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NAMEinode_vxfs — format of a VxFS file system inode SYNOPSIS#include <sys/types.h>
#include <sys/fs/vx_inode.h> DESCRIPTIONA VxFS inode is typically 256 bytes in length,
but an inode can also be 512 bytes.
You specify the inode size with
mkfs. An inode
entry has the following format:
- i_mode
The mode and type of file. - i_nlink
The number of links to the file. - i_uid
The inode owner. - i_gid
The inode group. - i_size
The size in bytes of the file.
Eight bytes are allocated. - i_atime
Time of last access, in
struct timeval
format. - i_mtime
Time of last modification, in
struct timeval
format. - i_ctime
Time of last inode change, in
struct timeval
format. - i_aflags
These flags control the allocation and extension of files:
- VX_AF_IBAD
If set,
the inode is invalid.
Cleared when
fsck
is run. - VX_AF_NOEXTEND
If set,
the file cannot be extended after the current
reservation is exceeded.
The reservation can be increased by the
VX_SETEXT
ioctl,
but the file is not automatically extended. - VX_AF_NOGROW
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. - VX_AF_ALIGN
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.
- i_orgtype
Mapping type.
Indicates how to interpret the
inode mapping area.
Currently
there are four supported mapping types:
- IORG_NONE
Mapping area is unused.
IORG_NONE
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. - IORG_EXT4
Mapping area consists of an array of 32-bit extent block addresses
and sizes. - IORG_IMMED
Mapping area itself is a data block.
This mapping is referred to
as Immediate Inode Data. - IORG_TYPED
Mapping area consists of typed-extent structures.
- i_eopflags
Extended inode operation flag area. - i_eopdata
Extended inode operation data area. - i_ftarea
This field is a union.
The contents are determined by file type. For devices, the following field is supported:
- i_rdev
The device number of a block or character special device.
For directories, the following field is supported:
- i_dotdot
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:
- i_reserve
The number of data blocks reserved for exclusive use by the
file (preallocation).
A preallocation can be requested using an ioctl.
See
vxfsio(7). - i_fixextsize
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:
- i_matchino
(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. - i_fsetindex
(Version 2 and later disk layouts only.)
The index of the fileset associated with the inode.
- i_blocks
The number of blocks allocated to the file, including the
blocks allocated for indirect address extents. - i_gen
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. - i_vversion
The number of times the inode metadata is modified.
This field is a 64-bit number. - ic_org
The mapping area.
This field is a union based on the value of
i_orgtype
and the file system type. For the VxFS
IORG_IMMED
organization type, the following
structure is used:
- i_immed
The immediate inode data area,
NIMMED_N
(currently 96) bytes in length
(see
fs_immedlen).
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
IORG_EXT4
organization type, the following
structure is used:
- i_ies
Indirect extent size.
The size, in blocks, of the indirect data
extents in the file. - i_ie
Array of indirect address extents.
There are
NIADDR
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. - i_dext
An array of structures containing the direct extent addresses and sizes.
Up to
NDADDR_N
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:
- i_de
Direct extent address. - i_des
Direct extent size.
- i_iattrino
(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
administrative domain, and data.
The valid record formats are:
- ATTR_EXTIMMED
Extends the immediate data area so that files larger than
96 bytes can be stored directly in the inode. - ATTR_IMMED
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.
- ATTR_DIRECT
When attributes are too large to store directly in the inode,
each attribute is stored in its own file.
ATTR_DIRECT
lists each attribute along with the inode number
corresponding 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).
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