@@ -209,6 +209,7 @@ version 2.
Available compression type values:
0: zlib <https://www.zlib.net/>
+ 1: zstd <http://github.com/facebook/zstd>
=== Header padding ===
@@ -1861,7 +1861,7 @@ disabled with --disable-FEATURE, default is enabled if available:
lzfse support of lzfse compression library
(for reading lzfse-compressed dmg images)
zstd support for zstd compression library
- (for migration compression)
+ (for migration compression and qcow2 cluster compression)
seccomp seccomp support
coroutine-pool coroutine freelist (better performance)
glusterfs GlusterFS backend
@@ -4293,11 +4293,12 @@
# Compression type used in qcow2 image file
#
# @zlib: zlib compression, see <http://zlib.net/>
+# @zstd: zstd compression, see <http://github.com/facebook/zstd>
#
# Since: 5.0
##
{ 'enum': 'Qcow2CompressionType',
- 'data': [ 'zlib' ] }
+ 'data': [ 'zlib', { 'name': 'zstd', 'if': 'defined(CONFIG_ZSTD)' } ] }
##
# @BlockdevCreateOptionsQcow2:
@@ -28,6 +28,11 @@
#define ZLIB_CONST
#include <zlib.h>
+#ifdef CONFIG_ZSTD
+#include <zstd.h>
+#include <zstd_errors.h>
+#endif
+
#include "qcow2.h"
#include "block/thread-pool.h"
#include "crypto.h"
@@ -166,6 +171,115 @@ static ssize_t qcow2_zlib_decompress(void *dest, size_t dest_size,
return ret;
}
+#ifdef CONFIG_ZSTD
+
+/*
+ * qcow2_zstd_compress()
+ *
+ * Compress @src_size bytes of data using zstd compression method
+ *
+ * @dest - destination buffer, @dest_size bytes
+ * @src - source buffer, @src_size bytes
+ *
+ * Returns: compressed size on success
+ * -ENOMEM destination buffer is not enough to store compressed data
+ * -EIO on any other error
+ */
+static ssize_t qcow2_zstd_compress(void *dest, size_t dest_size,
+ const void *src, size_t src_size)
+{
+ size_t ret;
+ ZSTD_outBuffer output = { dest, dest_size, 0 };
+ ZSTD_inBuffer input = { src, src_size, 0 };
+ ZSTD_CCtx *cctx;
+
+ /* make sure we can safely return compressed buffer size with ssize_t */
+ assert(dest_size <= SSIZE_MAX);
+
+ cctx = ZSTD_createCCtx();
+ if (!cctx) {
+ return -EIO;
+ }
+ /*
+ * ZSTD spec: "You must continue calling ZSTD_compressStream2()
+ * with ZSTD_e_end until it returns 0, at which point you are
+ * free to start a new frame".
+ * In the loop, we try to compress all the data into one zstd frame.
+ * ZSTD_compressStream2 potentially can finish a frame earlier
+ * than the full input data is consumed. That's why we are looping
+ * until all the input data is consumed.
+ */
+ do {
+ /*
+ * We want to use zstd streamed interface on decompression,
+ * as we won't know the exact size of the compressed data.
+ */
+ ret = ZSTD_compressStream2(cctx, &output, &input, ZSTD_e_end);
+ if (ZSTD_isError(ret)) {
+ ret = -EIO;
+ goto out;
+ }
+ /* Dest buffer isn't big enough to store compressed content */
+ if (output.pos + ret > output.size) {
+ ret = -ENOMEM;
+ goto out;
+ }
+ } while (ret || input.pos < input.size);
+
+ ret = output.pos;
+
+out:
+ ZSTD_freeCCtx(cctx);
+ return ret;
+}
+
+/*
+ * qcow2_zstd_decompress()
+ *
+ * Decompress some data (not more than @src_size bytes) to produce exactly
+ * @dest_size bytes using zstd compression method
+ *
+ * @dest - destination buffer, @dest_size bytes
+ * @src - source buffer, @src_size bytes
+ *
+ * Returns: 0 on success
+ * -EIO on any error
+ */
+static ssize_t qcow2_zstd_decompress(void *dest, size_t dest_size,
+ const void *src, size_t src_size)
+{
+ size_t ret = 0;
+ ZSTD_outBuffer output = { dest, dest_size, 0 };
+ ZSTD_inBuffer input = { src, src_size, 0 };
+ ZSTD_DCtx *dctx = ZSTD_createDCtx();
+
+ if (!dctx) {
+ return -EIO;
+ }
+
+ /*
+ * The compressed stream from input buffer may consist from more
+ * than one zstd frames. So we iterate until we get a fully
+ * uncompressed cluster.
