Move block drivers into their own directory

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 0 insertions, 2931 deletions

diff --git a/block-qcow2.c b/block-qcow2.c
deleted file mode 100644
index a6de9b6919..0000000000
--- a/block-qcow2.c
+++ /dev/null
@@ -1,2931 +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-common.h"
-#include "block_int.h"
-#include "module.h"
-#include <zlib.h>
-#include "aes.h"
-
-/*
-  Differences with QCOW:
-
-  - Support for multiple incremental snapshots.
-  - Memory management by reference counts.
-  - Clusters which have a reference count of one have the bit
-    QCOW_OFLAG_COPIED to optimize write performance.
-  - Size of compressed clusters is stored in sectors to reduce bit usage
-    in the cluster offsets.
-  - Support for storing additional data (such as the VM state) in the
-    snapshots.
-  - If a backing store is used, the cluster size is not constrained
-    (could be backported to QCOW).
-  - L2 tables have always a size of one cluster.
-*/
-
-//#define DEBUG_ALLOC
-//#define DEBUG_ALLOC2
-//#define DEBUG_EXT
-
-#define QCOW_MAGIC (('Q' << 24) | ('F' << 16) | ('I' << 8) | 0xfb)
-#define QCOW_VERSION 2
-
-#define QCOW_CRYPT_NONE 0
-#define QCOW_CRYPT_AES  1
-
-#define QCOW_MAX_CRYPT_CLUSTERS 32
-
-/* indicate that the refcount of the referenced cluster is exactly one. */
-#define QCOW_OFLAG_COPIED     (1LL << 63)
-/* indicate that the cluster is compressed (they never have the copied flag) */
-#define QCOW_OFLAG_COMPRESSED (1LL << 62)
-
-#define REFCOUNT_SHIFT 1 /* refcount size is 2 bytes */
-
-typedef struct QCowHeader {
-    uint32_t magic;
-    uint32_t version;
-    uint64_t backing_file_offset;
-    uint32_t backing_file_size;
-    uint32_t cluster_bits;
-    uint64_t size; /* in bytes */
-    uint32_t crypt_method;
-    uint32_t l1_size; /* XXX: save number of clusters instead ? */
-    uint64_t l1_table_offset;
-    uint64_t refcount_table_offset;
-    uint32_t refcount_table_clusters;
-    uint32_t nb_snapshots;
-    uint64_t snapshots_offset;
-} QCowHeader;
-
-
-typedef struct {
-    uint32_t magic;
-    uint32_t len;
-} QCowExtension;
-#define  QCOW_EXT_MAGIC_END 0
-#define  QCOW_EXT_MAGIC_BACKING_FORMAT 0xE2792ACA
-
-
-typedef struct __attribute__((packed)) QCowSnapshotHeader {
-    /* header is 8 byte aligned */
-    uint64_t l1_table_offset;
-
-    uint32_t l1_size;
-    uint16_t id_str_size;
-    uint16_t name_size;
-
-    uint32_t date_sec;
-    uint32_t date_nsec;
-
-    uint64_t vm_clock_nsec;
-
-    uint32_t vm_state_size;
-    uint32_t extra_data_size; /* for extension */
-    /* extra data follows */
-    /* id_str follows */
-    /* name follows  */
-} QCowSnapshotHeader;
-
-#define L2_CACHE_SIZE 16
-
-typedef struct QCowSnapshot {
-    uint64_t l1_table_offset;
-    uint32_t l1_size;
-    char *id_str;
-    char *name;
-    uint32_t vm_state_size;
-    uint32_t date_sec;
-    uint32_t date_nsec;
-    uint64_t vm_clock_nsec;
-} QCowSnapshot;
-
-typedef struct BDRVQcowState {
-    BlockDriverState *hd;
-    int cluster_bits;
-    int cluster_size;
-    int cluster_sectors;
-    int l2_bits;
-    int l2_size;
-    int l1_size;
-    int l1_vm_state_index;
-    int csize_shift;
-    int csize_mask;
-    uint64_t cluster_offset_mask;
-    uint64_t l1_table_offset;
-    uint64_t *l1_table;
-    uint64_t *l2_cache;
-    uint64_t l2_cache_offsets[L2_CACHE_SIZE];
-    uint32_t l2_cache_counts[L2_CACHE_SIZE];
-    uint8_t *cluster_cache;
-    uint8_t *cluster_data;
-    uint64_t cluster_cache_offset;
-
-    uint64_t *refcount_table;
-    uint64_t refcount_table_offset;
-    uint32_t refcount_table_size;
-    uint64_t refcount_block_cache_offset;
-    uint16_t *refcount_block_cache;
-    int64_t free_cluster_index;
-    int64_t free_byte_offset;
-
-    uint32_t crypt_method; /* current crypt method, 0 if no key yet */
-    uint32_t crypt_method_header;
-    AES_KEY aes_encrypt_key;
-    AES_KEY aes_decrypt_key;
-    uint64_t snapshots_offset;
-    int snapshots_size;
-    int nb_snapshots;
-    QCowSnapshot *snapshots;
-} BDRVQcowState;
-
-static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset);
-static int qcow_read(BlockDriverState *bs, int64_t sector_num,
-                     uint8_t *buf, int nb_sectors);
-static int qcow_read_snapshots(BlockDriverState *bs);
-static void qcow_free_snapshots(BlockDriverState *bs);
-static int refcount_init(BlockDriverState *bs);
-static void refcount_close(BlockDriverState *bs);
-static int get_refcount(BlockDriverState *bs, int64_t cluster_index);
-static int update_cluster_refcount(BlockDriverState *bs,
-                                   int64_t cluster_index,
-                                   int addend);
-static void update_refcount(BlockDriverState *bs,
-                            int64_t offset, int64_t length,
-                            int addend);
-static int64_t alloc_clusters(BlockDriverState *bs, int64_t size);
-static int64_t alloc_bytes(BlockDriverState *bs, int size);
-static void free_clusters(BlockDriverState *bs,
-                          int64_t offset, int64_t size);
-static int check_refcounts(BlockDriverState *bs);
-
-static int qcow_probe(const uint8_t *buf, int buf_size, const char *filename)
-{
-    const QCowHeader *cow_header = (const void *)buf;
-
-    if (buf_size >= sizeof(QCowHeader) &&
-        be32_to_cpu(cow_header->magic) == QCOW_MAGIC &&
-        be32_to_cpu(cow_header->version) == QCOW_VERSION)
-        return 100;
-    else
-        return 0;
-}
-
-
-/* 
- * read qcow2 extension and fill bs
- * start reading from start_offset
- * finish reading upon magic of value 0 or when end_offset reached
- * unknown magic is skipped (future extension this version knows nothing about)
- * return 0 upon success, non-0 otherwise
- */
-static int qcow_read_extensions(BlockDriverState *bs, uint64_t start_offset,
-                                uint64_t end_offset)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowExtension ext;
-    uint64_t offset;
-
-#ifdef DEBUG_EXT
-    printf("qcow_read_extensions: start=%ld end=%ld\n", start_offset, end_offset);
-#endif
-    offset = start_offset;
-    while (offset < end_offset) {
-
-#ifdef DEBUG_EXT
-        /* Sanity check */
-        if (offset > s->cluster_size)
-            printf("qcow_handle_extension: suspicious offset %lu\n", offset);
-
-        printf("attemting to read extended header in offset %lu\n", offset);
-#endif
-
-        if (bdrv_pread(s->hd, offset, &ext, sizeof(ext)) != sizeof(ext)) {
-            fprintf(stderr, "qcow_handle_extension: ERROR: pread fail from offset %llu\n",
-                    (unsigned long long)offset);
-            return 1;
-        }
-        be32_to_cpus(&ext.magic);
-        be32_to_cpus(&ext.len);
-        offset += sizeof(ext);
-#ifdef DEBUG_EXT
-        printf("ext.magic = 0x%x\n", ext.magic);
-#endif
-        switch (ext.magic) {
-        case QCOW_EXT_MAGIC_END:
-            return 0;
-
-        case QCOW_EXT_MAGIC_BACKING_FORMAT:
-            if (ext.len >= sizeof(bs->backing_format)) {
-                fprintf(stderr, "ERROR: ext_backing_format: len=%u too large"
-                        " (>=%zu)\n",
-                        ext.len, sizeof(bs->backing_format));
-                return 2;
-            }
-            if (bdrv_pread(s->hd, offset , bs->backing_format,
-                           ext.len) != ext.len)
-                return 3;
-            bs->backing_format[ext.len] = '\0';
-#ifdef DEBUG_EXT
-            printf("Qcow2: Got format extension %s\n", bs->backing_format);
-#endif
-            offset += ((ext.len + 7) & ~7);
-            break;
-
-        default:
-            /* unknown magic -- just skip it */
-            offset += ((ext.len + 7) & ~7);
-            break;
-        }
-    }
-
-    return 0;
-}
-
-
-static int qcow_open(BlockDriverState *bs, const char *filename, int flags)
-{
-    BDRVQcowState *s = bs->opaque;
-    int len, i, shift, ret;
-    QCowHeader header;
-    uint64_t ext_end;
-
-    /* Performance is terrible right now with cache=writethrough due mainly
-     * to reference count updates.  If the user does not explicitly specify
-     * a caching type, force to writeback caching.
