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Re: [PATCH v2 2/4] qcow2: rework the cluster compression routine
From: |
Vladimir Sementsov-Ogievskiy |
Subject: |
Re: [PATCH v2 2/4] qcow2: rework the cluster compression routine |
Date: |
Mon, 2 Mar 2020 16:02:36 +0300 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 |
02.03.2020 11:21, Denis Plotnikov wrote:
The patch enables processing the image compression type defined
for the image and chooses an appropriate method for image clusters
(de)compression.
Signed-off-by: Denis Plotnikov <address@hidden>
---
block/qcow2-threads.c | 77 +++++++++++++++++++++++++++++++++++--------
1 file changed, 63 insertions(+), 14 deletions(-)
diff --git a/block/qcow2-threads.c b/block/qcow2-threads.c
index 77bb578cdf..9288a4f852 100644
--- a/block/qcow2-threads.c
+++ b/block/qcow2-threads.c
@@ -74,7 +74,9 @@ typedef struct Qcow2CompressData {
} Qcow2CompressData;
/*
- * qcow2_compress()
+ * 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
@@ -83,8 +85,8 @@ typedef struct Qcow2CompressData {
* -ENOMEM destination buffer is not enough to store compressed data
* -EIO on any other error
*/
-static ssize_t qcow2_compress(void *dest, size_t dest_size,
- const void *src, size_t src_size)
+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;
@@ -119,19 +121,19 @@ static ssize_t qcow2_compress(void *dest, size_t
dest_size,
}
/*
- * qcow2_decompress()
+ * qcow2_zlib_decompress()
*
* Decompress some data (not more than @src_size bytes) to produce exactly
- * @dest_size bytes.
+ * @dest_size bytes using zlib compression method
*
* @dest - destination buffer, @dest_size bytes
* @src - source buffer, @src_size bytes
*
* Returns: 0 on success
- * -1 on fail
+ * -EIO on failure
*/
-static ssize_t qcow2_decompress(void *dest, size_t dest_size,
- const void *src, size_t src_size)
+static ssize_t qcow2_zlib_decompress(void *dest, size_t dest_size,
+ const void *src, size_t src_size)
{
int ret = 0;
z_stream strm;
@@ -144,7 +146,7 @@ static ssize_t qcow2_decompress(void *dest, size_t
dest_size,
ret = inflateInit2(&strm, -12);
if (ret != Z_OK) {
- return -1;
+ return -EIO;
}
ret = inflate(&strm, Z_FINISH);
more context:
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 = -1;
+ ret = -EIO;
}
Good thing that you've changed -1 to -EIO, to be more compatible with
_compress() function.
But seems, that there is an actual (preexisting) bug here, as we return direct
ret of inflate, which is
incompatible with our function defined API. And this mean, that Z_STREAM_END
most probably work,
as it is positive. But Z_BUF_ERROR will be treated as error actually.
Hmm, it was broken in far 341926ab83e2b4d in 2018.. By me of course :(
I think, I'll send a separate patch with stable@ in cc.
inflateEnd(&strm);
@@ -189,20 +191,67 @@ qcow2_co_do_compress(BlockDriverState *bs, void *dest,
size_t dest_size,
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)
{
- return qcow2_co_do_compress(bs, dest, dest_size, src, src_size,
- qcow2_compress);
+ BDRVQcow2State *s = bs->opaque;
+ Qcow2CompressFunc fn;
+
+ switch (s->compression_type) {
+ case QCOW2_COMPRESSION_TYPE_ZLIB:
+ fn = qcow2_zlib_compress;
+ break;
+
+ 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)
{
- return qcow2_co_do_compress(bs, dest, dest_size, src, src_size,
- qcow2_decompress);
+ BDRVQcow2State *s = bs->opaque;
+ Qcow2CompressFunc fn;
+
+ switch (s->compression_type) {
+ case QCOW2_COMPRESSION_TYPE_ZLIB:
+ fn = qcow2_zlib_decompress;
+ break;
+
+ default:
+ return -ENOTSUP;
+ }
+
+ return qcow2_co_do_compress(bs, dest, dest_size, src, src_size, fn);
}
--
Best regards,
Vladimir
- [PATCH v2 0/4] qcow2: Implement zstd cluster compression method, Denis Plotnikov, 2020/03/02
- [PATCH v2 2/4] qcow2: rework the cluster compression routine, Denis Plotnikov, 2020/03/02
- Re: [PATCH v2 2/4] qcow2: rework the cluster compression routine,
Vladimir Sementsov-Ogievskiy <=
- [PATCH v2 4/4] iotests: 287: add qcow2 compression type test, Denis Plotnikov, 2020/03/02
- [PATCH v2 3/4] qcow2: add zstd cluster compression, Denis Plotnikov, 2020/03/02
- [PATCH v2 1/4] qcow2: introduce compression type feature, Denis Plotnikov, 2020/03/02
- Re: [PATCH v2 0/4] qcow2: Implement zstd cluster compression method, Vladimir Sementsov-Ogievskiy, 2020/03/02