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-rw-r--r--block/qcow2-refcount.c267
-rw-r--r--block/qcow2.c20
-rw-r--r--block/qcow2.h4
-rw-r--r--tests/qemu-iotests/044.out2
4 files changed, 204 insertions, 89 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index e82e155208..082b5de4cd 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -34,6 +34,10 @@ static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size);
static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
int64_t offset, int64_t length, uint64_t addend,
bool decrease, enum qcow2_discard_type type);
+static int64_t qcow2_refcount_area(BlockDriverState *bs, uint64_t offset,
+ uint64_t additional_clusters,
+ bool exact_size, int new_refblock_index,
+ uint64_t new_refblock_offset);
static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index);
static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index);
@@ -281,25 +285,6 @@ int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index,
return 0;
}
-/*
- * Rounds the refcount table size up to avoid growing the table for each single
- * refcount block that is allocated.
- */
-static unsigned int next_refcount_table_size(BDRVQcow2State *s,
- unsigned int min_size)
-{
- unsigned int min_clusters = (min_size >> (s->cluster_bits - 3)) + 1;
- unsigned int refcount_table_clusters =
- MAX(1, s->refcount_table_size >> (s->cluster_bits - 3));
-
- while (min_clusters > refcount_table_clusters) {
- refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2;
- }
-
- return refcount_table_clusters << (s->cluster_bits - 3);
-}
-
-
/* Checks if two offsets are described by the same refcount block */
static int in_same_refcount_block(BDRVQcow2State *s, uint64_t offset_a,
uint64_t offset_b)
@@ -321,7 +306,7 @@ static int alloc_refcount_block(BlockDriverState *bs,
{
BDRVQcow2State *s = bs->opaque;
unsigned int refcount_table_index;
- int ret;
+ int64_t ret;
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC);
@@ -490,74 +475,201 @@ static int alloc_refcount_block(BlockDriverState *bs,
(new_block >> s->cluster_bits) + 1),
s->refcount_block_size);
- if (blocks_used > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) {
- return -EFBIG;
+ /* Create the new refcount table and blocks */
+ uint64_t meta_offset = (blocks_used * s->refcount_block_size) *
+ s->cluster_size;
+
+ ret = qcow2_refcount_area(bs, meta_offset, 0, false,
+ refcount_table_index, new_block);
+ if (ret < 0) {
+ return ret;
}
- /* And now we need at least one block more for the new metadata */
- uint64_t table_size = next_refcount_table_size(s, blocks_used + 1);
- uint64_t last_table_size;
- uint64_t blocks_clusters;
- do {
- uint64_t table_clusters =
- size_to_clusters(s, table_size * sizeof(uint64_t));
- blocks_clusters = 1 +
- DIV_ROUND_UP(table_clusters, s->refcount_block_size);
- uint64_t meta_clusters = table_clusters + blocks_clusters;
+ ret = load_refcount_block(bs, new_block, refcount_block);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* If we were trying to do the initial refcount update for some cluster
+ * allocation, we might have used the same clusters to store newly
+ * allocated metadata. Make the caller search some new space. */
+ return -EAGAIN;
+
+fail_block:
+ if (*refcount_block != NULL) {
+ qcow2_cache_put(bs, s->refcount_block_cache, refcount_block);
+ }
+ return ret;
+}
+
+/*
+ * Starting at @start_offset, this function creates new self-covering refcount
+ * structures: A new refcount table and refcount blocks which cover all of
+ * themselves, and a number of @additional_clusters beyond their end.
+ * @start_offset must be at the end of the image file, that is, there must be
+ * only empty space beyond it.
+ * If @exact_size is false, the refcount table will have 50 % more entries than
+ * necessary so it will not need to grow again soon.
+ * If @new_refblock_offset is not zero, it contains the offset of a refcount
+ * block that should be entered into the new refcount table at index
+ * @new_refblock_index.
+ *
+ * Returns: The offset after the new refcount structures (i.e. where the
+ * @additional_clusters may be placed) on success, -errno on error.