-     */
-    if ((flags & BDRV_O_CACHE_DEF)) {
-        flags |= BDRV_O_CACHE_WB;
-        flags &= ~BDRV_O_CACHE_DEF;
-    }
-    ret = bdrv_file_open(&s->hd, filename, flags);
-    if (ret < 0)
-        return ret;
-    if (bdrv_pread(s->hd, 0, &header, sizeof(header)) != sizeof(header))
-        goto fail;
-    be32_to_cpus(&header.magic);
-    be32_to_cpus(&header.version);
-    be64_to_cpus(&header.backing_file_offset);
-    be32_to_cpus(&header.backing_file_size);
-    be64_to_cpus(&header.size);
-    be32_to_cpus(&header.cluster_bits);
-    be32_to_cpus(&header.crypt_method);
-    be64_to_cpus(&header.l1_table_offset);
-    be32_to_cpus(&header.l1_size);
-    be64_to_cpus(&header.refcount_table_offset);
-    be32_to_cpus(&header.refcount_table_clusters);
-    be64_to_cpus(&header.snapshots_offset);
-    be32_to_cpus(&header.nb_snapshots);
-
-    if (header.magic != QCOW_MAGIC || header.version != QCOW_VERSION)
-        goto fail;
-    if (header.size <= 1 ||
-        header.cluster_bits < 9 ||
-        header.cluster_bits > 16)
-        goto fail;
-    if (header.crypt_method > QCOW_CRYPT_AES)
-        goto fail;
-    s->crypt_method_header = header.crypt_method;
-    if (s->crypt_method_header)
-        bs->encrypted = 1;
-    s->cluster_bits = header.cluster_bits;
-    s->cluster_size = 1 << s->cluster_bits;
-    s->cluster_sectors = 1 << (s->cluster_bits - 9);
-    s->l2_bits = s->cluster_bits - 3; /* L2 is always one cluster */
-    s->l2_size = 1 << s->l2_bits;
-    bs->total_sectors = header.size / 512;
-    s->csize_shift = (62 - (s->cluster_bits - 8));
-    s->csize_mask = (1 << (s->cluster_bits - 8)) - 1;
-    s->cluster_offset_mask = (1LL << s->csize_shift) - 1;
-    s->refcount_table_offset = header.refcount_table_offset;
-    s->refcount_table_size =
-        header.refcount_table_clusters << (s->cluster_bits - 3);
-
-    s->snapshots_offset = header.snapshots_offset;
-    s->nb_snapshots = header.nb_snapshots;
-
-    /* read the level 1 table */
-    s->l1_size = header.l1_size;
-    shift = s->cluster_bits + s->l2_bits;
-    s->l1_vm_state_index = (header.size + (1LL << shift) - 1) >> shift;
-    /* the L1 table must contain at least enough entries to put
-       header.size bytes */
-    if (s->l1_size < s->l1_vm_state_index)
-        goto fail;
-    s->l1_table_offset = header.l1_table_offset;
-    s->l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
-    if (bdrv_pread(s->hd, s->l1_table_offset, s->l1_table, s->l1_size * sizeof(uint64_t)) !=
-        s->l1_size * sizeof(uint64_t))
-        goto fail;
-    for(i = 0;i < s->l1_size; i++) {
-        be64_to_cpus(&s->l1_table[i]);
-    }
-    /* alloc L2 cache */
-    s->l2_cache = qemu_malloc(s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
-    s->cluster_cache = qemu_malloc(s->cluster_size);
-    /* one more sector for decompressed data alignment */
-    s->cluster_data = qemu_malloc(QCOW_MAX_CRYPT_CLUSTERS * s->cluster_size
-                                  + 512);
-    s->cluster_cache_offset = -1;
-
-    if (refcount_init(bs) < 0)
-        goto fail;
-
-    /* read qcow2 extensions */
-    if (header.backing_file_offset)
-        ext_end = header.backing_file_offset;
-    else
-        ext_end = s->cluster_size;
-    if (qcow_read_extensions(bs, sizeof(header), ext_end))
-        goto fail;
-
-    /* read the backing file name */
-    if (header.backing_file_offset != 0) {
-        len = header.backing_file_size;
-        if (len > 1023)
-            len = 1023;
-        if (bdrv_pread(s->hd, header.backing_file_offset, bs->backing_file, len) != len)
-            goto fail;
-        bs->backing_file[len] = '\0';
-    }
-    if (qcow_read_snapshots(bs) < 0)
-        goto fail;
-
-#ifdef DEBUG_ALLOC
-    check_refcounts(bs);
-#endif
-    return 0;
-
- fail:
-    qcow_free_snapshots(bs);
-    refcount_close(bs);
-    qemu_free(s->l1_table);
-    qemu_free(s->l2_cache);
-    qemu_free(s->cluster_cache);
-    qemu_free(s->cluster_data);
-    bdrv_delete(s->hd);
-    return -1;
-}
-
-static int qcow_set_key(BlockDriverState *bs, const char *key)
-{
-    BDRVQcowState *s = bs->opaque;
-    uint8_t keybuf[16];
-    int len, i;
-
-    memset(keybuf, 0, 16);
-    len = strlen(key);
-    if (len > 16)
-        len = 16;
-    /* XXX: we could compress the chars to 7 bits to increase
-       entropy */
-    for(i = 0;i < len;i++) {
-        keybuf[i] = key[i];
-    }
-    s->crypt_method = s->crypt_method_header;
-
-    if (AES_set_encrypt_key(keybuf, 128, &s->aes_encrypt_key) != 0)
-        return -1;
-    if (AES_set_decrypt_key(keybuf, 128, &s->aes_decrypt_key) != 0)
-        return -1;
-#if 0
-    /* test */
-    {
-        uint8_t in[16];
-        uint8_t out[16];
-        uint8_t tmp[16];
-        for(i=0;i<16;i++)
-            in[i] = i;
-        AES_encrypt(in, tmp, &s->aes_encrypt_key);
-        AES_decrypt(tmp, out, &s->aes_decrypt_key);
-        for(i = 0; i < 16; i++)
-            printf(" %02x", tmp[i]);
-        printf("\n");
-        for(i = 0; i < 16; i++)
-            printf(" %02x", out[i]);
-        printf("\n");
-    }
-#endif
-    return 0;
-}
-
-/* The crypt function is compatible with the linux cryptoloop
-   algorithm for < 4 GB images. NOTE: out_buf == in_buf is
-   supported */
-static void encrypt_sectors(BDRVQcowState *s, int64_t sector_num,
-                            uint8_t *out_buf, const uint8_t *in_buf,
-                            int nb_sectors, int enc,
-                            const AES_KEY *key)
-{
-    union {
-        uint64_t ll[2];
-        uint8_t b[16];
-    } ivec;
-    int i;
-
-    for(i = 0; i < nb_sectors; i++) {
-        ivec.ll[0] = cpu_to_le64(sector_num);
-        ivec.ll[1] = 0;
-        AES_cbc_encrypt(in_buf, out_buf, 512, key,
-                        ivec.b, enc);
-        sector_num++;
-        in_buf += 512;
-        out_buf += 512;
-    }
-}
-
-static int copy_sectors(BlockDriverState *bs, uint64_t start_sect,
-                        uint64_t cluster_offset, int n_start, int n_end)
-{
-    BDRVQcowState *s = bs->opaque;
-    int n, ret;
-
-    n = n_end - n_start;
-    if (n <= 0)
-        return 0;
-    ret = qcow_read(bs, start_sect + n_start, s->cluster_data, n);
-    if (ret < 0)
-        return ret;
-    if (s->crypt_method) {
-        encrypt_sectors(s, start_sect + n_start,
-                        s->cluster_data,
-                        s->cluster_data, n, 1,
-                        &s->aes_encrypt_key);
-    }
-    ret = bdrv_write(s->hd, (cluster_offset >> 9) + n_start,
-                     s->cluster_data, n);
-    if (ret < 0)
-        return ret;
-    return 0;
-}
-
-static void l2_cache_reset(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-
-    memset(s->l2_cache, 0, s->l2_size * L2_CACHE_SIZE * sizeof(uint64_t));
-    memset(s->l2_cache_offsets, 0, L2_CACHE_SIZE * sizeof(uint64_t));
-    memset(s->l2_cache_counts, 0, L2_CACHE_SIZE * sizeof(uint32_t));
-}
-
-static inline int l2_cache_new_entry(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    uint32_t min_count;
-    int min_index, i;
-
-    /* find a new entry in the least used one */
-    min_index = 0;
-    min_count = 0xffffffff;
-    for(i = 0; i < L2_CACHE_SIZE; i++) {
-        if (s->l2_cache_counts[i] < min_count) {
-            min_count = s->l2_cache_counts[i];
-            min_index = i;
-        }
-    }
-    return min_index;
-}
-
-static int64_t align_offset(int64_t offset, int n)
-{
-    offset = (offset + n - 1) & ~(n - 1);
-    return offset;
-}
-
-static int grow_l1_table(BlockDriverState *bs, int min_size)
-{
-    BDRVQcowState *s = bs->opaque;
-    int new_l1_size, new_l1_size2, ret, i;
-    uint64_t *new_l1_table;
-    uint64_t new_l1_table_offset;
-    uint8_t data[12];
-
-    new_l1_size = s->l1_size;
-    if (min_size <= new_l1_size)
-        return 0;
-    while (min_size > new_l1_size) {
-        new_l1_size = (new_l1_size * 3 + 1) / 2;
-    }
-#ifdef DEBUG_ALLOC2
-    printf("grow l1_table from %d to %d\n", s->l1_size, new_l1_size);
-#endif
-
-    new_l1_size2 = sizeof(uint64_t) * new_l1_size;
-    new_l1_table = qemu_mallocz(new_l1_size2);
-    memcpy(new_l1_table, s->l1_table, s->l1_size * sizeof(uint64_t));
-
-    /* write new table (align to cluster) */
-    new_l1_table_offset = alloc_clusters(bs, new_l1_size2);
-
-    for(i = 0; i < s->l1_size; i++)
-        new_l1_table[i] = cpu_to_be64(new_l1_table[i]);
-    ret = bdrv_pwrite(s->hd, new_l1_table_offset, new_l1_table, new_l1_size2);
-    if (ret != new_l1_size2)
-        goto fail;
-    for(i = 0; i < s->l1_size; i++)
-        new_l1_table[i] = be64_to_cpu(new_l1_table[i]);
-
-    /* set new table */
-    cpu_to_be32w((uint32_t*)data, new_l1_size);
-    cpu_to_be64w((uint64_t*)(data + 4), new_l1_table_offset);
-    if (bdrv_pwrite(s->hd, offsetof(QCowHeader, l1_size), data,
-                sizeof(data)) != sizeof(data))
-        goto fail;
-    qemu_free(s->l1_table);
-    free_clusters(bs, s->l1_table_offset, s->l1_size * sizeof(uint64_t));
-    s->l1_table_offset = new_l1_table_offset;
-    s->l1_table = new_l1_table;
-    s->l1_size = new_l1_size;
-    return 0;
- fail:
-    qemu_free(s->l1_table);
-    return -EIO;
-}
-
-/*
- * seek_l2_table
- *
- * seek l2_offset in the l2_cache table
- * if not found, return NULL,
- * if found,
- *   increments the l2 cache hit count of the entry,
- *   if counter overflow, divide by two all counters
- *   return the pointer to the l2 cache entry
- *
- */
-
-static uint64_t *seek_l2_table(BDRVQcowState *s, uint64_t l2_offset)
-{
-    int i, j;
-
-    for(i = 0; i < L2_CACHE_SIZE; i++) {
-        if (l2_offset == s->l2_cache_offsets[i]) {
-            /* increment the hit count */
-            if (++s->l2_cache_counts[i] == 0xffffffff) {
-                for(j = 0; j < L2_CACHE_SIZE; j++) {
-                    s->l2_cache_counts[j] >>= 1;
-                }
-            }
-            return s->l2_cache + (i << s->l2_bits);
-        }
-    }
-    return NULL;
-}
-
-/*
- * 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 uint64_t *l2_load(BlockDriverState *bs, uint64_t l2_offset)
-{
-    BDRVQcowState *s = bs->opaque;
-    int min_index;
-    uint64_t *l2_table;
-
-    /* seek if the table for the given offset is in the cache */
-
-    l2_table = seek_l2_table(s, l2_offset);
-    if (l2_table != NULL)
-        return l2_table;
-
-    /* not found: load a new entry in the least used one */
-
-    min_index = l2_cache_new_entry(bs);
-    l2_table = s->l2_cache + (min_index << s->l2_bits);
-    if (bdrv_pread(s->hd, l2_offset, l2_table, s->l2_size * sizeof(uint64_t)) !=
-        s->l2_size * sizeof(uint64_t))
-        return NULL;
-    s->l2_cache_offsets[min_index] = l2_offset;
-    s->l2_cache_counts[min_index] = 1;
-
-    return l2_table;
-}
-
-/*
- * 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 uint64_t *l2_allocate(BlockDriverState *bs, int l1_index)
-{
-    BDRVQcowState *s = bs->opaque;
-    int min_index;
-    uint64_t old_l2_offset, tmp;
-    uint64_t *l2_table, l2_offset;
-
-    old_l2_offset = s->l1_table[l1_index];
-
-    /* allocate a new l2 entry */
-
-    l2_offset = alloc_clusters(bs, s->l2_size * sizeof(uint64_t));
-
-    /* update the L1 entry */
-
-    s->l1_table[l1_index] = l2_offset | QCOW_OFLAG_COPIED;
-
-    tmp = cpu_to_be64(l2_offset | QCOW_OFLAG_COPIED);
-    if (bdrv_pwrite(s->hd, s->l1_table_offset + l1_index * sizeof(tmp),
-                    &tmp, sizeof(tmp)) != sizeof(tmp))
-        return NULL;
-
-    /* allocate a new entry in the l2 cache */
-
-    min_index = l2_cache_new_entry(bs);
-    l2_table = s->l2_cache + (min_index << s->l2_bits);
-
-    if (old_l2_offset == 0) {
-        /* if there was no old l2 table, clear the new table */
-        memset(l2_table, 0, s->l2_size * sizeof(uint64_t));
-    } else {
-        /* if there was an old l2 table, read it from the disk */
-        if (bdrv_pread(s->hd, old_l2_offset,
-                       l2_table, s->l2_size * sizeof(uint64_t)) !=
-            s->l2_size * sizeof(uint64_t))
-            return NULL;
-    }
-    /* write the l2 table to the file */
-    if (bdrv_pwrite(s->hd, l2_offset,
-                    l2_table, s->l2_size * sizeof(uint64_t)) !=
-        s->l2_size * sizeof(uint64_t))
-        return NULL;
-
-    /* update the l2 cache entry */
-
-    s->l2_cache_offsets[min_index] = l2_offset;
-    s->l2_cache_counts[min_index] = 1;
-
-    return l2_table;
-}
-
-static int size_to_clusters(BDRVQcowState *s, int64_t size)
-{
-    return (size + (s->cluster_size - 1)) >> s->cluster_bits;
-}
-
-static int count_contiguous_clusters(uint64_t nb_clusters, int cluster_size,
-        uint64_t *l2_table, uint64_t start, uint64_t mask)
-{
-    int i;
-    uint64_t offset = be64_to_cpu(l2_table[0]) & ~mask;
-
-    if (!offset)
-        return 0;
-
-    for (i = start; i < start + nb_clusters; i++)
-        if (offset + i * cluster_size != (be64_to_cpu(l2_table[i]) & ~mask))
-            break;
-
-	return (i - start);
-}
-
-static int count_contiguous_free_clusters(uint64_t nb_clusters, uint64_t *l2_table)
-{
-    int i = 0;
-
-    while(nb_clusters-- && l2_table[i] == 0)
-        i++;
-
-    return i;
-}
-
-/*
- * get_cluster_offset
- *
- * For a given offset of the disk image, return cluster offset in
- * qcow2 file.
