Adding qemu as a submodule of KVMFORNFV

This Patch includes the changes to add qemu as a submodule to
kvmfornfv repo and make use of the updated latest qemu for the
execution of all testcase
Change-Id: I1280af507a857675c7f81d30c95255635667bdd7
Signed-off-by:RajithaY<rajithax.yerrumsetty@intel.com>

1 files changed, 0 insertions, 1899 deletions

diff --git a/qemu/block/qcow2-cluster.c b/qemu/block/qcow2-cluster.c
deleted file mode 100644
index 31ecc1030..000000000
--- a/qemu/block/qcow2-cluster.c
+++ /dev/null
@@ -1,1899 +0,0 @@
-/*
- * 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/osdep.h"
-#include <zlib.h>
-
-#include "qapi/error.h"
-#include "qemu-common.h"
-#include "block/block_int.h"
-#include "block/qcow2.h"
-#include "trace.h"
-
-int qcow2_grow_l1_table(BlockDriverState *bs, uint64_t min_size,
-                        bool exact_size)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int new_l1_size2, ret, i;
-    uint64_t *new_l1_table;
-    int64_t old_l1_table_offset, old_l1_size;
-    int64_t new_l1_table_offset, new_l1_size;
-    uint8_t data[12];
-
-    if (min_size <= s->l1_size)
-        return 0;
-
-    /* Do a sanity check on min_size before trying to calculate new_l1_size
-     * (this prevents overflows during the while loop for the calculation of
-     * new_l1_size) */
-    if (min_size > INT_MAX / sizeof(uint64_t)) {
-        return -EFBIG;
-    }
-
-    if (exact_size) {
-        new_l1_size = min_size;
-    } else {
-        /* Bump size up to reduce the number of times we have to grow */
-        new_l1_size = s->l1_size;
-        if (new_l1_size == 0) {
-            new_l1_size = 1;
-        }
-        while (min_size > new_l1_size) {
-            new_l1_size = (new_l1_size * 3 + 1) / 2;
-        }
-    }
-
-    if (new_l1_size > INT_MAX / sizeof(uint64_t)) {
-        return -EFBIG;
-    }
-
-#ifdef DEBUG_ALLOC2
-    fprintf(stderr, "grow l1_table from %d to %" PRId64 "\n",
-            s->l1_size, new_l1_size);
-#endif
-
-    new_l1_size2 = sizeof(uint64_t) * new_l1_size;
-    new_l1_table = qemu_try_blockalign(bs->file->bs,
-                                       align_offset(new_l1_size2, 512));
-    if (new_l1_table == NULL) {
-        return -ENOMEM;
-    }
-    memset(new_l1_table, 0, align_offset(new_l1_size2, 512));
-
-    memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
-
-    /* write new table (align to cluster) */
-    BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ALLOC_TABLE);
-    new_l1_table_offset = qcow2_alloc_clusters(bs, new_l1_size2);
-    if (new_l1_table_offset < 0) {
-        qemu_vfree(new_l1_table);
-        return new_l1_table_offset;
-    }
-
-    ret = qcow2_cache_flush(bs, s->refcount_block_cache);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    /* the L1 position has not yet been updated, so these clusters must
-     * indeed be completely free */
-    ret = qcow2_pre_write_overlap_check(bs, 0, new_l1_table_offset,
-                                        new_l1_size2);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_WRITE_TABLE);
-    for(i = 0; i < s->l1_size; i++)
-        new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
-    ret = bdrv_pwrite_sync(bs->file->bs, new_l1_table_offset,
-                           new_l1_table, new_l1_size2);
-    if (ret < 0)
-        goto fail;
-    for(i = 0; i < s->l1_size; i++)
-        new_l1_table[i] = be64_to_cpu(new_l1_table[i]);
-
-    /* set new table */
-    BLKDBG_EVENT(bs->file, BLKDBG_L1_GROW_ACTIVATE_TABLE);
-    cpu_to_be32w((uint32_t*)data, new_l1_size);
-    stq_be_p(data + 4, new_l1_table_offset);
-    ret = bdrv_pwrite_sync(bs->file->bs, offsetof(QCowHeader, l1_size),
-                           data, sizeof(data));
-    if (ret < 0) {
-        goto fail;
-    }
-    qemu_vfree(s->l1_table);
-    old_l1_table_offset = s->l1_table_offset;
-    s->l1_table_offset = new_l1_table_offset;
-    s->l1_table = new_l1_table;
-    old_l1_size = s->l1_size;
-    s->l1_size = new_l1_size;
-    qcow2_free_clusters(bs, old_l1_table_offset, old_l1_size * sizeof(uint64_t),
-                        QCOW2_DISCARD_OTHER);
-    return 0;
- fail:
-    qemu_vfree(new_l1_table);
-    qcow2_free_clusters(bs, new_l1_table_offset, new_l1_size2,
-                        QCOW2_DISCARD_OTHER);
-    return ret;
-}
-
-/*
- * l2_load
- *
- * Loads a L2 table into memory. If the table is in the cache, the cache
- * is used; otherwise the L2 table is loaded from the image file.
- *
- * Returns a pointer to the L2 table on success, or NULL if the read from
- * the image file failed.
- */
-
-static int l2_load(BlockDriverState *bs, uint64_t l2_offset,
-    uint64_t **l2_table)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int ret;
-
-    ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset, (void**) l2_table);
-
-    return ret;
-}
-
-/*
- * Writes one sector of the L1 table to the disk (can't update single entries
- * and we really don't want bdrv_pread to perform a read-modify-write)
- */
-#define L1_ENTRIES_PER_SECTOR (512 / 8)
-int qcow2_write_l1_entry(BlockDriverState *bs, int l1_index)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t buf[L1_ENTRIES_PER_SECTOR] = { 0 };
-    int l1_start_index;
-    int i, ret;
-
-    l1_start_index = l1_index & ~(L1_ENTRIES_PER_SECTOR - 1);
-    for (i = 0; i < L1_ENTRIES_PER_SECTOR && l1_start_index + i < s->l1_size;
-         i++)
-    {
-        buf[i] = cpu_to_be64(s->l1_table[l1_start_index + i]);
-    }
-
-    ret = qcow2_pre_write_overlap_check(bs, QCOW2_OL_ACTIVE_L1,
-            s->l1_table_offset + 8 * l1_start_index, sizeof(buf));
-    if (ret < 0) {
-        return ret;
-    }
-
-    BLKDBG_EVENT(bs->file, BLKDBG_L1_UPDATE);
-    ret = bdrv_pwrite_sync(bs->file->bs,
-                           s->l1_table_offset + 8 * l1_start_index,
-                           buf, sizeof(buf));
-    if (ret < 0) {
-        return ret;
-    }
-
-    return 0;
-}
-
-/*
- * l2_allocate
- *
- * Allocate a new l2 entry in the file. If l1_index points to an already
- * used entry in the L2 table (i.e. we are doing a copy on write for the L2
- * table) copy the contents of the old L2 table into the newly allocated one.
- * Otherwise the new table is initialized with zeros.
