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authorMax Reitz <mreitz@redhat.com>2019-09-18 11:51:43 +0200
committerMax Reitz <mreitz@redhat.com>2019-10-28 12:08:45 +0100
commite8d04f92378c2de7b464e04469a657fd37eb29ea (patch)
tree0a274a9f3c9716def5230a4f09463e9d23fdd432 /block/qcow2.c
parente61a28a9b6b43da6a7a48f6d325fceadf9769388 (diff)
block: Pass truncate exact=true where reasonable
This is a change in behavior, so all instances need a good justification. The comments added here should explain my reasoning. qed already had a comment that suggests it always expected bdrv_truncate()/blk_truncate() to behave as if exact=true were passed (c743849bee7 came eight months before 55b949c8476), so it was simply broken until now. Signed-off-by: Max Reitz <mreitz@redhat.com> Message-id: 20190918095144.955-8-mreitz@redhat.com Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com> [mreitz: Changed comment in qed.c to explain why a new QED file must be empty, as requested and suggested by Maxim] Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block/qcow2.c')
-rw-r--r--block/qcow2.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/block/qcow2.c b/block/qcow2.c
index 9f32dae41f..7c18721741 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -5323,7 +5323,11 @@ static int qcow2_amend_options(BlockDriverState *bs, QemuOpts *opts,
return ret;
}
- ret = blk_truncate(blk, new_size, false, PREALLOC_MODE_OFF, errp);
+ /*
+ * Amending image options should ensure that the image has
+ * exactly the given new values, so pass exact=true here.
+ */
+ ret = blk_truncate(blk, new_size, true, PREALLOC_MODE_OFF, errp);
blk_unref(blk);
if (ret < 0) {
return ret;