+ */
+static int64_t qcow2_refcount_area(BlockDriverState *bs, uint64_t start_offset,
+ uint64_t additional_clusters,
+ bool exact_size, int new_refblock_index,
+ uint64_t new_refblock_offset)
+{
+ BDRVQcow2State *s = bs->opaque;
+ uint64_t total_refblock_count_u64, additional_refblock_count;
+ int total_refblock_count, table_size, area_reftable_index, table_clusters;
+ int i;
+ uint64_t table_offset, block_offset, end_offset;
+ int ret;
+ uint64_t *new_table;
- last_table_size = table_size;
- table_size = next_refcount_table_size(s, blocks_used +
- DIV_ROUND_UP(meta_clusters, s->refcount_block_size));
+ assert(!(start_offset % s->cluster_size));
- } while (last_table_size != table_size);
+ qcow2_refcount_metadata_size(start_offset / s->cluster_size +
+ additional_clusters,
+ s->cluster_size, s->refcount_order,
+ !exact_size, &total_refblock_count_u64);
+ if (total_refblock_count_u64 > QCOW_MAX_REFTABLE_SIZE) {
+ return -EFBIG;
+ }
+ total_refblock_count = total_refblock_count_u64;
-#ifdef DEBUG_ALLOC2
- fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n",
- s->refcount_table_size, table_size);
-#endif
+ /* Index in the refcount table of the first refcount block to cover the area
+ * of refcount structures we are about to create; we know that
+ * @total_refblock_count can cover @start_offset, so this will definitely
+ * fit into an int. */
+ area_reftable_index = (start_offset / s->cluster_size) /
+ s->refcount_block_size;
- /* Create the new refcount table and blocks */
- uint64_t meta_offset = (blocks_used * s->refcount_block_size) *
- s->cluster_size;
- uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size;
- uint64_t *new_table = g_try_new0(uint64_t, table_size);
- void *new_blocks = g_try_malloc0(blocks_clusters * s->cluster_size);
+ if (exact_size) {
+ table_size = total_refblock_count;
+ } else {
+ table_size = total_refblock_count +
+ DIV_ROUND_UP(total_refblock_count, 2);
+ }
+ /* The qcow2 file can only store the reftable size in number of clusters */
+ table_size = ROUND_UP(table_size, s->cluster_size / sizeof(uint64_t));
+ table_clusters = (table_size * sizeof(uint64_t)) / s->cluster_size;
- assert(table_size > 0 && blocks_clusters > 0);
- if (new_table == NULL || new_blocks == NULL) {
+ if (table_size > QCOW_MAX_REFTABLE_SIZE) {
+ return -EFBIG;
+ }
+
+ new_table = g_try_new0(uint64_t, table_size);
+
+ assert(table_size > 0);
+ if (new_table == NULL) {
ret = -ENOMEM;
- goto fail_table;
+ goto fail;
}
/* Fill the new refcount table */
- memcpy(new_table, s->refcount_table,
- s->refcount_table_size * sizeof(uint64_t));
- new_table[refcount_table_index] = new_block;
+ if (table_size > s->max_refcount_table_index) {
+ /* We're actually growing the reftable */
+ memcpy(new_table, s->refcount_table,
+ (s->max_refcount_table_index + 1) * sizeof(uint64_t));
+ } else {
+ /* Improbable case: We're shrinking the reftable. However, the caller
+ * has assured us that there is only empty space beyond @start_offset,
+ * so we can simply drop all of the refblocks that won't fit into the
+ * new reftable. */
+ memcpy(new_table, s->refcount_table, table_size * sizeof(uint64_t));
+ }
- int i;
- for (i = 0; i < blocks_clusters; i++) {
- new_table[blocks_used + i] = meta_offset + (i * s->cluster_size);
+ if (new_refblock_offset) {
+ assert(new_refblock_index < total_refblock_count);
+ new_table[new_refblock_index] = new_refblock_offset;
}
- /* Fill the refcount blocks */