- *
- * on entry, *num is the number of contiguous clusters we'd like to
- * access following offset.
- *
- * on exit, *num is the number of contiguous clusters we can read.
- *
- * Return 1, if the offset is found
- * Return 0, otherwise.
- *
- */
-
-static uint64_t get_cluster_offset(BlockDriverState *bs,
-                                   uint64_t offset, int *num)
-{
-    BDRVQcowState *s = bs->opaque;
-    int l1_index, l2_index;
-    uint64_t l2_offset, *l2_table, cluster_offset;
-    int l1_bits, c;
-    int index_in_cluster, nb_available, nb_needed, nb_clusters;
-
-    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 = (1 << l1_bits) - (offset & ((1 << 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;
-    }
-
-    cluster_offset = 0;
-
-    /* seek the the l2 offset in the l1 table */
-
-    l1_index = offset >> l1_bits;
-    if (l1_index >= s->l1_size)
-        goto out;
-
-    l2_offset = s->l1_table[l1_index];
-
-    /* seek the l2 table of the given l2 offset */
-
-    if (!l2_offset)
-        goto out;
-
-    /* load the l2 table in memory */
-
-    l2_offset &= ~QCOW_OFLAG_COPIED;
-    l2_table = l2_load(bs, l2_offset);
-    if (l2_table == NULL)
-        return 0;
-
-    /* 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_clusters = size_to_clusters(s, nb_needed << 9);
-
-    if (!cluster_offset) {
-        /* how many empty clusters ? */
-        c = count_contiguous_free_clusters(nb_clusters, &l2_table[l2_index]);
-    } else {
-        /* how many allocated clusters ? */
-        c = count_contiguous_clusters(nb_clusters, s->cluster_size,
-                &l2_table[l2_index], 0, QCOW_OFLAG_COPIED);
-    }
-
-   nb_available = (c * s->cluster_sectors);
-out:
-    if (nb_available > nb_needed)
-        nb_available = nb_needed;
-
-    *num = nb_available - index_in_cluster;
-
-    return cluster_offset & ~QCOW_OFLAG_COPIED;
-}
-
-/*
- * free_any_clusters
- *
- * free clusters according to its type: compressed or not
- *
- */
-
-static void free_any_clusters(BlockDriverState *bs,
-                              uint64_t cluster_offset, int nb_clusters)
-{
-    BDRVQcowState *s = bs->opaque;
-
-    /* free the cluster */
-
-    if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
-        int nb_csectors;
-        nb_csectors = ((cluster_offset >> s->csize_shift) &
-                       s->csize_mask) + 1;
-        free_clusters(bs, (cluster_offset & s->cluster_offset_mask) & ~511,
-                      nb_csectors * 512);
-        return;
-    }
-
-    free_clusters(bs, cluster_offset, nb_clusters << s->cluster_bits);
-
-    return;
-}
-
-/*
- * 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.
- *
- */
-
-static int get_cluster_table(BlockDriverState *bs, uint64_t offset,
-                             uint64_t **new_l2_table,
-                             uint64_t *new_l2_offset,
-                             int *new_l2_index)
-{
-    BDRVQcowState *s = bs->opaque;
-    int l1_index, l2_index, ret;
-    uint64_t l2_offset, *l2_table;
-
-    /* seek the the l2 offset in the l1 table */
-
-    l1_index = offset >> (s->l2_bits + s->cluster_bits);
-    if (l1_index >= s->l1_size) {
-        ret = grow_l1_table(bs, l1_index + 1);
-        if (ret < 0)
-            return 0;
-    }
-    l2_offset = s->l1_table[l1_index];
-
-    /* seek the l2 table of the given l2 offset */
-
-    if (l2_offset & QCOW_OFLAG_COPIED) {
-        /* load the l2 table in memory */
-        l2_offset &= ~QCOW_OFLAG_COPIED;
-        l2_table = l2_load(bs, l2_offset);
-        if (l2_table == NULL)
-            return 0;
-    } else {
-        if (l2_offset)
-            free_clusters(bs, l2_offset, s->l2_size * sizeof(uint64_t));
-        l2_table = l2_allocate(bs, l1_index);
-        if (l2_table == NULL)
-            return 0;
-        l2_offset = s->l1_table[l1_index] & ~QCOW_OFLAG_COPIED;
-    }
-
-    /* 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_offset = l2_offset;
-    *new_l2_index = l2_index;
-
-    return 1;
-}
-
-/*
- * 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.
- *
- */
-
-static uint64_t alloc_compressed_cluster_offset(BlockDriverState *bs,
-                                                uint64_t offset,
-                                                int compressed_size)
-{
-    BDRVQcowState *s = bs->opaque;
-    int l2_index, ret;
-    uint64_t l2_offset, *l2_table, cluster_offset;
-    int nb_csectors;
-
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
-    if (ret == 0)
-        return 0;
-
-    cluster_offset = be64_to_cpu(l2_table[l2_index]);
-    if (cluster_offset & QCOW_OFLAG_COPIED)
-        return cluster_offset & ~QCOW_OFLAG_COPIED;
-
-    if (cluster_offset)
-        free_any_clusters(bs, cluster_offset, 1);
-
-    cluster_offset = alloc_bytes(bs, compressed_size);
-    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 */
-
-    l2_table[l2_index] = cpu_to_be64(cluster_offset);
-    if (bdrv_pwrite(s->hd,
-                    l2_offset + l2_index * sizeof(uint64_t),
-                    l2_table + l2_index,
-                    sizeof(uint64_t)) != sizeof(uint64_t))
-        return 0;
-
-    return cluster_offset;
-}
-
-typedef struct QCowL2Meta
-{
-    uint64_t offset;
-    int n_start;
-    int nb_available;
-    int nb_clusters;
-} QCowL2Meta;
-
-static int alloc_cluster_link_l2(BlockDriverState *bs, uint64_t cluster_offset,
-        QCowL2Meta *m)
-{
-    BDRVQcowState *s = bs->opaque;
-    int i, j = 0, l2_index, ret;
-    uint64_t *old_cluster, start_sect, l2_offset, *l2_table;
-
-    if (m->nb_clusters == 0)
-        return 0;
-
-    old_cluster = qemu_malloc(m->nb_clusters * sizeof(uint64_t));
-
-    /* copy content of unmodified sectors */
-    start_sect = (m->offset & ~(s->cluster_size - 1)) >> 9;
-    if (m->n_start) {
-        ret = copy_sectors(bs, start_sect, cluster_offset, 0, m->n_start);
-        if (ret < 0)
-            goto err;
-    }
-
-    if (m->nb_available & (s->cluster_sectors - 1)) {
-        uint64_t end = m->nb_available & ~(uint64_t)(s->cluster_sectors - 1);
-        ret = copy_sectors(bs, start_sect + end, cluster_offset + (end << 9),
-                m->nb_available - end, s->cluster_sectors);
-        if (ret < 0)
-            goto err;
-    }
-
-    ret = -EIO;
-    /* update L2 table */
-    if (!get_cluster_table(bs, m->offset, &l2_table, &l2_offset, &l2_index))
-        goto err;
-
-    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);
-     }
-
-    if (bdrv_pwrite(s->hd, l2_offset + l2_index * sizeof(uint64_t),
-                l2_table + l2_index, m->nb_clusters * sizeof(uint64_t)) !=
-            m->nb_clusters * sizeof(uint64_t))
-        goto err;
-
-    for (i = 0; i < j; i++)
-        free_any_clusters(bs, be64_to_cpu(old_cluster[i]) & ~QCOW_OFLAG_COPIED,
-                          1);
-
-    ret = 0;
-err:
-    qemu_free(old_cluster);
-    return ret;
- }
-
-/*
- * alloc_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 cluster.
- *
- * Return the cluster offset if successful,
- * Return 0, otherwise.
- *
- */
-
-static uint64_t alloc_cluster_offset(BlockDriverState *bs,
-                                     uint64_t offset,
-                                     int n_start, int n_end,
-                                     int *num, QCowL2Meta *m)
-{
-    BDRVQcowState *s = bs->opaque;
-    int l2_index, ret;
-    uint64_t l2_offset, *l2_table, cluster_offset;
-    int nb_clusters, i = 0;
-
-    ret = get_cluster_table(bs, offset, &l2_table, &l2_offset, &l2_index);
-    if (ret == 0)
-        return 0;
-
-    nb_clusters = size_to_clusters(s, n_end << 9);
-
-    nb_clusters = MIN(nb_clusters, s->l2_size - l2_index);
-
-    cluster_offset = be64_to_cpu(l2_table[l2_index]);
-
-    /* We keep all QCOW_OFLAG_COPIED clusters */
-
-    if (cluster_offset & QCOW_OFLAG_COPIED) {
-        nb_clusters = count_contiguous_clusters(nb_clusters, s->cluster_size,
-                &l2_table[l2_index], 0, 0);
-
-        cluster_offset &= ~QCOW_OFLAG_COPIED;
-        m->nb_clusters = 0;
-
-        goto out;
-    }
-
-    /* for the moment, multiple compressed clusters are not managed */
-
-    if (cluster_offset & QCOW_OFLAG_COMPRESSED)
-        nb_clusters = 1;
-
-    /* how many available clusters ? */
-
-    while (i < nb_clusters) {
-        i += count_contiguous_clusters(nb_clusters - i, s->cluster_size,
-                &l2_table[l2_index], i, 0);
-
-        if(be64_to_cpu(l2_table[l2_index + i]))
-            break;
-
-        i += count_contiguous_free_clusters(nb_clusters - i,
-                &l2_table[l2_index + i]);
-
-        cluster_offset = be64_to_cpu(l2_table[l2_index + i]);
-
-        if ((cluster_offset & QCOW_OFLAG_COPIED) ||
-                (cluster_offset & QCOW_OFLAG_COMPRESSED))
-            break;
-    }
-    nb_clusters = i;
-
-    /* allocate a new cluster */
-
-    cluster_offset = alloc_clusters(bs, nb_clusters * s->cluster_size);
-
-    /* save info needed for meta data update */
-    m->offset = offset;
-    m->n_start = n_start;
-    m->nb_clusters = nb_clusters;
-
-out:
-    m->nb_available = MIN(nb_clusters << (s->cluster_bits - 9), n_end);
-
-    *num = m->nb_available - n_start;
-
-    return cluster_offset;
-}
-
-static int qcow_is_allocated(BlockDriverState *bs, int64_t sector_num,
-                             int nb_sectors, int *pnum)
-{
-    uint64_t cluster_offset;
-
-    *pnum = nb_sectors;
-    cluster_offset = get_cluster_offset(bs, sector_num << 9, pnum);
-
-    return (cluster_offset != 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;
-}
-
-static int decompress_cluster(BDRVQcowState *s, uint64_t cluster_offset)
-{
-    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;
-        ret = bdrv_read(s->hd, coffset >> 9, s->cluster_data, nb_csectors);
-        if (ret < 0) {
-            return -1;
-        }
-        if (decompress_buffer(s->cluster_cache, s->cluster_size,
-                              s->cluster_data + sector_offset, csize) < 0) {
-            return -1;
-        }
-        s->cluster_cache_offset = coffset;
-    }
-    return 0;
-}
-
-/* handle reading after the end of the backing file */
-static int backing_read1(BlockDriverState *bs,
-                         int64_t sector_num, uint8_t *buf, int nb_sectors)
-{
-    int n1;
-    if ((sector_num + nb_sectors) <= bs->total_sectors)
-        return nb_sectors;
-    if (sector_num >= bs->total_sectors)
-        n1 = 0;
-    else
-        n1 = bs->total_sectors - sector_num;
-    memset(buf + n1 * 512, 0, 512 * (nb_sectors - n1));
-    return n1;
-}
-
-static int qcow_read(BlockDriverState *bs, int64_t sector_num,
-                     uint8_t *buf, int nb_sectors)
-{
-    BDRVQcowState *s = bs->opaque;
-    int ret, index_in_cluster, n, n1;
-    uint64_t cluster_offset;
-
-    while (nb_sectors > 0) {
-        n = nb_sectors;
-        cluster_offset = get_cluster_offset(bs, sector_num << 9, &n);
-        index_in_cluster = sector_num & (s->cluster_sectors - 1);
-        if (!cluster_offset) {
-            if (bs->backing_hd) {
-                /* read from the base image */
-                n1 = backing_read1(bs->backing_hd, sector_num, buf, n);
-                if (n1 > 0) {
-                    ret = bdrv_read(bs->backing_hd, sector_num, buf, n1);
