virtio: de-structify virtio_block status byte

Ron Minnich points out that a struct containing a char is not always
sizeof(char); simplest to remove the structure to avoid confusion.

Cc: "ron minnich" <rminnich@gmail.com>

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

3 files changed, 10 insertions, 15 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 4c1fc65a8b3d..5cd705c3d75b 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -1398,7 +1398,7 @@ static bool service_io(struct device *dev)
         struct vblk_info *vblk = dev->priv;
         unsigned int head, out_num, in_num, wlen;
         int ret;
-        struct virtio_blk_inhdr *in;
+        u8 *in;
         struct virtio_blk_outhdr *out;
         struct iovec iov[dev->vq->vring.num];
         off64_t off;
@@ -1416,7 +1416,7 @@ static bool service_io(struct device *dev)
                      head, out_num, in_num);
 
         out = convert(&iov[0], struct virtio_blk_outhdr);
-        in = convert(&iov[out_num+in_num-1], struct virtio_blk_inhdr);
+        in = convert(&iov[out_num+in_num-1], u8);
         off = out->sector * 512;
 
         /* The block device implements "barriers", where the Guest indicates
@@ -1430,7 +1430,7 @@ static bool service_io(struct device *dev)
          * It'd be nice if we supported eject, for example, but we don't. */
         if (out->type & VIRTIO_BLK_T_SCSI_CMD) {
                 fprintf(stderr, "Scsi commands unsupported\n");
-                in->status = VIRTIO_BLK_S_UNSUPP;
+                *in = VIRTIO_BLK_S_UNSUPP;
                 wlen = sizeof(*in);
         } else if (out->type & VIRTIO_BLK_T_OUT) {
                 /* Write */
@@ -1453,7 +1453,7 @@ static bool service_io(struct device *dev)
                         errx(1, "Write past end %llu+%u", off, ret);
                 }
                 wlen = sizeof(*in);
-                in->status = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
+                *in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
         } else {
                 /* Read */
 
@@ -1466,10 +1466,10 @@ static bool service_io(struct device *dev)
                 verbose("READ from sector %llu: %i\n", out->sector, ret);
                 if (ret >= 0) {
                         wlen = sizeof(*in) + ret;
-                        in->status = VIRTIO_BLK_S_OK;
+                        *in = VIRTIO_BLK_S_OK;
                 } else {
                         wlen = sizeof(*in);
-                        in->status = VIRTIO_BLK_S_IOERR;
+                        *in = VIRTIO_BLK_S_IOERR;
                 }
         }
 
diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index 0cfbe8c594a5..fb283af38023 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -35,7 +35,7 @@ struct virtblk_req
         struct list_head list;
         struct request *req;
         struct virtio_blk_outhdr out_hdr;
-        struct virtio_blk_inhdr in_hdr;
+        u8 status;
 };
 
 static void blk_done(struct virtqueue *vq)
@@ -48,7 +48,7 @@ static void blk_done(struct virtqueue *vq)
         spin_lock_irqsave(&vblk->lock, flags);
         while ((vbr = vblk->vq->vq_ops->get_buf(vblk->vq, &len)) != NULL) {
                 int uptodate;
-                switch (vbr->in_hdr.status) {
+                switch (vbr->status) {
                 case VIRTIO_BLK_S_OK:
                         uptodate = 1;
                         break;
@@ -101,7 +101,7 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
         sg_init_table(vblk->sg, VIRTIO_MAX_SG);
         sg_set_buf(&vblk->sg[0], &vbr->out_hdr, sizeof(vbr->out_hdr));
         num = blk_rq_map_sg(q, vbr->req, vblk->sg+1);
-        sg_set_buf(&vblk->sg[num+1], &vbr->in_hdr, sizeof(vbr->in_hdr));
+        sg_set_buf(&vblk->sg[num+1], &vbr->status, sizeof(vbr->status));
 
         if (rq_data_dir(vbr->req) == WRITE) {
                 vbr->out_hdr.type |= VIRTIO_BLK_T_OUT;
diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index bca0b10d7947..c75a9e82b924 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -41,13 +41,8 @@ struct virtio_blk_outhdr
         __u64 sector;
 };
 
+/* And this is the final byte of the write scatter-gather list. */
 #define VIRTIO_BLK_S_OK         0
 #define VIRTIO_BLK_S_IOERR      1
 #define VIRTIO_BLK_S_UNSUPP     2
-
-/* This is the first element of the write scatter-gather list */
-struct virtio_blk_inhdr
-{
-        unsigned char status;
-};
 #endif /* _LINUX_VIRTIO_BLK_H */