From 53db4963174d9f65bd8ba04636ba0adba7615996 Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Tue, 7 Jan 2014 21:57:13 +0100
Subject: [PATCH 08/14] qcow2: Implement bdrv_amend_options
RH-Author: Max Reitz <mreitz@redhat.com>
Message-id: <1389131839-12920-9-git-send-email-mreitz@redhat.com>
Patchwork-id: 56544
O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 08/14] qcow2: Implement bdrv_amend_options
Bugzilla: 1033490
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
BZ: 1033490
Implement bdrv_amend_options for compat, size, backing_file, backing_fmt
and lazy_refcounts.
Downgrading images from compat=1.1 to compat=0.10 is achieved through
handling all incompatible flags accordingly, clearing all compatible and
autoclear flags and expanding all zero clusters.
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit 9296b3ed7050cc6e0645fbc3b0aea74406d7eeb2)
Signed-off-by: Max Reitz <mreitz@redhat.com>
---
block/qcow2.c | 194 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 194 insertions(+)
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
block/qcow2.c | 194 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 194 insertions(+), 0 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index 0a53a3c..5b28259 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -1989,6 +1989,199 @@ static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf,
return ret;
}
+/*
+ * Downgrades an image's version. To achieve this, any incompatible features
+ * have to be removed.
+ */
+static int qcow2_downgrade(BlockDriverState *bs, int target_version)
+{
+ BDRVQcowState *s = bs->opaque;
+ int current_version = s->qcow_version;
+ int ret;
+
+ if (target_version == current_version) {
+ return 0;
+ } else if (target_version > current_version) {
+ return -EINVAL;
+ } else if (target_version != 2) {
+ return -EINVAL;
+ }
+
+ if (s->refcount_order != 4) {
+ /* we would have to convert the image to a refcount_order == 4 image
+ * here; however, since qemu (at the time of writing this) does not
+ * support anything different than 4 anyway, there is no point in doing
+ * so right now; however, we should error out (if qemu supports this in
+ * the future and this code has not been adapted) */
+ error_report("qcow2_downgrade: Image refcount orders other than 4 are"
+ "currently not supported.");
+ return -ENOTSUP;
+ }
+
+ /* clear incompatible features */
+ if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
+ ret = qcow2_mark_clean(bs);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ /* with QCOW2_INCOMPAT_CORRUPT, it is pretty much impossible to get here in
+ * the first place; if that happens nonetheless, returning -ENOTSUP is the
+ * best thing to do anyway */
+
+ if (s->incompatible_features) {
+ return -ENOTSUP;
+ }
+
+ /* since we can ignore compatible features, we can set them to 0 as well */
+ s->compatible_features = 0;
+ /* if lazy refcounts have been used, they have already been fixed through
+ * clearing the dirty flag */
+
+ /* clearing autoclear features is trivial */
+ s->autoclear_features = 0;
+
+ ret = qcow2_expand_zero_clusters(bs);
+ if (ret < 0) {
+ return ret;
+ }
+
+ s->qcow_version = target_version;
+ ret = qcow2_update_header(bs);
+ if (ret < 0) {
+ s->qcow_version = current_version;
+ return ret;
+ }
+ return 0;
+}
+
+static int qcow2_amend_options(BlockDriverState *bs,
+ QEMUOptionParameter *options)
+{
+ BDRVQcowState *s = bs->opaque;
+ int old_version = s->qcow_version, new_version = old_version;
+ uint64_t new_size = 0;
+ const char *backing_file = NULL, *backing_format = NULL;
+ bool lazy_refcounts = s->use_lazy_refcounts;
+ int ret;
+ int i;
+
+ for (i = 0; options[i].name; i++)
+ {
+ if (!options[i].assigned) {
+ /* only change explicitly defined options */
+ continue;
+ }
+
+ if (!strcmp(options[i].name, "compat")) {
+ if (!options[i].value.s) {
+ /* preserve default */
+ } else if (!strcmp(options[i].value.s, "0.10")) {
+ new_version = 2;
+ } else if (!strcmp(options[i].value.s, "1.1")) {
+ new_version = 3;
+ } else {
+ fprintf(stderr, "Unknown compatibility level %s.\n",
+ options[i].value.s);
+ return -EINVAL;
+ }
+ } else if (!strcmp(options[i].name, "preallocation")) {
+ fprintf(stderr, "Cannot change preallocation mode.\n");
+ return -ENOTSUP;
+ } else if (!strcmp(options[i].name, "size")) {
+ new_size = options[i].value.n;
+ } else if (!strcmp(options[i].name, "backing_file")) {
+ backing_file = options[i].value.s;
+ } else if (!strcmp(options[i].name, "backing_fmt")) {
+ backing_format = options[i].value.s;
+ } else if (!strcmp(options[i].name, "encryption")) {
+ if ((options[i].value.n != !!s->crypt_method)) {
+ fprintf(stderr, "Changing the encryption flag is not "
+ "supported.\n");
+ return -ENOTSUP;
+ }
+ } else if (!strcmp(options[i].name, "cluster_size")) {
+ if (options[i].value.n != s->cluster_size) {
+ fprintf(stderr, "Changing the cluster size is not "
+ "supported.\n");
+ return -ENOTSUP;
+ }
+ } else if (!strcmp(options[i].name, "lazy_refcounts")) {
+ lazy_refcounts = options[i].value.n;
+ } else {
+ /* if this assertion fails, this probably means a new option was
+ * added without having it covered here */
+ assert(false);
+ }
+ }
+
+ if (new_version != old_version) {
+ if (new_version > old_version) {
+ /* Upgrade */
+ s->qcow_version = new_version;
+ ret = qcow2_update_header(bs);
+ if (ret < 0) {
+ s->qcow_version = old_version;
+ return ret;
+ }
+ } else {
+ ret = qcow2_downgrade(bs, new_version);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+ }
+
+ if (backing_file || backing_format) {
+ ret = qcow2_change_backing_file(bs, backing_file ?: bs->backing_file,
+ backing_format ?: bs->backing_format);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ if (s->use_lazy_refcounts != lazy_refcounts) {
+ if (lazy_refcounts) {
+ if (s->qcow_version < 3) {
+ fprintf(stderr, "Lazy refcounts only supported with compatibility "
+ "level 1.1 and above (use compat=1.1 or greater)\n");
+ return -EINVAL;
+ }
+ s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
+ ret = qcow2_update_header(bs);
+ if (ret < 0) {
+ s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
+ return ret;
+ }
+ s->use_lazy_refcounts = true;
+ } else {
+ /* make image clean first */
+ ret = qcow2_mark_clean(bs);
+ if (ret < 0) {
+ return ret;
+ }
+ /* now disallow lazy refcounts */
+ s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
+ ret = qcow2_update_header(bs);
+ if (ret < 0) {
+ s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
+ return ret;
+ }
+ s->use_lazy_refcounts = false;
+ }
+ }
+
+ if (new_size) {
+ ret = bdrv_truncate(bs, new_size);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
static QEMUOptionParameter qcow2_create_options[] = {
{
.name = BLOCK_OPT_SIZE,
@@ -2073,6 +2266,7 @@ static BlockDriver bdrv_qcow2 = {
.create_options = qcow2_create_options,
.bdrv_check = qcow2_check,
+ .bdrv_amend_options = qcow2_amend_options,
};
static void bdrv_qcow2_init(void)
--
1.7.1