--- /dev/null
+/*
+ * 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"
+#include "qemu/range.h"
+
+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 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);
+static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index);
+static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index);
+static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index);
+static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index);
+static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index);
+
+static void set_refcount_ro0(void *refcount_array, uint64_t index,
+ uint64_t value);
+static void set_refcount_ro1(void *refcount_array, uint64_t index,
+ uint64_t value);
+static void set_refcount_ro2(void *refcount_array, uint64_t index,
+ uint64_t value);
+static void set_refcount_ro3(void *refcount_array, uint64_t index,
+ uint64_t value);
+static void set_refcount_ro4(void *refcount_array, uint64_t index,
+ uint64_t value);
+static void set_refcount_ro5(void *refcount_array, uint64_t index,
+ uint64_t value);
+static void set_refcount_ro6(void *refcount_array, uint64_t index,
+ uint64_t value);
+
+
+static Qcow2GetRefcountFunc *const get_refcount_funcs[] = {
+ &get_refcount_ro0,
+ &get_refcount_ro1,
+ &get_refcount_ro2,
+ &get_refcount_ro3,
+ &get_refcount_ro4,
+ &get_refcount_ro5,
+ &get_refcount_ro6
+};
+
+static Qcow2SetRefcountFunc *const set_refcount_funcs[] = {
+ &set_refcount_ro0,
+ &set_refcount_ro1,
+ &set_refcount_ro2,
+ &set_refcount_ro3,
+ &set_refcount_ro4,
+ &set_refcount_ro5,
+ &set_refcount_ro6
+};
+
+
+/*********************************************************/
+/* refcount handling */
+
+int qcow2_refcount_init(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ unsigned int refcount_table_size2, i;
+ int ret;
+
+ assert(s->refcount_order >= 0 && s->refcount_order <= 6);
+
+ s->get_refcount = get_refcount_funcs[s->refcount_order];
+ s->set_refcount = set_refcount_funcs[s->refcount_order];
+
+ assert(s->refcount_table_size <= INT_MAX / sizeof(uint64_t));
+ refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
+ s->refcount_table = g_try_malloc(refcount_table_size2);
+
+ if (s->refcount_table_size > 0) {
+ if (s->refcount_table == NULL) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+ BLKDBG_EVENT(bs->file, BLKDBG_REFTABLE_LOAD);
+ ret = bdrv_pread(bs->file, s->refcount_table_offset,
+ s->refcount_table, refcount_table_size2);
+ if (ret < 0) {
+ goto fail;
+ }
+ for(i = 0; i < s->refcount_table_size; i++)
+ be64_to_cpus(&s->refcount_table[i]);
+ }
+ return 0;
+ fail:
+ return ret;
+}
+
+void qcow2_refcount_close(BlockDriverState *bs)
+{
+ BDRVQcowState *s = bs->opaque;
+ g_free(s->refcount_table);
+}
+
+
+static uint64_t get_refcount_ro0(const void *refcount_array, uint64_t index)
+{
+ return (((const uint8_t *)refcount_array)[index / 8] >> (index % 8)) & 0x1;
+}
+
+static void set_refcount_ro0(void *refcount_array, uint64_t index,
+ uint64_t value)
+{
+ assert(!(value >> 1));
+ ((uint8_t *)refcount_array)[index / 8] &= ~(0x1 << (index % 8));
+ ((uint8_t *)refcount_array)[index / 8] |= value << (index % 8);
+}
+
+static uint64_t get_refcount_ro1(const void *refcount_array, uint64_t index)
+{
+ return (((const uint8_t *)refcount_array)[index / 4] >> (2 * (index % 4)))
+ & 0x3;
+}
+
+static void set_refcount_ro1(void *refcount_array, uint64_t index,
+ uint64_t value)
+{
+ assert(!(value >> 2));
+ ((uint8_t *)refcount_array)[index / 4] &= ~(0x3 << (2 * (index % 4)));
+ ((uint8_t *)refcount_array)[index / 4] |= value << (2 * (index % 4));
+}
+
+static uint64_t get_refcount_ro2(const void *refcount_array, uint64_t index)
+{
+ return (((const uint8_t *)refcount_array)[index / 2] >> (4 * (index % 2)))
+ & 0xf;
+}
+
+static void set_refcount_ro2(void *refcount_array, uint64_t index,
+ uint64_t value)
+{
+ assert(!(value >> 4));
+ ((uint8_t *)refcount_array)[index / 2] &= ~(0xf << (4 * (index % 2)));
+ ((uint8_t *)refcount_array)[index / 2] |= value << (4 * (index % 2));
+}
+
+static uint64_t get_refcount_ro3(const void *refcount_array, uint64_t index)
+{
+ return ((const uint8_t *)refcount_array)[index];
+}
+
+static void set_refcount_ro3(void *refcount_array, uint64_t index,
+ uint64_t value)
+{
+ assert(!(value >> 8));
+ ((uint8_t *)refcount_array)[index] = value;
+}
+
+static uint64_t get_refcount_ro4(const void *refcount_array, uint64_t index)
+{
+ return be16_to_cpu(((const uint16_t *)refcount_array)[index]);
+}
+
+static void set_refcount_ro4(void *refcount_array, uint64_t index,
+ uint64_t value)
+{
+ assert(!(value >> 16));
+ ((uint16_t *)refcount_array)[index] = cpu_to_be16(value);
+}
+
+static uint64_t get_refcount_ro5(const void *refcount_array, uint64_t index)
+{
+ return be32_to_cpu(((const uint32_t *)refcount_array)[index]);
+}
+
+static void set_refcount_ro5(void *refcount_array, uint64_t index,
+ uint64_t value)
+{
+ assert(!(value >> 32));
+ ((uint32_t *)refcount_array)[index] = cpu_to_be32(value);
+}
+
+static uint64_t get_refcount_ro6(const void *refcount_array, uint64_t index)
+{
+ return be64_to_cpu(((const uint64_t *)refcount_array)[index]);
+}
+
+static void set_refcount_ro6(void *refcount_array, uint64_t index,
+ uint64_t value)
+{
+ ((uint64_t *)refcount_array)[index] = cpu_to_be64(value);
+}
+
+
+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;
+}
+
+/*
+ * Retrieves the refcount of the cluster given by its index and stores it in
+ * *refcount. Returns 0 on success and -errno on failure.
