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X-Received-From: 2607:f8b0:400e:c05::243 Subject: [Qemu-devel] [PATCH v7 6/8] vmdk: New functions to assist allocating multiple clusters X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: kwolf@redhat.com, qemu-block@nongnu.org, stefanha@gmail.com, qemu-devel@nongnu.org, mreitz@redhat.com, Ashijeet Acharya , jsnow@redhat.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP Introduce two new helper functions handle_alloc() and vmdk_alloc_cluster_offset(). handle_alloc() helps to allocate multiple clusters at once starting from a given offset on disk and performs COW if necessary for first and last allocated clusters. vmdk_alloc_cluster_offset() helps to return the offset of the first of the many newly allocated clusters. Also, provide proper documentation for both. Signed-off-by: Ashijeet Acharya --- block/vmdk.c | 200 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 190 insertions(+), 10 deletions(-) diff --git a/block/vmdk.c b/block/vmdk.c index fe2046b..277db16 100644 --- a/block/vmdk.c +++ b/block/vmdk.c @@ -136,6 +136,7 @@ typedef struct VmdkMetaData { unsigned int l2_offset; int valid; uint32_t *l2_cache_entry; + uint32_t nb_clusters; } VmdkMetaData; typedef struct VmdkGrainMarker { @@ -1242,6 +1243,182 @@ static int get_cluster_table(VmdkExtent *extent, uint64_t offset, return VMDK_OK; } +/* + * vmdk_handle_alloc + * + * Allocate new clusters for an area that either is yet unallocated or needs a + * copy on write. + * + * Returns: + * VMDK_OK: if new clusters were allocated, *bytes may be decreased if + * the new allocation doesn't cover all of the requested area. + * *cluster_offset is updated to contain the offset of the + * first newly allocated cluster. + * + * VMDK_UNALLOC: if no clusters could be allocated. *cluster_offset is left + * unchanged. + * + * VMDK_ERROR: in error cases + */ +static int vmdk_handle_alloc(BlockDriverState *bs, VmdkExtent *extent, + uint64_t offset, uint64_t *cluster_offset, + int64_t *bytes, VmdkMetaData *m_data, + bool allocate, uint32_t *total_alloc_clusters) +{ + int l1_index, l2_offset, l2_index; + uint32_t *l2_table; + uint32_t cluster_sector; + uint32_t nb_clusters; + bool zeroed = false; + uint64_t skip_start_bytes, skip_end_bytes; + int ret; + + ret = get_cluster_table(extent, offset, &l1_index, &l2_offset, + &l2_index, &l2_table); + if (ret < 0) { + return ret; + } + + cluster_sector = le32_to_cpu(l2_table[l2_index]); + + skip_start_bytes = vmdk_find_offset_in_cluster(extent, offset); + /* Calculate the number of clusters to look for. Here we truncate the last + * cluster, i.e. 1 less than the actual value calculated as we may need to + * perform COW for the last one. */ + nb_clusters = DIV_ROUND_UP(skip_start_bytes + *bytes, + extent->cluster_sectors << BDRV_SECTOR_BITS) - 1; + + nb_clusters = MIN(nb_clusters, extent->l2_size - l2_index); + assert(nb_clusters <= INT_MAX); + + /* update bytes according to final nb_clusters value */ + if (nb_clusters != 0) { + *bytes = ((nb_clusters * extent->cluster_sectors) << BDRV_SECTOR_BITS) + - skip_start_bytes; + } else { + nb_clusters = 1; + } + *total_alloc_clusters += nb_clusters; + + /* we need to use MIN() for basically 3 cases that arise : + * 1. alloc very first cluster : here skip_start_bytes >= 0 and + * *bytes <= cluster_size. + * 2. alloc middle clusters : here *bytes is a perfect multiple of + * cluster_size and skip_start_bytes is 0. + * 3. alloc very last cluster : here *bytes <= cluster_size and + * skip_start_bytes is 0 + */ + skip_end_bytes = skip_start_bytes + MIN(*bytes, + extent->cluster_sectors * BDRV_SECTOR_SIZE + - skip_start_bytes); + + if (extent->has_zero_grain && cluster_sector == VMDK_GTE_ZEROED) { + zeroed = true; + } + + if (!cluster_sector || zeroed) { + if (!allocate) { + return zeroed ? VMDK_ZEROED : VMDK_UNALLOC; + } + + cluster_sector = extent->next_cluster_sector; + extent->next_cluster_sector += extent->cluster_sectors + * nb_clusters; + + ret = vmdk_perform_cow(bs, extent, cluster_sector * BDRV_SECTOR_SIZE, + offset, skip_start_bytes, + skip_end_bytes); + if (ret < 0) { + return ret; + } + if (m_data) { + m_data->valid = 1; + m_data->l1_index = l1_index; + m_data->l2_index = l2_index; + m_data->l2_offset = l2_offset; + m_data->l2_cache_entry = &l2_table[l2_index]; + m_data->nb_clusters = nb_clusters; + } + } + *cluster_offset = cluster_sector << BDRV_SECTOR_BITS; + return VMDK_OK; +} + +/* + * vmdk_alloc_clusters + * + * For a given offset on the virtual disk, find the cluster offset in vmdk + * file. If the offset is not found, allocate a new cluster. + * + * If the cluster is newly allocated, m_data->nb_clusters is set to the number + * of contiguous clusters that have been allocated. In this case, the other + * fields of m_data are valid and contain information about the first allocated + * cluster. + * + * Returns: + * + * VMDK_OK: on success and @cluster_offset was set + * + * VMDK_UNALLOC: if no clusters were allocated and @cluster_offset is + * set to zero + * + * VMDK_ERROR: in error cases + */ +static int vmdk_alloc_clusters(BlockDriverState *bs, + VmdkExtent *extent, + VmdkMetaData *m_data, uint64_t offset, + bool allocate, uint64_t *cluster_offset, + int64_t bytes, + uint32_t *total_alloc_clusters) +{ + uint64_t start, remaining; + uint64_t new_cluster_offset; + int64_t n_bytes; + int ret; + + if (extent->flat) { + *cluster_offset = extent->flat_start_offset; + return VMDK_OK; + } + + start = offset; + remaining = bytes; + new_cluster_offset = 0; + *cluster_offset = 0; + n_bytes = 0; + if (m_data) { + m_data->valid = 0; + } + + /* due to L2 table margins all bytes may not get allocated at once */ + while (true) { + + if (!*cluster_offset) { + *cluster_offset = new_cluster_offset; + } + + start += n_bytes; + remaining -= n_bytes; + new_cluster_offset += n_bytes; + + if (remaining == 0) { + break; + } + + n_bytes = remaining; + + ret = vmdk_handle_alloc(bs, extent, start, &new_cluster_offset, &n_bytes, + m_data, allocate, total_alloc_clusters); + + if (ret < 0) { + return ret; + + } + } + + return VMDK_OK; +} + /** * vmdk_get_cluster_offset * @@ -1625,6 +1802,7 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t bytes_done = 0; VmdkMetaData m_data; uint64_t extent_end; + uint32_t total_alloc_clusters = 0; if (DIV_ROUND_UP(offset, BDRV_SECTOR_SIZE) > bs->total_sectors) { error_report("Wrong offset: offset=0x%" PRIx64 @@ -1650,10 +1828,10 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, n_bytes = MIN(bytes, extent_end - offset); } - ret = vmdk_get_cluster_offset(bs, extent, &m_data, offset, - !(extent->compressed || zeroed), - &cluster_offset, offset_in_cluster, - offset_in_cluster + n_bytes); + ret = vmdk_alloc_clusters(bs, extent, &m_data, offset, + !(extent->compressed || zeroed), + &cluster_offset, n_bytes, + &total_alloc_clusters); if (extent->compressed) { if (ret == VMDK_OK) { /* Refuse write to allocated cluster for streamOptimized */ @@ -1662,8 +1840,9 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, return -EIO; } else { /* allocate */ - ret = vmdk_get_cluster_offset(bs, extent, &m_data, offset, - true, &cluster_offset, 0, 0); + ret = vmdk_alloc_clusters(bs, extent, &m_data, offset, + true, &cluster_offset, n_bytes, + &total_alloc_clusters); } } if (ret == VMDK_ERROR) { @@ -1671,10 +1850,11 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, } if (zeroed) { /* Do zeroed write, buf is ignored */ - if (extent->has_zero_grain && - offset_in_cluster == 0 && - n_bytes >= extent->cluster_sectors * BDRV_SECTOR_SIZE) { - n_bytes = extent->cluster_sectors * BDRV_SECTOR_SIZE; + if (extent->has_zero_grain && offset_in_cluster == 0 && + n_bytes >= extent->cluster_sectors * BDRV_SECTOR_SIZE * + total_alloc_clusters) { + n_bytes = extent->cluster_sectors * BDRV_SECTOR_SIZE * + total_alloc_clusters; if (!zero_dry_run) { /* update L2 tables */ if (vmdk_L2update(extent, &m_data, VMDK_GTE_ZEROED)