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[PULL 14/24] qcow2: simple case support for downgrading of qcow2 images
From: |
Hanna Reitz |
Subject: |
[PULL 14/24] qcow2: simple case support for downgrading of qcow2 images with zstd |
Date: |
Tue, 1 Feb 2022 15:42:23 +0100 |
From: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
If image doesn't have any compressed cluster we can easily switch to
zlib compression, which may allow to downgrade the image.
That's mostly needed to support IMGOPTS='compression_type=zstd' in some
iotests which do qcow2 downgrade.
While being here also fix checkpatch complain against '#' in printf
formatting.
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20211223160144.1097696-13-vsementsov@virtuozzo.com>
Signed-off-by: Hanna Reitz <hreitz@redhat.com>
---
block/qcow2.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 56 insertions(+), 2 deletions(-)
diff --git a/block/qcow2.c b/block/qcow2.c
index d509016756..c8115e1cba 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -5279,6 +5279,38 @@ static int qcow2_load_vmstate(BlockDriverState *bs,
QEMUIOVector *qiov,
return bs->drv->bdrv_co_preadv_part(bs, offset, qiov->size, qiov, 0, 0);
}
+static int qcow2_has_compressed_clusters(BlockDriverState *bs)
+{
+ int64_t offset = 0;
+ int64_t bytes = bdrv_getlength(bs);
+
+ if (bytes < 0) {
+ return bytes;
+ }
+
+ while (bytes != 0) {
+ int ret;
+ QCow2SubclusterType type;
+ unsigned int cur_bytes = MIN(INT_MAX, bytes);
+ uint64_t host_offset;
+
+ ret = qcow2_get_host_offset(bs, offset, &cur_bytes, &host_offset,
+ &type);
+ if (ret < 0) {
+ return ret;
+ }
+
+ if (type == QCOW2_SUBCLUSTER_COMPRESSED) {
+ return 1;
+ }
+
+ offset += cur_bytes;
+ bytes -= cur_bytes;
+ }
+
+ return 0;
+}
+
/*
* Downgrades an image's version. To achieve this, any incompatible features
* have to be removed.
@@ -5336,9 +5368,10 @@ static int qcow2_downgrade(BlockDriverState *bs, int
target_version,
* the first place; if that happens nonetheless, returning -ENOTSUP is the
* best thing to do anyway */
- if (s->incompatible_features) {
+ if (s->incompatible_features & ~QCOW2_INCOMPAT_COMPRESSION) {
error_setg(errp, "Cannot downgrade an image with incompatible features
"
- "%#" PRIx64 " set", s->incompatible_features);
+ "0x%" PRIx64 " set",
+ s->incompatible_features & ~QCOW2_INCOMPAT_COMPRESSION);
return -ENOTSUP;
}
@@ -5356,6 +5389,27 @@ static int qcow2_downgrade(BlockDriverState *bs, int
target_version,
return ret;
}
+ if (s->incompatible_features & QCOW2_INCOMPAT_COMPRESSION) {
+ ret = qcow2_has_compressed_clusters(bs);
+ if (ret < 0) {
+ error_setg(errp, "Failed to check block status");
+ return -EINVAL;
+ }
+ if (ret) {
+ error_setg(errp, "Cannot downgrade an image with zstd compression "
+ "type and existing compressed clusters");
+ return -ENOTSUP;
+ }
+ /*
+ * No compressed clusters for now, so just chose default zlib
+ * compression.
+ */
+ s->incompatible_features &= ~QCOW2_INCOMPAT_COMPRESSION;
+ s->compression_type = QCOW2_COMPRESSION_TYPE_ZLIB;
+ }
+
+ assert(s->incompatible_features == 0);
+
s->qcow_version = target_version;
ret = qcow2_update_header(bs);
if (ret < 0) {
--
2.34.1
- [PULL 00/24] Block patches, Hanna Reitz, 2022/02/01
- [PULL 06/24] iotests.py: qemu_img*("create"): support IMGOPTS='compression_type=zstd', Hanna Reitz, 2022/02/01
- [PULL 03/24] iotests.py: img_info_log(): rename imgopts argument, Hanna Reitz, 2022/02/01
- [PULL 18/24] iotests: bash tests: filter compression type, Hanna Reitz, 2022/02/01
- [PULL 15/24] iotests/common.rc: introduce _qcow2_dump_header helper, Hanna Reitz, 2022/02/01
- [PULL 11/24] iotests.py: filter out successful output of qemu-img create, Hanna Reitz, 2022/02/01
- [PULL 10/24] iotest 065: explicit compression type, Hanna Reitz, 2022/02/01
- [PULL 17/24] iotest 39: use _qcow2_dump_header, Hanna Reitz, 2022/02/01
- [PULL 14/24] qcow2: simple case support for downgrading of qcow2 images with zstd,
Hanna Reitz <=
- [PULL 22/24] block-backend: Retain permissions after migration, Hanna Reitz, 2022/02/01
- [PULL 16/24] iotests: massive use _qcow2_dump_header, Hanna Reitz, 2022/02/01
- [PULL 21/24] iotests: declare lack of support for compresion_type in IMGOPTS, Hanna Reitz, 2022/02/01
- [PULL 02/24] iotests/MRCE: Write data to source, Hanna Reitz, 2022/02/01
- [PULL 23/24] iotests/migration-permissions: New test, Hanna Reitz, 2022/02/01
- [PULL 24/24] block.h: remove outdated comment, Hanna Reitz, 2022/02/01
- [PULL 20/24] iotest 214: explicit compression type, Hanna Reitz, 2022/02/01
- [PULL 09/24] iotest 303: explicit compression type, Hanna Reitz, 2022/02/01
- [PULL 19/24] iotests 60: more accurate set dirty bit in qcow2 header, Hanna Reitz, 2022/02/01
- [PULL 04/24] iotests.py: implement unsupported_imgopts, Hanna Reitz, 2022/02/01