From c35749fb3959f2d09b233571b2a3a36ce40c933a Mon Sep 17 00:00:00 2001
From: Anatol Belski <anbelski@linux.microsoft.com>
Date: Wed, 15 Apr 2026 15:37:55 +0200
Subject: [PATCH] block: qcow: Rename Qcow2MetadataBacking to Qcow2Backing

The old name read as 'metadata for a QCOW2 backing file' rather
than what it actually is: a QCOW2 backing file reader. Rename to
Qcow2Backing to parallel RawBacking and clarify intent.

Suggested-by: Philipp Schuster <philipp.schuster@cyberus-technology.de>
Signed-off-by: Anatol Belski <anbelski@linux.microsoft.com>
---
 block/src/qcow/backing.rs | 12 ++++++------
 block/src/qcow_sync.rs    |  4 ++--
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/block/src/qcow/backing.rs b/block/src/qcow/backing.rs
index e5e037b0a..754618f13 100644
--- a/block/src/qcow/backing.rs
+++ b/block/src/qcow/backing.rs
@@ -48,7 +48,7 @@ impl BackingRead for RawBacking {
 /// tables, refcounts) before reading the underlying data. Read only
 /// because backing files never receive writes. Nested backing chains
 /// are handled recursively via the optional `backing_file` field.
-pub(crate) struct Qcow2MetadataBacking {
+pub(crate) struct Qcow2Backing {
     pub(crate) metadata: Arc<QcowMetadata>,
     pub(crate) data_fd: OwnedFd,
     pub(crate) backing_file: Option<Arc<dyn BackingRead>>,
@@ -56,9 +56,9 @@ pub(crate) struct Qcow2MetadataBacking {
 
 // SAFETY: All reads go through QcowMetadata which uses RwLock
 // and pread64 which is position independent and thread safe.
-unsafe impl Sync for Qcow2MetadataBacking {}
+unsafe impl Sync for Qcow2Backing {}
 
-impl BackingRead for Qcow2MetadataBacking {
+impl BackingRead for Qcow2Backing {
     fn read_at(&self, address: u64, buf: &mut [u8]) -> io::Result<()> {
         let virtual_size = self.metadata.virtual_size();
         if address >= virtual_size {
@@ -75,7 +75,7 @@ impl BackingRead for Qcow2MetadataBacking {
     }
 }
 
-impl Qcow2MetadataBacking {
+impl Qcow2Backing {
     /// Resolve cluster mappings via metadata then read allocated clusters
     /// with pread64.
     fn read_clusters(&self, address: u64, buf: &mut [u8]) -> io::Result<()> {
@@ -125,7 +125,7 @@ impl Qcow2MetadataBacking {
     }
 }
 
-impl Drop for Qcow2MetadataBacking {
+impl Drop for Qcow2Backing {
     fn drop(&mut self) {
         self.metadata.shutdown();
     }
@@ -152,7 +152,7 @@ pub fn shared_backing_from(bf: BackingFile) -> BlockResult<Arc<dyn BackingRead>>
         }
         BackingKind::Qcow { inner, backing } => {
             let data_fd = dup_fd(inner.raw_file.as_fd())?;
-            Ok(Arc::new(Qcow2MetadataBacking {
+            Ok(Arc::new(Qcow2Backing {
                 metadata: Arc::new(QcowMetadata::new(*inner)),
                 data_fd,
                 backing_file: backing.map(|bf| shared_backing_from(*bf)).transpose()?,
diff --git a/block/src/qcow_sync.rs b/block/src/qcow_sync.rs
index f948a3b5f..ec1637543 100644
--- a/block/src/qcow_sync.rs
+++ b/block/src/qcow_sync.rs
@@ -783,7 +783,7 @@ mod unit_tests {
 
     #[test]
     fn test_multi_queue_concurrent_reads_qcow2_backing() {
-        // Same as above but reads go through a Qcow2MetadataBacking,
+        // Same as above but reads go through a Qcow2Backing,
         // exercising concurrent metadata resolution + pread64 in the backing.
         let backing_temp = TempFile::new().unwrap();
         let cluster_size = 1u64 << 16;
@@ -1123,7 +1123,7 @@ mod unit_tests {
     #[test]
     fn test_qcow2_backing_cross_cluster_read() {
         // Read spanning a cluster boundary through qcow2 backing.
-        // Exercises the read_clusters loop in Qcow2MetadataBacking.
+        // Exercises the read_clusters loop in Qcow2Backing.
         let cluster_size = 1u64 << 16;
         let file_size = cluster_size * 4;
         let pattern: Vec<u8> = (0..file_size as usize).map(|i| (i % 251) as u8).collect();