+ */
+ while (output.pos < output.size) {
+ ret = ZSTD_decompressStream(dctx, &output, &input);
+ /*
+ * if we don't fully populate the output but have read
+ * all the frames from the input, we end up with error
+ * here
+ */
+ if (ZSTD_isError(ret)) {
+ ret = -EIO;
+ break;
+ }
+ }
+
+ ZSTD_freeDCtx(dctx);
+ return 0;
+}
+#endif
+
static int qcow2_compress_pool_func(void *opaque)
{
Qcow2CompressData *data = opaque;
@@ -217,6 +331,11 @@ qcow2_co_compress(BlockDriverState *bs, void *dest, size_t dest_size,
fn = qcow2_zlib_compress;
break;
+#ifdef CONFIG_ZSTD
+ case QCOW2_COMPRESSION_TYPE_ZSTD:
+ fn = qcow2_zstd_compress;
+ break;
+#endif
default:
abort();
}
@@ -249,6 +368,11 @@ qcow2_co_decompress(BlockDriverState *bs, void *dest, size_t dest_size,
fn = qcow2_zlib_decompress;
break;
+#ifdef CONFIG_ZSTD
+ case QCOW2_COMPRESSION_TYPE_ZSTD:
+ fn = qcow2_zstd_decompress;
+ break;
+#endif
default:
abort();
}
@@ -1246,6 +1246,9 @@ static int validate_compression_type(BDRVQcow2State *s, Error **errp)
{
switch (s->compression_type) {
case QCOW2_COMPRESSION_TYPE_ZLIB:
+#ifdef CONFIG_ZSTD
+ case QCOW2_COMPRESSION_TYPE_ZSTD:
+#endif
break;
default:
@@ -3478,6 +3481,10 @@ qcow2_co_create(BlockdevCreateOptions *create_options, Error **errp)
}
switch (qcow2_opts->compression_type) {
+#ifdef CONFIG_ZSTD
+ case QCOW2_COMPRESSION_TYPE_ZSTD:
+ break;
+#endif
default:
error_setg(errp, "Unknown compression type");
goto out;
zstd significantly reduces cluster compression time. It provides better compression performance maintaining the same level of the compression ratio in comparison with zlib, which, at the moment, is the only compression method available. The performance test results: Test compresses and decompresses qemu qcow2 image with just installed rhel-7.6 guest. Image cluster size: 64K. Image on disk size: 2.2G The test was conducted with brd disk to reduce the influence of disk subsystem to the test results. The results is given in seconds. compress cmd: time ./qemu-img convert -O qcow2 -c -o compression_type=[zlib|zstd] src.img [zlib|zstd]_compressed.img decompress cmd time ./qemu-img convert -O qcow2 [zlib|zstd]_compressed.img uncompressed.img compression decompression zlib zstd zlib zstd ------------------------------------------------------------ real 65.5 16.3 (-75 %) 1.9 1.6 (-16 %) user 65.0 15.8 5.3 2.5 sys 3.3 0.2 2.0 2.0 Both ZLIB and ZSTD gave the same compression ratio: 1.57 compressed image size in both cases: 1.4G Signed-off-by: Denis Plotnikov <dplotnikov@virtuozzo.com> QAPI part: Acked-by: Markus Armbruster <armbru@redhat.com> --- docs/interop/qcow2.txt | 1 + configure | 2 +- qapi/block-core.json | 3 +- block/qcow2-threads.c | 124 +++++++++++++++++++++++++++++++++++++++++ block/qcow2.c | 7 +++ 5 files changed, 135 insertions(+), 2 deletions(-)