qemu-img: Don't allow preallocation and compression at the same time
Only qcow and qcow2 can do compression at all, and they require unallocated
clusters when writing the compressed data.
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
diff --git a/qemu-img.c b/qemu-img.c
index 6a39731..86127f0 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -824,6 +824,8 @@
if (compress) {
QEMUOptionParameter *encryption =
get_option_parameter(param, BLOCK_OPT_ENCRYPT);
+ QEMUOptionParameter *preallocation =
+ get_option_parameter(param, BLOCK_OPT_PREALLOC);
if (!drv->bdrv_write_compressed) {
error_report("Compression not supported for this file format");
@@ -837,6 +839,15 @@
ret = -1;
goto out;
}
+
+ if (preallocation && preallocation->value.s
+ && strcmp(preallocation->value.s, "off"))
+ {
+ error_report("Compression and preallocation not supported at "
+ "the same time");
+ ret = -1;
+ goto out;
+ }
}
/* Create the new image */
