summaryrefslogtreecommitdiffstats
path: root/contrib/qemu/block/qcow2-refcount.c
diff options
context:
space:
mode:
authorAnand Avati <avati@redhat.com>2013-03-06 01:11:59 -0800
committerAnand Avati <avati@redhat.com>2013-09-03 11:25:33 -0700
commit0d60175bd684cf6a14f750579d82dbd1ba97fcbc (patch)
tree1571f530548196006526442f3fc027cb623bb6fa /contrib/qemu/block/qcow2-refcount.c
parent7dbfbfd3694e02b90e8f3ce509f5279da1523a02 (diff)
contrib/qemu: Import qemu block source code
This qemu block format source code and its minimal dependency files will be used in the next patch to implement a qemu-block format translator. Change-Id: Ic87638972f7ea9b3df84d7a0539512a250c11c1c BUG: 986775 Signed-off-by: Anand Avati <avati@redhat.com> Reviewed-on: http://review.gluster.org/5366 Tested-by: Gluster Build System <jenkins@build.gluster.com> Reviewed-by: Brian Foster <bfoster@redhat.com>
Diffstat (limited to 'contrib/qemu/block/qcow2-refcount.c')
-rw-r--r--contrib/qemu/block/qcow2-refcount.c1374
1 files changed, 1374 insertions, 0 deletions
diff --git a/contrib/qemu/block/qcow2-refcount.c b/contrib/qemu/block/qcow2-refcount.c
new file mode 100644
index 00000000000..1244693f39e
--- /dev/null
+++ b/contrib/qemu/block/qcow2-refcount.c
@@ -0,0 +1,1374 @@
+/*
+ * Block driver for the QCOW version 2 format
+ *
+ * Copyright (c) 2004-2006 Fabrice Bellard
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "qemu-common.h"
+#include "block/block_int.h"
+#include "block/qcow2.h"
+
+static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size);
+static int QEMU_WARN_UNUSED_RESULT update_refcount(BlockDriverState *bs,
+ int64_t offset, int64_t length,
+ int addend, enum qcow2_discard_type type);
+
+
+/*********************************************************/
+/* refcount handling */
+
+int qcow2_refcount_init(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ int ret, refcount_table_size2, i;
+
+ refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
+ s->refcount_table = g_malloc(refcount_table_size2);
+ if (s->refcount_table_size > 0) {
+ BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD);
+ ret = bdrv_pread(bs->file, s->refcount_table_offset,
+ s->refcount_table, refcount_table_size2);
+ if (ret != refcount_table_size2)
+ goto fail;
+ for(i = 0; i < s->refcount_table_size; i++)
+ be64_to_cpus(&s->refcount_table[i]);
+ }
+ return 0;
+ fail:
+ return -ENOMEM;
+}
+
+void qcow2_refcount_close(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ g_free(s->refcount_table);
+}
+
+
+static int load_refcount_block(BlockDriverState *bs,
+ int64_t refcount_block_offset,
+ void **refcount_block)
+{
+ BDRVQcowState *s = bs->opaque;
+ int ret;
+
+ BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_LOAD);
+ ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
+ refcount_block);
+
+ return ret;
+}
+
+/*
+ * Returns the refcount of the cluster given by its index. Any non-negative
+ * return value is the refcount of the cluster, negative values are -errno
+ * and indicate an error.
+ */
+static int get_refcount(BlockDriverState *bs, int64_t cluster_index)
+{
+ BDRVQcowState *s = bs->opaque;
+ int refcount_table_index, block_index;
+ int64_t refcount_block_offset;
+ int ret;
+ uint16_t *refcount_block;
+ uint16_t refcount;
+
+ refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
+ if (refcount_table_index >= s->refcount_table_size)
+ return 0;
+ refcount_block_offset = s->refcount_table[refcount_table_index];
+ if (!refcount_block_offset)
+ return 0;
+
+ ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
+ (void**) &refcount_block);
+ if (ret < 0) {
+ return ret;
+ }
+
+ block_index = cluster_index &
+ ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
+ refcount = be16_to_cpu(refcount_block[block_index]);
+
+ ret = qcow2_cache_put(bs, s->refcount_block_cache,
+ (void**) &refcount_block);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return refcount;
+}
+
+/*
+ * 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(BDRVQcowState *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(BDRVQcowState *s, uint64_t offset_a,
+ uint64_t offset_b)
+{
+ uint64_t block_a = offset_a >> (2 * s->cluster_bits - REFCOUNT_SHIFT);
+ uint64_t block_b = offset_b >> (2 * s->cluster_bits - REFCOUNT_SHIFT);
+
+ return (block_a == block_b);
+}
+
+/*
+ * Loads a refcount block. If it doesn't exist yet, it is allocated first
+ * (including growing the refcount table if needed).
