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| author | Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> | 2016-07-14 19:59:25 +0300 |
|---|---|---|
| committer | Max Reitz <mreitz@redhat.com> | 2016-07-26 17:46:37 +0200 |
| commit | ebf7bba090e617fd841177e6ea3de3a129c31a97 (patch) | |
| tree | cbf9ba9ac0a63e2d3cb290390576db173729001c /block | |
| parent | f49ee630d73729ecaeecf4b38a8df11bc613914d (diff) | |
| download | qemu-ebf7bba090e617fd841177e6ea3de3a129c31a97.zip qemu-ebf7bba090e617fd841177e6ea3de3a129c31a97.tar.gz qemu-ebf7bba090e617fd841177e6ea3de3a129c31a97.tar.bz2 | |
qcow2: do not allocate extra memory
There are no needs to allocate more than one cluster, as we set
avail_out for deflate to one cluster.
Zlib docs (http://www.zlib.net/manual.html) says:
"deflate compresses as much data as possible, and stops when the input
buffer becomes empty or the output buffer becomes full."
So, deflate will not write more than avail_out to output buffer. If
there is not enough space in output buffer for compressed data (it may
be larger than input data) deflate just returns Z_OK. (if all data is
compressed and written to output buffer deflate returns Z_STREAM_END).
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-id: 1468515565-81313-1-git-send-email-vsementsov@virtuozzo.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/qcow.c | 2 | ||||
| -rw-r--r-- | block/qcow2.c | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/block/qcow.c b/block/qcow.c index 0c7b75b..6f9b2e2 100644 --- a/block/qcow.c +++ b/block/qcow.c @@ -983,7 +983,7 @@ static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num, return ret; } - out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); + out_buf = g_malloc(s->cluster_size); /* best compression, small window, no zlib header */ memset(&strm, 0, sizeof(strm)); diff --git a/block/qcow2.c b/block/qcow2.c index d620d0a..91ef4df 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2612,7 +2612,7 @@ static int qcow2_write_compressed(BlockDriverState *bs, int64_t sector_num, return ret; } - out_buf = g_malloc(s->cluster_size + (s->cluster_size / 1000) + 128); + out_buf = g_malloc(s->cluster_size); /* best compression, small window, no zlib header */ memset(&strm, 0, sizeof(strm)); |