mm: Use maple tree operations for find_vma_intersection() and find_vma()

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.  This means the find_vma() call changes to a special
case of the find_vma_intersection().

Exported 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 10a997fb60dc313c3324e61d3c391d5cdb105492..21f2f6dbea64d4fd02b4cf0e4eef52ea42333dac 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2679,26 +2679,13 @@ 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 9764e1ce63e9c244d7ed11e577a4d537340bfbdd..abe232fe1e0ed461c8681867f71df144b42e5bb7 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2028,32 +2028,50 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
 EXPORT_SYMBOL(get_unmapped_area);
 
 /**
- * find_vma() - Find the VMA for a given address, or the next vma.
- * @mm: The mm_struct to check
- * @addr: The address
+ * 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 VMA associated with addr, or the next vma.
- * May return %NULL in the case of no vma at addr or above.
+ * Returns: The first VMA within the provided range, %NULL otherwise.  Assumes
+ * start_addr < end_addr.
  */
-struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long 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;
-       MA_STATE(mas, &mm->mm_mt, addr, addr);
+       MA_STATE(mas, &mm->mm_mt, start_addr, start_addr);
 
        mmap_assert_locked(mm);
        /* Check the cache first. */
-       vma = vmacache_find(mm, addr);
+       vma = vmacache_find(mm, start_addr);
        if (likely(vma))
                return vma;
 
        rcu_read_lock();
-       vma = mas_find(&mas, -1);
+       vma = mas_find(&mas, end_addr - 1);
        rcu_read_unlock();
        if (vma)
-               vmacache_update(addr, vma);
+               vmacache_update(mas.index, 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
+ * @addr: The address
+ *
+ * Returns: The VMA associated with addr, or the next vma.
+ * May return NULL in the case of no vma at addr or above.
+ */
+inline struct vm_area_struct *find_vma(struct mm_struct *mm, unsigned long addr)
+{
+       // Note find_vma_intersection will decrease 0 to underflow to ULONG_MAX
+       return find_vma_intersection(mm, addr, 0);
+}
 EXPORT_SYMBOL(find_vma);
 
 /**