/*
* mbuf chain defragmenter. This function uses some evil tricks to defragment
* an mbuf chain into a single buffer without changing the mbuf pointer.
* This needs to know a lot of the mbuf internals to make this work.
*/
int
m_defrag(struct mbuf *m, int how)
{
struct mbuf *m0;
if (m->m_next == NULL)
return (0);
#ifdef DIAGNOSTIC
if (!(m->m_flags & M_PKTHDR))
panic("m_defrag: no packet hdr or not a chain");
#endif
if ((m0 = m_gethdr(how, m->m_type)) == NULL)
return (ENOBUFS);
if (m->m_pkthdr.len > MHLEN) {
MCLGETI(m0, how, NULL, m->m_pkthdr.len);
if (!(m0->m_flags & M_EXT)) {
m_free(m0);
return (ENOBUFS);
}
}
m_copydata(m, 0, m->m_pkthdr.len, mtod(m0, caddr_t));
m0->m_pkthdr.len = m0->m_len = m->m_pkthdr.len;
/* free chain behind and possible ext buf on the first mbuf */
m_freem(m->m_next);
m->m_next = NULL;
if (m->m_flags & M_EXT)
m_extfree(m);
/*
* Bounce copy mbuf over to the original mbuf and set everything up.
* This needs to reset or clear all pointers that may go into the
* original mbuf chain.
*/
if (m0->m_flags & M_EXT) {
memcpy(&m->m_ext, &m0->m_ext, sizeof(struct mbuf_ext));
MCLINITREFERENCE(m);
m->m_flags |= m0->m_flags & (M_EXT|M_EXTWR);
m->m_data = m->m_ext.ext_buf;
} else {
m->m_data = m->m_pktdat;
memcpy(m->m_data, m0->m_data, m0->m_len);
}
m->m_pkthdr.len = m->m_len = m0->m_len;
m0->m_flags &= ~(M_EXT|M_EXTWR); /* cluster is gone */
m_free(m0);
return (0);
}
void
m_clget(struct mbuf *m, int how)
{
int s;
s = splvm();
m->m_ext.ext_buf =
pool_get(&mclpool, how == M_WAIT ? PR_WAITOK : 0);
splx(s);
if (m->m_ext.ext_buf != NULL) {
m->m_data = m->m_ext.ext_buf;
m->m_flags |= M_EXT|M_CLUSTER;
m->m_ext.ext_size = MCLBYTES;
m->m_ext.ext_free = NULL;
m->m_ext.ext_arg = NULL;
MCLINITREFERENCE(m);
}
}
