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author | Max Reitz <mreitz@redhat.com> | 2013-09-03 10:09:54 +0200 |
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committer | Kevin Wolf <kwolf@redhat.com> | 2013-09-12 10:12:46 +0200 |
commit | 9296b3ed7050cc6e0645fbc3b0aea74406d7eeb2 (patch) | |
tree | 860710d98819ba0aa74d8ba14eb6963673805a88 /block/qcow2.c | |
parent | b6481f376bc65894910dd98db3f299d698817106 (diff) | |
download | qemu-9296b3ed7050cc6e0645fbc3b0aea74406d7eeb2.zip qemu-9296b3ed7050cc6e0645fbc3b0aea74406d7eeb2.tar.gz qemu-9296b3ed7050cc6e0645fbc3b0aea74406d7eeb2.tar.bz2 |
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>
Diffstat (limited to 'block/qcow2.c')
-rw-r--r-- | block/qcow2.c | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/block/qcow2.c b/block/qcow2.c index 27203f8..7c9354c 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1820,6 +1820,199 @@ 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, @@ -1903,6 +2096,7 @@ 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) |