task_mmu: Reduce excessive indentation in clear_refs_write

fs/proc/task_mmu.c

 #include <linux/mm.h>
 #include <linux/vmacache.h>
 #include <linux/hugetlb.h>
 #include <linux/huge_mm.h>
 #include <linux/mount.h>
 #include <linux/seq_file.h>
 #include <linux/highmem.h>
 #include <linux/ptrace.h>
 #include <linux/slab.h>
 #include <linux/pagemap.h>
@@ skipping 729 matching lines @@
  *    of page-shift in pagemap entries.
  */
 
 static bool soft_dirty_cleared __read_mostly;
 
 enum clear_refs_types {
         CLEAR_REFS_ALL = 1,
         CLEAR_REFS_ANON,
         CLEAR_REFS_MAPPED,
         CLEAR_REFS_SOFT_DIRTY,
+        CLEAR_REFS_MM_HIWATER_RSS,
         CLEAR_REFS_LAST,
 };
 
 struct clear_refs_private {
         struct vm_area_struct *vma;
         enum clear_refs_types type;
 };
 
 static inline void clear_soft_dirty(struct vm_area_struct *vma,
                 unsigned long addr, pte_t *pte)
@@ skipping 85 matching lines @@
                 soft_dirty_cleared = true;
                 pr_warn_once("The pagemap bits 55-60 has changed their meaning!"
                              " See the linux/Documentation/vm/pagemap.txt for "
                              "details.\n");
         }
 
         task = get_proc_task(file_inode(file));
         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) {
+        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) {
+                        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) {
-                                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;
+                                vma->vm_flags &= ~VM_SOFTDIRTY;
+                                vma_set_page_prot(vma);
                         }
-                        mmu_notifier_invalidate_range_start(mm, 0, -1);
+                        downgrade_write(&mm->mmap_sem);
+                        break;
                 }
-                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);
-                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;
 }
 
 const struct file_operations proc_clear_refs_operations = {
         .write          = clear_refs_write,
         .llseek         = noop_llseek,
 };
 
@@ skipping 693 matching lines @@
         .release        = proc_map_release,
 };
 
 const struct file_operations proc_tid_numa_maps_operations = {
         .open           = tid_numa_maps_open,
         .read           = seq_read,
         .llseek         = seq_lseek,
         .release        = proc_map_release,
 };
 #endif /* CONFIG_NUMA */