+ *
+ * Returns 0 on success or -errno in error case
+ */
+static int alloc_refcount_block(BlockDriverState *bs,
+ int64_t cluster_index, uint16_t **refcount_block)
+{
+ BDRVQcowState *s = bs->opaque;
+ unsigned int refcount_table_index;
+ int ret;
+
+ BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC);
+
+ /* Find the refcount block for the given cluster */
+ refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
+
+ if (refcount_table_index < s->refcount_table_size) {
+
+ uint64_t refcount_block_offset =
+ s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK;
+
+ /* If it's already there, we're done */
+ if (refcount_block_offset) {
+ return load_refcount_block(bs, refcount_block_offset,
+ (void**) refcount_block);
+ }
+ }
+
+ /*
+ * If we came here, we need to allocate something. Something is at least
+ * a cluster for the new refcount block. It may also include a new refcount
+ * table if the old refcount table is too small.
+ *
+ * Note that allocating clusters here needs some special care:
+ *
+ * - We can't use the normal qcow2_alloc_clusters(), it would try to
+ * increase the refcount and very likely we would end up with an endless
+ * recursion. Instead we must place the refcount blocks in a way that
+ * they can describe them themselves.
+ *
+ * - We need to consider that at this point we are inside update_refcounts
+ * and doing the initial refcount increase. This means that some clusters
+ * have already been allocated by the caller, but their refcount isn't
+ * accurate yet. free_cluster_index tells us where this allocation ends
+ * as long as we don't overwrite it by freeing clusters.
+ *
+ * - alloc_clusters_noref and qcow2_free_clusters may load a different
+ * refcount block into the cache
+ */
+
+ *refcount_block = NULL;
+
+ /* We write to the refcount table, so we might depend on L2 tables */
+ ret = qcow2_cache_flush(bs, s->l2_table_cache);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* Allocate the refcount block itself and mark it as used */
+ int64_t new_block = alloc_clusters_noref(bs, s->cluster_size);
+ if (new_block < 0) {
+ return new_block;
+ }
+
+#ifdef DEBUG_ALLOC2
+ fprintf(stderr, "qcow2: Allocate refcount block %d for %" PRIx64
+ " at %" PRIx64 "\n",
+ refcount_table_index, cluster_index << s->cluster_bits, new_block);
+#endif
+
+ if (in_same_refcount_block(s, new_block, cluster_index << s->cluster_bits)) {
+ /* Zero the new refcount block before updating it */
+ ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block,
+ (void**) refcount_block);
+ if (ret < 0) {
+ goto fail_block;
+ }
+
+ memset(*refcount_block, 0, s->cluster_size);
+
+ /* The block describes itself, need to update the cache */
+ int block_index = (new_block >> s->cluster_bits) &
+ ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
+ (*refcount_block)[block_index] = cpu_to_be16(1);
+ } else {
+ /* Described somewhere else. This can recurse at most twice before we
+ * arrive at a block that describes itself. */
+ ret = update_refcount(bs, new_block, s->cluster_size, 1,
+ QCOW2_DISCARD_NEVER);
+ if (ret < 0) {
+ goto fail_block;
+ }
+
+ ret = qcow2_cache_flush(bs, s->refcount_block_cache);
+ if (ret < 0) {
+ goto fail_block;
+ }
+
+ /* Initialize the new refcount block only after updating its refcount,
+ * update_refcount uses the refcount cache itself */
+ ret = qcow2_cache_get_empty(bs, s->refcount_block_cache, new_block,
+ (void**) refcount_block);
+ if (ret < 0) {
+ goto fail_block;
+ }
+
+ memset(*refcount_block, 0, s->cluster_size);
+ }
+
+ /* Now the new refcount block needs to be written to disk */
+ BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE);
+ qcow2_cache_entry_mark_dirty(s->refcount_block_cache, *refcount_block);
+ ret = qcow2_cache_flush(bs, s->refcount_block_cache);
+ if (ret < 0) {
+ goto fail_block;
+ }
+
+ /* If the refcount table is big enough, just hook the block up there */
+ if (refcount_table_index < s->refcount_table_size) {
+ uint64_t data64 = cpu_to_be64(new_block);
+ BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_HOOKUP);
+ ret = bdrv_pwrite_sync(bs->file,
+ s->refcount_table_offset + refcount_table_index * sizeof(uint64_t),
+ &data64, sizeof(data64));
+ if (ret < 0) {
+ goto fail_block;
+ }
+
+ s->refcount_table[refcount_table_index] = new_block;
+ return 0;
+ }
+
+ ret = qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_block);
+ if (ret < 0) {
+ goto fail_block;
+ }
+
+ /*
+ * If we come here, we need to grow the refcount table. Again, a new
+ * refcount table needs some space and we can't simply allocate to avoid
+ * endless recursion.
+ *
+ * Therefore let's grab new refcount blocks at the end of the image, which
+ * will describe themselves and the new refcount table. This way we can
+ * reference them only in the new table and do the switch to the new
+ * refcount table at once without producing an inconsistent state in
+ * between.
