Author: bryanv
Date: Tue Mar 5 07:00:05 2013
New Revision: 247829
URL: http://svnweb.freebsd.org/changeset/base/247829
Log:
Only set the barrier flag if the feature was negotiated
When the VirtIO barrier feature is not negotiated, the driver
must enforce the proper ordering for BIO_ORDERED BIOs. All the
in-flight BIOs must complete before starting the BIO, and the
ordered BIO must complete before subsequent BIOs can start.
Also fix a few whitespace nits.
Reported by: neel
Approved by: grehan (mentor)
MFC after: 3 days
Modified:
head/sys/dev/virtio/block/virtio_blk.c
Modified: head/sys/dev/virtio/block/virtio_blk.c
==============================================================================
--- head/sys/dev/virtio/block/virtio_blk.c Tue Mar 5 06:43:54 2013
(r247828)
+++ head/sys/dev/virtio/block/virtio_blk.c Tue Mar 5 07:00:05 2013
(r247829)
@@ -72,6 +72,7 @@ struct vtblk_softc {
#define VTBLK_FLAG_DETACH 0x0004
#define VTBLK_FLAG_SUSPEND 0x0008
#define VTBLK_FLAG_DUMPING 0x0010
+#define VTBLK_FLAG_BARRIER 0x0020
struct virtqueue *vtblk_vq;
struct sglist *vtblk_sglist;
@@ -81,7 +82,8 @@ struct vtblk_softc {
TAILQ_HEAD(, vtblk_request)
vtblk_req_free;
TAILQ_HEAD(, vtblk_request)
- vtblk_req_ready;
+ vtblk_req_ready;
+ struct vtblk_request *vtblk_req_ordered;
struct taskqueue *vtblk_tq;
struct task vtblk_intr_task;
@@ -278,9 +280,10 @@ vtblk_attach(device_t dev)
if (virtio_with_feature(dev, VIRTIO_RING_F_INDIRECT_DESC))
sc->vtblk_flags |= VTBLK_FLAG_INDIRECT;
-
if (virtio_with_feature(dev, VIRTIO_BLK_F_RO))
sc->vtblk_flags |= VTBLK_FLAG_READONLY;
+ if (virtio_with_feature(dev, VIRTIO_BLK_F_BARRIER))
+ sc->vtblk_flags |= VTBLK_FLAG_BARRIER;
/* Get local copy of config. */
virtio_read_device_config(dev, 0, &blkcfg,
@@ -766,25 +769,45 @@ vtblk_bio_request(struct vtblk_softc *sc
bp->bio_cmd);
}
- if (bp->bio_flags & BIO_ORDERED)
- req->vbr_hdr.type |= VIRTIO_BLK_T_BARRIER;
-
return (req);
}
static int
vtblk_execute_request(struct vtblk_softc *sc, struct vtblk_request *req)
{
+ struct virtqueue *vq;
struct sglist *sg;
struct bio *bp;
- int readable, writable, error;
+ int ordered, readable, writable, error;
+ vq = sc->vtblk_vq;
sg = sc->vtblk_sglist;
bp = req->vbr_bp;
+ ordered = 0;
writable = 0;
VTBLK_LOCK_ASSERT(sc);
+ /*
+ * Wait until the ordered request completes before
+ * executing subsequent requests.
+ */
+ if (sc->vtblk_req_ordered != NULL)
+ return (EBUSY);
+
+ if (bp->bio_flags & BIO_ORDERED) {
+ if ((sc->vtblk_flags & VTBLK_FLAG_BARRIER) == 0) {
+ /*
+ * This request will be executed once all
+ * the in-flight requests are completed.
+ */
+ if (!virtqueue_empty(vq))
+ return (EBUSY);
+ ordered = 1;
+ } else
+ req->vbr_hdr.type |= VIRTIO_BLK_T_BARRIER;
+ }
+
sglist_reset(sg);
sglist_append(sg, &req->vbr_hdr, sizeof(struct virtio_blk_outhdr));
@@ -802,10 +825,13 @@ vtblk_execute_request(struct vtblk_softc
writable++;
sglist_append(sg, &req->vbr_ack, sizeof(uint8_t));
-
readable = sg->sg_nseg - writable;
- return (virtqueue_enqueue(sc->vtblk_vq, req, sg, readable, writable));
+ error = virtqueue_enqueue(vq, req, sg, readable, writable);
+ if (error == 0 && ordered)
+ sc->vtblk_req_ordered = req;
+
+ return (error);
}
static int
@@ -1013,6 +1039,12 @@ vtblk_finish_completed(struct vtblk_soft
while ((req = virtqueue_dequeue(sc->vtblk_vq, NULL)) != NULL) {
bp = req->vbr_bp;
+ if (sc->vtblk_req_ordered != NULL) {
+ /* This should be the only outstanding request. */
+ MPASS(sc->vtblk_req_ordered == req);
+ sc->vtblk_req_ordered = NULL;
+ }
+
error = vtblk_request_error(req);
if (error)
disk_err(bp, "hard error", -1, 1);
@@ -1039,6 +1071,7 @@ vtblk_drain_vq(struct vtblk_softc *sc, i
vtblk_enqueue_request(sc, req);
}
+ sc->vtblk_req_ordered = NULL;
KASSERT(virtqueue_empty(vq), ("virtqueue not empty"));
}
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