layout: Add generators for refcount table and blocks
Refcount structures are placed in clusters randomly selected from all unallocated host clusters. Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Signed-off-by: Maria Kustova <maria.k@catit.be> Reviewed-by: Fam Zheng <famz@redhat.com> Message-id: 7e2f38608db6fba2da53997390b19400d445c45d.1408450493.git.maria.k@catit.be Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
This commit is contained in:
Maria Kustova
Stefan Hajnoczi
parent
2e5be6b77e
commit
1e8fd8d44d
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@ -102,6 +102,8 @@ class Image(object):
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self.end_of_extension_area = FieldsList()
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self.l2_tables = FieldsList()
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self.l1_table = FieldsList()
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self.refcount_table = FieldsList()
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self.refcount_blocks = FieldsList()
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self.ext_offset = 0
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self.create_header(cluster_bits, backing_file_name)
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self.set_backing_file_name(backing_file_name)
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@ -113,7 +115,8 @@ class Image(object):
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def __iter__(self):
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return chain(self.header, self.backing_file_format,
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self.feature_name_table, self.end_of_extension_area,
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self.backing_file_name, self.l1_table, self.l2_tables)
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self.backing_file_name, self.l1_table, self.l2_tables,
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self.refcount_table, self.refcount_blocks)
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def create_header(self, cluster_bits, backing_file_name=None):
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"""Generate a random valid header."""
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@ -330,6 +333,138 @@ class Image(object):
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float(self.cluster_size**2)))
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self.header['l1_table_offset'][0].value = l1_offset
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def create_refcount_structures(self):
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"""Generate random refcount blocks and refcount table."""
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def allocate_rfc_blocks(data, size):
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"""Return indices of clusters allocated for refcount blocks."""
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cluster_ids = set()
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diff = block_ids = set([x / size for x in data])
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while len(diff) != 0:
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# Allocate all yet not allocated clusters
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new = self._get_available_clusters(data | cluster_ids,
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len(diff))
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# Indices of new refcount blocks necessary to cover clusters
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# in 'new'
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diff = set([x / size for x in new]) - block_ids
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cluster_ids |= new
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block_ids |= diff
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return cluster_ids, block_ids
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def allocate_rfc_table(data, init_blocks, block_size):
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"""Return indices of clusters allocated for the refcount table
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and updated indices of clusters allocated for blocks and indices
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of blocks.
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"""
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blocks = set(init_blocks)
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clusters = set()
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# Number of entries in one cluster of the refcount table
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size = self.cluster_size / UINT64_S
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# Number of clusters necessary for the refcount table based on
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# the current number of refcount blocks
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table_size = int(ceil((max(blocks) + 1) / float(size)))
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# Index of the first cluster of the refcount table
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table_start = self._get_adjacent_clusters(data, table_size + 1)
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# Clusters allocated for the current length of the refcount table
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table_clusters = set(range(table_start, table_start + table_size))
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# Clusters allocated for the refcount table including
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# last optional one for potential l1 growth
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table_clusters_allocated = set(range(table_start, table_start +
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table_size + 1))
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# New refcount blocks necessary for clusters occupied by the
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# refcount table
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diff = set([c / block_size for c in table_clusters]) - blocks
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blocks |= diff
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while len(diff) != 0:
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# Allocate clusters for new refcount blocks
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new = self._get_available_clusters((data | clusters) |
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table_clusters_allocated,
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len(diff))
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# Indices of new refcount blocks necessary to cover
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# clusters in 'new'
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diff = set([x / block_size for x in new]) - blocks
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clusters |= new
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blocks |= diff
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# Check if the refcount table needs one more cluster
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if int(ceil((max(blocks) + 1) / float(size))) > table_size:
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new_block_id = (table_start + table_size) / block_size
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# Check if the additional table cluster needs
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# one more refcount block
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if new_block_id not in blocks:
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diff.add(new_block_id)
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table_clusters.add(table_start + table_size)
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table_size += 1
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return table_clusters, blocks, clusters
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def create_table_entry(table_offset, block_cluster, block_size,
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cluster):
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"""Generate a refcount table entry."""
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offset = table_offset + UINT64_S * (cluster / block_size)
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return ['>Q', offset, block_cluster * self.cluster_size,
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'refcount_table_entry']
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def create_block_entry(block_cluster, block_size, cluster):
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"""Generate a list of entries for the current block."""
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entry_size = self.cluster_size / block_size
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offset = block_cluster * self.cluster_size
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entry_offset = offset + entry_size * (cluster % block_size)
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# While snapshots are not supported all refcounts are set to 1
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return ['>H', entry_offset, 1, 'refcount_block_entry']
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# Size of a block entry in bits
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refcount_bits = 1 << self.header['refcount_order'][0].value
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# Number of refcount entries per refcount block
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# Convert self.cluster_size from bytes to bits to have the same
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# base for the numerator and denominator
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block_size = self.cluster_size * 8 / refcount_bits
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meta_data = self._get_metadata()
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if len(self.data_clusters) == 0:
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# All metadata for an empty guest image needs 4 clusters:
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# header, rfc table, rfc block, L1 table.
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# Header takes cluster #0, other clusters ##1-3 can be used
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block_clusters = set([random.choice(list(set(range(1, 4)) -
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meta_data))])
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block_ids = set([0])
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table_clusters = set([random.choice(list(set(range(1, 4)) -
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meta_data -
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block_clusters))])
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else:
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block_clusters, block_ids = \
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allocate_rfc_blocks(self.data_clusters |
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meta_data, block_size)
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table_clusters, block_ids, new_clusters = \
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allocate_rfc_table(self.data_clusters |
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meta_data |
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block_clusters,
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block_ids,
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block_size)
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block_clusters |= new_clusters
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meta_data |= block_clusters | table_clusters
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table_offset = min(table_clusters) * self.cluster_size
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block_id = None
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# Clusters allocated for refcount blocks
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block_clusters = list(block_clusters)
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# Indices of refcount blocks
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block_ids = list(block_ids)
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# Refcount table entries
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rfc_table = []
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# Refcount entries
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rfc_blocks = []
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for cluster in sorted(self.data_clusters | meta_data):
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if cluster / block_size != block_id:
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block_id = cluster / block_size
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block_cluster = block_clusters[block_ids.index(block_id)]
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rfc_table.append(create_table_entry(table_offset,
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block_cluster,
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block_size, cluster))
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rfc_blocks.append(create_block_entry(block_cluster, block_size,
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cluster))
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self.refcount_table = FieldsList(rfc_table)
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self.refcount_blocks = FieldsList(rfc_blocks)
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self.header['refcount_table_offset'][0].value = table_offset
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self.header['refcount_table_clusters'][0].value = len(table_clusters)
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def fuzz(self, fields_to_fuzz=None):
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"""Fuzz an image by corrupting values of a random subset of its fields.
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@ -471,6 +606,7 @@ def create_image(test_img_path, backing_file_name=None, backing_file_fmt=None,
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image.create_feature_name_table()
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image.set_end_of_extension_area()
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image.create_l_structures()
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image.create_refcount_structures()
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image.fuzz(fields_to_fuzz)
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image.write(test_img_path)
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return image.image_size
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