From 6529ac40614e6b28a9c52de40defb6e2f455698b Mon Sep 17 00:00:00 2001
From: Max Reitz <mreitz@redhat.com>
Date: Tue, 7 Jan 2014 21:57:14 +0100
Subject: [PATCH 09/14] qcow2: Correct bitmap size in zero expansion

RH-Author: Max Reitz <mreitz@redhat.com>
Message-id: <1389131839-12920-10-git-send-email-mreitz@redhat.com>
Patchwork-id: 56545
O-Subject: [RHEL-7.0 qemu-kvm PATCH v2 09/14] qcow2: Correct bitmap size in zero expansion
Bugzilla: 1033490
RH-Acked-by: Kevin Wolf <kwolf@redhat.com>
RH-Acked-by: Fam Zheng <famz@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

BZ: 1033490

Since the expanded_clusters bitmap is addressed using host offsets in
the underlying image file, the correct size to use for allocating the
bitmap is not determined by the guest disk image but by the underlying
host image file.

Furthermore, this size may change during the expansion due to cluster
allocations on growable image files. In this case, the bitmap needs to
be resized as well to reflect the growth.

Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
(cherry picked from commit e390cf5a9722d3f3cc54efb505f6ff37fa554b11)

Signed-off-by: Max Reitz <mreitz@redhat.com>
---
 block/qcow2-cluster.c | 38 +++++++++++++++++++++++++++-----------
 1 file changed, 27 insertions(+), 11 deletions(-)

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 block/qcow2-cluster.c |   38 +++++++++++++++++++++++++++-----------
 1 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 796d7c5..bfdc83a 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1511,8 +1511,8 @@ fail:
  * i.e., the number of bits in expanded_clusters.
  */
 static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
-                                      int l1_size, uint8_t *expanded_clusters,
-                                      uint64_t nb_clusters)
+                                      int l1_size, uint8_t **expanded_clusters,
+                                      uint64_t *nb_clusters)
 {
     BDRVQcowState *s = bs->opaque;
     bool is_active_l1 = (l1_table == s->l1_table);
@@ -1555,8 +1555,8 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
 
             if (cluster_type == QCOW2_CLUSTER_NORMAL) {
                 cluster_index = offset >> s->cluster_bits;
-                assert((cluster_index >= 0) && (cluster_index < nb_clusters));
-                if (expanded_clusters[cluster_index / 8] &
+                assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
+                if ((*expanded_clusters)[cluster_index / 8] &
                     (1 << (cluster_index % 8))) {
                     /* Probably a shared L2 table; this cluster was a zero
                      * cluster which has been expanded, its refcount
@@ -1613,8 +1613,25 @@ static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
             l2_dirty = true;
 
             cluster_index = offset >> s->cluster_bits;
-            assert((cluster_index >= 0) && (cluster_index < nb_clusters));
-            expanded_clusters[cluster_index / 8] |= 1 << (cluster_index % 8);
+
+            if (cluster_index >= *nb_clusters) {
+                uint64_t old_bitmap_size = (*nb_clusters + 7) / 8;
+                uint64_t new_bitmap_size;
+                /* The offset may lie beyond the old end of the underlying image
+                 * file for growable files only */
+                assert(bs->file->growable);
+                *nb_clusters = size_to_clusters(s, bs->file->total_sectors *
+                                                BDRV_SECTOR_SIZE);
+                new_bitmap_size = (*nb_clusters + 7) / 8;
+                *expanded_clusters = g_realloc(*expanded_clusters,
+                                               new_bitmap_size);
+                /* clear the newly allocated space */
+                memset(&(*expanded_clusters)[old_bitmap_size], 0,
+                       new_bitmap_size - old_bitmap_size);
+            }
+
+            assert((cluster_index >= 0) && (cluster_index < *nb_clusters));
+            (*expanded_clusters)[cluster_index / 8] |= 1 << (cluster_index % 8);
         }
 
         if (is_active_l1) {
@@ -1673,18 +1690,17 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs)
 {
     BDRVQcowState *s = bs->opaque;
     uint64_t *l1_table = NULL;
-    int cluster_to_sector_bits = s->cluster_bits - BDRV_SECTOR_BITS;
     uint64_t nb_clusters;
     uint8_t *expanded_clusters;
     int ret;
     int i, j;
 
-    nb_clusters = (bs->total_sectors + (1 << cluster_to_sector_bits) - 1)
-            >> cluster_to_sector_bits;
+    nb_clusters = size_to_clusters(s, bs->file->total_sectors *
+                                   BDRV_SECTOR_SIZE);
     expanded_clusters = g_malloc0((nb_clusters + 7) / 8);
 
     ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
-                                     expanded_clusters, nb_clusters);
+                                     &expanded_clusters, &nb_clusters);
     if (ret < 0) {
         goto fail;
     }
@@ -1718,7 +1734,7 @@ int qcow2_expand_zero_clusters(BlockDriverState *bs)
         }
 
         ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size,
-                                         expanded_clusters, nb_clusters);
+                                         &expanded_clusters, &nb_clusters);
         if (ret < 0) {
             goto fail;
         }
-- 
1.7.1