From: Alberto Garcia <berto@igalia.com>

"qemu-io reopen" doesn't allow changing the writethrough setting of
the cache, but the check is wrong, causing an error even on a simple
reopen with the default parameters:

   $ qemu-img create -f qcow2 hd.qcow2 1M
   $ qemu-system-x86_64 -monitor stdio -drive if=virtio,file=hd.qcow2
   (qemu) qemu-io virtio0 reopen
   Cannot change cache.writeback: Device attached

Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 qemu-io-cmds.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qemu-io-cmds.c b/qemu-io-cmds.c
index 5bf5f28178..db0b3ee5ef 100644
--- a/qemu-io-cmds.c
+++ b/qemu-io-cmds.c
@@ -2025,7 +2025,7 @@ static int reopen_f(BlockBackend *blk, int argc, char **argv)
         return -EINVAL;
     }
 
-    if (writethrough != blk_enable_write_cache(blk) &&
+    if (!writethrough != blk_enable_write_cache(blk) &&
         blk_get_attached_dev(blk))
     {
         error_report("Cannot change cache.writeback: Device attached");
-- 
2.13.6