-                    if (ret < 0)
-                        return -1;
-                }
-            } else {
-                memset(buf, 0, 512 * n);
-            }
-        } else if (cluster_offset & QCOW_OFLAG_COMPRESSED) {
-            if (decompress_cluster(s, cluster_offset) < 0)
-                return -1;
-            memcpy(buf, s->cluster_cache + index_in_cluster * 512, 512 * n);
-        } else {
-            ret = bdrv_pread(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
-            if (ret != n * 512)
-                return -1;
-            if (s->crypt_method) {
-                encrypt_sectors(s, sector_num, buf, buf, n, 0,
-                                &s->aes_decrypt_key);
-            }
-        }
-        nb_sectors -= n;
-        sector_num += n;
-        buf += n * 512;
-    }
-    return 0;
-}
-
-static int qcow_write(BlockDriverState *bs, int64_t sector_num,
-                     const uint8_t *buf, int nb_sectors)
-{
-    BDRVQcowState *s = bs->opaque;
-    int ret, index_in_cluster, n;
-    uint64_t cluster_offset;
-    int n_end;
-    QCowL2Meta l2meta;
-
-    while (nb_sectors > 0) {
-        index_in_cluster = sector_num & (s->cluster_sectors - 1);
-        n_end = index_in_cluster + nb_sectors;
-        if (s->crypt_method &&
-            n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors)
-            n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
-        cluster_offset = alloc_cluster_offset(bs, sector_num << 9,
-                                              index_in_cluster,
-                                              n_end, &n, &l2meta);
-        if (!cluster_offset)
-            return -1;
-        if (s->crypt_method) {
-            encrypt_sectors(s, sector_num, s->cluster_data, buf, n, 1,
-                            &s->aes_encrypt_key);
-            ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512,
-                              s->cluster_data, n * 512);
-        } else {
-            ret = bdrv_pwrite(s->hd, cluster_offset + index_in_cluster * 512, buf, n * 512);
-        }
-        if (ret != n * 512 || alloc_cluster_link_l2(bs, cluster_offset, &l2meta) < 0) {
-            free_any_clusters(bs, cluster_offset, l2meta.nb_clusters);
-            return -1;
-        }
-        nb_sectors -= n;
-        sector_num += n;
-        buf += n * 512;
-    }
-    s->cluster_cache_offset = -1; /* disable compressed cache */
-    return 0;
-}
-
-typedef struct QCowAIOCB {
-    BlockDriverAIOCB common;
-    int64_t sector_num;
-    QEMUIOVector *qiov;
-    uint8_t *buf;
-    void *orig_buf;
-    int nb_sectors;
-    int n;
-    uint64_t cluster_offset;
-    uint8_t *cluster_data;
-    BlockDriverAIOCB *hd_aiocb;
-    struct iovec hd_iov;
-    QEMUIOVector hd_qiov;
-    QEMUBH *bh;
-    QCowL2Meta l2meta;
-} QCowAIOCB;
-
-static void qcow_aio_read_cb(void *opaque, int ret);
-static void qcow_aio_read_bh(void *opaque)
-{
-    QCowAIOCB *acb = opaque;
-    qemu_bh_delete(acb->bh);
-    acb->bh = NULL;
-    qcow_aio_read_cb(opaque, 0);
-}
-
-static int qcow_schedule_bh(QEMUBHFunc *cb, QCowAIOCB *acb)
-{
-    if (acb->bh)
-        return -EIO;
-
-    acb->bh = qemu_bh_new(cb, acb);
-    if (!acb->bh)
-        return -EIO;
-
-    qemu_bh_schedule(acb->bh);
-
-    return 0;
-}
-
-static void qcow_aio_read_cb(void *opaque, int ret)
-{
-    QCowAIOCB *acb = opaque;
-    BlockDriverState *bs = acb->common.bs;
-    BDRVQcowState *s = bs->opaque;
-    int index_in_cluster, n1;
-
-    acb->hd_aiocb = NULL;
-    if (ret < 0)
-        goto done;
-
-    /* post process the read buffer */
-    if (!acb->cluster_offset) {
-        /* nothing to do */
-    } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
-        /* nothing to do */
-    } else {
-        if (s->crypt_method) {
-            encrypt_sectors(s, acb->sector_num, acb->buf, acb->buf,
-                            acb->n, 0,
-                            &s->aes_decrypt_key);
-        }
-    }
-
-    acb->nb_sectors -= acb->n;
-    acb->sector_num += acb->n;
-    acb->buf += acb->n * 512;
-
-    if (acb->nb_sectors == 0) {
-        /* request completed */
-        ret = 0;
-        goto done;
-    }
-
-    /* prepare next AIO request */
-    acb->n = acb->nb_sectors;
-    acb->cluster_offset = get_cluster_offset(bs, acb->sector_num << 9, &acb->n);
-    index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
-
-    if (!acb->cluster_offset) {
-        if (bs->backing_hd) {
-            /* read from the base image */
-            n1 = backing_read1(bs->backing_hd, acb->sector_num,
-                               acb->buf, acb->n);
-            if (n1 > 0) {
-                acb->hd_iov.iov_base = (void *)acb->buf;
-                acb->hd_iov.iov_len = acb->n * 512;
-                qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-                acb->hd_aiocb = bdrv_aio_readv(bs->backing_hd, acb->sector_num,
-                                    &acb->hd_qiov, acb->n,
-				    qcow_aio_read_cb, acb);
-                if (acb->hd_aiocb == NULL)
-                    goto done;
-            } else {
-                ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
-                if (ret < 0)
-                    goto done;
-            }
-        } else {
-            /* Note: in this case, no need to wait */
-            memset(acb->buf, 0, 512 * acb->n);
-            ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
-            if (ret < 0)
-                goto done;
-        }
-    } else if (acb->cluster_offset & QCOW_OFLAG_COMPRESSED) {
-        /* add AIO support for compressed blocks ? */
-        if (decompress_cluster(s, acb->cluster_offset) < 0)
-            goto done;
-        memcpy(acb->buf,
-               s->cluster_cache + index_in_cluster * 512, 512 * acb->n);
-        ret = qcow_schedule_bh(qcow_aio_read_bh, acb);
-        if (ret < 0)
-            goto done;
-    } else {
-        if ((acb->cluster_offset & 511) != 0) {
-            ret = -EIO;
-            goto done;
-        }
-
-        acb->hd_iov.iov_base = (void *)acb->buf;
-        acb->hd_iov.iov_len = acb->n * 512;
-        qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-        acb->hd_aiocb = bdrv_aio_readv(s->hd,
-                            (acb->cluster_offset >> 9) + index_in_cluster,
-                            &acb->hd_qiov, acb->n, qcow_aio_read_cb, acb);
-        if (acb->hd_aiocb == NULL)
-            goto done;
-    }
-
-    return;
-done:
-    if (acb->qiov->niov > 1) {
-        qemu_iovec_from_buffer(acb->qiov, acb->orig_buf, acb->qiov->size);
-        qemu_vfree(acb->orig_buf);
-    }
-    acb->common.cb(acb->common.opaque, ret);
-    qemu_aio_release(acb);
-}
-
-static QCowAIOCB *qcow_aio_setup(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque, int is_write)
-{
-    QCowAIOCB *acb;
-
-    acb = qemu_aio_get(bs, cb, opaque);
-    if (!acb)
-        return NULL;
-    acb->hd_aiocb = NULL;
-    acb->sector_num = sector_num;
-    acb->qiov = qiov;
-    if (qiov->niov > 1) {
-        acb->buf = acb->orig_buf = qemu_blockalign(bs, qiov->size);
-        if (is_write)
-            qemu_iovec_to_buffer(qiov, acb->buf);
-    } else {
-        acb->buf = (uint8_t *)qiov->iov->iov_base;
-    }
-    acb->nb_sectors = nb_sectors;
-    acb->n = 0;
-    acb->cluster_offset = 0;
-    acb->l2meta.nb_clusters = 0;
-    return acb;
-}
-
-static BlockDriverAIOCB *qcow_aio_readv(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque)
-{
-    QCowAIOCB *acb;
-
-    acb = qcow_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 0);
-    if (!acb)
-        return NULL;
-
-    qcow_aio_read_cb(acb, 0);
-    return &acb->common;
-}
-
-static void qcow_aio_write_cb(void *opaque, int ret)
-{
-    QCowAIOCB *acb = opaque;
-    BlockDriverState *bs = acb->common.bs;
-    BDRVQcowState *s = bs->opaque;
-    int index_in_cluster;
-    const uint8_t *src_buf;
-    int n_end;
-
-    acb->hd_aiocb = NULL;
-
-    if (ret < 0)
-        goto done;
-
-    if (alloc_cluster_link_l2(bs, acb->cluster_offset, &acb->l2meta) < 0) {
-        free_any_clusters(bs, acb->cluster_offset, acb->l2meta.nb_clusters);
-        goto done;
-    }
-
-    acb->nb_sectors -= acb->n;
-    acb->sector_num += acb->n;
-    acb->buf += acb->n * 512;
-
-    if (acb->nb_sectors == 0) {
-        /* request completed */
-        ret = 0;
-        goto done;
-    }
-
-    index_in_cluster = acb->sector_num & (s->cluster_sectors - 1);
-    n_end = index_in_cluster + acb->nb_sectors;
-    if (s->crypt_method &&
-        n_end > QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors)
-        n_end = QCOW_MAX_CRYPT_CLUSTERS * s->cluster_sectors;
-
-    acb->cluster_offset = alloc_cluster_offset(bs, acb->sector_num << 9,
-                                          index_in_cluster,
-                                          n_end, &acb->n, &acb->l2meta);
-    if (!acb->cluster_offset || (acb->cluster_offset & 511) != 0) {
-        ret = -EIO;
-        goto done;
-    }
-    if (s->crypt_method) {
-        if (!acb->cluster_data) {
-            acb->cluster_data = qemu_mallocz(QCOW_MAX_CRYPT_CLUSTERS *
-                                             s->cluster_size);
-        }
-        encrypt_sectors(s, acb->sector_num, acb->cluster_data, acb->buf,
-                        acb->n, 1, &s->aes_encrypt_key);
-        src_buf = acb->cluster_data;
-    } else {
-        src_buf = acb->buf;
-    }
-    acb->hd_iov.iov_base = (void *)src_buf;
-    acb->hd_iov.iov_len = acb->n * 512;
-    qemu_iovec_init_external(&acb->hd_qiov, &acb->hd_iov, 1);
-    acb->hd_aiocb = bdrv_aio_writev(s->hd,
-                                    (acb->cluster_offset >> 9) + index_in_cluster,
-                                    &acb->hd_qiov, acb->n,
-                                    qcow_aio_write_cb, acb);
-    if (acb->hd_aiocb == NULL)
-        goto done;
-
-    return;
-
-done:
-    if (acb->qiov->niov > 1)
-        qemu_vfree(acb->orig_buf);
-    acb->common.cb(acb->common.opaque, ret);
-    qemu_aio_release(acb);
-}
-
-static BlockDriverAIOCB *qcow_aio_writev(BlockDriverState *bs,
-        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
-        BlockDriverCompletionFunc *cb, void *opaque)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowAIOCB *acb;
-
-    s->cluster_cache_offset = -1; /* disable compressed cache */
-
-    acb = qcow_aio_setup(bs, sector_num, qiov, nb_sectors, cb, opaque, 1);
-    if (!acb)
-        return NULL;
-
-    qcow_aio_write_cb(acb, 0);
-    return &acb->common;
-}
-
-static void qcow_aio_cancel(BlockDriverAIOCB *blockacb)
-{
-    QCowAIOCB *acb = (QCowAIOCB *)blockacb;
-    if (acb->hd_aiocb)
-        bdrv_aio_cancel(acb->hd_aiocb);
-    qemu_aio_release(acb);
-}
-
-static void qcow_close(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    qemu_free(s->l1_table);
-    qemu_free(s->l2_cache);
-    qemu_free(s->cluster_cache);
-    qemu_free(s->cluster_data);
-    refcount_close(bs);
-    bdrv_delete(s->hd);
-}
-
-/* XXX: use std qcow open function ? */
-typedef struct QCowCreateState {
-    int cluster_size;
-    int cluster_bits;
-    uint16_t *refcount_block;
-    uint64_t *refcount_table;
-    int64_t l1_table_offset;
-    int64_t refcount_table_offset;
-    int64_t refcount_block_offset;
