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[PATCH v8 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2(
From: |
Alberto Garcia |
Subject: |
[PATCH v8 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2() |
Date: |
Wed, 10 Jun 2020 17:03:03 +0200 |
The L2 bitmap needs to be updated after each write to indicate what
new subclusters are now allocated. This needs to happen even if the
cluster was already allocated and the L2 entry was otherwise valid.
In some cases however a write operation doesn't need change the L2
bitmap (because all affected subclusters were already allocated). This
is detected in calculate_l2_meta(), and qcow2_alloc_cluster_link_l2()
is never called in those cases.
Signed-off-by: Alberto Garcia <berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
---
block/qcow2-cluster.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index edfc8ea91c..2276cee6d6 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1061,6 +1061,24 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs,
QCowL2Meta *m)
assert((offset & L2E_OFFSET_MASK) == offset);
set_l2_entry(s, l2_slice, l2_index + i, offset | QCOW_OFLAG_COPIED);
+
+ /* Update bitmap with the subclusters that were just written */
+ if (has_subclusters(s)) {
+ uint64_t l2_bitmap = get_l2_bitmap(s, l2_slice, l2_index + i);
+ unsigned written_from = m->cow_start.offset;
+ unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes ?:
+ m->nb_clusters << s->cluster_bits;
+ int first_sc, last_sc;
+ /* Narrow written_from and written_to down to the current cluster
*/
+ written_from = MAX(written_from, i << s->cluster_bits);
+ written_to = MIN(written_to, (i + 1) << s->cluster_bits);
+ assert(written_from < written_to);
+ first_sc = offset_to_sc_index(s, written_from);
+ last_sc = offset_to_sc_index(s, written_to - 1);
+ l2_bitmap |= QCOW_OFLAG_SUB_ALLOC_RANGE(first_sc, last_sc + 1);
+ l2_bitmap &= ~QCOW_OFLAG_SUB_ZERO_RANGE(first_sc, last_sc + 1);
+ set_l2_bitmap(s, l2_slice, l2_index + i, l2_bitmap);
+ }
}
--
2.20.1
- Re: [PATCH v8 32/34] qcow2: Allow preallocation and backing files if extended_l2 is set, (continued)
- [PATCH v8 05/34] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied(), Alberto Garcia, 2020/06/10
- [PATCH v8 33/34] qcow2: Assert that expand_zero_clusters_in_l1() does not support subclusters, Alberto Garcia, 2020/06/10
- [PATCH v8 14/34] qcow2: Add QCow2SubclusterType and qcow2_get_subcluster_type(), Alberto Garcia, 2020/06/10
- [PATCH v8 31/34] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit, Alberto Garcia, 2020/06/10
- [PATCH v8 21/34] qcow2: Add subcluster support to qcow2_get_host_offset(), Alberto Garcia, 2020/06/10
- [PATCH v8 30/34] qcow2: Add prealloc field to QCowL2Meta, Alberto Garcia, 2020/06/10
- [PATCH v8 27/34] qcow2: Add subcluster support to handle_alloc_space(), Alberto Garcia, 2020/06/10
- [PATCH v8 25/34] qcow2: Update L2 bitmap in qcow2_alloc_cluster_link_l2(),
Alberto Garcia <=
- [PATCH v8 26/34] qcow2: Clear the L2 bitmap when allocating a compressed cluster, Alberto Garcia, 2020/06/10
- [PATCH v8 17/34] qcow2: Add cluster type parameter to qcow2_get_host_offset(), Alberto Garcia, 2020/06/10
- [PATCH v8 20/34] qcow2: Add subcluster support to calculate_l2_meta(), Alberto Garcia, 2020/06/10
- [PATCH v8 24/34] qcow2: Add subcluster support to check_refcounts_l2(), Alberto Garcia, 2020/06/10
- [PATCH v8 18/34] qcow2: Replace QCOW2_CLUSTER_* with QCOW2_SUBCLUSTER_*, Alberto Garcia, 2020/06/10
- [PATCH v8 28/34] qcow2: Add subcluster support to qcow2_co_pwrite_zeroes(), Alberto Garcia, 2020/06/10
- [PATCH v8 34/34] iotests: Add tests for qcow2 images with extended L2 entries, Alberto Garcia, 2020/06/10
- Re: [PATCH v8 00/34] Add subcluster allocation to qcow2, Eric Blake, 2020/06/10
- Re: [PATCH v8 00/34] Add subcluster allocation to qcow2, no-reply, 2020/06/10