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-rw-r--r--block/qcow2-refcount.c120
1 files changed, 120 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index 8c17c0e3aa..88d5a3f1ad 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -29,6 +29,7 @@
#include "block/qcow2.h"
#include "qemu/range.h"
#include "qemu/bswap.h"
+#include "qemu/cutils.h"
static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size);
static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
@@ -3061,3 +3062,122 @@ done:
qemu_vfree(new_refblock);
return ret;
}
+
+static int qcow2_discard_refcount_block(BlockDriverState *bs,
+ uint64_t discard_block_offs)
+{
+ BDRVQcow2State *s = bs->opaque;
+ uint64_t refblock_offs = get_refblock_offset(s, discard_block_offs);
+ uint64_t cluster_index = discard_block_offs >> s->cluster_bits;
+ uint32_t block_index = cluster_index & (s->refcount_block_size - 1);
+ void *refblock;
+ int ret;
+
+ assert(discard_block_offs != 0);
+
+ ret = qcow2_cache_get(bs, s->refcount_block_cache, refblock_offs,
+ &refblock);
+ if (ret < 0) {
+ return ret;
+ }
+
+ if (s->get_refcount(refblock, block_index) != 1) {
+ qcow2_signal_corruption(bs, true, -1, -1, "Invalid refcount:"
+ " refblock offset %#" PRIx64
+ ", reftable index %u"
+ ", block offset %#" PRIx64
+ ", refcount %#" PRIx64,
+ refblock_offs,
+ offset_to_reftable_index(s, discard_block_offs),
+ discard_block_offs,
+ s->get_refcount(refblock, block_index));
+ qcow2_cache_put(bs, s->refcount_block_cache, &refblock);
+ return -EINVAL;
+ }
+ s->set_refcount(refblock, block_index, 0);
+
+ qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache, refblock);
+
+ qcow2_cache_put(bs, s->refcount_block_cache, &refblock);
+
+ if (cluster_index < s->free_cluster_index) {
+ s->free_cluster_index = cluster_index;
+ }
+
+ refblock = qcow2_cache_is_table_offset(bs, s->refcount_block_cache,
+ discard_block_offs);
+ if (refblock) {
+ /* discard refblock from the cache if refblock is cached */
+ qcow2_cache_discard(bs, s->refcount_block_cache, refblock);
+ }
+ update_refcount_discard(bs, discard_block_offs, s->cluster_size);
+
+ return 0;
+}
+
+int qcow2_shrink_reftable(BlockDriverState *bs)
+{
+ BDRVQcow2State *s = bs->opaque;
+ uint64_t *reftable_tmp =
+ g_malloc(s->refcount_table_size * sizeof(uint64_t));
+ int i, ret;
+
+ for (i = 0; i < s->refcount_table_size; i++) {
+ int64_t refblock_offs = s->refcount_table[i] & REFT_OFFSET_MASK;
+ void *refblock;
+ bool unused_block;
+
+ if (refblock_offs == 0) {
+ reftable_tmp[i] = 0;
+ continue;
+ }
+ ret = qcow2_cache_get(bs, s->refcount_block_cache, refblock_offs,
+ &refblock);
+ if (ret < 0) {
+ goto out;
+ }
+
+ /* the refblock has own reference */
+ if (i == offset_to_reftable_index(s, refblock_offs)) {
+ uint64_t block_index = (refblock_offs >> s->cluster_bits) &
+ (s->refcount_block_size - 1);
+ uint64_t refcount = s->get_refcount(refblock, block_index);
+
+ s->set_refcount(refblock, block_index, 0);
+
+ unused_block = buffer_is_zero(refblock, s->cluster_size);
+
+ s->set_refcount(refblock, block_index, refcount);
+ } else {
+ unused_block = buffer_is_zero(refblock, s->cluster_size);
+ }
+ qcow2_cache_put(bs, s->refcount_block_cache, &refblock);
+
+ reftable_tmp[i] = unused_block ? 0 : cpu_to_be64(s->refcount_table[i]);
+ }
+
+ ret = bdrv_pwrite_sync(bs->file, s->refcount_table_offset, reftable_tmp,
+ s->refcount_table_size * sizeof(uint64_t));
+ /*
+ * If the write in the reftable failed the image may contain a partially
+ * overwritten reftable. In this case it would be better to clear the
+ * reftable in memory to avoid possible image corruption.
+ */
+ for (i = 0; i < s->refcount_table_size; i++) {
+ if (s->refcount_table[i] && !reftable_tmp[i]) {
+ if (ret == 0) {
+ ret = qcow2_discard_refcount_block(bs, s->refcount_table[i] &
+ REFT_OFFSET_MASK);
+ }
+ s->refcount_table[i] = 0;
+ }
+ }
+
+ if (!s->cache_discards) {
+ qcow2_process_discards(bs, ret);
+ }
+
+out:
+ g_free(reftable_tmp);
+ return ret;
+}