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vfs_unregister(9) [freebsd man page]

VFSCONF(9)						   BSD Kernel Developer's Manual						VFSCONF(9)

NAME
vfsconf -- vfs configuration information SYNOPSIS
#include <sys/param.h> #include <sys/mount.h> int vfs_register(struct vfsconf *vfc); int vfs_unregister(struct vfsconf *vfc); int vfs_modevent(module_t mod, int type, void *data); DESCRIPTION
Each file system type known to the kernel has a vfsconf structure that contains the information required to create a new mount of that file systems type. struct vfsconf { struct vfsops *vfc_vfsops; /* file system operations vector */ char vfc_name[MFSNAMELEN]; /* file system type name */ int vfc_typenum; /* historic file system type number */ int vfc_refcount; /* number mounted of this type */ int vfc_flags; /* permanent flags */ struct vfsconf *vfc_next; /* next in list */ }; When a new file system is mounted, mount(2) does a lookup of the vfsconf structure by its name, and if it is not already registered, attempts to load a kernel module for it. The file system 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 vfsconf structure for the file system type. The file system type number is taken from vfc_typenum which was assigned in vfs_register(), and the mount flags are taken from a mask of vfc_flags. Each time a file system of a given type is mounted, vfc_refcount is incremented. vfs_register() takes a new vfsconf structure and adds it to the list of existing file systems. If the type has not already been registered, it is initialized by calling the vfs_init() function in the file system operations vector. vfs_register() also updates the oid's of any sysctl nodes for this file system type to be the same as the newly assigned type number. vfs_unregister() unlinks vfc from the list of registered file system types if there are currently no mounted instances. If the vfs_uninit() function in the file systems initialization vector is defined, it is called. vfs_modevent() is registered by VFS_SET() to handle the loading and unloading of file system kernel modules. In the case of MOD_LOAD, vfs_register() is called. In the case of MOD_UNLOAD, vfs_unregister() is called. RETURN VALUES
vfs_register() returns 0 if successful; otherwise, EEXIST is returned indicating that the file system type has already been registered. vfs_unregister() returns 0 if successful. If no vfsconf entry can be found matching the name in vfc, EINVAL is returned. If the reference count of mounted instances of the file system type is not zero, EBUSY is returned. If vfs_uninit() is called, any errors it returns will be returned by vfs_unregister(). vfs_modevent() returns the result of the call to vfs_register() or vfs_unregister(), whatever the case. SEE ALSO
mount(2), vfs_rootmountalloc(9), VFS_SET(9) AUTHORS
This manual page was written by Chad David <davidc@acns.ab.ca>. BSD
June 16, 2013 BSD

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VFS_SET(9)						   BSD Kernel Developer's Manual						VFS_SET(9)

NAME
VFS_SET -- set up loadable file system vfsconf SYNOPSIS
#include <sys/param.h> #include <sys/kernel.h> #include <sys/module.h> #include <sys/mount.h> void VFS_SET(struct vfsops *vfsops, fsname, int flags); DESCRIPTION
VFS_SET() creates a vfsconf structure for the loadable module with the given vfsops, fsname and flags, and declares it by calling DECLARE_MODULE(9) using vfs_modevent() as the event handler. Possible values for the flags argument are: VFCF_STATIC File system should be statically available in the kernel. VFCF_NETWORK Network exportable file system. VFCF_READONLY Does not support write operations. VFCF_SYNTHETIC Pseudo file system, data does not represent on-disk files. VFCF_LOOPBACK Loopback file system layer. VFCF_UNICODE File names are stored as Unicode. VFCF_JAIL Can be mounted from within a jail if security.jail.mount_allowed sysctl is set to 1. VFCF_DELEGADMIN Supports delegated administration if vfs.usermount sysctl is set to 1. VFCF_SBDRY When in VFS method, the thread suspension is deferred to the user boundary upon arrival of stop action. PSEUDOCODE
/* * Fill in the fields for which we have special methods. * The others are initially null. This tells vfs to change them to * pointers to vfs_std* functions during file system registration. */ static struct vfsops myfs_vfsops = { .vfs_mount = myfs_mount, .vfs_root = myfs_root, .vfs_statfs = myfs_statfs, .vfs_unmount = myfs_unmount, }; VFS_SET(myfs_vfsops, myfs, 0); SEE ALSO
jail(2), jail(8), DECLARE_MODULE(9), vfs_modevent(9), vfsconf(9) AUTHORS
This manual page was written by Chad David <davidc@acns.ab.ca>. BSD
February 21, 2013 BSD
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