+ */
+int qcow2_get_refcount(BlockDriverState *bs, int64_t cluster_index,
+ uint64_t *refcount)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t refcount_table_index, block_index;
+ int64_t refcount_block_offset;
+ int ret;
+ void *refcount_block;
+
+ refcount_table_index = cluster_index >> s->refcount_block_bits;
+ if (refcount_table_index >= s->refcount_table_size) {
+ *refcount = 0;
+ return 0;
+ }
+ refcount_block_offset =
+ s->refcount_table[refcount_table_index] & REFT_OFFSET_MASK;
+ if (!refcount_block_offset) {
+ *refcount = 0;
+ return 0;
+ }
+
+ if (offset_into_cluster(s, refcount_block_offset)) {
+ qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#" PRIx64
+ " unaligned (reftable index: %#" PRIx64 ")",
+ refcount_block_offset, refcount_table_index);
+ return -EIO;
+ }
+
+ ret = qcow2_cache_get(bs, s->refcount_block_cache, refcount_block_offset,
+ &refcount_block);
+ if (ret < 0) {
+ return ret;
+ }
+
+ block_index = cluster_index & (s->refcount_block_size - 1);
+ *refcount = s->get_refcount(refcount_block, block_index);
+
+ qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
+
+ 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(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 >> (s->cluster_bits + s->refcount_block_bits);
+ uint64_t block_b = offset_b >> (s->cluster_bits + s->refcount_block_bits);
+
+ 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, void **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->refcount_block_bits;
+
+ 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) {
+ if (offset_into_cluster(s, refcount_block_offset)) {
+ qcow2_signal_corruption(bs, true, -1, -1, "Refblock offset %#"
+ PRIx64 " unaligned (reftable index: "
+ "%#x)", refcount_block_offset,
+ refcount_table_index);
+ return -EIO;
+ }
+
+ return load_refcount_block(bs, refcount_block_offset,
+ 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 potentially doing an initial refcount increase. This means that
+ * some clusters have already been allocated by the caller, but their
+ * refcount isn't accurate yet. If we allocate clusters for metadata, we
+ * need to return -EAGAIN to signal the caller that it needs to restart
+ * the search for free 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,
+ 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) &
+ (s->refcount_block_size - 1);
+ s->set_refcount(*refcount_block, block_index, 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, false,
+ 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,
+ 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(bs, 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;
+
+ /* The new refcount block may be where the caller intended to put its
+ * data, so let it restart the search. */
+ return -EAGAIN;
+ }
+
+ qcow2_cache_put(bs, s->refcount_block_cache, refcount_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; this will be the
+ * basis for calculating the index of the first cluster used for the
+ * self-describing refcount structures which we are about to create.
+ *
+ * Because we reached this point, there cannot be any refcount entries for
+ * cluster_index or higher indices yet. However, because new_block has been
+ * allocated to describe that cluster (and it will assume this role later
+ * on), we cannot use that index; also, new_block may actually have a higher
+ * cluster index than cluster_index, so it needs to be taken into account
+ * here (and 1 needs to be added to its value because that cluster is used).
+ */
+ uint64_t blocks_used = DIV_ROUND_UP(MAX(cluster_index + 1,
+ (new_block >> s->cluster_bits) + 1),
+ s->refcount_block_size);
+
+ if (blocks_used > QCOW_MAX_REFTABLE_SIZE / sizeof(uint64_t)) {
+ return -EFBIG;
+ }
+
+ /* 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 + s->refcount_block_size - 1)
+ / s->refcount_block_size);
+ uint64_t meta_clusters = table_clusters + blocks_clusters;
+
+ last_table_size = table_size;
+ table_size = next_refcount_table_size(s, blocks_used +
+ ((meta_clusters + s->refcount_block_size - 1)
+ / s->refcount_block_size));
+
+ } 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 * 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);
+
+ assert(table_size > 0 && blocks_clusters > 0);
+ if (new_table == NULL || new_blocks == NULL) {
+ ret = -ENOMEM;
+ goto fail_table;
+ }
+
+ /* 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++) {
+ s->set_refcount(new_blocks, block++, 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);
+ new_blocks = NULL;
+ 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. */
+ 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;
+
+fail_table:
+ g_free(new_blocks);
+ g_free(new_table);
+fail_block:
+ if (*refcount_block != NULL) {
+ qcow2_cache_put(bs, s->refcount_block_cache, 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;
+ g_free(p);
+ }
+}
+
+/* XXX: cache several refcount block clusters ? */
+/* @addend is the absolute value of the addend; if @decrease is set, @addend
+ * will be subtracted from the current refcount, otherwise it will be added */
+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)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t start, last, cluster_offset;
+ void *refcount_block = NULL;
+ int64_t old_table_index = -1;
+ int ret;
+
+#ifdef DEBUG_ALLOC2
+ fprintf(stderr, "update_refcount: offset=%" PRId64 " size=%" PRId64
+ " addend=%s%" PRIu64 "\n", offset, length, decrease ? "-" : "",
+ addend);
+#endif
+ if (length < 0) {
+ return -EINVAL;
+ } else if (length == 0) {
+ return 0;
+ }
+
+ if (decrease) {
+ qcow2_cache_set_dependency(bs, s->refcount_block_cache,
+ s->l2_table_cache);
+ }
+
+ start = start_of_cluster(s, offset);
+ last = start_of_cluster(s, offset + length - 1);
+ for(cluster_offset = start; cluster_offset <= last;
+ cluster_offset += s->cluster_size)
+ {
+ int block_index;
+ uint64_t refcount;
+ int64_t cluster_index = cluster_offset >> s->cluster_bits;
+ int64_t table_index = cluster_index >> s->refcount_block_bits;
+
+ /* Load the refcount block and allocate it if needed */
+ if (table_index != old_table_index) {
+ if (refcount_block) {
+ qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
+ }
+ ret = alloc_refcount_block(bs, cluster_index, &refcount_block);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+ old_table_index = table_index;
+
+ qcow2_cache_entry_mark_dirty(bs, s->refcount_block_cache,
+ refcount_block);
+
+ /* we can update the count and save it */
+ block_index = cluster_index & (s->refcount_block_size - 1);
+
+ refcount = s->get_refcount(refcount_block, block_index);
+ if (decrease ? (refcount - addend > refcount)
+ : (refcount + addend < refcount ||
+ refcount + addend > s->refcount_max))
+ {
+ ret = -EINVAL;
+ goto fail;
+ }
+ if (decrease) {
+ refcount -= addend;
+ } else {
+ refcount += addend;
+ }
+ if (refcount == 0 && cluster_index < s->free_cluster_index) {
+ s->free_cluster_index = cluster_index;
+ }
+ s->set_refcount(refcount_block, block_index, 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) {
+ qcow2_cache_put(bs, s->refcount_block_cache, &refcount_block);
+ }
+
+ /*
+ * 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,
+ !decrease, QCOW2_DISCARD_NEVER);
+ (void)dummy;
+ }
+
+ return ret;
+}
+
+/*
+ * Increases or decreases the refcount of a given cluster.
+ *
+ * @addend is the absolute value of the addend; if @decrease is set, @addend
+ * will be subtracted from the current refcount, otherwise it will be added.
+ *
+ * On success 0 is returned; on failure -errno is returned.
