rbd: fix DiffIterateByID Length to exclude startingOffset

kaovilai · claude · happy-otter · kaovilai · commit 41d995bf5bd0 · 2026-03-24T18:44:44.000-04:00
The Length parameter in DiffIterateByIDConfig was set to the full VolSize, but rbd_diff_iterate3 treats len as the number of bytes to scan from ofs. When startingOffset > 0, this caused the scan range to extend past the image end (scanning [startingOffset, startingOffset + VolSize) instead of [startingOffset, VolSize)). Fix by subtracting startingOffset from VolSize to get the correct scan length. Ref: kaovilai/cephcsi-cbt-e2e#2 Generated with [Claude Code](https://claude.ai/code) via [Happy](https://happy.engineering) Co-Authored-By: Claude <noreply@anthropic.com> Co-Authored-By: Happy <yesreply@happy.engineering> Signed-off-by: Tiger Kaovilai <tkaovila@redhat.com> Signed-off-by: Tiger Kaovilai <passawit.kaovilai@gmail.com>
diff --git a/internal/rbd/snap_diff.go b/internal/rbd/snap_diff.go
@@ -98,7 +98,7 @@ func (rbdSnap *rbdSnapshot) ProcessMetadata(
 	)
 	diffIterateByIDConfig := librbd.DiffIterateByIDConfig{
 		Offset:   uint64(startingOffset),
-		Length:   uint64(rbdSnap.VolSize),
+		Length:   uint64(rbdSnap.VolSize) - uint64(startingOffset),
 		Callback: cb,
 	}
 	if baseSnap != nil {

Original file line number	Diff line number	Diff line change
`@@ -98,7 +98,7 @@ func (rbdSnap *rbdSnapshot) ProcessMetadata(`
`98`	`98`	`)`
`99`	`99`	`diffIterateByIDConfig := librbd.DiffIterateByIDConfig{`
`100`	`100`	`Offset: uint64(startingOffset),`
`101`		`- Length: uint64(rbdSnap.VolSize),`
	`101`	`+ Length: uint64(rbdSnap.VolSize) - uint64(startingOffset),`
`102`	`102`	`Callback: cb,`
`103`	`103`	`}`
`104`	`104`	`if baseSnap != nil {`