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From 0e79ef6691f77a7c0da31dff9276b6dad42441a0 Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Mon, 4 Nov 2013 22:31:59 +0100
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Subject: [PATCH 06/87] qcow2: Add corrupt bit
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1383604354-12743-9-git-send-email-mreitz@redhat.com>
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Patchwork-id: 55308
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 08/43] qcow2: Add corrupt bit
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Bugzilla: 1004347
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RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@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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BZ: 1004347
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This adds an incompatible bit indicating corruption to qcow2. Any image
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with this bit set may not be written to unless for repairing (and
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subsequently clearing the bit if the repair has been successful).
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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Signed-off-by: Kevin Wolf <kwolf@redhat.com>
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(cherry picked from commit 69c98726537627e708abb8fcb33e3a2b10e40bf1)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/qcow2.c              | 47 ++++++++++++++++++++++++++++++++++++++++++++++
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 block/qcow2.h              |  7 ++++++-
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 docs/specs/qcow2.txt       |  7 ++++++-
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 tests/qemu-iotests/031.out | 12 ++++++------
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 tests/qemu-iotests/036.out |  2 +-
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 5 files changed, 66 insertions(+), 9 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow2.c              |   47 ++++++++++++++++++++++++++++++++++++++++++++
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 block/qcow2.h              |    7 +++++-
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 docs/specs/qcow2.txt       |    7 +++++-
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 tests/qemu-iotests/031.out |   12 +++++-----
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 tests/qemu-iotests/036.out |    2 +-
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 5 files changed, 66 insertions(+), 9 deletions(-)
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diff --git a/block/qcow2.c b/block/qcow2.c
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index c2728c9..aa9dd23 100644
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--- a/block/qcow2.c
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+++ b/block/qcow2.c
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@@ -272,6 +272,37 @@ static int qcow2_mark_clean(BlockDriverState *bs)
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     return 0;
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 }
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+/*
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+ * Marks the image as corrupt.
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+ */
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+int qcow2_mark_corrupt(BlockDriverState *bs)
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+{
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+    BDRVQcowState *s = bs->opaque;
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+
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+    s->incompatible_features |= QCOW2_INCOMPAT_CORRUPT;
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+    return qcow2_update_header(bs);
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+}
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+
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+/*
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+ * Marks the image as consistent, i.e., unsets the corrupt bit, and flushes
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+ * before if necessary.
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+ */
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+int qcow2_mark_consistent(BlockDriverState *bs)
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+{
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+    BDRVQcowState *s = bs->opaque;
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+
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+    if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
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+        int ret = bdrv_flush(bs);
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+        if (ret < 0) {
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+            return ret;
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+        }
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+
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+        s->incompatible_features &= ~QCOW2_INCOMPAT_CORRUPT;
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+        return qcow2_update_header(bs);
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+    }
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+    return 0;
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+}
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+
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 static int qcow2_check(BlockDriverState *bs, BdrvCheckResult *result,
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                        BdrvCheckMode fix)
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 {
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@@ -402,6 +433,17 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags)
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         goto fail;
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     }
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+    if (s->incompatible_features & QCOW2_INCOMPAT_CORRUPT) {
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+        /* Corrupt images may not be written to unless they are being repaired
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+         */
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+        if ((flags & BDRV_O_RDWR) && !(flags & BDRV_O_CHECK)) {
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+            error_report("qcow2: Image is corrupt; cannot be opened "
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+                    "read/write.");
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+            ret = -EACCES;
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+            goto fail;
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+        }
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+    }
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+
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     /* Check support for various header values */
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     if (header.refcount_order != 4) {
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         report_unsupported(bs, "%d bit reference counts",
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@@ -1140,6 +1182,11 @@ int qcow2_update_header(BlockDriverState *bs)
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             .name = "dirty bit",
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         },
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         {
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+            .type = QCOW2_FEAT_TYPE_INCOMPATIBLE,
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+            .bit  = QCOW2_INCOMPAT_CORRUPT_BITNR,
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+            .name = "corrupt bit",
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+        },
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+        {
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             .type = QCOW2_FEAT_TYPE_COMPATIBLE,
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             .bit  = QCOW2_COMPAT_LAZY_REFCOUNTS_BITNR,
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             .name = "lazy refcounts",
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diff --git a/block/qcow2.h b/block/qcow2.h
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index dba9771..4297487 100644
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--- a/block/qcow2.h
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+++ b/block/qcow2.h