+ */
+int qcow2_update_cluster_refcount(BlockDriverState *bs,
+ int64_t cluster_index,
+ uint64_t addend, bool decrease,
+ enum qcow2_discard_type type)
+{
+ BDRVQcowState *s = bs->opaque;
+ int ret;
+
+ ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend,
+ decrease, type);
+ if (ret < 0) {
+ return ret;
+ }
+
+ return 0;
+}
+
+
+
+/*********************************************************/
+/* cluster allocation functions */
+
+
+
+/* return < 0 if error */
+static int64_t alloc_clusters_noref(BlockDriverState *bs, uint64_t size)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t i, nb_clusters, refcount;
+ int ret;
+
+ /* We can't allocate clusters if they may still be queued for discard. */
+ if (s->cache_discards) {
+ qcow2_process_discards(bs, 0);
+ }
+
+ nb_clusters = size_to_clusters(s, size);
+retry:
+ for(i = 0; i < nb_clusters; i++) {
+ uint64_t next_cluster_index = s->free_cluster_index++;
+ ret = qcow2_get_refcount(bs, next_cluster_index, &refcount);
+
+ if (ret < 0) {
+ return ret;
+ } else if (refcount != 0) {
+ goto retry;
+ }
+ }
+
+ /* Make sure that all offsets in the "allocated" range are representable
+ * in an int64_t */
+ if (s->free_cluster_index > 0 &&
+ s->free_cluster_index - 1 > (INT64_MAX >> s->cluster_bits))
+ {
+ return -EFBIG;
+ }
+
+#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, uint64_t size)
+{
+ int64_t offset;
+ int ret;
+
+ BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC);
+ do {
+ offset = alloc_clusters_noref(bs, size);
+ if (offset < 0) {
+ return offset;
+ }
+
+ ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER);
+ } while (ret == -EAGAIN);
+
+ 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, refcount;
+ uint64_t i;
+ int ret;
+
+ assert(nb_clusters >= 0);
+ if (nb_clusters == 0) {
+ return 0;
+ }
+
+ do {
+ /* Check how many clusters there are free */
+ cluster_index = offset >> s->cluster_bits;
+ for(i = 0; i < nb_clusters; i++) {
+ ret = qcow2_get_refcount(bs, cluster_index++, &refcount);
+ if (ret < 0) {
+ return ret;
+ } else if (refcount != 0) {
+ break;
+ }
+ }
+
+ /* And then allocate them */
+ ret = update_refcount(bs, offset, i << s->cluster_bits, 1, false,
+ QCOW2_DISCARD_NEVER);
+ } while (ret == -EAGAIN);
+
+ if (ret < 0) {
+ return ret;
+ }
+
+ 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;
+ size_t free_in_cluster;
+ int ret;
+
+ BLKDBG_EVENT(bs->file, BLKDBG_CLUSTER_ALLOC_BYTES);
+ assert(size > 0 && size <= s->cluster_size);
+ assert(!s->free_byte_offset || offset_into_cluster(s, s->free_byte_offset));
+
+ offset = s->free_byte_offset;
+
+ if (offset) {
+ uint64_t refcount;
+ ret = qcow2_get_refcount(bs, offset >> s->cluster_bits, &refcount);
+ if (ret < 0) {
+ return ret;
+ }
+
+ if (refcount == s->refcount_max) {
+ offset = 0;
+ }
+ }
+
+ free_in_cluster = s->cluster_size - offset_into_cluster(s, offset);
+ do {
+ if (!offset || free_in_cluster < size) {
+ int64_t new_cluster = alloc_clusters_noref(bs, s->cluster_size);
+ if (new_cluster < 0) {
+ return new_cluster;
+ }
+
+ if (!offset || ROUND_UP(offset, s->cluster_size) != new_cluster) {
+ offset = new_cluster;
+ }
+ }
+
+ assert(offset);
+ ret = update_refcount(bs, offset, size, 1, false, QCOW2_DISCARD_NEVER);
+ } while (ret == -EAGAIN);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* The cluster refcount was incremented; 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);
+
+ s->free_byte_offset = offset + size;
+ if (!offset_into_cluster(s, s->free_byte_offset)) {
+ s->free_byte_offset = 0;
+ }
+
+ 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, true, 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:
+ case QCOW2_CLUSTER_ZERO:
+ if (l2_entry & L2E_OFFSET_MASK) {
+ if (offset_into_cluster(s, l2_entry & L2E_OFFSET_MASK)) {
+ qcow2_signal_corruption(bs, false, -1, -1,
+ "Cannot free unaligned cluster %#llx",
+ l2_entry & L2E_OFFSET_MASK);
+ } else {
+ qcow2_free_clusters(bs, l2_entry & L2E_OFFSET_MASK,
+ nb_clusters << s->cluster_bits, type);
+ }
+ }
+ break;
+ case QCOW2_CLUSTER_UNALLOCATED:
+ 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, refcount;
+ bool l1_allocated = false;
+ int64_t old_offset, old_l2_offset;
+ int i, j, l1_modified = 0, nb_csectors;
+ int ret;
+
+ assert(addend >= -1 && addend <= 1);
+
+ 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_try_malloc0(align_offset(l1_size2, 512));
+ if (l1_size2 && l1_table == NULL) {
+ ret = -ENOMEM;
+ goto fail;
+ }
+ l1_allocated = true;
+
+ 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 = false;
+ }
+
+ 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;
+
+ if (offset_into_cluster(s, l2_offset)) {
+ qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#"
+ PRIx64 " unaligned (L1 index: %#x)",
+ l2_offset, i);
+ ret = -EIO;
+ goto fail;
+ }
+
+ 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++) {
+ uint64_t cluster_index;
+
+ offset = be64_to_cpu(l2_table[j]);
+ old_offset = offset;
+ offset &= ~QCOW_OFLAG_COPIED;
+
+ switch (qcow2_get_cluster_type(offset)) {
+ case QCOW2_CLUSTER_COMPRESSED:
+ nb_csectors = ((offset >> s->csize_shift) &
+ s->csize_mask) + 1;
+ if (addend != 0) {
+ ret = update_refcount(bs,
+ (offset & s->cluster_offset_mask) & ~511,
+ nb_csectors * 512, abs(addend), addend < 0,
+ QCOW2_DISCARD_SNAPSHOT);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+ /* compressed clusters are never modified */
+ refcount = 2;
+ break;
+
+ case QCOW2_CLUSTER_NORMAL:
+ case QCOW2_CLUSTER_ZERO:
+ if (offset_into_cluster(s, offset & L2E_OFFSET_MASK)) {
+ qcow2_signal_corruption(bs, true, -1, -1, "Data "
+ "cluster offset %#llx "
+ "unaligned (L2 offset: %#"
+ PRIx64 ", L2 index: %#x)",
+ offset & L2E_OFFSET_MASK,
+ l2_offset, j);
+ ret = -EIO;
+ goto fail;
+ }
+
+ cluster_index = (offset & L2E_OFFSET_MASK) >> s->cluster_bits;
+ if (!cluster_index) {
+ /* unallocated */
+ refcount = 0;
+ break;
+ }
+ if (addend != 0) {
+ ret = qcow2_update_cluster_refcount(bs,
+ cluster_index, abs(addend), addend < 0,
+ QCOW2_DISCARD_SNAPSHOT);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+
+ ret = qcow2_get_refcount(bs, cluster_index, &refcount);
+ if (ret < 0) {
+ goto fail;
+ }
+ break;
+
+ case QCOW2_CLUSTER_UNALLOCATED:
+ refcount = 0;
+ break;
+
+ default:
+ abort();
+ }
+
+ 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(bs, s->l2_table_cache,
+ l2_table);
+ }
+ }
+
+ qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
+
+ if (addend != 0) {
+ ret = qcow2_update_cluster_refcount(bs, l2_offset >>
+ s->cluster_bits,
+ abs(addend), addend < 0,
+ QCOW2_DISCARD_SNAPSHOT);
+ if (ret < 0) {
+ goto fail;
+ }
+ }
+ ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
+ &refcount);
+ if (ret < 0) {
+ 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 */
+
+
+static size_t refcount_array_byte_size(BDRVQcowState *s, uint64_t entries)
+{
+ /* This assertion holds because there is no way we can address more than
+ * 2^(64 - 9) clusters at once (with cluster size 512 = 2^9, and because
+ * offsets have to be representable in bytes); due to every cluster
+ * corresponding to one refcount entry, we are well below that limit */
+ assert(entries < (UINT64_C(1) << (64 - 9)));
+
+ /* Thanks to the assertion this will not overflow, because
+ * s->refcount_order < 7.