+ */
+ BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_GROW);
+
+ /* Calculate the number of refcount blocks needed so far */
+ uint64_t refcount_block_clusters = 1 << (s->cluster_bits - REFCOUNT_SHIFT);
+ uint64_t blocks_used = (s->free_cluster_index +
+ refcount_block_clusters - 1) / refcount_block_clusters;
+
+ /* 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 +
+ ((table_clusters + refcount_block_clusters - 1)
+ / refcount_block_clusters);
+ uint64_t meta_clusters = table_clusters + blocks_clusters;
+
+ last_table_size = table_size;
+ table_size = next_refcount_table_size(s, blocks_used +
+ ((meta_clusters + refcount_block_clusters - 1)
+ / refcount_block_clusters));
+
+ } while (last_table_size != table_size);
+
+#ifdef DEBUG_ALLOC2
+ fprintf(stderr, "qcow2: Grow refcount table %" PRId32 " => %" PRId64 "\n",
+ s->refcount_table_size, table_size);
+#endif
+
+ /* Create the new refcount table and blocks */
+ uint64_t meta_offset = (blocks_used * refcount_block_clusters) *
+ s->cluster_size;
+ uint64_t table_offset = meta_offset + blocks_clusters * s->cluster_size;
+ uint16_t *new_blocks = g_malloc0(blocks_clusters * s->cluster_size);
+ uint64_t *new_table = g_malloc0(table_size * sizeof(uint64_t));
+
+ assert(meta_offset >= (s->free_cluster_index * s->cluster_size));
+
+ /* 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;
+
+ int i;
+ for (i = 0; i < blocks_clusters; i++) {
+ new_table[blocks_used + i] = meta_offset + (i * s->cluster_size);
+ }
+
+ /* 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++) {
+ new_blocks[block++] = cpu_to_be16(1);
+ }
+
+ /* 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);
+ if (ret < 0) {
+ goto fail_table;
+ }
+
+ /* Write refcount table to disk */
+ for(i = 0; i < table_size; i++) {
+ cpu_to_be64s(&new_table[i]);
+ }
+
+ BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_WRITE_TABLE);
+ ret = bdrv_pwrite_sync(bs->file, table_offset, new_table,
+ table_size * sizeof(uint64_t));
+ if (ret < 0) {
+ goto fail_table;
+ }
+
+ for(i = 0; i < table_size; i++) {
+ be64_to_cpus(&new_table[i]);
+ }
+
+ /* Hook up the new refcount table in the qcow2 header */
+ uint8_t data[12];
+ cpu_to_be64w((uint64_t*)data, table_offset);
+ cpu_to_be32w((uint32_t*)(data + 8), table_clusters);
+ BLKDBG_EVENT(bs->file, BLKDBG_REFBLOCK_ALLOC_SWITCH_TABLE);
+ ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader, refcount_table_offset),
+ data, sizeof(data));
+ if (ret < 0) {
+ goto fail_table;
+ }
+
+ /* And switch it in memory */
+ uint64_t old_table_offset = s->refcount_table_offset;
+ uint64_t old_table_size = s->refcount_table_size;
+
+ g_free(s->refcount_table);
+ s->refcount_table = new_table;
+ s->refcount_table_size = table_size;
+ s->refcount_table_offset = table_offset;
+
+ /* Free old table. Remember, we must not change free_cluster_index */
+ uint64_t old_free_cluster_index = s->free_cluster_index;
+ qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t),
+ QCOW2_DISCARD_OTHER);
+ s->free_cluster_index = old_free_cluster_index;
+
+ ret = load_refcount_block(bs, new_block, (void**) refcount_block);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return 0;
+
+fail_table:
+ g_free(new_table);
+fail_block:
+ if (*refcount_block != NULL) {
+ qcow2_cache_put(bs, s->refcount_block_cache, (void**) refcount_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)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t start, last, cluster_offset;
+ uint16_t *refcount_block = NULL;
+ int64_t old_table_index = -1;
+ int ret;
+
+#ifdef DEBUG_ALLOC2
+ fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64 " addend=%d\n",
+ offset, length, addend);
+#endif
+ if (length < 0) {
+ return -EINVAL;
+ } else if (length == 0) {
+ return 0;
+ }
+
+ if (addend < 0) {
+ qcow2_cache_set_dependency(bs, s->refcount_block_cache,
+ s->l2_table_cache);
+ }
+
+ start = offset & ~(s->cluster_size - 1);
+ last = (offset + length - 1) & ~(s->cluster_size - 1);
+ for(cluster_offset = start; cluster_offset <= last;
+ cluster_offset += s->cluster_size)
+ {
+ int block_index, refcount;
+ int64_t cluster_index = cluster_offset >> s->cluster_bits;
+ int64_t table_index =
+ cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
+
+ /* Load the refcount block and allocate it if needed */
+ if (table_index != old_table_index) {
+ if (refcount_block) {
+ ret = qcow2_cache_put(bs, s->refcount_block_cache,
+ (void**) &refcount_block);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+
+ ret = alloc_refcount_block(bs, cluster_index, &refcount_block);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+ old_table_index = table_index;
+
+ qcow2_cache_entry_mark_dirty(s->refcount_block_cache, refcount_block);
+
+ /* we can update the count and save it */
+ block_index = cluster_index &
+ ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
+
+ refcount = be16_to_cpu(refcount_block[block_index]);
+ refcount += addend;
+ if (refcount < 0 || refcount > 0xffff) {
+ ret = -EINVAL;
+ goto fail;
+ }
+ if (refcount == 0 && cluster_index < s->free_cluster_index) {
+ s->free_cluster_index = cluster_index;
+ }
+ refcount_block[block_index] = cpu_to_be16(refcount);
+
+ if (refcount == 0 && s->discard_passthrough[type]) {
+ 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;
+ wret = qcow2_cache_put(bs, s->refcount_block_cache,
+ (void**) &refcount_block);
+ if (wret < 0) {
+ return ret < 0 ? ret : wret;
+ }
+ }
+
+ /*
+ * Try do undo any updates if an error is returned (This may succeed in
+ * some cases like ENOSPC for allocating a new refcount block)
+ */
+ if (ret < 0) {
+ int dummy;
+ dummy = update_refcount(bs, offset, cluster_offset - offset, -addend,
+ QCOW2_DISCARD_NEVER);
+ (void)dummy;
+ }
+
+ return ret;
+}
+
+/*
+ * Increases or decreases the refcount of a given cluster by one.
