qemu/block/qcow2-threads.c
Denis Plotnikov d298ac10ad qcow2: add zstd cluster compression
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>
Message-Id: <20200507082521.29210-4-dplotnikov@virtuozzo.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2020-05-13 14:20:31 +02:00

528 lines
14 KiB
C

/*
* Threaded data processing for Qcow2: compression, encryption
*
* Copyright (c) 2004-2006 Fabrice Bellard
* Copyright (c) 2018 Virtuozzo International GmbH. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#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"
static int coroutine_fn
qcow2_co_process(BlockDriverState *bs, ThreadPoolFunc *func, void *arg)
{
int ret;
BDRVQcow2State *s = bs->opaque;
ThreadPool *pool = aio_get_thread_pool(bdrv_get_aio_context(bs));
qemu_co_mutex_lock(&s->lock);
while (s->nb_threads >= QCOW2_MAX_THREADS) {
qemu_co_queue_wait(&s->thread_task_queue, &s->lock);
}
s->nb_threads++;
qemu_co_mutex_unlock(&s->lock);
ret = thread_pool_submit_co(pool, func, arg);
qemu_co_mutex_lock(&s->lock);
s->nb_threads--;
qemu_co_queue_next(&s->thread_task_queue);
qemu_co_mutex_unlock(&s->lock);
return ret;
}
/*
* Compression
*/
typedef ssize_t (*Qcow2CompressFunc)(void *dest, size_t dest_size,
const void *src, size_t src_size);
typedef struct Qcow2CompressData {
void *dest;
size_t dest_size;
const void *src;
size_t src_size;
ssize_t ret;
Qcow2CompressFunc func;
} Qcow2CompressData;
/*
* qcow2_zlib_compress()
*
* Compress @src_size bytes of data using zlib 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_zlib_compress(void *dest, size_t dest_size,
const void *src, size_t src_size)
{
ssize_t ret;
z_stream strm;
/* best compression, small window, no zlib header */
memset(&strm, 0, sizeof(strm));
ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION, Z_DEFLATED,
-12, 9, Z_DEFAULT_STRATEGY);
if (ret != Z_OK) {
return -EIO;
}
/*
* strm.next_in is not const in old zlib versions, such as those used on
* OpenBSD/NetBSD, so cast the const away
*/
strm.avail_in = src_size;
strm.next_in = (void *) src;
strm.avail_out = dest_size;
strm.next_out = dest;
ret = deflate(&strm, Z_FINISH);
if (ret == Z_STREAM_END) {
ret = dest_size - strm.avail_out;
} else {
ret = (ret == Z_OK ? -ENOMEM : -EIO);
}
deflateEnd(&strm);
return ret;
}
/*
* qcow2_zlib_decompress()
*
* Decompress some data (not more than @src_size bytes) to produce exactly
* @dest_size bytes using zlib compression method
*
* @dest - destination buffer, @dest_size bytes
* @src - source buffer, @src_size bytes
*
* Returns: 0 on success
* -EIO on fail
*/
static ssize_t qcow2_zlib_decompress(void *dest, size_t dest_size,
const void *src, size_t src_size)
{
int ret;
z_stream strm;
memset(&strm, 0, sizeof(strm));
strm.avail_in = src_size;
strm.next_in = (void *) src;
strm.avail_out = dest_size;
strm.next_out = dest;
ret = inflateInit2(&strm, -12);
if (ret != Z_OK) {
return -EIO;
}
ret = inflate(&strm, Z_FINISH);
if ((ret == Z_STREAM_END || ret == Z_BUF_ERROR) && strm.avail_out == 0) {
/*
* We approve Z_BUF_ERROR because we need @dest buffer to be filled, but
* @src buffer may be processed partly (because in qcow2 we know size of
* compressed data with precision of one sector)
*/
ret = 0;
} else {
ret = -EIO;
}
inflateEnd(&strm);
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)
{
ssize_t ret;
size_t zstd_ret;
ZSTD_outBuffer output = {
.dst = dest,
.size = dest_size,
.pos = 0
};
ZSTD_inBuffer input = {
.src = src,
.size = src_size,
.pos = 0
};
ZSTD_CCtx *cctx = ZSTD_createCCtx();
if (!cctx) {
return -EIO;
}
/*
* Use the zstd streamed interface for symmetry with decompression,
* where streaming is essential since we don't record the exact
* compressed size.
