Defines the structure of the data associated with a virtual file system.
The /usr/include/sys/vmount.h file defines the vmount structure. Each active virtual file system (VFS) has a vmount structure associated with it. The vmount structure contains the mount parameters (such as the mount object and the mounted-over object) for that VFS. The vmount data is created when the VFS is mounted. The mntctl subroutine returns the VFS data.
The vmount structure contains the following fields to describe fixed-length data:
| Item | Description |
|---|---|
| vmt_revision | The revision code in effect when the program that created this VFS was compiled. |
| vmt_length | The total length of the structure and data. This will always be a multiple of the word size (4 bytes). |
| vmt_fsid | The two-word file system identifier; the interpretation of this identifier depends on the vmt_gfstype field. |
| vmt_vfsnumber | The unique identifier of the VFS. Virtual file systems and their identifiers are deleted at IPL (initial program load). |
| vmt_time | The time at which the VFS was created. |
| vmt_flags | The general mount flags, for example: READONLY, REMOVABLE, DEVICE, REMOTE. |
| vmt_gfstype | The type of the general file system. Possible values are:
|
The remaining fields in the vmount structure describe variable-length data. Each entry in the vmt_data array specifies the offset from the start of the vmount structure at which a data item appears, as well as the length of the data item.
| Item | Description |
|---|---|
| vmt_off | Offset of the data, aligned on a word (32-bit) boundary. |
| vmt_size | Actual size of the data in bytes. |
| vmt_data[VMT_OBJECT] | Name of the device, directory, or file that is mounted. |
| vmt_data[VMT_STUB] | Name of the device, directory, or file that is mounted over. |
| vmt_data[VMT_HOST] | Short (binary) name of the host that owns the mounted object. |
| vmt_data[VMT_HOSTNAME] | Long (character) name of the host that owns the mounted object. |
| vmt_data[VMT_INFO] | Binary information passed to the file system implementation that supports this object; the contents of this field are specific to the generic file system (GFS) type defined by the vmt_gfstype field. |
| vmt_data[VMT_ARGS] | Character-string representation of the arguments supplied when the VFS was created. |