- *
- */
-
-static int l2_allocate(BlockDriverState *bs, int l1_index, uint64_t **table)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t old_l2_offset;
-    uint64_t *l2_table = NULL;
-    int64_t l2_offset;
-    int ret;
-
-    old_l2_offset = s->l1_table[l1_index];
-
-    trace_qcow2_l2_allocate(bs, l1_index);
-
-    /* allocate a new l2 entry */
-
-    l2_offset = qcow2_alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
-    if (l2_offset < 0) {
-        ret = l2_offset;
-        goto fail;
-    }
-
-    ret = qcow2_cache_flush(bs, s->refcount_block_cache);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    /* allocate a new entry in the l2 cache */
-
-    trace_qcow2_l2_allocate_get_empty(bs, l1_index);
-    ret = qcow2_cache_get_empty(bs, s->l2_table_cache, l2_offset, (void**) table);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    l2_table = *table;
-
-    if ((old_l2_offset & L1E_OFFSET_MASK) == 0) {
-        /* if there was no old l2 table, clear the new table */
-        memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
-    } else {
-        uint64_t* old_table;
-
-        /* if there was an old l2 table, read it from the disk */
-        BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_COW_READ);
-        ret = qcow2_cache_get(bs, s->l2_table_cache,
-            old_l2_offset & L1E_OFFSET_MASK,
-            (void**) &old_table);
-        if (ret < 0) {
-            goto fail;
-        }
-
-        memcpy(l2_table, old_table, s->cluster_size);
-
-        qcow2_cache_put(bs, s->l2_table_cache, (void **) &old_table);
-    }
-
-    /* write the l2 table to the file */
-    BLKDBG_EVENT(bs->file, BLKDBG_L2_ALLOC_WRITE);
-
-    trace_qcow2_l2_allocate_write_l2(bs, l1_index);
-    qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table);
-    ret = qcow2_cache_flush(bs, s->l2_table_cache);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    /* update the L1 entry */
-    trace_qcow2_l2_allocate_write_l1(bs, l1_index);
-    s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
-    ret = qcow2_write_l1_entry(bs, l1_index);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    *table = l2_table;
-    trace_qcow2_l2_allocate_done(bs, l1_index, 0);
-    return 0;
-
-fail:
-    trace_qcow2_l2_allocate_done(bs, l1_index, ret);
-    if (l2_table != NULL) {
-        qcow2_cache_put(bs, s->l2_table_cache, (void**) table);
-    }
-    s->l1_table[l1_index] = old_l2_offset;
-    if (l2_offset > 0) {
-        qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
-                            QCOW2_DISCARD_ALWAYS);
-    }
-    return ret;
-}
-
-/*
- * Checks how many clusters in a given L2 table are contiguous in the image
- * file. As soon as one of the flags in the bitmask stop_flags changes compared
- * to the first cluster, the search is stopped and the cluster is not counted
- * as contiguous. (This allows it, for example, to stop at the first compressed
- * cluster which may require a different handling)
- */
-static int count_contiguous_clusters(int nb_clusters, int cluster_size,
-        uint64_t *l2_table, uint64_t stop_flags)
-{
-    int i;
-    uint64_t mask = stop_flags | L2E_OFFSET_MASK | QCOW_OFLAG_COMPRESSED;
-    uint64_t first_entry = be64_to_cpu(l2_table[0]);
-    uint64_t offset = first_entry & mask;
-
-    if (!offset)
-        return 0;
-
-    assert(qcow2_get_cluster_type(first_entry) == QCOW2_CLUSTER_NORMAL);
-
-    for (i = 0; i < nb_clusters; i++) {
-        uint64_t l2_entry = be64_to_cpu(l2_table[i]) & mask;
-        if (offset + (uint64_t) i * cluster_size != l2_entry) {
-            break;
-        }
-    }
-
-	return i;
-}
-
-static int count_contiguous_clusters_by_type(int nb_clusters,
-                                             uint64_t *l2_table,
-                                             int wanted_type)
-{
-    int i;
-
-    for (i = 0; i < nb_clusters; i++) {
-        int type = qcow2_get_cluster_type(be64_to_cpu(l2_table[i]));
-
-        if (type != wanted_type) {
-            break;
-        }
-    }
-
-    return i;
-}
-
-/* The crypt function is compatible with the linux cryptoloop
-   algorithm for < 4 GB images. NOTE: out_buf == in_buf is
-   supported */
-int qcow2_encrypt_sectors(BDRVQcow2State *s, int64_t sector_num,
-                          uint8_t *out_buf, const uint8_t *in_buf,
-                          int nb_sectors, bool enc,
-                          Error **errp)
-{
-    union {
-        uint64_t ll[2];
-        uint8_t b[16];
-    } ivec;
-    int i;
-    int ret;
-
-    for(i = 0; i < nb_sectors; i++) {
-        ivec.ll[0] = cpu_to_le64(sector_num);
-        ivec.ll[1] = 0;
-        if (qcrypto_cipher_setiv(s->cipher,
-                                 ivec.b, G_N_ELEMENTS(ivec.b),
-                                 errp) < 0) {
-            return -1;
-        }
-        if (enc) {
-            ret = qcrypto_cipher_encrypt(s->cipher,
-                                         in_buf,
-                                         out_buf,
-                                         512,
-                                         errp);
-        } else {
-            ret = qcrypto_cipher_decrypt(s->cipher,
-                                         in_buf,
-                                         out_buf,
-                                         512,
-                                         errp);
-        }
-        if (ret < 0) {
-            return -1;
-        }
-        sector_num++;
-        in_buf += 512;
-        out_buf += 512;
-    }
-    return 0;
-}
-
-static int coroutine_fn copy_sectors(BlockDriverState *bs,
-                                     uint64_t start_sect,
-                                     uint64_t cluster_offset,
-                                     int n_start, int n_end)
-{
-    BDRVQcow2State *s = bs->opaque;
-    QEMUIOVector qiov;
-    struct iovec iov;
-    int n, ret;
-
-    n = n_end - n_start;
-    if (n <= 0) {
-        return 0;
-    }
-
-    iov.iov_len = n * BDRV_SECTOR_SIZE;
-    iov.iov_base = qemu_try_blockalign(bs, iov.iov_len);
-    if (iov.iov_base == NULL) {
-        return -ENOMEM;
-    }
-
-    qemu_iovec_init_external(&qiov, &iov, 1);
-
-    BLKDBG_EVENT(bs->file, BLKDBG_COW_READ);
-
-    if (!bs->drv) {
-        ret = -ENOMEDIUM;
-        goto out;
-    }
-
-    /* Call .bdrv_co_readv() directly instead of using the public block-layer
-     * interface.  This avoids double I/O throttling and request tracking,
-     * which can lead to deadlock when block layer copy-on-read is enabled.
-     */
-    ret = bs->drv->bdrv_co_readv(bs, start_sect + n_start, n, &qiov);
-    if (ret < 0) {
-        goto out;
-    }
-
-    if (bs->encrypted) {
-        Error *err = NULL;
-        assert(s->cipher);
-        if (qcow2_encrypt_sectors(s, start_sect + n_start,
-                                  iov.iov_base, iov.iov_base, n,
-                                  true, &err) < 0) {
-            ret = -EIO;
-            error_free(err);
-            goto out;
-        }
-    }
-
-    ret = qcow2_pre_write_overlap_check(bs, 0,
-            cluster_offset + n_start * BDRV_SECTOR_SIZE, n * BDRV_SECTOR_SIZE);
-    if (ret < 0) {
-        goto out;
-    }
-
-    BLKDBG_EVENT(bs->file, BLKDBG_COW_WRITE);
-    ret = bdrv_co_writev(bs->file->bs, (cluster_offset >> 9) + n_start, n,
-                         &qiov);
-    if (ret < 0) {
-        goto out;
-    }
-
-    ret = 0;
-out:
-    qemu_vfree(iov.iov_base);
-    return ret;
-}
-
-
-/*
- * get_cluster_offset
- *
- * For a given offset of the disk image, find the cluster offset in
- * qcow2 file. The offset is stored in *cluster_offset.
- *
- * on entry, *num is the number of contiguous sectors we'd like to
- * access following offset.
- *
- * on exit, *num is the number of contiguous sectors we can read.
- *
- * Returns the cluster type (QCOW2_CLUSTER_*) on success, -errno in error
- * cases.
