[PATCH v4 09/21] mm/mmap: Expand mmap_region() munmap call

["Liam R. Howlett" <Liam.Howlett@oracle.com>]

From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>

Open code the do_vmi_align_munmap() call so that it can be broken up
later in the series.

Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
---
 mm/mmap.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/mm/mmap.c b/mm/mmap.c
index 49b3ab406353..a1544a68558e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2916,6 +2916,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	struct vm_area_struct *next, *prev, *merge;
 	pgoff_t pglen = len >> PAGE_SHIFT;
 	unsigned long charged = 0;
+	struct vma_munmap_struct vms;
+	struct ma_state mas_detach;
+	struct maple_tree mt_detach;
 	unsigned long end = addr + len;
 	unsigned long merge_start = addr, merge_end = end;
 	bool writable_file_mapping = false;
@@ -2948,10 +2951,27 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	/* Find the first overlapping VMA */
 	vma = vma_find(&vmi, end);
 	if (vma) {
-		/* Unmap any existing mapping in the area */
-		if (do_vmi_align_munmap(&vmi, vma, mm, addr, end, uf, false))
+		mt_init_flags(&mt_detach, vmi.mas.tree->ma_flags & MT_FLAGS_LOCK_MASK);
+		mt_on_stack(mt_detach);
+		mas_init(&mas_detach, &mt_detach, /* addr = */ 0);
+		init_vma_munmap(&vms, &vmi, vma, addr, end, uf, /* unlock = */ false);
+		/* Prepare to unmap any existing mapping in the area */
+		if (vms_gather_munmap_vmas(&vms, &mas_detach))
+			return -ENOMEM;
+
+		/* Remove any existing mappings from the vma tree */
+		if (vma_iter_clear_gfp(&vmi, addr, end, GFP_KERNEL))
 			return -ENOMEM;
+
+		/* Unmap any existing mapping in the area */
+		vms_complete_munmap_vmas(&vms, &mas_detach);
+		next = vms.next;
+		prev = vms.prev;
+		vma_prev(&vmi);
 		vma = NULL;
+	} else {
+		next = vma_next(&vmi);
+		prev = vma_prev(&vmi);
 	}
 
 	/*
@@ -2964,8 +2984,6 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		vm_flags |= VM_ACCOUNT;
 	}
 
-	next = vma_next(&vmi);
-	prev = vma_prev(&vmi);
 	if (vm_flags & VM_SPECIAL) {
 		if (prev)
 			vma_iter_next_range(&vmi);
-- 
2.43.0