+ * addend must be 1 or -1.
+ *
+ * If the return value is non-negative, it is the new refcount of the cluster.
+ * If it is negative, it is -errno and indicates an error.
+ */
+static int update_cluster_refcount(BlockDriverState *bs,
+ int64_t cluster_index,
+ int addend,
+ enum qcow2_discard_type type)
+{
+ BDRVQcowState *s = bs->opaque;
+ int ret;
+
+ ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend,
+ type);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return get_refcount(bs, cluster_index);
+}
+
+
+
+/*********************************************************/
+/* cluster allocation functions */
+
+
+
+/* return < 0 if error */
+static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size)
+{
+ BDRVQcowState *s = bs->opaque;
+ int i, nb_clusters, refcount;
+
+ nb_clusters = size_to_clusters(s, size);
+retry:
+ for(i = 0; i < nb_clusters; i++) {
+ int64_t next_cluster_index = s->free_cluster_index++;
+ refcount = get_refcount(bs, next_cluster_index);
+
+ if (refcount < 0) {
+ return refcount;
+ } else if (refcount != 0) {
+ goto retry;
+ }
+ }
+#ifdef DEBUG_ALLOC2
+ fprintf(stderr, "alloc_clusters: size=%" PRId64 " -> %" PRId64 "\n",
+ size,
+ (s->free_cluster_index - nb_clusters) << s->cluster_bits);
+#endif
+ return (s->free_cluster_index - nb_clusters) << s->cluster_bits;
+}
+
+int64_t qcow2_alloc_clusters(BlockDriverState *bs, int64_t size)
+{
+ int64_t offset;
+ int ret;
+
+ BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC);
+ offset = alloc_clusters_noref(bs, size);
+ if (offset < 0) {
+ return offset;
+ }
+
+ ret = update_refcount(bs, offset, size, 1, QCOW2_DISCARD_NEVER);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return offset;
+}
+
+int qcow2_alloc_clusters_at(BlockDriverState *bs, uint64_t offset,
+ int nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t cluster_index;
+ uint64_t old_free_cluster_index;
+ int i, refcount, ret;
+
+ /* Check how many clusters there are free */
+ cluster_index = offset >> s->cluster_bits;
+ for(i = 0; i < nb_clusters; i++) {
+ refcount = get_refcount(bs, cluster_index++);
+
+ if (refcount < 0) {
+ return refcount;
+ } else if (refcount != 0) {
+ break;
+ }
+ }
+
+ /* And then allocate them */
+ old_free_cluster_index = s->free_cluster_index;
+ s->free_cluster_index = cluster_index + i;
+
+ ret = update_refcount(bs, offset, i << s->cluster_bits, 1,
+ QCOW2_DISCARD_NEVER);
+ if (ret < 0) {
+ return ret;
+ }
+
+ s->free_cluster_index = old_free_cluster_index;
+
+ return i;
+}
+
+/* only used to allocate compressed sectors. We try to allocate
+ contiguous sectors. size must be <= cluster_size */
+int64_t qcow2_alloc_bytes(BlockDriverState *bs, int size)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t offset, cluster_offset;
+ int free_in_cluster;
+
+ BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES);
+ assert(size > 0 && size <= s->cluster_size);
+ if (s->free_byte_offset == 0) {
+ offset = qcow2_alloc_clusters(bs, s->cluster_size);
+ if (offset < 0) {
+ return offset;
+ }
+ s->free_byte_offset = offset;
+ }
+ redo:
+ free_in_cluster = s->cluster_size -
+ (s->free_byte_offset & (s->cluster_size - 1));
+ if (size <= free_in_cluster) {
+ /* enough space in current cluster */
+ offset = s->free_byte_offset;
+ s->free_byte_offset += size;
+ free_in_cluster -= size;
+ if (free_in_cluster == 0)
+ s->free_byte_offset = 0;
+ if ((offset & (s->cluster_size - 1)) != 0)
+ update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
+ QCOW2_DISCARD_NEVER);
+ } else {
+ offset = qcow2_alloc_clusters(bs, s->cluster_size);
+ if (offset < 0) {
+ return offset;
+ }
+ cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1);
+ if ((cluster_offset + s->cluster_size) == offset) {
+ /* we are lucky: contiguous data */
+ offset = s->free_byte_offset;
+ update_cluster_refcount(bs, offset >> s->cluster_bits, 1,
+ QCOW2_DISCARD_NEVER);
+ s->free_byte_offset += size;
+ } else {
+ s->free_byte_offset = offset;
+ goto redo;
+ }
+ }
+
+ /* The cluster refcount was incremented, either by qcow2_alloc_clusters()
+ * or explicitly by update_cluster_refcount(). Refcount blocks must be
+ * flushed before the caller's L2 table updates.
