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>

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 4c1fc65..5cd705c 100644 (file)
--- 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 0cfbe8c..fb283af 100644 (file)
--- 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 bca0b10..c75a9e8 100644 (file)
--- 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 */