*
* ZSTD_compressStream2() tries to compress everything it could
* with a single call. Although, ZSTD docs says that:
* "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 out tests we saw the only case when it returned with >0 -
* when the output buffer was too small. In that case,
* ZSTD_compressStream2() expects a bigger buffer on the next call.
* We can't provide a bigger buffer because we are limited with dest_size
* which we pass to the ZSTD_compressStream2() at once.
* So, we don't need any loops and just abort the compression when we
* don't get 0 result on the first call.
*/
zstd_ret = ZSTD_compressStream2(cctx, &output, &input, ZSTD_e_end);
if (zstd_ret) {
if (zstd_ret > output.size - output.pos) {
ret = -ENOMEM;
} else {
ret = -EIO;
}
goto out;
}
/* make sure that zstd didn't overflow the dest buffer */
assert(output.pos <= dest_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 zstd_ret = 0;
ssize_t ret = 0;
ZSTD_outBuffer output = {
.dst = dest,
.size = dest_size,
.pos = 0
};
ZSTD_inBuffer input = {
.src = src,
.size = src_size,
.pos = 0
};
ZSTD_DCtx *dctx = ZSTD_createDCtx();
if (!dctx) {
return -EIO;
}
/*
* The compressed stream from the input buffer may consist of more
* than one zstd frame. So we iterate until we get a fully
* uncompressed cluster.
* From zstd docs related to ZSTD_decompressStream:
* "return : 0 when a frame is completely decoded and fully flushed"
* We suppose that this means: each time ZSTD_decompressStream reads
* only ONE full frame and returns 0 if and only if that frame
* is completely decoded and flushed. Only after returning 0,
* ZSTD_decompressStream reads another ONE full frame.
*/
while (output.pos < output.size) {
size_t last_in_pos = input.pos;
size_t last_out_pos = output.pos;
zstd_ret = ZSTD_decompressStream(dctx, &output, &input);
if (ZSTD_isError(zstd_ret)) {
ret = -EIO;
break;
}
/*
* The ZSTD manual is vague about what to do if it reads
* the buffer partially, and we don't want to get stuck
* in an infinite loop where ZSTD_decompressStream
* returns > 0 waiting for another input chunk. So, we add
* a check which ensures that the loop makes some progress
* on each step.
*/
if (last_in_pos >= input.pos &&
last_out_pos >= output.pos) {
ret = -EIO;
break;
}
}
/*
* Make sure that we have the frame fully flushed here
* if not, we somehow managed to get uncompressed cluster
* greater then the cluster size, possibly because of its
* damage.
*/
if (zstd_ret > 0) {
ret = -EIO;
}
ZSTD_freeDCtx(dctx);
assert(ret == 0 || ret == -EIO);
return ret;
}
#endif
static int qcow2_compress_pool_func(void *opaque)
{
Qcow2CompressData *data = opaque;
data->ret = data->func(data->dest, data->dest_size,
data->src, data->src_size);
return 0;
}
static ssize_t coroutine_fn
qcow2_co_do_compress(BlockDriverState *bs, void *dest, size_t dest_size,
const void *src, size_t src_size, Qcow2CompressFunc func)
{
Qcow2CompressData arg = {
.dest = dest,
.dest_size = dest_size,
.src = src,
.src_size = src_size,
.func = func,
};
qcow2_co_process(bs, qcow2_compress_pool_func, &arg);
return arg.ret;
}
/*
* qcow2_co_compress()
*
* Compress @src_size bytes of data using the compression
* method defined by the image compression type
*
* @dest - destination buffer, @dest_size bytes
* @src - source buffer, @src_size bytes
*
* Returns: compressed size on success
* a negative error code on failure
*/
ssize_t coroutine_fn
qcow2_co_compress(BlockDriverState *bs, void *dest, size_t dest_size,
const void *src, size_t src_size)
{
BDRVQcow2State *s = bs->opaque;
Qcow2CompressFunc fn;
switch (s->compression_type) {
