Blame SOURCES/kvm-qcow2-Correct-bitmap-size-in-zero-expansion.patch

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From 6529ac40614e6b28a9c52de40defb6e2f455698b Mon Sep 17 00:00:00 2001
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From: Max Reitz <mreitz@redhat.com>
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Date: Tue, 7 Jan 2014 21:57:14 +0100
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Subject: [PATCH 09/14] qcow2: Correct bitmap size in zero expansion
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RH-Author: Max Reitz <mreitz@redhat.com>
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Message-id: <1389131839-12920-10-git-send-email-mreitz@redhat.com>
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Patchwork-id: 56545
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O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 09/14] qcow2: Correct bitmap size in zero expansion
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Bugzilla: 1033490
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RH-Acked-by: Kevin Wolf <kwolf@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: 1033490
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Since the expanded_clusters bitmap is addressed using host offsets in
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the underlying image file, the correct size to use for allocating the
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bitmap is not determined by the guest disk image but by the underlying
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host image file.
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Furthermore, this size may change during the expansion due to cluster
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allocations on growable image files. In this case, the bitmap needs to
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be resized as well to reflect the growth.
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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 e390cf5a9722d3f3cc54efb505f6ff37fa554b11)
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Signed-off-by: Max Reitz <mreitz@redhat.com>
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---
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 block/qcow2-cluster.c | 38 +++++++++++++++++++++++++++-----------
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 1 file changed, 27 insertions(+), 11 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 block/qcow2-cluster.c |   38 +++++++++++++++++++++++++++-----------
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 1 files changed, 27 insertions(+), 11 deletions(-)
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diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
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index 796d7c5..bfdc83a 100644
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--- a/block/qcow2-cluster.c
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+++ b/block/qcow2-cluster.c
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@@ -1511,8 +1511,8 @@ fail:
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  * i.e., the number of bits in expanded_clusters.
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  */
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 static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
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-                                      int l1_size, uint8_t *expanded_clusters,
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-                                      uint64_t nb_clusters)
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+                                      int l1_size, uint8_t **expanded_clusters,
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+                                      uint64_t *nb_clusters)
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 {
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     BDRVQcowState *s = bs->opaque;
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     bool is_active_l1 = (l1_table == s->l1_table);
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@@ -1555,8 +1555,8 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
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             if (cluster_type == QCOW2_CLUSTER_NORMAL) {
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                 cluster_index = offset >> s->cluster_bits;
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-                assert((cluster_index >= 0) && (cluster_index < nb_clusters));
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-                if (expanded_clusters[cluster_index / 8] &
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+                assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
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+                if ((*expanded_clusters)[cluster_index / 8] &
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                     (1 << (cluster_index % 8))) {
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                     /* Probably a shared L2 table; this cluster was a zero
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                      * cluster which has been expanded, its refcount
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@@ -1613,8 +1613,25 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
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             l2_dirty = true;
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             cluster_index = offset >> s->cluster_bits;
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-            assert((cluster_index >= 0) && (cluster_index < nb_clusters));
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-            expanded_clusters[cluster_index / 8] |= 1 << (cluster_index % 8);
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+
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+            if (cluster_index >= *nb_clusters) {
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+                uint64_t old_bitmap_size = (*nb_clusters + 7) / 8;
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+                uint64_t new_bitmap_size;
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+                /* The offset may lie beyond the old end of the underlying image
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+                 * file for growable files only */
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+                assert(bs->file->growable);
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+                *nb_clusters = size_to_clusters(s, bs->file->total_sectors *
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+                                                BDRV_SECTOR_SIZE);
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+                new_bitmap_size = (*nb_clusters + 7) / 8;
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+                *expanded_clusters = g_realloc(*expanded_clusters,
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+                                               new_bitmap_size);
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+                /* clear the newly allocated space */
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+                memset(&(*expanded_clusters)[old_bitmap_size], 0,
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+                       new_bitmap_size - old_bitmap_size);
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+            }
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+
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+            assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
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+            (*expanded_clusters)[cluster_index / 8] |= 1 << (cluster_index % 8);
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         }
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         if (is_active_l1) {
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@@ -1673,18 +1690,17 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs)
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 {
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     BDRVQcowState *s = bs->opaque;
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     uint64_t *l1_table = NULL;
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-    int cluster_to_sector_bits = s->cluster_bits - BDRV_SECTOR_BITS;
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     uint64_t nb_clusters;
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     uint8_t *expanded_clusters;
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     int ret;
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     int i, j;
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-    nb_clusters = (bs->total_sectors + (1 << cluster_to_sector_bits) - 1)
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-            >> cluster_to_sector_bits;
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+    nb_clusters = size_to_clusters(s, bs->file->total_sectors *
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+                                   BDRV_SECTOR_SIZE);
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     expanded_clusters = g_malloc0((nb_clusters + 7) / 8);
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     ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
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-                                     expanded_clusters, nb_clusters);
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+                                     &expanded_clusters, &nb_clusters);
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     if (ret < 0) {
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         goto fail;
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     }
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@@ -1718,7 +1734,7 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs)
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         }
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         ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size,
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-                                         expanded_clusters, nb_clusters);
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+                                         &expanded_clusters, &nb_clusters);
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         if (ret < 0) {
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             goto fail;
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         }
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-- 
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1.7.1
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