+ * (note: x << s->refcount_order == x * s->refcount_bits) */
+ return DIV_ROUND_UP(entries << s->refcount_order, 8);
+}
+
+/**
+ * Reallocates *array so that it can hold new_size entries. *size must contain
+ * the current number of entries in *array. If the reallocation fails, *array
+ * and *size will not be modified and -errno will be returned. If the
+ * reallocation is successful, *array will be set to the new buffer, *size
+ * will be set to new_size and 0 will be returned. The size of the reallocated
+ * refcount array buffer will be aligned to a cluster boundary, and the newly
+ * allocated area will be zeroed.
+ */
+static int realloc_refcount_array(BDRVQcowState *s, void **array,
+ int64_t *size, int64_t new_size)
+{
+ size_t old_byte_size, new_byte_size;
+ void *new_ptr;
+
+ /* Round to clusters so the array can be directly written to disk */
+ old_byte_size = size_to_clusters(s, refcount_array_byte_size(s, *size))
+ * s->cluster_size;
+ new_byte_size = size_to_clusters(s, refcount_array_byte_size(s, new_size))
+ * s->cluster_size;
+
+ if (new_byte_size == old_byte_size) {
+ *size = new_size;
+ return 0;
+ }
+
+ assert(new_byte_size > 0);
+
+ new_ptr = g_try_realloc(*array, new_byte_size);
+ if (!new_ptr) {
+ return -ENOMEM;
+ }
+
+ if (new_byte_size > old_byte_size) {
+ memset((void *)((uintptr_t)new_ptr + old_byte_size), 0,
+ new_byte_size - old_byte_size);
+ }
+
+ *array = new_ptr;
+ *size = new_size;
+
+ return 0;
+}
+
+/*
+ * 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 int inc_refcounts(BlockDriverState *bs,
+ BdrvCheckResult *res,
+ void **refcount_table,
+ int64_t *refcount_table_size,
+ int64_t offset, int64_t size)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t start, last, cluster_offset, k, refcount;
+ int ret;
+
+ if (size <= 0) {
+ return 0;
+ }
+
+ start = start_of_cluster(s, offset);
+ last = start_of_cluster(s, offset + size - 1);
+ for(cluster_offset = start; cluster_offset <= last;
+ cluster_offset += s->cluster_size) {
+ k = cluster_offset >> s->cluster_bits;
+ if (k >= *refcount_table_size) {
+ ret = realloc_refcount_array(s, refcount_table,
+ refcount_table_size, k + 1);
+ if (ret < 0) {
+ res->check_errors++;
+ return ret;
+ }
+ }
+
+ refcount = s->get_refcount(*refcount_table, k);
+ if (refcount == s->refcount_max) {
+ fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
+ "\n", cluster_offset);
+ res->corruptions++;
+ continue;
+ }
+ s->set_refcount(*refcount_table, k, refcount + 1);
+ }
+
+ return 0;
+}
+
+/* Flags for check_refcounts_l1() and check_refcounts_l2() */
+enum {
+ 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,
+ void **refcount_table,
+ int64_t *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, ret;
+
+ /* Read L2 table from disk */
+ l2_size = s->l2_size * sizeof(uint64_t);
+ l2_table = g_malloc(l2_size);
+
+ ret = bdrv_pread(bs->file, l2_offset, l2_table, l2_size);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: I/O error in check_refcounts_l2\n");
+ res->check_errors++;
+ 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;
+ ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
+ l2_entry & ~511, nb_csectors * 512);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ 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:
+ {
+ uint64_t offset = l2_entry & L2E_OFFSET_MASK;
+
+ 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 */
+ ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
+ offset, s->cluster_size);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* Correct offsets are cluster aligned */
+ if (offset_into_cluster(s, offset)) {
+ 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:
+ g_free(l2_table);
+ return ret;
+}
+
+/*
+ * 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,
+ void **refcount_table,
+ int64_t *refcount_table_size,
+ int64_t l1_table_offset, int l1_size,
+ int flags)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t *l1_table = NULL, l2_offset, l1_size2;
+ int i, ret;
+
+ l1_size2 = l1_size * sizeof(uint64_t);
+
+ /* Mark L1 table as used */
+ ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
+ l1_table_offset, l1_size2);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* Read L1 table entries from disk */
+ if (l1_size2 > 0) {
+ l1_table = g_try_malloc(l1_size2);
+ if (l1_table == NULL) {
+ ret = -ENOMEM;
+ res->check_errors++;
+ goto fail;
+ }
+ ret = bdrv_pread(bs->file, l1_table_offset, l1_table, l1_size2);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
+ res->check_errors++;
+ 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) {
+ /* Mark L2 table as used */
+ l2_offset &= L1E_OFFSET_MASK;
+ ret = inc_refcounts(bs, res, refcount_table, refcount_table_size,
+ l2_offset, s->cluster_size);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* L2 tables are cluster aligned */
+ if (offset_into_cluster(s, l2_offset)) {
+ 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:
+ g_free(l1_table);
+ return ret;
+}
+
+/*
+ * Checks the OFLAG_COPIED flag for all L1 and L2 entries.
+ *
+ * This function does not print an error message nor does it increment
+ * check_errors if qcow2_get_refcount fails (this is because such an error will
+ * have been already detected and sufficiently signaled by the calling function
+ * (qcow2_check_refcounts) by the time this function is called).
