From ebf7bba090e617fd841177e6ea3de3a129c31a97 Mon Sep 17 00:00:00 2001 From: Vladimir Sementsov-Ogievskiy Date: Thu, 14 Jul 2016 19:59:25 +0300 Subject: [PATCH] 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 Message-id: 1468515565-81313-1-git-send-email-vsementsov@virtuozzo.com Reviewed-by: Eric Blake Reviewed-by: John Snow Signed-off-by: Max Reitz --- block/qcow.c | 2 +- block/qcow2.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/block/qcow.c b/block/qcow.c index 0c7b75bc76..6f9b2e2d26 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 d620d0a85b..91ef4dfefc 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));