-} QCowCreateState;
-
-static void create_refcount_update(QCowCreateState *s,
-                                   int64_t offset, int64_t size)
-{
-    int refcount;
-    int64_t start, last, cluster_offset;
-    uint16_t *p;
-
-    start = offset & ~(s->cluster_size - 1);
-    last = (offset + size - 1)  & ~(s->cluster_size - 1);
-    for(cluster_offset = start; cluster_offset <= last;
-        cluster_offset += s->cluster_size) {
-        p = &s->refcount_block[cluster_offset >> s->cluster_bits];
-        refcount = be16_to_cpu(*p);
-        refcount++;
-        *p = cpu_to_be16(refcount);
-    }
-}
-
-static int qcow_create2(const char *filename, int64_t total_size,
-                        const char *backing_file, const char *backing_format,
-                        int flags)
-{
-
-    int fd, header_size, backing_filename_len, l1_size, i, shift, l2_bits;
-    int ref_clusters, backing_format_len = 0;
-    QCowHeader header;
-    uint64_t tmp, offset;
-    QCowCreateState s1, *s = &s1;
-    QCowExtension ext_bf = {0, 0};
-
-
-    memset(s, 0, sizeof(*s));
-
-    fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, 0644);
-    if (fd < 0)
-        return -1;
-    memset(&header, 0, sizeof(header));
-    header.magic = cpu_to_be32(QCOW_MAGIC);
-    header.version = cpu_to_be32(QCOW_VERSION);
-    header.size = cpu_to_be64(total_size * 512);
-    header_size = sizeof(header);
-    backing_filename_len = 0;
-    if (backing_file) {
-        if (backing_format) {
-            ext_bf.magic = QCOW_EXT_MAGIC_BACKING_FORMAT;
-            backing_format_len = strlen(backing_format);
-            ext_bf.len = (backing_format_len + 7) & ~7;
-            header_size += ((sizeof(ext_bf) + ext_bf.len + 7) & ~7);
-        }
-        header.backing_file_offset = cpu_to_be64(header_size);
-        backing_filename_len = strlen(backing_file);
-        header.backing_file_size = cpu_to_be32(backing_filename_len);
-        header_size += backing_filename_len;
-    }
-    s->cluster_bits = 12;  /* 4 KB clusters */
-    s->cluster_size = 1 << s->cluster_bits;
-    header.cluster_bits = cpu_to_be32(s->cluster_bits);
-    header_size = (header_size + 7) & ~7;
-    if (flags & BLOCK_FLAG_ENCRYPT) {
-        header.crypt_method = cpu_to_be32(QCOW_CRYPT_AES);
-    } else {
-        header.crypt_method = cpu_to_be32(QCOW_CRYPT_NONE);
-    }
-    l2_bits = s->cluster_bits - 3;
-    shift = s->cluster_bits + l2_bits;
-    l1_size = (((total_size * 512) + (1LL << shift) - 1) >> shift);
-    offset = align_offset(header_size, s->cluster_size);
-    s->l1_table_offset = offset;
-    header.l1_table_offset = cpu_to_be64(s->l1_table_offset);
-    header.l1_size = cpu_to_be32(l1_size);
-    offset += align_offset(l1_size * sizeof(uint64_t), s->cluster_size);
-
-    s->refcount_table = qemu_mallocz(s->cluster_size);
-
-    s->refcount_table_offset = offset;
-    header.refcount_table_offset = cpu_to_be64(offset);
-    header.refcount_table_clusters = cpu_to_be32(1);
-    offset += s->cluster_size;
-    s->refcount_block_offset = offset;
-
-    /* count how many refcount blocks needed */
-    tmp = offset >> s->cluster_bits;
-    ref_clusters = (tmp >> (s->cluster_bits - REFCOUNT_SHIFT)) + 1;
-    for (i=0; i < ref_clusters; i++) {
-        s->refcount_table[i] = cpu_to_be64(offset);
-        offset += s->cluster_size;
-    }
-
-    s->refcount_block = qemu_mallocz(ref_clusters * s->cluster_size);
-
-    /* update refcounts */
-    create_refcount_update(s, 0, header_size);
-    create_refcount_update(s, s->l1_table_offset, l1_size * sizeof(uint64_t));
-    create_refcount_update(s, s->refcount_table_offset, s->cluster_size);
-    create_refcount_update(s, s->refcount_block_offset, ref_clusters * s->cluster_size);
-
-    /* write all the data */
-    write(fd, &header, sizeof(header));
-    if (backing_file) {
-        if (backing_format_len) {
-            char zero[16];
-            int d = ext_bf.len - backing_format_len;
-
-            memset(zero, 0, sizeof(zero));
-            cpu_to_be32s(&ext_bf.magic);
-            cpu_to_be32s(&ext_bf.len);
-            write(fd, &ext_bf, sizeof(ext_bf));
-            write(fd, backing_format, backing_format_len);
-            if (d>0) {
-                write(fd, zero, d);
-            }
-        }
-        write(fd, backing_file, backing_filename_len);
-    }
-    lseek(fd, s->l1_table_offset, SEEK_SET);
-    tmp = 0;
-    for(i = 0;i < l1_size; i++) {
-        write(fd, &tmp, sizeof(tmp));
-    }
-    lseek(fd, s->refcount_table_offset, SEEK_SET);
-    write(fd, s->refcount_table, s->cluster_size);
-
-    lseek(fd, s->refcount_block_offset, SEEK_SET);
-    write(fd, s->refcount_block, ref_clusters * s->cluster_size);
-
-    qemu_free(s->refcount_table);
-    qemu_free(s->refcount_block);
-    close(fd);
-    return 0;
-}
-
-static int qcow_create(const char *filename, int64_t total_size,
-                       const char *backing_file, int flags)
-{
-    return qcow_create2(filename, total_size, backing_file, NULL, flags);
-}
-
-static int qcow_make_empty(BlockDriverState *bs)
-{
-#if 0
-    /* XXX: not correct */
-    BDRVQcowState *s = bs->opaque;
-    uint32_t l1_length = s->l1_size * sizeof(uint64_t);
-    int ret;
-
-    memset(s->l1_table, 0, l1_length);
-    if (bdrv_pwrite(s->hd, s->l1_table_offset, s->l1_table, l1_length) < 0)
-        return -1;
-    ret = bdrv_truncate(s->hd, s->l1_table_offset + l1_length);
-    if (ret < 0)
-        return ret;
-
-    l2_cache_reset(bs);
-#endif
-    return 0;
-}
-
-/* XXX: put compressed sectors first, then all the cluster aligned
-   tables to avoid losing bytes in alignment */
-static int qcow_write_compressed(BlockDriverState *bs, int64_t sector_num,
-                                 const uint8_t *buf, int nb_sectors)
-{
-    BDRVQcowState *s = bs->opaque;
-    z_stream strm;
-    int ret, out_len;
-    uint8_t *out_buf;
-    uint64_t cluster_offset;
-
-    if (nb_sectors == 0) {
-        /* align end of file to a sector boundary to ease reading with
-           sector based I/Os */
-        cluster_offset = bdrv_getlength(s->hd);
-        cluster_offset = (cluster_offset + 511) & ~511;
-        bdrv_truncate(s->hd, cluster_offset);
-        return 0;
-    }
-
-    if (nb_sectors != s->cluster_sectors)
-        return -EINVAL;
-
-    out_buf = qemu_malloc(s->cluster_size + (s->cluster_size / 1000) + 128);
-
-    /* best compression, small window, no zlib header */
-    memset(&strm, 0, sizeof(strm));
-    ret = deflateInit2(&strm, Z_DEFAULT_COMPRESSION,
-                       Z_DEFLATED, -12,
-                       9, Z_DEFAULT_STRATEGY);
-    if (ret != 0) {
-        qemu_free(out_buf);
-        return -1;
-    }
-
-    strm.avail_in = s->cluster_size;
-    strm.next_in = (uint8_t *)buf;
-    strm.avail_out = s->cluster_size;
-    strm.next_out = out_buf;
-
-    ret = deflate(&strm, Z_FINISH);
-    if (ret != Z_STREAM_END && ret != Z_OK) {
-        qemu_free(out_buf);
-        deflateEnd(&strm);
-        return -1;
-    }
-    out_len = strm.next_out - out_buf;
-
-    deflateEnd(&strm);
-
-    if (ret != Z_STREAM_END || out_len >= s->cluster_size) {
-        /* could not compress: write normal cluster */
-        qcow_write(bs, sector_num, buf, s->cluster_sectors);
-    } else {
-        cluster_offset = alloc_compressed_cluster_offset(bs, sector_num << 9,
-                                              out_len);
-        if (!cluster_offset)
-            return -1;
-        cluster_offset &= s->cluster_offset_mask;
-        if (bdrv_pwrite(s->hd, cluster_offset, out_buf, out_len) != out_len) {
-            qemu_free(out_buf);
-            return -1;
-        }
-    }
-
-    qemu_free(out_buf);
-    return 0;
-}
-
-static void qcow_flush(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    bdrv_flush(s->hd);
-}
-
-static int qcow_get_info(BlockDriverState *bs, BlockDriverInfo *bdi)
-{
-    BDRVQcowState *s = bs->opaque;
-    bdi->cluster_size = s->cluster_size;
-    bdi->vm_state_offset = (int64_t)s->l1_vm_state_index <<
-        (s->cluster_bits + s->l2_bits);
-    return 0;
-}
-
-/*********************************************************/
-/* snapshot support */
-
-/* update the refcounts of snapshots and the copied flag */
-static int update_snapshot_refcount(BlockDriverState *bs,
-                                    int64_t l1_table_offset,
-                                    int l1_size,
-                                    int addend)
-{
-    BDRVQcowState *s = bs->opaque;
-    uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated;
-    int64_t old_offset, old_l2_offset;
-    int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount;
-
-    l2_cache_reset(bs);
-
-    l2_table = NULL;
-    l1_table = NULL;
-    l1_size2 = l1_size * sizeof(uint64_t);
-    l1_allocated = 0;
-    if (l1_table_offset != s->l1_table_offset) {
-        l1_table = qemu_malloc(l1_size2);
-        l1_allocated = 1;
-        if (bdrv_pread(s->hd, l1_table_offset,
-                       l1_table, l1_size2) != l1_size2)
-            goto fail;
-        for(i = 0;i < l1_size; i++)
-            be64_to_cpus(&l1_table[i]);
-    } else {
-        assert(l1_size == s->l1_size);
-        l1_table = s->l1_table;
-        l1_allocated = 0;
-    }
-
-    l2_size = s->l2_size * sizeof(uint64_t);
-    l2_table = qemu_malloc(l2_size);
-    l1_modified = 0;
-    for(i = 0; i < l1_size; i++) {
-        l2_offset = l1_table[i];
-        if (l2_offset) {
-            old_l2_offset = l2_offset;
-            l2_offset &= ~QCOW_OFLAG_COPIED;
-            l2_modified = 0;
-            if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
-                goto fail;
-            for(j = 0; j < s->l2_size; j++) {
-                offset = be64_to_cpu(l2_table[j]);
-                if (offset != 0) {
-                    old_offset = offset;
-                    offset &= ~QCOW_OFLAG_COPIED;
-                    if (offset & QCOW_OFLAG_COMPRESSED) {
-                        nb_csectors = ((offset >> s->csize_shift) &
-                                       s->csize_mask) + 1;
-                        if (addend != 0)
-                            update_refcount(bs, (offset & s->cluster_offset_mask) & ~511,
-                                            nb_csectors * 512, addend);
-                        /* compressed clusters are never modified */
-                        refcount = 2;
-                    } else {
-                        if (addend != 0) {
-                            refcount = update_cluster_refcount(bs, offset >> s->cluster_bits, addend);
-                        } else {
-                            refcount = get_refcount(bs, offset >> s->cluster_bits);
-                        }
-                    }
-
-                    if (refcount == 1) {
-                        offset |= QCOW_OFLAG_COPIED;
-                    }
-                    if (offset != old_offset) {
-                        l2_table[j] = cpu_to_be64(offset);
-                        l2_modified = 1;
-                    }
-                }
-            }
-            if (l2_modified) {
-                if (bdrv_pwrite(s->hd,
-                                l2_offset, l2_table, l2_size) != l2_size)
-                    goto fail;
-            }
-
