Continuation of multi page mbuf redesign from r359919.

The following series of patches addresses three things:

Now that array of pages is embedded into mbuf, we no longer need
separate structure to pass around, so struct mbuf_ext_pgs is an
artifact of the first implementation. And struct mbuf_ext_pgs_data
is a crutch to accomodate the main idea r359919 with minimal churn.

Also, M_EXT of type EXT_PGS are just a synonym of M_NOMAP.

The namespace for the newfeature is somewhat inconsistent and
sometimes has a lengthy prefixes. In these patches we will
gradually bring the namespace to "m_epg" prefix for all mbuf
fields and most functions.

Step 1 of 4:

 o Anonymize mbuf_ext_pgs_data, embed in m_ext
 o Embed mbuf_ext_pgs
 o Start documenting all this entanglement

Reviewed by:	gallatin
Differential Revision:	https://reviews.freebsd.org/D24598

1 files changed, 3 insertions, 3 deletions

diff --git a/sys/kern/subr_bus_dma.c b/sys/kern/subr_bus_dma.c
index 8f8f48fa238d..bfdcc91ff21c 100644
--- a/sys/kern/subr_bus_dma.c
+++ b/sys/kern/subr_bus_dma.c
@@ -141,7 +141,7 @@ _bus_dmamap_load_unmapped_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map,
 			off = 0;
 			len -= seglen;
 			error = _bus_dmamap_load_buffer(dmat, map,
-			    &ext_pgs->m_epg_hdr[segoff], seglen, kernel_pmap,
+			    &m->m_epg_hdr[segoff], seglen, kernel_pmap,
 			    flags, segs, nsegs);
 		}
 	}
@@ -159,7 +159,7 @@ _bus_dmamap_load_unmapped_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map,
 		seglen = min(seglen, len);
 		len -= seglen;
 		error = _bus_dmamap_load_phys(dmat, map,
-		    ext_pgs->m_epg_pa[i] + segoff, seglen, flags, segs, nsegs);
+		    m->m_epg_pa[i] + segoff, seglen, flags, segs, nsegs);
 		pgoff = 0;
 	};
 	if (len != 0 && error == 0) {
@@ -167,7 +167,7 @@ _bus_dmamap_load_unmapped_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map,
 		    ("off + len > trail (%d + %d > %d)", off, len,
 		    ext_pgs->trail_len));
 		error = _bus_dmamap_load_buffer(dmat, map,
-		    &ext_pgs->m_epg_trail[off], len, kernel_pmap, flags, segs,
+		    &m->m_epg_trail[off], len, kernel_pmap, flags, segs,
 		    nsegs);
 	}
 	return (error);