mm: expand vma iterator interface

Add wrappers for the maple tree to the vma iterator.  This will provide
type safety at compile time.

Link: https://lkml.kernel.org/r/20230120162650.984577-8-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 64 insertions, 0 deletions

diff --git a/mm/internal.h b/mm/internal.h
index 2d1b9fa8083e..ffd65248f266 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -877,4 +877,68 @@ static inline bool vma_soft_dirty_enabled(struct vm_area_struct *vma)
 	return !(vma->vm_flags & VM_SOFTDIRTY);
 }
 
+/*
+ * VMA Iterator functions shared between nommu and mmap
+ */
+static inline int vma_iter_prealloc(struct vma_iterator *vmi)
+{
+	return mas_preallocate(&vmi->mas, GFP_KERNEL);
+}
+
+static inline void vma_iter_clear(struct vma_iterator *vmi,
+				  unsigned long start, unsigned long end)
+{
+	mas_set_range(&vmi->mas, start, end - 1);
+	mas_store_prealloc(&vmi->mas, NULL);
+}
+
+static inline struct vm_area_struct *vma_iter_load(struct vma_iterator *vmi)
+{
+	return mas_walk(&vmi->mas);
+}
+
+/* Store a VMA with preallocated memory */
+static inline void vma_iter_store(struct vma_iterator *vmi,
+				  struct vm_area_struct *vma)
+{
+
+#if defined(CONFIG_DEBUG_VM_MAPLE_TREE)
+	if (WARN_ON(vmi->mas.node != MAS_START && vmi->mas.index > vma->vm_start)) {
+		printk("%lu > %lu\n", vmi->mas.index, vma->vm_start);
+		printk("store of vma %lu-%lu", vma->vm_start, vma->vm_end);
+		printk("into slot    %lu-%lu", vmi->mas.index, vmi->mas.last);
+		mt_dump(vmi->mas.tree);
+	}
+	if (WARN_ON(vmi->mas.node != MAS_START && vmi->mas.last <  vma->vm_start)) {
+		printk("%lu < %lu\n", vmi->mas.last, vma->vm_start);
+		printk("store of vma %lu-%lu", vma->vm_start, vma->vm_end);
+		printk("into slot    %lu-%lu", vmi->mas.index, vmi->mas.last);
+		mt_dump(vmi->mas.tree);
+	}
+#endif
+
+	if (vmi->mas.node != MAS_START &&
+	    ((vmi->mas.index > vma->vm_start) || (vmi->mas.last < vma->vm_start)))
+		vma_iter_invalidate(vmi);
+
+	vmi->mas.index = vma->vm_start;
+	vmi->mas.last = vma->vm_end - 1;
+	mas_store_prealloc(&vmi->mas, vma);
+}
+
+static inline int vma_iter_store_gfp(struct vma_iterator *vmi,
+			struct vm_area_struct *vma, gfp_t gfp)
+{
+	if (vmi->mas.node != MAS_START &&
+	    ((vmi->mas.index > vma->vm_start) || (vmi->mas.last < vma->vm_start)))
+		vma_iter_invalidate(vmi);
+
+	vmi->mas.index = vma->vm_start;
+	vmi->mas.last = vma->vm_end - 1;
+	mas_store_gfp(&vmi->mas, vma, gfp);
+	if (unlikely(mas_is_err(&vmi->mas)))
+		return -ENOMEM;
+
+	return 0;
+}
 #endif	/* __MM_INTERNAL_H */