From 2ac728f96c56939949a1836a340fabc3ab899b05 Mon Sep 17 00:00:00 2001 Message-Id: <2ac728f96c56939949a1836a340fabc3ab899b05.1429902956.git.jen@redhat.com> In-Reply-To: <67968bc615637394c3ef7dfefa360dab90f33d5d.1429902956.git.jen@redhat.com> References: <67968bc615637394c3ef7dfefa360dab90f33d5d.1429902956.git.jen@redhat.com> From: Max Reitz Date: Wed, 18 Mar 2015 19:21:46 -0500 Subject: [CHANGE 03/42] qcow2: Ignore reserved bits in count_contiguous_clusters() To: rhvirt-patches@redhat.com, jen@redhat.com RH-Author: Max Reitz Message-id: <1426706542-30384-4-git-send-email-mreitz@redhat.com> Patchwork-id: 64467 O-Subject: [RHEL-6.7 qemu-kvm PATCH v2 03/39] qcow2: Ignore reserved bits in count_contiguous_clusters() Bugzilla: 1129892 RH-Acked-by: Jeffrey Cody RH-Acked-by: Kevin Wolf RH-Acked-by: Stefan Hajnoczi From: Kevin Wolf BZ: 1129892 Until now, count_contiguous_clusters() has an argument that allowed to specify flags that should be ignored in the comparison, i.e. that are allowed to change between contiguous clusters. This patch changes the function so that it ignores all flags by default now and you need to pass the flags on which it should stop. Signed-off-by: Kevin Wolf (cherry picked from commit 2bfcc4a0a0b5120b6518e1c823c18cf0e8b963cb) Signed-off-by: Jeff E. Nelson Conflicts: block/qcow2-cluster.c 250196f19c6e7df12965d74a5073e10aba06c802 missing downstream. Signed-off-by: Max Reitz --- block/qcow2-cluster.c | 38 ++++++++++++++++++++++++++++---------- 1 file changed, 28 insertions(+), 10 deletions(-) Signed-off-by: Jeff E. Nelson --- block/qcow2-cluster.c | 38 ++++++++++++++++++++++++++++---------- 1 file changed, 28 insertions(+), 10 deletions(-) diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index d2c7beb..7ff8b50 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -255,28 +255,44 @@ fail: return ret; } +/* + * Checks how many clusters in a given L2 table are contiguous in the image + * file. As soon as one of the flags in the bitmask stop_flags changes compared + * to the first cluster, the search is stopped and the cluster is not counted + * as contiguous. (This allows it, for example, to stop at the first compressed + * cluster which may require a different handling) + */ static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size, - uint64_t *l2_table, uint64_t start, uint64_t mask) + uint64_t *l2_table, uint64_t start, uint64_t stop_flags) { int i; - uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask; + uint64_t mask = stop_flags | L2E_OFFSET_MASK; + uint64_t offset = be64_to_cpu(l2_table[0]) & mask; if (!offset) return 0; - for (i = start; i < start + nb_clusters; i++) - if (offset + (uint64_t) i * cluster_size != (be64_to_cpu(l2_table[i]) & ~mask)) + for (i = start; i < start + nb_clusters; i++) { + uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask; + if (offset + (uint64_t) i * cluster_size != l2_entry) { break; + } + } return (i - start); } static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table) { - int i = 0; + int i; - while(nb_clusters-- && l2_table[i] == 0) - i++; + for (i = 0; i < nb_clusters; i++) { + int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i])); + + if (type != QCOW2_CLUSTER_UNALLOCATED) { + break; + } + } return i; } @@ -493,7 +509,7 @@ int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset, case QCOW2_CLUSTER_NORMAL: /* how many allocated clusters ? */ c = count_contiguous_clusters(nb_clusters, s->cluster_size, - &l2_table[l2_index], 0, QCOW_OFLAG_COPIED); + &l2_table[l2_index], 0, QCOW_OFLAG_COMPRESSED); *cluster_offset &= L2E_OFFSET_MASK; break; } @@ -741,7 +757,8 @@ static int count_cow_clusters(BDRVQcowState *s, int nb_clusters, while (i < nb_clusters) { i += count_contiguous_clusters(nb_clusters - i, s->cluster_size, - &l2_table[l2_index], i, 0); + &l2_table[l2_index], i, + QCOW_OFLAG_COPIED | QCOW_OFLAG_COMPRESSED); if ((i >= nb_clusters) || be64_to_cpu(l2_table[l2_index + i])) { break; } @@ -808,7 +825,8 @@ again: if (cluster_offset & QCOW_OFLAG_COPIED) { nb_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size, - &l2_table[l2_index], 0, 0); + &l2_table[l2_index], 0, + QCOW_OFLAG_COPIED); cluster_offset &= L2E_OFFSET_MASK; m->nb_clusters = 0; -- 2.1.0