-            if (addend != 0) {
-                refcount = update_cluster_refcount(bs, l2_offset >> s->cluster_bits, addend);
-            } else {
-                refcount = get_refcount(bs, l2_offset >> s->cluster_bits);
-            }
-            if (refcount == 1) {
-                l2_offset |= QCOW_OFLAG_COPIED;
-            }
-            if (l2_offset != old_l2_offset) {
-                l1_table[i] = l2_offset;
-                l1_modified = 1;
-            }
-        }
-    }
-    if (l1_modified) {
-        for(i = 0; i < l1_size; i++)
-            cpu_to_be64s(&l1_table[i]);
-        if (bdrv_pwrite(s->hd, l1_table_offset, l1_table,
-                        l1_size2) != l1_size2)
-            goto fail;
-        for(i = 0; i < l1_size; i++)
-            be64_to_cpus(&l1_table[i]);
-    }
-    if (l1_allocated)
-        qemu_free(l1_table);
-    qemu_free(l2_table);
-    return 0;
- fail:
-    if (l1_allocated)
-        qemu_free(l1_table);
-    qemu_free(l2_table);
-    return -EIO;
-}
-
-static void qcow_free_snapshots(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    int i;
-
-    for(i = 0; i < s->nb_snapshots; i++) {
-        qemu_free(s->snapshots[i].name);
-        qemu_free(s->snapshots[i].id_str);
-    }
-    qemu_free(s->snapshots);
-    s->snapshots = NULL;
-    s->nb_snapshots = 0;
-}
-
-static int qcow_read_snapshots(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowSnapshotHeader h;
-    QCowSnapshot *sn;
-    int i, id_str_size, name_size;
-    int64_t offset;
-    uint32_t extra_data_size;
-
-    if (!s->nb_snapshots) {
-        s->snapshots = NULL;
-        s->snapshots_size = 0;
-        return 0;
-    }
-
-    offset = s->snapshots_offset;
-    s->snapshots = qemu_mallocz(s->nb_snapshots * sizeof(QCowSnapshot));
-    for(i = 0; i < s->nb_snapshots; i++) {
-        offset = align_offset(offset, 8);
-        if (bdrv_pread(s->hd, offset, &h, sizeof(h)) != sizeof(h))
-            goto fail;
-        offset += sizeof(h);
-        sn = s->snapshots + i;
-        sn->l1_table_offset = be64_to_cpu(h.l1_table_offset);
-        sn->l1_size = be32_to_cpu(h.l1_size);
-        sn->vm_state_size = be32_to_cpu(h.vm_state_size);
-        sn->date_sec = be32_to_cpu(h.date_sec);
-        sn->date_nsec = be32_to_cpu(h.date_nsec);
-        sn->vm_clock_nsec = be64_to_cpu(h.vm_clock_nsec);
-        extra_data_size = be32_to_cpu(h.extra_data_size);
-
-        id_str_size = be16_to_cpu(h.id_str_size);
-        name_size = be16_to_cpu(h.name_size);
-
-        offset += extra_data_size;
-
-        sn->id_str = qemu_malloc(id_str_size + 1);
-        if (bdrv_pread(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
-            goto fail;
-        offset += id_str_size;
-        sn->id_str[id_str_size] = '\0';
-
-        sn->name = qemu_malloc(name_size + 1);
-        if (bdrv_pread(s->hd, offset, sn->name, name_size) != name_size)
-            goto fail;
-        offset += name_size;
-        sn->name[name_size] = '\0';
-    }
-    s->snapshots_size = offset - s->snapshots_offset;
-    return 0;
- fail:
-    qcow_free_snapshots(bs);
-    return -1;
-}
-
-/* add at the end of the file a new list of snapshots */
-static int qcow_write_snapshots(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowSnapshot *sn;
-    QCowSnapshotHeader h;
-    int i, name_size, id_str_size, snapshots_size;
-    uint64_t data64;
-    uint32_t data32;
-    int64_t offset, snapshots_offset;
-
-    /* compute the size of the snapshots */
-    offset = 0;
-    for(i = 0; i < s->nb_snapshots; i++) {
-        sn = s->snapshots + i;
-        offset = align_offset(offset, 8);
-        offset += sizeof(h);
-        offset += strlen(sn->id_str);
-        offset += strlen(sn->name);
-    }
-    snapshots_size = offset;
-
-    snapshots_offset = alloc_clusters(bs, snapshots_size);
-    offset = snapshots_offset;
-
-    for(i = 0; i < s->nb_snapshots; i++) {
-        sn = s->snapshots + i;
-        memset(&h, 0, sizeof(h));
-        h.l1_table_offset = cpu_to_be64(sn->l1_table_offset);
-        h.l1_size = cpu_to_be32(sn->l1_size);
-        h.vm_state_size = cpu_to_be32(sn->vm_state_size);
-        h.date_sec = cpu_to_be32(sn->date_sec);
-        h.date_nsec = cpu_to_be32(sn->date_nsec);
-        h.vm_clock_nsec = cpu_to_be64(sn->vm_clock_nsec);
-
-        id_str_size = strlen(sn->id_str);
-        name_size = strlen(sn->name);
-        h.id_str_size = cpu_to_be16(id_str_size);
-        h.name_size = cpu_to_be16(name_size);
-        offset = align_offset(offset, 8);
-        if (bdrv_pwrite(s->hd, offset, &h, sizeof(h)) != sizeof(h))
-            goto fail;
-        offset += sizeof(h);
-        if (bdrv_pwrite(s->hd, offset, sn->id_str, id_str_size) != id_str_size)
-            goto fail;
-        offset += id_str_size;
-        if (bdrv_pwrite(s->hd, offset, sn->name, name_size) != name_size)
-            goto fail;
-        offset += name_size;
-    }
-
-    /* update the various header fields */
-    data64 = cpu_to_be64(snapshots_offset);
-    if (bdrv_pwrite(s->hd, offsetof(QCowHeader, snapshots_offset),
-                    &data64, sizeof(data64)) != sizeof(data64))
-        goto fail;
-    data32 = cpu_to_be32(s->nb_snapshots);
-    if (bdrv_pwrite(s->hd, offsetof(QCowHeader, nb_snapshots),
-                    &data32, sizeof(data32)) != sizeof(data32))
-        goto fail;
-
-    /* free the old snapshot table */
-    free_clusters(bs, s->snapshots_offset, s->snapshots_size);
-    s->snapshots_offset = snapshots_offset;
-    s->snapshots_size = snapshots_size;
-    return 0;
- fail:
-    return -1;
-}
-
-static void find_new_snapshot_id(BlockDriverState *bs,
-                                 char *id_str, int id_str_size)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowSnapshot *sn;
-    int i, id, id_max = 0;
-
-    for(i = 0; i < s->nb_snapshots; i++) {
-        sn = s->snapshots + i;
-        id = strtoul(sn->id_str, NULL, 10);
-        if (id > id_max)
-            id_max = id;
-    }
-    snprintf(id_str, id_str_size, "%d", id_max + 1);
-}
-
-static int find_snapshot_by_id(BlockDriverState *bs, const char *id_str)
-{
-    BDRVQcowState *s = bs->opaque;
-    int i;
-
-    for(i = 0; i < s->nb_snapshots; i++) {
-        if (!strcmp(s->snapshots[i].id_str, id_str))
-            return i;
-    }
-    return -1;
-}
-
-static int find_snapshot_by_id_or_name(BlockDriverState *bs, const char *name)
-{
-    BDRVQcowState *s = bs->opaque;
-    int i, ret;
-
-    ret = find_snapshot_by_id(bs, name);
-    if (ret >= 0)
-        return ret;
-    for(i = 0; i < s->nb_snapshots; i++) {
-        if (!strcmp(s->snapshots[i].name, name))
-            return i;
-    }
-    return -1;
-}
-
-/* if no id is provided, a new one is constructed */
-static int qcow_snapshot_create(BlockDriverState *bs,
-                                QEMUSnapshotInfo *sn_info)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowSnapshot *snapshots1, sn1, *sn = &sn1;
-    int i, ret;
-    uint64_t *l1_table = NULL;
-
-    memset(sn, 0, sizeof(*sn));
-
-    if (sn_info->id_str[0] == '\0') {
-        /* compute a new id */
-        find_new_snapshot_id(bs, sn_info->id_str, sizeof(sn_info->id_str));
-    }
-
-    /* check that the ID is unique */
-    if (find_snapshot_by_id(bs, sn_info->id_str) >= 0)
-        return -ENOENT;
-
-    sn->id_str = qemu_strdup(sn_info->id_str);
-    if (!sn->id_str)
-        goto fail;
-    sn->name = qemu_strdup(sn_info->name);
-    if (!sn->name)
-        goto fail;
-    sn->vm_state_size = sn_info->vm_state_size;
-    sn->date_sec = sn_info->date_sec;
-    sn->date_nsec = sn_info->date_nsec;
-    sn->vm_clock_nsec = sn_info->vm_clock_nsec;
-
-    ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1);
-    if (ret < 0)
-        goto fail;
-
-    /* create the L1 table of the snapshot */
-    sn->l1_table_offset = alloc_clusters(bs, s->l1_size * sizeof(uint64_t));
-    sn->l1_size = s->l1_size;
-
-    l1_table = qemu_malloc(s->l1_size * sizeof(uint64_t));
-    for(i = 0; i < s->l1_size; i++) {
-        l1_table[i] = cpu_to_be64(s->l1_table[i]);
-    }
-    if (bdrv_pwrite(s->hd, sn->l1_table_offset,
-                    l1_table, s->l1_size * sizeof(uint64_t)) !=
-        (s->l1_size * sizeof(uint64_t)))
-        goto fail;
-    qemu_free(l1_table);
-    l1_table = NULL;
-
-    snapshots1 = qemu_malloc((s->nb_snapshots + 1) * sizeof(QCowSnapshot));
-    if (s->snapshots) {
-        memcpy(snapshots1, s->snapshots, s->nb_snapshots * sizeof(QCowSnapshot));
-        qemu_free(s->snapshots);
-    }
-    s->snapshots = snapshots1;
-    s->snapshots[s->nb_snapshots++] = *sn;
-
-    if (qcow_write_snapshots(bs) < 0)
-        goto fail;
-#ifdef DEBUG_ALLOC
-    check_refcounts(bs);
-#endif
-    return 0;
- fail:
-    qemu_free(sn->name);
-    qemu_free(l1_table);
-    return -1;
-}
-
-/* copy the snapshot 'snapshot_name' into the current disk image */
-static int qcow_snapshot_goto(BlockDriverState *bs,
-                              const char *snapshot_id)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowSnapshot *sn;
-    int i, snapshot_index, l1_size2;
-
-    snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
-    if (snapshot_index < 0)
-        return -ENOENT;
-    sn = &s->snapshots[snapshot_index];
-
-    if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, -1) < 0)
-        goto fail;
-
-    if (grow_l1_table(bs, sn->l1_size) < 0)
-        goto fail;
-
-    s->l1_size = sn->l1_size;
-    l1_size2 = s->l1_size * sizeof(uint64_t);
-    /* copy the snapshot l1 table to the current l1 table */
-    if (bdrv_pread(s->hd, sn->l1_table_offset,
-                   s->l1_table, l1_size2) != l1_size2)
-        goto fail;
-    if (bdrv_pwrite(s->hd, s->l1_table_offset,
-                    s->l1_table, l1_size2) != l1_size2)
-        goto fail;
-    for(i = 0;i < s->l1_size; i++) {
-        be64_to_cpus(&s->l1_table[i]);
-    }
-
-    if (update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 1) < 0)
-        goto fail;
-
-#ifdef DEBUG_ALLOC
-    check_refcounts(bs);
-#endif
-    return 0;
- fail:
-    return -EIO;
-}
-
-static int qcow_snapshot_delete(BlockDriverState *bs, const char *snapshot_id)
-{
-    BDRVQcowState *s = bs->opaque;
-    QCowSnapshot *sn;
-    int snapshot_index, ret;
-
-    snapshot_index = find_snapshot_by_id_or_name(bs, snapshot_id);
-    if (snapshot_index < 0)
-        return -ENOENT;
-    sn = &s->snapshots[snapshot_index];
-
-    ret = update_snapshot_refcount(bs, sn->l1_table_offset, sn->l1_size, -1);
-    if (ret < 0)
-        return ret;
-    /* must update the copied flag on the current cluster offsets */
-    ret = update_snapshot_refcount(bs, s->l1_table_offset, s->l1_size, 0);
-    if (ret < 0)
-        return ret;
-    free_clusters(bs, sn->l1_table_offset, sn->l1_size * sizeof(uint64_t));
-
-    qemu_free(sn->id_str);
-    qemu_free(sn->name);
-    memmove(sn, sn + 1, (s->nb_snapshots - snapshot_index - 1) * sizeof(*sn));
-    s->nb_snapshots--;
-    ret = qcow_write_snapshots(bs);
-    if (ret < 0) {
-        /* XXX: restore snapshot if error ? */
-        return ret;
-    }
-#ifdef DEBUG_ALLOC
-    check_refcounts(bs);
-#endif
-    return 0;
-}
-
-static int qcow_snapshot_list(BlockDriverState *bs,
-                              QEMUSnapshotInfo **psn_tab)
