powerpc: Convert mmu context allocator from idr to ida

We can use the much more lightweight ida allocator since we don't
need the pointer storage idr provides.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/mm/mmu_context_hash64.c

@@ -23,7 +23,7 @@
 #include <asm/mmu_context.h>
 
 static DEFINE_SPINLOCK(mmu_context_lock);
-static DEFINE_IDR(mmu_context_idr);
+static DEFINE_IDA(mmu_context_ida);
 
 /*
  * The proto-VSID space has 2^35 - 1 segments available for user mappings.
@@ -39,11 +39,11 @@ int __init_new_context(void)
 	int err;
 
 again:
-	if (!idr_pre_get(&mmu_context_idr, GFP_KERNEL))
+	if (!ida_pre_get(&mmu_context_ida, GFP_KERNEL))
 		return -ENOMEM;
 
 	spin_lock(&mmu_context_lock);
-	err = idr_get_new_above(&mmu_context_idr, NULL, 1, &index);
+	err = ida_get_new_above(&mmu_context_ida, 1, &index);
 	spin_unlock(&mmu_context_lock);
 
 	if (err == -EAGAIN)
@@ -53,7 +53,7 @@ again:
 
 	if (index > MAX_CONTEXT) {
 		spin_lock(&mmu_context_lock);
-		idr_remove(&mmu_context_idr, index);
+		ida_remove(&mmu_context_ida, index);
 		spin_unlock(&mmu_context_lock);
 		return -ENOMEM;
 	}
@@ -85,7 +85,7 @@ int init_new_context(struct task_struct *tsk, struct mm_struct *mm)
 void __destroy_context(int context_id)
 {
 	spin_lock(&mmu_context_lock);
-	idr_remove(&mmu_context_idr, context_id);
+	ida_remove(&mmu_context_ida, context_id);
 	spin_unlock(&mmu_context_lock);
 }
 EXPORT_SYMBOL_GPL(__destroy_context);