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[RFC PATCH 01/23] qcow2: Add calculate_l2_meta()
From: |
Alberto Garcia |
Subject: |
[RFC PATCH 01/23] qcow2: Add calculate_l2_meta() |
Date: |
Tue, 15 Oct 2019 18:23:12 +0300 |
handle_alloc() creates a QCowL2Meta structure in order to update the
image metadata and perform the necessary copy-on-write operations.
This patch moves that code to a separate function so it can be used
from other places.
Signed-off-by: Alberto Garcia <address@hidden>
---
block/qcow2-cluster.c | 76 +++++++++++++++++++++++++++++--------------
1 file changed, 52 insertions(+), 24 deletions(-)
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c
index 8d5fa1539c..fe2523ed66 100644
--- a/block/qcow2-cluster.c
+++ b/block/qcow2-cluster.c
@@ -1019,6 +1019,55 @@ void qcow2_alloc_cluster_abort(BlockDriverState *bs,
QCowL2Meta *m)
QCOW2_DISCARD_NEVER);
}
+/*
+ * For a given write request, create a new QCowL2Meta structure and
+ * add it to @m.
+ *
+ * @host_offset points to the beginning of the first cluster.
+ *
+ * @guest_offset and @bytes indicate the offset and length of the
+ * request.
+ *
+ * If @keep_old is true it means that the clusters were already
+ * allocated and will be overwritten. If false then the clusters are
+ * new and we have to decrease the reference count of the old ones.
+ */
+static void calculate_l2_meta(BlockDriverState *bs, uint64_t host_offset,
+ uint64_t guest_offset, uint64_t bytes,
+ QCowL2Meta **m, bool keep_old)
+{
+ BDRVQcow2State *s = bs->opaque;
+ unsigned cow_start_from = 0;
+ unsigned cow_start_to = offset_into_cluster(s, guest_offset);
+ unsigned cow_end_from = cow_start_to + bytes;
+ unsigned cow_end_to = ROUND_UP(cow_end_from, s->cluster_size);
+ unsigned nb_clusters = size_to_clusters(s, cow_end_from);
+ QCowL2Meta *old_m = *m;
+
+ *m = g_malloc0(sizeof(**m));
+ **m = (QCowL2Meta) {
+ .next = old_m,
+
+ .alloc_offset = host_offset,
+ .offset = start_of_cluster(s, guest_offset),
+ .nb_clusters = nb_clusters,
+
+ .keep_old_clusters = keep_old,
+
+ .cow_start = {
+ .offset = cow_start_from,
+ .nb_bytes = cow_start_to - cow_start_from,
+ },
+ .cow_end = {
+ .offset = cow_end_from,
+ .nb_bytes = cow_end_to - cow_end_from,
+ },
+ };
+
+ qemu_co_queue_init(&(*m)->dependent_requests);
+ QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
+}
+
/*
* Returns the number of contiguous clusters that can be used for an allocating
* write, but require COW to be performed (this includes yet unallocated space,
@@ -1414,35 +1463,14 @@ static int handle_alloc(BlockDriverState *bs, uint64_t
guest_offset,
uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset);
int avail_bytes = MIN(INT_MAX, nb_clusters << s->cluster_bits);
int nb_bytes = MIN(requested_bytes, avail_bytes);
- QCowL2Meta *old_m = *m;
-
- *m = g_malloc0(sizeof(**m));
-
- **m = (QCowL2Meta) {
- .next = old_m,
-
- .alloc_offset = alloc_cluster_offset,
- .offset = start_of_cluster(s, guest_offset),
- .nb_clusters = nb_clusters,
-
- .keep_old_clusters = keep_old_clusters,
-
- .cow_start = {
- .offset = 0,
- .nb_bytes = offset_into_cluster(s, guest_offset),
- },
- .cow_end = {
- .offset = nb_bytes,
- .nb_bytes = avail_bytes - nb_bytes,
- },
- };
- qemu_co_queue_init(&(*m)->dependent_requests);
- QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
*host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
*bytes = MIN(*bytes, nb_bytes - offset_into_cluster(s, guest_offset));
assert(*bytes != 0);
+ calculate_l2_meta(bs, alloc_cluster_offset, guest_offset, *bytes,
+ m, keep_old_clusters);
+
return 1;
fail:
--
2.20.1
- [RFC PATCH 00/23] Add subcluster allocation to qcow2, Alberto Garcia, 2019/10/15
- [RFC PATCH 10/23] qcow2: Update get/set_l2_entry() and add get/set_l2_bitmap(), Alberto Garcia, 2019/10/15
- [RFC PATCH 01/23] qcow2: Add calculate_l2_meta(),
Alberto Garcia <=
- [RFC PATCH 16/23] qcow2: Add subcluster support to discard_in_l2_slice(), Alberto Garcia, 2019/10/15
- [RFC PATCH 06/23] qcow2: Add dummy has_subclusters() function, Alberto Garcia, 2019/10/15
- [RFC PATCH 12/23] qcow2: Handle QCOW2_CLUSTER_UNALLOCATED_SUBCLUSTER, Alberto Garcia, 2019/10/15
- [RFC PATCH 09/23] qcow2: Add l2_entry_size(), Alberto Garcia, 2019/10/15
- [RFC PATCH 03/23] qcow2: Process QCOW2_CLUSTER_ZERO_ALLOC clusters in handle_copied(), Alberto Garcia, 2019/10/15
- [RFC PATCH 05/23] qcow2: Document the Extended L2 Entries feature, Alberto Garcia, 2019/10/15
- [RFC PATCH 04/23] qcow2: Add get_l2_entry() and set_l2_entry(), Alberto Garcia, 2019/10/15
- [RFC PATCH 23/23] qcow2: Add the 'extended_l2' option and the QCOW2_INCOMPAT_EXTL2 bit, Alberto Garcia, 2019/10/15
- [RFC PATCH 11/23] qcow2: Add qcow2_get_subcluster_type(), Alberto Garcia, 2019/10/15