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From 712a6ef0d0d3bbc91953305ad8e7e96f82f19cf0 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 22:32:27 +0100
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Subject: [PATCH 34/87] qcow2: Use pread for inactive L1 in overlap check
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1383604354-12743-37-git-send-email-mreitz@redhat.com>
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Patchwork-id: 55336
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O-Subject: [RHEL-7.0 qemu-kvm PATCH 36/43] qcow2: Use pread for inactive L1 in overlap check
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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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Currently, qcow2_check_metadata_overlap uses bdrv_read to read inactive
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L1 tables from disk. The number of sectors to read is calculated through
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a truncating integer division, therefore, if the L1 table size is not a
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multiple of the sector size, the final entries will not be read and
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their entries in memory remain undefined (from the g_malloc).
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Using bdrv_pread fixes this.
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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 998b959c1e59044f5d5f64c482f4ce8facc8e0bc)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/qcow2-refcount.c | 7 +++----
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 1 file changed, 3 insertions(+), 4 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow2-refcount.c |    7 +++----
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 1 files changed, 3 insertions(+), 4 deletions(-)
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diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
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index 34fcf2f..5c5683d 100644
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--- a/block/qcow2-refcount.c
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+++ b/block/qcow2-refcount.c
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@@ -1701,12 +1701,11 @@ int qcow2_check_metadata_overlap(BlockDriverState *bs, int chk, int64_t offset,
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         for (i = 0; i < s->nb_snapshots; i++) {
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             uint64_t l1_ofs = s->snapshots[i].l1_table_offset;
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             uint32_t l1_sz  = s->snapshots[i].l1_size;
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-            uint64_t *l1 = g_malloc(l1_sz * sizeof(uint64_t));
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+            uint64_t l1_sz2 = l1_sz * sizeof(uint64_t);
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+            uint64_t *l1 = g_malloc(l1_sz2);
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             int ret;
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-            ret = bdrv_read(bs->file, l1_ofs / BDRV_SECTOR_SIZE, (uint8_t *)l1,
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-                            l1_sz * sizeof(uint64_t) / BDRV_SECTOR_SIZE);
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-
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+            ret = bdrv_pread(bs->file, l1_ofs, l1, l1_sz2);
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             if (ret < 0) {
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                 g_free(l1);
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                 return ret;
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-- 
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1.7.1
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