+ */
+ qcow2_cache_set_dependency(bs, s->l2_table_cache, s->refcount_block_cache);
+ return offset;
+}
+
+void qcow2_free_clusters(BlockDriverState *bs,
+ int64_t offset, int64_t size,
+ enum qcow2_discard_type type)
+{
+ int ret;
+
+ BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_FREE);
+ ret = update_refcount(bs, offset, size, -1, type);
+ if (ret < 0) {
+ fprintf(stderr, "qcow2_free_clusters failed: %s\n", strerror(-ret));
+ /* TODO Remember the clusters to free them later and avoid leaking */
+ }
+}
+
+/*
+ * Free a cluster using its L2 entry (handles clusters of all types, e.g.
+ * normal cluster, compressed cluster, etc.)
+ */
+void qcow2_free_any_clusters(BlockDriverState *bs, uint64_t l2_entry,
+ int nb_clusters, enum qcow2_discard_type type)
+{
+ BDRVQcowState *s = bs->opaque;
+
+ switch (qcow2_get_cluster_type(l2_entry)) {
+ case QCOW2_CLUSTER_COMPRESSED:
+ {
+ int nb_csectors;
+ nb_csectors = ((l2_entry >> s->csize_shift) &
+ s->csize_mask) + 1;
+ qcow2_free_clusters(bs,
+ (l2_entry & s->cluster_offset_mask) & ~511,
+ nb_csectors * 512, type);
+ }
+ break;
+ case QCOW2_CLUSTER_NORMAL:
+ qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK,
+ nb_clusters << s->cluster_bits, type);
+ break;
+ case QCOW2_CLUSTER_UNALLOCATED:
+ case QCOW2_CLUSTER_ZERO:
+ break;
+ default:
+ abort();
+ }
+}
+
+
+
+/*********************************************************/
+/* snapshots and image creation */
+
+
+
+/* update the refcounts of snapshots and the copied flag */
+int qcow2_update_snapshot_refcount(BlockDriverState *bs,
+ int64_t l1_table_offset, int l1_size, int addend)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated;
+ int64_t old_offset, old_l2_offset;
+ int i, j, l1_modified = 0, nb_csectors, refcount;
+ int ret;
+
+ l2_table = NULL;
+ 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! */
+ if (l1_table_offset != s->l1_table_offset) {
+ l1_table = g_malloc0(align_offset(l1_size2, 512));
+ l1_allocated = 1;
+
+ ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ for(i = 0;i < l1_size; i++)
+ be64_to_cpus(&l1_table[i]);
+ } else {
+ assert(l1_size == s->l1_size);
+ l1_table = s->l1_table;
+ l1_allocated = 0;
+ }
+
+ for(i = 0; i < l1_size; i++) {
+ l2_offset = l1_table[i];
+ if (l2_offset) {
+ old_l2_offset = l2_offset;
+ l2_offset &= L1E_OFFSET_MASK;
+
+ ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
+ (void**) &l2_table);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ for(j = 0; j < s->l2_size; j++) {
+ offset = be64_to_cpu(l2_table[j]);
+ if (offset != 0) {
+ old_offset = offset;
+ offset &= ~QCOW_OFLAG_COPIED;
+ if (offset & QCOW_OFLAG_COMPRESSED) {
+ nb_csectors = ((offset >> s->csize_shift) &
+ s->csize_mask) + 1;
+ if (addend != 0) {
+ int ret;
+ ret = update_refcount(bs,
+ (offset & s->cluster_offset_mask) & ~511,
+ nb_csectors * 512, addend,
+ QCOW2_DISCARD_SNAPSHOT);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+ /* compressed clusters are never modified */
+ refcount = 2;
+ } else {
+ uint64_t cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;
+ if (addend != 0) {
+ refcount = update_cluster_refcount(bs, cluster_index, addend,
+ QCOW2_DISCARD_SNAPSHOT);
+ } else {
+ refcount = get_refcount(bs, cluster_index);
+ }
+
+ if (refcount < 0) {
+ ret = refcount;
+ goto fail;
+ }
+ }
+
+ if (refcount == 1) {
+ offset |= QCOW_OFLAG_COPIED;
+ }
+ if (offset != old_offset) {
+ if (addend > 0) {
+ qcow2_cache_set_dependency(bs, s->l2_table_cache,
+ s->refcount_block_cache);
+ }
+ l2_table[j] = cpu_to_be64(offset);
+ qcow2_cache_entry_mark_dirty(s->l2_table_cache, l2_table);
+ }
+ }
+ }
+
+ ret = qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
+ if (ret < 0) {
+ goto fail;
+ }
+
+
+ if (addend != 0) {
+ refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend,
+ QCOW2_DISCARD_SNAPSHOT);
+ } else {
+ refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
+ }
+ if (refcount < 0) {
+ ret = refcount;
+ goto fail;
