qcow2: Implement bdrv_amend_options
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>
This commit is contained in:
Max Reitz
Kevin Wolf
parent
b6481f376b
commit
9296b3ed70
194
block/qcow2.c
194
block/qcow2.c
@ -1820,6 +1820,199 @@ static int qcow2_load_vmstate(BlockDriverState *bs, uint8_t *buf,
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return ret;
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}
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/*
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* Downgrades an image's version. To achieve this, any incompatible features
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* have to be removed.
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*/
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static int qcow2_downgrade(BlockDriverState *bs, int target_version)
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{
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BDRVQcowState *s = bs->opaque;
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int current_version = s->qcow_version;
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int ret;
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if (target_version == current_version) {
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return 0;
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} else if (target_version > current_version) {
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return -EINVAL;
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} else if (target_version != 2) {
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return -EINVAL;
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}
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if (s->refcount_order != 4) {
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/* we would have to convert the image to a refcount_order == 4 image
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* here; however, since qemu (at the time of writing this) does not
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* support anything different than 4 anyway, there is no point in doing
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* so right now; however, we should error out (if qemu supports this in
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* the future and this code has not been adapted) */
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error_report("qcow2_downgrade: Image refcount orders other than 4 are"
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"currently not supported.");
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return -ENOTSUP;
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}
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/* clear incompatible features */
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if (s->incompatible_features & QCOW2_INCOMPAT_DIRTY) {
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ret = qcow2_mark_clean(bs);
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if (ret < 0) {
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return ret;
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}
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}
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/* with QCOW2_INCOMPAT_CORRUPT, it is pretty much impossible to get here in
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* the first place; if that happens nonetheless, returning -ENOTSUP is the
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* best thing to do anyway */
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if (s->incompatible_features) {
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return -ENOTSUP;
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}
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/* since we can ignore compatible features, we can set them to 0 as well */
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s->compatible_features = 0;
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/* if lazy refcounts have been used, they have already been fixed through
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* clearing the dirty flag */
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/* clearing autoclear features is trivial */
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s->autoclear_features = 0;
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ret = qcow2_expand_zero_clusters(bs);
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if (ret < 0) {
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return ret;
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}
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s->qcow_version = target_version;
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ret = qcow2_update_header(bs);
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if (ret < 0) {
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s->qcow_version = current_version;
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return ret;
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}
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return 0;
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}
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static int qcow2_amend_options(BlockDriverState *bs,
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QEMUOptionParameter *options)
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{
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BDRVQcowState *s = bs->opaque;
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int old_version = s->qcow_version, new_version = old_version;
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uint64_t new_size = 0;
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const char *backing_file = NULL, *backing_format = NULL;
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bool lazy_refcounts = s->use_lazy_refcounts;
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int ret;
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int i;
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for (i = 0; options[i].name; i++)
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{
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if (!options[i].assigned) {
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/* only change explicitly defined options */
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continue;
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}
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if (!strcmp(options[i].name, "compat")) {
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if (!options[i].value.s) {
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/* preserve default */
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} else if (!strcmp(options[i].value.s, "0.10")) {
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new_version = 2;
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} else if (!strcmp(options[i].value.s, "1.1")) {
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new_version = 3;
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} else {
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fprintf(stderr, "Unknown compatibility level %s.\n",
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options[i].value.s);
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return -EINVAL;
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}
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} else if (!strcmp(options[i].name, "preallocation")) {
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fprintf(stderr, "Cannot change preallocation mode.\n");
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return -ENOTSUP;
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} else if (!strcmp(options[i].name, "size")) {
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new_size = options[i].value.n;
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} else if (!strcmp(options[i].name, "backing_file")) {
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backing_file = options[i].value.s;
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} else if (!strcmp(options[i].name, "backing_fmt")) {
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backing_format = options[i].value.s;
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} else if (!strcmp(options[i].name, "encryption")) {
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if ((options[i].value.n != !!s->crypt_method)) {
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fprintf(stderr, "Changing the encryption flag is not "
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"supported.\n");
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return -ENOTSUP;
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}
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} else if (!strcmp(options[i].name, "cluster_size")) {
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if (options[i].value.n != s->cluster_size) {
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fprintf(stderr, "Changing the cluster size is not "
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"supported.\n");
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return -ENOTSUP;
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}
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} else if (!strcmp(options[i].name, "lazy_refcounts")) {
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lazy_refcounts = options[i].value.n;
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} else {
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/* if this assertion fails, this probably means a new option was
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* added without having it covered here */
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assert(false);
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}
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}
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if (new_version != old_version) {
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if (new_version > old_version) {
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/* Upgrade */
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s->qcow_version = new_version;
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ret = qcow2_update_header(bs);
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if (ret < 0) {
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s->qcow_version = old_version;
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return ret;
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}
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} else {
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ret = qcow2_downgrade(bs, new_version);
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if (ret < 0) {
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return ret;
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}
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}
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}
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if (backing_file || backing_format) {
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ret = qcow2_change_backing_file(bs, backing_file ?: bs->backing_file,
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backing_format ?: bs->backing_format);
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if (ret < 0) {
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return ret;
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}
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}
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if (s->use_lazy_refcounts != lazy_refcounts) {
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if (lazy_refcounts) {
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if (s->qcow_version < 3) {
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fprintf(stderr, "Lazy refcounts only supported with compatibility "
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"level 1.1 and above (use compat=1.1 or greater)\n");
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return -EINVAL;
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}
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s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
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ret = qcow2_update_header(bs);
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if (ret < 0) {
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s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
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return ret;
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}
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s->use_lazy_refcounts = true;
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} else {
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/* make image clean first */
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ret = qcow2_mark_clean(bs);
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if (ret < 0) {
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return ret;
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}
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/* now disallow lazy refcounts */
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s->compatible_features &= ~QCOW2_COMPAT_LAZY_REFCOUNTS;
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ret = qcow2_update_header(bs);
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if (ret < 0) {
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s->compatible_features |= QCOW2_COMPAT_LAZY_REFCOUNTS;
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return ret;
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}
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s->use_lazy_refcounts = false;
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}
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}
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if (new_size) {
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ret = bdrv_truncate(bs, new_size);
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if (ret < 0) {
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return ret;
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}
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}
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return 0;
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}
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static QEMUOptionParameter qcow2_create_options[] = {
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{
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.name = BLOCK_OPT_SIZE,
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@ -1903,6 +2096,7 @@ static BlockDriver bdrv_qcow2 = {
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.create_options = qcow2_create_options,
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.bdrv_check = qcow2_check,
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.bdrv_amend_options = qcow2_amend_options,
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};
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static void bdrv_qcow2_init(void)
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