[Qemu-devel] [RFC v9 13/27] virtio-blk: Increase max requests for indirect vring

[Stefan Hajnoczi]

With indirect vring descriptors, one can no longer assume that the
maximum number of requests is VRING_MAX / 2 (outhdr and inhdr).  Now a
single indirect descriptor can contain the outhdr and inhdr so max
requests becomes VRING_MAX.

Signed-off-by: Stefan Hajnoczi <address@hidden>
---
 hw/virtio-blk.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c
index 591eace..7ae3c56 100644
--- a/hw/virtio-blk.c
+++ b/hw/virtio-blk.c
@@ -26,7 +26,9 @@
 enum {
     SEG_MAX = 126,                  /* maximum number of I/O segments */
     VRING_MAX = SEG_MAX + 2,        /* maximum number of vring descriptors */
-    REQ_MAX = VRING_MAX / 2,        /* maximum number of requests in the vring 
*/
+    REQ_MAX = VRING_MAX,            /* maximum number of requests in the vring,
+                                     * is VRING_MAX / 2 with traditional and
+                                     * VRING_MAX with indirect descriptors */
 };
 
 typedef struct {
-- 
1.7.10.4