mm/mmap: Add do_mas_munmap() and wraper for __do_munmap()

To avoid extra tree work, it is necessary to support passing in a maple state
to key functions.  Start this work with __do_munmap().

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

diff --git a/mm/mmap.c b/mm/mmap.c
index c0e65f6332876949681f9683a01e60a47fc9fa67..189796ffa70aa554e2e6aef352338dc1095258dd 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2463,34 +2463,24 @@ static inline int unlock_range(struct vm_area_struct *start,
 
        return count;
 }
-/* Munmap is split into 2 main parts -- this part which finds
- * what needs doing, and the areas themselves, which do the
- * work.  This now handles partial unmappings.
- * Jeremy Fitzhardinge <jeremy@goop.org>
+
+/* do_mas_align_munmap() - munmap the aligned region from @start to @end.
+ *
+ * @mas: The maple_state, ideally set up to alter the correct tree location.
+ * @vma: The starting vm_area_struct
+ * @mm: The mm_struct
+ * @start: The aligned start address to munmap.
+ * @end: The aligned end address to munmap.
+ * @uf: The userfaultfd list_head
+ * @downgrade: Set to true to attempt a downwrite of the mmap_sem
+ *
+ *
  */
-int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
-               struct list_head *uf, bool downgrade)
+int do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
+                       struct mm_struct *mm, unsigned long start,
+                       unsigned long end, struct list_head *uf, bool downgrade)
 {
-       unsigned long end;
-       struct vm_area_struct *vma, *prev, *last;
-       MA_STATE(mas, &mm->mm_mt, start, start);
-
-       if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
-               return -EINVAL;
-
-       end = start + PAGE_ALIGN(len);
-       if (end == start)
-               return -EINVAL;
-
-        /* arch_unmap() might do unmaps itself.  */
-       arch_unmap(mm, start, end);
-
-       /* Find the first overlapping VMA */
-       vma = mas_find(&mas, end - 1);
-       if (!vma)
-               return 0;
-
-       mas.last = end - 1;
+       struct vm_area_struct *prev, *last;
        /* we have start < vma->vm_end  */
 
        /*
@@ -2515,8 +2505,8 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
                        return error;
                prev = vma;
                vma = vma_next(mm, prev);
-               mas.index = start;
-               mas_reset(&mas);
+               mas->index = start;
+               mas_reset(mas);
        } else {
                prev = vma->vm_prev;
        }
@@ -2532,7 +2522,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
                if (error)
                        return error;
                vma = vma_next(mm, prev);
-               mas_reset(&mas);
+               mas_reset(mas);
        }
 
 
@@ -2559,7 +2549,7 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
         */
        mm->map_count -= unlock_range(vma, &last, end);
        /* Drop removed area from the tree */
-       mas_store_gfp(&mas, NULL, GFP_KERNEL);
+       mas_store_gfp(mas, NULL, GFP_KERNEL);
 
        /* Detach vmas from the MM linked list */
        vma->vm_prev = NULL;
@@ -2596,6 +2586,59 @@ int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
        return downgrade ? 1 : 0;
 }
 
+/*
+ * do_mas_munmap() - munmap a given range.
+ * @mas: The maple state
+ * @mm: The mm_struct
+ * @start: The start address to munmap
+ * @len: The length of the range to munmap
+ * @uf: The userfaultfd list_head
+ * @downgrade: set to true if the user wants to attempt to write_downgrade the
+ * mmap_sem
+ *
+ * This function takes a @mas that is in the correct state to remove the
+ * mapping(s).  The @len will be aligned and any arch_unmap work will be
+ * preformed.
+ */
+int do_mas_munmap(struct ma_state *mas, struct mm_struct *mm,
+                 unsigned long start, size_t len, struct list_head *uf,
+                 bool downgrade)
+{
+       unsigned long end;
+       struct vm_area_struct *vma;
+
+       if ((offset_in_page(start)) || start > TASK_SIZE || len > TASK_SIZE-start)
+               return -EINVAL;
+
+       end = start + PAGE_ALIGN(len);
+       if (end == start)
+               return -EINVAL;
+
+        /* arch_unmap() might do unmaps itself.  */
+       arch_unmap(mm, start, end);
+
+       /* Find the first overlapping VMA */
+       vma = mas_find(mas, end - 1);
+       if (!vma)
+               return 0;
+
+       mas->last = end - 1;
+       return do_mas_align_munmap(mas, vma, mm, start, end, uf, downgrade);
+}
+
+int __do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
+               struct list_head *uf, bool downgrade)
+{
+       MA_STATE(mas, &mm->mm_mt, start, start);
+       return do_mas_munmap(&mas, mm, start, len, uf, downgrade);
+}
+
+/* do_munmap() - Wrapper function for non-maple tree aware do_munmap() calls.
+ * @mm: The mm_struct
+ * @start: The start address to munmap
+ * @len: The length to be munmapped.
+ * @uf: The userfaultfd list_head
+ */
 int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
              struct list_head *uf)
 {
@@ -2633,7 +2676,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
        }
 
        /* Unmap any existing mapping in the area */
-       if (do_munmap(mm, addr, len, uf))
+       if (do_mas_munmap(&mas, mm, addr, len, uf, false))
                return -ENOMEM;
 
        /*
@@ -3005,7 +3048,7 @@ static int do_brk_munmap(struct ma_state *mas, struct vm_area_struct *vma,
                mas_set(mas, newbrk);
                if (vma->vm_start != newbrk)
                        mas_reset(mas); // cause a re-walk for the first overlap.
-               ret = __do_munmap(mm, newbrk, oldbrk - newbrk, uf, true);
+               ret = do_mas_munmap(mas, mm, newbrk, oldbrk-newbrk, uf, true);
                goto munmap_full_vma;
        }