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Diffstat (limited to 'block/qcow2-refcount.c')
-rw-r--r--block/qcow2-refcount.c82
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++) {