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block: qcow: Set OFLAG_COPIED bit in L1 entries for QCOW2 spec compli… #7526

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Merged
rbradford merged 1 commit into from
Dec 1, 2025
Merged

block: qcow: Set OFLAG_COPIED bit in L1 entries for QCOW2 spec compli… #7526

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29 changes: 24 additions & 5 deletions block/src/qcow/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -207,6 +207,11 @@ fn l2_entry_make_std(cluster_addr: u64) -> u64 {
(cluster_addr & L2_TABLE_OFFSET_MASK) | CLUSTER_USED_FLAG
}

// Make L1 entry with optional flags
fn l1_entry_make(cluster_addr: u64, refcount_is_one: bool) -> u64 {
(cluster_addr & L1_TABLE_OFFSET_MASK) | (refcount_is_one as u64 * CLUSTER_USED_FLAG)
}

/// Contains the information from the header of a qcow file.
#[derive(Clone, Debug)]
pub struct QcowHeader {
Expand Down Expand Up @@ -1571,11 +1576,25 @@ impl QcowFile {
// Push L1 table and refcount table last as all the clusters they point to are now
// guaranteed to be valid.
let mut sync_required = if self.l1_table.dirty() {
self.raw_file.write_pointer_table(
self.header.l1_table_offset,
self.l1_table.get_values(),
0,
)?;
// Build L1 table with OFLAG_COPIED bits set correctly based on L2 cluster refcounts
let l1_active: Vec<u64> = self
.l1_table
.get_values()
.iter()
.map(|&l2_addr| {
if l2_addr == 0 {
Ok(0)
} else {
let refcount = self
.refcounts
.get_cluster_refcount(&mut self.raw_file, l2_addr)
.map_err(|e| std::io::Error::other(Error::GettingRefcount(e)))?;
Ok(l1_entry_make(l2_addr, refcount == 1))
}
})
.collect::<io::Result<Vec<u64>>>()?;
self.raw_file
.write_pointer_table(self.header.l1_table_offset, &l1_active, 0)?;
self.l1_table.mark_clean();
true
} else {
Expand Down
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