Re: [Qemu-devel] [PATCH v3 28/39] qcow2: Read refcount before L2 table in expand_zero_clusters_in_l1()

[Max Reitz]

On 2018-01-26 15:59, Alberto Garcia wrote:
> At the moment it doesn't really make a difference whether we call
> qcow2_get_refcount() before of after reading the L2 table, but if we
> want to support L2 slices we'll need to read the refcount first.
> 
> This patch simply changes the order of those two operations to prepare
> for that. The patch with the actual semantic changes will be easier to
> read because of this.
> 
> Signed-off-by: Alberto Garcia 
> ---
>  block/qcow2-cluster.c | 12 ++--
>  1 file changed, 6 insertions(+), 6 deletions(-)

Reviewed-by: Max Reitz 



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Re: [Qemu-devel] [PATCH v3 28/39] qcow2: Read refcount before L2 table in expand_zero_clusters_in_l1()

[Eric Blake]

On 01/26/2018 08:59 AM, Alberto Garcia wrote:
> At the moment it doesn't really make a difference whether we call
> qcow2_get_refcount() before of after reading the L2 table, but if we
> want to support L2 slices we'll need to read the refcount first.
> 
> This patch simply changes the order of those two operations to prepare
> for that. The patch with the actual semantic changes will be easier to
> read because of this.
> 
> Signed-off-by: Alberto Garcia 
> ---
>  block/qcow2-cluster.c | 12 ++--
>  1 file changed, 6 insertions(+), 6 deletions(-)

Reviewed-by: Eric Blake 

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.   +1-919-301-3266
Virtualization:  qemu.org | libvirt.org



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[Qemu-devel] [PATCH v3 28/39] qcow2: Read refcount before L2 table in expand_zero_clusters_in_l1()

[Alberto Garcia]

At the moment it doesn't really make a difference whether we call
qcow2_get_refcount() before of after reading the L2 table, but if we
want to support L2 slices we'll need to read the refcount first.

This patch simply changes the order of those two operations to prepare
for that. The patch with the actual semantic changes will be easier to
read because of this.

Signed-off-by: Alberto Garcia 
---
 block/qcow2-cluster.c | 12 ++--
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index e13f8f2f14..1338485184 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1899,6 +1899,12 @@ static int expand_zero_clusters_in_l1(BlockDriverState 
*bs, uint64_t *l1_table,
 goto fail;
 }
 
+ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
+ _refcount);
+if (ret < 0) {
+goto fail;
+}
+
 if (is_active_l1) {
 /* get active L2 tables from cache */
 ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
@@ -1912,12 +1918,6 @@ static int expand_zero_clusters_in_l1(BlockDriverState 
*bs, uint64_t *l1_table,
 goto fail;
 }
 
-ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
- _refcount);
-if (ret < 0) {
-goto fail;
-}
-
 for (j = 0; j < s->l2_size; j++) {
 uint64_t l2_entry = be64_to_cpu(l2_table[j]);
 int64_t offset = l2_entry & L2E_OFFSET_MASK;
-- 
2.11.0