#include "qemu/bswap.h"
#include "trace.h"
+int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t exact_size)
+{
+ BDRVQcow2State *s = bs->opaque;
+ int new_l1_size, i, ret;
+
+ if (exact_size >= s->l1_size) {
+ return 0;
+ }
+
+ new_l1_size = exact_size;
+
+#ifdef DEBUG_ALLOC2
+ fprintf(stderr, "shrink l1_table from %d to %d\n", s->l1_size, new_l1_size);
+#endif
+
+ BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_WRITE_TABLE);
+ ret = bdrv_pwrite_zeroes(bs->file, s->l1_table_offset +
+ new_l1_size * sizeof(uint64_t),
+ (s->l1_size - new_l1_size) * sizeof(uint64_t), 0);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ ret = bdrv_flush(bs->file->bs);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ BLKDBG_EVENT(bs->file, BLKDBG_L1_SHRINK_FREE_L2_CLUSTERS);
+ for (i = s->l1_size - 1; i > new_l1_size - 1; i--) {
+ if ((s->l1_table[i] & L1E_OFFSET_MASK) == 0) {
+ continue;
+ }
+ qcow2_free_clusters(bs, s->l1_table[i] & L1E_OFFSET_MASK,
+ s->cluster_size, QCOW2_DISCARD_ALWAYS);
+ s->l1_table[i] = 0;
+ }
+ return 0;
+
+fail:
+ /*
+ * If the write in the l1_table failed the image may contain a partially
+ * overwritten l1_table. In this case it would be better to clear the
+ * l1_table in memory to avoid possible image corruption.
+ */
+ memset(s->l1_table + new_l1_size, 0,
+ (s->l1_size - new_l1_size) * sizeof(uint64_t));
+ return ret;
+}
+
int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
bool exact_size)
{
#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,
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;
+}
}
old_length = bs->total_sectors * 512;
+ new_l1_size = size_to_l1(s, offset);
- /* shrinking is currently not supported */
if (offset < old_length) {
- error_setg(errp, "qcow2 doesn't support shrinking images yet");
- return -ENOTSUP;
- }
+ if (prealloc != PREALLOC_MODE_OFF) {
+ error_setg(errp,
+ "Preallocation can't be used for shrinking an image");
+ return -EINVAL;
+ }
- new_l1_size = size_to_l1(s, offset);
- ret = qcow2_grow_l1_table(bs, new_l1_size, true);
- if (ret < 0) {
- error_setg_errno(errp, -ret, "Failed to grow the L1 table");
- return ret;
+ ret = qcow2_cluster_discard(bs, ROUND_UP(offset, s->cluster_size),
+ old_length - ROUND_UP(offset,
+ s->cluster_size),
+ QCOW2_DISCARD_ALWAYS, true);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Failed to discard cropped clusters");
+ return ret;
+ }
+
+ ret = qcow2_shrink_l1_table(bs, new_l1_size);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "Failed to reduce the number of L2 tables");
+ return ret;
+ }
+
+ ret = qcow2_shrink_reftable(bs);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret,
+ "Failed to discard unused refblocks");
+ return ret;
+ }
+ } else {
+ ret = qcow2_grow_l1_table(bs, new_l1_size, true);
+ if (ret < 0) {
+ error_setg_errno(errp, -ret, "Failed to grow the L1 table");
+ return ret;
+ }
}
switch (prealloc) {
return r1 > r2 ? r1 - r2 : r2 - r1;
}
+static inline
+uint32_t offset_to_reftable_index(BDRVQcow2State *s, uint64_t offset)
+{
+ return offset >> (s->refcount_block_bits + s->cluster_bits);
+}
+
+static inline uint64_t get_refblock_offset(BDRVQcow2State *s, uint64_t offset)
+{
+ uint32_t index = offset_to_reftable_index(s, offset);
+ return s->refcount_table[index] & REFT_OFFSET_MASK;
+}
+
/* qcow2.c functions */
int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
int64_t sector_num, int nb_sectors);
int qcow2_change_refcount_order(BlockDriverState *bs, int refcount_order,
BlockDriverAmendStatusCB *status_cb,
void *cb_opaque, Error **errp);
+int qcow2_shrink_reftable(BlockDriverState *bs);
/* qcow2-cluster.c functions */
int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
bool exact_size);
+int qcow2_shrink_l1_table(BlockDriverState *bs, uint64_t max_size);
int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index);
int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset);
int qcow2_encrypt_sectors(BDRVQcow2State *s, int64_t sector_num,
#
# Trigger events supported by blkdebug.
#
+# @l1_shrink_write_table: write zeros to the l1 table to shrink image.
+# (since 2.11)
+#
+# @l1_shrink_free_l2_clusters: discard the l2 tables. (since 2.11)
+#
# Since: 2.9
##
{ 'enum': 'BlkdebugEvent', 'prefix': 'BLKDBG',
'cluster_alloc_bytes', 'cluster_free', 'flush_to_os',
'flush_to_disk', 'pwritev_rmw_head', 'pwritev_rmw_after_head',
'pwritev_rmw_tail', 'pwritev_rmw_after_tail', 'pwritev',
- 'pwritev_zero', 'pwritev_done', 'empty_image_prepare' ] }
+ 'pwritev_zero', 'pwritev_done', 'empty_image_prepare',
+ 'l1_shrink_write_table', 'l1_shrink_free_l2_clusters' ] }
##
# @BlkdebugInjectErrorOptions:
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