+ */
+static int check_oflag_copied(BlockDriverState *bs, BdrvCheckResult *res,
+ BdrvCheckMode fix)
+{
+ BDRVQcowState *s = bs->opaque;
+ uint64_t *l2_table = qemu_blockalign(bs, s->cluster_size);
+ int ret;
+ uint64_t refcount;
+ int i, j;
+
+ for (i = 0; i < s->l1_size; i++) {
+ uint64_t l1_entry = s->l1_table[i];
+ uint64_t l2_offset = l1_entry & L1E_OFFSET_MASK;
+ bool l2_dirty = false;
+
+ if (!l2_offset) {
+ continue;
+ }
+
+ ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
+ &refcount);
+ if (ret < 0) {
+ /* don't print message nor increment check_errors */
+ continue;
+ }
+ if ((refcount == 1) != ((l1_entry & QCOW_OFLAG_COPIED) != 0)) {
+ fprintf(stderr, "%s OFLAG_COPIED L2 cluster: l1_index=%d "
+ "l1_entry=%" PRIx64 " refcount=%" PRIu64 "\n",
+ fix & BDRV_FIX_ERRORS ? "Repairing" :
+ "ERROR",
+ i, l1_entry, refcount);
+ if (fix & BDRV_FIX_ERRORS) {
+ s->l1_table[i] = refcount == 1
+ ? l1_entry | QCOW_OFLAG_COPIED
+ : l1_entry & ~QCOW_OFLAG_COPIED;
+ ret = qcow2_write_l1_entry(bs, i);
+ if (ret < 0) {
+ res->check_errors++;
+ goto fail;
+ }
+ res->corruptions_fixed++;
+ } else {
+ res->corruptions++;
+ }
+ }
+
+ ret = bdrv_pread(bs->file, l2_offset, l2_table,
+ s->l2_size * sizeof(uint64_t));
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: Could not read L2 table: %s\n",
+ strerror(-ret));
+ res->check_errors++;
+ goto fail;
+ }
+
+ for (j = 0; j < s->l2_size; j++) {
+ uint64_t l2_entry = be64_to_cpu(l2_table[j]);
+ uint64_t data_offset = l2_entry & L2E_OFFSET_MASK;
+ int cluster_type = qcow2_get_cluster_type(l2_entry);
+
+ if ((cluster_type == QCOW2_CLUSTER_NORMAL) ||
+ ((cluster_type == QCOW2_CLUSTER_ZERO) && (data_offset != 0))) {
+ ret = qcow2_get_refcount(bs,
+ data_offset >> s->cluster_bits,
+ &refcount);
+ if (ret < 0) {
+ /* don't print message nor increment check_errors */
+ continue;
+ }
+ if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
+ fprintf(stderr, "%s OFLAG_COPIED data cluster: "
+ "l2_entry=%" PRIx64 " refcount=%" PRIu64 "\n",
+ fix & BDRV_FIX_ERRORS ? "Repairing" :
+ "ERROR",
+ l2_entry, refcount);
+ if (fix & BDRV_FIX_ERRORS) {
+ l2_table[j] = cpu_to_be64(refcount == 1
+ ? l2_entry | QCOW_OFLAG_COPIED
+ : l2_entry & ~QCOW_OFLAG_COPIED);
+ l2_dirty = true;
+ res->corruptions_fixed++;
+ } else {
+ res->corruptions++;
+ }
+ }
+ }
+ }
+
+ if (l2_dirty) {
+ ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L2,
+ l2_offset, s->cluster_size);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: Could not write L2 table; metadata "
+ "overlap check failed: %s\n", strerror(-ret));
+ res->check_errors++;
+ goto fail;
+ }
+
+ ret = bdrv_pwrite(bs->file, l2_offset, l2_table, s->cluster_size);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR: Could not write L2 table: %s\n",
+ strerror(-ret));
+ res->check_errors++;
+ goto fail;
+ }
+ }
+ }
+
+ ret = 0;
+
+fail:
+ qemu_vfree(l2_table);
+ return ret;
+}
+
+/*
+ * Checks consistency of refblocks and accounts for each refblock in
+ * *refcount_table.
+ */
+static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res,
+ BdrvCheckMode fix, bool *rebuild,
+ void **refcount_table, int64_t *nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t i, size;
+ int ret;
+
+ 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_into_cluster(s, offset)) {
+ fprintf(stderr, "ERROR refcount block %" PRId64 " is not "
+ "cluster aligned; refcount table entry corrupted\n", i);
+ res->corruptions++;
+ *rebuild = true;
+ continue;
+ }
+
+ if (cluster >= *nb_clusters) {
+ fprintf(stderr, "%s refcount block %" PRId64 " is outside image\n",
+ fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i);
+
+ if (fix & BDRV_FIX_ERRORS) {
+ int64_t new_nb_clusters;
+
+ if (offset > INT64_MAX - s->cluster_size) {
+ ret = -EINVAL;
+ goto resize_fail;
+ }
+
+ ret = bdrv_truncate(bs->file, offset + s->cluster_size);
+ if (ret < 0) {
+ goto resize_fail;
+ }
+ size = bdrv_getlength(bs->file);
+ if (size < 0) {
+ ret = size;
+ goto resize_fail;
+ }
+
+ new_nb_clusters = size_to_clusters(s, size);
+ assert(new_nb_clusters >= *nb_clusters);
+
+ ret = realloc_refcount_array(s, refcount_table,
+ nb_clusters, new_nb_clusters);
+ if (ret < 0) {
+ res->check_errors++;
+ return ret;
+ }
+
+ if (cluster >= *nb_clusters) {
+ ret = -EINVAL;
+ goto resize_fail;
+ }
+
+ res->corruptions_fixed++;
+ ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
+ offset, s->cluster_size);
+ if (ret < 0) {
+ return ret;
+ }
+ /* No need to check whether the refcount is now greater than 1:
+ * This area was just allocated and zeroed, so it can only be
+ * exactly 1 after inc_refcounts() */
+ continue;
+
+resize_fail:
+ res->corruptions++;
+ *rebuild = true;
+ fprintf(stderr, "ERROR could not resize image: %s\n",
+ strerror(-ret));
+ } else {
+ res->corruptions++;
+ }
+ continue;
+ }
+
+ if (offset != 0) {
+ ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
+ offset, s->cluster_size);
+ if (ret < 0) {
+ return ret;
+ }
+ if (s->get_refcount(*refcount_table, cluster) != 1) {
+ fprintf(stderr, "ERROR refcount block %" PRId64
+ " refcount=%" PRIu64 "\n", i,
+ s->get_refcount(*refcount_table, cluster));
+ res->corruptions++;
+ *rebuild = true;
+ }
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * Calculates an in-memory refcount table.
+ */
+static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
+ BdrvCheckMode fix, bool *rebuild,
+ void **refcount_table, int64_t *nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t i;
+ QCowSnapshot *sn;
+ int ret;
+
+ if (!*refcount_table) {
+ int64_t old_size = 0;
+ ret = realloc_refcount_array(s, refcount_table,
+ &old_size, *nb_clusters);
+ if (ret < 0) {
+ res->check_errors++;
+ return ret;
+ }
+ }
+
+ /* header */
+ ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
+ 0, s->cluster_size);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* current L1 table */
+ ret = check_refcounts_l1(bs, res, refcount_table, nb_clusters,
+ s->l1_table_offset, s->l1_size, CHECK_FRAG_INFO);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* 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) {
+ return ret;
+ }
+ }
+ ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
+ s->snapshots_offset, s->snapshots_size);
+ if (ret < 0) {
+ return ret;
+ }
+
+ /* refcount data */
+ ret = inc_refcounts(bs, res, refcount_table, nb_clusters,
+ s->refcount_table_offset,
+ s->refcount_table_size * sizeof(uint64_t));
+ if (ret < 0) {
+ return ret;
+ }
+
+ return check_refblocks(bs, res, fix, rebuild, refcount_table, nb_clusters);
+}
+
+/*
+ * Compares the actual reference count for each cluster in the image against the
+ * refcount as reported by the refcount structures on-disk.