- */
-int qcow2_get_cluster_offset(BlockDriverState *bs, uint64_t offset,
-    int *num, uint64_t *cluster_offset)
-{
-    BDRVQcow2State *s = bs->opaque;
-    unsigned int l2_index;
-    uint64_t l1_index, l2_offset, *l2_table;
-    int l1_bits, c;
-    unsigned int index_in_cluster, nb_clusters;
-    uint64_t nb_available, nb_needed;
-    int ret;
-
-    index_in_cluster = (offset >> 9) & (s->cluster_sectors - 1);
-    nb_needed = *num + index_in_cluster;
-
-    l1_bits = s->l2_bits + s->cluster_bits;
-
-    /* compute how many bytes there are between the offset and
-     * the end of the l1 entry
-     */
-
-    nb_available = (1ULL << l1_bits) - (offset & ((1ULL << l1_bits) - 1));
-
-    /* compute the number of available sectors */
-
-    nb_available = (nb_available >> 9) + index_in_cluster;
-
-    if (nb_needed > nb_available) {
-        nb_needed = nb_available;
-    }
-    assert(nb_needed <= INT_MAX);
-
-    *cluster_offset = 0;
-
-    /* seek to the l2 offset in the l1 table */
-
-    l1_index = offset >> l1_bits;
-    if (l1_index >= s->l1_size) {
-        ret = QCOW2_CLUSTER_UNALLOCATED;
-        goto out;
-    }
-
-    l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
-    if (!l2_offset) {
-        ret = QCOW2_CLUSTER_UNALLOCATED;
-        goto out;
-    }
-
-    if (offset_into_cluster(s, l2_offset)) {
-        qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
-                                " unaligned (L1 index: %#" PRIx64 ")",
-                                l2_offset, l1_index);
-        return -EIO;
-    }
-
-    /* load the l2 table in memory */
-
-    ret = l2_load(bs, l2_offset, &l2_table);
-    if (ret < 0) {
-        return ret;
-    }
-
-    /* find the cluster offset for the given disk offset */
-
-    l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
-    *cluster_offset = be64_to_cpu(l2_table[l2_index]);
-
-    /* nb_needed <= INT_MAX, thus nb_clusters <= INT_MAX, too */
-    nb_clusters = size_to_clusters(s, nb_needed << 9);
-
-    ret = qcow2_get_cluster_type(*cluster_offset);
-    switch (ret) {
-    case QCOW2_CLUSTER_COMPRESSED:
-        /* Compressed clusters can only be processed one by one */
-        c = 1;
-        *cluster_offset &= L2E_COMPRESSED_OFFSET_SIZE_MASK;
-        break;
-    case QCOW2_CLUSTER_ZERO:
-        if (s->qcow_version < 3) {
-            qcow2_signal_corruption(bs, true, -1, -1, "Zero cluster entry found"
-                                    " in pre-v3 image (L2 offset: %#" PRIx64
-                                    ", L2 index: %#x)", l2_offset, l2_index);
-            ret = -EIO;
-            goto fail;
-        }
-        c = count_contiguous_clusters_by_type(nb_clusters, &l2_table[l2_index],
-                                              QCOW2_CLUSTER_ZERO);
-        *cluster_offset = 0;
-        break;
-    case QCOW2_CLUSTER_UNALLOCATED:
-        /* how many empty clusters ? */
-        c = count_contiguous_clusters_by_type(nb_clusters, &l2_table[l2_index],
-                                              QCOW2_CLUSTER_UNALLOCATED);
-        *cluster_offset = 0;
-        break;
-    case QCOW2_CLUSTER_NORMAL:
-        /* how many allocated clusters ? */
-        c = count_contiguous_clusters(nb_clusters, s->cluster_size,
-                &l2_table[l2_index], QCOW_OFLAG_ZERO);
-        *cluster_offset &= L2E_OFFSET_MASK;
-        if (offset_into_cluster(s, *cluster_offset)) {
-            qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset %#"
-                                    PRIx64 " unaligned (L2 offset: %#" PRIx64
-                                    ", L2 index: %#x)", *cluster_offset,
-                                    l2_offset, l2_index);
-            ret = -EIO;
-            goto fail;
-        }
-        break;
-    default:
-        abort();
-    }
-
-    qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
-
-    nb_available = (c * s->cluster_sectors);
-
-out:
-    if (nb_available > nb_needed)
-        nb_available = nb_needed;
-
-    *num = nb_available - index_in_cluster;
-
-    return ret;
-
-fail:
-    qcow2_cache_put(bs, s->l2_table_cache, (void **)&l2_table);
-    return ret;
-}
-
-/*
- * get_cluster_table
- *
- * for a given disk offset, load (and allocate if needed)
- * the l2 table.
- *
- * the l2 table offset in the qcow2 file and the cluster index
- * in the l2 table are given to the caller.
- *
- * Returns 0 on success, -errno in failure case
- */
-static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
-                             uint64_t **new_l2_table,
-                             int *new_l2_index)
-{
-    BDRVQcow2State *s = bs->opaque;
-    unsigned int l2_index;
-    uint64_t l1_index, l2_offset;
-    uint64_t *l2_table = NULL;
-    int ret;
-
-    /* seek to the l2 offset in the l1 table */
-
-    l1_index = offset >> (s->l2_bits + s->cluster_bits);
-    if (l1_index >= s->l1_size) {
-        ret = qcow2_grow_l1_table(bs, l1_index + 1, false);
-        if (ret < 0) {
-            return ret;
-        }
-    }
-
-    assert(l1_index < s->l1_size);
-    l2_offset = s->l1_table[l1_index] & L1E_OFFSET_MASK;
-    if (offset_into_cluster(s, l2_offset)) {
-        qcow2_signal_corruption(bs, true, -1, -1, "L2 table offset %#" PRIx64
-                                " unaligned (L1 index: %#" PRIx64 ")",
-                                l2_offset, l1_index);
-        return -EIO;
-    }
-
-    /* seek the l2 table of the given l2 offset */
-
-    if (s->l1_table[l1_index] & QCOW_OFLAG_COPIED) {
-        /* load the l2 table in memory */
-        ret = l2_load(bs, l2_offset, &l2_table);
-        if (ret < 0) {
-            return ret;
-        }
-    } else {
-        /* First allocate a new L2 table (and do COW if needed) */
-        ret = l2_allocate(bs, l1_index, &l2_table);
-        if (ret < 0) {
-            return ret;
-        }
-
-        /* Then decrease the refcount of the old table */
-        if (l2_offset) {
-            qcow2_free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t),
-                                QCOW2_DISCARD_OTHER);
-        }
-    }
-
-    /* find the cluster offset for the given disk offset */
-
-    l2_index = (offset >> s->cluster_bits) & (s->l2_size - 1);
-
-    *new_l2_table = l2_table;
-    *new_l2_index = l2_index;
-
-    return 0;
-}
-
-/*
- * alloc_compressed_cluster_offset
- *
- * For a given offset of the disk image, return cluster offset in
- * qcow2 file.
- *
- * If the offset is not found, allocate a new compressed cluster.
- *
- * Return the cluster offset if successful,
- * Return 0, otherwise.
- *
- */
-
-uint64_t qcow2_alloc_compressed_cluster_offset(BlockDriverState *bs,
-                                               uint64_t offset,
-                                               int compressed_size)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int l2_index, ret;
-    uint64_t *l2_table;
-    int64_t cluster_offset;
-    int nb_csectors;
-
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
-    if (ret < 0) {
-        return 0;
-    }
-
-    /* Compression can't overwrite anything. Fail if the cluster was already
-     * allocated. */
-    cluster_offset = be64_to_cpu(l2_table[l2_index]);
-    if (cluster_offset & L2E_OFFSET_MASK) {
-        qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
-        return 0;
-    }
-
-    cluster_offset = qcow2_alloc_bytes(bs, compressed_size);
-    if (cluster_offset < 0) {
-        qcow2_cache_put(bs, s->l2_table_cache, (void**) &l2_table);
-        return 0;
-    }
-
-    nb_csectors = ((cluster_offset + compressed_size - 1) >> 9) -
-                  (cluster_offset >> 9);
-
-    cluster_offset |= QCOW_OFLAG_COMPRESSED |
-                      ((uint64_t)nb_csectors << s->csize_shift);
-
-    /* update L2 table */
-
-    /* compressed clusters never have the copied flag */
-
-    BLKDBG_EVENT(bs->file, BLKDBG_L2_UPDATE_COMPRESSED);
-    qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table);
-    l2_table[l2_index] = cpu_to_be64(cluster_offset);
-    qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-
-    return cluster_offset;
-}
-
-static int perform_cow(BlockDriverState *bs, QCowL2Meta *m, Qcow2COWRegion *r)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int ret;
-
-    if (r->nb_sectors == 0) {
-        return 0;
-    }
-
-    qemu_co_mutex_unlock(&s->lock);
-    ret = copy_sectors(bs, m->offset / BDRV_SECTOR_SIZE, m->alloc_offset,
-                       r->offset / BDRV_SECTOR_SIZE,
-                       r->offset / BDRV_SECTOR_SIZE + r->nb_sectors);
-    qemu_co_mutex_lock(&s->lock);
-
-    if (ret < 0) {
-        return ret;
-    }
-
-    /*
-     * Before we update the L2 table to actually point to the new cluster, we
-     * need to be sure that the refcounts have been increased and COW was
-     * handled.
