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[Qemu-block] [PATCH v3] qcow2: fix preallocation with metadata on bare b
From: |
Ivan Ren |
Subject: |
[Qemu-block] [PATCH v3] qcow2: fix preallocation with metadata on bare block device |
Date: |
Fri, 11 May 2018 23:36:44 +0800 |
Create a qcow2 directly on bare block device with
"-o preallocation=metadata" option. When read this qcow2, it will
return pre-existing data on block device. This patch add
QCOW_OFLAG_ZERO flag (supported in qcow_version >= 3) for
preallocated l2 entry to avoid this problem.
Signed-off-by: Ivan Ren <address@hidden>
---
Changes in v2:
- always pass QCOW_OFLAG_ZERO when preallocate metadta
Changes in v3:
- limit this feature only on qcow_version >= 3
---
block/qcow2-cluster.c | 5 +++--
block/qcow2.c | 12 +++++++++---
block/qcow2.h | 3 ++-
3 files changed, 14 insertions(+), 6 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 1aee726..b9e0ceb 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -919,7 +919,8 @@ fail:
return ret;
}
-int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
+int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m,
+ uint64_t flags)
{
BDRVQcow2State *s = bs->opaque;
int i, j = 0, l2_index, ret;
@@ -969,7 +970,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs,
QCowL2Meta *m)
}
l2_slice[l2_index + i] = cpu_to_be64((cluster_offset +
- (i << s->cluster_bits)) | QCOW_OFLAG_COPIED);
+ (i << s->cluster_bits)) | QCOW_OFLAG_COPIED | flags);
}
diff --git a/block/qcow2.c b/block/qcow2.c
index 2f36e63..ee862b0 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2044,7 +2044,7 @@ static coroutine_fn int qcow2_co_pwritev(BlockDriverState
*bs, uint64_t offset,
while (l2meta != NULL) {
QCowL2Meta *next;
- ret = qcow2_alloc_cluster_link_l2(bs, l2meta);
+ ret = qcow2_alloc_cluster_link_l2(bs, l2meta, 0);
if (ret < 0) {
goto fail;
}
@@ -2552,7 +2552,13 @@ static void coroutine_fn preallocate_co(void *opaque)
while (meta) {
QCowL2Meta *next = meta->next;
- ret = qcow2_alloc_cluster_link_l2(bs, meta);
+ if (s->qcow_version >= 3) {
+ /* add QCOW_OFLAG_ZERO to avoid pre-existing data be read */
+ ret = qcow2_alloc_cluster_link_l2(bs, meta, QCOW_OFLAG_ZERO);
+ } else {
+ ret = qcow2_alloc_cluster_link_l2(bs, meta, 0);
+ }
+
if (ret < 0) {
qcow2_free_any_clusters(bs, meta->alloc_offset,
meta->nb_clusters,
QCOW2_DISCARD_NEVER);
@@ -3458,7 +3464,7 @@ static int qcow2_truncate(BlockDriverState *bs, int64_t
offset,
};
qemu_co_queue_init(&allocation.dependent_requests);
- ret = qcow2_alloc_cluster_link_l2(bs, &allocation);
+ ret = qcow2_alloc_cluster_link_l2(bs, &allocation, 0);
if (ret < 0) {
error_setg_errno(errp, -ret, "Failed to update L2 tables");
qcow2_free_clusters(bs, host_offset,
diff --git a/block/qcow2.h b/block/qcow2.h
index adf5c39..9a59602 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -617,7 +617,8 @@ uint64_t
qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
uint64_t offset,
int compressed_size);
-int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m);
+int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m,
+ uint64_t flags);
int qcow2_cluster_discard(BlockDriverState *bs, uint64_t offset,
uint64_t bytes, enum qcow2_discard_type type,
bool full_discard);
--
1.8.3.1
- [Qemu-block] [PATCH v3] qcow2: fix preallocation with metadata on bare block device,
Ivan Ren <=