x86/dma_bounce: revert r289834 and r289836

The new load_ma implementation can cause dereferences when used with
certain drivers, back it out until the reason is found:

Fatal trap 12: page fault while in kernel mode
cpuid = 11; apic id = 03
fault virtual address   = 0x30
fault code              = supervisor read data, page not present
instruction pointer     = 0x20:0xffffffff808a2d22
stack pointer           = 0x28:0xfffffe07cc737710
frame pointer           = 0x28:0xfffffe07cc737790
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, long 1, def32 0, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 13 (g_down)
trap number             = 12
panic: page fault
cpuid = 11
KDB: stack backtrace:
#0 0xffffffff80641647 at kdb_backtrace+0x67
#1 0xffffffff80606762 at vpanic+0x182
#2 0xffffffff806067e3 at panic+0x43
#3 0xffffffff8084eef1 at trap_fatal+0x351
#4 0xffffffff8084f0e4 at trap_pfault+0x1e4
#5 0xffffffff8084e82f at trap+0x4bf
#6 0xffffffff80830d57 at calltrap+0x8
#7 0xffffffff8063beab at _bus_dmamap_load_ccb+0x1fb
#8 0xffffffff8063bc51 at bus_dmamap_load_ccb+0x91
#9 0xffffffff8042dcad at ata_dmaload+0x11d
#10 0xffffffff8042df7e at ata_begin_transaction+0x7e
#11 0xffffffff8042c18e at ataaction+0x9ce
#12 0xffffffff802a220f at xpt_run_devq+0x5bf
#13 0xffffffff802a17ad at xpt_action_default+0x94d
#14 0xffffffff802c0024 at adastart+0x8b4
#15 0xffffffff802a2e93 at xpt_run_allocq+0x193
#16 0xffffffff802c0735 at adastrategy+0xf5
#17 0xffffffff80554206 at g_disk_start+0x426
Uptime: 2m29s

1 files changed, 5 insertions, 7 deletions

diff --git a/sys/dev/xen/blkfront/blkfront.c b/sys/dev/xen/blkfront/blkfront.c
index 0a75d79..fa8d479 100644
--- a/sys/dev/xen/blkfront/blkfront.c
+++ b/sys/dev/xen/blkfront/blkfront.c
@@ -293,12 +293,8 @@ xbd_queue_request(struct xbd_softc *sc, struct xbd_command *cm)
 {
 	int error;
 
-	if (cm->cm_bp != NULL)
-		error = bus_dmamap_load_bio(sc->xbd_io_dmat, cm->cm_map,
-		    cm->cm_bp, xbd_queue_cb, cm, 0);
-	else
-		error = bus_dmamap_load(sc->xbd_io_dmat, cm->cm_map,
-		    cm->cm_data, cm->cm_datalen, xbd_queue_cb, cm, 0);
+	error = bus_dmamap_load(sc->xbd_io_dmat, cm->cm_map, cm->cm_data,
+	    cm->cm_datalen, xbd_queue_cb, cm, 0);
 	if (error == EINPROGRESS) {
 		/*
 		 * Maintain queuing order by freezing the queue.  The next
@@ -358,6 +354,8 @@ xbd_bio_command(struct xbd_softc *sc)
 	}
 
 	cm->cm_bp = bp;
+	cm->cm_data = bp->bio_data;
+	cm->cm_datalen = bp->bio_bcount;
 	cm->cm_sector_number = (blkif_sector_t)bp->bio_pblkno;
 
 	switch (bp->bio_cmd) {
@@ -1011,7 +1009,7 @@ xbd_instance_create(struct xbd_softc *sc, blkif_sector_t sectors,
 
 	sc->xbd_disk->d_mediasize = sectors * sector_size;
 	sc->xbd_disk->d_maxsize = sc->xbd_max_request_size;
-	sc->xbd_disk->d_flags = DISKFLAG_UNMAPPED_BIO;
+	sc->xbd_disk->d_flags = 0;
 	if ((sc->xbd_flags & (XBDF_FLUSH|XBDF_BARRIER)) != 0) {
 		sc->xbd_disk->d_flags |= DISKFLAG_CANFLUSHCACHE;
 		device_printf(sc->xbd_dev,