks allocated to the file, including the
		      blocks allocated for indirect address extents.

       The generation number.
		      A  serial  number  which	increments  whenever the inode is freed and reallocated.  This provides a ``handle'' for stateless
		      servers such as NFS.

       The number of times the inode metadata is modified.
		      This field is a 64-bit number.

       The mapping area.
		      This field is a union based on the value of and the file system type.

		      For the VxFS organization type, the following structure is used:
		      The immediate inode data area, (currently 96) bytes in length (see Any directory or symbolic link  which	is  less  than	or
		      equal to 96 bytes in length is stored directly in the inode.

		      For the VxFS organization type, the following structure is used:
		      Indirect extent size.  The size, in blocks, of the indirect data extents in the file.

		      Array of indirect address extents.
			     There  are indirect address extents.  The indirect address extents are 8192 bytes long.  Each indirect address extent
			     may contain up to 2048 extent addresses.

			     The first indirect address extent is for single indirection.  With single indirection, each  entry  in  the  indirect
			     address extent indicates the starting block number of a data extent.

			     The  second  indirect address extent is a double indirect address extent.	With double indirection, each entry in the
			     indirect address extent indicates the starting block number of a single indirect address extent.

		      An array of structures containing the direct extent addresses and sizes.
			     Up to direct extents are supported.  Because there is a variable length extent allocation policy, each direct  extent
			     can have a different size.  Each structure contains the following elements:

			     Direct extent address.

			     Direct extent size.

		      (Version 2 and later disk layouts.)
			     Indirect attribute inode.	Identifies the inode in the attribute fileset that contains indirect attribute references.

			     The remaining bytes of the inode are reserved for extended attribute records. Their format is:
			     length  The  length  of  the  attribute record. If this is not a multiple of 4 bytes, the start of the next attribute
			     record is found by rounding the length up to a 4 byte boundary.

			     format The format of the data layout of the remainder of the attribute record.  Each attribute consists  of  a  class
				    identifying the attribute's administrative domain, a subclass identifying the attribute within the administra-
				    tive domain, and data.  The valid record formats are:

				    Extends the immediate data area so that files larger than
					   96 bytes can be stored directly in the inode.

				    The attribute is stored directly in the inode. The fields
					   in the rest of this record are:

					   class     The class of the attribute.

					   subclass  The subclass of the attribute.

					   data      The attribute data.

				    When attributes are too large to store directly in the inode,
					   each attribute is stored in its own file.  lists each attribute along with the inode number correspond-
					   ing	to  the file in which the attribute is stored.	The number of entries in the list is determined by
					   the length of the record. The fields in each entry are:

					   class     The class of the attribute.

					   subclass  The subclass of the attribute.

					   length    The length of the attribute data. This allows attribute operations to check the length of	an
						     attribute without reading the attribute inode.

					   inumber   The  inode  number  of  the  file	containing  the  attribute data.  The inode is part of the
						     attribute fileset.

			     The attribute records in the inode terminate with a record that has a format of zero  (for  compatibility	with  file
			     systems that have the last 80 bytes of all inodes set to NULL).

SEE ALSO

       setext(1M), stat(2), fs_vxfs(4), vxfsio(7).

																     inode_vxfs(4)