mm: Use maple tree operations for find_vma_intersection()

Move find_vma_intersection() to mmap.c and change implementation to
maple tree.

When searching for a vma within a range, it is easier to use the maple
tree interface.

Exported find_vma_intersection() for kvm module.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 965298bba99527c11fd96aa20dd5ba705a8ad9ca..dba94d6524d57f5b469e2df991a8b320a8bba1a7 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2784,26 +2784,13 @@ extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long add
 extern struct vm_area_struct * find_vma_prev(struct mm_struct * mm, unsigned long addr,
                                             struct vm_area_struct **pprev);
 
-/**
- * find_vma_intersection() - Look up the first VMA which intersects the interval
- * @mm: The process address space.
- * @start_addr: The inclusive start user address.
- * @end_addr: The exclusive end user address.
- *
- * Returns: The first VMA within the provided range, %NULL otherwise.  Assumes
- * start_addr < end_addr.
+/*
+ * Look up the first VMA which intersects the interval [start_addr, end_addr)
+ * NULL if none.  Assume start_addr < end_addr.
  */
-static inline
-struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
-                                            unsigned long start_addr,
-                                            unsigned long end_addr)
-{
-       struct vm_area_struct *vma = find_vma(mm, start_addr);
-
-       if (vma && end_addr <= vma->vm_start)
-               vma = NULL;
-       return vma;
-}
+extern struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
+                                                   unsigned long start_addr,
+                                                   unsigned long end_addr);
 
 /**
  * vma_lookup() - Find a VMA at a specific address

diff --git a/mm/mmap.c b/mm/mmap.c
index c080ea65215d42871c7aaa971862378bb4ef8a52..80ff8be0631b2529b075d48841761ba3e6851176 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2030,6 +2030,35 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 
 EXPORT_SYMBOL(get_unmapped_area);
 
+/**
+ * find_vma_intersection() - Look up the first VMA which intersects the interval
+ * @mm: The process address space.
+ * @start_addr: The inclusive start user address.
+ * @end_addr: The exclusive end user address.
+ *
+ * Returns: The first VMA within the provided range, %NULL otherwise.  Assumes
+ * start_addr < end_addr.
+ */
+struct vm_area_struct *find_vma_intersection(struct mm_struct *mm,
+                                            unsigned long start_addr,
+                                            unsigned long end_addr)
+{
+       struct vm_area_struct *vma;
+       unsigned long index = start_addr;
+
+       mmap_assert_locked(mm);
+       /* Check the cache first. */
+       vma = vmacache_find(mm, start_addr);
+       if (likely(vma))
+               return vma;
+
+       vma = mt_find(&mm->mm_mt, &index, end_addr - 1);
+       if (vma)
+               vmacache_update(start_addr, vma);
+       return vma;
+}
+EXPORT_SYMBOL(find_vma_intersection);
+
 /**
  * find_vma() - Find the VMA for a given address, or the next vma.
  * @mm: The mm_struct to check
@@ -2038,7 +2067,7 @@ EXPORT_SYMBOL(get_unmapped_area);
  * Returns: The VMA associated with addr, or the next vma.
  * May return %NULL in the case of no vma at addr or above.
  */
-struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+inline struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
 {
        struct vm_area_struct *vma;
        unsigned long index = addr;