diff options
| -rw-r--r-- | block/qcow2-cluster.c | 240 | ||||
| -rw-r--r-- | trace-events | 1 |
2 files changed, 152 insertions, 89 deletions
diff --git a/block/qcow2-cluster.c b/block/qcow2-cluster.c index 9550927c4..454a30cab 100644 --- a/block/qcow2-cluster.c +++ b/block/qcow2-cluster.c @@ -859,6 +859,146 @@ static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset, } /* + * Allocates new clusters for an area that either is yet unallocated or needs a + * copy on write. If *host_offset is non-zero, clusters are only allocated if + * the new allocation can match the specified host offset. + * + * Note that guest_offset may not be cluster aligned. + * + * Returns: + * 0: if no clusters could be allocated. *bytes is set to 0, + * *host_offset is left unchanged. + * + * 1: if new clusters were allocated. *bytes may be decreased if the + * new allocation doesn't cover all of the requested area. + * *host_offset is updated to contain the host offset of the first + * newly allocated cluster. + * + * -errno: in error cases + * + * TODO Get rid of nb_clusters, keep_clusters, n_start, n_end + * TODO Make *bytes actually behave as specified above + */ +static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset, + uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m, + unsigned int nb_clusters, int keep_clusters, int n_start, int n_end) +{ + BDRVQcowState *s = bs->opaque; + int l2_index; + uint64_t *l2_table; + uint64_t entry; + int ret; + + uint64_t alloc_offset; + uint64_t alloc_cluster_offset; + uint64_t keep_bytes = keep_clusters * s->cluster_size; + + trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset, + *bytes); + assert(*bytes > 0); + + /* Find L2 entry for the first involved cluster */ + ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index); + if (ret < 0) { + return ret; + } + + entry = be64_to_cpu(l2_table[l2_index + keep_clusters]); + + /* For the moment, overwrite compressed clusters one by one */ + if (entry & QCOW_OFLAG_COMPRESSED) { + nb_clusters = 1; + } else { + nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, + l2_index + keep_clusters); + } + + ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); + if (ret < 0) { + return ret; + } + + if (nb_clusters == 0) { + *bytes = 0; + return 0; + } + + /* Calculate start and size of allocation */ + alloc_offset = guest_offset + keep_bytes; + + if (keep_clusters == 0) { + alloc_cluster_offset = 0; + } else { + alloc_cluster_offset = *host_offset + keep_bytes; + } + + /* Allocate, if necessary at a given offset in the image file */ + ret = do_alloc_cluster_offset(bs, alloc_offset, &alloc_cluster_offset, + &nb_clusters); + if (ret < 0) { + goto fail; + } + + /* save info needed for meta data update */ + if (nb_clusters > 0) { + /* + * requested_sectors: Number of sectors from the start of the first + * newly allocated cluster to the end of the (possibly shortened + * before) write request. + * + * avail_sectors: Number of sectors from the start of the first + * newly allocated to the end of the last newly allocated cluster. + * + * nb_sectors: The number of sectors from the start of the first + * newly allocated cluster to the end of the aread that the write + * request actually writes to (excluding COW at the end) + */ + int requested_sectors = n_end - keep_clusters * s->cluster_sectors; + int avail_sectors = nb_clusters + << (s->cluster_bits - BDRV_SECTOR_BITS); + int alloc_n_start = keep_clusters == 0 ? n_start : 0; + int nb_sectors = MIN(requested_sectors, avail_sectors); + + if (keep_clusters == 0) { + *host_offset = alloc_cluster_offset; + } + + *m = g_malloc0(sizeof(**m)); + + **m = (QCowL2Meta) { + .alloc_offset = alloc_cluster_offset, + .offset = alloc_offset & ~(s->cluster_size - 1), + .nb_clusters = nb_clusters, + .nb_available = nb_sectors, + + .cow_start = { + .offset = 0, + .nb_sectors = alloc_n_start, + }, + .cow_end = { + .offset = nb_sectors * BDRV_SECTOR_SIZE, + .nb_sectors = avail_sectors - nb_sectors, + }, + }; + qemu_co_queue_init(&(*m)->dependent_requests); + QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight); + + *bytes = nb_clusters * s->cluster_size; + } else { + *bytes = 0; + return 0; + } + + return 1; + +fail: + if (*m && (*m)->nb_clusters > 0) { + QLIST_REMOVE(*m, next_in_flight); + } + return ret; +} + +/* * alloc_cluster_offset * * For a given offset on the virtual disk, find the cluster offset in qcow2 @@ -977,93 +1117,21 @@ again: } /* If there is something left to allocate, do that now */ - if (nb_clusters > 0) { - uint64_t alloc_offset; - uint64_t alloc_cluster_offset; - uint64_t keep_bytes = keep_clusters * s->cluster_size; - - ret = get_cluster_table(bs, offset, &l2_table, &l2_index); - if (ret < 0) { - return ret; - } - - /* For the moment, overwrite compressed clusters one by one */ - uint64_t entry = be64_to_cpu(l2_table[l2_index + keep_clusters]); - if (entry & QCOW_OFLAG_COMPRESSED) { - nb_clusters = 1; - } else { - nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, - l2_index + keep_clusters); - } - - ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); - if (ret < 0) { - return ret; - } - - /* Calculate start and size of allocation */ - alloc_offset = offset + keep_bytes; - - if (keep_clusters == 0) { - alloc_cluster_offset = 0; - } else { - alloc_cluster_offset = cluster_offset + keep_bytes; - } - - /* Allocate, if necessary at a given offset in the image file */ - ret = do_alloc_cluster_offset(bs, alloc_offset, &alloc_cluster_offset, - &nb_clusters); - if (ret < 0) { - goto fail; - } - - /* save info needed for meta data update */ - if (nb_clusters > 0) { - /* - * requested_sectors: Number of sectors from the start of the first - * newly allocated cluster to the end of the (possibly shortened - * before) write request. - * - * avail_sectors: Number of sectors from the start of the first - * newly allocated to the end of the last newly allocated cluster. - * - * nb_sectors: The number of sectors from the start of the first - * newly allocated cluster to the end of the aread that the write - * request actually writes to (excluding COW at the end) - */ - int requested_sectors = n_end - keep_clusters * s->cluster_sectors; - int avail_sectors = nb_clusters - << (s->cluster_bits - BDRV_SECTOR_BITS); - int alloc_n_start = keep_clusters == 0 ? n_start : 0; - int nb_sectors = MIN(requested_sectors, avail_sectors); - - if (keep_clusters == 0) { - cluster_offset = alloc_cluster_offset; - } + if (nb_clusters == 0) { + goto done; + } - *m = g_malloc0(sizeof(**m)); - - **m = (QCowL2Meta) { - .alloc_offset = alloc_cluster_offset, - .offset = alloc_offset & ~(s->cluster_size - 1), - .nb_clusters = nb_clusters, - .nb_available = nb_sectors, - - .cow_start = { - .offset = 0, - .nb_sectors = alloc_n_start, - }, - .cow_end = { - .offset = nb_sectors * BDRV_SECTOR_SIZE, - .nb_sectors = avail_sectors - nb_sectors, - }, - }; - qemu_co_queue_init(&(*m)->dependent_requests); - QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight); - } + cur_bytes = nb_clusters * s->cluster_size; + ret = handle_alloc(bs, offset, &cluster_offset, &cur_bytes, m, + nb_clusters, keep_clusters, n_start, n_end); + if (ret < 0) { + return ret; } + nb_clusters = size_to_clusters(s, cur_bytes); + /* Some cleanup work */ +done: sectors = (keep_clusters + nb_clusters) << (s->cluster_bits - 9); if (sectors > n_end) { sectors = n_end; @@ -1074,12 +1142,6 @@ again: *host_offset = cluster_offset; return 0; - -fail: - if (*m && (*m)->nb_clusters > 0) { - QLIST_REMOVE(*m, next_in_flight); - } - return ret; } static int decompress_buffer(uint8_t *out_buf, int out_buf_size, diff --git a/trace-events b/trace-events index 406fe5f40..9511a28ca 100644 --- a/trace-events +++ b/trace-events @@ -483,6 +483,7 @@ qcow2_writev_done_part(void *co, int cur_nr_sectors) "co %p cur_nr_sectors %d" qcow2_writev_data(void *co, uint64_t offset) "co %p offset %" PRIx64 qcow2_alloc_clusters_offset(void *co, uint64_t offset, int n_start, int n_end) "co %p offet %" PRIx64 " n_start %d n_end %d" +qcow2_handle_alloc(void *co, uint64_t guest_offset, uint64_t host_offset, uint64_t bytes) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " bytes %" PRIx64 qcow2_do_alloc_clusters_offset(void *co, uint64_t guest_offset, uint64_t host_offset, int nb_clusters) "co %p guest_offet %" PRIx64 " host_offset %" PRIx64 " nb_clusters %d" qcow2_cluster_alloc_phys(void *co) "co %p" qcow2_cluster_link_l2(void *co, int nb_clusters) "co %p nb_clusters %d" |