qemu-img: Empty image after commit
After the top image has been committed, it should be emptied unless
specified otherwise.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 1414159063-25977-10-git-send-email-mreitz@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/qemu-img-cmds.hx b/qemu-img-cmds.hx
index 55aec6b..e2ceadf 100644
--- a/qemu-img-cmds.hx
+++ b/qemu-img-cmds.hx
@@ -22,9 +22,9 @@
ETEXI
DEF("commit", img_commit,
- "commit [-q] [-f fmt] [-t cache] filename")
+ "commit [-q] [-f fmt] [-t cache] [-d] filename")
STEXI
-@item commit [-q] [-f @var{fmt}] [-t @var{cache}] @var{filename}
+@item commit [-q] [-f @var{fmt}] [-t @var{cache}] [-d] @var{filename}
ETEXI
DEF("compare", img_compare,
diff --git a/qemu-img.c b/qemu-img.c
index 494146d..cf8c01c 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -757,14 +757,14 @@
const char *filename, *fmt, *cache;
BlockBackend *blk;
BlockDriverState *bs, *base_bs;
- bool quiet = false;
+ bool quiet = false, drop = false;
Error *local_err = NULL;
CommonBlockJobCBInfo cbi;
fmt = NULL;
cache = BDRV_DEFAULT_CACHE;
for(;;) {
- c = getopt(argc, argv, "f:ht:q");
+ c = getopt(argc, argv, "f:ht:dq");
if (c == -1) {
break;
}
@@ -779,6 +779,9 @@
case 't':
cache = optarg;
break;
+ case 'd':
+ drop = true;
+ break;
case 'q':
quiet = true;
break;
@@ -789,7 +792,7 @@
}
filename = argv[optind++];
- flags = BDRV_O_RDWR;
+ flags = BDRV_O_RDWR | BDRV_O_UNMAP;
ret = bdrv_parse_cache_flags(cache, &flags);
if (ret < 0) {
error_report("Invalid cache option: %s", cache);
@@ -822,7 +825,32 @@
goto done;
}
+ /* The block job will swap base_bs and bs (which is not what we really want
+ * here, but okay) and unref base_bs (after the swap, i.e., the old top
+ * image). In order to still be able to empty that top image afterwards,
+ * increment the reference counter here preemptively. */
+ if (!drop) {
+ bdrv_ref(base_bs);
+ }
+
run_block_job(bs->job, &local_err);
+ if (local_err) {
+ goto unref_backing;
+ }
+
+ if (!drop && base_bs->drv->bdrv_make_empty) {
+ ret = base_bs->drv->bdrv_make_empty(base_bs);
+ if (ret) {
+ error_setg_errno(&local_err, -ret, "Could not empty %s",
+ filename);
+ goto unref_backing;
+ }
+ }
+
+unref_backing:
+ if (!drop) {
+ bdrv_unref(base_bs);
+ }
done:
blk_unref(blk);
diff --git a/qemu-img.texi b/qemu-img.texi
index e3ef4a0..420bd91 100644
--- a/qemu-img.texi
+++ b/qemu-img.texi
@@ -167,7 +167,7 @@
The size can also be specified using the @var{size} option with @code{-o},
it doesn't need to be specified separately in this case.
-@item commit [-f @var{fmt}] [-t @var{cache}] @var{filename}
+@item commit [-f @var{fmt}] [-t @var{cache}] [-d] @var{filename}
Commit the changes recorded in @var{filename} in its base image or backing file.
If the backing file is smaller than the snapshot, then the backing file will be
@@ -176,6 +176,10 @@
backing file to match the size of the smaller snapshot, you can safely truncate
it yourself once the commit operation successfully completes.
+The image @var{filename} is emptied after the operation has succeeded. If you do
+not need @var{filename} afterwards and intend to drop it, you may skip emptying
+@var{filename} by specifying the @code{-d} flag.
+
@item compare [-f @var{fmt}] [-F @var{fmt}] [-T @var{src_cache}] [-p] [-s] [-q] @var{filename1} @var{filename2}
Check if two images have the same content. You can compare images with