+ */
+static void compare_refcounts(BlockDriverState *bs, BdrvCheckResult *res,
+ BdrvCheckMode fix, bool *rebuild,
+ int64_t *highest_cluster,
+ void *refcount_table, int64_t nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t i;
+ uint64_t refcount1, refcount2;
+ int ret;
+
+ for (i = 0, *highest_cluster = 0; i < nb_clusters; i++) {
+ ret = qcow2_get_refcount(bs, i, &refcount1);
+ if (ret < 0) {
+ fprintf(stderr, "Can't get refcount for cluster %" PRId64 ": %s\n",
+ i, strerror(-ret));
+ res->check_errors++;
+ continue;
+ }
+
+ refcount2 = s->get_refcount(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 == 0) {
+ *rebuild = true;
+ } else 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=%" PRIu64
+ " reference=%" PRIu64 "\n",
+ num_fixed != NULL ? "Repairing" :
+ refcount1 < refcount2 ? "ERROR" :
+ "Leaked",
+ i, refcount1, refcount2);
+
+ if (num_fixed) {
+ ret = update_refcount(bs, i << s->cluster_bits, 1,
+ refcount_diff(refcount1, refcount2),
+ refcount1 > refcount2,
+ 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++;
+ }
+ }
+ }
+}
+
+/*
+ * Allocates clusters using an in-memory refcount table (IMRT) in contrast to
+ * the on-disk refcount structures.
+ *
+ * On input, *first_free_cluster tells where to start looking, and need not
+ * actually be a free cluster; the returned offset will not be before that
+ * cluster. On output, *first_free_cluster points to the first gap found, even
+ * if that gap was too small to be used as the returned offset.
+ *
+ * Note that *first_free_cluster is a cluster index whereas the return value is
+ * an offset.
+ */
+static int64_t alloc_clusters_imrt(BlockDriverState *bs,
+ int cluster_count,
+ void **refcount_table,
+ int64_t *imrt_nb_clusters,
+ int64_t *first_free_cluster)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t cluster = *first_free_cluster, i;
+ bool first_gap = true;
+ int contiguous_free_clusters;
+ int ret;
+
+ /* Starting at *first_free_cluster, find a range of at least cluster_count
+ * continuously free clusters */
+ for (contiguous_free_clusters = 0;
+ cluster < *imrt_nb_clusters &&
+ contiguous_free_clusters < cluster_count;
+ cluster++)
+ {
+ if (!s->get_refcount(*refcount_table, cluster)) {
+ contiguous_free_clusters++;
+ if (first_gap) {
+ /* If this is the first free cluster found, update
+ * *first_free_cluster accordingly */
+ *first_free_cluster = cluster;
+ first_gap = false;
+ }
+ } else if (contiguous_free_clusters) {
+ contiguous_free_clusters = 0;
+ }
+ }
+
+ /* If contiguous_free_clusters is greater than zero, it contains the number
+ * of continuously free clusters until the current cluster; the first free
+ * cluster in the current "gap" is therefore
+ * cluster - contiguous_free_clusters */
+
+ /* If no such range could be found, grow the in-memory refcount table
+ * accordingly to append free clusters at the end of the image */
+ if (contiguous_free_clusters < cluster_count) {
+ /* contiguous_free_clusters clusters are already empty at the image end;
+ * we need cluster_count clusters; therefore, we have to allocate
+ * cluster_count - contiguous_free_clusters new clusters at the end of
+ * the image (which is the current value of cluster; note that cluster
+ * may exceed old_imrt_nb_clusters if *first_free_cluster pointed beyond
+ * the image end) */
+ ret = realloc_refcount_array(s, refcount_table, imrt_nb_clusters,
+ cluster + cluster_count
+ - contiguous_free_clusters);
+ if (ret < 0) {
+ return ret;
+ }
+ }
+
+ /* Go back to the first free cluster */
+ cluster -= contiguous_free_clusters;
+ for (i = 0; i < cluster_count; i++) {
+ s->set_refcount(*refcount_table, cluster + i, 1);
+ }
+
+ return cluster << s->cluster_bits;
+}
+
+/*
+ * Creates a new refcount structure based solely on the in-memory information
+ * given through *refcount_table. All necessary allocations will be reflected
+ * in that array.
+ *
+ * On success, the old refcount structure is leaked (it will be covered by the
+ * new refcount structure).
+ */
+static int rebuild_refcount_structure(BlockDriverState *bs,
+ BdrvCheckResult *res,
+ void **refcount_table,
+ int64_t *nb_clusters)
+{
+ BDRVQcowState *s = bs->opaque;
+ int64_t first_free_cluster = 0, reftable_offset = -1, cluster = 0;
+ int64_t refblock_offset, refblock_start, refblock_index;
+ uint32_t reftable_size = 0;
+ uint64_t *on_disk_reftable = NULL;
+ void *on_disk_refblock;
+ int ret = 0;
+ struct {
+ uint64_t reftable_offset;
+ uint32_t reftable_clusters;
+ } QEMU_PACKED reftable_offset_and_clusters;
+
+ qcow2_cache_empty(bs, s->refcount_block_cache);
+
+write_refblocks:
+ for (; cluster < *nb_clusters; cluster++) {
+ if (!s->get_refcount(*refcount_table, cluster)) {
+ continue;
+ }
+
+ refblock_index = cluster >> s->refcount_block_bits;
+ refblock_start = refblock_index << s->refcount_block_bits;
+
+ /* Don't allocate a cluster in a refblock already written to disk */
+ if (first_free_cluster < refblock_start) {
+ first_free_cluster = refblock_start;
+ }
+ refblock_offset = alloc_clusters_imrt(bs, 1, refcount_table,
+ nb_clusters, &first_free_cluster);
+ if (refblock_offset < 0) {
+ fprintf(stderr, "ERROR allocating refblock: %s\n",
+ strerror(-refblock_offset));
+ res->check_errors++;
+ ret = refblock_offset;
+ goto fail;
+ }
+
+ if (reftable_size <= refblock_index) {
+ uint32_t old_reftable_size = reftable_size;
+ uint64_t *new_on_disk_reftable;
+
+ reftable_size = ROUND_UP((refblock_index + 1) * sizeof(uint64_t),
+ s->cluster_size) / sizeof(uint64_t);
+ new_on_disk_reftable = g_try_realloc(on_disk_reftable,
+ reftable_size *
+ sizeof(uint64_t));
+ if (!new_on_disk_reftable) {
+ res->check_errors++;
+ ret = -ENOMEM;
+ goto fail;
+ }
+ on_disk_reftable = new_on_disk_reftable;
+
+ memset(on_disk_reftable + old_reftable_size, 0,
+ (reftable_size - old_reftable_size) * sizeof(uint64_t));
+
+ /* The offset we have for the reftable is now no longer valid;
+ * this will leak that range, but we can easily fix that by running
+ * a leak-fixing check after this rebuild operation */
+ reftable_offset = -1;
+ }
+ on_disk_reftable[refblock_index] = refblock_offset;
+
+ /* If this is apparently the last refblock (for now), try to squeeze the
+ * reftable in */
+ if (refblock_index == (*nb_clusters - 1) >> s->refcount_block_bits &&
+ reftable_offset < 0)
+ {
+ uint64_t reftable_clusters = size_to_clusters(s, reftable_size *
+ sizeof(uint64_t));
+ reftable_offset = alloc_clusters_imrt(bs, reftable_clusters,
+ refcount_table, nb_clusters,
