vfs_getnewfsid(9)

NAME

vfs_getnewfsid - allocate a new file system identifier

#include <sys/param.h>
#include <sys/mount.h>
void
vfs_getnewfsid(struct mount *mp);

The vfs_getnewfsid() function allocates a new file system
identifier for the mount point given. File systems typically call
vfs_getnewfsid() in
their mount routine in order to acquire a unique ID within
the system which can later be used to uniquely identify the file system
via calls such as vfs_getvfs(9).
The actual fsid is made up of two 32 bit integers, that are
stored in the statfs structure of mp. The first integer is unique in the
set of mounted file systems, while the second holds the file system
type.
typedef struct fsid {: int32_t val[2];
} fsid_t;

xxx_mount(struct mount *mp, char *path, caddr_t data,: struct nameidata *ndp, struct thread *td)
{: ...
vfs_getnewfsid(mp);
...
}