| Message ID | 1491057878-27868-4-git-send-email-ashijeetacharya@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, 04/01 20:14, Ashijeet Acharya wrote: > Move the cluster tables loading code out of the existing > get_cluster_offset() function to avoid code duplication and implement it > in separate get_cluster_table() and vmdk_L2load() functions. > > 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 <ashijeetacharya@gmail.com> > --- > block/vmdk.c | 337 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----- > 1 file changed, 308 insertions(+), 29 deletions(-) > > diff --git a/block/vmdk.c b/block/vmdk.c > index 73ae786..e5a289d 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 { > @@ -254,6 +255,14 @@ static inline uint64_t vmdk_find_offset_in_cluster(VmdkExtent *extent, > return extent_relative_offset % cluster_size; > } > > +static inline uint64_t size_to_clusters(VmdkExtent *extent, uint64_t size) > +{ > + uint64_t cluster_size, round_off_size; > + cluster_size = extent->cluster_sectors * BDRV_SECTOR_SIZE; > + round_off_size = cluster_size - (size % cluster_size); > + return DIV_ROUND_UP(size + round_off_size, BDRV_SECTOR_SIZE * 128) - 1; What is (BDRV_SECTOR_SIZE * 128)? Do you mean extent->cluster_size? And the function doesn't make sense up to me. Just un-inline this to DIV_ROUND_UP(size, extent->cluster_sectors << BDRV_SECTOR_BITS) - 1 in the calling site and be done with it. > +} > + > static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent) > { > char *desc; > @@ -1028,6 +1037,133 @@ static void vmdk_refresh_limits(BlockDriverState *bs, Error **errp) > } > } > > +static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data, > + uint32_t offset) > +{ > + offset = cpu_to_le32(offset); > + /* update L2 table */ > + if (bdrv_pwrite_sync(extent->file, > + ((int64_t)m_data->l2_offset * 512) > + + (m_data->l2_index * sizeof(offset)), > + &offset, sizeof(offset)) < 0) { > + return VMDK_ERROR; > + } > + /* update backup L2 table */ > + if (extent->l1_backup_table_offset != 0) { > + m_data->l2_offset = extent->l1_backup_table[m_data->l1_index]; > + if (bdrv_pwrite_sync(extent->file, > + ((int64_t)m_data->l2_offset * 512) > + + (m_data->l2_index * sizeof(offset)), > + &offset, sizeof(offset)) < 0) { > + return VMDK_ERROR; > + } > + } > + if (m_data->l2_cache_entry) { > + *m_data->l2_cache_entry = offset; > + } > + > + return VMDK_OK; > +} > + > +/* > + * vmdk_l2load > + * > + * Loads a new L2 table into memory. If the table is in the cache, the cache Not a native speaker, but s/Loads/Load/ feels more nature and consistent with other comments. > + * is used; otherwise the L2 table is loaded from the image file. > + * > + * Returns: > + * VMDK_OK: on success > + * VMDK_ERROR: in error cases > + */ > +static int vmdk_l2load(VmdkExtent *extent, uint64_t offset, int l2_offset, > + uint32_t **new_l2_table, int *new_l2_index) > +{ > + int min_index, i, j; > + uint32_t *l2_table; > + uint32_t min_count; > + > + for (i = 0; i < L2_CACHE_SIZE; i++) { > + if (l2_offset == extent->l2_cache_offsets[i]) { > + /* increment the hit count */ > + if (++extent->l2_cache_counts[i] == UINT32_MAX) { > + for (j = 0; j < L2_CACHE_SIZE; j++) { > + extent->l2_cache_counts[j] >>= 1; > + } > + } > + l2_table = extent->l2_cache + (i * extent->l2_size); > + goto found; > + } > + } > + /* not found: load a new entry in the least used one */ > + min_index = 0; > + min_count = UINT32_MAX; > + for (i = 0; i < L2_CACHE_SIZE; i++) { > + if (extent->l2_cache_counts[i] < min_count) { > + min_count = extent->l2_cache_counts[i]; > + min_index = i; > + } > + } > + l2_table = extent->l2_cache + (min_index * extent->l2_size); > + if (bdrv_pread(extent->file, > + (int64_t)l2_offset * 