-     */
-    qcow2_cache_depends_on_flush(s->l2_table_cache);
-
-    return 0;
-}
-
-int qcow2_alloc_cluster_link_l2(BlockDriverState *bs, QCowL2Meta *m)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int i, j = 0, l2_index, ret;
-    uint64_t *old_cluster, *l2_table;
-    uint64_t cluster_offset = m->alloc_offset;
-
-    trace_qcow2_cluster_link_l2(qemu_coroutine_self(), m->nb_clusters);
-    assert(m->nb_clusters > 0);
-
-    old_cluster = g_try_new(uint64_t, m->nb_clusters);
-    if (old_cluster == NULL) {
-        ret = -ENOMEM;
-        goto err;
-    }
-
-    /* copy content of unmodified sectors */
-    ret = perform_cow(bs, m, &m->cow_start);
-    if (ret < 0) {
-        goto err;
-    }
-
-    ret = perform_cow(bs, m, &m->cow_end);
-    if (ret < 0) {
-        goto err;
-    }
-
-    /* Update L2 table. */
-    if (s->use_lazy_refcounts) {
-        qcow2_mark_dirty(bs);
-    }
-    if (qcow2_need_accurate_refcounts(s)) {
-        qcow2_cache_set_dependency(bs, s->l2_table_cache,
-                                   s->refcount_block_cache);
-    }
-
-    ret = get_cluster_table(bs, m->offset, &l2_table, &l2_index);
-    if (ret < 0) {
-        goto err;
-    }
-    qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table);
-
-    assert(l2_index + m->nb_clusters <= s->l2_size);
-    for (i = 0; i < m->nb_clusters; i++) {
-        /* if two concurrent writes happen to the same unallocated cluster
-	 * each write allocates separate cluster and writes data concurrently.
-	 * The first one to complete updates l2 table with pointer to its
-	 * cluster the second one has to do RMW (which is done above by
-	 * copy_sectors()), update l2 table with its cluster pointer and free
-	 * old cluster. This is what this loop does */
-        if(l2_table[l2_index + i] != 0)
-            old_cluster[j++] = l2_table[l2_index + i];
-
-        l2_table[l2_index + i] = cpu_to_be64((cluster_offset +
-                    (i << s->cluster_bits)) | QCOW_OFLAG_COPIED);
-     }
-
-
-    qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-
-    /*
-     * If this was a COW, we need to decrease the refcount of the old cluster.
-     *
-     * Don't discard clusters that reach a refcount of 0 (e.g. compressed
-     * clusters), the next write will reuse them anyway.
-     */
-    if (j != 0) {
-        for (i = 0; i < j; i++) {
-            qcow2_free_any_clusters(bs, be64_to_cpu(old_cluster[i]), 1,
-                                    QCOW2_DISCARD_NEVER);
-        }
-    }
-
-    ret = 0;
-err:
-    g_free(old_cluster);
-    return ret;
- }
-
-/*
- * Returns the number of contiguous clusters that can be used for an allocating
- * write, but require COW to be performed (this includes yet unallocated space,
- * which must copy from the backing file)
- */
-static int count_cow_clusters(BDRVQcow2State *s, int nb_clusters,
-    uint64_t *l2_table, int l2_index)
-{
-    int i;
-
-    for (i = 0; i < nb_clusters; i++) {
-        uint64_t l2_entry = be64_to_cpu(l2_table[l2_index + i]);
-        int cluster_type = qcow2_get_cluster_type(l2_entry);
-
-        switch(cluster_type) {
-        case QCOW2_CLUSTER_NORMAL:
-            if (l2_entry & QCOW_OFLAG_COPIED) {
-                goto out;
-            }
-            break;
-        case QCOW2_CLUSTER_UNALLOCATED:
-        case QCOW2_CLUSTER_COMPRESSED:
-        case QCOW2_CLUSTER_ZERO:
-            break;
-        default:
-            abort();
-        }
-    }
-
-out:
-    assert(i <= nb_clusters);
-    return i;
-}
-
-/*
- * Check if there already is an AIO write request in flight which allocates
- * the same cluster. In this case we need to wait until the previous
- * request has completed and updated the L2 table accordingly.
- *
- * Returns:
- *   0       if there was no dependency. *cur_bytes indicates the number of
- *           bytes from guest_offset that can be read before the next
- *           dependency must be processed (or the request is complete)
- *
- *   -EAGAIN if we had to wait for another request, previously gathered
- *           information on cluster allocation may be invalid now. The caller
- *           must start over anyway, so consider *cur_bytes undefined.
- */
-static int handle_dependencies(BlockDriverState *bs, uint64_t guest_offset,
-    uint64_t *cur_bytes, QCowL2Meta **m)
-{
-    BDRVQcow2State *s = bs->opaque;
-    QCowL2Meta *old_alloc;
-    uint64_t bytes = *cur_bytes;
-
-    QLIST_FOREACH(old_alloc, &s->cluster_allocs, next_in_flight) {
-
-        uint64_t start = guest_offset;
-        uint64_t end = start + bytes;
-        uint64_t old_start = l2meta_cow_start(old_alloc);
-        uint64_t old_end = l2meta_cow_end(old_alloc);
-
-        if (end <= old_start || start >= old_end) {
-            /* No intersection */
-        } else {
-            if (start < old_start) {
-                /* Stop at the start of a running allocation */
-                bytes = old_start - start;
-            } else {
-                bytes = 0;
-            }
-
-            /* Stop if already an l2meta exists. After yielding, it wouldn't
-             * be valid any more, so we'd have to clean up the old L2Metas
-             * and deal with requests depending on them before starting to
-             * gather new ones. Not worth the trouble. */
-            if (bytes == 0 && *m) {
-                *cur_bytes = 0;
-                return 0;
-            }
-
-            if (bytes == 0) {
-                /* Wait for the dependency to complete. We need to recheck
-                 * the free/allocated clusters when we continue. */
-                qemu_co_mutex_unlock(&s->lock);
-                qemu_co_queue_wait(&old_alloc->dependent_requests);
-                qemu_co_mutex_lock(&s->lock);
-                return -EAGAIN;
-            }
-        }
-    }
-
-    /* Make sure that existing clusters and new allocations are only used up to
-     * the next dependency if we shortened the request above */
-    *cur_bytes = bytes;
-
-    return 0;
-}
-
-/*
- * Checks how many already allocated clusters that don't require a copy on
- * write there are at the given guest_offset (up to *bytes). If
- * *host_offset is not zero, only physically contiguous clusters beginning at
- * this host offset are counted.
- *
- * Note that guest_offset may not be cluster aligned. In this case, the
- * returned *host_offset points to exact byte referenced by guest_offset and
- * therefore isn't cluster aligned as well.
- *
- * Returns:
- *   0:     if no allocated clusters are available at the given offset.
