Copyright (C) 2001 Chad David <davidc@acns.ab.ca>. All rights reserved.

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$FreeBSD: head/share/man/man9/vfsconf.9 87252 2001-12-03 00:25:04Z alfred $

.Dd November 21, 2001 .Dt VFSCONF 9 .Os .Sh NAME .Nm vfsconf .Nd "vfs configuration information" .Sh SYNOPSIS n sys/param.h n sys/mount.h .Ft int .Fn vfs_register "struct vfsconf *vfc" .Ft int .Fn vfs_unregister "struct vfsconf *vfc" .Ft int .Fn vfs_modevent "module_t mod" "int type" "void *data" .Sh DESCRIPTION Each filesystem type known to the kernel has a vfsconf structure that contains the information required to create a new mount of that filesystems type. d -literal struct vfsconf { struct vfsops *vfc_vfsops; /* filesystem operations vector */ char vfc_name[MFSNAMELEN]; /* filesystem type name */ int vfc_typenum; /* historic filesystem type number */ int vfc_refcount; /* number mounted of this type */ int vfc_flags; /* permanent flags */ struct vfsconf *vfc_next; /* next in list */ }; .Ed When a new filesystem is mounted .Fn vfs_mount does a lookup of the vfcconf structure by its name, and if it is not already registered, attempts to load a kernel module for it. The filesystem operations for the new mount point are taken from vfc_vfsops, and mnt_vfc in the mount structure is made to point directly at the vfcconf structure for the filesystem type. The filesystem type number is taken from vfs_typenum which was assigned in .Fn vfs_register , and the mount flags are taken from a mask of vfc_flags. Each time a filesystem of a given type is mounted vfc_refcount is incremented.

p .Fn vfs_register takes a new vfsconf structure and adds it to the list of existing filesystems. If the type has not already been registered it is initialize by calling the .Fn vfs_init function in the filesystem operations vector. .Fn vfs_register also updates the oid's of any sysctl nodes for this filesystem type to be the same as the newly assigned type number.

p .Fn vfs_unregister unlinks .Fa vfc from the list of registered filesystem types if there are currently no mounted instances. If the .Fn vfs_uninit function in the filesystems initialization vector is defined it is called.

p .Fn vfs_modevent is registered by .Fn VFS_SET to handle the loading and unloading of filesystem kernel modules. In the case of .Dv MOD_LOAD .Fn vfs_register is called. In the case of .Dv MOD_UNLOAD .Fn vfs_unregister is called. .Sh RETURN VALUES .Fn vfs_register returns 0 if successful; otherwise, .Dv EEXIST is returned indicating that the filesystem type has already been registered.

p .Fn vfs_unregister returns 0 if successful. If no vfsconf entry can be found matching the name in .Fa vfc , .Dv EINVAL is returned. If the reference count of mounted instances of the filesystem type is not zero .Dv EBUSY is returned. If .Fn vfs_uninit is called any errors it returns will be returned by .Fn vfs_unregister .

p .Fn vfs_modevent returns the result of the call to .Fn vfs_register or .Fn vfs_unregister whatever the case. .Sh SEE ALSO .Xr vfs_rootmountalloc 9 , .Xr vfs_mount , .Xr VFS_SET 9 .Sh AUTHORS This man page was written by .An Chad David Aq davidc@acns.ab.ca .