- uint64_t table_clusters = size_to_clusters(s, table_size * sizeof(uint64_t));
- int block = 0;
- for (i = 0; i < table_clusters + blocks_clusters; i++) {
- s->set_refcount(new_blocks, block++, 1);
+ /* Count how many new refblocks we have to create */
+ additional_refblock_count = 0;
+ for (i = area_reftable_index; i < total_refblock_count; i++) {
+ if (!new_table[i]) {
+ additional_refblock_count++;
+ }
}
+ table_offset = start_offset + additional_refblock_count * s->cluster_size;
+ end_offset = table_offset + table_clusters * s->cluster_size;
+
+ /* Fill the refcount blocks, and create new ones, if necessary */
+ block_offset = start_offset;
+ for (i = area_reftable_index; i < total_refblock_count; i++) {
+ void *refblock_data;
+ uint64_t first_offset_covered;
+
+ /* Reuse an existing refblock if possible, create a new one otherwise */
+ if (new_table[i]) {
+ ret = qcow2_cache_get(bs, s->refcount_block_cache, new_table[i],
+ &refblock_data);
+ if (ret < 0) {
+ goto fail;
+ }
+ } else {
+ ret = qcow2_cache_get_empty(bs, s->refcount_block_cache,
+ block_offset, &refblock_data);
+ if (ret < 0) {
+ goto fail;
+ }
+ memset(refblock_data, 0, s->cluster_size);
+ qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache,
+ refblock_data);
+
+ new_table[i] = block_offset;
+ block_offset += s->cluster_size;
+ }
+
+ /* First host offset covered by this refblock */
+ first_offset_covered = (uint64_t)i * s->refcount_block_size *
+ s->cluster_size;
+ if (first_offset_covered < end_offset) {
+ int j, end_index;
+
+ /* Set the refcount of all of the new refcount structures to 1 */
+
+ if (first_offset_covered < start_offset) {
+ assert(i == area_reftable_index);
+ j = (start_offset - first_offset_covered) / s->cluster_size;
+ assert(j < s->refcount_block_size);
+ } else {
+ j = 0;
+ }
+
+ end_index = MIN((end_offset - first_offset_covered) /
+ s->cluster_size,
+ s->refcount_block_size);
+
+ for (; j < end_index; j++) {
+ /* The caller guaranteed us this space would be empty */
+ assert(s->get_refcount(refblock_data, j) == 0);
+ s->set_refcount(refblock_data, j, 1);
+ }
+
+ qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache,
+ refblock_data);
+ }
+
+ qcow2_cache_put(bs, s->refcount_block_cache, &refblock_data);
+ }
+
+ assert(block_offset == table_offset);
+
/* Write refcount blocks to disk */
BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_BLOCKS);
- ret = bdrv_pwrite_sync(bs->file, meta_offset, new_blocks,
- blocks_clusters * s->cluster_size);
- g_free(new_blocks);
- new_blocks = NULL;
+ ret = qcow2_cache_flush(bs, s->refcount_block_cache);
if (ret < 0) {
- goto fail_table;
+ goto fail;
}
/* Write refcount table to disk */
- for(i = 0; i < table_size; i++) {
+ for (i = 0; i < total_refblock_count; i++) {
cpu_to_be64s(&new_table[i]);
}
@@ -565,10 +677,10 @@ static int alloc_refcount_block(BlockDriverState *bs,
ret = bdrv_pwrite_sync(bs->file, table_offset, new_table,
table_size * sizeof(uint64_t));
if (ret < 0) {
- goto fail_table;
+ goto fail;
}
- for(i = 0; i < table_size; i++) {
+ for (i = 0; i < total_refblock_count; i++) {
be64_to_cpus(&new_table[i]);
}
@@ -584,7 +696,7 @@ static int alloc_refcount_block(BlockDriverState *bs,
offsetof(QCowHeader, refcount_table_offset),
&data, sizeof(data));
if (ret < 0) {
- goto fail_table;
+ goto fail;
}
/* And switch it in memory */
@@ -601,23 +713,10 @@ static int alloc_refcount_block(BlockDriverState *bs,
qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t),
QCOW2_DISCARD_OTHER);
- ret = load_refcount_block(bs, new_block, refcount_block);
- if (ret < 0) {
- return ret;
- }
-
- /* If we were trying to do the initial refcount update for some cluster
- * allocation, we might have used the same clusters to store newly
- * allocated metadata. Make the caller search some new space. */
- return -EAGAIN;
+ return end_offset;
-fail_table:
- g_free(new_blocks);
+fail:
g_free(new_table);
-fail_block:
- if (*refcount_block != NULL) {
- qcow2_cache_put(bs, s->refcount_block_cache, refcount_block);
- }
return ret;
}
diff --git a/block/qcow2.c b/block/qcow2.c
index 47537d0a3f..46edea8dec 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -2559,12 +2559,14 @@ done:
* @clusters: number of clusters to refcount (including data and L1/L2 tables)
* @cluster_size: size of a cluster, in bytes
* @refcount_order: refcount bits power-of-2 exponent
+ * @generous_increase: allow for the refcount table to be 1.5x as large as it
+ * needs to be
*
* Returns: Number of bytes required for refcount blocks and table metadata.
*/
-static int64_t qcow2_refcount_metadata_size(int64_t clusters,
- size_t cluster_size,
- int refcount_order)
+int64_t qcow2_refcount_metadata_size(int64_t clusters, size_t cluster_size,
+ int refcount_order, bool generous_increase,
+ uint64_t *refblock_count)
{
/*
* Every host cluster is reference-counted, including metadata (even
@@ -2587,8 +2589,18 @@ static int64_t qcow2_refcount_metadata_size(int64_t clusters,
blocks = DIV_ROUND_UP(clusters + table + blocks, refcounts_per_block);
table = DIV_ROUND_UP(blocks, blocks_per_table_cluster);
n = clusters + blocks + table;
+
+ if (n == last && generous_increase) {
+ clusters += DIV_ROUND_UP(table, 2);
+ n = 0; /* force another loop */
+ generous_increase = false;
+ }
} while (n != last);
+ if (refblock_count) {
+ *refblock_count = blocks;
+ }
+
return (blocks + table) * cluster_size;
}
@@ -2625,7 +2637,7 @@ static int64_t qcow2_calc_prealloc_size(int64_t total_size,
/* total size of refcount table and blocks */
meta_size += qcow2_refcount_metadata_size(
(meta_size + aligned_total_size) / cluster_size,
- cluster_size, refcount_order);
+ cluster_size, refcount_order, false, NULL);
return meta_size + aligned_total_size;
}
diff --git a/block/qcow2.h b/block/qcow2.h
index 2df05ac8dd..3854080725 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -525,6 +525,10 @@ static inline uint64_t refcount_diff(uint64_t r1, uint64_t r2)
int qcow2_backing_read1(BlockDriverState *bs, QEMUIOVector *qiov,
int64_t sector_num, int nb_sectors);
+int64_t qcow2_refcount_metadata_size(int64_t clusters, size_t cluster_size,
+ int refcount_order, bool generous_increase,
+ uint64_t *refblock_count);
+
int qcow2_mark_dirty(BlockDriverState *bs);
int qcow2_mark_corrupt(BlockDriverState *bs);
int qcow2_mark_consistent(BlockDriverState *bs);
diff --git a/tests/qemu-iotests/044.out b/tests/qemu-iotests/044.out
index 4789a5310e..703cf3dee1 100644
--- a/tests/qemu-iotests/044.out
+++ b/tests/qemu-iotests/044.out
@@ -1,6 +1,6 @@
No errors were found on the image.
7292415/33554432 = 21.73% allocated, 0.00% fragmented, 0.00% compressed clusters
-Image end offset: 4296152064
+Image end offset: 4296217088
.
----------------------------------------------------------------------
Ran 1 tests
generated by cgit v1.2.3 (git 2.26.2) at 2024-12-23 22:22:45 +0000