-{
-    BDRVQcowState *s = bs->opaque;
-    QEMUSnapshotInfo *sn_tab, *sn_info;
-    QCowSnapshot *sn;
-    int i;
-
-    sn_tab = qemu_mallocz(s->nb_snapshots * sizeof(QEMUSnapshotInfo));
-    for(i = 0; i < s->nb_snapshots; i++) {
-        sn_info = sn_tab + i;
-        sn = s->snapshots + i;
-        pstrcpy(sn_info->id_str, sizeof(sn_info->id_str),
-                sn->id_str);
-        pstrcpy(sn_info->name, sizeof(sn_info->name),
-                sn->name);
-        sn_info->vm_state_size = sn->vm_state_size;
-        sn_info->date_sec = sn->date_sec;
-        sn_info->date_nsec = sn->date_nsec;
-        sn_info->vm_clock_nsec = sn->vm_clock_nsec;
-    }
-    *psn_tab = sn_tab;
-    return s->nb_snapshots;
-}
-
-/*********************************************************/
-/* refcount handling */
-
-static int refcount_init(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    int ret, refcount_table_size2, i;
-
-    s->refcount_block_cache = qemu_malloc(s->cluster_size);
-    refcount_table_size2 = s->refcount_table_size * sizeof(uint64_t);
-    s->refcount_table = qemu_malloc(refcount_table_size2);
-    if (s->refcount_table_size > 0) {
-        ret = bdrv_pread(s->hd, s->refcount_table_offset,
-                         s->refcount_table, refcount_table_size2);
-        if (ret != refcount_table_size2)
-            goto fail;
-        for(i = 0; i < s->refcount_table_size; i++)
-            be64_to_cpus(&s->refcount_table[i]);
-    }
-    return 0;
- fail:
-    return -ENOMEM;
-}
-
-static void refcount_close(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    qemu_free(s->refcount_block_cache);
-    qemu_free(s->refcount_table);
-}
-
-
-static int load_refcount_block(BlockDriverState *bs,
-                               int64_t refcount_block_offset)
-{
-    BDRVQcowState *s = bs->opaque;
-    int ret;
-    ret = bdrv_pread(s->hd, refcount_block_offset, s->refcount_block_cache,
-                     s->cluster_size);
-    if (ret != s->cluster_size)
-        return -EIO;
-    s->refcount_block_cache_offset = refcount_block_offset;
-    return 0;
-}
-
-static int get_refcount(BlockDriverState *bs, int64_t cluster_index)
-{
-    BDRVQcowState *s = bs->opaque;
-    int refcount_table_index, block_index;
-    int64_t refcount_block_offset;
-
-    refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
-    if (refcount_table_index >= s->refcount_table_size)
-        return 0;
-    refcount_block_offset = s->refcount_table[refcount_table_index];
-    if (!refcount_block_offset)
-        return 0;
-    if (refcount_block_offset != s->refcount_block_cache_offset) {
-        /* better than nothing: return allocated if read error */
-        if (load_refcount_block(bs, refcount_block_offset) < 0)
-            return 1;
-    }
-    block_index = cluster_index &
-        ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
-    return be16_to_cpu(s->refcount_block_cache[block_index]);
-}
-
-/* return < 0 if error */
-static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size)
-{
-    BDRVQcowState *s = bs->opaque;
-    int i, nb_clusters;
-
-    nb_clusters = size_to_clusters(s, size);
-retry:
-    for(i = 0; i < nb_clusters; i++) {
-        int64_t i = s->free_cluster_index++;
-        if (get_refcount(bs, i) != 0)
-            goto retry;
-    }
-#ifdef DEBUG_ALLOC2
-    printf("alloc_clusters: size=%lld -> %lld\n",
-            size,
-            (s->free_cluster_index - nb_clusters) << s->cluster_bits);
-#endif
-    return (s->free_cluster_index - nb_clusters) << s->cluster_bits;
-}
-
-static int64_t alloc_clusters(BlockDriverState *bs, int64_t size)
-{
-    int64_t offset;
-
-    offset = alloc_clusters_noref(bs, size);
-    update_refcount(bs, offset, size, 1);
-    return offset;
-}
-
-/* only used to allocate compressed sectors. We try to allocate
-   contiguous sectors. size must be <= cluster_size */
-static int64_t alloc_bytes(BlockDriverState *bs, int size)
-{
-    BDRVQcowState *s = bs->opaque;
-    int64_t offset, cluster_offset;
-    int free_in_cluster;
-
-    assert(size > 0 && size <= s->cluster_size);
-    if (s->free_byte_offset == 0) {
-        s->free_byte_offset = alloc_clusters(bs, s->cluster_size);
-    }
- redo:
-    free_in_cluster = s->cluster_size -
-        (s->free_byte_offset & (s->cluster_size - 1));
-    if (size <= free_in_cluster) {
-        /* enough space in current cluster */
-        offset = s->free_byte_offset;
-        s->free_byte_offset += size;
-        free_in_cluster -= size;
-        if (free_in_cluster == 0)
-            s->free_byte_offset = 0;
-        if ((offset & (s->cluster_size - 1)) != 0)
-            update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
-    } else {
-        offset = alloc_clusters(bs, s->cluster_size);
-        cluster_offset = s->free_byte_offset & ~(s->cluster_size - 1);
-        if ((cluster_offset + s->cluster_size) == offset) {
-            /* we are lucky: contiguous data */
-            offset = s->free_byte_offset;
-            update_cluster_refcount(bs, offset >> s->cluster_bits, 1);
-            s->free_byte_offset += size;
-        } else {
-            s->free_byte_offset = offset;
-            goto redo;
-        }
-    }
-    return offset;
-}
-
-static void free_clusters(BlockDriverState *bs,
-                          int64_t offset, int64_t size)
-{
-    update_refcount(bs, offset, size, -1);
-}
-
-static int grow_refcount_table(BlockDriverState *bs, int min_size)
-{
-    BDRVQcowState *s = bs->opaque;
-    int new_table_size, new_table_size2, refcount_table_clusters, i, ret;
-    uint64_t *new_table;
-    int64_t table_offset;
-    uint8_t data[12];
-    int old_table_size;
-    int64_t old_table_offset;
-
-    if (min_size <= s->refcount_table_size)
-        return 0;
-    /* compute new table size */
-    refcount_table_clusters = s->refcount_table_size >> (s->cluster_bits - 3);
-    for(;;) {
-        if (refcount_table_clusters == 0) {
-            refcount_table_clusters = 1;
-        } else {
-            refcount_table_clusters = (refcount_table_clusters * 3 + 1) / 2;
-        }
-        new_table_size = refcount_table_clusters << (s->cluster_bits - 3);
-        if (min_size <= new_table_size)
-            break;
-    }
-#ifdef DEBUG_ALLOC2
-    printf("grow_refcount_table from %d to %d\n",
-           s->refcount_table_size,
-           new_table_size);
-#endif
-    new_table_size2 = new_table_size * sizeof(uint64_t);
-    new_table = qemu_mallocz(new_table_size2);
-    memcpy(new_table, s->refcount_table,
-           s->refcount_table_size * sizeof(uint64_t));
-    for(i = 0; i < s->refcount_table_size; i++)
-        cpu_to_be64s(&new_table[i]);
-    /* Note: we cannot update the refcount now to avoid recursion */
-    table_offset = alloc_clusters_noref(bs, new_table_size2);
-    ret = bdrv_pwrite(s->hd, table_offset, new_table, new_table_size2);
-    if (ret != new_table_size2)
-        goto fail;
-    for(i = 0; i < s->refcount_table_size; i++)
-        be64_to_cpus(&new_table[i]);
-
-    cpu_to_be64w((uint64_t*)data, table_offset);
-    cpu_to_be32w((uint32_t*)(data + 8), refcount_table_clusters);
-    if (bdrv_pwrite(s->hd, offsetof(QCowHeader, refcount_table_offset),
-                    data, sizeof(data)) != sizeof(data))
-        goto fail;
-    qemu_free(s->refcount_table);
-    old_table_offset = s->refcount_table_offset;
-    old_table_size = s->refcount_table_size;
-    s->refcount_table = new_table;
-    s->refcount_table_size = new_table_size;
-    s->refcount_table_offset = table_offset;
-
-    update_refcount(bs, table_offset, new_table_size2, 1);
-    free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t));
-    return 0;
- fail:
-    free_clusters(bs, table_offset, new_table_size2);
-    qemu_free(new_table);
-    return -EIO;
-}
-
-/* addend must be 1 or -1 */
-/* XXX: cache several refcount block clusters ? */
-static int update_cluster_refcount(BlockDriverState *bs,
-                                   int64_t cluster_index,
-                                   int addend)
-{
-    BDRVQcowState *s = bs->opaque;
-    int64_t offset, refcount_block_offset;
-    int ret, refcount_table_index, block_index, refcount;
-    uint64_t data64;
-
-    refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT);
-    if (refcount_table_index >= s->refcount_table_size) {
-        if (addend < 0)
-            return -EINVAL;
-        ret = grow_refcount_table(bs, refcount_table_index + 1);
-        if (ret < 0)
-            return ret;
-    }
-    refcount_block_offset = s->refcount_table[refcount_table_index];
-    if (!refcount_block_offset) {
-        if (addend < 0)
-            return -EINVAL;
-        /* create a new refcount block */
-        /* Note: we cannot update the refcount now to avoid recursion */
-        offset = alloc_clusters_noref(bs, s->cluster_size);
-        memset(s->refcount_block_cache, 0, s->cluster_size);
-        ret = bdrv_pwrite(s->hd, offset, s->refcount_block_cache, s->cluster_size);
-        if (ret != s->cluster_size)
-            return -EINVAL;
-        s->refcount_table[refcount_table_index] = offset;
-        data64 = cpu_to_be64(offset);
-        ret = bdrv_pwrite(s->hd, s->refcount_table_offset +
-                          refcount_table_index * sizeof(uint64_t),
-                          &data64, sizeof(data64));
-        if (ret != sizeof(data64))
-            return -EINVAL;
-
-        refcount_block_offset = offset;
-        s->refcount_block_cache_offset = offset;
-        update_refcount(bs, offset, s->cluster_size, 1);
-    } else {
-        if (refcount_block_offset != s->refcount_block_cache_offset) {
-            if (load_refcount_block(bs, refcount_block_offset) < 0)
-                return -EIO;
-        }
-    }
-    /* we can update the count and save it */
-    block_index = cluster_index &
-        ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1);
-    refcount = be16_to_cpu(s->refcount_block_cache[block_index]);
-    refcount += addend;
-    if (refcount < 0 || refcount > 0xffff)
-        return -EINVAL;
-    if (refcount == 0 && cluster_index < s->free_cluster_index) {
-        s->free_cluster_index = cluster_index;
-    }
-    s->refcount_block_cache[block_index] = cpu_to_be16(refcount);
-    if (bdrv_pwrite(s->hd,
-                    refcount_block_offset + (block_index << REFCOUNT_SHIFT),
-                    &s->refcount_block_cache[block_index], 2) != 2)
-        return -EIO;
-    return refcount;
-}
-
-static void update_refcount(BlockDriverState *bs,
-                            int64_t offset, int64_t length,
-                            int addend)
-{
-    BDRVQcowState *s = bs->opaque;
-    int64_t start, last, cluster_offset;
-
-#ifdef DEBUG_ALLOC2
-    printf("update_refcount: offset=%lld size=%lld addend=%d\n",
-           offset, length, addend);
-#endif
-    if (length <= 0)
-        return;
-    start = offset & ~(s->cluster_size - 1);
-    last = (offset + length - 1) & ~(s->cluster_size - 1);
-    for(cluster_offset = start; cluster_offset <= last;
-        cluster_offset += s->cluster_size) {
-        update_cluster_refcount(bs, cluster_offset >> s->cluster_bits, addend);
-    }
-}
-
-/*
- * 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.
- *
- * Returns the number of errors in the image that were found
- */
-static int inc_refcounts(BlockDriverState *bs,
-                          uint16_t *refcount_table,
-                          int refcount_table_size,
-                          int64_t offset, int64_t size)
-{
-    BDRVQcowState *s = bs->opaque;
-    int64_t start, last, cluster_offset;
-    int k;
-    int errors = 0;
-
-    if (size <= 0)
-        return 0;
-
-    start = offset & ~(s->cluster_size - 1);
-    last = (offset + size - 1) & ~(s->cluster_size - 1);
-    for(cluster_offset = start; cluster_offset <= last;
-        cluster_offset += s->cluster_size) {
-        k = cluster_offset >> s->cluster_bits;
-        if (k < 0 || k >= refcount_table_size) {
-            fprintf(stderr, "ERROR: invalid cluster offset=0x%" PRIx64 "\n",
-                cluster_offset);
-            errors++;
-        } else {
-            if (++refcount_table[k] == 0) {
-                fprintf(stderr, "ERROR: overflow cluster offset=0x%" PRIx64
-                    "\n", cluster_offset);
-                errors++;
-            }
-        }
-    }
-
-    return errors;
-}
-
-/*
- * 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,
-    uint16_t *refcount_table, int refcount_table_size, int64_t l2_offset,
-    int check_copied)
-{
-    BDRVQcowState *s = bs->opaque;
-    uint64_t *l2_table, offset;
-    int i, l2_size, nb_csectors, refcount;
-    int errors = 0;
-
-    /* Read L2 table from disk */
-    l2_size = s->l2_size * sizeof(uint64_t);
-    l2_table = qemu_malloc(l2_size);
-
-    if (bdrv_pread(s->hd, l2_offset, l2_table, l2_size) != l2_size)
-        goto fail;
-
-    /* Do the actual checks */
-    for(i = 0; i < s->l2_size; i++) {
-        offset = be64_to_cpu(l2_table[i]);
-        if (offset != 0) {
-            if (offset & QCOW_OFLAG_COMPRESSED) {
-                /* Compressed clusters don't have QCOW_OFLAG_COPIED */
-                if (offset & QCOW_OFLAG_COPIED) {
-                    fprintf(stderr, "ERROR: cluster %" PRId64 ": "
-                        "copied flag must never be set for compressed "
-                        "clusters\n", offset >> s->cluster_bits);
-                    offset &= ~QCOW_OFLAG_COPIED;
-                    errors++;
-                }
-
-                /* Mark cluster as used */
-                nb_csectors = ((offset >> s->csize_shift) &
-                               s->csize_mask) + 1;
-                offset &= s->cluster_offset_mask;
-                errors += inc_refcounts(bs, refcount_table,
-                              refcount_table_size,
-                              offset & ~511, nb_csectors * 512);
-            } else {
-                /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
-                if (check_copied) {
-                    uint64_t entry = offset;
-                    offset &= ~QCOW_OFLAG_COPIED;
-                    refcount = get_refcount(bs, offset >> s->cluster_bits);
-                    if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) {
-                        fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
-                            PRIx64 " refcount=%d\n", entry, refcount);
-                        errors++;
-                    }
-                }
-
-                /* Mark cluster as used */
-                offset &= ~QCOW_OFLAG_COPIED;
-                errors += inc_refcounts(bs, refcount_table,
-                              refcount_table_size,
-                              offset, s->cluster_size);
-
-                /* Correct offsets are cluster aligned */
-                if (offset & (s->cluster_size - 1)) {
-                    fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
-                        "properly aligned; L2 entry corrupted.\n", offset);
-                    errors++;
-                }
-            }
-        }
-    }
-
-    qemu_free(l2_table);
-    return errors;
-
-fail:
-    fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
-    qemu_free(l2_table);
-    return -EIO;
-}
-
-/*
- * Increases the refcount for the L1 table, its L2 tables and all referenced
- * clusters in the given refcount table. While doing so, performs some checks
- * on L1 and L2 entries.
- *
- * Returns the number of errors found by the checks or -errno if an internal
- * error occurred.
- */
-static int check_refcounts_l1(BlockDriverState *bs,
-                              uint16_t *refcount_table,
-                              int refcount_table_size,
-                              int64_t l1_table_offset, int l1_size,
-                              int check_copied)
-{
-    BDRVQcowState *s = bs->opaque;
-    uint64_t *l1_table, l2_offset, l1_size2;
-    int i, refcount, ret;
-    int errors = 0;
-
-    l1_size2 = l1_size * sizeof(uint64_t);
-
-    /* Mark L1 table as used */
-    errors += inc_refcounts(bs, refcount_table, refcount_table_size,
-                  l1_table_offset, l1_size2);
-
-    /* Read L1 table entries from disk */
-    l1_table = qemu_malloc(l1_size2);
-    if (bdrv_pread(s->hd, l1_table_offset,
-                   l1_table, l1_size2) != l1_size2)
-        goto fail;
-    for(i = 0;i < l1_size; i++)
-        be64_to_cpus(&l1_table[i]);
-
-    /* Do the actual checks */
-    for(i = 0; i < l1_size; i++) {
-        l2_offset = l1_table[i];
-        if (l2_offset) {
-            /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
-            if (check_copied) {
-                refcount = get_refcount(bs, (l2_offset & ~QCOW_OFLAG_COPIED)
-                    >> s->cluster_bits);
-                if ((refcount == 1) != ((l2_offset & QCOW_OFLAG_COPIED) != 0)) {
-                    fprintf(stderr, "ERROR OFLAG_COPIED: l2_offset=%" PRIx64
-                        " refcount=%d\n", l2_offset, refcount);
-                    errors++;
-                }
-            }
-
-            /* Mark L2 table as used */
-            l2_offset &= ~QCOW_OFLAG_COPIED;
-            errors += inc_refcounts(bs, refcount_table,
-                          refcount_table_size,
-                          l2_offset,
-                          s->cluster_size);
-
-            /* L2 tables are cluster aligned */
-            if (l2_offset & (s->cluster_size - 1)) {
-                fprintf(stderr, "ERROR l2_offset=%" PRIx64 ": Table is not "
-                    "cluster aligned; L1 entry corrupted\n", l2_offset);
-                errors++;
-            }
-
-            /* Process and check L2 entries */
-            ret = check_refcounts_l2(bs, refcount_table, refcount_table_size,
-                l2_offset, check_copied);
-            if (ret < 0) {
-                goto fail;
-            }
-            errors += ret;
-        }
-    }
-    qemu_free(l1_table);
-    return errors;
-
-fail:
-    fprintf(stderr, "ERROR: I/O error in check_refcounts_l1\n");
-    qemu_free(l1_table);
-    return -EIO;
-}
-
-/*
- * Checks an image for refcount consistency.
- *
- * Returns 0 if no errors are found, the number of errors in case the image is
- * detected as corrupted, and -errno when an internal error occured.
- */
-static int check_refcounts(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    int64_t size;
-    int nb_clusters, refcount1, refcount2, i;
-    QCowSnapshot *sn;
-    uint16_t *refcount_table;
-    int ret, errors = 0;
-
-    size = bdrv_getlength(s->hd);
-    nb_clusters = size_to_clusters(s, size);
-    refcount_table = qemu_mallocz(nb_clusters * sizeof(uint16_t));
-
-    /* header */
-    errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                  0, s->cluster_size);
-
-    /* current L1 table */
-    ret = check_refcounts_l1(bs, refcount_table, nb_clusters,
-                       s->l1_table_offset, s->l1_size, 1);
-    if (ret < 0) {
-        return ret;
-    }
-    errors += ret;
-
-    /* snapshots */
-    for(i = 0; i < s->nb_snapshots; i++) {
-        sn = s->snapshots + i;
-        check_refcounts_l1(bs, refcount_table, nb_clusters,
-                           sn->l1_table_offset, sn->l1_size, 0);
-    }
-    errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                  s->snapshots_offset, s->snapshots_size);
-
-    /* refcount data */
-    errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                  s->refcount_table_offset,
-                  s->refcount_table_size * sizeof(uint64_t));
-    for(i = 0; i < s->refcount_table_size; i++) {
-        int64_t offset;
-        offset = s->refcount_table[i];
-        if (offset != 0) {
-            errors += inc_refcounts(bs, refcount_table, nb_clusters,
-                          offset, s->cluster_size);
-        }
-    }
-
-    /* compare ref counts */
-    for(i = 0; i < nb_clusters; i++) {
-        refcount1 = get_refcount(bs, i);
-        refcount2 = refcount_table[i];
-        if (refcount1 != refcount2) {
-            fprintf(stderr, "ERROR cluster %d refcount=%d reference=%d\n",
-                   i, refcount1, refcount2);
-            errors++;
-        }
-    }
-
-    qemu_free(refcount_table);
-
-    return errors;
-}
-
-static int qcow_check(BlockDriverState *bs)
-{
-    return check_refcounts(bs);
-}
-
-#if 0
-static void dump_refcounts(BlockDriverState *bs)
-{
-    BDRVQcowState *s = bs->opaque;
-    int64_t nb_clusters, k, k1, size;
-    int refcount;
-
-    size = bdrv_getlength(s->hd);
-    nb_clusters = size_to_clusters(s, size);
-    for(k = 0; k < nb_clusters;) {
-        k1 = k;
-        refcount = get_refcount(bs, k);
-        k++;
-        while (k < nb_clusters && get_refcount(bs, k) == refcount)
-            k++;
-        printf("%lld: refcount=%d nb=%lld\n", k, refcount, k - k1);
-    }
-}
-#endif
-
-static int qcow_put_buffer(BlockDriverState *bs, const uint8_t *buf,
-                           int64_t pos, int size)
-{
-    int growable = bs->growable;
-
-    bs->growable = 1;
-    bdrv_pwrite(bs, pos, buf, size);
-    bs->growable = growable;
-
-    return size;
-}
-
-static int qcow_get_buffer(BlockDriverState *bs, uint8_t *buf,
-                           int64_t pos, int size)
-{
-    int growable = bs->growable;
-    int ret;
-
-    bs->growable = 1;
-    ret = bdrv_pread(bs, pos, buf, size);
-    bs->growable = growable;
-
-    return ret;
-}
-
-static BlockDriver bdrv_qcow2 = {
-    .format_name	= "qcow2",
-    .instance_size	= sizeof(BDRVQcowState),
-    .bdrv_probe		= qcow_probe,
-    .bdrv_open		= qcow_open,
-    .bdrv_close		= qcow_close,
-    .bdrv_create	= qcow_create,
-    .bdrv_flush		= qcow_flush,
-    .bdrv_is_allocated	= qcow_is_allocated,
-    .bdrv_set_key	= qcow_set_key,
-    .bdrv_make_empty	= qcow_make_empty,
-
-    .bdrv_aio_readv	= qcow_aio_readv,
-    .bdrv_aio_writev	= qcow_aio_writev,
-    .bdrv_aio_cancel	= qcow_aio_cancel,
-    .aiocb_size		= sizeof(QCowAIOCB),
-    .bdrv_write_compressed = qcow_write_compressed,
-
-    .bdrv_snapshot_create = qcow_snapshot_create,
-    .bdrv_snapshot_goto	= qcow_snapshot_goto,
-    .bdrv_snapshot_delete = qcow_snapshot_delete,
-    .bdrv_snapshot_list	= qcow_snapshot_list,
-    .bdrv_get_info	= qcow_get_info,
-
-    .bdrv_put_buffer    = qcow_put_buffer,
-    .bdrv_get_buffer    = qcow_get_buffer,
-
-    .bdrv_create2 = qcow_create2,
-    .bdrv_check = qcow_check,
-};
-
-static void bdrv_qcow2_init(void)
-{
-    bdrv_register(&bdrv_qcow2);
-}
-
-block_init(bdrv_qcow2_init);