task_mmu: Reduce excessive indentation in clear_refs_write

fs/proc/task_mmu.c

Index: fs/proc/task_mmu.c
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 246eae84b13b1be4bf36bdf48fe50b178a9cb407..7967535f7e27791cb2f5eaad4a55b2e9d03b231b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -747,6 +747,7 @@ enum clear_refs_types {
 	CLEAR_REFS_ANON,
 	CLEAR_REFS_MAPPED,
 	CLEAR_REFS_SOFT_DIRTY,
+	CLEAR_REFS_MM_HIWATER_RSS,
 	CLEAR_REFS_LAST,
 };
 
@@ -852,59 +853,73 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
 	if (!task)
 		return -ESRCH;
 	mm = get_task_mm(task);
-	if (mm) {
-		struct clear_refs_private cp = {
-			.type = type,
-		};
-		struct mm_walk clear_refs_walk = {
-			.pmd_entry = clear_refs_pte_range,
-			.mm = mm,
-			.private = &cp,
-		};
-		down_read(&mm->mmap_sem);
-		if (type == CLEAR_REFS_SOFT_DIRTY) {
-			for (vma = mm->mmap; vma; vma = vma->vm_next) {
-				if (!(vma->vm_flags & VM_SOFTDIRTY))
-					continue;
-				up_read(&mm->mmap_sem);
-				down_write(&mm->mmap_sem);
-				for (vma = mm->mmap; vma; vma = vma->vm_next) {
-					vma->vm_flags &= ~VM_SOFTDIRTY;
-					vma_set_page_prot(vma);
-				}
-				downgrade_write(&mm->mmap_sem);
-				break;
-			}
-			mmu_notifier_invalidate_range_start(mm, 0, -1);
-		}
+	if (!mm)
+		goto out_task;
+
+	if (type == CLEAR_REFS_MM_HIWATER_RSS) {
+		/*
+		 * Writing 5 to /proc/pid/clear_refs resets the peak resident
+		 * set size.
+		 */
+		down_write(&mm->mmap_sem);
+		reset_mm_hiwater_rss(mm);
+		up_write(&mm->mmap_sem);
+		goto out_mm;
+	}
+
+	struct clear_refs_private cp = {
+		.type = type,
+	};
+	struct mm_walk clear_refs_walk = {
+		.pmd_entry = clear_refs_pte_range,
+		.mm = mm,
+		.private = &cp,
+	};
+	down_read(&mm->mmap_sem);
+	if (type == CLEAR_REFS_SOFT_DIRTY) {
 		for (vma = mm->mmap; vma; vma = vma->vm_next) {
-			cp.vma = vma;
-			if (is_vm_hugetlb_page(vma))
+			if (!(vma->vm_flags & VM_SOFTDIRTY))
 				continue;
-			/*
-			 * Writing 1 to /proc/pid/clear_refs affects all pages.
-			 *
-			 * Writing 2 to /proc/pid/clear_refs only affects
-			 * Anonymous pages.
-			 *
-			 * Writing 3 to /proc/pid/clear_refs only affects file
-			 * mapped pages.
-			 *
-			 * Writing 4 to /proc/pid/clear_refs affects all pages.
-			 */
-			if (type == CLEAR_REFS_ANON && vma->vm_file)
-				continue;
-			if (type == CLEAR_REFS_MAPPED && !vma->vm_file)
-				continue;
-			walk_page_range(vma->vm_start, vma->vm_end,
-					&clear_refs_walk);
+			up_read(&mm->mmap_sem);
+			down_write(&mm->mmap_sem);
+			for (vma = mm->mmap; vma; vma = vma->vm_next) {
+				vma->vm_flags &= ~VM_SOFTDIRTY;
+				vma_set_page_prot(vma);
+			}
+			downgrade_write(&mm->mmap_sem);
+			break;
 		}
-		if (type == CLEAR_REFS_SOFT_DIRTY)
-			mmu_notifier_invalidate_range_end(mm, 0, -1);
-		flush_tlb_mm(mm);
-		up_read(&mm->mmap_sem);
-		mmput(mm);
+		mmu_notifier_invalidate_range_start(mm, 0, -1);
 	}
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		cp.vma = vma;
+		if (is_vm_hugetlb_page(vma))
+			continue;
+		/*
+		 * Writing 1 to /proc/pid/clear_refs affects all pages.
+		 *
+		 * Writing 2 to /proc/pid/clear_refs only affects anonymous
+		 * pages.
+		 *
+		 * Writing 3 to /proc/pid/clear_refs only affects file mapped
+		 * pages.
+		 *
+		 * Writing 4 to /proc/pid/clear_refs affects all pages.
+		 */
+		if (type == CLEAR_REFS_ANON && vma->vm_file)
+			continue;
+		if (type == CLEAR_REFS_MAPPED && !vma->vm_file)
+			continue;
+		walk_page_range(vma->vm_start, vma->vm_end, &clear_refs_walk);
+	}
+	if (type == CLEAR_REFS_SOFT_DIRTY)
+		mmu_notifier_invalidate_range_end(mm, 0, -1);
+	flush_tlb_mm(mm);
+	up_read(&mm->mmap_sem);
+
+out_mm:
+	mmput(mm);
+out_task:
 	put_task_struct(task);
 
 	return count;