512, > + l2_table, > + extent->l2_size * sizeof(uint32_t) > + ) != extent->l2_size * sizeof(uint32_t)) { > + return VMDK_ERROR; > + } > + > + extent->l2_cache_offsets[min_index] = l2_offset; > + extent->l2_cache_counts[min_index] = 1; > +found: > + *new_l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size; > + *new_l2_table = l2_table; > + > + return VMDK_OK; > +} > + > +/* > + * get_cluster_table > + * > + * for a given offset, load (and allocate if needed) the l2 table. > + * > + * Returns: > + * VMDK_OK: on success > + * > + * VMDK_UNALLOC: if cluster is not mapped > + * > + * VMDK_ERROR: in error cases > + */ > +static int get_cluster_table(VmdkExtent *extent, uint64_t offset, > + int *new_l1_index, int *new_l2_offset, > + int *new_l2_index, uint32_t **new_l2_table) > +{ > + int l1_index, l2_offset, l2_index; > + uint32_t *l2_table; > + int ret; > + > + offset -= (extent->end_sector - extent->sectors) * SECTOR_SIZE; > + l1_index = (offset >> 9) / extent->l1_entry_sectors; > + if (l1_index >= extent->l1_size) { > + return VMDK_ERROR; > + } > + l2_offset = extent->l1_table[l1_index]; > + if (!l2_offset) { > + return VMDK_UNALLOC; > + } > + > + ret = vmdk_l2load(extent, offset, l2_offset, &l2_table, &l2_index); > + if (ret < 0) { > + return ret; > + } > + > + *new_l1_index = l1_index; > + *new_l2_offset = l2_offset; > + *new_l2_index = l2_index; > + *new_l2_table = l2_table; > + > + return VMDK_OK; > +} > + Can you move this hunk into patch 4 and put it before this patch? It will make reviewing a bit easier. (Yes, this patch is already big.) > /* > * vmdk_perform_cow > * > @@ -1115,29 +1251,168 @@ exit: > return ret; > } > > -static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data, > - uint32_t offset) > +/* > + * handle_alloc > + * > + * Allocates new clusters for an area that either is yet unallocated or needs a Similar to vmdk_l2load, s/Allocates/Allocate/ > + * copy on write. If *cluster_offset is non_zero, clusters are only allocated if > + * the new allocation can match the specified host offset. > + * > + * 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 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) > { > - offset = cpu_to_le32(offset); > - /* update L2 table */ > - if (bdrv_pwrite_sync(extent->file, > - ((int64_t)m_data->l2_offset * 512) > - + (m_data->l2_index * sizeof(offset)), > - &offset, sizeof(offset)) < 0) { > - return VMDK_ERROR; > + 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; > } > - /* update backup L2 table */ > - if (extent->l1_backup_table_offset != 0) { > - m_data->l2_offset = extent->l1_backup_table[m_data->l1_index]; > - if (bdrv_pwrite_sync(extent->file, > - ((int64_t)m_data->l2_offset * 512) > - + (m_data->l2_index * sizeof(offset)), > - &offset, sizeof(offset)) < 0) { > - return VMDK_ERROR; > + > + 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 it will return one > + * cluster less than the actual value calculated as we may need to perfrom > + * COW for the last one. */ > + nb_clusters = size_to_clusters(extent, skip_start_bytes + *bytes); > + > + 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) << 9) > + - skip_start_bytes; > + } else { > + nb_clusters = 1; > + } > + *total_alloc_clusters += nb_clusters; > + 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; > } > } > - if (m_data->l2_cache_entry) { > - *m_data->l2_cache_entry = offset; > + *cluster_offset = cluster_sector << BDRV_SECTOR_BITS; > + return VMDK_OK; > +} > + > +/* > + * vmdk_alloc_cluster_offset Maybe just name it "vmdk_alloc_clusters", which sounds better to me? Because the clusters are what we allocate here, it's rather "vmdk_alloc_clusters_and_get_offset" but we probably don't want it that long. > + * > + * 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 