+ &first_free_cluster);
+ if (reftable_offset < 0) {
+ fprintf(stderr, "ERROR allocating reftable: %s\n",
+ strerror(-reftable_offset));
+ res->check_errors++;
+ ret = reftable_offset;
+ goto fail;
+ }
+ }
+
+ ret = qcow2_pre_write_overlap_check(bs, 0, refblock_offset,
+ s->cluster_size);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
+ goto fail;
+ }
+
+ /* The size of *refcount_table is always cluster-aligned, therefore the
+ * write operation will not overflow */
+ on_disk_refblock = (void *)((char *) *refcount_table +
+ refblock_index * s->cluster_size);
+
+ ret = bdrv_write(bs->file, refblock_offset / BDRV_SECTOR_SIZE,
+ on_disk_refblock, s->cluster_sectors);
+ if (ret < 0) {
+ fprintf(stderr, "ERROR writing refblock: %s\n", strerror(-ret));
+ goto fail;
+ }
+
+ /* Go to the end of this refblock */
+ cluster = refblock_start + s->refcount_block_size - 1;
+ }
+
+ if (reftable_offset < 0) {
+ uint64_t post_refblock_start, reftable_clusters;
+
+ post_refblock_start = ROUND_UP(*nb_clusters, s->refcount_block_size);
+ reftable_clusters = size_to_clusters(s,
+ reftable_size * sizeof(uint64_t));
+ /* Not pretty but simple */
+ if (first_free_cluster < post_refblock_start) {
+ first_free_cluster = post_refblock_start;
+ }
+ reftable_offset = alloc_clusters_imrt(bs, reftable_clusters,
+ refcount_table, nb_clusters,
+ &first_free_cluster);
+ if (reftable_offset < 0) {
+ fprintf(stderr, "ERROR allocating reftable: %s\n",
+ strerror(-reftable_offset));
+ res->check_errors++;
+ ret = reftable_offset;
+ goto fail;
+ }
+
+ goto write_refblocks;
+ }
+
+ assert(on_disk_reftable);
+
+ for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) {
+ cpu_to_be64s(&on_disk_reftable[refblock_index]);
+ }
+
+ ret = qcow2_pre_write_overlap_check(bs, 0, reftable_offset,
+ reftable_size * sizeof(uint64_t));
+ if (ret < 0) {
+ fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret));
+ goto fail;
+ }
+
+ assert(reftable_size < INT_MAX / sizeof(uint64_t));
+ ret = bdrv_pwrite(bs->file, reftable_offset, on_disk_reftable,
+ reftable_size * sizeof(uint64_t));
+ if (ret < 0) {
+ fprintf(stderr, "ERROR writing reftable: %s\n", strerror(-ret));
+ goto fail;
+ }
+
+ /* Enter new reftable into the image header */
+ cpu_to_be64w(&reftable_offset_and_clusters.reftable_offset,
+ reftable_offset);
+ cpu_to_be32w(&reftable_offset_and_clusters.reftable_clusters,
+ size_to_clusters(s, reftable_size * sizeof(uint64_t)));
+ ret = bdrv_pwrite_sync(bs->file, offsetof(QCowHeader,
+ refcount_table_offset),
+ &reftable_offset_and_clusters,
+ sizeof(reftable_offset_and_clusters));
+ if (ret < 0) {
+ fprintf(stderr, "ERROR setting reftable: %s\n", strerror(-ret));
+ goto fail;
+ }
+
+ for (refblock_index = 0; refblock_index < reftable_size; refblock_index++) {
+ be64_to_cpus(&on_disk_reftable[refblock_index]);
+ }
+ s->refcount_table = on_disk_reftable;
+ s->refcount_table_offset = reftable_offset;
+ s->refcount_table_size = reftable_size;
+
+ return 0;
+
+fail:
+ g_free(on_disk_reftable);
+ return ret;
+}
+
+/*
+ * 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;
+ BdrvCheckResult pre_compare_res;
+ int64_t size, highest_cluster, nb_clusters;
+ void *refcount_table = NULL;
+ bool rebuild = false;
+ int ret;
+
+ size = bdrv_getlength(bs->file);
+ if (size < 0) {
+ res->check_errors++;
+ return size;
+ }
+
+ nb_clusters = size_to_clusters(s, size);
+ if (nb_clusters > INT_MAX) {
+ res->check_errors++;
+ return -EFBIG;
+ }
+
+ res->bfi.total_clusters =
+ size_to_clusters(s, bs->total_sectors * BDRV_SECTOR_SIZE);
+
+ ret = calculate_refcounts(bs, res, fix, &rebuild, &refcount_table,
+ &nb_clusters);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ /* In case we don't need to rebuild the refcount structure (but want to fix
+ * something), this function is immediately called again, in which case the
+ * result should be ignored */
+ pre_compare_res = *res;
+ compare_refcounts(bs, res, 0, &rebuild, &highest_cluster, refcount_table,
+ nb_clusters);
+
+ if (rebuild && (fix & BDRV_FIX_ERRORS)) {
+ BdrvCheckResult old_res = *res;
+ int fresh_leaks = 0;
+
+ fprintf(stderr, "Rebuilding refcount structure\n");
+ ret = rebuild_refcount_structure(bs, res, &refcount_table,
+ &nb_clusters);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ res->corruptions = 0;
+ res->leaks = 0;
+
+ /* Because the old reftable has been exchanged for a new one the
+ * references have to be recalculated */
+ rebuild = false;
+ memset(refcount_table, 0, refcount_array_byte_size(s, nb_clusters));
+ ret = calculate_refcounts(bs, res, 0, &rebuild, &refcount_table,
+ &nb_clusters);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ if (fix & BDRV_FIX_LEAKS) {
+ /* The old refcount structures are now leaked, fix it; the result
+ * can be ignored, aside from leaks which were introduced by
+ * rebuild_refcount_structure() that could not be fixed */
+ BdrvCheckResult saved_res = *res;
+ *res = (BdrvCheckResult){ 0 };
+
+ compare_refcounts(bs, res, BDRV_FIX_LEAKS, &rebuild,
+ &highest_cluster, refcount_table, nb_clusters);
+ if (rebuild) {
+ fprintf(stderr, "ERROR rebuilt refcount structure is still "
+ "broken\n");
+ }
+
+ /* Any leaks accounted for here were introduced by
+ * rebuild_refcount_structure() because that function has created a
+ * new refcount structure from scratch */
+ fresh_leaks = res->leaks;
+ *res = saved_res;
+ }
+
+ if (res->corruptions < old_res.corruptions) {
+ res->corruptions_fixed += old_res.corruptions - res->corruptions;
+ }
+ if (res->leaks < old_res.leaks) {
+ res->leaks_fixed += old_res.leaks - res->leaks;
+ }
+ res->leaks += fresh_leaks;
+ } else if (fix) {
+ if (rebuild) {
+ fprintf(stderr, "ERROR need to rebuild refcount structures\n");
+ res->check_errors++;
+ ret = -EIO;
+ goto fail;
+ }
+
+ if (res->leaks || res->corruptions) {
+ *res = pre_compare_res;
+ compare_refcounts(bs, res, fix, &rebuild, &highest_cluster,
+ refcount_table, nb_clusters);
+ }
+ }
+
+ /* check OFLAG_COPIED */
+ ret = check_oflag_copied(bs, res, fix);
+ if (ret < 0) {
+ goto fail;
+ }
+
+ res->image_end_offset = (highest_cluster + 1) * s->cluster_size;
+ ret = 0;
+
+fail:
+ g_free(refcount_table);
+
+ return ret;
+}
+
+#define overlaps_with(ofs, sz) \
+ ranges_overlap(offset, size, ofs, sz)
+
+/*
+ * Checks if the given offset into the image file is actually free to use by
+ * looking for overlaps with important metadata sections (L1/L2 tables etc.),
+ * i.e. a sanity check without relying on the refcount tables.
