diff options
Diffstat (limited to 'block/qcow2-cluster.c')
| -rw-r--r-- | block/qcow2-cluster.c | 40 |
1 files changed, 28 insertions, 12 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 7f4f73eaca..202adb4807 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -759,31 +759,41 @@ out: * Check if there already is an AIO write request in flight which allocates * the same cluster. In this case we need to wait until the previous * request has completed and updated the L2 table accordingly. + * + * Returns: + * 0 if there was no dependency. *cur_bytes indicates the number of + * bytes from guest_offset that can be read before the next + * dependency must be processed (or the request is complete) + * + * -EAGAIN if we had to wait for another request, previously gathered + * information on cluster allocation may be invalid now. The caller + * must start over anyway, so consider *cur_bytes undefined. */ static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset, - unsigned int *nb_clusters) + uint64_t *cur_bytes) { BDRVQcowState *s = bs->opaque; QCowL2Meta *old_alloc; + uint64_t bytes = *cur_bytes; QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) { - uint64_t start = guest_offset >> s->cluster_bits; - uint64_t end = start + *nb_clusters; - uint64_t old_start = old_alloc->offset >> s->cluster_bits; - uint64_t old_end = old_start + old_alloc->nb_clusters; + uint64_t start = guest_offset; + uint64_t end = start + bytes; + uint64_t old_start = l2meta_cow_start(old_alloc); + uint64_t old_end = l2meta_cow_end(old_alloc); if (end <= old_start || start >= old_end) { /* No intersection */ } else { if (start < old_start) { /* Stop at the start of a running allocation */ - *nb_clusters = old_start - start; + bytes = old_start - start; } else { - *nb_clusters = 0; + bytes = 0; } - if (*nb_clusters == 0) { + if (bytes == 0) { /* Wait for the dependency to complete. We need to recheck * the free/allocated clusters when we continue. */ qemu_co_mutex_unlock(&s->lock); @@ -794,9 +804,9 @@ static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset, } } - if (!*nb_clusters) { - abort(); - } + /* Make sure that existing clusters and new allocations are only used up to + * the next dependency if we shortened the request above */ + *cur_bytes = bytes; return 0; } @@ -875,6 +885,7 @@ int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset, uint64_t *l2_table; unsigned int nb_clusters, keep_clusters; uint64_t cluster_offset; + uint64_t cur_bytes; trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, n_start, n_end); @@ -887,6 +898,7 @@ again: l2_index = offset_to_l2_index(s, offset); nb_clusters = MIN(size_to_clusters(s, n_end << BDRV_SECTOR_BITS), s->l2_size - l2_index); + n_end = MIN(n_end, nb_clusters * s->cluster_sectors); /* * Now start gathering as many contiguous clusters as possible: @@ -911,7 +923,8 @@ again: * 3. If the request still hasn't completed, allocate new clusters, * considering any cluster_offset of steps 1c or 2. */ - ret = handle_dependencies(bs, offset, &nb_clusters); + cur_bytes = (n_end - n_start) * BDRV_SECTOR_SIZE; + ret = handle_dependencies(bs, offset, &cur_bytes); if (ret == -EAGAIN) { goto again; } else if (ret < 0) { @@ -922,6 +935,9 @@ again: * correctly during the next loop iteration. */ } + nb_clusters = size_to_clusters(s, offset + cur_bytes) + - (offset >> s->cluster_bits); + /* Find L2 entry for the first involved cluster */ ret = get_cluster_table(bs, offset, &l2_table, &l2_index); if (ret < 0) { |