- *          *bytes is normally unchanged. It is set to 0 if the cluster
- *          is allocated and doesn't need COW, but doesn't have the right
- *          physical offset.
- *
- *   1:     if allocated clusters that don't require a COW are available at
- *          the requested offset. *bytes may have decreased and describes
- *          the length of the area that can be written to.
- *
- *  -errno: in error cases
- */
-static int handle_copied(BlockDriverState *bs, uint64_t guest_offset,
-    uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int l2_index;
-    uint64_t cluster_offset;
-    uint64_t *l2_table;
-    uint64_t nb_clusters;
-    unsigned int keep_clusters;
-    int ret;
-
-    trace_qcow2_handle_copied(qemu_coroutine_self(), guest_offset, *host_offset,
-                              *bytes);
-
-    assert(*host_offset == 0 ||    offset_into_cluster(s, guest_offset)
-                                == offset_into_cluster(s, *host_offset));
-
-    /*
-     * Calculate the number of clusters to look for. We stop at L2 table
-     * boundaries to keep things simple.
-     */
-    nb_clusters =
-        size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
-
-    l2_index = offset_to_l2_index(s, guest_offset);
-    nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
-    assert(nb_clusters <= INT_MAX);
-
-    /* Find L2 entry for the first involved cluster */
-    ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
-    if (ret < 0) {
-        return ret;
-    }
-
-    cluster_offset = be64_to_cpu(l2_table[l2_index]);
-
-    /* Check how many clusters are already allocated and don't need COW */
-    if (qcow2_get_cluster_type(cluster_offset) == QCOW2_CLUSTER_NORMAL
-        && (cluster_offset & QCOW_OFLAG_COPIED))
-    {
-        /* If a specific host_offset is required, check it */
-        bool offset_matches =
-            (cluster_offset & L2E_OFFSET_MASK) == *host_offset;
-
-        if (offset_into_cluster(s, cluster_offset & L2E_OFFSET_MASK)) {
-            qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset "
-                                    "%#llx unaligned (guest offset: %#" PRIx64
-                                    ")", cluster_offset & L2E_OFFSET_MASK,
-                                    guest_offset);
-            ret = -EIO;
-            goto out;
-        }
-
-        if (*host_offset != 0 && !offset_matches) {
-            *bytes = 0;
-            ret = 0;
-            goto out;
-        }
-
-        /* We keep all QCOW_OFLAG_COPIED clusters */
-        keep_clusters =
-            count_contiguous_clusters(nb_clusters, s->cluster_size,
-                                      &l2_table[l2_index],
-                                      QCOW_OFLAG_COPIED | QCOW_OFLAG_ZERO);
-        assert(keep_clusters <= nb_clusters);
-
-        *bytes = MIN(*bytes,
-                 keep_clusters * s->cluster_size
-                 - offset_into_cluster(s, guest_offset));
-
-        ret = 1;
-    } else {
-        ret = 0;
-    }
-
-    /* Cleanup */
-out:
-    qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-
-    /* Only return a host offset if we actually made progress. Otherwise we
-     * would make requirements for handle_alloc() that it can't fulfill */
-    if (ret > 0) {
-        *host_offset = (cluster_offset & L2E_OFFSET_MASK)
-                     + offset_into_cluster(s, guest_offset);
-    }
-
-    return ret;
-}
-
-/*
- * Allocates new clusters for the given guest_offset.
- *
- * At most *nb_clusters are allocated, and on return *nb_clusters is updated to
- * contain the number of clusters that have been allocated and are contiguous
- * in the image file.
- *
- * If *host_offset is non-zero, it specifies the offset in the image file at
- * which the new clusters must start. *nb_clusters can be 0 on return in this
- * case if the cluster at host_offset is already in use. If *host_offset is
- * zero, the clusters can be allocated anywhere in the image file.
- *
- * *host_offset is updated to contain the offset into the image file at which
- * the first allocated cluster starts.
- *
- * Return 0 on success and -errno in error cases. -EAGAIN means that the
- * function has been waiting for another request and the allocation must be
- * restarted, but the whole request should not be failed.
- */
-static int do_alloc_cluster_offset(BlockDriverState *bs, uint64_t guest_offset,
-                                   uint64_t *host_offset, uint64_t *nb_clusters)
-{
-    BDRVQcow2State *s = bs->opaque;
-
-    trace_qcow2_do_alloc_clusters_offset(qemu_coroutine_self(), guest_offset,
-                                         *host_offset, *nb_clusters);
-
-    /* Allocate new clusters */
-    trace_qcow2_cluster_alloc_phys(qemu_coroutine_self());
-    if (*host_offset == 0) {
-        int64_t cluster_offset =
-            qcow2_alloc_clusters(bs, *nb_clusters * s->cluster_size);
-        if (cluster_offset < 0) {
-            return cluster_offset;
-        }
-        *host_offset = cluster_offset;
-        return 0;
-    } else {
-        int64_t ret = qcow2_alloc_clusters_at(bs, *host_offset, *nb_clusters);
-        if (ret < 0) {
-            return ret;
-        }
-        *nb_clusters = ret;
-        return 0;
-    }
-}
-
-/*
- * Allocates new clusters for an area that either is yet unallocated or needs a
- * copy on write. If *host_offset is non-zero, clusters are only allocated if
- * the new allocation can match the specified host offset.
- *
- * Note that guest_offset may not be cluster aligned. In this case, the
- * returned *host_offset points to exact byte referenced by guest_offset and
- * therefore isn't cluster aligned as well.
- *
- * Returns:
- *   0:     if no clusters could be allocated. *bytes is set to 0,
- *          *host_offset is left unchanged.
- *
- *   1:     if new clusters were allocated. *bytes may be decreased if the
- *          new allocation doesn't cover all of the requested area.
- *          *host_offset is updated to contain the host offset of the first
- *          newly allocated cluster.
- *
- *  -errno: in error cases
- */
-static int handle_alloc(BlockDriverState *bs, uint64_t guest_offset,
-    uint64_t *host_offset, uint64_t *bytes, QCowL2Meta **m)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int l2_index;
-    uint64_t *l2_table;
-    uint64_t entry;
-    uint64_t nb_clusters;
-    int ret;
-
-    uint64_t alloc_cluster_offset;
-
-    trace_qcow2_handle_alloc(qemu_coroutine_self(), guest_offset, *host_offset,
-                             *bytes);
-    assert(*bytes > 0);
-
-    /*
-     * Calculate the number of clusters to look for. We stop at L2 table
-     * boundaries to keep things simple.
-     */
-    nb_clusters =
-        size_to_clusters(s, offset_into_cluster(s, guest_offset) + *bytes);
-
-    l2_index = offset_to_l2_index(s, guest_offset);
-    nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
-    assert(nb_clusters <= INT_MAX);
-
-    /* Find L2 entry for the first involved cluster */
-    ret = get_cluster_table(bs, guest_offset, &l2_table, &l2_index);
-    if (ret < 0) {
-        return ret;
-    }
-
-    entry = be64_to_cpu(l2_table[l2_index]);
-
-    /* For the moment, overwrite compressed clusters one by one */
-    if (entry & QCOW_OFLAG_COMPRESSED) {
-        nb_clusters = 1;
-    } else {
-        nb_clusters = count_cow_clusters(s, nb_clusters, l2_table, l2_index);
-    }
-
-    /* This function is only called when there were no non-COW clusters, so if
-     * we can't find any unallocated or COW clusters either, something is
-     * wrong with our code. */
-    assert(nb_clusters > 0);
-
-    qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-
-    /* Allocate, if necessary at a given offset in the image file */
-    alloc_cluster_offset = start_of_cluster(s, *host_offset);
-    ret = do_alloc_cluster_offset(bs, guest_offset, &alloc_cluster_offset,
-                                  &nb_clusters);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    /* Can't extend contiguous allocation */
-    if (nb_clusters == 0) {
-        *bytes = 0;
-        return 0;
-    }
-
-    /* !*host_offset would overwrite the image header and is reserved for "no
-     * host offset preferred". If 0 was a valid host offset, it'd trigger the
-     * following overlap check; do that now to avoid having an invalid value in
-     * *host_offset. */
-    if (!alloc_cluster_offset) {
-        ret = qcow2_pre_write_overlap_check(bs, 0, alloc_cluster_offset,
-                                            nb_clusters * s->cluster_size);
-        assert(ret < 0);
-        goto fail;
-    }
-
-    /*
-     * Save info needed for meta data update.