+ } else if (refcount == 1) {
+ l2_offset |= QCOW_OFLAG_COPIED;
+ }
+ if (l2_offset != old_l2_offset) {
+ l1_table[i] = l2_offset;
+ l1_modified = 1;
+ }
+ }
+ }
+
+ ret = bdrv_flush(bs);
+fail:
+ if (l2_table) {
+ 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++) {
+ cpu_to_be64s(&l1_table[i]);
+ }
+
+ ret = bdrv_pwrite_sync(bs->file, l1_table_offset, l1_table, l1_size2);
+
+ for (i = 0; i < l1_size; i++) {
+ be64_to_cpus(&l1_table[i]);
+ }
+ }
+ if (l1_allocated)
+ g_free(l1_table);
+ return ret;
+}
+
+
+
+
+/*********************************************************/
+/* refcount checking functions */
+
+
+
+/*
+ * Increases the refcount for a range of clusters in a given refcount table.
+ * This is used to construct a temporary refcount table out of L1 and L2 tables
+ * which can be compared the the refcount table saved in the image.
+ *
+ * Modifies the number of errors in res.
+ */
+static void inc_refcounts(BlockDriverState *bs,
+ BdrvCheckResult *res,
+ uint16_t *refcount_table,
+ int refcount_table_size,
+ int64_t offset, int64_t size)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t start, last, cluster_offset;
+ int k;
+
+ if (size <= 0)
+ return;
+
+ start = offset & ~(s->cluster_size - 1);
+ last = (offset + size - 1) & ~(s->cluster_size - 1);
+ for(cluster_offset = start; cluster_offset <= last;
+ cluster_offset += s->cluster_size) {
+ k = cluster_offset >> s->cluster_bits;
+ if (k < 0) {
+ fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n",
+ cluster_offset);
+ res->corruptions++;
+ } else if (k >= refcount_table_size) {
+ fprintf(stderr, "Warning: cluster offset=0x%" PRIx64 " is after "
+ "the end of the image file, can't properly check refcounts.\n",
+ cluster_offset);
+ res->check_errors++;
+ } else {
+ if (++refcount_table[k] == 0) {
+ fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
+ "\n", cluster_offset);
+ res->corruptions++;
+ }
+ }
+ }
+}
+
+/* Flags for check_refcounts_l1() and check_refcounts_l2() */
+enum {
+ CHECK_OFLAG_COPIED = 0x1, /* check QCOW_OFLAG_COPIED matches refcount */
+ CHECK_FRAG_INFO = 0x2, /* update BlockFragInfo counters */
+};
+
+/*
+ * Increases the refcount in the given refcount table for the all clusters
+ * referenced in the L2 table. While doing so, performs some checks on L2
+ * entries.
+ *
+ * Returns the number of errors found by the checks or -errno if an internal
+ * error occurred.
+ */
+static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
+ uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset,
+ int flags)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t *l2_table, l2_entry;
+ uint64_t next_contiguous_offset = 0;
+ int i, l2_size, nb_csectors, refcount;
+
+ /* Read L2 table from disk */
+ l2_size = s->l2_size * sizeof(uint64_t);
+ l2_table = g_malloc(l2_size);
+
+ if (bdrv_pread(bs->file, l2_offset, l2_table, l2_size) != l2_size)
+ goto fail;
+
+ /* Do the actual checks */
+ for(i = 0; i < s->l2_size; i++) {
+ l2_entry = be64_to_cpu(l2_table[i]);
+
+ switch (qcow2_get_cluster_type(l2_entry)) {
+ case QCOW2_CLUSTER_COMPRESSED:
+ /* Compressed clusters don't have QCOW_OFLAG_COPIED */
+ if (l2_entry & QCOW_OFLAG_COPIED) {
+ fprintf(stderr, "ERROR: cluster %" PRId64 ": "
+ "copied flag must never be set for compressed "
+ "clusters\n", l2_entry >> s->cluster_bits);
+ l2_entry &= ~QCOW_OFLAG_COPIED;
+ res->corruptions++;
+ }
+
+ /* Mark cluster as used */
+ nb_csectors = ((l2_entry >> s->csize_shift) &
+ s->csize_mask) + 1;
+ l2_entry &= s->cluster_offset_mask;
+ inc_refcounts(bs, res, refcount_table, refcount_table_size,
+ l2_entry & ~511, nb_csectors * 512);
+
+ if (flags & CHECK_FRAG_INFO) {
+ res->bfi.allocated_clusters++;
+ res->bfi.compressed_clusters++;
+
+ /* Compressed clusters are fragmented by nature. Since they
+ * take up sub-sector space but we only have sector granularity
+ * I/O we need to re-read the same sectors even for adjacent
+ * compressed clusters.
