[PATCH 7/9] kvm tools, qcow: Use big endian order for L2 table entries

Pekka Enberg
2011-07-09T13:03:04Z

Don't keep the in-memory array in CPU byte order to simplify delayed L2 table
writeout.

Cc: Asias He <asias.hejun@gmail.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Prasad Joshi <prasadjoshi124@gmail.com>
Cc: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
---
tools/kvm/disk/qcow.c | 11 +++--------
1 files changed, 3 insertions(+), 8 deletions(-)

diff --git a/tools/kvm/disk/qcow.c b/tools/kvm/disk/qcow.c
index 35408ab..c851e7f 100644
--- a/tools/kvm/disk/qcow.c
+++ b/tools/kvm/disk/qcow.c
@@ -183,7 +183,6 @@ static struct qcow_l2_table *qcow_read_l2_table(struct qcow *q, u64 offset)
struct qcow_header *header = q->header;
struct qcow_l2_table *l2t;
u64 size;
- u64 i;

size = 1 << header->l2_bits;

@@ -205,10 +204,6 @@ static struct qcow_l2_table *qcow_read_l2_table(struct qcow *q, u64 offset)
if (cache_table(q, l2t) < 0)
goto error;

- /* change cached table to CPU's byte-order */
- for (i = 0; i < size; i++)
- be64_to_cpus(&l2t->table[i]);
-
return l2t;
error:
free(l2t);
@@ -259,7 +254,7 @@ static ssize_t qcow_read_cluster(struct qcow *q, u64 offset, void *dst, u32 dst_
if (l2_idx >= l2_table_size)
goto out_error;

- clust_start = l2_table->table[l2_idx] & ~header->oflag_mask;
+ clust_start = be64_to_cpu(l2_table->table[l2_idx]) & ~header->oflag_mask;
if (!clust_start)
goto zero_cluster;

@@ -437,7 +432,7 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
if (!f_sz)
goto error;

- clust_start = l2t->table[l2t_idx] & ~header->oflag_mask;
+ clust_start = be64_to_cpu(l2t->table[l2t_idx]) & ~header->oflag_mask;
if (!clust_start) {
clust_start = ALIGN(f_sz, clust_sz);
update_meta = true;
@@ -459,7 +454,7 @@ static ssize_t qcow_write_cluster(struct qcow *q, u64 offset, void *buf, u32 src
}

/* Update the cached level2 entry */
- l2t->table[l2t_idx] = clust_start;
+ l2t->table[l2t_idx] = cpu_to_be64(clust_start);
}

mutex_unlock(&q->mutex);
--
1.7.0.4