-     *
-     * requested_sectors: Number of sectors from the start of the first
-     * newly allocated cluster to the end of the (possibly shortened
-     * before) write request.
-     *
-     * avail_sectors: Number of sectors from the start of the first
-     * newly allocated to the end of the last newly allocated cluster.
-     *
-     * nb_sectors: The number of sectors from the start of the first
-     * newly allocated cluster to the end of the area that the write
-     * request actually writes to (excluding COW at the end)
-     */
-    int requested_sectors =
-        (*bytes + offset_into_cluster(s, guest_offset))
-        >> BDRV_SECTOR_BITS;
-    int avail_sectors = nb_clusters
-                        << (s->cluster_bits - BDRV_SECTOR_BITS);
-    int alloc_n_start = offset_into_cluster(s, guest_offset)
-                        >> BDRV_SECTOR_BITS;
-    int nb_sectors = MIN(requested_sectors, avail_sectors);
-    QCowL2Meta *old_m = *m;
-
-    *m = g_malloc0(sizeof(**m));
-
-    **m = (QCowL2Meta) {
-        .next           = old_m,
-
-        .alloc_offset   = alloc_cluster_offset,
-        .offset         = start_of_cluster(s, guest_offset),
-        .nb_clusters    = nb_clusters,
-        .nb_available   = nb_sectors,
-
-        .cow_start = {
-            .offset     = 0,
-            .nb_sectors = alloc_n_start,
-        },
-        .cow_end = {
-            .offset     = nb_sectors * BDRV_SECTOR_SIZE,
-            .nb_sectors = avail_sectors - nb_sectors,
-        },
-    };
-    qemu_co_queue_init(&(*m)->dependent_requests);
-    QLIST_INSERT_HEAD(&s->cluster_allocs, *m, next_in_flight);
-
-    *host_offset = alloc_cluster_offset + offset_into_cluster(s, guest_offset);
-    *bytes = MIN(*bytes, (nb_sectors * BDRV_SECTOR_SIZE)
-                         - offset_into_cluster(s, guest_offset));
-    assert(*bytes != 0);
-
-    return 1;
-
-fail:
-    if (*m && (*m)->nb_clusters > 0) {
-        QLIST_REMOVE(*m, next_in_flight);
-    }
-    return ret;
-}
-
-/*
- * alloc_cluster_offset
- *
- * For a given offset on the virtual disk, find the cluster offset in qcow2
- * file. If the offset is not found, allocate a new cluster.
- *
- * If the cluster was already allocated, m->nb_clusters is set to 0 and
- * other fields in m are meaningless.
- *
- * If the cluster is newly allocated, m->nb_clusters is set to the number of
- * contiguous clusters that have been allocated. In this case, the other
- * fields of m are valid and contain information about the first allocated
- * cluster.
- *
- * If the request conflicts with another write request in flight, the coroutine
- * is queued and will be reentered when the dependency has completed.
- *
- * Return 0 on success and -errno in error cases
- */
-int qcow2_alloc_cluster_offset(BlockDriverState *bs, uint64_t offset,
-    int *num, uint64_t *host_offset, QCowL2Meta **m)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t start, remaining;
-    uint64_t cluster_offset;
-    uint64_t cur_bytes;
-    int ret;
-
-    trace_qcow2_alloc_clusters_offset(qemu_coroutine_self(), offset, *num);
-
-    assert((offset & ~BDRV_SECTOR_MASK) == 0);
-
-again:
-    start = offset;
-    remaining = (uint64_t)*num << BDRV_SECTOR_BITS;
-    cluster_offset = 0;
-    *host_offset = 0;
-    cur_bytes = 0;
-    *m = NULL;
-
-    while (true) {
-
-        if (!*host_offset) {
-            *host_offset = start_of_cluster(s, cluster_offset);
-        }
-
-        assert(remaining >= cur_bytes);
-
-        start           += cur_bytes;
-        remaining       -= cur_bytes;
-        cluster_offset  += cur_bytes;
-
-        if (remaining == 0) {
-            break;
-        }
-
-        cur_bytes = remaining;
-
-        /*
-         * Now start gathering as many contiguous clusters as possible:
-         *
-         * 1. Check for overlaps with in-flight allocations
-         *
-         *      a) Overlap not in the first cluster -> shorten this request and
-         *         let the caller handle the rest in its next loop iteration.
-         *
-         *      b) Real overlaps of two requests. Yield and restart the search
-         *         for contiguous clusters (the situation could have changed
-         *         while we were sleeping)
-         *
-         *      c) TODO: Request starts in the same cluster as the in-flight
-         *         allocation ends. Shorten the COW of the in-fight allocation,
-         *         set cluster_offset to write to the same cluster and set up
-         *         the right synchronisation between the in-flight request and
-         *         the new one.
-         */
-        ret = handle_dependencies(bs, start, &cur_bytes, m);
-        if (ret == -EAGAIN) {
-            /* Currently handle_dependencies() doesn't yield if we already had
-             * an allocation. If it did, we would have to clean up the L2Meta
-             * structs before starting over. */
-            assert(*m == NULL);
-            goto again;
-        } else if (ret < 0) {
-            return ret;
-        } else if (cur_bytes == 0) {
-            break;
-        } else {
-            /* handle_dependencies() may have decreased cur_bytes (shortened
-             * the allocations below) so that the next dependency is processed
-             * correctly during the next loop iteration. */
-        }
-
-        /*
-         * 2. Count contiguous COPIED clusters.
-         */
-        ret = handle_copied(bs, start, &cluster_offset, &cur_bytes, m);
-        if (ret < 0) {
-            return ret;
-        } else if (ret) {
-            continue;
-        } else if (cur_bytes == 0) {
-            break;
-        }
-
-        /*
-         * 3. If the request still hasn't completed, allocate new clusters,
-         *    considering any cluster_offset of steps 1c or 2.
-         */
-        ret = handle_alloc(bs, start, &cluster_offset, &cur_bytes, m);
-        if (ret < 0) {
-            return ret;
-        } else if (ret) {
-            continue;
-        } else {
-            assert(cur_bytes == 0);
-            break;
-        }
-    }
-
-    *num -= remaining >> BDRV_SECTOR_BITS;
-    assert(*num > 0);
-    assert(*host_offset != 0);
-
-    return 0;
-}
-
-static int decompress_buffer(uint8_t *out_buf, int out_buf_size,
-                             const uint8_t *buf, int buf_size)
-{
-    z_stream strm1, *strm = &strm1;
-    int ret, out_len;
-
-    memset(strm, 0, sizeof(*strm));
-
-    strm->next_in = (uint8_t *)buf;
-    strm->avail_in = buf_size;
-    strm->next_out = out_buf;
-    strm->avail_out = out_buf_size;
-
-    ret = inflateInit2(strm, -12);
-    if (ret != Z_OK)
-        return -1;
-    ret = inflate(strm, Z_FINISH);
-    out_len = strm->next_out - out_buf;
-    if ((ret != Z_STREAM_END && ret != Z_BUF_ERROR) ||
-        out_len != out_buf_size) {
-        inflateEnd(strm);
-        return -1;
-    }
-    inflateEnd(strm);
-    return 0;
-}
-
-int qcow2_decompress_cluster(BlockDriverState *bs, uint64_t cluster_offset)
-{
-    BDRVQcow2State *s = bs->opaque;
-    int ret, csize, nb_csectors, sector_offset;
-    uint64_t coffset;
-
-    coffset = cluster_offset & s->cluster_offset_mask;
-    if (s->cluster_cache_offset != coffset) {
-        nb_csectors = ((cluster_offset >> s->csize_shift) & s->csize_mask) + 1;
-        sector_offset = coffset & 511;
-        csize = nb_csectors * 512 - sector_offset;
-        BLKDBG_EVENT(bs->file, BLKDBG_READ_COMPRESSED);
-        ret = bdrv_read(bs->file->bs, coffset >> 9, s->cluster_data,
-                        nb_csectors);
-        if (ret < 0) {
-            return ret;
-        }
-        if (decompress_buffer(s->cluster_cache, s->cluster_size,
-                              s->cluster_data + sector_offset, csize) < 0) {
-            return -EIO;
-        }
-        s->cluster_cache_offset = coffset;
-    }
-    return 0;
-}
-
-/*
- * This discards as many clusters of nb_clusters as possible at once (i.e.
