Проект OpenNet: MAN vfsconf (9) Ядро (FreeBSD и Linux)

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vfsconf (9)

>> vfsconf (9) ( FreeBSD man: Ядро )

BSD mandoc

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 Vt 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, vfs_mount9 does a lookup of the Vt 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 Vt mount structure is made to point directly at the Vt 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 Vt 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 Fa 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, Er EEXIST is returned indicating that the file system type has already been registered.

vfs_unregister ();
returns 0 if successful. If no Vt vfsconf entry can be found matching the name in Fa vfc , Er EINVAL is returned. If the reference count of mounted instances of the file system type is not zero, Er 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.