case QCOW2_COMPRESSION_TYPE_ZLIB:
fn = qcow2_zlib_compress;
break;
#ifdef CONFIG_ZSTD
case QCOW2_COMPRESSION_TYPE_ZSTD:
fn = qcow2_zstd_compress;
break;
#endif
default:
abort();
}
return qcow2_co_do_compress(bs, dest, dest_size, src, src_size, fn);
}
/*
* qcow2_co_decompress()
*
* Decompress some data (not more than @src_size bytes) to produce exactly
* @dest_size bytes using the compression method defined by the image
* compression type
*
* @dest - destination buffer, @dest_size bytes
* @src - source buffer, @src_size bytes
*
* Returns: 0 on success
* a negative error code on failure
*/
ssize_t coroutine_fn
qcow2_co_decompress(BlockDriverState *bs, void *dest, size_t dest_size,
const void *src, size_t src_size)
{
BDRVQcow2State *s = bs->opaque;
Qcow2CompressFunc fn;
switch (s->compression_type) {
case QCOW2_COMPRESSION_TYPE_ZLIB:
fn = qcow2_zlib_decompress;
break;
#ifdef CONFIG_ZSTD
case QCOW2_COMPRESSION_TYPE_ZSTD:
fn = qcow2_zstd_decompress;
break;
#endif
default:
abort();
}
return qcow2_co_do_compress(bs, dest, dest_size, src, src_size, fn);
}
/*
* Cryptography
*/
/*
* Qcow2EncDecFunc: common prototype of qcrypto_block_encrypt() and
* qcrypto_block_decrypt() functions.
*/
typedef int (*Qcow2EncDecFunc)(QCryptoBlock *block, uint64_t offset,
uint8_t *buf, size_t len, Error **errp);
typedef struct Qcow2EncDecData {
QCryptoBlock *block;
uint64_t offset;
uint8_t *buf;
size_t len;
Qcow2EncDecFunc func;
} Qcow2EncDecData;
static int qcow2_encdec_pool_func(void *opaque)
{
Qcow2EncDecData *data = opaque;
return data->func(data->block, data->offset, data->buf, data->len, NULL);
}
static int coroutine_fn
qcow2_co_encdec(BlockDriverState *bs, uint64_t host_offset,
uint64_t guest_offset, void *buf, size_t len,
Qcow2EncDecFunc func)
{
BDRVQcow2State *s = bs->opaque;
Qcow2EncDecData arg = {
.block = s->crypto,
.offset = s->crypt_physical_offset ? host_offset : guest_offset,
.buf = buf,
.len = len,
.func = func,
};
uint64_t sector_size;
assert(s->crypto);
sector_size = qcrypto_block_get_sector_size(s->crypto);
assert(QEMU_IS_ALIGNED(guest_offset, sector_size));
assert(QEMU_IS_ALIGNED(host_offset, sector_size));
assert(QEMU_IS_ALIGNED(len, sector_size));
return len == 0 ? 0 : qcow2_co_process(bs, qcow2_encdec_pool_func, &arg);
}
/*
* qcow2_co_encrypt()
*
* Encrypts one or more contiguous aligned sectors
*
* @host_offset - underlying storage offset of the first sector of the
* data to be encrypted
*
* @guest_offset - guest (virtual) offset of the first sector of the
* data to be encrypted
*
* @buf - buffer with the data to encrypt, that after encryption
* will be written to the underlying storage device at
* @host_offset
*
* @len - length of the buffer (must be a multiple of the encryption
* sector size)
*
* Depending on the encryption method, @host_offset and/or @guest_offset
* may be used for generating the initialization vector for
* encryption.
*
* Note that while the whole range must be aligned on sectors, it
* does not have to be aligned on clusters and can also cross cluster
* boundaries
*/
int coroutine_fn
qcow2_co_encrypt(BlockDriverState *bs, uint64_t host_offset,
uint64_t guest_offset, void *buf, size_t len)
{
return qcow2_co_encdec(bs, host_offset, guest_offset, buf, len,
qcrypto_block_encrypt);
}
/*
* qcow2_co_decrypt()
*
* Decrypts one or more contiguous aligned sectors
* Similar to qcow2_co_encrypt
*/
int coroutine_fn
qcow2_co_decrypt(BlockDriverState *bs, uint64_t host_offset,
uint64_t guest_offset, void *buf, size_t len)
{
return qcow2_co_encdec(bs, host_offset, guest_offset, buf, len,
qcrypto_block_decrypt);
}