mm: add vma iterator to vma_adjust() arguments

Change the vma_adjust() function definition to accept the vma iterator and
pass it through to __vma_adjust().

Update fs/exec to use the new vma_adjust() function parameters.

Update mm/mremap to use the new vma_adjust() function parameters.

Revert the __split_vma() calls back from __vma_adjust() to vma_adjust()
and pass through the vma iterator.

Link: https://lkml.kernel.org/r/20230120162650.984577-37-Liam.Howlett@oracle.comSigned-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/exec.c

@@ -699,7 +699,7 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 	/*
 	 * cover the whole range: [new_start, old_end)
 	 */
-	if (vma_adjust(vma, new_start, old_end, vma->vm_pgoff, NULL))
+	if (vma_adjust(&vmi, vma, new_start, old_end, vma->vm_pgoff, NULL))
 		return -ENOMEM;
 
 	/*
@@ -731,12 +731,9 @@ static int shift_arg_pages(struct vm_area_struct *vma, unsigned long shift)
 	}
 	tlb_finish_mmu(&tlb);
 
-	/*
-	 * Shrink the vma to just the new range.  Always succeeds.
-	 */
-	vma_adjust(vma, new_start, new_end, vma->vm_pgoff, NULL);
-
-	return 0;
+	vma_prev(&vmi);
+	/* Shrink the vma to just the new range */
+	return vma_adjust(&vmi, vma, new_start, new_end, vma->vm_pgoff, NULL);
 }
 
 /*

include/linux/mm.h

@@ -2834,12 +2834,11 @@ extern int __vm_enough_memory(struct mm_struct *mm, long pages, int cap_sys_admi
 extern int __vma_adjust(struct vma_iterator *vmi, struct vm_area_struct *vma, unsigned long start,
 	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert,
 	struct vm_area_struct *expand);
-static inline int vma_adjust(struct vm_area_struct *vma, unsigned long start,
-	unsigned long end, pgoff_t pgoff, struct vm_area_struct *insert)
+static inline int vma_adjust(struct vma_iterator *vmi,
+	struct vm_area_struct *vma, unsigned long start, unsigned long end,
+	pgoff_t pgoff, struct vm_area_struct *insert)
 {
-	VMA_ITERATOR(vmi, vma->vm_mm, start);
-
-	return __vma_adjust(&vmi, vma, start, end, pgoff, insert, NULL);
+	return __vma_adjust(vmi, vma, start, end, pgoff, insert, NULL);
 }
 extern struct vm_area_struct *vma_merge(struct vma_iterator *vmi,
 	struct mm_struct *, struct vm_area_struct *prev, unsigned long addr,

mm/mmap.c

@@ -2210,12 +2210,12 @@ int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		new->vm_ops->open(new);
 
 	if (new_below)
-		err = __vma_adjust(vmi, vma, addr, vma->vm_end,
-		   vma->vm_pgoff + ((addr - new->vm_start) >> PAGE_SHIFT),
-		   new, NULL);
+		err = vma_adjust(vmi, vma, addr, vma->vm_end,
+			vma->vm_pgoff + ((addr - new->vm_start) >> PAGE_SHIFT),
+			new);
 	else
-		err = __vma_adjust(vmi, vma, vma->vm_start, addr, vma->vm_pgoff,
-				 new, NULL);
+		err = vma_adjust(vmi, vma, vma->vm_start, addr, vma->vm_pgoff,
+				 new);
 
 	/* Success. */
 	if (!err) {

mm/mremap.c

@@ -1047,8 +1047,8 @@ SYSCALL_DEFINE5(mremap, unsigned long, addr, unsigned long, old_len,
 					extension_end, vma->vm_flags, vma->anon_vma,
 					vma->vm_file, extension_pgoff, vma_policy(vma),
 					vma->vm_userfaultfd_ctx, anon_vma_name(vma));
-			} else if (vma_adjust(vma, vma->vm_start, addr + new_len,
-				   vma->vm_pgoff, NULL)) {
+			} else if (vma_adjust(&vmi, vma, vma->vm_start,
+					addr + new_len, vma->vm_pgoff, NULL)) {
 				vma = NULL;
 			}
 			if (!vma) {