diff options
| -rw-r--r-- | block/qcow2-cluster.c | 5 | ||||
| -rw-r--r-- | block/qcow2.c | 19 | ||||
| -rw-r--r-- | block/qcow2.h | 19 |
3 files changed, 29 insertions, 14 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index aa87d3e99b..485b4cb92e 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -1049,6 +1049,8 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_slice); assert(l2_index + m->nb_clusters <= s->l2_slice_size); + assert(m->cow_end.offset + m->cow_end.nb_bytes <= + m->nb_clusters << s->cluster_bits); for (i = 0; i < m->nb_clusters; i++) { uint64_t offset = cluster_offset + ((uint64_t)i << s->cluster_bits); /* if two concurrent writes happen to the same unallocated cluster @@ -1070,8 +1072,7 @@ int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m) if (has_subclusters(s) && !m->prealloc) { 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; + unsigned written_to = m->cow_end.offset + m->cow_end.nb_bytes; 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); diff --git a/block/qcow2.c b/block/qcow2.c index 4274806a2a..1b0733238b 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -2361,15 +2361,26 @@ static bool merge_cow(uint64_t offset, unsigned bytes, continue; } - /* The data (middle) region must be immediately after the - * start region */ + /* + * The write request should start immediately after the first + * COW region. This does not always happen because the area + * touched by the request can be larger than the one defined + * by @m (a single request can span an area consisting of a + * mix of previously unallocated and allocated clusters, that + * is why @l2meta is a list). + */ if (l2meta_cow_start(m) + m->cow_start.nb_bytes != offset) { + /* In this case the request starts before this region */ + assert(offset < l2meta_cow_start(m)); + assert(m->cow_start.nb_bytes == 0); continue; } - /* The end region must be immediately after the data (middle) - * region */ + /* The write request should end immediately before the second + * COW region (see above for why it does not always happen) */ if (m->offset + m->cow_end.offset != offset + bytes) { + assert(offset + bytes > m->offset + m->cow_end.offset); + assert(m->cow_end.nb_bytes == 0); continue; } diff --git a/block/qcow2.h b/block/qcow2.h index 125ea9679b..2e0272a7b8 100644 --- a/block/qcow2.h +++ b/block/qcow2.h @@ -435,17 +435,18 @@ typedef struct Qcow2COWRegion { /** * Describes an in-flight (part of a) write request that writes to clusters - * that are not referenced in their L2 table yet. + * that need to have their L2 table entries updated (because they are + * newly allocated or need changes in their L2 bitmaps) */ typedef struct QCowL2Meta { - /** Guest offset of the first newly allocated cluster */ + /** Guest offset of the first updated cluster */ uint64_t offset; - /** Host offset of the first newly allocated cluster */ + /** Host offset of the first updated cluster */ uint64_t alloc_offset; - /** Number of newly allocated clusters */ + /** Number of updated clusters */ int nb_clusters; /** Do not free the old clusters */ @@ -458,14 +459,16 @@ typedef struct QCowL2Meta CoQueue dependent_requests; /** - * The COW Region between the start of the first allocated cluster and the - * area the guest actually writes to. + * The COW Region immediately before the area the guest actually + * writes to. This (part of the) write request starts at + * cow_start.offset + cow_start.nb_bytes. */ Qcow2COWRegion cow_start; /** - * The COW Region between the area the guest actually writes to and the - * end of the last allocated cluster. + * The COW Region immediately after the area the guest actually + * writes to. This (part of the) write request ends at cow_end.offset + * (which must always be set even when cow_end.nb_bytes is 0). */ Qcow2COWRegion cow_end; |