VFSSUBR(9)						   BSD Kernel Developer's Manual						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_mountalloc, 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

     #include <sys/param.h>
     #include <sys/mount.h>
     #include <sys/vnode.h>

     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);

     struct mount *
     vfs_mountalloc(struct vfsops *vfs, struct vnode *vp);

     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 sys-
	      tem.

     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_mountalloc(vfsops, vp)
	      Allocate and initialise a mount structure, setting mnt_vnodecovered to vp and mnt_op to vfsops.  On success, mark the mount struc-
	      ture as busy and return its address.  Otherwise, return NULL.

     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 allo-
	      cated 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

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

SEE ALSO

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

BSD
								    May 9, 2009 							       BSD