[LoRA] feat: support more Qwen LoRAs from the community. (huggingface#12170)

* feat: support more Qwen LoRAs from the community.

* revert unrelated changes.

* Revert "revert unrelated changes."

This reverts commit 82dea55.

Author: sayakpaul

src/diffusers/loaders/lora_conversion_utils.py

@@ -2080,6 +2080,74 @@ def _convert_non_diffusers_ltxv_lora_to_diffusers(state_dict, non_diffusers_pref
 
 
 def _convert_non_diffusers_qwen_lora_to_diffusers(state_dict):
+    has_lora_unet = any(k.startswith("lora_unet_") for k in state_dict)
+    if has_lora_unet:
+        state_dict = {k.removeprefix("lora_unet_"): v for k, v in state_dict.items()}
+
+        def convert_key(key: str) -> str:
+            prefix = "transformer_blocks"
+            if "." in key:
+                base, suffix = key.rsplit(".", 1)
+            else:
+                base, suffix = key, ""
+
+            start = f"{prefix}_"
+            rest = base[len(start) :]
+
+            if "." in rest:
+                head, tail = rest.split(".", 1)
+                tail = "." + tail
+            else:
+                head, tail = rest, ""
+
+            # Protected n-grams that must keep their internal underscores
+            protected = {
+                # pairs
+                ("to", "q"),
+                ("to", "k"),
+                ("to", "v"),
+                ("to", "out"),
+                ("add", "q"),
+                ("add", "k"),
+                ("add", "v"),
+                ("txt", "mlp"),
+                ("img", "mlp"),
+                ("txt", "mod"),
+                ("img", "mod"),
+                # triplets
+                ("add", "q", "proj"),
+                ("add", "k", "proj"),
+                ("add", "v", "proj"),
+                ("to", "add", "out"),
+            }
+
+            prot_by_len = {}
+            for ng in protected:
+                prot_by_len.setdefault(len(ng), set()).add(ng)
+
+            parts = head.split("_")
+            merged = []
+            i = 0
+            lengths_desc = sorted(prot_by_len.keys(), reverse=True)
+
+            while i < len(parts):
+                matched = False
+                for L in lengths_desc:
+                    if i + L <= len(parts) and tuple(parts[i : i + L]) in prot_by_len[L]:
+                        merged.append("_".join(parts[i : i + L]))
+                        i += L
+                        matched = True
+                        break
+                if not matched:
+                    merged.append(parts[i])
+                    i += 1
+
+            head_converted = ".".join(merged)
+            converted_base = f"{prefix}.{head_converted}{tail}"
+            return converted_base + (("." + suffix) if suffix else "")
+
+        state_dict = {convert_key(k): v for k, v in state_dict.items()}
+
     converted_state_dict = {}
     all_keys = list(state_dict.keys())
     down_key = ".lora_down.weight"

src/diffusers/loaders/lora_pipeline.py

@@ -6643,7 +6643,8 @@ def lora_state_dict(
             state_dict = {k: v for k, v in state_dict.items() if "dora_scale" not in k}
 
         has_alphas_in_sd = any(k.endswith(".alpha") for k in state_dict)
-        if has_alphas_in_sd:
+        has_lora_unet = any(k.startswith("lora_unet_") for k in state_dict)
+        if has_alphas_in_sd or has_lora_unet:
             state_dict = _convert_non_diffusers_qwen_lora_to_diffusers(state_dict)
 
         out = (state_dict, metadata) if return_lora_metadata else state_dict