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From a27b645ebf68deff6658389f34ee938ba042a2dd Mon Sep 17 00:00:00 2001
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From: Kevin Wolf <kwolf@redhat.com>
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Date: Tue, 7 Jan 2014 12:44:44 +0100
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Subject: [PATCH 8/8] qcow2: Zero-initialise first cluster for new images
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RH-Author: Kevin Wolf <kwolf@redhat.com>
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Message-id: <1389098684-1559-1-git-send-email-kwolf@redhat.com>
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Patchwork-id: 56522
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O-Subject: [RHEL-7.0 qemu-kvm PATCH] qcow2: Zero-initialise first cluster for new images
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Bugzilla: 1032904
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RH-Acked-by: Max Reitz <mreitz@redhat.com>
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RH-Acked-by: Fam Zheng <famz@redhat.com>
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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Bugzilla: 1032904
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Brew: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=6817817
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Strictly speaking, this is only required for has_zero_init() == false,
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but it's easy enough to just do a cluster-aligned write that is padded
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with zeros after the header.
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This fixes that after 'qemu-img create' header extensions are attempted
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to be parsed that are really just random leftover data.
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Cc: qemu-stable@nongnu.org
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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Reviewed-by: Fam Zheng <famz@redhat.com>
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Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
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Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
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(cherry picked from commit f8413b3c23b08a547ce18609acc6fae5fd04ed5c)
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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---
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 block/qcow2.c | 36 ++++++++++++++++++++----------------
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 1 file changed, 20 insertions(+), 16 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow2.c |   36 ++++++++++++++++++++----------------
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 1 files changed, 20 insertions(+), 16 deletions(-)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index bf1f66f..f5f68f8 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -1471,7 +1471,7 @@ static int qcow2_create2(const char *filename, int64_t total_size,
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      * size for any qcow2 image.
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      */
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     BlockDriverState* bs;
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-    QCowHeader header;
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+    QCowHeader *header;
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     uint8_t* refcount_table;
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     Error *local_err = NULL;
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     int ret;
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@@ -1489,30 +1489,34 @@ static int qcow2_create2(const char *filename, int64_t total_size,
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     }
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     /* Write the header */
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-    memset(&header, 0, sizeof(header));
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-    header.magic = cpu_to_be32(QCOW_MAGIC);
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-    header.version = cpu_to_be32(version);
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-    header.cluster_bits = cpu_to_be32(cluster_bits);
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-    header.size = cpu_to_be64(0);
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-    header.l1_table_offset = cpu_to_be64(0);
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-    header.l1_size = cpu_to_be32(0);
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-    header.refcount_table_offset = cpu_to_be64(cluster_size);
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-    header.refcount_table_clusters = cpu_to_be32(1);
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-    header.refcount_order = cpu_to_be32(3 + REFCOUNT_SHIFT);
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-    header.header_length = cpu_to_be32(sizeof(header));
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+    QEMU_BUILD_BUG_ON((1 << MIN_CLUSTER_BITS) < sizeof(*header));
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+    header = g_malloc0(cluster_size);
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+    *header = (QCowHeader) {
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+        .magic                      = cpu_to_be32(QCOW_MAGIC),
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+        .version                    = cpu_to_be32(version),
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+        .cluster_bits               = cpu_to_be32(cluster_bits),
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+        .size                       = cpu_to_be64(0),
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+        .l1_table_offset            = cpu_to_be64(0),
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+        .l1_size                    = cpu_to_be32(0),
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+        .refcount_table_offset      = cpu_to_be64(cluster_size),
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+        .refcount_table_clusters    = cpu_to_be32(1),
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+        .refcount_order             = cpu_to_be32(3 + REFCOUNT_SHIFT),
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+        .header_length              = cpu_to_be32(sizeof(*header)),
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+    };
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     if (flags & BLOCK_FLAG_ENCRYPT) {
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-        header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
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+        header->crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
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     } else {
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-        header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
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+        header->crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
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     }
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     if (flags & BLOCK_FLAG_LAZY_REFCOUNTS) {
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-        header.compatible_features |=
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+        header->compatible_features |=
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             cpu_to_be64(QCOW2_COMPAT_LAZY_REFCOUNTS);
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     }
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-    ret = bdrv_pwrite(bs, 0, &header, sizeof(header));
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+    ret = bdrv_pwrite(bs, 0, header, cluster_size);
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+    g_free(header);
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     if (ret < 0) {
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         error_setg_errno(errp, -ret, "Could not write qcow2 header");
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         goto out;
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-- 
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1.7.1
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