Thank you for adding the function documentations! > + */ > +static int vmdk_alloc_cluster_offset(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; Here, in the first iteration, remaining == bytes and n_bytes == 0. > + new_cluster_offset += n_bytes; > + > + if (remaining == 0) { > + break; > + } > + > + n_bytes = remaining; Then n_bytes becomes bytes; In the second iteration, remaining is always 0 because of "remaining -= n_bytes". What's the point of the while loop? > + > + ret = handle_alloc(bs, extent, start, &new_cluster_offset, &n_bytes, > + m_data, allocate, total_alloc_clusters); > + > + if (ret < 0) { > + return ret; > + > + } > } > > return VMDK_OK; > @@ -1567,6 +1842,7 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, > uint64_t cluster_offset; > uint64_t bytes_done = 0; > VmdkMetaData m_data; > + uint32_t total_alloc_clusters = 0; > > if (DIV_ROUND_UP(offset, BDRV_SECTOR_SIZE) > bs->total_sectors) { > error_report("Wrong offset: offset=0x%" PRIx64 > @@ -1584,10 +1860,10 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, > n_bytes = MIN(bytes, extent->cluster_sectors * BDRV_SECTOR_SIZE > - offset_in_cluster); > > - ret = get_cluster_offset(bs, extent, &m_data, offset, > - !(extent->compressed || zeroed), > - &cluster_offset, offset_in_cluster, > - offset_in_cluster + n_bytes); > + ret = vmdk_alloc_cluster_offset(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 */ > @@ -1596,19 +1872,22 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, > return -EIO; > } else { > /* allocate */ > - ret = get_cluster_offset(bs, extent, &m_data, offset, > - true, &cluster_offset, 0, 0); > + ret = vmdk_alloc_cluster_offset(bs, extent, &m_data, offset, > + true, &cluster_offset, n_bytes, > + &total_alloc_clusters); Parameter list is no longer aligned now. > } > } > if (ret == VMDK_ERROR) { > return -EINVAL; > } > + > 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) > -- > 2.6.2 >
On Wed, Apr 19, 2017 at 18:26 Fam Zheng <famz@redhat.com> wrote: > On Sat, 04/01 20:14, Ashijeet Acharya wrote: > > Move the cluster tables loading code out of the existing > > get_cluster_offset() function to avoid code duplication and implement it > > in separate get_cluster_table() and vmdk_L2load() functions. > > > > 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 <ashijeetacharya@gmail.com> > > --- > > block/vmdk.c | 337 > ++++++++++++++++++++++++++++++++++++++++++++++++++++++----- > > 1 file changed, 308 insertions(+), 29 deletions(-) > > > > diff --git a/block/vmdk.c b/block/vmdk.c > > index 73ae786..e5a289d 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 { > > @@ -254,6 +255,14 @@ static inline uint64_t > vmdk_find_offset_in_cluster(VmdkExtent *extent, > > return extent_relative_offset % cluster_size; > > } > > > > +static inline uint64_t size_to_clusters(VmdkExtent *extent, uint64_t > size) > > +{ > > + uint64_t cluster_size, round_off_size; > > + cluster_size = extent->cluster_sectors * BDRV_SECTOR_SIZE; > > + round_off_size = cluster_size - (size % cluster_size); > > + return DIV_ROUND_UP(size + round_off_size, BDRV_SECTOR_SIZE * 128) > - 1; > > What is (BDRV_SECTOR_SIZE * 128)? Do you mean extent->cluster_size? And > the > function doesn't make sense up to me. > > Just un-inline this to > > DIV_ROUND_UP(size, > extent->cluster_sectors << BDRV_SECTOR_BITS) - 1 > > in the calling site and be done with it. > > > +} > > + > > static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent) > > { > > char *desc; > > @@ -1028,6 +1037,133 @@ static void vmdk_refresh_limits(BlockDriverState > *bs, Error **errp) > > } > > } > > > > +static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data, > > + uint32_t offset) > > +{ > > + offset = cpu_to_le32(offset); > > + /* update L2 table */ > > + if (bdrv_pwrite_sync(extent->file, > > + ((int64_t)m_data->l2_offset * 512) > > + + (m_data->l2_index * sizeof(offset)), > > + &offset, sizeof(offset)) < 0) { > > + return VMDK_ERROR; > > + } > > + /* update backup L2 table */ > > + if (extent->l1_backup_table_offset != 0) { > > + m_data->l2_offset = extent->l1_backup_table[m_data->l1_index]; > > + if (bdrv_pwrite_sync(extent->file, > > + ((int64_t)m_data->l2_offset * 512) > > + + (m_data->l2_index * sizeof(offset)), > > + &offset, sizeof(offset)) < 0) { > > + return VMDK_ERROR; > > + } > > + } > > + if (m_data->l2_cache_entry) { > > + *m_data->l2_cache_entry = offset; > > + } > > + > > + return VMDK_OK; > > +} > > + > > +/* > > + * vmdk_l2load > > + * > > + * Loads a new L2 table into memory. If the table is in the cache, the > cache > > Not a native speaker, but s/Loads/Load/ feels more nature and consistent > with > other comments. > > > + * is used; otherwise the L2 table is loaded from the image file. > > + * > > + * Returns: > > + * VMDK_OK: on success > > + * VMDK_ERROR: in error cases > > + */ > > +static int vmdk_l2load(VmdkExtent *extent, uint64_t offset, int > l2_offset, > > + uint32_t **new_l2_table, int *new_l2_index) > > +{ > > + int min_index, i, j; > > + uint32_t *l2_table; > > + uint32_t min_count; > > + > > + for (i = 0; i < L2_CACHE_SIZE; i++) { > > + if (l2_offset == extent->l2_cache_offsets[i]) { > > + /* increment the hit count */ > > + if (++extent->l2_cache_counts[i] == UINT32_MAX) { > > + for (j = 0; j < L2_CACHE_SIZE; j++) { > > + extent->l2_cache_counts[j] >>= 1; > > + } > > + } > > + l2_table = extent->l2_cache + (i * extent->l2_size); > > + goto found; > > + } > > + } > > + /* not found: load a new entry in the least used one */ > > + min_index = 0; > > + min_count = UINT32_MAX; > > + for (i = 0; i < L2_CACHE_SIZE; i++) { > > + if (extent->l2_cache_counts[i] < min_count) { > > + min_count = extent->l2_cache_counts[i]; > > + min_index = i; > > + } > > + } > > + l2_table = extent->l2_cache + (min_index * extent->l2_size); > > + if (bdrv_pread(extent->file, > > + (int64_t)l2_offset * 512, > > + l2_table, > > + extent->l2_size * sizeof(uint32_t) > > + ) != extent->l2_size * sizeof(uint32_t)) { > > + return VMDK_ERROR; > > + } > > + > > + extent->l2_cache_offsets[min_index] = l2_offset; > > + extent->l2_cache_counts[min_index] = 1; > > +found: > > + *new_l2_index = ((offset >> 9) / extent->cluster_sectors) % > extent->l2_size; > > + *new_l2_table = l2_table; > > + > > + return VMDK_OK; > > +} > > + > > +/* > > + * get_cluster_table > > + * > > + * for a given offset, load (and allocate if needed) the l2 table. > > + * > > + * Returns: > > + * VMDK_OK: on success > > + * > > + * VMDK_UNALLOC: if cluster is not mapped > > + * > > + * VMDK_ERROR: in error cases > > + */ > > +static int get_cluster_table(VmdkExtent *extent, uint64_t offset, > > + int *new_l1_index, int *new_l2_offset, > > + int *new_l2_index, uint32_t **new_l2_table) > > +{ > > + int l1_index, l2_offset, l2_index; > > + uint32_t *l2_table; > > + int ret; > > + > > + offset -= (extent->end_sector - extent->sectors) * SECTOR_SIZE; > > + l1_index = (offset >> 9) / extent->l1_entry_sectors; > > + if (l1_index >= extent->l1_size) { > > + return VMDK_ERROR; > > + } > > + l2_offset = extent->l1_table[l1_index]; > > + if (!l2_offset) { > > + return VMDK_UNALLOC; > > + } > > + > > + ret = vmdk_l2load(extent, offset, l2_offset, &l2_table, &l2_index); > > + if (ret < 0) { > > + return ret; > > + } > > + > > + *new_l1_index = l1_index; > > + *new_l2_offset = l2_offset; > > + *new_l2_index = l2_index; > > + *new_l2_table = l2_table; > > + > > + return VMDK_OK; > > +} > > + > > Can you move this hunk into patch 4 and