qemu-img: Print available options with -o ?

This patch adds a small help text to each of the options in the block drivers
which can be displayed by using qemu-img create -f fmt -o ?

Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/block/cow.c b/block/cow.c
index 41d292aac2..84818f1034 100644
--- a/block/cow.c
+++ b/block/cow.c
@@ -262,8 +262,16 @@ static void cow_flush(BlockDriverState *bs)
 }
 
 static QEMUOptionParameter cow_create_options[] = {
-    { BLOCK_OPT_SIZE,           OPT_SIZE },
-    { BLOCK_OPT_BACKING_FILE,   OPT_STRING },
+    {
+        .name = BLOCK_OPT_SIZE,
+        .type = OPT_SIZE,
+        .help = "Virtual disk size"
+    },
+    {
+        .name = BLOCK_OPT_BACKING_FILE,
+        .type = OPT_STRING,
+        .help = "File name of a base image"
+    },
     { NULL }
 };