January 21, 2007 VFSSUBR 9

### NAME

vfssubr, vfs_getnewfsid, vfs_getvfs, vfs_export, vfs_showexport, vfs_export_lookup, vfs_setpublicfs, vfs_mountedon, vfs_mountroot, vfs_unmountall, vfs_busy, vfs_unbusy, vfs_rootmountalloc, vfs_shutdown, vfs_attach, vfs_detach, vfs_reinit, vfs_getopsbyname, vfs_suspend, vfs_resume - high-level interface to kernel file system interface

### SYNOPSIS

```void` vfs_getnewfsid(```struct mount *mp`)
```struct` `mount``*` vfs_getvfs(```fsid_t *fsid`)
```int` vfs_export_lookup(```struct mount *mp``, struct netexport *nep``, struct export_args *argp`)
```int` vfs_setpublicfs(```struct mount *mp``, struct netexport *nep``, struct export_args *argp`)
```int` vfs_mountedon(```struct vnode *vp`)
```int` vfs_mountroot(```void`)
```void` vfs_unmountall(```struct lwp *l`)
```int` vfs_busy(```struct mount *mp``, int flags``, struct simplelock *interlkp`)
```void` vfs_unbusy(```struct mount *mp`)
```int` vfs_rootmountalloc(```char *fstypename``, char *devname``, struct mount **mpp`)
```void` vfs_shutdown(```void`)
```int` vfs_attach(```struct vfsops *vfs`)
```int` vfs_detach(```struct vfsops *vfs`)
```void` vfs_reinit(```void`)
```struct` `vfsops``*` vfs_getopsbyname(```const char *name`)
```int` vfs_suspend(```struct mount *mp``, int nowait`)
```void` vfs_resume(```struct mount *mp`)

### DESCRIPTION

The high-level functions described in this page are the interface to the kernel file system interface (VFS).

### FUNCTIONS

vfs_getnewfsid(```mp`)
  Get a new unique file system id type for the file system specified by the mount structure ```mp`. The file system id type is stored in mp->mnt_stat.f_fsidx.

vfs_getvfs(```fsid`)
  Lookup a mount point with the file system identifier ```fsid`.

vfs_export_lookup(```mp``, nep``, argp`)
  Check client permission on the exportable file system specified by the mount structure ```mp`. The argument ```nam` is the address of the networked client. This function is used by file system type specific functions to verify that the client can access the file system.

vfs_setpublicfs(```mp``, nep``, argp`)
  Set the publicly exported file system specified by the mount structure ```mp`.

vfs_mountedon(```vp`)
  Check to see if a file system is mounted on a block device specified by the vnode ```vp`.

vfs_mountroot(```void`)
  Mount the root file system.

vfs_unmountall(```l`)
  Unmount all file systems.

vfs_busy(```mp``, flags``, interlkp`)
  Mark the mount point specified by ```mp` as busy. This function is used to synchronize access and to delay unmounting. The interlock specified by argument ```interlkp` is not released on failure.

vfs_unbusy(```mp`)
  Free the busy file system specified by the mount structure ```mp`.

vfs_rootmountalloc(```fstypename``, devname``, mpp`)
  Lookup a file system type specified by the name ```fstypename` and if found allocate and initialise a mount structure for it. The allocated mount structure is returned in the address specified by ```mpp`. The device the root file system was mounted from is specified by the argument ```devname` and is recorded in the new mount structure.

vfs_shutdown(``)
  Sync and unmount all file systems before shutting down. Invoked by cpu_reboot(9).

vfs_attach(```vfs`)
  Establish file system ```vfs` and initialise it.

vfs_detach(```vfs`)
  Remove file system ```vfs` from the kernel.

vfs_reinit(```void`)
  Reinitialises all file systems within the kernel through file system-specific vfs operation (see vfsops(9)).

vfs_getopsbyname(```name`)
  Given a file system name specified by ```name`, look up the vfs operations for that file system (see vfsops(9)), or return ```NULL` if file system isn't present in the kernel.

vfs_suspend(```mp``, nowait`)
  Request a mounted file system to suspend all operations. All new operations to the file system are stopped. After all operations in progress have completed, the file system is synced to disk and the function returns. If a file system suspension is currently in progress and ```nowait` is set ```EWOULDBLOCK` is returned. If the operation is successful, zero is returned, otherwise an appropriate error code is returned.

vfs_resume(```mp`)
  Request a mounted file system to resume operations.

### CODE REFERENCES

This section describes places within the NetBSD source tree where actual code implementing or using the vfs operations can be found. All pathnames are relative to ```/usr/src`.

The vfs interface functions are implemented within the files ```sys/kern/vfs_subr.c`, ```sys/kern/vfs_subr2.c`, and ```sys/kern/vfs_init.c`.

### SEE ALSO

intro(9), namei(9), vfs(9), vfsops(9), vnode(9), vnodeops(9)