+ */
+ res->bfi.fragmented_clusters++;
+ }
+ break;
+
+ case QCOW2_CLUSTER_ZERO:
+ if ((l2_entry & L2E_OFFSET_MASK) == 0) {
+ break;
+ }
+ /* fall through */
+
+ case QCOW2_CLUSTER_NORMAL:
+ {
+ /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
+ uint64_t offset = l2_entry & L2E_OFFSET_MASK;
+
+ if (flags & CHECK_OFLAG_COPIED) {
+ refcount = get_refcount(bs, offset >> s->cluster_bits);
+ if (refcount < 0) {
+ fprintf(stderr, "Can't get refcount for offset %"
+ PRIx64 ": %s\n", l2_entry, strerror(-refcount));
+ goto fail;
+ }
+ if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
+ fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
+ PRIx64 " refcount=%d\n", l2_entry, refcount);
+ res->corruptions++;
+ }
+ }
+
+ if (flags & CHECK_FRAG_INFO) {
+ res->bfi.allocated_clusters++;
+ if (next_contiguous_offset &&
+ offset != next_contiguous_offset) {
+ res->bfi.fragmented_clusters++;
+ }
+ next_contiguous_offset = offset + s->cluster_size;
+ }
+
+ /* Mark cluster as used */
+ inc_refcounts(bs, res, refcount_table,refcount_table_size,
+ offset, s->cluster_size);
+
+ /* Correct offsets are cluster aligned */
+ if (offset & (s->cluster_size - 1)) {
+ fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
+ "properly aligned; L2 entry corrupted.\n", offset);
+ res->corruptions++;
+ }
+ break;
+ }
+
+ case QCOW2_CLUSTER_UNALLOCATED:
+ break;
+
+ default:
+ abort();
+ }
+ }
+
+ g_free(l2_table);
+ return 0;
+
+fail:
+ fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n");
+ g_free(l2_table);
+ return -EIO;
+}
+
+/*
+ * Increases the refcount for the L1 table, its L2 tables and all referenced
+ * clusters in the given refcount table. While doing so, performs some checks
+ * on L1 and L2 entries.
+ *
+ * Returns the number of errors found by the checks or -errno if an internal
+ * error occurred.
+ */
+static int check_refcounts_l1(BlockDriverState *bs,
+ BdrvCheckResult *res,
+ uint16_t *refcount_table,
+ int refcount_table_size,
+ int64_t l1_table_offset, int l1_size,
+ int flags)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t *l1_table, l2_offset, l1_size2;
+ int i, refcount, ret;
+
+ l1_size2 = l1_size * sizeof(uint64_t);
+
+ /* Mark L1 table as used */
+ inc_refcounts(bs, res, refcount_table, refcount_table_size,
+ l1_table_offset, l1_size2);
+
+ /* Read L1 table entries from disk */
+ if (l1_size2 == 0) {
+ l1_table = NULL;
+ } else {
+ l1_table = g_malloc(l1_size2);
+ if (bdrv_pread(bs->file, l1_table_offset,
+ l1_table, l1_size2) != l1_size2)
+ goto fail;
+ for(i = 0;i < l1_size; i++)
+ be64_to_cpus(&l1_table[i]);
+ }
+
+ /* Do the actual checks */
+ for(i = 0; i < l1_size; i++) {
+ l2_offset = l1_table[i];
+ if (l2_offset) {
+ /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
+ if (flags & CHECK_OFLAG_COPIED) {
+ refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED)
+ >> s->cluster_bits);
+ if (refcount < 0) {
+ fprintf(stderr, "Can't get refcount for l2_offset %"
+ PRIx64 ": %s\n", l2_offset, strerror(-refcount));
+ goto fail;
+ }
+ if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) {
+ fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64
+ " refcount=%d\n", l2_offset, refcount);
+ res->corruptions++;
+ }
+ }
+
+ /* Mark L2 table as used */
+ l2_offset &= L1E_OFFSET_MASK;
+ inc_refcounts(bs, res, refcount_table, refcount_table_size,
+ l2_offset, s->cluster_size);
+
+ /* L2 tables are cluster aligned */
+ if (l2_offset & (s->cluster_size - 1)) {
+ fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not "
+ "cluster aligned; L1 entry corrupted\n", l2_offset);
+ res->corruptions++;
+ }
+
+ /* Process and check L2 entries */
+ ret = check_refcounts_l2(bs, res, refcount_table,
+ refcount_table_size, l2_offset, flags);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+ }
+ g_free(l1_table);
+ return 0;
+
+fail:
+ fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
+ res->check_errors++;
+ g_free(l1_table);
+ return -EIO;
+}
+
+/*
+ * Checks an image for refcount consistency.
