qemu-img: Specify backing file for commit
Introduce a new parameter for qemu-img commit which may be used to
explicitly specify the backing file into which an image should be
committed if the backing chain has more than a single layer.
[Applied Eric Blake's qemu-img.texi documentation rewording
--Stefan]
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1414159063-25977-12-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/qemu-img.c b/qemu-img.c
index 8fec160..bd5a2ae 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -759,7 +759,7 @@
static int img_commit(int argc, char **argv)
{
int c, ret, flags;
- const char *filename, *fmt, *cache;
+ const char *filename, *fmt, *cache, *base;
BlockBackend *blk;
BlockDriverState *bs, *base_bs;
bool progress = false, quiet = false, drop = false;
@@ -768,8 +768,9 @@
fmt = NULL;
cache = BDRV_DEFAULT_CACHE;
+ base = NULL;
for(;;) {
- c = getopt(argc, argv, "f:ht:dpq");
+ c = getopt(argc, argv, "f:ht:b:dpq");
if (c == -1) {
break;
}
@@ -784,6 +785,11 @@
case 't':
cache = optarg;
break;
+ case 'b':
+ base = optarg;
+ /* -b implies -d */
+ drop = true;
+ break;
case 'd':
drop = true;
break;
@@ -822,13 +828,21 @@
qemu_progress_init(progress, 1.f);
qemu_progress_print(0.f, 100);
- /* This is different from QMP, which by default uses the deepest file in the
- * backing chain (i.e., the very base); however, the traditional behavior of
- * qemu-img commit is using the immediate backing file. */
- base_bs = bs->backing_hd;
- if (!base_bs) {
- error_setg(&local_err, "Image does not have a backing file");
- goto done;
+ if (base) {
+ base_bs = bdrv_find_backing_image(bs, base);
+ if (!base_bs) {
+ error_set(&local_err, QERR_BASE_NOT_FOUND, base);
+ goto done;
+ }
+ } else {
+ /* This is different from QMP, which by default uses the deepest file in
+ * the backing chain (i.e., the very base); however, the traditional
+ * behavior of qemu-img commit is using the immediate backing file. */
+ base_bs = bs->backing_hd;
+ if (!base_bs) {
+ error_setg(&local_err, "Image does not have a backing file");
+ goto done;
+ }
}
cbi = (CommonBlockJobCBInfo){