put it before this patch? It will > make > reviewing a bit easier. (Yes, this patch is already big.) > Right, I will change it to as you say. I know its big and I didn't like it either :( > > /* > > * vmdk_perform_cow > > * > > @@ -1115,29 +1251,168 @@ exit: > > return ret; > > } > > > > -static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data, > > - uint32_t offset) > > +/* > > + * handle_alloc > > + * > > + * Allocates new clusters for an area that either is yet unallocated or > needs a > > Similar to vmdk_l2load, s/Allocates/Allocate/ > > > + * copy on write. If *cluster_offset is non_zero, clusters are only > allocated if > > + * the new allocation can match the specified host offset. > > + * > > + * 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 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) > > { > > - offset = cpu_to_le32(offset); > > - /* update L2 table */ > > - if (bdrv_pwrite_sync(extent->file, > > - ((int64_t)m_data->l2_offset * 512) > > - + (m_data->l2_index * sizeof(offset)), > > - &offset, sizeof(offset)) < 0) { > > - return VMDK_ERROR; > > + 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; > > } > > - /* update backup L2 table */ > > - if (extent->l1_backup_table_offset != 0) { > > - m_data->l2_offset = extent->l1_backup_table[m_data->l1_index]; > > - if (bdrv_pwrite_sync(extent->file, > > - ((int64_t)m_data->l2_offset * 512) > > - + (m_data->l2_index * sizeof(offset)), > > - &offset, sizeof(offset)) < 0) { > > - return VMDK_ERROR; > > + > > + 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 it will > return one > > + * cluster less than the actual value calculated as we may need to > perfrom > > + * COW for the last one. */ > > + nb_clusters = size_to_clusters(extent, skip_start_bytes + *bytes); > > + > > + 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) << 9) > > + - skip_start_bytes; [continuation of why the while loop?]....here. So the bytes may get reduced if nb_clusters were more than 512 (l2 table margin) . Thus @remaining down there won't necessarily be zero after first pass. I hope I explained it correctly! > > > + } else { > > + nb_clusters = 1; > > + } > > + *total_alloc_clusters += nb_clusters; > > + 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; > > } > > } > > - if (m_data->l2_cache_entry) { > > - *m_data->l2_cache_entry = offset; > > + *cluster_offset = cluster_sector << BDRV_SECTOR_BITS; > > + return VMDK_OK; > > +} > > + > > +/* > > + * vmdk_alloc_cluster_offset > > Maybe just name it "vmdk_alloc_clusters", which sounds better to me? > Because the > clusters are what we allocate here, it's rather > "vmdk_alloc_clusters_and_get_offset" but we probably don't want it that > long. > > > + * > > + * 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 > > Thank you for adding the function documentations! > > > + */ > > +static int vmdk_alloc_cluster_offset(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; > > Here, in the first iteration, remaining == bytes and n_bytes == 0. > > > + new_cluster_offset += n_bytes; > > + > > + if (remaining == 0) { > > + break; > > + } > > + > > + n_bytes = remaining; > > Then n_bytes becomes bytes; > > In the second iteration, remaining is always 0 because of "remaining -= > n_bytes". What's the point of the while loop? I need the while loop in case if I truncate the bytes according to the L2 table margins....[scroll up to handle alloc() __^ ] Ashijeet
On Wed, 04/19 15:13, Ashijeet Acharya wrote: > > In the second iteration, remaining is always 0 because of "remaining -= > > n_bytes". What's the point of the while loop? > > > I need the while loop in case if I truncate the bytes according to the L2 > table margins....[scroll up to handle alloc() __^ ] Yes, I see it now. Fam
