1 files changed, 15 insertions, 3 deletions

diff --git a/include/linux/virtio_blk.h b/include/linux/virtio_blk.h
index 8dab9f2b8832..15cb666581d7 100644
--- a/include/linux/virtio_blk.h
+++ b/include/linux/virtio_blk.h
@@ -5,9 +5,6 @@
 #include <linux/types.h>
 #include <linux/virtio_config.h>
 
-/* The ID for virtio_block */
-#define VIRTIO_ID_BLOCK 2
-
 /* Feature bits */
 #define VIRTIO_BLK_F_BARRIER    0       /* Does host support barriers? */
 #define VIRTIO_BLK_F_SIZE_MAX   1       /* Indicates maximum segment size */
@@ -17,6 +14,7 @@
 #define VIRTIO_BLK_F_BLK_SIZE   6       /* Block size of disk is available*/
 #define VIRTIO_BLK_F_SCSI       7       /* Supports scsi command passthru */
 #define VIRTIO_BLK_F_IDENTIFY   8       /* ATA IDENTIFY supported */
+#define VIRTIO_BLK_F_FLUSH      9       /* Cache flush command support */
 
 #define VIRTIO_BLK_ID_BYTES     (sizeof(__u16[256]))    /* IDENTIFY DATA */
 
@@ -38,6 +36,17 @@ struct virtio_blk_config {
         __u8 identify[VIRTIO_BLK_ID_BYTES];
 } __attribute__((packed));
 
+/*
+ * Command types
+ *
+ * Usage is a bit tricky as some bits are used as flags and some are not.
+ *
+ * Rules:
+ *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
+ *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
+ *   and may not be combined with any of the other flags.
+ */
+
 /* These two define direction. */
 #define VIRTIO_BLK_T_IN         0
 #define VIRTIO_BLK_T_OUT        1
@@ -45,6 +54,9 @@ struct virtio_blk_config {
 /* This bit says it's a scsi command, not an actual read or write. */
 #define VIRTIO_BLK_T_SCSI_CMD   2
 
+/* Cache flush command */
+#define VIRTIO_BLK_T_FLUSH      4
+
 /* Barrier before this op. */
 #define VIRTIO_BLK_T_BARRIER    0x80000000