- * all clusters in the same L2 table) and returns the number of discarded
- * clusters.
- */
-static int discard_single_l2(BlockDriverState *bs, uint64_t offset,
-                             uint64_t nb_clusters, enum qcow2_discard_type type,
-                             bool full_discard)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t *l2_table;
-    int l2_index;
-    int ret;
-    int i;
-
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
-    if (ret < 0) {
-        return ret;
-    }
-
-    /* Limit nb_clusters to one L2 table */
-    nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
-    assert(nb_clusters <= INT_MAX);
-
-    for (i = 0; i < nb_clusters; i++) {
-        uint64_t old_l2_entry;
-
-        old_l2_entry = be64_to_cpu(l2_table[l2_index + i]);
-
-        /*
-         * If full_discard is false, make sure that a discarded area reads back
-         * as zeroes for v3 images (we cannot do it for v2 without actually
-         * writing a zero-filled buffer). We can skip the operation if the
-         * cluster is already marked as zero, or if it's unallocated and we
-         * don't have a backing file.
-         *
-         * TODO We might want to use bdrv_get_block_status(bs) here, but we're
-         * holding s->lock, so that doesn't work today.
-         *
-         * If full_discard is true, the sector should not read back as zeroes,
-         * but rather fall through to the backing file.
-         */
-        switch (qcow2_get_cluster_type(old_l2_entry)) {
-            case QCOW2_CLUSTER_UNALLOCATED:
-                if (full_discard || !bs->backing) {
-                    continue;
-                }
-                break;
-
-            case QCOW2_CLUSTER_ZERO:
-                if (!full_discard) {
-                    continue;
-                }
-                break;
-
-            case QCOW2_CLUSTER_NORMAL:
-            case QCOW2_CLUSTER_COMPRESSED:
-                break;
-
-            default:
-                abort();
-        }
-
-        /* First remove L2 entries */
-        qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table);
-        if (!full_discard && s->qcow_version >= 3) {
-            l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
-        } else {
-            l2_table[l2_index + i] = cpu_to_be64(0);
-        }
-
-        /* Then decrease the refcount */
-        qcow2_free_any_clusters(bs, old_l2_entry, 1, type);
-    }
-
-    qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-
-    return nb_clusters;
-}
-
-int qcow2_discard_clusters(BlockDriverState *bs, uint64_t offset,
-    int nb_sectors, enum qcow2_discard_type type, bool full_discard)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t end_offset;
-    uint64_t nb_clusters;
-    int ret;
-
-    end_offset = offset + (nb_sectors << BDRV_SECTOR_BITS);
-
-    /* Round start up and end down */
-    offset = align_offset(offset, s->cluster_size);
-    end_offset = start_of_cluster(s, end_offset);
-
-    if (offset > end_offset) {
-        return 0;
-    }
-
-    nb_clusters = size_to_clusters(s, end_offset - offset);
-
-    s->cache_discards = true;
-
-    /* Each L2 table is handled by its own loop iteration */
-    while (nb_clusters > 0) {
-        ret = discard_single_l2(bs, offset, nb_clusters, type, full_discard);
-        if (ret < 0) {
-            goto fail;
-        }
-
-        nb_clusters -= ret;
-        offset += (ret * s->cluster_size);
-    }
-
-    ret = 0;
-fail:
-    s->cache_discards = false;
-    qcow2_process_discards(bs, ret);
-
-    return ret;
-}
-
-/*
- * This zeroes as many clusters of nb_clusters as possible at once (i.e.
- * all clusters in the same L2 table) and returns the number of zeroed
- * clusters.
- */
-static int zero_single_l2(BlockDriverState *bs, uint64_t offset,
-                          uint64_t nb_clusters)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t *l2_table;
-    int l2_index;
-    int ret;
-    int i;
-
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_index);
-    if (ret < 0) {
-        return ret;
-    }
-
-    /* Limit nb_clusters to one L2 table */
-    nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
-    assert(nb_clusters <= INT_MAX);
-
-    for (i = 0; i < nb_clusters; i++) {
-        uint64_t old_offset;
-
-        old_offset = be64_to_cpu(l2_table[l2_index + i]);
-
-        /* Update L2 entries */
-        qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table);
-        if (old_offset & QCOW_OFLAG_COMPRESSED) {
-            l2_table[l2_index + i] = cpu_to_be64(QCOW_OFLAG_ZERO);
-            qcow2_free_any_clusters(bs, old_offset, 1, QCOW2_DISCARD_REQUEST);
-        } else {
-            l2_table[l2_index + i] |= cpu_to_be64(QCOW_OFLAG_ZERO);
-        }
-    }
-
-    qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-
-    return nb_clusters;
-}
-
-int qcow2_zero_clusters(BlockDriverState *bs, uint64_t offset, int nb_sectors)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t nb_clusters;
-    int ret;
-
-    /* The zero flag is only supported by version 3 and newer */
-    if (s->qcow_version < 3) {
-        return -ENOTSUP;
-    }
-
-    /* Each L2 table is handled by its own loop iteration */
-    nb_clusters = size_to_clusters(s, nb_sectors << BDRV_SECTOR_BITS);
-
-    s->cache_discards = true;
-
-    while (nb_clusters > 0) {
-        ret = zero_single_l2(bs, offset, nb_clusters);
-        if (ret < 0) {
-            goto fail;
-        }
-
-        nb_clusters -= ret;
-        offset += (ret * s->cluster_size);
-    }
-
-    ret = 0;
-fail:
-    s->cache_discards = false;
-    qcow2_process_discards(bs, ret);
-
-    return ret;
-}
-
-/*
- * Expands all zero clusters in a specific L1 table (or deallocates them, for
- * non-backed non-pre-allocated zero clusters).
- *
- * l1_entries and *visited_l1_entries are used to keep track of progress for
- * status_cb(). l1_entries contains the total number of L1 entries and
- * *visited_l1_entries counts all visited L1 entries.