diff --git a/block/vmdk.c b/block/vmdk.c index 73ae786..e5a289d 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 { @@ -254,6 +255,14 @@ static inline uint64_t vmdk_find_offset_in_cluster(VmdkExtent *extent, return extent_relative_offset % cluster_size; } +static inline uint64_t size_to_clusters(VmdkExtent *extent, uint64_t size) +{ + uint64_t cluster_size, round_off_size; + cluster_size = extent->cluster_sectors * BDRV_SECTOR_SIZE; + round_off_size = cluster_size - (size % cluster_size); + return DIV_ROUND_UP(size + round_off_size, BDRV_SECTOR_SIZE * 128) - 1; +} + static uint32_t vmdk_read_cid(BlockDriverState *bs, int parent) { char *desc; @@ -1028,6 +1037,133 @@ static void vmdk_refresh_limits(BlockDriverState *bs, Error **errp) } } +static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data, + uint32_t offset) +{ + offset = cpu_to_le32(offset); + /* update L2 table */ + if (bdrv_pwrite_sync(extent->file, + ((int64_t)m_data->l2_offset * 512) + + (m_data->l2_index * sizeof(offset)), + &offset, sizeof(offset)) < 0) { + return VMDK_ERROR; + } + /* update backup L2 table */ + if (extent->l1_backup_table_offset != 0) { + m_data->l2_offset = extent->l1_backup_table[m_data->l1_index]; + if (bdrv_pwrite_sync(extent->file, + ((int64_t)m_data->l2_offset * 512) + + (m_data->l2_index * sizeof(offset)), + &offset, sizeof(offset)) < 0) { + return VMDK_ERROR; + } + } + if (m_data->l2_cache_entry) { + *m_data->l2_cache_entry = offset; + } + + return VMDK_OK; +} + +/* + * vmdk_l2load + * + * Loads a new 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: + * VMDK_OK: on success + * VMDK_ERROR: in error cases + */ +static int vmdk_l2load(VmdkExtent *extent, uint64_t offset, int l2_offset, + uint32_t **new_l2_table, int *new_l2_index) +{ + int min_index, i, j; + uint32_t *l2_table; + uint32_t min_count; + + for (i = 0; i < L2_CACHE_SIZE; i++) { + if (l2_offset == extent->l2_cache_offsets[i]) { + /* increment the hit count */ + if (++extent->l2_cache_counts[i] == UINT32_MAX) { + for (j = 0; j < L2_CACHE_SIZE; j++) { + extent->l2_cache_counts[j] >>= 1; + } + } + l2_table = extent->l2_cache + (i * extent->l2_size); + goto found; + } + } + /* not found: load a new entry in the least used one */ + min_index = 0; + min_count = UINT32_MAX; + for (i = 0; i < L2_CACHE_SIZE; i++) { + if (extent->l2_cache_counts[i] < min_count) { + min_count = extent->l2_cache_counts[i]; + min_index = i; + } + } + l2_table = extent->l2_cache + (min_index * extent->l2_size); + if (bdrv_pread(extent->file, + (int64_t)l2_offset * 512, + l2_table, + extent->l2_size * sizeof(uint32_t) + ) != extent->l2_size * sizeof(uint32_t)) { + return VMDK_ERROR; + } + + extent->l2_cache_offsets[min_index] = l2_offset; + extent->l2_cache_counts[min_index] = 1; +found: + *new_l2_index = ((offset >> 9) / extent->cluster_sectors) % extent->l2_size; + *new_l2_table = l2_table; + + return VMDK_OK; +} + +/* + * get_cluster_table + * + * for a given offset, load (and allocate if needed) the l2 table. + * + * Returns: + * VMDK_OK: on success + * + * VMDK_UNALLOC: if cluster is not mapped + * + * VMDK_ERROR: in error cases + */ +static int get_cluster_table(VmdkExtent *extent, uint64_t offset, + int *new_l1_index, int *new_l2_offset, + int *new_l2_index, uint32_t **new_l2_table) +{ + int l1_index, l2_offset, l2_index; + uint32_t *l2_table; + int ret; + + offset -= (extent->end_sector - extent->sectors) * SECTOR_SIZE; + l1_index = (offset >> 9) / extent->l1_entry_sectors; + if (l1_index >= extent->l1_size) { + return VMDK_ERROR; + } + l2_offset = extent->l1_table[l1_index]; + if (!l2_offset) { + return VMDK_UNALLOC; + } + + ret = vmdk_l2load(extent, offset, l2_offset, &l2_table, &l2_index); + if (ret < 0) { + return