diff options
Diffstat (limited to 'block/qcow2-refcount.c')
-rw-r--r-- | block/qcow2-refcount.c | 82 |
1 files changed, 79 insertions, 3 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index 7488988a9a..1244693f39 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -420,6 +420,74 @@ fail_block: return ret; } +void qcow2_process_discards(BlockDriverState *bs, int ret) +{ + BDRVQcowState *s = bs->opaque; + Qcow2DiscardRegion *d, *next; + + QTAILQ_FOREACH_SAFE(d, &s->discards, next, next) { + QTAILQ_REMOVE(&s->discards, d, next); + + /* Discard is optional, ignore the return value */ + if (ret >= 0) { + bdrv_discard(bs->file, + d->offset >> BDRV_SECTOR_BITS, + d->bytes >> BDRV_SECTOR_BITS); + } + + g_free(d); + } +} + +static void update_refcount_discard(BlockDriverState *bs, + uint64_t offset, uint64_t length) +{ + BDRVQcowState *s = bs->opaque; + Qcow2DiscardRegion *d, *p, *next; + + QTAILQ_FOREACH(d, &s->discards, next) { + uint64_t new_start = MIN(offset, d->offset); + uint64_t new_end = MAX(offset + length, d->offset + d->bytes); + + if (new_end - new_start <= length + d->bytes) { + /* There can't be any overlap, areas ending up here have no + * references any more and therefore shouldn't get freed another + * time. */ + assert(d->bytes + length == new_end - new_start); + d->offset = new_start; + d->bytes = new_end - new_start; + goto found; + } + } + + d = g_malloc(sizeof(*d)); + *d = (Qcow2DiscardRegion) { + .bs = bs, + .offset = offset, + .bytes = length, + }; + QTAILQ_INSERT_TAIL(&s->discards, d, next); + +found: + /* Merge discard requests if they are adjacent now */ + QTAILQ_FOREACH_SAFE(p, &s->discards, next, next) { + if (p == d + || p->offset > d->offset + d->bytes + || d->offset > p->offset + p->bytes) + { + continue; + } + + /* Still no overlap possible */ + assert(p->offset == d->offset + d->bytes + || d->offset == p->offset + p->bytes); + + QTAILQ_REMOVE(&s->discards, p, next); + d->offset = MIN(d->offset, p->offset); + d->bytes += p->bytes; + } +} + /* XXX: cache several refcount block clusters ? */ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, int64_t offset, int64_t length, int addend, enum qcow2_discard_type type) @@ -488,15 +556,18 @@ static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs, s->free_cluster_index = cluster_index; } refcount_block[block_index] = cpu_to_be16(refcount); + if (refcount == 0 && s->discard_passthrough[type]) { - /* Try discarding, ignore errors */ - /* FIXME Doing this cluster by cluster will be painfully slow */ - bdrv_discard(bs->file, cluster_offset, 1); + update_refcount_discard(bs, cluster_offset, s->cluster_size); } } ret = 0; fail: + if (!s->cache_discards) { + qcow2_process_discards(bs, ret); + } + /* Write last changed block to disk */ if (refcount_block) { int wret; @@ -755,6 +826,8 @@ int qcow2_update_snapshot_refcount(BlockDriverState *bs, l1_table = NULL; l1_size2 = l1_size * sizeof(uint64_t); + s->cache_discards = true; + /* WARNING: qcow2_snapshot_goto relies on this function not using the * l1_table_offset when it is the current s->l1_table_offset! Be careful * when changing this! */ @@ -867,6 +940,9 @@ fail: qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table); } + s->cache_discards = false; + qcow2_process_discards(bs, ret); + /* Update L1 only if it isn't deleted anyway (addend = -1) */ if (ret == 0 && addend >= 0 && l1_modified) { for (i = 0; i < l1_size; i++) { |