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qcow: Fix the calculation of the number of clusters for L1 table

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In function create_for_size(), when calculating the number
of clusters for the L1 table, it incorrectly divides the total number of
entries in the L1 table by the cluster size. In fact, it should be
divided by the number of entries/addresses that can fit into a cluster.

Signed-off-by: lv.mengzhao <lv.mengzhao@zte.com.cn>
This commit is contained in:
lv.mengzhao 2022-10-12 18:54:41 +08:00 committed by Rob Bradford
parent 099cdd2af8
commit 2a45e44bda
1 changed files with 9 additions and 8 deletions
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17
qcow/src/qcow.rs
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@ -255,10 +255,10 @@ impl QcowHeader {
let cluster_bits: u32 = DEFAULT_CLUSTER_BITS; let cluster_bits: u32 = DEFAULT_CLUSTER_BITS;
let cluster_size: u32 = 0x01 << cluster_bits; let cluster_size: u32 = 0x01 << cluster_bits;
// L2 blocks are always one cluster long. They contain cluster_size/sizeof(u64) addresses. // L2 blocks are always one cluster long. They contain cluster_size/sizeof(u64) addresses.
let l2_size: u32 = cluster_size / size_of::<u64>() as u32; let entries_per_cluster: u32 = cluster_size / size_of::<u64>() as u32;
let num_clusters: u32 = div_round_up_u64(size, u64::from(cluster_size)) as u32; let num_clusters: u32 = div_round_up_u64(size, u64::from(cluster_size)) as u32;
let num_l2_clusters: u32 = div_round_up_u32(num_clusters, l2_size); let num_l2_clusters: u32 = div_round_up_u32(num_clusters, entries_per_cluster);
let l1_clusters: u32 = div_round_up_u32(num_l2_clusters, cluster_size); let l1_clusters: u32 = div_round_up_u32(num_l2_clusters, entries_per_cluster);
let header_clusters = div_round_up_u32(size_of::<QcowHeader>() as u32, cluster_size); let header_clusters = div_round_up_u32(size_of::<QcowHeader>() as u32, cluster_size);
QcowHeader { QcowHeader {
magic: QCOW_MAGIC, magic: QCOW_MAGIC,
@ -473,10 +473,10 @@ impl QcowFile {
QcowFile::rebuild_refcounts(&mut raw_file, header)?; QcowFile::rebuild_refcounts(&mut raw_file, header)?;
} }
let l2_size = cluster_size / size_of::<u64>() as u64; let entries_per_cluster = cluster_size / size_of::<u64>() as u64;
let num_clusters = div_round_up_u64(header.size, cluster_size); let num_clusters = div_round_up_u64(header.size, cluster_size);
let num_l2_clusters = div_round_up_u64(num_clusters, l2_size); let num_l2_clusters = div_round_up_u64(num_clusters, entries_per_cluster);
let l1_clusters = div_round_up_u64(num_l2_clusters, cluster_size); let l1_clusters = div_round_up_u64(num_l2_clusters, entries_per_cluster);
let header_clusters = div_round_up_u64(size_of::<QcowHeader>() as u64, cluster_size); let header_clusters = div_round_up_u64(size_of::<QcowHeader>() as u64, cluster_size);
if num_l2_clusters > MAX_RAM_POINTER_TABLE_SIZE { if num_l2_clusters > MAX_RAM_POINTER_TABLE_SIZE {
return Err(Error::TooManyL1Entries(num_l2_clusters)); return Err(Error::TooManyL1Entries(num_l2_clusters));
@ -705,7 +705,8 @@ impl QcowFile {
header: QcowHeader, header: QcowHeader,
cluster_size: u64, cluster_size: u64,
) -> Result<()> { ) -> Result<()> {
let l1_clusters = div_round_up_u64(u64::from(header.l1_size), cluster_size); let entries_per_cluster = cluster_size / size_of::<u64>() as u64;
let l1_clusters = div_round_up_u64(u64::from(header.l1_size), entries_per_cluster);
let l1_table_offset = header.l1_table_offset; let l1_table_offset = header.l1_table_offset;
for i in 0..l1_clusters { for i in 0..l1_clusters {
add_ref(refcounts, cluster_size, l1_table_offset + i * cluster_size)?; add_ref(refcounts, cluster_size, l1_table_offset + i * cluster_size)?;
@ -872,7 +873,7 @@ impl QcowFile {
let pointers_per_cluster = cluster_size / size_of::<u64>() as u64; let pointers_per_cluster = cluster_size / size_of::<u64>() as u64;
let data_clusters = div_round_up_u64(header.size, cluster_size); let data_clusters = div_round_up_u64(header.size, cluster_size);
let l2_clusters = div_round_up_u64(data_clusters, pointers_per_cluster); let l2_clusters = div_round_up_u64(data_clusters, pointers_per_cluster);
let l1_clusters = div_round_up_u64(l2_clusters, cluster_size); let l1_clusters = div_round_up_u64(l2_clusters, pointers_per_cluster);
let header_clusters = div_round_up_u64(size_of::<QcowHeader>() as u64, cluster_size); let header_clusters = div_round_up_u64(size_of::<QcowHeader>() as u64, cluster_size);
let max_clusters = data_clusters + l2_clusters + l1_clusters + header_clusters; let max_clusters = data_clusters + l2_clusters + l1_clusters + header_clusters;
let mut max_valid_cluster_index = max_clusters; let mut max_valid_cluster_index = max_clusters;