xref: /freebsd/share/man/man9/vfs_getnewfsid.9 (revision 2008043f386721d58158e37e0d7e50df8095942d)
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27.Dd November 21, 2001
28.Dt VFS_GETNEWFSID 9
29.Os
30.Sh NAME
31.Nm vfs_getnewfsid
32.Nd "allocate a new file system identifier"
33.Sh SYNOPSIS
34.In sys/param.h
35.In sys/mount.h
36.Ft void
37.Fn vfs_getnewfsid "struct mount *mp"
38.Sh DESCRIPTION
39The
40.Fn vfs_getnewfsid
41function allocates a new file system identifier for the mount point given.
42File systems typically call
43.Fn vfs_getnewfsid
44in their mount routine in order to acquire a unique ID within the system
45which can later be used to uniquely identify the file system via calls such as
46.Xr vfs_getvfs 9 .
47.Pp
48The actual
49.Vt fsid
50is made up of two 32 bit integers, that are stored in the
51.Vt statfs
52structure of
53.Fa mp .
54The first integer is unique in the set of mounted file systems,
55while the second holds the file system type.
56.Bd -literal
57typedef	struct fsid {
58	int32_t val[2];
59} fsid_t;
60.Ed
61.Sh PSEUDOCODE
62.Bd -literal
63xxx_mount(struct mount *mp, char *path, caddr_t data,
64	struct nameidata *ndp, struct thread *td)
65{
66	...
67	vfs_getnewfsid(mp);
68	...
69}
70.Ed
71.Sh SEE ALSO
72.Xr vfs_getvfs 9
73.Sh AUTHORS
74This manual page was written by
75.An Chad David Aq Mt davidc@acns.ab.ca .
76