From 786dba91d1222f9123dd1a18f73f0353619d49b3 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Mon, 9 Mar 2020 12:52:34 +0000
Subject: [PATCH] Revert "lib: Autodetect backing format and specify it
 explicitly."

This reverts commit 92fd5d5d40a39035824fe8f20ce3cb0871367b4a.

See discussion here:
https://www.redhat.com/archives/libguestfs/2020-March/thread.html#00041
---
 lib/create.c | 13 -------------
 1 file changed, 13 deletions(-)

diff --git a/lib/create.c b/lib/create.c
index f7b78255c..44a7df25f 100644
--- a/lib/create.c
+++ b/lib/create.c
@@ -255,7 +255,6 @@ disk_create_qcow2 (guestfs_h *g, const char *filename, int64_t size,
                    const struct guestfs_disk_create_argv *optargs)
 {
   const char *backingformat = NULL;
-  CLEANUP_FREE char *backingformat_free = NULL;
   const char *preallocation = NULL;
   const char *compat = NULL;
   int clustersize = -1;
@@ -303,18 +302,6 @@ disk_create_qcow2 (guestfs_h *g, const char *filename, int64_t size,
     }
   }
 
-  /* With libvirt >= 6.0 the backing format must be specified. */
-  if (backingfile != NULL && backingformat == NULL) {
-    backingformat = backingformat_free = guestfs_disk_format (g, backingfile);
-    if (!backingformat)
-      return -1;
-    if (STREQ (backingformat, "unknown")) {
-      error (g, _("could not auto-detect the format of the backing file %s"),
-             backingfile);
-      return -1;
-    }
-  }
-
   /* Assemble the qemu-img command line. */
   guestfs_int_cmd_add_arg (cmd, "qemu-img");
   guestfs_int_cmd_add_arg (cmd, "create");