virtio: make add_buf return capacity remaining

This API change means that virtio_net can tell how much capacity
remains for buffers.  It's necessarily fuzzy, since
VIRTIO_RING_F_INDIRECT_DESC means we can fit any number of descriptors
in one, *if* we can kmalloc.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dinesh Subhraveti <dineshs@us.ibm.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c
index aa1a3d5a3e2..d739ee4201f 100644
--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -139,7 +139,7 @@ static bool do_req(struct request_queue *q, struct virtio_blk *vblk,
                 }
         }
 
-        if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr)) {
+        if (vblk->vq->vq_ops->add_buf(vblk->vq, vblk->sg, out, in, vbr) < 0) {
                 mempool_free(vbr, vblk->pool);
                 return false;
         }