+ *
+ * The ign parameter specifies what checks not to perform (being a bitmask of
+ * QCow2MetadataOverlap values), i.e., what sections to ignore.
+ *
+ * Returns:
+ * - 0 if writing to this offset will not affect the mentioned metadata
+ * - a positive QCow2MetadataOverlap value indicating one overlapping section
+ * - a negative value (-errno) indicating an error while performing a check,
+ * e.g. when bdrv_read failed on QCOW2_OL_INACTIVE_L2
+ */
+int qcow2_check_metadata_overlap(BlockDriverState *bs, int ign, int64_t offset,
+ int64_t size)
+{
+ BDRVQcowState *s = bs->opaque;
+ int chk = s->overlap_check & ~ign;
+ int i, j;
+
+ if (!size) {
+ return 0;
+ }
+
+ if (chk & QCOW2_OL_MAIN_HEADER) {
+ if (offset < s->cluster_size) {
+ return QCOW2_OL_MAIN_HEADER;
+ }
+ }
+
+ /* align range to test to cluster boundaries */
+ size = align_offset(offset_into_cluster(s, offset) + size, s->cluster_size);
+ offset = start_of_cluster(s, offset);
+
+ if ((chk & QCOW2_OL_ACTIVE_L1) && s->l1_size) {
+ if (overlaps_with(s->l1_table_offset, s->l1_size * sizeof(uint64_t))) {
+ return QCOW2_OL_ACTIVE_L1;
+ }
+ }
+
+ if ((chk & QCOW2_OL_REFCOUNT_TABLE) && s->refcount_table_size) {
+ if (overlaps_with(s->refcount_table_offset,
+ s->refcount_table_size * sizeof(uint64_t))) {
+ return QCOW2_OL_REFCOUNT_TABLE;
+ }
+ }
+
+ if ((chk & QCOW2_OL_SNAPSHOT_TABLE) && s->snapshots_size) {
+ if (overlaps_with(s->snapshots_offset, s->snapshots_size)) {
+ return QCOW2_OL_SNAPSHOT_TABLE;
+ }
+ }
+
+ if ((chk & QCOW2_OL_INACTIVE_L1) && s->snapshots) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ if (s->snapshots[i].l1_size &&
+ overlaps_with(s->snapshots[i].l1_table_offset,
+ s->snapshots[i].l1_size * sizeof(uint64_t))) {
+ return QCOW2_OL_INACTIVE_L1;
+ }
+ }
+ }
+
+ if ((chk & QCOW2_OL_ACTIVE_L2) && s->l1_table) {
+ for (i = 0; i < s->l1_size; i++) {
+ if ((s->l1_table[i] & L1E_OFFSET_MASK) &&
+ overlaps_with(s->l1_table[i] & L1E_OFFSET_MASK,
+ s->cluster_size)) {
+ return QCOW2_OL_ACTIVE_L2;
+ }
+ }
+ }
+
+ if ((chk & QCOW2_OL_REFCOUNT_BLOCK) && s->refcount_table) {
+ for (i = 0; i < s->refcount_table_size; i++) {
+ if ((s->refcount_table[i] & REFT_OFFSET_MASK) &&
+ overlaps_with(s->refcount_table[i] & REFT_OFFSET_MASK,
+ s->cluster_size)) {
+ return QCOW2_OL_REFCOUNT_BLOCK;
+ }
+ }
+ }
+
+ if ((chk & QCOW2_OL_INACTIVE_L2) && s->snapshots) {
+ for (i = 0; i < s->nb_snapshots; i++) {
+ uint64_t l1_ofs = s->snapshots[i].l1_table_offset;
+ uint32_t l1_sz = s->snapshots[i].l1_size;
+ uint64_t l1_sz2 = l1_sz * sizeof(uint64_t);
+ uint64_t *l1 = g_try_malloc(l1_sz2);
+ int ret;
+
+ if (l1_sz2 && l1 == NULL) {
+ return -ENOMEM;
+ }
+
+ ret = bdrv_pread(bs->file, l1_ofs, l1, l1_sz2);
+ if (ret < 0) {
+ g_free(l1);
+ return ret;
+ }
+
+ for (j = 0; j < l1_sz; j++) {
+ uint64_t l2_ofs = be64_to_cpu(l1[j]) & L1E_OFFSET_MASK;
+ if (l2_ofs && overlaps_with(l2_ofs, s->cluster_size)) {
+ g_free(l1);
+ return QCOW2_OL_INACTIVE_L2;
+ }
+ }
+
+ g_free(l1);
+ }
+ }
+
+ return 0;
+}
+
+static const char *metadata_ol_names[] = {
+ [QCOW2_OL_MAIN_HEADER_BITNR] = "qcow2_header",
+ [QCOW2_OL_ACTIVE_L1_BITNR] = "active L1 table",
+ [QCOW2_OL_ACTIVE_L2_BITNR] = "active L2 table",
+ [QCOW2_OL_REFCOUNT_TABLE_BITNR] = "refcount table",
+ [QCOW2_OL_REFCOUNT_BLOCK_BITNR] = "refcount block",
+ [QCOW2_OL_SNAPSHOT_TABLE_BITNR] = "snapshot table",
+ [QCOW2_OL_INACTIVE_L1_BITNR] = "inactive L1 table",
+ [QCOW2_OL_INACTIVE_L2_BITNR] = "inactive L2 table",
+};
+
+/*
+ * First performs a check for metadata overlaps (through
+ * qcow2_check_metadata_overlap); if that fails with a negative value (error
+ * while performing a check), that value is returned. If an impending overlap
+ * is detected, the BDS will be made unusable, the qcow2 file marked corrupt
+ * and -EIO returned.
+ *
+ * Returns 0 if there were neither overlaps nor errors while checking for
+ * overlaps; or a negative value (-errno) on error.
+ */
+int qcow2_pre_write_overlap_check(BlockDriverState *bs, int ign, int64_t offset,
+ int64_t size)
+{
+ int ret = qcow2_check_metadata_overlap(bs, ign, offset, size);
+
+ if (ret < 0) {
+ return ret;
+ } else if (ret > 0) {
+ int metadata_ol_bitnr = ctz32(ret);
+ assert(metadata_ol_bitnr < QCOW2_OL_MAX_BITNR);
+
+ qcow2_signal_corruption(bs, true, offset, size, "Preventing invalid "
+ "write on metadata (overlaps with %s)",
+ metadata_ol_names[metadata_ol_bitnr]);
+ return -EIO;
+ }
+
+ return 0;
+}
Code Review / kvmfornfv.git / blobdiff