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Technical Reference: Kernel and Subsystems, Volume 1
vfs_mount Entry Point
Purpose
Mounts a virtual file system.
Syntax
int vfs_mount ( vfsp)
struct vfs *vfsp;
struct ucred * crp;
Parameter
vfsp |
Points to the newly created vfs structure. |
crp |
Points to the cred structure. This structure
contains data that the file system can use to validate access permission. |
Description
The vfs_mount entry point is
called by the logical file system to mount a new file system. This entry point
is called after the vfs structure is allocated and initialized.
Before this structure is passed to the vfs_mount entry
point, the logical file system:
- Guarantees the syntax of the vmount or mount subroutines.
- Allocates the vfs structure.
- Resolves the stub to a virtual node (v-node). This is the vfs_mntdover field in the vfs structure.
- Initializes the following virtual file system
fields:
Field |
Description |
vfs_flags |
Initialized depending on the type of mount. This field takes the
following values:
- VFS_MOUNTOK
- The user has write permission in the stub's parent directory and is
the owner of the stub.
- VFS_SUSER
- The user has root user authority.
- VFS_NOSUID
- Execution of setuid and setgid programs from this mount are not allowed.
- VFS_NODEV
- Opens of devices from this mount are not allowed.
|
vfs_type |
Initialized to the / (root) file system type when the mount subroutine is used. If the vmount subroutine
is used, the vfs_type field is set to the type parameter supplied by the user. The logical file system verifies
the existence of the type parameter. |
vfs_ops |
Initialized according to the vfs_type
field. |
vfs_mntdover |
Identifies the v-node that refers to the stub path argument. This
argument is supplied by the mount or vmount subroutine. |
vfs_date |
Holds the time stamp. The time stamp specifies the time to initialize
the virtual file system. |
vfs_number |
Indicates the unique number sequence representing this virtual file
system. |
vfs_mdata |
Initialized with the vmount structure supplied
by the user. The virtual file system data is detailed in the /usr/include/sys/vmount.h file. All arguments indicated by this field
are copied to kernel space. |
Execution Environment
The vfs_mount entry point can
be called from the process environment only.
Return Values
Nonzero return values are returned from the /usr/include/sys/errno.h file to indicate failure.
Related Information
The mount subroutine, vmount
subroutine.
Virtual File System Overview, Virtual File System Kernel Extensions Overview, Logical File System Overview in AIX 5L Version 5.2 Kernel Extensions and Device Support Programming Concepts.
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