diff options
Diffstat (limited to 'block/qcow2-refcount.c')
| -rw-r--r-- | block/qcow2-refcount.c | 130 |
1 files changed, 81 insertions, 49 deletions
diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c index e86a1d6ccf..497364f673 100644 --- a/block/qcow2-refcount.c +++ b/block/qcow2-refcount.c @@ -1095,6 +1095,63 @@ fail: /* refcount checking functions */ +static size_t refcount_array_byte_size(BDRVQcowState *s, uint64_t entries) +{ + /* This assertion holds because there is no way we can address more than + * 2^(64 - 9) clusters at once (with cluster size 512 = 2^9, and because + * offsets have to be representable in bytes); due to every cluster + * corresponding to one refcount entry, we are well below that limit */ + assert(entries < (UINT64_C(1) << (64 - 9))); + + /* Thanks to the assertion this will not overflow, because + * s->refcount_order < 7. + * (note: x << s->refcount_order == x * s->refcount_bits) */ + return DIV_ROUND_UP(entries << s->refcount_order, 8); +} + +/** + * Reallocates *array so that it can hold new_size entries. *size must contain + * the current number of entries in *array. If the reallocation fails, *array + * and *size will not be modified and -errno will be returned. If the + * reallocation is successful, *array will be set to the new buffer, *size + * will be set to new_size and 0 will be returned. The size of the reallocated + * refcount array buffer will be aligned to a cluster boundary, and the newly + * allocated area will be zeroed. + */ +static int realloc_refcount_array(BDRVQcowState *s, uint16_t **array, + int64_t *size, int64_t new_size) +{ + size_t old_byte_size, new_byte_size; + uint16_t *new_ptr; + + /* Round to clusters so the array can be directly written to disk */ + old_byte_size = size_to_clusters(s, refcount_array_byte_size(s, *size)) + * s->cluster_size; + new_byte_size = size_to_clusters(s, refcount_array_byte_size(s, new_size)) + * s->cluster_size; + + if (new_byte_size == old_byte_size) { + *size = new_size; + return 0; + } + + assert(new_byte_size > 0); + + new_ptr = g_try_realloc(*array, new_byte_size); + if (!new_ptr) { + return -ENOMEM; + } + + if (new_byte_size > old_byte_size) { + memset((void *)((uintptr_t)new_ptr + old_byte_size), 0, + new_byte_size - old_byte_size); + } + + *array = new_ptr; + *size = new_size; + + return 0; +} /* * Increases the refcount for a range of clusters in a given refcount table. @@ -1111,6 +1168,7 @@ static int inc_refcounts(BlockDriverState *bs, { BDRVQcowState *s = bs->opaque; uint64_t start, last, cluster_offset, k; + int ret; if (size <= 0) { return 0; @@ -1122,23 +1180,12 @@ static int inc_refcounts(BlockDriverState *bs, cluster_offset += s->cluster_size) { k = cluster_offset >> s->cluster_bits; if (k >= *refcount_table_size) { - int64_t old_refcount_table_size = *refcount_table_size; - uint16_t *new_refcount_table; - - *refcount_table_size = k + 1; - new_refcount_table = g_try_realloc(*refcount_table, - *refcount_table_size * - sizeof(**refcount_table)); - if (!new_refcount_table) { - *refcount_table_size = old_refcount_table_size; + ret = realloc_refcount_array(s, refcount_table, + refcount_table_size, k + 1); + if (ret < 0) { res->check_errors++; - return -ENOMEM; + return ret; } - *refcount_table = new_refcount_table; - - memset(*refcount_table + old_refcount_table_size, 0, - (*refcount_table_size - old_refcount_table_size) * - sizeof(**refcount_table)); } if (++(*refcount_table)[k] == 0) { @@ -1507,8 +1554,7 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res, fix & BDRV_FIX_ERRORS ? "Repairing" : "ERROR", i); if (fix & BDRV_FIX_ERRORS) { - int64_t old_nb_clusters = *nb_clusters; - uint16_t *new_refcount_table; + int64_t new_nb_clusters; if (offset > INT64_MAX - s->cluster_size) { ret = -EINVAL; @@ -1525,22 +1571,15 @@ static int check_refblocks(BlockDriverState *bs, BdrvCheckResult *res, goto resize_fail; } - *nb_clusters = size_to_clusters(s, size); - assert(*nb_clusters >= old_nb_clusters); + new_nb_clusters = size_to_clusters(s, size); + assert(new_nb_clusters >= *nb_clusters); - new_refcount_table = g_try_realloc(*refcount_table, - *nb_clusters * - sizeof(**refcount_table)); - if (!new_refcount_table) { - *nb_clusters = old_nb_clusters; + ret = realloc_refcount_array(s, refcount_table, + nb_clusters, new_nb_clusters); + if (ret < 0) { res->check_errors++; - return -ENOMEM; + return ret; } - *refcount_table = new_refcount_table; - - memset(*refcount_table + old_nb_clusters, 0, - (*nb_clusters - old_nb_clusters) * - sizeof(**refcount_table)); if (cluster >= *nb_clusters) { ret = -EINVAL; @@ -1600,10 +1639,12 @@ static int calculate_refcounts(BlockDriverState *bs, BdrvCheckResult *res, int ret; if (!*refcount_table) { - *refcount_table = g_try_new0(uint16_t, *nb_clusters); - if (*nb_clusters && *refcount_table == NULL) { + int64_t old_size = 0; + ret = realloc_refcount_array(s, refcount_table, + &old_size, *nb_clusters); + if (ret < 0) { res->check_errors++; - return -ENOMEM; + return ret; } } @@ -1737,6 +1778,7 @@ static int64_t alloc_clusters_imrt(BlockDriverState *bs, int64_t cluster = *first_free_cluster, i; bool first_gap = true; int contiguous_free_clusters; + int ret; /* Starting at *first_free_cluster, find a range of at least cluster_count * continuously free clusters */ @@ -1766,28 +1808,18 @@ static int64_t alloc_clusters_imrt(BlockDriverState *bs, /* If no such range could be found, grow the in-memory refcount table * accordingly to append free clusters at the end of the image */ if (contiguous_free_clusters < cluster_count) { - int64_t old_imrt_nb_clusters = *imrt_nb_clusters; - uint16_t *new_refcount_table; - /* contiguous_free_clusters clusters are already empty at the image end; * we need cluster_count clusters; therefore, we have to allocate * cluster_count - contiguous_free_clusters new clusters at the end of * the image (which is the current value of cluster; note that cluster * may exceed old_imrt_nb_clusters if *first_free_cluster pointed beyond * the image end) */ - *imrt_nb_clusters = cluster + cluster_count - contiguous_free_clusters; - new_refcount_table = g_try_realloc(*refcount_table, - *imrt_nb_clusters * - sizeof(**refcount_table)); - if (!new_refcount_table) { - *imrt_nb_clusters = old_imrt_nb_clusters; - return -ENOMEM; - } - *refcount_table = new_refcount_table; - - memset(*refcount_table + old_imrt_nb_clusters, 0, - (*imrt_nb_clusters - old_imrt_nb_clusters) * - sizeof(**refcount_table)); + ret = realloc_refcount_array(s, refcount_table, imrt_nb_clusters, + cluster + cluster_count + - contiguous_free_clusters); + if (ret < 0) { + return ret; + } } /* Go back to the first free cluster */ |