1.\" 2.\" Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice(s), this list of conditions and the following disclaimer as 9.\" the first lines of this file unmodified other than the possible 10.\" addition of one or more copyright notices. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice(s), this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY 16.\" EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18.\" DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE LIABLE FOR ANY 19.\" DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 20.\" (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21.\" SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 22.\" CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH 25.\" DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd November 21, 2001 30.Dt VFSCONF 9 31.Os 32.Sh NAME 33.Nm vfsconf 34.Nd "vfs configuration information" 35.Sh SYNOPSIS 36.In sys/param.h 37.In sys/mount.h 38.Ft int 39.Fn vfs_register "struct vfsconf *vfc" 40.Ft int 41.Fn vfs_unregister "struct vfsconf *vfc" 42.Ft int 43.Fn vfs_modevent "module_t mod" "int type" "void *data" 44.Sh DESCRIPTION 45Each filesystem type known to the kernel has a 46.Vt vfsconf 47structure that contains the 48information required to create a new mount of that filesystems type. 49.Bd -literal 50struct vfsconf { 51 struct vfsops *vfc_vfsops; /* filesystem operations vector */ 52 char vfc_name[MFSNAMELEN]; /* filesystem type name */ 53 int vfc_typenum; /* historic filesystem type number */ 54 int vfc_refcount; /* number mounted of this type */ 55 int vfc_flags; /* permanent flags */ 56 struct vfsconf *vfc_next; /* next in list */ 57}; 58.Ed 59.Pp 60When a new filesystem is mounted, 61.Xr vfs_mount 9 62does a lookup of the 63.Vt vfsconf 64structure by its name, and if it is not already registered, 65attempts to load a kernel module for it. 66The filesystem operations for the new mount point are taken from 67.Va vfc_vfsops , 68and 69.Va mnt_vfc 70in the 71.Vt mount 72structure is made to point directly at the 73.Vt vfsconf 74structure for the 75filesystem type. 76The filesystem type number is taken from 77.Va vfc_typenum 78which was assigned in 79.Fn vfs_register , 80and the mount flags are taken from a mask of 81.Va vfc_flags . 82Each time a filesystem of a given type is mounted, 83.Va vfc_refcount 84is incremented. 85.Pp 86.Fn vfs_register 87takes a new 88.Vt vfsconf 89structure and adds it to the list of existing filesystems. 90If the type has not already been registered, it is initialized by calling the 91.Fn vfs_init 92function in the filesystem operations vector. 93.Fn vfs_register 94also updates the oid's of any sysctl nodes for this filesystem type 95to be the same as the newly assigned type number. 96.Pp 97.Fn vfs_unregister 98unlinks 99.Fa vfc 100from the list of registered filesystem types if there are currently no mounted instances. 101If the 102.Fn vfs_uninit 103function in the filesystems initialization vector is defined, it is called. 104.Pp 105.Fn vfs_modevent 106is registered by 107.Fn VFS_SET 108to handle the loading and unloading of filesystem kernel modules. 109In the case of 110.Dv MOD_LOAD , 111.Fn vfs_register 112is called. 113In the case of 114.Dv MOD_UNLOAD , 115.Fn vfs_unregister 116is called. 117.Sh RETURN VALUES 118.Fn vfs_register 119returns 0 if successful; otherwise, 120.Er EEXIST 121is returned indicating that the filesystem type has already been registered. 122.Pp 123.Fn vfs_unregister 124returns 0 if successful. 125If no 126.Vt vfsconf 127entry can be found matching the name in 128.Fa vfc , 129.Er EINVAL 130is returned. 131If the reference count of mounted instances of the filesystem type is not zero, 132.Er EBUSY 133is returned. 134If 135.Fn vfs_uninit 136is called, any errors it returns will be returned by 137.Fn vfs_unregister . 138.Pp 139.Fn vfs_modevent 140returns the result of the call to 141.Fn vfs_register 142or 143.Fn vfs_unregister , 144whatever the case. 145.Sh SEE ALSO 146.Xr vfs_mount 9 , 147.Xr vfs_rootmountalloc 9 , 148.Xr VFS_SET 9 149.Sh AUTHORS 150This man page was written by 151.An Chad David Aq davidc@acns.ab.ca . 152