- */
-static int expand_zero_clusters_in_l1(BlockDriverState *bs, uint64_t *l1_table,
-                                      int l1_size, int64_t *visited_l1_entries,
-                                      int64_t l1_entries,
-                                      BlockDriverAmendStatusCB *status_cb,
-                                      void *cb_opaque)
-{
-    BDRVQcow2State *s = bs->opaque;
-    bool is_active_l1 = (l1_table == s->l1_table);
-    uint64_t *l2_table = NULL;
-    int ret;
-    int i, j;
-
-    if (!is_active_l1) {
-        /* inactive L2 tables require a buffer to be stored in when loading
-         * them from disk */
-        l2_table = qemu_try_blockalign(bs->file->bs, s->cluster_size);
-        if (l2_table == NULL) {
-            return -ENOMEM;
-        }
-    }
-
-    for (i = 0; i < l1_size; i++) {
-        uint64_t l2_offset = l1_table[i] & L1E_OFFSET_MASK;
-        bool l2_dirty = false;
-        uint64_t l2_refcount;
-
-        if (!l2_offset) {
-            /* unallocated */
-            (*visited_l1_entries)++;
-            if (status_cb) {
-                status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
-            }
-            continue;
-        }
-
-        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;
-        }
-
-        if (is_active_l1) {
-            /* get active L2 tables from cache */
-            ret = qcow2_cache_get(bs, s->l2_table_cache, l2_offset,
-                    (void **)&l2_table);
-        } else {
-            /* load inactive L2 tables from disk */
-            ret = bdrv_read(bs->file->bs, l2_offset / BDRV_SECTOR_SIZE,
-                            (void *)l2_table, s->cluster_sectors);
-        }
-        if (ret < 0) {
-            goto fail;
-        }
-
-        ret = qcow2_get_refcount(bs, l2_offset >> s->cluster_bits,
-                                 &l2_refcount);
-        if (ret < 0) {
-            goto fail;
-        }
-
-        for (j = 0; j < s->l2_size; j++) {
-            uint64_t l2_entry = be64_to_cpu(l2_table[j]);
-            int64_t offset = l2_entry & L2E_OFFSET_MASK;
-            int cluster_type = qcow2_get_cluster_type(l2_entry);
-            bool preallocated = offset != 0;
-
-            if (cluster_type != QCOW2_CLUSTER_ZERO) {
-                continue;
-            }
-
-            if (!preallocated) {
-                if (!bs->backing) {
-                    /* not backed; therefore we can simply deallocate the
-                     * cluster */
-                    l2_table[j] = 0;
-                    l2_dirty = true;
-                    continue;
-                }
-
-                offset = qcow2_alloc_clusters(bs, s->cluster_size);
-                if (offset < 0) {
-                    ret = offset;
-                    goto fail;
-                }
-
-                if (l2_refcount > 1) {
-                    /* For shared L2 tables, set the refcount accordingly (it is
-                     * already 1 and needs to be l2_refcount) */
-                    ret = qcow2_update_cluster_refcount(bs,
-                            offset >> s->cluster_bits,
-                            refcount_diff(1, l2_refcount), false,
-                            QCOW2_DISCARD_OTHER);
-                    if (ret < 0) {
-                        qcow2_free_clusters(bs, offset, s->cluster_size,
-                                            QCOW2_DISCARD_OTHER);
-                        goto fail;
-                    }
-                }
-            }
-
-            if (offset_into_cluster(s, offset)) {
-                qcow2_signal_corruption(bs, true, -1, -1, "Data cluster offset "
-                                        "%#" PRIx64 " unaligned (L2 offset: %#"
-                                        PRIx64 ", L2 index: %#x)", offset,
-                                        l2_offset, j);
-                if (!preallocated) {
-                    qcow2_free_clusters(bs, offset, s->cluster_size,
-                                        QCOW2_DISCARD_ALWAYS);
-                }
-                ret = -EIO;
-                goto fail;
-            }
-
-            ret = qcow2_pre_write_overlap_check(bs, 0, offset, s->cluster_size);
-            if (ret < 0) {
-                if (!preallocated) {
-                    qcow2_free_clusters(bs, offset, s->cluster_size,
-                                        QCOW2_DISCARD_ALWAYS);
-                }
-                goto fail;
-            }
-
-            ret = bdrv_write_zeroes(bs->file->bs, offset / BDRV_SECTOR_SIZE,
-                                    s->cluster_sectors, 0);
-            if (ret < 0) {
-                if (!preallocated) {
-                    qcow2_free_clusters(bs, offset, s->cluster_size,
-                                        QCOW2_DISCARD_ALWAYS);
-                }
-                goto fail;
-            }
-
-            if (l2_refcount == 1) {
-                l2_table[j] = cpu_to_be64(offset | QCOW_OFLAG_COPIED);
-            } else {
-                l2_table[j] = cpu_to_be64(offset);
-            }
-            l2_dirty = true;
-        }
-
-        if (is_active_l1) {
-            if (l2_dirty) {
-                qcow2_cache_entry_mark_dirty(bs, s->l2_table_cache, l2_table);
-                qcow2_cache_depends_on_flush(s->l2_table_cache);
-            }
-            qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-        } else {
-            if (l2_dirty) {
-                ret = qcow2_pre_write_overlap_check(bs,
-                        QCOW2_OL_INACTIVE_L2 | QCOW2_OL_ACTIVE_L2, l2_offset,
-                        s->cluster_size);
-                if (ret < 0) {
-                    goto fail;
-                }
-
-                ret = bdrv_write(bs->file->bs, l2_offset / BDRV_SECTOR_SIZE,
-                                 (void *)l2_table, s->cluster_sectors);
-                if (ret < 0) {
-                    goto fail;
-                }
-            }
-        }
-
-        (*visited_l1_entries)++;
-        if (status_cb) {
-            status_cb(bs, *visited_l1_entries, l1_entries, cb_opaque);
-        }
-    }
-
-    ret = 0;
-
-fail:
-    if (l2_table) {
-        if (!is_active_l1) {
-            qemu_vfree(l2_table);
-        } else {
-            qcow2_cache_put(bs, s->l2_table_cache, (void **) &l2_table);
-        }
-    }
-    return ret;
-}
-
-/*
- * For backed images, expands all zero clusters on the image. For non-backed
- * images, deallocates all non-pre-allocated zero clusters (and claims the
- * allocation for pre-allocated ones). This is important for downgrading to a
- * qcow2 version which doesn't yet support metadata zero clusters.
- */
-int qcow2_expand_zero_clusters(BlockDriverState *bs,
-                               BlockDriverAmendStatusCB *status_cb,
-                               void *cb_opaque)
-{
-    BDRVQcow2State *s = bs->opaque;
-    uint64_t *l1_table = NULL;
-    int64_t l1_entries = 0, visited_l1_entries = 0;
-    int ret;
-    int i, j;
-
-    if (status_cb) {
-        l1_entries = s->l1_size;
-        for (i = 0; i < s->nb_snapshots; i++) {
-            l1_entries += s->snapshots[i].l1_size;
-        }
-    }
-
-    ret = expand_zero_clusters_in_l1(bs, s->l1_table, s->l1_size,
-                                     &visited_l1_entries, l1_entries,
-                                     status_cb, cb_opaque);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    /* Inactive L1 tables may point to active L2 tables - therefore it is
-     * necessary to flush the L2 table cache before trying to access the L2
-     * tables pointed to by inactive L1 entries (else we might try to expand
-     * zero clusters that have already been expanded); furthermore, it is also
-     * necessary to empty the L2 table cache, since it may contain tables which
-     * are now going to be modified directly on disk, bypassing the cache.
-     * qcow2_cache_empty() does both for us. */
-    ret = qcow2_cache_empty(bs, s->l2_table_cache);
-    if (ret < 0) {
-        goto fail;
-    }
-
-    for (i = 0; i < s->nb_snapshots; i++) {
-        int l1_sectors = (s->snapshots[i].l1_size * sizeof(uint64_t) +
-                BDRV_SECTOR_SIZE - 1) / BDRV_SECTOR_SIZE;
-
-        l1_table = g_realloc(l1_table, l1_sectors * BDRV_SECTOR_SIZE);
-
-        ret = bdrv_read(bs->file->bs,
-                        s->snapshots[i].l1_table_offset / BDRV_SECTOR_SIZE,
-                        (void *)l1_table, l1_sectors);
-        if (ret < 0) {
-            goto fail;
-        }
-
-        for (j = 0; j < s->snapshots[i].l1_size; j++) {
-            be64_to_cpus(&l1_table[j]);
-        }
-
-        ret = expand_zero_clusters_in_l1(bs, l1_table, s->snapshots[i].l1_size,
-                                         &visited_l1_entries, l1_entries,
-                                         status_cb, cb_opaque);
-        if (ret < 0) {
-            goto fail;
-        }
-    }
-
-    ret = 0;
-
-fail:
-    g_free(l1_table);
-    return ret;
-}