From fca40ea19ca3800a971fd16f6c463184dc35a44e Mon Sep 17 00:00:00 2001 Message-Id: In-Reply-To: <67968bc615637394c3ef7dfefa360dab90f33d5d.1429902956.git.jen@redhat.com> References: <67968bc615637394c3ef7dfefa360dab90f33d5d.1429902956.git.jen@redhat.com> From: Max Reitz Date: Wed, 18 Mar 2015 19:21:45 -0500 Subject: [CHANGE 02/42] qcow2: Factor out count_cow_clusters To: rhvirt-patches@redhat.com, jen@redhat.com RH-Author: Max Reitz Message-id: <1426706542-30384-3-git-send-email-mreitz@redhat.com> Patchwork-id: 64466 O-Subject: [RHEL-6.7 qemu-kvm PATCH v2 02/39] qcow2: Factor out count_cow_clusters Bugzilla: 1129892 RH-Acked-by: Jeffrey Cody RH-Acked-by: Kevin Wolf RH-Acked-by: Stefan Hajnoczi From: Kevin Wolf BZ: 1129892 Signed-off-by: Kevin Wolf Reviewed-by: Stefan Hajnoczi (cherry picked from commit bf319ece56bc07608bfdf46b8ef5c61b52be83f6) Signed-off-by: Jeff E. Nelson Conflicts: block/qcow2-cluster.c Conflicts because of downstream-only commit f4dfd3f3a2a6d8d779252df8703cf83294afb5a6. The "later code changes" upstream which "fixed this bug as a side effect" mentioned in that commit are exactly this patch (which replaces the downstream fix by the upstream code). Signed-off-by: Max Reitz --- block/qcow2-cluster.c | 55 +++++++++++++++++++++++++++++++++------------------ 1 file changed, 36 insertions(+), 19 deletions(-) Signed-off-by: Jeff E. Nelson --- block/qcow2-cluster.c | 55 +++++++++++++++++++++++++++++++++------------------ 1 file changed, 36 insertions(+), 19 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 439c86d..d2c7beb 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -729,6 +729,41 @@ err: } /* + * 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, + * which must copy from the backing file) + */ +static int count_cow_clusters(BDRVQcowState *s, int nb_clusters, + uint64_t *l2_table, int l2_index) +{ + int i = 0; + uint64_t cluster_offset; + + while (i < nb_clusters) { + i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, + &l2_table[l2_index], i, 0); + if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { + break; + } + + i += count_contiguous_free_clusters(nb_clusters - i, + &l2_table[l2_index + i]); + if (i >= nb_clusters) { + break; + } + + cluster_offset = be64_to_cpu(l2_table[l2_index + i]); + + if ((cluster_offset & QCOW_OFLAG_COPIED) || + (cluster_offset & QCOW_OFLAG_COMPRESSED)) + break; + } + + assert(i <= nb_clusters); + return i; +} + +/* * alloc_cluster_offset * * For a given offset of the disk image, return cluster offset in qcow2 file. @@ -793,26 +828,8 @@ again: nb_clusters = 1; /* how many available clusters ? */ - i = 0; - while (i < nb_clusters) { - i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, - &l2_table[l2_index], i, 0); - if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { - break; - } - i += count_contiguous_free_clusters(nb_clusters - i, - &l2_table[l2_index + i]); - if (i >= nb_clusters) { - break; - } - - cluster_offset = be64_to_cpu(l2_table[l2_index + i]); - - if ((cluster_offset & QCOW_OFLAG_COPIED) || - (cluster_offset & QCOW_OFLAG_COMPRESSED)) - break; - } + i = count_cow_clusters(s, nb_clusters, l2_table, l2_index); assert(i <= nb_clusters); nb_clusters = i; -- 2.1.0