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@@ -119,9 +119,12 @@ enum {
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 /* Incompatible feature bits */
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 enum {
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     QCOW2_INCOMPAT_DIRTY_BITNR   = 0,
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+    QCOW2_INCOMPAT_CORRUPT_BITNR = 1,
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     QCOW2_INCOMPAT_DIRTY         = 1 << QCOW2_INCOMPAT_DIRTY_BITNR,
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+    QCOW2_INCOMPAT_CORRUPT       = 1 << QCOW2_INCOMPAT_CORRUPT_BITNR,
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-    QCOW2_INCOMPAT_MASK          = QCOW2_INCOMPAT_DIRTY,
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+    QCOW2_INCOMPAT_MASK          = QCOW2_INCOMPAT_DIRTY
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+                                 | QCOW2_INCOMPAT_CORRUPT,
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 };
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 /* Compatible feature bits */
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@@ -361,6 +364,8 @@ int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
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                   int64_t sector_num, int nb_sectors);
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 int qcow2_mark_dirty(BlockDriverState *bs);
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+int qcow2_mark_corrupt(BlockDriverState *bs);
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+int qcow2_mark_consistent(BlockDriverState *bs);
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 int qcow2_update_header(BlockDriverState *bs);
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 /* qcow2-refcount.c functions */
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diff --git a/docs/specs/qcow2.txt b/docs/specs/qcow2.txt
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index 36a559d..33eca36 100644
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--- a/docs/specs/qcow2.txt
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+++ b/docs/specs/qcow2.txt
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@@ -80,7 +80,12 @@ in the description of a field.
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                                 tables to repair refcounts before accessing the
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                                 image.
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-                    Bits 1-63:  Reserved (set to 0)
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+                    Bit 1:      Corrupt bit.  If this bit is set then any data
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+                                structure may be corrupt and the image must not
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+                                be written to (unless for regaining
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+                                consistency).
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+
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+                    Bits 2-63:  Reserved (set to 0)
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          80 -  87:  compatible_features
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                     Bitmask of compatible features. An implementation can
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diff --git a/tests/qemu-iotests/031.out b/tests/qemu-iotests/031.out
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index 796c993..a943344 100644
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--- a/tests/qemu-iotests/031.out
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+++ b/tests/qemu-iotests/031.out
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@@ -54,7 +54,7 @@ header_length             72
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 Header extension:
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 magic                     0x6803f857
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-length                    96
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+length                    144
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 data                      <binary>
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 Header extension:
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@@ -68,7 +68,7 @@ No errors were found on the image.
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 magic                     0x514649fb
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 version                   2
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-backing_file_offset       0xf8
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+backing_file_offset       0x128
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 backing_file_size         0x17
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 cluster_bits              16
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 size                      67108864
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@@ -92,7 +92,7 @@ data                      'host_device'
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 Header extension:
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 magic                     0x6803f857
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-length                    96
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+length                    144
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 data                      <binary>
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 Header extension:
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@@ -155,7 +155,7 @@ header_length             104
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 Header extension:
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 magic                     0x6803f857
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-length                    96
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+length                    144
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 data                      <binary>
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 Header extension:
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@@ -169,7 +169,7 @@ No errors were found on the image.
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 magic                     0x514649fb
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 version                   3
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-backing_file_offset       0x118
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+backing_file_offset       0x148
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 backing_file_size         0x17
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 cluster_bits              16
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 size                      67108864
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@@ -193,7 +193,7 @@ data                      'host_device'
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 Header extension:
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 magic                     0x6803f857
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-length                    96
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+length                    144
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 data                      <binary>
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 Header extension:
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diff --git a/tests/qemu-iotests/036.out b/tests/qemu-iotests/036.out
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index 063ca22..55a3e6e 100644
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--- a/tests/qemu-iotests/036.out
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+++ b/tests/qemu-iotests/036.out
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@@ -46,7 +46,7 @@ header_length             104
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 Header extension:
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 magic                     0x6803f857
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-length                    96
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+length                    144
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 data                      <binary>
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 *** done
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-- 
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1.7.1
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