ret; + } + + *new_l1_index = l1_index; + *new_l2_offset = l2_offset; + *new_l2_index = l2_index; + *new_l2_table = l2_table; + + return VMDK_OK; +} + /* * vmdk_perform_cow * @@ -1115,29 +1251,168 @@ exit: return ret; } -static int vmdk_L2update(VmdkExtent *extent, VmdkMetaData *m_data, - uint32_t offset) +/* + * handle_alloc + * + * Allocates new clusters for an area that either is yet unallocated or needs a + * copy on write. If *cluster_offset is non_zero, clusters are only allocated if + * the new allocation can match the specified host offset. + * + * 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 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) { - offset = cpu_to_le32(offset); - /* update L2 table */ - if (bdrv_pwrite_sync(extent->file, - ((int64_t)m_data->l2_offset * 512) - + (m_data->l2_index * sizeof(offset)), - &offset, sizeof(offset)) < 0) { - return VMDK_ERROR; + 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; } - /* update backup L2 table */ - if (extent->l1_backup_table_offset != 0) { - m_data->l2_offset = extent->l1_backup_table[m_data->l1_index]; - if (bdrv_pwrite_sync(extent->file, - ((int64_t)m_data->l2_offset * 512) - + (m_data->l2_index * sizeof(offset)), - &offset, sizeof(offset)) < 0) { - return VMDK_ERROR; + + 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 it will return one + * cluster less than the actual value calculated as we may need to perfrom + * COW for the last one. */ + nb_clusters = size_to_clusters(extent, skip_start_bytes + *bytes); + + 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) << 9) + - skip_start_bytes; + } else { + nb_clusters = 1; + } + *total_alloc_clusters += nb_clusters; + 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; } } - if (m_data->l2_cache_entry) { - *m_data->l2_cache_entry = offset; + *cluster_offset = cluster_sector << BDRV_SECTOR_BITS; + return VMDK_OK; +} + +/* + * vmdk_alloc_cluster_offset + * + * 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_cluster_offset(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 = handle_alloc(bs, extent, start, &new_cluster_offset, &n_bytes, + m_data, allocate, total_alloc_clusters); + + if (ret < 0) { + return ret; + + } } return VMDK_OK; @@ -1567,6 +1842,7 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, uint64_t cluster_offset; uint64_t bytes_done = 0; VmdkMetaData m_data; + uint32_t total_alloc_clusters = 0; if (DIV_ROUND_UP(offset, BDRV_SECTOR_SIZE) > bs->total_sectors) { error_report("Wrong offset: offset=0x%" PRIx64 @@ -1584,10 +1860,10 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, n_bytes = MIN(bytes, extent->cluster_sectors * BDRV_SECTOR_SIZE - offset_in_cluster); - ret = get_cluster_offset(bs, extent, &m_data, offset, - !(extent->compressed || zeroed), - &cluster_offset, offset_in_cluster, - offset_in_cluster + n_bytes); + ret = vmdk_alloc_cluster_offset(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 */ @@ -1596,19 +1872,22 @@ static int vmdk_pwritev(BlockDriverState *bs, uint64_t offset, return -EIO; } else { /* allocate */ - ret = get_cluster_offset(bs, extent, &m_data, offset, - true, &cluster_offset, 0, 0); + ret = vmdk_alloc_cluster_offset(bs, extent, &m_data, offset, + true, &cluster_offset, n_bytes, + &total_alloc_clusters); } } if (ret == VMDK_ERROR) { return -EINVAL; } + 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)
Move the cluster tables loading code out of the existing get_cluster_offset() function to avoid code duplication and implement it in separate get_cluster_table() and vmdk_L2load() functions. 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 <ashijeetacharya@gmail.com> --- block/vmdk.c | 337 ++++++++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 308 insertions(+), 29 deletions(-)