Where is the implementation of dm_task_create in cryptsetup?

Where is the implementation of the function dm_task_create in cryptsetup (and other dm_task_ related functions)? Grepping for this function in the source for cryptsetup I come up with nothing. I see it is used in lib/libdevmapper.c and that it has a function prototype in libdevmapper.h. However where is the implementation? As a side note, cryptsetup compiles fine and executes.

Just to check, I grepped through the kernel source as well but it doesn't appear to be implemented in the kernel either.

From the following link http://www.saout.de/pipermail/dm-crypt/2009-December/000464.html it appears that at least in the past it was implemented in libdevmapper.c.

It's implemented in libdm-common.c, which is part of libdm (lib device-mapper). It is not implemented as part of cryptsetup itself.

This code is maintained alongside LVM2, as documented on this page:

The userspace code (dmsetup and libdevmapper) is now maintained alongside the LVM2 source available from http://sources.redhat.com/lvm2/. To build / install it without LVM2 use 'make device-mapper' / 'make device-mapper_install'.

Here's the implementation:

struct dm_task *dm_task_create(int type)
{
    struct dm_task *dmt = dm_zalloc(sizeof(*dmt));

    if (!dmt) {
        log_error("dm_task_create: malloc(%" PRIsize_t ") failed",
              sizeof(*dmt));
        return NULL;
    }

    if (!dm_check_version()) {
        dm_free(dmt);
        return_NULL;
    }

    dmt->type = type;
    dmt->minor = -1;
    dmt->major = -1;
    dmt->allow_default_major_fallback = 1;
    dmt->uid = DM_DEVICE_UID;
    dmt->gid = DM_DEVICE_GID;
    dmt->mode = DM_DEVICE_MODE;
    dmt->no_open_count = 0;
    dmt->read_ahead = DM_READ_AHEAD_AUTO;
    dmt->read_ahead_flags = 0;
    dmt->event_nr = 0;
    dmt->cookie_set = 0;
    dmt->query_inactive_table = 0;
    dmt->new_uuid = 0;
    dmt->secure_data = 0;

    return dmt;
}