+ *
+ * Returns 0 if no errors are found, the number of errors in case the image is
+ * detected as corrupted, and -errno when an internal error occurred.
+ */
+int qcow2_check_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
+ BdrvCheckMode fix)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t size, i, highest_cluster;
+ int nb_clusters, refcount1, refcount2;
+ QCowSnapshot *sn;
+ uint16_t *refcount_table;
+ int ret;
+
+ size = bdrv_getlength(bs->file);
+ nb_clusters = size_to_clusters(s, size);
+ refcount_table = g_malloc0(nb_clusters * sizeof(uint16_t));
+
+ res->bfi.total_clusters =
+ size_to_clusters(s, bs->total_sectors * BDRV_SECTOR_SIZE);
+
+ /* header */
+ inc_refcounts(bs, res, refcount_table, nb_clusters,
+ 0, s->cluster_size);
+
+ /* current L1 table */
+ ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
+ s->l1_table_offset, s->l1_size,
+ CHECK_OFLAG_COPIED | CHECK_FRAG_INFO);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* snapshots */
+ for(i = 0; i < s->nb_snapshots; i++) {
+ sn = s->snapshots + i;
+ ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
+ sn->l1_table_offset, sn->l1_size, 0);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+ inc_refcounts(bs, res, refcount_table, nb_clusters,
+ s->snapshots_offset, s->snapshots_size);
+
+ /* refcount data */
+ inc_refcounts(bs, res, refcount_table, nb_clusters,
+ s->refcount_table_offset,
+ s->refcount_table_size * sizeof(uint64_t));
+
+ for(i = 0; i < s->refcount_table_size; i++) {
+ uint64_t offset, cluster;
+ offset = s->refcount_table[i];
+ cluster = offset >> s->cluster_bits;
+
+ /* Refcount blocks are cluster aligned */
+ if (offset & (s->cluster_size - 1)) {
+ fprintf(stderr, "ERROR refcount block %" PRId64 " is not "
+ "cluster aligned; refcount table entry corrupted\n", i);
+ res->corruptions++;
+ continue;
+ }
+
+ if (cluster >= nb_clusters) {
+ fprintf(stderr, "ERROR refcount block %" PRId64
+ " is outside image\n", i);
+ res->corruptions++;
+ continue;
+ }
+
+ if (offset != 0) {
+ inc_refcounts(bs, res, refcount_table, nb_clusters,
+ offset, s->cluster_size);
+ if (refcount_table[cluster] != 1) {
+ fprintf(stderr, "ERROR refcount block %" PRId64
+ " refcount=%d\n",
+ i, refcount_table[cluster]);
+ res->corruptions++;
+ }
+ }
+ }
+
+ /* compare ref counts */
+ for (i = 0, highest_cluster = 0; i < nb_clusters; i++) {
+ refcount1 = get_refcount(bs, i);
+ if (refcount1 < 0) {
+ fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n",
+ i, strerror(-refcount1));
+ res->check_errors++;
+ continue;
+ }
+
+ refcount2 = refcount_table[i];
+
+ if (refcount1 > 0 || refcount2 > 0) {
+ highest_cluster = i;
+ }
+
+ if (refcount1 != refcount2) {
+
+ /* Check if we're allowed to fix the mismatch */
+ int *num_fixed = NULL;
+ if (refcount1 > refcount2 && (fix & BDRV_FIX_LEAKS)) {
+ num_fixed = &res->leaks_fixed;
+ } else if (refcount1 < refcount2 && (fix & BDRV_FIX_ERRORS)) {
+ num_fixed = &res->corruptions_fixed;
+ }
+
+ fprintf(stderr, "%s cluster %" PRId64 " refcount=%d reference=%d\n",
+ num_fixed != NULL ? "Repairing" :
+ refcount1 < refcount2 ? "ERROR" :
+ "Leaked",
+ i, refcount1, refcount2);
+
+ if (num_fixed) {
+ ret = update_refcount(bs, i << s->cluster_bits, 1,
+ refcount2 - refcount1,
+ QCOW2_DISCARD_ALWAYS);
+ if (ret >= 0) {
+ (*num_fixed)++;
+ continue;
+ }
+ }
+
+ /* And if we couldn't, print an error */
+ if (refcount1 < refcount2) {
+ res->corruptions++;
+ } else {
+ res->leaks++;
+ }
+ }
+ }
+
+ res->image_end_offset = (highest_cluster + 1) * s->cluster_size;
+ ret = 0;
+
+fail:
+ g_free(refcount_table);
+
+ return ret;
+}
+