[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[PATCH v6 22/32] qcow2: Add subcluster support to zero_in_l2_slice()
From: |
Alberto Garcia |
Subject: |
[PATCH v6 22/32] qcow2: Add subcluster support to zero_in_l2_slice() |
Date: |
Sun, 24 May 2020 16:51:42 +0200 |
The QCOW_OFLAG_ZERO bit that indicates that a cluster reads as
zeroes is only used in standard L2 entries. Extended L2 entries use
individual 'all zeroes' bits for each subcluster.
This must be taken into account when updating the L2 entry and also
when deciding that an existing entry does not need to be updated.
Signed-off-by: Alberto Garcia <address@hidden>
---
block/qcow2-cluster.c | 36 +++++++++++++++++++-----------------
1 file changed, 19 insertions(+), 17 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 2f3bd3a882..4e59bbd545 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1956,7 +1956,6 @@ static int zero_in_l2_slice(BlockDriverState *bs,
uint64_t offset,
int l2_index;
int ret;
int i;
- bool unmap = !!(flags & BDRV_REQ_MAY_UNMAP);
ret = get_cluster_table(bs, offset, &l2_slice, &l2_index);
if (ret < 0) {
@@ -1968,28 +1967,31 @@ static int zero_in_l2_slice(BlockDriverState *bs,
uint64_t offset,
assert(nb_clusters <= INT_MAX);
for (i = 0; i < nb_clusters; i++) {
- uint64_t old_offset;
- QCow2ClusterType cluster_type;
+ uint64_t old_l2_entry = get_l2_entry(s, l2_slice, l2_index + i);
+ uint64_t old_l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ QCow2ClusterType type = qcow2_get_cluster_type(bs, old_l2_entry);
+ bool unmap = (type == QCOW2_CLUSTER_COMPRESSED) ||
+ ((flags & BDRV_REQ_MAY_UNMAP) && qcow2_cluster_is_allocated(type));
+ uint64_t new_l2_entry = unmap ? 0 : old_l2_entry;
+ uint64_t new_l2_bitmap = old_l2_bitmap;
- old_offset = get_l2_entry(s, l2_slice, l2_index + i);
+ if (has_subclusters(s)) {
+ new_l2_bitmap = QCOW_L2_BITMAP_ALL_ZEROES;
+ } else {
+ new_l2_entry |= QCOW_OFLAG_ZERO;
+ }
- /*
- * Minimize L2 changes if the cluster already reads back as
- * zeroes with correct allocation.
- */
- cluster_type = qcow2_get_cluster_type(bs, old_offset);
- if (cluster_type == QCOW2_CLUSTER_ZERO_PLAIN ||
- (cluster_type == QCOW2_CLUSTER_ZERO_ALLOC && !unmap)) {
+ if (old_l2_entry == new_l2_entry && old_l2_bitmap == new_l2_bitmap) {
continue;
}
qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice);
- if (cluster_type == QCOW2_CLUSTER_COMPRESSED || unmap) {
- set_l2_entry(s, l2_slice, l2_index + i, QCOW_OFLAG_ZERO);
- qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
- } else {
- uint64_t entry = get_l2_entry(s, l2_slice, l2_index + i);
- set_l2_entry(s, l2_slice, l2_index + i, entry | QCOW_OFLAG_ZERO);
+ if (unmap) {
+ qcow2_free_any_clusters(bs, old_l2_entry, 1,
QCOW2_DISCARD_REQUEST);
+ }
+ set_l2_entry(s, l2_slice, l2_index + i, new_l2_entry);
+ if (has_subclusters(s)) {
+ set_l2_bitmap(s, l2_slice, l2_index + i, new_l2_bitmap);
}
}
--
2.20.1
- [PATCH v6 14/32] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type(), (continued)
- [PATCH v6 14/32] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type(), Alberto Garcia, 2020/05/24
- [PATCH v6 10/32] qcow2: Add offset_to_sc_index(), Alberto Garcia, 2020/05/24
- [PATCH v6 05/32] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied(), Alberto Garcia, 2020/05/24
- [PATCH v6 01/32] qcow2: Make Qcow2AioTask store the full host offset, Alberto Garcia, 2020/05/24
- [PATCH v6 06/32] qcow2: Add get_l2_entry() and set_l2_entry(), Alberto Garcia, 2020/05/24
- [PATCH v6 23/32] qcow2: Add subcluster support to discard_in_l2_slice(), Alberto Garcia, 2020/05/24
- [PATCH v6 12/32] qcow2: Add l2_entry_size(), Alberto Garcia, 2020/05/24
- [PATCH v6 16/32] qcow2: Add qcow2_cluster_is_allocated(), Alberto Garcia, 2020/05/24
- [PATCH v6 09/32] qcow2: Add subcluster-related fields to BDRVQcow2State, Alberto Garcia, 2020/05/24
- [PATCH v6 02/32] qcow2: Convert qcow2_get_cluster_offset() into qcow2_get_host_offset(), Alberto Garcia, 2020/05/24
- [PATCH v6 22/32] qcow2: Add subcluster support to zero_in_l2_slice(),
Alberto Garcia <=
- [PATCH v6 17/32] qcow2: Add cluster type parameter to qcow2_get_host_offset(), Alberto Garcia, 2020/05/24
- [PATCH v6 24/32] qcow2: Add subcluster support to check_refcounts_l2(), Alberto Garcia, 2020/05/24
- [PATCH v6 26/32] qcow2: Clear the L2 bitmap when allocating a compressed cluster, Alberto Garcia, 2020/05/24
- [PATCH v6 28/32] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes(), Alberto Garcia, 2020/05/24
- [PATCH v6 27/32] qcow2: Add subcluster support to handle_alloc_space(), Alberto Garcia, 2020/05/24
- [PATCH v6 19/32] qcow2: Handle QCOW2_SUBCLUSTER_UNALLOCATED_ALLOC, Alberto Garcia, 2020/05/24
- [PATCH v6 25/32] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2(), Alberto Garcia, 2020/05/24
- [PATCH v6 11/32] qcow2: Add offset_into_subcluster() and size_to_subclusters(), Alberto Garcia, 2020/05/24
- [PATCH v6 15/32] qcow2: Add qcow2_get_subcluster_range_type(), Alberto Garcia, 2020/05/24
- [PATCH v6 07/32] qcow2: Document the Extended L2 Entries feature, Alberto Garcia, 2020/05/24