From 8f91d6906c2217b968b6b01cdcb9e0edbb4d18ab Mon Sep 17 00:00:00 2001 From: Alberto Garcia Date: Fri, 10 Jul 2020 18:12:45 +0200 Subject: [PATCH] qcow2: Add calculate_l2_meta() 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 Reviewed-by: Max Reitz Message-Id: Signed-off-by: Max Reitz --- block/qcow2-cluster.c | 77 +++++++++++++++++++++++++++++-------------- 1 file changed, 53 insertions(+), 24 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 71ddb0c462..6447222ba0 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1038,6 +1038,56 @@ void qcow2_alloc_cluster_abort(BlockDriverState *bs, QCowL2Meta *m) } } +/* + * For a given write request, create a new QCowL2Meta structure, add + * it to @m and the BDRVQcow2State.cluster_allocs list. + * + * @host_cluster_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_cluster_offset, + uint64_t guest_offset, unsigned 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_cluster_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, @@ -1436,35 +1486,14 @@ static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset, uint64_t requested_bytes = *bytes + offset_into_cluster(s, guest_offset); int avail_bytes = 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: