diff options
Diffstat (limited to 'block/qcow2-refcount.c')
| -rw-r--r-- | block/qcow2-refcount.c | 854 |
1 files changed, 854 insertions, 0 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c new file mode 100644 index 000000000..dd6e293d0 --- /dev/null +++ b/block/qcow2-refcount.c @@ -0,0 +1,854 @@ +/* + * 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 "block/qcow2.h" + +static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size); +static int update_refcount(BlockDriverState *bs, + int64_t offset, int64_t length, + int addend); + +/*********************************************************/ +/* refcount handling */ + +int qcow2_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; +} + +void qcow2_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]); +} + +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); + qcow2_free_clusters(bs, old_table_offset, old_table_size * sizeof(uint64_t)); + return 0; + fail: + qcow2_free_clusters(bs, table_offset, new_table_size2); + qemu_free(new_table); + return -EIO; +} + + +static int64_t alloc_refcount_block(BlockDriverState *bs, int64_t cluster_index) +{ + BDRVQcowState *s = bs->opaque; + int64_t offset, refcount_block_offset; + int ret, refcount_table_index; + uint64_t data64; + + /* Find L1 index and grow refcount table if needed */ + refcount_table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); + if (refcount_table_index >= s->refcount_table_size) { + ret = grow_refcount_table(bs, refcount_table_index + 1); + if (ret < 0) + return ret; + } + + /* Load or allocate the refcount block */ + refcount_block_offset = s->refcount_table[refcount_table_index]; + if (!refcount_block_offset) { + /* 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; + } + } + + return refcount_block_offset; +} + +#define REFCOUNTS_PER_SECTOR (512 >> REFCOUNT_SHIFT) +static int write_refcount_block_entries(BDRVQcowState *s, + int64_t refcount_block_offset, int first_index, int last_index) +{ + size_t size; + + first_index &= ~(REFCOUNTS_PER_SECTOR - 1); + last_index = (last_index + REFCOUNTS_PER_SECTOR) + & ~(REFCOUNTS_PER_SECTOR - 1); + + size = (last_index - first_index) << REFCOUNT_SHIFT; + if (bdrv_pwrite(s->hd, + refcount_block_offset + (first_index << REFCOUNT_SHIFT), + &s->refcount_block_cache[first_index], size) != size) + { + return -EIO; + } + + return 0; +} + +/* XXX: cache several refcount block clusters ? */ +static int update_refcount(BlockDriverState *bs, + int64_t offset, int64_t length, + int addend) +{ + BDRVQcowState *s = bs->opaque; + int64_t start, last, cluster_offset; + int64_t refcount_block_offset = 0; + int64_t table_index = -1, old_table_index; + int first_index = -1, last_index = -1; + +#ifdef DEBUG_ALLOC2 + printf("update_refcount: offset=%lld size=%lld addend=%d\n", + offset, length, addend); +#endif + if (length <= 0) + return -EINVAL; + start = offset & ~(s->cluster_size - 1); + last = (offset + length - 1) & ~(s->cluster_size - 1); + for(cluster_offset = start; cluster_offset <= last; + cluster_offset += s->cluster_size) + { + int block_index, refcount; + int64_t cluster_index = cluster_offset >> s->cluster_bits; + + /* Only write refcount block to disk when we are done with it */ + old_table_index = table_index; + table_index = cluster_index >> (s->cluster_bits - REFCOUNT_SHIFT); + if ((old_table_index >= 0) && (table_index != old_table_index)) { + + if (write_refcount_block_entries(s, refcount_block_offset, + first_index, last_index) < 0) + { + return -EIO; + } + + first_index = -1; + last_index = -1; + } + + /* Load the refcount block and allocate it if needed */ + refcount_block_offset = alloc_refcount_block(bs, cluster_index); + if (refcount_block_offset < 0) { + return refcount_block_offset; + } + + /* we can update the count and save it */ + block_index = cluster_index & + ((1 << (s->cluster_bits - REFCOUNT_SHIFT)) - 1); + if (first_index == -1 || block_index < first_index) { + first_index = block_index; + } + if (block_index > last_index) { + last_index = block_index; + } + + 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); + } + + /* Write last changed block to disk */ + if (refcount_block_offset != 0) { + if (write_refcount_block_entries(s, refcount_block_offset, + first_index, last_index) < 0) + { + return -EIO; + } + } + + return 0; +} + +/* addend must be 1 or -1 */ +static int update_cluster_refcount(BlockDriverState *bs, + int64_t cluster_index, + int addend) +{ + BDRVQcowState *s = bs->opaque; + int ret; + + ret = update_refcount(bs, cluster_index << s->cluster_bits, 1, addend); + if (ret < 0) { + return ret; + } + + return get_refcount(bs, cluster_index); +} + + + +/*********************************************************/ +/* cluster allocation functions */ + + + +/* return < 0 if error */ +static int64_t alloc_clusters_noref(BlockDriverState *bs, int64_t size) +{ + BDRVQcowState *s = bs->opaque; + int i, nb_clusters; + + 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; +} + +int64_t qcow2_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 */ +int64_t qcow2_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 = qcow2_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 = qcow2_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; +} + +void qcow2_free_clusters(BlockDriverState *bs, + int64_t offset, int64_t size) +{ + update_refcount(bs, offset, size, -1); +} + +/* + * free_any_clusters + * + * free clusters according to its type: compressed or not + * + */ + +void qcow2_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; + qcow2_free_clusters(bs, + (cluster_offset & s->cluster_offset_mask) & ~511, + nb_csectors * 512); + return; + } + + qcow2_free_clusters(bs, cluster_offset, nb_clusters << s->cluster_bits); + + return; +} + + + +/*********************************************************/ +/* snapshots and image creation */ + + + +void qcow2_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); + } +} + +/* update the refcounts of snapshots and the copied flag */ +int qcow2_update_snapshot_refcount(BlockDriverState *bs, + int64_t l1_table_offset, int l1_size, int addend) +{ + BDRVQcowState *s = bs->opaque; + uint64_t *l1_table, *l2_table, l2_offset, offset, l1_size2, l1_allocated; + int64_t old_offset, old_l2_offset; + int l2_size, i, j, l1_modified, l2_modified, nb_csectors, refcount; + + qcow2_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; +} + + + + +/*********************************************************/ +/* refcount checking functions */ + + + +/* + * Increases the refcount for a range of clusters in a given refcount table. + * This is used to construct a temporary refcount table out of L1 and L2 tables + * which can be compared the the refcount table saved in the image. + * + * 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. + */ +int qcow2_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; +} + |